Re: [PATCH] loongarch: Only select HAVE_OBJTOOL and allow ORC unwinder if the inline assembler supports R_LARCH_{32,64}_PCREL

[Nathan Chancellor]

On Tue, Jun 04, 2024 at 11:07:41PM +0800, Xi Ruoyao wrote:
> GAS <= 2.41 does not support generating R_LARCH_{32,64}_PCREL for
> "label - ." and it generates R_LARCH_{ADD,SUB}{32,64} pairs instead.
> objtool cannot handle R_LARCH_{ADD,SUB}{32,64} pair in __jump_table
> (static key implementation) and etc. so it will produce some warnings.
> This is causing the kernel CI systems to complain everywhere.
> 
> For GAS we can check if -mthin-add-sub option is available to know if
> R_LARCH_{32,64}_PCREL are supported.
> 
> For Clang, we require Clang >= 18 and Clang >= 17 already supports
> R_LARCH_{32,64}_PCREL, so we can always assume Clang is fine for
> objtool.

For what it's worth, I have noticed some warnings with clang that I
don't see with GCC but I only filed an issue on our GitHub and never
followed up on the mailing list, so sorry about that.

https://github.com/ClangBuiltLinux/linux/issues/2024

Might be tangential to this patch though but I felt it was worth
mentioning.

Cheers,
Nathan