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From: Jisheng Zhang <jszhang3@mail.ustc.edu.cn>
To: "liaochang (A)" <liaochang1@huawei.com>
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: Fri, 2 Apr 2021 21:32:06 +0800	[thread overview]
Message-ID: <20210402213206.7db93785@xhacker> (raw)
In-Reply-To: <096752a7-21f9-8339-2e76-8c65859fa1d7@huawei.com>

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


_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
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WARNING: multiple messages have this Message-ID (diff)
From: Jisheng Zhang <jszhang3@mail.ustc.edu.cn>
To: "liaochang (A)" <liaochang1@huawei.com>
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: Fri, 2 Apr 2021 21:32:06 +0800	[thread overview]
Message-ID: <20210402213206.7db93785@xhacker> (raw)
In-Reply-To: <096752a7-21f9-8339-2e76-8c65859fa1d7@huawei.com>

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


  reply	other threads:[~2021-04-02 13:37 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-29 18:16 [PATCH] riscv: keep interrupts disabled for BREAKPOINT exception Jisheng Zhang
2021-03-29 18:16 ` Jisheng Zhang
2021-03-30  9:33 ` Masami Hiramatsu
2021-03-30  9:33   ` Masami Hiramatsu
2021-03-31 14:22   ` Jisheng Zhang
2021-03-31 14:22     ` Jisheng Zhang
2021-04-01  0:30     ` Masami Hiramatsu
2021-04-01  0:30       ` Masami Hiramatsu
2021-04-03 18:30       ` Maciej W. Rozycki
2021-04-03 18:30         ` Maciej W. Rozycki
2021-04-08 11:23         ` Jisheng Zhang
2021-04-08 11:23           ` Jisheng Zhang
2021-04-08 22:38           ` Masami Hiramatsu
2021-04-08 22:38             ` Masami Hiramatsu
2021-04-08 22:45             ` Maciej W. Rozycki
2021-04-08 22:45               ` Maciej W. Rozycki
2021-04-01  8:49     ` liaochang (A)
2021-04-01  8:49       ` liaochang (A)
2021-04-02 13:32       ` Jisheng Zhang [this message]
2021-04-02 13:32         ` Jisheng Zhang
2021-04-06  7:27         ` liaochang (A)
2021-04-06  7:27           ` liaochang (A)
2021-04-12  1:09 ` Palmer Dabbelt
2021-04-12  1:09   ` Palmer Dabbelt

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