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x86, 32-bit: fix kernel_trap_sp()

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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>
This commit is contained in:
Masami Hiramatsu 2009-05-11 17:03:00 -04:00 committed by Ingo Molnar
parent 3c598766a2
commit 7b6c6c7773
2 changed files with 5 additions and 4 deletions
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7
arch/x86/include/asm/ptrace.h
View file

@ -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

2
arch/x86/oprofile/backtrace.c
View file

@ -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);