From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Ryan Sullivan <rysulliv@redhat.com>,
live-patching@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Cc: joe.lawrence@redhat.com, pmladek@suse.com, mbenes@suse.cz,
jikos@kernel.org, jpoimboe@kernel.org,
naveen.n.rao@linux.ibm.com, mpe@ellerman.id.au,
npiggin@gmail.com
Subject: Re: [PATCH] powerpc/ftrace: restore r2 to caller's stack on livepatch sibling call
Date: Thu, 8 Aug 2024 09:00:21 +0200 [thread overview]
Message-ID: <79fffe34-ce0b-4937-a85a-0ce566684887@csgroup.eu> (raw)
In-Reply-To: <20240724183321.9195-1-rysulliv@redhat.com>
Le 24/07/2024 à 20:33, Ryan Sullivan a écrit :
> [Vous ne recevez pas souvent de courriers de rysulliv@redhat.com. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
>
> Currently, on PowerPC machines, sibling calls in livepatched functions
> cause the stack to be corrupted and are thus not supported by tools
> such as kpatch. Below is an example stack frame showing one such
> currupted stacks:
>
> RHEL-7.6: Linux 3.10.0 ppc64le
>
...
>
> This is caused by the toc stub generated on a sibling call:
>
...
>
> This patch restores r2 value to caller's stack, on a sibling call this
> will uncorrupt the caller's stack and otherwise will be redundant.
Be carefull. On powerpc/32, r2 contains the pointer to current struct.
When I first read the subject of the patch I was puzzled.
You should say toc instead of r2, or make it explicit in the title that
it is for powerpc/64
Christophe
WARNING: multiple messages have this Message-ID (diff)
From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Ryan Sullivan <rysulliv@redhat.com>,
live-patching@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Cc: pmladek@suse.com, joe.lawrence@redhat.com, jikos@kernel.org,
npiggin@gmail.com, naveen.n.rao@linux.ibm.com, mbenes@suse.cz,
jpoimboe@kernel.org
Subject: Re: [PATCH] powerpc/ftrace: restore r2 to caller's stack on livepatch sibling call
Date: Thu, 8 Aug 2024 09:00:21 +0200 [thread overview]
Message-ID: <79fffe34-ce0b-4937-a85a-0ce566684887@csgroup.eu> (raw)
In-Reply-To: <20240724183321.9195-1-rysulliv@redhat.com>
Le 24/07/2024 à 20:33, Ryan Sullivan a écrit :
> [Vous ne recevez pas souvent de courriers de rysulliv@redhat.com. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
>
> Currently, on PowerPC machines, sibling calls in livepatched functions
> cause the stack to be corrupted and are thus not supported by tools
> such as kpatch. Below is an example stack frame showing one such
> currupted stacks:
>
> RHEL-7.6: Linux 3.10.0 ppc64le
>
...
>
> This is caused by the toc stub generated on a sibling call:
>
...
>
> This patch restores r2 value to caller's stack, on a sibling call this
> will uncorrupt the caller's stack and otherwise will be redundant.
Be carefull. On powerpc/32, r2 contains the pointer to current struct.
When I first read the subject of the patch I was puzzled.
You should say toc instead of r2, or make it explicit in the title that
it is for powerpc/64
Christophe
next prev parent reply other threads:[~2024-08-08 7:00 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-24 18:33 [PATCH] powerpc/ftrace: restore r2 to caller's stack on livepatch sibling call Ryan Sullivan
2024-07-24 18:33 ` Ryan Sullivan
2024-07-29 14:17 ` Michael Ellerman
2024-07-29 14:17 ` Michael Ellerman
2024-07-29 15:02 ` Ryan Sullivan
2024-07-29 15:02 ` Ryan Sullivan
2024-08-15 10:22 ` Michael Ellerman
2024-08-15 16:07 ` Ryan Sullivan
2024-08-15 16:24 ` Joe Lawrence
2024-09-09 16:33 ` Ryan B. Sullivan
2024-09-10 7:21 ` Michael Ellerman
2024-09-10 15:02 ` Ryan B. Sullivan
2024-08-08 7:00 ` Christophe Leroy [this message]
2024-08-08 7:00 ` Christophe Leroy
2024-08-08 17:55 ` [PATCH v2] powerpc/ftrace: restore caller's toc on ppc64 " Ryan Sullivan
2024-08-08 17:55 ` Ryan Sullivan
2024-08-08 21:17 ` Ryan Sullivan
2024-08-08 21:17 ` Ryan Sullivan
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