include/linux/futex.h

Source file repositories/reference/linux-study-clean/include/linux/futex.h

File Facts

System
Linux kernel
Corpus path
include/linux/futex.h
Extension
.h
Size
4945 bytes
Lines
163
Domain
Core OS
Bucket
Core Kernel Interface
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

static inline int futex_hash_allocate_default(void) { return 0; }
static inline int futex_hash_free(struct mm_struct *mm) { return 0; }
#endif /* !CONFIG_FUTEX_PRIVATE_HASH */

#else  /* CONFIG_FUTEX */
static inline void futex_init_task(struct task_struct *tsk) { }
static inline void futex_exit_recursive(struct task_struct *tsk) { }
static inline void futex_exit_release(struct task_struct *tsk) { }
static inline void futex_exec_release(struct task_struct *tsk) { }
static inline long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
			    u32 __user *uaddr2, u32 val2, u32 val3)
{
	return -EINVAL;
}
static inline int futex_hash_prctl(unsigned long arg2, unsigned long arg3, unsigned long arg4)
{
	return -EINVAL;
}
static inline int futex_hash_allocate_default(void) { return 0; }
static inline int futex_hash_free(struct mm_struct *mm) { return 0; }
#endif /* !CONFIG_FUTEX */

#ifdef CONFIG_FUTEX_ROBUST_UNLOCK
#include <asm/futex_robust.h>

void futex_reset_cs_ranges(struct futex_mm_data *fd);
void __futex_fixup_robust_unlock(struct pt_regs *regs, struct futex_unlock_cs_range *csr);

static inline bool futex_within_robust_unlock(struct pt_regs *regs,
					      struct futex_unlock_cs_range *csr)
{
	unsigned long ip = instruction_pointer(regs);

	return ip >= csr->start_ip && ip < csr->start_ip + csr->len;
}

static inline void futex_fixup_robust_unlock(struct pt_regs *regs)
{
	struct futex_unlock_cs_range *csr;

	/*
	 * Avoid dereferencing current->mm if not returning from interrupt.
	 * current->rseq.event is going to be used subsequently, so bringing the
	 * cache line in is not a big deal.
	 */
	if (!current->rseq.event.user_irq)
		return;

	csr = current->mm->futex.unlock.cs_ranges;

	/* The loop is optimized out for !COMPAT */
	for (int r = 0; r < FUTEX_ROBUST_MAX_CS_RANGES; r++, csr++) {
		if (unlikely(futex_within_robust_unlock(regs, csr))) {
			__futex_fixup_robust_unlock(regs, csr);
			return;
		}
	}
}

static inline void futex_set_vdso_cs_range(struct futex_mm_data *fd, unsigned int idx,
					   unsigned long start, unsigned long end, bool sz32)
{
	fd->unlock.cs_ranges[idx].start_ip = start;
	fd->unlock.cs_ranges[idx].len = end - start;
	fd->unlock.cs_ranges[idx].pop_size32 = sz32;
}
#else /* CONFIG_FUTEX_ROBUST_UNLOCK */
static inline void futex_fixup_robust_unlock(struct pt_regs *regs) { }
#endif /* !CONFIG_FUTEX_ROBUST_UNLOCK */


#if defined(CONFIG_FUTEX_PRIVATE_HASH) || defined(CONFIG_FUTEX_ROBUST_UNLOCK)
void futex_mm_init(struct mm_struct *mm);
#else
static inline void futex_mm_init(struct mm_struct *mm) { }
#endif

#endif /* _LINUX_FUTEX_H */

Annotation

Implementation Notes