From: Nathan Chancellor <natechancellor@xxxxxxxxx>
[ Upstream commit 72cf3b3df423c1bbd8fa1056fed009d3a260f8a9 ]
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@xxxxxxxxx>
Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Tested-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Signed-off-by: Paul Burton <paulburton@xxxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: clang-built-linux@xxxxxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 bfb65b2d57c7f..2cf4b6131d88d 100644
--- a/arch/mips/vdso/Makefile
+++ b/arch/mips/vdso/Makefile
@@ -29,7 +29,7 @@ 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)
--
2.20.1
