1 #ifndef _LINUX_FUTEX_H 2 #define _LINUX_FUTEX_H 3 4 5 #include <linux/types.h> 6 7 /* Second argument to futex syscall */ 8 9 10 #define FUTEX_WAIT 0 11 #define FUTEX_WAKE 1 12 #define FUTEX_FD 2 13 #define FUTEX_REQUEUE 3 14 #define FUTEX_CMP_REQUEUE 4 15 #define FUTEX_WAKE_OP 5 16 #define FUTEX_LOCK_PI 6 17 #define FUTEX_UNLOCK_PI 7 18 #define FUTEX_TRYLOCK_PI 8 19 #define FUTEX_WAIT_BITSET 9 20 #define FUTEX_WAKE_BITSET 10 21 #define FUTEX_WAIT_REQUEUE_PI 11 22 #define FUTEX_CMP_REQUEUE_PI 12 23 24 #define FUTEX_PRIVATE_FLAG 128 25 #define FUTEX_CLOCK_REALTIME 256 26 #define FUTEX_CMD_MASK ~(FUTEX_PRIVATE_FLAG | FUTEX_CLOCK_REALTIME) 27 28 #define FUTEX_WAIT_PRIVATE (FUTEX_WAIT | FUTEX_PRIVATE_FLAG) 29 #define FUTEX_WAKE_PRIVATE (FUTEX_WAKE | FUTEX_PRIVATE_FLAG) 30 #define FUTEX_REQUEUE_PRIVATE (FUTEX_REQUEUE | FUTEX_PRIVATE_FLAG) 31 #define FUTEX_CMP_REQUEUE_PRIVATE (FUTEX_CMP_REQUEUE | FUTEX_PRIVATE_FLAG) 32 #define FUTEX_WAKE_OP_PRIVATE (FUTEX_WAKE_OP | FUTEX_PRIVATE_FLAG) 33 #define FUTEX_LOCK_PI_PRIVATE (FUTEX_LOCK_PI | FUTEX_PRIVATE_FLAG) 34 #define FUTEX_UNLOCK_PI_PRIVATE (FUTEX_UNLOCK_PI | FUTEX_PRIVATE_FLAG) 35 #define FUTEX_TRYLOCK_PI_PRIVATE (FUTEX_TRYLOCK_PI | FUTEX_PRIVATE_FLAG) 36 #define FUTEX_WAIT_BITSET_PRIVATE (FUTEX_WAIT_BITSET | FUTEX_PRIVATE_FLAG) 37 #define FUTEX_WAKE_BITSET_PRIVATE (FUTEX_WAKE_BITSET | FUTEX_PRIVATE_FLAG) 38 #define FUTEX_WAIT_REQUEUE_PI_PRIVATE (FUTEX_WAIT_REQUEUE_PI | \ 39 FUTEX_PRIVATE_FLAG) 40 #define FUTEX_CMP_REQUEUE_PI_PRIVATE (FUTEX_CMP_REQUEUE_PI | \ 41 FUTEX_PRIVATE_FLAG) 42 43 /* 44 * Support for robust futexes: the kernel cleans up held futexes at 45 * thread exit time. 46 */ 47 48 /* 49 * Per-lock list entry - embedded in user-space locks, somewhere close 50 * to the futex field. (Note: user-space uses a double-linked list to 51 * achieve O(1) list add and remove, but the kernel only needs to know 52 * about the forward link) 53 * 54 * NOTE: this structure is part of the syscall ABI, and must not be 55 * changed. 56 */ 57 struct robust_list { 58 struct robust_list *next; 59 }; 60 61 /* 62 * Per-thread list head: 63 * 64 * NOTE: this structure is part of the syscall ABI, and must only be 65 * changed if the change is first communicated with the glibc folks. 66 * (When an incompatible change is done, we'll increase the structure 67 * size, which glibc will detect) 68 */ 69 struct robust_list_head { 70 /* 71 * The head of the list. Points back to itself if empty: 72 */ 73 struct robust_list list; 74 75 /* 76 * This relative offset is set by user-space, it gives the kernel 77 * the relative position of the futex field to examine. This way 78 * we keep userspace flexible, to freely shape its data-structure, 79 * without hardcoding any particular offset into the kernel: 80 */ 81 long futex_offset; 82 83 /* 84 * The death of the thread may race with userspace setting 85 * up a lock's links. So to handle this race, userspace first 86 * sets this field to the address of the to-be-taken lock, 87 * then does the lock acquire, and then adds itself to the 88 * list, and then clears this field. Hence the kernel will 89 * always have full knowledge of all locks that the thread 90 * _might_ have taken. We check the owner TID in any case, 91 * so only truly owned locks will be handled. 92 */ 93 struct robust_list *list_op_pending; 94 }; 95 96 /* 97 * Are there any waiters for this robust futex: 98 */ 99 #define FUTEX_WAITERS 0x80000000 100 101 /* 102 * The kernel signals via this bit that a thread holding a futex 103 * has exited without unlocking the futex. The kernel also does 104 * a FUTEX_WAKE on such futexes, after setting the bit, to wake 105 * up any possible waiters: 106 */ 107 #define FUTEX_OWNER_DIED 0x40000000 108 109 /* 110 * The rest of the robust-futex field is for the TID: 111 */ 112 #define FUTEX_TID_MASK 0x3fffffff 113 114 /* 115 * This limit protects against a deliberately circular list. 116 * (Not worth introducing an rlimit for it) 117 */ 118 #define ROBUST_LIST_LIMIT 2048 119 120 /* 121 * bitset with all bits set for the FUTEX_xxx_BITSET OPs to request a 122 * match of any bit. 123 */ 124 #define FUTEX_BITSET_MATCH_ANY 0xffffffff 125 126 127 #define FUTEX_OP_SET 0 /* *(int *)UADDR2 = OPARG; */ 128 #define FUTEX_OP_ADD 1 /* *(int *)UADDR2 += OPARG; */ 129 #define FUTEX_OP_OR 2 /* *(int *)UADDR2 |= OPARG; */ 130 #define FUTEX_OP_ANDN 3 /* *(int *)UADDR2 &= ~OPARG; */ 131 #define FUTEX_OP_XOR 4 /* *(int *)UADDR2 ^= OPARG; */ 132 133 #define FUTEX_OP_OPARG_SHIFT 8 /* Use (1 << OPARG) instead of OPARG. */ 134 135 #define FUTEX_OP_CMP_EQ 0 /* if (oldval == CMPARG) wake */ 136 #define FUTEX_OP_CMP_NE 1 /* if (oldval != CMPARG) wake */ 137 #define FUTEX_OP_CMP_LT 2 /* if (oldval < CMPARG) wake */ 138 #define FUTEX_OP_CMP_LE 3 /* if (oldval <= CMPARG) wake */ 139 #define FUTEX_OP_CMP_GT 4 /* if (oldval > CMPARG) wake */ 140 #define FUTEX_OP_CMP_GE 5 /* if (oldval >= CMPARG) wake */ 141 142 /* FUTEX_WAKE_OP will perform atomically 143 int oldval = *(int *)UADDR2; 144 *(int *)UADDR2 = oldval OP OPARG; 145 if (oldval CMP CMPARG) 146 wake UADDR2; */ 147 148 #define FUTEX_OP(op, oparg, cmp, cmparg) \ 149 (((op & 0xf) << 28) | ((cmp & 0xf) << 24) \ 150 | ((oparg & 0xfff) << 12) | (cmparg & 0xfff)) 151 152 #endif 153
