futex.h

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#ifndef _ASM_HEXAGON_FUTEX_H
#define _ASM_HEXAGON_FUTEX_H

#ifdef __KERNEL__

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

/* XXX TODO-- need to add sync barriers! */

#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \
    __asm__ __volatile( \
    "1: %0 = memw_locked(%3);\n" \
        /* For example: %1 = %4 */ \
        insn \
    "2: memw_locked(%3,p2) = %1;\n" \
    "   if !p2 jump 1b;\n" \
    "   %1 = #0;\n" \
    "3:\n" \
    ".section .fixup,\"ax\"\n" \
    "4: %1 = #%5;\n" \
    "   jump 3b\n" \
    ".previous\n" \
    ".section __ex_table,\"a\"\n" \
    ".long 1b,4b,2b,4b\n" \
    ".previous\n" \
    : "=&r" (oldval), "=&r" (ret), "+m" (*uaddr) \
    : "r" (uaddr), "r" (oparg), "i" (-EFAULT) \
    : "p2", "memory")


static inline int
futex_atomic_op_inuser(int encoded_op, int __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(int)))
        return -EFAULT;

    pagefault_disable();

    switch (op) {
    case FUTEX_OP_SET:
        __futex_atomic_op("%1 = %4\n", ret, oldval, uaddr, oparg);
        break;
    case FUTEX_OP_ADD:
        __futex_atomic_op("%1 = add(%0,%4)\n", ret, oldval, uaddr,
                  oparg);
        break;
    case FUTEX_OP_OR:
        __futex_atomic_op("%1 = or(%0,%4)\n", ret, oldval, uaddr,
                  oparg);
        break;
    case FUTEX_OP_ANDN:
        __futex_atomic_op("%1 = not(%4); %1 = and(%0,%1)\n", ret,
                  oldval, uaddr, oparg);
        break;
    case FUTEX_OP_XOR:
        __futex_atomic_op("%1 = xor(%0,%4)\n", 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 prev;
    int ret;

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

    __asm__ __volatile__ (
    "1: %1 = memw_locked(%3)\n"
    "   {\n"
    "      p2 = cmp.eq(%1,%4)\n"
    "      if !p2.new jump:NT 3f\n"
    "   }\n"
    "2: memw_locked(%3,p2) = %5\n"
    "   if !p2 jump 1b\n"
    "3:\n"
    ".section .fixup,\"ax\"\n"
    "4: %0 = #%6\n"
    "   jump 3b\n"
    ".previous\n"
    ".section __ex_table,\"a\"\n"
    ".long 1b,4b,2b,4b\n"
    ".previous\n"
    : "+r" (ret), "=&r" (prev), "+m" (*uaddr)
    : "r" (uaddr), "r" (oldval), "r" (newval), "i"(-EFAULT)
    : "p2", "memory");

    *uval = prev;
    return ret;
}

#endif /* __KERNEL__ */
#endif /* _ASM_HEXAGON_FUTEX_H */