diff options
Diffstat (limited to 'include/linux/futex.h')
| -rw-r--r-- | include/linux/futex.h | 215 |
1 files changed, 215 insertions, 0 deletions
diff --git a/include/linux/futex.h b/include/linux/futex.h new file mode 100644 index 00000000..1e5a26d7 --- /dev/null +++ b/include/linux/futex.h @@ -0,0 +1,215 @@ +#ifndef _LINUX_FUTEX_H +#define _LINUX_FUTEX_H + +#include <linux/compiler.h> +#include <linux/types.h> + +/* Second argument to futex syscall */ + + +#define FUTEX_WAIT 0 +#define FUTEX_WAKE 1 +#define FUTEX_FD 2 +#define FUTEX_REQUEUE 3 +#define FUTEX_CMP_REQUEUE 4 +#define FUTEX_WAKE_OP 5 +#define FUTEX_LOCK_PI 6 +#define FUTEX_UNLOCK_PI 7 +#define FUTEX_TRYLOCK_PI 8 +#define FUTEX_WAIT_BITSET 9 +#define FUTEX_WAKE_BITSET 10 +#define FUTEX_WAIT_REQUEUE_PI 11 +#define FUTEX_CMP_REQUEUE_PI 12 + +#define FUTEX_PRIVATE_FLAG 128 +#define FUTEX_CLOCK_REALTIME 256 +#define FUTEX_CMD_MASK ~(FUTEX_PRIVATE_FLAG | FUTEX_CLOCK_REALTIME) + +#define FUTEX_WAIT_PRIVATE (FUTEX_WAIT | FUTEX_PRIVATE_FLAG) +#define FUTEX_WAKE_PRIVATE (FUTEX_WAKE | FUTEX_PRIVATE_FLAG) +#define FUTEX_REQUEUE_PRIVATE (FUTEX_REQUEUE | FUTEX_PRIVATE_FLAG) +#define FUTEX_CMP_REQUEUE_PRIVATE (FUTEX_CMP_REQUEUE | FUTEX_PRIVATE_FLAG) +#define FUTEX_WAKE_OP_PRIVATE (FUTEX_WAKE_OP | FUTEX_PRIVATE_FLAG) +#define FUTEX_LOCK_PI_PRIVATE (FUTEX_LOCK_PI | FUTEX_PRIVATE_FLAG) +#define FUTEX_UNLOCK_PI_PRIVATE (FUTEX_UNLOCK_PI | FUTEX_PRIVATE_FLAG) +#define FUTEX_TRYLOCK_PI_PRIVATE (FUTEX_TRYLOCK_PI | FUTEX_PRIVATE_FLAG) +#define FUTEX_WAIT_BITSET_PRIVATE (FUTEX_WAIT_BITSET | FUTEX_PRIVATE_FLAG) +#define FUTEX_WAKE_BITSET_PRIVATE (FUTEX_WAKE_BITSET | FUTEX_PRIVATE_FLAG) +#define FUTEX_WAIT_REQUEUE_PI_PRIVATE (FUTEX_WAIT_REQUEUE_PI | \ + FUTEX_PRIVATE_FLAG) +#define FUTEX_CMP_REQUEUE_PI_PRIVATE (FUTEX_CMP_REQUEUE_PI | \ + FUTEX_PRIVATE_FLAG) + +/* + * Support for robust futexes: the kernel cleans up held futexes at + * thread exit time. + */ + +/* + * Per-lock list entry - embedded in user-space locks, somewhere close + * to the futex field. (Note: user-space uses a double-linked list to + * achieve O(1) list add and remove, but the kernel only needs to know + * about the forward link) + * + * NOTE: this structure is part of the syscall ABI, and must not be + * changed. + */ +struct robust_list { + struct robust_list __user *next; +}; + +/* + * Per-thread list head: + * + * NOTE: this structure is part of the syscall ABI, and must only be + * changed if the change is first communicated with the glibc folks. + * (When an incompatible change is done, we'll increase the structure + * size, which glibc will detect) + */ +struct robust_list_head { + /* + * The head of the list. Points back to itself if empty: + */ + struct robust_list list; + + /* + * This relative offset is set by user-space, it gives the kernel + * the relative position of the futex field to examine. This way + * we keep userspace flexible, to freely shape its data-structure, + * without hardcoding any particular offset into the kernel: + */ + long futex_offset; + + /* + * The death of the thread may race with userspace setting + * up a lock's links. So to handle this race, userspace first + * sets this field to the address of the to-be-taken lock, + * then does the lock acquire, and then adds itself to the + * list, and then clears this field. Hence the kernel will + * always have full knowledge of all locks that the thread + * _might_ have taken. We check the owner TID in any case, + * so only truly owned locks will be handled. + */ + struct robust_list __user *list_op_pending; +}; + +/* + * Are there any waiters for this robust futex: + */ +#define FUTEX_WAITERS 0x80000000 + +/* + * The kernel signals via this bit that a thread holding a futex + * has exited without unlocking the futex. The kernel also does + * a FUTEX_WAKE on such futexes, after setting the bit, to wake + * up any possible waiters: + */ +#define FUTEX_OWNER_DIED 0x40000000 + +/* + * The rest of the robust-futex field is for the TID: + */ +#define FUTEX_TID_MASK 0x3fffffff + +/* + * This limit protects against a deliberately circular list. + * (Not worth introducing an rlimit for it) + */ +#define ROBUST_LIST_LIMIT 2048 + +/* + * bitset with all bits set for the FUTEX_xxx_BITSET OPs to request a + * match of any bit. + */ +#define FUTEX_BITSET_MATCH_ANY 0xffffffff + +#ifdef __KERNEL__ +struct inode; +struct mm_struct; +struct task_struct; +union ktime; + +long do_futex(u32 __user *uaddr, int op, u32 val, union ktime *timeout, + u32 __user *uaddr2, u32 val2, u32 val3); + +extern int +handle_futex_death(u32 __user *uaddr, struct task_struct *curr, int pi); + +/* + * Futexes are matched on equal values of this key. + * The key type depends on whether it's a shared or private mapping. + * Don't rearrange members without looking at hash_futex(). + * + * offset is aligned to a multiple of sizeof(u32) (== 4) by definition. + * We use the two low order bits of offset to tell what is the kind of key : + * 00 : Private process futex (PTHREAD_PROCESS_PRIVATE) + * (no reference on an inode or mm) + * 01 : Shared futex (PTHREAD_PROCESS_SHARED) + * mapped on a file (reference on the underlying inode) + * 10 : Shared futex (PTHREAD_PROCESS_SHARED) + * (but private mapping on an mm, and reference taken on it) +*/ + +#define FUT_OFF_INODE 1 /* We set bit 0 if key has a reference on inode */ +#define FUT_OFF_MMSHARED 2 /* We set bit 1 if key has a reference on mm */ + +union futex_key { + struct { + unsigned long pgoff; + struct inode *inode; + int offset; + } shared; + struct { + unsigned long address; + struct mm_struct *mm; + int offset; + } private; + struct { + unsigned long word; + void *ptr; + int offset; + } both; +}; + +#define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = NULL } } + +#ifdef CONFIG_FUTEX +extern void exit_robust_list(struct task_struct *curr); +extern void exit_pi_state_list(struct task_struct *curr); +extern int futex_cmpxchg_enabled; +#else +static inline void exit_robust_list(struct task_struct *curr) +{ +} +static inline void exit_pi_state_list(struct task_struct *curr) +{ +} +#endif +#endif /* __KERNEL__ */ + +#define FUTEX_OP_SET 0 /* *(int *)UADDR2 = OPARG; */ +#define FUTEX_OP_ADD 1 /* *(int *)UADDR2 += OPARG; */ +#define FUTEX_OP_OR 2 /* *(int *)UADDR2 |= OPARG; */ +#define FUTEX_OP_ANDN 3 /* *(int *)UADDR2 &= ~OPARG; */ +#define FUTEX_OP_XOR 4 /* *(int *)UADDR2 ^= OPARG; */ + +#define FUTEX_OP_OPARG_SHIFT 8 /* Use (1 << OPARG) instead of OPARG. */ + +#define FUTEX_OP_CMP_EQ 0 /* if (oldval == CMPARG) wake */ +#define FUTEX_OP_CMP_NE 1 /* if (oldval != CMPARG) wake */ +#define FUTEX_OP_CMP_LT 2 /* if (oldval < CMPARG) wake */ +#define FUTEX_OP_CMP_LE 3 /* if (oldval <= CMPARG) wake */ +#define FUTEX_OP_CMP_GT 4 /* if (oldval > CMPARG) wake */ +#define FUTEX_OP_CMP_GE 5 /* if (oldval >= CMPARG) wake */ + +/* FUTEX_WAKE_OP will perform atomically + int oldval = *(int *)UADDR2; + *(int *)UADDR2 = oldval OP OPARG; + if (oldval CMP CMPARG) + wake UADDR2; */ + +#define FUTEX_OP(op, oparg, cmp, cmparg) \ + (((op & 0xf) << 28) | ((cmp & 0xf) << 24) \ + | ((oparg & 0xfff) << 12) | (cmparg & 0xfff)) + +#endif |