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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notifier.h (8356B)


      1/* SPDX-License-Identifier: GPL-2.0 */
      2/*
      3 *	Routines to manage notifier chains for passing status changes to any
      4 *	interested routines. We need this instead of hard coded call lists so
      5 *	that modules can poke their nose into the innards. The network devices
      6 *	needed them so here they are for the rest of you.
      7 *
      8 *				Alan Cox <Alan.Cox@linux.org>
      9 */
     10 
     11#ifndef _LINUX_NOTIFIER_H
     12#define _LINUX_NOTIFIER_H
     13#include <linux/errno.h>
     14#include <linux/mutex.h>
     15#include <linux/rwsem.h>
     16#include <linux/srcu.h>
     17
     18/*
     19 * Notifier chains are of four types:
     20 *
     21 *	Atomic notifier chains: Chain callbacks run in interrupt/atomic
     22 *		context. Callouts are not allowed to block.
     23 *	Blocking notifier chains: Chain callbacks run in process context.
     24 *		Callouts are allowed to block.
     25 *	Raw notifier chains: There are no restrictions on callbacks,
     26 *		registration, or unregistration.  All locking and protection
     27 *		must be provided by the caller.
     28 *	SRCU notifier chains: A variant of blocking notifier chains, with
     29 *		the same restrictions.
     30 *
     31 * atomic_notifier_chain_register() may be called from an atomic context,
     32 * but blocking_notifier_chain_register() and srcu_notifier_chain_register()
     33 * must be called from a process context.  Ditto for the corresponding
     34 * _unregister() routines.
     35 *
     36 * atomic_notifier_chain_unregister(), blocking_notifier_chain_unregister(),
     37 * and srcu_notifier_chain_unregister() _must not_ be called from within
     38 * the call chain.
     39 *
     40 * SRCU notifier chains are an alternative form of blocking notifier chains.
     41 * They use SRCU (Sleepable Read-Copy Update) instead of rw-semaphores for
     42 * protection of the chain links.  This means there is _very_ low overhead
     43 * in srcu_notifier_call_chain(): no cache bounces and no memory barriers.
     44 * As compensation, srcu_notifier_chain_unregister() is rather expensive.
     45 * SRCU notifier chains should be used when the chain will be called very
     46 * often but notifier_blocks will seldom be removed.
     47 */
     48
     49struct notifier_block;
     50
     51typedef	int (*notifier_fn_t)(struct notifier_block *nb,
     52			unsigned long action, void *data);
     53
     54struct notifier_block {
     55	notifier_fn_t notifier_call;
     56	struct notifier_block __rcu *next;
     57	int priority;
     58};
     59
     60struct atomic_notifier_head {
     61	spinlock_t lock;
     62	struct notifier_block __rcu *head;
     63};
     64
     65struct blocking_notifier_head {
     66	struct rw_semaphore rwsem;
     67	struct notifier_block __rcu *head;
     68};
     69
     70struct raw_notifier_head {
     71	struct notifier_block __rcu *head;
     72};
     73
     74struct srcu_notifier_head {
     75	struct mutex mutex;
     76	struct srcu_struct srcu;
     77	struct notifier_block __rcu *head;
     78};
     79
     80#define ATOMIC_INIT_NOTIFIER_HEAD(name) do {	\
     81		spin_lock_init(&(name)->lock);	\
     82		(name)->head = NULL;		\
     83	} while (0)
     84#define BLOCKING_INIT_NOTIFIER_HEAD(name) do {	\
     85		init_rwsem(&(name)->rwsem);	\
     86		(name)->head = NULL;		\
     87	} while (0)
     88#define RAW_INIT_NOTIFIER_HEAD(name) do {	\
     89		(name)->head = NULL;		\
     90	} while (0)
     91
     92/* srcu_notifier_heads must be cleaned up dynamically */
     93extern void srcu_init_notifier_head(struct srcu_notifier_head *nh);
     94#define srcu_cleanup_notifier_head(name)	\
     95		cleanup_srcu_struct(&(name)->srcu);
     96
     97#define ATOMIC_NOTIFIER_INIT(name) {				\
     98		.lock = __SPIN_LOCK_UNLOCKED(name.lock),	\
     99		.head = NULL }
    100#define BLOCKING_NOTIFIER_INIT(name) {				\
    101		.rwsem = __RWSEM_INITIALIZER((name).rwsem),	\
    102		.head = NULL }
    103#define RAW_NOTIFIER_INIT(name)	{				\
    104		.head = NULL }
    105
    106#define SRCU_NOTIFIER_INIT(name, pcpu)				\
    107	{							\
    108		.mutex = __MUTEX_INITIALIZER(name.mutex),	\
    109		.head = NULL,					\
    110		.srcu = __SRCU_STRUCT_INIT(name.srcu, pcpu),	\
    111	}
    112
    113#define ATOMIC_NOTIFIER_HEAD(name)				\
    114	struct atomic_notifier_head name =			\
    115		ATOMIC_NOTIFIER_INIT(name)
    116#define BLOCKING_NOTIFIER_HEAD(name)				\
    117	struct blocking_notifier_head name =			\
    118		BLOCKING_NOTIFIER_INIT(name)
    119#define RAW_NOTIFIER_HEAD(name)					\
    120	struct raw_notifier_head name =				\
    121		RAW_NOTIFIER_INIT(name)
    122
    123#ifdef CONFIG_TREE_SRCU
    124#define _SRCU_NOTIFIER_HEAD(name, mod)				\
    125	static DEFINE_PER_CPU(struct srcu_data, name##_head_srcu_data); \
    126	mod struct srcu_notifier_head name =			\
    127			SRCU_NOTIFIER_INIT(name, name##_head_srcu_data)
    128
    129#else
    130#define _SRCU_NOTIFIER_HEAD(name, mod)				\
    131	mod struct srcu_notifier_head name =			\
    132			SRCU_NOTIFIER_INIT(name, name)
    133
    134#endif
    135
    136#define SRCU_NOTIFIER_HEAD(name)				\
    137	_SRCU_NOTIFIER_HEAD(name, /* not static */)
    138
    139#define SRCU_NOTIFIER_HEAD_STATIC(name)				\
    140	_SRCU_NOTIFIER_HEAD(name, static)
    141
    142#ifdef __KERNEL__
    143
    144extern int atomic_notifier_chain_register(struct atomic_notifier_head *nh,
    145		struct notifier_block *nb);
    146extern int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
    147		struct notifier_block *nb);
    148extern int raw_notifier_chain_register(struct raw_notifier_head *nh,
    149		struct notifier_block *nb);
    150extern int srcu_notifier_chain_register(struct srcu_notifier_head *nh,
    151		struct notifier_block *nb);
    152
    153extern int atomic_notifier_chain_register_unique_prio(
    154		struct atomic_notifier_head *nh, struct notifier_block *nb);
    155extern int blocking_notifier_chain_register_unique_prio(
    156		struct blocking_notifier_head *nh, struct notifier_block *nb);
    157
    158extern int atomic_notifier_chain_unregister(struct atomic_notifier_head *nh,
    159		struct notifier_block *nb);
    160extern int blocking_notifier_chain_unregister(struct blocking_notifier_head *nh,
    161		struct notifier_block *nb);
    162extern int raw_notifier_chain_unregister(struct raw_notifier_head *nh,
    163		struct notifier_block *nb);
    164extern int srcu_notifier_chain_unregister(struct srcu_notifier_head *nh,
    165		struct notifier_block *nb);
    166
    167extern int atomic_notifier_call_chain(struct atomic_notifier_head *nh,
    168		unsigned long val, void *v);
    169extern int blocking_notifier_call_chain(struct blocking_notifier_head *nh,
    170		unsigned long val, void *v);
    171extern int raw_notifier_call_chain(struct raw_notifier_head *nh,
    172		unsigned long val, void *v);
    173extern int srcu_notifier_call_chain(struct srcu_notifier_head *nh,
    174		unsigned long val, void *v);
    175
    176extern int blocking_notifier_call_chain_robust(struct blocking_notifier_head *nh,
    177		unsigned long val_up, unsigned long val_down, void *v);
    178extern int raw_notifier_call_chain_robust(struct raw_notifier_head *nh,
    179		unsigned long val_up, unsigned long val_down, void *v);
    180
    181extern bool atomic_notifier_call_chain_is_empty(struct atomic_notifier_head *nh);
    182
    183#define NOTIFY_DONE		0x0000		/* Don't care */
    184#define NOTIFY_OK		0x0001		/* Suits me */
    185#define NOTIFY_STOP_MASK	0x8000		/* Don't call further */
    186#define NOTIFY_BAD		(NOTIFY_STOP_MASK|0x0002)
    187						/* Bad/Veto action */
    188/*
    189 * Clean way to return from the notifier and stop further calls.
    190 */
    191#define NOTIFY_STOP		(NOTIFY_OK|NOTIFY_STOP_MASK)
    192
    193/* Encapsulate (negative) errno value (in particular, NOTIFY_BAD <=> EPERM). */
    194static inline int notifier_from_errno(int err)
    195{
    196	if (err)
    197		return NOTIFY_STOP_MASK | (NOTIFY_OK - err);
    198
    199	return NOTIFY_OK;
    200}
    201
    202/* Restore (negative) errno value from notify return value. */
    203static inline int notifier_to_errno(int ret)
    204{
    205	ret &= ~NOTIFY_STOP_MASK;
    206	return ret > NOTIFY_OK ? NOTIFY_OK - ret : 0;
    207}
    208
    209/*
    210 *	Declared notifiers so far. I can imagine quite a few more chains
    211 *	over time (eg laptop power reset chains, reboot chain (to clean 
    212 *	device units up), device [un]mount chain, module load/unload chain,
    213 *	low memory chain, screenblank chain (for plug in modular screenblankers) 
    214 *	VC switch chains (for loadable kernel svgalib VC switch helpers) etc...
    215 */
    216 
    217/* CPU notfiers are defined in include/linux/cpu.h. */
    218
    219/* netdevice notifiers are defined in include/linux/netdevice.h */
    220
    221/* reboot notifiers are defined in include/linux/reboot.h. */
    222
    223/* Hibernation and suspend events are defined in include/linux/suspend.h. */
    224
    225/* Virtual Terminal events are defined in include/linux/vt.h. */
    226
    227#define NETLINK_URELEASE	0x0001	/* Unicast netlink socket released */
    228
    229/* Console keyboard events.
    230 * Note: KBD_KEYCODE is always sent before KBD_UNBOUND_KEYCODE, KBD_UNICODE and
    231 * KBD_KEYSYM. */
    232#define KBD_KEYCODE		0x0001 /* Keyboard keycode, called before any other */
    233#define KBD_UNBOUND_KEYCODE	0x0002 /* Keyboard keycode which is not bound to any other */
    234#define KBD_UNICODE		0x0003 /* Keyboard unicode */
    235#define KBD_KEYSYM		0x0004 /* Keyboard keysym */
    236#define KBD_POST_KEYSYM		0x0005 /* Called after keyboard keysym interpretation */
    237
    238extern struct blocking_notifier_head reboot_notifier_list;
    239
    240#endif /* __KERNEL__ */
    241#endif /* _LINUX_NOTIFIER_H */