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