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#include <asm/errno.h>
  24
  25#define __futex_atomic_op(insn, ret, oldval, uaddr, tmp, oparg)         \
  26        asm volatile(                                                   \
  27"1:     ldaxr   %w1, %2\n"                                              \
  28        insn "\n"                                                       \
  29"2:     stlxr   %w3, %w0, %2\n"                                         \
  30"       cbnz    %w3, 1b\n"                                              \
  31"3:\n"                                                                  \
  32"       .pushsection .fixup,\"ax\"\n"                                   \
  33"4:     mov     %w0, %w5\n"                                             \
  34"       b       3b\n"                                                   \
  35"       .popsection\n"                                                  \
  36"       .pushsection __ex_table,\"a\"\n"                                \
  37"       .align  3\n"                                                    \
  38"       .quad   1b, 4b, 2b, 4b\n"                                       \
  39"       .popsection\n"                                                  \
  40        : "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp)       \
  41        : "r" (oparg), "Ir" (-EFAULT)                                   \
  42        : "cc", "memory")
  43
  44static inline int
  45futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
  46{
  47        int op = (encoded_op >> 28) & 7;
  48        int cmp = (encoded_op >> 24) & 15;
  49        int oparg = (encoded_op << 8) >> 20;
  50        int cmparg = (encoded_op << 20) >> 20;
  51        int oldval = 0, ret, tmp;
  52
  53        if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
  54                oparg = 1 << oparg;
  55
  56        if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
  57                return -EFAULT;
  58
  59        pagefault_disable();    /* implies preempt_disable() */
  60
  61        switch (op) {
  62        case FUTEX_OP_SET:
  63                __futex_atomic_op("mov  %w0, %w4",
  64                                  ret, oldval, uaddr, tmp, oparg);
  65                break;
  66        case FUTEX_OP_ADD:
  67                __futex_atomic_op("add  %w0, %w1, %w4",
  68                                  ret, oldval, uaddr, tmp, oparg);
  69                break;
  70        case FUTEX_OP_OR:
  71                __futex_atomic_op("orr  %w0, %w1, %w4",
  72                                  ret, oldval, uaddr, tmp, oparg);
  73                break;
  74        case FUTEX_OP_ANDN:
  75                __futex_atomic_op("and  %w0, %w1, %w4",
  76                                  ret, oldval, uaddr, tmp, ~oparg);
  77                break;
  78        case FUTEX_OP_XOR:
  79                __futex_atomic_op("eor  %w0, %w1, %w4",
  80                                  ret, oldval, uaddr, tmp, oparg);
  81                break;
  82        default:
  83                ret = -ENOSYS;
  84        }
  85
  86        pagefault_enable();     /* subsumes preempt_enable() */
  87
  88        if (!ret) {
  89                switch (cmp) {
  90                case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
  91                case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
  92                case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
  93                case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
  94                case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
  95                case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
  96                default: ret = -ENOSYS;
  97                }
  98        }
  99        return ret;
 100}
 101
 102static inline int
 103futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 104                              u32 oldval, u32 newval)
 105{
 106        int ret = 0;
 107        u32 val, tmp;
 108
 109        if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
 110                return -EFAULT;
 111
 112        asm volatile("// futex_atomic_cmpxchg_inatomic\n"
 113"1:     ldaxr   %w1, %2\n"
 114"       sub     %w3, %w1, %w4\n"
 115"       cbnz    %w3, 3f\n"
 116"2:     stlxr   %w3, %w5, %2\n"
 117"       cbnz    %w3, 1b\n"
 118"3:\n"
 119"       .pushsection .fixup,\"ax\"\n"
 120"4:     mov     %w0, %w6\n"
 121"       b       3b\n"
 122"       .popsection\n"
 123"       .pushsection __ex_table,\"a\"\n"
 124"       .align  3\n"
 125"       .quad   1b, 4b, 2b, 4b\n"
 126"       .popsection\n"
 127        : "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp)
 128        : "r" (oldval), "r" (newval), "Ir" (-EFAULT)
 129        : "cc", "memory");
 130
 131        *uval = val;
 132        return ret;
 133}
 134
 135#endif /* __KERNEL__ */
 136#endif /* __ASM_FUTEX_H */
 137