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/alternative.h>
  25 #include <asm/cpufeature.h>
  26 #include <asm/errno.h>
  27 #include <asm/sysreg.h>
  28
  29 #define __futex_atomic_op(insn, ret, oldval, uaddr, tmp, oparg)         \
  30         asm volatile(                                                   \
  31         ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN,            \
  32                     CONFIG_ARM64_PAN)                                   \
  33 "       prfm    pstl1strm, %2\n"                                        \
  34 "1:     ldxr    %w1, %2\n"                                              \
  35         insn "\n"                                                       \
  36 "2:     stlxr   %w3, %w0, %2\n"                                         \
  37 "       cbnz    %w3, 1b\n"                                              \
  38 "       dmb     ish\n"                                                  \
  39 "3:\n"                                                                  \
  40 "       .pushsection .fixup,\"ax\"\n"                                   \
  41 "       .align  2\n"                                                    \
  42 "4:     mov     %w0, %w5\n"                                             \
  43 "       b       3b\n"                                                   \
  44 "       .popsection\n"                                                  \
  45         _ASM_EXTABLE(1b, 4b)                                            \
  46         _ASM_EXTABLE(2b, 4b)                                            \
  47         ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN,            \
  48                     CONFIG_ARM64_PAN)                                   \
  49         : "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp)       \
  50         : "r" (oparg), "Ir" (-EFAULT)                                   \
  51         : "memory")
  52
  53 static inline int
  54 futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
  55 {
  56         int op = (encoded_op >> 28) & 7;
  57         int cmp = (encoded_op >> 24) & 15;
  58         int oparg = (encoded_op << 8) >> 20;
  59         int cmparg = (encoded_op << 20) >> 20;
  60         int oldval = 0, ret, tmp;
  61
  62         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
  63                 oparg = 1 << oparg;
  64
  65         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
  66                 return -EFAULT;
  67
  68         pagefault_disable();
  69
  70         switch (op) {
  71         case FUTEX_OP_SET:
  72                 __futex_atomic_op("mov  %w0, %w4",
  73                                   ret, oldval, uaddr, tmp, oparg);
  74                 break;
  75         case FUTEX_OP_ADD:
  76                 __futex_atomic_op("add  %w0, %w1, %w4",
  77                                   ret, oldval, uaddr, tmp, oparg);
  78                 break;
  79         case FUTEX_OP_OR:
  80                 __futex_atomic_op("orr  %w0, %w1, %w4",
  81                                   ret, oldval, uaddr, tmp, oparg);
  82                 break;
  83         case FUTEX_OP_ANDN:
  84                 __futex_atomic_op("and  %w0, %w1, %w4",
  85                                   ret, oldval, uaddr, tmp, ~oparg);
  86                 break;
  87         case FUTEX_OP_XOR:
  88                 __futex_atomic_op("eor  %w0, %w1, %w4",
  89                                   ret, oldval, uaddr, tmp, oparg);
  90                 break;
  91         default:
  92                 ret = -ENOSYS;
  93         }
  94
  95         pagefault_enable();
  96
  97         if (!ret) {
  98                 switch (cmp) {
  99                 case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
 100                 case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
 101                 case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
 102                 case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
 103                 case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
 104                 case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
 105                 default: ret = -ENOSYS;
 106                 }
 107         }
 108         return ret;
 109 }
 110
 111 static inline int
 112 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 113                               u32 oldval, u32 newval)
 114 {
 115         int ret = 0;
 116         u32 val, tmp;
 117
 118         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
 119                 return -EFAULT;
 120
 121         asm volatile("// futex_atomic_cmpxchg_inatomic\n"
 122 ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, CONFIG_ARM64_PAN)
 123 "       prfm    pstl1strm, %2\n"
 124 "1:     ldxr    %w1, %2\n"
 125 "       sub     %w3, %w1, %w4\n"
 126 "       cbnz    %w3, 3f\n"
 127 "2:     stlxr   %w3, %w5, %2\n"
 128 "       cbnz    %w3, 1b\n"
 129 "       dmb     ish\n"
 130 "3:\n"
 131 "       .pushsection .fixup,\"ax\"\n"
 132 "4:     mov     %w0, %w6\n"
 133 "       b       3b\n"
 134 "       .popsection\n"
 135         _ASM_EXTABLE(1b, 4b)
 136         _ASM_EXTABLE(2b, 4b)
 137 ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, CONFIG_ARM64_PAN)
 138         : "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp)
 139         : "r" (oldval), "r" (newval), "Ir" (-EFAULT)
 140         : "memory");
 141
 142         *uval = val;
 143         return ret;
 144 }
 145
 146 #endif /* __KERNEL__ */
 147 #endif /* __ASM_FUTEX_H */