Re: [PATCH v2 3/3] btf: Avoid weak external references

[Arnd Bergmann]

On Tue, Apr 9, 2024, at 17:01, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@xxxxxxxxxx>
>
> If the BTF code is enabled in the build configuration, the start/stop
> BTF markers are guaranteed to exist in the final link but not during the
> first linker pass.
>
> Avoid GOT based relocations to these markers in the final executable by
> providing preliminary definitions that will be used by the first linker
> pass, and superseded by the actual definitions in the subsequent ones.
>
> Make the preliminary definitions dependent on CONFIG_DEBUG_INFO_BTF so
> that inadvertent references to this section will trigger a link failure
> if they occur in code that does not honour CONFIG_DEBUG_INFO_BTF.
>
> Note that Clang will notice that taking the address of__start_BTF cannot
> yield NULL any longer, so testing for that condition is no longer
> needed.
>
> Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>

Acked-by: Arnd Bergmann <arnd@xxxxxxxx>