On Fri, May 23, 2025 at 12:38 PM Xi Ruoyao xry111@xry111.site wrote:
On Thu, 2025-05-22 at 20:50 +0800, Huacai Chen wrote:
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 | ^
The "mask" of the csrxchg instruction should not be $r0 or $r1, but the compiler cannot avoid generating such code currently.
Maybe "to prevent the compiler from allocating $r0 or $r1, the 'q' constraint must be used but Clang < 22 does not support it. So force to use t0 in order to avoid using $r0/$r1 while keeping the backward compatibility."
OK, that's better.
Huacai
So force to use t0 in the inline asm, in order to avoid using $r0/$r1.
Cc: stable@vger.kernel.org Suggested-by: WANG Rui wangrui@loongson.cn Signed-off-by: Huacai Chen chenhuacai@loongson.cn
arch/loongarch/include/asm/irqflags.h | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/arch/loongarch/include/asm/irqflags.h b/arch/loongarch/include/asm/irqflags.h index 319a8c616f1f..003172b8406b 100644 --- a/arch/loongarch/include/asm/irqflags.h +++ b/arch/loongarch/include/asm/irqflags.h @@ -14,40 +14,48 @@ static inline void arch_local_irq_enable(void) { u32 flags = CSR_CRMD_IE;
register u32 mask asm("t0") = CSR_CRMD_IE;__asm__ __volatile__( "csrxchg %[val], %[mask], %[reg]\n\t" : [val] "+r" (flags)
: [mask] "r" (CSR_CRMD_IE), [reg] "i" (LOONGARCH_CSR_CRMD)
: [mask] "r" (mask), [reg] "i" (LOONGARCH_CSR_CRMD) : "memory");}
static inline void arch_local_irq_disable(void) { u32 flags = 0;
register u32 mask asm("t0") = CSR_CRMD_IE;__asm__ __volatile__( "csrxchg %[val], %[mask], %[reg]\n\t" : [val] "+r" (flags)
: [mask] "r" (CSR_CRMD_IE), [reg] "i" (LOONGARCH_CSR_CRMD)
: [mask] "r" (mask), [reg] "i" (LOONGARCH_CSR_CRMD) : "memory");}
static inline unsigned long arch_local_irq_save(void) { u32 flags = 0;
register u32 mask asm("t0") = CSR_CRMD_IE;__asm__ __volatile__( "csrxchg %[val], %[mask], %[reg]\n\t" : [val] "+r" (flags)
: [mask] "r" (CSR_CRMD_IE), [reg] "i" (LOONGARCH_CSR_CRMD)
: [mask] "r" (mask), [reg] "i" (LOONGARCH_CSR_CRMD) : "memory"); return flags;}
static inline void arch_local_irq_restore(unsigned long flags) {
register u32 mask asm("t0") = CSR_CRMD_IE;__asm__ __volatile__( "csrxchg %[val], %[mask], %[reg]\n\t" : [val] "+r" (flags)
: [mask] "r" (CSR_CRMD_IE), [reg] "i" (LOONGARCH_CSR_CRMD)
: [mask] "r" (mask), [reg] "i" (LOONGARCH_CSR_CRMD) : "memory");}
-- Xi Ruoyao xry111@xry111.site School of Aerospace Science and Technology, Xidian University