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LoongArch: Only use SC.Q when supported by the assembler 

The 128-bit atomic cmpxchg implementation uses the SC.Q instruction.
Older versions of GNU AS do not support that instruction, erroring out:

ERROR:root:{standard input}: Assembler messages:
{standard input}:4831: Error: no match insn: sc.q	$t0,$t1,$r14
{standard input}:6407: Error: no match insn: sc.q	$t0,$t1,$r23
{standard input}:10856: Error: no match insn: sc.q	$t0,$t1,$r14

make[4]: *** [../scripts/Makefile.build:289: mm/slub.o] Error 1

(Binutils 2.41)

So test support for SC.Q in Kconfig and disable the atomics if the
instruction is not available.

Fixes: f0e4b1b6e2 ("LoongArch: Add 128-bit atomic cmpxchg support")
Closes: https://lore.kernel.org/lkml/20260216082834-edc51c46-7b7a-4295-8ea5-4d9a3ca2224f@linutronix.de/
Reviewed-by: Xi Ruoyao <xry111@xry111.site>
Acked-by: Hengqi Chen <hengqi.chen@gmail.com>
Tested-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
This commit is contained in:
Thomas Weißschuh 2026-03-16 10:36:00 +08:00 committed by Huacai Chen
parent f338e77383
commit c8b8f3c50f
2 changed files with 8 additions and 0 deletions
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3
arch/loongarch/Kconfig
View File

@ -304,6 +304,9 @@ config AS_HAS_LBT_EXTENSION
config AS_HAS_LVZ_EXTENSION
def_bool $(as-instr,hvcl 0)
config AS_HAS_SCQ_EXTENSION
def_bool $(as-instr,sc.q \$t0$(comma)\$t1$(comma)\$t2)
config CC_HAS_ANNOTATE_TABLEJUMP
def_bool $(cc-option,-mannotate-tablejump)

5
arch/loongarch/include/asm/cmpxchg.h
View File

@ -238,6 +238,8 @@ __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, unsigned int
arch_cmpxchg((ptr), (o), (n)); \
})
#ifdef CONFIG_AS_HAS_SCQ_EXTENSION
union __u128_halves {
u128 full;
struct {
@ -290,6 +292,9 @@ union __u128_halves {
BUILD_BUG_ON(sizeof(*(ptr)) != 16); \
__arch_cmpxchg128(ptr, o, n, ""); \
})
#endif /* CONFIG_AS_HAS_SCQ_EXTENSION */
#else
#include <asm-generic/cmpxchg-local.h>
#define arch_cmpxchg64_local(ptr, o, n) __generic_cmpxchg64_local((ptr), (o), (n))