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Re: [PATCH -tip v8 02/26] kprobes/x86: Allow to handle reentered kprobe on singlestepping
- 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 <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>, Thomas Gleixner <tglx at linutronix dot de>
- Date: Fri, 21 Mar 2014 17:44:00 -0400
- Subject: Re: [PATCH -tip v8 02/26] kprobes/x86: Allow to handle reentered kprobe on singlestepping
- Authentication-results: sourceware.org; auth=none
- References: <20140305115843 dot 22766 dot 8355 dot stgit at ltc230 dot yrl dot intra dot hitachi dot co dot jp> <20140305115857 dot 22766 dot 61414 dot stgit at ltc230 dot yrl dot intra dot hitachi dot co dot jp>
On Wed, 05 Mar 2014 20:58:57 +0900
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> wrote:
> Since the NMI handlers(e.g. perf) can interrupt in the
> single stepping (or preparing the single stepping, do_debug
> etc.), we should consider a kprobe is hit in the NMI
> handler. Even in that case, the kprobe is allowed to be
> reentered as same as the kprobes hit in kprobe handlers
> (KPROBE_HIT_ACTIVE or KPROBE_HIT_SSDONE).
> The real issue will happen when a kprobe hit while another
> reentered kprobe is processing (KPROBE_REENTER), because
> we already consumed a saved-area for the previous kprobe.
>
> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
-- Steve