diff options
| author | Michael S. Tsirkin <mst@redhat.com> | 2016-01-07 17:54:54 +0200 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2016-01-12 20:47:01 +0200 |
| commit | 3226aad81aa670015a59e51458a0deb2d3bcb600 (patch) | |
| tree | 0cc2ab0abf363ad3f851fdcb14c0f7c1386e89de /arch/sh/include/asm/cmpxchg-grb.h | |
| parent | a65961272e1ebdb60804bbe2bb440481fcbd1c76 (diff) | |
sh: support 1 and 2 byte xchg
This completes the xchg implementation for sh architecture. Note: The
llsc variant is tricky since this only supports 4 byte atomics, the
existing implementation of 1 byte xchg is wrong: we need to do a 4 byte
cmpxchg and retry if any bytes changed meanwhile.
Write this in C for clarity.
Suggested-by: Rich Felker <dalias@libc.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Diffstat (limited to 'arch/sh/include/asm/cmpxchg-grb.h')
| -rw-r--r-- | arch/sh/include/asm/cmpxchg-grb.h | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/arch/sh/include/asm/cmpxchg-grb.h b/arch/sh/include/asm/cmpxchg-grb.h index f848dec9e483..2ed557b31bd9 100644 --- a/arch/sh/include/asm/cmpxchg-grb.h +++ b/arch/sh/include/asm/cmpxchg-grb.h @@ -23,6 +23,28 @@ static inline unsigned long xchg_u32(volatile u32 *m, unsigned long val) return retval; } +static inline unsigned long xchg_u16(volatile u16 *m, unsigned long val) +{ + unsigned long retval; + + __asm__ __volatile__ ( + " .align 2 \n\t" + " mova 1f, r0 \n\t" /* r0 = end point */ + " mov r15, r1 \n\t" /* r1 = saved sp */ + " mov #-6, r15 \n\t" /* LOGIN */ + " mov.w @%1, %0 \n\t" /* load old value */ + " extu.w %0, %0 \n\t" /* extend as unsigned */ + " mov.w %2, @%1 \n\t" /* store new value */ + "1: mov r1, r15 \n\t" /* LOGOUT */ + : "=&r" (retval), + "+r" (m), + "+r" (val) /* inhibit r15 overloading */ + : + : "memory" , "r0", "r1"); + + return retval; +} + static inline unsigned long xchg_u8(volatile u8 *m, unsigned long val) { unsigned long retval; |