The patch titled
kdump/kexec: calculate note size at compile time (update2)
has been removed from the -mm tree. Its filename was
kdump-kexec-calculate-note-size-at-compile-time-update-2.patch
This patch was dropped because it was folded into kdump-kexec-calculate-note-size-at-compile-time.patch
------------------------------------------------------
Subject: kdump/kexec: calculate note size at compile time (update2)
From: Simon Horman <horms@xxxxxxxxxxxx>
Currently the size of the per-cpu region reserved to save crash notes is
set by the per-architecture value MAX_NOTE_BYTES. Which in turn is
currently set to 1024 on all supported architectures.
While testing ia64 I recently discovered that this value is in fact too
small. The particular setup I was using actually needs 1172 bytes. This
lead to very tedious failure mode where the tail of one elf note would
overwrite the head of another if they ended up being alocated sequentially
by kmalloc, which was often the case.
It seems to me that a far better approach is to caclculate the size that
the area needs to be. This patch does just that.
If a simpler stop-gap patch for ia64 to be squeezed into 2.6.21(.X) is
needed then this should be as easy as making MAX_NOTE_BYTES larger in
arch/asm-ia64/kexec.h. Perhaps 2048 would be a good choice. However, I
think that the approach in this patch is a much more robust idea.
Signed-off-by: Simon Horman <horms@xxxxxxxxxxxx>
Acked-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/ia64/kernel/crash.c | 2 +-
include/linux/kexec.h | 21 +++++++++++----------
kernel/kexec.c | 4 ++--
3 files changed, 14 insertions(+), 13 deletions(-)
diff -puN arch/ia64/kernel/crash.c~kdump-kexec-calculate-note-size-at-compile-time-update-2 arch/ia64/kernel/crash.c
--- a/arch/ia64/kernel/crash.c~kdump-kexec-calculate-note-size-at-compile-time-update-2
+++ a/arch/ia64/kernel/crash.c
@@ -74,7 +74,7 @@ crash_save_this_cpu(void)
buf = (u64 *) per_cpu_ptr(crash_notes, cpu);
if (!buf)
return;
- buf = append_elf_note(buf, KEXEC_NOTE_NAME, NT_PRSTATUS, prstatus,
+ buf = append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_PRSTATUS, prstatus,
sizeof(*prstatus));
final_note(buf);
}
diff -puN include/linux/kexec.h~kdump-kexec-calculate-note-size-at-compile-time-update-2 include/linux/kexec.h
--- a/include/linux/kexec.h~kdump-kexec-calculate-note-size-at-compile-time-update-2
+++ a/include/linux/kexec.h
@@ -33,17 +33,18 @@
#error KEXEC_ARCH not defined
#endif
-#define KEXEC_NOTE_NAME "CORE"
#define KEXEC_NOTE_HEAD_BYTES ALIGN(sizeof(struct elf_note), 4)
-#define KEXEC_NOTE_NAME_BYTES ALIGN(sizeof("CORE"), 4) /* N.B: Includes '\0' */
-#define KEXEC_NOTE_DESC_BYTES ALIGN(sizeof(struct elf_prstatus), 4)
-/* The notes are read and combined by the code in vmcore.c running
- * in the second-kernel after kdump is performed. This code
- * expects the notes area to be a list of notes, terminated
- * by a "NULL" note header. The "* 2" below is to provide space
- * for the terminating note header */
-#define KEXEC_NOTE_BYTES ( (KEXEC_NOTE_HEAD_BYTES * 2) + \
- KEXEC_NOTE_NAME_BYTES + KEXEC_NOTE_DESC_BYTES )
+#define KEXEC_CORE_NOTE_NAME "CORE"
+#define KEXEC_CORE_NOTE_NAME_BYTES ALIGN(sizeof(KEXEC_CORE_NOTE_NAME), 4)
+#define KEXEC_CORE_NOTE_DESC_BYTES ALIGN(sizeof(struct elf_prstatus), 4)
+/*
+ * The per-cpu notes area is a list of notes terminated by a "NULL"
+ * note header. For kdump, the code in vmcore.c runs in the context
+ * of the second kernel to combine them into one note.
+ */
+#define KEXEC_NOTE_BYTES ( (KEXEC_NOTE_HEAD_BYTES * 2) + \
+ KEXEC_CORE_NOTE_NAME_BYTES + \
+ KEXEC_CORE_NOTE_DESC_BYTES )
/*
* This structure is used to hold the arguments that are used when loading
diff -puN kernel/kexec.c~kdump-kexec-calculate-note-size-at-compile-time-update-2 kernel/kexec.c
--- a/kernel/kexec.c~kdump-kexec-calculate-note-size-at-compile-time-update-2
+++ a/kernel/kexec.c
@@ -1118,8 +1118,8 @@ void crash_save_cpu(struct pt_regs *regs
memset(&prstatus, 0, sizeof(prstatus));
prstatus.pr_pid = current->pid;
elf_core_copy_regs(&prstatus.pr_reg, regs);
- buf = append_elf_note(buf, KEXEC_NOTE_NAME, NT_PRSTATUS, &prstatus,
- sizeof(prstatus));
+ buf = append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_PRSTATUS,
+ &prstatus, sizeof(prstatus));
final_note(buf);
}
_
Patches currently in -mm which might be from horms@xxxxxxxxxxxx are
origin.patch
git-ia64.patch
git-scsi-misc.patch
kdump-kexec-calculate-note-size-at-compile-time.patch
kdump-kexec-calculate-note-size-at-compile-time-update-2.patch
use-menuconfig-objects-ipvs.patch
-
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