clang and gas seem to interpret the symbols in memmove_64.S and memset_64.S differently, such that clang does not make them 'weak' as expected, which leads to a linker error, with both ld.bfd and ld.lld: ld.lld: error: duplicate symbol: memmove >>> defined at common.c >>> kasan/common.o:(memmove) in archive mm/built-in.a >>> defined at memmove.o:(__memmove) in archive arch/arm64/lib/lib.a ld.lld: error: duplicate symbol: memset >>> defined at common.c >>> kasan/common.o:(memset) in archive mm/built-in.a >>> defined at memset.o:(__memset) in archive arch/arm64/lib/lib.a Copy the exact way these are written in memcpy_64.S, which does not have the same problem. I don't know why this makes a difference, and it would be good to have someone with a better understanding of assembler internals review it. It might be either a bug in the kernel or a bug in the assembler, no idea which one. My patch makes it work with all versions of clang and gcc, which is probably helpful even if it's a workaround for a clang bug. Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> --- arch/x86/lib/memmove_64.S | 4 ++-- arch/x86/lib/memset_64.S | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/x86/lib/memmove_64.S b/arch/x86/lib/memmove_64.S index 7ff00ea64e4f..dcca01434be8 100644 --- a/arch/x86/lib/memmove_64.S +++ b/arch/x86/lib/memmove_64.S @@ -26,8 +26,8 @@ */ .weak memmove -SYM_FUNC_START_ALIAS(memmove) -SYM_FUNC_START(__memmove) +SYM_FUNC_START_ALIAS(__memmove) +SYM_FUNC_START_LOCAL(memmove) mov %rdi, %rax diff --git a/arch/x86/lib/memset_64.S b/arch/x86/lib/memset_64.S index 9ff15ee404a4..a97f2ea4e0b2 100644 --- a/arch/x86/lib/memset_64.S +++ b/arch/x86/lib/memset_64.S @@ -19,8 +19,8 @@ * * rax original destination */ -SYM_FUNC_START_ALIAS(memset) -SYM_FUNC_START(__memset) +SYM_FUNC_START_ALIAS(__memset) +SYM_FUNC_START_LOCAL(memset) /* * Some CPUs support enhanced REP MOVSB/STOSB feature. It is recommended * to use it when possible. If not available, use fast string instructions. -- 2.26.2
