[PATCH v2 0/4] locking/atomic: arch_cmpxchg[64]_local undefined

[PATCH v2 0/4] locking/atomic: arch_cmpxchg[64]_local undefined

[wuqiang.matt]

This patch series implement arch_cmpxchg[64]_local for arc,
openrisc and hexagon.

For architectures that support native cmpxchg, we'd like to
implement arch_cmpxchg[64]_local with the native variants of
supported data size. If not, the generci_cmpxchg[64]_local
will be used.

wuqiang.matt (4):
  locking/atomic: arc: data size checking in arch_cmpxchg
  locking/atomic: arc: arch_cmpxchg[64]_local undefined
  locking/atomic: openrisc: arch_cmpxchg[64]_local undefined
  locking/atomic: hexagon: arch_cmpxchg[64]_local undefined

 arch/arc/include/asm/cmpxchg.h      | 40 ++++++++++++++++++----
 arch/hexagon/include/asm/cmpxchg.h  | 51 ++++++++++++++++++++++++++++-
 arch/openrisc/include/asm/cmpxchg.h |  6 ++++
 3 files changed, 90 insertions(+), 7 deletions(-)

-- 
2.40.1

[PATCH v2 1/4] locking/atomic: arc: data size checking in arch_cmpxchg

[wuqiang.matt]

Macro __cmpxchg() renamed to __cmpxchg_32() to emphasize it's explicit
support of 32bit data size, BUILD_BUG_ON() added to avoid any possible
misuses with unsupported data types.

In case CONFIG_ARC_HAS_LLSC is undefined, arch_cmpxchg() uses spinlock
to accomplish SMP-safety, so the BUILD_BUG_ON checking is uncecessary.

Signed-off-by: wuqiang.matt <wuqiang.matt@bytedance.com>
---
 arch/arc/include/asm/cmpxchg.h | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/arc/include/asm/cmpxchg.h b/arch/arc/include/asm/cmpxchg.h
index e138fde067de..bf46514f6f12 100644
--- a/arch/arc/include/asm/cmpxchg.h
+++ b/arch/arc/include/asm/cmpxchg.h
@@ -18,14 +18,16 @@
  * if (*ptr == @old)
  *      *ptr = @new
  */
-#define __cmpxchg(ptr, old, new)					\
+#define __cmpxchg_32(ptr, old, new)					\
 ({									\
 	__typeof__(*(ptr)) _prev;					\
 									\
+	BUILD_BUG_ON(sizeof(*(ptr)) != 4);				\
+									\
 	__asm__ __volatile__(						\
-	"1:	llock  %0, [%1]	\n"					\
+	"1:	llock  %0, [%1]		\n"				\
 	"	brne   %0, %2, 2f	\n"				\
-	"	scond  %3, [%1]	\n"					\
+	"	scond  %3, [%1]		\n"				\
 	"	bnz     1b		\n"				\
 	"2:				\n"				\
 	: "=&r"(_prev)	/* Early clobber prevent reg reuse */		\
@@ -47,7 +49,7 @@
 									\
 	switch(sizeof((_p_))) {						\
 	case 4:								\
-		_prev_ = __cmpxchg(_p_, _o_, _n_);			\
+		_prev_ = __cmpxchg_32(_p_, _o_, _n_);			\
 		break;							\
 	default:							\
 		BUILD_BUG();						\
@@ -65,8 +67,6 @@
 	__typeof__(*(ptr)) _prev_;					\
 	unsigned long __flags;						\
 									\
-	BUILD_BUG_ON(sizeof(_p_) != 4);					\
-									\
 	/*								\
 	 * spin lock/unlock provide the needed smp_mb() before/after	\
 	 */								\
-- 
2.40.1

Re: [PATCH v2 1/4] locking/atomic: arc: data size checking in arch_cmpxchg

[Masami Hiramatsu]

On Sat,  4 Nov 2023 17:16:12 +0800
"wuqiang.matt" <wuqiang.matt@bytedance.com> wrote:

> Macro __cmpxchg() renamed to __cmpxchg_32() to emphasize it's explicit
> support of 32bit data size, BUILD_BUG_ON() added to avoid any possible
> misuses with unsupported data types.
> 
> In case CONFIG_ARC_HAS_LLSC is undefined, arch_cmpxchg() uses spinlock
> to accomplish SMP-safety, so the BUILD_BUG_ON checking is uncecessary.
> 

Looks good to me.

Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

> Signed-off-by: wuqiang.matt <wuqiang.matt@bytedance.com>
> ---
>  arch/arc/include/asm/cmpxchg.h | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/arc/include/asm/cmpxchg.h b/arch/arc/include/asm/cmpxchg.h
> index e138fde067de..bf46514f6f12 100644
> --- a/arch/arc/include/asm/cmpxchg.h
> +++ b/arch/arc/include/asm/cmpxchg.h
> @@ -18,14 +18,16 @@
>   * if (*ptr == @old)
>   *      *ptr = @new
>   */
> -#define __cmpxchg(ptr, old, new)					\
> +#define __cmpxchg_32(ptr, old, new)					\
>  ({									\
>  	__typeof__(*(ptr)) _prev;					\
>  									\
> +	BUILD_BUG_ON(sizeof(*(ptr)) != 4);				\
> +									\
>  	__asm__ __volatile__(						\
> -	"1:	llock  %0, [%1]	\n"					\
> +	"1:	llock  %0, [%1]		\n"				\
>  	"	brne   %0, %2, 2f	\n"				\
> -	"	scond  %3, [%1]	\n"					\
> +	"	scond  %3, [%1]		\n"				\
>  	"	bnz     1b		\n"				\
>  	"2:				\n"				\
>  	: "=&r"(_prev)	/* Early clobber prevent reg reuse */		\
> @@ -47,7 +49,7 @@
>  									\
>  	switch(sizeof((_p_))) {						\
>  	case 4:								\
> -		_prev_ = __cmpxchg(_p_, _o_, _n_);			\
> +		_prev_ = __cmpxchg_32(_p_, _o_, _n_);			\
>  		break;							\
>  	default:							\
>  		BUILD_BUG();						\
> @@ -65,8 +67,6 @@
>  	__typeof__(*(ptr)) _prev_;					\
>  	unsigned long __flags;						\
>  									\
> -	BUILD_BUG_ON(sizeof(_p_) != 4);					\
> -									\
>  	/*								\
>  	 * spin lock/unlock provide the needed smp_mb() before/after	\
>  	 */								\
> -- 
> 2.40.1
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>

[PATCH v2 2/4] locking/atomic: arc: arch_cmpxchg[64]_local undefined

[wuqiang.matt]

For architectures that support native cmpxchg, we'd like to
implement arch_cmpxchg[64]_local with the native variants of
supported data size. If not, the generci_cmpxchg[64]_local
will be used.

Signed-off-by: wuqiang.matt <wuqiang.matt@bytedance.com>
---
 arch/arc/include/asm/cmpxchg.h | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/arch/arc/include/asm/cmpxchg.h b/arch/arc/include/asm/cmpxchg.h
index bf46514f6f12..91429f2350df 100644
--- a/arch/arc/include/asm/cmpxchg.h
+++ b/arch/arc/include/asm/cmpxchg.h
@@ -80,6 +80,34 @@
 
 #endif
 
+/*
+ * always make arch_cmpxchg[64]_local available, native cmpxchg
+ * will be used if available, then generic_cmpxchg[64]_local
+ */
+#include <asm-generic/cmpxchg-local.h>
+static inline unsigned long __cmpxchg_local(volatile void *ptr,
+				      unsigned long old,
+				      unsigned long new, int size)
+{
+	switch (size) {
+#ifdef CONFIG_ARC_HAS_LLSC
+	case 4:
+		return __cmpxchg_32((int32_t *)ptr, old, new);
+#endif
+	default:
+		return __generic_cmpxchg_local(ptr, old, new, size);
+	}
+
+	return old;
+}
+#define arch_cmpxchg_local(ptr, o, n) ({				\
+	(__typeof__(*ptr))__cmpxchg_local((ptr),			\
+					(unsigned long)(o),		\
+					(unsigned long)(n),		\
+					sizeof(*(ptr)));		\
+})
+#define arch_cmpxchg64_local(ptr, o, n) __generic_cmpxchg64_local((ptr), (o), (n))
+
 /*
  * xchg
  */
-- 
2.40.1

Re: [PATCH v2 2/4] locking/atomic: arc: arch_cmpxchg[64]_local undefined

[Masami Hiramatsu]

On Sat,  4 Nov 2023 17:16:13 +0800
"wuqiang.matt" <wuqiang.matt@bytedance.com> wrote:

> For architectures that support native cmpxchg, we'd like to
> implement arch_cmpxchg[64]_local with the native variants of
> supported data size. If not, the generci_cmpxchg[64]_local
> will be used.
> 

Looks good to me.

Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

> Signed-off-by: wuqiang.matt <wuqiang.matt@bytedance.com>
> ---
>  arch/arc/include/asm/cmpxchg.h | 28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
> 
> diff --git a/arch/arc/include/asm/cmpxchg.h b/arch/arc/include/asm/cmpxchg.h
> index bf46514f6f12..91429f2350df 100644
> --- a/arch/arc/include/asm/cmpxchg.h
> +++ b/arch/arc/include/asm/cmpxchg.h
> @@ -80,6 +80,34 @@
>  
>  #endif
>  
> +/*
> + * always make arch_cmpxchg[64]_local available, native cmpxchg
> + * will be used if available, then generic_cmpxchg[64]_local
> + */
> +#include <asm-generic/cmpxchg-local.h>
> +static inline unsigned long __cmpxchg_local(volatile void *ptr,
> +				      unsigned long old,
> +				      unsigned long new, int size)
> +{
> +	switch (size) {
> +#ifdef CONFIG_ARC_HAS_LLSC
> +	case 4:
> +		return __cmpxchg_32((int32_t *)ptr, old, new);
> +#endif
> +	default:
> +		return __generic_cmpxchg_local(ptr, old, new, size);
> +	}
> +
> +	return old;
> +}
> +#define arch_cmpxchg_local(ptr, o, n) ({				\
> +	(__typeof__(*ptr))__cmpxchg_local((ptr),			\
> +					(unsigned long)(o),		\
> +					(unsigned long)(n),		\
> +					sizeof(*(ptr)));		\
> +})
> +#define arch_cmpxchg64_local(ptr, o, n) __generic_cmpxchg64_local((ptr), (o), (n))
> +
>  /*
>   * xchg
>   */
> -- 
> 2.40.1
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>

[PATCH v2 3/4] locking/atomic: openrisc: arch_cmpxchg[64]_local undefined

[wuqiang.matt]

For architectures that support native cmpxchg, we'd like to
implement arch_cmpxchg[64]_local with the native variants of
supported data size. If not, the generci_cmpxchg[64]_local
will be used.

Signed-off-by: wuqiang.matt <wuqiang.matt@bytedance.com>
---
 arch/openrisc/include/asm/cmpxchg.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/openrisc/include/asm/cmpxchg.h b/arch/openrisc/include/asm/cmpxchg.h
index 8ee151c072e4..f1ffe8b6f5ef 100644
--- a/arch/openrisc/include/asm/cmpxchg.h
+++ b/arch/openrisc/include/asm/cmpxchg.h
@@ -139,6 +139,12 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
 					       (unsigned long)(n),	\
 					       sizeof(*(ptr)));		\
 	})
+#define arch_cmpxchg_local arch_cmpxchg
+
+/* always make arch_cmpxchg64_local available for openrisc */
+#include <asm-generic/cmpxchg-local.h>
+
+#define arch_cmpxchg64_local(ptr, o, n) __generic_cmpxchg64_local((ptr), (o), (n))
 
 /*
  * This function doesn't exist, so you'll get a linker error if
-- 
2.40.1

Re: [PATCH v2 3/4] locking/atomic: openrisc: arch_cmpxchg[64]_local undefined

[Masami Hiramatsu]

On Sat,  4 Nov 2023 17:16:14 +0800
"wuqiang.matt" <wuqiang.matt@bytedance.com> wrote:

> For architectures that support native cmpxchg, we'd like to
> implement arch_cmpxchg[64]_local with the native variants of
> supported data size. If not, the generci_cmpxchg[64]_local
> will be used.


Looks good to me.

Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

> 
> Signed-off-by: wuqiang.matt <wuqiang.matt@bytedance.com>
> ---
>  arch/openrisc/include/asm/cmpxchg.h | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/openrisc/include/asm/cmpxchg.h b/arch/openrisc/include/asm/cmpxchg.h
> index 8ee151c072e4..f1ffe8b6f5ef 100644
> --- a/arch/openrisc/include/asm/cmpxchg.h
> +++ b/arch/openrisc/include/asm/cmpxchg.h
> @@ -139,6 +139,12 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
>  					       (unsigned long)(n),	\
>  					       sizeof(*(ptr)));		\
>  	})
> +#define arch_cmpxchg_local arch_cmpxchg
> +
> +/* always make arch_cmpxchg64_local available for openrisc */
> +#include <asm-generic/cmpxchg-local.h>
> +
> +#define arch_cmpxchg64_local(ptr, o, n) __generic_cmpxchg64_local((ptr), (o), (n))
>  
>  /*
>   * This function doesn't exist, so you'll get a linker error if
> -- 
> 2.40.1
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>

[PATCH v2 4/4] locking/atomic: hexagon: arch_cmpxchg[64]_local undefined

[wuqiang.matt]

For architectures that support native cmpxchg, we'd like to
implement arch_cmpxchg[64]_local with the native variants of
supported data size. If not, the generci_cmpxchg[64]_local
will be used.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202310272207.tLPflya4-lkp@intel.com/

Signed-off-by: wuqiang.matt <wuqiang.matt@bytedance.com>
---
 arch/hexagon/include/asm/cmpxchg.h | 51 +++++++++++++++++++++++++++++-
 1 file changed, 50 insertions(+), 1 deletion(-)

diff --git a/arch/hexagon/include/asm/cmpxchg.h b/arch/hexagon/include/asm/cmpxchg.h
index bf6cf5579cf4..2b5e5bbaf807 100644
--- a/arch/hexagon/include/asm/cmpxchg.h
+++ b/arch/hexagon/include/asm/cmpxchg.h
@@ -8,6 +8,8 @@
 #ifndef _ASM_CMPXCHG_H
 #define _ASM_CMPXCHG_H
 
+#include <linux/build_bug.h>
+
 /*
  * __arch_xchg - atomically exchange a register and a memory location
  * @x: value to swap
@@ -51,13 +53,15 @@ __arch_xchg(unsigned long x, volatile void *ptr, int size)
  *  variable casting.
  */
 
-#define arch_cmpxchg(ptr, old, new)				\
+#define __cmpxchg_32(ptr, old, new)				\
 ({								\
 	__typeof__(ptr) __ptr = (ptr);				\
 	__typeof__(*(ptr)) __old = (old);			\
 	__typeof__(*(ptr)) __new = (new);			\
 	__typeof__(*(ptr)) __oldval = 0;			\
 								\
+	BUILD_BUG_ON(sizeof(*(ptr)) != 4);			\
+								\
 	asm volatile(						\
 		"1:	%0 = memw_locked(%1);\n"		\
 		"	{ P0 = cmp.eq(%0,%2);\n"		\
@@ -72,4 +76,49 @@ __arch_xchg(unsigned long x, volatile void *ptr, int size)
 	__oldval;						\
 })
 
+#define __cmpxchg(ptr, old, val, size)				\
+({								\
+	__typeof__(*(ptr)) oldval;				\
+								\
+	switch (size) {						\
+	case 4:							\
+		oldval = __cmpxchg_32(ptr, old, val);		\
+		break;						\
+	default:						\
+		BUILD_BUG();					\
+		oldval = val;					\
+		break;						\
+	}							\
+								\
+	oldval;							\
+})
+
+#define arch_cmpxchg(ptr, o, n)	__cmpxchg((ptr), (o), (n), sizeof(*(ptr)))
+
+/*
+ * always make arch_cmpxchg[64]_local available, native cmpxchg
+ * will be used if available, then generic_cmpxchg[64]_local
+ */
+#include <asm-generic/cmpxchg-local.h>
+
+#define arch_cmpxchg_local(ptr, old, val)			\
+({								\
+	__typeof__(*(ptr)) retval;				\
+	int size = sizeof(*(ptr));				\
+								\
+	switch (size) {						\
+	case 4:							\
+		retval = __cmpxchg_32(ptr, old, val);		\
+		break;						\
+	default:						\
+		retval = __generic_cmpxchg_local(ptr, old,	\
+						 val, size);	\
+		break;						\
+	}							\
+								\
+	retval;							\
+})
+
+#define arch_cmpxchg64_local(ptr, o, n) __generic_cmpxchg64_local((ptr), (o), (n))
+
 #endif /* _ASM_CMPXCHG_H */
-- 
2.40.1

Re: [PATCH v2 4/4] locking/atomic: hexagon: arch_cmpxchg[64]_local undefined

[Masami Hiramatsu]

On Sat,  4 Nov 2023 17:16:15 +0800
"wuqiang.matt" <wuqiang.matt@bytedance.com> wrote:

> For architectures that support native cmpxchg, we'd like to
> implement arch_cmpxchg[64]_local with the native variants of
> supported data size. If not, the generci_cmpxchg[64]_local
> will be used.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202310272207.tLPflya4-lkp@intel.com/
> 

Looks good to me.

Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

But I need hexagon's maintainer's comment too.

Thank you,

> Signed-off-by: wuqiang.matt <wuqiang.matt@bytedance.com>
> ---
>  arch/hexagon/include/asm/cmpxchg.h | 51 +++++++++++++++++++++++++++++-
>  1 file changed, 50 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/hexagon/include/asm/cmpxchg.h b/arch/hexagon/include/asm/cmpxchg.h
> index bf6cf5579cf4..2b5e5bbaf807 100644
> --- a/arch/hexagon/include/asm/cmpxchg.h
> +++ b/arch/hexagon/include/asm/cmpxchg.h
> @@ -8,6 +8,8 @@
>  #ifndef _ASM_CMPXCHG_H
>  #define _ASM_CMPXCHG_H
>  
> +#include <linux/build_bug.h>
> +
>  /*
>   * __arch_xchg - atomically exchange a register and a memory location
>   * @x: value to swap
> @@ -51,13 +53,15 @@ __arch_xchg(unsigned long x, volatile void *ptr, int size)
>   *  variable casting.
>   */
>  
> -#define arch_cmpxchg(ptr, old, new)				\
> +#define __cmpxchg_32(ptr, old, new)				\
>  ({								\
>  	__typeof__(ptr) __ptr = (ptr);				\
>  	__typeof__(*(ptr)) __old = (old);			\
>  	__typeof__(*(ptr)) __new = (new);			\
>  	__typeof__(*(ptr)) __oldval = 0;			\
>  								\
> +	BUILD_BUG_ON(sizeof(*(ptr)) != 4);			\
> +								\
>  	asm volatile(						\
>  		"1:	%0 = memw_locked(%1);\n"		\
>  		"	{ P0 = cmp.eq(%0,%2);\n"		\
> @@ -72,4 +76,49 @@ __arch_xchg(unsigned long x, volatile void *ptr, int size)
>  	__oldval;						\
>  })
>  
> +#define __cmpxchg(ptr, old, val, size)				\
> +({								\
> +	__typeof__(*(ptr)) oldval;				\
> +								\
> +	switch (size) {						\
> +	case 4:							\
> +		oldval = __cmpxchg_32(ptr, old, val);		\
> +		break;						\
> +	default:						\
> +		BUILD_BUG();					\
> +		oldval = val;					\
> +		break;						\
> +	}							\
> +								\
> +	oldval;							\
> +})
> +
> +#define arch_cmpxchg(ptr, o, n)	__cmpxchg((ptr), (o), (n), sizeof(*(ptr)))
> +
> +/*
> + * always make arch_cmpxchg[64]_local available, native cmpxchg
> + * will be used if available, then generic_cmpxchg[64]_local
> + */
> +#include <asm-generic/cmpxchg-local.h>
> +
> +#define arch_cmpxchg_local(ptr, old, val)			\
> +({								\
> +	__typeof__(*(ptr)) retval;				\
> +	int size = sizeof(*(ptr));				\
> +								\
> +	switch (size) {						\
> +	case 4:							\
> +		retval = __cmpxchg_32(ptr, old, val);		\
> +		break;						\
> +	default:						\
> +		retval = __generic_cmpxchg_local(ptr, old,	\
> +						 val, size);	\
> +		break;						\
> +	}							\
> +								\
> +	retval;							\
> +})
> +
> +#define arch_cmpxchg64_local(ptr, o, n) __generic_cmpxchg64_local((ptr), (o), (n))
> +
>  #endif /* _ASM_CMPXCHG_H */
> -- 
> 2.40.1
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>