1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ 2 #ifndef _UAPI_LINUX_FUTEX_H 3 #define _UAPI_LINUX_FUTEX_H 4 5 #include <linux/compiler.h> 6 #include <linux/types.h> 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 #define FUTEX_WAIT_BITSET 9 21 #define FUTEX_WAKE_BITSET 10 22 #define FUTEX_WAIT_REQUEUE_PI 11 23 #define FUTEX_CMP_REQUEUE_PI 12 24 #define FUTEX_LOCK_PI2 13 25 26 #define FUTEX_PRIVATE_FLAG 128 27 #define FUTEX_CLOCK_REALTIME 256 28 #define FUTEX_CMD_MASK ~(FUTEX_PRIVATE_FLAG | FUTEX_CLOCK_REALTIME) 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_LOCK_PI2_PRIVATE (FUTEX_LOCK_PI2 | FUTEX_PRIVATE_FLAG) 37 #define FUTEX_UNLOCK_PI_PRIVATE (FUTEX_UNLOCK_PI | FUTEX_PRIVATE_FLAG) 38 #define FUTEX_TRYLOCK_PI_PRIVATE (FUTEX_TRYLOCK_PI | FUTEX_PRIVATE_FLAG) 39 #define FUTEX_WAIT_BITSET_PRIVATE (FUTEX_WAIT_BITSET | FUTEX_PRIVATE_FLAG) 40 #define FUTEX_WAKE_BITSET_PRIVATE (FUTEX_WAKE_BITSET | FUTEX_PRIVATE_FLAG) 41 #define FUTEX_WAIT_REQUEUE_PI_PRIVATE (FUTEX_WAIT_REQUEUE_PI | \ 42 FUTEX_PRIVATE_FLAG) 43 #define FUTEX_CMP_REQUEUE_PI_PRIVATE (FUTEX_CMP_REQUEUE_PI | \ 44 FUTEX_PRIVATE_FLAG) 45 46 /* 47 * Flags for futex2 syscalls. 48 * 49 * NOTE: these are not pure flags, they can also be seen as: 50 * 51 * union { 52 * u32 flags; 53 * struct { 54 * u32 size : 2, 55 * numa : 1, 56 * : 4, 57 * private : 1; 58 * }; 59 * }; 60 */ 61 #define FUTEX2_SIZE_U8 0x00 62 #define FUTEX2_SIZE_U16 0x01 63 #define FUTEX2_SIZE_U32 0x02 64 #define FUTEX2_SIZE_U64 0x03 65 #define FUTEX2_NUMA 0x04 66 #define FUTEX2_MPOL 0x08 67 /* 0x10 */ 68 /* 0x20 */ 69 /* 0x40 */ 70 #define FUTEX2_PRIVATE FUTEX_PRIVATE_FLAG 71 72 #define FUTEX2_SIZE_MASK 0x03 73 74 /* do not use */ 75 #define FUTEX_32 FUTEX2_SIZE_U32 /* historical accident :-( */ 76 77 /* 78 * When FUTEX2_NUMA doubles the futex word, the second word is a node value. 79 * The special value -1 indicates no-node. This is the same value as 80 * NUMA_NO_NODE, except that value is not ABI, this is. 81 */ 82 #define FUTEX_NO_NODE (-1) 83 84 /* 85 * Max numbers of elements in a futex_waitv array 86 */ 87 #define FUTEX_WAITV_MAX 128 88 89 /** 90 * struct futex_waitv - A waiter for vectorized wait 91 * @val: Expected value at uaddr 92 * @uaddr: User address to wait on 93 * @flags: Flags for this waiter 94 * @__reserved: Reserved member to preserve data alignment. Should be 0. 95 */ 96 struct futex_waitv { 97 __u64 val; 98 __u64 uaddr; 99 __u32 flags; 100 __u32 __reserved; 101 }; 102 103 /* 104 * Support for robust futexes: the kernel cleans up held futexes at 105 * thread exit time. 106 */ 107 108 /* 109 * Per-lock list entry - embedded in user-space locks, somewhere close 110 * to the futex field. (Note: user-space uses a double-linked list to 111 * achieve O(1) list add and remove, but the kernel only needs to know 112 * about the forward link) 113 * 114 * NOTE: this structure is part of the syscall ABI, and must not be 115 * changed. 116 */ 117 struct robust_list { 118 struct robust_list __user *next; 119 }; 120 121 /* 122 * Per-thread list head: 123 * 124 * NOTE: this structure is part of the syscall ABI, and must only be 125 * changed if the change is first communicated with the glibc folks. 126 * (When an incompatible change is done, we'll increase the structure 127 * size, which glibc will detect) 128 */ 129 struct robust_list_head { 130 /* 131 * The head of the list. Points back to itself if empty: 132 */ 133 struct robust_list list; 134 135 /* 136 * This relative offset is set by user-space, it gives the kernel 137 * the relative position of the futex field to examine. This way 138 * we keep userspace flexible, to freely shape its data-structure, 139 * without hardcoding any particular offset into the kernel: 140 */ 141 long futex_offset; 142 143 /* 144 * The death of the thread may race with userspace setting 145 * up a lock's links. So to handle this race, userspace first 146 * sets this field to the address of the to-be-taken lock, 147 * then does the lock acquire, and then adds itself to the 148 * list, and then clears this field. Hence the kernel will 149 * always have full knowledge of all locks that the thread 150 * _might_ have taken. We check the owner TID in any case, 151 * so only truly owned locks will be handled. 152 */ 153 struct robust_list __user *list_op_pending; 154 }; 155 156 /* 157 * Are there any waiters for this robust futex: 158 */ 159 #define FUTEX_WAITERS 0x80000000 160 161 /* 162 * The kernel signals via this bit that a thread holding a futex 163 * has exited without unlocking the futex. The kernel also does 164 * a FUTEX_WAKE on such futexes, after setting the bit, to wake 165 * up any possible waiters: 166 */ 167 #define FUTEX_OWNER_DIED 0x40000000 168 169 /* 170 * The rest of the robust-futex field is for the TID: 171 */ 172 #define FUTEX_TID_MASK 0x3fffffff 173 174 /* 175 * This limit protects against a deliberately circular list. 176 * (Not worth introducing an rlimit for it) 177 */ 178 #define ROBUST_LIST_LIMIT 2048 179 180 /* 181 * bitset with all bits set for the FUTEX_xxx_BITSET OPs to request a 182 * match of any bit. 183 */ 184 #define FUTEX_BITSET_MATCH_ANY 0xffffffff 185 186 187 #define FUTEX_OP_SET 0 /* *(int *)UADDR2 = OPARG; */ 188 #define FUTEX_OP_ADD 1 /* *(int *)UADDR2 += OPARG; */ 189 #define FUTEX_OP_OR 2 /* *(int *)UADDR2 |= OPARG; */ 190 #define FUTEX_OP_ANDN 3 /* *(int *)UADDR2 &= ~OPARG; */ 191 #define FUTEX_OP_XOR 4 /* *(int *)UADDR2 ^= OPARG; */ 192 193 #define FUTEX_OP_OPARG_SHIFT 8 /* Use (1 << OPARG) instead of OPARG. */ 194 195 #define FUTEX_OP_CMP_EQ 0 /* if (oldval == CMPARG) wake */ 196 #define FUTEX_OP_CMP_NE 1 /* if (oldval != CMPARG) wake */ 197 #define FUTEX_OP_CMP_LT 2 /* if (oldval < CMPARG) wake */ 198 #define FUTEX_OP_CMP_LE 3 /* if (oldval <= CMPARG) wake */ 199 #define FUTEX_OP_CMP_GT 4 /* if (oldval > CMPARG) wake */ 200 #define FUTEX_OP_CMP_GE 5 /* if (oldval >= CMPARG) wake */ 201 202 /* FUTEX_WAKE_OP will perform atomically 203 int oldval = *(int *)UADDR2; 204 *(int *)UADDR2 = oldval OP OPARG; 205 if (oldval CMP CMPARG) 206 wake UADDR2; */ 207 208 #define FUTEX_OP(op, oparg, cmp, cmparg) \ 209 (((op & 0xf) << 28) | ((cmp & 0xf) << 24) \ 210 | ((oparg & 0xfff) << 12) | (cmparg & 0xfff)) 211 212 #endif /* _UAPI_LINUX_FUTEX_H */ 213