system.h

xen 3.2.2 源码

#ifndef __X86_32_SYSTEM_H__
#define __X86_32_SYSTEM_H__

static always_inline unsigned long long __cmpxchg8b(
    volatile void *ptr, unsigned long long old, unsigned long long new)
{
    unsigned long long prev;
    asm volatile (
        LOCK_PREFIX "cmpxchg8b %3"
        : "=A" (prev)
        : "c" ((u32)(new>>32)), "b" ((u32)new),
          "m" (*__xg((volatile void *)ptr)), "0" (old)
        : "memory" );
    return prev;
}

#define cmpxchg(ptr,o,n)                                \
({                                                      \
    __typeof__(*(ptr)) __prev;                          \
    switch ( sizeof(*(ptr)) ) {                         \
    case 8:                                             \
        __prev = ((__typeof__(*(ptr)))__cmpxchg8b(      \
            (ptr),                                      \
            (unsigned long long)(o),                    \
            (unsigned long long)(n)));                  \
        break;                                          \
    default:                                            \
        __prev = ((__typeof__(*(ptr)))__cmpxchg(        \
            (ptr),                                      \
            (unsigned long)(o),                         \
            (unsigned long)(n),                         \
            sizeof(*(ptr))));                           \
        break;                                          \
    }                                                   \
    __prev;                                             \
})

/*
 * This function causes value _o to be changed to _n at location _p.
 * If this access causes a fault then we return 1, otherwise we return 0.
 * If no fault occurs then _o is updated to the value we saw at _p. If this
 * is the same as the initial value of _o then _n is written to location _p.
 */
#define __cmpxchg_user(_p,_o,_n,_isuff,_oppre,_regtype)                 \
    asm volatile (                                                      \
        "1: " LOCK_PREFIX "cmpxchg"_isuff" %"_oppre"2,%3\n"             \
        "2:\n"                                                          \
        ".section .fixup,\"ax\"\n"                                      \
        "3:     movl $1,%1\n"                                           \
        "       jmp 2b\n"                                               \
        ".previous\n"                                                   \
        ".section __ex_table,\"a\"\n"                                   \
        "       .align 4\n"                                             \
        "       .long 1b,3b\n"                                          \
        ".previous"                                                     \
        : "=a" (_o), "=r" (_rc)                                         \
        : _regtype (_n), "m" (*__xg((volatile void *)_p)), "0" (_o), "1" (0) \
        : "memory");

#define cmpxchg_user(_p,_o,_n)                                          \
({                                                                      \
    int _rc;                                                            \
    switch ( sizeof(*(_p)) ) {                                          \
    case 1:                                                             \
        __cmpxchg_user(_p,_o,_n,"b","b","q");                           \
        break;                                                          \
    case 2:                                                             \
        __cmpxchg_user(_p,_o,_n,"w","w","r");                           \
        break;                                                          \
    case 4:                                                             \
        __cmpxchg_user(_p,_o,_n,"l","","r");                            \
        break;                                                          \
    case 8:                                                             \
        asm volatile (                                                  \
            "1: " LOCK_PREFIX "cmpxchg8b %4\n"                          \
            "2:\n"                                                      \
            ".section .fixup,\"ax\"\n"                                  \
            "3:     movl $1,%1\n"                                       \
            "       jmp 2b\n"                                           \
            ".previous\n"                                               \
            ".section __ex_table,\"a\"\n"                               \
            "       .align 4\n"                                         \
            "       .long 1b,3b\n"                                      \
            ".previous"                                                 \
            : "=A" (_o), "=r" (_rc)                                     \
            : "c" ((u32)((u64)(_n)>>32)), "b" ((u32)(_n)),              \
              "m" (*__xg((volatile void *)(_p))), "0" (_o), "1" (0)     \
            : "memory");                                                \
        break;                                                          \
    }                                                                   \
    _rc;                                                                \
})

static inline void atomic_write64(uint64_t *p, uint64_t v)
{
    uint64_t w = *p, x;
    while ( (x = __cmpxchg8b(p, w, v)) != w )
        w = x;
}

#define mb()                    \
    asm volatile ( "lock; addl $0,0(%%esp)" : : : "memory" )

#define __save_flags(x)         \
    asm volatile ( "pushfl ; popl %0" : "=g" (x) : )
#define __restore_flags(x)      \
    asm volatile ( "pushl %0 ; popfl" : : "g" (x) : "memory", "cc" )

#define local_irq_save(x)       \
    asm volatile ( "pushfl ; popl %0 ; cli" : "=g" (x) : : "memory" )
#define local_irq_restore(x)    \
    __restore_flags(x)

#endif /* __X86_32_SYSTEM_H__ */