5:02 a.m.
Yet some issues, but ...
changes in v2:
* Fixed build warnings
* Moved ARM64_NEW_VMEMMAP to machdep->flags
* Show additional kaslr-related parameters in arm64_dump_machdep_table()
* Handle a VMCOREINFO, "NUMBER(kimage_voffset)"
===8<===
From 080a54ec232ac48ef2d8123cbedcf0f1fe27e391 Mon Sep 17 00:00:00 2001
From: AKASHI Takahiro <takahiro.akashi(a)linaro.org>
Date: Mon, 16 May 2016 17:31:55 +0900
Subject: [PATCH v2] arm64: fix kernel memory map handling for kaslr-enabled
kernel
In kernel v4.6, Kernel ASLR (KASLR) is supported on arm64, and the start
address of the kernel image can be randomized if CONFIG_RANDOMIZE_BASE is
enabled.
Even worse, the kernel image is no more mapped in the linear mapping, but
in vmalloc area (i.e. below PAGE_OFFSET).
Now, according to the kernel's memory.h, converting a virtual address to
a physical address should be done like below:
phys_addr_t __x = (phys_addr_t)(x); \
__x & BIT(VA_BITS - 1) ? (__x & ~PAGE_OFFSET) + PHYS_OFFSET : \
(__x - kimage_voffset); })
Please note that PHYS_OFFSET is no more equal to the start address of
the first usable memory block in SYSTEM RAM due to the fact mentioned
above.
This patch addresses this change and allows the crash utility to access
memory contents with correct addresses.
*However*, it is still rough-edged and we need more refinements.
1-1) On a live system, crash with this patch won't work because
we currently have no way to know kimage_voffset.
1-2) For a core dump file, we can do simply:
$ crash <vmlinux> <vmcore>
as long as the file has "NUMBER(kimage_voffset)"
(RELOC_AUTO|KASLR is automatically set.)
I'm planning to add this enhancement in my next version of kexec/kdump
patch, i.e. v17.
2) My current change breaks the backward compatibility.
Crash won't work with v4.5 or early kernel partly because I changed
the calculation of VA_BITS. (I think that the existing code is wrong.)
So far I don't have enough time to look into this issue as I'm focusing
on KASLR support.
3) Backtracing a 'panic'ed task fails:
crash> bt
PID: 999 TASK: ffffffe960081800 CPU: 0 COMMAND: "sh"
bt: WARNING: corrupt prstatus? pstate=0x80000000, but no user frame found
bt: WARNING: cannot determine starting stack frame for task ffffffe960081800
frame->pc indicates that it is a kernel address, so obviously something
is wrong. I'm diggin into it.
Signed-off-by: AKASHI Takahiro <takahiro.akashi(a)linaro.org>
---
arm64.c | 217 ++++++++++++++++++++++++++++++++++++++++++++++++--------------
defs.h | 24 +++++--
main.c | 7 +-
symbols.c | 10 +--
4 files changed, 196 insertions(+), 62 deletions(-)
diff --git a/arm64.c b/arm64.c
index 34c8c59..6b97093 100644
--- a/arm64.c
+++ b/arm64.c
@@ -72,6 +72,21 @@ static int arm64_get_crash_notes(void);
static void arm64_calc_VA_BITS(void);
static int arm64_is_uvaddr(ulong, struct task_context *);
+ulong
+arm64_VTOP(ulong addr)
+{
+ if (!(machdep->flags & NEW_VMEMMAP) ||
+ (addr >= machdep->machspec->page_offset)) {
+ return machdep->machspec->phys_offset
+ + (addr - machdep->machspec->page_offset);
+ } else {
+ if (machdep->machspec->kimage_voffset)
+ return addr - machdep->machspec->kimage_voffset;
+ else /* no randomness */
+ return machdep->machspec->phys_offset
+ + (addr - machdep->machspec->vmalloc_start_addr);
+ }
+}
/*
* Do all necessary machine-specific setup here. This is called several times
@@ -81,6 +96,7 @@ void
arm64_init(int when)
{
ulong value;
+ char *string;
struct machine_specific *ms;
#if defined(__x86_64__)
@@ -102,9 +118,34 @@ arm64_init(int when)
if (machdep->cmdline_args[0])
arm64_parse_cmdline_args();
machdep->flags |= MACHDEP_BT_TEXT;
+
+ ms = machdep->machspec;
+ if (!ms->kimage_voffset &&
+ (string = pc->read_vmcoreinfo("NUMBER(kimage_voffset)"))) {
+ ms->kimage_voffset = htol(string, QUIET, NULL);
+ free(string);
+ }
+
+ if (ms->kimage_voffset) {
+ machdep->flags |= NEW_VMEMMAP;
+
+ /* if not specified in command line */
+ if (!kt->relocate && !(kt->flags2 & (RELOC_AUTO|KASLR)))
+ kt->flags2 |= (RELOC_AUTO|KASLR);
+ }
+
break;
case PRE_GDB:
+ /* This check is somewhat redundant */
+ if (kernel_symbol_exists("kimage_voffset")) {
+ machdep->flags |= NEW_VMEMMAP;
+
+ if (!machdep->machspec->kimage_voffset)
+ error(WARNING,
+ "kimage_voffset not identified for kaslr kernel\n");
+ }
+
if (!machdep->pagesize) {
/*
* Kerneldoc Documentation/arm64/booting.txt describes
@@ -160,16 +201,35 @@ arm64_init(int when)
machdep->pagemask = ~((ulonglong)machdep->pageoffset);
arm64_calc_VA_BITS();
- machdep->machspec->page_offset = ARM64_PAGE_OFFSET;
+ ms = machdep->machspec;
+ ms->page_offset = ARM64_PAGE_OFFSET;
+ /* FIXME: idmap for NEW_VMEMMAP */
machdep->identity_map_base = ARM64_PAGE_OFFSET;
- machdep->machspec->userspace_top = ARM64_USERSPACE_TOP;
- machdep->machspec->modules_vaddr = ARM64_MODULES_VADDR;
- machdep->machspec->modules_end = ARM64_MODULES_END;
- machdep->machspec->vmalloc_start_addr = ARM64_VMALLOC_START;
- machdep->machspec->vmalloc_end = ARM64_VMALLOC_END;
- machdep->kvbase = ARM64_VMALLOC_START;
- machdep->machspec->vmemmap_vaddr = ARM64_VMEMMAP_VADDR;
- machdep->machspec->vmemmap_end = ARM64_VMEMMAP_END;
+ machdep->kvbase = ARM64_VA_START;
+ ms->userspace_top = ARM64_USERSPACE_TOP;
+ if (machdep->flags & NEW_VMEMMAP) {
+ struct syment *sp;
+
+ sp = kernel_symbol_search("_text");
+ ms->kimage_text = (sp ? sp->value : 0);
+ sp = kernel_symbol_search("_end");
+ ms->kimage_end = (sp ? sp->value : 0);
+
+ ms->modules_vaddr = ARM64_VA_START;
+ if (kernel_symbol_exists("kasan_init"))
+ ms->modules_vaddr += ARM64_KASAN_SHADOW_SIZE;
+ ms->modules_end = ms->modules_vaddr
+ + ARM64_MODULES_VSIZE -1;
+
+ ms->vmalloc_start_addr = ms->modules_end + 1;
+ } else {
+ ms->modules_vaddr = ARM64_PAGE_OFFSET - MEGABYTES(64);
+ ms->modules_end = ARM64_PAGE_OFFSET - 1;
+ ms->vmalloc_start_addr = ARM64_VA_START;
+ }
+ ms->vmalloc_end = ARM64_VMALLOC_END;
+ ms->vmemmap_vaddr = ARM64_VMEMMAP_VADDR;
+ ms->vmemmap_end = ARM64_VMEMMAP_END;
switch (machdep->pagesize)
{
@@ -232,8 +292,6 @@ arm64_init(int when)
machdep->stacksize = ARM64_STACK_SIZE;
machdep->flags |= VMEMMAP;
- arm64_calc_phys_offset();
-
machdep->uvtop = arm64_uvtop;
machdep->kvtop = arm64_kvtop;
machdep->is_kvaddr = generic_is_kvaddr;
@@ -262,6 +320,10 @@ arm64_init(int when)
machdep->dumpfile_init = NULL;
machdep->verify_line_number = NULL;
machdep->init_kernel_pgd = arm64_init_kernel_pgd;
+
+ /* use machdep parameters */
+ arm64_calc_phys_offset();
+
break;
case POST_GDB:
@@ -409,6 +471,8 @@ arm64_dump_machdep_table(ulong arg)
fprintf(fp, "%sIRQ_STACKS", others++ ? "|" : "");
if (machdep->flags & MACHDEP_BT_TEXT)
fprintf(fp, "%sMACHDEP_BT_TEXT", others++ ? "|" : "");
+ if (machdep->flags & NEW_VMEMMAP)
+ fprintf(fp, "%sNEW_VMEMMAP", others++ ? "|" : "");
fprintf(fp, ")\n");
fprintf(fp, " kvbase: %lx\n", machdep->kvbase);
@@ -494,6 +558,8 @@ arm64_dump_machdep_table(ulong arg)
ms = machdep->machspec;
fprintf(fp, " machspec: %lx\n", (ulong)ms);
+ fprintf(fp, " memory map layout: %s\n",
+ (machdep->flags & NEW_VMEMMAP) ? "new" : "old");
fprintf(fp, " VA_BITS: %ld\n", ms->VA_BITS);
fprintf(fp, " userspace_top: %016lx\n", ms->userspace_top);
fprintf(fp, " page_offset: %016lx\n", ms->page_offset);
@@ -503,6 +569,11 @@ arm64_dump_machdep_table(ulong arg)
fprintf(fp, " modules_end: %016lx\n", ms->modules_end);
fprintf(fp, " vmemmap_vaddr: %016lx\n", ms->vmemmap_vaddr);
fprintf(fp, " vmemmap_end: %016lx\n", ms->vmemmap_end);
+ if (machdep->flags & NEW_VMEMMAP) {
+ fprintf(fp, " kimage_text: %016lx\n", ms->kimage_text);
+ fprintf(fp, " kimage_end: %016lx\n", ms->kimage_end);
+ fprintf(fp, " kimage_voffset: %016lx\n", ms->kimage_voffset);
+ }
fprintf(fp, " phys_offset: %lx\n", ms->phys_offset);
fprintf(fp, "__exception_text_start: %lx\n", ms->__exception_text_start);
fprintf(fp, " __exception_text_end: %lx\n", ms->__exception_text_end);
@@ -543,6 +614,42 @@ arm64_dump_machdep_table(ulong arg)
}
}
+static int
+arm64_parse_machdep_arg_l(char *argstring, char *param, ulong *value)
+{
+ int len;
+ int megabytes = FALSE;
+ char *p;
+
+ len = strlen(param);
+ if (!STRNEQ(argstring, param) || (argstring[len] != '='))
+ return FALSE;
+
+ if ((LASTCHAR(argstring) == 'm') ||
+ (LASTCHAR(argstring) == 'M')) {
+ LASTCHAR(argstring) = NULLCHAR;
+ megabytes = TRUE;
+ }
+
+ p = argstring + len + 1;
+ if (strlen(p)) {
+ int flags = RETURN_ON_ERROR | QUIET;
+ int err = 0;
+
+ if (megabytes) {
+ *value = dtol(p, flags, &err);
+ if (!err)
+ *value = MEGABYTES(*value);
+ } else {
+ *value = htol(p, flags, &err);
+ }
+
+ if (!err)
+ return TRUE;
+ }
+
+ return FALSE;
+}
/*
* Parse machine dependent command line arguments.
@@ -554,11 +661,10 @@ arm64_dump_machdep_table(ulong arg)
static void
arm64_parse_cmdline_args(void)
{
- int index, i, c, err;
+ int index, i, c;
char *arglist[MAXARGS];
char buf[BUFSIZE];
char *p;
- ulong value = 0;
for (index = 0; index < MAX_MACHDEP_ARGS; index++) {
if (!machdep->cmdline_args[index])
@@ -580,39 +686,23 @@ arm64_parse_cmdline_args(void)
c = parse_line(buf, arglist);
for (i = 0; i < c; i++) {
- err = 0;
-
- if (STRNEQ(arglist[i], "phys_offset=")) {
- int megabytes = FALSE;
- int flags = RETURN_ON_ERROR | QUIET;
-
- if ((LASTCHAR(arglist[i]) == 'm') ||
- (LASTCHAR(arglist[i]) == 'M')) {
- LASTCHAR(arglist[i]) = NULLCHAR;
- megabytes = TRUE;
- }
-
- p = arglist[i] + strlen("phys_offset=");
- if (strlen(p)) {
- if (megabytes)
- value = dtol(p, flags, &err);
- else
- value = htol(p, flags, &err);
- }
-
- if (!err) {
- if (megabytes)
- value = MEGABYTES(value);
-
- machdep->machspec->phys_offset = value;
-
- error(NOTE,
- "setting phys_offset to: 0x%lx\n\n",
- machdep->machspec->phys_offset);
+ if (arm64_parse_machdep_arg_l(arglist[i],
+ "phys_offset",
+ &machdep->machspec->phys_offset)) {
+ error(NOTE,
+ "setting phys_offset to: 0x%lx\n\n",
+ machdep->machspec->phys_offset);
+
+ machdep->flags |= PHYS_OFFSET;
+ continue;
+ } else if (arm64_parse_machdep_arg_l(arglist[i],
+ "kimage_voffset",
+ &machdep->machspec->kimage_voffset)) {
+ error(NOTE,
+ "setting kimage_voffset to: 0x%lx\n\n",
+ machdep->machspec->kimage_voffset);
- machdep->flags |= PHYS_OFFSET;
- continue;
- }
+ continue;
}
error(WARNING, "ignoring --machdep option: %s\n",
@@ -627,10 +717,20 @@ arm64_calc_phys_offset(void)
{
struct machine_specific *ms = machdep->machspec;
ulong phys_offset;
+ struct syment *sp;
+ ulong value;
if (machdep->flags & PHYS_OFFSET) /* --machdep override */
return;
+ sp = kernel_symbol_search("memstart_addr");
+ if (sp && readmem(sp->value, KVADDR, (char *)&value, sizeof(value),
+ "memstart_addr", QUIET|RETURN_ON_ERROR)) {
+ ms->phys_offset = value;
+ machdep->flags |= PHYS_OFFSET;
+ return;
+ }
+
/*
* Next determine suitable value for phys_offset. User can override this
* by passing valid '--machdep phys_offset=<addr>' option.
@@ -2377,6 +2477,11 @@ arm64_IS_VMALLOC_ADDR(ulong vaddr)
{
struct machine_specific *ms = machdep->machspec;
+ if ((machdep->flags & NEW_VMEMMAP) &&
+ (vaddr >= machdep->machspec->kimage_text) &&
+ (vaddr <= machdep->machspec->kimage_end))
+ return FALSE;
+
return ((vaddr >= ms->vmalloc_start_addr && vaddr <=
ms->vmalloc_end) ||
((machdep->flags & VMEMMAP) &&
(vaddr >= ms->vmemmap_vaddr && vaddr <=
ms->vmemmap_end)) ||
@@ -2407,7 +2512,11 @@ arm64_calc_VA_BITS(void)
for (bitval = highest_bit_long(value); bitval; bitval--) {
if ((value & (1UL << bitval)) == 0) {
+#if 1
+ machdep->machspec->VA_BITS = bitval + 1;
+#else /* FIXME: bug? */
machdep->machspec->VA_BITS = bitval + 2;
+#endif
break;
}
}
@@ -2459,10 +2568,22 @@ arm64_calc_virtual_memory_ranges(void)
break;
}
- vmemmap_size = ALIGN((1UL << (ms->VA_BITS - machdep->pageshift)) *
SIZE(page), PUD_SIZE);
+ if (machdep->flags & NEW_VMEMMAP)
+#define STRUCT_PAGE_MAX_SHIFT 6
+ vmemmap_size = 1UL << (ms->VA_BITS - machdep->pageshift - 1
+ + STRUCT_PAGE_MAX_SHIFT);
+ else
+ vmemmap_size = ALIGN((1UL << (ms->VA_BITS - machdep->pageshift)) *
SIZE(page), PUD_SIZE);
+
vmalloc_end = (ms->page_offset - PUD_SIZE - vmemmap_size - SZ_64K);
- vmemmap_start = vmalloc_end + SZ_64K;
- vmemmap_end = vmemmap_start + vmemmap_size;
+
+ if (machdep->flags & NEW_VMEMMAP) {
+ vmemmap_start = ms->page_offset - vmemmap_size;
+ vmemmap_end = ms->page_offset;
+ } else {
+ vmemmap_start = vmalloc_end + SZ_64K;
+ vmemmap_end = vmemmap_start + vmemmap_size;
+ }
ms->vmalloc_end = vmalloc_end - 1;
ms->vmemmap_vaddr = vmemmap_start;
diff --git a/defs.h b/defs.h
index a09fa9a..2bbb55b 100644
--- a/defs.h
+++ b/defs.h
@@ -2844,8 +2844,8 @@ typedef u64 pte_t;
#define PTOV(X) \
((unsigned
long)(X)-(machdep->machspec->phys_offset)+(machdep->machspec->page_offset))
-#define VTOP(X) \
- ((unsigned
long)(X)-(machdep->machspec->page_offset)+(machdep->machspec->phys_offset))
+
+#define VTOP(X) arm64_VTOP((ulong)(X))
#define USERSPACE_TOP (machdep->machspec->userspace_top)
#define PAGE_OFFSET (machdep->machspec->page_offset)
@@ -2938,18 +2938,23 @@ typedef signed int s32;
#define VM_L3_4K (0x10)
#define KDUMP_ENABLED (0x20)
#define IRQ_STACKS (0x40)
+#define NEW_VMEMMAP (0x80)
/*
* sources: Documentation/arm64/memory.txt
* arch/arm64/include/asm/memory.h
* arch/arm64/include/asm/pgtable.h
*/
-
-#define ARM64_PAGE_OFFSET ((0xffffffffffffffffUL) <<
(machdep->machspec->VA_BITS - 1))
+#define ARM64_VA_START ((0xffffffffffffffffUL) \
+ << machdep->machspec->VA_BITS)
+#define ARM64_PAGE_OFFSET ((0xffffffffffffffffUL) \
+ << (machdep->machspec->VA_BITS - 1))
#define ARM64_USERSPACE_TOP ((1UL) << machdep->machspec->VA_BITS)
-#define ARM64_MODULES_VADDR (ARM64_PAGE_OFFSET - MEGABYTES(64))
-#define ARM64_MODULES_END (ARM64_PAGE_OFFSET - 1)
-#define ARM64_VMALLOC_START ((0xffffffffffffffffUL) <<
machdep->machspec->VA_BITS)
+
+/* only used for v4.6 or later */
+#define ARM64_MODULES_VSIZE MEGABYTES(128)
+#define ARM64_KASAN_SHADOW_SIZE (1UL << (machdep->machspec->VA_BITS - 3))
+
/*
* The following 3 definitions are the original values, but are obsolete
* for 3.17 and later kernels because they are now build-time calculations.
@@ -3028,6 +3033,10 @@ struct machine_specific {
ulong kernel_flags;
ulong irq_stack_size;
ulong *irq_stacks;
+ /* only needed for kaslr-enabled kernel */
+ ulong kimage_voffset;
+ ulong kimage_text;
+ ulong kimage_end;
};
struct arm64_stackframe {
@@ -5385,6 +5394,7 @@ void unwind_backtrace(struct bt_info *);
#ifdef ARM64
void arm64_init(int);
void arm64_dump_machdep_table(ulong);
+ulong arm64_VTOP(ulong);
int arm64_IS_VMALLOC_ADDR(ulong);
ulong arm64_swp_type(ulong);
ulong arm64_swp_offset(ulong);
diff --git a/main.c b/main.c
index 821bb4e..3f24908 100644
--- a/main.c
+++ b/main.c
@@ -227,9 +227,10 @@ main(int argc, char **argv)
optarg);
}
} else if (STREQ(long_options[option_index].name, "kaslr")) {
- if (!machine_type("X86_64"))
- error(INFO, "--kaslr only valid "
- "with X86_64 machine type.\n");
+ if (!machine_type("X86_64") &&
+ !machine_type("ARM64"))
+ error(INFO, "--kaslr not valid "
+ "with this machine type.\n");
else if (STREQ(optarg, "auto"))
kt->flags2 |= (RELOC_AUTO|KASLR);
else {
diff --git a/symbols.c b/symbols.c
index a8d3563..df27793 100644
--- a/symbols.c
+++ b/symbols.c
@@ -593,7 +593,8 @@ kaslr_init(void)
{
char *string;
- if (!machine_type("X86_64") || (kt->flags & RELOC_SET))
+ if ((!machine_type("X86_64") && !machine_type("ARM64")) ||
+ (kt->flags & RELOC_SET))
return;
/*
@@ -712,7 +713,7 @@ store_symbols(bfd *abfd, int dynamic, void *minisyms, long symcount,
if (machine_type("X86")) {
if (!(kt->flags & RELOC_SET))
kt->flags |= RELOC_FORCE;
- } else if (machine_type("X86_64")) {
+ } else if (machine_type("X86_64") || machine_type("ARM64")) {
if ((kt->flags2 & RELOC_AUTO) && !(kt->flags & RELOC_SET))
derive_kaslr_offset(abfd, dynamic, from,
fromend, size, store);
@@ -783,7 +784,8 @@ store_sysmap_symbols(void)
error(FATAL, "symbol table namespace malloc: %s\n",
strerror(errno));
- if (!machine_type("X86") && !machine_type("X86_64"))
+ if (!machine_type("X86") && !machine_type("X86_64")
&&
+ !machine_type("ARM64"))
kt->flags &= ~RELOC_SET;
first = 0;
@@ -4681,7 +4683,7 @@ value_search(ulong value, ulong *offset)
if ((sp = machdep->value_to_symbol(value, offset)))
return sp;
- if (IS_VMALLOC_ADDR(value))
+ if (IS_VMALLOC_ADDR(value))
goto check_modules;
if ((sp = symval_hash_search(value)) == NULL)
--
2.8.1
12:59 p.m.
----- Original Message -----
Yet some issues, but ...
Hi Takahiro,
Here are my general comments on my testing of the v2 patch, followed
by a few comments in the patch itself.
First, the combination of the new memory map layout and KASLR is somewhat
confusing. I am testing your patch on a 4.6.0-0.rc7.git2.1.fc25 kernel
that has this configuration:
config-arm64:# CONFIG_RANDOMIZE_BASE is not set
So KASLR doesn't really enter into the picture. But when bringing
up the crash session, it shows the "kaslr kernel" WARNING:
# ./crash
crash 7.1.5++
Copyright (C) 2002-2016 Red Hat, Inc.
Copyright (C) 2004, 2005, 2006, 2010 IBM Corporation
Copyright (C) 1999-2006 Hewlett-Packard Co
Copyright (C) 2005, 2006, 2011, 2012 Fujitsu Limited
Copyright (C) 2006, 2007 VA Linux Systems Japan K.K.
Copyright (C) 2005, 2011 NEC Corporation
Copyright (C) 1999, 2002, 2007 Silicon Graphics, Inc.
Copyright (C) 1999, 2000, 2001, 2002 Mission Critical Linux, Inc.
This program is free software, covered by the GNU General Public License,
and you are welcome to change it and/or distribute copies of it under
certain conditions. Enter "help copying" to see the conditions.
This program has absolutely no warranty. Enter "help warranty" for details.
WARNING: kimage_voffset not identified for kaslr kernel
GNU gdb (GDB) 7.6
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "aarch64-unknown-linux-gnu"...
KERNEL: /usr/lib/debug/lib/modules/4.6.0-0.rc7.git2.1.fc25.aarch64/vmlinux
DUMPFILE: /dev/crash
CPUS: 8
DATE: Tue May 24 10:08:08 2016
UPTIME: 11 days, 18:32:41
LOAD AVERAGE: 0.17, 0.09, 0.12
TASKS: 197
NODENAME: apm-mustang-ev3-36.khw.lab.eng.bos.redhat.com
RELEASE: 4.6.0-0.rc7.git2.1.fc25.aarch64
VERSION: #1 SMP Thu May 12 13:28:43 UTC 2016
MACHINE: aarch64 (unknown Mhz)
MEMORY: 16 GB
PID: 7556
COMMAND: "crash"
TASK: fffffe00beb45400 [THREAD_INFO: fffffe00beb98000]
CPU: 7
STATE: TASK_RUNNING (ACTIVE)
crash>
Why show that WARNING in this case? I understant that it's not
stashed during early initialization:
crash> help -m
flags: 104000c5
(KSYMS_START|VM_L2_64K|VMEMMAP|IRQ_STACKS|MACHDEP_BT_TEXT|NEW_VMEMMAP)
... [ cut ] ...
memory map layout: new <--- BTW, this is redundant/not-a-member, and
we've got NEW_VMEMMAP
VA_BITS: 42
userspace_top: 0000040000000000
page_offset: fffffe0000000000
vmalloc_start_addr: fffffc0008000000
vmalloc_end: fffffdff5ffeffff
modules_vaddr: fffffc0000000000
modules_end: fffffc0007ffffff
vmemmap_vaddr: fffffdff80000000
vmemmap_end: fffffdffffffffff
kimage_text: fffffc0008080000
kimage_end: fffffc0009070000
kimage_voffset: 0000000000000000 <-- available if kernel is not
randomized
phys_offset: 4000000000
...
But it can be read:
crash> px kimage_voffset
kimage_voffset = $1 = 0xfffffbc008000000
crash>
SO because it wasn't determined during session initialization,
it falls into the "no randomness" section of arm64_VTOP():
ulong
arm64_VTOP(ulong addr)
{
if (!(machdep->flags & NEW_VMEMMAP) ||
(addr >= machdep->machspec->page_offset)) {
return machdep->machspec->phys_offset
+ (addr - machdep->machspec->page_offset);
} else {
if (machdep->machspec->kimage_voffset)
return addr - machdep->machspec->kimage_voffset;
else /* no randomness */
return machdep->machspec->phys_offset
+ (addr - machdep->machspec->vmalloc_start_addr);
}
}
That works, but if "kimage_offset" can be read normally later on, perhaps it
should update "machdep->machspec->kimage_voffset" at that time?
There are some discrepancies with respect to the calculated addresses
and what is seen by looking at the reported memory map in the kernel log:
[ 0.000000] Virtual kernel memory layout:
[ 0.000000] modules : 0xfffffc0000000000 - 0xfffffc0008000000 ( 128 MB)
[ 0.000000] vmalloc : 0xfffffc0008000000 - 0xfffffdfedfff0000 ( 2043 GB)
[ 0.000000] .text : 0xfffffc0008080000 - 0xfffffc0008890000 ( 8256 KB)
.rodata : 0xfffffc0008890000 - 0xfffffc0008c10000 ( 3584 KB)
.init : 0xfffffc0008c10000 - 0xfffffc0008d50000 ( 1280 KB)
.data : 0xfffffc0008d50000 - 0xfffffc0008eaac00 ( 1387 KB)
[ 0.000000] vmemmap : 0xfffffdfee0000000 - 0xfffffdffe0000000 ( 4 GB
maximum)
0xfffffdfee0000000 - 0xfffffdfee1000000 ( 16 MB
actual)
[ 0.000000] fixed : 0xfffffdfffe7d0000 - 0xfffffdfffec00000 ( 4288 KB)
[ 0.000000] PCI I/O : 0xfffffdfffee00000 - 0xfffffdffffe00000 ( 16 MB)
[ 0.000000] memory : 0xfffffe0000000000 - 0xfffffe0400000000 ( 16384 MB)
Comparing it to the calculated values:
VA_BITS: 42
userspace_top: 0000040000000000
page_offset: fffffe0000000000 OK
vmalloc_start_addr: fffffc0008000000 OK
vmalloc_end: fffffdff5ffeffff ? (seems wrong)
modules_vaddr: fffffc0000000000 OK
modules_end: fffffc0007ffffff OK (-1)
vmemmap_vaddr: fffffdff80000000 ? (seems wrong)
vmemmap_end: fffffdffffffffff ? (seems wrong)
kimage_text: fffffc0008080000 OK
kimage_end: fffffc0009070000 OK
kimage_voffset: 0000000000000000
phys_offset: 4000000000
Starting with vmalloc_start_addr/vmalloc_end, if I run "kmem -v" to dump the
vmalloc allocations, there are some allocations that are below the
0xfffffc0008000000 start value shown in the log and by your calcuation.
I'm not clear on what that means?:
crash> kmem -v
VMAP_AREA VM_STRUCT ADDRESS RANGE SIZE
fffffe03daefd900 fffffe03daefd880 fffffc0000c10000 - fffffc0000c30000 131072
fffffe00bf2c3a00 fffffe00bf2c3980 fffffc0000c90000 - fffffc0000cb0000 131072
fffffe00bf2c7400 fffffe00bf2c7380 fffffc0000d50000 - fffffc0000d70000 131072
fffffe03dc76aa00 fffffe03dc76a980 fffffc0000d90000 - fffffc0000db0000 131072
fffffe03dc76be00 fffffe03dc76bd80 fffffc0000dd0000 - fffffc0000ee0000 1114112
fffffe03d90e7900 fffffe03d90e7b80 fffffc0000f40000 - fffffc0000fb0000 458752
fffffe00bec12f00 fffffe00bec12b00 fffffc0000fe0000 - fffffc0001000000 131072
fffffe00bf3a1100 fffffe00bf3a1080 fffffc0001020000 - fffffc0001050000 196608
fffffe00bf3a3280 fffffe00bf3a3200 fffffc0001070000 - fffffc0001090000 131072
fffffe03ddf7fc00 fffffe03ddf7a880 fffffc0001230000 - fffffc0001250000 131072
fffffe03fd508900 fffffe03fd508880 fffffc0008000000 - fffffc0008020000 131072
fffffe03fd509580 fffffe03fd508d00 fffffc0008020000 - fffffc0008040000 131072
fffffe03fd508a00 fffffe03fd508980 fffffc0008040000 - fffffc0008070000 196608
... [ cut ] ...
fffffe03d7235000 fffffe03d7233480 fffffc0014b30000 - fffffc0014b50000 131072
fffffe00b921e700 fffffe00b921df00 fffffc0014b70000 - fffffc0014b90000 131072
fffffe00b851eb00 fffffe00b8512900 fffffdfedfcf0000 - fffffdfedfe70000 1572864
fffffe03dca4ef00 fffffe03dca4ef80 fffffdfedfe70000 - fffffdfedfff0000 1572864
crash>
Although the end value of fffffdfedfff0000 does match up with the value in the
kernel log, your calculation is 2GB higher at fffffdff5ffeffff:
crash> eval fffffdff5ffeffff - 0xfffffdfedfff0000
hexadecimal: 7fffffff
decimal: 2147483647
octal: 17777777777
binary: 0000000000000000000000000000000001111111111111111111111111111111
crash> eval 7fffffff + 1
hexadecimal: 80000000 (2GB)
decimal: 2147483648
octal: 20000000000
binary: 0000000000000000000000000000000010000000000000000000000000000000
crash>
With respect to the vmemmap range, vmmemap address in the log file is the one
that is displayed by "kmem -p":
crash> kmem -p
PAGE PHYSICAL MAPPING INDEX CNT FLAGS
fffffdfee0000000 4000000000 fffffe03fd441950 2f 1 1002c
referenced,uptodate,lru,mappedtodisk
fffffdfee0000040 4000010000 fffffe03fd441950 30 1 1002c
referenced,uptodate,lru,mappedtodisk
fffffdfee0000080 4000020000 fffffe03fd441950 31 1 1002c
referenced,uptodate,lru,mappedtodisk
fffffdfee00000c0 4000030000 fffffe03fd441950 32 1 1002c
referenced,uptodate,lru,mappedtodisk
...
fffffdfee0ffff00 43fffc0000 0 0 1 4000000000000400
reserved
fffffdfee0ffff40 43fffd0000 0 0 1 4000000000000400
reserved
fffffdfee0ffff80 43fffe0000 0 0 1 4000000000000400
reserved
fffffdfee0ffffc0 43ffff0000 0 0 1 4000000000000400
reserved
crash>
And "kmem" alone recognizes it:
crash> kmem fffffdfee0000000
PAGE PHYSICAL MAPPING INDEX CNT FLAGS
fffffdfee0000000 4000000000 fffffe03fd441950 2f 1 1002c
referenced,uptodate,lru,mappedtodisk
crash>
But your calculated vmemmap_vaddr above doesn't seem right:
crash> kmem fffffdff80000000
kmem: WARNING: cannot make virtual-to-physical translation: fffffdff80000000
fffffdff80000000: kernel virtual address not found in mem map
crash>
Do your numbers match up on a dump that actually has CONFIG_RANDOMIZE_BASE?
Anyway, onto the patch...
changes in v2:
* Fixed build warnings
* Moved ARM64_NEW_VMEMMAP to machdep->flags
* Show additional kaslr-related parameters in arm64_dump_machdep_table()
* Handle a VMCOREINFO, "NUMBER(kimage_voffset)"
===8<===
>From 080a54ec232ac48ef2d8123cbedcf0f1fe27e391 Mon Sep 17 00:00:00 2001
From: AKASHI Takahiro <takahiro.akashi(a)linaro.org>
Date: Mon, 16 May 2016 17:31:55 +0900
Subject: [PATCH v2] arm64: fix kernel memory map handling for kaslr-enabled
kernel
In kernel v4.6, Kernel ASLR (KASLR) is supported on arm64, and the start
address of the kernel image can be randomized if CONFIG_RANDOMIZE_BASE is
enabled.
Even worse, the kernel image is no more mapped in the linear mapping, but
in vmalloc area (i.e. below PAGE_OFFSET).
Now, according to the kernel's memory.h, converting a virtual address to
a physical address should be done like below:
phys_addr_t __x = (phys_addr_t)(x); \
__x & BIT(VA_BITS - 1) ? (__x & ~PAGE_OFFSET) + PHYS_OFFSET : \
(__x - kimage_voffset); })
Please note that PHYS_OFFSET is no more equal to the start address of
the first usable memory block in SYSTEM RAM due to the fact mentioned
above.
This patch addresses this change and allows the crash utility to access
memory contents with correct addresses.
*However*, it is still rough-edged and we need more refinements.
1-1) On a live system, crash with this patch won't work because
we currently have no way to know kimage_voffset.
1-2) For a core dump file, we can do simply:
$ crash <vmlinux> <vmcore>
as long as the file has "NUMBER(kimage_voffset)"
(RELOC_AUTO|KASLR is automatically set.)
I'm planning to add this enhancement in my next version of kexec/kdump
patch, i.e. v17.
2) My current change breaks the backward compatibility.
Crash won't work with v4.5 or early kernel partly because I changed
the calculation of VA_BITS. (I think that the existing code is wrong.)
So far I don't have enough time to look into this issue as I'm focusing
on KASLR support.
OK, but you still haven't shown how the current VA_BITS determination is
not a correct representation of CONFIG_ARM64_VA_BITS.
3) Backtracing a 'panic'ed task fails:
crash> bt
PID: 999 TASK: ffffffe960081800 CPU: 0 COMMAND: "sh"
bt: WARNING: corrupt prstatus? pstate=0x80000000, but no user frame found
bt: WARNING: cannot determine starting stack frame for task ffffffe960081800
frame->pc indicates that it is a kernel address, so obviously something
is wrong. I'm diggin into it.
Can you add a debug statement that displays frame->pc, frame->sp, and frame->fp?
Signed-off-by: AKASHI Takahiro <takahiro.akashi(a)linaro.org>
---
arm64.c | 217
++++++++++++++++++++++++++++++++++++++++++++++++--------------
defs.h | 24 +++++--
main.c | 7 +-
symbols.c | 10 +--
4 files changed, 196 insertions(+), 62 deletions(-)
diff --git a/arm64.c b/arm64.c
index 34c8c59..6b97093 100644
--- a/arm64.c
+++ b/arm64.c
@@ -72,6 +72,21 @@ static int arm64_get_crash_notes(void);
static void arm64_calc_VA_BITS(void);
static int arm64_is_uvaddr(ulong, struct task_context *);
+ulong
+arm64_VTOP(ulong addr)
+{
+ if (!(machdep->flags & NEW_VMEMMAP) ||
+ (addr >= machdep->machspec->page_offset)) {
+ return machdep->machspec->phys_offset
+ + (addr - machdep->machspec->page_offset);
+ } else {
+ if (machdep->machspec->kimage_voffset)
+ return addr - machdep->machspec->kimage_voffset;
+ else /* no randomness */
+ return machdep->machspec->phys_offset
+ + (addr - machdep->machspec->vmalloc_start_addr);
+ }
+}
/*
* Do all necessary machine-specific setup here. This is called several
times
@@ -81,6 +96,7 @@ void
arm64_init(int when)
{
ulong value;
+ char *string;
struct machine_specific *ms;
#if defined(__x86_64__)
@@ -102,9 +118,34 @@ arm64_init(int when)
if (machdep->cmdline_args[0])
arm64_parse_cmdline_args();
machdep->flags |= MACHDEP_BT_TEXT;
+
+ ms = machdep->machspec;
+ if (!ms->kimage_voffset &&
+ (string = pc->read_vmcoreinfo("NUMBER(kimage_voffset)"))) {
+ ms->kimage_voffset = htol(string, QUIET, NULL);
+ free(string);
+ }
It doesn't make sense to call pc->read_vmcoreinfo() if !DUMPFILE().
+
+ if (ms->kimage_voffset) {
+ machdep->flags |= NEW_VMEMMAP;
+
+ /* if not specified in command line */
+ if (!kt->relocate && !(kt->flags2 & (RELOC_AUTO|KASLR)))
+ kt->flags2 |= (RELOC_AUTO|KASLR);
+ }
+
If CONFIG_RANDOMIZE_BASE is NOT set, should RELOC_AUTO|KASLR be set? They
don't get set on my live system.
break;
case PRE_GDB:
+ /* This check is somewhat redundant */
+ if (kernel_symbol_exists("kimage_voffset")) {
+ machdep->flags |= NEW_VMEMMAP;
+
+ if (!machdep->machspec->kimage_voffset)
+ error(WARNING,
+ "kimage_voffset not identified for kaslr kernel\n");
+ }
+
As mentioned in the general discussion above, the WARNING above makes
no sense if CONFIG_RANDOMIZE_BASE is not configured.
I'm now thinking that CONFIG_RANDOMIZE_BASE (and maybe others like KASAN?)
should be passed in the dumpfile with VMCOREINFO_CONFIG().
if (!machdep->pagesize) {
/*
* Kerneldoc Documentation/arm64/booting.txt describes
@@ -160,16 +201,35 @@ arm64_init(int when)
machdep->pagemask = ~((ulonglong)machdep->pageoffset);
arm64_calc_VA_BITS();
- machdep->machspec->page_offset = ARM64_PAGE_OFFSET;
+ ms = machdep->machspec;
+ ms->page_offset = ARM64_PAGE_OFFSET;
+ /* FIXME: idmap for NEW_VMEMMAP */
machdep->identity_map_base = ARM64_PAGE_OFFSET;
- machdep->machspec->userspace_top = ARM64_USERSPACE_TOP;
- machdep->machspec->modules_vaddr = ARM64_MODULES_VADDR;
- machdep->machspec->modules_end = ARM64_MODULES_END;
- machdep->machspec->vmalloc_start_addr = ARM64_VMALLOC_START;
- machdep->machspec->vmalloc_end = ARM64_VMALLOC_END;
- machdep->kvbase = ARM64_VMALLOC_START;
- machdep->machspec->vmemmap_vaddr = ARM64_VMEMMAP_VADDR;
- machdep->machspec->vmemmap_end = ARM64_VMEMMAP_END;
+ machdep->kvbase = ARM64_VA_START;
+ ms->userspace_top = ARM64_USERSPACE_TOP;
+ if (machdep->flags & NEW_VMEMMAP) {
+ struct syment *sp;
+
+ sp = kernel_symbol_search("_text");
+ ms->kimage_text = (sp ? sp->value : 0);
+ sp = kernel_symbol_search("_end");
+ ms->kimage_end = (sp ? sp->value : 0);
+
+ ms->modules_vaddr = ARM64_VA_START;
+ if (kernel_symbol_exists("kasan_init"))
+ ms->modules_vaddr += ARM64_KASAN_SHADOW_SIZE;
+ ms->modules_end = ms->modules_vaddr
+ + ARM64_MODULES_VSIZE -1;
+
+ ms->vmalloc_start_addr = ms->modules_end + 1;
+ } else {
+ ms->modules_vaddr = ARM64_PAGE_OFFSET - MEGABYTES(64);
+ ms->modules_end = ARM64_PAGE_OFFSET - 1;
+ ms->vmalloc_start_addr = ARM64_VA_START;
+ }
+ ms->vmalloc_end = ARM64_VMALLOC_END;
+ ms->vmemmap_vaddr = ARM64_VMEMMAP_VADDR;
+ ms->vmemmap_end = ARM64_VMEMMAP_END;
switch (machdep->pagesize)
{
@@ -232,8 +292,6 @@ arm64_init(int when)
machdep->stacksize = ARM64_STACK_SIZE;
machdep->flags |= VMEMMAP;
- arm64_calc_phys_offset();
-
machdep->uvtop = arm64_uvtop;
machdep->kvtop = arm64_kvtop;
machdep->is_kvaddr = generic_is_kvaddr;
@@ -262,6 +320,10 @@ arm64_init(int when)
machdep->dumpfile_init = NULL;
machdep->verify_line_number = NULL;
machdep->init_kernel_pgd = arm64_init_kernel_pgd;
+
+ /* use machdep parameters */
+ arm64_calc_phys_offset();
+
This doesn't make any sense to me. I understand you've done it because
you are now doing a readmem() in arm64_calc_phys_offset(). But readmem()
calls are never done this early. And in fact, on the live system the
readmem() in arm64_calc_phys_offset() fails like so (running "crash -d4"):
<readmem: fffffc0008d70bb0, KVADDR, "memstart_addr", 8, (ROE|Q),
3ffcc2842c0>
<read_memory_device: addr: fffffc0008d70bb0 paddr: d70bb0 cnt: 8>
crash: read error: kernel virtual address: fffffc0008d70bb0 type:
"memstart_addr"
It fails above because it needs the phys_base in order to do the readmem(). During
runtime it has it:
crash> set debug 4
debug: 4
crash> rd memstart_addr
<addr: fffffc0008d70bb0 count: 1 flag: 490 (KVADDR)>
<readmem: fffffc0008d70bb0, KVADDR, "64-bit KVADDR", 8, (FOE),
3ffcbfbfc28>
<read_memory_device: addr: fffffc0008d70bb0 paddr: 4000d70bb0 cnt: 8>
fffffc0008d70bb0: 0000004000000000 ....@...
crash>
So without kimage_voffset, that readmem(), how would that readmem() possibly work?
You need the *contents* of memstart_addr in order to *read* memstart_addr.
Now, if it kimage_voffset were passed into the vmcore, then I guess you could
read it. But why do it that way? That's what diskdump_get_phys_base() and
kdump_get_phys_base() are supposed to do.
break;
case POST_GDB:
@@ -409,6 +471,8 @@ arm64_dump_machdep_table(ulong arg)
fprintf(fp, "%sIRQ_STACKS", others++ ? "|" : "");
if (machdep->flags & MACHDEP_BT_TEXT)
fprintf(fp, "%sMACHDEP_BT_TEXT", others++ ? "|" : "");
+ if (machdep->flags & NEW_VMEMMAP)
+ fprintf(fp, "%sNEW_VMEMMAP", others++ ? "|" : "");
fprintf(fp, ")\n");
fprintf(fp, " kvbase: %lx\n", machdep->kvbase);
@@ -494,6 +558,8 @@ arm64_dump_machdep_table(ulong arg)
ms = machdep->machspec;
fprintf(fp, " machspec: %lx\n", (ulong)ms);
+ fprintf(fp, " memory map layout: %s\n",
+ (machdep->flags & NEW_VMEMMAP) ? "new" : "old");
As before, these internal "help" structure dumps just show existing structure
fields,
and NEW_VMMEMAP is already shown in the flags.
fprintf(fp, " VA_BITS: %ld\n",
ms->VA_BITS);
fprintf(fp, " userspace_top: %016lx\n", ms->userspace_top);
fprintf(fp, " page_offset: %016lx\n", ms->page_offset);
@@ -503,6 +569,11 @@ arm64_dump_machdep_table(ulong arg)
fprintf(fp, " modules_end: %016lx\n", ms->modules_end);
fprintf(fp, " vmemmap_vaddr: %016lx\n", ms->vmemmap_vaddr);
fprintf(fp, " vmemmap_end: %016lx\n", ms->vmemmap_end);
+ if (machdep->flags & NEW_VMEMMAP) {
+ fprintf(fp, " kimage_text: %016lx\n", ms->kimage_text);
+ fprintf(fp, " kimage_end: %016lx\n", ms->kimage_end);
+ fprintf(fp, " kimage_voffset: %016lx\n", ms->kimage_voffset);
+ }
fprintf(fp, " phys_offset: %lx\n", ms->phys_offset);
fprintf(fp, "__exception_text_start: %lx\n", ms->__exception_text_start);
fprintf(fp, " __exception_text_end: %lx\n", ms->__exception_text_end);
@@ -543,6 +614,42 @@ arm64_dump_machdep_table(ulong arg)
}
}
+static int
+arm64_parse_machdep_arg_l(char *argstring, char *param, ulong *value)
+{
+ int len;
+ int megabytes = FALSE;
+ char *p;
+
+ len = strlen(param);
+ if (!STRNEQ(argstring, param) || (argstring[len] != '='))
+ return FALSE;
+
+ if ((LASTCHAR(argstring) == 'm') ||
+ (LASTCHAR(argstring) == 'M')) {
+ LASTCHAR(argstring) = NULLCHAR;
+ megabytes = TRUE;
+ }
+
+ p = argstring + len + 1;
+ if (strlen(p)) {
+ int flags = RETURN_ON_ERROR | QUIET;
+ int err = 0;
+
+ if (megabytes) {
+ *value = dtol(p, flags, &err);
+ if (!err)
+ *value = MEGABYTES(*value);
+ } else {
+ *value = htol(p, flags, &err);
+ }
+
+ if (!err)
+ return TRUE;
+ }
+
+ return FALSE;
+}
/*
* Parse machine dependent command line arguments.
@@ -554,11 +661,10 @@ arm64_dump_machdep_table(ulong arg)
static void
arm64_parse_cmdline_args(void)
{
- int index, i, c, err;
+ int index, i, c;
char *arglist[MAXARGS];
char buf[BUFSIZE];
char *p;
- ulong value = 0;
for (index = 0; index < MAX_MACHDEP_ARGS; index++) {
if (!machdep->cmdline_args[index])
@@ -580,39 +686,23 @@ arm64_parse_cmdline_args(void)
c = parse_line(buf, arglist);
for (i = 0; i < c; i++) {
- err = 0;
-
- if (STRNEQ(arglist[i], "phys_offset=")) {
- int megabytes = FALSE;
- int flags = RETURN_ON_ERROR | QUIET;
-
- if ((LASTCHAR(arglist[i]) == 'm') ||
- (LASTCHAR(arglist[i]) == 'M')) {
- LASTCHAR(arglist[i]) = NULLCHAR;
- megabytes = TRUE;
- }
-
- p = arglist[i] + strlen("phys_offset=");
- if (strlen(p)) {
- if (megabytes)
- value = dtol(p, flags, &err);
- else
- value = htol(p, flags, &err);
- }
-
- if (!err) {
- if (megabytes)
- value = MEGABYTES(value);
-
- machdep->machspec->phys_offset = value;
-
- error(NOTE,
- "setting phys_offset to: 0x%lx\n\n",
- machdep->machspec->phys_offset);
+ if (arm64_parse_machdep_arg_l(arglist[i],
+ "phys_offset",
+ &machdep->machspec->phys_offset)) {
+ error(NOTE,
+ "setting phys_offset to: 0x%lx\n\n",
+ machdep->machspec->phys_offset);
+
+ machdep->flags |= PHYS_OFFSET;
+ continue;
+ } else if (arm64_parse_machdep_arg_l(arglist[i],
+ "kimage_voffset",
+ &machdep->machspec->kimage_voffset)) {
+ error(NOTE,
+ "setting kimage_voffset to: 0x%lx\n\n",
+ machdep->machspec->kimage_voffset);
- machdep->flags |= PHYS_OFFSET;
- continue;
- }
+ continue;
}
error(WARNING, "ignoring --machdep option: %s\n",
@@ -627,10 +717,20 @@ arm64_calc_phys_offset(void)
{
struct machine_specific *ms = machdep->machspec;
ulong phys_offset;
+ struct syment *sp;
+ ulong value;
if (machdep->flags & PHYS_OFFSET) /* --machdep override */
return;
+ sp = kernel_symbol_search("memstart_addr");
+ if (sp && readmem(sp->value, KVADDR, (char *)&value, sizeof(value),
+ "memstart_addr", QUIET|RETURN_ON_ERROR)) {
+ ms->phys_offset = value;
+ machdep->flags |= PHYS_OFFSET;
+ return;
+ }
+
Also, I may be missing something, but the PHYS_OFFSET flag means that it was
passed in via --machdep, and is only used in this function to avoid any further
attempts to figure out what it is. Here you are setting the flag for no particular
reason that I can see. Why?
But again, doing a readmem() call this early is setting a bad precedent -- they have
*always* been delayed until after gdb_session_init() in main_loop(). And the work
of determining phys_base should be done by the dumpfile call-out functions that
already exist.
/*
* Next determine suitable value for phys_offset. User can override this
* by passing valid '--machdep phys_offset=<addr>' option.
@@ -2377,6 +2477,11 @@ arm64_IS_VMALLOC_ADDR(ulong vaddr)
{
struct machine_specific *ms = machdep->machspec;
+ if ((machdep->flags & NEW_VMEMMAP) &&
+ (vaddr >= machdep->machspec->kimage_text) &&
+ (vaddr <= machdep->machspec->kimage_end))
+ return FALSE;
+
return ((vaddr >= ms->vmalloc_start_addr && vaddr <=
ms->vmalloc_end) ||
((machdep->flags & VMEMMAP) &&
(vaddr >= ms->vmemmap_vaddr && vaddr <=
ms->vmemmap_end))
||
@@ -2407,7 +2512,11 @@ arm64_calc_VA_BITS(void)
for (bitval = highest_bit_long(value); bitval; bitval--) {
if ((value & (1UL << bitval)) == 0) {
+#if 1
+ machdep->machspec->VA_BITS = bitval + 1;
+#else /* FIXME: bug? */
machdep->machspec->VA_BITS = bitval + 2;
+#endif
break;
}
}
Again, a non-starter until the above is resolved -- but you know that already...
@@ -2459,10 +2568,22 @@ arm64_calc_virtual_memory_ranges(void)
break;
}
- vmemmap_size = ALIGN((1UL << (ms->VA_BITS - machdep->pageshift)) *
SIZE(page), PUD_SIZE);
+ if (machdep->flags & NEW_VMEMMAP)
+#define STRUCT_PAGE_MAX_SHIFT 6
+ vmemmap_size = 1UL << (ms->VA_BITS - machdep->pageshift - 1
+ + STRUCT_PAGE_MAX_SHIFT);
+ else
+ vmemmap_size = ALIGN((1UL << (ms->VA_BITS - machdep->pageshift)) *
SIZE(page), PUD_SIZE);
+
vmalloc_end = (ms->page_offset - PUD_SIZE - vmemmap_size - SZ_64K);
- vmemmap_start = vmalloc_end + SZ_64K;
- vmemmap_end = vmemmap_start + vmemmap_size;
+
+ if (machdep->flags & NEW_VMEMMAP) {
+ vmemmap_start = ms->page_offset - vmemmap_size;
+ vmemmap_end = ms->page_offset;
+ } else {
+ vmemmap_start = vmalloc_end + SZ_64K;
+ vmemmap_end = vmemmap_start + vmemmap_size;
+ }
ms->vmalloc_end = vmalloc_end - 1;
ms->vmemmap_vaddr = vmemmap_start;
diff --git a/defs.h b/defs.h
index a09fa9a..2bbb55b 100644
--- a/defs.h
+++ b/defs.h
@@ -2844,8 +2844,8 @@ typedef u64 pte_t;
#define PTOV(X) \
((unsigned
long)(X)-(machdep->machspec->phys_offset)+(machdep->machspec->page_offset))
-#define VTOP(X) \
- ((unsigned
long)(X)-(machdep->machspec->page_offset)+(machdep->machspec->phys_offset))
+
+#define VTOP(X) arm64_VTOP((ulong)(X))
#define USERSPACE_TOP (machdep->machspec->userspace_top)
#define PAGE_OFFSET (machdep->machspec->page_offset)
@@ -2938,18 +2938,23 @@ typedef signed int s32;
#define VM_L3_4K (0x10)
#define KDUMP_ENABLED (0x20)
#define IRQ_STACKS (0x40)
+#define NEW_VMEMMAP (0x80)
/*
* sources: Documentation/arm64/memory.txt
* arch/arm64/include/asm/memory.h
* arch/arm64/include/asm/pgtable.h
*/
-
-#define ARM64_PAGE_OFFSET ((0xffffffffffffffffUL) <<
(machdep->machspec->VA_BITS - 1))
+#define ARM64_VA_START ((0xffffffffffffffffUL) \
+ << machdep->machspec->VA_BITS)
+#define ARM64_PAGE_OFFSET ((0xffffffffffffffffUL) \
+ << (machdep->machspec->VA_BITS - 1))
#define ARM64_USERSPACE_TOP ((1UL) << machdep->machspec->VA_BITS)
-#define ARM64_MODULES_VADDR (ARM64_PAGE_OFFSET - MEGABYTES(64))
-#define ARM64_MODULES_END (ARM64_PAGE_OFFSET - 1)
-#define ARM64_VMALLOC_START ((0xffffffffffffffffUL) <<
machdep->machspec->VA_BITS)
+
+/* only used for v4.6 or later */
+#define ARM64_MODULES_VSIZE MEGABYTES(128)
+#define ARM64_KASAN_SHADOW_SIZE (1UL << (machdep->machspec->VA_BITS - 3))
+
/*
* The following 3 definitions are the original values, but are obsolete
* for 3.17 and later kernels because they are now build-time calculations.
@@ -3028,6 +3033,10 @@ struct machine_specific {
ulong kernel_flags;
ulong irq_stack_size;
ulong *irq_stacks;
+ /* only needed for kaslr-enabled kernel */
+ ulong kimage_voffset;
+ ulong kimage_text;
+ ulong kimage_end;
};
The comment is wrong -- the kimage_text and kimage_end values are needed for
NEW_VMEMMAP kernels that are NOT configured with CONFIG_RANDOMIZE_BASE.
Unless you consider my live system "kaslr-enabled"?
struct arm64_stackframe {
@@ -5385,6 +5394,7 @@ void unwind_backtrace(struct bt_info *);
#ifdef ARM64
void arm64_init(int);
void arm64_dump_machdep_table(ulong);
+ulong arm64_VTOP(ulong);
int arm64_IS_VMALLOC_ADDR(ulong);
ulong arm64_swp_type(ulong);
ulong arm64_swp_offset(ulong);
diff --git a/main.c b/main.c
index 821bb4e..3f24908 100644
--- a/main.c
+++ b/main.c
@@ -227,9 +227,10 @@ main(int argc, char **argv)
optarg);
}
} else if (STREQ(long_options[option_index].name, "kaslr")) {
- if (!machine_type("X86_64"))
- error(INFO, "--kaslr only valid "
- "with X86_64 machine type.\n");
+ if (!machine_type("X86_64") &&
+ !machine_type("ARM64"))
+ error(INFO, "--kaslr not valid "
+ "with this machine type.\n");
else if (STREQ(optarg, "auto"))
kt->flags2 |= (RELOC_AUTO|KASLR);
else {
diff --git a/symbols.c b/symbols.c
index a8d3563..df27793 100644
--- a/symbols.c
+++ b/symbols.c
@@ -593,7 +593,8 @@ kaslr_init(void)
{
char *string;
- if (!machine_type("X86_64") || (kt->flags & RELOC_SET))
+ if ((!machine_type("X86_64") && !machine_type("ARM64")) ||
+ (kt->flags & RELOC_SET))
return;
/*
@@ -712,7 +713,7 @@ store_symbols(bfd *abfd, int dynamic, void *minisyms,
long symcount,
if (machine_type("X86")) {
if (!(kt->flags & RELOC_SET))
kt->flags |= RELOC_FORCE;
- } else if (machine_type("X86_64")) {
+ } else if (machine_type("X86_64") || machine_type("ARM64")) {
if ((kt->flags2 & RELOC_AUTO) && !(kt->flags & RELOC_SET))
derive_kaslr_offset(abfd, dynamic, from,
fromend, size, store);
@@ -783,7 +784,8 @@ store_sysmap_symbols(void)
error(FATAL, "symbol table namespace malloc: %s\n",
strerror(errno));
- if (!machine_type("X86") && !machine_type("X86_64"))
+ if (!machine_type("X86") && !machine_type("X86_64")
&&
+ !machine_type("ARM64"))
kt->flags &= ~RELOC_SET;
first = 0;
@@ -4681,7 +4683,7 @@ value_search(ulong value, ulong *offset)
if ((sp = machdep->value_to_symbol(value, offset)))
return sp;
- if (IS_VMALLOC_ADDR(value))
+ if (IS_VMALLOC_ADDR(value))
goto check_modules;
if ((sp = symval_hash_search(value)) == NULL)
--
2.8.1
--
Looking better, still a ways to go...
Thanks,
Dave
3:35 a.m.
On Tue, May 24, 2016 at 01:59:06PM -0400, Dave Anderson wrote:
----- Original Message -----
> Yet some issues, but ...
>
Hi Takahiro,
Here are my general comments on my testing of the v2 patch, followed
by a few comments in the patch itself.
Thank you for your quick review/testing, again.
First, the combination of the new memory map layout and KASLR is
somewhat
confusing. I am testing your patch on a 4.6.0-0.rc7.git2.1.fc25 kernel
that has this configuration:
Right. I use the "kaslr kernel" or "kaslr-enabled kernel" in two
meanings (almost interchangeably):
- kernel with a new memory map, that is v4.6 or later
- kernel that has ability of KASLR (configured with CONFIG_RANDOMIZE_RAM)
When we talked offline, you mentioned the possibility of backporting
KASLR to older kernel, so I hesitated to use "v4.6 or later".
But I think that we'd better use "v4.6 or later" for a clarification
for now.
config-arm64:# CONFIG_RANDOMIZE_BASE is not set
So KASLR doesn't really enter into the picture. But when bringing
up the crash session, it shows the "kaslr kernel" WARNING:
# ./crash
crash 7.1.5++
Copyright (C) 2002-2016 Red Hat, Inc.
Copyright (C) 2004, 2005, 2006, 2010 IBM Corporation
Copyright (C) 1999-2006 Hewlett-Packard Co
Copyright (C) 2005, 2006, 2011, 2012 Fujitsu Limited
Copyright (C) 2006, 2007 VA Linux Systems Japan K.K.
Copyright (C) 2005, 2011 NEC Corporation
Copyright (C) 1999, 2002, 2007 Silicon Graphics, Inc.
Copyright (C) 1999, 2000, 2001, 2002 Mission Critical Linux, Inc.
This program is free software, covered by the GNU General Public License,
and you are welcome to change it and/or distribute copies of it under
certain conditions. Enter "help copying" to see the conditions.
This program has absolutely no warranty. Enter "help warranty" for details.
WARNING: kimage_voffset not identified for kaslr kernel
GNU gdb (GDB) 7.6
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "aarch64-unknown-linux-gnu"...
KERNEL: /usr/lib/debug/lib/modules/4.6.0-0.rc7.git2.1.fc25.aarch64/vmlinux
DUMPFILE: /dev/crash
CPUS: 8
DATE: Tue May 24 10:08:08 2016
UPTIME: 11 days, 18:32:41
LOAD AVERAGE: 0.17, 0.09, 0.12
TASKS: 197
NODENAME: apm-mustang-ev3-36.khw.lab.eng.bos.redhat.com
RELEASE: 4.6.0-0.rc7.git2.1.fc25.aarch64
VERSION: #1 SMP Thu May 12 13:28:43 UTC 2016
MACHINE: aarch64 (unknown Mhz)
MEMORY: 16 GB
PID: 7556
COMMAND: "crash"
TASK: fffffe00beb45400 [THREAD_INFO: fffffe00beb98000]
CPU: 7
STATE: TASK_RUNNING (ACTIVE)
crash>
Why show that WARNING in this case? I understant that it's not
stashed during early initialization:
If we don't know kimage_voffset, we can't analyze the contents of
memory (live or kdump).
crash> help -m
flags: 104000c5
(KSYMS_START|VM_L2_64K|VMEMMAP|IRQ_STACKS|MACHDEP_BT_TEXT|NEW_VMEMMAP)
... [ cut ] ...
memory map layout: new <--- BTW, this is redundant/not-a-member, and
we've got NEW_VMEMMAP
VA_BITS: 42
userspace_top: 0000040000000000
page_offset: fffffe0000000000
vmalloc_start_addr: fffffc0008000000
vmalloc_end: fffffdff5ffeffff
modules_vaddr: fffffc0000000000
modules_end: fffffc0007ffffff
vmemmap_vaddr: fffffdff80000000
vmemmap_end: fffffdffffffffff
kimage_text: fffffc0008080000
kimage_end: fffffc0009070000
kimage_voffset: 0000000000000000 <-- available if kernel is not
randomized
phys_offset: 4000000000
...
But it can be read:
crash> px kimage_voffset
kimage_voffset = $1 = 0xfffffbc008000000
crash>
SO because it wasn't determined during session initialization,
it falls into the "no randomness" section of arm64_VTOP():
Exactly.
ulong
arm64_VTOP(ulong addr)
{
if (!(machdep->flags & NEW_VMEMMAP) ||
(addr >= machdep->machspec->page_offset)) {
return machdep->machspec->phys_offset
+ (addr - machdep->machspec->page_offset);
} else {
if (machdep->machspec->kimage_voffset)
return addr - machdep->machspec->kimage_voffset;
else /* no randomness */
return machdep->machspec->phys_offset
+ (addr -
machdep->machspec->vmalloc_start_addr);
}
}
That works, but if "kimage_offset" can be read normally later on, perhaps it
should update "machdep->machspec->kimage_voffset" at that time?
It is possible, but the check in arm64_VTOP() would be still necessary.
There are some discrepancies with respect to the calculated
addresses
and what is seen by looking at the reported memory map in the kernel log:
[ 0.000000] Virtual kernel memory layout:
[ 0.000000] modules : 0xfffffc0000000000 - 0xfffffc0008000000 ( 128 MB)
[ 0.000000] vmalloc : 0xfffffc0008000000 - 0xfffffdfedfff0000 ( 2043 GB)
[ 0.000000] .text : 0xfffffc0008080000 - 0xfffffc0008890000 ( 8256 KB)
.rodata : 0xfffffc0008890000 - 0xfffffc0008c10000 ( 3584 KB)
.init : 0xfffffc0008c10000 - 0xfffffc0008d50000 ( 1280 KB)
.data : 0xfffffc0008d50000 - 0xfffffc0008eaac00 ( 1387 KB)
[ 0.000000] vmemmap : 0xfffffdfee0000000 - 0xfffffdffe0000000 ( 4 GB
maximum)
0xfffffdfee0000000 - 0xfffffdfee1000000 ( 16 MB
actual)
[ 0.000000] fixed : 0xfffffdfffe7d0000 - 0xfffffdfffec00000 ( 4288 KB)
[ 0.000000] PCI I/O : 0xfffffdfffee00000 - 0xfffffdffffe00000 ( 16 MB)
[ 0.000000] memory : 0xfffffe0000000000 - 0xfffffe0400000000 ( 16384 MB)
Comparing it to the calculated values:
VA_BITS: 42
userspace_top: 0000040000000000
page_offset: fffffe0000000000 OK
vmalloc_start_addr: fffffc0008000000 OK
vmalloc_end: fffffdff5ffeffff ? (seems wrong)
modules_vaddr: fffffc0000000000 OK
modules_end: fffffc0007ffffff OK (-1)
vmemmap_vaddr: fffffdff80000000 ? (seems wrong)
vmemmap_end: fffffdffffffffff ? (seems wrong)
kimage_text: fffffc0008080000 OK
kimage_end: fffffc0009070000 OK
kimage_voffset: 0000000000000000
phys_offset: 4000000000
Starting with vmalloc_start_addr/vmalloc_end, if I run "kmem -v" to dump the
vmalloc allocations, there are some allocations that are below the
0xfffffc0008000000 start value shown in the log and by your calcuation.
I'm not clear on what that means?:
crash> kmem -v
VMAP_AREA VM_STRUCT ADDRESS RANGE SIZE
fffffe03daefd900 fffffe03daefd880 fffffc0000c10000 - fffffc0000c30000 131072
fffffe00bf2c3a00 fffffe00bf2c3980 fffffc0000c90000 - fffffc0000cb0000 131072
fffffe00bf2c7400 fffffe00bf2c7380 fffffc0000d50000 - fffffc0000d70000 131072
fffffe03dc76aa00 fffffe03dc76a980 fffffc0000d90000 - fffffc0000db0000 131072
fffffe03dc76be00 fffffe03dc76bd80 fffffc0000dd0000 - fffffc0000ee0000 1114112
fffffe03d90e7900 fffffe03d90e7b80 fffffc0000f40000 - fffffc0000fb0000 458752
fffffe00bec12f00 fffffe00bec12b00 fffffc0000fe0000 - fffffc0001000000 131072
fffffe00bf3a1100 fffffe00bf3a1080 fffffc0001020000 - fffffc0001050000 196608
fffffe00bf3a3280 fffffe00bf3a3200 fffffc0001070000 - fffffc0001090000 131072
fffffe03ddf7fc00 fffffe03ddf7a880 fffffc0001230000 - fffffc0001250000 131072
fffffe03fd508900 fffffe03fd508880 fffffc0008000000 - fffffc0008020000 131072
fffffe03fd509580 fffffe03fd508d00 fffffc0008020000 - fffffc0008040000 131072
fffffe03fd508a00 fffffe03fd508980 fffffc0008040000 - fffffc0008070000 196608
... [ cut ] ...
fffffe03d7235000 fffffe03d7233480 fffffc0014b30000 - fffffc0014b50000 131072
fffffe00b921e700 fffffe00b921df00 fffffc0014b70000 - fffffc0014b90000 131072
fffffe00b851eb00 fffffe00b8512900 fffffdfedfcf0000 - fffffdfedfe70000 1572864
fffffe03dca4ef00 fffffe03dca4ef80 fffffdfedfe70000 - fffffdfedfff0000 1572864
crash>
Although the end value of fffffdfedfff0000 does match up with the value in the
kernel log, your calculation is 2GB higher at fffffdff5ffeffff:
crash> eval fffffdff5ffeffff - 0xfffffdfedfff0000
hexadecimal: 7fffffff
decimal: 2147483647
octal: 17777777777
binary: 0000000000000000000000000000000001111111111111111111111111111111
crash> eval 7fffffff + 1
hexadecimal: 80000000 (2GB)
decimal: 2147483648
octal: 20000000000
binary: 0000000000000000000000000000000010000000000000000000000000000000
crash>
With respect to the vmemmap range, vmmemap address in the log file is the one
that is displayed by "kmem -p":
crash> kmem -p
PAGE PHYSICAL MAPPING INDEX CNT FLAGS
fffffdfee0000000 4000000000 fffffe03fd441950 2f 1 1002c
referenced,uptodate,lru,mappedtodisk
fffffdfee0000040 4000010000 fffffe03fd441950 30 1 1002c
referenced,uptodate,lru,mappedtodisk
fffffdfee0000080 4000020000 fffffe03fd441950 31 1 1002c
referenced,uptodate,lru,mappedtodisk
fffffdfee00000c0 4000030000 fffffe03fd441950 32 1 1002c
referenced,uptodate,lru,mappedtodisk
...
fffffdfee0ffff00 43fffc0000 0 0 1 4000000000000400
reserved
fffffdfee0ffff40 43fffd0000 0 0 1 4000000000000400
reserved
fffffdfee0ffff80 43fffe0000 0 0 1 4000000000000400
reserved
fffffdfee0ffffc0 43ffff0000 0 0 1 4000000000000400
reserved
crash>
And "kmem" alone recognizes it:
crash> kmem fffffdfee0000000
PAGE PHYSICAL MAPPING INDEX CNT FLAGS
fffffdfee0000000 4000000000 fffffe03fd441950 2f 1 1002c
referenced,uptodate,lru,mappedtodisk
crash>
But your calculated vmemmap_vaddr above doesn't seem right:
crash> kmem fffffdff80000000
kmem: WARNING: cannot make virtual-to-physical translation: fffffdff80000000
fffffdff80000000: kernel virtual address not found in mem map
crash>
Do your numbers match up on a dump that actually has CONFIG_RANDOMIZE_BASE?
In my environment, the numbers above match up on a dump whether
CONFIG_RANDOMIZE_BASE is enabled or not.
Are you using a mainline kernel (final v4.6, not -rcX)?
Anyway, onto the patch...
>
> changes in v2:
> * Fixed build warnings
> * Moved ARM64_NEW_VMEMMAP to machdep->flags
> * Show additional kaslr-related parameters in arm64_dump_machdep_table()
> * Handle a VMCOREINFO, "NUMBER(kimage_voffset)"
>
> ===8<===
> >From 080a54ec232ac48ef2d8123cbedcf0f1fe27e391 Mon Sep 17 00:00:00 2001
> From: AKASHI Takahiro <takahiro.akashi(a)linaro.org>
> Date: Mon, 16 May 2016 17:31:55 +0900
> Subject: [PATCH v2] arm64: fix kernel memory map handling for kaslr-enabled
> kernel
>
> In kernel v4.6, Kernel ASLR (KASLR) is supported on arm64, and the start
> address of the kernel image can be randomized if CONFIG_RANDOMIZE_BASE is
> enabled.
> Even worse, the kernel image is no more mapped in the linear mapping, but
> in vmalloc area (i.e. below PAGE_OFFSET).
>
> Now, according to the kernel's memory.h, converting a virtual address to
> a physical address should be done like below:
>
> phys_addr_t __x = (phys_addr_t)(x); \
> __x & BIT(VA_BITS - 1) ? (__x & ~PAGE_OFFSET) + PHYS_OFFSET : \
> (__x - kimage_voffset); })
>
> Please note that PHYS_OFFSET is no more equal to the start address of
> the first usable memory block in SYSTEM RAM due to the fact mentioned
> above.
>
> This patch addresses this change and allows the crash utility to access
> memory contents with correct addresses.
> *However*, it is still rough-edged and we need more refinements.
>
> 1-1) On a live system, crash with this patch won't work because
> we currently have no way to know kimage_voffset.
>
> 1-2) For a core dump file, we can do simply:
> $ crash <vmlinux> <vmcore>
> as long as the file has "NUMBER(kimage_voffset)"
> (RELOC_AUTO|KASLR is automatically set.)
>
> I'm planning to add this enhancement in my next version of kexec/kdump
> patch, i.e. v17.
>
> 2) My current change breaks the backward compatibility.
> Crash won't work with v4.5 or early kernel partly because I changed
> the calculation of VA_BITS. (I think that the existing code is wrong.)
> So far I don't have enough time to look into this issue as I'm focusing
> on KASLR support.
OK, but you still haven't shown how the current VA_BITS determination is
not a correct representation of CONFIG_ARM64_VA_BITS.
At least, the current VA_BITS doesn't work with my calculations, which
were derived directly from v4.6's "asm/memory.h".
> 3) Backtracing a 'panic'ed task fails:
> crash> bt
> PID: 999 TASK: ffffffe960081800 CPU: 0 COMMAND: "sh"
> bt: WARNING: corrupt prstatus? pstate=0x80000000, but no user frame found
> bt: WARNING: cannot determine starting stack frame for task ffffffe960081800
>
> frame->pc indicates that it is a kernel address, so obviously something
> is wrong. I'm diggin into it.
Can you add a debug statement that displays frame->pc, frame->sp, and frame->fp?
I've already identified the cause.
pt_regs->pstate was set mistakenly from "sprsr_el1" in panic().
But I have a difficulty here to fix the problem as we have no direct way
to retrieve a value of the *current* PSTATE.
> Signed-off-by: AKASHI Takahiro <takahiro.akashi(a)linaro.org>
> ---
> arm64.c | 217
> ++++++++++++++++++++++++++++++++++++++++++++++++--------------
> defs.h | 24 +++++--
> main.c | 7 +-
> symbols.c | 10 +--
> 4 files changed, 196 insertions(+), 62 deletions(-)
>
> diff --git a/arm64.c b/arm64.c
> index 34c8c59..6b97093 100644
> --- a/arm64.c
> +++ b/arm64.c
> @@ -72,6 +72,21 @@ static int arm64_get_crash_notes(void);
> static void arm64_calc_VA_BITS(void);
> static int arm64_is_uvaddr(ulong, struct task_context *);
>
> +ulong
> +arm64_VTOP(ulong addr)
> +{
> + if (!(machdep->flags & NEW_VMEMMAP) ||
> + (addr >= machdep->machspec->page_offset)) {
> + return machdep->machspec->phys_offset
> + + (addr - machdep->machspec->page_offset);
> + } else {
> + if (machdep->machspec->kimage_voffset)
> + return addr - machdep->machspec->kimage_voffset;
> + else /* no randomness */
> + return machdep->machspec->phys_offset
> + + (addr - machdep->machspec->vmalloc_start_addr);
> + }
> +}
>
> /*
> * Do all necessary machine-specific setup here. This is called several
> times
> @@ -81,6 +96,7 @@ void
> arm64_init(int when)
> {
> ulong value;
> + char *string;
> struct machine_specific *ms;
>
> #if defined(__x86_64__)
> @@ -102,9 +118,34 @@ arm64_init(int when)
> if (machdep->cmdline_args[0])
> arm64_parse_cmdline_args();
> machdep->flags |= MACHDEP_BT_TEXT;
> +
> + ms = machdep->machspec;
> + if (!ms->kimage_voffset &&
> + (string = pc->read_vmcoreinfo("NUMBER(kimage_voffset)"))) {
> + ms->kimage_voffset = htol(string, QUIET, NULL);
> + free(string);
> + }
It doesn't make sense to call pc->read_vmcoreinfo() if !DUMPFILE().
Do you think so?
By default, pc->read_vmcoreinfo is set to no_vmcoreinfo.
So it doesn't hurt anything.
> +
> + if (ms->kimage_voffset) {
> + machdep->flags |= NEW_VMEMMAP;
> +
> + /* if not specified in command line */
> + if (!kt->relocate && !(kt->flags2 & (RELOC_AUTO|KASLR)))
> + kt->flags2 |= (RELOC_AUTO|KASLR);
> + }
> +
If CONFIG_RANDOMIZE_BASE is NOT set, should RELOC_AUTO|KASLR be set? They
don't get set on my live system.
Not necessarily, but the current implementation of derive_kaslr_offset()
just works even in this case.
(This is the reason that I don't think we need a VMCOREINFO for
CONFIG_RANDOMIZE_BASE.)
> break;
>
> case PRE_GDB:
> + /* This check is somewhat redundant */
> + if (kernel_symbol_exists("kimage_voffset")) {
> + machdep->flags |= NEW_VMEMMAP;
> +
> + if (!machdep->machspec->kimage_voffset)
> + error(WARNING,
> + "kimage_voffset not identified for kaslr kernel\n");
> + }
> +
As mentioned in the general discussion above, the WARNING above makes
no sense if CONFIG_RANDOMIZE_BASE is not configured.
What about if I change the message "for v4.6 or later kernel"?
I'm now thinking that CONFIG_RANDOMIZE_BASE (and maybe others
like KASAN?)
should be passed in the dumpfile with VMCOREINFO_CONFIG().
Regarding KASAN, we only need to check for an existence of "kasan_init"
symbol as you recommended before :)
> if (!machdep->pagesize) {
> /*
> * Kerneldoc Documentation/arm64/booting.txt describes
> @@ -160,16 +201,35 @@ arm64_init(int when)
> machdep->pagemask = ~((ulonglong)machdep->pageoffset);
>
> arm64_calc_VA_BITS();
> - machdep->machspec->page_offset = ARM64_PAGE_OFFSET;
> + ms = machdep->machspec;
> + ms->page_offset = ARM64_PAGE_OFFSET;
> + /* FIXME: idmap for NEW_VMEMMAP */
> machdep->identity_map_base = ARM64_PAGE_OFFSET;
> - machdep->machspec->userspace_top = ARM64_USERSPACE_TOP;
> - machdep->machspec->modules_vaddr = ARM64_MODULES_VADDR;
> - machdep->machspec->modules_end = ARM64_MODULES_END;
> - machdep->machspec->vmalloc_start_addr = ARM64_VMALLOC_START;
> - machdep->machspec->vmalloc_end = ARM64_VMALLOC_END;
> - machdep->kvbase = ARM64_VMALLOC_START;
> - machdep->machspec->vmemmap_vaddr = ARM64_VMEMMAP_VADDR;
> - machdep->machspec->vmemmap_end = ARM64_VMEMMAP_END;
> + machdep->kvbase = ARM64_VA_START;
> + ms->userspace_top = ARM64_USERSPACE_TOP;
> + if (machdep->flags & NEW_VMEMMAP) {
> + struct syment *sp;
> +
> + sp = kernel_symbol_search("_text");
> + ms->kimage_text = (sp ? sp->value : 0);
> + sp = kernel_symbol_search("_end");
> + ms->kimage_end = (sp ? sp->value : 0);
> +
> + ms->modules_vaddr = ARM64_VA_START;
> + if (kernel_symbol_exists("kasan_init"))
> + ms->modules_vaddr += ARM64_KASAN_SHADOW_SIZE;
> + ms->modules_end = ms->modules_vaddr
> + + ARM64_MODULES_VSIZE -1;
> +
> + ms->vmalloc_start_addr = ms->modules_end + 1;
> + } else {
> + ms->modules_vaddr = ARM64_PAGE_OFFSET - MEGABYTES(64);
> + ms->modules_end = ARM64_PAGE_OFFSET - 1;
> + ms->vmalloc_start_addr = ARM64_VA_START;
> + }
> + ms->vmalloc_end = ARM64_VMALLOC_END;
> + ms->vmemmap_vaddr = ARM64_VMEMMAP_VADDR;
> + ms->vmemmap_end = ARM64_VMEMMAP_END;
>
> switch (machdep->pagesize)
> {
> @@ -232,8 +292,6 @@ arm64_init(int when)
> machdep->stacksize = ARM64_STACK_SIZE;
> machdep->flags |= VMEMMAP;
>
> - arm64_calc_phys_offset();
> -
> machdep->uvtop = arm64_uvtop;
> machdep->kvtop = arm64_kvtop;
> machdep->is_kvaddr = generic_is_kvaddr;
> @@ -262,6 +320,10 @@ arm64_init(int when)
> machdep->dumpfile_init = NULL;
> machdep->verify_line_number = NULL;
> machdep->init_kernel_pgd = arm64_init_kernel_pgd;
> +
> + /* use machdep parameters */
> + arm64_calc_phys_offset();
> +
This doesn't make any sense to me. I understand you've done it because
you are now doing a readmem() in arm64_calc_phys_offset(). But readmem()
calls are never done this early. And in fact, on the live system the
readmem() in arm64_calc_phys_offset() fails like so (running "crash -d4"):
<readmem: fffffc0008d70bb0, KVADDR, "memstart_addr", 8, (ROE|Q),
3ffcc2842c0>
<read_memory_device: addr: fffffc0008d70bb0 paddr: d70bb0 cnt: 8>
crash: read error: kernel virtual address: fffffc0008d70bb0 type:
"memstart_addr"
It fails above because it needs the phys_base in order to do the readmem(). During
runtime it has it:
This is because we don't know kimage_voffset on a live system.
(and so I mentioned this issue in my commit log.)
As far as kdump case is concerned, readmem() at this point just works
for any address in kernel image. This is my intentional use of this function.
crash> set debug 4
debug: 4
crash> rd memstart_addr
<addr: fffffc0008d70bb0 count: 1 flag: 490 (KVADDR)>
<readmem: fffffc0008d70bb0, KVADDR, "64-bit KVADDR", 8, (FOE),
3ffcbfbfc28>
<read_memory_device: addr: fffffc0008d70bb0 paddr: 4000d70bb0 cnt: 8>
fffffc0008d70bb0: 0000004000000000 ....@...
crash>
So without kimage_voffset, that readmem(), how would that readmem() possibly work?
You need the *contents* of memstart_addr in order to *read* memstart_addr.
Now, if it kimage_voffset were passed into the vmcore, then I guess you could
read it. But why do it that way? That's what diskdump_get_phys_base() and
kdump_get_phys_base() are supposed to do.
Because I believe that this is the *common* place to do it either for
diskdump, or kdump ( or even a live system if we know kimage_voffset.)
> break;
>
> case POST_GDB:
> @@ -409,6 +471,8 @@ arm64_dump_machdep_table(ulong arg)
> fprintf(fp, "%sIRQ_STACKS", others++ ? "|" : "");
> if (machdep->flags & MACHDEP_BT_TEXT)
> fprintf(fp, "%sMACHDEP_BT_TEXT", others++ ? "|" :
"");
> + if (machdep->flags & NEW_VMEMMAP)
> + fprintf(fp, "%sNEW_VMEMMAP", others++ ? "|" : "");
> fprintf(fp, ")\n");
>
> fprintf(fp, " kvbase: %lx\n", machdep->kvbase);
> @@ -494,6 +558,8 @@ arm64_dump_machdep_table(ulong arg)
> ms = machdep->machspec;
>
> fprintf(fp, " machspec: %lx\n", (ulong)ms);
> + fprintf(fp, " memory map layout: %s\n",
> + (machdep->flags & NEW_VMEMMAP) ? "new" : "old");
As before, these internal "help" structure dumps just show existing structure
fields,
and NEW_VMMEMAP is already shown in the flags.
I put it as useful information for those people who might have got
any concerns about those odd numbers/kernel layout.
But if you don't like it, I will remove it.
> fprintf(fp, " VA_BITS: %ld\n", ms->VA_BITS);
> fprintf(fp, " userspace_top: %016lx\n", ms->userspace_top);
> fprintf(fp, " page_offset: %016lx\n", ms->page_offset);
> @@ -503,6 +569,11 @@ arm64_dump_machdep_table(ulong arg)
> fprintf(fp, " modules_end: %016lx\n", ms->modules_end);
> fprintf(fp, " vmemmap_vaddr: %016lx\n", ms->vmemmap_vaddr);
> fprintf(fp, " vmemmap_end: %016lx\n", ms->vmemmap_end);
> + if (machdep->flags & NEW_VMEMMAP) {
> + fprintf(fp, " kimage_text: %016lx\n", ms->kimage_text);
> + fprintf(fp, " kimage_end: %016lx\n", ms->kimage_end);
> + fprintf(fp, " kimage_voffset: %016lx\n",
ms->kimage_voffset);
> + }
> fprintf(fp, " phys_offset: %lx\n", ms->phys_offset);
> fprintf(fp, "__exception_text_start: %lx\n",
ms->__exception_text_start);
> fprintf(fp, " __exception_text_end: %lx\n",
ms->__exception_text_end);
> @@ -543,6 +614,42 @@ arm64_dump_machdep_table(ulong arg)
> }
> }
>
> +static int
> +arm64_parse_machdep_arg_l(char *argstring, char *param, ulong *value)
> +{
> + int len;
> + int megabytes = FALSE;
> + char *p;
> +
> + len = strlen(param);
> + if (!STRNEQ(argstring, param) || (argstring[len] != '='))
> + return FALSE;
> +
> + if ((LASTCHAR(argstring) == 'm') ||
> + (LASTCHAR(argstring) == 'M')) {
> + LASTCHAR(argstring) = NULLCHAR;
> + megabytes = TRUE;
> + }
> +
> + p = argstring + len + 1;
> + if (strlen(p)) {
> + int flags = RETURN_ON_ERROR | QUIET;
> + int err = 0;
> +
> + if (megabytes) {
> + *value = dtol(p, flags, &err);
> + if (!err)
> + *value = MEGABYTES(*value);
> + } else {
> + *value = htol(p, flags, &err);
> + }
> +
> + if (!err)
> + return TRUE;
> + }
> +
> + return FALSE;
> +}
>
> /*
> * Parse machine dependent command line arguments.
> @@ -554,11 +661,10 @@ arm64_dump_machdep_table(ulong arg)
> static void
> arm64_parse_cmdline_args(void)
> {
> - int index, i, c, err;
> + int index, i, c;
> char *arglist[MAXARGS];
> char buf[BUFSIZE];
> char *p;
> - ulong value = 0;
>
> for (index = 0; index < MAX_MACHDEP_ARGS; index++) {
> if (!machdep->cmdline_args[index])
> @@ -580,39 +686,23 @@ arm64_parse_cmdline_args(void)
> c = parse_line(buf, arglist);
>
> for (i = 0; i < c; i++) {
> - err = 0;
> -
> - if (STRNEQ(arglist[i], "phys_offset=")) {
> - int megabytes = FALSE;
> - int flags = RETURN_ON_ERROR | QUIET;
> -
> - if ((LASTCHAR(arglist[i]) == 'm') ||
> - (LASTCHAR(arglist[i]) == 'M')) {
> - LASTCHAR(arglist[i]) = NULLCHAR;
> - megabytes = TRUE;
> - }
> -
> - p = arglist[i] + strlen("phys_offset=");
> - if (strlen(p)) {
> - if (megabytes)
> - value = dtol(p, flags, &err);
> - else
> - value = htol(p, flags, &err);
> - }
> -
> - if (!err) {
> - if (megabytes)
> - value = MEGABYTES(value);
> -
> - machdep->machspec->phys_offset = value;
> -
> - error(NOTE,
> - "setting phys_offset to: 0x%lx\n\n",
> - machdep->machspec->phys_offset);
> + if (arm64_parse_machdep_arg_l(arglist[i],
> + "phys_offset",
> + &machdep->machspec->phys_offset)) {
> + error(NOTE,
> + "setting phys_offset to: 0x%lx\n\n",
> + machdep->machspec->phys_offset);
> +
> + machdep->flags |= PHYS_OFFSET;
> + continue;
> + } else if (arm64_parse_machdep_arg_l(arglist[i],
> + "kimage_voffset",
> + &machdep->machspec->kimage_voffset)) {
> + error(NOTE,
> + "setting kimage_voffset to: 0x%lx\n\n",
> + machdep->machspec->kimage_voffset);
>
> - machdep->flags |= PHYS_OFFSET;
> - continue;
> - }
> + continue;
> }
>
> error(WARNING, "ignoring --machdep option: %s\n",
> @@ -627,10 +717,20 @@ arm64_calc_phys_offset(void)
> {
> struct machine_specific *ms = machdep->machspec;
> ulong phys_offset;
> + struct syment *sp;
> + ulong value;
>
> if (machdep->flags & PHYS_OFFSET) /* --machdep override */
> return;
>
> + sp = kernel_symbol_search("memstart_addr");
> + if (sp && readmem(sp->value, KVADDR, (char *)&value,
sizeof(value),
> + "memstart_addr", QUIET|RETURN_ON_ERROR)) {
> + ms->phys_offset = value;
> + machdep->flags |= PHYS_OFFSET;
> + return;
> + }
> +
Also, I may be missing something, but the PHYS_OFFSET flag means that it was
passed in via --machdep, and is only used in this function to avoid any further
attempts to figure out what it is. Here you are setting the flag for no particular
reason that I can see. Why?
Well, I don't remember very well. If not necessary, I will remove it.
But again, doing a readmem() call this early is setting a bad
precedent -- they have
*always* been delayed until after gdb_session_init() in main_loop(). And the work
of determining phys_base should be done by the dumpfile call-out functions that
already exist.
> /*
> * Next determine suitable value for phys_offset. User can override this
> * by passing valid '--machdep phys_offset=<addr>' option.
> @@ -2377,6 +2477,11 @@ arm64_IS_VMALLOC_ADDR(ulong vaddr)
> {
> struct machine_specific *ms = machdep->machspec;
>
> + if ((machdep->flags & NEW_VMEMMAP) &&
> + (vaddr >= machdep->machspec->kimage_text) &&
> + (vaddr <= machdep->machspec->kimage_end))
> + return FALSE;
> +
> return ((vaddr >= ms->vmalloc_start_addr && vaddr <=
> ms->vmalloc_end) ||
> ((machdep->flags & VMEMMAP) &&
> (vaddr >= ms->vmemmap_vaddr && vaddr <=
ms->vmemmap_end))
> ||
> @@ -2407,7 +2512,11 @@ arm64_calc_VA_BITS(void)
>
> for (bitval = highest_bit_long(value); bitval; bitval--) {
> if ((value & (1UL << bitval)) == 0) {
> +#if 1
> + machdep->machspec->VA_BITS = bitval + 1;
> +#else /* FIXME: bug? */
> machdep->machspec->VA_BITS = bitval + 2;
> +#endif
> break;
> }
> }
Again, a non-starter until the above is resolved -- but you know that already...
Just a reminder for now.
> @@ -2459,10 +2568,22 @@ arm64_calc_virtual_memory_ranges(void)
> break;
> }
>
> - vmemmap_size = ALIGN((1UL << (ms->VA_BITS - machdep->pageshift)) *
> SIZE(page), PUD_SIZE);
> + if (machdep->flags & NEW_VMEMMAP)
> +#define STRUCT_PAGE_MAX_SHIFT 6
> + vmemmap_size = 1UL << (ms->VA_BITS - machdep->pageshift - 1
> + + STRUCT_PAGE_MAX_SHIFT);
> + else
> + vmemmap_size = ALIGN((1UL << (ms->VA_BITS - machdep->pageshift)) *
> SIZE(page), PUD_SIZE);
> +
> vmalloc_end = (ms->page_offset - PUD_SIZE - vmemmap_size - SZ_64K);
> - vmemmap_start = vmalloc_end + SZ_64K;
> - vmemmap_end = vmemmap_start + vmemmap_size;
> +
> + if (machdep->flags & NEW_VMEMMAP) {
> + vmemmap_start = ms->page_offset - vmemmap_size;
> + vmemmap_end = ms->page_offset;
> + } else {
> + vmemmap_start = vmalloc_end + SZ_64K;
> + vmemmap_end = vmemmap_start + vmemmap_size;
> + }
>
> ms->vmalloc_end = vmalloc_end - 1;
> ms->vmemmap_vaddr = vmemmap_start;
> diff --git a/defs.h b/defs.h
> index a09fa9a..2bbb55b 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -2844,8 +2844,8 @@ typedef u64 pte_t;
>
> #define PTOV(X) \
> ((unsigned
>
long)(X)-(machdep->machspec->phys_offset)+(machdep->machspec->page_offset))
> -#define VTOP(X) \
> - ((unsigned
>
long)(X)-(machdep->machspec->page_offset)+(machdep->machspec->phys_offset))
> +
> +#define VTOP(X) arm64_VTOP((ulong)(X))
>
> #define USERSPACE_TOP (machdep->machspec->userspace_top)
> #define PAGE_OFFSET (machdep->machspec->page_offset)
> @@ -2938,18 +2938,23 @@ typedef signed int s32;
> #define VM_L3_4K (0x10)
> #define KDUMP_ENABLED (0x20)
> #define IRQ_STACKS (0x40)
> +#define NEW_VMEMMAP (0x80)
>
> /*
> * sources: Documentation/arm64/memory.txt
> * arch/arm64/include/asm/memory.h
> * arch/arm64/include/asm/pgtable.h
> */
> -
> -#define ARM64_PAGE_OFFSET ((0xffffffffffffffffUL) <<
> (machdep->machspec->VA_BITS - 1))
> +#define ARM64_VA_START ((0xffffffffffffffffUL) \
> + << machdep->machspec->VA_BITS)
> +#define ARM64_PAGE_OFFSET ((0xffffffffffffffffUL) \
> + << (machdep->machspec->VA_BITS - 1))
> #define ARM64_USERSPACE_TOP ((1UL) << machdep->machspec->VA_BITS)
> -#define ARM64_MODULES_VADDR (ARM64_PAGE_OFFSET - MEGABYTES(64))
> -#define ARM64_MODULES_END (ARM64_PAGE_OFFSET - 1)
> -#define ARM64_VMALLOC_START ((0xffffffffffffffffUL) <<
machdep->machspec->VA_BITS)
> +
> +/* only used for v4.6 or later */
> +#define ARM64_MODULES_VSIZE MEGABYTES(128)
> +#define ARM64_KASAN_SHADOW_SIZE (1UL << (machdep->machspec->VA_BITS -
3))
> +
> /*
> * The following 3 definitions are the original values, but are obsolete
> * for 3.17 and later kernels because they are now build-time calculations.
> @@ -3028,6 +3033,10 @@ struct machine_specific {
> ulong kernel_flags;
> ulong irq_stack_size;
> ulong *irq_stacks;
> + /* only needed for kaslr-enabled kernel */
> + ulong kimage_voffset;
> + ulong kimage_text;
> + ulong kimage_end;
> };
The comment is wrong -- the kimage_text and kimage_end values are needed for
NEW_VMEMMAP kernels that are NOT configured with CONFIG_RANDOMIZE_BASE.
Unless you consider my live system "kaslr-enabled"?
I will change it to "for v4.6 or later".
I have limited (or no) time to investigate a live-system case, and so if
you have any suggestions or your own patch, it is very much appreciated.
Thanks,
-Takahiro AKASHI
>
> struct arm64_stackframe {
> @@ -5385,6 +5394,7 @@ void unwind_backtrace(struct bt_info *);
> #ifdef ARM64
> void arm64_init(int);
> void arm64_dump_machdep_table(ulong);
> +ulong arm64_VTOP(ulong);
> int arm64_IS_VMALLOC_ADDR(ulong);
> ulong arm64_swp_type(ulong);
> ulong arm64_swp_offset(ulong);
> diff --git a/main.c b/main.c
> index 821bb4e..3f24908 100644
> --- a/main.c
> +++ b/main.c
> @@ -227,9 +227,10 @@ main(int argc, char **argv)
> optarg);
> }
> } else if (STREQ(long_options[option_index].name, "kaslr")) {
> - if (!machine_type("X86_64"))
> - error(INFO, "--kaslr only valid "
> - "with X86_64 machine type.\n");
> + if (!machine_type("X86_64") &&
> + !machine_type("ARM64"))
> + error(INFO, "--kaslr not valid "
> + "with this machine type.\n");
> else if (STREQ(optarg, "auto"))
> kt->flags2 |= (RELOC_AUTO|KASLR);
> else {
> diff --git a/symbols.c b/symbols.c
> index a8d3563..df27793 100644
> --- a/symbols.c
> +++ b/symbols.c
> @@ -593,7 +593,8 @@ kaslr_init(void)
> {
> char *string;
>
> - if (!machine_type("X86_64") || (kt->flags & RELOC_SET))
> + if ((!machine_type("X86_64") &&
!machine_type("ARM64")) ||
> + (kt->flags & RELOC_SET))
> return;
>
> /*
> @@ -712,7 +713,7 @@ store_symbols(bfd *abfd, int dynamic, void *minisyms,
> long symcount,
> if (machine_type("X86")) {
> if (!(kt->flags & RELOC_SET))
> kt->flags |= RELOC_FORCE;
> - } else if (machine_type("X86_64")) {
> + } else if (machine_type("X86_64") || machine_type("ARM64")) {
> if ((kt->flags2 & RELOC_AUTO) && !(kt->flags & RELOC_SET))
> derive_kaslr_offset(abfd, dynamic, from,
> fromend, size, store);
> @@ -783,7 +784,8 @@ store_sysmap_symbols(void)
> error(FATAL, "symbol table namespace malloc: %s\n",
> strerror(errno));
>
> - if (!machine_type("X86") && !machine_type("X86_64"))
> + if (!machine_type("X86") && !machine_type("X86_64")
&&
> + !machine_type("ARM64"))
> kt->flags &= ~RELOC_SET;
>
> first = 0;
> @@ -4681,7 +4683,7 @@ value_search(ulong value, ulong *offset)
> if ((sp = machdep->value_to_symbol(value, offset)))
> return sp;
>
> - if (IS_VMALLOC_ADDR(value))
> + if (IS_VMALLOC_ADDR(value))
> goto check_modules;
>
> if ((sp = symval_hash_search(value)) == NULL)
> --
> 2.8.1
>
> --
Looking better, still a ways to go...
Thanks,
Dave
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--
Thanks,
-Takahiro AKASHI
9:28 a.m.
----- Original Message -----
On Tue, May 24, 2016 at 01:59:06PM -0400, Dave Anderson wrote:
>
> ----- Original Message -----
> > Yet some issues, but ...
> >
>
> Hi Takahiro,
>
> Here are my general comments on my testing of the v2 patch, followed
> by a few comments in the patch itself.
Thank you for your quick review/testing, again.
> First, the combination of the new memory map layout and KASLR is somewhat
> confusing. I am testing your patch on a 4.6.0-0.rc7.git2.1.fc25 kernel
> that has this configuration:
Right. I use the "kaslr kernel" or "kaslr-enabled kernel" in two
meanings (almost interchangeably):
- kernel with a new memory map, that is v4.6 or later
- kernel that has ability of KASLR (configured with CONFIG_RANDOMIZE_RAM)
When we talked offline, you mentioned the possibility of backporting
KASLR to older kernel, so I hesitated to use "v4.6 or later".
But I think that we'd better use "v4.6 or later" for a clarification
for now.
Actually I was thinking more along the lines of the new vmemmap stuff
being backported. But it looks like that would be impossible without
also bringing along "kimage_voffset".
> config-arm64:# CONFIG_RANDOMIZE_BASE is not set
>
> So KASLR doesn't really enter into the picture. But when bringing
> up the crash session, it shows the "kaslr kernel" WARNING:
>
> # ./crash
>
> crash 7.1.5++
> Copyright (C) 2002-2016 Red Hat, Inc.
> Copyright (C) 2004, 2005, 2006, 2010 IBM Corporation
> Copyright (C) 1999-2006 Hewlett-Packard Co
> Copyright (C) 2005, 2006, 2011, 2012 Fujitsu Limited
> Copyright (C) 2006, 2007 VA Linux Systems Japan K.K.
> Copyright (C) 2005, 2011 NEC Corporation
> Copyright (C) 1999, 2002, 2007 Silicon Graphics, Inc.
> Copyright (C) 1999, 2000, 2001, 2002 Mission Critical Linux, Inc.
> This program is free software, covered by the GNU General Public License,
> and you are welcome to change it and/or distribute copies of it under
> certain conditions. Enter "help copying" to see the conditions.
> This program has absolutely no warranty. Enter "help warranty" for
> details.
>
> WARNING: kimage_voffset not identified for kaslr kernel
> GNU gdb (GDB) 7.6
> Copyright (C) 2013 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later
> <http://gnu.org/licenses/gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law. Type "show
> copying"
> and "show warranty" for details.
> This GDB was configured as "aarch64-unknown-linux-gnu"...
>
> KERNEL:
> /usr/lib/debug/lib/modules/4.6.0-0.rc7.git2.1.fc25.aarch64/vmlinux
> DUMPFILE: /dev/crash
> CPUS: 8
> DATE: Tue May 24 10:08:08 2016
> UPTIME: 11 days, 18:32:41
> LOAD AVERAGE: 0.17, 0.09, 0.12
> TASKS: 197
> NODENAME: apm-mustang-ev3-36.khw.lab.eng.bos.redhat.com
> RELEASE: 4.6.0-0.rc7.git2.1.fc25.aarch64
> VERSION: #1 SMP Thu May 12 13:28:43 UTC 2016
> MACHINE: aarch64 (unknown Mhz)
> MEMORY: 16 GB
> PID: 7556
> COMMAND: "crash"
> TASK: fffffe00beb45400 [THREAD_INFO: fffffe00beb98000]
> CPU: 7
> STATE: TASK_RUNNING (ACTIVE)
>
> crash>
>
> Why show that WARNING in this case? I understant that it's not
> stashed during early initialization:
If we don't know kimage_voffset, we can't analyze the contents of
memory (live or kdump).
I understand. But clearly that's not the case with my system above that
does not have CONFIG_RANDOMIZE_BASE configured, so the warning message
is nonsensical/confusing. That's why I was speculating about perhaps
having kdump export a VMCOREINFO_CONFIG(RANDOMIZE_BASE) so that it is
readily apparent.
> crash> help -m
> flags: 104000c5
>
(KSYMS_START|VM_L2_64K|VMEMMAP|IRQ_STACKS|MACHDEP_BT_TEXT|NEW_VMEMMAP)
> ... [ cut ] ...
> memory map layout: new <--- BTW, this is
> redundant/not-a-member, and we've got NEW_VMEMMAP
> VA_BITS: 42
> userspace_top: 0000040000000000
> page_offset: fffffe0000000000
> vmalloc_start_addr: fffffc0008000000
> vmalloc_end: fffffdff5ffeffff
> modules_vaddr: fffffc0000000000
> modules_end: fffffc0007ffffff
> vmemmap_vaddr: fffffdff80000000
> vmemmap_end: fffffdffffffffff
> kimage_text: fffffc0008080000
> kimage_end: fffffc0009070000
> kimage_voffset: 0000000000000000 <-- available if kernel is
> not randomized
> phys_offset: 4000000000
> ...
>
> But it can be read:
>
> crash> px kimage_voffset
> kimage_voffset = $1 = 0xfffffbc008000000
> crash>
>
> SO because it wasn't determined during session initialization,
> it falls into the "no randomness" section of arm64_VTOP():
Exactly.
> ulong
> arm64_VTOP(ulong addr)
> {
> if (!(machdep->flags & NEW_VMEMMAP) ||
> (addr >= machdep->machspec->page_offset)) {
> return machdep->machspec->phys_offset
> + (addr - machdep->machspec->page_offset);
> } else {
> if (machdep->machspec->kimage_voffset)
> return addr - machdep->machspec->kimage_voffset;
> else /* no randomness */
> return machdep->machspec->phys_offset
> + (addr -
> machdep->machspec->vmalloc_start_addr);
> }
> }
>
> That works, but if "kimage_offset" can be read normally later on, perhaps
it
> should update "machdep->machspec->kimage_voffset" at that time?
It is possible, but the check in arm64_VTOP() would be still necessary.
Agreed...
> There are some discrepancies with respect to the calculated addresses
> and what is seen by looking at the reported memory map in the kernel log:
>
> [ 0.000000] Virtual kernel memory layout:
> [ 0.000000] modules : 0xfffffc0000000000 - 0xfffffc0008000000 (
> 128 MB)
> [ 0.000000] vmalloc : 0xfffffc0008000000 - 0xfffffdfedfff0000 (
> 2043 GB)
> [ 0.000000] .text : 0xfffffc0008080000 - 0xfffffc0008890000 (
> 8256 KB)
> .rodata : 0xfffffc0008890000 - 0xfffffc0008c10000 (
> 3584 KB)
> .init : 0xfffffc0008c10000 - 0xfffffc0008d50000 (
> 1280 KB)
> .data : 0xfffffc0008d50000 - 0xfffffc0008eaac00 (
> 1387 KB)
> [ 0.000000] vmemmap : 0xfffffdfee0000000 - 0xfffffdffe0000000 (
> 4 GB maximum)
> 0xfffffdfee0000000 - 0xfffffdfee1000000 (
> 16 MB actual)
> [ 0.000000] fixed : 0xfffffdfffe7d0000 - 0xfffffdfffec00000 (
> 4288 KB)
> [ 0.000000] PCI I/O : 0xfffffdfffee00000 - 0xfffffdffffe00000 (
> 16 MB)
> [ 0.000000] memory : 0xfffffe0000000000 - 0xfffffe0400000000 (
> 16384 MB)
>
> Comparing it to the calculated values:
>
> VA_BITS: 42
> userspace_top: 0000040000000000
> page_offset: fffffe0000000000 OK
> vmalloc_start_addr: fffffc0008000000 OK
> vmalloc_end: fffffdff5ffeffff ? (seems wrong)
> modules_vaddr: fffffc0000000000 OK
> modules_end: fffffc0007ffffff OK (-1)
> vmemmap_vaddr: fffffdff80000000 ? (seems wrong)
> vmemmap_end: fffffdffffffffff ? (seems wrong)
> kimage_text: fffffc0008080000 OK
> kimage_end: fffffc0009070000 OK
> kimage_voffset: 0000000000000000
> phys_offset: 4000000000
>
> Starting with vmalloc_start_addr/vmalloc_end, if I run "kmem -v" to dump
> the
> vmalloc allocations, there are some allocations that are below the
> 0xfffffc0008000000 start value shown in the log and by your calcuation.
> I'm not clear on what that means?:
>
> crash> kmem -v
> VMAP_AREA VM_STRUCT ADDRESS RANGE
> SIZE
> fffffe03daefd900 fffffe03daefd880 fffffc0000c10000 - fffffc0000c30000
> 131072
> fffffe00bf2c3a00 fffffe00bf2c3980 fffffc0000c90000 - fffffc0000cb0000
> 131072
> fffffe00bf2c7400 fffffe00bf2c7380 fffffc0000d50000 - fffffc0000d70000
> 131072
> fffffe03dc76aa00 fffffe03dc76a980 fffffc0000d90000 - fffffc0000db0000
> 131072
> fffffe03dc76be00 fffffe03dc76bd80 fffffc0000dd0000 - fffffc0000ee0000
> 1114112
> fffffe03d90e7900 fffffe03d90e7b80 fffffc0000f40000 - fffffc0000fb0000
> 458752
> fffffe00bec12f00 fffffe00bec12b00 fffffc0000fe0000 - fffffc0001000000
> 131072
> fffffe00bf3a1100 fffffe00bf3a1080 fffffc0001020000 - fffffc0001050000
> 196608
> fffffe00bf3a3280 fffffe00bf3a3200 fffffc0001070000 - fffffc0001090000
> 131072
> fffffe03ddf7fc00 fffffe03ddf7a880 fffffc0001230000 - fffffc0001250000
> 131072
> fffffe03fd508900 fffffe03fd508880 fffffc0008000000 - fffffc0008020000
> 131072
> fffffe03fd509580 fffffe03fd508d00 fffffc0008020000 - fffffc0008040000
> 131072
> fffffe03fd508a00 fffffe03fd508980 fffffc0008040000 - fffffc0008070000
> 196608
> ... [ cut ] ...
> fffffe03d7235000 fffffe03d7233480 fffffc0014b30000 - fffffc0014b50000
> 131072
> fffffe00b921e700 fffffe00b921df00 fffffc0014b70000 - fffffc0014b90000
> 131072
> fffffe00b851eb00 fffffe00b8512900 fffffdfedfcf0000 - fffffdfedfe70000
> 1572864
> fffffe03dca4ef00 fffffe03dca4ef80 fffffdfedfe70000 - fffffdfedfff0000
> 1572864
> crash>
>
> Although the end value of fffffdfedfff0000 does match up with the value in
> the
> kernel log, your calculation is 2GB higher at fffffdff5ffeffff:
>
> crash> eval fffffdff5ffeffff - 0xfffffdfedfff0000
> hexadecimal: 7fffffff
> decimal: 2147483647
> octal: 17777777777
> binary:
> 0000000000000000000000000000000001111111111111111111111111111111
> crash> eval 7fffffff + 1
> hexadecimal: 80000000 (2GB)
> decimal: 2147483648
> octal: 20000000000
> binary:
> 0000000000000000000000000000000010000000000000000000000000000000
> crash>
>
> With respect to the vmemmap range, vmmemap address in the log file is the
> one
> that is displayed by "kmem -p":
>
> crash> kmem -p
> PAGE PHYSICAL MAPPING INDEX CNT FLAGS
> fffffdfee0000000 4000000000 fffffe03fd441950 2f 1 1002c
> referenced,uptodate,lru,mappedtodisk
> fffffdfee0000040 4000010000 fffffe03fd441950 30 1 1002c
> referenced,uptodate,lru,mappedtodisk
> fffffdfee0000080 4000020000 fffffe03fd441950 31 1 1002c
> referenced,uptodate,lru,mappedtodisk
> fffffdfee00000c0 4000030000 fffffe03fd441950 32 1 1002c
> referenced,uptodate,lru,mappedtodisk
> ...
> fffffdfee0ffff00 43fffc0000 0 0 1
> 4000000000000400 reserved
> fffffdfee0ffff40 43fffd0000 0 0 1
> 4000000000000400 reserved
> fffffdfee0ffff80 43fffe0000 0 0 1
> 4000000000000400 reserved
> fffffdfee0ffffc0 43ffff0000 0 0 1
> 4000000000000400 reserved
> crash>
>
> And "kmem" alone recognizes it:
>
> crash> kmem fffffdfee0000000
> PAGE PHYSICAL MAPPING INDEX CNT FLAGS
> fffffdfee0000000 4000000000 fffffe03fd441950 2f 1 1002c
> referenced,uptodate,lru,mappedtodisk
> crash>
>
> But your calculated vmemmap_vaddr above doesn't seem right:
>
> crash> kmem fffffdff80000000
> kmem: WARNING: cannot make virtual-to-physical translation:
> fffffdff80000000
> fffffdff80000000: kernel virtual address not found in mem map
> crash>
>
> Do your numbers match up on a dump that actually has CONFIG_RANDOMIZE_BASE?
In my environment, the numbers above match up on a dump whether
CONFIG_RANDOMIZE_BASE is enabled or not.
Are you using a mainline kernel (final v4.6, not -rcX)?
Good point. When I configured my arm64 test system, I installed the latest
Fedora kernel available at the time (4.6.0-0.rc7.git2.1.fc25), but it is based
upon linux-4.5.tar.xz. I see now that there is a kernel-4.6.0-1.fc25 available
that is based upon linux-4.6.tar.xz. I'll update the system.
> Anyway, onto the patch...
>
> >
> > changes in v2:
> > * Fixed build warnings
> > * Moved ARM64_NEW_VMEMMAP to machdep->flags
> > * Show additional kaslr-related parameters in arm64_dump_machdep_table()
> > * Handle a VMCOREINFO, "NUMBER(kimage_voffset)"
> >
> > ===8<===
> > >From 080a54ec232ac48ef2d8123cbedcf0f1fe27e391 Mon Sep 17 00:00:00 2001
> > From: AKASHI Takahiro <takahiro.akashi(a)linaro.org>
> > Date: Mon, 16 May 2016 17:31:55 +0900
> > Subject: [PATCH v2] arm64: fix kernel memory map handling for
> > kaslr-enabled
> > kernel
> >
> > In kernel v4.6, Kernel ASLR (KASLR) is supported on arm64, and the start
> > address of the kernel image can be randomized if CONFIG_RANDOMIZE_BASE is
> > enabled.
> > Even worse, the kernel image is no more mapped in the linear mapping, but
> > in vmalloc area (i.e. below PAGE_OFFSET).
> >
> > Now, according to the kernel's memory.h, converting a virtual address to
> > a physical address should be done like below:
> >
> > phys_addr_t __x = (phys_addr_t)(x); \
> > __x & BIT(VA_BITS - 1) ? (__x & ~PAGE_OFFSET) + PHYS_OFFSET : \
> > (__x - kimage_voffset); })
> >
> > Please note that PHYS_OFFSET is no more equal to the start address of
> > the first usable memory block in SYSTEM RAM due to the fact mentioned
> > above.
> >
> > This patch addresses this change and allows the crash utility to access
> > memory contents with correct addresses.
> > *However*, it is still rough-edged and we need more refinements.
> >
> > 1-1) On a live system, crash with this patch won't work because
> > we currently have no way to know kimage_voffset.
> >
> > 1-2) For a core dump file, we can do simply:
> > $ crash <vmlinux> <vmcore>
> > as long as the file has "NUMBER(kimage_voffset)"
> > (RELOC_AUTO|KASLR is automatically set.)
> >
> > I'm planning to add this enhancement in my next version of kexec/kdump
> > patch, i.e. v17.
> >
> > 2) My current change breaks the backward compatibility.
> > Crash won't work with v4.5 or early kernel partly because I changed
> > the calculation of VA_BITS. (I think that the existing code is wrong.)
> > So far I don't have enough time to look into this issue as I'm
> > focusing
> > on KASLR support.
>
> OK, but you still haven't shown how the current VA_BITS determination is
> not a correct representation of CONFIG_ARM64_VA_BITS.
At least, the current VA_BITS doesn't work with my calculations, which
were derived directly from v4.6's "asm/memory.h".
What are your kernel's PAGE_OFFSET value and CONFIG_ARM64_VA_BITS value?
> > 3) Backtracing a 'panic'ed task fails:
> > crash> bt
> > PID: 999 TASK: ffffffe960081800 CPU: 0 COMMAND: "sh"
> > bt: WARNING: corrupt prstatus? pstate=0x80000000, but no user frame
> > found
> > bt: WARNING: cannot determine starting stack frame for task
> > ffffffe960081800
> >
> > frame->pc indicates that it is a kernel address, so obviously something
> > is wrong. I'm diggin into it.
>
> Can you add a debug statement that displays frame->pc, frame->sp, and
> frame->fp?
I've already identified the cause.
pt_regs->pstate was set mistakenly from "sprsr_el1" in panic().
But I have a difficulty here to fix the problem as we have no direct way
to retrieve a value of the *current* PSTATE.
Interesting. I don't know what you mean by "sprsr_el1" in panic(), but
I just got a report from my github "issues", where the user injected a panic()
call into a kernel module and got the same error as above because of the pstate
value. I asked him to put this hack into arm64.c:
--- a/arm64.c
+++ b/arm64.c
@@ -1711,11 +1711,14 @@ arm64_get_dumpfile_stackframe(struct bt_info *bt, struct
arm64_stackframe *frame
error(WARNING,
"corrupt prstatus? pstate=0x%lx, but no user frame
found\n",
ptregs->pstate);
+ if (INSTACK(frame->sp, bt) && INSTACK(frame->fp,
bt))
+ goto try_kernel;
bt->flags |= BT_REGS_NOT_FOUND;
return FALSE;
}
bt->flags |= BT_USER_SPACE;
} else {
+try_kernel:
frame->sp = ptregs->sp;
frame->fp = ptregs->regs[29];
}
Can you give that a shot?
>
> > Signed-off-by: AKASHI Takahiro <takahiro.akashi(a)linaro.org>
> > ---
> > arm64.c | 217
> > ++++++++++++++++++++++++++++++++++++++++++++++++--------------
> > defs.h | 24 +++++--
> > main.c | 7 +-
> > symbols.c | 10 +--
> > 4 files changed, 196 insertions(+), 62 deletions(-)
> >
> > diff --git a/arm64.c b/arm64.c
> > index 34c8c59..6b97093 100644
> > --- a/arm64.c
> > +++ b/arm64.c
> > @@ -72,6 +72,21 @@ static int arm64_get_crash_notes(void);
> > static void arm64_calc_VA_BITS(void);
> > static int arm64_is_uvaddr(ulong, struct task_context *);
> >
> > +ulong
> > +arm64_VTOP(ulong addr)
> > +{
> > + if (!(machdep->flags & NEW_VMEMMAP) ||
> > + (addr >= machdep->machspec->page_offset)) {
> > + return machdep->machspec->phys_offset
> > + + (addr - machdep->machspec->page_offset);
> > + } else {
> > + if (machdep->machspec->kimage_voffset)
> > + return addr - machdep->machspec->kimage_voffset;
> > + else /* no randomness */
> > + return machdep->machspec->phys_offset
> > + + (addr - machdep->machspec->vmalloc_start_addr);
> > + }
> > +}
> >
> > /*
> > * Do all necessary machine-specific setup here. This is called several
> > times
> > @@ -81,6 +96,7 @@ void
> > arm64_init(int when)
> > {
> > ulong value;
> > + char *string;
> > struct machine_specific *ms;
> >
> > #if defined(__x86_64__)
> > @@ -102,9 +118,34 @@ arm64_init(int when)
> > if (machdep->cmdline_args[0])
> > arm64_parse_cmdline_args();
> > machdep->flags |= MACHDEP_BT_TEXT;
> > +
> > + ms = machdep->machspec;
> > + if (!ms->kimage_voffset &&
> > + (string = pc->read_vmcoreinfo("NUMBER(kimage_voffset)")))
{
> > + ms->kimage_voffset = htol(string, QUIET, NULL);
> > + free(string);
> > + }
>
> It doesn't make sense to call pc->read_vmcoreinfo() if !DUMPFILE().
Do you think so?
By default, pc->read_vmcoreinfo is set to no_vmcoreinfo.
So it doesn't hurt anything.
Right, just a suggestion...
> > +
> > + if (ms->kimage_voffset) {
> > + machdep->flags |= NEW_VMEMMAP;
> > +
> > + /* if not specified in command line */
> > + if (!kt->relocate && !(kt->flags2 & (RELOC_AUTO|KASLR)))
> > + kt->flags2 |= (RELOC_AUTO|KASLR);
> > + }
> > +
>
> If CONFIG_RANDOMIZE_BASE is NOT set, should RELOC_AUTO|KASLR be set? They
> don't get set on my live system.
Not necessarily, but the current implementation of derive_kaslr_offset()
just works even in this case.
Ahah -- cool!
(This is the reason that I don't think we need a VMCOREINFO for
CONFIG_RANDOMIZE_BASE.)
Well, as long as there's a way to avoid that unnecessary/confusing
warning message for non-KASLR new-vmemmap kernels.
I also wonder whether makedumpfile could use it?
> > break;
> >
> > case PRE_GDB:
> > + /* This check is somewhat redundant */
> > + if (kernel_symbol_exists("kimage_voffset")) {
> > + machdep->flags |= NEW_VMEMMAP;
> > +
> > + if (!machdep->machspec->kimage_voffset)
> > + error(WARNING,
> > + "kimage_voffset not identified for kaslr kernel\n");
> > + }
> > +
>
> As mentioned in the general discussion above, the WARNING above makes
> no sense if CONFIG_RANDOMIZE_BASE is not configured.
What about if I change the message "for v4.6 or later kernel"?
But again, I do not want the message at all if it's not applicable.
Worse case, you could set a flag, and then if/when the crash session
ultimately craps out if it can't figure things out, then the message
could be displayed post-mortem.
> I'm now thinking that CONFIG_RANDOMIZE_BASE (and maybe
others like KASAN?)
> should be passed in the dumpfile with VMCOREINFO_CONFIG().
Regarding KASAN, we only need to check for an existence of "kasan_init"
symbol as you recommended before :)
Nice.
>
> > if (!machdep->pagesize) {
> > /*
> > * Kerneldoc Documentation/arm64/booting.txt describes
> > @@ -160,16 +201,35 @@ arm64_init(int when)
> > machdep->pagemask = ~((ulonglong)machdep->pageoffset);
> >
> > arm64_calc_VA_BITS();
> > - machdep->machspec->page_offset = ARM64_PAGE_OFFSET;
> > + ms = machdep->machspec;
> > + ms->page_offset = ARM64_PAGE_OFFSET;
> > + /* FIXME: idmap for NEW_VMEMMAP */
> > machdep->identity_map_base = ARM64_PAGE_OFFSET;
> > - machdep->machspec->userspace_top = ARM64_USERSPACE_TOP;
> > - machdep->machspec->modules_vaddr = ARM64_MODULES_VADDR;
> > - machdep->machspec->modules_end = ARM64_MODULES_END;
> > - machdep->machspec->vmalloc_start_addr = ARM64_VMALLOC_START;
> > - machdep->machspec->vmalloc_end = ARM64_VMALLOC_END;
> > - machdep->kvbase = ARM64_VMALLOC_START;
> > - machdep->machspec->vmemmap_vaddr = ARM64_VMEMMAP_VADDR;
> > - machdep->machspec->vmemmap_end = ARM64_VMEMMAP_END;
> > + machdep->kvbase = ARM64_VA_START;
> > + ms->userspace_top = ARM64_USERSPACE_TOP;
> > + if (machdep->flags & NEW_VMEMMAP) {
> > + struct syment *sp;
> > +
> > + sp = kernel_symbol_search("_text");
> > + ms->kimage_text = (sp ? sp->value : 0);
> > + sp = kernel_symbol_search("_end");
> > + ms->kimage_end = (sp ? sp->value : 0);
> > +
> > + ms->modules_vaddr = ARM64_VA_START;
> > + if (kernel_symbol_exists("kasan_init"))
> > + ms->modules_vaddr += ARM64_KASAN_SHADOW_SIZE;
> > + ms->modules_end = ms->modules_vaddr
> > + + ARM64_MODULES_VSIZE -1;
> > +
> > + ms->vmalloc_start_addr = ms->modules_end + 1;
> > + } else {
> > + ms->modules_vaddr = ARM64_PAGE_OFFSET - MEGABYTES(64);
> > + ms->modules_end = ARM64_PAGE_OFFSET - 1;
> > + ms->vmalloc_start_addr = ARM64_VA_START;
> > + }
> > + ms->vmalloc_end = ARM64_VMALLOC_END;
> > + ms->vmemmap_vaddr = ARM64_VMEMMAP_VADDR;
> > + ms->vmemmap_end = ARM64_VMEMMAP_END;
> >
> > switch (machdep->pagesize)
> > {
> > @@ -232,8 +292,6 @@ arm64_init(int when)
> > machdep->stacksize = ARM64_STACK_SIZE;
> > machdep->flags |= VMEMMAP;
> >
> > - arm64_calc_phys_offset();
> > -
> > machdep->uvtop = arm64_uvtop;
> > machdep->kvtop = arm64_kvtop;
> > machdep->is_kvaddr = generic_is_kvaddr;
> > @@ -262,6 +320,10 @@ arm64_init(int when)
> > machdep->dumpfile_init = NULL;
> > machdep->verify_line_number = NULL;
> > machdep->init_kernel_pgd = arm64_init_kernel_pgd;
> > +
> > + /* use machdep parameters */
> > + arm64_calc_phys_offset();
> > +
>
> This doesn't make any sense to me. I understand you've done it because
> you are now doing a readmem() in arm64_calc_phys_offset(). But readmem()
> calls are never done this early. And in fact, on the live system the
> readmem() in arm64_calc_phys_offset() fails like so (running "crash
-d4"):
>
> <readmem: fffffc0008d70bb0, KVADDR, "memstart_addr", 8, (ROE|Q),
> 3ffcc2842c0>
> <read_memory_device: addr: fffffc0008d70bb0 paddr: d70bb0 cnt: 8>
> crash: read error: kernel virtual address: fffffc0008d70bb0 type:
> "memstart_addr"
>
> It fails above because it needs the phys_base in order to do the readmem().
> During
> runtime it has it:
This is because we don't know kimage_voffset on a live system.
(and so I mentioned this issue in my commit log.)
Right -- which is a good reason for NOT using readmem() at that point
in time. I can also envision a scenario where readmem() may inadvertently
"work" (i.e. depending upon where phys_base really is), and then return
something bogus from an unintended location.
As far as kdump case is concerned, readmem() at this point just
works
for any address in kernel image. This is my intentional use of this function.
I understand, but you're subverting the subsequent dumpfile-specific
calls later in the function. It is precisely *their* responsibility
to return the value of phys_offset.
> crash> set debug 4
> debug: 4
> crash> rd memstart_addr
> <addr: fffffc0008d70bb0 count: 1 flag: 490 (KVADDR)>
> <readmem: fffffc0008d70bb0, KVADDR, "64-bit KVADDR", 8, (FOE),
> 3ffcbfbfc28>
> <read_memory_device: addr: fffffc0008d70bb0 paddr: 4000d70bb0 cnt: 8>
> fffffc0008d70bb0: 0000004000000000 ....@...
> crash>
>
> So without kimage_voffset, that readmem(), how would that readmem()
> possibly work?
> You need the *contents* of memstart_addr in order to *read* memstart_addr.
>
> Now, if it kimage_voffset were passed into the vmcore, then I guess you
> could
> read it. But why do it that way? That's what diskdump_get_phys_base() and
> kdump_get_phys_base() are supposed to do.
Because I believe that this is the *common* place to do it either for
diskdump, or kdump ( or even a live system if we know kimage_voffset.)
Well, as I have shown, it won't work on my live system because of the
chicken-and-egg scenario. Let's worry about live system analysis after
we get kdump straightened out.
>
> > break;
> >
> > case POST_GDB:
> > @@ -409,6 +471,8 @@ arm64_dump_machdep_table(ulong arg)
> > fprintf(fp, "%sIRQ_STACKS", others++ ? "|" :
"");
> > if (machdep->flags & MACHDEP_BT_TEXT)
> > fprintf(fp, "%sMACHDEP_BT_TEXT", others++ ? "|" :
"");
> > + if (machdep->flags & NEW_VMEMMAP)
> > + fprintf(fp, "%sNEW_VMEMMAP", others++ ? "|" :
"");
> > fprintf(fp, ")\n");
> >
> > fprintf(fp, " kvbase: %lx\n", machdep->kvbase);
> > @@ -494,6 +558,8 @@ arm64_dump_machdep_table(ulong arg)
> > ms = machdep->machspec;
> >
> > fprintf(fp, " machspec: %lx\n", (ulong)ms);
> > + fprintf(fp, " memory map layout: %s\n",
> > + (machdep->flags & NEW_VMEMMAP) ? "new" :
"old");
>
> As before, these internal "help" structure dumps just show existing
> structure fields,
> and NEW_VMMEMAP is already shown in the flags.
I put it as useful information for those people who might have got
any concerns about those odd numbers/kernel layout.
But if you don't like it, I will remove it.
>
> > fprintf(fp, " VA_BITS: %ld\n", ms->VA_BITS);
> > fprintf(fp, " userspace_top: %016lx\n",
ms->userspace_top);
> > fprintf(fp, " page_offset: %016lx\n",
ms->page_offset);
> > @@ -503,6 +569,11 @@ arm64_dump_machdep_table(ulong arg)
> > fprintf(fp, " modules_end: %016lx\n",
ms->modules_end);
> > fprintf(fp, " vmemmap_vaddr: %016lx\n",
ms->vmemmap_vaddr);
> > fprintf(fp, " vmemmap_end: %016lx\n",
ms->vmemmap_end);
> > + if (machdep->flags & NEW_VMEMMAP) {
> > + fprintf(fp, " kimage_text: %016lx\n",
ms->kimage_text);
> > + fprintf(fp, " kimage_end: %016lx\n",
ms->kimage_end);
> > + fprintf(fp, " kimage_voffset: %016lx\n",
ms->kimage_voffset);
> > + }
> > fprintf(fp, " phys_offset: %lx\n", ms->phys_offset);
> > fprintf(fp, "__exception_text_start: %lx\n",
> > ms->__exception_text_start);
> > fprintf(fp, " __exception_text_end: %lx\n",
ms->__exception_text_end);
> > @@ -543,6 +614,42 @@ arm64_dump_machdep_table(ulong arg)
> > }
> > }
> >
> > +static int
> > +arm64_parse_machdep_arg_l(char *argstring, char *param, ulong *value)
> > +{
> > + int len;
> > + int megabytes = FALSE;
> > + char *p;
> > +
> > + len = strlen(param);
> > + if (!STRNEQ(argstring, param) || (argstring[len] != '='))
> > + return FALSE;
> > +
> > + if ((LASTCHAR(argstring) == 'm') ||
> > + (LASTCHAR(argstring) == 'M')) {
> > + LASTCHAR(argstring) = NULLCHAR;
> > + megabytes = TRUE;
> > + }
> > +
> > + p = argstring + len + 1;
> > + if (strlen(p)) {
> > + int flags = RETURN_ON_ERROR | QUIET;
> > + int err = 0;
> > +
> > + if (megabytes) {
> > + *value = dtol(p, flags, &err);
> > + if (!err)
> > + *value = MEGABYTES(*value);
> > + } else {
> > + *value = htol(p, flags, &err);
> > + }
> > +
> > + if (!err)
> > + return TRUE;
> > + }
> > +
> > + return FALSE;
> > +}
> >
> > /*
> > * Parse machine dependent command line arguments.
> > @@ -554,11 +661,10 @@ arm64_dump_machdep_table(ulong arg)
> > static void
> > arm64_parse_cmdline_args(void)
> > {
> > - int index, i, c, err;
> > + int index, i, c;
> > char *arglist[MAXARGS];
> > char buf[BUFSIZE];
> > char *p;
> > - ulong value = 0;
> >
> > for (index = 0; index < MAX_MACHDEP_ARGS; index++) {
> > if (!machdep->cmdline_args[index])
> > @@ -580,39 +686,23 @@ arm64_parse_cmdline_args(void)
> > c = parse_line(buf, arglist);
> >
> > for (i = 0; i < c; i++) {
> > - err = 0;
> > -
> > - if (STRNEQ(arglist[i], "phys_offset=")) {
> > - int megabytes = FALSE;
> > - int flags = RETURN_ON_ERROR | QUIET;
> > -
> > - if ((LASTCHAR(arglist[i]) == 'm') ||
> > - (LASTCHAR(arglist[i]) == 'M')) {
> > - LASTCHAR(arglist[i]) = NULLCHAR;
> > - megabytes = TRUE;
> > - }
> > -
> > - p = arglist[i] + strlen("phys_offset=");
> > - if (strlen(p)) {
> > - if (megabytes)
> > - value = dtol(p, flags, &err);
> > - else
> > - value = htol(p, flags, &err);
> > - }
> > -
> > - if (!err) {
> > - if (megabytes)
> > - value = MEGABYTES(value);
> > -
> > - machdep->machspec->phys_offset = value;
> > -
> > - error(NOTE,
> > - "setting phys_offset to: 0x%lx\n\n",
> > - machdep->machspec->phys_offset);
> > + if (arm64_parse_machdep_arg_l(arglist[i],
> > + "phys_offset",
> > + &machdep->machspec->phys_offset)) {
> > + error(NOTE,
> > + "setting phys_offset to: 0x%lx\n\n",
> > + machdep->machspec->phys_offset);
> > +
> > + machdep->flags |= PHYS_OFFSET;
> > + continue;
> > + } else if (arm64_parse_machdep_arg_l(arglist[i],
> > + "kimage_voffset",
> > + &machdep->machspec->kimage_voffset)) {
> > + error(NOTE,
> > + "setting kimage_voffset to: 0x%lx\n\n",
> > + machdep->machspec->kimage_voffset);
> >
> > - machdep->flags |= PHYS_OFFSET;
> > - continue;
> > - }
> > + continue;
> > }
> >
> > error(WARNING, "ignoring --machdep option: %s\n",
> > @@ -627,10 +717,20 @@ arm64_calc_phys_offset(void)
> > {
> > struct machine_specific *ms = machdep->machspec;
> > ulong phys_offset;
> > + struct syment *sp;
> > + ulong value;
> >
> > if (machdep->flags & PHYS_OFFSET) /* --machdep override */
> > return;
> >
> > + sp = kernel_symbol_search("memstart_addr");
> > + if (sp && readmem(sp->value, KVADDR, (char *)&value,
sizeof(value),
> > + "memstart_addr", QUIET|RETURN_ON_ERROR)) {
> > + ms->phys_offset = value;
> > + machdep->flags |= PHYS_OFFSET;
> > + return;
> > + }
> > +
>
> Also, I may be missing something, but the PHYS_OFFSET flag means that it
> was
> passed in via --machdep, and is only used in this function to avoid any
> further
> attempts to figure out what it is. Here you are setting the flag for no
> particular
> reason that I can see. Why?
Well, I don't remember very well. If not necessary, I will remove it.
OK, I guarantee it's useless in this case...
> But again, doing a readmem() call this early is setting a bad
precedent --
> they have
> *always* been delayed until after gdb_session_init() in main_loop(). And
> the work
> of determining phys_base should be done by the dumpfile call-out functions
> that
> already exist.
>
>
> > /*
> > * Next determine suitable value for phys_offset. User can override
> > this
> > * by passing valid '--machdep phys_offset=<addr>' option.
> > @@ -2377,6 +2477,11 @@ arm64_IS_VMALLOC_ADDR(ulong vaddr)
> > {
> > struct machine_specific *ms = machdep->machspec;
> >
> > + if ((machdep->flags & NEW_VMEMMAP) &&
> > + (vaddr >= machdep->machspec->kimage_text) &&
> > + (vaddr <= machdep->machspec->kimage_end))
> > + return FALSE;
> > +
> > return ((vaddr >= ms->vmalloc_start_addr && vaddr <=
> > ms->vmalloc_end) ||
> > ((machdep->flags & VMEMMAP) &&
> > (vaddr >= ms->vmemmap_vaddr && vaddr <=
> > ms->vmemmap_end))
> > ||
> > @@ -2407,7 +2512,11 @@ arm64_calc_VA_BITS(void)
> >
> > for (bitval = highest_bit_long(value); bitval; bitval--) {
> > if ((value & (1UL << bitval)) == 0) {
> > +#if 1
> > + machdep->machspec->VA_BITS = bitval + 1;
> > +#else /* FIXME: bug? */
> > machdep->machspec->VA_BITS = bitval + 2;
> > +#endif
> > break;
> > }
> > }
>
> Again, a non-starter until the above is resolved -- but you know that
> already...
Just a reminder for now.
>
> > @@ -2459,10 +2568,22 @@ arm64_calc_virtual_memory_ranges(void)
> > break;
> > }
> >
> > - vmemmap_size = ALIGN((1UL << (ms->VA_BITS - machdep->pageshift))
*
> > SIZE(page), PUD_SIZE);
> > + if (machdep->flags & NEW_VMEMMAP)
> > +#define STRUCT_PAGE_MAX_SHIFT 6
> > + vmemmap_size = 1UL << (ms->VA_BITS - machdep->pageshift - 1
> > + + STRUCT_PAGE_MAX_SHIFT);
> > + else
> > + vmemmap_size = ALIGN((1UL << (ms->VA_BITS - machdep->pageshift))
*
> > SIZE(page), PUD_SIZE);
> > +
> > vmalloc_end = (ms->page_offset - PUD_SIZE - vmemmap_size - SZ_64K);
> > - vmemmap_start = vmalloc_end + SZ_64K;
> > - vmemmap_end = vmemmap_start + vmemmap_size;
> > +
> > + if (machdep->flags & NEW_VMEMMAP) {
> > + vmemmap_start = ms->page_offset - vmemmap_size;
> > + vmemmap_end = ms->page_offset;
> > + } else {
> > + vmemmap_start = vmalloc_end + SZ_64K;
> > + vmemmap_end = vmemmap_start + vmemmap_size;
> > + }
> >
> > ms->vmalloc_end = vmalloc_end - 1;
> > ms->vmemmap_vaddr = vmemmap_start;
> > diff --git a/defs.h b/defs.h
> > index a09fa9a..2bbb55b 100644
> > --- a/defs.h
> > +++ b/defs.h
> > @@ -2844,8 +2844,8 @@ typedef u64 pte_t;
> >
> > #define PTOV(X) \
> > ((unsigned
> >
long)(X)-(machdep->machspec->phys_offset)+(machdep->machspec->page_offset))
> > -#define VTOP(X) \
> > - ((unsigned
> >
long)(X)-(machdep->machspec->page_offset)+(machdep->machspec->phys_offset))
> > +
> > +#define VTOP(X) arm64_VTOP((ulong)(X))
> >
> > #define USERSPACE_TOP (machdep->machspec->userspace_top)
> > #define PAGE_OFFSET (machdep->machspec->page_offset)
> > @@ -2938,18 +2938,23 @@ typedef signed int s32;
> > #define VM_L3_4K (0x10)
> > #define KDUMP_ENABLED (0x20)
> > #define IRQ_STACKS (0x40)
> > +#define NEW_VMEMMAP (0x80)
> >
> > /*
> > * sources: Documentation/arm64/memory.txt
> > * arch/arm64/include/asm/memory.h
> > * arch/arm64/include/asm/pgtable.h
> > */
> > -
> > -#define ARM64_PAGE_OFFSET ((0xffffffffffffffffUL) <<
> > (machdep->machspec->VA_BITS - 1))
> > +#define ARM64_VA_START ((0xffffffffffffffffUL) \
> > + << machdep->machspec->VA_BITS)
> > +#define ARM64_PAGE_OFFSET ((0xffffffffffffffffUL) \
> > + << (machdep->machspec->VA_BITS - 1))
> > #define ARM64_USERSPACE_TOP ((1UL) <<
machdep->machspec->VA_BITS)
> > -#define ARM64_MODULES_VADDR (ARM64_PAGE_OFFSET - MEGABYTES(64))
> > -#define ARM64_MODULES_END (ARM64_PAGE_OFFSET - 1)
> > -#define ARM64_VMALLOC_START ((0xffffffffffffffffUL) <<
> > machdep->machspec->VA_BITS)
> > +
> > +/* only used for v4.6 or later */
> > +#define ARM64_MODULES_VSIZE MEGABYTES(128)
> > +#define ARM64_KASAN_SHADOW_SIZE (1UL <<
(machdep->machspec->VA_BITS -
> > 3))
> > +
> > /*
> > * The following 3 definitions are the original values, but are obsolete
> > * for 3.17 and later kernels because they are now build-time
> > calculations.
> > @@ -3028,6 +3033,10 @@ struct machine_specific {
> > ulong kernel_flags;
> > ulong irq_stack_size;
> > ulong *irq_stacks;
> > + /* only needed for kaslr-enabled kernel */
> > + ulong kimage_voffset;
> > + ulong kimage_text;
> > + ulong kimage_end;
> > };
>
> The comment is wrong -- the kimage_text and kimage_end values are needed
> for
> NEW_VMEMMAP kernels that are NOT configured with CONFIG_RANDOMIZE_BASE.
> Unless you consider my live system "kaslr-enabled"?
I will change it to "for v4.6 or later".
I have limited (or no) time to investigate a live-system case, and so if
you have any suggestions or your own patch, it is very much appreciated.
Yep... but I will build upon your solid foundation.
If I see anything interesting/different after my live system upgrade, I'll let
you know.
Thanks,
Dave
10:44 a.m.
----- Original Message -----
>
> Are you using a mainline kernel (final v4.6, not -rcX)?
Good point. When I configured my arm64 test system, I installed the latest
Fedora kernel available at the time (4.6.0-0.rc7.git2.1.fc25), but it is based
upon linux-4.5.tar.xz. I see now that there is a kernel-4.6.0-1.fc25 available
that is based upon linux-4.6.tar.xz. I'll update the system.
Here's the output from the updated non-randomized live system:
crash> sys
KERNEL: /usr/lib/debug/lib/modules/4.6.0-1.fc25.aarch64/vmlinux
DUMPFILE: /dev/crash
CPUS: 8
DATE: Wed May 25 11:30:06 2016
UPTIME: 00:18:43
LOAD AVERAGE: 0.01, 0.14, 0.17
TASKS: 200
NODENAME: apm-mustang-ev3-36.khw.lab.eng.bos.redhat.com
RELEASE: 4.6.0-1.fc25.aarch64
VERSION: #1 SMP Mon May 16 23:11:08 UTC 2016
MACHINE: aarch64 (unknown Mhz)
MEMORY: 16 GB
crash> log
... [ cut ] ...
[ 0.000000] Virtual kernel memory layout:
[ 0.000000] modules : 0xfffffc0000000000 - 0xfffffc0008000000 ( 128 MB)
[ 0.000000] vmalloc : 0xfffffc0008000000 - 0xfffffdfedfff0000 ( 2043 GB)
[ 0.000000] .text : 0xfffffc0008080000 - 0xfffffc0008890000 ( 8256 KB)
.rodata : 0xfffffc0008890000 - 0xfffffc0008c10000 ( 3584 KB)
.init : 0xfffffc0008c10000 - 0xfffffc0008d50000 ( 1280 KB)
.data : 0xfffffc0008d50000 - 0xfffffc0008eaac00 ( 1387 KB)
[ 0.000000] vmemmap : 0xfffffdfee0000000 - 0xfffffdffe0000000 ( 4 GB
maximum)
0xfffffdfee0000000 - 0xfffffdfee1000000 ( 16 MB
actual)
[ 0.000000] fixed : 0xfffffdfffe7d0000 - 0xfffffdfffec00000 ( 4288 KB)
[ 0.000000] PCI I/O : 0xfffffdfffee00000 - 0xfffffdffffe00000 ( 16 MB)
[ 0.000000] memory : 0xfffffe0000000000 - 0xfffffe0400000000 ( 16384 MB)
...
The starting addresses are OK, but still the vmemmap range looks suspect:
crash> help -m
... [ cut ] ...
VA_BITS: 42
userspace_top: 0000040000000000
page_offset: fffffe0000000000
vmalloc_start_addr: fffffc0008000000
vmalloc_end: fffffdff5ffeffff
modules_vaddr: fffffc0000000000
modules_end: fffffc0007ffffff
vmemmap_vaddr: fffffdff80000000 ???
vmemmap_end: fffffdffffffffff
kimage_text: fffffc0008080000
kimage_end: fffffc0009070000
kimage_voffset: 0000000000000000
phys_offset: 4000000000
...
crash> kmem fffffdff80000000
kmem: WARNING: cannot make virtual-to-physical translation: fffffdff80000000
fffffdff80000000: kernel virtual address not found in mem map
crash>
The vmemmap address from the log reads OK:
crash> kmem -p | head -10
PAGE PHYSICAL MAPPING INDEX CNT FLAGS
fffffdfee0000000 4000000000 fffffe03dc99f430 1b 2 4003c
referenced,uptodate,dirty,lru,swapbacked
fffffdfee0000040 4000010000 fffffe03dc99f430 1c 2 4003c
referenced,uptodate,dirty,lru,swapbacked
fffffdfee0000080 4000020000 fffffe03dc99f430 1d 2 4003c
referenced,uptodate,dirty,lru,swapbacked
fffffdfee00000c0 4000030000 fffffe03dc99f430 1e 2 4003c
referenced,uptodate,dirty,lru,swapbacked
fffffdfee0000100 4000040000 fffffe03dc99f430 1f 2 4003c
referenced,uptodate,dirty,lru,swapbacked
fffffdfee0000140 4000050000 fffffe03dc99f430 20 2 40078
uptodate,dirty,lru,active,swapbacked
fffffdfee0000180 4000060000 fffffe03dc99f430 21 2 4003c
referenced,uptodate,dirty,lru,swapbacked
fffffdfee00001c0 4000070000 fffffe03dc99f430 22 2 40078
uptodate,dirty,lru,active,swapbacked
fffffdfee0000200 4000080000 0 0 1 400 reserved
... [ cut ] ...
fffffdfee0fffd80 43fff60000 0 0 1 4000000000000400
reserved
fffffdfee0fffdc0 43fff70000 0 0 1 4000000000000400
reserved
fffffdfee0fffe00 43fff80000 0 0 1 4000000000000400
reserved
fffffdfee0fffe40 43fff90000 0 0 1 4000000000000400
reserved
fffffdfee0fffe80 43fffa0000 0 0 1 4000000000000400
reserved
fffffdfee0fffec0 43fffb0000 0 0 1 4000000000000400
reserved
fffffdfee0ffff00 43fffc0000 0 0 1 4000000000000400
reserved
fffffdfee0ffff40 43fffd0000 0 0 1 4000000000000400
reserved
fffffdfee0ffff80 43fffe0000 0 0 1 4000000000000400
reserved
fffffdfee0ffffc0 43ffff0000 0 0 1 4000000000000400
reserved
crash>
And again, the page_offset is fffffe0000000000 with a kernel VA_BITS configuration of 42:
kernel-4.6.0-aarch64.config:CONFIG_ARM64_VA_BITS_42=y
kernel-4.6.0-aarch64.config:# CONFIG_ARM64_VA_BITS_48 is not set
kernel-4.6.0-aarch64.config:CONFIG_ARM64_VA_BITS=42
Dave
3:37 a.m.
On Wed, May 25, 2016 at 11:44:23AM -0400, Dave Anderson wrote:
----- Original Message -----
> >
> > Are you using a mainline kernel (final v4.6, not -rcX)?
>
> Good point. When I configured my arm64 test system, I installed the latest
> Fedora kernel available at the time (4.6.0-0.rc7.git2.1.fc25), but it is based
> upon linux-4.5.tar.xz. I see now that there is a kernel-4.6.0-1.fc25 available
> that is based upon linux-4.6.tar.xz. I'll update the system.
Here's the output from the updated non-randomized live system:
crash> sys
KERNEL: /usr/lib/debug/lib/modules/4.6.0-1.fc25.aarch64/vmlinux
DUMPFILE: /dev/crash
CPUS: 8
DATE: Wed May 25 11:30:06 2016
UPTIME: 00:18:43
LOAD AVERAGE: 0.01, 0.14, 0.17
TASKS: 200
NODENAME: apm-mustang-ev3-36.khw.lab.eng.bos.redhat.com
RELEASE: 4.6.0-1.fc25.aarch64
VERSION: #1 SMP Mon May 16 23:11:08 UTC 2016
MACHINE: aarch64 (unknown Mhz)
MEMORY: 16 GB
crash> log
... [ cut ] ...
[ 0.000000] Virtual kernel memory layout:
[ 0.000000] modules : 0xfffffc0000000000 - 0xfffffc0008000000 ( 128 MB)
[ 0.000000] vmalloc : 0xfffffc0008000000 - 0xfffffdfedfff0000 ( 2043 GB)
[ 0.000000] .text : 0xfffffc0008080000 - 0xfffffc0008890000 ( 8256 KB)
.rodata : 0xfffffc0008890000 - 0xfffffc0008c10000 ( 3584 KB)
.init : 0xfffffc0008c10000 - 0xfffffc0008d50000 ( 1280 KB)
.data : 0xfffffc0008d50000 - 0xfffffc0008eaac00 ( 1387 KB)
[ 0.000000] vmemmap : 0xfffffdfee0000000 - 0xfffffdffe0000000 ( 4 GB
maximum)
0xfffffdfee0000000 - 0xfffffdfee1000000 ( 16 MB
actual)
[ 0.000000] fixed : 0xfffffdfffe7d0000 - 0xfffffdfffec00000 ( 4288 KB)
[ 0.000000] PCI I/O : 0xfffffdfffee00000 - 0xfffffdffffe00000 ( 16 MB)
[ 0.000000] memory : 0xfffffe0000000000 - 0xfffffe0400000000 ( 16384 MB)
...
The starting addresses are OK, but still the vmemmap range looks suspect:
crash> help -m
... [ cut ] ...
VA_BITS: 42
userspace_top: 0000040000000000
page_offset: fffffe0000000000
vmalloc_start_addr: fffffc0008000000
vmalloc_end: fffffdff5ffeffff
modules_vaddr: fffffc0000000000
modules_end: fffffc0007ffffff
vmemmap_vaddr: fffffdff80000000 ???
vmemmap_end: fffffdffffffffff
kimage_text: fffffc0008080000
kimage_end: fffffc0009070000
kimage_voffset: 0000000000000000
phys_offset: 4000000000
...
In my environment,
Virtual kernel memory layout:
modules : 0xffff000000000000 - 0xffff000008000000 ( 128 MB)
vmalloc : 0xffff000008000000 - 0xffff7dffbfff0000 (129022 GB)
.text : 0xffff000008080000 - 0xffff0000087e0000 ( 7552 KB)
.rodata : 0xffff0000087e0000 - 0xffff000008b10000 ( 3264 KB)
.init : 0xffff000008b10000 - 0xffff000008c00000 ( 960 KB)
.data : 0xffff000008c00000 - 0xffff000008ca1e00 ( 648 KB)
.bss : 0xffff000008ca1e00 - 0xffff000008ce4b38 ( 268 KB)
fixed : 0xffff7dfffe7fd000 - 0xffff7dfffec00000 ( 4108 KB)
PCI I/O : 0xffff7dfffee00000 - 0xffff7dffffe00000 ( 16 MB)
vmemmap : 0xffff7e0000000000 - 0xffff800000000000 ( 2048 GB maximum)
0xffff7e0000000000 - 0xffff7e0000900000 ( 9 MB actual)
memory : 0xffff800000000000 - 0xffff800024000000 ( 576 MB)
and,
$ crash ...
KERNEL: ./vmlinux.0526_64_48_nok
DUMPFILE: vmcore.0526_64_48_nok
CPUS: 8 [OFFLINE: 7]
DATE: Thu May 26 12:04:05 2016
UPTIME: 00:00:49
LOAD AVERAGE: 0.13, 0.04, 0.01
TASKS: 100
NODENAME: buildroot_le
RELEASE: 4.6.0+
VERSION: #1 SMP PREEMPT Thu May 26 12:02:41 JST 2016
MACHINE: aarch64 (unknown Mhz)
MEMORY: 512 MB
PANIC: "sysrq: SysRq : Trigger a crash"
PID: 1050
COMMAND: "sh"
TASK: ffff800020679c00 [THREAD_INFO: ffff8000205fc000]
CPU: 0
STATE: TASK_RUNNING (SYSRQ)
crash> help -m
...
VA_BITS: 48
userspace_top: 0001000000000000
page_offset: ffff800000000000
vmalloc_start_addr: ffff000008000000
vmalloc_end: ffff7fdfdffeffff
modules_vaddr: ffff000000000000
modules_end: ffff000007ffffff
vmemmap_vaddr: ffff7fe000000000
vmemmap_end: ffff7fffffffffff
kimage_text: ffff000008080000
kimage_end: ffff000008de0000
kimage_voffset: fffeffff88000000
phys_offset: 80000000
crash> kmem fffffdff80000000
kmem: WARNING: cannot make virtual-to-physical translation: fffffdff80000000
fffffdff80000000: kernel virtual address not found in mem map
crash>
Yeah, I noticed this issue.
But the current crash doesn't support 4-level translation for 4KB now,
I changed the kernel configuration with 64KB page size and
with 48 bit VA (so 3-level), then confirmed that it just worked on
non-randomized kernel, but not on randomized kernel.
The vmemmap address from the log reads OK:
crash> kmem -p | head -10
PAGE PHYSICAL MAPPING INDEX CNT FLAGS
fffffdfee0000000 4000000000 fffffe03dc99f430 1b 2 4003c
referenced,uptodate,dirty,lru,swapbacked
fffffdfee0000040 4000010000 fffffe03dc99f430 1c 2 4003c
referenced,uptodate,dirty,lru,swapbacked
fffffdfee0000080 4000020000 fffffe03dc99f430 1d 2 4003c
referenced,uptodate,dirty,lru,swapbacked
fffffdfee00000c0 4000030000 fffffe03dc99f430 1e 2 4003c
referenced,uptodate,dirty,lru,swapbacked
fffffdfee0000100 4000040000 fffffe03dc99f430 1f 2 4003c
referenced,uptodate,dirty,lru,swapbacked
fffffdfee0000140 4000050000 fffffe03dc99f430 20 2 40078
uptodate,dirty,lru,active,swapbacked
fffffdfee0000180 4000060000 fffffe03dc99f430 21 2 4003c
referenced,uptodate,dirty,lru,swapbacked
fffffdfee00001c0 4000070000 fffffe03dc99f430 22 2 40078
uptodate,dirty,lru,active,swapbacked
fffffdfee0000200 4000080000 0 0 1 400 reserved
... [ cut ] ...
fffffdfee0fffd80 43fff60000 0 0 1 4000000000000400
reserved
fffffdfee0fffdc0 43fff70000 0 0 1 4000000000000400
reserved
fffffdfee0fffe00 43fff80000 0 0 1 4000000000000400
reserved
fffffdfee0fffe40 43fff90000 0 0 1 4000000000000400
reserved
fffffdfee0fffe80 43fffa0000 0 0 1 4000000000000400
reserved
fffffdfee0fffec0 43fffb0000 0 0 1 4000000000000400
reserved
fffffdfee0ffff00 43fffc0000 0 0 1 4000000000000400
reserved
fffffdfee0ffff40 43fffd0000 0 0 1 4000000000000400
reserved
fffffdfee0ffff80 43fffe0000 0 0 1 4000000000000400
reserved
fffffdfee0ffffc0 43ffff0000 0 0 1 4000000000000400
reserved
crash>
And again, the page_offset is fffffe0000000000 with a kernel VA_BITS configuration of
42:
kernel-4.6.0-aarch64.config:CONFIG_ARM64_VA_BITS_42=y
kernel-4.6.0-aarch64.config:# CONFIG_ARM64_VA_BITS_48 is not set
kernel-4.6.0-aarch64.config:CONFIG_ARM64_VA_BITS=42
I think it looks OK.
Thanks,
-Takahiro AKASHI
Dave
--
Crash-utility mailing list
Crash-utility(a)redhat.com
https://www.redhat.com/mailman/listinfo/crash-utility
--
Thanks,
-Takahiro AKASHI
3:13 a.m.
On Wed, May 25, 2016 at 10:28:10AM -0400, Dave Anderson wrote:
----- Original Message -----
> On Tue, May 24, 2016 at 01:59:06PM -0400, Dave Anderson wrote:
> >
> > ----- Original Message -----
> > > Yet some issues, but ...
> > >
> >
> > Hi Takahiro,
> >
> > Here are my general comments on my testing of the v2 patch, followed
> > by a few comments in the patch itself.
>
> Thank you for your quick review/testing, again.
>
> > First, the combination of the new memory map layout and KASLR is somewhat
> > confusing. I am testing your patch on a 4.6.0-0.rc7.git2.1.fc25 kernel
> > that has this configuration:
>
> Right. I use the "kaslr kernel" or "kaslr-enabled kernel" in
two
> meanings (almost interchangeably):
> - kernel with a new memory map, that is v4.6 or later
> - kernel that has ability of KASLR (configured with CONFIG_RANDOMIZE_RAM)
>
> When we talked offline, you mentioned the possibility of backporting
> KASLR to older kernel, so I hesitated to use "v4.6 or later".
> But I think that we'd better use "v4.6 or later" for a clarification
> for now.
Actually I was thinking more along the lines of the new vmemmap stuff
being backported. But it looks like that would be impossible without
also bringing along "kimage_voffset".
Yeah, a sbustantial amount of code on mm code must be changed, and it is
impractical to backport them.
> > config-arm64:# CONFIG_RANDOMIZE_BASE is not set
> >
> > So KASLR doesn't really enter into the picture. But when bringing
> > up the crash session, it shows the "kaslr kernel" WARNING:
> >
> > # ./crash
> >
> > crash 7.1.5++
> > Copyright (C) 2002-2016 Red Hat, Inc.
> > Copyright (C) 2004, 2005, 2006, 2010 IBM Corporation
> > Copyright (C) 1999-2006 Hewlett-Packard Co
> > Copyright (C) 2005, 2006, 2011, 2012 Fujitsu Limited
> > Copyright (C) 2006, 2007 VA Linux Systems Japan K.K.
> > Copyright (C) 2005, 2011 NEC Corporation
> > Copyright (C) 1999, 2002, 2007 Silicon Graphics, Inc.
> > Copyright (C) 1999, 2000, 2001, 2002 Mission Critical Linux, Inc.
> > This program is free software, covered by the GNU General Public License,
> > and you are welcome to change it and/or distribute copies of it under
> > certain conditions. Enter "help copying" to see the conditions.
> > This program has absolutely no warranty. Enter "help warranty"
for
> > details.
> >
> > WARNING: kimage_voffset not identified for kaslr kernel
> > GNU gdb (GDB) 7.6
> > Copyright (C) 2013 Free Software Foundation, Inc.
> > License GPLv3+: GNU GPL version 3 or later
> > <http://gnu.org/licenses/gpl.html>
> > This is free software: you are free to change and redistribute it.
> > There is NO WARRANTY, to the extent permitted by law. Type "show
> > copying"
> > and "show warranty" for details.
> > This GDB was configured as "aarch64-unknown-linux-gnu"...
> >
> > KERNEL:
> > /usr/lib/debug/lib/modules/4.6.0-0.rc7.git2.1.fc25.aarch64/vmlinux
> > DUMPFILE: /dev/crash
> > CPUS: 8
> > DATE: Tue May 24 10:08:08 2016
> > UPTIME: 11 days, 18:32:41
> > LOAD AVERAGE: 0.17, 0.09, 0.12
> > TASKS: 197
> > NODENAME: apm-mustang-ev3-36.khw.lab.eng.bos.redhat.com
> > RELEASE: 4.6.0-0.rc7.git2.1.fc25.aarch64
> > VERSION: #1 SMP Thu May 12 13:28:43 UTC 2016
> > MACHINE: aarch64 (unknown Mhz)
> > MEMORY: 16 GB
> > PID: 7556
> > COMMAND: "crash"
> > TASK: fffffe00beb45400 [THREAD_INFO: fffffe00beb98000]
> > CPU: 7
> > STATE: TASK_RUNNING (ACTIVE)
> >
> > crash>
> >
> > Why show that WARNING in this case? I understant that it's not
> > stashed during early initialization:
>
> If we don't know kimage_voffset, we can't analyze the contents of
> memory (live or kdump).
I understand. But clearly that's not the case with my system above that
does not have CONFIG_RANDOMIZE_BASE configured, so the warning message
is nonsensical/confusing. That's why I was speculating about perhaps
having kdump export a VMCOREINFO_CONFIG(RANDOMIZE_BASE) so that it is
readily apparent.
>
> > crash> help -m
> > flags: 104000c5
> >
(KSYMS_START|VM_L2_64K|VMEMMAP|IRQ_STACKS|MACHDEP_BT_TEXT|NEW_VMEMMAP)
> > ... [ cut ] ...
> > memory map layout: new <--- BTW, this is
> > redundant/not-a-member, and we've got NEW_VMEMMAP
> > VA_BITS: 42
> > userspace_top: 0000040000000000
> > page_offset: fffffe0000000000
> > vmalloc_start_addr: fffffc0008000000
> > vmalloc_end: fffffdff5ffeffff
> > modules_vaddr: fffffc0000000000
> > modules_end: fffffc0007ffffff
> > vmemmap_vaddr: fffffdff80000000
> > vmemmap_end: fffffdffffffffff
> > kimage_text: fffffc0008080000
> > kimage_end: fffffc0009070000
> > kimage_voffset: 0000000000000000 <-- available if kernel is
> > not randomized
> > phys_offset: 4000000000
> > ...
> >
> > But it can be read:
> >
> > crash> px kimage_voffset
> > kimage_voffset = $1 = 0xfffffbc008000000
> > crash>
> >
> > SO because it wasn't determined during session initialization,
> > it falls into the "no randomness" section of arm64_VTOP():
>
> Exactly.
>
> > ulong
> > arm64_VTOP(ulong addr)
> > {
> > if (!(machdep->flags & NEW_VMEMMAP) ||
> > (addr >= machdep->machspec->page_offset)) {
> > return machdep->machspec->phys_offset
> > + (addr - machdep->machspec->page_offset);
> > } else {
> > if (machdep->machspec->kimage_voffset)
> > return addr -
machdep->machspec->kimage_voffset;
> > else /* no randomness */
> > return machdep->machspec->phys_offset
> > + (addr -
> >
machdep->machspec->vmalloc_start_addr);
> > }
> > }
> >
> > That works, but if "kimage_offset" can be read normally later on,
perhaps it
> > should update "machdep->machspec->kimage_voffset" at that
time?
>
> It is possible, but the check in arm64_VTOP() would be still necessary.
Agreed...
Keep it there.
>
> > There are some discrepancies with respect to the calculated addresses
> > and what is seen by looking at the reported memory map in the kernel log:
> >
> > [ 0.000000] Virtual kernel memory layout:
> > [ 0.000000] modules : 0xfffffc0000000000 - 0xfffffc0008000000 (
> > 128 MB)
> > [ 0.000000] vmalloc : 0xfffffc0008000000 - 0xfffffdfedfff0000 (
> > 2043 GB)
> > [ 0.000000] .text : 0xfffffc0008080000 - 0xfffffc0008890000 (
> > 8256 KB)
> > .rodata : 0xfffffc0008890000 - 0xfffffc0008c10000 (
> > 3584 KB)
> > .init : 0xfffffc0008c10000 - 0xfffffc0008d50000 (
> > 1280 KB)
> > .data : 0xfffffc0008d50000 - 0xfffffc0008eaac00 (
> > 1387 KB)
> > [ 0.000000] vmemmap : 0xfffffdfee0000000 - 0xfffffdffe0000000 (
> > 4 GB maximum)
> > 0xfffffdfee0000000 - 0xfffffdfee1000000 (
> > 16 MB actual)
> > [ 0.000000] fixed : 0xfffffdfffe7d0000 - 0xfffffdfffec00000 (
> > 4288 KB)
> > [ 0.000000] PCI I/O : 0xfffffdfffee00000 - 0xfffffdffffe00000 (
> > 16 MB)
> > [ 0.000000] memory : 0xfffffe0000000000 - 0xfffffe0400000000 (
> > 16384 MB)
> >
> > Comparing it to the calculated values:
> >
> > VA_BITS: 42
> > userspace_top: 0000040000000000
> > page_offset: fffffe0000000000 OK
> > vmalloc_start_addr: fffffc0008000000 OK
> > vmalloc_end: fffffdff5ffeffff ? (seems wrong)
> > modules_vaddr: fffffc0000000000 OK
> > modules_end: fffffc0007ffffff OK (-1)
> > vmemmap_vaddr: fffffdff80000000 ? (seems wrong)
> > vmemmap_end: fffffdffffffffff ? (seems wrong)
> > kimage_text: fffffc0008080000 OK
> > kimage_end: fffffc0009070000 OK
> > kimage_voffset: 0000000000000000
> > phys_offset: 4000000000
> >
> > Starting with vmalloc_start_addr/vmalloc_end, if I run "kmem -v" to
dump
> > the
> > vmalloc allocations, there are some allocations that are below the
> > 0xfffffc0008000000 start value shown in the log and by your calcuation.
> > I'm not clear on what that means?:
> >
> > crash> kmem -v
> > VMAP_AREA VM_STRUCT ADDRESS RANGE
> > SIZE
> > fffffe03daefd900 fffffe03daefd880 fffffc0000c10000 - fffffc0000c30000
> > 131072
> > fffffe00bf2c3a00 fffffe00bf2c3980 fffffc0000c90000 - fffffc0000cb0000
> > 131072
> > fffffe00bf2c7400 fffffe00bf2c7380 fffffc0000d50000 - fffffc0000d70000
> > 131072
> > fffffe03dc76aa00 fffffe03dc76a980 fffffc0000d90000 - fffffc0000db0000
> > 131072
> > fffffe03dc76be00 fffffe03dc76bd80 fffffc0000dd0000 - fffffc0000ee0000
> > 1114112
> > fffffe03d90e7900 fffffe03d90e7b80 fffffc0000f40000 - fffffc0000fb0000
> > 458752
> > fffffe00bec12f00 fffffe00bec12b00 fffffc0000fe0000 - fffffc0001000000
> > 131072
> > fffffe00bf3a1100 fffffe00bf3a1080 fffffc0001020000 - fffffc0001050000
> > 196608
> > fffffe00bf3a3280 fffffe00bf3a3200 fffffc0001070000 - fffffc0001090000
> > 131072
> > fffffe03ddf7fc00 fffffe03ddf7a880 fffffc0001230000 - fffffc0001250000
> > 131072
> > fffffe03fd508900 fffffe03fd508880 fffffc0008000000 - fffffc0008020000
> > 131072
> > fffffe03fd509580 fffffe03fd508d00 fffffc0008020000 - fffffc0008040000
> > 131072
> > fffffe03fd508a00 fffffe03fd508980 fffffc0008040000 - fffffc0008070000
> > 196608
> > ... [ cut ] ...
> > fffffe03d7235000 fffffe03d7233480 fffffc0014b30000 - fffffc0014b50000
> > 131072
> > fffffe00b921e700 fffffe00b921df00 fffffc0014b70000 - fffffc0014b90000
> > 131072
> > fffffe00b851eb00 fffffe00b8512900 fffffdfedfcf0000 - fffffdfedfe70000
> > 1572864
> > fffffe03dca4ef00 fffffe03dca4ef80 fffffdfedfe70000 - fffffdfedfff0000
> > 1572864
> > crash>
> >
> > Although the end value of fffffdfedfff0000 does match up with the value in
> > the
> > kernel log, your calculation is 2GB higher at fffffdff5ffeffff:
> >
> > crash> eval fffffdff5ffeffff - 0xfffffdfedfff0000
> > hexadecimal: 7fffffff
> > decimal: 2147483647
> > octal: 17777777777
> > binary:
> > 0000000000000000000000000000000001111111111111111111111111111111
> > crash> eval 7fffffff + 1
> > hexadecimal: 80000000 (2GB)
> > decimal: 2147483648
> > octal: 20000000000
> > binary:
> > 0000000000000000000000000000000010000000000000000000000000000000
> > crash>
> >
> > With respect to the vmemmap range, vmmemap address in the log file is the
> > one
> > that is displayed by "kmem -p":
> >
> > crash> kmem -p
> > PAGE PHYSICAL MAPPING INDEX CNT FLAGS
> > fffffdfee0000000 4000000000 fffffe03fd441950 2f 1 1002c
> > referenced,uptodate,lru,mappedtodisk
> > fffffdfee0000040 4000010000 fffffe03fd441950 30 1 1002c
> > referenced,uptodate,lru,mappedtodisk
> > fffffdfee0000080 4000020000 fffffe03fd441950 31 1 1002c
> > referenced,uptodate,lru,mappedtodisk
> > fffffdfee00000c0 4000030000 fffffe03fd441950 32 1 1002c
> > referenced,uptodate,lru,mappedtodisk
> > ...
> > fffffdfee0ffff00 43fffc0000 0 0 1
> > 4000000000000400 reserved
> > fffffdfee0ffff40 43fffd0000 0 0 1
> > 4000000000000400 reserved
> > fffffdfee0ffff80 43fffe0000 0 0 1
> > 4000000000000400 reserved
> > fffffdfee0ffffc0 43ffff0000 0 0 1
> > 4000000000000400 reserved
> > crash>
> >
> > And "kmem" alone recognizes it:
> >
> > crash> kmem fffffdfee0000000
> > PAGE PHYSICAL MAPPING INDEX CNT FLAGS
> > fffffdfee0000000 4000000000 fffffe03fd441950 2f 1 1002c
> > referenced,uptodate,lru,mappedtodisk
> > crash>
> >
> > But your calculated vmemmap_vaddr above doesn't seem right:
> >
> > crash> kmem fffffdff80000000
> > kmem: WARNING: cannot make virtual-to-physical translation:
> > fffffdff80000000
> > fffffdff80000000: kernel virtual address not found in mem map
> > crash>
> >
> > Do your numbers match up on a dump that actually has CONFIG_RANDOMIZE_BASE?
>
> In my environment, the numbers above match up on a dump whether
> CONFIG_RANDOMIZE_BASE is enabled or not.
>
> Are you using a mainline kernel (final v4.6, not -rcX)?
Good point. When I configured my arm64 test system, I installed the latest
Fedora kernel available at the time (4.6.0-0.rc7.git2.1.fc25), but it is based
upon linux-4.5.tar.xz. I see now that there is a kernel-4.6.0-1.fc25 available
that is based upon linux-4.6.tar.xz. I'll update the system.
> > Anyway, onto the patch...
> >
> > >
> > > changes in v2:
> > > * Fixed build warnings
> > > * Moved ARM64_NEW_VMEMMAP to machdep->flags
> > > * Show additional kaslr-related parameters in arm64_dump_machdep_table()
> > > * Handle a VMCOREINFO, "NUMBER(kimage_voffset)"
> > >
> > > ===8<===
> > > >From 080a54ec232ac48ef2d8123cbedcf0f1fe27e391 Mon Sep 17 00:00:00
2001
> > > From: AKASHI Takahiro <takahiro.akashi(a)linaro.org>
> > > Date: Mon, 16 May 2016 17:31:55 +0900
> > > Subject: [PATCH v2] arm64: fix kernel memory map handling for
> > > kaslr-enabled
> > > kernel
> > >
> > > In kernel v4.6, Kernel ASLR (KASLR) is supported on arm64, and the start
> > > address of the kernel image can be randomized if CONFIG_RANDOMIZE_BASE is
> > > enabled.
> > > Even worse, the kernel image is no more mapped in the linear mapping, but
> > > in vmalloc area (i.e. below PAGE_OFFSET).
> > >
> > > Now, according to the kernel's memory.h, converting a virtual address
to
> > > a physical address should be done like below:
> > >
> > > phys_addr_t __x = (phys_addr_t)(x); \
> > > __x & BIT(VA_BITS - 1) ? (__x & ~PAGE_OFFSET) + PHYS_OFFSET :
\
> > > (__x - kimage_voffset); })
> > >
> > > Please note that PHYS_OFFSET is no more equal to the start address of
> > > the first usable memory block in SYSTEM RAM due to the fact mentioned
> > > above.
> > >
> > > This patch addresses this change and allows the crash utility to access
> > > memory contents with correct addresses.
> > > *However*, it is still rough-edged and we need more refinements.
> > >
> > > 1-1) On a live system, crash with this patch won't work because
> > > we currently have no way to know kimage_voffset.
> > >
> > > 1-2) For a core dump file, we can do simply:
> > > $ crash <vmlinux> <vmcore>
> > > as long as the file has "NUMBER(kimage_voffset)"
> > > (RELOC_AUTO|KASLR is automatically set.)
> > >
> > > I'm planning to add this enhancement in my next version of
kexec/kdump
> > > patch, i.e. v17.
> > >
> > > 2) My current change breaks the backward compatibility.
> > > Crash won't work with v4.5 or early kernel partly because I
changed
> > > the calculation of VA_BITS. (I think that the existing code is wrong.)
> > > So far I don't have enough time to look into this issue as I'm
> > > focusing
> > > on KASLR support.
> >
> > OK, but you still haven't shown how the current VA_BITS determination is
> > not a correct representation of CONFIG_ARM64_VA_BITS.
>
> At least, the current VA_BITS doesn't work with my calculations, which
> were derived directly from v4.6's "asm/memory.h".
What are your kernel's PAGE_OFFSET value and CONFIG_ARM64_VA_BITS value?
>
> > > 3) Backtracing a 'panic'ed task fails:
> > > crash> bt
> > > PID: 999 TASK: ffffffe960081800 CPU: 0 COMMAND: "sh"
> > > bt: WARNING: corrupt prstatus? pstate=0x80000000, but no user frame
> > > found
> > > bt: WARNING: cannot determine starting stack frame for task
> > > ffffffe960081800
> > >
> > > frame->pc indicates that it is a kernel address, so obviously
something
> > > is wrong. I'm diggin into it.
> >
> > Can you add a debug statement that displays frame->pc, frame->sp, and
> > frame->fp?
>
> I've already identified the cause.
> pt_regs->pstate was set mistakenly from "sprsr_el1" in panic().
> But I have a difficulty here to fix the problem as we have no direct way
> to retrieve a value of the *current* PSTATE.
Interesting. I don't know what you mean by "sprsr_el1" in panic(), but
I just got a report from my github "issues", where the user injected a panic()
call into a kernel module and got the same error as above because of the pstate
value. I asked him to put this hack into arm64.c:
spspr_el1 is a register that holds a value of PSTATE when an exception
is trapped into EL1. Since panic() is called even in case of software
bugs, it is not useful anyway.
Currently I'm trying to save a "faked" current PSTATE into
pt_regs->pstate
and will add this fix in my next kdump patch series (v17).
--- a/arm64.c
+++ b/arm64.c
@@ -1711,11 +1711,14 @@ arm64_get_dumpfile_stackframe(struct bt_info *bt, struct
arm64_stackframe *frame
error(WARNING,
"corrupt prstatus? pstate=0x%lx, but no user frame
found\n",
ptregs->pstate);
+ if (INSTACK(frame->sp, bt) && INSTACK(frame->fp,
bt))
+ goto try_kernel;
bt->flags |= BT_REGS_NOT_FOUND;
return FALSE;
}
bt->flags |= BT_USER_SPACE;
} else {
+try_kernel:
frame->sp = ptregs->sp;
frame->fp = ptregs->regs[29];
}
Can you give that a shot?
Well, I think I've already fixed...
> >
> > > Signed-off-by: AKASHI Takahiro <takahiro.akashi(a)linaro.org>
> > > ---
> > > arm64.c | 217
> > > ++++++++++++++++++++++++++++++++++++++++++++++++--------------
> > > defs.h | 24 +++++--
> > > main.c | 7 +-
> > > symbols.c | 10 +--
> > > 4 files changed, 196 insertions(+), 62 deletions(-)
> > >
> > > diff --git a/arm64.c b/arm64.c
> > > index 34c8c59..6b97093 100644
> > > --- a/arm64.c
> > > +++ b/arm64.c
> > > @@ -72,6 +72,21 @@ static int arm64_get_crash_notes(void);
> > > static void arm64_calc_VA_BITS(void);
> > > static int arm64_is_uvaddr(ulong, struct task_context *);
> > >
> > > +ulong
> > > +arm64_VTOP(ulong addr)
> > > +{
> > > + if (!(machdep->flags & NEW_VMEMMAP) ||
> > > + (addr >= machdep->machspec->page_offset)) {
> > > + return machdep->machspec->phys_offset
> > > + + (addr - machdep->machspec->page_offset);
> > > + } else {
> > > + if (machdep->machspec->kimage_voffset)
> > > + return addr - machdep->machspec->kimage_voffset;
> > > + else /* no randomness */
> > > + return machdep->machspec->phys_offset
> > > + + (addr - machdep->machspec->vmalloc_start_addr);
> > > + }
> > > +}
> > >
> > > /*
> > > * Do all necessary machine-specific setup here. This is called several
> > > times
> > > @@ -81,6 +96,7 @@ void
> > > arm64_init(int when)
> > > {
> > > ulong value;
> > > + char *string;
> > > struct machine_specific *ms;
> > >
> > > #if defined(__x86_64__)
> > > @@ -102,9 +118,34 @@ arm64_init(int when)
> > > if (machdep->cmdline_args[0])
> > > arm64_parse_cmdline_args();
> > > machdep->flags |= MACHDEP_BT_TEXT;
> > > +
> > > + ms = machdep->machspec;
> > > + if (!ms->kimage_voffset &&
> > > + (string =
pc->read_vmcoreinfo("NUMBER(kimage_voffset)"))) {
> > > + ms->kimage_voffset = htol(string, QUIET, NULL);
> > > + free(string);
> > > + }
> >
> > It doesn't make sense to call pc->read_vmcoreinfo() if !DUMPFILE().
>
> Do you think so?
> By default, pc->read_vmcoreinfo is set to no_vmcoreinfo.
> So it doesn't hurt anything.
Right, just a suggestion...
So keep it there for now.
> > > +
> > > + if (ms->kimage_voffset) {
> > > + machdep->flags |= NEW_VMEMMAP;
> > > +
> > > + /* if not specified in command line */
> > > + if (!kt->relocate && !(kt->flags2 &
(RELOC_AUTO|KASLR)))
> > > + kt->flags2 |= (RELOC_AUTO|KASLR);
> > > + }
> > > +
> >
> > If CONFIG_RANDOMIZE_BASE is NOT set, should RELOC_AUTO|KASLR be set? They
> > don't get set on my live system.
>
> Not necessarily, but the current implementation of derive_kaslr_offset()
> just works even in this case.
Ahah -- cool!
kt->relocate will be set to 0 in this case, we will see no difference
between KASLR and non-KASLR case.
> (This is the reason that I don't think we need a VMCOREINFO
for
> CONFIG_RANDOMIZE_BASE.)
Well, as long as there's a way to avoid that unnecessary/confusing
warning message for non-KASLR new-vmemmap kernels.
I also wonder whether makedumpfile could use it?
-> Pratyush?
> > > break;
> > >
> > > case PRE_GDB:
> > > + /* This check is somewhat redundant */
> > > + if (kernel_symbol_exists("kimage_voffset")) {
> > > + machdep->flags |= NEW_VMEMMAP;
> > > +
> > > + if (!machdep->machspec->kimage_voffset)
> > > + error(WARNING,
> > > + "kimage_voffset not identified for kaslr kernel\n");
> > > + }
> > > +
> >
> > As mentioned in the general discussion above, the WARNING above makes
> > no sense if CONFIG_RANDOMIZE_BASE is not configured.
>
> What about if I change the message "for v4.6 or later kernel"?
But again, I do not want the message at all if it's not applicable.
I removed this message.
Worse case, you could set a flag, and then if/when the crash session
ultimately craps out if it can't figure things out, then the message
could be displayed post-mortem.
> > I'm now thinking that CONFIG_RANDOMIZE_BASE (and maybe others like KASAN?)
> > should be passed in the dumpfile with VMCOREINFO_CONFIG().
>
> Regarding KASAN, we only need to check for an existence of "kasan_init"
> symbol as you recommended before :)
Nice.
> >
> > > if (!machdep->pagesize) {
> > > /*
> > > * Kerneldoc Documentation/arm64/booting.txt describes
> > > @@ -160,16 +201,35 @@ arm64_init(int when)
> > > machdep->pagemask = ~((ulonglong)machdep->pageoffset);
> > >
> > > arm64_calc_VA_BITS();
> > > - machdep->machspec->page_offset = ARM64_PAGE_OFFSET;
> > > + ms = machdep->machspec;
> > > + ms->page_offset = ARM64_PAGE_OFFSET;
> > > + /* FIXME: idmap for NEW_VMEMMAP */
> > > machdep->identity_map_base = ARM64_PAGE_OFFSET;
> > > - machdep->machspec->userspace_top = ARM64_USERSPACE_TOP;
> > > - machdep->machspec->modules_vaddr = ARM64_MODULES_VADDR;
> > > - machdep->machspec->modules_end = ARM64_MODULES_END;
> > > - machdep->machspec->vmalloc_start_addr = ARM64_VMALLOC_START;
> > > - machdep->machspec->vmalloc_end = ARM64_VMALLOC_END;
> > > - machdep->kvbase = ARM64_VMALLOC_START;
> > > - machdep->machspec->vmemmap_vaddr = ARM64_VMEMMAP_VADDR;
> > > - machdep->machspec->vmemmap_end = ARM64_VMEMMAP_END;
> > > + machdep->kvbase = ARM64_VA_START;
> > > + ms->userspace_top = ARM64_USERSPACE_TOP;
> > > + if (machdep->flags & NEW_VMEMMAP) {
> > > + struct syment *sp;
> > > +
> > > + sp = kernel_symbol_search("_text");
> > > + ms->kimage_text = (sp ? sp->value : 0);
> > > + sp = kernel_symbol_search("_end");
> > > + ms->kimage_end = (sp ? sp->value : 0);
> > > +
> > > + ms->modules_vaddr = ARM64_VA_START;
> > > + if (kernel_symbol_exists("kasan_init"))
> > > + ms->modules_vaddr += ARM64_KASAN_SHADOW_SIZE;
> > > + ms->modules_end = ms->modules_vaddr
> > > + + ARM64_MODULES_VSIZE -1;
> > > +
> > > + ms->vmalloc_start_addr = ms->modules_end + 1;
> > > + } else {
> > > + ms->modules_vaddr = ARM64_PAGE_OFFSET - MEGABYTES(64);
> > > + ms->modules_end = ARM64_PAGE_OFFSET - 1;
> > > + ms->vmalloc_start_addr = ARM64_VA_START;
> > > + }
> > > + ms->vmalloc_end = ARM64_VMALLOC_END;
> > > + ms->vmemmap_vaddr = ARM64_VMEMMAP_VADDR;
> > > + ms->vmemmap_end = ARM64_VMEMMAP_END;
> > >
> > > switch (machdep->pagesize)
> > > {
> > > @@ -232,8 +292,6 @@ arm64_init(int when)
> > > machdep->stacksize = ARM64_STACK_SIZE;
> > > machdep->flags |= VMEMMAP;
> > >
> > > - arm64_calc_phys_offset();
> > > -
> > > machdep->uvtop = arm64_uvtop;
> > > machdep->kvtop = arm64_kvtop;
> > > machdep->is_kvaddr = generic_is_kvaddr;
> > > @@ -262,6 +320,10 @@ arm64_init(int when)
> > > machdep->dumpfile_init = NULL;
> > > machdep->verify_line_number = NULL;
> > > machdep->init_kernel_pgd = arm64_init_kernel_pgd;
> > > +
> > > + /* use machdep parameters */
> > > + arm64_calc_phys_offset();
> > > +
> >
> > This doesn't make any sense to me. I understand you've done it
because
> > you are now doing a readmem() in arm64_calc_phys_offset(). But readmem()
> > calls are never done this early. And in fact, on the live system the
> > readmem() in arm64_calc_phys_offset() fails like so (running "crash
-d4"):
> >
> > <readmem: fffffc0008d70bb0, KVADDR, "memstart_addr", 8,
(ROE|Q),
> > 3ffcc2842c0>
> > <read_memory_device: addr: fffffc0008d70bb0 paddr: d70bb0 cnt: 8>
> > crash: read error: kernel virtual address: fffffc0008d70bb0 type:
> > "memstart_addr"
> >
> > It fails above because it needs the phys_base in order to do the readmem().
> > During
> > runtime it has it:
>
> This is because we don't know kimage_voffset on a live system.
> (and so I mentioned this issue in my commit log.)
Right -- which is a good reason for NOT using readmem() at that point
in time. I can also envision a scenario where readmem() may inadvertently
"work" (i.e. depending upon where phys_base really is), and then return
something bogus from an unintended location.
> As far as kdump case is concerned, readmem() at this point just works
> for any address in kernel image. This is my intentional use of this function.
I understand, but you're subverting the subsequent dumpfile-specific
calls later in the function. It is precisely *their* responsibility
to return the value of phys_offset.
I think that the code should precede the other cases, including
diskdump and kdump. The only exception would be a live sysmem with
CONFIG_RANDOMIZE_RAM configured.
I will temporarily add a check here like:
arm64_calc_phys_offset()
{
if (machdep->flags & NEW_VMEMMAP)
sp = kernel_symbol_search("memstart_addr");
readmem(sp->value, ...);
...
}
This way, even on a live system with no KASLR, "phys_offset" will be
determined based on /proc/iomem, and eventually the crash should work.
(Sorry, I haven't tested it yet though.)
> > crash> set debug 4
> > debug: 4
> > crash> rd memstart_addr
> > <addr: fffffc0008d70bb0 count: 1 flag: 490 (KVADDR)>
> > <readmem: fffffc0008d70bb0, KVADDR, "64-bit KVADDR", 8, (FOE),
> > 3ffcbfbfc28>
> > <read_memory_device: addr: fffffc0008d70bb0 paddr: 4000d70bb0 cnt: 8>
> > fffffc0008d70bb0: 0000004000000000 ....@...
> > crash>
> >
> > So without kimage_voffset, that readmem(), how would that readmem()
> > possibly work?
> > You need the *contents* of memstart_addr in order to *read* memstart_addr.
> >
> > Now, if it kimage_voffset were passed into the vmcore, then I guess you
> > could
> > read it. But why do it that way? That's what diskdump_get_phys_base()
and
> > kdump_get_phys_base() are supposed to do.
>
> Because I believe that this is the *common* place to do it either for
> diskdump, or kdump ( or even a live system if we know kimage_voffset.)
Well, as I have shown, it won't work on my live system because of the
chicken-and-egg scenario. Let's worry about live system analysis after
we get kdump straightened out.
See above.
> >
> > > break;
> > >
> > > case POST_GDB:
> > > @@ -409,6 +471,8 @@ arm64_dump_machdep_table(ulong arg)
> > > fprintf(fp, "%sIRQ_STACKS", others++ ? "|" :
"");
> > > if (machdep->flags & MACHDEP_BT_TEXT)
> > > fprintf(fp, "%sMACHDEP_BT_TEXT", others++ ? "|" :
"");
> > > + if (machdep->flags & NEW_VMEMMAP)
> > > + fprintf(fp, "%sNEW_VMEMMAP", others++ ? "|" :
"");
> > > fprintf(fp, ")\n");
> > >
> > > fprintf(fp, " kvbase: %lx\n",
machdep->kvbase);
> > > @@ -494,6 +558,8 @@ arm64_dump_machdep_table(ulong arg)
> > > ms = machdep->machspec;
> > >
> > > fprintf(fp, " machspec: %lx\n", (ulong)ms);
> > > + fprintf(fp, " memory map layout: %s\n",
> > > + (machdep->flags & NEW_VMEMMAP) ? "new" :
"old");
> >
> > As before, these internal "help" structure dumps just show existing
> > structure fields,
> > and NEW_VMMEMAP is already shown in the flags.
>
> I put it as useful information for those people who might have got
> any concerns about those odd numbers/kernel layout.
> But if you don't like it, I will remove it.
I removed it.
> >
> > > fprintf(fp, " VA_BITS: %ld\n", ms->VA_BITS);
> > > fprintf(fp, " userspace_top: %016lx\n",
ms->userspace_top);
> > > fprintf(fp, " page_offset: %016lx\n",
ms->page_offset);
> > > @@ -503,6 +569,11 @@ arm64_dump_machdep_table(ulong arg)
> > > fprintf(fp, " modules_end: %016lx\n",
ms->modules_end);
> > > fprintf(fp, " vmemmap_vaddr: %016lx\n",
ms->vmemmap_vaddr);
> > > fprintf(fp, " vmemmap_end: %016lx\n",
ms->vmemmap_end);
> > > + if (machdep->flags & NEW_VMEMMAP) {
> > > + fprintf(fp, " kimage_text: %016lx\n",
ms->kimage_text);
> > > + fprintf(fp, " kimage_end: %016lx\n",
ms->kimage_end);
> > > + fprintf(fp, " kimage_voffset: %016lx\n",
ms->kimage_voffset);
> > > + }
> > > fprintf(fp, " phys_offset: %lx\n",
ms->phys_offset);
> > > fprintf(fp, "__exception_text_start: %lx\n",
> > > ms->__exception_text_start);
> > > fprintf(fp, " __exception_text_end: %lx\n",
ms->__exception_text_end);
> > > @@ -543,6 +614,42 @@ arm64_dump_machdep_table(ulong arg)
> > > }
> > > }
> > >
> > > +static int
> > > +arm64_parse_machdep_arg_l(char *argstring, char *param, ulong *value)
> > > +{
> > > + int len;
> > > + int megabytes = FALSE;
> > > + char *p;
> > > +
> > > + len = strlen(param);
> > > + if (!STRNEQ(argstring, param) || (argstring[len] != '='))
> > > + return FALSE;
> > > +
> > > + if ((LASTCHAR(argstring) == 'm') ||
> > > + (LASTCHAR(argstring) == 'M')) {
> > > + LASTCHAR(argstring) = NULLCHAR;
> > > + megabytes = TRUE;
> > > + }
> > > +
> > > + p = argstring + len + 1;
> > > + if (strlen(p)) {
> > > + int flags = RETURN_ON_ERROR | QUIET;
> > > + int err = 0;
> > > +
> > > + if (megabytes) {
> > > + *value = dtol(p, flags, &err);
> > > + if (!err)
> > > + *value = MEGABYTES(*value);
> > > + } else {
> > > + *value = htol(p, flags, &err);
> > > + }
> > > +
> > > + if (!err)
> > > + return TRUE;
> > > + }
> > > +
> > > + return FALSE;
> > > +}
> > >
> > > /*
> > > * Parse machine dependent command line arguments.
> > > @@ -554,11 +661,10 @@ arm64_dump_machdep_table(ulong arg)
> > > static void
> > > arm64_parse_cmdline_args(void)
> > > {
> > > - int index, i, c, err;
> > > + int index, i, c;
> > > char *arglist[MAXARGS];
> > > char buf[BUFSIZE];
> > > char *p;
> > > - ulong value = 0;
> > >
> > > for (index = 0; index < MAX_MACHDEP_ARGS; index++) {
> > > if (!machdep->cmdline_args[index])
> > > @@ -580,39 +686,23 @@ arm64_parse_cmdline_args(void)
> > > c = parse_line(buf, arglist);
> > >
> > > for (i = 0; i < c; i++) {
> > > - err = 0;
> > > -
> > > - if (STRNEQ(arglist[i], "phys_offset=")) {
> > > - int megabytes = FALSE;
> > > - int flags = RETURN_ON_ERROR | QUIET;
> > > -
> > > - if ((LASTCHAR(arglist[i]) == 'm') ||
> > > - (LASTCHAR(arglist[i]) == 'M')) {
> > > - LASTCHAR(arglist[i]) = NULLCHAR;
> > > - megabytes = TRUE;
> > > - }
> > > -
> > > - p = arglist[i] + strlen("phys_offset=");
> > > - if (strlen(p)) {
> > > - if (megabytes)
> > > - value = dtol(p, flags, &err);
> > > - else
> > > - value = htol(p, flags, &err);
> > > - }
> > > -
> > > - if (!err) {
> > > - if (megabytes)
> > > - value = MEGABYTES(value);
> > > -
> > > - machdep->machspec->phys_offset = value;
> > > -
> > > - error(NOTE,
> > > - "setting phys_offset to: 0x%lx\n\n",
> > > - machdep->machspec->phys_offset);
> > > + if (arm64_parse_machdep_arg_l(arglist[i],
> > > + "phys_offset",
> > > + &machdep->machspec->phys_offset)) {
> > > + error(NOTE,
> > > + "setting phys_offset to: 0x%lx\n\n",
> > > + machdep->machspec->phys_offset);
> > > +
> > > + machdep->flags |= PHYS_OFFSET;
> > > + continue;
> > > + } else if (arm64_parse_machdep_arg_l(arglist[i],
> > > + "kimage_voffset",
> > > + &machdep->machspec->kimage_voffset)) {
> > > + error(NOTE,
> > > + "setting kimage_voffset to: 0x%lx\n\n",
> > > + machdep->machspec->kimage_voffset);
> > >
> > > - machdep->flags |= PHYS_OFFSET;
> > > - continue;
> > > - }
> > > + continue;
> > > }
> > >
> > > error(WARNING, "ignoring --machdep option: %s\n",
> > > @@ -627,10 +717,20 @@ arm64_calc_phys_offset(void)
> > > {
> > > struct machine_specific *ms = machdep->machspec;
> > > ulong phys_offset;
> > > + struct syment *sp;
> > > + ulong value;
> > >
> > > if (machdep->flags & PHYS_OFFSET) /* --machdep override */
> > > return;
> > >
> > > + sp = kernel_symbol_search("memstart_addr");
> > > + if (sp && readmem(sp->value, KVADDR, (char *)&value,
sizeof(value),
> > > + "memstart_addr", QUIET|RETURN_ON_ERROR)) {
> > > + ms->phys_offset = value;
> > > + machdep->flags |= PHYS_OFFSET;
> > > + return;
> > > + }
> > > +
> >
> > Also, I may be missing something, but the PHYS_OFFSET flag means that it
> > was
> > passed in via --machdep, and is only used in this function to avoid any
> > further
> > attempts to figure out what it is. Here you are setting the flag for no
> > particular
> > reason that I can see. Why?
>
> Well, I don't remember very well. If not necessary, I will remove it.
OK, I guarantee it's useless in this case...
I removed it.
Thanks,
-Takahiro AKASHI
> > But again, doing a readmem() call this early is setting a
bad precedent --
> > they have
> > *always* been delayed until after gdb_session_init() in main_loop(). And
> > the work
> > of determining phys_base should be done by the dumpfile call-out functions
> > that
> > already exist.
> >
> >
> > > /*
> > > * Next determine suitable value for phys_offset. User can override
> > > this
> > > * by passing valid '--machdep phys_offset=<addr>'
option.
> > > @@ -2377,6 +2477,11 @@ arm64_IS_VMALLOC_ADDR(ulong vaddr)
> > > {
> > > struct machine_specific *ms = machdep->machspec;
> > >
> > > + if ((machdep->flags & NEW_VMEMMAP) &&
> > > + (vaddr >= machdep->machspec->kimage_text) &&
> > > + (vaddr <= machdep->machspec->kimage_end))
> > > + return FALSE;
> > > +
> > > return ((vaddr >= ms->vmalloc_start_addr && vaddr
<=
> > > ms->vmalloc_end) ||
> > > ((machdep->flags & VMEMMAP) &&
> > > (vaddr >= ms->vmemmap_vaddr && vaddr
<=
> > > ms->vmemmap_end))
> > > ||
> > > @@ -2407,7 +2512,11 @@ arm64_calc_VA_BITS(void)
> > >
> > > for (bitval = highest_bit_long(value); bitval; bitval--) {
> > > if ((value & (1UL << bitval)) == 0) {
> > > +#if 1
> > > + machdep->machspec->VA_BITS = bitval + 1;
> > > +#else /* FIXME: bug? */
> > > machdep->machspec->VA_BITS = bitval + 2;
> > > +#endif
> > > break;
> > > }
> > > }
> >
> > Again, a non-starter until the above is resolved -- but you know that
> > already...
>
> Just a reminder for now.
>
> >
> > > @@ -2459,10 +2568,22 @@ arm64_calc_virtual_memory_ranges(void)
> > > break;
> > > }
> > >
> > > - vmemmap_size = ALIGN((1UL << (ms->VA_BITS -
machdep->pageshift)) *
> > > SIZE(page), PUD_SIZE);
> > > + if (machdep->flags & NEW_VMEMMAP)
> > > +#define STRUCT_PAGE_MAX_SHIFT 6
> > > + vmemmap_size = 1UL << (ms->VA_BITS - machdep->pageshift -
1
> > > + + STRUCT_PAGE_MAX_SHIFT);
> > > + else
> > > + vmemmap_size = ALIGN((1UL << (ms->VA_BITS -
machdep->pageshift)) *
> > > SIZE(page), PUD_SIZE);
> > > +
> > > vmalloc_end = (ms->page_offset - PUD_SIZE - vmemmap_size - SZ_64K);
> > > - vmemmap_start = vmalloc_end + SZ_64K;
> > > - vmemmap_end = vmemmap_start + vmemmap_size;
> > > +
> > > + if (machdep->flags & NEW_VMEMMAP) {
> > > + vmemmap_start = ms->page_offset - vmemmap_size;
> > > + vmemmap_end = ms->page_offset;
> > > + } else {
> > > + vmemmap_start = vmalloc_end + SZ_64K;
> > > + vmemmap_end = vmemmap_start + vmemmap_size;
> > > + }
> > >
> > > ms->vmalloc_end = vmalloc_end - 1;
> > > ms->vmemmap_vaddr = vmemmap_start;
> > > diff --git a/defs.h b/defs.h
> > > index a09fa9a..2bbb55b 100644
> > > --- a/defs.h
> > > +++ b/defs.h
> > > @@ -2844,8 +2844,8 @@ typedef u64 pte_t;
> > >
> > > #define PTOV(X) \
> > > ((unsigned
> > >
long)(X)-(machdep->machspec->phys_offset)+(machdep->machspec->page_offset))
> > > -#define VTOP(X) \
> > > - ((unsigned
> > >
long)(X)-(machdep->machspec->page_offset)+(machdep->machspec->phys_offset))
> > > +
> > > +#define VTOP(X) arm64_VTOP((ulong)(X))
> > >
> > > #define USERSPACE_TOP (machdep->machspec->userspace_top)
> > > #define PAGE_OFFSET (machdep->machspec->page_offset)
> > > @@ -2938,18 +2938,23 @@ typedef signed int s32;
> > > #define VM_L3_4K (0x10)
> > > #define KDUMP_ENABLED (0x20)
> > > #define IRQ_STACKS (0x40)
> > > +#define NEW_VMEMMAP (0x80)
> > >
> > > /*
> > > * sources: Documentation/arm64/memory.txt
> > > * arch/arm64/include/asm/memory.h
> > > * arch/arm64/include/asm/pgtable.h
> > > */
> > > -
> > > -#define ARM64_PAGE_OFFSET ((0xffffffffffffffffUL) <<
> > > (machdep->machspec->VA_BITS - 1))
> > > +#define ARM64_VA_START ((0xffffffffffffffffUL) \
> > > + << machdep->machspec->VA_BITS)
> > > +#define ARM64_PAGE_OFFSET ((0xffffffffffffffffUL) \
> > > + << (machdep->machspec->VA_BITS - 1))
> > > #define ARM64_USERSPACE_TOP ((1UL) <<
machdep->machspec->VA_BITS)
> > > -#define ARM64_MODULES_VADDR (ARM64_PAGE_OFFSET - MEGABYTES(64))
> > > -#define ARM64_MODULES_END (ARM64_PAGE_OFFSET - 1)
> > > -#define ARM64_VMALLOC_START ((0xffffffffffffffffUL) <<
> > > machdep->machspec->VA_BITS)
> > > +
> > > +/* only used for v4.6 or later */
> > > +#define ARM64_MODULES_VSIZE MEGABYTES(128)
> > > +#define ARM64_KASAN_SHADOW_SIZE (1UL <<
(machdep->machspec->VA_BITS -
> > > 3))
> > > +
> > > /*
> > > * The following 3 definitions are the original values, but are obsolete
> > > * for 3.17 and later kernels because they are now build-time
> > > calculations.
> > > @@ -3028,6 +3033,10 @@ struct machine_specific {
> > > ulong kernel_flags;
> > > ulong irq_stack_size;
> > > ulong *irq_stacks;
> > > + /* only needed for kaslr-enabled kernel */
> > > + ulong kimage_voffset;
> > > + ulong kimage_text;
> > > + ulong kimage_end;
> > > };
> >
> > The comment is wrong -- the kimage_text and kimage_end values are needed
> > for
> > NEW_VMEMMAP kernels that are NOT configured with CONFIG_RANDOMIZE_BASE.
> > Unless you consider my live system "kaslr-enabled"?
>
> I will change it to "for v4.6 or later".
>
> I have limited (or no) time to investigate a live-system case, and so if
> you have any suggestions or your own patch, it is very much appreciated.
Yep... but I will build upon your solid foundation.
If I see anything interesting/different after my live system upgrade, I'll let
you know.
Thanks,
Dave
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-Takahiro AKASHI
4:39 a.m.
On 26/05/2016:05:13:30 PM, AKASHI Takahiro wrote:
On Wed, May 25, 2016 at 10:28:10AM -0400, Dave Anderson wrote:
[...]
> > (This is the reason that I don't think we need a
VMCOREINFO for
> > CONFIG_RANDOMIZE_BASE.)
>
> Well, as long as there's a way to avoid that unnecessary/confusing
> warning message for non-KASLR new-vmemmap kernels.
>
> I also wonder whether makedumpfile could use it?
-> Pratyush?
Since second kernel's initrd cannot include a large file like VMLINUX, so
makedumpfile should also work without passing '-x vmlinux'. Therefore,
makedumpfile will need some minimal symbol's values to be passed in vmcore.
IIUC, then you need to pass CONFIG_RANDOMIZE_BASE in order to calculate
PHYS_OFFSET. If yes, then why not to pass PHYS_OFFSET itself into vmcore.
Following numbers in vmcore [1] is helping me out in implementing __pa() and
__va() for all page table sizes and levels.
VMCOREINFO_NUMBER(pgtable_levels);
VMCOREINFO_NUMBER(va_bits);
VMCOREINFO_NUMBER(page_shift);
VMCOREINFO_NUMBER(phys_offset);
VMCOREINFO_NUMBER(config_kasan);
VMCOREINFO_NUMBER(kimage_voffset);
~Pratyush
[1]
https://github.com/pratyushanand/linux/blob/7011e478aae3e568cc8dca15b6c12...
11:03 p.m.
On Thu, May 26, 2016 at 03:09:55PM +0530, Pratyush Anand wrote:
On 26/05/2016:05:13:30 PM, AKASHI Takahiro wrote:
> On Wed, May 25, 2016 at 10:28:10AM -0400, Dave Anderson wrote:
[...]
> > > (This is the reason that I don't think we need a VMCOREINFO for
> > > CONFIG_RANDOMIZE_BASE.)
> >
> > Well, as long as there's a way to avoid that unnecessary/confusing
> > warning message for non-KASLR new-vmemmap kernels.
> >
> > I also wonder whether makedumpfile could use it?
>
> -> Pratyush?
Since second kernel's initrd cannot include a large file like VMLINUX, so
makedumpfile should also work without passing '-x vmlinux'. Therefore,
makedumpfile will need some minimal symbol's values to be passed in vmcore.
I understand.
(but I wonder why makedumpfile doesn't utilize System.map nor .config.)
IIUC, then you need to pass CONFIG_RANDOMIZE_BASE in order to
calculate
PHYS_OFFSET. If yes, then why not to pass PHYS_OFFSET itself into vmcore.
No, as I said in the discussions, I don't think that we need
CONFIG_RANDOMIZE_BASE *if* we can read a kernel symbol's value
from /proc/vmcore.
Following numbers in vmcore [1] is helping me out in implementing
__pa() and
__va() for all page table sizes and levels.
VMCOREINFO_NUMBER(pgtable_levels);
VMCOREINFO_NUMBER(va_bits);
VMCOREINFO_NUMBER(page_shift);
Since We already have VMCOREINFO(PAGESIZE), we won't nedd page_shift.
As well, pgtable_levels can be determined by va_bits and PAGESIZE.
See arch/arm64/Kconfig.
VMCOREINFO_NUMBER(phys_offset);
VMCOREINFO_NUMBER(config_kasan);
Let me ask some questions.
* What kind of data in vmcore and how does makedumpfile access
without vmlinux nor System.map?
* Why do you need CONFIG_KASAN?
Thanks,
-Takahiro AKASHI
VMCOREINFO_NUMBER(kimage_voffset);
~Pratyush
[1]
https://github.com/pratyushanand/linux/blob/7011e478aae3e568cc8dca15b6c12...
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-Takahiro AKASHI
12:07 a.m.
On 27/05/2016:01:03:56 PM, AKASHI Takahiro wrote:
On Thu, May 26, 2016 at 03:09:55PM +0530, Pratyush Anand wrote:
> On 26/05/2016:05:13:30 PM, AKASHI Takahiro wrote:
> > On Wed, May 25, 2016 at 10:28:10AM -0400, Dave Anderson wrote:
>
> [...]
>
> > > > (This is the reason that I don't think we need a VMCOREINFO for
> > > > CONFIG_RANDOMIZE_BASE.)
> > >
> > > Well, as long as there's a way to avoid that unnecessary/confusing
> > > warning message for non-KASLR new-vmemmap kernels.
> > >
> > > I also wonder whether makedumpfile could use it?
> >
> > -> Pratyush?
>
> Since second kernel's initrd cannot include a large file like VMLINUX, so
> makedumpfile should also work without passing '-x vmlinux'. Therefore,
> makedumpfile will need some minimal symbol's values to be passed in vmcore.
I understand.
(but I wonder why makedumpfile doesn't utilize System.map nor .config.)
So far makedumpfile has been designed to work only with vmcore as input in it's
minimal form (specially in second kernel).
+Atsushi & makedumpfile list: He will have better idea about it.
Moreover, there are few variables, whose values are needed in order to translate
phys to virt and vice versa. So, passing their symbol address would not be of
much help. For example, we need to know value of kimage_voffset for __pa(), and
so symbol address of kimage_voffset will not help.
> IIUC, then you need to pass CONFIG_RANDOMIZE_BASE in order to calculate
> PHYS_OFFSET. If yes, then why not to pass PHYS_OFFSET itself into vmcore.
No, as I said in the discussions, I don't think that we need
CONFIG_RANDOMIZE_BASE *if* we can read a kernel symbol's value
from /proc/vmcore.
What I understand that, we can read only those symbols/variables from vmcore
which have been embedded using VMCOREINFO_xxxx macros (if we do not pass
vmlinux, like in second kernel). Atsushi, please correct me if I am wrong.
> Following numbers in vmcore [1] is helping me out in implementing __pa() and
> __va() for all page table sizes and levels.
>
> VMCOREINFO_NUMBER(pgtable_levels);
> VMCOREINFO_NUMBER(va_bits);
> VMCOREINFO_NUMBER(page_shift);
Since We already have VMCOREINFO(PAGESIZE), we won't nedd page_shift.
Yes, agreed.
As well, pgtable_levels can be determined by va_bits and PAGESIZE.
See arch/arm64/Kconfig.
Yes, agreed.
> VMCOREINFO_NUMBER(phys_offset);
> VMCOREINFO_NUMBER(config_kasan);
Let me ask some questions.
* What kind of data in vmcore and how does makedumpfile access
without vmlinux nor System.map?
Well, I do not have the deep idea, again Atsushi can help here.
makedumpfile mainly compresses vmcore (ram image of panicked kernel),
additionally it also excludes unnecessary pages for analysis. It will need
symbol information to exclude unnecessary pages, where vmlinux is needed mainly.
So, normally we do not perform erase(exclude) functionality in second kernel. It
is being performed latter, on a compressed dumpfile.
* Why do you need CONFIG_KASAN?
KASAN_SHADOW_SIZE is dependent on CONFIG_KASAN.
MODULES_VADDR is dependent on KASAN_SHADOW_SIZE.
We need MODULES_VADDR,VMALLOC_START,VMEMMAP_START and their END addresses in
order to define whether a virtual to physical translation can be obtained using
linear mapping or need to read from page table instead.
Thanks for the questions and inputs. Those are helpful. :-)
~Pratyush
Thanks,
-Takahiro AKASHI
> VMCOREINFO_NUMBER(kimage_voffset);
>
> ~Pratyush
>
> [1]
>
https://github.com/pratyushanand/linux/blob/7011e478aae3e568cc8dca15b6c12...
>
> --
> Crash-utility mailing list
> Crash-utility(a)redhat.com
> https://www.redhat.com/mailman/listinfo/crash-utility
--
Thanks,
-Takahiro AKASHI
--
Crash-utility mailing list
Crash-utility(a)redhat.com
https://www.redhat.com/mailman/listinfo/crash-utility
1:43 a.m.
On Fri, May 27, 2016 at 10:37:38AM +0530, Pratyush Anand wrote:
On 27/05/2016:01:03:56 PM, AKASHI Takahiro wrote:
> On Thu, May 26, 2016 at 03:09:55PM +0530, Pratyush Anand wrote:
> > On 26/05/2016:05:13:30 PM, AKASHI Takahiro wrote:
> > > On Wed, May 25, 2016 at 10:28:10AM -0400, Dave Anderson wrote:
> >
> > [...]
> >
> > > > > (This is the reason that I don't think we need a VMCOREINFO
for
> > > > > CONFIG_RANDOMIZE_BASE.)
> > > >
> > > > Well, as long as there's a way to avoid that
unnecessary/confusing
> > > > warning message for non-KASLR new-vmemmap kernels.
> > > >
> > > > I also wonder whether makedumpfile could use it?
> > >
> > > -> Pratyush?
> >
> > Since second kernel's initrd cannot include a large file like VMLINUX, so
> > makedumpfile should also work without passing '-x vmlinux'.
Therefore,
> > makedumpfile will need some minimal symbol's values to be passed in
vmcore.
>
> I understand.
> (but I wonder why makedumpfile doesn't utilize System.map nor .config.)
So far makedumpfile has been designed to work only with vmcore as input in it's
minimal form (specially in second kernel).
+Atsushi & makedumpfile list: He will have better idea about it.
Moreover, there are few variables, whose values are needed in order to translate
phys to virt and vice versa. So, passing their symbol address would not be of
much help. For example, we need to know value of kimage_voffset for __pa(), and
so symbol address of kimage_voffset will not help.
I do agree to adding any vmcoreinfo *if* it is really needed,
and so I'm asking why you need it.
What I'm thinking now is that I would add a minimal set of vmcoreinfo
which are necessary for crash util to work (for /proc/vmcore, not a live
system) and then, if you want to add anything else, you can post your
own patch.
Make sense?
But I think ...
If we would eventually add, say, "NUMBER(va_bits)", makedumpfile() will
use it, but crash util doen't. Looks a bit odd.
-> Dave, do you have any opinion here?
>
> > IIUC, then you need to pass CONFIG_RANDOMIZE_BASE in order to calculate
> > PHYS_OFFSET. If yes, then why not to pass PHYS_OFFSET itself into vmcore.
>
> No, as I said in the discussions, I don't think that we need
> CONFIG_RANDOMIZE_BASE *if* we can read a kernel symbol's value
> from /proc/vmcore.
What I understand that, we can read only those symbols/variables from vmcore
which have been embedded using VMCOREINFO_xxxx macros (if we do not pass
vmlinux, like in second kernel). Atsushi, please correct me if I am wrong.
>
> > Following numbers in vmcore [1] is helping me out in implementing __pa() and
> > __va() for all page table sizes and levels.
> >
> > VMCOREINFO_NUMBER(pgtable_levels);
> > VMCOREINFO_NUMBER(va_bits);
> > VMCOREINFO_NUMBER(page_shift);
>
> Since We already have VMCOREINFO(PAGESIZE), we won't nedd page_shift.
Yes, agreed.
> As well, pgtable_levels can be determined by va_bits and PAGESIZE.
> See arch/arm64/Kconfig.
Yes, agreed.
>
> > VMCOREINFO_NUMBER(phys_offset);
> > VMCOREINFO_NUMBER(config_kasan);
>
> Let me ask some questions.
> * What kind of data in vmcore and how does makedumpfile access
> without vmlinux nor System.map?
Well, I do not have the deep idea, again Atsushi can help here.
makedumpfile mainly compresses vmcore (ram image of panicked kernel),
additionally it also excludes unnecessary pages for analysis. It will need
symbol information to exclude unnecessary pages, where vmlinux is needed mainly.
So, normally we do not perform erase(exclude) functionality in second kernel. It
is being performed latter, on a compressed dumpfile.
Well, I don't look into the makedumpfile code in details, it only accesses
MMU tables and struct page data. So you need a few *well-known* symbols'
values in vmcore.
> * Why do you need CONFIG_KASAN?
KASAN_SHADOW_SIZE is dependent on CONFIG_KASAN.
MODULES_VADDR is dependent on KASAN_SHADOW_SIZE.
We need MODULES_VADDR,VMALLOC_START,VMEMMAP_START and their END addresses in
order to define whether a virtual to physical translation can be obtained using
linear mapping or need to read from page table instead.
I guess that we can check for this simply like:
vaddr >= PAGE_OFFSET || ("_text" <= vaddr < "_end")
(Again, *if* we can access kernel symbols' values.)
Thanks,
-Takahiro AKASHI
Thanks for the questions and inputs. Those are helpful. :-)
~Pratyush
>
> Thanks,
> -Takahiro AKASHI
>
> > VMCOREINFO_NUMBER(kimage_voffset);
> >
> > ~Pratyush
> >
> > [1]
> >
https://github.com/pratyushanand/linux/blob/7011e478aae3e568cc8dca15b6c12...
> >
> > --
> > Crash-utility mailing list
> > Crash-utility(a)redhat.com
> > https://www.redhat.com/mailman/listinfo/crash-utility
>
> --
> Thanks,
> -Takahiro AKASHI
>
> --
> Crash-utility mailing list
> Crash-utility(a)redhat.com
> https://www.redhat.com/mailman/listinfo/crash-utility
--
Thanks,
-Takahiro AKASHI
2:28 a.m.
On 27/05/2016:03:43:33 PM, AKASHI Takahiro wrote:
On Fri, May 27, 2016 at 10:37:38AM +0530, Pratyush Anand wrote:
> On 27/05/2016:01:03:56 PM, AKASHI Takahiro wrote:
> > On Thu, May 26, 2016 at 03:09:55PM +0530, Pratyush Anand wrote:
> > > On 26/05/2016:05:13:30 PM, AKASHI Takahiro wrote:
> > > > On Wed, May 25, 2016 at 10:28:10AM -0400, Dave Anderson wrote:
> > >
> > > [...]
> > >
> > > > > > (This is the reason that I don't think we need a
VMCOREINFO for
> > > > > > CONFIG_RANDOMIZE_BASE.)
> > > > >
> > > > > Well, as long as there's a way to avoid that
unnecessary/confusing
> > > > > warning message for non-KASLR new-vmemmap kernels.
> > > > >
> > > > > I also wonder whether makedumpfile could use it?
> > > >
> > > > -> Pratyush?
> > >
> > > Since second kernel's initrd cannot include a large file like
VMLINUX, so
> > > makedumpfile should also work without passing '-x vmlinux'.
Therefore,
> > > makedumpfile will need some minimal symbol's values to be passed in
vmcore.
> >
> > I understand.
> > (but I wonder why makedumpfile doesn't utilize System.map nor .config.)
>
> So far makedumpfile has been designed to work only with vmcore as input in it's
> minimal form (specially in second kernel).
> +Atsushi & makedumpfile list: He will have better idea about it.
>
> Moreover, there are few variables, whose values are needed in order to translate
> phys to virt and vice versa. So, passing their symbol address would not be of
> much help. For example, we need to know value of kimage_voffset for __pa(), and
> so symbol address of kimage_voffset will not help.
I do agree to adding any vmcoreinfo *if* it is really needed,
and so I'm asking why you need it.
What I'm thinking now is that I would add a minimal set of vmcoreinfo
which are necessary for crash util to work (for /proc/vmcore, not a live
system) and then, if you want to add anything else, you can post your
own patch.
Make sense?
Yes, No issue.
In fact, I do not have any plan to send arm64 makedulpfile enhancement either
until kernel support is upstreamed.
But I think ...
If we would eventually add, say, "NUMBER(va_bits)", makedumpfile() will
use it, but crash util doen't. Looks a bit odd.
-> Dave, do you have any opinion here?
> >
> > > IIUC, then you need to pass CONFIG_RANDOMIZE_BASE in order to calculate
> > > PHYS_OFFSET. If yes, then why not to pass PHYS_OFFSET itself into vmcore.
> >
> > No, as I said in the discussions, I don't think that we need
> > CONFIG_RANDOMIZE_BASE *if* we can read a kernel symbol's value
> > from /proc/vmcore.
>
> What I understand that, we can read only those symbols/variables from vmcore
> which have been embedded using VMCOREINFO_xxxx macros (if we do not pass
> vmlinux, like in second kernel). Atsushi, please correct me if I am wrong.
>
> >
> > > Following numbers in vmcore [1] is helping me out in implementing __pa()
and
> > > __va() for all page table sizes and levels.
> > >
> > > VMCOREINFO_NUMBER(pgtable_levels);
> > > VMCOREINFO_NUMBER(va_bits);
> > > VMCOREINFO_NUMBER(page_shift);
> >
> > Since We already have VMCOREINFO(PAGESIZE), we won't nedd page_shift.
>
> Yes, agreed.
>
> > As well, pgtable_levels can be determined by va_bits and PAGESIZE.
> > See arch/arm64/Kconfig.
>
> Yes, agreed.
>
> >
> > > VMCOREINFO_NUMBER(phys_offset);
> > > VMCOREINFO_NUMBER(config_kasan);
> >
> > Let me ask some questions.
> > * What kind of data in vmcore and how does makedumpfile access
> > without vmlinux nor System.map?
>
> Well, I do not have the deep idea, again Atsushi can help here.
>
> makedumpfile mainly compresses vmcore (ram image of panicked kernel),
> additionally it also excludes unnecessary pages for analysis. It will need
> symbol information to exclude unnecessary pages, where vmlinux is needed mainly.
> So, normally we do not perform erase(exclude) functionality in second kernel. It
> is being performed latter, on a compressed dumpfile.
Well, I don't look into the makedumpfile code in details, it only accesses
MMU tables and struct page data. So you need a few *well-known* symbols'
values in vmcore.
> > * Why do you need CONFIG_KASAN?
>
> KASAN_SHADOW_SIZE is dependent on CONFIG_KASAN.
> MODULES_VADDR is dependent on KASAN_SHADOW_SIZE.
>
> We need MODULES_VADDR,VMALLOC_START,VMEMMAP_START and their END addresses in
> order to define whether a virtual to physical translation can be obtained using
> linear mapping or need to read from page table instead.
I guess that we can check for this simply like:
vaddr >= PAGE_OFFSET || ("_text" <= vaddr < "_end")
(Again, *if* we can access kernel symbols' values.)
Unfortunately, We have _stext in vmcore but we do not have _text and _end.
However, instead of passing CONFIG_KASAN and then calculating module, vmalloc
and vmemmap areas in makedumpfile, it would be cleaner to pass _text and _end.
Then, makedumpfile will be immune to changes in kernel for memory layout of
these spaces.
~Pratyush
Thanks,
-Takahiro AKASHI
> Thanks for the questions and inputs. Those are helpful. :-)
> ~Pratyush
> >
> > Thanks,
> > -Takahiro AKASHI
> >
> > > VMCOREINFO_NUMBER(kimage_voffset);
> > >
> > > ~Pratyush
> > >
> > > [1]
> > >
https://github.com/pratyushanand/linux/blob/7011e478aae3e568cc8dca15b6c12...
> > >
> > > --
> > > Crash-utility mailing list
> > > Crash-utility(a)redhat.com
> > > https://www.redhat.com/mailman/listinfo/crash-utility
> >
> > --
> > Thanks,
> > -Takahiro AKASHI
> >
> > --
> > Crash-utility mailing list
> > Crash-utility(a)redhat.com
> > https://www.redhat.com/mailman/listinfo/crash-utility
--
Thanks,
-Takahiro AKASHI
3:10 a.m.
Hello,
On 27/05/2016:01:03:56 PM, AKASHI Takahiro wrote:
> On Thu, May 26, 2016 at 03:09:55PM +0530, Pratyush Anand wrote:
> > On 26/05/2016:05:13:30 PM, AKASHI Takahiro wrote:
> > > On Wed, May 25, 2016 at 10:28:10AM -0400, Dave Anderson wrote:
> >
> > [...]
> >
> > > > > (This is the reason that I don't think we need a VMCOREINFO
for
> > > > > CONFIG_RANDOMIZE_BASE.)
> > > >
> > > > Well, as long as there's a way to avoid that
unnecessary/confusing
> > > > warning message for non-KASLR new-vmemmap kernels.
> > > >
> > > > I also wonder whether makedumpfile could use it?
> > >
> > > -> Pratyush?
> >
> > Since second kernel's initrd cannot include a large file like VMLINUX, so
> > makedumpfile should also work without passing '-x vmlinux'. Therefore,
> > makedumpfile will need some minimal symbol's values to be passed in vmcore.
>
> I understand.
> (but I wonder why makedumpfile doesn't utilize System.map nor .config.)
So far makedumpfile has been designed to work only with vmcore as input in it's
minimal form (specially in second kernel).
+Atsushi & makedumpfile list: He will have better idea about it.
I'm not the designer, but I think it was designed to get robustness.
If /proc/vmcore itself provides the stuffs for analysis, it prevents the
inconsistency between passed symbol list(like System.map) and actual kernel
memory image.
Additionally, makedumpfile requires not only symbol address list but struct
member's offset, struct size and enum number. So vmcoreinfo is needed anyway.
Moreover, there are few variables, whose values are needed in order to
translate
phys to virt and vice versa. So, passing their symbol address would not be of
much help. For example, we need to know value of kimage_voffset for __pa(), and
so symbol address of kimage_voffset will not help.
>
> > IIUC, then you need to pass CONFIG_RANDOMIZE_BASE in order to calculate
> > PHYS_OFFSET. If yes, then why not to pass PHYS_OFFSET itself into vmcore.
>
> No, as I said in the discussions, I don't think that we need
> CONFIG_RANDOMIZE_BASE *if* we can read a kernel symbol's value
> from /proc/vmcore.
What I understand that, we can read only those symbols/variables from vmcore
which have been embedded using VMCOREINFO_xxxx macros (if we do not pass
vmlinux, like in second kernel). Atsushi, please correct me if I am wrong.
That's right.
>
> > Following numbers in vmcore [1] is helping me out in implementing __pa() and
> > __va() for all page table sizes and levels.
> >
> > VMCOREINFO_NUMBER(pgtable_levels);
> > VMCOREINFO_NUMBER(va_bits);
> > VMCOREINFO_NUMBER(page_shift);
>
> Since We already have VMCOREINFO(PAGESIZE), we won't nedd page_shift.
Yes, agreed.
> As well, pgtable_levels can be determined by va_bits and PAGESIZE.
> See arch/arm64/Kconfig.
Yes, agreed.
>
> > VMCOREINFO_NUMBER(phys_offset);
> > VMCOREINFO_NUMBER(config_kasan);
>
> Let me ask some questions.
> * What kind of data in vmcore and how does makedumpfile access
> without vmlinux nor System.map?
Well, I do not have the deep idea, again Atsushi can help here.
makedumpfile mainly compresses vmcore (ram image of panicked kernel),
additionally it also excludes unnecessary pages for analysis. It will need
symbol information to exclude unnecessary pages, where vmlinux is needed mainly.
So, normally we do not perform erase(exclude) functionality in second kernel. It
is being performed latter, on a compressed dumpfile.
Yes, basically the data in vmcore are used to exclude unnecessary pages.
Most data are required to get the members of struct page to distinguish
what kind of page it is.
Thanks,
Astushi Kumagai
> * Why do you need CONFIG_KASAN?
KASAN_SHADOW_SIZE is dependent on CONFIG_KASAN.
MODULES_VADDR is dependent on KASAN_SHADOW_SIZE.
We need MODULES_VADDR,VMALLOC_START,VMEMMAP_START and their END addresses in
order to define whether a virtual to physical translation can be obtained using
linear mapping or need to read from page table instead.
Thanks for the questions and inputs. Those are helpful. :-)
~Pratyush
>
> Thanks,
> -Takahiro AKASHI
>
> > VMCOREINFO_NUMBER(kimage_voffset);
> >
> > ~Pratyush
> >
> > [1]
> >
https://github.com/pratyushanand/linux/blob/7011e478aae3e568cc8dca15b6c12...
.c#L275
> >
> > --
> > Crash-utility mailing list
> > Crash-utility(a)redhat.com
> > https://www.redhat.com/mailman/listinfo/crash-utility
>
> --
> Thanks,
> -Takahiro AKASHI
>
> --
> Crash-utility mailing list
> Crash-utility(a)redhat.com
> https://www.redhat.com/mailman/listinfo/crash-utility
8:44 a.m.
----- Original Message -----
> > > > 3) Backtracing a 'panic'ed task fails:
> > > > crash> bt
> > > > PID: 999 TASK: ffffffe960081800 CPU: 0 COMMAND:
"sh"
> > > > bt: WARNING: corrupt prstatus? pstate=0x80000000, but no user frame
found
> > > > bt: WARNING: cannot determine starting stack frame for task
ffffffe960081800
> > > >
> > > > frame->pc indicates that it is a kernel address, so obviously
something
> > > > is wrong. I'm diggin into it.
> > >
> > > Can you add a debug statement that displays frame->pc, frame->sp,
and frame->fp?
> >
> > I've already identified the cause.
> > pt_regs->pstate was set mistakenly from "sprsr_el1" in panic().
> > But I have a difficulty here to fix the problem as we have no direct way
> > to retrieve a value of the *current* PSTATE.
>
> Interesting. I don't know what you mean by "sprsr_el1" in panic(),
but
> I just got a report from my github "issues", where the
user injected a panic()
> call into a kernel module and got the same error as above because of the pstate
> value. I asked him to put this hack into arm64.c:
spspr_el1 is a register that holds a value of PSTATE when an exception
is trapped into EL1. Since panic() is called even in case of software
bugs, it is not useful anyway.
Currently I'm trying to save a "faked" current PSTATE into
pt_regs->pstate
and will add this fix in my next kdump patch series (v17).
OK thanks. Mystery solved. I think I'll still add the hack-around that prints
the warning message but allows it to continue if the sp, fp and pc appear correct.
It used to do that, but the new behavior was actually a regression that was
introduced as part of this patch in crash-7.1.5:
Fix for the "bt" command to properly pull the stack and frame pointer
registers from the NT_PRSTATUS notes of 32-bit tasks running in
user-mode on ARM64. Without the patch, the "bt" command utilizes
ptregs->sp and ptregs->regs[29] for 32-bit tasks instead of the
architecturally-mapped ptregs->regs[13] and ptregs->regs[11], which
yields unpredictable/invalid results, and possibly a segmentation
violation.
(drjones(a)redhat.com)
Thanks,
Dave
12:28 a.m.
On 24/05/2016:01:59:06 PM, Dave Anderson wrote:
----- Original Message -----
> Yet some issues, but ...
>
Hi Takahiro,
Here are my general comments on my testing of the v2 patch, followed
by a few comments in the patch itself.
First, the combination of the new memory map layout and KASLR is somewhat
confusing. I am testing your patch on a 4.6.0-0.rc7.git2.1.fc25 kernel
that has this configuration:
config-arm64:# CONFIG_RANDOMIZE_BASE is not set
So KASLR doesn't really enter into the picture. But when bringing
up the crash session, it shows the "kaslr kernel" WARNING:
# ./crash
crash 7.1.5++
Copyright (C) 2002-2016 Red Hat, Inc.
Copyright (C) 2004, 2005, 2006, 2010 IBM Corporation
Copyright (C) 1999-2006 Hewlett-Packard Co
Copyright (C) 2005, 2006, 2011, 2012 Fujitsu Limited
Copyright (C) 2006, 2007 VA Linux Systems Japan K.K.
Copyright (C) 2005, 2011 NEC Corporation
Copyright (C) 1999, 2002, 2007 Silicon Graphics, Inc.
Copyright (C) 1999, 2000, 2001, 2002 Mission Critical Linux, Inc.
This program is free software, covered by the GNU General Public License,
and you are welcome to change it and/or distribute copies of it under
certain conditions. Enter "help copying" to see the conditions.
This program has absolutely no warranty. Enter "help warranty" for details.
WARNING: kimage_voffset not identified for kaslr kernel
GNU gdb (GDB) 7.6
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "aarch64-unknown-linux-gnu"...
KERNEL: /usr/lib/debug/lib/modules/4.6.0-0.rc7.git2.1.fc25.aarch64/vmlinux
DUMPFILE: /dev/crash
CPUS: 8
DATE: Tue May 24 10:08:08 2016
UPTIME: 11 days, 18:32:41
LOAD AVERAGE: 0.17, 0.09, 0.12
TASKS: 197
NODENAME: apm-mustang-ev3-36.khw.lab.eng.bos.redhat.com
RELEASE: 4.6.0-0.rc7.git2.1.fc25.aarch64
VERSION: #1 SMP Thu May 12 13:28:43 UTC 2016
MACHINE: aarch64 (unknown Mhz)
MEMORY: 16 GB
PID: 7556
COMMAND: "crash"
TASK: fffffe00beb45400 [THREAD_INFO: fffffe00beb98000]
CPU: 7
STATE: TASK_RUNNING (ACTIVE)
crash>
Do not know whats missing, I am yet not able to reach "crash>" prompt. I
have
crash utility having this patch on top of "commit
8ceb1ac628bf6a0a7f0bbfff030ec93081bca4cd" [1]. I have kernel code v4.6+kexec-v15
[2].
In my .config:
# CONFIG_KASAN is not set
# CONFIG_RANDOMIZE_BASE is not set
This is what I get:
[root@dhcppc15 crash]# ./crash /lib/modules/4.6.0+/build/vmlinux
/var/crash/127.0.0.1-2016-05-26-09\:40\:05/vmcore
crash 7.1.5++
Copyright (C) 2002-2016 Red Hat, Inc.
Copyright (C) 2004, 2005, 2006, 2010 IBM Corporation
Copyright (C) 1999-2006 Hewlett-Packard Co
Copyright (C) 2005, 2006, 2011, 2012 Fujitsu Limited
Copyright (C) 2006, 2007 VA Linux Systems Japan K.K.
Copyright (C) 2005, 2011 NEC Corporation
Copyright (C) 1999, 2002, 2007 Silicon Graphics, Inc.
Copyright (C) 1999, 2000, 2001, 2002 Mission Critical Linux, Inc.
This program is free software, covered by the GNU General Public License,
and you are welcome to change it and/or distribute copies of it under
certain conditions. Enter "help copying" to see the conditions.
This program has absolutely no warranty. Enter "help warranty" for details.
GNU gdb (GDB) 7.6
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "aarch64-unknown-linux-gnu"...
crash: read error: kernel virtual address: fffffc0008b80fd8 type: "possible"
WARNING: cannot read cpu_possible_map
crash: read error: kernel virtual address: fffffc0008b80dd8 type: "present"
WARNING: cannot read cpu_present_map
crash: read error: kernel virtual address: fffffc0008b80bd8 type: "online"
WARNING: cannot read cpu_online_map
crash: read error: kernel virtual address: fffffc0008b811d8 type: "active"
WARNING: cannot read cpu_active_map
crash: read error: kernel virtual address: fffffc00091f6c78 type: "shadow_timekeeper
xtime_sec"
crash: read error: kernel virtual address: fffffc0008b9223c type:
"init_uts_ns"
crash: /lib/modules/4.6.0+/build/vmlinux and
/var/crash/127.0.0.1-2016-05-26-09:40:05/vmcore do not match!
Usage:
crash [OPTION]... NAMELIST MEMORY-IMAGE[@ADDRESS] (dumpfile form)
crash [OPTION]... [NAMELIST] (live system form)
Enter "crash -h" for details.
~Pratyush
[1] https://github.com/pratyushanand/crash/commits/master
[2] https://github.com/pratyushanand/linux/commits/upstream_arm64_devel_test
2:04 a.m.
Pratyush,
Just for debug purpose.
Please add the following line to *your* arch_crash_save_vmcoreinfo():
vmcoreinfo_append_str("NUMBER(kimage_voffset)=%llx\n",
kimage_voffset);
I will add this to my next kdump patch.
Thanks,
-Takahiro AKASHI
On Thu, May 26, 2016 at 10:58:24AM +0530, Pratyush Anand wrote:
On 24/05/2016:01:59:06 PM, Dave Anderson wrote:
>
>
> ----- Original Message -----
> > Yet some issues, but ...
> >
>
> Hi Takahiro,
>
> Here are my general comments on my testing of the v2 patch, followed
> by a few comments in the patch itself.
>
> First, the combination of the new memory map layout and KASLR is somewhat
> confusing. I am testing your patch on a 4.6.0-0.rc7.git2.1.fc25 kernel
> that has this configuration:
>
> config-arm64:# CONFIG_RANDOMIZE_BASE is not set
>
> So KASLR doesn't really enter into the picture. But when bringing
> up the crash session, it shows the "kaslr kernel" WARNING:
>
> # ./crash
>
> crash 7.1.5++
> Copyright (C) 2002-2016 Red Hat, Inc.
> Copyright (C) 2004, 2005, 2006, 2010 IBM Corporation
> Copyright (C) 1999-2006 Hewlett-Packard Co
> Copyright (C) 2005, 2006, 2011, 2012 Fujitsu Limited
> Copyright (C) 2006, 2007 VA Linux Systems Japan K.K.
> Copyright (C) 2005, 2011 NEC Corporation
> Copyright (C) 1999, 2002, 2007 Silicon Graphics, Inc.
> Copyright (C) 1999, 2000, 2001, 2002 Mission Critical Linux, Inc.
> This program is free software, covered by the GNU General Public License,
> and you are welcome to change it and/or distribute copies of it under
> certain conditions. Enter "help copying" to see the conditions.
> This program has absolutely no warranty. Enter "help warranty" for
details.
>
> WARNING: kimage_voffset not identified for kaslr kernel
> GNU gdb (GDB) 7.6
> Copyright (C) 2013 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later
<http://gnu.org/licenses/gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law. Type "show
copying"
> and "show warranty" for details.
> This GDB was configured as "aarch64-unknown-linux-gnu"...
>
> KERNEL: /usr/lib/debug/lib/modules/4.6.0-0.rc7.git2.1.fc25.aarch64/vmlinux
> DUMPFILE: /dev/crash
> CPUS: 8
> DATE: Tue May 24 10:08:08 2016
> UPTIME: 11 days, 18:32:41
> LOAD AVERAGE: 0.17, 0.09, 0.12
> TASKS: 197
> NODENAME: apm-mustang-ev3-36.khw.lab.eng.bos.redhat.com
> RELEASE: 4.6.0-0.rc7.git2.1.fc25.aarch64
> VERSION: #1 SMP Thu May 12 13:28:43 UTC 2016
> MACHINE: aarch64 (unknown Mhz)
> MEMORY: 16 GB
> PID: 7556
> COMMAND: "crash"
> TASK: fffffe00beb45400 [THREAD_INFO: fffffe00beb98000]
> CPU: 7
> STATE: TASK_RUNNING (ACTIVE)
>
> crash>
Do not know whats missing, I am yet not able to reach "crash>" prompt. I
have
crash utility having this patch on top of "commit
8ceb1ac628bf6a0a7f0bbfff030ec93081bca4cd" [1]. I have kernel code v4.6+kexec-v15
[2].
In my .config:
# CONFIG_KASAN is not set
# CONFIG_RANDOMIZE_BASE is not set
This is what I get:
[root@dhcppc15 crash]# ./crash /lib/modules/4.6.0+/build/vmlinux
/var/crash/127.0.0.1-2016-05-26-09\:40\:05/vmcore
crash 7.1.5++
Copyright (C) 2002-2016 Red Hat, Inc.
Copyright (C) 2004, 2005, 2006, 2010 IBM Corporation
Copyright (C) 1999-2006 Hewlett-Packard Co
Copyright (C) 2005, 2006, 2011, 2012 Fujitsu Limited
Copyright (C) 2006, 2007 VA Linux Systems Japan K.K.
Copyright (C) 2005, 2011 NEC Corporation
Copyright (C) 1999, 2002, 2007 Silicon Graphics, Inc.
Copyright (C) 1999, 2000, 2001, 2002 Mission Critical Linux, Inc.
This program is free software, covered by the GNU General Public License,
and you are welcome to change it and/or distribute copies of it under
certain conditions. Enter "help copying" to see the conditions.
This program has absolutely no warranty. Enter "help warranty" for details.
GNU gdb (GDB) 7.6
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "aarch64-unknown-linux-gnu"...
crash: read error: kernel virtual address: fffffc0008b80fd8 type: "possible"
WARNING: cannot read cpu_possible_map
crash: read error: kernel virtual address: fffffc0008b80dd8 type: "present"
WARNING: cannot read cpu_present_map
crash: read error: kernel virtual address: fffffc0008b80bd8 type: "online"
WARNING: cannot read cpu_online_map
crash: read error: kernel virtual address: fffffc0008b811d8 type: "active"
WARNING: cannot read cpu_active_map
crash: read error: kernel virtual address: fffffc00091f6c78 type:
"shadow_timekeeper xtime_sec"
crash: read error: kernel virtual address: fffffc0008b9223c type:
"init_uts_ns"
crash: /lib/modules/4.6.0+/build/vmlinux and
/var/crash/127.0.0.1-2016-05-26-09:40:05/vmcore do not match!
Usage:
crash [OPTION]... NAMELIST MEMORY-IMAGE[@ADDRESS] (dumpfile form)
crash [OPTION]... [NAMELIST] (live system form)
Enter "crash -h" for details.
~Pratyush
[1] https://github.com/pratyushanand/crash/commits/master
[2] https://github.com/pratyushanand/linux/commits/upstream_arm64_devel_test
--
Thanks,
-Takahiro AKASHI
2:57 a.m.
On 26/05/2016:04:04:08 PM, AKASHI Takahiro wrote:
Pratyush,
Just for debug purpose.
Please add the following line to *your* arch_crash_save_vmcoreinfo():
> vmcoreinfo_append_str("NUMBER(kimage_voffset)=%llx\n", kimage_voffset);
Thanks for the pointer.
I did had VMCOREINFO_NUMBER(kimage_voffset) in arch_crash_save_vmcoreinfo().
https://github.com/pratyushanand/linux/commit/7011e478aae3e568cc8dca15b6c...
But, I noticed that in crash code you have "ms->kimage_voffset = htol(string,
QUIET, NULL);". So, the change you have suggested will work.
However, I think its preferable to use VMCOREINFO_NUMBER() macro instead.
makedumpfile is able to calculate kimage_voffset correctly with that without any
issue.
I will suggest to take following modification in crash code:
diff --git a/arm64.c b/arm64.c
index 6b97093..9397d6d 100644
--- a/arm64.c
+++ b/arm64.c
@@ -122,7 +122,7 @@ arm64_init(int when)
ms = machdep->machspec;
if (!ms->kimage_voffset &&
(string = pc->read_vmcoreinfo("NUMBER(kimage_voffset)")))
{
- ms->kimage_voffset = htol(string, QUIET, NULL);
+ ms->kimage_voffset = dtol(string, QUIET, NULL);
free(string);
}
diff --git a/tools.c b/tools.c
index 384bebd..1383e43 100644
--- a/tools.c
+++ b/tools.c
@@ -877,7 +877,7 @@ dtol(char *s, int flags, int *errptr)
s++;
for (j = 0; s[j] != '\0'; j++)
- if ((s[j] < '0' || s[j] > '9'))
+ if ( (s[j] != '-') && ((s[j] < '0' || s[j]
> '9')))
break ;
if (s[j] != '\0') {
~Pratyush
I will add this to my next kdump patch.
Thanks,
-Takahiro AKASHI
On Thu, May 26, 2016 at 10:58:24AM +0530, Pratyush Anand wrote:
> On 24/05/2016:01:59:06 PM, Dave Anderson wrote:
> >
> >
> > ----- Original Message -----
> > > Yet some issues, but ...
> > >
> >
> > Hi Takahiro,
> >
> > Here are my general comments on my testing of the v2 patch, followed
> > by a few comments in the patch itself.
> >
> > First, the combination of the new memory map layout and KASLR is somewhat
> > confusing. I am testing your patch on a 4.6.0-0.rc7.git2.1.fc25 kernel
> > that has this configuration:
> >
> > config-arm64:# CONFIG_RANDOMIZE_BASE is not set
> >
> > So KASLR doesn't really enter into the picture. But when bringing
> > up the crash session, it shows the "kaslr kernel" WARNING:
> >
> > # ./crash
> >
> > crash 7.1.5++
> > Copyright (C) 2002-2016 Red Hat, Inc.
> > Copyright (C) 2004, 2005, 2006, 2010 IBM Corporation
> > Copyright (C) 1999-2006 Hewlett-Packard Co
> > Copyright (C) 2005, 2006, 2011, 2012 Fujitsu Limited
> > Copyright (C) 2006, 2007 VA Linux Systems Japan K.K.
> > Copyright (C) 2005, 2011 NEC Corporation
> > Copyright (C) 1999, 2002, 2007 Silicon Graphics, Inc.
> > Copyright (C) 1999, 2000, 2001, 2002 Mission Critical Linux, Inc.
> > This program is free software, covered by the GNU General Public License,
> > and you are welcome to change it and/or distribute copies of it under
> > certain conditions. Enter "help copying" to see the conditions.
> > This program has absolutely no warranty. Enter "help warranty" for
details.
> >
> > WARNING: kimage_voffset not identified for kaslr kernel
> > GNU gdb (GDB) 7.6
> > Copyright (C) 2013 Free Software Foundation, Inc.
> > License GPLv3+: GNU GPL version 3 or later
<http://gnu.org/licenses/gpl.html>
> > This is free software: you are free to change and redistribute it.
> > There is NO WARRANTY, to the extent permitted by law. Type "show
copying"
> > and "show warranty" for details.
> > This GDB was configured as "aarch64-unknown-linux-gnu"...
> >
> > KERNEL:
/usr/lib/debug/lib/modules/4.6.0-0.rc7.git2.1.fc25.aarch64/vmlinux
> > DUMPFILE: /dev/crash
> > CPUS: 8
> > DATE: Tue May 24 10:08:08 2016
> > UPTIME: 11 days, 18:32:41
> > LOAD AVERAGE: 0.17, 0.09, 0.12
> > TASKS: 197
> > NODENAME: apm-mustang-ev3-36.khw.lab.eng.bos.redhat.com
> > RELEASE: 4.6.0-0.rc7.git2.1.fc25.aarch64
> > VERSION: #1 SMP Thu May 12 13:28:43 UTC 2016
> > MACHINE: aarch64 (unknown Mhz)
> > MEMORY: 16 GB
> > PID: 7556
> > COMMAND: "crash"
> > TASK: fffffe00beb45400 [THREAD_INFO: fffffe00beb98000]
> > CPU: 7
> > STATE: TASK_RUNNING (ACTIVE)
> >
> > crash>
>
> Do not know whats missing, I am yet not able to reach "crash>" prompt.
I have
> crash utility having this patch on top of "commit
> 8ceb1ac628bf6a0a7f0bbfff030ec93081bca4cd" [1]. I have kernel code
v4.6+kexec-v15 [2].
>
> In my .config:
> # CONFIG_KASAN is not set
> # CONFIG_RANDOMIZE_BASE is not set
>
> This is what I get:
>
> [root@dhcppc15 crash]# ./crash /lib/modules/4.6.0+/build/vmlinux
/var/crash/127.0.0.1-2016-05-26-09\:40\:05/vmcore
>
> crash 7.1.5++
> Copyright (C) 2002-2016 Red Hat, Inc.
> Copyright (C) 2004, 2005, 2006, 2010 IBM Corporation
> Copyright (C) 1999-2006 Hewlett-Packard Co
> Copyright (C) 2005, 2006, 2011, 2012 Fujitsu Limited
> Copyright (C) 2006, 2007 VA Linux Systems Japan K.K.
> Copyright (C) 2005, 2011 NEC Corporation
> Copyright (C) 1999, 2002, 2007 Silicon Graphics, Inc.
> Copyright (C) 1999, 2000, 2001, 2002 Mission Critical Linux, Inc.
> This program is free software, covered by the GNU General Public License,
> and you are welcome to change it and/or distribute copies of it under
> certain conditions. Enter "help copying" to see the conditions.
> This program has absolutely no warranty. Enter "help warranty" for
details.
>
> GNU gdb (GDB) 7.6
> Copyright (C) 2013 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law. Type "show
copying"
> and "show warranty" for details.
> This GDB was configured as "aarch64-unknown-linux-gnu"...
>
> crash: read error: kernel virtual address: fffffc0008b80fd8 type:
"possible"
> WARNING: cannot read cpu_possible_map
> crash: read error: kernel virtual address: fffffc0008b80dd8 type:
"present"
> WARNING: cannot read cpu_present_map
> crash: read error: kernel virtual address: fffffc0008b80bd8 type:
"online"
> WARNING: cannot read cpu_online_map
> crash: read error: kernel virtual address: fffffc0008b811d8 type:
"active"
> WARNING: cannot read cpu_active_map
> crash: read error: kernel virtual address: fffffc00091f6c78 type:
"shadow_timekeeper xtime_sec"
> crash: read error: kernel virtual address: fffffc0008b9223c type:
"init_uts_ns"
> crash: /lib/modules/4.6.0+/build/vmlinux and
/var/crash/127.0.0.1-2016-05-26-09:40:05/vmcore do not match!
>
> Usage:
>
> crash [OPTION]... NAMELIST MEMORY-IMAGE[@ADDRESS] (dumpfile form)
> crash [OPTION]... [NAMELIST] (live system form)
>
> Enter "crash -h" for details.
>
>
> ~Pratyush
>
> [1] https://github.com/pratyushanand/crash/commits/master
> [2] https://github.com/pratyushanand/linux/commits/upstream_arm64_devel_test
>
--
Thanks,
-Takahiro AKASHI
10:18 p.m.
On Thu, May 26, 2016 at 01:27:08PM +0530, Pratyush Anand wrote:
On 26/05/2016:04:04:08 PM, AKASHI Takahiro wrote:
> Pratyush,
>
> Just for debug purpose.
> Please add the following line to *your* arch_crash_save_vmcoreinfo():
> > vmcoreinfo_append_str("NUMBER(kimage_voffset)=%llx\n",
kimage_voffset);
Thanks for the pointer.
I did had VMCOREINFO_NUMBER(kimage_voffset) in arch_crash_save_vmcoreinfo().
https://github.com/pratyushanand/linux/commit/7011e478aae3e568cc8dca15b6c...
But, I noticed that in crash code you have "ms->kimage_voffset = htol(string,
QUIET, NULL);". So, the change you have suggested will work.
I know that. It is intentional.
However, I think its preferable to use VMCOREINFO_NUMBER() macro
instead.
makedumpfile is able to calculate kimage_voffset correctly with that without any
issue.
I think that VMCOREINFO_NUMBER() is, at least originally, intended
to be used for a small *unsigned* integer.
I also know that PHYS_OFFSET can now be nagative in v4.6 on arm64.
Yet I'm thinking of adding "0x" as a prefix to VMCOREINOF string.
-Takahiro AKASHI
I will suggest to take following modification in crash code:
diff --git a/arm64.c b/arm64.c
index 6b97093..9397d6d 100644
--- a/arm64.c
+++ b/arm64.c
@@ -122,7 +122,7 @@ arm64_init(int when)
ms = machdep->machspec;
if (!ms->kimage_voffset &&
(string =
pc->read_vmcoreinfo("NUMBER(kimage_voffset)"))) {
- ms->kimage_voffset = htol(string, QUIET, NULL);
+ ms->kimage_voffset = dtol(string, QUIET, NULL);
free(string);
}
diff --git a/tools.c b/tools.c
index 384bebd..1383e43 100644
--- a/tools.c
+++ b/tools.c
@@ -877,7 +877,7 @@ dtol(char *s, int flags, int *errptr)
s++;
for (j = 0; s[j] != '\0'; j++)
- if ((s[j] < '0' || s[j] > '9'))
+ if ( (s[j] != '-') && ((s[j] < '0' || s[j]
> '9')))
break ;
if (s[j] != '\0') {
~Pratyush
>
> I will add this to my next kdump patch.
>
> Thanks,
> -Takahiro AKASHI
>
>
> On Thu, May 26, 2016 at 10:58:24AM +0530, Pratyush Anand wrote:
> > On 24/05/2016:01:59:06 PM, Dave Anderson wrote:
> > >
> > >
> > > ----- Original Message -----
> > > > Yet some issues, but ...
> > > >
> > >
> > > Hi Takahiro,
> > >
> > > Here are my general comments on my testing of the v2 patch, followed
> > > by a few comments in the patch itself.
> > >
> > > First, the combination of the new memory map layout and KASLR is somewhat
> > > confusing. I am testing your patch on a 4.6.0-0.rc7.git2.1.fc25 kernel
> > > that has this configuration:
> > >
> > > config-arm64:# CONFIG_RANDOMIZE_BASE is not set
> > >
> > > So KASLR doesn't really enter into the picture. But when bringing
> > > up the crash session, it shows the "kaslr kernel" WARNING:
> > >
> > > # ./crash
> > >
> > > crash 7.1.5++
> > > Copyright (C) 2002-2016 Red Hat, Inc.
> > > Copyright (C) 2004, 2005, 2006, 2010 IBM Corporation
> > > Copyright (C) 1999-2006 Hewlett-Packard Co
> > > Copyright (C) 2005, 2006, 2011, 2012 Fujitsu Limited
> > > Copyright (C) 2006, 2007 VA Linux Systems Japan K.K.
> > > Copyright (C) 2005, 2011 NEC Corporation
> > > Copyright (C) 1999, 2002, 2007 Silicon Graphics, Inc.
> > > Copyright (C) 1999, 2000, 2001, 2002 Mission Critical Linux, Inc.
> > > This program is free software, covered by the GNU General Public
License,
> > > and you are welcome to change it and/or distribute copies of it under
> > > certain conditions. Enter "help copying" to see the
conditions.
> > > This program has absolutely no warranty. Enter "help
warranty" for details.
> > >
> > > WARNING: kimage_voffset not identified for kaslr kernel
> > > GNU gdb (GDB) 7.6
> > > Copyright (C) 2013 Free Software Foundation, Inc.
> > > License GPLv3+: GNU GPL version 3 or later
<http://gnu.org/licenses/gpl.html>
> > > This is free software: you are free to change and redistribute it.
> > > There is NO WARRANTY, to the extent permitted by law. Type "show
copying"
> > > and "show warranty" for details.
> > > This GDB was configured as "aarch64-unknown-linux-gnu"...
> > >
> > > KERNEL:
/usr/lib/debug/lib/modules/4.6.0-0.rc7.git2.1.fc25.aarch64/vmlinux
> > > DUMPFILE: /dev/crash
> > > CPUS: 8
> > > DATE: Tue May 24 10:08:08 2016
> > > UPTIME: 11 days, 18:32:41
> > > LOAD AVERAGE: 0.17, 0.09, 0.12
> > > TASKS: 197
> > > NODENAME: apm-mustang-ev3-36.khw.lab.eng.bos.redhat.com
> > > RELEASE: 4.6.0-0.rc7.git2.1.fc25.aarch64
> > > VERSION: #1 SMP Thu May 12 13:28:43 UTC 2016
> > > MACHINE: aarch64 (unknown Mhz)
> > > MEMORY: 16 GB
> > > PID: 7556
> > > COMMAND: "crash"
> > > TASK: fffffe00beb45400 [THREAD_INFO: fffffe00beb98000]
> > > CPU: 7
> > > STATE: TASK_RUNNING (ACTIVE)
> > >
> > > crash>
> >
> > Do not know whats missing, I am yet not able to reach "crash>"
prompt. I have
> > crash utility having this patch on top of "commit
> > 8ceb1ac628bf6a0a7f0bbfff030ec93081bca4cd" [1]. I have kernel code
v4.6+kexec-v15 [2].
> >
> > In my .config:
> > # CONFIG_KASAN is not set
> > # CONFIG_RANDOMIZE_BASE is not set
> >
> > This is what I get:
> >
> > [root@dhcppc15 crash]# ./crash /lib/modules/4.6.0+/build/vmlinux
/var/crash/127.0.0.1-2016-05-26-09\:40\:05/vmcore
> >
> > crash 7.1.5++
> > Copyright (C) 2002-2016 Red Hat, Inc.
> > Copyright (C) 2004, 2005, 2006, 2010 IBM Corporation
> > Copyright (C) 1999-2006 Hewlett-Packard Co
> > Copyright (C) 2005, 2006, 2011, 2012 Fujitsu Limited
> > Copyright (C) 2006, 2007 VA Linux Systems Japan K.K.
> > Copyright (C) 2005, 2011 NEC Corporation
> > Copyright (C) 1999, 2002, 2007 Silicon Graphics, Inc.
> > Copyright (C) 1999, 2000, 2001, 2002 Mission Critical Linux, Inc.
> > This program is free software, covered by the GNU General Public License,
> > and you are welcome to change it and/or distribute copies of it under
> > certain conditions. Enter "help copying" to see the conditions.
> > This program has absolutely no warranty. Enter "help warranty" for
details.
> >
> > GNU gdb (GDB) 7.6
> > Copyright (C) 2013 Free Software Foundation, Inc.
> > License GPLv3+: GNU GPL version 3 or later
<http://gnu.org/licenses/gpl.html>
> > This is free software: you are free to change and redistribute it.
> > There is NO WARRANTY, to the extent permitted by law. Type "show
copying"
> > and "show warranty" for details.
> > This GDB was configured as "aarch64-unknown-linux-gnu"...
> >
> > crash: read error: kernel virtual address: fffffc0008b80fd8 type:
"possible"
> > WARNING: cannot read cpu_possible_map
> > crash: read error: kernel virtual address: fffffc0008b80dd8 type:
"present"
> > WARNING: cannot read cpu_present_map
> > crash: read error: kernel virtual address: fffffc0008b80bd8 type:
"online"
> > WARNING: cannot read cpu_online_map
> > crash: read error: kernel virtual address: fffffc0008b811d8 type:
"active"
> > WARNING: cannot read cpu_active_map
> > crash: read error: kernel virtual address: fffffc00091f6c78 type:
"shadow_timekeeper xtime_sec"
> > crash: read error: kernel virtual address: fffffc0008b9223c type:
"init_uts_ns"
> > crash: /lib/modules/4.6.0+/build/vmlinux and
/var/crash/127.0.0.1-2016-05-26-09:40:05/vmcore do not match!
> >
> > Usage:
> >
> > crash [OPTION]... NAMELIST MEMORY-IMAGE[@ADDRESS] (dumpfile form)
> > crash [OPTION]... [NAMELIST] (live system form)
> >
> > Enter "crash -h" for details.
> >
> >
> > ~Pratyush
> >
> > [1] https://github.com/pratyushanand/crash/commits/master
> > [2] https://github.com/pratyushanand/linux/commits/upstream_arm64_devel_test
> >
>
> --
> Thanks,
> -Takahiro AKASHI
--
Thanks,
-Takahiro AKASHI
11:16 p.m.
On 27/05/2016:12:18:56 PM, AKASHI Takahiro wrote:
On Thu, May 26, 2016 at 01:27:08PM +0530, Pratyush Anand wrote:
> On 26/05/2016:04:04:08 PM, AKASHI Takahiro wrote:
> > Pratyush,
> >
> > Just for debug purpose.
> > Please add the following line to *your* arch_crash_save_vmcoreinfo():
> > > vmcoreinfo_append_str("NUMBER(kimage_voffset)=%llx\n",
kimage_voffset);
>
> Thanks for the pointer.
>
> I did had VMCOREINFO_NUMBER(kimage_voffset) in arch_crash_save_vmcoreinfo().
>
>
https://github.com/pratyushanand/linux/commit/7011e478aae3e568cc8dca15b6c...
>
> But, I noticed that in crash code you have "ms->kimage_voffset =
htol(string,
> QUIET, NULL);". So, the change you have suggested will work.
I know that. It is intentional.
> However, I think its preferable to use VMCOREINFO_NUMBER() macro instead.
> makedumpfile is able to calculate kimage_voffset correctly with that without any
> issue.
I think that VMCOREINFO_NUMBER() is, at least originally, intended
to be used for a small *unsigned* integer.
Not sure..When I see all the places where it has been used, it seems it can
accommodate *long* variable.
See, read_vmcoreinfo_long() of makedumpfile [1] , which is being used to read
"NUMBER" string. This function uses strtol(). So I think, we must have similar
implementation if we intend to use VMCOREINFO_NUMBER().
[1] https://sourceforge.net/p/makedumpfile/code/ci/master/tree/makedumpfile.c...
I also know that PHYS_OFFSET can now be nagative in v4.6 on arm64.
Yet I'm thinking of adding "0x" as a prefix to VMCOREINOF string.
I think, we should not change existing VMCOREINFO_xxxx() macros of kernel,
because it will break the applications which rely on it's current structure.
ATM, I also do not see any urgency of defining a new macro which can have
implementation like vmcoreinfo_append_str("NUMBER(X)=%#llx\n", X), because
exiting macros is able to take care of the needs.
-Takahiro AKASHI
> I will suggest to take following modification in crash code:
>
> diff --git a/arm64.c b/arm64.c
> index 6b97093..9397d6d 100644
> --- a/arm64.c
> +++ b/arm64.c
> @@ -122,7 +122,7 @@ arm64_init(int when)
> ms = machdep->machspec;
> if (!ms->kimage_voffset &&
> (string =
pc->read_vmcoreinfo("NUMBER(kimage_voffset)"))) {
> - ms->kimage_voffset = htol(string, QUIET, NULL);
> + ms->kimage_voffset = dtol(string, QUIET, NULL);
> free(string);
> }
>
> diff --git a/tools.c b/tools.c
> index 384bebd..1383e43 100644
> --- a/tools.c
> +++ b/tools.c
> @@ -877,7 +877,7 @@ dtol(char *s, int flags, int *errptr)
> s++;
>
> for (j = 0; s[j] != '\0'; j++)
> - if ((s[j] < '0' || s[j] > '9'))
> + if ( (s[j] != '-') && ((s[j] < '0' ||
s[j] > '9')))
> break ;
>
> if (s[j] != '\0') {
>
~Pratyush
1:21 a.m.
On Fri, May 27, 2016 at 09:46:10AM +0530, Pratyush Anand wrote:
On 27/05/2016:12:18:56 PM, AKASHI Takahiro wrote:
> On Thu, May 26, 2016 at 01:27:08PM +0530, Pratyush Anand wrote:
> > On 26/05/2016:04:04:08 PM, AKASHI Takahiro wrote:
> > > Pratyush,
> > >
> > > Just for debug purpose.
> > > Please add the following line to *your* arch_crash_save_vmcoreinfo():
> > > > vmcoreinfo_append_str("NUMBER(kimage_voffset)=%llx\n",
kimage_voffset);
> >
> > Thanks for the pointer.
> >
> > I did had VMCOREINFO_NUMBER(kimage_voffset) in arch_crash_save_vmcoreinfo().
> >
> >
https://github.com/pratyushanand/linux/commit/7011e478aae3e568cc8dca15b6c...
> >
> > But, I noticed that in crash code you have "ms->kimage_voffset =
htol(string,
> > QUIET, NULL);". So, the change you have suggested will work.
>
> I know that. It is intentional.
>
> > However, I think its preferable to use VMCOREINFO_NUMBER() macro instead.
> > makedumpfile is able to calculate kimage_voffset correctly with that without
any
> > issue.
>
> I think that VMCOREINFO_NUMBER() is, at least originally, intended
> to be used for a small *unsigned* integer.
Not sure..When I see all the places where it has been used, it seems it can
accommodate *long* variable.
I don't know makedumpfile side, but as far as I look at the kernel code
in crash_save_vmcoreinfo_init(), all the values seem to be small positive
numbers.
See, read_vmcoreinfo_long() of makedumpfile [1] , which is being used
to read
"NUMBER" string. This function uses strtol(). So I think, we must have
similar
implementation if we intend to use VMCOREINFO_NUMBER().
[1] https://sourceforge.net/p/makedumpfile/code/ci/master/tree/makedumpfile.c...
>
> I also know that PHYS_OFFSET can now be nagative in v4.6 on arm64.
> Yet I'm thinking of adding "0x" as a prefix to VMCOREINOF string.
I think, we should not change existing VMCOREINFO_xxxx() macros of kernel,
because it will break the applications which rely on it's current structure.
I'm not saying that we change VMCOREINFO_NUMBER() macro.
ATM, I also do not see any urgency of defining a new macro which can
have
implementation like vmcoreinfo_append_str("NUMBER(X)=%#llx\n", X), because
exiting macros is able to take care of the needs.
>
> -Takahiro AKASHI
>
> > I will suggest to take following modification in crash code:
> >
> > diff --git a/arm64.c b/arm64.c
> > index 6b97093..9397d6d 100644
> > --- a/arm64.c
> > +++ b/arm64.c
> > @@ -122,7 +122,7 @@ arm64_init(int when)
> > ms = machdep->machspec;
> > if (!ms->kimage_voffset &&
> > (string =
pc->read_vmcoreinfo("NUMBER(kimage_voffset)"))) {
> > - ms->kimage_voffset = htol(string, QUIET, NULL);
> > + ms->kimage_voffset = dtol(string, QUIET, NULL);
> > free(string);
> > }
> >
> > diff --git a/tools.c b/tools.c
> > index 384bebd..1383e43 100644
> > --- a/tools.c
> > +++ b/tools.c
> > @@ -877,7 +877,7 @@ dtol(char *s, int flags, int *errptr)
> > s++;
> >
> > for (j = 0; s[j] != '\0'; j++)
> > - if ((s[j] < '0' || s[j] > '9'))
> > + if ( (s[j] != '-') && ((s[j] < '0'
|| s[j] > '9')))
> > break ;
> >
> > if (s[j] != '\0') {
> >
~Pratyush
--
Thanks,
-Takahiro AKASHI
3105
days inactive
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devel@lists.crash-utility.osci.io
19 comments
4 participants
participants (4)
-
AKASHI Takahiro -
Atsushi Kumagai -
Dave Anderson -
Pratyush Anand