lkml.org 
[lkml]   [2023]   [Feb]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: vmlinux.o: warning: objtool: mptscsih_abort+0x7f4: unreachable instruction
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.

\
 
 \ /
  Last update: 2023-03-27 00:37    [W:0.041 / U:0.872 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site