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