fdaaae5998
operations are actually the compare_and_set 32 and 64 bits. For all others atomic there is a fallback in sys/atomic.c For ia32 I add a workaround the ebx register. When compiling with -fPIC ebx is reserved for the shared object interface (store some global pointer). On the same time cmpxchg8b use ebx and ecx to store the new value. The workaround save the ebx content before cmpxchg8b and restore it afterward. There is still a possible bug !!! If we get interrupted between the push and pop of the ebx then we will definitivelly crash ... This commit was SVN r3387.
150 строки
3.9 KiB
C
150 строки
3.9 KiB
C
/*
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* $HEADER$
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*/
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#ifndef OMPI_SYS_ARCH_ATOMIC_H
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#define OMPI_SYS_ARCH_ATOMIC_H 1
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/*
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* On ia32, we use cmpxchg.
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*/
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#ifdef HAVE_SMP
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#define SMPLOCK "lock; "
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#define MB() __asm__ __volatile__("": : :"memory")
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#else
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#define SMPLOCK
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#define MB()
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#endif
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static inline void ompi_atomic_mb(void)
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{
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MB();
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}
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static inline void ompi_atomic_rmb(void)
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{
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MB();
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}
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static inline void ompi_atomic_wmb(void)
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{
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MB();
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}
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static inline int ompi_atomic_cmpset_32(volatile int32_t *addr,
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int32_t oldval,
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int32_t newval)
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{
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unsigned char ret;
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__asm__ __volatile (
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SMPLOCK "cmpxchgl %1,%2 \n\t"
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"sete %0 \n\t"
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: "=qm" (ret)
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: "q"(newval), "m"(*((volatile long*)addr)), "a"(oldval)
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: "memory");
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return (int)ret;
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}
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#define ompi_atomic_cmpset_acq_32 ompi_atomic_cmpset_32
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#define ompi_atomic_cmpset_rel_32 ompi_atomic_cmpset_32
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typedef struct {
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uint32_t lo;
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uint32_t hi;
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} lwords_t;
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/* On Linux the EBX register is used by the shared libraries
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* to keep the global offset. In same time this register is
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* required by the cmpxchg8b instruction (as an input parameter).
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* This conflict orce us to save the EBX before the cmpxchg8b
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* and to restore it afterward.
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*/
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static inline int ompi_atomic_cmpset_64(volatile int64_t *addr,
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int64_t oldval,
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int64_t newval)
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{
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/*
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* Compare EDX:EAX with m64. If equal, set ZF and load ECX:EBX into
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* m64. Else, clear ZF and load m64 into EDX:EAX.
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*/
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lwords_t *pnew = (lwords_t*)&newval;
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#if 1
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int64_t prev;
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__asm__ __volatile__(
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"push %%ebx \n\t"
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"movl %3, %%ebx \n\t"
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SMPLOCK "cmpxchg8b %4 \n\t"
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"pop %%ebx \n\t"
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: "=A" (prev)
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: "0" (oldval), "c" ((unsigned long)pnew->lo),
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"r" ((unsigned long)pnew->hi), "m" (addr)
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: "cc", "memory");
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return (prev == oldval);
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#else
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unsigned char realized;
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lwords_t *pold = (lwords_t*)&oldval;
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__asm__ __volatile(
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"push %%ebx \n\t"
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"movl %4, %%ebx \n\t"
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SMPLOCK "cmpxchg8b %1 \n\t"
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"sete %0 \n\t"
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"pop %%ebx \n\t"
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: "=qm" (realized)
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: "m"(*((volatile long*)addr)), "a"(pold->hi), "d"(pold->lo),
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"r"(pnew->hi), "c"(pnew->lo)
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: "cc", "memory" );
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return realized;
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#endif
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}
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#define ompi_atomic_cmpset_acq_64 ompi_atomic_cmpset_64
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#define ompi_atomic_cmpset_rel_64 ompi_atomic_cmpset_64
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#define OMPI_ARCHITECTURE_DEFINE_ATOMIC_ADD_32
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/**
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* atomic_add - add integer to atomic variable
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* @i: integer value to add
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* @v: pointer of type int
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*
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* Atomically adds @i to @v.
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*/
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static inline int ompi_atomic_add_32(volatile int32_t* v, int i)
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{
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__asm__ __volatile__(
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SMPLOCK "addl %1,%0"
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:"=m" (*v)
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:"ir" (i), "m" (*v));
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return (*v); /* should be an atomic operation */
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}
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#define OMPI_ARCHITECTURE_DEFINE_ATOMIC_SUB_32
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/**
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* atomic_sub - subtract the atomic variable
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* @i: integer value to subtract
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* @v: pointer of type int
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*
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* Atomically subtracts @i from @v.
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*/
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static inline int ompi_atomic_sub_32(volatile int32_t* v, int i)
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{
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__asm__ __volatile__(
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SMPLOCK "subl %1,%0"
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:"=m" (*v)
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:"ir" (i), "m" (*v));
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return (*v); /* should be an atomic operation */
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}
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#endif /* ! OMPI_SYS_ARCH_ATOMIC_H */
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