LXR linux/arch/arm64/include/asm/futex.h

   1/*
   2 * Copyright (C) 2012 ARM Ltd.
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License version 2 as
   6 * published by the Free Software Foundation.
   7 *
   8 * This program is distributed in the hope that it will be useful,
   9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 * GNU General Public License for more details.
  12 *
  13 * You should have received a copy of the GNU General Public License
  14 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  15 */
  16#ifndef __ASM_FUTEX_H
  17#define __ASM_FUTEX_H
  18
  19#ifdef __KERNEL__
  20
  21#include <linux/futex.h>
  22#include <linux/uaccess.h>
  23
  24#include <asm/errno.h>
  25
  26#define __futex_atomic_op(insn, ret, oldval, uaddr, tmp, oparg)         \
  27do {                                                                    \
  28        uaccess_enable();                                               \
  29        asm volatile(                                                   \
  30"       prfm    pstl1strm, %2\n"                                        \
  31"1:     ldxr    %w1, %2\n"                                              \
  32        insn "\n"                                                       \
  33"2:     stlxr   %w0, %w3, %2\n"                                         \
  34"       cbnz    %w0, 1b\n"                                              \
  35"       dmb     ish\n"                                                  \
  36"3:\n"                                                                  \
  37"       .pushsection .fixup,\"ax\"\n"                                   \
  38"       .align  2\n"                                                    \
  39"4:     mov     %w0, %w5\n"                                             \
  40"       b       3b\n"                                                   \
  41"       .popsection\n"                                                  \
  42        _ASM_EXTABLE(1b, 4b)                                            \
  43        _ASM_EXTABLE(2b, 4b)                                            \
  44        : "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp)       \
  45        : "r" (oparg), "Ir" (-EFAULT)                                   \
  46        : "memory");                                                    \
  47        uaccess_disable();                                              \
  48} while (0)
  49
  50static inline int
  51arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr)
  52{
  53        int oldval = 0, ret, tmp;
  54        u32 __user *uaddr = __uaccess_mask_ptr(_uaddr);
  55
  56        pagefault_disable();
  57
  58        switch (op) {
  59        case FUTEX_OP_SET:
  60                __futex_atomic_op("mov  %w3, %w4",
  61                                  ret, oldval, uaddr, tmp, oparg);
  62                break;
  63        case FUTEX_OP_ADD:
  64                __futex_atomic_op("add  %w3, %w1, %w4",
  65                                  ret, oldval, uaddr, tmp, oparg);
  66                break;
  67        case FUTEX_OP_OR:
  68                __futex_atomic_op("orr  %w3, %w1, %w4",
  69                                  ret, oldval, uaddr, tmp, oparg);
  70                break;
  71        case FUTEX_OP_ANDN:
  72                __futex_atomic_op("and  %w3, %w1, %w4",
  73                                  ret, oldval, uaddr, tmp, ~oparg);
  74                break;
  75        case FUTEX_OP_XOR:
  76                __futex_atomic_op("eor  %w3, %w1, %w4",
  77                                  ret, oldval, uaddr, tmp, oparg);
  78                break;
  79        default:
  80                ret = -ENOSYS;
  81        }
  82
  83        pagefault_enable();
  84
  85        if (!ret)
  86                *oval = oldval;
  87
  88        return ret;
  89}
  90
  91static inline int
  92futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *_uaddr,
  93                              u32 oldval, u32 newval)
  94{
  95        int ret = 0;
  96        u32 val, tmp;
  97        u32 __user *uaddr;
  98
  99        if (!access_ok(_uaddr, sizeof(u32)))
 100                return -EFAULT;
 101
 102        uaddr = __uaccess_mask_ptr(_uaddr);
 103        uaccess_enable();
 104        asm volatile("// futex_atomic_cmpxchg_inatomic\n"
 105"       prfm    pstl1strm, %2\n"
 106"1:     ldxr    %w1, %2\n"
 107"       sub     %w3, %w1, %w4\n"
 108"       cbnz    %w3, 3f\n"
 109"2:     stlxr   %w3, %w5, %2\n"
 110"       cbnz    %w3, 1b\n"
 111"       dmb     ish\n"
 112"3:\n"
 113"       .pushsection .fixup,\"ax\"\n"
 114"4:     mov     %w0, %w6\n"
 115"       b       3b\n"
 116"       .popsection\n"
 117        _ASM_EXTABLE(1b, 4b)
 118        _ASM_EXTABLE(2b, 4b)
 119        : "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp)
 120        : "r" (oldval), "r" (newval), "Ir" (-EFAULT)
 121        : "memory");
 122        uaccess_disable();
 123
 124        *uval = val;
 125        return ret;
 126}
 127
 128#endif /* __KERNEL__ */
 129#endif /* __ASM_FUTEX_H */
 130