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From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Fri, 14 Apr 2023 02:53:05 +0900
Message-ID: <CAK7LNATyYS2WA9kGQ9=OK+Xn5KdnG9bmcxSKE4=9Z5jc2kr+uA@mail.gmail.com>
Subject: Re: [PATCH v3] Makefile: use -z pack-relative-relocs
To:     Will Deacon <will@kernel.org>
Cc:     Fangrui Song <maskray@google.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
        Peter Collingbourne <pcc@google.com>
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On Thu, Apr 13, 2023 at 11:55=E2=80=AFPM Will Deacon <will@kernel.org> wrot=
e:
>
> 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.d=
yn'
> >
> > 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=3Drelr as well for older LLD versions=
.
> > There is no indication of obsolescence for --pack-dyn-relocs=3Drelr.
> >
> > As of today, GNU ld supports the latter option for x86 and powerpc64
> > ports and has no intention to support --pack-dyn-relocs=3Drelr. In the
> > absence of the glibc symbol version GLIBC_ABI_DT_RELR,
> > --pack-dyn-relocs=3Drelr and -z pack-relative-relocs are identical in
> > ld.lld.
> >
> > GNU ld and newer versions of LLD report warnings (instead of errors) fo=
r
> > unknown -z options. Only errors lead to non-zero exit codes. Therefore,
> > we should test --pack-dyn-relocs=3Drelr before testing
> > -z pack-relative-relocs.
> >
> > Link: https://github.com/ClangBuiltLinux/linux/issues/1057
> > Link: https://sourceware.org/git/?p=3Dbinutils-gdb.git;a=3Dcommit;h=3Da=
619b58721f0a03fd91c27670d3e4c2fb0d88f1e
> > 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?


Sure. Applied to linux-kbuild.


(I will push it next week.)


> If not, I can take it via
> arm64 (as the only arch currently using this reloc format).
>
> Cheers,
>
> Will


--=20
Best Regards
Masahiro Yamada