cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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rtmutex_common.h (6338B)

      1/* SPDX-License-Identifier: GPL-2.0 */
      2/*
      3 * RT Mutexes: blocking mutual exclusion locks with PI support
      4 *
      5 * started by Ingo Molnar and Thomas Gleixner:
      6 *
      7 *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
      8 *  Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
      9 *
     10 * This file contains the private data structure and API definitions.
     11 */
     12
     13#ifndef __KERNEL_RTMUTEX_COMMON_H
     14#define __KERNEL_RTMUTEX_COMMON_H
     15
     16#include <linux/debug_locks.h>
     17#include <linux/rtmutex.h>
     18#include <linux/sched/wake_q.h>
     19
     20/*
     21 * This is the control structure for tasks blocked on a rt_mutex,
     22 * which is allocated on the kernel stack on of the blocked task.
     23 *
     24 * @tree_entry:		pi node to enqueue into the mutex waiters tree
     25 * @pi_tree_entry:	pi node to enqueue into the mutex owner waiters tree
     26 * @task:		task reference to the blocked task
     27 * @lock:		Pointer to the rt_mutex on which the waiter blocks
     28 * @wake_state:		Wakeup state to use (TASK_NORMAL or TASK_RTLOCK_WAIT)
     29 * @prio:		Priority of the waiter
     30 * @deadline:		Deadline of the waiter if applicable
     31 * @ww_ctx:		WW context pointer
     32 */
     33struct rt_mutex_waiter {
     34	struct rb_node		tree_entry;
     35	struct rb_node		pi_tree_entry;
     36	struct task_struct	*task;
     37	struct rt_mutex_base	*lock;
     38	unsigned int		wake_state;
     39	int			prio;
     40	u64			deadline;
     41	struct ww_acquire_ctx	*ww_ctx;
     42};
     43
     44/**
     45 * rt_wake_q_head - Wrapper around regular wake_q_head to support
     46 *		    "sleeping" spinlocks on RT
     47 * @head:		The regular wake_q_head for sleeping lock variants
     48 * @rtlock_task:	Task pointer for RT lock (spin/rwlock) wakeups
     49 */
     50struct rt_wake_q_head {
     51	struct wake_q_head	head;
     52	struct task_struct	*rtlock_task;
     53};
     54
     55#define DEFINE_RT_WAKE_Q(name)						\
     56	struct rt_wake_q_head name = {					\
     57		.head		= WAKE_Q_HEAD_INITIALIZER(name.head),	\
     58		.rtlock_task	= NULL,					\
     59	}
     60
     61/*
     62 * PI-futex support (proxy locking functions, etc.):
     63 */
     64extern void rt_mutex_init_proxy_locked(struct rt_mutex_base *lock,
     65				       struct task_struct *proxy_owner);
     66extern void rt_mutex_proxy_unlock(struct rt_mutex_base *lock);
     67extern int __rt_mutex_start_proxy_lock(struct rt_mutex_base *lock,
     68				     struct rt_mutex_waiter *waiter,
     69				     struct task_struct *task);
     70extern int rt_mutex_start_proxy_lock(struct rt_mutex_base *lock,
     71				     struct rt_mutex_waiter *waiter,
     72				     struct task_struct *task);
     73extern int rt_mutex_wait_proxy_lock(struct rt_mutex_base *lock,
     74			       struct hrtimer_sleeper *to,
     75			       struct rt_mutex_waiter *waiter);
     76extern bool rt_mutex_cleanup_proxy_lock(struct rt_mutex_base *lock,
     77				 struct rt_mutex_waiter *waiter);
     78
     79extern int rt_mutex_futex_trylock(struct rt_mutex_base *l);
     80extern int __rt_mutex_futex_trylock(struct rt_mutex_base *l);
     81
     82extern void rt_mutex_futex_unlock(struct rt_mutex_base *lock);
     83extern bool __rt_mutex_futex_unlock(struct rt_mutex_base *lock,
     84				struct rt_wake_q_head *wqh);
     85
     86extern void rt_mutex_postunlock(struct rt_wake_q_head *wqh);
     87
     88/*
     89 * Must be guarded because this header is included from rcu/tree_plugin.h
     90 * unconditionally.
     91 */
     92#ifdef CONFIG_RT_MUTEXES
     93static inline int rt_mutex_has_waiters(struct rt_mutex_base *lock)
     94{
     95	return !RB_EMPTY_ROOT(&lock->waiters.rb_root);
     96}
     97
     98/*
     99 * Lockless speculative check whether @waiter is still the top waiter on
    100 * @lock. This is solely comparing pointers and not derefencing the
    101 * leftmost entry which might be about to vanish.
    102 */
    103static inline bool rt_mutex_waiter_is_top_waiter(struct rt_mutex_base *lock,
    104						 struct rt_mutex_waiter *waiter)
    105{
    106	struct rb_node *leftmost = rb_first_cached(&lock->waiters);
    107
    108	return rb_entry(leftmost, struct rt_mutex_waiter, tree_entry) == waiter;
    109}
    110
    111static inline struct rt_mutex_waiter *rt_mutex_top_waiter(struct rt_mutex_base *lock)
    112{
    113	struct rb_node *leftmost = rb_first_cached(&lock->waiters);
    114	struct rt_mutex_waiter *w = NULL;
    115
    116	if (leftmost) {
    117		w = rb_entry(leftmost, struct rt_mutex_waiter, tree_entry);
    118		BUG_ON(w->lock != lock);
    119	}
    120	return w;
    121}
    122
    123static inline int task_has_pi_waiters(struct task_struct *p)
    124{
    125	return !RB_EMPTY_ROOT(&p->pi_waiters.rb_root);
    126}
    127
    128static inline struct rt_mutex_waiter *task_top_pi_waiter(struct task_struct *p)
    129{
    130	return rb_entry(p->pi_waiters.rb_leftmost, struct rt_mutex_waiter,
    131			pi_tree_entry);
    132}
    133
    134#define RT_MUTEX_HAS_WAITERS	1UL
    135
    136static inline struct task_struct *rt_mutex_owner(struct rt_mutex_base *lock)
    137{
    138	unsigned long owner = (unsigned long) READ_ONCE(lock->owner);
    139
    140	return (struct task_struct *) (owner & ~RT_MUTEX_HAS_WAITERS);
    141}
    142
    143/*
    144 * Constants for rt mutex functions which have a selectable deadlock
    145 * detection.
    146 *
    147 * RT_MUTEX_MIN_CHAINWALK:	Stops the lock chain walk when there are
    148 *				no further PI adjustments to be made.
    149 *
    150 * RT_MUTEX_FULL_CHAINWALK:	Invoke deadlock detection with a full
    151 *				walk of the lock chain.
    152 */
    153enum rtmutex_chainwalk {
    154	RT_MUTEX_MIN_CHAINWALK,
    155	RT_MUTEX_FULL_CHAINWALK,
    156};
    157
    158static inline void __rt_mutex_base_init(struct rt_mutex_base *lock)
    159{
    160	raw_spin_lock_init(&lock->wait_lock);
    161	lock->waiters = RB_ROOT_CACHED;
    162	lock->owner = NULL;
    163}
    164
    165/* Debug functions */
    166static inline void debug_rt_mutex_unlock(struct rt_mutex_base *lock)
    167{
    168	if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES))
    169		DEBUG_LOCKS_WARN_ON(rt_mutex_owner(lock) != current);
    170}
    171
    172static inline void debug_rt_mutex_proxy_unlock(struct rt_mutex_base *lock)
    173{
    174	if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES))
    175		DEBUG_LOCKS_WARN_ON(!rt_mutex_owner(lock));
    176}
    177
    178static inline void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
    179{
    180	if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES))
    181		memset(waiter, 0x11, sizeof(*waiter));
    182}
    183
    184static inline void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
    185{
    186	if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES))
    187		memset(waiter, 0x22, sizeof(*waiter));
    188}
    189
    190static inline void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
    191{
    192	debug_rt_mutex_init_waiter(waiter);
    193	RB_CLEAR_NODE(&waiter->pi_tree_entry);
    194	RB_CLEAR_NODE(&waiter->tree_entry);
    195	waiter->wake_state = TASK_NORMAL;
    196	waiter->task = NULL;
    197}
    198
    199static inline void rt_mutex_init_rtlock_waiter(struct rt_mutex_waiter *waiter)
    200{
    201	rt_mutex_init_waiter(waiter);
    202	waiter->wake_state = TASK_RTLOCK_WAIT;
    203}
    204
    205#else /* CONFIG_RT_MUTEXES */
    206/* Used in rcu/tree_plugin.h */
    207static inline struct task_struct *rt_mutex_owner(struct rt_mutex_base *lock)
    208{
    209	return NULL;
    210}
    211#endif  /* !CONFIG_RT_MUTEXES */
    212
    213#endif