2 * linux/kernel/futex_compat.c
4 * Futex compatibililty routines.
6 * Copyright 2006, Red Hat, Inc., Ingo Molnar
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 #include <linux/syscalls.h>
16 #include <asm/uaccess.h>
20 * Fetch a robust-list pointer. Bit 0 signals PI futexes:
23 fetch_robust_entry(compat_uptr_t *uentry, struct robust_list __user **entry,
24 compat_uptr_t __user *head, unsigned int *pi)
26 if (get_user(*uentry, head))
29 *entry = compat_ptr((*uentry) & ~1);
30 *pi = (unsigned int)(*uentry) & 1;
35 static void __user *futex_uaddr(struct robust_list __user *entry,
36 compat_long_t futex_offset)
38 compat_uptr_t base = ptr_to_compat(entry);
39 void __user *uaddr = compat_ptr(base + futex_offset);
45 * Walk curr->robust_list (very carefully, it's a userspace list!)
46 * and mark any locks found there dead, and notify any waiters.
48 * We silently return on any sign of list-walking problem.
50 void compat_exit_robust_list(struct task_struct *curr)
52 struct compat_robust_list_head __user *head = curr->compat_robust_list;
53 struct robust_list __user *entry, *next_entry, *pending;
54 unsigned int limit = ROBUST_LIST_LIMIT, pi, pip;
55 unsigned int uninitialized_var(next_pi);
56 compat_uptr_t uentry, next_uentry, upending;
57 compat_long_t futex_offset;
60 if (!futex_cmpxchg_enabled)
64 * Fetch the list head (which was registered earlier, via
65 * sys_set_robust_list()):
67 if (fetch_robust_entry(&uentry, &entry, &head->list.next, &pi))
70 * Fetch the relative futex offset:
72 if (get_user(futex_offset, &head->futex_offset))
75 * Fetch any possibly pending lock-add first, and handle it
78 if (fetch_robust_entry(&upending, &pending,
79 &head->list_op_pending, &pip))
82 next_entry = NULL; /* avoid warning with gcc */
83 while (entry != (struct robust_list __user *) &head->list) {
85 * Fetch the next entry in the list before calling
88 rc = fetch_robust_entry(&next_uentry, &next_entry,
89 (compat_uptr_t __user *)&entry->next, &next_pi);
91 * A pending lock might already be on the list, so
92 * dont process it twice:
94 if (entry != pending) {
95 void __user *uaddr = futex_uaddr(entry, futex_offset);
97 if (handle_futex_death(uaddr, curr, pi))
102 uentry = next_uentry;
106 * Avoid excessively long or circular lists:
114 void __user *uaddr = futex_uaddr(pending, futex_offset);
116 handle_futex_death(uaddr, curr, pip);
120 COMPAT_SYSCALL_DEFINE2(set_robust_list,
121 struct compat_robust_list_head __user *, head,
124 if (!futex_cmpxchg_enabled)
127 if (unlikely(len != sizeof(*head)))
130 current->compat_robust_list = head;
135 COMPAT_SYSCALL_DEFINE3(get_robust_list, int, pid,
136 compat_uptr_t __user *, head_ptr,
137 compat_size_t __user *, len_ptr)
139 struct compat_robust_list_head __user *head;
141 struct task_struct *p;
143 if (!futex_cmpxchg_enabled)
152 p = find_task_by_vpid(pid);
158 if (!ptrace_may_access(p, PTRACE_MODE_READ_REALCREDS))
161 head = p->compat_robust_list;
164 if (put_user(sizeof(*head), len_ptr))
166 return put_user(ptr_to_compat(head), head_ptr);
174 COMPAT_SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
175 struct compat_timespec __user *, utime, u32 __user *, uaddr2,
179 ktime_t t, *tp = NULL;
181 int cmd = op & FUTEX_CMD_MASK;
183 if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI ||
184 cmd == FUTEX_WAIT_BITSET ||
185 cmd == FUTEX_WAIT_REQUEUE_PI)) {
186 if (compat_get_timespec(&ts, utime))
188 if (!timespec_valid(&ts))
191 t = timespec_to_ktime(ts);
192 if (cmd == FUTEX_WAIT)
193 t = ktime_add_safe(ktime_get(), t);
196 if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE ||
197 cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP)
198 val2 = (int) (unsigned long) utime;
200 return do_futex(uaddr, op, val, tp, uaddr2, val2, val3);