From: Vivek Goyal - In case of system crash, current state of cpu registers is saved in memory in elf note format. So far memory for storing elf notes was being allocated statically for NR_CPUS. - This patch introduces dynamic allocation of memory for storing elf notes. It uses alloc_percpu() interface. This should lead to better memory usage. - Introduced based on Andi Kleen's and Eric W. Biederman's suggestions. - This patch also moves memory allocation for elf notes from architecture dependent portion to architecture independent portion. Now crash_notes is architecture independent. The whole idea is that size of memory to be allocated per cpu (MAX_NOTE_BYTES) can be architecture dependent and allocation of this memory can be architecture independent. Signed-off-by: Vivek Goyal Signed-off-by: Andrew Morton --- arch/i386/kernel/crash.c | 5 +++-- arch/ppc/kernel/machine_kexec.c | 6 ------ arch/s390/kernel/crash.c | 2 -- arch/x86_64/kernel/crash.c | 2 -- include/asm-i386/kexec.h | 3 --- include/asm-powerpc/kexec.h | 3 --- include/asm-s390/kexec.h | 3 --- include/asm-x86_64/kexec.h | 3 --- include/linux/kexec.h | 2 ++ kernel/kexec.c | 16 ++++++++++++++++ powerpc/kernel/machine_kexec.c | 0 11 files changed, 21 insertions(+), 24 deletions(-) diff -puN arch/i386/kernel/crash.c~kdump-dynamic-per-cpu-allocation-of-memory-for-saving-cpu-registers arch/i386/kernel/crash.c --- 25/arch/i386/kernel/crash.c~kdump-dynamic-per-cpu-allocation-of-memory-for-saving-cpu-registers Thu Nov 17 14:21:02 2005 +++ 25-akpm/arch/i386/kernel/crash.c Thu Nov 17 14:21:02 2005 @@ -25,7 +25,6 @@ #include -note_buf_t crash_notes[NR_CPUS]; /* This keeps a track of which one is crashing cpu. */ static int crashing_cpu; @@ -72,7 +71,9 @@ static void crash_save_this_cpu(struct p * squirrelled away. ELF notes happen to provide * all of that that no need to invent something new. */ - buf = &crash_notes[cpu][0]; + buf = (u32*)per_cpu_ptr(crash_notes, cpu); + if (!buf) + return; memset(&prstatus, 0, sizeof(prstatus)); prstatus.pr_pid = current->pid; elf_core_copy_regs(&prstatus.pr_reg, regs); diff -puN arch/powerpc/kernel/machine_kexec.c~kdump-dynamic-per-cpu-allocation-of-memory-for-saving-cpu-registers arch/powerpc/kernel/machine_kexec.c diff -puN arch/ppc/kernel/machine_kexec.c~kdump-dynamic-per-cpu-allocation-of-memory-for-saving-cpu-registers arch/ppc/kernel/machine_kexec.c --- 25/arch/ppc/kernel/machine_kexec.c~kdump-dynamic-per-cpu-allocation-of-memory-for-saving-cpu-registers Thu Nov 17 14:21:02 2005 +++ 25-akpm/arch/ppc/kernel/machine_kexec.c Thu Nov 17 14:21:02 2005 @@ -28,12 +28,6 @@ typedef NORET_TYPE void (*relocate_new_k const extern unsigned char relocate_new_kernel[]; const extern unsigned int relocate_new_kernel_size; -/* - * Provide a dummy crash_notes definition while crash dump arrives to ppc. - * This prevents breakage of crash_notes attribute in kernel/ksysfs.c. - */ -note_buf_t crash_notes[NR_CPUS]; - void machine_shutdown(void) { if (ppc_md.machine_shutdown) diff -puN arch/s390/kernel/crash.c~kdump-dynamic-per-cpu-allocation-of-memory-for-saving-cpu-registers arch/s390/kernel/crash.c --- 25/arch/s390/kernel/crash.c~kdump-dynamic-per-cpu-allocation-of-memory-for-saving-cpu-registers Thu Nov 17 14:21:02 2005 +++ 25-akpm/arch/s390/kernel/crash.c Thu Nov 17 14:21:02 2005 @@ -10,8 +10,6 @@ #include #include -note_buf_t crash_notes[NR_CPUS]; - void machine_crash_shutdown(struct pt_regs *regs) { } diff -puN arch/x86_64/kernel/crash.c~kdump-dynamic-per-cpu-allocation-of-memory-for-saving-cpu-registers arch/x86_64/kernel/crash.c --- 25/arch/x86_64/kernel/crash.c~kdump-dynamic-per-cpu-allocation-of-memory-for-saving-cpu-registers Thu Nov 17 14:21:02 2005 +++ 25-akpm/arch/x86_64/kernel/crash.c Thu Nov 17 14:21:02 2005 @@ -19,8 +19,6 @@ #include #include -note_buf_t crash_notes[NR_CPUS]; - void machine_crash_shutdown(struct pt_regs *regs) { /* This function is only called after the system diff -puN include/asm-i386/kexec.h~kdump-dynamic-per-cpu-allocation-of-memory-for-saving-cpu-registers include/asm-i386/kexec.h --- 25/include/asm-i386/kexec.h~kdump-dynamic-per-cpu-allocation-of-memory-for-saving-cpu-registers Thu Nov 17 14:21:02 2005 +++ 25-akpm/include/asm-i386/kexec.h Thu Nov 17 14:21:02 2005 @@ -26,8 +26,5 @@ #define KEXEC_ARCH KEXEC_ARCH_386 #define MAX_NOTE_BYTES 1024 -typedef u32 note_buf_t[MAX_NOTE_BYTES/4]; - -extern note_buf_t crash_notes[]; #endif /* _I386_KEXEC_H */ diff -puN include/asm-powerpc/kexec.h~kdump-dynamic-per-cpu-allocation-of-memory-for-saving-cpu-registers include/asm-powerpc/kexec.h --- 25/include/asm-powerpc/kexec.h~kdump-dynamic-per-cpu-allocation-of-memory-for-saving-cpu-registers Thu Nov 17 14:21:02 2005 +++ 25-akpm/include/asm-powerpc/kexec.h Thu Nov 17 14:21:02 2005 @@ -33,9 +33,6 @@ #ifndef __ASSEMBLY__ #define MAX_NOTE_BYTES 1024 -typedef u32 note_buf_t[MAX_NOTE_BYTES / sizeof(u32)]; - -extern note_buf_t crash_notes[]; #ifdef __powerpc64__ extern void kexec_smp_wait(void); /* get and clear naca physid, wait for diff -puN include/asm-s390/kexec.h~kdump-dynamic-per-cpu-allocation-of-memory-for-saving-cpu-registers include/asm-s390/kexec.h --- 25/include/asm-s390/kexec.h~kdump-dynamic-per-cpu-allocation-of-memory-for-saving-cpu-registers Thu Nov 17 14:21:02 2005 +++ 25-akpm/include/asm-s390/kexec.h Thu Nov 17 14:21:02 2005 @@ -35,8 +35,5 @@ #define KEXEC_ARCH KEXEC_ARCH_S390 #define MAX_NOTE_BYTES 1024 -typedef u32 note_buf_t[MAX_NOTE_BYTES/4]; - -extern note_buf_t crash_notes[]; #endif /*_S390_KEXEC_H */ diff -puN include/asm-x86_64/kexec.h~kdump-dynamic-per-cpu-allocation-of-memory-for-saving-cpu-registers include/asm-x86_64/kexec.h --- 25/include/asm-x86_64/kexec.h~kdump-dynamic-per-cpu-allocation-of-memory-for-saving-cpu-registers Thu Nov 17 14:21:02 2005 +++ 25-akpm/include/asm-x86_64/kexec.h Thu Nov 17 14:21:02 2005 @@ -26,8 +26,5 @@ #define KEXEC_ARCH KEXEC_ARCH_X86_64 #define MAX_NOTE_BYTES 1024 -typedef u32 note_buf_t[MAX_NOTE_BYTES/4]; - -extern note_buf_t crash_notes[]; #endif /* _X86_64_KEXEC_H */ diff -puN include/linux/kexec.h~kdump-dynamic-per-cpu-allocation-of-memory-for-saving-cpu-registers include/linux/kexec.h --- 25/include/linux/kexec.h~kdump-dynamic-per-cpu-allocation-of-memory-for-saving-cpu-registers Thu Nov 17 14:21:02 2005 +++ 25-akpm/include/linux/kexec.h Thu Nov 17 14:21:02 2005 @@ -125,6 +125,8 @@ extern struct kimage *kexec_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]; +extern note_buf_t *crash_notes; #else /* !CONFIG_KEXEC */ struct pt_regs; diff -puN kernel/kexec.c~kdump-dynamic-per-cpu-allocation-of-memory-for-saving-cpu-registers kernel/kexec.c --- 25/kernel/kexec.c~kdump-dynamic-per-cpu-allocation-of-memory-for-saving-cpu-registers Thu Nov 17 14:21:02 2005 +++ 25-akpm/kernel/kexec.c Thu Nov 17 14:21:02 2005 @@ -26,6 +26,9 @@ #include #include +/* Per cpu memory for storing cpu states in case of system crash. */ +note_buf_t* crash_notes; + /* Location of the reserved area for the crash kernel */ struct resource crashk_res = { .name = "Crash kernel", @@ -1060,3 +1063,16 @@ void crash_kexec(struct pt_regs *regs) xchg(&kexec_lock, 0); } } + +static int __init crash_notes_memory_init(void) +{ + /* Allocate memory for saving cpu registers. */ + crash_notes = alloc_percpu(note_buf_t); + if (!crash_notes) { + printk("Kexec: Memory allocation for saving cpu register" + " states failed\n"); + return -ENOMEM; + } + return 0; +} +module_init(crash_notes_memory_init) _