1 #ifndef _LINUX_FUTEX_H 2 #define _LINUX_FUTEX_H 3 4 #include <linux/compiler.h> 5 #include <linux/types.h> 6 7 struct inode; 8 struct mm_struct; 9 struct task_struct; 10 union ktime; 11 12 /* Second argument to futex syscall */ 13 14 15 #define FUTEX_WAIT 0 16 #define FUTEX_WAKE 1 17 #define FUTEX_FD 2 18 #define FUTEX_REQUEUE 3 19 #define FUTEX_CMP_REQUEUE 4 20 #define FUTEX_WAKE_OP 5 21 #define FUTEX_LOCK_PI 6 22 #define FUTEX_UNLOCK_PI 7 23 #define FUTEX_TRYLOCK_PI 8 24 #define FUTEX_WAIT_BITSET 9 25 #define FUTEX_WAKE_BITSET 10 26 #define FUTEX_WAIT_REQUEUE_PI 11 27 #define FUTEX_CMP_REQUEUE_PI 12 28 29 #define FUTEX_PRIVATE_FLAG 128 30 #define FUTEX_CLOCK_REALTIME 256 31 #define FUTEX_CMD_MASK ~(FUTEX_PRIVATE_FLAG | FUTEX_CLOCK_REALTIME) 32 33 #define FUTEX_WAIT_PRIVATE (FUTEX_WAIT | FUTEX_PRIVATE_FLAG) 34 #define FUTEX_WAKE_PRIVATE (FUTEX_WAKE | FUTEX_PRIVATE_FLAG) 35 #define FUTEX_REQUEUE_PRIVATE (FUTEX_REQUEUE | FUTEX_PRIVATE_FLAG) 36 #define FUTEX_CMP_REQUEUE_PRIVATE (FUTEX_CMP_REQUEUE | FUTEX_PRIVATE_FLAG) 37 #define FUTEX_WAKE_OP_PRIVATE (FUTEX_WAKE_OP | FUTEX_PRIVATE_FLAG) 38 #define FUTEX_LOCK_PI_PRIVATE (FUTEX_LOCK_PI | FUTEX_PRIVATE_FLAG) 39 #define FUTEX_UNLOCK_PI_PRIVATE (FUTEX_UNLOCK_PI | FUTEX_PRIVATE_FLAG) 40 #define FUTEX_TRYLOCK_PI_PRIVATE (FUTEX_TRYLOCK_PI | FUTEX_PRIVATE_FLAG) 41 #define FUTEX_WAIT_BITSET_PRIVATE (FUTEX_WAIT_BITS | FUTEX_PRIVATE_FLAG) 42 #define FUTEX_WAKE_BITSET_PRIVATE (FUTEX_WAKE_BITS | FUTEX_PRIVATE_FLAG) 43 #define FUTEX_WAIT_REQUEUE_PI_PRIVATE (FUTEX_WAIT_REQUEUE_PI | \ 44 FUTEX_PRIVATE_FLAG) 45 #define FUTEX_CMP_REQUEUE_PI_PRIVATE (FUTEX_CMP_REQUEUE_PI | \ 46 FUTEX_PRIVATE_FLAG) 47 48 /* 49 * Support for robust futexes: the kernel cleans up held futexes at 50 * thread exit time. 51 */ 52 53 /* 54 * Per-lock list entry - embedded in user-space locks, somewhere close 55 * to the futex field. (Note: user-space uses a double-linked list to 56 * achieve O(1) list add and remove, but the kernel only needs to know 57 * about the forward link) 58 * 59 * NOTE: this structure is part of the syscall ABI, and must not be 60 * changed. 61 */ 62 struct robust_list { 63 struct robust_list __user *next; 64 }; 65 66 /* 67 * Per-thread list head: 68 * 69 * NOTE: this structure is part of the syscall ABI, and must only be 70 * changed if the change is first communicated with the glibc folks. 71 * (When an incompatible change is done, we'll increase the structure 72 * size, which glibc will detect) 73 */ 74 struct robust_list_head { 75 /* 76 * The head of the list. Points back to itself if empty: 77 */ 78 struct robust_list list; 79 80 /* 81 * This relative offset is set by user-space, it gives the kernel 82 * the relative position of the futex field to examine. This way 83 * we keep userspace flexible, to freely shape its data-structure, 84 * without hardcoding any particular offset into the kernel: 85 */ 86 long futex_offset; 87 88 /* 89 * The death of the thread may race with userspace setting 90 * up a lock's links. So to handle this race, userspace first 91 * sets this field to the address of the to-be-taken lock, 92 * then does the lock acquire, and then adds itself to the 93 * list, and then clears this field. Hence the kernel will 94 * always have full knowledge of all locks that the thread 95 * _might_ have taken. We check the owner TID in any case, 96 * so only truly owned locks will be handled. 97 */ 98 struct robust_list __user *list_op_pending; 99 }; 100 101 /* 102 * Are there any waiters for this robust futex: 103 */ 104 #define FUTEX_WAITERS 0x80000000 105 106 /* 107 * The kernel signals via this bit that a thread holding a futex 108 * has exited without unlocking the futex. The kernel also does 109 * a FUTEX_WAKE on such futexes, after setting the bit, to wake 110 * up any possible waiters: 111 */ 112 #define FUTEX_OWNER_DIED 0x40000000 113 114 /* 115 * The rest of the robust-futex field is for the TID: 116 */ 117 #define FUTEX_TID_MASK 0x3fffffff 118 119 /* 120 * This limit protects against a deliberately circular list. 121 * (Not worth introducing an rlimit for it) 122 */ 123 #define ROBUST_LIST_LIMIT 2048 124 125 /* 126 * bitset with all bits set for the FUTEX_xxx_BITSET OPs to request a 127 * match of any bit. 128 */ 129 #define FUTEX_BITSET_MATCH_ANY 0xffffffff 130 131 #ifdef __KERNEL__ 132 long do_futex(u32 __user *uaddr, int op, u32 val, union ktime *timeout, 133 u32 __user *uaddr2, u32 val2, u32 val3); 134 135 extern int 136 handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi); 137 138 /* 139 * Futexes are matched on equal values of this key. 140 * The key type depends on whether it's a shared or private mapping. 141 * Don't rearrange members without looking at hash_futex(). 142 * 143 * offset is aligned to a multiple of sizeof(u32) (== 4) by definition. 144 * We use the two low order bits of offset to tell what is the kind of key : 145 * 00 : Private process futex (PTHREAD_PROCESS_PRIVATE) 146 * (no reference on an inode or mm) 147 * 01 : Shared futex (PTHREAD_PROCESS_SHARED) 148 * mapped on a file (reference on the underlying inode) 149 * 10 : Shared futex (PTHREAD_PROCESS_SHARED) 150 * (but private mapping on an mm, and reference taken on it) 151 */ 152 153 #define FUT_OFF_INODE 1 /* We set bit 0 if key has a reference on inode */ 154 #define FUT_OFF_MMSHARED 2 /* We set bit 1 if key has a reference on mm */ 155 156 union futex_key { 157 struct { 158 unsigned long pgoff; 159 struct inode *inode; 160 int offset; 161 } shared; 162 struct { 163 unsigned long address; 164 struct mm_struct *mm; 165 int offset; 166 } private; 167 struct { 168 unsigned long word; 169 void *ptr; 170 int offset; 171 } both; 172 }; 173 174 #define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = NULL } } 175 176 #ifdef CONFIG_FUTEX 177 extern void exit_robust_list(struct task_struct *curr); 178 extern void exit_pi_state_list(struct task_struct *curr); 179 extern int futex_cmpxchg_enabled; 180 #else 181 static inline void exit_robust_list(struct task_struct *curr) 182 { 183 } 184 static inline void exit_pi_state_list(struct task_struct *curr) 185 { 186 } 187 #endif 188 #endif /* __KERNEL__ */ 189 190 #define FUTEX_OP_SET 0 /* *(int *)UADDR2 = OPARG; */ 191 #define FUTEX_OP_ADD 1 /* *(int *)UADDR2 += OPARG; */ 192 #define FUTEX_OP_OR 2 /* *(int *)UADDR2 |= OPARG; */ 193 #define FUTEX_OP_ANDN 3 /* *(int *)UADDR2 &= ~OPARG; */ 194 #define FUTEX_OP_XOR 4 /* *(int *)UADDR2 ^= OPARG; */ 195 196 #define FUTEX_OP_OPARG_SHIFT 8 /* Use (1 << OPARG) instead of OPARG. */ 197 198 #define FUTEX_OP_CMP_EQ 0 /* if (oldval == CMPARG) wake */ 199 #define FUTEX_OP_CMP_NE 1 /* if (oldval != CMPARG) wake */ 200 #define FUTEX_OP_CMP_LT 2 /* if (oldval < CMPARG) wake */ 201 #define FUTEX_OP_CMP_LE 3 /* if (oldval <= CMPARG) wake */ 202 #define FUTEX_OP_CMP_GT 4 /* if (oldval > CMPARG) wake */ 203 #define FUTEX_OP_CMP_GE 5 /* if (oldval >= CMPARG) wake */ 204 205 /* FUTEX_WAKE_OP will perform atomically 206 int oldval = *(int *)UADDR2; 207 *(int *)UADDR2 = oldval OP OPARG; 208 if (oldval CMP CMPARG) 209 wake UADDR2; */ 210 211 #define FUTEX_OP(op, oparg, cmp, cmparg) \ 212 (((op & 0xf) << 28) | ((cmp & 0xf) << 24) \ 213 | ((oparg & 0xfff) << 12) | (cmparg & 0xfff)) 214 215 #endif 216