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Message-ID: <ZDcUvWuqv2VevITe@google.com>
Date: Wed, 12 Apr 2023 13:29:49 -0700
From: Nick Desaulniers <ndesaulniers@...gle.com>
To: Josh Poimboeuf <jpoimboe@...nel.org>,
"Borislav Petkov (AMD)" <bp@...en8.de>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org,
Peter Zijlstra <peterz@...radead.org>,
Miroslav Benes <mbenes@...e.cz>, linux-btrfs@...r.kernel.org,
Mark Rutland <mark.rutland@....com>,
linux-scsi@...r.kernel.org, linux-hyperv@...r.kernel.org,
Arnd Bergmann <arnd@...db.de>,
"Guilherme G . Piccoli" <gpiccoli@...lia.com>,
Michael Kelley <mikelley@...rosoft.com>,
kernel test robot <lkp@...el.com>
Subject: Re: [PATCH 02/11] init: Mark start_kernel() __noreturn
On Fri, Apr 07, 2023 at 05:09:55PM -0700, Josh Poimboeuf wrote:
> Fixes the following warning:
>
> vmlinux.o: warning: objtool: x86_64_start_reservations+0x28: unreachable instruction
>
> Reported-by: kernel test robot <lkp@...el.com>
> Link: https://lore.kernel.org/r/202302161142.K3ziREaj-lkp@intel.com/
> Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
Ah, I just realized that my series will conflict with this.
https://lore.kernel.org/llvm/20230412-no_stackp-v1-1-46a69b507a4b@google.com/
Perhaps if my series gets positive feedback; I can rebase it on top of
this and it can become part of your series?
For this patch,
Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>
Though I'm curious, it does look like it's necessary because of 01/11 in
the series? Any idea how the 0day bot report happened before 1/11
existed?
(Surely gcc isn't assuming a weak function is implicitly noreturn and
make optimizations based on that (that's one hazard I'm worried about)?)
It looks like perhaps the link to
https://lore.kernel.org/all/202302161142.K3ziREaj-lkp@intel.com/
on 2/11 was 0day testing the arch-cpu-idle-dead-noreturn branch of your
kernel tree
https://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux.git/log/?h=arch-cpu-idle-dead-noreturn
, which had 1/11 in it, IIUC? Perhaps this link should go on 1/11
rather than 2/11?
Looking back at 1/11, 3/11, 8/11 I noticed not all patches have links to 0day
reports. Are you able to flesh out more info how/what/when such objtool
warnings are observed? Are the warnings ever results of patches earlier
in the series?
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