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. ] Reported-by: Mark Brown <broonie@xxxxxxxxxx> Closes: https://lore.kernel.org/all/54798f68-48f7-4c65-9cba-47c0bf175143@xxxxxxxxxxxxx/ Reported-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx> Closes: https://lore.kernel.org/all/CA+G9fYuZ+pf6p8AXMZWtdFtX-gbG8HMaBKp=XbxcdzA_QeLkxQ@xxxxxxxxxxxxxx/ Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> Tested-by: Nathan Chancellor <nathan@xxxxxxxxxx> Cc: "Russell King (Oracle)" <rmk+kernel@xxxxxxxxxxxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> Cc: Andrew Davis <afd@xxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Linus Walleij <linus.walleij@xxxxxxxxxx> Cc: Eric DeVolder <eric.devolder@xxxxxxxxxx> Cc: Rob Herring <robh@xxxxxxxxxx> Cc: <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx> --- arch/arm/Kconfig | 1 + arch/arm/include/asm/cmpxchg.h | 7 ++++++- 2 files changed, 7 insertions(+), 1 deletion(-) diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index ee5115252aac4..a867a7d967aa5 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 44667bdb4707a..a428e06fe94ee 100644 --- a/arch/arm/include/asm/cmpxchg.h +++ b/arch/arm/include/asm/cmpxchg.h @@ -5,6 +5,7 @@ #include <linux/irqflags.h> #include <linux/prefetch.h> #include <asm/barrier.h> +#include <linux/cmpxchg-emu.h> #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 /* min ARCH < ARMv6K */ + case 1: + oldval = cmpxchg_emu_u8((volatile u8 *)ptr, old, new); + break; +#else /* min ARCH >= ARMv6K */ case 1: do { asm volatile("@ __cmpxchg1\n" -- 2.40.1
