Re: [PATCH v3] Makefile: use -z pack-relative-relocs

[Will Deacon <will@kernel.org>]

On Tue, Apr 11, 2023 at 08:09:44PM +0000, Fangrui Song wrote:
> Commit 27f2a4db76e8 ("Makefile: fix GDB warning with CONFIG_RELR")
> added --use-android-relr-tags to fix a GDB warning
> 
> BFD: /android0/linux-next/vmlinux: unknown type [0x13] section `.relr.dyn'
> 
> The GDB warning has been fixed in version 11.2.
> 
> The DT_ANDROID_RELR tag was deprecated since DT_RELR was standardized.
> Thus, --use-android-relr-tags should be removed. While making the
> change, try -z pack-relative-relocs, which is supported since LLD 15.
> Keep supporting --pack-dyn-relocs=relr as well for older LLD versions.
> There is no indication of obsolescence for --pack-dyn-relocs=relr.
> 
> As of today, GNU ld supports the latter option for x86 and powerpc64
> ports and has no intention to support --pack-dyn-relocs=relr. In the
> absence of the glibc symbol version GLIBC_ABI_DT_RELR,
> --pack-dyn-relocs=relr and -z pack-relative-relocs are identical in
> ld.lld.
> 
> GNU ld and newer versions of LLD report warnings (instead of errors) for
> unknown -z options. Only errors lead to non-zero exit codes. Therefore,
> we should test --pack-dyn-relocs=relr before testing
> -z pack-relative-relocs.
> 
> Link: https://github.com/ClangBuiltLinux/linux/issues/1057
> Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=a619b58721f0a03fd91c27670d3e4c2fb0d88f1e
> Signed-off-by: Fangrui Song <maskray@google.com>
> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
> ---
>  Makefile                      | 3 ++-
>  scripts/tools-support-relr.sh | 8 ++++++--
>  2 files changed, 8 insertions(+), 3 deletions(-)

Acked-by: Will Deacon <will@kernel.org>

Masahiro -- are you happy to pick this one up? If not, I can take it via
arm64 (as the only arch currently using this reloc format).

Cheers,

Will