1 #ifndef _LINUX_FUTEX_H 2 #define _LINUX_FUTEX_H 3 4 #include <linux/sched.h> 5 6 union ktime; 7 8 /* Second argument to futex syscall */ 9 10 11 #define FUTEX_WAIT 0 12 #define FUTEX_WAKE 1 13 #define FUTEX_FD 2 14 #define FUTEX_REQUEUE 3 15 #define FUTEX_CMP_REQUEUE 4 16 #define FUTEX_WAKE_OP 5 17 #define FUTEX_LOCK_PI 6 18 #define FUTEX_UNLOCK_PI 7 19 #define FUTEX_TRYLOCK_PI 8 20 21 #define FUTEX_PRIVATE_FLAG 128 22 #define FUTEX_CMD_MASK ~FUTEX_PRIVATE_FLAG 23 24 #define FUTEX_WAIT_PRIVATE (FUTEX_WAIT | FUTEX_PRIVATE_FLAG) 25 #define FUTEX_WAKE_PRIVATE (FUTEX_WAKE | FUTEX_PRIVATE_FLAG) 26 #define FUTEX_REQUEUE_PRIVATE (FUTEX_REQUEUE | FUTEX_PRIVATE_FLAG) 27 #define FUTEX_CMP_REQUEUE_PRIVATE (FUTEX_CMP_REQUEUE | FUTEX_PRIVATE_FLAG) 28 #define FUTEX_WAKE_OP_PRIVATE (FUTEX_WAKE_OP | FUTEX_PRIVATE_FLAG) 29 #define FUTEX_LOCK_PI_PRIVATE (FUTEX_LOCK_PI | FUTEX_PRIVATE_FLAG) 30 #define FUTEX_UNLOCK_PI_PRIVATE (FUTEX_UNLOCK_PI | FUTEX_PRIVATE_FLAG) 31 #define FUTEX_TRYLOCK_PI_PRIVATE (FUTEX_TRYLOCK_PI | FUTEX_PRIVATE_FLAG) 32 33 /* 34 * Support for robust futexes: the kernel cleans up held futexes at 35 * thread exit time. 36 */ 37 38 /* 39 * Per-lock list entry - embedded in user-space locks, somewhere close 40 * to the futex field. (Note: user-space uses a double-linked list to 41 * achieve O(1) list add and remove, but the kernel only needs to know 42 * about the forward link) 43 * 44 * NOTE: this structure is part of the syscall ABI, and must not be 45 * changed. 46 */ 47 struct robust_list { 48 struct robust_list __user *next; 49 }; 50 51 /* 52 * Per-thread list head: 53 * 54 * NOTE: this structure is part of the syscall ABI, and must only be 55 * changed if the change is first communicated with the glibc folks. 56 * (When an incompatible change is done, we'll increase the structure 57 * size, which glibc will detect) 58 */ 59 struct robust_list_head { 60 /* 61 * The head of the list. Points back to itself if empty: 62 */ 63 struct robust_list list; 64 65 /* 66 * This relative offset is set by user-space, it gives the kernel 67 * the relative position of the futex field to examine. This way 68 * we keep userspace flexible, to freely shape its data-structure, 69 * without hardcoding any particular offset into the kernel: 70 */ 71 long futex_offset; 72 73 /* 74 * The death of the thread may race with userspace setting 75 * up a lock's links. So to handle this race, userspace first 76 * sets this field to the address of the to-be-taken lock, 77 * then does the lock acquire, and then adds itself to the 78 * list, and then clears this field. Hence the kernel will 79 * always have full knowledge of all locks that the thread 80 * _might_ have taken. We check the owner TID in any case, 81 * so only truly owned locks will be handled. 82 */ 83 struct robust_list __user *list_op_pending; 84 }; 85 86 /* 87 * Are there any waiters for this robust futex: 88 */ 89 #define FUTEX_WAITERS 0x80000000 90 91 /* 92 * The kernel signals via this bit that a thread holding a futex 93 * has exited without unlocking the futex. The kernel also does 94 * a FUTEX_WAKE on such futexes, after setting the bit, to wake 95 * up any possible waiters: 96 */ 97 #define FUTEX_OWNER_DIED 0x40000000 98 99 /* 100 * The rest of the robust-futex field is for the TID: 101 */ 102 #define FUTEX_TID_MASK 0x3fffffff 103 104 /* 105 * This limit protects against a deliberately circular list. 106 * (Not worth introducing an rlimit for it) 107 */ 108 #define ROBUST_LIST_LIMIT 2048 109 110 #ifdef __KERNEL__ 111 long do_futex(u32 __user *uaddr, int op, u32 val, union ktime *timeout, 112 u32 __user *uaddr2, u32 val2, u32 val3); 113 114 extern int 115 handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi); 116 117 /* 118 * Futexes are matched on equal values of this key. 119 * The key type depends on whether it's a shared or private mapping. 120 * Don't rearrange members without looking at hash_futex(). 121 * 122 * offset is aligned to a multiple of sizeof(u32) (== 4) by definition. 123 * We use the two low order bits of offset to tell what is the kind of key : 124 * 00 : Private process futex (PTHREAD_PROCESS_PRIVATE) 125 * (no reference on an inode or mm) 126 * 01 : Shared futex (PTHREAD_PROCESS_SHARED) 127 * mapped on a file (reference on the underlying inode) 128 * 10 : Shared futex (PTHREAD_PROCESS_SHARED) 129 * (but private mapping on an mm, and reference taken on it) 130 */ 131 132 #define FUT_OFF_INODE 1 /* We set bit 0 if key has a reference on inode */ 133 #define FUT_OFF_MMSHARED 2 /* We set bit 1 if key has a reference on mm */ 134 135 union futex_key { 136 struct { 137 unsigned long pgoff; 138 struct inode *inode; 139 int offset; 140 } shared; 141 struct { 142 unsigned long address; 143 struct mm_struct *mm; 144 int offset; 145 } private; 146 struct { 147 unsigned long word; 148 void *ptr; 149 int offset; 150 } both; 151 }; 152 153 #ifdef CONFIG_FUTEX 154 extern void exit_robust_list(struct task_struct *curr); 155 extern void exit_pi_state_list(struct task_struct *curr); 156 #else 157 static inline void exit_robust_list(struct task_struct *curr) 158 { 159 } 160 static inline void exit_pi_state_list(struct task_struct *curr) 161 { 162 } 163 #endif 164 #endif /* __KERNEL__ */ 165 166 #define FUTEX_OP_SET 0 /* *(int *)UADDR2 = OPARG; */ 167 #define FUTEX_OP_ADD 1 /* *(int *)UADDR2 += OPARG; */ 168 #define FUTEX_OP_OR 2 /* *(int *)UADDR2 |= OPARG; */ 169 #define FUTEX_OP_ANDN 3 /* *(int *)UADDR2 &= ~OPARG; */ 170 #define FUTEX_OP_XOR 4 /* *(int *)UADDR2 ^= OPARG; */ 171 172 #define FUTEX_OP_OPARG_SHIFT 8 /* Use (1 << OPARG) instead of OPARG. */ 173 174 #define FUTEX_OP_CMP_EQ 0 /* if (oldval == CMPARG) wake */ 175 #define FUTEX_OP_CMP_NE 1 /* if (oldval != CMPARG) wake */ 176 #define FUTEX_OP_CMP_LT 2 /* if (oldval < CMPARG) wake */ 177 #define FUTEX_OP_CMP_LE 3 /* if (oldval <= CMPARG) wake */ 178 #define FUTEX_OP_CMP_GT 4 /* if (oldval > CMPARG) wake */ 179 #define FUTEX_OP_CMP_GE 5 /* if (oldval >= CMPARG) wake */ 180 181 /* FUTEX_WAKE_OP will perform atomically 182 int oldval = *(int *)UADDR2; 183 *(int *)UADDR2 = oldval OP OPARG; 184 if (oldval CMP CMPARG) 185 wake UADDR2; */ 186 187 #define FUTEX_OP(op, oparg, cmp, cmparg) \ 188 (((op & 0xf) << 28) | ((cmp & 0xf) << 24) \ 189 | ((oparg & 0xfff) << 12) | (cmparg & 0xfff)) 190 191 #endif 192