From 6672f76a5a1878d42264c1deba8f1ab52b4618d9 Mon Sep 17 00:00:00 2001 From: Simon Horman Date: Tue, 8 May 2007 00:28:22 -0700 Subject: [PATCH] kdump/kexec: calculate note size at compile time 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 Signed-off-by: Simon Horman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/ia64/kernel/crash.c | 2 +- include/asm-arm/kexec.h | 2 -- include/asm-i386/kexec.h | 2 -- include/asm-ia64/kexec.h | 2 -- include/asm-mips/kexec.h | 2 -- include/asm-powerpc/kexec.h | 2 -- include/asm-s390/kexec.h | 2 -- include/asm-sh/kexec.h | 2 -- include/asm-x86_64/kexec.h | 2 -- include/linux/kexec.h | 17 ++++++++++++++++- kernel/kexec.c | 4 ++-- 11 files changed, 19 insertions(+), 20 deletions(-) diff --git a/arch/ia64/kernel/crash.c b/arch/ia64/kernel/crash.c index 3d51a3f770..aeb79fb28f 100644 --- a/arch/ia64/kernel/crash.c +++ b/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, "CORE", NT_PRSTATUS, prstatus, + buf = append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_PRSTATUS, prstatus, sizeof(*prstatus)); final_note(buf); } diff --git a/include/asm-arm/kexec.h b/include/asm-arm/kexec.h index 8c1c6162a8..b5b030ef63 100644 --- a/include/asm-arm/kexec.h +++ b/include/asm-arm/kexec.h @@ -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, diff --git a/include/asm-i386/kexec.h b/include/asm-i386/kexec.h index bcb5b21de2..4b9dc9e6b7 100644 --- a/include/asm-i386/kexec.h +++ b/include/asm-i386/kexec.h @@ -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. diff --git a/include/asm-ia64/kexec.h b/include/asm-ia64/kexec.h index 41299ddfee..541be835fc 100644 --- a/include/asm-ia64/kexec.h +++ b/include/asm-ia64/kexec.h @@ -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); \ diff --git a/include/asm-mips/kexec.h b/include/asm-mips/kexec.h index b25267ebcb..cdbab43b7d 100644 --- a/include/asm-mips/kexec.h +++ b/include/asm-mips/kexec.h @@ -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) { diff --git a/include/asm-powerpc/kexec.h b/include/asm-powerpc/kexec.h index 11cbdf81fd..b6f817b8ba 100644 --- a/include/asm-powerpc/kexec.h +++ b/include/asm-powerpc/kexec.h @@ -108,8 +108,6 @@ static inline void crash_setup_regs(struct pt_regs *newregs, struct pt_regs *oldregs) { } #endif /* !__powerpc64 __ */ -#define MAX_NOTE_BYTES 1024 - extern void kexec_smp_wait(void); /* get and clear naca physid, wait for master to copy new code to 0 */ extern int crashing_cpu; diff --git a/include/asm-s390/kexec.h b/include/asm-s390/kexec.h index 9c35c8ad1a..7592af708b 100644 --- a/include/asm-s390/kexec.h +++ b/include/asm-s390/kexec.h @@ -34,8 +34,6 @@ /* The native architecture */ #define KEXEC_ARCH KEXEC_ARCH_S390 -#define MAX_NOTE_BYTES 1024 - /* Provide a dummy definition to avoid build failures. */ static inline void crash_setup_regs(struct pt_regs *newregs, struct pt_regs *oldregs) { } diff --git a/include/asm-sh/kexec.h b/include/asm-sh/kexec.h index da36a75486..00f4260ef0 100644 --- a/include/asm-sh/kexec.h +++ b/include/asm-sh/kexec.h @@ -26,8 +26,6 @@ /* The native architecture */ #define KEXEC_ARCH KEXEC_ARCH_SH -#define MAX_NOTE_BYTES 1024 - static inline void crash_setup_regs(struct pt_regs *newregs, struct pt_regs *oldregs) { diff --git a/include/asm-x86_64/kexec.h b/include/asm-x86_64/kexec.h index 5fab957e10..738e581b67 100644 --- a/include/asm-x86_64/kexec.h +++ b/include/asm-x86_64/kexec.h @@ -48,8 +48,6 @@ /* The native architecture */ #define KEXEC_ARCH KEXEC_ARCH_X86_64 -#define MAX_NOTE_BYTES 1024 - /* * Saving the registers of the cpu on which panic occured in * crash_kexec to save a valid sp. The registers of other cpus diff --git a/include/linux/kexec.h b/include/linux/kexec.h index 696e5ec63f..8c2c7fcd58 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -7,6 +7,8 @@ #include #include #include +#include +#include #include /* Verify architecture specific macros are defined */ @@ -31,6 +33,19 @@ #error KEXEC_ARCH not defined #endif +#define KEXEC_NOTE_HEAD_BYTES ALIGN(sizeof(struct elf_note), 4) +#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 * kernel binaries. @@ -136,7 +151,7 @@ extern struct kimage *kexec_crash_image; /* Location of a reserved region to hold the crash kernel. */ extern struct resource crashk_res; -typedef u32 note_buf_t[MAX_NOTE_BYTES/4]; +typedef u32 note_buf_t[KEXEC_NOTE_BYTES/4]; extern note_buf_t *crash_notes; diff --git a/kernel/kexec.c b/kernel/kexec.c index 2a59c8a01a..25db14b89e 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -1118,8 +1118,8 @@ void crash_save_cpu(struct pt_regs *regs, int cpu) memset(&prstatus, 0, sizeof(prstatus)); prstatus.pr_pid = current->pid; elf_core_copy_regs(&prstatus.pr_reg, regs); - buf = append_elf_note(buf, "CORE", NT_PRSTATUS, &prstatus, - sizeof(prstatus)); + buf = append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_PRSTATUS, + &prstatus, sizeof(prstatus)); final_note(buf); } -- 2.39.5