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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srcutiny.h (2813B)

      1/* SPDX-License-Identifier: GPL-2.0+ */
      2/*
      3 * Sleepable Read-Copy Update mechanism for mutual exclusion,
      4 *	tiny variant.
      5 *
      6 * Copyright (C) IBM Corporation, 2017
      7 *
      8 * Author: Paul McKenney <paulmck@linux.ibm.com>
      9 */
     10
     11#ifndef _LINUX_SRCU_TINY_H
     12#define _LINUX_SRCU_TINY_H
     13
     14#include <linux/swait.h>
     15
     16struct srcu_struct {
     17	short srcu_lock_nesting[2];	/* srcu_read_lock() nesting depth. */
     18	unsigned short srcu_idx;	/* Current reader array element in bit 0x2. */
     19	unsigned short srcu_idx_max;	/* Furthest future srcu_idx request. */
     20	u8 srcu_gp_running;		/* GP workqueue running? */
     21	u8 srcu_gp_waiting;		/* GP waiting for readers? */
     22	struct swait_queue_head srcu_wq;
     23					/* Last srcu_read_unlock() wakes GP. */
     24	struct rcu_head *srcu_cb_head;	/* Pending callbacks: Head. */
     25	struct rcu_head **srcu_cb_tail;	/* Pending callbacks: Tail. */
     26	struct work_struct srcu_work;	/* For driving grace periods. */
     27#ifdef CONFIG_DEBUG_LOCK_ALLOC
     28	struct lockdep_map dep_map;
     29#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
     30};
     31
     32void srcu_drive_gp(struct work_struct *wp);
     33
     34#define __SRCU_STRUCT_INIT(name, __ignored)				\
     35{									\
     36	.srcu_wq = __SWAIT_QUEUE_HEAD_INITIALIZER(name.srcu_wq),	\
     37	.srcu_cb_tail = &name.srcu_cb_head,				\
     38	.srcu_work = __WORK_INITIALIZER(name.srcu_work, srcu_drive_gp),	\
     39	__SRCU_DEP_MAP_INIT(name)					\
     40}
     41
     42/*
     43 * This odd _STATIC_ arrangement is needed for API compatibility with
     44 * Tree SRCU, which needs some per-CPU data.
     45 */
     46#define DEFINE_SRCU(name) \
     47	struct srcu_struct name = __SRCU_STRUCT_INIT(name, name)
     48#define DEFINE_STATIC_SRCU(name) \
     49	static struct srcu_struct name = __SRCU_STRUCT_INIT(name, name)
     50
     51void synchronize_srcu(struct srcu_struct *ssp);
     52
     53/*
     54 * Counts the new reader in the appropriate per-CPU element of the
     55 * srcu_struct.  Can be invoked from irq/bh handlers, but the matching
     56 * __srcu_read_unlock() must be in the same handler instance.  Returns an
     57 * index that must be passed to the matching srcu_read_unlock().
     58 */
     59static inline int __srcu_read_lock(struct srcu_struct *ssp)
     60{
     61	int idx;
     62
     63	idx = ((READ_ONCE(ssp->srcu_idx) + 1) & 0x2) >> 1;
     64	WRITE_ONCE(ssp->srcu_lock_nesting[idx], READ_ONCE(ssp->srcu_lock_nesting[idx]) + 1);
     65	return idx;
     66}
     67
     68static inline void synchronize_srcu_expedited(struct srcu_struct *ssp)
     69{
     70	synchronize_srcu(ssp);
     71}
     72
     73static inline void srcu_barrier(struct srcu_struct *ssp)
     74{
     75	synchronize_srcu(ssp);
     76}
     77
     78/* Defined here to avoid size increase for non-torture kernels. */
     79static inline void srcu_torture_stats_print(struct srcu_struct *ssp,
     80					    char *tt, char *tf)
     81{
     82	int idx;
     83
     84	idx = ((data_race(READ_ONCE(ssp->srcu_idx)) + 1) & 0x2) >> 1;
     85	pr_alert("%s%s Tiny SRCU per-CPU(idx=%d): (%hd,%hd)\n",
     86		 tt, tf, idx,
     87		 data_race(READ_ONCE(ssp->srcu_lock_nesting[!idx])),
     88		 data_race(READ_ONCE(ssp->srcu_lock_nesting[idx])));
     89}
     90
     91#endif