From: Peter Zijlstra <peterz@infradead.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: kernel test robot <lkp@intel.com>,
oe-kbuild-all@lists.linux.dev, linux-kernel@vger.kernel.org,
Catalin Marinas <catalin.marinas@arm.com>,
Josh Poimboeuf <jpoimboe@kernel.org>
Subject: Re: vmlinux.o: warning: objtool: mptscsih_abort+0x7f4: unreachable instruction
Date: Mon, 27 Feb 2023 15:08:42 +0100 [thread overview]
Message-ID: <Y/y5aucdGL7U+W7a@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <Y/ykNfK+1G8ZNYSU@FVFF77S0Q05N>
On Mon, Feb 27, 2023 at 12:38:13PM +0000, Mark Rutland wrote:
> [adding Peter and Josh, given objtool]
>
> On Mon, Feb 27, 2023 at 05:28:53PM +0800, kernel test robot wrote:
> > Hi Mark,
> >
> > FYI, the error/warning still remains.
> >
> > tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > head: f3a2439f20d918930cc4ae8f76fe1c1afd26958f
> > commit: c27cd083cfb9d392f304657ed00fcde1136704e7 Compiler attributes: GCC cold function alignment workarounds
> > date: 5 weeks ago
> > config: x86_64-randconfig-r026-20230227 (https://download.01.org/0day-ci/archive/20230227/202302271743.78emit6I-lkp@intel.com/config)
> > compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
> > reproduce (this is a W=1 build):
> > # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c27cd083cfb9d392f304657ed00fcde1136704e7
> > git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> > git fetch --no-tags linus master
> > git checkout c27cd083cfb9d392f304657ed00fcde1136704e7
> > # save the config file
> > mkdir build_dir && cp config build_dir/.config
> > make W=1 O=build_dir ARCH=x86_64 olddefconfig
> > make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash
> >
> > If you fix the issue, kindly add following tag where applicable
> > | Reported-by: kernel test robot <lkp@intel.com>
> > | Link: https://lore.kernel.org/oe-kbuild-all/202302271743.78emit6I-lkp@intel.com/
> >
> > All warnings (new ones prefixed by >>):
> >
> > >> vmlinux.o: warning: objtool: mptscsih_abort+0x7f4: unreachable instruction
> > 07ef 2fb7bff: e8 00 00 00 00 call 2fb7c04 <mptscsih_abort+0x7f4> 2fb7c00: R_X86_64_PLT32 mpt_halt_firmware-0x4
> > 07f4 2fb7c04: e9 75 fb ff ff jmp 2fb777e <mptscsih_abort+0x36e>
this is one of those noreturn things again... objtool was clever enough
to figure out that mpt_halt_firmware() does not return (all it's control
flow ends in panic()) and hence it 'knows' that +7f4 will not be
executed. But GCC didn't figure out the same.
next prev parent reply other threads:[~2023-02-27 14:09 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-27 9:28 vmlinux.o: warning: objtool: mptscsih_abort+0x7f4: unreachable instruction kernel test robot
2023-02-27 12:38 ` Mark Rutland
2023-02-27 14:08 ` Peter Zijlstra [this message]
2023-02-27 15:13 ` Josh Poimboeuf
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