From: Michael Ellerman <mpe@ellerman.id.au>
To: "Ryan B. Sullivan" <rysulliv@redhat.com>,
Joe Lawrence <joe.lawrence@redhat.com>
Cc: live-patching@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
pmladek@suse.com, mbenes@suse.cz, jikos@kernel.org,
jpoimboe@kernel.org, naveen.n.rao@linux.ibm.com,
christophe.leroy@csgroup.eu, npiggin@gmail.com
Subject: Re: [PATCH] powerpc/ftrace: restore r2 to caller's stack on livepatch sibling call
Date: Tue, 10 Sep 2024 17:21:57 +1000 [thread overview]
Message-ID: <87bk0wrn1m.fsf@mail.lhotse> (raw)
In-Reply-To: <Zt8jaSQjpwtfJaVx@sullivan-work>
"Ryan B. Sullivan" <rysulliv@redhat.com> writes:
> Hello all,
>
> Just wanted to ping and see if there was any further feedback or
> questions regarding the patch?
Hi Ryan,
I'd really like a selftest that triggers the sibling call behaviour.
As I said upthread I tried writing one but failed. Which you later
explained is because the cross-module sibling call is not generated by
the compiler but rather by the code being objcopy'ed (or similar).
I think it should be possible to trick the compiler into letting us do a
cross-module sibling call by doing it in an inline asm block. Obviously
that's non-standard, but I think it might work well enough for a test?
We have an example of calling a function within an inline asm block in
call_do_irq().
I'll try to find time to get that done, but I can't promise when.
cheers
next prev parent reply other threads:[~2024-09-10 7:22 UTC|newest]
Thread overview: 12+ 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
2024-07-29 14:17 ` Michael Ellerman
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 [this message]
2024-09-10 15:02 ` Ryan B. Sullivan
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 21:17 ` Ryan Sullivan
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