4 #include <linux/sched.h>
6 /* Second argument to futex syscall */
12 #define FUTEX_REQUEUE 3
13 #define FUTEX_CMP_REQUEUE 4
14 #define FUTEX_WAKE_OP 5
15 #define FUTEX_LOCK_PI 6
16 #define FUTEX_UNLOCK_PI 7
17 #define FUTEX_TRYLOCK_PI 8
20 * Support for robust futexes: the kernel cleans up held futexes at
25 * Per-lock list entry - embedded in user-space locks, somewhere close
26 * to the futex field. (Note: user-space uses a double-linked list to
27 * achieve O(1) list add and remove, but the kernel only needs to know
28 * about the forward link)
30 * NOTE: this structure is part of the syscall ABI, and must not be
34 struct robust_list __user
*next
;
38 * Per-thread list head:
40 * NOTE: this structure is part of the syscall ABI, and must only be
41 * changed if the change is first communicated with the glibc folks.
42 * (When an incompatible change is done, we'll increase the structure
43 * size, which glibc will detect)
45 struct robust_list_head
{
47 * The head of the list. Points back to itself if empty:
49 struct robust_list list
;
52 * This relative offset is set by user-space, it gives the kernel
53 * the relative position of the futex field to examine. This way
54 * we keep userspace flexible, to freely shape its data-structure,
55 * without hardcoding any particular offset into the kernel:
60 * The death of the thread may race with userspace setting
61 * up a lock's links. So to handle this race, userspace first
62 * sets this field to the address of the to-be-taken lock,
63 * then does the lock acquire, and then adds itself to the
64 * list, and then clears this field. Hence the kernel will
65 * always have full knowledge of all locks that the thread
66 * _might_ have taken. We check the owner TID in any case,
67 * so only truly owned locks will be handled.
69 struct robust_list __user
*list_op_pending
;
73 * Are there any waiters for this robust futex:
75 #define FUTEX_WAITERS 0x80000000
78 * The kernel signals via this bit that a thread holding a futex
79 * has exited without unlocking the futex. The kernel also does
80 * a FUTEX_WAKE on such futexes, after setting the bit, to wake
81 * up any possible waiters:
83 #define FUTEX_OWNER_DIED 0x40000000
86 * The rest of the robust-futex field is for the TID:
88 #define FUTEX_TID_MASK 0x3fffffff
91 * This limit protects against a deliberately circular list.
92 * (Not worth introducing an rlimit for it)
94 #define ROBUST_LIST_LIMIT 2048
96 long do_futex(u32 __user
*uaddr
, int op
, u32 val
, unsigned long timeout
,
97 u32 __user
*uaddr2
, u32 val2
, u32 val3
);
100 handle_futex_death(u32 __user
*uaddr
, struct task_struct
*curr
, int pi
);
103 extern void exit_robust_list(struct task_struct
*curr
);
104 extern void exit_pi_state_list(struct task_struct
*curr
);
106 static inline void exit_robust_list(struct task_struct
*curr
)
109 static inline void exit_pi_state_list(struct task_struct
*curr
)
114 #define FUTEX_OP_SET 0 /* *(int *)UADDR2 = OPARG; */
115 #define FUTEX_OP_ADD 1 /* *(int *)UADDR2 += OPARG; */
116 #define FUTEX_OP_OR 2 /* *(int *)UADDR2 |= OPARG; */
117 #define FUTEX_OP_ANDN 3 /* *(int *)UADDR2 &= ~OPARG; */
118 #define FUTEX_OP_XOR 4 /* *(int *)UADDR2 ^= OPARG; */
120 #define FUTEX_OP_OPARG_SHIFT 8 /* Use (1 << OPARG) instead of OPARG. */
122 #define FUTEX_OP_CMP_EQ 0 /* if (oldval == CMPARG) wake */
123 #define FUTEX_OP_CMP_NE 1 /* if (oldval != CMPARG) wake */
124 #define FUTEX_OP_CMP_LT 2 /* if (oldval < CMPARG) wake */
125 #define FUTEX_OP_CMP_LE 3 /* if (oldval <= CMPARG) wake */
126 #define FUTEX_OP_CMP_GT 4 /* if (oldval > CMPARG) wake */
127 #define FUTEX_OP_CMP_GE 5 /* if (oldval >= CMPARG) wake */
129 /* FUTEX_WAKE_OP will perform atomically
130 int oldval = *(int *)UADDR2;
131 *(int *)UADDR2 = oldval OP OPARG;
132 if (oldval CMP CMPARG)
135 #define FUTEX_OP(op, oparg, cmp, cmparg) \
136 (((op & 0xf) << 28) | ((cmp & 0xf) << 24) \
137 | ((oparg & 0xfff) << 12) | (cmparg & 0xfff))
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