Commit cc571658 authored by Vivek Goyal's avatar Vivek Goyal Committed by Linus Torvalds
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[PATCH] kdump: dynamic per cpu allocation of memory for saving cpu registers



- 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: default avatarVivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 82409411
......@@ -25,7 +25,6 @@
#include <mach_ipi.h>
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 pt_regs *regs, int cpu)
* 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);
......
......@@ -28,12 +28,6 @@ typedef NORET_TYPE void (*relocate_new_kernel_t)(
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)
......
......@@ -10,8 +10,6 @@
#include <linux/threads.h>
#include <linux/kexec.h>
note_buf_t crash_notes[NR_CPUS];
void machine_crash_shutdown(struct pt_regs *regs)
{
}
......@@ -19,8 +19,6 @@
#include <asm/nmi.h>
#include <asm/hw_irq.h>
note_buf_t crash_notes[NR_CPUS];
void machine_crash_shutdown(struct pt_regs *regs)
{
/* This function is only called after the system
......
......@@ -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 */
......@@ -38,9 +38,6 @@
#ifdef CONFIG_KEXEC
#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
......
......@@ -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 */
......@@ -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 */
......@@ -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;
......
......@@ -26,6 +26,9 @@
#include <asm/system.h>
#include <asm/semaphore.h>
/* 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)
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