From: "liaochang (A)" <liaochang1@huawei.com>
To: Jisheng Zhang <jszhang3@mail.ustc.edu.cn>
Cc: Masami Hiramatsu <mhiramat@kernel.org>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Guo Ren <guoren@linux.alibaba.com>,
<linux-riscv@lists.infradead.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] riscv: keep interrupts disabled for BREAKPOINT exception
Date: Tue, 6 Apr 2021 15:27:51 +0800 [thread overview]
Message-ID: <a00d3c12-bbb9-1849-47ce-75c320ed5900@huawei.com> (raw)
In-Reply-To: <20210402213206.7db93785@xhacker>
Hi Jisheng,
在 2021/4/2 21:32, Jisheng Zhang 写道:
> On Thu, 1 Apr 2021 16:49:47 +0800
> "liaochang (A)" <liaochang1@huawei.com> wrote:
>
>> Hi Jisheng,
>
> Hi,
>
>>
>> 在 2021/3/31 22:22, Jisheng Zhang 写道:
>>> On Tue, 30 Mar 2021 18:33:16 +0900
>>> Masami Hiramatsu <mhiramat@kernel.org> wrote:
>>>
>>>> Hi Jisheng,
>>>
>>> Hi Masami,
>>>
>>>>
>>>> On Tue, 30 Mar 2021 02:16:24 +0800
>>>> Jisheng Zhang <jszhang3@mail.ustc.edu.cn> wrote:
>>>>
>>>>> From: Jisheng Zhang <jszhang@kernel.org>
>>>>>
>>>>> Current riscv's kprobe handlers are run with both preemption and
>>>>> interrupt enabled, this violates kprobe requirements. Fix this issue
>>>>> by keeping interrupts disabled for BREAKPOINT exception.
>>>>
>>>> Not only while the breakpoint exception but also until the end of
>>>> the single step (maybe you are using __BUG_INSN_32 ??) need to be
>>>> disable interrupts. Can this do that?
>>>>
>>>
>>> interrupt is disabled during "single step" by kprobes_save_local_irqflag()
>>> and kprobes_restore_local_irqflag(). The code flow looks like:
>>>
>>> do_trap_break() // for bp
>>> kprobe_breakpoint_handler()
>>> setup_singlestep()
>>> kprobes_restore_local_irqflag()
>>>
>>> do_trap_break() // for ss
>>> kprobe_single_step_handler()
>>> kprobes_restore_local_irqflag()
>>
>> Recently, kernel hit BUG_ON() on QEMU after I install a probe at "sys_read" via kprobe,
>
> TIPS: Each line should not exceed 80 chars
>
>> accoriding to my debugging and analysis it looks like caused by the "irq disable" operation for single-stepping.
>>
>> I present a detailed description about this problem in the mail with title "[PATCH] riscv/kprobe: fix kernel panic when invoking sys_read traced by kprobe".
>> Looking forward to some feedback,Thanks.
>>
>
> I will comment that patch.
Thanks for your reminder.
>
> thanks
>
> .
>
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next prev parent reply other threads:[~2021-04-06 7:28 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-29 18:16 [PATCH] riscv: keep interrupts disabled for BREAKPOINT exception Jisheng Zhang
2021-03-30 9:33 ` Masami Hiramatsu
2021-03-31 14:22 ` Jisheng Zhang
2021-04-01 0:30 ` Masami Hiramatsu
2021-04-03 18:30 ` Maciej W. Rozycki
2021-04-08 11:23 ` Jisheng Zhang
2021-04-08 22:38 ` Masami Hiramatsu
2021-04-08 22:45 ` Maciej W. Rozycki
2021-04-01 8:49 ` liaochang (A)
2021-04-02 13:32 ` Jisheng Zhang
2021-04-06 7:27 ` liaochang (A) [this message]
2021-04-12 1:09 ` Palmer Dabbelt
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