4:10 a.m.
In my next version of kdump patch, the following VMCOREINFO will be
added:
NUMBER(VA_BITS)
NUMBER(kimage_voffset)
NUMBER(PHYS_OFFSET)
KERNELOFFSET
I think that those will also satisfy mkdumpfile requirements.
-> Pratyush
Thanks,
-Takahiro AKASHI
changes in v5:
* Calcs PHYS_OFFSET by reading VMCOREINFO, "NUMBER(PHYS_OFFSET)"
"memstart_addr"-based routine was also moved into arm64_calc_phys_base().
changes in v4:
* Fixed VA_BITS calculation for v4.5 or earlier
* Added 4-level address translation with 4KB page size
* Removed "fix a renaming of a member of struct page, _count to _refcount"
Chnages in v3:
* Refined KASLR handling
hopefully the tool works even on a live system if CONFIG_RANDOMIZE_RAM is
not configured
* Fixed a renaming of a member of struct page
* Removed a commit message regarding an issue of backtracing a panic'ed task
because this is not a bug in this tool, but my kdump patch's.
* Reported "kmem <vmalloc addr>" issue in a commit message
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 a6dd9d73120dcc3f2d68dbe9a8f2d16a128c4002 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 v5] 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.
* On a live system, crash with this patch won't work, especially
with CONFIG_RANDOMIZE_BASE configured, because we currently have no way
to know kimage_voffset.
* 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.)
Signed-off-by: AKASHI Takahiro <takahiro.akashi(a)linaro.org>
---
arm64.c | 232 ++++++++++++++++++++++++++++++++++++++++++++++++--------------
defs.h | 26 ++++---
main.c | 7 +-
symbols.c | 12 ++--
4 files changed, 211 insertions(+), 66 deletions(-)
diff --git a/arm64.c b/arm64.c
index 86ec348..37524c8 100644
--- a/arm64.c
+++ b/arm64.c
@@ -73,6 +73,23 @@ 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) {
+ if (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);
+ } else {
+ return machdep->machspec->phys_offset
+ + (addr - machdep->machspec->page_offset);
+ }
+}
/*
* Do all necessary machine-specific setup here. This is called several times
@@ -82,6 +99,7 @@ void
arm64_init(int when)
{
ulong value;
+ char *string;
struct machine_specific *ms;
#if defined(__x86_64__)
@@ -103,9 +121,32 @@ 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;
+
+ /*
+ * Even if CONFIG_RANDOMIZE_BASE is not configured,
+ * derive_kaslr_offset() should work and set
+ * kt->relocate to 0
+ */
+ if (!kt->relocate && !(kt->flags2 & (RELOC_AUTO|KASLR)))
+ kt->flags2 |= (RELOC_AUTO|KASLR);
+ }
+
break;
case PRE_GDB:
+ if (kernel_symbol_exists("kimage_voffset"))
+ machdep->flags |= NEW_VMEMMAP;
+
if (!machdep->pagesize) {
/*
* Kerneldoc Documentation/arm64/booting.txt describes
@@ -161,16 +202,34 @@ 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;
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)
{
@@ -241,8 +300,6 @@ 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;
@@ -271,6 +328,10 @@ 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:
@@ -420,6 +481,8 @@ 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);
@@ -524,6 +587,11 @@ 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);
@@ -566,6 +634,42 @@ 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.
@@ -577,11 +681,10 @@ 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])
@@ -603,39 +706,23 @@ 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",
@@ -720,7 +807,32 @@ arm64_calc_phys_offset(void)
static int
arm64_kdump_phys_base(ulong *phys_offset)
{
- return arm_kdump_phys_base(phys_offset);
+ char *string;
+ struct syment *sp;
+ physaddr_t paddr;
+
+ if (string = pc->read_vmcoreinfo("NUMBER(PHYS_OFFSET)")) {
+ *phys_offset = htol(string, QUIET, NULL);
+ free(string);
+ return TRUE;
+ }
+
+ if (machdep->flags & NEW_VMEMMAP) {
+ if (!(sp = kernel_symbol_search("memstart_addr")))
+ return FALSE;
+
+ /* sanity check */
+ if (!machdep->machspec->kimage_voffset)
+ return FALSE;
+
+ paddr = sp->value - machdep->machspec->kimage_voffset;
+ if (READMEM(-1, phys_offset, sizeof(*phys_offset),
+ sp->value, paddr) > 0)
+ return TRUE;
+ else
+ return FALSE;
+ } else
+ return arm_kdump_phys_base(phys_offset);
}
static void
@@ -2509,6 +2621,11 @@ 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)) ||
@@ -2539,7 +2656,10 @@ arm64_calc_VA_BITS(void)
for (bitval = highest_bit_long(value); bitval; bitval--) {
if ((value & (1UL << bitval)) == 0) {
- machdep->machspec->VA_BITS = bitval + 2;
+ if (machdep->flags & NEW_VMEMMAP)
+ machdep->machspec->VA_BITS = bitval + 1;
+ else
+ machdep->machspec->VA_BITS = bitval + 2;
break;
}
}
@@ -2593,10 +2713,22 @@ 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 8eb601b..d6f719c 100644
--- a/defs.h
+++ b/defs.h
@@ -2846,8 +2846,8 @@ 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)
@@ -2962,19 +2962,24 @@ typedef signed int s32;
#define VM_L3_4K (0x10)
#define KDUMP_ENABLED (0x20)
#define IRQ_STACKS (0x40)
-#define VM_L4_4K (0x80)
+#define NEW_VMEMMAP (0x80)
+#define VM_L4_4K (0x100)
/*
* 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.
@@ -3055,6 +3060,10 @@ struct machine_specific {
ulong *irq_stacks;
ulong __irqentry_text_start;
ulong __irqentry_text_end;
+ /* only needed for v4.6 or later kernel */
+ ulong kimage_voffset;
+ ulong kimage_text;
+ ulong kimage_end;
};
struct arm64_stackframe {
@@ -5412,6 +5421,7 @@ 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 05787f0..4065e9a 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..b0a6461 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;
@@ -833,7 +835,7 @@ store_sysmap_symbols(void)
}
/*
- * Handle x86 kernels configured such that the vmlinux symbols
+ * Handle x86/arm64 kernels configured such that the vmlinux symbols
* are not as loaded into the kernel (not unity-mapped).
*/
static ulong
@@ -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
5:03 a.m.
Hi Takahiro,
On 13/06/2016:05:10:08 PM, AKASHI Takahiro wrote:
In my next version of kdump patch, the following VMCOREINFO will be
added:
NUMBER(VA_BITS)
NUMBER(kimage_voffset)
NUMBER(PHYS_OFFSET)
KERNELOFFSET
I think that those will also satisfy mkdumpfile requirements.
-> Pratyush
Thanks, Those would be useful for Makedumpfile. However, I am still not able to
see a way to distinguish between kernel text area and others.
makedumpfile needs a way to identify between VAs "which could be translated using
__pa()" and others, "which needs to be translated using page tables".
Currently,
it uses __pa() if a VA is not within either vmalloc, or vmemmap or module area.
But as, you had suggested, it seems a better approach to translate using __pa()
when VA >= PAGE_OFFSET || (VA >= SYMBOL(_text) && vaddr <= SYMBOL(_end)).
I am
still not getting, how can I get _end from the passed information.
~Pratyush
Thanks,
-Takahiro AKASHI
changes in v5:
* Calcs PHYS_OFFSET by reading VMCOREINFO, "NUMBER(PHYS_OFFSET)"
"memstart_addr"-based routine was also moved into arm64_calc_phys_base().
changes in v4:
* Fixed VA_BITS calculation for v4.5 or earlier
* Added 4-level address translation with 4KB page size
* Removed "fix a renaming of a member of struct page, _count to _refcount"
Chnages in v3:
* Refined KASLR handling
hopefully the tool works even on a live system if CONFIG_RANDOMIZE_RAM is
not configured
* Fixed a renaming of a member of struct page
* Removed a commit message regarding an issue of backtracing a panic'ed task
because this is not a bug in this tool, but my kdump patch's.
* Reported "kmem <vmalloc addr>" issue in a commit message
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 a6dd9d73120dcc3f2d68dbe9a8f2d16a128c4002 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 v5] 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.
* On a live system, crash with this patch won't work, especially
with CONFIG_RANDOMIZE_BASE configured, because we currently have no way
to know kimage_voffset.
* 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.)
Signed-off-by: AKASHI Takahiro <takahiro.akashi(a)linaro.org>
---
arm64.c | 232 ++++++++++++++++++++++++++++++++++++++++++++++++--------------
defs.h | 26 ++++---
main.c | 7 +-
symbols.c | 12 ++--
4 files changed, 211 insertions(+), 66 deletions(-)
diff --git a/arm64.c b/arm64.c
index 86ec348..37524c8 100644
--- a/arm64.c
+++ b/arm64.c
@@ -73,6 +73,23 @@ 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) {
+ if (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);
+ } else {
+ return machdep->machspec->phys_offset
+ + (addr - machdep->machspec->page_offset);
+ }
+}
/*
* Do all necessary machine-specific setup here. This is called several times
@@ -82,6 +99,7 @@ void
arm64_init(int when)
{
ulong value;
+ char *string;
struct machine_specific *ms;
#if defined(__x86_64__)
@@ -103,9 +121,32 @@ 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;
+
+ /*
+ * Even if CONFIG_RANDOMIZE_BASE is not configured,
+ * derive_kaslr_offset() should work and set
+ * kt->relocate to 0
+ */
+ if (!kt->relocate && !(kt->flags2 & (RELOC_AUTO|KASLR)))
+ kt->flags2 |= (RELOC_AUTO|KASLR);
+ }
+
break;
case PRE_GDB:
+ if (kernel_symbol_exists("kimage_voffset"))
+ machdep->flags |= NEW_VMEMMAP;
+
if (!machdep->pagesize) {
/*
* Kerneldoc Documentation/arm64/booting.txt describes
@@ -161,16 +202,34 @@ 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;
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)
{
@@ -241,8 +300,6 @@ 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;
@@ -271,6 +328,10 @@ 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:
@@ -420,6 +481,8 @@ 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);
@@ -524,6 +587,11 @@ 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);
@@ -566,6 +634,42 @@ 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.
@@ -577,11 +681,10 @@ 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])
@@ -603,39 +706,23 @@ 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",
@@ -720,7 +807,32 @@ arm64_calc_phys_offset(void)
static int
arm64_kdump_phys_base(ulong *phys_offset)
{
- return arm_kdump_phys_base(phys_offset);
+ char *string;
+ struct syment *sp;
+ physaddr_t paddr;
+
+ if (string = pc->read_vmcoreinfo("NUMBER(PHYS_OFFSET)")) {
+ *phys_offset = htol(string, QUIET, NULL);
+ free(string);
+ return TRUE;
+ }
+
+ if (machdep->flags & NEW_VMEMMAP) {
+ if (!(sp = kernel_symbol_search("memstart_addr")))
+ return FALSE;
+
+ /* sanity check */
+ if (!machdep->machspec->kimage_voffset)
+ return FALSE;
+
+ paddr = sp->value - machdep->machspec->kimage_voffset;
+ if (READMEM(-1, phys_offset, sizeof(*phys_offset),
+ sp->value, paddr) > 0)
+ return TRUE;
+ else
+ return FALSE;
+ } else
+ return arm_kdump_phys_base(phys_offset);
}
static void
@@ -2509,6 +2621,11 @@ 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)) ||
@@ -2539,7 +2656,10 @@ arm64_calc_VA_BITS(void)
for (bitval = highest_bit_long(value); bitval; bitval--) {
if ((value & (1UL << bitval)) == 0) {
- machdep->machspec->VA_BITS = bitval + 2;
+ if (machdep->flags & NEW_VMEMMAP)
+ machdep->machspec->VA_BITS = bitval + 1;
+ else
+ machdep->machspec->VA_BITS = bitval + 2;
break;
}
}
@@ -2593,10 +2713,22 @@ 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 8eb601b..d6f719c 100644
--- a/defs.h
+++ b/defs.h
@@ -2846,8 +2846,8 @@ 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)
@@ -2962,19 +2962,24 @@ typedef signed int s32;
#define VM_L3_4K (0x10)
#define KDUMP_ENABLED (0x20)
#define IRQ_STACKS (0x40)
-#define VM_L4_4K (0x80)
+#define NEW_VMEMMAP (0x80)
+#define VM_L4_4K (0x100)
/*
* 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.
@@ -3055,6 +3060,10 @@ struct machine_specific {
ulong *irq_stacks;
ulong __irqentry_text_start;
ulong __irqentry_text_end;
+ /* only needed for v4.6 or later kernel */
+ ulong kimage_voffset;
+ ulong kimage_text;
+ ulong kimage_end;
};
struct arm64_stackframe {
@@ -5412,6 +5421,7 @@ 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 05787f0..4065e9a 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..b0a6461 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;
@@ -833,7 +835,7 @@ store_sysmap_symbols(void)
}
/*
- * Handle x86 kernels configured such that the vmlinux symbols
+ * Handle x86/arm64 kernels configured such that the vmlinux symbols
* are not as loaded into the kernel (not unity-mapped).
*/
static ulong
@@ -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
10:30 p.m.
Pratyush,
On Mon, Jun 13, 2016 at 02:33:22PM +0530, Pratyush Anand wrote:
Hi Takahiro,
On 13/06/2016:05:10:08 PM, AKASHI Takahiro wrote:
> In my next version of kdump patch, the following VMCOREINFO will be
> added:
> NUMBER(VA_BITS)
> NUMBER(kimage_voffset)
> NUMBER(PHYS_OFFSET)
> KERNELOFFSET
>
> I think that those will also satisfy mkdumpfile requirements.
> -> Pratyush
Thanks, Those would be useful for Makedumpfile. However, I am still not able to
see a way to distinguish between kernel text area and others.
makedumpfile needs a way to identify between VAs "which could be translated using
__pa()" and others, "which needs to be translated using page tables".
Currently,
it uses __pa() if a VA is not within either vmalloc, or vmemmap or module area.
But as, you had suggested, it seems a better approach to translate using __pa()
when VA >= PAGE_OFFSET || (VA >= SYMBOL(_text) && vaddr <=
SYMBOL(_end)). I am
still not getting, how can I get _end from the passed information.
According to vmlinux.lds.S, "_end" can be calculated as:
_end = swapper_pg_dir + SWAPPER_DIR_SIZE
though it can be vulnerable.
Another approach will be that you can scan MMU tables (swapper_pg_dir)
even if you don't know "_end", and then identify the continuously
linear-mapped memory range starting from "_stext".
Just as ideas.
Obviously, VMCOREINFO("SYMBOL(_end)") would be simple.
Anyway, this won't be a topic in crash-utility mailing list :)
Thanks,
-Takahiro AKASHI
~Pratyush
>
> Thanks,
> -Takahiro AKASHI
>
> changes in v5:
> * Calcs PHYS_OFFSET by reading VMCOREINFO, "NUMBER(PHYS_OFFSET)"
> "memstart_addr"-based routine was also moved into
arm64_calc_phys_base().
>
> changes in v4:
> * Fixed VA_BITS calculation for v4.5 or earlier
> * Added 4-level address translation with 4KB page size
> * Removed "fix a renaming of a member of struct page, _count to
_refcount"
>
> Chnages in v3:
> * Refined KASLR handling
> hopefully the tool works even on a live system if CONFIG_RANDOMIZE_RAM is
> not configured
> * Fixed a renaming of a member of struct page
> * Removed a commit message regarding an issue of backtracing a panic'ed task
> because this is not a bug in this tool, but my kdump patch's.
> * Reported "kmem <vmalloc addr>" issue in a commit message
>
> 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 a6dd9d73120dcc3f2d68dbe9a8f2d16a128c4002 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 v5] 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.
>
> * On a live system, crash with this patch won't work, especially
> with CONFIG_RANDOMIZE_BASE configured, because we currently have no way
> to know kimage_voffset.
>
> * 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.)
>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi(a)linaro.org>
> ---
> arm64.c | 232 ++++++++++++++++++++++++++++++++++++++++++++++++--------------
> defs.h | 26 ++++---
> main.c | 7 +-
> symbols.c | 12 ++--
> 4 files changed, 211 insertions(+), 66 deletions(-)
>
> diff --git a/arm64.c b/arm64.c
> index 86ec348..37524c8 100644
> --- a/arm64.c
> +++ b/arm64.c
> @@ -73,6 +73,23 @@ 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) {
> + if (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);
> + } else {
> + return machdep->machspec->phys_offset
> + + (addr - machdep->machspec->page_offset);
> + }
> +}
>
> /*
> * Do all necessary machine-specific setup here. This is called several times
> @@ -82,6 +99,7 @@ void
> arm64_init(int when)
> {
> ulong value;
> + char *string;
> struct machine_specific *ms;
>
> #if defined(__x86_64__)
> @@ -103,9 +121,32 @@ 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;
> +
> + /*
> + * Even if CONFIG_RANDOMIZE_BASE is not configured,
> + * derive_kaslr_offset() should work and set
> + * kt->relocate to 0
> + */
> + if (!kt->relocate && !(kt->flags2 & (RELOC_AUTO|KASLR)))
> + kt->flags2 |= (RELOC_AUTO|KASLR);
> + }
> +
> break;
>
> case PRE_GDB:
> + if (kernel_symbol_exists("kimage_voffset"))
> + machdep->flags |= NEW_VMEMMAP;
> +
> if (!machdep->pagesize) {
> /*
> * Kerneldoc Documentation/arm64/booting.txt describes
> @@ -161,16 +202,34 @@ 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;
> 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)
> {
> @@ -241,8 +300,6 @@ 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;
> @@ -271,6 +328,10 @@ 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:
> @@ -420,6 +481,8 @@ 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);
> @@ -524,6 +587,11 @@ 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);
> @@ -566,6 +634,42 @@ 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.
> @@ -577,11 +681,10 @@ 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])
> @@ -603,39 +706,23 @@ 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",
> @@ -720,7 +807,32 @@ arm64_calc_phys_offset(void)
> static int
> arm64_kdump_phys_base(ulong *phys_offset)
> {
> - return arm_kdump_phys_base(phys_offset);
> + char *string;
> + struct syment *sp;
> + physaddr_t paddr;
> +
> + if (string = pc->read_vmcoreinfo("NUMBER(PHYS_OFFSET)")) {
> + *phys_offset = htol(string, QUIET, NULL);
> + free(string);
> + return TRUE;
> + }
> +
> + if (machdep->flags & NEW_VMEMMAP) {
> + if (!(sp = kernel_symbol_search("memstart_addr")))
> + return FALSE;
> +
> + /* sanity check */
> + if (!machdep->machspec->kimage_voffset)
> + return FALSE;
> +
> + paddr = sp->value - machdep->machspec->kimage_voffset;
> + if (READMEM(-1, phys_offset, sizeof(*phys_offset),
> + sp->value, paddr) > 0)
> + return TRUE;
> + else
> + return FALSE;
> + } else
> + return arm_kdump_phys_base(phys_offset);
> }
>
> static void
> @@ -2509,6 +2621,11 @@ 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)) ||
> @@ -2539,7 +2656,10 @@ arm64_calc_VA_BITS(void)
>
> for (bitval = highest_bit_long(value); bitval; bitval--) {
> if ((value & (1UL << bitval)) == 0) {
> - machdep->machspec->VA_BITS = bitval + 2;
> + if (machdep->flags & NEW_VMEMMAP)
> + machdep->machspec->VA_BITS = bitval + 1;
> + else
> + machdep->machspec->VA_BITS = bitval + 2;
> break;
> }
> }
> @@ -2593,10 +2713,22 @@ 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 8eb601b..d6f719c 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -2846,8 +2846,8 @@ 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)
> @@ -2962,19 +2962,24 @@ typedef signed int s32;
> #define VM_L3_4K (0x10)
> #define KDUMP_ENABLED (0x20)
> #define IRQ_STACKS (0x40)
> -#define VM_L4_4K (0x80)
> +#define NEW_VMEMMAP (0x80)
> +#define VM_L4_4K (0x100)
>
> /*
> * 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.
> @@ -3055,6 +3060,10 @@ struct machine_specific {
> ulong *irq_stacks;
> ulong __irqentry_text_start;
> ulong __irqentry_text_end;
> + /* only needed for v4.6 or later kernel */
> + ulong kimage_voffset;
> + ulong kimage_text;
> + ulong kimage_end;
> };
>
> struct arm64_stackframe {
> @@ -5412,6 +5421,7 @@ 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 05787f0..4065e9a 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..b0a6461 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;
> @@ -833,7 +835,7 @@ store_sysmap_symbols(void)
> }
>
> /*
> - * Handle x86 kernels configured such that the vmlinux symbols
> + * Handle x86/arm64 kernels configured such that the vmlinux symbols
> * are not as loaded into the kernel (not unity-mapped).
> */
> static ulong
> @@ -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
4:06 p.m.
----- Original Message -----
In my next version of kdump patch, the following VMCOREINFO will be
added:
NUMBER(VA_BITS)
NUMBER(kimage_voffset)
NUMBER(PHYS_OFFSET)
KERNELOFFSET
I think that those will also satisfy mkdumpfile requirements.
-> Pratyush
Thanks,
-Takahiro AKASHI
Hi Takahiro,
This patch looks good. From my end, I'm pretty much ready to check
it in, notwithstanding the lack of live system KASLR support. And
even in that case, a live system with KASLR enabled could be brought
up with --machdep arguments for now.
One minor nit:
$ make warn
...
arm64.c: In function 'arm64_kdump_phys_base':
arm64.c:814:2: warning: suggest parentheses around assignment used as truth value
[-Wparentheses]
if (string = pc->read_vmcoreinfo("NUMBER(PHYS_OFFSET)")) {
^
...
And speaking of arm64_kdump_phys_base(), I do have a question about the 3 FALSE returns:
@@ -720,7 +807,32 @@ arm64_calc_phys_offset(void)
static int
arm64_kdump_phys_base(ulong *phys_offset)
{
- return arm_kdump_phys_base(phys_offset);
+ char *string;
+ struct syment *sp;
+ physaddr_t paddr;
+
+ if (string = pc->read_vmcoreinfo("NUMBER(PHYS_OFFSET)")) {
+ *phys_offset = htol(string, QUIET, NULL);
+ free(string);
+ return TRUE;
+ }
+
+ if (machdep->flags & NEW_VMEMMAP) {
+ if (!(sp = kernel_symbol_search("memstart_addr")))
+ return FALSE;
+
+ /* sanity check */
+ if (!machdep->machspec->kimage_voffset)
+ return FALSE;
How could NEW_VMEMMAP possibly be set if !machdep->machspec->kimage_voffset?
+
+ paddr = sp->value - machdep->machspec->kimage_voffset;
+ if (READMEM(-1, phys_offset, sizeof(*phys_offset),
+ sp->value, paddr) > 0)
+ return TRUE;
+ else
+ return FALSE;
+ } else
+ return arm_kdump_phys_base(phys_offset);
}
But regardless whether the "sanity check" needs to be made, shouldn't
all 3 of the FALSE returns above alternatively allow arm_kdump_phys_base()
to go ahead with its PT_LOAD segment check?
In any case, do you have anything else you would like to add to it?
Thanks,
Dave
changes in v5:
* Calcs PHYS_OFFSET by reading VMCOREINFO, "NUMBER(PHYS_OFFSET)"
"memstart_addr"-based routine was also moved into arm64_calc_phys_base().
changes in v4:
* Fixed VA_BITS calculation for v4.5 or earlier
* Added 4-level address translation with 4KB page size
* Removed "fix a renaming of a member of struct page, _count to _refcount"
Chnages in v3:
* Refined KASLR handling
hopefully the tool works even on a live system if CONFIG_RANDOMIZE_RAM is
not configured
* Fixed a renaming of a member of struct page
* Removed a commit message regarding an issue of backtracing a panic'ed task
because this is not a bug in this tool, but my kdump patch's.
* Reported "kmem <vmalloc addr>" issue in a commit message
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 a6dd9d73120dcc3f2d68dbe9a8f2d16a128c4002 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 v5] 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.
* On a live system, crash with this patch won't work, especially
with CONFIG_RANDOMIZE_BASE configured, because we currently have no way
to know kimage_voffset.
* 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.)
Signed-off-by: AKASHI Takahiro <takahiro.akashi(a)linaro.org>
---
arm64.c | 232
++++++++++++++++++++++++++++++++++++++++++++++++--------------
defs.h | 26 ++++---
main.c | 7 +-
symbols.c | 12 ++--
4 files changed, 211 insertions(+), 66 deletions(-)
diff --git a/arm64.c b/arm64.c
index 86ec348..37524c8 100644
--- a/arm64.c
+++ b/arm64.c
@@ -73,6 +73,23 @@ 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) {
+ if (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);
+ } else {
+ return machdep->machspec->phys_offset
+ + (addr - machdep->machspec->page_offset);
+ }
+}
/*
* Do all necessary machine-specific setup here. This is called several
times
@@ -82,6 +99,7 @@ void
arm64_init(int when)
{
ulong value;
+ char *string;
struct machine_specific *ms;
#if defined(__x86_64__)
@@ -103,9 +121,32 @@ 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;
+
+ /*
+ * Even if CONFIG_RANDOMIZE_BASE is not configured,
+ * derive_kaslr_offset() should work and set
+ * kt->relocate to 0
+ */
+ if (!kt->relocate && !(kt->flags2 & (RELOC_AUTO|KASLR)))
+ kt->flags2 |= (RELOC_AUTO|KASLR);
+ }
+
break;
case PRE_GDB:
+ if (kernel_symbol_exists("kimage_voffset"))
+ machdep->flags |= NEW_VMEMMAP;
+
if (!machdep->pagesize) {
/*
* Kerneldoc Documentation/arm64/booting.txt describes
@@ -161,16 +202,34 @@ 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;
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)
{
@@ -241,8 +300,6 @@ 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;
@@ -271,6 +328,10 @@ 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:
@@ -420,6 +481,8 @@ 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);
@@ -524,6 +587,11 @@ 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);
@@ -566,6 +634,42 @@ 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.
@@ -577,11 +681,10 @@ 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])
@@ -603,39 +706,23 @@ 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",
@@ -720,7 +807,32 @@ arm64_calc_phys_offset(void)
static int
arm64_kdump_phys_base(ulong *phys_offset)
{
- return arm_kdump_phys_base(phys_offset);
+ char *string;
+ struct syment *sp;
+ physaddr_t paddr;
+
+ if (string = pc->read_vmcoreinfo("NUMBER(PHYS_OFFSET)")) {
+ *phys_offset = htol(string, QUIET, NULL);
+ free(string);
+ return TRUE;
+ }
+
+ if (machdep->flags & NEW_VMEMMAP) {
+ if (!(sp = kernel_symbol_search("memstart_addr")))
+ return FALSE;
+
+ /* sanity check */
+ if (!machdep->machspec->kimage_voffset)
+ return FALSE;
+
+ paddr = sp->value - machdep->machspec->kimage_voffset;
+ if (READMEM(-1, phys_offset, sizeof(*phys_offset),
+ sp->value, paddr) > 0)
+ return TRUE;
+ else
+ return FALSE;
+ } else
+ return arm_kdump_phys_base(phys_offset);
}
static void
@@ -2509,6 +2621,11 @@ 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))
||
@@ -2539,7 +2656,10 @@ arm64_calc_VA_BITS(void)
for (bitval = highest_bit_long(value); bitval; bitval--) {
if ((value & (1UL << bitval)) == 0) {
- machdep->machspec->VA_BITS = bitval + 2;
+ if (machdep->flags & NEW_VMEMMAP)
+ machdep->machspec->VA_BITS = bitval + 1;
+ else
+ machdep->machspec->VA_BITS = bitval + 2;
break;
}
}
@@ -2593,10 +2713,22 @@ 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 8eb601b..d6f719c 100644
--- a/defs.h
+++ b/defs.h
@@ -2846,8 +2846,8 @@ 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)
@@ -2962,19 +2962,24 @@ typedef signed int s32;
#define VM_L3_4K (0x10)
#define KDUMP_ENABLED (0x20)
#define IRQ_STACKS (0x40)
-#define VM_L4_4K (0x80)
+#define NEW_VMEMMAP (0x80)
+#define VM_L4_4K (0x100)
/*
* 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.
@@ -3055,6 +3060,10 @@ struct machine_specific {
ulong *irq_stacks;
ulong __irqentry_text_start;
ulong __irqentry_text_end;
+ /* only needed for v4.6 or later kernel */
+ ulong kimage_voffset;
+ ulong kimage_text;
+ ulong kimage_end;
};
struct arm64_stackframe {
@@ -5412,6 +5421,7 @@ 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 05787f0..4065e9a 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..b0a6461 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;
@@ -833,7 +835,7 @@ store_sysmap_symbols(void)
}
/*
- * Handle x86 kernels configured such that the vmlinux symbols
+ * Handle x86/arm64 kernels configured such that the vmlinux symbols
* are not as loaded into the kernel (not unity-mapped).
*/
static ulong
@@ -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
--
Crash-utility mailing list
Crash-utility(a)redhat.com
https://www.redhat.com/mailman/listinfo/crash-utility
9:22 p.m.
On Mon, Jun 13, 2016 at 04:06:22PM -0400, Dave Anderson wrote:
> In my next version of kdump patch, the following VMCOREINFO will be
> added:
> NUMBER(VA_BITS)
> NUMBER(kimage_voffset)
> NUMBER(PHYS_OFFSET)
> KERNELOFFSET
>
> I think that those will also satisfy mkdumpfile requirements.
> -> Pratyush
>
> Thanks,
> -Takahiro AKASHI
Hi Takahiro,
This patch looks good. From my end, I'm pretty much ready to check
it in, notwithstanding the lack of live system KASLR support. And
even in that case, a live system with KASLR enabled could be brought
up with --machdep arguments for now.
One minor nit:
$ make warn
...
arm64.c: In function 'arm64_kdump_phys_base':
arm64.c:814:2: warning: suggest parentheses around assignment used as truth value
[-Wparentheses]
if (string = pc->read_vmcoreinfo("NUMBER(PHYS_OFFSET)")) {
^
...
Oops, fixed it.
And speaking of arm64_kdump_phys_base(), I do have a question about
the 3 FALSE returns:
@@ -720,7 +807,32 @@ arm64_calc_phys_offset(void)
static int
arm64_kdump_phys_base(ulong *phys_offset)
{
- return arm_kdump_phys_base(phys_offset);
+ char *string;
+ struct syment *sp;
+ physaddr_t paddr;
+
+ if (string = pc->read_vmcoreinfo("NUMBER(PHYS_OFFSET)")) {
+ *phys_offset = htol(string, QUIET, NULL);
+ free(string);
+ return TRUE;
+ }
+
+ if (machdep->flags & NEW_VMEMMAP) {
+ if (!(sp = kernel_symbol_search("memstart_addr")))
+ return FALSE;
+
+ /* sanity check */
+ if (!machdep->machspec->kimage_voffset)
+ return FALSE;
How could NEW_VMEMMAP possibly be set if !machdep->machspec->kimage_voffset?
It is possible iff:
* v4.6 or later
* on a live system
* user doesn't specify "--machdep kimage_voffset" option
This is also why I put "if (kimage_voffset)" check in arm64_VTOP().
+
+ paddr = sp->value - machdep->machspec->kimage_voffset;
+ if (READMEM(-1, phys_offset, sizeof(*phys_offset),
+ sp->value, paddr) > 0)
+ return TRUE;
+ else
+ return FALSE;
+ } else
+ return arm_kdump_phys_base(phys_offset);
}
But regardless whether the "sanity check" needs to be made, shouldn't
all 3 of the FALSE returns above alternatively allow arm_kdump_phys_base()
to go ahead with its PT_LOAD segment check?
OK as a last resort.
In any case, do you have anything else you would like to add to it?
No. Please take a look at my next version, v6, hopefully the last one :)
Thanks,
-Takahiro AKASHI
Thanks,
Dave
> changes in v5:
> * Calcs PHYS_OFFSET by reading VMCOREINFO, "NUMBER(PHYS_OFFSET)"
> "memstart_addr"-based routine was also moved into
arm64_calc_phys_base().
>
> changes in v4:
> * Fixed VA_BITS calculation for v4.5 or earlier
> * Added 4-level address translation with 4KB page size
> * Removed "fix a renaming of a member of struct page, _count to
_refcount"
>
> Chnages in v3:
> * Refined KASLR handling
> hopefully the tool works even on a live system if CONFIG_RANDOMIZE_RAM is
> not configured
> * Fixed a renaming of a member of struct page
> * Removed a commit message regarding an issue of backtracing a panic'ed task
> because this is not a bug in this tool, but my kdump patch's.
> * Reported "kmem <vmalloc addr>" issue in a commit message
>
> 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 a6dd9d73120dcc3f2d68dbe9a8f2d16a128c4002 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 v5] 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.
>
> * On a live system, crash with this patch won't work, especially
> with CONFIG_RANDOMIZE_BASE configured, because we currently have no way
> to know kimage_voffset.
>
> * 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.)
>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi(a)linaro.org>
> ---
> arm64.c | 232
> ++++++++++++++++++++++++++++++++++++++++++++++++--------------
> defs.h | 26 ++++---
> main.c | 7 +-
> symbols.c | 12 ++--
> 4 files changed, 211 insertions(+), 66 deletions(-)
>
> diff --git a/arm64.c b/arm64.c
> index 86ec348..37524c8 100644
> --- a/arm64.c
> +++ b/arm64.c
> @@ -73,6 +73,23 @@ 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) {
> + if (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);
> + } else {
> + return machdep->machspec->phys_offset
> + + (addr - machdep->machspec->page_offset);
> + }
> +}
>
> /*
> * Do all necessary machine-specific setup here. This is called several
> times
> @@ -82,6 +99,7 @@ void
> arm64_init(int when)
> {
> ulong value;
> + char *string;
> struct machine_specific *ms;
>
> #if defined(__x86_64__)
> @@ -103,9 +121,32 @@ 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;
> +
> + /*
> + * Even if CONFIG_RANDOMIZE_BASE is not configured,
> + * derive_kaslr_offset() should work and set
> + * kt->relocate to 0
> + */
> + if (!kt->relocate && !(kt->flags2 & (RELOC_AUTO|KASLR)))
> + kt->flags2 |= (RELOC_AUTO|KASLR);
> + }
> +
> break;
>
> case PRE_GDB:
> + if (kernel_symbol_exists("kimage_voffset"))
> + machdep->flags |= NEW_VMEMMAP;
> +
> if (!machdep->pagesize) {
> /*
> * Kerneldoc Documentation/arm64/booting.txt describes
> @@ -161,16 +202,34 @@ 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;
> 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)
> {
> @@ -241,8 +300,6 @@ 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;
> @@ -271,6 +328,10 @@ 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:
> @@ -420,6 +481,8 @@ 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);
> @@ -524,6 +587,11 @@ 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);
> @@ -566,6 +634,42 @@ 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.
> @@ -577,11 +681,10 @@ 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])
> @@ -603,39 +706,23 @@ 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",
> @@ -720,7 +807,32 @@ arm64_calc_phys_offset(void)
> static int
> arm64_kdump_phys_base(ulong *phys_offset)
> {
> - return arm_kdump_phys_base(phys_offset);
> + char *string;
> + struct syment *sp;
> + physaddr_t paddr;
> +
> + if (string = pc->read_vmcoreinfo("NUMBER(PHYS_OFFSET)")) {
> + *phys_offset = htol(string, QUIET, NULL);
> + free(string);
> + return TRUE;
> + }
> +
> + if (machdep->flags & NEW_VMEMMAP) {
> + if (!(sp = kernel_symbol_search("memstart_addr")))
> + return FALSE;
> +
> + /* sanity check */
> + if (!machdep->machspec->kimage_voffset)
> + return FALSE;
> +
> + paddr = sp->value - machdep->machspec->kimage_voffset;
> + if (READMEM(-1, phys_offset, sizeof(*phys_offset),
> + sp->value, paddr) > 0)
> + return TRUE;
> + else
> + return FALSE;
> + } else
> + return arm_kdump_phys_base(phys_offset);
> }
>
> static void
> @@ -2509,6 +2621,11 @@ 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))
> ||
> @@ -2539,7 +2656,10 @@ arm64_calc_VA_BITS(void)
>
> for (bitval = highest_bit_long(value); bitval; bitval--) {
> if ((value & (1UL << bitval)) == 0) {
> - machdep->machspec->VA_BITS = bitval + 2;
> + if (machdep->flags & NEW_VMEMMAP)
> + machdep->machspec->VA_BITS = bitval + 1;
> + else
> + machdep->machspec->VA_BITS = bitval + 2;
> break;
> }
> }
> @@ -2593,10 +2713,22 @@ 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 8eb601b..d6f719c 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -2846,8 +2846,8 @@ 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)
> @@ -2962,19 +2962,24 @@ typedef signed int s32;
> #define VM_L3_4K (0x10)
> #define KDUMP_ENABLED (0x20)
> #define IRQ_STACKS (0x40)
> -#define VM_L4_4K (0x80)
> +#define NEW_VMEMMAP (0x80)
> +#define VM_L4_4K (0x100)
>
> /*
> * 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.
> @@ -3055,6 +3060,10 @@ struct machine_specific {
> ulong *irq_stacks;
> ulong __irqentry_text_start;
> ulong __irqentry_text_end;
> + /* only needed for v4.6 or later kernel */
> + ulong kimage_voffset;
> + ulong kimage_text;
> + ulong kimage_end;
> };
>
> struct arm64_stackframe {
> @@ -5412,6 +5421,7 @@ 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 05787f0..4065e9a 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..b0a6461 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;
> @@ -833,7 +835,7 @@ store_sysmap_symbols(void)
> }
>
> /*
> - * Handle x86 kernels configured such that the vmlinux symbols
> + * Handle x86/arm64 kernels configured such that the vmlinux symbols
> * are not as loaded into the kernel (not unity-mapped).
> */
> static ulong
> @@ -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
>
> --
> Crash-utility mailing list
> Crash-utility(a)redhat.com
> https://www.redhat.com/mailman/listinfo/crash-utility
>
--
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Crash-utility(a)redhat.com
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1:47 a.m.
Dave,
On Mon, Jun 13, 2016 at 04:06:22PM -0400, Dave Anderson wrote:
----- Original Message -----
> In my next version of kdump patch, the following VMCOREINFO will be
> added:
> NUMBER(VA_BITS)
> NUMBER(kimage_voffset)
> NUMBER(PHYS_OFFSET)
> KERNELOFFSET
Is "KERNELOFFSET" useful for arm64?
As you said, this value is used as a trigger of KASLR_CHECK,
but the current kernel doesn't have "randomize_modules".
Thanks,
-Takahiro AKASHI
> I think that those will also satisfy mkdumpfile requirements.
> -> Pratyush
>
> Thanks,
> -Takahiro AKASHI
Hi Takahiro,
This patch looks good. From my end, I'm pretty much ready to check
it in, notwithstanding the lack of live system KASLR support. And
even in that case, a live system with KASLR enabled could be brought
up with --machdep arguments for now.
One minor nit:
$ make warn
...
arm64.c: In function 'arm64_kdump_phys_base':
arm64.c:814:2: warning: suggest parentheses around assignment used as truth value
[-Wparentheses]
if (string = pc->read_vmcoreinfo("NUMBER(PHYS_OFFSET)")) {
^
...
And speaking of arm64_kdump_phys_base(), I do have a question about the 3 FALSE returns:
@@ -720,7 +807,32 @@ arm64_calc_phys_offset(void)
static int
arm64_kdump_phys_base(ulong *phys_offset)
{
- return arm_kdump_phys_base(phys_offset);
+ char *string;
+ struct syment *sp;
+ physaddr_t paddr;
+
+ if (string = pc->read_vmcoreinfo("NUMBER(PHYS_OFFSET)")) {
+ *phys_offset = htol(string, QUIET, NULL);
+ free(string);
+ return TRUE;
+ }
+
+ if (machdep->flags & NEW_VMEMMAP) {
+ if (!(sp = kernel_symbol_search("memstart_addr")))
+ return FALSE;
+
+ /* sanity check */
+ if (!machdep->machspec->kimage_voffset)
+ return FALSE;
How could NEW_VMEMMAP possibly be set if !machdep->machspec->kimage_voffset?
+
+ paddr = sp->value - machdep->machspec->kimage_voffset;
+ if (READMEM(-1, phys_offset, sizeof(*phys_offset),
+ sp->value, paddr) > 0)
+ return TRUE;
+ else
+ return FALSE;
+ } else
+ return arm_kdump_phys_base(phys_offset);
}
But regardless whether the "sanity check" needs to be made, shouldn't
all 3 of the FALSE returns above alternatively allow arm_kdump_phys_base()
to go ahead with its PT_LOAD segment check?
In any case, do you have anything else you would like to add to it?
Thanks,
Dave
> changes in v5:
> * Calcs PHYS_OFFSET by reading VMCOREINFO, "NUMBER(PHYS_OFFSET)"
> "memstart_addr"-based routine was also moved into
arm64_calc_phys_base().
>
> changes in v4:
> * Fixed VA_BITS calculation for v4.5 or earlier
> * Added 4-level address translation with 4KB page size
> * Removed "fix a renaming of a member of struct page, _count to
_refcount"
>
> Chnages in v3:
> * Refined KASLR handling
> hopefully the tool works even on a live system if CONFIG_RANDOMIZE_RAM is
> not configured
> * Fixed a renaming of a member of struct page
> * Removed a commit message regarding an issue of backtracing a panic'ed task
> because this is not a bug in this tool, but my kdump patch's.
> * Reported "kmem <vmalloc addr>" issue in a commit message
>
> 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 a6dd9d73120dcc3f2d68dbe9a8f2d16a128c4002 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 v5] 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.
>
> * On a live system, crash with this patch won't work, especially
> with CONFIG_RANDOMIZE_BASE configured, because we currently have no way
> to know kimage_voffset.
>
> * 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.)
>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi(a)linaro.org>
> ---
> arm64.c | 232
> ++++++++++++++++++++++++++++++++++++++++++++++++--------------
> defs.h | 26 ++++---
> main.c | 7 +-
> symbols.c | 12 ++--
> 4 files changed, 211 insertions(+), 66 deletions(-)
>
> diff --git a/arm64.c b/arm64.c
> index 86ec348..37524c8 100644
> --- a/arm64.c
> +++ b/arm64.c
> @@ -73,6 +73,23 @@ 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) {
> + if (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);
> + } else {
> + return machdep->machspec->phys_offset
> + + (addr - machdep->machspec->page_offset);
> + }
> +}
>
> /*
> * Do all necessary machine-specific setup here. This is called several
> times
> @@ -82,6 +99,7 @@ void
> arm64_init(int when)
> {
> ulong value;
> + char *string;
> struct machine_specific *ms;
>
> #if defined(__x86_64__)
> @@ -103,9 +121,32 @@ 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;
> +
> + /*
> + * Even if CONFIG_RANDOMIZE_BASE is not configured,
> + * derive_kaslr_offset() should work and set
> + * kt->relocate to 0
> + */
> + if (!kt->relocate && !(kt->flags2 & (RELOC_AUTO|KASLR)))
> + kt->flags2 |= (RELOC_AUTO|KASLR);
> + }
> +
> break;
>
> case PRE_GDB:
> + if (kernel_symbol_exists("kimage_voffset"))
> + machdep->flags |= NEW_VMEMMAP;
> +
> if (!machdep->pagesize) {
> /*
> * Kerneldoc Documentation/arm64/booting.txt describes
> @@ -161,16 +202,34 @@ 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;
> 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)
> {
> @@ -241,8 +300,6 @@ 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;
> @@ -271,6 +328,10 @@ 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:
> @@ -420,6 +481,8 @@ 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);
> @@ -524,6 +587,11 @@ 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);
> @@ -566,6 +634,42 @@ 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.
> @@ -577,11 +681,10 @@ 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])
> @@ -603,39 +706,23 @@ 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",
> @@ -720,7 +807,32 @@ arm64_calc_phys_offset(void)
> static int
> arm64_kdump_phys_base(ulong *phys_offset)
> {
> - return arm_kdump_phys_base(phys_offset);
> + char *string;
> + struct syment *sp;
> + physaddr_t paddr;
> +
> + if (string = pc->read_vmcoreinfo("NUMBER(PHYS_OFFSET)")) {
> + *phys_offset = htol(string, QUIET, NULL);
> + free(string);
> + return TRUE;
> + }
> +
> + if (machdep->flags & NEW_VMEMMAP) {
> + if (!(sp = kernel_symbol_search("memstart_addr")))
> + return FALSE;
> +
> + /* sanity check */
> + if (!machdep->machspec->kimage_voffset)
> + return FALSE;
> +
> + paddr = sp->value - machdep->machspec->kimage_voffset;
> + if (READMEM(-1, phys_offset, sizeof(*phys_offset),
> + sp->value, paddr) > 0)
> + return TRUE;
> + else
> + return FALSE;
> + } else
> + return arm_kdump_phys_base(phys_offset);
> }
>
> static void
> @@ -2509,6 +2621,11 @@ 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))
> ||
> @@ -2539,7 +2656,10 @@ arm64_calc_VA_BITS(void)
>
> for (bitval = highest_bit_long(value); bitval; bitval--) {
> if ((value & (1UL << bitval)) == 0) {
> - machdep->machspec->VA_BITS = bitval + 2;
> + if (machdep->flags & NEW_VMEMMAP)
> + machdep->machspec->VA_BITS = bitval + 1;
> + else
> + machdep->machspec->VA_BITS = bitval + 2;
> break;
> }
> }
> @@ -2593,10 +2713,22 @@ 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 8eb601b..d6f719c 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -2846,8 +2846,8 @@ 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)
> @@ -2962,19 +2962,24 @@ typedef signed int s32;
> #define VM_L3_4K (0x10)
> #define KDUMP_ENABLED (0x20)
> #define IRQ_STACKS (0x40)
> -#define VM_L4_4K (0x80)
> +#define NEW_VMEMMAP (0x80)
> +#define VM_L4_4K (0x100)
>
> /*
> * 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.
> @@ -3055,6 +3060,10 @@ struct machine_specific {
> ulong *irq_stacks;
> ulong __irqentry_text_start;
> ulong __irqentry_text_end;
> + /* only needed for v4.6 or later kernel */
> + ulong kimage_voffset;
> + ulong kimage_text;
> + ulong kimage_end;
> };
>
> struct arm64_stackframe {
> @@ -5412,6 +5421,7 @@ 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 05787f0..4065e9a 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..b0a6461 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;
> @@ -833,7 +835,7 @@ store_sysmap_symbols(void)
> }
>
> /*
> - * Handle x86 kernels configured such that the vmlinux symbols
> + * Handle x86/arm64 kernels configured such that the vmlinux symbols
> * are not as loaded into the kernel (not unity-mapped).
> */
> static ulong
> @@ -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
>
> --
> Crash-utility mailing list
> Crash-utility(a)redhat.com
> https://www.redhat.com/mailman/listinfo/crash-utility
>
--
Crash-utility mailing list
Crash-utility(a)redhat.com
https://www.redhat.com/mailman/listinfo/crash-utility
10:08 a.m.
----- Original Message -----
Dave,
On Mon, Jun 13, 2016 at 04:06:22PM -0400, Dave Anderson wrote:
>
>
> ----- Original Message -----
> > In my next version of kdump patch, the following VMCOREINFO will be
> > added:
> > NUMBER(VA_BITS)
> > NUMBER(kimage_voffset)
> > NUMBER(PHYS_OFFSET)
> > KERNELOFFSET
Is "KERNELOFFSET" useful for arm64?
As you said, this value is used as a trigger of KASLR_CHECK,
but the current kernel doesn't have "randomize_modules".
Right, so AIUI, this crash-7.0.7 update is not valid for Linux 4.1 and later
kernels where "randomize_modules" was removed:
- Linux 3.15 and later kernels configured with CONFIG_RANDOMIZE_BASE
can be now be readily identified because of new kernel symbols that
have been added. For those kernels, the new "--kaslr=<offset>"
and/or "--kaslr=auto" options are not necessary for ELF or
compressed
kdump vmcores, or for live systems that have /proc/kallsyms showing
the relocated symbol values. A new KASLR initialization function
called kaslr_init() is now called by symtab_init() prior to the
initial symbol-sorting operation. If kaslr_init() determines that
KASLR may be in effect, it will trigger a search for the relevant
vmlinux symbols during the sorting operation, which in turn will
cause the relocation value to be automatically calculated.
(anderson(a)redhat.com)
So for those kernels, --kaslr would be required.
But it appears that I can just change crash to look for "module_load_offset",
which went into the kernel at the same time as "randomize_modules":
+#ifdef CONFIG_RANDOMIZE_BASE
+static unsigned long module_load_offset;
+static int randomize_modules = 1;
+
and still exists after it was removed from arch/x86/kernel/module.c:
#ifdef CONFIG_RANDOMIZE_BASE
static unsigned long module_load_offset;
-static int randomize_modules = 1;
For arm64 in the crash utility, I see that you would never use KASLR_CHECK because
(RELOC_AUTO|KASLR) gets set by default if NEW_VMEMMAP is set.
Would it be useful for makedumpfile? And while I understand you're dead set against
adding anything that could be considered superfluous, but since it does exist for x86_64,
it seems natural to include it for arm64.
Dave
Thanks,
-Takahiro AKASHI
9:02 p.m.
On Tue, Jun 14, 2016 at 10:08:25AM -0400, Dave Anderson wrote:
> Dave,
>
> On Mon, Jun 13, 2016 at 04:06:22PM -0400, Dave Anderson wrote:
> >
> >
> > ----- Original Message -----
> > > In my next version of kdump patch, the following VMCOREINFO will be
> > > added:
> > > NUMBER(VA_BITS)
> > > NUMBER(kimage_voffset)
> > > NUMBER(PHYS_OFFSET)
> > > KERNELOFFSET
>
> Is "KERNELOFFSET" useful for arm64?
> As you said, this value is used as a trigger of KASLR_CHECK,
> but the current kernel doesn't have "randomize_modules".
Right, so AIUI, this crash-7.0.7 update is not valid for Linux 4.1 and later
kernels where "randomize_modules" was removed:
- Linux 3.15 and later kernels configured with CONFIG_RANDOMIZE_BASE
can be now be readily identified because of new kernel symbols that
have been added. For those kernels, the new
"--kaslr=<offset>"
and/or "--kaslr=auto" options are not necessary for ELF or
compressed
kdump vmcores, or for live systems that have /proc/kallsyms showing
the relocated symbol values. A new KASLR initialization function
called kaslr_init() is now called by symtab_init() prior to the
initial symbol-sorting operation. If kaslr_init() determines that
KASLR may be in effect, it will trigger a search for the relevant
vmlinux symbols during the sorting operation, which in turn will
cause the relocation value to be automatically calculated.
(anderson(a)redhat.com)
So for those kernels, --kaslr would be required.
But it appears that I can just change crash to look for "module_load_offset",
which went into the kernel at the same time as "randomize_modules":
+#ifdef CONFIG_RANDOMIZE_BASE
+static unsigned long module_load_offset;
+static int randomize_modules = 1;
+
and still exists after it was removed from arch/x86/kernel/module.c:
#ifdef CONFIG_RANDOMIZE_BASE
static unsigned long module_load_offset;
-static int randomize_modules = 1;
For arm64 in the crash utility, I see that you would never use KASLR_CHECK because
(RELOC_AUTO|KASLR) gets set by default if NEW_VMEMMAP is set.
Would it be useful for makedumpfile?
Given that makedumpfile doesn't reply on vmlinux, "kaslr_offset" is
not useful.
-> Pratyush, any comments?
So I'd like to exclude KERNELOFFSET in my kexec/dkump patch, v19,
hopefully posted this weekend.
(This won't hurt crash utility anyway.)
Thanks,
-Takahiro AKASHI
And while I understand you're dead set against
adding anything that could be considered superfluous, but since it does exist for
x86_64,
it seems natural to include it for arm64.
Dave
> Thanks,
> -Takahiro AKASHI
>
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7 comments
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participants (3)
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AKASHI Takahiro -
Dave Anderson -
Pratyush Anand