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)         \
  27 do {                                                                    \
  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
  50 static inline int
  51 futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
  52 {
  53         int op = (encoded_op >> 28) & 7;
  54         int cmp = (encoded_op >> 24) & 15;
  55         int oparg = (encoded_op << 8) >> 20;
  56         int cmparg = (encoded_op << 20) >> 20;
  57         int oldval = 0, ret, tmp;
  58
  59         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
  60                 oparg = 1 << oparg;
  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
 108 static inline int
 109 futex_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 */