diff options
Diffstat (limited to 'arch/x86/include/asm/rwsem.h')
| -rw-r--r-- | arch/x86/include/asm/rwsem.h | 174 |
1 files changed, 67 insertions, 107 deletions
diff --git a/arch/x86/include/asm/rwsem.h b/arch/x86/include/asm/rwsem.h index ca7517d3377..cad82c9c2fd 100644 --- a/arch/x86/include/asm/rwsem.h +++ b/arch/x86/include/asm/rwsem.h @@ -37,67 +37,25 @@ #endif #ifdef __KERNEL__ - -#include <linux/list.h> -#include <linux/spinlock.h> -#include <linux/lockdep.h> - -struct rwsem_waiter; - -extern asmregparm struct rw_semaphore * - rwsem_down_read_failed(struct rw_semaphore *sem); -extern asmregparm struct rw_semaphore * - rwsem_down_write_failed(struct rw_semaphore *sem); -extern asmregparm struct rw_semaphore * - rwsem_wake(struct rw_semaphore *); -extern asmregparm struct rw_semaphore * - rwsem_downgrade_wake(struct rw_semaphore *sem); +#include <asm/asm.h> /* - * 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) -#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS -#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS) - -struct rw_semaphore { - signed long count; - spinlock_t wait_lock; - struct list_head wait_list; -#ifdef CONFIG_DEBUG_LOCK_ALLOC - struct lockdep_map dep_map; -#endif -}; - -#ifdef CONFIG_DEBUG_LOCK_ALLOC -# define __RWSEM_DEP_MAP_INIT(lockname) , .dep_map = { .name = #lockname } +#ifdef CONFIG_X86_64 +# define RWSEM_ACTIVE_MASK 0xffffffffL #else -# define __RWSEM_DEP_MAP_INIT(lockname) +# define RWSEM_ACTIVE_MASK 0x0000ffffL #endif - -#define __RWSEM_INITIALIZER(name) \ -{ \ - RWSEM_UNLOCKED_VALUE, __SPIN_LOCK_UNLOCKED((name).wait_lock), \ - LIST_HEAD_INIT((name).wait_list) __RWSEM_DEP_MAP_INIT(name) \ -} - -#define DECLARE_RWSEM(name) \ - struct rw_semaphore name = __RWSEM_INITIALIZER(name) - -extern void __init_rwsem(struct rw_semaphore *sem, const char *name, - struct lock_class_key *key); - -#define init_rwsem(sem) \ -do { \ - static struct lock_class_key __key; \ - \ - __init_rwsem((sem), #sem, &__key); \ -} while (0) +#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) /* * lock for reading @@ -105,8 +63,8 @@ do { \ static inline void __down_read(struct rw_semaphore *sem) { asm volatile("# beginning down_read\n\t" - LOCK_PREFIX " incl (%%eax)\n\t" - /* adds 0x00000001, returns the old value */ + LOCK_PREFIX _ASM_INC "(%1)\n\t" + /* adds 0x00000001 */ " jns 1f\n" " call call_rwsem_down_read_failed\n" "1:\n\t" @@ -121,14 +79,14 @@ static inline void __down_read(struct rw_semaphore *sem) */ static inline int __down_read_trylock(struct rw_semaphore *sem) { - __s32 result, tmp; + long 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" @@ -143,20 +101,18 @@ static inline int __down_read_trylock(struct rw_semaphore *sem) */ static inline void __down_write_nested(struct rw_semaphore *sem, int subclass) { - int tmp; - - tmp = RWSEM_ACTIVE_WRITE_BIAS; + long tmp; asm volatile("# beginning down_write\n\t" - LOCK_PREFIX " xadd %%edx,(%%eax)\n\t" - /* subtract 0x0000ffff, returns the old value */ - " testl %%edx,%%edx\n\t" - /* was the count 0 before? */ + LOCK_PREFIX " xadd %1,(%2)\n\t" + /* adds 0xffff0001, returns the old value */ + " test " __ASM_SEL(%w1,%k1) "," __ASM_SEL(%w1,%k1) "\n\t" + /* was the active mask 0 before? */ " jz 1f\n" " call call_rwsem_down_write_failed\n" "1:\n" "# ending down_write" : "+m" (sem->count), "=d" (tmp) - : "a" (sem), "1" (tmp) + : "a" (sem), "1" (RWSEM_ACTIVE_WRITE_BIAS) : "memory", "cc"); } @@ -170,12 +126,25 @@ 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); - if (ret == RWSEM_UNLOCKED_VALUE) - return 1; - return 0; + long result, tmp; + asm volatile("# beginning __down_write_trylock\n\t" + " mov %0,%1\n\t" + "1:\n\t" + " test " __ASM_SEL(%w1,%k1) "," __ASM_SEL(%w1,%k1) "\n\t" + /* was the active mask 0 before? */ + " jnz 2f\n\t" + " mov %1,%2\n\t" + " add %3,%2\n\t" + LOCK_PREFIX " cmpxchg %2,%0\n\t" + " jnz 1b\n\t" + "2:\n\t" + " sete %b1\n\t" + " movzbl %b1, %k1\n\t" + "# ending __down_write_trylock\n\t" + : "+m" (sem->count), "=&a" (result), "=&r" (tmp) + : "er" (RWSEM_ACTIVE_WRITE_BIAS) + : "memory", "cc"); + return result; } /* @@ -183,16 +152,16 @@ 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; + long tmp; 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" + " call call_rwsem_wake\n" /* expects old value in %edx */ "1:\n" "# ending __up_read\n" : "+m" (sem->count), "=d" (tmp) - : "a" (sem), "1" (tmp) + : "a" (sem), "1" (-RWSEM_ACTIVE_READ_BIAS) : "memory", "cc"); } @@ -201,18 +170,17 @@ static inline void __up_read(struct rw_semaphore *sem) */ static inline void __up_write(struct rw_semaphore *sem) { + long tmp; asm volatile("# beginning __up_write\n\t" - " movl %2,%%edx\n\t" - LOCK_PREFIX " xaddl %%edx,(%%eax)\n\t" - /* tries to transition - 0xffff0001 -> 0x00000000 */ - " jz 1f\n" - " call call_rwsem_wake\n" + LOCK_PREFIX " xadd %1,(%2)\n\t" + /* subtracts 0xffff0001, returns the old value */ + " jns 1f\n\t" + " call call_rwsem_wake\n" /* expects old value in %edx */ "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"); } /* @@ -221,44 +189,36 @@ 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(long 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) -{ - int tmp = delta; - - asm volatile(LOCK_PREFIX "xadd %0,%1" - : "+r" (tmp), "+m" (sem->count) - : : "memory"); - - return tmp + delta; -} - -static inline int rwsem_is_locked(struct rw_semaphore *sem) +static inline long rwsem_atomic_update(long delta, struct rw_semaphore *sem) { - return (sem->count != 0); + return delta + xadd(&sem->count, delta); } #endif /* __KERNEL__ */ |