* Steven Rostedt <rost...@goodmis.org> wrote:
> Ingo, Peter,
>
> I posted this back in July as an RFC and did get Masami's reviewed-by
> tag. I'm currently cleaning out my inbox and realized I didn't push this
> further. I didn't know which branch to base this on, so I just picked
> the tip/x86/asm branch where I did my last x86 work in.
>
> https://lkml.org/lkml/2012/7/13/351
>
> Please pull the latest tip/x86/asm tree, which can be found at:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
> tip/x86/asm
>
> Head SHA1: 6c8d8b3c69cef1330e0c5cbc2a8b9268024927a0
>
>
> Steven Rostedt (1):
> x86_32: Return actual stack when requesting sp from regs
>
> ----
> arch/x86/include/asm/ptrace.h | 9 +++++++++
> 1 file changed, 9 insertions(+)
> ---------------------------
> commit 6c8d8b3c69cef1330e0c5cbc2a8b9268024927a0
> Author: Steven Rostedt <rost...@goodmis.org>
> Date: Fri Jul 13 15:44:14 2012 -0400
>
> x86_32: Return actual stack when requesting sp from regs
>
> As x86_32 traps do not save sp when taken in kernel mode, we need to
> accommodate the sp when requesting to get the register.
>
> This affects kprobes.
>
> Before:
>
> # echo 'p:ftrace sys_read+4 s=%sp' > /debug/tracing/kprobe_events
> # echo 1 > /debug/tracing/events/kprobes/enable
> # cat trace
> sshd-1345 [000] d... 489.117168: ftrace:
> (sys_read+0x4/0x70) s=b7e96768
> sshd-1345 [000] d... 489.117191: ftrace:
> (sys_read+0x4/0x70) s=b7e96768
> cat-1447 [000] d... 489.117392: ftrace:
> (sys_read+0x4/0x70) s=5a7
> cat-1447 [001] d... 489.118023: ftrace:
> (sys_read+0x4/0x70) s=b77ad05f
> less-1448 [000] d... 489.118079: ftrace:
> (sys_read+0x4/0x70) s=b7762e06
> less-1448 [000] d... 489.118117: ftrace:
> (sys_read+0x4/0x70) s=b7764970
>
> After:
> sshd-1352 [000] d... 362.348016: ftrace:
> (sys_read+0x4/0x70) s=f3febfa8
> sshd-1352 [000] d... 362.348048: ftrace:
> (sys_read+0x4/0x70) s=f3febfa8
> bash-1355 [001] d... 362.348081: ftrace:
> (sys_read+0x4/0x70) s=f5075fa8
> sshd-1352 [000] d... 362.348082: ftrace:
> (sys_read+0x4/0x70) s=f3febfa8
> sshd-1352 [000] d... 362.690950: ftrace:
> (sys_read+0x4/0x70) s=f3febfa8
> bash-1355 [001] d... 362.691033: ftrace:
> (sys_read+0x4/0x70) s=f5075fa8
>
> Link:
> http://lkml.kernel.org/r/1342208654.30075.22.ca...@gandalf.stny.rr.com
>
> Reviewed-by: Masami Hiramatsu <masami.hiramatsu...@hitachi.com>
> Signed-off-by: Steven Rostedt <rost...@goodmis.org>
>
> diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
> index dcfde52..2233713 100644
> --- a/arch/x86/include/asm/ptrace.h
> +++ b/arch/x86/include/asm/ptrace.h
> @@ -246,6 +246,15 @@ static inline unsigned long regs_get_register(struct
> pt_regs *regs,
> {
> if (unlikely(offset > MAX_REG_OFFSET))
> return 0;
> +#ifdef CONFIG_X86_32
> + /*
> + * Traps from the kernel do not save sp and ss.
> + * Use the helper function to retrieve sp.
> + */
> + if (offset == offsetof(struct pt_regs, sp) &&
> + regs->cs == __KERNEL_CS)
> + return kernel_stack_pointer(regs);
> +#endif
> return *(unsigned long *)((unsigned long)regs + offset);
> }
Pulled, thanks Steve!
Ingo
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