From: "Jon Medhurst (Tixy)" <tixy@linaro.org>
To: Masami Hiramatsu <mhiramat@kernel.org>,
Russell King <linux@armlinux.org.uk>
Cc: linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"H . Peter Anvin" <hpa@zytor.com>, Wang Nan <wangnan0@huawei.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
"David A . Long" <dave.long@linaro.org>,
Sandeepa Prabhu <sandeepa.s.prabhu@gmail.com>
Subject: Re: [BUGFIX PATCH 1/3] kprobes/arm: Allow to handle reentered kprobe on single-stepping
Date: Tue, 14 Feb 2017 10:01:43 +0000 [thread overview]
Message-ID: <1487066503.2978.1.camel@linaro.org> (raw)
In-Reply-To: <148699820793.8505.2215835182494999847.stgit@devbox>
On Tue, 2017-02-14 at 00:03 +0900, Masami Hiramatsu wrote:
> This is arm port of commit 6a5022a56ac3 ("kprobes/x86: Allow to
> handle reentered kprobe on single-stepping")
>
> Since the FIQ handlers 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
Could to with 'is' being inserted above ^^^
(I know this is a copy of the x86 commit message)
> reentered kprobe is processing (KPROBE_REENTER), because
> we already consumed a saved-area for the previous kprobe.
>
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> ---
Acked-by: Jon Medhurst <tixy@linaro.org>
> arch/arm/probes/kprobes/core.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/arch/arm/probes/kprobes/core.c b/arch/arm/probes/kprobes/core.c
> index a4ec240..264fedb 100644
> --- a/arch/arm/probes/kprobes/core.c
> +++ b/arch/arm/probes/kprobes/core.c
> @@ -270,6 +270,7 @@ void __kprobes kprobe_handler(struct pt_regs *regs)
> switch (kcb->kprobe_status) {
> case KPROBE_HIT_ACTIVE:
> case KPROBE_HIT_SSDONE:
> + case KPROBE_HIT_SS:
> /* A pre- or post-handler probe got us here. */
> kprobes_inc_nmissed_count(p);
> save_previous_kprobe(kcb);
> @@ -278,6 +279,11 @@ void __kprobes kprobe_handler(struct pt_regs *regs)
> singlestep(p, regs, kcb);
> restore_previous_kprobe(kcb);
> break;
> + case KPROBE_REENTER:
> + /* A nested probe was hit in FIQ, it is a BUG */
> + pr_warn("Unrecoverable kprobe detected at %p.\n",
> + p->addr);
> + /* fall through */
> default:
> /* impossible cases */
> BUG();
>
next prev parent reply other threads:[~2017-02-14 10:28 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-13 15:02 [BUGFIX PATCH 0/3] kprobes/arm: Improve kprobes implementation on arm Masami Hiramatsu
2017-02-13 15:03 ` [BUGFIX PATCH 1/3] kprobes/arm: Allow to handle reentered kprobe on single-stepping Masami Hiramatsu
2017-02-14 10:01 ` Jon Medhurst (Tixy) [this message]
2017-02-14 15:32 ` Masami Hiramatsu
2017-02-13 15:04 ` [BUGFIX PATCH 2/3] kprobes/arm: Skip single-stepping in recursing path if possible Masami Hiramatsu
2017-02-14 10:07 ` Jon Medhurst (Tixy)
2017-02-14 15:31 ` Masami Hiramatsu
2017-02-13 15:05 ` [BUGFIX PATCH 3/3] kprobes/arm: Fix the return address of multiple kretprobes Masami Hiramatsu
2017-02-14 10:32 ` Jon Medhurst (Tixy)
2017-02-14 13:47 ` Jon Medhurst (Tixy)
2017-02-14 16:01 ` Masami Hiramatsu
2017-02-14 16:39 ` Jon Medhurst (Tixy)
2017-02-14 23:55 ` Masami Hiramatsu
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