Linux Kernel  3.7.1
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futex.h
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1 #ifndef _ASM_PARISC_FUTEX_H
2 #define _ASM_PARISC_FUTEX_H
3 
4 #ifdef __KERNEL__
5 
6 #include <linux/futex.h>
7 #include <linux/uaccess.h>
8 #include <asm/atomic.h>
9 #include <asm/errno.h>
10 
11 /* The following has to match the LWS code in syscall.S. We have
12  sixteen four-word locks. */
13 
14 static inline void
15 _futex_spin_lock_irqsave(u32 __user *uaddr, unsigned long int *flags)
16 {
17  extern u32 lws_lock_start[];
18  long index = ((long)uaddr & 0xf0) >> 2;
19  arch_spinlock_t *s = (arch_spinlock_t *)&lws_lock_start[index];
20  local_irq_save(*flags);
21  arch_spin_lock(s);
22 }
23 
24 static inline void
25 _futex_spin_unlock_irqrestore(u32 __user *uaddr, unsigned long int *flags)
26 {
27  extern u32 lws_lock_start[];
28  long index = ((long)uaddr & 0xf0) >> 2;
29  arch_spinlock_t *s = (arch_spinlock_t *)&lws_lock_start[index];
31  local_irq_restore(*flags);
32 }
33 
34 static inline int
35 futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr)
36 {
37  unsigned long int flags;
38  u32 val;
39  int op = (encoded_op >> 28) & 7;
40  int cmp = (encoded_op >> 24) & 15;
41  int oparg = (encoded_op << 8) >> 20;
42  int cmparg = (encoded_op << 20) >> 20;
43  int oldval = 0, ret;
44  if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
45  oparg = 1 << oparg;
46 
47  if (!access_ok(VERIFY_WRITE, uaddr, sizeof(*uaddr)))
48  return -EFAULT;
49 
50  pagefault_disable();
51 
52  _futex_spin_lock_irqsave(uaddr, &flags);
53 
54  switch (op) {
55  case FUTEX_OP_SET:
56  /* *(int *)UADDR2 = OPARG; */
57  ret = get_user(oldval, uaddr);
58  if (!ret)
59  ret = put_user(oparg, uaddr);
60  break;
61  case FUTEX_OP_ADD:
62  /* *(int *)UADDR2 += OPARG; */
63  ret = get_user(oldval, uaddr);
64  if (!ret) {
65  val = oldval + oparg;
66  ret = put_user(val, uaddr);
67  }
68  break;
69  case FUTEX_OP_OR:
70  /* *(int *)UADDR2 |= OPARG; */
71  ret = get_user(oldval, uaddr);
72  if (!ret) {
73  val = oldval | oparg;
74  ret = put_user(val, uaddr);
75  }
76  break;
77  case FUTEX_OP_ANDN:
78  /* *(int *)UADDR2 &= ~OPARG; */
79  ret = get_user(oldval, uaddr);
80  if (!ret) {
81  val = oldval & ~oparg;
82  ret = put_user(val, uaddr);
83  }
84  break;
85  case FUTEX_OP_XOR:
86  /* *(int *)UADDR2 ^= OPARG; */
87  ret = get_user(oldval, uaddr);
88  if (!ret) {
89  val = oldval ^ oparg;
90  ret = put_user(val, uaddr);
91  }
92  break;
93  default:
94  ret = -ENOSYS;
95  }
96 
97  _futex_spin_unlock_irqrestore(uaddr, &flags);
98 
99  pagefault_enable();
100 
101  if (!ret) {
102  switch (cmp) {
103  case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
104  case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
105  case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
106  case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
107  case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
108  case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
109  default: ret = -ENOSYS;
110  }
111  }
112  return ret;
113 }
114 
115 /* Non-atomic version */
116 static inline int
117 futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
118  u32 oldval, u32 newval)
119 {
120  int ret;
121  u32 val;
122  unsigned long flags;
123 
124  /* futex.c wants to do a cmpxchg_inatomic on kernel NULL, which is
125  * our gateway page, and causes no end of trouble...
126  */
127  if (segment_eq(KERNEL_DS, get_fs()) && !uaddr)
128  return -EFAULT;
129 
130  if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
131  return -EFAULT;
132 
133  /* HPPA has no cmpxchg in hardware and therefore the
134  * best we can do here is use an array of locks. The
135  * lock selected is based on a hash of the userspace
136  * address. This should scale to a couple of CPUs.
137  */
138 
139  _futex_spin_lock_irqsave(uaddr, &flags);
140 
141  ret = get_user(val, uaddr);
142 
143  if (!ret && val == oldval)
144  ret = put_user(newval, uaddr);
145 
146  *uval = val;
147 
148  _futex_spin_unlock_irqrestore(uaddr, &flags);
149 
150  return ret;
151 }
152 
153 #endif /*__KERNEL__*/
154 #endif /*_ASM_PARISC_FUTEX_H*/