From: Paul E. McKenney <paulmck@kernel.org>
Date: Wed, 27 Mar 2024 22:21:31 +0000 (-0700)
Subject: sh: Emulate one-byte cmpxchg
X-Git-Tag: v6.12-rc1~220^2~1
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=c81a748edefd098ea21dd35d4bba03f69412fc26;p=thirdparty%2Fkernel%2Flinux.git

sh: Emulate one-byte cmpxchg

Use the new cmpxchg_emu_u8() to emulate one-byte cmpxchg() on sh.

[ paulmck: Drop two-byte support per Arnd Bergmann feedback. ]
[ paulmck: Apply feedback from Naresh Kamboju. ]
[ Apply Geert Uytterhoeven feedback. ]

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Andi Shyti <andi.shyti@linux.intel.com>
Cc: Palmer Dabbelt <palmer@rivosinc.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: <linux-sh@vger.kernel.org>
Acked-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
---

diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 1aa3c4a0c5b27..e9103998cca91 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
diff --git a/arch/sh/include/asm/cmpxchg.h b/arch/sh/include/asm/cmpxchg.h
index 5d617b3ef78f7..1e5dc5ccf7bf5 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);
 	}