[tip:x86/urgent] x86, 32-bit: fix kernel_trap_sp()

[tip-bot for Masami Hiramatsu <mhiramat@redhat.com>]

Commit-ID:  11d0f25f06fb67e707e6ed4bf9967b859e403639
Gitweb:     http://git.kernel.org/tip/11d0f25f06fb67e707e6ed4bf9967b859e403639
Author:     Masami Hiramatsu <mhiramat@redhat.com>
AuthorDate: Mon, 11 May 2009 17:03:00 -0400
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Mon, 11 May 2009 23:49:17 +0200

x86, 32-bit: fix kernel_trap_sp()

Use &regs->sp instead of regs for getting the top of stack in kernel mode.
(on x86-64, regs->sp always points the top of stack)

[ Impact: Oprofile decodes only stack for backtracing on i386 ]

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: systemtap@sources.redhat.com
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Harvey Harrison <harvey.harrison@gmail.com>
Cc: Jan Blunck <jblunck@suse.de>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <20090511210300.17332.67549.stgit@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
 arch/x86/include/asm/ptrace.h |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index e304b66..aed0894 100644
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -187,14 +187,14 @@ static inline int v8086_mode(struct pt_regs *regs)
 
 /*
  * X86_32 CPUs don't save ss and esp if the CPU is already in kernel mode
- * when it traps.  So regs will be the current sp.
+ * when it traps.  So &regs->sp will be the current sp.
  *
  * This is valid only for kernel mode traps.
  */
 static inline unsigned long kernel_trap_sp(struct pt_regs *regs)
 {
 #ifdef CONFIG_X86_32
-	return (unsigned long)regs;
+	return (unsigned long)&regs->sp;
 #else
 	return regs->sp;
 #endif