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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rcupdate_trace.h (3165B)

      1/* SPDX-License-Identifier: GPL-2.0+ */
      2/*
      3 * Read-Copy Update mechanism for mutual exclusion, adapted for tracing.
      4 *
      5 * Copyright (C) 2020 Paul E. McKenney.
      6 */
      7
      8#ifndef __LINUX_RCUPDATE_TRACE_H
      9#define __LINUX_RCUPDATE_TRACE_H
     10
     11#include <linux/sched.h>
     12#include <linux/rcupdate.h>
     13
     14extern struct lockdep_map rcu_trace_lock_map;
     15
     16#ifdef CONFIG_DEBUG_LOCK_ALLOC
     17
     18static inline int rcu_read_lock_trace_held(void)
     19{
     20	return lock_is_held(&rcu_trace_lock_map);
     21}
     22
     23#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
     24
     25static inline int rcu_read_lock_trace_held(void)
     26{
     27	return 1;
     28}
     29
     30#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
     31
     32#ifdef CONFIG_TASKS_TRACE_RCU
     33
     34void rcu_read_unlock_trace_special(struct task_struct *t);
     35
     36/**
     37 * rcu_read_lock_trace - mark beginning of RCU-trace read-side critical section
     38 *
     39 * When synchronize_rcu_tasks_trace() is invoked by one task, then that
     40 * task is guaranteed to block until all other tasks exit their read-side
     41 * critical sections.  Similarly, if call_rcu_trace() is invoked on one
     42 * task while other tasks are within RCU read-side critical sections,
     43 * invocation of the corresponding RCU callback is deferred until after
     44 * the all the other tasks exit their critical sections.
     45 *
     46 * For more details, please see the documentation for rcu_read_lock().
     47 */
     48static inline void rcu_read_lock_trace(void)
     49{
     50	struct task_struct *t = current;
     51
     52	WRITE_ONCE(t->trc_reader_nesting, READ_ONCE(t->trc_reader_nesting) + 1);
     53	barrier();
     54	if (IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB) &&
     55	    t->trc_reader_special.b.need_mb)
     56		smp_mb(); // Pairs with update-side barriers
     57	rcu_lock_acquire(&rcu_trace_lock_map);
     58}
     59
     60/**
     61 * rcu_read_unlock_trace - mark end of RCU-trace read-side critical section
     62 *
     63 * Pairs with a preceding call to rcu_read_lock_trace(), and nesting is
     64 * allowed.  Invoking a rcu_read_unlock_trace() when there is no matching
     65 * rcu_read_lock_trace() is verboten, and will result in lockdep complaints.
     66 *
     67 * For more details, please see the documentation for rcu_read_unlock().
     68 */
     69static inline void rcu_read_unlock_trace(void)
     70{
     71	int nesting;
     72	struct task_struct *t = current;
     73
     74	rcu_lock_release(&rcu_trace_lock_map);
     75	nesting = READ_ONCE(t->trc_reader_nesting) - 1;
     76	barrier(); // Critical section before disabling.
     77	// Disable IPI-based setting of .need_qs.
     78	WRITE_ONCE(t->trc_reader_nesting, INT_MIN);
     79	if (likely(!READ_ONCE(t->trc_reader_special.s)) || nesting) {
     80		WRITE_ONCE(t->trc_reader_nesting, nesting);
     81		return;  // We assume shallow reader nesting.
     82	}
     83	WARN_ON_ONCE(nesting != 0);
     84	rcu_read_unlock_trace_special(t);
     85}
     86
     87void call_rcu_tasks_trace(struct rcu_head *rhp, rcu_callback_t func);
     88void synchronize_rcu_tasks_trace(void);
     89void rcu_barrier_tasks_trace(void);
     90#else
     91/*
     92 * The BPF JIT forms these addresses even when it doesn't call these
     93 * functions, so provide definitions that result in runtime errors.
     94 */
     95static inline void call_rcu_tasks_trace(struct rcu_head *rhp, rcu_callback_t func) { BUG(); }
     96static inline void rcu_read_lock_trace(void) { BUG(); }
     97static inline void rcu_read_unlock_trace(void) { BUG(); }
     98#endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
     99
    100#endif /* __LINUX_RCUPDATE_TRACE_H */