1#ifndef _LINUX_FUTEX_H 2#define _LINUX_FUTEX_H 3 4#include <linux/compiler.h> 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 */ 57struct robust_list { 58 struct robust_list __user *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 */ 69struct 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 __user *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#ifdef __KERNEL__ 127struct inode; 128struct mm_struct; 129struct task_struct; 130union ktime; 131 132long do_futex(u32 __user *uaddr, int op, u32 val, union ktime *timeout, 133 u32 __user *uaddr2, u32 val2, u32 val3); 134 135extern int 136handle_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 156union 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 177extern void exit_robust_list(struct task_struct *curr); 178extern void exit_pi_state_list(struct task_struct *curr); 179extern int futex_cmpxchg_enabled; 180#else 181static inline void exit_robust_list(struct task_struct *curr) 182{ 183} 184static 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