arch/arc/include/asm/futex.h

   1 /*
   2  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
   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  * Vineetg: August 2010: From Android kernel work
   9  */
  10
  11 #ifndef _ASM_FUTEX_H
  12 #define _ASM_FUTEX_H
  13
  14 #include <linux/futex.h>
  15 #include <linux/preempt.h>
  16 #include <linux/uaccess.h>
  17 #include <asm/errno.h>
  18
  19 #ifdef CONFIG_ARC_HAS_LLSC
  20
  21 #define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\
  22                                                         \
  23         __asm__ __volatile__(                           \
  24         "1:     llock   %1, [%2]                \n"     \
  25                 insn                            "\n"    \
  26         "2:     scond   %0, [%2]                \n"     \
  27         "       bnz     1b                      \n"     \
  28         "       mov %0, 0                       \n"     \
  29         "3:                                     \n"     \
  30         "       .section .fixup,\"ax\"          \n"     \
  31         "       .align  4                       \n"     \
  32         "4:     mov %0, %4                      \n"     \
  33         "       b   3b                          \n"     \
  34         "       .previous                       \n"     \
  35         "       .section __ex_table,\"a\"       \n"     \
  36         "       .align  4                       \n"     \
  37         "       .word   1b, 4b                  \n"     \
  38         "       .word   2b, 4b                  \n"     \
  39         "       .previous                       \n"     \
  40                                                         \
  41         : "=&r" (ret), "=&r" (oldval)                   \
  42         : "r" (uaddr), "r" (oparg), "ir" (-EFAULT)      \
  43         : "cc", "memory")
  44
  45 #else   /* !CONFIG_ARC_HAS_LLSC */
  46
  47 #define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\
  48                                                         \
  49         __asm__ __volatile__(                           \
  50         "1:     ld      %1, [%2]                \n"     \
  51                 insn                            "\n"    \
  52         "2:     st      %0, [%2]                \n"     \
  53         "       mov %0, 0                       \n"     \
  54         "3:                                     \n"     \
  55         "       .section .fixup,\"ax\"          \n"     \
  56         "       .align  4                       \n"     \
  57         "4:     mov %0, %4                      \n"     \
  58         "       b   3b                          \n"     \
  59         "       .previous                       \n"     \
  60         "       .section __ex_table,\"a\"       \n"     \
  61         "       .align  4                       \n"     \
  62         "       .word   1b, 4b                  \n"     \
  63         "       .word   2b, 4b                  \n"     \
  64         "       .previous                       \n"     \
  65                                                         \
  66         : "=&r" (ret), "=&r" (oldval)                   \
  67         : "r" (uaddr), "r" (oparg), "ir" (-EFAULT)      \
  68         : "cc", "memory")
  69
  70 #endif
  71
  72 static inline int futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
  73 {
  74         int op = (encoded_op >> 28) & 7;
  75         int cmp = (encoded_op >> 24) & 15;
  76         int oparg = (encoded_op << 8) >> 20;
  77         int cmparg = (encoded_op << 20) >> 20;
  78         int oldval = 0, ret;
  79
  80         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
  81                 oparg = 1 << oparg;
  82
  83         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
  84                 return -EFAULT;
  85
  86         pagefault_disable();
  87
  88         switch (op) {
  89         case FUTEX_OP_SET:
  90                 __futex_atomic_op("mov %0, %3", ret, oldval, uaddr, oparg);
  91                 break;
  92         case FUTEX_OP_ADD:
  93                 __futex_atomic_op("add %0, %1, %3", ret, oldval, uaddr, oparg);
  94                 break;
  95         case FUTEX_OP_OR:
  96                 __futex_atomic_op("or  %0, %1, %3", ret, oldval, uaddr, oparg);
  97                 break;
  98         case FUTEX_OP_ANDN:
  99                 __futex_atomic_op("bic %0, %1, %3", ret, oldval, uaddr, oparg);
 100                 break;
 101         case FUTEX_OP_XOR:
 102                 __futex_atomic_op("xor %0, %1, %3", ret, oldval, uaddr, oparg);
 103                 break;
 104         default:
 105                 ret = -ENOSYS;
 106         }
 107
 108         pagefault_enable();
 109
 110         if (!ret) {
 111                 switch (cmp) {
 112                 case FUTEX_OP_CMP_EQ:
 113                         ret = (oldval == cmparg);
 114                         break;
 115                 case FUTEX_OP_CMP_NE:
 116                         ret = (oldval != cmparg);
 117                         break;
 118                 case FUTEX_OP_CMP_LT:
 119                         ret = (oldval < cmparg);
 120                         break;
 121                 case FUTEX_OP_CMP_GE:
 122                         ret = (oldval >= cmparg);
 123                         break;
 124                 case FUTEX_OP_CMP_LE:
 125                         ret = (oldval <= cmparg);
 126                         break;
 127                 case FUTEX_OP_CMP_GT:
 128                         ret = (oldval > cmparg);
 129                         break;
 130                 default:
 131                         ret = -ENOSYS;
 132                 }
 133         }
 134         return ret;
 135 }
 136
 137 /* Compare-xchg with pagefaults disabled.
 138  *  Notes:
 139  *      -Best-Effort: Exchg happens only if compare succeeds.
 140  *          If compare fails, returns; leaving retry/looping to upper layers
 141  *      -successful cmp-xchg: return orig value in @addr (same as cmp val)
 142  *      -Compare fails: return orig value in @addr
 143  *      -user access r/w fails: return -EFAULT
 144  */
 145 static inline int
 146 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 oldval,
 147                                         u32 newval)
 148 {
 149         u32 val;
 150
 151         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
 152                 return -EFAULT;
 153
 154         pagefault_disable();
 155
 156         __asm__ __volatile__(
 157 #ifdef CONFIG_ARC_HAS_LLSC
 158         "1:     llock   %0, [%3]                \n"
 159         "       brne    %0, %1, 3f              \n"
 160         "2:     scond   %2, [%3]                \n"
 161         "       bnz     1b                      \n"
 162 #else
 163         "1:     ld      %0, [%3]                \n"
 164         "       brne    %0, %1, 3f              \n"
 165         "2:     st      %2, [%3]                \n"
 166 #endif
 167         "3:     \n"
 168         "       .section .fixup,\"ax\"  \n"
 169         "4:     mov %0, %4      \n"
 170         "       b   3b  \n"
 171         "       .previous       \n"
 172         "       .section __ex_table,\"a\"       \n"
 173         "       .align  4       \n"
 174         "       .word   1b, 4b  \n"
 175         "       .word   2b, 4b  \n"
 176         "       .previous\n"
 177         : "=&r"(val)
 178         : "r"(oldval), "r"(newval), "r"(uaddr), "ir"(-EFAULT)
 179         : "cc", "memory");
 180
 181         pagefault_enable();
 182
 183         *uval = val;
 184         return val;
 185 }
 186
 187 #endif