kexec-tools: x86_64 read kernel vaddr and size from /proc/kcore

o With relocatable kernel in picture, the kernel text map offset
  (__START_KERNEL_map) is no longer constant. It depends on where kernel
  is loaded.

o Now /proc/kcore is read to determine the virtual address the kernel
  is mapped at and /porc/iomem is read for determining the physical
  address where kernel is loaded at. This information is enough to
  create to fill virtual address and phy addr info for elf header
  mapping kernel text and data.

o Virtual address for kernel text are needed by gdb as well as crash to
  retrieve the meaningful data from core file.

o This patch requires "elf note memsz" fix in the kernel. Currently
  that fix is in -mm tree. It will still work with older kernels. It will
  display the warning messages (/proc/kcore could not be parsed) and hardcode
  the kernel virtual address and size.

Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Simon Horman <horms@verge.net.au>

1 files changed, 4 insertions, 0 deletions

diff --git a/kexec/kexec.h b/kexec/kexec.h
index 57fca7d..1cee900 100644
--- a/kexec/kexec.h
+++ b/kexec/kexec.h
@@ -116,6 +116,9 @@ struct kexec_info {
 	struct mem_ehdr rhdr;
 	unsigned long backup_start;
 	unsigned long kexec_flags;
+	unsigned long kern_vaddr_start;
+	unsigned long kern_paddr_start;
+	unsigned long kern_size;
 };
 
 void usage(void);
@@ -177,6 +180,7 @@ extern void die(char *fmt, ...);
 extern void *xmalloc(size_t size);
 extern void *xrealloc(void *ptr, size_t size);
 extern char *slurp_file(const char *filename, off_t *r_size);
+extern char *slurp_file_len(const char *filename, off_t size);
 extern char *slurp_decompress_file(const char *filename, off_t *r_size);
 extern void add_segment(struct kexec_info *info,
 	const void *buf, size_t bufsz, unsigned long base, size_t memsz);