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   %w3, %w0, %2\n"                                         \
  34"       cbnz    %w3, 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
  51futex_atomic_op_inuser(unsigned int encoded_op, u32 __user *uaddr)
  52{
  53        int op = (encoded_op >> 28) & 7;
  54        int cmp = (encoded_op >> 24) & 15;
  55        int oparg = (int)(encoded_op << 8) >> 20;
  56        int cmparg = (int)(encoded_op << 20) >> 20;
  57        int oldval = 0, ret, tmp;
  58
  59        if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
  60                oparg = 1U << (oparg & 0x1f);
  61
  62        if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
  63                return -EFAULT;
  64
  65        pagefault_disable();
  66
  67        switch (op) {
  68        case FUTEX_OP_SET:
  69                __futex_atomic_op("mov  %w0, %w4",
  70                                  ret, oldval, uaddr, tmp, oparg);
  71                break;
  72        case FUTEX_OP_ADD:
  73                __futex_atomic_op("add  %w0, %w1, %w4",
  74                                  ret, oldval, uaddr, tmp, oparg);
  75                break;
  76        case FUTEX_OP_OR:
  77                __futex_atomic_op("orr  %w0, %w1, %w4",
  78                                  ret, oldval, uaddr, tmp, oparg);
  79                break;
  80        case FUTEX_OP_ANDN:
  81                __futex_atomic_op("and  %w0, %w1, %w4",
  82                                  ret, oldval, uaddr, tmp, ~oparg);
  83                break;
  84        case FUTEX_OP_XOR:
  85                __futex_atomic_op("eor  %w0, %w1, %w4",
  86                                  ret, oldval, uaddr, tmp, oparg);
  87                break;
  88        default:
  89                ret = -ENOSYS;
  90        }
  91
  92        pagefault_enable();
  93
  94        if (!ret) {
  95                switch (cmp) {
  96                case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
  97                case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
  98                case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
  99                case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
 100                case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
 101                case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
 102                default: ret = -ENOSYS;
 103                }
 104        }
 105        return ret;
 106}
 107
 108static inline int
 109futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 110                              u32 oldval, u32 newval)
 111{
 112        int ret = 0;
 113        u32 val, tmp;
 114
 115        if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
 116                return -EFAULT;
 117
 118        uaccess_enable();
 119        asm volatile("// futex_atomic_cmpxchg_inatomic\n"
 120"       prfm    pstl1strm, %2\n"
 121"1:     ldxr    %w1, %2\n"
 122"       sub     %w3, %w1, %w4\n"
 123"       cbnz    %w3, 3f\n"
 124"2:     stlxr   %w3, %w5, %2\n"
 125"       cbnz    %w3, 1b\n"
 126"       dmb     ish\n"
 127"3:\n"
 128"       .pushsection .fixup,\"ax\"\n"
 129"4:     mov     %w0, %w6\n"
 130"       b       3b\n"
 131"       .popsection\n"
 132        _ASM_EXTABLE(1b, 4b)
 133        _ASM_EXTABLE(2b, 4b)
 134        : "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp)
 135        : "r" (oldval), "r" (newval), "Ir" (-EFAULT)
 136        : "memory");
 137        uaccess_disable();
 138
 139        *uval = val;
 140        return ret;
 141}
 142
 143#endif /* __KERNEL__ */
 144#endif /* __ASM_FUTEX_H */
 145