Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'cmpxchg.2024.07.12a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu
Pull arm byte cmpxchg from Paul McKenney:
"ARM: Provide one-byte cmpxchg emulation
This provides emulated one-byte cmpxchg() support for ARM using the
cmpxchg_emu_u8() function that uses a four-byte cmpxchg() to emulate
the one-byte variant.
Similar patches for emulation of one-byte cmpxchg() for arc, sh, and
xtensa have not yet received maintainer acks, so they are slated for
the v6.12 merge window"
* tag 'cmpxchg.2024.07.12a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
ARM: Emulate one-byte cmpxchg
+7
-1
+1
arch/arm/Kconfig
+1
arch/arm/Kconfig
···
34
34
select ARCH_MIGHT_HAVE_PC_PARPORT
35
35
select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX
36
36
select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if CPU_V7
37
+
select ARCH_NEED_CMPXCHG_1_EMU if CPU_V6
37
38
select ARCH_SUPPORTS_ATOMIC_RMW
38
39
select ARCH_SUPPORTS_CFI_CLANG
39
40
select ARCH_SUPPORTS_HUGETLBFS if ARM_LPAE
+6
-1
arch/arm/include/asm/cmpxchg.h
+6
-1
arch/arm/include/asm/cmpxchg.h
···
5
5
#include <linux/irqflags.h>
6
6
#include <linux/prefetch.h>
7
7
#include <asm/barrier.h>
8
+
#include <linux/cmpxchg-emu.h>
8
9
9
10
#if defined(CONFIG_CPU_SA1100) || defined(CONFIG_CPU_SA110)
10
11
/*
···
163
162
prefetchw((const void *)ptr);
164
163
165
164
switch (size) {
166
-
#ifndef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */
165
+
#ifdef CONFIG_CPU_V6 /* ARCH == ARMv6 */
166
+
case 1:
167
+
oldval = cmpxchg_emu_u8((volatile u8 *)ptr, old, new);
168
+
break;
169
+
#else /* min ARCH > ARMv6 */
167
170
case 1:
168
171
do {
169
172
asm volatile("@ __cmpxchg1\n"