[PATCH v2 cmpxchg 11/13] csky: Emulate one-byte cmpxchg

Paul E. McKenney
2024-05-01T23:01:32Z

Use the new cmpxchg_emu_u8() to emulate one-byte cmpxchg() on csky.

[ paulmck: Apply kernel test robot feedback. ]
[ paulmck: Drop two-byte support per Arnd Bergmann feedback. ]

Co-developed-by: Yujie Liu <yujie.liu@intel.com>
Signed-off-by: Yujie Liu <yujie.liu@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Yujie Liu <yujie.liu@intel.com>
Cc: Guo Ren <guoren@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: <linux-csky@vger.kernel.org>
---
arch/csky/Kconfig | 1 +
arch/csky/include/asm/cmpxchg.h | 10 ++++++++++
2 files changed, 11 insertions(+)

diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
index d3ac36751ad1f..5479707eb5d10 100644
--- a/arch/csky/Kconfig
+++ b/arch/csky/Kconfig
@@ -37,6 +37,7 @@ config CSKY
select ARCH_INLINE_SPIN_UNLOCK_BH if !PREEMPTION
select ARCH_INLINE_SPIN_UNLOCK_IRQ if !PREEMPTION
select ARCH_INLINE_SPIN_UNLOCK_IRQRESTORE if !PREEMPTION
+ select ARCH_NEED_CMPXCHG_1_EMU
select ARCH_WANT_FRAME_POINTERS if !CPU_CK610 && $(cc-option,-mbacktrace)
select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
select COMMON_CLK
diff --git a/arch/csky/include/asm/cmpxchg.h b/arch/csky/include/asm/cmpxchg.h
index 916043b845f14..db6dda47184e4 100644
--- a/arch/csky/include/asm/cmpxchg.h
+++ b/arch/csky/include/asm/cmpxchg.h
@@ -6,6 +6,7 @@
#ifdef CONFIG_SMP
#include <linux/bug.h>
#include <asm/barrier.h>
+#include <linux/cmpxchg-emu.h>

#define __xchg_relaxed(new, ptr, size) \
({ \
@@ -61,6 +62,9 @@
__typeof__(old) __old = (old); \
__typeof__(*(ptr)) __ret; \
switch (size) { \
+ case 1: \
+ __ret = (__typeof__(*(ptr)))cmpxchg_emu_u8((volatile u8 *)__ptr, (uintptr_t)__old, (uintptr_t)__new); \
+ break; \
case 4: \
asm volatile ( \
"1: ldex.w %0, (%3) \n" \
@@ -91,6 +95,9 @@
__typeof__(old) __old = (old); \
__typeof__(*(ptr)) __ret; \
switch (size) { \
+ case 1: \
+ __ret = (__typeof__(*(ptr)))cmpxchg_emu_u8((volatile u8 *)__ptr, (uintptr_t)__old, (uintptr_t)__new); \
+ break; \
case 4: \
asm volatile ( \
"1: ldex.w %0, (%3) \n" \
@@ -122,6 +129,9 @@
__typeof__(old) __old = (old); \
__typeof__(*(ptr)) __ret; \
switch (size) { \
+ case 1: \
+ __ret = (__typeof__(*(ptr)))cmpxchg_emu_u8((volatile u8 *)__ptr, (uintptr_t)__old, (uintptr_t)__new); \
+ break; \
case 4: \
asm volatile ( \
RELEASE_FENCE \
--
2.40.1