projects/linux·blob v2.6.21 · refs

164 lines · 3.7 KiB

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/futex.h>
12
13#include <asm/uaccess.h>
14
15
16/*
17 * Fetch a robust-list pointer. Bit 0 signals PI futexes:
18 */
19static inline int
20fetch_robust_entry(compat_uptr_t *uentry, struct robust_list __user **entry,
21 compat_uptr_t __user *head, int *pi)
22{
23 if (get_user(*uentry, head))
24 return -EFAULT;
25
26 *entry = compat_ptr((*uentry) & ~1);
27 *pi = (unsigned int)(*uentry) & 1;
28
29 return 0;
30}
31
32/*
33 * Walk curr->robust_list (very carefully, it's a userspace list!)
34 * and mark any locks found there dead, and notify any waiters.
35 *
36 * We silently return on any sign of list-walking problem.
37 */
38void compat_exit_robust_list(struct task_struct *curr)
39{
40 struct compat_robust_list_head __user *head = curr->compat_robust_list;
41 struct robust_list __user *entry, *pending;
42 unsigned int limit = ROBUST_LIST_LIMIT, pi, pip;
43 compat_uptr_t uentry, upending;
44 compat_long_t futex_offset;
45
46 /*
47 * Fetch the list head (which was registered earlier, via
48 * sys_set_robust_list()):
49 */
50 if (fetch_robust_entry(&uentry, &entry, &head->list.next, &pi))
51 return;
52 /*
53 * Fetch the relative futex offset:
54 */
55 if (get_user(futex_offset, &head->futex_offset))
56 return;
57 /*
58 * Fetch any possibly pending lock-add first, and handle it
59 * if it exists:
60 */
61 if (fetch_robust_entry(&upending, &pending,
62 &head->list_op_pending, &pip))
63 return;
64 if (upending)
65 handle_futex_death((void __user *)pending + futex_offset, curr, pip);
66
67 while (compat_ptr(uentry) != &head->list) {
68 /*
69 * A pending lock might already be on the list, so
70 * dont process it twice:
71 */
72 if (entry != pending)
73 if (handle_futex_death((void __user *)entry + futex_offset,
74 curr, pi))
75 return;
76
77 /*
78 * Fetch the next entry in the list:
79 */
80 if (fetch_robust_entry(&uentry, &entry,
81 (compat_uptr_t __user *)&entry->next, &pi))
82 return;
83 /*
84 * Avoid excessively long or circular lists:
85 */
86 if (!--limit)
87 break;
88
89 cond_resched();
90 }
91}
92
93asmlinkage long
94compat_sys_set_robust_list(struct compat_robust_list_head __user *head,
95 compat_size_t len)
96{
97 if (unlikely(len != sizeof(*head)))
98 return -EINVAL;
99
100 current->compat_robust_list = head;
101
102 return 0;
103}
104
105asmlinkage long
106compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr,
107 compat_size_t __user *len_ptr)
108{
109 struct compat_robust_list_head __user *head;
110 unsigned long ret;
111
112 if (!pid)
113 head = current->compat_robust_list;
114 else {
115 struct task_struct *p;
116
117 ret = -ESRCH;
118 read_lock(&tasklist_lock);
119 p = find_task_by_pid(pid);
120 if (!p)
121 goto err_unlock;
122 ret = -EPERM;
123 if ((current->euid != p->euid) && (current->euid != p->uid) &&
124 !capable(CAP_SYS_PTRACE))
125 goto err_unlock;
126 head = p->compat_robust_list;
127 read_unlock(&tasklist_lock);
128 }
129
130 if (put_user(sizeof(*head), len_ptr))
131 return -EFAULT;
132 return put_user(ptr_to_compat(head), head_ptr);
133
134err_unlock:
135 read_unlock(&tasklist_lock);
136
137 return ret;
138}
139
140asmlinkage long compat_sys_futex(u32 __user *uaddr, int op, u32 val,
141 struct compat_timespec __user *utime, u32 __user *uaddr2,
142 u32 val3)
143{
144 struct timespec t;
145 unsigned long timeout = MAX_SCHEDULE_TIMEOUT;
146 int val2 = 0;
147
148 if (utime && (op == FUTEX_WAIT || op == FUTEX_LOCK_PI)) {
149 if (get_compat_timespec(&t, utime))
150 return -EFAULT;
151 if (!timespec_valid(&t))
152 return -EINVAL;
153 if (op == FUTEX_WAIT)
154 timeout = timespec_to_jiffies(&t) + 1;
155 else {
156 timeout = t.tv_sec;
157 val2 = t.tv_nsec;
158 }
159 }
160 if (op == FUTEX_REQUEUE || op == FUTEX_CMP_REQUEUE)
161 val2 = (int) (unsigned long) utime;
162
163 return do_futex(uaddr, op, val, timeout, uaddr2, val2, val3);
164}