futex.h

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#ifndef _ASM_MICROBLAZE_FUTEX_H
#define _ASM_MICROBLAZE_FUTEX_H

#ifdef __KERNEL__

#include <linux/futex.h>
#include <linux/uaccess.h>
#include <asm/errno.h>

#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \
({                                  \
    __asm__ __volatile__ (                      \
            "1: lwx %0, %2, r0; "           \
                insn                    \
            "2: swx %1, %2, r0;         \
                addic   %1, r0, 0;          \
                bnei    %1, 1b;             \
            3:                      \
            .section .fixup,\"ax\";             \
            4:  brid    3b;             \
                addik   %1, r0, %3;         \
            .previous;                  \
            .section __ex_table,\"a\";          \
            .word   1b,4b,2b,4b;                \
            .previous;"                 \
    : "=&r" (oldval), "=&r" (ret)                   \
    : "r" (uaddr), "i" (-EFAULT), "r" (oparg)           \
    );                              \
})

static inline int
futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
{
    int op = (encoded_op >> 28) & 7;
    int cmp = (encoded_op >> 24) & 15;
    int oparg = (encoded_op << 8) >> 20;
    int cmparg = (encoded_op << 20) >> 20;
    int oldval = 0, ret;
    if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
        oparg = 1 << oparg;

    if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
        return -EFAULT;

    pagefault_disable();

    switch (op) {
    case FUTEX_OP_SET:
        __futex_atomic_op("or %1,%4,%4;", ret, oldval, uaddr, oparg);
        break;
    case FUTEX_OP_ADD:
        __futex_atomic_op("add %1,%0,%4;", ret, oldval, uaddr, oparg);
        break;
    case FUTEX_OP_OR:
        __futex_atomic_op("or %1,%0,%4;", ret, oldval, uaddr, oparg);
        break;
    case FUTEX_OP_ANDN:
        __futex_atomic_op("andn %1,%0,%4;", ret, oldval, uaddr, oparg);
        break;
    case FUTEX_OP_XOR:
        __futex_atomic_op("xor %1,%0,%4;", ret, oldval, uaddr, oparg);
        break;
    default:
        ret = -ENOSYS;
    }

    pagefault_enable();

    if (!ret) {
        switch (cmp) {
        case FUTEX_OP_CMP_EQ:
            ret = (oldval == cmparg);
            break;
        case FUTEX_OP_CMP_NE:
            ret = (oldval != cmparg);
            break;
        case FUTEX_OP_CMP_LT:
            ret = (oldval < cmparg);
            break;
        case FUTEX_OP_CMP_GE:
            ret = (oldval >= cmparg);
            break;
        case FUTEX_OP_CMP_LE:
            ret = (oldval <= cmparg);
            break;
        case FUTEX_OP_CMP_GT:
            ret = (oldval > cmparg);
            break;
        default:
            ret = -ENOSYS;
        }
    }
    return ret;
}

static inline int
futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
                  u32 oldval, u32 newval)
{
    int ret = 0, cmp;
    u32 prev;

    if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
        return -EFAULT;

    __asm__ __volatile__ ("1:   lwx %1, %3, r0;     \
                    cmp %2, %1, %4;     \
                    beqi    %2, 3f;         \
                2:  swx %5, %3, r0;     \
                    addic   %2, r0, 0;      \
                    bnei    %2, 1b;         \
                3:                  \
                .section .fixup,\"ax\";         \
                4:  brid    3b;         \
                    addik   %0, r0, %6;     \
                .previous;              \
                .section __ex_table,\"a\";      \
                .word   1b,4b,2b,4b;            \
                .previous;"             \
        : "+r" (ret), "=&r" (prev), "=&r"(cmp)  \
        : "r" (uaddr), "r" (oldval), "r" (newval), "i" (-EFAULT));

    *uval = prev;
    return ret;
}

#endif /* __KERNEL__ */

#endif