9:14 a.m.
Itsuro ODA wrote:
Hi,
The attached is some fixes which are necessary for xencrash to use
for the newer version of xen (after 3.1.0, ex. 3.1.2, 3.2.0).
* x86
- add some symbols which are used to know the boundary
condition at the tracing in 'bt'.
- fix for the symbol 'idle_pg_table_l3' going away.
* x86_64
- fix for the virtual address area of xen code/data is added.
- fix for the symbol 'idle_pg_table_l4' going away.
- add the option '--xen_phys_start_mfn='
newer version of xen (ex. RHEL5.2, 3.2.0) moves the
physical(machine) address of xen code/data area after
the system started up.
The relocated physical(machine) address of xen code/data
area is necessary to use xencrash.
The value can be got by 'cat /proc/iomem' under dom0.
-------------------------------------------------------
# cat /proc/iomem
...
7e600000-7f5fffff : Hypervisor code and data *** this line
...
-------------------------------------------------------
ex. to use xencrash:
# crash --xen_phys_start_mfn=0x7e600 xen-syms vmcore
- extract 'xen_phys_start_mfn' from the XEN_ELFNOTE_CRASH_INFO
ElfNote.
This is experimental code because it is necessary to modify
the xen to add the xen_phys_start_mfn value in the ElfNote
at crash time. (the patch is also attached in this mail.)
A sample dump is availavle in the following URL:
http://people.valinux.co.jp/~oda/x86_64_dump_080417.tar.gz
This patch is for crash-4.0-6.2.
Thanks.
Itsuro Oda
Hi Itsuro,
Thanks very much for the quick response.
I have one relatively minor issue. I understand that the previously existing
"--p2m_mfn" option was expressed as an mfn, and that made sense because its
value
exists in the xen hypervisor code as an mfn value (actually a xen_pfn_t).
But it seems unnecessary to bother going through the translation of the
hypservisors's "xen_phys_start" physical address into an mfn? And then
only to have the crash utility have to turn it back into a physical address
when it uses it? Why not just leave it as a physical address in both the
kernel patch, and when passing it to the crash utility?
From a user's standpoint, when it's necessary to pre-determine the argument from
a hypervisor/dom0 vmcore that doesn't contain it, the xen_phys_start can be
determined
by either reading /proc/iomem on the live system, where as you've shown in
the example above, it's 7e600000:
# cat /proc/iomem
...
7e600000-7f5fffff : Hypervisor code and data *** this line
...
Alternatively, the same dom0/HV kdump vmcore can be run in a crash session using
the dom0 vmlinux, where in this example vmcore, it's 0x3f000000:
crash> px xen_hypervisor_res
xen_hypervisor_res = $3 = {
start = 0x3f000000,
end = 0x3fffffff,
name = 0xffffffff8049ab72 "Hypervisor code and data",
flags = 0x80000200,
parent = 0xffff880000001180,
sibling = 0x0,
child = 0xffff8800000000a8
}
For convenience sake, I'd prefer to just leave it as that, without
needlessly forcing the user to translate the above into an mfn, so
that they can simply enter: "crash --xen_phys_start=0x3f000000 ..."
The same thing applies to the kernel patch -- just leave it in its
natural state as a physical (machine) address.
Unfortunately it's already going to be an annoyance to have to pre-determine
the xen_phys_start value -- so why bother making it even more cryptic by
forcing the user to turn it into an mfn?
Another theoretical question -- since the /proc/iomem exports the
xen_phys_start variable to user space, is there any way it could
be handled entirely in user space by kexec-tools?
Dave
=== for x86 ===
--- lkcd_x86_trace.c.org 2008-04-17 10:13:05.000000000 +0900
+++ lkcd_x86_trace.c 2008-04-17 10:13:17.000000000 +0900
@@ -1423,6 +1423,7 @@
if (XEN_HYPER_MODE()) {
func_name = kl_funcname(pc);
if (STREQ(func_name, "idle_loop") || STREQ(func_name,
"hypercall")
+ || STREQ(func_name, "tracing_off")
|| STREQ(func_name, "handle_exception")) {
UPDATE_FRAME(func_name, pc, 0, sp, bp, asp, 0, 0, bp - sp, 0);
return(trace->nframes);
@@ -1682,6 +1683,7 @@
if (func_name && XEN_HYPER_MODE()) {
if (STREQ(func_name, "continue_nmi") ||
STREQ(func_name, "vmx_asm_vmexit_handler") ||
+ STREQ(func_name, "handle_nmi_mce") ||
STREQ(func_name, "deferred_nmi")) {
/* Interrupt frame */
sp = curframe->fp + 4;
--- x86.c.org 2008-04-17 10:29:21.000000000 +0900
+++ x86.c 2008-04-17 10:31:51.000000000 +0900
@@ -2846,7 +2846,10 @@
*paddr = kvaddr - DIRECTMAP_VIRT_START;
return TRUE;
}
- pgd = (ulonglong *)symbol_value("idle_pg_table_l3");
+ if (symbol_exists("idle_pg_table_l3"))
+ pgd = (ulonglong *)symbol_value("idle_pg_table_l3");
+ else
+ pgd = (ulonglong *)symbol_value("idle_pg_table");
} else {
if (!vt->vmalloc_start) {
*paddr = VTOP(kvaddr);
@@ -4965,7 +4968,8 @@
break;
case PRE_GDB:
- if (symbol_exists("idle_pg_table_l3")) {
+ if (symbol_exists("create_pae_xen_mappings") ||
+ symbol_exists("idle_pg_table_l3")) {
machdep->flags |= PAE;
PGDIR_SHIFT = PGDIR_SHIFT_3LEVEL;
PTRS_PER_PTE = PTRS_PER_PTE_3LEVEL;
=== for x86_64 ===
--- defs.h.org 2008-04-17 15:03:14.000000000 +0900
+++ defs.h 2008-04-17 15:41:10.000000000 +0900
@@ -2162,10 +2162,13 @@
#define FILL_PML4_HYPER() { \
if (!machdep->machspec->last_pml4_read) { \
- readmem(symbol_value("idle_pg_table_4"), KVADDR, \
- machdep->machspec->pml4, PAGESIZE(), "idle_pg_table_4", \
+ unsigned long idle_pg_table = \
+ symbol_exists("idle_pg_table_4") ?
symbol_value("idle_pg_table_4") : \
+ symbol_value("idle_pg_table"); \
+ readmem(idle_pg_table, KVADDR, \
+ machdep->machspec->pml4, PAGESIZE(), "idle_pg_table", \
FAULT_ON_ERROR); \
- machdep->machspec->last_pml4_read = symbol_value("idle_pg_table_4");
\
+ machdep->machspec->last_pml4_read = idle_pg_table; \
}\
}
@@ -4081,6 +4084,8 @@
void get_kdump_regs(struct bt_info *, ulong *, ulong *);
void xen_kdump_p2m_mfn(char *);
int is_sadump_xen(void);
+void set_xen_phys_start_mfn(char *);
+ulong xen_phys_start_mfn(void);
/*
* diskdump.c
--- main.c.org 2008-04-17 15:26:37.000000000 +0900
+++ main.c 2008-04-17 15:45:18.000000000 +0900
@@ -48,6 +48,7 @@
{"no_ikconfig", 0, 0, 0},
{"hyper", 0, 0, 0},
{"p2m_mfn", required_argument, 0, 0},
+ {"xen_phys_start_mfn", required_argument, 0, 0},
{"zero_excluded", 0, 0, 0},
{"no_panic", 0, 0, 0},
{"more", 0, 0, 0},
@@ -155,6 +156,9 @@
else if (STREQ(long_options[option_index].name, "p2m_mfn"))
xen_kdump_p2m_mfn(optarg);
+ else if (STREQ(long_options[option_index].name,
"xen_phys_start_mfn"))
+ set_xen_phys_start_mfn(optarg);
+
else if (STREQ(long_options[option_index].name, "zero_excluded"))
*diskdump_flags |= ZERO_EXCLUDED;
--- netdump.c.org 2008-04-17 15:09:06.000000000 +0900
+++ netdump.c 2008-04-17 15:48:44.000000000 +0900
@@ -1521,6 +1521,8 @@
*/
if (!nd->xen_kdump_data->p2m_mfn)
nd->xen_kdump_data->p2m_mfn = *(uptr+(words-1));
+ if (words > 9 && !nd->xen_kdump_data->xen_phys_start_mfn)
+ nd->xen_kdump_data->xen_phys_start_mfn = *(uptr+(words-2));
}
}
break;
@@ -1724,6 +1726,8 @@
*/
if (!nd->xen_kdump_data->p2m_mfn)
nd->xen_kdump_data->p2m_mfn = *(up+(words-1));
+ if (words > 9 && !nd->xen_kdump_data->xen_phys_start_mfn)
+ nd->xen_kdump_data->xen_phys_start_mfn = *(up+(words-2));
}
}
break;
@@ -2312,3 +2316,22 @@
return FALSE;
}
+
+void
+set_xen_phys_start_mfn(char *arg)
+{
+ ulong value;
+ int errflag = 0;
+
+ value = htol(arg, RETURN_ON_ERROR|QUIET, &errflag);
+ if (!errflag)
+ xen_kdump_data.xen_phys_start_mfn = value;
+ else
+ error(WARNING, "invalid xen_phys_start_mfn argument: %s\n", arg);
+}
+
+ulong
+xen_phys_start_mfn(void)
+{
+ return nd->xen_kdump_data->xen_phys_start_mfn;
+}
--- netdump.h.org 2008-04-17 15:38:59.000000000 +0900
+++ netdump.h 2008-04-17 15:39:38.000000000 +0900
@@ -109,6 +109,7 @@
ulong accesses;
int p2m_frames;
ulong *p2m_mfn_frame_list;
+ ulong xen_phys_start_mfn;
};
#define KDUMP_P2M_INIT (0x1)
--- x86_64.c.org 2008-04-17 15:34:32.000000000 +0900
+++ x86_64.c 2008-04-17 15:36:53.000000000 +0900
@@ -1401,6 +1401,10 @@
return FALSE;
if (XEN_HYPER_MODE()) {
+ if (XENTEXT_VIRT_ADDR(kvaddr)) {
+ *paddr = kvaddr - __XEN_VIRT_START + (xen_phys_start_mfn() << PAGESHIFT());
+ return TRUE;
+ }
if (DIRECTMAP_VIRT_ADDR(kvaddr)) {
*paddr = kvaddr - DIRECTMAP_VIRT_START;
return TRUE;
--- xen_hyper_defs.h.org 2008-04-17 15:31:23.000000000 +0900
+++ xen_hyper_defs.h 2008-04-17 15:34:15.000000000 +0900
@@ -64,6 +64,9 @@
#define DIRECTMAP_VIRT_START (0xffff830000000000)
#define DIRECTMAP_VIRT_END (0xffff840000000000)
#define PAGE_OFFSET_XEN_HYPER DIRECTMAP_VIRT_START
+#define __XEN_VIRT_START (0xFFFF828C80000000)
+#define XENTEXT_VIRT_ADDR(vaddr) \
+ (((vaddr) >= __XEN_VIRT_START) && ((vaddr) < DIRECTMAP_VIRT_START))
#endif
#ifdef IA64
=== Xen (explanation purpose) ===
--- include/xen/elfcore.h.org 2008-04-17 14:11:41.000000000 +0900
+++ include/xen/elfcore.h 2008-04-17 14:11:57.000000000 +0900
@@ -66,6 +66,7 @@
unsigned long xen_compile_time;
unsigned long tainted;
#ifdef CONFIG_X86
+ unsigned long xen_phys_start_mfn;
unsigned long dom0_pfn_to_mfn_frame_list_list;
#endif
} crash_xen_info_t;
--- arch/x86/crash.c.org 2008-04-17 14:12:51.000000000 +0900
+++ arch/x86/crash.c 2008-04-17 14:13:13.000000000 +0900
@@ -102,6 +102,7 @@
hvm_disable();
info = kexec_crash_save_info();
+ info->xen_phys_start_mfn = xen_phys_start >> PAGE_SHIFT;
info->dom0_pfn_to_mfn_frame_list_list =
arch_get_pfn_to_mfn_frame_list_list(dom0);
}