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_ROBUST_UNLOCK 512 29 #define FUTEX_ROBUST_LIST32 1024 30 31 #define FUTEX_CMD_MASK ~(FUTEX_PRIVATE_FLAG | FUTEX_CLOCK_REALTIME | \ 32 FUTEX_ROBUST_UNLOCK | FUTEX_ROBUST_LIST32) 33 34 #define FUTEX_WAIT_PRIVATE (FUTEX_WAIT | FUTEX_PRIVATE_FLAG) 35 #define FUTEX_WAKE_PRIVATE (FUTEX_WAKE | FUTEX_PRIVATE_FLAG) 36 #define FUTEX_REQUEUE_PRIVATE (FUTEX_REQUEUE | FUTEX_PRIVATE_FLAG) 37 #define FUTEX_CMP_REQUEUE_PRIVATE (FUTEX_CMP_REQUEUE | FUTEX_PRIVATE_FLAG) 38 #define FUTEX_WAKE_OP_PRIVATE (FUTEX_WAKE_OP | FUTEX_PRIVATE_FLAG) 39 #define FUTEX_LOCK_PI_PRIVATE (FUTEX_LOCK_PI | FUTEX_PRIVATE_FLAG) 40 #define FUTEX_LOCK_PI2_PRIVATE (FUTEX_LOCK_PI2 | FUTEX_PRIVATE_FLAG) 41 #define FUTEX_UNLOCK_PI_PRIVATE (FUTEX_UNLOCK_PI | FUTEX_PRIVATE_FLAG) 42 #define FUTEX_TRYLOCK_PI_PRIVATE (FUTEX_TRYLOCK_PI | FUTEX_PRIVATE_FLAG) 43 #define FUTEX_WAIT_BITSET_PRIVATE (FUTEX_WAIT_BITSET | FUTEX_PRIVATE_FLAG) 44 #define FUTEX_WAKE_BITSET_PRIVATE (FUTEX_WAKE_BITSET | FUTEX_PRIVATE_FLAG) 45 #define FUTEX_WAIT_REQUEUE_PI_PRIVATE (FUTEX_WAIT_REQUEUE_PI | FUTEX_PRIVATE_FLAG) 46 #define FUTEX_CMP_REQUEUE_PI_PRIVATE (FUTEX_CMP_REQUEUE_PI | FUTEX_PRIVATE_FLAG) 47 48 /* 49 * Operations to unlock a futex, clear the robust list pending op pointer and 50 * wake waiters. 51 */ 52 #define FUTEX_UNLOCK_PI_LIST64 (FUTEX_UNLOCK_PI | FUTEX_ROBUST_UNLOCK) 53 #define FUTEX_UNLOCK_PI_LIST64_PRIVATE (FUTEX_UNLOCK_PI_LIST64 | FUTEX_PRIVATE_FLAG) 54 #define FUTEX_UNLOCK_PI_LIST32 (FUTEX_UNLOCK_PI | FUTEX_ROBUST_UNLOCK | \ 55 FUTEX_ROBUST_LIST32) 56 #define FUTEX_UNLOCK_PI_LIST32_PRIVATE (FUTEX_UNLOCK_PI_LIST32 | FUTEX_PRIVATE_FLAG) 57 58 #define FUTEX_UNLOCK_WAKE_LIST64 (FUTEX_WAKE | FUTEX_ROBUST_UNLOCK) 59 #define FUTEX_UNLOCK_WAKE_LIST64_PRIVATE (FUTEX_UNLOCK_WAKE_LIST64 | FUTEX_PRIVATE_FLAG) 60 61 #define FUTEX_UNLOCK_WAKE_LIST32 (FUTEX_WAKE | FUTEX_ROBUST_UNLOCK | \ 62 FUTEX_ROBUST_LIST32) 63 #define FUTEX_UNLOCK_WAKE_LIST32_PRIVATE (FUTEX_UNLOCK_WAKE_LIST32 | FUTEX_PRIVATE_FLAG) 64 65 #define FUTEX_UNLOCK_BITSET_LIST64 (FUTEX_WAKE_BITSET | FUTEX_ROBUST_UNLOCK) 66 #define FUTEX_UNLOCK_BITSET_LIST64_PRIVATE (FUTEX_UNLOCK_BITSET_LIST64 | FUTEX_PRIVATE_FLAG) 67 68 #define FUTEX_UNLOCK_BITSET_LIST32 (FUTEX_WAKE_BITSET | FUTEX_ROBUST_UNLOCK | \ 69 FUTEX_ROBUST_LIST32) 70 #define FUTEX_UNLOCK_BITSET_LIST32_PRIVATE (FUTEX_UNLOCK_BITSET_LIST32 | FUTEX_PRIVATE_FLAG) 71 72 /* 73 * Flags for futex2 syscalls. 74 * 75 * NOTE: these are not pure flags, they can also be seen as: 76 * 77 * union { 78 * u32 flags; 79 * struct { 80 * u32 size : 2, 81 * numa : 1, 82 * : 4, 83 * private : 1; 84 * }; 85 * }; 86 */ 87 #define FUTEX2_SIZE_U8 0x00 88 #define FUTEX2_SIZE_U16 0x01 89 #define FUTEX2_SIZE_U32 0x02 90 #define FUTEX2_SIZE_U64 0x03 91 #define FUTEX2_NUMA 0x04 92 #define FUTEX2_MPOL 0x08 93 /* 0x10 */ 94 /* 0x20 */ 95 /* 0x40 */ 96 #define FUTEX2_PRIVATE FUTEX_PRIVATE_FLAG 97 98 #define FUTEX2_SIZE_MASK 0x03 99 100 /* do not use */ 101 #define FUTEX_32 FUTEX2_SIZE_U32 /* historical accident :-( */ 102 103 /* 104 * When FUTEX2_NUMA doubles the futex word, the second word is a node value. 105 * The special value -1 indicates no-node. This is the same value as 106 * NUMA_NO_NODE, except that value is not ABI, this is. 107 */ 108 #define FUTEX_NO_NODE (-1) 109 110 /* 111 * Max numbers of elements in a futex_waitv array 112 */ 113 #define FUTEX_WAITV_MAX 128 114 115 /** 116 * struct futex_waitv - A waiter for vectorized wait 117 * @val: Expected value at uaddr 118 * @uaddr: User address to wait on 119 * @flags: Flags for this waiter 120 * @__reserved: Reserved member to preserve data alignment. Should be 0. 121 */ 122 struct futex_waitv { 123 __u64 val; 124 __u64 uaddr; 125 __u32 flags; 126 __u32 __reserved; 127 }; 128 129 /* 130 * Support for robust futexes: the kernel cleans up held futexes at 131 * thread exit time. 132 */ 133 134 /* 135 * Per-lock list entry - embedded in user-space locks, somewhere close 136 * to the futex field. (Note: user-space uses a double-linked list to 137 * achieve O(1) list add and remove, but the kernel only needs to know 138 * about the forward link) 139 * 140 * NOTE: this structure is part of the syscall ABI, and must not be 141 * changed. 142 */ 143 struct robust_list { 144 struct robust_list __user *next; 145 }; 146 147 /* 148 * Per-thread list head: 149 * 150 * NOTE: this structure is part of the syscall ABI, and must only be 151 * changed if the change is first communicated with the glibc folks. 152 * (When an incompatible change is done, we'll increase the structure 153 * size, which glibc will detect) 154 */ 155 struct robust_list_head { 156 /* 157 * The head of the list. Points back to itself if empty: 158 */ 159 struct robust_list list; 160 161 /* 162 * This relative offset is set by user-space, it gives the kernel 163 * the relative position of the futex field to examine. This way 164 * we keep userspace flexible, to freely shape its data-structure, 165 * without hardcoding any particular offset into the kernel: 166 */ 167 long futex_offset; 168 169 /* 170 * The death of the thread may race with userspace setting 171 * up a lock's links. So to handle this race, userspace first 172 * sets this field to the address of the to-be-taken lock, 173 * then does the lock acquire, and then adds itself to the 174 * list, and then clears this field. Hence the kernel will 175 * always have full knowledge of all locks that the thread 176 * _might_ have taken. We check the owner TID in any case, 177 * so only truly owned locks will be handled. 178 */ 179 struct robust_list __user *list_op_pending; 180 }; 181 182 /* 183 * Are there any waiters for this robust futex: 184 */ 185 #define FUTEX_WAITERS 0x80000000 186 187 /* 188 * The kernel signals via this bit that a thread holding a futex 189 * has exited without unlocking the futex. The kernel also does 190 * a FUTEX_WAKE on such futexes, after setting the bit, to wake 191 * up any possible waiters: 192 */ 193 #define FUTEX_OWNER_DIED 0x40000000 194 195 /* 196 * The rest of the robust-futex field is for the TID: 197 */ 198 #define FUTEX_TID_MASK 0x3fffffff 199 200 /* 201 * This limit protects against a deliberately circular list. 202 * (Not worth introducing an rlimit for it) 203 */ 204 #define ROBUST_LIST_LIMIT 2048 205 206 /* Modifiers for robust_list_head::list_op_pending */ 207 #define FUTEX_ROBUST_MOD_PI (0x1UL) 208 #define FUTEX_ROBUST_MOD_MASK (FUTEX_ROBUST_MOD_PI) 209 210 /* 211 * bitset with all bits set for the FUTEX_xxx_BITSET OPs to request a 212 * match of any bit. 213 */ 214 #define FUTEX_BITSET_MATCH_ANY 0xffffffff 215 216 217 #define FUTEX_OP_SET 0 /* *(int *)UADDR2 = OPARG; */ 218 #define FUTEX_OP_ADD 1 /* *(int *)UADDR2 += OPARG; */ 219 #define FUTEX_OP_OR 2 /* *(int *)UADDR2 |= OPARG; */ 220 #define FUTEX_OP_ANDN 3 /* *(int *)UADDR2 &= ~OPARG; */ 221 #define FUTEX_OP_XOR 4 /* *(int *)UADDR2 ^= OPARG; */ 222 223 #define FUTEX_OP_OPARG_SHIFT 8 /* Use (1 << OPARG) instead of OPARG. */ 224 225 #define FUTEX_OP_CMP_EQ 0 /* if (oldval == CMPARG) wake */ 226 #define FUTEX_OP_CMP_NE 1 /* if (oldval != CMPARG) wake */ 227 #define FUTEX_OP_CMP_LT 2 /* if (oldval < CMPARG) wake */ 228 #define FUTEX_OP_CMP_LE 3 /* if (oldval <= CMPARG) wake */ 229 #define FUTEX_OP_CMP_GT 4 /* if (oldval > CMPARG) wake */ 230 #define FUTEX_OP_CMP_GE 5 /* if (oldval >= CMPARG) wake */ 231 232 /* FUTEX_WAKE_OP will perform atomically 233 int oldval = *(int *)UADDR2; 234 *(int *)UADDR2 = oldval OP OPARG; 235 if (oldval CMP CMPARG) 236 wake UADDR2; */ 237 238 #define FUTEX_OP(op, oparg, cmp, cmparg) \ 239 (((op & 0xf) << 28) | ((cmp & 0xf) << 24) \ 240 | ((oparg & 0xfff) << 12) | (cmparg & 0xfff)) 241 242 #endif /* _UAPI_LINUX_FUTEX_H */ 243