root/include/asm-x86/futex.h

INCLUDED FROM

DEFINITIONS

1. futex_atomic_op_inuser
2. futex_atomic_cmpxchg_inatomic

#ifndef ASM_X86__FUTEX_H
#define ASM_X86__FUTEX_H

#ifdef __KERNEL__

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

#include <asm/asm.h>
#include <asm/errno.h>
#include <asm/processor.h>
#include <asm/system.h>

#define __futex_atomic_op1(insn, ret, oldval, uaddr, oparg)     \
        asm volatile("1:\t" insn "\n"                           \
                     "2:\t.section .fixup,\"ax\"\n"             \
                     "3:\tmov\t%3, %1\n"                        \
                     "\tjmp\t2b\n"                              \
                     "\t.previous\n"                            \
                     _ASM_EXTABLE(1b, 3b)                       \
                     : "=r" (oldval), "=r" (ret), "+m" (*uaddr) \
                     : "i" (-EFAULT), "0" (oparg), "1" (0))

#define __futex_atomic_op2(insn, ret, oldval, uaddr, oparg)     \
        asm volatile("1:\tmovl  %2, %0\n"                       \
                     "\tmovl\t%0, %3\n"                         \
                     "\t" insn "\n"                             \
                     "2:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"     \
                     "\tjnz\t1b\n"                              \
                     "3:\t.section .fixup,\"ax\"\n"             \
                     "4:\tmov\t%5, %1\n"                        \
                     "\tjmp\t3b\n"                              \
                     "\t.previous\n"                            \
                     _ASM_EXTABLE(1b, 4b)                       \
                     _ASM_EXTABLE(2b, 4b)                       \
                     : "=&a" (oldval), "=&r" (ret),             \
                       "+m" (*uaddr), "=&r" (tem)               \
                     : "r" (oparg), "i" (-EFAULT), "1" (0))

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, tem;

        if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
                oparg = 1 << oparg;

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

#if defined(CONFIG_X86_32) && !defined(CONFIG_X86_BSWAP)
        /* Real i386 machines can only support FUTEX_OP_SET */
        if (op != FUTEX_OP_SET && boot_cpu_data.x86 == 3)
                return -ENOSYS;
#endif

        pagefault_disable();

        switch (op) {
        case FUTEX_OP_SET:
                __futex_atomic_op1("xchgl %0, %2", ret, oldval, uaddr, oparg);
                break;
        case FUTEX_OP_ADD:
                __futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret, oldval,
                                   uaddr, oparg);
                break;
        case FUTEX_OP_OR:
                __futex_atomic_op2("orl %4, %3", ret, oldval, uaddr, oparg);
                break;
        case FUTEX_OP_ANDN:
                __futex_atomic_op2("andl %4, %3", ret, oldval, uaddr, ~oparg);
                break;
        case FUTEX_OP_XOR:
                __futex_atomic_op2("xorl %4, %3", 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(int __user *uaddr, int oldval,
                                                int newval)
{

#if defined(CONFIG_X86_32) && !defined(CONFIG_X86_BSWAP)
        /* Real i386 machines have no cmpxchg instruction */
        if (boot_cpu_data.x86 == 3)
                return -ENOSYS;
#endif

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

        asm volatile("1:\t" LOCK_PREFIX "cmpxchgl %3, %1\n"
                     "2:\t.section .fixup, \"ax\"\n"
                     "3:\tmov     %2, %0\n"
                     "\tjmp     2b\n"
                     "\t.previous\n"
                     _ASM_EXTABLE(1b, 3b)
                     : "=a" (oldval), "+m" (*uaddr)
                     : "i" (-EFAULT), "r" (newval), "0" (oldval)
                     : "memory"
        );

        return oldval;
}

#endif
#endif /* ASM_X86__FUTEX_H */