use clamp_t in UNAME26 fix
[linux-2.6.git] / kernel / futex_compat.c
1 /*
2  * linux/kernel/futex_compat.c
3  *
4  * Futex compatibililty routines.
5  *
6  * Copyright 2006, Red Hat, Inc., Ingo Molnar
7  */
8
9 #include <linux/linkage.h>
10 #include <linux/compat.h>
11 #include <linux/nsproxy.h>
12 #include <linux/futex.h>
13 #include <linux/ptrace.h>
14
15 #include <asm/uaccess.h>
16
17
18 /*
19  * Fetch a robust-list pointer. Bit 0 signals PI futexes:
20  */
21 static inline int
22 fetch_robust_entry(compat_uptr_t *uentry, struct robust_list __user **entry,
23                    compat_uptr_t __user *head, unsigned int *pi)
24 {
25         if (get_user(*uentry, head))
26                 return -EFAULT;
27
28         *entry = compat_ptr((*uentry) & ~1);
29         *pi = (unsigned int)(*uentry) & 1;
30
31         return 0;
32 }
33
34 static void __user *futex_uaddr(struct robust_list __user *entry,
35                                 compat_long_t futex_offset)
36 {
37         compat_uptr_t base = ptr_to_compat(entry);
38         void __user *uaddr = compat_ptr(base + futex_offset);
39
40         return uaddr;
41 }
42
43 /*
44  * Walk curr->robust_list (very carefully, it's a userspace list!)
45  * and mark any locks found there dead, and notify any waiters.
46  *
47  * We silently return on any sign of list-walking problem.
48  */
49 void compat_exit_robust_list(struct task_struct *curr)
50 {
51         struct compat_robust_list_head __user *head = curr->compat_robust_list;
52         struct robust_list __user *entry, *next_entry, *pending;
53         unsigned int limit = ROBUST_LIST_LIMIT, pi, pip;
54         unsigned int uninitialized_var(next_pi);
55         compat_uptr_t uentry, next_uentry, upending;
56         compat_long_t futex_offset;
57         int rc;
58
59         if (!futex_cmpxchg_enabled)
60                 return;
61
62         /*
63          * Fetch the list head (which was registered earlier, via
64          * sys_set_robust_list()):
65          */
66         if (fetch_robust_entry(&uentry, &entry, &head->list.next, &pi))
67                 return;
68         /*
69          * Fetch the relative futex offset:
70          */
71         if (get_user(futex_offset, &head->futex_offset))
72                 return;
73         /*
74          * Fetch any possibly pending lock-add first, and handle it
75          * if it exists:
76          */
77         if (fetch_robust_entry(&upending, &pending,
78                                &head->list_op_pending, &pip))
79                 return;
80
81         next_entry = NULL;      /* avoid warning with gcc */
82         while (entry != (struct robust_list __user *) &head->list) {
83                 /*
84                  * Fetch the next entry in the list before calling
85                  * handle_futex_death:
86                  */
87                 rc = fetch_robust_entry(&next_uentry, &next_entry,
88                         (compat_uptr_t __user *)&entry->next, &next_pi);
89                 /*
90                  * A pending lock might already be on the list, so
91                  * dont process it twice:
92                  */
93                 if (entry != pending) {
94                         void __user *uaddr = futex_uaddr(entry, futex_offset);
95
96                         if (handle_futex_death(uaddr, curr, pi))
97                                 return;
98                 }
99                 if (rc)
100                         return;
101                 uentry = next_uentry;
102                 entry = next_entry;
103                 pi = next_pi;
104                 /*
105                  * Avoid excessively long or circular lists:
106                  */
107                 if (!--limit)
108                         break;
109
110                 cond_resched();
111         }
112         if (pending) {
113                 void __user *uaddr = futex_uaddr(pending, futex_offset);
114
115                 handle_futex_death(uaddr, curr, pip);
116         }
117 }
118
119 asmlinkage long
120 compat_sys_set_robust_list(struct compat_robust_list_head __user *head,
121                            compat_size_t len)
122 {
123         if (!futex_cmpxchg_enabled)
124                 return -ENOSYS;
125
126         if (unlikely(len != sizeof(*head)))
127                 return -EINVAL;
128
129         current->compat_robust_list = head;
130
131         return 0;
132 }
133
134 asmlinkage long
135 compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr,
136                            compat_size_t __user *len_ptr)
137 {
138         struct compat_robust_list_head __user *head;
139         unsigned long ret;
140         struct task_struct *p;
141
142         if (!futex_cmpxchg_enabled)
143                 return -ENOSYS;
144
145         WARN_ONCE(1, "deprecated: get_robust_list will be deleted in 2013.\n");
146
147         rcu_read_lock();
148
149         ret = -ESRCH;
150         if (!pid)
151                 p = current;
152         else {
153                 p = find_task_by_vpid(pid);
154                 if (!p)
155                         goto err_unlock;
156         }
157
158         ret = -EPERM;
159         if (!ptrace_may_access(p, PTRACE_MODE_READ))
160                 goto err_unlock;
161
162         head = p->compat_robust_list;
163         rcu_read_unlock();
164
165         if (put_user(sizeof(*head), len_ptr))
166                 return -EFAULT;
167         return put_user(ptr_to_compat(head), head_ptr);
168
169 err_unlock:
170         rcu_read_unlock();
171
172         return ret;
173 }
174
175 asmlinkage long compat_sys_futex(u32 __user *uaddr, int op, u32 val,
176                 struct compat_timespec __user *utime, u32 __user *uaddr2,
177                 u32 val3)
178 {
179         struct timespec ts;
180         ktime_t t, *tp = NULL;
181         int val2 = 0;
182         int cmd = op & FUTEX_CMD_MASK;
183
184         if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI ||
185                       cmd == FUTEX_WAIT_BITSET ||
186                       cmd == FUTEX_WAIT_REQUEUE_PI)) {
187                 if (get_compat_timespec(&ts, utime))
188                         return -EFAULT;
189                 if (!timespec_valid(&ts))
190                         return -EINVAL;
191
192                 t = timespec_to_ktime(ts);
193                 if (cmd == FUTEX_WAIT)
194                         t = ktime_add_safe(ktime_get(), t);
195                 tp = &t;
196         }
197         if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE ||
198             cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP)
199                 val2 = (int) (unsigned long) utime;
200
201         return do_futex(uaddr, op, val, tp, uaddr2, val2, val3);
202 }