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From: Mark Rutland <mark.rutland@arm.com>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Mark Brown <broonie@kernel.org>,
	Kalesh Singh <kaleshsingh@google.com>,
	Marc Zyngier <maz@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Sandeepa Prabhu <sandeepa.s.prabhu@gmail.com>
Subject: Re: [PATCH v2 1/3] arm64: Prohibit instrumentation on arch_stack_walk()
Date: Fri, 9 Dec 2022 11:16:34 +0000	[thread overview]
Message-ID: <Y5MZEhIpBYd81lZV@FVFF77S0Q05N> (raw)
In-Reply-To: <20221206094137.389e4c374f4be060af19f33a@kernel.org>

On Tue, Dec 06, 2022 at 09:41:37AM +0900, Masami Hiramatsu wrote:
> On Fri, 2 Dec 2022 13:17:30 +0000
> Mark Rutland <mark.rutland@arm.com> wrote:
> > I had a go at testing this patch, and it fixes the crash with the reproducer
> > above, but there are plenty of other instances in stacktrace.c that lead to the
> > same sort of crash, e.g.
> > 
> > # echo p stackinfo_get_task >> ${TRACEFS}/kprobe_events
> > # echo 1 > ${TRACEFS}/events/kprobes/enable
> 
> Oops, thanks for pointing! Hmm, I thought stackinfo_get_task() is an
> inlined function usually. Maybe we should make it nokprobe_inline.
> But this is just one case. I need to scan all symbols to trace...

FWIW, due to other instrumentation issues I've started doing a larger noinstr
cleanup on arm64 which should address this, as fixing this properly involves
also modifying a bunch of underlying helpers (e.g. preempt_count()).

I can Cc you when sending that out, if you'd like? That'll probably be in the
new year.

Thanks,
Mark.

_______________________________________________
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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
From: Mark Rutland <mark.rutland@arm.com>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Mark Brown <broonie@kernel.org>,
	Kalesh Singh <kaleshsingh@google.com>,
	Marc Zyngier <maz@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Sandeepa Prabhu <sandeepa.s.prabhu@gmail.com>
Subject: Re: [PATCH v2 1/3] arm64: Prohibit instrumentation on arch_stack_walk()
Date: Fri, 9 Dec 2022 11:16:34 +0000	[thread overview]
Message-ID: <Y5MZEhIpBYd81lZV@FVFF77S0Q05N> (raw)
In-Reply-To: <20221206094137.389e4c374f4be060af19f33a@kernel.org>

On Tue, Dec 06, 2022 at 09:41:37AM +0900, Masami Hiramatsu wrote:
> On Fri, 2 Dec 2022 13:17:30 +0000
> Mark Rutland <mark.rutland@arm.com> wrote:
> > I had a go at testing this patch, and it fixes the crash with the reproducer
> > above, but there are plenty of other instances in stacktrace.c that lead to the
> > same sort of crash, e.g.
> > 
> > # echo p stackinfo_get_task >> ${TRACEFS}/kprobe_events
> > # echo 1 > ${TRACEFS}/events/kprobes/enable
> 
> Oops, thanks for pointing! Hmm, I thought stackinfo_get_task() is an
> inlined function usually. Maybe we should make it nokprobe_inline.
> But this is just one case. I need to scan all symbols to trace...

FWIW, due to other instrumentation issues I've started doing a larger noinstr
cleanup on arm64 which should address this, as fixing this properly involves
also modifying a bunch of underlying helpers (e.g. preempt_count()).

I can Cc you when sending that out, if you'd like? That'll probably be in the
new year.

Thanks,
Mark.

  reply	other threads:[~2022-12-09 11:17 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-12-02  2:18 [PATCH v2 0/3] arm64: kprobes: Fix bugs in kprobes for arm64 Masami Hiramatsu (Google)
2022-12-02  2:18 ` Masami Hiramatsu (Google)
2022-12-02  2:18 ` [PATCH v2 1/3] arm64: Prohibit instrumentation on arch_stack_walk() Masami Hiramatsu (Google)
2022-12-02  2:18   ` Masami Hiramatsu (Google)
2022-12-02 13:17   ` Mark Rutland
2022-12-02 13:17     ` Mark Rutland
2022-12-06  0:41     ` Masami Hiramatsu
2022-12-06  0:41       ` Masami Hiramatsu
2022-12-09 11:16       ` Mark Rutland [this message]
2022-12-09 11:16         ` Mark Rutland
2022-12-11  3:30         ` Masami Hiramatsu
2022-12-11  3:30           ` Masami Hiramatsu
2022-12-02  2:18 ` [PATCH v2 2/3] arm64: kprobes: Let arch do_page_fault() fix up page fault in user handler Masami Hiramatsu (Google)
2022-12-02  2:18   ` Masami Hiramatsu (Google)
2022-12-02  2:18 ` [PATCH v2 3/3] arm64: kprobes: Return DBG_HOOK_ERROR if kprobes can not handle a BRK Masami Hiramatsu (Google)
2022-12-02  2:18   ` Masami Hiramatsu (Google)
2022-12-05 15:43 ` [PATCH v2 0/3] arm64: kprobes: Fix bugs in kprobes for arm64 Will Deacon
2022-12-05 15:43   ` Will Deacon

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