From 6d9b37a3a80195d317887ff81aad6a58a66954b5 Mon Sep 17 00:00:00 2001 From: Russell King Date: Tue, 26 Jul 2005 19:44:26 +0100 Subject: [PATCH] [PATCH] ARM SMP: Add ARMv6 memory barriers Convert explicit gcc asm-based memory barriers into smp_mb() calls. These change between barrier() and the ARMv6 data memory barrier instruction depending on whether ARMv6 SMP is enabled. Signed-off-by: Russell King --- include/asm-arm/bitops.h | 4 +-- include/asm-arm/locks.h | 36 +++++++++++++++++--------- include/asm-arm/spinlock.h | 53 +++++++++++++++++++++++++++----------- include/asm-arm/system.h | 5 ++++ 4 files changed, 69 insertions(+), 29 deletions(-) diff --git a/include/asm-arm/bitops.h b/include/asm-arm/bitops.h index 4edd4dc40c5b..c1adc6b3e86d 100644 --- a/include/asm-arm/bitops.h +++ b/include/asm-arm/bitops.h @@ -21,8 +21,8 @@ #include -#define smp_mb__before_clear_bit() do { } while (0) -#define smp_mb__after_clear_bit() do { } while (0) +#define smp_mb__before_clear_bit() mb() +#define smp_mb__after_clear_bit() mb() /* * These functions are the basis of our bit ops. diff --git a/include/asm-arm/locks.h b/include/asm-arm/locks.h index 9cb33fcc06c1..f08dc8447913 100644 --- a/include/asm-arm/locks.h +++ b/include/asm-arm/locks.h @@ -28,7 +28,8 @@ " blmi " #fail \ : \ : "r" (ptr), "I" (1) \ - : "ip", "lr", "cc", "memory"); \ + : "ip", "lr", "cc"); \ + smp_mb(); \ }) #define __down_op_ret(ptr,fail) \ @@ -48,12 +49,14 @@ " mov %0, ip" \ : "=&r" (ret) \ : "r" (ptr), "I" (1) \ - : "ip", "lr", "cc", "memory"); \ + : "ip", "lr", "cc"); \ + smp_mb(); \ ret; \ }) #define __up_op(ptr,wake) \ ({ \ + smp_mb(); \ __asm__ __volatile__( \ "@ up_op\n" \ "1: ldrex lr, [%0]\n" \ @@ -66,7 +69,7 @@ " blle " #wake \ : \ : "r" (ptr), "I" (1) \ - : "ip", "lr", "cc", "memory"); \ + : "ip", "lr", "cc"); \ }) /* @@ -92,11 +95,13 @@ " blne " #fail \ : \ : "r" (ptr), "I" (RW_LOCK_BIAS) \ - : "ip", "lr", "cc", "memory"); \ + : "ip", "lr", "cc"); \ + smp_mb(); \ }) #define __up_op_write(ptr,wake) \ ({ \ + smp_mb(); \ __asm__ __volatile__( \ "@ up_op_read\n" \ "1: ldrex lr, [%0]\n" \ @@ -108,7 +113,7 @@ " blcs " #wake \ : \ : "r" (ptr), "I" (RW_LOCK_BIAS) \ - : "ip", "lr", "cc", "memory"); \ + : "ip", "lr", "cc"); \ }) #define __down_op_read(ptr,fail) \ @@ -116,6 +121,7 @@ #define __up_op_read(ptr,wake) \ ({ \ + smp_mb(); \ __asm__ __volatile__( \ "@ up_op_read\n" \ "1: ldrex lr, [%0]\n" \ @@ -128,7 +134,7 @@ " bleq " #wake \ : \ : "r" (ptr), "I" (1) \ - : "ip", "lr", "cc", "memory"); \ + : "ip", "lr", "cc"); \ }) #else @@ -148,7 +154,8 @@ " blmi " #fail \ : \ : "r" (ptr), "I" (1) \ - : "ip", "lr", "cc", "memory"); \ + : "ip", "lr", "cc"); \ + smp_mb(); \ }) #define __down_op_ret(ptr,fail) \ @@ -169,12 +176,14 @@ " mov %0, ip" \ : "=&r" (ret) \ : "r" (ptr), "I" (1) \ - : "ip", "lr", "cc", "memory"); \ + : "ip", "lr", "cc"); \ + smp_mb(); \ ret; \ }) #define __up_op(ptr,wake) \ ({ \ + smp_mb(); \ __asm__ __volatile__( \ "@ up_op\n" \ " mrs ip, cpsr\n" \ @@ -188,7 +197,7 @@ " blle " #wake \ : \ : "r" (ptr), "I" (1) \ - : "ip", "lr", "cc", "memory"); \ + : "ip", "lr", "cc"); \ }) /* @@ -215,7 +224,8 @@ " blne " #fail \ : \ : "r" (ptr), "I" (RW_LOCK_BIAS) \ - : "ip", "lr", "cc", "memory"); \ + : "ip", "lr", "cc"); \ + smp_mb(); \ }) #define __up_op_write(ptr,wake) \ @@ -233,7 +243,8 @@ " blcs " #wake \ : \ : "r" (ptr), "I" (RW_LOCK_BIAS) \ - : "ip", "lr", "cc", "memory"); \ + : "ip", "lr", "cc"); \ + smp_mb(); \ }) #define __down_op_read(ptr,fail) \ @@ -241,6 +252,7 @@ #define __up_op_read(ptr,wake) \ ({ \ + smp_mb(); \ __asm__ __volatile__( \ "@ up_op_read\n" \ " mrs ip, cpsr\n" \ @@ -254,7 +266,7 @@ " bleq " #wake \ : \ : "r" (ptr), "I" (1) \ - : "ip", "lr", "cc", "memory"); \ + : "ip", "lr", "cc"); \ }) #endif diff --git a/include/asm-arm/spinlock.h b/include/asm-arm/spinlock.h index 9705d5eec94c..1f906d09b688 100644 --- a/include/asm-arm/spinlock.h +++ b/include/asm-arm/spinlock.h @@ -8,9 +8,10 @@ /* * ARMv6 Spin-locking. * - * We (exclusively) read the old value, and decrement it. If it - * hits zero, we may have won the lock, so we try (exclusively) - * storing it. + * We exclusively read the old value. If it is zero, we may have + * won the lock, so we try exclusively storing it. A memory barrier + * is required after we get a lock, and before we release it, because + * V6 CPUs are assumed to have weakly ordered memory. * * Unlocked value: 0 * Locked value: 1 @@ -41,7 +42,9 @@ static inline void _raw_spin_lock(spinlock_t *lock) " bne 1b" : "=&r" (tmp) : "r" (&lock->lock), "r" (1) - : "cc", "memory"); + : "cc"); + + smp_mb(); } static inline int _raw_spin_trylock(spinlock_t *lock) @@ -54,18 +57,25 @@ static inline int _raw_spin_trylock(spinlock_t *lock) " strexeq %0, %2, [%1]" : "=&r" (tmp) : "r" (&lock->lock), "r" (1) - : "cc", "memory"); - - return tmp == 0; + : "cc"); + + if (tmp == 0) { + smp_mb(); + return 1; + } else { + return 0; + } } static inline void _raw_spin_unlock(spinlock_t *lock) { + smp_mb(); + __asm__ __volatile__( " str %1, [%0]" : : "r" (&lock->lock), "r" (0) - : "cc", "memory"); + : "cc"); } /* @@ -98,7 +108,9 @@ static inline void _raw_write_lock(rwlock_t *rw) " bne 1b" : "=&r" (tmp) : "r" (&rw->lock), "r" (0x80000000) - : "cc", "memory"); + : "cc"); + + smp_mb(); } static inline int _raw_write_trylock(rwlock_t *rw) @@ -111,18 +123,25 @@ static inline int _raw_write_trylock(rwlock_t *rw) " strexeq %0, %2, [%1]" : "=&r" (tmp) : "r" (&rw->lock), "r" (0x80000000) - : "cc", "memory"); - - return tmp == 0; + : "cc"); + + if (tmp == 0) { + smp_mb(); + return 1; + } else { + return 0; + } } static inline void _raw_write_unlock(rwlock_t *rw) { + smp_mb(); + __asm__ __volatile__( "str %1, [%0]" : : "r" (&rw->lock), "r" (0) - : "cc", "memory"); + : "cc"); } /* @@ -149,13 +168,17 @@ static inline void _raw_read_lock(rwlock_t *rw) " bmi 1b" : "=&r" (tmp), "=&r" (tmp2) : "r" (&rw->lock) - : "cc", "memory"); + : "cc"); + + smp_mb(); } static inline void _raw_read_unlock(rwlock_t *rw) { unsigned long tmp, tmp2; + smp_mb(); + __asm__ __volatile__( "1: ldrex %0, [%2]\n" " sub %0, %0, #1\n" @@ -164,7 +187,7 @@ static inline void _raw_read_unlock(rwlock_t *rw) " bne 1b" : "=&r" (tmp), "=&r" (tmp2) : "r" (&rw->lock) - : "cc", "memory"); + : "cc"); } #define _raw_read_trylock(lock) generic_raw_read_trylock(lock) diff --git a/include/asm-arm/system.h b/include/asm-arm/system.h index 3f9c3626a73c..8efa4ebdcacb 100644 --- a/include/asm-arm/system.h +++ b/include/asm-arm/system.h @@ -139,7 +139,12 @@ extern unsigned int user_debug; #define vectors_high() (0) #endif +#if __LINUX_ARM_ARCH__ >= 6 +#define mb() __asm__ __volatile__ ("mcr p15, 0, %0, c7, c10, 5" \ + : : "r" (0) : "memory") +#else #define mb() __asm__ __volatile__ ("" : : : "memory") +#endif #define rmb() mb() #define wmb() mb() #define read_barrier_depends() do { } while(0) -- 2.30.2