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Re: [PATCH -tip v8 08/26] kprobes/x86: Call exception handlers directly from do_int3/do_debug
- From: Steven Rostedt <rostedt at goodmis dot org>
- To: Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>
- Cc: linux-kernel at vger dot kernel dot org, Ingo Molnar <mingo at kernel dot org>, Andi Kleen <ak at linux dot intel dot com>, Andi Kleen <andi at firstfloor dot org>, Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, Sandeepa Prabhu <sandeepa dot prabhu at linaro dot org>, Frederic Weisbecker <fweisbec at gmail dot com>, x86 at kernel dot org, fche at redhat dot com, mingo at redhat dot com, systemtap at sourceware dot org, "H. Peter Anvin" <hpa at zytor dot com>, Sasha Levin <sasha dot levin at oracle dot com>, Thomas Gleixner <tglx at linutronix dot de>, Seiji Aguchi <seiji dot aguchi at hds dot com>, Andrew Morton <akpm at linux-foundation dot org>
- Date: Mon, 24 Mar 2014 14:58:15 -0400
- Subject: Re: [PATCH -tip v8 08/26] kprobes/x86: Call exception handlers directly from do_int3/do_debug
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- References: <20140305115843 dot 22766 dot 8355 dot stgit at ltc230 dot yrl dot intra dot hitachi dot co dot jp> <20140305115939 dot 22766 dot 21199 dot stgit at ltc230 dot yrl dot intra dot hitachi dot co dot jp> <20140321210508 dot 358c30ee at gandalf dot local dot home> <532FF10A dot 8010502 at hitachi dot com>
On Mon, 24 Mar 2014 17:47:06 +0900
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> wrote:
> >> @@ -857,7 +857,7 @@ no_change:
> >> * Interrupts are disabled on entry as trap1 is an interrupt gate and they
> >> * remain disabled throughout this function.
> >> */
> >> -static int __kprobes post_kprobe_handler(struct pt_regs *regs)
> >> +int __kprobes kprobe_debug_handler(struct pt_regs *regs)
> >> - break;
> >> - case DIE_DEBUG:
> >> - if (post_kprobe_handler(args->regs)) {
> >
> > The DIE_DEBUG case is removed but not added anyplace else. The change
> > log doesn't say why this was removed.
>
> As you can see the above hunk, post_kprobe_handler() is now renamed
> as kprobe_debug_handler() which is called from do_debug() directly.
>
> What I meant in the patch comment;
>
> >> To avoid a kernel crash by probing on lockdep code, call
> >> kprobe_int3_handler and kprobe_debug_handler directly
> >> from do_int3 and do_debug.
>
> was actually pointing that change...
>
I missed the rename of post_kprobe_handler().
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
-- Steve