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 #define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\
  20                                                         \
  21         __asm__ __volatile__(                           \
  22         "1:     ld  %1, [%2]                    \n"     \
  23                 insn                            "\n"    \
  24         "2:     st  %0, [%2]                    \n"     \
  25         "       mov %0, 0                       \n"     \
  26         "3:                                     \n"     \
  27         "       .section .fixup,\"ax\"          \n"     \
  28         "       .align  4                       \n"     \
  29         "4:     mov %0, %4                      \n"     \
  30         "       b   3b                          \n"     \
  31         "       .previous                       \n"     \
  32         "       .section __ex_table,\"a\"       \n"     \
  33         "       .align  4                       \n"     \
  34         "       .word   1b, 4b                  \n"     \
  35         "       .word   2b, 4b                  \n"     \
  36         "       .previous                       \n"     \
  37                                                         \
  38         : "=&r" (ret), "=&r" (oldval)                   \
  39         : "r" (uaddr), "r" (oparg), "ir" (-EFAULT)      \
  40         : "cc", "memory")
  41
  42 static inline int futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
  43 {
  44         int op = (encoded_op >> 28) & 7;
  45         int cmp = (encoded_op >> 24) & 15;
  46         int oparg = (encoded_op << 8) >> 20;
  47         int cmparg = (encoded_op << 20) >> 20;
  48         int oldval = 0, ret;
  49
  50         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
  51                 oparg = 1 << oparg;
  52
  53         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
  54                 return -EFAULT;
  55
  56         pagefault_disable();    /* implies preempt_disable() */
  57
  58         switch (op) {
  59         case FUTEX_OP_SET:
  60                 __futex_atomic_op("mov %0, %3", ret, oldval, uaddr, oparg);
  61                 break;
  62         case FUTEX_OP_ADD:
  63                 __futex_atomic_op("add %0, %1, %3", ret, oldval, uaddr, oparg);
  64                 break;
  65         case FUTEX_OP_OR:
  66                 __futex_atomic_op("or  %0, %1, %3", ret, oldval, uaddr, oparg);
  67                 break;
  68         case FUTEX_OP_ANDN:
  69                 __futex_atomic_op("bic %0, %1, %3", ret, oldval, uaddr, oparg);
  70                 break;
  71         case FUTEX_OP_XOR:
  72                 __futex_atomic_op("xor %0, %1, %3", ret, oldval, uaddr, oparg);
  73                 break;
  74         default:
  75                 ret = -ENOSYS;
  76         }
  77
  78         pagefault_enable();     /* subsumes preempt_enable() */
  79
  80         if (!ret) {
  81                 switch (cmp) {
  82                 case FUTEX_OP_CMP_EQ:
  83                         ret = (oldval == cmparg);
  84                         break;
  85                 case FUTEX_OP_CMP_NE:
  86                         ret = (oldval != cmparg);
  87                         break;
  88                 case FUTEX_OP_CMP_LT:
  89                         ret = (oldval < cmparg);
  90                         break;
  91                 case FUTEX_OP_CMP_GE:
  92                         ret = (oldval >= cmparg);
  93                         break;
  94                 case FUTEX_OP_CMP_LE:
  95                         ret = (oldval <= cmparg);
  96                         break;
  97                 case FUTEX_OP_CMP_GT:
  98                         ret = (oldval > cmparg);
  99                         break;
 100                 default:
 101                         ret = -ENOSYS;
 102                 }
 103         }
 104         return ret;
 105 }
 106
 107 /* Compare-xchg with preemption disabled.
 108  *  Notes:
 109  *      -Best-Effort: Exchg happens only if compare succeeds.
 110  *          If compare fails, returns; leaving retry/looping to upper layers
 111  *      -successful cmp-xchg: return orig value in @addr (same as cmp val)
 112  *      -Compare fails: return orig value in @addr
 113  *      -user access r/w fails: return -EFAULT
 114  */
 115 static inline int
 116 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 oldval,
 117                                         u32 newval)
 118 {
 119         u32 val;
 120
 121         if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
 122                 return -EFAULT;
 123
 124         pagefault_disable();    /* implies preempt_disable() */
 125
 126         /* TBD : can use llock/scond */
 127         __asm__ __volatile__(
 128         "1:     ld    %0, [%3]  \n"
 129         "       brne  %0, %1, 3f        \n"
 130         "2:     st    %2, [%3]  \n"
 131         "3:     \n"
 132         "       .section .fixup,\"ax\"  \n"
 133         "4:     mov %0, %4      \n"
 134         "       b   3b  \n"
 135         "       .previous       \n"
 136         "       .section __ex_table,\"a\"       \n"
 137         "       .align  4       \n"
 138         "       .word   1b, 4b  \n"
 139         "       .word   2b, 4b  \n"
 140         "       .previous\n"
 141         : "=&r"(val)
 142         : "r"(oldval), "r"(newval), "r"(uaddr), "ir"(-EFAULT)
 143         : "cc", "memory");
 144
 145         pagefault_enable();     /* subsumes preempt_enable() */
 146
 147         *uval = val;
 148         return val;
 149 }
 150
 151 #endif