[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: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/linux/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;