From: Jisheng Zhang <jszhang@kernel.org>
To: Changbin Du <changbin.du@gmail.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] riscv: fix oops caused by irq on/off tracer
Date: Thu, 10 Feb 2022 23:37:06 +0800 [thread overview]
Message-ID: <YgUxIgMJRhJD6/GP@xhacker> (raw)
In-Reply-To: <YgUuzZp/eiNoXejK@xhacker>
On Thu, Feb 10, 2022 at 11:27:21PM +0800, Jisheng Zhang wrote:
> On Thu, Feb 10, 2022 at 09:37:58PM +0800, Changbin Du wrote:
> > On Thu, Feb 10, 2022 at 01:32:59AM +0800, Jisheng Zhang wrote:
> > [snip]
> > > Hi Changbin,
> > >
> > > I read the code and find that current riscv frame records during
> > > exception isn't as completed as other architectures. riscv only
> > > records frames from the ret_from_exception(). If we add completed
> > What do you mean for 'record'?
> >
>
> stack frame record.
>
> > > frame records as other arch do, then the issue you saw can also
> > > be fixed at the same time.
> > >
> > I don't think so. The problem is __builtin_return_address(1) trigger page fault
> > here.
>
> There's misunderstanding here. I interpret this bug as incomplete
> stackframes.
>
> This is current riscv stackframe during exception:
>
> high
> ----------------
> top | | <- ret_from_exception
> ----------------
> | | <- trace_hardirqs_on
> -----------------
> low
sorry, the "top" is wrongly placed.
high
----------------
| | <- ret_from_exception
----------------
| | <- trace_hardirqs_on
-----------------
top
low
>
> As you said, the CALLER_ADDR1 a.k.a __builtin_return_address(1) needs
> at least two parent call frames.
>
> If we complete the stackframes during exception as other arch does:
>
> high
> ----------------
> top | | <- the synthetic stackframe from the interrupted point
> ----------------
> .....
> ----------------
> | | <- ret_from_exception
> ----------------
> | | <- trace_hardirqs_on
> -----------------
> low
ditto
>
>
> Then we meet the "at least two parent call frames" requirement. IOW, my
> solution solve the problem from the entry.S side. One of the advantages
> would be we let interrupted point show up in dump_stack() as other arch
> do. What I'm not sure is whether it's safe to do so now since rc3 is
> released.
>
next prev parent reply other threads:[~2022-02-10 15:45 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-29 0:42 [PATCH v2] riscv: fix oops caused by irq on/off tracer Changbin Du
2022-01-29 14:49 ` kernel test robot
2022-02-06 17:25 ` Jisheng Zhang
2022-02-07 12:38 ` ChangbinCONFIG_IRQSOFF_TRACER Du
2022-02-07 15:31 ` Jisheng Zhang
2022-02-08 0:35 ` Changbin Du
2022-02-09 17:32 ` Jisheng Zhang
2022-02-10 13:37 ` Changbin Du
2022-02-10 15:27 ` Jisheng Zhang
2022-02-10 15:37 ` Jisheng Zhang [this message]
2022-02-11 3:06 ` Changbin Du
2022-02-10 15:59 ` Jessica Clarke
2022-02-11 3:21 ` Changbin Du
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