diff options
| -rw-r--r-- | arch/xtensa/include/asm/cmpxchg.h | 36 |
1 files changed, 32 insertions, 4 deletions
diff --git a/arch/xtensa/include/asm/cmpxchg.h b/arch/xtensa/include/asm/cmpxchg.h index 201e9009efd8..22a10c715c1f 100644 --- a/arch/xtensa/include/asm/cmpxchg.h +++ b/arch/xtensa/include/asm/cmpxchg.h @@ -13,6 +13,7 @@ #ifndef __ASSEMBLY__ +#include <linux/bits.h> #include <linux/stringify.h> /* @@ -138,6 +139,28 @@ static inline unsigned long xchg_u32(volatile int * m, unsigned long val) #define xchg(ptr,x) \ ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr)))) +static inline u32 xchg_small(volatile void *ptr, u32 x, int size) +{ + int off = (unsigned long)ptr % sizeof(u32); + volatile u32 *p = ptr - off; +#ifdef __BIG_ENDIAN + int bitoff = (sizeof(u32) - size - off) * BITS_PER_BYTE; +#else + int bitoff = off * BITS_PER_BYTE; +#endif + u32 bitmask = ((0x1 << size * BITS_PER_BYTE) - 1) << bitoff; + u32 oldv, newv; + u32 ret; + + do { + oldv = READ_ONCE(*p); + ret = (oldv & bitmask) >> bitoff; + newv = (oldv & ~bitmask) | (x << bitoff); + } while (__cmpxchg_u32(p, oldv, newv) != oldv); + + return ret; +} + /* * This only works if the compiler isn't horribly bad at optimizing. * gcc-2.5.8 reportedly can't handle this, but I define that one to @@ -150,11 +173,16 @@ static __inline__ unsigned long __xchg(unsigned long x, volatile void * ptr, int size) { switch (size) { - case 4: - return xchg_u32(ptr, x); + case 1: + return xchg_small(ptr, x, 1); + case 2: + return xchg_small(ptr, x, 2); + case 4: + return xchg_u32(ptr, x); + default: + __xchg_called_with_bad_pointer(); + return x; } - __xchg_called_with_bad_pointer(); - return x; } #endif /* __ASSEMBLY__ */ |