diff options
Diffstat (limited to 'arch/arm64/include/asm/spinlock.h')
| -rw-r--r-- | arch/arm64/include/asm/spinlock.h | 122 |
1 files changed, 77 insertions, 45 deletions
diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h index 41112fe2f8b..c45b7b1b719 100644 --- a/arch/arm64/include/asm/spinlock.h +++ b/arch/arm64/include/asm/spinlock.h @@ -22,17 +22,10 @@ /* * Spinlock implementation. * - * The old value is read exclusively and the new one, if unlocked, is written - * exclusively. In case of failure, the loop is restarted. - * * The memory barriers are implicit with the load-acquire and store-release * instructions. - * - * Unlocked value: 0 - * Locked value: 1 */ -#define arch_spin_is_locked(x) ((x)->lock != 0) #define arch_spin_unlock_wait(lock) \ do { while (arch_spin_is_locked(lock)) cpu_relax(); } while (0) @@ -41,30 +34,50 @@ static inline void arch_spin_lock(arch_spinlock_t *lock) { unsigned int tmp; + arch_spinlock_t lockval, newval; asm volatile( - " sevl\n" - "1: wfe\n" - "2: ldaxr %w0, [%1]\n" - " cbnz %w0, 1b\n" - " stxr %w0, %w2, [%1]\n" - " cbnz %w0, 2b\n" - : "=&r" (tmp) - : "r" (&lock->lock), "r" (1) + /* Atomically increment the next ticket. */ +" prfm pstl1strm, %3\n" +"1: ldaxr %w0, %3\n" +" add %w1, %w0, %w5\n" +" stxr %w2, %w1, %3\n" +" cbnz %w2, 1b\n" + /* Did we get the lock? */ +" eor %w1, %w0, %w0, ror #16\n" +" cbz %w1, 3f\n" + /* + * No: spin on the owner. Send a local event to avoid missing an + * unlock before the exclusive load. + */ +" sevl\n" +"2: wfe\n" +" ldaxrh %w2, %4\n" +" eor %w1, %w2, %w0, lsr #16\n" +" cbnz %w1, 2b\n" + /* We got the lock. Critical section starts here. */ +"3:" + : "=&r" (lockval), "=&r" (newval), "=&r" (tmp), "+Q" (*lock) + : "Q" (lock->owner), "I" (1 << TICKET_SHIFT) : "memory"); } static inline int arch_spin_trylock(arch_spinlock_t *lock) { unsigned int tmp; + arch_spinlock_t lockval; asm volatile( - " ldaxr %w0, [%1]\n" - " cbnz %w0, 1f\n" - " stxr %w0, %w2, [%1]\n" - "1:\n" - : "=&r" (tmp) - : "r" (&lock->lock), "r" (1) +" prfm pstl1strm, %2\n" +"1: ldaxr %w0, %2\n" +" eor %w1, %w0, %w0, ror #16\n" +" cbnz %w1, 2f\n" +" add %w0, %w0, %3\n" +" stxr %w1, %w0, %2\n" +" cbnz %w1, 1b\n" +"2:" + : "=&r" (lockval), "=&r" (tmp), "+Q" (*lock) + : "I" (1 << TICKET_SHIFT) : "memory"); return !tmp; @@ -73,9 +86,28 @@ static inline int arch_spin_trylock(arch_spinlock_t *lock) static inline void arch_spin_unlock(arch_spinlock_t *lock) { asm volatile( - " stlr %w1, [%0]\n" - : : "r" (&lock->lock), "r" (0) : "memory"); +" stlrh %w1, %0\n" + : "=Q" (lock->owner) + : "r" (lock->owner + 1) + : "memory"); +} + +static inline int arch_spin_value_unlocked(arch_spinlock_t lock) +{ + return lock.owner == lock.next; +} + +static inline int arch_spin_is_locked(arch_spinlock_t *lock) +{ + return !arch_spin_value_unlocked(ACCESS_ONCE(*lock)); +} + +static inline int arch_spin_is_contended(arch_spinlock_t *lock) +{ + arch_spinlock_t lockval = ACCESS_ONCE(*lock); + return (lockval.next - lockval.owner) > 1; } +#define arch_spin_is_contended arch_spin_is_contended /* * Write lock implementation. @@ -94,12 +126,12 @@ static inline void arch_write_lock(arch_rwlock_t *rw) asm volatile( " sevl\n" "1: wfe\n" - "2: ldaxr %w0, [%1]\n" + "2: ldaxr %w0, %1\n" " cbnz %w0, 1b\n" - " stxr %w0, %w2, [%1]\n" + " stxr %w0, %w2, %1\n" " cbnz %w0, 2b\n" - : "=&r" (tmp) - : "r" (&rw->lock), "r" (0x80000000) + : "=&r" (tmp), "+Q" (rw->lock) + : "r" (0x80000000) : "memory"); } @@ -108,12 +140,12 @@ static inline int arch_write_trylock(arch_rwlock_t *rw) unsigned int tmp; asm volatile( - " ldaxr %w0, [%1]\n" + " ldaxr %w0, %1\n" " cbnz %w0, 1f\n" - " stxr %w0, %w2, [%1]\n" + " stxr %w0, %w2, %1\n" "1:\n" - : "=&r" (tmp) - : "r" (&rw->lock), "r" (0x80000000) + : "=&r" (tmp), "+Q" (rw->lock) + : "r" (0x80000000) : "memory"); return !tmp; @@ -122,8 +154,8 @@ static inline int arch_write_trylock(arch_rwlock_t *rw) static inline void arch_write_unlock(arch_rwlock_t *rw) { asm volatile( - " stlr %w1, [%0]\n" - : : "r" (&rw->lock), "r" (0) : "memory"); + " stlr %w1, %0\n" + : "=Q" (rw->lock) : "r" (0) : "memory"); } /* write_can_lock - would write_trylock() succeed? */ @@ -148,13 +180,13 @@ static inline void arch_read_lock(arch_rwlock_t *rw) asm volatile( " sevl\n" "1: wfe\n" - "2: ldaxr %w0, [%2]\n" + "2: ldaxr %w0, %2\n" " add %w0, %w0, #1\n" " tbnz %w0, #31, 1b\n" - " stxr %w1, %w0, [%2]\n" + " stxr %w1, %w0, %2\n" " cbnz %w1, 2b\n" - : "=&r" (tmp), "=&r" (tmp2) - : "r" (&rw->lock) + : "=&r" (tmp), "=&r" (tmp2), "+Q" (rw->lock) + : : "memory"); } @@ -163,12 +195,12 @@ static inline void arch_read_unlock(arch_rwlock_t *rw) unsigned int tmp, tmp2; asm volatile( - "1: ldxr %w0, [%2]\n" + "1: ldxr %w0, %2\n" " sub %w0, %w0, #1\n" - " stlxr %w1, %w0, [%2]\n" + " stlxr %w1, %w0, %2\n" " cbnz %w1, 1b\n" - : "=&r" (tmp), "=&r" (tmp2) - : "r" (&rw->lock) + : "=&r" (tmp), "=&r" (tmp2), "+Q" (rw->lock) + : : "memory"); } @@ -177,13 +209,13 @@ static inline int arch_read_trylock(arch_rwlock_t *rw) unsigned int tmp, tmp2 = 1; asm volatile( - " ldaxr %w0, [%2]\n" + " ldaxr %w0, %2\n" " add %w0, %w0, #1\n" " tbnz %w0, #31, 1f\n" - " stxr %w1, %w0, [%2]\n" + " stxr %w1, %w0, %2\n" "1:\n" - : "=&r" (tmp), "+r" (tmp2) - : "r" (&rw->lock) + : "=&r" (tmp), "+r" (tmp2), "+Q" (rw->lock) + : : "memory"); return !tmp2; |