diff options
Diffstat (limited to 'arch/x86/include/asm/rwsem.h')
| -rw-r--r-- | arch/x86/include/asm/rwsem.h | 81 |
1 files changed, 49 insertions, 32 deletions
diff --git a/arch/x86/include/asm/rwsem.h b/arch/x86/include/asm/rwsem.h index ca7517d33776..606ede126972 100644 --- a/arch/x86/include/asm/rwsem.h +++ b/arch/x86/include/asm/rwsem.h @@ -41,6 +41,7 @@ #include <linux/list.h> #include <linux/spinlock.h> #include <linux/lockdep.h> +#include <asm/asm.h> struct rwsem_waiter; @@ -55,17 +56,28 @@ extern asmregparm struct rw_semaphore * /* * the semaphore definition + * + * The bias values and the counter type limits the number of + * potential readers/writers to 32767 for 32 bits and 2147483647 + * for 64 bits. */ -#define RWSEM_UNLOCKED_VALUE 0x00000000 -#define RWSEM_ACTIVE_BIAS 0x00000001 -#define RWSEM_ACTIVE_MASK 0x0000ffff -#define RWSEM_WAITING_BIAS (-0x00010000) +#ifdef CONFIG_X86_64 +# define RWSEM_ACTIVE_MASK 0xffffffffL +#else +# define RWSEM_ACTIVE_MASK 0x0000ffffL +#endif + +#define RWSEM_UNLOCKED_VALUE 0x00000000L +#define RWSEM_ACTIVE_BIAS 0x00000001L +#define RWSEM_WAITING_BIAS (-RWSEM_ACTIVE_MASK-1) #define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS #define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS) +typedef signed long rwsem_count_t; + struct rw_semaphore { - signed long count; + rwsem_count_t count; spinlock_t wait_lock; struct list_head wait_list; #ifdef CONFIG_DEBUG_LOCK_ALLOC @@ -105,7 +117,7 @@ do { \ static inline void __down_read(struct rw_semaphore *sem) { asm volatile("# beginning down_read\n\t" - LOCK_PREFIX " incl (%%eax)\n\t" + LOCK_PREFIX _ASM_INC "(%1)\n\t" /* adds 0x00000001, returns the old value */ " jns 1f\n" " call call_rwsem_down_read_failed\n" @@ -121,14 +133,14 @@ static inline void __down_read(struct rw_semaphore *sem) */ static inline int __down_read_trylock(struct rw_semaphore *sem) { - __s32 result, tmp; + rwsem_count_t result, tmp; asm volatile("# beginning __down_read_trylock\n\t" - " movl %0,%1\n\t" + " mov %0,%1\n\t" "1:\n\t" - " movl %1,%2\n\t" - " addl %3,%2\n\t" + " mov %1,%2\n\t" + " add %3,%2\n\t" " jle 2f\n\t" - LOCK_PREFIX " cmpxchgl %2,%0\n\t" + LOCK_PREFIX " cmpxchg %2,%0\n\t" " jnz 1b\n\t" "2:\n\t" "# ending __down_read_trylock\n\t" @@ -143,13 +155,13 @@ static inline int __down_read_trylock(struct rw_semaphore *sem) */ static inline void __down_write_nested(struct rw_semaphore *sem, int subclass) { - int tmp; + rwsem_count_t tmp; tmp = RWSEM_ACTIVE_WRITE_BIAS; asm volatile("# beginning down_write\n\t" - LOCK_PREFIX " xadd %%edx,(%%eax)\n\t" + LOCK_PREFIX " xadd %1,(%2)\n\t" /* subtract 0x0000ffff, returns the old value */ - " testl %%edx,%%edx\n\t" + " test %1,%1\n\t" /* was the count 0 before? */ " jz 1f\n" " call call_rwsem_down_write_failed\n" @@ -170,9 +182,9 @@ static inline void __down_write(struct rw_semaphore *sem) */ static inline int __down_write_trylock(struct rw_semaphore *sem) { - signed long ret = cmpxchg(&sem->count, - RWSEM_UNLOCKED_VALUE, - RWSEM_ACTIVE_WRITE_BIAS); + rwsem_count_t ret = cmpxchg(&sem->count, + RWSEM_UNLOCKED_VALUE, + RWSEM_ACTIVE_WRITE_BIAS); if (ret == RWSEM_UNLOCKED_VALUE) return 1; return 0; @@ -183,9 +195,9 @@ static inline int __down_write_trylock(struct rw_semaphore *sem) */ static inline void __up_read(struct rw_semaphore *sem) { - __s32 tmp = -RWSEM_ACTIVE_READ_BIAS; + rwsem_count_t tmp = -RWSEM_ACTIVE_READ_BIAS; asm volatile("# beginning __up_read\n\t" - LOCK_PREFIX " xadd %%edx,(%%eax)\n\t" + LOCK_PREFIX " xadd %1,(%2)\n\t" /* subtracts 1, returns the old value */ " jns 1f\n\t" " call call_rwsem_wake\n" @@ -201,18 +213,18 @@ static inline void __up_read(struct rw_semaphore *sem) */ static inline void __up_write(struct rw_semaphore *sem) { + rwsem_count_t tmp; asm volatile("# beginning __up_write\n\t" - " movl %2,%%edx\n\t" - LOCK_PREFIX " xaddl %%edx,(%%eax)\n\t" + LOCK_PREFIX " xadd %1,(%2)\n\t" /* tries to transition 0xffff0001 -> 0x00000000 */ " jz 1f\n" " call call_rwsem_wake\n" "1:\n\t" "# ending __up_write\n" - : "+m" (sem->count) - : "a" (sem), "i" (-RWSEM_ACTIVE_WRITE_BIAS) - : "memory", "cc", "edx"); + : "+m" (sem->count), "=d" (tmp) + : "a" (sem), "1" (-RWSEM_ACTIVE_WRITE_BIAS) + : "memory", "cc"); } /* @@ -221,33 +233,38 @@ static inline void __up_write(struct rw_semaphore *sem) static inline void __downgrade_write(struct rw_semaphore *sem) { asm volatile("# beginning __downgrade_write\n\t" - LOCK_PREFIX " addl %2,(%%eax)\n\t" - /* transitions 0xZZZZ0001 -> 0xYYYY0001 */ + LOCK_PREFIX _ASM_ADD "%2,(%1)\n\t" + /* + * transitions 0xZZZZ0001 -> 0xYYYY0001 (i386) + * 0xZZZZZZZZ00000001 -> 0xYYYYYYYY00000001 (x86_64) + */ " jns 1f\n\t" " call call_rwsem_downgrade_wake\n" "1:\n\t" "# ending __downgrade_write\n" : "+m" (sem->count) - : "a" (sem), "i" (-RWSEM_WAITING_BIAS) + : "a" (sem), "er" (-RWSEM_WAITING_BIAS) : "memory", "cc"); } /* * implement atomic add functionality */ -static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem) +static inline void rwsem_atomic_add(rwsem_count_t delta, + struct rw_semaphore *sem) { - asm volatile(LOCK_PREFIX "addl %1,%0" + asm volatile(LOCK_PREFIX _ASM_ADD "%1,%0" : "+m" (sem->count) - : "ir" (delta)); + : "er" (delta)); } /* * implement exchange and add functionality */ -static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem) +static inline rwsem_count_t rwsem_atomic_update(rwsem_count_t delta, + struct rw_semaphore *sem) { - int tmp = delta; + rwsem_count_t tmp = delta; asm volatile(LOCK_PREFIX "xadd %0,%1" : "+r" (tmp), "+m" (sem->count) |
