kdump/kexec: calculate note size at compile time (6672f76a) · Commits · 戴 / test

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. Acked-by:

Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by:

Simon Horman <horms@verge.net.au> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

arch/ia64/kernel/crash.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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, "CORE", NT_PRSTATUS, prstatus,
		buf = append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_PRSTATUS, prstatus,
		sizeof(*prstatus));
		final_note(buf);
		}

include/asm-arm/kexec.h

+0 −2

Original line number	Diff line number	Diff line
		@@ -16,8 +16,6 @@

		#ifndef __ASSEMBLY__

		#define MAX_NOTE_BYTES 1024

		struct kimage;
		/* Provide a dummy definition to avoid build failures. */
		static inline void crash_setup_regs(struct pt_regs *newregs,

include/asm-i386/kexec.h

+0 −2

Original line number	Diff line number	Diff line
		@@ -45,8 +45,6 @@
		/* We can also handle crash dumps from 64 bit kernel. */
		#define vmcore_elf_check_arch_cross(x) ((x)->e_machine == EM_X86_64)

		#define MAX_NOTE_BYTES 1024

		/* CPU does not save ss and esp on stack if execution is already
		* running in kernel mode at the time of NMI occurrence. This code
		* fixes it.

include/asm-ia64/kexec.h

+0 −2

Original line number	Diff line number	Diff line
		@@ -14,8 +14,6 @@
		/* The native architecture */
		#define KEXEC_ARCH KEXEC_ARCH_IA_64

		#define MAX_NOTE_BYTES 1024

		#define kexec_flush_icache_page(page) do { \
		unsigned long page_addr = (unsigned long)page_address(page); \
		flush_icache_range(page_addr, page_addr + PAGE_SIZE); \

include/asm-mips/kexec.h

+0 −2

Original line number	Diff line number	Diff line
		@@ -21,8 +21,6 @@
		/* The native architecture */
		#define KEXEC_ARCH KEXEC_ARCH_MIPS

		#define MAX_NOTE_BYTES 1024

		static inline void crash_setup_regs(struct pt_regs *newregs,
		struct pt_regs *oldregs)
		{

Admin message