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ARM: Emulate one-byte cmpxchg

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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 <broonie@kernel.org>
Closes: https://lore.kernel.org/all/54798f68-48f7-4c65-9cba-47c0bf175143@sirena.org.uk/
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Closes: https://lore.kernel.org/all/CA+G9fYuZ+pf6p8AXMZWtdFtX-gbG8HMaBKp=XbxcdzA_QeLkxQ@mail.gmail.com/
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Cc: "Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Andrew Davis <afd@ti.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Eric DeVolder <eric.devolder@oracle.com>
Cc: Rob Herring <robh@kernel.org>
Cc: <linux-arm-kernel@lists.infradead.org>
This commit is contained in:
Paul E. McKenney 2024-05-30 10:11:31 -07:00
parent 1613e604df
commit f1b5644862
2 changed files with 7 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/arm/Kconfig
View File

@ -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

7
arch/arm/include/asm/cmpxchg.h
View File

@ -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 /* 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"