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