On Fri, Sep 15, 2023 at 09:42:20AM -0700, Nick Desaulniers wrote:
> Marcus and Satya reported an issue where BTF_ID macro generates same
> symbol in separate objects and that breaks final vmlinux link.
>
> ld.lld: error: ld-temp.o <inline asm>:14577:1: symbol
> '__BTF_ID__struct__cgroup__624' is already defined
>
> This can be triggered under specific configs when __COUNTER__ happens to
> be the same for the same symbol in two different translation units,
> which is already quite unlikely to happen.
>
> Add __LINE__ number suffix to make BTF_ID symbol more unique, which is
> not a complete fix, but it would help for now and meanwhile we can work
> on better solution as suggested by Andrii.
>
> Cc: [email protected]
> Reported-by: Satya Durga Srinivasu Prabhala <[email protected]>
> Reported-by: Marcus Seyfarth <[email protected]>
> Closes: https://github.com/ClangBuiltLinux/linux/issues/1913
> Tested-by: Marcus Seyfarth <[email protected]>
> Debugged-by: Nathan Chancellor <[email protected]>
> Co-developed-by: Jiri Olsa <[email protected]>
> Link: https://lore.kernel.org/bpf/CAEf4Bzb5KQ2_LmhN769ifMeSJaWfebccUasQOfQKaOd0nQ51tw@mail.gmail.com/
> Signed-off-by: Nick Desaulniers <[email protected]>
> ---
> tools/include/linux/btf_ids.h | 2 +-
Shouldn't this diff be in include/linux/btf_ids.h as well? Otherwise, I
don't think it will be used by the kernel build.
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/include/linux/btf_ids.h b/tools/include/linux/btf_ids.h
> index 71e54b1e3796..30e920b96a18 100644
> --- a/tools/include/linux/btf_ids.h
> +++ b/tools/include/linux/btf_ids.h
> @@ -38,7 +38,7 @@ asm( \
> ____BTF_ID(symbol)
>
> #define __ID(prefix) \
> - __PASTE(prefix, __COUNTER__)
> + __PASTE(prefix, __COUNTER__ __LINE__)
>
> /*
> * The BTF_ID defines unique symbol for each ID pointing
>
> ---
> base-commit: 9fdfb15a3dbf818e06be514f4abbfc071004cbe7
> change-id: 20230915-bpf_collision-36889a391d44
>
> Best regards,
> --
> Nick Desaulniers <[email protected]>
>
On Fri, Sep 15, 2023 at 10:18 AM Nathan Chancellor <[email protected]> wrote:
>
> On Fri, Sep 15, 2023 at 09:42:20AM -0700, Nick Desaulniers wrote:
> > Marcus and Satya reported an issue where BTF_ID macro generates same
> > symbol in separate objects and that breaks final vmlinux link.
> >
> > ld.lld: error: ld-temp.o <inline asm>:14577:1: symbol
> > '__BTF_ID__struct__cgroup__624' is already defined
> >
> > This can be triggered under specific configs when __COUNTER__ happens to
> > be the same for the same symbol in two different translation units,
> > which is already quite unlikely to happen.
> >
> > Add __LINE__ number suffix to make BTF_ID symbol more unique, which is
> > not a complete fix, but it would help for now and meanwhile we can work
> > on better solution as suggested by Andrii.
> >
> > Cc: [email protected]
> > Reported-by: Satya Durga Srinivasu Prabhala <[email protected]>
> > Reported-by: Marcus Seyfarth <[email protected]>
> > Closes: https://github.com/ClangBuiltLinux/linux/issues/1913
> > Tested-by: Marcus Seyfarth <[email protected]>
> > Debugged-by: Nathan Chancellor <[email protected]>
> > Co-developed-by: Jiri Olsa <[email protected]>
> > Link: https://lore.kernel.org/bpf/CAEf4Bzb5KQ2_LmhN769ifMeSJaWfebccUasQOfQKaOd0nQ51tw@mail.gmail.com/
> > Signed-off-by: Nick Desaulniers <[email protected]>
> > ---
> > tools/include/linux/btf_ids.h | 2 +-
>
> Shouldn't this diff be in include/linux/btf_ids.h as well? Otherwise, I
> don't think it will be used by the kernel build.
argh.
Let's do this patch as-is and another patch to update everything
in tools/../btf_ids.h, since it got out of sync quite a bit.