* [PATCH][GIT PULL] x86_32: Return actual stack when requesting sp from regs
@ 2012-11-20 19:56 Steven Rostedt
2012-12-08 15:07 ` Ingo Molnar
0 siblings, 1 reply; 2+ messages in thread
From: Steven Rostedt @ 2012-11-20 19:56 UTC (permalink / raw)
To: LKML
Cc: Ingo Molnar, H. Peter Anvin, Thomas Gleixner, Masami Hiramatsu,
H. Peter Anvin
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 <rostedt@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.camel@gandalf.stny.rr.com
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@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);
}
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH][GIT PULL] x86_32: Return actual stack when requesting sp from regs
2012-11-20 19:56 [PATCH][GIT PULL] x86_32: Return actual stack when requesting sp from regs Steven Rostedt
@ 2012-12-08 15:07 ` Ingo Molnar
0 siblings, 0 replies; 2+ messages in thread
From: Ingo Molnar @ 2012-12-08 15:07 UTC (permalink / raw)
To: Steven Rostedt; +Cc: LKML, H. Peter Anvin, Thomas Gleixner, Masami Hiramatsu
* Steven Rostedt <rostedt@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 <rostedt@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.camel@gandalf.stny.rr.com
>
> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> Signed-off-by: Steven Rostedt <rostedt@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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