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         smp_mb();                                       \
  24         __asm__ __volatile__(                           \
  25         "1:     llock   %1, [%2]                \n"     \
  26                 insn                            "\n"    \
  27         "2:     scond   %0, [%2]                \n"     \
  28         "       bnz     1b                      \n"     \
  29         "       mov %0, 0                       \n"     \
  30         "3:                                     \n"     \
  31         "       .section .fixup,\"ax\"          \n"     \
  32         "       .align  4                       \n"     \
  33         "4:     mov %0, %4                      \n"     \
  34         "       j   3b                          \n"     \
  35         "       .previous                       \n"     \
  36         "       .section __ex_table,\"a\"       \n"     \
  37         "       .align  4                       \n"     \
  38         "       .word   1b, 4b                  \n"     \
  39         "       .word   2b, 4b                  \n"     \
  40         "       .previous                       \n"     \
  41                                                         \
  42         : "=&r" (ret), "=&r" (oldval)                   \
  43         : "r" (uaddr), "r" (oparg), "ir" (-EFAULT)      \
  44         : "cc", "memory");                              \
  45         smp_mb()                                        \
  46
  47 #else   /* !CONFIG_ARC_HAS_LLSC */
  48
  49 #define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\
  50                                                         \
  51         smp_mb();                                       \
  52         __asm__ __volatile__(                           \
  53         "1:     ld      %1, [%2]                \n"     \
  54                 insn                            "\n"    \
  55         "2:     st      %0, [%2]                \n"     \
  56         "       mov %0, 0                       \n"     \
  57         "3:                                     \n"     \
  58         "       .section .fixup,\"ax\"          \n"     \
  59         "       .align  4                       \n"     \
  60         "4:     mov %0, %4                      \n"     \
  61         "       j   3b                          \n"     \
  62         "       .previous                       \n"     \
  63         "       .section __ex_table,\"a\"       \n"     \
  64         "       .align  4                       \n"     \
  65         "       .word   1b, 4b                  \n"     \
  66         "       .word   2b, 4b                  \n"     \
  67         "       .previous                       \n"     \
  68                                                         \
  69         : "=&r" (ret), "=&r" (oldval)                   \
  70         : "r" (uaddr), "r" (oparg), "ir" (-EFAULT)      \
  71         : "cc", "memory");                              \
  72         smp_mb()                                        \
  73
  74 #endif
  75
  76 static inline int futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
  77 {
  78         int op = (encoded_op >> 28) & 7;
  79         int cmp = (encoded_op >> 24) & 15;
  80         int oparg = (encoded_op << 8) >> 20;
  81         int cmparg = (encoded_op << 20) >> 20;
  82         int oldval = 0, ret;
  83
  84         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
  85                 oparg = 1 << oparg;
  86
  87         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
  88                 return -EFAULT;
  89
  90 #ifndef CONFIG_ARC_HAS_LLSC
  91         preempt_disable();      /* to guarantee atomic r-m-w of futex op */
  92 #endif
  93         pagefault_disable();
  94
  95         switch (op) {
  96         case FUTEX_OP_SET:
  97                 __futex_atomic_op("mov %0, %3", ret, oldval, uaddr, oparg);
  98                 break;
  99         case FUTEX_OP_ADD:
 100                 /* oldval = *uaddr; *uaddr += oparg ; ret = *uaddr */
 101                 __futex_atomic_op("add %0, %1, %3", ret, oldval, uaddr, oparg);
 102                 break;
 103         case FUTEX_OP_OR:
 104                 __futex_atomic_op("or  %0, %1, %3", ret, oldval, uaddr, oparg);
 105                 break;
 106         case FUTEX_OP_ANDN:
 107                 __futex_atomic_op("bic %0, %1, %3", ret, oldval, uaddr, oparg);
 108                 break;
 109         case FUTEX_OP_XOR:
 110                 __futex_atomic_op("xor %0, %1, %3", ret, oldval, uaddr, oparg);
 111                 break;
 112         default:
 113                 ret = -ENOSYS;
 114         }
 115
 116         pagefault_enable();
 117 #ifndef CONFIG_ARC_HAS_LLSC
 118         preempt_enable();
 119 #endif
 120
 121         if (!ret) {
 122                 switch (cmp) {
 123                 case FUTEX_OP_CMP_EQ:
 124                         ret = (oldval == cmparg);
 125                         break;
 126                 case FUTEX_OP_CMP_NE:
 127                         ret = (oldval != cmparg);
 128                         break;
 129                 case FUTEX_OP_CMP_LT:
 130                         ret = (oldval < cmparg);
 131                         break;
 132                 case FUTEX_OP_CMP_GE:
 133                         ret = (oldval >= cmparg);
 134                         break;
 135                 case FUTEX_OP_CMP_LE:
 136                         ret = (oldval <= cmparg);
 137                         break;
 138                 case FUTEX_OP_CMP_GT:
 139                         ret = (oldval > cmparg);
 140                         break;
 141                 default:
 142                         ret = -ENOSYS;
 143                 }
 144         }
 145         return ret;
 146 }
 147
 148 /*
 149  * cmpxchg of futex (pagefaults disabled by caller)
 150  * Return 0 for success, -EFAULT otherwise
 151  */
 152 static inline int
 153 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 expval,
 154                               u32 newval)
 155 {
 156         int ret = 0;
 157         u32 existval;
 158
 159         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
 160                 return -EFAULT;
 161
 162 #ifndef CONFIG_ARC_HAS_LLSC
 163         preempt_disable();      /* to guarantee atomic r-m-w of futex op */
 164 #endif
 165         smp_mb();
 166
 167         __asm__ __volatile__(
 168 #ifdef CONFIG_ARC_HAS_LLSC
 169         "1:     llock   %1, [%4]                \n"
 170         "       brne    %1, %2, 3f              \n"
 171         "2:     scond   %3, [%4]                \n"
 172         "       bnz     1b                      \n"
 173 #else
 174         "1:     ld      %1, [%4]                \n"
 175         "       brne    %1, %2, 3f              \n"
 176         "2:     st      %3, [%4]                \n"
 177 #endif
 178         "3:     \n"
 179         "       .section .fixup,\"ax\"  \n"
 180         "4:     mov %0, %5      \n"
 181         "       j   3b  \n"
 182         "       .previous       \n"
 183         "       .section __ex_table,\"a\"       \n"
 184         "       .align  4       \n"
 185         "       .word   1b, 4b  \n"
 186         "       .word   2b, 4b  \n"
 187         "       .previous\n"
 188         : "+&r"(ret), "=&r"(existval)
 189         : "r"(expval), "r"(newval), "r"(uaddr), "ir"(-EFAULT)
 190         : "cc", "memory");
 191
 192         smp_mb();
 193
 194 #ifndef CONFIG_ARC_HAS_LLSC
 195         preempt_enable();
 196 #endif
 197         *uval = existval;
 198         return ret;
 199 }
 200
 201 #endif