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Huacai Chen d46f8f1ede LoongArch: Avoid using $r0/$r1 as "mask" for csrxchg commit `52c22661c7` upstream. When building kernel with LLVM there are occasionally such errors: In file included from ./include/linux/spinlock.h:59: In file included from ./include/linux/irqflags.h:17: arch/loongarch/include/asm/irqflags.h:38:3: error: must not be $r0 or $r1 38 \| "csrxchg %[val], %[mask], %[reg]\n\t" \| ^ <inline asm>:1:16: note: instantiated into assembly here 1 \| csrxchg $a1, $ra, 0 \| ^ To prevent the compiler from allocating $r0 or $r1 for the "mask" of the csrxchg instruction, the 'q' constraint must be used but Clang < 21 does not support it. So force to use $t0 in the inline asm, in order to avoid using $r0/$r1 while keeping the backward compatibility. Cc: stable@vger.kernel.org Link: https://github.com/llvm/llvm-project/pull/141037 Reviewed-by: Yanteng Si <si.yanteng@linux.dev> Suggested-by: WANG Rui <wangrui@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>	History 2025-06-27 11:11:37 +01:00
..
asm	LoongArch: Avoid using $r0/$r1 as "mask" for csrxchg	2025-06-27 11:11:37 +01:00
uapi/asm	LoongArch: Extend the maximum number of watchpoints	2025-02-17 10:05:18 +01:00

Huacai Chen d46f8f1ede LoongArch: Avoid using $r0/$r1 as "mask" for csrxchg

commit 52c22661c7 upstream.

When building kernel with LLVM there are occasionally such errors:

In file included from ./include/linux/spinlock.h:59:
In file included from ./include/linux/irqflags.h:17:
arch/loongarch/include/asm/irqflags.h:38:3: error: must not be $r0 or $r1
   38 |                 "csrxchg %[val], %[mask], %[reg]\n\t"
      |                 ^
<inline asm>:1:16: note: instantiated into assembly here
    1 |         csrxchg $a1, $ra, 0
      |                       ^

To prevent the compiler from allocating $r0 or $r1 for the "mask" of the
csrxchg instruction, the 'q' constraint must be used but Clang < 21 does
not support it. So force to use $t0 in the inline asm, in order to avoid
using $r0/$r1 while keeping the backward compatibility.

Cc: stable@vger.kernel.org
Link: https://github.com/llvm/llvm-project/pull/141037
Reviewed-by: Yanteng Si <si.yanteng@linux.dev>
Suggested-by: WANG Rui <wangrui@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

History

2025-06-27 11:11:37 +01:00

asm LoongArch: Avoid using $r0/$r1 as "mask" for csrxchg 2025-06-27 11:11:37 +01:00

uapi/asm LoongArch: Extend the maximum number of watchpoints 2025-02-17 10:05:18 +01:00