Re: [PATCH] rust: Makefile: apply fixed-x18 workaround only on arm64

[Charalampos Mitrodimas]

HeeSu Kim <mlksvender@xxxxxxxxx> writes:

> The `-Cunsafe-allow-abi-mismatch=fixed-x18` option is a workaround for
> a rustdoc issue (rust-lang/rust#144521) where target modifiers were not
> properly saved. This affects both rustdoc and doctests builds.
>
> However, `fixed-x18` is an ARM64-specific ABI modifier related to the
> x18 register reservation (used for Shadow Call Stack). Currently, this
> workaround is applied unconditionally on all architectures, which is
> incorrect and may cause issues on non-ARM64 builds.
>
> Restrict the workaround to only apply when building for arm64
> (SRCARCH=arm64).
>
> Fixes: 68e8e79e1bdc ("rust: fix `rustdoc` target modifiers")

Are we sure this is in the correct commit hash? It is not present on
mainline.

Maybe it should be this one?

      Fixes: abbf9a449441 ("rust: workaround `rustdoc` target modifiers bug")

Cheers,
C. Mitrodimas

> Signed-off-by: HeeSu Kim <mlksvender@xxxxxxxxx>
> ---
>  rust/Makefile | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/rust/Makefile b/rust/Makefile
> index 5c0155b83..2bd547611 100644
> --- a/rust/Makefile
> +++ b/rust/Makefile
> @@ -136,7 +136,8 @@ pin_init-flags := \
>  
>  # `rustdoc` did not save the target modifiers, thus workaround for
>  # the time being (https://github.com/rust-lang/rust/issues/144521).
> -rustdoc_modifiers_workaround := $(if $(call rustc-min-version,108800),-Cunsafe-allow-abi-mismatch=fixed-x18)
> +# The `fixed-x18` modifier is ARM64-specific, so only apply it there.
> +rustdoc_modifiers_workaround := $(if $(filter arm64,$(SRCARCH)),$(if
> $(call
> rustc-min-version,108800),-Cunsafe-allow-abi-mismatch=fixed-x18))
>  
>  # Similarly, for doctests (https://github.com/rust-lang/rust/issues/146465).
>  doctests_modifiers_workaround := $(rustdoc_modifiers_workaround)$(if
> $(call rustc-min-version,109100),$(comma)sanitizer)