[PATCH 5.4 19/27] arm64: alternative: fix build with clang integrated assembler

From: Greg Kroah-Hartman
Date: Wed Apr 01 2020 - 12:22:07 EST


From: Ilie Halip <ilie.halip@xxxxxxxxx>

commit 6f5459da2b8736720afdbd67c4bd2d1edba7d0e3 upstream.

Building an arm64 defconfig with clang's integrated assembler, this error
occurs:
<instantiation>:2:2: error: unrecognized instruction mnemonic
_ASM_EXTABLE 9999b, 9f
^
arch/arm64/mm/cache.S:50:1: note: while in macro instantiation
user_alt 9f, "dc cvau, x4", "dc civac, x4", 0
^

While GNU as seems fine with case-sensitive macro instantiations, clang
doesn't, so use the actual macro name (_asm_extable) as in the rest of
the file.

Also checked that the generated assembly matches the GCC output.

Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Tested-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Fixes: 290622efc76e ("arm64: fix "dc cvau" cache operation on errata-affected core")
Link: https://github.com/ClangBuiltLinux/linux/issues/924
Signed-off-by: Ilie Halip <ilie.halip@xxxxxxxxx>
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
arch/arm64/include/asm/alternative.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/arm64/include/asm/alternative.h
+++ b/arch/arm64/include/asm/alternative.h
@@ -221,7 +221,7 @@ alternative_endif

.macro user_alt, label, oldinstr, newinstr, cond
9999: alternative_insn "\oldinstr", "\newinstr", \cond
- _ASM_EXTABLE 9999b, \label
+ _asm_extable 9999b, \label
.endm

/*