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From: Nathan Chancellor <natechancellor@gmail.com>
To: Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Masahiro Yamada <masahiroy@kernel.org>
Cc: linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org,
	clang-built-linux@googlegroups.com, linux-kbuild@vger.kernel.org,
	Nick Desaulniers <ndesaulniers@google.com>,
	Sami Tolvanen <samitolvanen@google.com>,
	Dmitry Golovin <dima@golovin.in>,
	Sedat Dilek <sedat.dilek@gmail.com>
Subject: Re: [PATCH 2/2] MIPS: VDSO: Do not disable VDSO when linking with ld.lld
Date: Sun, 19 Apr 2020 11:17:15 -0700	[thread overview]
Message-ID: <20200419181715.GA36234@ubuntu-s3-xlarge-x86> (raw)
In-Reply-To: <20200419180445.26722-2-natechancellor@gmail.com>

On Sun, Apr 19, 2020 at 11:04:45AM -0700, Nathan Chancellor wrote:
> Currently, when linking with ld.lld, this warning pops up:
> 
>     arch/mips/vdso/Makefile:70: MIPS VDSO requires binutils >= 2.25
> 
> ld-ifversion calls ld-version, which calls scripts/ld-version.sh, which
> is specific to GNU ld. ld.lld has a completely different versioning
> scheme (as it follows LLVM's versioning) and it does not have the issue
> mentioned in the comment above this block so it should not be subjected
> to this check.
> 
> With this patch, the VDSO successfully links and shows P_MIPS_PC32 in
> vgettimeofday.o.
> 
> $ llvm-objdump -Dr arch/mips/vdso/vgettimeofday.o | grep R_MIPS_PC32
> 			00000024:  R_MIPS_PC32	_start
> 			000000b0:  R_MIPS_PC32	_start
> 			000002bc:  R_MIPS_PC32	_start
> 			0000036c:  R_MIPS_PC32	_start
> 			00000468:  R_MIPS_PC32	_start
> 
> Link: https://github.com/ClangBuiltLinux/linux/issues/785
> Link: https://github.com/llvm/llvm-project/commit/e364e2e9ce50c12eb2bf093560e1a1a8544d455a
> Reported-by: Dmitry Golovin <dima@golovin.in>
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
>  arch/mips/vdso/Makefile | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/mips/vdso/Makefile b/arch/mips/vdso/Makefile
> index d7fe8408603e..f99e583d14a1 100644
> --- a/arch/mips/vdso/Makefile
> +++ b/arch/mips/vdso/Makefile
> @@ -65,9 +65,11 @@ DISABLE_VDSO := n
>  # the comments on that file.
>  #
>  ifndef CONFIG_CPU_MIPSR6
> -  ifeq ($(call ld-ifversion, -lt, 225000000, y),y)
> -    $(warning MIPS VDSO requires binutils >= 2.25)
> -    DISABLE_VDSO := y
> +  ifndef CONFIG_LD_IS_LLD
> +    ifeq ($(call ld-ifversion, -lt, 225000000, y),y)
> +      $(warning MIPS VDSO requires binutils >= 2.25)
> +      DISABLE_VDSO := y
> +    endif
>    endif
>  endif
>  
> -- 
> 2.26.1
> 

Hmmm, I still see this warning when first runing make <config>... I
assume because this Makefile gets parsed before Kconfig runs.

Perhaps it would be better to check if ld-version is 0 (since that means
we are not using GNU ld):

ifneq ($(call ld-ifversion, -eq, 0, y),y)

I am open to suggestions though.

Cheers,
Nathan

  reply	other threads:[~2020-04-19 18:17 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-19 18:04 [PATCH 1/2] kbuild: add CONFIG_LD_IS_LLD Nathan Chancellor
2020-04-19 18:04 ` [PATCH 2/2] MIPS: VDSO: Do not disable VDSO when linking with ld.lld Nathan Chancellor
2020-04-19 18:17   ` Nathan Chancellor [this message]
2020-04-19 19:32     ` Masahiro Yamada
2020-04-19 20:05       ` Nathan Chancellor
2020-04-19 20:21 ` [PATCH v2 1/3] kbuild: add CONFIG_LD_IS_LLD Nathan Chancellor
2020-04-19 20:21   ` [PATCH v2 2/3] MIPS: VDSO: Move disabling the VDSO logic to Kconfig Nathan Chancellor
2020-04-20  9:53     ` Sedat Dilek
2020-04-21  2:42       ` Nathan Chancellor
2020-04-23 14:41         ` Masahiro Yamada
2020-04-19 20:21   ` [PATCH v2 3/3] MIPS: VDSO: Allow ld.lld to link the VDSO Nathan Chancellor
2020-04-23 14:38   ` [PATCH v2 1/3] kbuild: add CONFIG_LD_IS_LLD Masahiro Yamada
2020-04-23 17:18   ` [PATCH v3 1/4] " Nathan Chancellor
2020-04-23 17:18     ` [PATCH v3 2/4] MIPS: VDSO: Move disabling the VDSO logic to Kconfig Nathan Chancellor
2020-04-23 17:18     ` [PATCH v3 3/4] MIPS: VDSO: Use $(LD) instead of $(CC) to link VDSO Nathan Chancellor
2020-04-26 16:27       ` Thomas Bogendoerfer
2020-04-27  2:08         ` Nathan Chancellor
2020-04-27 16:22           ` Maciej W. Rozycki
2020-04-27 23:24             ` Nathan Chancellor
2020-04-29 17:46               ` Maciej W. Rozycki
2020-04-30  3:14                 ` Nathan Chancellor
2020-04-28  2:17         ` Nathan Chancellor
2020-04-23 17:18     ` [PATCH v3 4/4] MIPS: VDSO: Allow ld.lld to link the VDSO Nathan Chancellor
2020-04-28 22:14     ` [PATCH v5 0/5] Allow ld.lld to link the MIPS VDSO Nathan Chancellor
2020-04-28 22:14       ` [PATCH v4 1/5] kbuild: add CONFIG_LD_IS_LLD Nathan Chancellor
2020-04-29  7:13         ` Sedat Dilek
2020-04-30  3:05           ` Nathan Chancellor
2020-04-28 22:14       ` [PATCH v4 2/5] MIPS: VDSO: Move disabling the VDSO logic to Kconfig Nathan Chancellor
2020-04-28 22:14       ` [PATCH v4 3/5] MIPS: Unconditionally specify '-EB' or '-EL' Nathan Chancellor
2020-04-28 22:14       ` [PATCH v4 4/5] MIPS: VDSO: Use $(LD) instead of $(CC) to link VDSO Nathan Chancellor
2020-04-28 22:54         ` Fangrui Song
2020-04-29  0:44           ` Nathan Chancellor
2020-05-02 13:34           ` Maciej W. Rozycki
2020-05-02 13:50         ` Maciej W. Rozycki
2020-05-02 15:49           ` Nathan Chancellor
2020-04-28 22:14       ` [PATCH v4 5/5] MIPS: VDSO: Allow ld.lld to link the VDSO Nathan Chancellor
2020-04-29  7:04       ` [PATCH v5 0/5] Allow ld.lld to link the MIPS VDSO Sedat Dilek
2020-04-30  3:06         ` Nathan Chancellor
2020-05-12  8:05       ` Thomas Bogendoerfer
2020-05-12  8:28         ` Nathan Chancellor
2020-05-13 11:18           ` Thomas Bogendoerfer

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