* [PATCH] LoongArch: Avoid using $r0/$r1 as "mask" for csrxchg
@ 2025-05-22 12:50 Huacai Chen
2025-05-23 4:38 ` Xi Ruoyao
2025-05-23 6:43 ` Yanteng Si
0 siblings, 2 replies; 4+ messages in thread
From: Huacai Chen @ 2025-05-22 12:50 UTC (permalink / raw)
To: Huacai Chen
Cc: loongarch, Xuefeng Li, Guo Ren, Xuerui Wang, Jiaxun Yang,
linux-kernel, Huacai Chen, stable, WANG Rui
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. 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");
}
--
2.47.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] LoongArch: Avoid using $r0/$r1 as "mask" for csrxchg
2025-05-22 12:50 [PATCH] LoongArch: Avoid using $r0/$r1 as "mask" for csrxchg Huacai Chen
@ 2025-05-23 4:38 ` Xi Ruoyao
2025-05-23 4:51 ` Huacai Chen
2025-05-23 6:43 ` Yanteng Si
1 sibling, 1 reply; 4+ messages in thread
From: Xi Ruoyao @ 2025-05-23 4:38 UTC (permalink / raw)
To: Huacai Chen, Huacai Chen
Cc: loongarch, Xuefeng Li, Guo Ren, Xuerui Wang, Jiaxun Yang,
linux-kernel, stable, WANG Rui
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."
And Link: https://github.com/llvm/llvm-project/pull/141037
> 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
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] LoongArch: Avoid using $r0/$r1 as "mask" for csrxchg
2025-05-23 4:38 ` Xi Ruoyao
@ 2025-05-23 4:51 ` Huacai Chen
0 siblings, 0 replies; 4+ messages in thread
From: Huacai Chen @ 2025-05-23 4:51 UTC (permalink / raw)
To: Xi Ruoyao
Cc: Huacai Chen, loongarch, Xuefeng Li, Guo Ren, Xuerui Wang,
Jiaxun Yang, linux-kernel, stable, WANG Rui
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."
>
> And Link: https://github.com/llvm/llvm-project/pull/141037
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
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] LoongArch: Avoid using $r0/$r1 as "mask" for csrxchg
2025-05-22 12:50 [PATCH] LoongArch: Avoid using $r0/$r1 as "mask" for csrxchg Huacai Chen
2025-05-23 4:38 ` Xi Ruoyao
@ 2025-05-23 6:43 ` Yanteng Si
1 sibling, 0 replies; 4+ messages in thread
From: Yanteng Si @ 2025-05-23 6:43 UTC (permalink / raw)
To: Huacai Chen, Huacai Chen
Cc: loongarch, Xuefeng Li, Guo Ren, Xuerui Wang, Jiaxun Yang,
linux-kernel, stable, WANG Rui
在 5/22/25 8:50 PM, Huacai Chen 写道:
> 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. 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>
Reviewed-by: Yanteng Si <si.yanteng@linux.dev>
Thanks,
Yanteng
> ---
> 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");
> }
>
^ permalink raw reply [flat|nested] 4+ messages in thread
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2025-05-22 12:50 [PATCH] LoongArch: Avoid using $r0/$r1 as "mask" for csrxchg Huacai Chen
2025-05-23 4:38 ` Xi Ruoyao
2025-05-23 4:51 ` Huacai Chen
2025-05-23 6:43 ` Yanteng Si
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