From f1b5644862c5b594f48ad01d7880a96b95d83a2f Mon Sep 17 00:00:00 2001 From: Paul E. McKenney Date: Thu, 30 May 2024 10:11:31 -0700 Subject: ARM: Emulate one-byte cmpxchg Use the new cmpxchg_emu_u8() to emulate one-byte cmpxchg() on ARM systems with ARCH == ARMv6K. [ paulmck: Apply Arnd Bergmann and Nathan Chancellor feedback. ] [ paulmck: Apply Linus Walleij feedback. ] Reported-by: Mark Brown Closes: https://lore.kernel.org/all/54798f68-48f7-4c65-9cba-47c0bf175143@sirena.org.uk/ Reported-by: Naresh Kamboju Closes: https://lore.kernel.org/all/CA+G9fYuZ+pf6p8AXMZWtdFtX-gbG8HMaBKp=XbxcdzA_QeLkxQ@mail.gmail.com/ Signed-off-by: Paul E. McKenney Tested-by: Nathan Chancellor Reviewed-by: Linus Walleij Cc: "Russell King (Oracle)" Cc: Arnd Bergmann Cc: Andrew Davis Cc: Andrew Morton Cc: Eric DeVolder Cc: Rob Herring Cc: --- arch/arm/Kconfig | 1 + arch/arm/include/asm/cmpxchg.h | 7 ++++++- 2 files changed, 7 insertions(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index ee5115252aac..a867a7d967aa 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -34,6 +34,7 @@ config ARM select ARCH_MIGHT_HAVE_PC_PARPORT select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if CPU_V7 + select ARCH_NEED_CMPXCHG_1_EMU if CPU_V6 select ARCH_SUPPORTS_ATOMIC_RMW select ARCH_SUPPORTS_CFI_CLANG select ARCH_SUPPORTS_HUGETLBFS if ARM_LPAE diff --git a/arch/arm/include/asm/cmpxchg.h b/arch/arm/include/asm/cmpxchg.h index 44667bdb4707..9beb64d30586 100644 --- a/arch/arm/include/asm/cmpxchg.h +++ b/arch/arm/include/asm/cmpxchg.h @@ -5,6 +5,7 @@ #include #include #include +#include #if defined(CONFIG_CPU_SA1100) || defined(CONFIG_CPU_SA110) /* @@ -162,7 +163,11 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, prefetchw((const void *)ptr); switch (size) { -#ifndef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */ +#ifdef CONFIG_CPU_V6 /* ARCH == ARMv6 */ + case 1: + oldval = cmpxchg_emu_u8((volatile u8 *)ptr, old, new); + break; +#else /* min ARCH > ARMv6 */ case 1: do { asm volatile("@ __cmpxchg1\n" -- cgit v1.2.3