v2.6.22.24-op1
[linux-2.6.22.y-op.git] / kernel / futex_compat.c
blob589b1e427b78de3e04ccfa75c2682f16e8458904
1 /*
2 * linux/kernel/futex_compat.c
4 * Futex compatibililty routines.
6 * Copyright 2006, Red Hat, Inc., Ingo Molnar
7 */
9 #include <linux/linkage.h>
10 #include <linux/compat.h>
11 #include <linux/futex.h>
13 #include <asm/uaccess.h>
17 * Fetch a robust-list pointer. Bit 0 signals PI futexes:
19 static inline int
20 fetch_robust_entry(compat_uptr_t *uentry, struct robust_list __user **entry,
21 compat_uptr_t __user *head, int *pi)
23 if (get_user(*uentry, head))
24 return -EFAULT;
26 *entry = compat_ptr((*uentry) & ~1);
27 *pi = (unsigned int)(*uentry) & 1;
29 return 0;
32 static void __user *futex_uaddr(struct robust_list *entry,
33 compat_long_t futex_offset)
35 compat_uptr_t base = ptr_to_compat(entry);
36 void __user *uaddr = compat_ptr(base + futex_offset);
38 return uaddr;
42 * Walk curr->robust_list (very carefully, it's a userspace list!)
43 * and mark any locks found there dead, and notify any waiters.
45 * We silently return on any sign of list-walking problem.
47 void compat_exit_robust_list(struct task_struct *curr)
49 struct compat_robust_list_head __user *head = curr->compat_robust_list;
50 struct robust_list __user *entry, *pending;
51 unsigned int limit = ROBUST_LIST_LIMIT, pi, pip;
52 compat_uptr_t uentry, upending;
53 compat_long_t futex_offset;
56 * Fetch the list head (which was registered earlier, via
57 * sys_set_robust_list()):
59 if (fetch_robust_entry(&uentry, &entry, &head->list.next, &pi))
60 return;
62 * Fetch the relative futex offset:
64 if (get_user(futex_offset, &head->futex_offset))
65 return;
67 * Fetch any possibly pending lock-add first, and handle it
68 * if it exists:
70 if (fetch_robust_entry(&upending, &pending,
71 &head->list_op_pending, &pip))
72 return;
73 if (pending) {
74 void __user *uaddr = futex_uaddr(pending,
75 futex_offset);
76 handle_futex_death(uaddr, curr, pip);
79 while (entry != (struct robust_list __user *) &head->list) {
81 * A pending lock might already be on the list, so
82 * dont process it twice:
84 if (entry != pending) {
85 void __user *uaddr = futex_uaddr(entry,
86 futex_offset);
87 if (handle_futex_death(uaddr, curr, pi))
88 return;
92 * Fetch the next entry in the list:
94 if (fetch_robust_entry(&uentry, &entry,
95 (compat_uptr_t __user *)&entry->next, &pi))
96 return;
98 * Avoid excessively long or circular lists:
100 if (!--limit)
101 break;
103 cond_resched();
107 asmlinkage long
108 compat_sys_set_robust_list(struct compat_robust_list_head __user *head,
109 compat_size_t len)
111 if (unlikely(len != sizeof(*head)))
112 return -EINVAL;
114 current->compat_robust_list = head;
116 return 0;
119 asmlinkage long
120 compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr,
121 compat_size_t __user *len_ptr)
123 struct compat_robust_list_head __user *head;
124 unsigned long ret;
126 if (!pid)
127 head = current->compat_robust_list;
128 else {
129 struct task_struct *p;
131 ret = -ESRCH;
132 read_lock(&tasklist_lock);
133 p = find_task_by_pid(pid);
134 if (!p)
135 goto err_unlock;
136 ret = -EPERM;
137 if ((current->euid != p->euid) && (current->euid != p->uid) &&
138 !capable(CAP_SYS_PTRACE))
139 goto err_unlock;
140 head = p->compat_robust_list;
141 read_unlock(&tasklist_lock);
144 if (put_user(sizeof(*head), len_ptr))
145 return -EFAULT;
146 return put_user(ptr_to_compat(head), head_ptr);
148 err_unlock:
149 read_unlock(&tasklist_lock);
151 return ret;
154 asmlinkage long compat_sys_futex(u32 __user *uaddr, int op, u32 val,
155 struct compat_timespec __user *utime, u32 __user *uaddr2,
156 u32 val3)
158 struct timespec ts;
159 ktime_t t, *tp = NULL;
160 int val2 = 0;
161 int cmd = op & FUTEX_CMD_MASK;
163 if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI)) {
164 if (get_compat_timespec(&ts, utime))
165 return -EFAULT;
166 if (!timespec_valid(&ts))
167 return -EINVAL;
169 t = timespec_to_ktime(ts);
170 if (cmd == FUTEX_WAIT)
171 t = ktime_add(ktime_get(), t);
172 tp = &t;
174 if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE)
175 val2 = (int) (unsigned long) utime;
177 return do_futex(uaddr, op, val, tp, uaddr2, val2, val3);