linux-kernel - Re: [PATCH v3 9/9] powerpc/traps: Add line prefix in show

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Message-Id: <20180801150350.GC6022@kermit-br-ibm-com>
Date:   Wed, 1 Aug 2018 12:03:50 -0300
From:   Murilo Opsfelder Araujo <muriloo@...ux.ibm.com>
To:     Christophe LEROY <christophe.leroy@....fr>
Cc:     linux-kernel@...r.kernel.org,
        "Alastair D'Silva" <alastair@...ilva.org>,
        Andrew Donnellan <andrew.donnellan@....ibm.com>,
        Balbir Singh <bsingharora@...il.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Cyril Bur <cyrilbur@...il.com>,
        "Eric W . Biederman" <ebiederm@...ssion.com>,
        Joe Perches <joe@...ches.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Michael Neuling <mikey@...ling.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Paul Mackerras <paulus@...ba.org>,
        Simon Guo <wei.guo.simon@...il.com>,
        Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>,
        "Tobin C . Harding" <me@...in.cc>, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v3 9/9] powerpc/traps: Add line prefix in
 show_instructions()

Hi, Christophe.

On Wed, Aug 01, 2018 at 08:41:15AM +0200, Christophe LEROY wrote:
>
>
> Le 31/07/2018 à 16:50, Murilo Opsfelder Araujo a écrit :
> > Remove "Instruction dump:" line by adding a prefix to display current->comm
> > and current->pid, along with the instructions dump.
> >
> > The prefix can serve as a glue that links the instructions dump to its
> > originator, allowing messages to be interleaved in the logs.
> >
> > Before this patch, a page fault looked like:
> >
> >    pandafault[10524]: segfault (11) at 100007d0 nip 1000061c lr 7fffbd295100 code 2 in pandafault[10000000+10000]
> >    Instruction dump:
> >    4bfffeec 4bfffee8 3c401002 38427f00 fbe1fff8 f821ffc1 7c3f0b78 3d22fffe
> >    392988d0 f93f0020 e93f0020 39400048 <99490000> 39200000 7d234b78 383f0040
> >
> > After this patch, it looks like:
> >
> >    pandafault[10850]: segfault (11) at 100007d0 nip 1000061c lr 7fff9f3e5100 code 2 in pandafault[10000000+10000]
> >    pandafault[10850]: code: 4bfffeec 4bfffee8 3c401002 38427f00 fbe1fff8 f821ffc1 7c3f0b78 3d22fffe
> >    pandafault[10850]: code: 392988d0 f93f0020 e93f0020 39400048 <99490000> 39200000 7d234b78 383f0040
> >
> > Signed-off-by: Murilo Opsfelder Araujo <muriloo@...ux.ibm.com>
>
> Does the script scripts/decode_stacktrace.sh also works with this format
> change ?

I've got more feedback from Michael about this.  A better approach would be
having a new show_user_instructions(), a slightly modified version of
show_instructions(), that can be called from within show_signal_msg().

Since _exception_pkey() dies if the exception is in kernel mode, we'll be
safe to call the new show_user_instructions(), without interfering in
scripts/decode_stacktrace.sh.

Cheers
Murilo