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>
14 #include <asm/uaccess.h>
18 * Fetch a robust-list pointer. Bit 0 signals PI futexes:
21 fetch_robust_entry(compat_uptr_t
*uentry
, struct robust_list __user
**entry
,
22 compat_uptr_t __user
*head
, int *pi
)
24 if (get_user(*uentry
, head
))
27 *entry
= compat_ptr((*uentry
) & ~1);
28 *pi
= (unsigned int)(*uentry
) & 1;
33 static void __user
*futex_uaddr(struct robust_list __user
*entry
,
34 compat_long_t futex_offset
)
36 compat_uptr_t base
= ptr_to_compat(entry
);
37 void __user
*uaddr
= compat_ptr(base
+ futex_offset
);
43 * Walk curr->robust_list (very carefully, it's a userspace list!)
44 * and mark any locks found there dead, and notify any waiters.
46 * We silently return on any sign of list-walking problem.
48 void compat_exit_robust_list(struct task_struct
*curr
)
50 struct compat_robust_list_head __user
*head
= curr
->compat_robust_list
;
51 struct robust_list __user
*entry
, *next_entry
, *pending
;
52 unsigned int limit
= ROBUST_LIST_LIMIT
, pi
, next_pi
, pip
;
53 compat_uptr_t uentry
, next_uentry
, upending
;
54 compat_long_t futex_offset
;
57 if (!futex_cmpxchg_enabled
)
61 * Fetch the list head (which was registered earlier, via
62 * sys_set_robust_list()):
64 if (fetch_robust_entry(&uentry
, &entry
, &head
->list
.next
, &pi
))
67 * Fetch the relative futex offset:
69 if (get_user(futex_offset
, &head
->futex_offset
))
72 * Fetch any possibly pending lock-add first, and handle it
75 if (fetch_robust_entry(&upending
, &pending
,
76 &head
->list_op_pending
, &pip
))
79 next_entry
= NULL
; /* avoid warning with gcc */
80 while (entry
!= (struct robust_list __user
*) &head
->list
) {
82 * Fetch the next entry in the list before calling
85 rc
= fetch_robust_entry(&next_uentry
, &next_entry
,
86 (compat_uptr_t __user
*)&entry
->next
, &next_pi
);
88 * A pending lock might already be on the list, so
89 * dont process it twice:
91 if (entry
!= pending
) {
92 void __user
*uaddr
= futex_uaddr(entry
, futex_offset
);
94 if (handle_futex_death(uaddr
, curr
, pi
))
103 * Avoid excessively long or circular lists:
111 void __user
*uaddr
= futex_uaddr(pending
, futex_offset
);
113 handle_futex_death(uaddr
, curr
, pip
);
118 compat_sys_set_robust_list(struct compat_robust_list_head __user
*head
,
121 if (!futex_cmpxchg_enabled
)
124 if (unlikely(len
!= sizeof(*head
)))
127 current
->compat_robust_list
= head
;
133 compat_sys_get_robust_list(int pid
, compat_uptr_t __user
*head_ptr
,
134 compat_size_t __user
*len_ptr
)
136 struct compat_robust_list_head __user
*head
;
139 if (!futex_cmpxchg_enabled
)
143 head
= current
->compat_robust_list
;
145 struct task_struct
*p
;
148 read_lock(&tasklist_lock
);
149 p
= find_task_by_vpid(pid
);
153 if ((current
->euid
!= p
->euid
) && (current
->euid
!= p
->uid
) &&
154 !capable(CAP_SYS_PTRACE
))
156 head
= p
->compat_robust_list
;
157 read_unlock(&tasklist_lock
);
160 if (put_user(sizeof(*head
), len_ptr
))
162 return put_user(ptr_to_compat(head
), head_ptr
);
165 read_unlock(&tasklist_lock
);
170 asmlinkage
long compat_sys_futex(u32 __user
*uaddr
, int op
, u32 val
,
171 struct compat_timespec __user
*utime
, u32 __user
*uaddr2
,
175 ktime_t t
, *tp
= NULL
;
177 int cmd
= op
& FUTEX_CMD_MASK
;
179 if (utime
&& (cmd
== FUTEX_WAIT
|| cmd
== FUTEX_LOCK_PI
||
180 cmd
== FUTEX_WAIT_BITSET
)) {
181 if (get_compat_timespec(&ts
, utime
))
183 if (!timespec_valid(&ts
))
186 t
= timespec_to_ktime(ts
);
187 if (cmd
== FUTEX_WAIT
)
188 t
= ktime_add_safe(ktime_get(), t
);
191 if (cmd
== FUTEX_REQUEUE
|| cmd
== FUTEX_CMP_REQUEUE
)
192 val2
= (int) (unsigned long) utime
;
194 return do_futex(uaddr
, op
, val
, tp
, uaddr2
, val2
, val3
);