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authorMasami Hiramatsu <mhiramat@redhat.com>2009-05-11 17:03:00 -0400
committerIngo Molnar <mingo@elte.hu>2009-05-12 00:39:52 +0200
commit7b6c6c77732ca1d2498eda7eabb64f9648896e96 (patch)
treef5eccbffc028d396e454898db1edc66e7e6a4666
parent3c598766a2bae1b208470e7cc934ac462561e3cb (diff)
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> [ v2: rename the API to kernel_stack_pointer(), move variable inside ] Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: systemtap@sources.redhat.com Cc: Harvey Harrison <harvey.harrison@gmail.com> Cc: Jan Blunck <jblunck@suse.de> Cc: Christoph Hellwig <hch@infradead.org> LKML-Reference: <20090511210300.17332.67549.stgit@localhost.localdomain> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--arch/x86/include/asm/ptrace.h7
-rw-r--r--arch/x86/oprofile/backtrace.c2
2 files changed, 5 insertions, 4 deletions
diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index e304b66abee..624f133943e 100644
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -187,14 +187,15 @@ 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. The previous stack will be directly underneath the saved
+ * registers, and 'sp/ss' won't even have been saved. Thus the '&regs->sp'.
*
* This is valid only for kernel mode traps.
*/
-static inline unsigned long kernel_trap_sp(struct pt_regs *regs)
+static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
{
#ifdef CONFIG_X86_32
- return (unsigned long)regs;
+ return (unsigned long)(&regs->sp);
#else
return regs->sp;
#endif
diff --git a/arch/x86/oprofile/backtrace.c b/arch/x86/oprofile/backtrace.c
index 04df67f8a7b..044897be021 100644
--- a/arch/x86/oprofile/backtrace.c
+++ b/arch/x86/oprofile/backtrace.c
@@ -76,9 +76,9 @@ void
x86_backtrace(struct pt_regs * const regs, unsigned int depth)
{
struct frame_head *head = (struct frame_head *)frame_pointer(regs);
- unsigned long stack = kernel_trap_sp(regs);
if (!user_mode_vm(regs)) {
+ unsigned long stack = kernel_stack_pointer(regs);
if (depth)
dump_trace(NULL, regs, (unsigned long *)stack, 0,
&backtrace_ops, &depth);