kernel/include/asm-generic/futex.h

   1 #ifndef _ASM_GENERIC_FUTEX_H
   2 #define _ASM_GENERIC_FUTEX_H
   3
   4 #include <linux/futex.h>
   5 #include <linux/uaccess.h>
   6 #include <asm/errno.h>
   7
   8 #ifndef CONFIG_SMP
   9 /*
  10  * The following implementation only for uniprocessor machines.
  11  * It relies on preempt_disable() ensuring mutual exclusion.
  12  *
  13  */
  14
  15 /**
  16  * futex_atomic_op_inuser() - Atomic arithmetic operation with constant
  17  *                        argument and comparison of the previous
  18  *                        futex value with another constant.
  19  *
  20  * @encoded_op: encoded operation to execute
  21  * @uaddr:      pointer to user space address
  22  *
  23  * Return:
  24  * 0 - On success
  25  * <0 - On error
  26  */
  27 static inline int
  28 futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
  29 {
  30         int op = (encoded_op >> 28) & 7;
  31         int cmp = (encoded_op >> 24) & 15;
  32         int oparg = (encoded_op << 8) >> 20;
  33         int cmparg = (encoded_op << 20) >> 20;
  34         int oldval, ret;
  35         u32 tmp;
  36
  37         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
  38                 oparg = 1 << oparg;
  39
  40         preempt_disable();
  41         pagefault_disable();
  42
  43         ret = -EFAULT;
  44         if (unlikely(get_user(oldval, uaddr) != 0))
  45                 goto out_pagefault_enable;
  46
  47         ret = 0;
  48         tmp = oldval;
  49
  50         switch (op) {
  51         case FUTEX_OP_SET:
  52                 tmp = oparg;
  53                 break;
  54         case FUTEX_OP_ADD:
  55                 tmp += oparg;
  56                 break;
  57         case FUTEX_OP_OR:
  58                 tmp |= oparg;
  59                 break;
  60         case FUTEX_OP_ANDN:
  61                 tmp &= ~oparg;
  62                 break;
  63         case FUTEX_OP_XOR:
  64                 tmp ^= oparg;
  65                 break;
  66         default:
  67                 ret = -ENOSYS;
  68         }
  69
  70         if (ret == 0 && unlikely(put_user(tmp, uaddr) != 0))
  71                 ret = -EFAULT;
  72
  73 out_pagefault_enable:
  74         pagefault_enable();
  75         preempt_enable();
  76
  77         if (ret == 0) {
  78                 switch (cmp) {
  79                 case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
  80                 case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
  81                 case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
  82                 case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
  83                 case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
  84                 case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
  85                 default: ret = -ENOSYS;
  86                 }
  87         }
  88         return ret;
  89 }
  90
  91 /**
  92  * futex_atomic_cmpxchg_inatomic() - Compare and exchange the content of the
  93  *                              uaddr with newval if the current value is
  94  *                              oldval.
  95  * @uval:       pointer to store content of @uaddr
  96  * @uaddr:      pointer to user space address
  97  * @oldval:     old value
  98  * @newval:     new value to store to @uaddr
  99  *
 100  * Return:
 101  * 0 - On success
 102  * <0 - On error
 103  */
 104 static inline int
 105 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 106                               u32 oldval, u32 newval)
 107 {
 108         u32 val;
 109
 110         preempt_disable();
 111         if (unlikely(get_user(val, uaddr) != 0))
 112                 return -EFAULT;
 113
 114         if (val == oldval && unlikely(put_user(newval, uaddr) != 0))
 115                 return -EFAULT;
 116
 117         *uval = val;
 118         preempt_enable();
 119
 120         return 0;
 121 }
 122
 123 #else
 124 static inline int
 125 futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
 126 {
 127         int op = (encoded_op >> 28) & 7;
 128         int cmp = (encoded_op >> 24) & 15;
 129         int oparg = (encoded_op << 8) >> 20;
 130         int cmparg = (encoded_op << 20) >> 20;
 131         int oldval = 0, ret;
 132         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
 133                 oparg = 1 << oparg;
 134
 135         if (! access_ok (VERIFY_WRITE, uaddr, sizeof(u32)))
 136                 return -EFAULT;
 137
 138         pagefault_disable();
 139
 140         switch (op) {
 141         case FUTEX_OP_SET:
 142         case FUTEX_OP_ADD:
 143         case FUTEX_OP_OR:
 144         case FUTEX_OP_ANDN:
 145         case FUTEX_OP_XOR:
 146         default:
 147                 ret = -ENOSYS;
 148         }
 149
 150         pagefault_enable();
 151
 152         if (!ret) {
 153                 switch (cmp) {
 154                 case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
 155                 case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
 156                 case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
 157                 case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
 158                 case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
 159                 case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
 160                 default: ret = -ENOSYS;
 161                 }
 162         }
 163         return ret;
 164 }
 165
 166 static inline int
 167 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 168                               u32 oldval, u32 newval)
 169 {
 170         return -ENOSYS;
 171 }
 172
 173 #endif /* CONFIG_SMP */
 174 #endif