* Re: FYI: x86_64 bug when using gdb with vmcore
2010-02-05 16:53 ` FYI: x86_64 bug when using gdb with vmcore Dave Anderson
@ 2010-02-17 7:18 ` Simon Horman
0 siblings, 0 replies; 4+ messages in thread
From: Simon Horman @ 2010-02-17 7:18 UTC (permalink / raw)
To: Dave Anderson; +Cc: kexec
On Fri, Feb 05, 2010 at 11:53:18AM -0500, Dave Anderson wrote:
>
> The kexec/arch/x86_64/crashdump-x86_64.h file contains a
> stale PAGE_OFFSET value. In 2.6.27 it was changed from
> 0xffff810000000000UL to 0xffff880000000000UL. This is
> only a problem when using gdb with the vmlinux/vmcore
> pair, because gdb relies upon the PT_LOAD segment's p_vaddr
> values in the ELF header to be correct.
>
> Anyway, in the RHEL6 kexec-tools, this simple patch
> was made:
>
> -#define PAGE_OFFSET 0xffff810000000000UL
> +#define PAGE_OFFSET 0xffff880000000000UL
>
> which is OK since the RHEL6 version of kexec-tools
> will only be used with RHEL6 kernels.
>
> But for backwards compatibility, the better way to do
> it would be to check the utsname of the running kernel,
> and use the right value.
>
> But again, this is only required for gdb usage. The
> crash utility (and makedumpfile) make kernel version checks
> to determine which x86_64 PAGE_OFFSET value is applicable,
> and don't rely on the ELF header p_vaddr values for
> the unity-mapped regions.
Hi Dave,
Something like this?
----------------------------------------------------------------------
x86_64: use correct PAGE_OFFSET
This fixes a bug when using gdb with vmcore
as explained by Dave Anderson:
The kexec/arch/x86_64/crashdump-x86_64.h file contains a
stale PAGE_OFFSET value. In 2.6.27 it was changed from
0xffff810000000000UL to 0xffff880000000000UL. This is
only a problem when using gdb with the vmlinux/vmcore
pair, because gdb relies upon the PT_LOAD segment's p_vaddr
values in the ELF header to be correct.
Cc: Dave Anderson <anderson@redhat.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
Index: kexec-tools/kexec/arch/x86_64/crashdump-x86_64.c
===================================================================
--- kexec-tools.orig/kexec/arch/x86_64/crashdump-x86_64.c 2010-02-17 16:04:18.000000000 +1100
+++ kexec-tools/kexec/arch/x86_64/crashdump-x86_64.c 2010-02-17 16:18:42.000000000 +1100
@@ -36,15 +36,6 @@
#include "crashdump-x86_64.h"
#include <x86/x86-linux.h>
-static struct crash_elf_info elf_info =
-{
- class: ELFCLASS64,
- data: ELFDATA2LSB,
- machine: EM_X86_64,
- backup_src_start: BACKUP_SRC_START,
- backup_src_end: BACKUP_SRC_END,
- page_offset: PAGE_OFFSET,
-};
/* Forward Declaration. */
static int exclude_region(int *nr_ranges, uint64_t start, uint64_t end);
@@ -604,6 +595,16 @@ int load_crashdump_segments(struct kexec
int nr_ranges, align = 1024, i;
struct memory_range *mem_range, *memmap_p;
+ struct crash_elf_info elf_info =
+ {
+ class: ELFCLASS64,
+ data: ELFDATA2LSB,
+ machine: EM_X86_64,
+ backup_src_start: BACKUP_SRC_START,
+ backup_src_end: BACKUP_SRC_END,
+ page_offset: page_offset,
+ };
+
if (get_kernel_paddr(info))
return -1;
Index: kexec-tools/kexec/arch/x86_64/crashdump-x86_64.h
===================================================================
--- kexec-tools.orig/kexec/arch/x86_64/crashdump-x86_64.h 2010-02-17 16:04:18.000000000 +1100
+++ kexec-tools/kexec/arch/x86_64/crashdump-x86_64.h 2010-02-17 17:41:10.000000000 +1100
@@ -1,12 +1,16 @@
#ifndef CRASHDUMP_X86_64_H
#define CRASHDUMP_X86_64_H
+#include "../../kexec.h"
+
int load_crashdump_segments(struct kexec_info *info, char *mod_cmdline,
unsigned long max_addr, unsigned long min_base);
#define __START_KERNEL_map 0xffffffff80000000UL
-#define PAGE_OFFSET 0xffff810000000000UL
-#define __pa(x) (((unsigned long)(x)>=__START_KERNEL_map)?(unsigned long)(x) - (unsigned long)__START_KERNEL_map:(unsigned long)(x) - PAGE_OFFSET)
+
+extern unsigned long page_offset;
+
+#define __pa(x) (((unsigned long)(x)>=__START_KERNEL_map)?(unsigned long)(x) - (unsigned long)__START_KERNEL_map:(unsigned long)(x) - page_offset)
#define MAXMEM 0x3fffffffffffUL
Index: kexec-tools/kexec/kexec.c
===================================================================
--- kexec-tools.orig/kexec/kexec.c 2010-02-17 16:04:18.000000000 +1100
+++ kexec-tools/kexec/kexec.c 2010-02-17 16:11:06.000000000 +1100
@@ -1041,6 +1041,8 @@ int main(int argc, char *argv[])
};
static const char short_options[] = KEXEC_OPT_STR;
+ arch_init();
+
opterr = 0; /* Don't complain about unrecognized options here */
while ((opt = getopt_long(argc, argv, short_options,
options, 0)) != -1) {
Index: kexec-tools/kexec/Makefile
===================================================================
--- kexec-tools.orig/kexec/Makefile 2010-02-17 16:06:32.000000000 +1100
+++ kexec-tools/kexec/Makefile 2010-02-17 16:11:11.000000000 +1100
@@ -44,6 +44,8 @@ $(ARCH)_ADD_BUFFER = kexec/add_buffer.c
KEXEC_SRCS += $($(ARCH)_ADD_BUFFER)
$(ARCH)_ARCH_REUSE_INITRD = kexec/arch_reuse_initrd.c
KEXEC_SRCS += $($(ARCH)_ARCH_REUSE_INITRD)
+$(ARCH)_ARCH_INIT = kexec/arch_init.c
+KEXEC_SRCS += $($(ARCH)_ARCH_INIT)
include $(srcdir)/kexec/arch/alpha/Makefile
include $(srcdir)/kexec/arch/arm/Makefile
Index: kexec-tools/kexec/arch/x86_64/Makefile
===================================================================
--- kexec-tools.orig/kexec/arch/x86_64/Makefile 2010-02-17 17:33:59.000000000 +1100
+++ kexec-tools/kexec/arch/x86_64/Makefile 2010-02-17 17:36:22.000000000 +1100
@@ -13,6 +13,8 @@ x86_64_KEXEC_SRCS += kexec/arch/x86_64/k
x86_64_KEXEC_SRCS += kexec/arch/x86_64/kexec-elf-x86_64.c
x86_64_KEXEC_SRCS += kexec/arch/x86_64/kexec-elf-rel-x86_64.c
+x86_64_ARCH_INIT = kexec/arch/x86_64/arch_init.c
+
dist += kexec/arch/x86_64/Makefile $(x86_64_KEXEC_SRCS) \
kexec/arch/x86_64/kexec-x86_64.h kexec/arch/x86_64/crashdump-x86_64.h \
kexec/arch/x86_64/include/arch/options.h
Index: kexec-tools/kexec/arch/x86_64/arch_init.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ kexec-tools/kexec/arch/x86_64/arch_init.c 2010-02-17 18:06:52.000000000 +1100
@@ -0,0 +1,83 @@
+#include <errno.h>
+#include <string.h>
+#include <sys/utsname.h>
+#include <stdlib.h>
+#include <limits.h>
+#include <stdio.h>
+
+#include "crashdump-x86_64.h"
+
+#define KERNEL_VERSION(major, minor, patch) \
+ (((major) << 16) | ((minor) << 8) | patch)
+
+long kernel_version(void)
+{
+ struct utsname utsname;
+ unsigned long major, minor, patch;
+ char *p;
+
+ if (uname(&utsname) < 0) {
+ fprintf(stderr, "uname failed: %s\n", strerror(errno));
+ return -1;
+ }
+
+ p = utsname.release;
+ major = strtoul(p, &p, 10);
+ if (major == ULONG_MAX) {
+ fprintf(stderr, "strtoul failed: %s\n", strerror(errno));
+ return -1;
+ }
+
+ if (*p++ != '.') {
+ fprintf(stderr, "Unsupported utsname.release: %s\n",
+ utsname.release);
+ return -1;
+ }
+
+ minor = strtoul(p, &p, 10);
+ if (major == ULONG_MAX) {
+ fprintf(stderr, "strtoul failed: %s\n", strerror(errno));
+ return -1;
+ }
+
+ if (*p++ != '.') {
+ fprintf(stderr, "Unsupported utsname.release: %s\n",
+ utsname.release);
+ return -1;
+ }
+
+ patch = strtoul(p, &p, 10);
+ if (major == ULONG_MAX) {
+ fprintf(stderr, "strtoul failed: %s\n", strerror(errno));
+ return -1;
+ }
+
+ if (major >= 256 || minor >= 256 || patch >= 256) {
+ fprintf(stderr, "Unsupported utsname.release: %s\n",
+ utsname.release);
+ return -1;
+ }
+
+ return KERNEL_VERSION(major, minor, patch);
+}
+
+#define PAGE_OFFSET_PRE_2_6_27 0xffff810000000000UL
+#define PAGE_OFFSET 0xffff880000000000UL
+
+unsigned long page_offset;
+
+int arch_init(void)
+{
+ int kv;
+
+ kv = kernel_version();
+ if (kv < 0)
+ return -1;
+
+ if (kv < KERNEL_VERSION(2, 4, 27))
+ page_offset = PAGE_OFFSET_PRE_2_6_27;
+ else
+ page_offset = PAGE_OFFSET;
+
+ return 0;
+}
Index: kexec-tools/kexec/arch_init.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ kexec-tools/kexec/arch_init.c 2010-02-17 16:12:14.000000000 +1100
@@ -0,0 +1,4 @@
+int arch_init(void)
+{
+ return 0;
+}
Index: kexec-tools/kexec/kexec.h
===================================================================
--- kexec-tools.orig/kexec/kexec.h 2010-02-17 16:12:44.000000000 +1100
+++ kexec-tools/kexec/kexec.h 2010-02-17 16:13:03.000000000 +1100
@@ -249,6 +249,8 @@ int kexec_iomem_for_each_line(char *matc
int parse_iomem_single(char *str, uint64_t *start, uint64_t *end);
const char * proc_iomem(void);
+int arch_init(void);
+
extern int add_backup_segments(struct kexec_info *info,
unsigned long backup_base,
unsigned long backup_size);
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