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 arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
  77                 u32 __user *uaddr)
  78 {
  79         int oldval = 0, ret;
  80
  81 #ifndef CONFIG_ARC_HAS_LLSC
  82         preempt_disable();      /* to guarantee atomic r-m-w of futex op */
  83 #endif
  84         pagefault_disable();
  85
  86         switch (op) {
  87         case FUTEX_OP_SET:
  88                 __futex_atomic_op("mov %0, %3", ret, oldval, uaddr, oparg);
  89                 break;
  90         case FUTEX_OP_ADD:
  91                 /* oldval = *uaddr; *uaddr += oparg ; ret = *uaddr */
  92                 __futex_atomic_op("add %0, %1, %3", ret, oldval, uaddr, oparg);
  93                 break;
  94         case FUTEX_OP_OR:
  95                 __futex_atomic_op("or  %0, %1, %3", ret, oldval, uaddr, oparg);
  96                 break;
  97         case FUTEX_OP_ANDN:
  98                 __futex_atomic_op("bic %0, %1, %3", ret, oldval, uaddr, oparg);
  99                 break;
 100         case FUTEX_OP_XOR:
 101                 __futex_atomic_op("xor %0, %1, %3", ret, oldval, uaddr, oparg);
 102                 break;
 103         default:
 104                 ret = -ENOSYS;
 105         }
 106
 107         pagefault_enable();
 108 #ifndef CONFIG_ARC_HAS_LLSC
 109         preempt_enable();
 110 #endif
 111
 112         if (!ret)
 113                 *oval = oldval;
 114
 115         return ret;
 116 }
 117
 118 /*
 119  * cmpxchg of futex (pagefaults disabled by caller)
 120  * Return 0 for success, -EFAULT otherwise
 121  */
 122 static inline int
 123 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 expval,
 124                               u32 newval)
 125 {
 126         int ret = 0;
 127         u32 existval;
 128
 129         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
 130                 return -EFAULT;
 131
 132 #ifndef CONFIG_ARC_HAS_LLSC
 133         preempt_disable();      /* to guarantee atomic r-m-w of futex op */
 134 #endif
 135         smp_mb();
 136
 137         __asm__ __volatile__(
 138 #ifdef CONFIG_ARC_HAS_LLSC
 139         "1:     llock   %1, [%4]                \n"
 140         "       brne    %1, %2, 3f              \n"
 141         "2:     scond   %3, [%4]                \n"
 142         "       bnz     1b                      \n"
 143 #else
 144         "1:     ld      %1, [%4]                \n"
 145         "       brne    %1, %2, 3f              \n"
 146         "2:     st      %3, [%4]                \n"
 147 #endif
 148         "3:     \n"
 149         "       .section .fixup,\"ax\"  \n"
 150         "4:     mov %0, %5      \n"
 151         "       j   3b  \n"
 152         "       .previous       \n"
 153         "       .section __ex_table,\"a\"       \n"
 154         "       .align  4       \n"
 155         "       .word   1b, 4b  \n"
 156         "       .word   2b, 4b  \n"
 157         "       .previous\n"
 158         : "+&r"(ret), "=&r"(existval)
 159         : "r"(expval), "r"(newval), "r"(uaddr), "ir"(-EFAULT)
 160         : "cc", "memory");
 161
 162         smp_mb();
 163
 164 #ifndef CONFIG_ARC_HAS_LLSC
 165         preempt_enable();
 166 #endif
 167         *uval = existval;
 168         return ret;
 169 }
 170
 171 #endif