Re: [kbuild-all] Re: [ammarfaizi2-block:stable/linux-stable-rc/queue/5.15 146/150] kernel/futex.o: warning: objtool: futex_atomic_op_inuser()+0xb8: unreachable instruction

Chen, Rong A
2022-05-12T09:30:30Z

On 5/12/2022 4:17 PM, Peter Zijlstra wrote:
> On Thu, May 12, 2022 at 10:00:33AM +0800, kernel test robot wrote:
>> tree: https://github.com/ammarfaizi2/linux-block stable/linux-stable-rc/queue/5.15
>> head: 305e905f70311e1b49cc730931a19c3e364f4d8c
>> commit: 45dc9d706619a6814e4063d5431483f94badb5a1 [146/150] x86: Add straight-line-speculation mitigation
>> config: x86_64-randconfig-m001-20220509 (https://download.01.org/0day-ci/archive/20220512/202205120956.qLpGQurX-lkp@intel.com/config)
>> compiler: gcc-11 (Debian 11.2.0-20) 11.2.0
>> reproduce (this is a W=1 build):
>> # https://github.com/ammarfaizi2/linux-block/commit/45dc9d706619a6814e4063d5431483f94badb5a1
>> git remote add ammarfaizi2-block https://github.com/ammarfaizi2/linux-block
>> git fetch --no-tags ammarfaizi2-block stable/linux-stable-rc/queue/5.15
>> git checkout 45dc9d706619a6814e4063d5431483f94badb5a1
>> # save the config file
>> mkdir build_dir && cp config build_dir/.config
>> make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash
>>
>> If you fix the issue, kindly add following tag as appropriate
>> Reported-by: kernel test robot <lkp@intel.com>
>>
>> All warnings (new ones prefixed by >>):
>>
>>>> kernel/futex.o: warning: objtool: futex_atomic_op_inuser()+0xb8: unreachable instruction
>> --
>>>> mm/madvise.o: warning: objtool: madvise_behavior()+0x69: unreachable instruction
>> --
>>>> kernel/bpf/btf.o: warning: objtool: __btf_resolve_size()+0x72: unreachable instruction
>
> Would it be possible for the robot to include the output of this script:

Hi Peter,

Thanks for your advice, we'll support it asap.

Best Regards,
Rong Chen

>
> https://lkml.kernel.org/r/3eb3f091fd6bd9caba50392ceab98ce756804f3b.1650578171.git.jpoimboe@redhat.com
>
> for each objtool warning it gives (as run on vmlinux.o):
>
> $ ./scripts/objdump-func build-output/vmlinux.o futex_atomic_op_inuser
> $ ./scripts/objdump-func build-output/vmlinux.o madvise_behavior
> $ ./scripts/objdump-func build-output/vmlinux.o __btf_resolve_size
>
> etc.. that would make it easier to see what the problem is without
> having to reproduce the build.
>
> A super wild guess; but try this commit:
>
> 1ffbe4e935f9 ("objtool: Default ignore INT3 for unreachable")
>
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