From: Nathan Chancellor <natechancellor@gmail.com>
To: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paulburton@kernel.org>,
linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org,
clang-built-linux@googlegroups.com,
Nathan Chancellor <natechancellor@gmail.com>
Subject: [PATCH] MIPS: vdso: Wrap -mexplicit-relocs in cc-option
Date: Mon, 17 Feb 2020 14:11:49 -0700 [thread overview]
Message-ID: <20200217211149.44132-1-natechancellor@gmail.com> (raw)
Clang does not support this option and errors out:
clang-11: error: unknown argument: '-mexplicit-relocs'
Clang does not appear to need this flag like GCC does because the jalr
check that was added in commit 976c23af3ee5 ("mips: vdso: add build
time check that no 'jalr t9' calls left") passes just fine with
$ make ARCH=mips CC=clang CROSS_COMPILE=mipsel-linux-gnu- malta_defconfig arch/mips/vdso/
even before commit d3f703c4359f ("mips: vdso: fix 'jalr t9' crash in
vdso code").
-mrelax-pic-calls has been supported since clang 9, which is the
earliest version that could build a working MIPS kernel, and it is the
default for clang so just leave it be.
Fixes: d3f703c4359f ("mips: vdso: fix 'jalr t9' crash in vdso code")
Link: https://github.com/ClangBuiltLinux/linux/issues/890
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
---
arch/mips/vdso/Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/mips/vdso/Makefile b/arch/mips/vdso/Makefile
index 77374c1f0c77..d7fe8408603e 100644
--- a/arch/mips/vdso/Makefile
+++ b/arch/mips/vdso/Makefile
@@ -33,7 +33,7 @@ endif
cflags-vdso := $(ccflags-vdso) \
$(filter -W%,$(filter-out -Wa$(comma)%,$(KBUILD_CFLAGS))) \
-O3 -g -fPIC -fno-strict-aliasing -fno-common -fno-builtin -G 0 \
- -mrelax-pic-calls -mexplicit-relocs \
+ -mrelax-pic-calls $(call cc-option, -mexplicit-relocs) \
-fno-stack-protector -fno-jump-tables -DDISABLE_BRANCH_PROFILING \
$(call cc-option, -fno-asynchronous-unwind-tables) \
$(call cc-option, -fno-stack-protector)
--
2.25.1
next reply other threads:[~2020-02-17 21:11 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-17 21:11 Nathan Chancellor [this message]
2020-02-18 18:28 ` [PATCH] MIPS: vdso: Wrap -mexplicit-relocs in cc-option Nick Desaulniers
2020-02-18 18:30 ` Nathan Chancellor
2020-02-19 19:01 ` Paul Burton
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