fprobe.h

  1/* SPDX-License-Identifier: GPL-2.0 */
  2/* Simple ftrace probe wrapper */
  3#ifndef _LINUX_FPROBE_H
  4#define _LINUX_FPROBE_H
  5
  6#include <linux/compiler.h>
  7#include <linux/ftrace.h>
  8#include <linux/rcupdate.h>
  9#include <linux/refcount.h>
 10#include <linux/rhashtable.h>
 11#include <linux/slab.h>
 12
 13struct fprobe;
 14typedef int (*fprobe_entry_cb)(struct fprobe *fp, unsigned long entry_ip,
 15			       unsigned long ret_ip, struct ftrace_regs *regs,
 16			       void *entry_data);
 17
 18typedef void (*fprobe_exit_cb)(struct fprobe *fp, unsigned long entry_ip,
 19			       unsigned long ret_ip, struct ftrace_regs *regs,
 20			       void *entry_data);
 21
 22/**
 23 * struct fprobe_hlist_node - address based hash list node for fprobe.
 24 *
 25 * @hlist: The hlist node for address search hash table.
 26 * @addr: One of the probing address of @fp.
 27 * @fp: The fprobe which owns this.
 28 */
 29struct fprobe_hlist_node {
 30	struct rhlist_head	hlist;
 31	unsigned long		addr;
 32	struct fprobe		*fp;
 33};
 34
 35/**
 36 * struct fprobe_hlist - hash list nodes for fprobe.
 37 *
 38 * @hlist: The hlist node for existence checking hash table.
 39 * @rcu: rcu_head for RCU deferred release.
 40 * @fp: The fprobe which owns this fprobe_hlist.
 41 * @size: The size of @array.
 42 * @array: The fprobe_hlist_node for each address to probe.
 43 */
 44struct fprobe_hlist {
 45	struct hlist_node		hlist;
 46	struct rcu_head			rcu;
 47	struct fprobe			*fp;
 48	int				size;
 49	struct fprobe_hlist_node	array[] __counted_by(size);
 50};
 51
 52/**
 53 * struct fprobe - ftrace based probe.
 54 *
 55 * @nmissed: The counter for missing events.
 56 * @flags: The status flag.
 57 * @entry_data_size: The private data storage size.
 58 * @entry_handler: The callback function for function entry.
 59 * @exit_handler: The callback function for function exit.
 60 * @hlist_array: The fprobe_hlist for fprobe search from IP hash table.
 61 */
 62struct fprobe {
 63	unsigned long		nmissed;
 64	unsigned int		flags;
 65	size_t			entry_data_size;
 66
 67	fprobe_entry_cb entry_handler;
 68	fprobe_exit_cb  exit_handler;
 69
 70	struct fprobe_hlist	*hlist_array;
 71};
 72
 73/* This fprobe is soft-disabled. */
 74#define FPROBE_FL_DISABLED	1
 75
 76/*
 77 * This fprobe handler will be shared with kprobes.
 78 * This flag must be set before registering.
 79 */
 80#define FPROBE_FL_KPROBE_SHARED	2
 81
 82static inline bool fprobe_disabled(struct fprobe *fp)
 83{
 84	return (fp) ? fp->flags & FPROBE_FL_DISABLED : false;
 85}
 86
 87static inline bool fprobe_shared_with_kprobes(struct fprobe *fp)
 88{
 89	return (fp) ? fp->flags & FPROBE_FL_KPROBE_SHARED : false;
 90}
 91
 92#ifdef CONFIG_FPROBE
 93int register_fprobe(struct fprobe *fp, const char *filter, const char *notfilter);
 94int register_fprobe_ips(struct fprobe *fp, unsigned long *addrs, int num);
 95int register_fprobe_syms(struct fprobe *fp, const char **syms, int num);
 96int unregister_fprobe(struct fprobe *fp);
 97bool fprobe_is_registered(struct fprobe *fp);
 98int fprobe_count_ips_from_filter(const char *filter, const char *notfilter);
 99#else
100static inline int register_fprobe(struct fprobe *fp, const char *filter, const char *notfilter)
101{
102	return -EOPNOTSUPP;
103}
104static inline int register_fprobe_ips(struct fprobe *fp, unsigned long *addrs, int num)
105{
106	return -EOPNOTSUPP;
107}
108static inline int register_fprobe_syms(struct fprobe *fp, const char **syms, int num)
109{
110	return -EOPNOTSUPP;
111}
112static inline int unregister_fprobe(struct fprobe *fp)
113{
114	return -EOPNOTSUPP;
115}
116static inline bool fprobe_is_registered(struct fprobe *fp)
117{
118	return false;
119}
120static inline int fprobe_count_ips_from_filter(const char *filter, const char *notfilter)
121{
122	return -EOPNOTSUPP;
123}
124#endif
125
126/**
127 * disable_fprobe() - Disable fprobe
128 * @fp: The fprobe to be disabled.
129 *
130 * This will soft-disable @fp. Note that this doesn't remove the ftrace
131 * hooks from the function entry.
132 */
133static inline void disable_fprobe(struct fprobe *fp)
134{
135	if (fp)
136		fp->flags |= FPROBE_FL_DISABLED;
137}
138
139/**
140 * enable_fprobe() - Enable fprobe
141 * @fp: The fprobe to be enabled.
142 *
143 * This will soft-enable @fp.
144 */
145static inline void enable_fprobe(struct fprobe *fp)
146{
147	if (fp)
148		fp->flags &= ~FPROBE_FL_DISABLED;
149}
150
151/* The entry data size is 4 bits (=16) * sizeof(long) in maximum */
152#define FPROBE_DATA_SIZE_BITS		4
153#define MAX_FPROBE_DATA_SIZE_WORD	((1L << FPROBE_DATA_SIZE_BITS) - 1)
154#define MAX_FPROBE_DATA_SIZE		(MAX_FPROBE_DATA_SIZE_WORD * sizeof(long))
155
156#endif