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 arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
  52 {
  53         int oldval = 0, ret, tmp;
  54
  55         pagefault_disable();
  56
  57         switch (op) {
  58         case FUTEX_OP_SET:
  59                 __futex_atomic_op("mov  %w0, %w4",
  60                                   ret, oldval, uaddr, tmp, oparg);
  61                 break;
  62         case FUTEX_OP_ADD:
  63                 __futex_atomic_op("add  %w0, %w1, %w4",
  64                                   ret, oldval, uaddr, tmp, oparg);
  65                 break;
  66         case FUTEX_OP_OR:
  67                 __futex_atomic_op("orr  %w0, %w1, %w4",
  68                                   ret, oldval, uaddr, tmp, oparg);
  69                 break;
  70         case FUTEX_OP_ANDN:
  71                 __futex_atomic_op("and  %w0, %w1, %w4",
  72                                   ret, oldval, uaddr, tmp, ~oparg);
  73                 break;
  74         case FUTEX_OP_XOR:
  75                 __futex_atomic_op("eor  %w0, %w1, %w4",
  76                                   ret, oldval, uaddr, tmp, oparg);
  77                 break;
  78         default:
  79                 ret = -ENOSYS;
  80         }
  81
  82         pagefault_enable();
  83
  84         if (!ret)
  85                 *oval = oldval;
  86
  87         return ret;
  88 }
  89
  90 static inline int
  91 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
  92                               u32 oldval, u32 newval)
  93 {
  94         int ret = 0;
  95         u32 val, tmp;
  96
  97         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
  98                 return -EFAULT;
  99
 100         uaccess_enable();
 101         asm volatile("// futex_atomic_cmpxchg_inatomic\n"
 102 "       prfm    pstl1strm, %2\n"
 103 "1:     ldxr    %w1, %2\n"
 104 "       sub     %w3, %w1, %w4\n"
 105 "       cbnz    %w3, 3f\n"
 106 "2:     stlxr   %w3, %w5, %2\n"
 107 "       cbnz    %w3, 1b\n"
 108 "       dmb     ish\n"
 109 "3:\n"
 110 "       .pushsection .fixup,\"ax\"\n"
 111 "4:     mov     %w0, %w6\n"
 112 "       b       3b\n"
 113 "       .popsection\n"
 114         _ASM_EXTABLE(1b, 4b)
 115         _ASM_EXTABLE(2b, 4b)
 116         : "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp)
 117         : "r" (oldval), "r" (newval), "Ir" (-EFAULT)
 118         : "memory");
 119         uaccess_disable();
 120
 121         *uval = val;
 122         return ret;
 123 }
 124
 125 #endif /* __KERNEL__ */
 126 #endif /* __ASM_FUTEX_H */