projects/linux·commit 980bcd35

Merge tag 'cmpxchg.2024.09.15a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

980bcd35 · Linus Torvalds <[email protected]> · 2024-09-16 07:34:24 +02:00

Pull byte cmpxchg updates from Paul McKenney:
 "ARC/sh/xtensa: Provide one-byte cmpxchg emulation

  This series provides emulated one-byte cmpxchg() support for ARM, sh,
  and xtensa using the cmpxchg_emu_u8() function that uses a four-byte
  cmpxchg() to emulate the one-byte variant.

  This covers all architectures"

* tag 'cmpxchg.2024.09.15a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
  xtensa: Emulate one-byte cmpxchg
  sh: Emulate one-byte cmpxchg
  ARC: Emulate one-byte cmpxchg
Commit
980bcd35ae0a21da9a22155e386c8ff17019d545
Parents
114143a5 · e799bef0

Merge commit. Changes below are compared with the first parent: 114143a5.

Changes

6 files changed · +12 −2

FileStatusAddDelContent
arch/arc/Kconfigmodified+1−0View file
arch/arc/include/asm/cmpxchg.hmodified+4−2View file
arch/sh/Kconfigmodified+1−0View file
arch/sh/include/asm/cmpxchg.hmodified+3−0View file
arch/xtensa/Kconfigmodified+1−0View file
arch/xtensa/include/asm/cmpxchg.hmodified+2−0View file

arch/arc/Kconfig

View file
diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index fd0b0a0..163608f 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -13,6 +13,7 @@ config ARC
select ARCH_HAS_SETUP_DMA_OPS
select ARCH_HAS_SYNC_DMA_FOR_CPU
select ARCH_HAS_SYNC_DMA_FOR_DEVICE
+ select ARCH_NEED_CMPXCHG_1_EMU
select ARCH_SUPPORTS_ATOMIC_RMW if ARC_HAS_LLSC
select ARCH_32BIT_OFF_T
select BUILDTIME_TABLE_SORT

arch/arc/include/asm/cmpxchg.h

View file
diff --git a/arch/arc/include/asm/cmpxchg.h b/arch/arc/include/asm/cmpxchg.h
index e138fde..58045c8 100644
--- a/arch/arc/include/asm/cmpxchg.h
+++ b/arch/arc/include/asm/cmpxchg.h
@@ -8,6 +8,7 @@
#include <linux/build_bug.h>
#include <linux/types.h>
+#include <linux/cmpxchg-emu.h>
#include <asm/barrier.h>
#include <asm/smp.h>
@@ -46,6 +47,9 @@
__typeof__(*(ptr)) _prev_; \
\
switch(sizeof((_p_))) { \
+ case 1: \
+ _prev_ = (__typeof__(*(ptr)))cmpxchg_emu_u8((volatile u8 *)_p_, (uintptr_t)_o_, (uintptr_t)_n_); \
+ break; \
case 4: \
_prev_ = __cmpxchg(_p_, _o_, _n_); \
break; \
@@ -65,8 +69,6 @@
__typeof__(*(ptr)) _prev_; \
unsigned long __flags; \
\
- BUILD_BUG_ON(sizeof(_p_) != 4); \
- \
/* \
* spin lock/unlock provide the needed smp_mb() before/after \
*/ \

arch/sh/Kconfig

View file
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 1aa3c4a..e910399 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -14,6 +14,7 @@ config SUPERH
select ARCH_HIBERNATION_POSSIBLE if MMU
select ARCH_MIGHT_HAVE_PC_PARPORT
select ARCH_WANT_IPC_PARSE_VERSION
+ select ARCH_NEED_CMPXCHG_1_EMU
select CPU_NO_EFFICIENT_FFS
select DMA_DECLARE_COHERENT
select GENERIC_ATOMIC64

arch/sh/include/asm/cmpxchg.h

View file
diff --git a/arch/sh/include/asm/cmpxchg.h b/arch/sh/include/asm/cmpxchg.h
index 5d617b3..1e5dc5c 100644
--- a/arch/sh/include/asm/cmpxchg.h
+++ b/arch/sh/include/asm/cmpxchg.h
@@ -9,6 +9,7 @@
#include <linux/compiler.h>
#include <linux/types.h>
+#include <linux/cmpxchg-emu.h>
#if defined(CONFIG_GUSA_RB)
#include <asm/cmpxchg-grb.h>
@@ -56,6 +57,8 @@ static inline unsigned long __cmpxchg(volatile void * ptr, unsigned long old,
unsigned long new, int size)
{
switch (size) {
+ case 1:
+ return cmpxchg_emu_u8(ptr, old, new);
case 4:
return __cmpxchg_u32(ptr, old, new);
}

arch/xtensa/Kconfig

View file
diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index f200a4e..d3db28f 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -14,6 +14,7 @@ config XTENSA
select ARCH_HAS_DMA_SET_UNCACHED if MMU
select ARCH_HAS_STRNCPY_FROM_USER if !KASAN
select ARCH_HAS_STRNLEN_USER
+ select ARCH_NEED_CMPXCHG_1_EMU
select ARCH_USE_MEMTEST
select ARCH_USE_QUEUED_RWLOCKS
select ARCH_USE_QUEUED_SPINLOCKS

arch/xtensa/include/asm/cmpxchg.h

View file
diff --git a/arch/xtensa/include/asm/cmpxchg.h b/arch/xtensa/include/asm/cmpxchg.h
index 675a11e..95e33a9 100644
--- a/arch/xtensa/include/asm/cmpxchg.h
+++ b/arch/xtensa/include/asm/cmpxchg.h
@@ -15,6 +15,7 @@
#include <linux/bits.h>
#include <linux/stringify.h>
+#include <linux/cmpxchg-emu.h>
/*
* cmpxchg
@@ -74,6 +75,7 @@ static __inline__ unsigned long
__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size)
{
switch (size) {
+ case 1: return cmpxchg_emu_u8(ptr, old, new);
case 4: return __cmpxchg_u32(ptr, old, new);
default: __cmpxchg_called_with_bad_pointer();
return old;