Commit c8b8f3c5 authored by Thomas Weißschuh's avatar Thomas Weißschuh Committed by Huacai Chen
Browse files

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: f0e4b1b6 ("LoongArch: Add 128-bit atomic cmpxchg support")
Closes: https://lore.kernel.org/lkml/20260216082834-edc51c46-7b7a-4295-8ea5-4d9a3ca2224f@linutronix.de/


Reviewed-by: default avatarXi Ruoyao <xry111@xry111.site>
Acked-by: default avatarHengqi Chen <hengqi.chen@gmail.com>
Tested-by: default avatarHengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: default avatarThomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
parent f338e773

arch/loongarch/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -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)

arch/loongarch/include/asm/cmpxchg.h

+5 −0
Original line number Diff line number Diff line
@@ -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))