[tip:x86/urgent] x86, kaslr: export offset in VMCOREINFO ELF notes

[tip-bot for Eugene Surovegin <tipbot@zytor.com>]

Commit-ID:  b6085a865762236bb84934161273cdac6dd11c2d
Gitweb:     http://git.kernel.org/tip/b6085a865762236bb84934161273cdac6dd11c2d
Author:     Eugene Surovegin <surovegin@google.com>
AuthorDate: Thu, 23 Jan 2014 09:31:20 -0800
Committer:  H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Tue, 25 Feb 2014 16:57:47 -0800

x86, kaslr: export offset in VMCOREINFO ELF notes

Include kASLR offset in VMCOREINFO ELF notes to assist in debugging.

[ hpa: pushing this for v3.14 to avoid having a kernel version with
  kASLR where we can't debug output. ]

Signed-off-by: Eugene Surovegin <surovegin@google.com>
Link: http://lkml.kernel.org/r/20140123173120.GA25474@www.outflux.net
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
---
 arch/x86/kernel/machine_kexec_64.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index 4eabc16..679cef0 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -279,5 +279,7 @@ void arch_crash_save_vmcoreinfo(void)
 	VMCOREINFO_SYMBOL(node_data);
 	VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
 #endif
+	vmcoreinfo_append_str("KERNELOFFSET=%lx\n",
+			      (unsigned long)&_text - __START_KERNEL);
 }