Re: [PATCH] objtool: continue if find_insn() fails in decode_instructions()

From: Ingo Molnar
Date: Sat Jan 07 2023 - 05:22:27 EST



* Sathvika Vasireddy <sv@xxxxxxxxxxxxx> wrote:

> Currently, decode_instructions() is failing if it is not able to find
> instruction, and this is happening since commit dbcdbdfdf137b4
> ("objtool: Rework instruction -> symbol mapping") because it is
> expecting instruction for STT_NOTYPE symbols.
>
> Due to this, the following objtool warnings are seen:
> [1] arch/powerpc/kernel/optprobes_head.o: warning: objtool: optprobe_template_end(): can't find starting instruction
> [2] arch/powerpc/kernel/kvm_emul.o: warning: objtool: kvm_template_end(): can't find starting instruction
> [3] arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): can't find starting instruction
>
> The warnings are thrown because find_insn() is failing for symbols that
> are at the end of the file, or at the end of the section. Given how
> STT_NOTYPE symbols are currently handled in decode_instructions(),
> continue if the instruction is not found, instead of throwing warning
> and returning.
>
> Signed-off-by: Naveen N. Rao <naveen.n.rao@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Sathvika Vasireddy <sv@xxxxxxxxxxxxx>

The SOB chain doesn't look valid: is Naveen N. Rao, the first SOB line, the
author of the patch? If yes then a matching From: line is needed.

Or if two people developed the patch, then Co-developed-by should be used:

Co-developed-by: First Co-Author <first@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: First Co-Author <first@xxxxxxxxxxxxxxxxxxxx>
Co-developed-by: Second Co-Author <second@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Second Co-Author <second@xxxxxxxxxxxxxxxxxxxx>

[ In this SOB sequence "Second Co-Author" is the one who submits the patch. ]

[ Please only use Co-developed-by if actual lines of code were written by
the co-author that created copyrightable material - it's not a courtesy
tag. Reviewed-by/Acked-by/Tested-by can be used to credit non-code
contributions. ]

Thanks,

Ingo