From b862f3b099f3ea672c7438c0b282ce8201d39dfc Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 8 Jul 2006 15:24:18 -0700 Subject: [PATCH] i386: improve and correct inline asm memory constraints Use "+m" rather than a combination of "=m" and "m" for improved clarity and consistency. This also fixes some inlines that incorrectly didn't tell the compiler that they read the old value at all, potentially causing the compiler to generate bogus code. It appear that all of those potential bugs were hidden by the use of extra "volatile" specifiers on the data structures in question, though. Signed-off-by: Linus Torvalds --- include/asm-i386/atomic.h | 30 ++++++++++++++--------------- include/asm-i386/futex.h | 10 +++++----- include/asm-i386/local.h | 14 ++++++-------- include/asm-i386/posix_types.h | 4 ++-- include/asm-i386/rwlock.h | 4 ++-- include/asm-i386/rwsem.h | 35 +++++++++++++++++----------------- include/asm-i386/semaphore.h | 8 ++++---- include/asm-i386/spinlock.h | 14 +++++++------- 8 files changed, 57 insertions(+), 62 deletions(-) diff --git a/include/asm-i386/atomic.h b/include/asm-i386/atomic.h index 4f061fa737..51a1662425 100644 --- a/include/asm-i386/atomic.h +++ b/include/asm-i386/atomic.h @@ -46,8 +46,8 @@ static __inline__ void atomic_add(int i, atomic_t *v) { __asm__ __volatile__( LOCK_PREFIX "addl %1,%0" - :"=m" (v->counter) - :"ir" (i), "m" (v->counter)); + :"+m" (v->counter) + :"ir" (i)); } /** @@ -61,8 +61,8 @@ static __inline__ void atomic_sub(int i, atomic_t *v) { __asm__ __volatile__( LOCK_PREFIX "subl %1,%0" - :"=m" (v->counter) - :"ir" (i), "m" (v->counter)); + :"+m" (v->counter) + :"ir" (i)); } /** @@ -80,8 +80,8 @@ static __inline__ int atomic_sub_and_test(int i, atomic_t *v) __asm__ __volatile__( LOCK_PREFIX "subl %2,%0; sete %1" - :"=m" (v->counter), "=qm" (c) - :"ir" (i), "m" (v->counter) : "memory"); + :"+m" (v->counter), "=qm" (c) + :"ir" (i) : "memory"); return c; } @@ -95,8 +95,7 @@ static __inline__ void atomic_inc(atomic_t *v) { __asm__ __volatile__( LOCK_PREFIX "incl %0" - :"=m" (v->counter) - :"m" (v->counter)); + :"+m" (v->counter)); } /** @@ -109,8 +108,7 @@ static __inline__ void atomic_dec(atomic_t *v) { __asm__ __volatile__( LOCK_PREFIX "decl %0" - :"=m" (v->counter) - :"m" (v->counter)); + :"+m" (v->counter)); } /** @@ -127,8 +125,8 @@ static __inline__ int atomic_dec_and_test(atomic_t *v) __asm__ __volatile__( LOCK_PREFIX "decl %0; sete %1" - :"=m" (v->counter), "=qm" (c) - :"m" (v->counter) : "memory"); + :"+m" (v->counter), "=qm" (c) + : : "memory"); return c != 0; } @@ -146,8 +144,8 @@ static __inline__ int atomic_inc_and_test(atomic_t *v) __asm__ __volatile__( LOCK_PREFIX "incl %0; sete %1" - :"=m" (v->counter), "=qm" (c) - :"m" (v->counter) : "memory"); + :"+m" (v->counter), "=qm" (c) + : : "memory"); return c != 0; } @@ -166,8 +164,8 @@ static __inline__ int atomic_add_negative(int i, atomic_t *v) __asm__ __volatile__( LOCK_PREFIX "addl %2,%0; sets %1" - :"=m" (v->counter), "=qm" (c) - :"ir" (i), "m" (v->counter) : "memory"); + :"+m" (v->counter), "=qm" (c) + :"ir" (i) : "memory"); return c; } diff --git a/include/asm-i386/futex.h b/include/asm-i386/futex.h index 7b8ceefd01..946d97cfea 100644 --- a/include/asm-i386/futex.h +++ b/include/asm-i386/futex.h @@ -20,8 +20,8 @@ .align 8\n\ .long 1b,3b\n\ .previous" \ - : "=r" (oldval), "=r" (ret), "=m" (*uaddr) \ - : "i" (-EFAULT), "m" (*uaddr), "0" (oparg), "1" (0)) + : "=r" (oldval), "=r" (ret), "+m" (*uaddr) \ + : "i" (-EFAULT), "0" (oparg), "1" (0)) #define __futex_atomic_op2(insn, ret, oldval, uaddr, oparg) \ __asm__ __volatile ( \ @@ -38,9 +38,9 @@ .align 8\n\ .long 1b,4b,2b,4b\n\ .previous" \ - : "=&a" (oldval), "=&r" (ret), "=m" (*uaddr), \ + : "=&a" (oldval), "=&r" (ret), "+m" (*uaddr), \ "=&r" (tem) \ - : "r" (oparg), "i" (-EFAULT), "m" (*uaddr), "1" (0)) + : "r" (oparg), "i" (-EFAULT), "1" (0)) static inline int futex_atomic_op_inuser (int encoded_op, int __user *uaddr) @@ -123,7 +123,7 @@ futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval) " .long 1b,3b \n" " .previous \n" - : "=a" (oldval), "=m" (*uaddr) + : "=a" (oldval), "+m" (*uaddr) : "i" (-EFAULT), "r" (newval), "0" (oldval) : "memory" ); diff --git a/include/asm-i386/local.h b/include/asm-i386/local.h index 3b4998c51d..12060e22f7 100644 --- a/include/asm-i386/local.h +++ b/include/asm-i386/local.h @@ -17,32 +17,30 @@ static __inline__ void local_inc(local_t *v) { __asm__ __volatile__( "incl %0" - :"=m" (v->counter) - :"m" (v->counter)); + :"+m" (v->counter)); } static __inline__ void local_dec(local_t *v) { __asm__ __volatile__( "decl %0" - :"=m" (v->counter) - :"m" (v->counter)); + :"+m" (v->counter)); } static __inline__ void local_add(long i, local_t *v) { __asm__ __volatile__( "addl %1,%0" - :"=m" (v->counter) - :"ir" (i), "m" (v->counter)); + :"+m" (v->counter) + :"ir" (i)); } static __inline__ void local_sub(long i, local_t *v) { __asm__ __volatile__( "subl %1,%0" - :"=m" (v->counter) - :"ir" (i), "m" (v->counter)); + :"+m" (v->counter) + :"ir" (i)); } /* On x86, these are no better than the atomic variants. */ diff --git a/include/asm-i386/posix_types.h b/include/asm-i386/posix_types.h index 4e47ed059a..133e31e7df 100644 --- a/include/asm-i386/posix_types.h +++ b/include/asm-i386/posix_types.h @@ -51,12 +51,12 @@ typedef struct { #undef __FD_SET #define __FD_SET(fd,fdsetp) \ __asm__ __volatile__("btsl %1,%0": \ - "=m" (*(__kernel_fd_set *) (fdsetp)):"r" ((int) (fd))) + "+m" (*(__kernel_fd_set *) (fdsetp)):"r" ((int) (fd))) #undef __FD_CLR #define __FD_CLR(fd,fdsetp) \ __asm__ __volatile__("btrl %1,%0": \ - "=m" (*(__kernel_fd_set *) (fdsetp)):"r" ((int) (fd))) + "+m" (*(__kernel_fd_set *) (fdsetp)):"r" ((int) (fd))) #undef __FD_ISSET #define __FD_ISSET(fd,fdsetp) (__extension__ ({ \ diff --git a/include/asm-i386/rwlock.h b/include/asm-i386/rwlock.h index 94f00195d5..96b0bef2ea 100644 --- a/include/asm-i386/rwlock.h +++ b/include/asm-i386/rwlock.h @@ -37,7 +37,7 @@ "popl %%eax\n\t" \ "1:\n", \ "subl $1,%0\n\t", \ - "=m" (*(volatile int *)rw) : : "memory") + "+m" (*(volatile int *)rw) : : "memory") #define __build_read_lock(rw, helper) do { \ if (__builtin_constant_p(rw)) \ @@ -63,7 +63,7 @@ "popl %%eax\n\t" \ "1:\n", \ "subl $" RW_LOCK_BIAS_STR ",%0\n\t", \ - "=m" (*(volatile int *)rw) : : "memory") + "+m" (*(volatile int *)rw) : : "memory") #define __build_write_lock(rw, helper) do { \ if (__builtin_constant_p(rw)) \ diff --git a/include/asm-i386/rwsem.h b/include/asm-i386/rwsem.h index 2f07601562..43113f5608 100644 --- a/include/asm-i386/rwsem.h +++ b/include/asm-i386/rwsem.h @@ -111,8 +111,8 @@ LOCK_PREFIX " incl (%%eax)\n\t" /* adds 0x00000001, returns the old value " jmp 1b\n" LOCK_SECTION_END "# ending down_read\n\t" - : "=m"(sem->count) - : "a"(sem), "m"(sem->count) + : "+m" (sem->count) + : "a" (sem) : "memory", "cc"); } @@ -133,8 +133,8 @@ LOCK_PREFIX " cmpxchgl %2,%0\n\t" " jnz 1b\n\t" "2:\n\t" "# ending __down_read_trylock\n\t" - : "+m"(sem->count), "=&a"(result), "=&r"(tmp) - : "i"(RWSEM_ACTIVE_READ_BIAS) + : "+m" (sem->count), "=&a" (result), "=&r" (tmp) + : "i" (RWSEM_ACTIVE_READ_BIAS) : "memory", "cc"); return result>=0 ? 1 : 0; } @@ -161,8 +161,8 @@ LOCK_PREFIX " xadd %%edx,(%%eax)\n\t" /* subtract 0x0000ffff, returns the " jmp 1b\n" LOCK_SECTION_END "# ending down_write" - : "=m"(sem->count), "=d"(tmp) - : "a"(sem), "1"(tmp), "m"(sem->count) + : "+m" (sem->count), "=d" (tmp) + : "a" (sem), "1" (tmp) : "memory", "cc"); } @@ -205,8 +205,8 @@ LOCK_PREFIX " xadd %%edx,(%%eax)\n\t" /* subtracts 1, returns the old valu " jmp 1b\n" LOCK_SECTION_END "# ending __up_read\n" - : "=m"(sem->count), "=d"(tmp) - : "a"(sem), "1"(tmp), "m"(sem->count) + : "+m" (sem->count), "=d" (tmp) + : "a" (sem), "1" (tmp) : "memory", "cc"); } @@ -231,8 +231,8 @@ LOCK_PREFIX " xaddl %%edx,(%%eax)\n\t" /* tries to transition 0xffff0001 -> " jmp 1b\n" LOCK_SECTION_END "# ending __up_write\n" - : "=m"(sem->count) - : "a"(sem), "i"(-RWSEM_ACTIVE_WRITE_BIAS), "m"(sem->count) + : "+m" (sem->count) + : "a" (sem), "i" (-RWSEM_ACTIVE_WRITE_BIAS) : "memory", "cc", "edx"); } @@ -256,8 +256,8 @@ LOCK_PREFIX " addl %2,(%%eax)\n\t" /* transitions 0xZZZZ0001 -> 0xYYYY0001 " jmp 1b\n" LOCK_SECTION_END "# ending __downgrade_write\n" - : "=m"(sem->count) - : "a"(sem), "i"(-RWSEM_WAITING_BIAS), "m"(sem->count) + : "+m" (sem->count) + : "a" (sem), "i" (-RWSEM_WAITING_BIAS) : "memory", "cc"); } @@ -268,8 +268,8 @@ static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem) { __asm__ __volatile__( LOCK_PREFIX "addl %1,%0" - : "=m"(sem->count) - : "ir"(delta), "m"(sem->count)); + : "+m" (sem->count) + : "ir" (delta)); } /* @@ -280,10 +280,9 @@ static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem) int tmp = delta; __asm__ __volatile__( -LOCK_PREFIX "xadd %0,(%2)" - : "+r"(tmp), "=m"(sem->count) - : "r"(sem), "m"(sem->count) - : "memory"); +LOCK_PREFIX "xadd %0,%1" + : "+r" (tmp), "+m" (sem->count) + : : "memory"); return tmp+delta; } diff --git a/include/asm-i386/semaphore.h b/include/asm-i386/semaphore.h index f7a0f310c5..d51e800acf 100644 --- a/include/asm-i386/semaphore.h +++ b/include/asm-i386/semaphore.h @@ -107,7 +107,7 @@ static inline void down(struct semaphore * sem) "call __down_failed\n\t" "jmp 1b\n" LOCK_SECTION_END - :"=m" (sem->count) + :"+m" (sem->count) : :"memory","ax"); } @@ -132,7 +132,7 @@ static inline int down_interruptible(struct semaphore * sem) "call __down_failed_interruptible\n\t" "jmp 1b\n" LOCK_SECTION_END - :"=a" (result), "=m" (sem->count) + :"=a" (result), "+m" (sem->count) : :"memory"); return result; @@ -157,7 +157,7 @@ static inline int down_trylock(struct semaphore * sem) "call __down_failed_trylock\n\t" "jmp 1b\n" LOCK_SECTION_END - :"=a" (result), "=m" (sem->count) + :"=a" (result), "+m" (sem->count) : :"memory"); return result; @@ -182,7 +182,7 @@ static inline void up(struct semaphore * sem) "jmp 1b\n" LOCK_SECTION_END ".subsection 0\n" - :"=m" (sem->count) + :"+m" (sem->count) : :"memory","ax"); } diff --git a/include/asm-i386/spinlock.h b/include/asm-i386/spinlock.h index 87c40f8306..d816c62a7a 100644 --- a/include/asm-i386/spinlock.h +++ b/include/asm-i386/spinlock.h @@ -65,7 +65,7 @@ static inline void __raw_spin_lock(raw_spinlock_t *lock) alternative_smp( __raw_spin_lock_string, __raw_spin_lock_string_up, - "=m" (lock->slock) : : "memory"); + "+m" (lock->slock) : : "memory"); } /* @@ -79,7 +79,7 @@ static inline void __raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long fla alternative_smp( __raw_spin_lock_string_flags, __raw_spin_lock_string_up, - "=m" (lock->slock) : "r" (flags) : "memory"); + "+m" (lock->slock) : "r" (flags) : "memory"); } #endif @@ -88,7 +88,7 @@ static inline int __raw_spin_trylock(raw_spinlock_t *lock) char oldval; __asm__ __volatile__( "xchgb %b0,%1" - :"=q" (oldval), "=m" (lock->slock) + :"=q" (oldval), "+m" (lock->slock) :"0" (0) : "memory"); return oldval > 0; } @@ -104,7 +104,7 @@ static inline int __raw_spin_trylock(raw_spinlock_t *lock) #define __raw_spin_unlock_string \ "movb $1,%0" \ - :"=m" (lock->slock) : : "memory" + :"+m" (lock->slock) : : "memory" static inline void __raw_spin_unlock(raw_spinlock_t *lock) @@ -118,7 +118,7 @@ static inline void __raw_spin_unlock(raw_spinlock_t *lock) #define __raw_spin_unlock_string \ "xchgb %b0, %1" \ - :"=q" (oldval), "=m" (lock->slock) \ + :"=q" (oldval), "+m" (lock->slock) \ :"0" (oldval) : "memory" static inline void __raw_spin_unlock(raw_spinlock_t *lock) @@ -199,13 +199,13 @@ static inline int __raw_write_trylock(raw_rwlock_t *lock) static inline void __raw_read_unlock(raw_rwlock_t *rw) { - asm volatile(LOCK_PREFIX "incl %0" :"=m" (rw->lock) : : "memory"); + asm volatile(LOCK_PREFIX "incl %0" :"+m" (rw->lock) : : "memory"); } static inline void __raw_write_unlock(raw_rwlock_t *rw) { asm volatile(LOCK_PREFIX "addl $" RW_LOCK_BIAS_STR ", %0" - : "=m" (rw->lock) : : "memory"); + : "+m" (rw->lock) : : "memory"); } #endif /* __ASM_SPINLOCK_H */ -- 2.39.5