1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_TRACE_SEQ_H
3#define _LINUX_TRACE_SEQ_H
4
5#include <linux/seq_buf.h>
6
7#include <asm/page.h>
8
9/*
10 * Trace sequences are used to allow a function to call several other functions
11 * to create a string of data to use.
12 *
13 * Have the trace seq to be 8K which is typically PAGE_SIZE * 2 on
14 * most architectures. The TRACE_SEQ_BUFFER_SIZE (which is
15 * TRACE_SEQ_SIZE minus the other fields of trace_seq), is the
16 * max size the output of a trace event may be.
17 */
18
19#define TRACE_SEQ_SIZE 8192
20#define TRACE_SEQ_BUFFER_SIZE (TRACE_SEQ_SIZE - \
21 (sizeof(struct seq_buf) + sizeof(size_t) + sizeof(int)))
22
23struct trace_seq {
24 struct seq_buf seq;
25 size_t readpos;
26 int full;
27 char buffer[TRACE_SEQ_BUFFER_SIZE];
28};
29
30static inline void
31trace_seq_init(struct trace_seq *s)
32{
33 seq_buf_init(s: &s->seq, buf: s->buffer, TRACE_SEQ_BUFFER_SIZE);
34 s->full = 0;
35 s->readpos = 0;
36}
37
38/**
39 * trace_seq_used - amount of actual data written to buffer
40 * @s: trace sequence descriptor
41 *
42 * Returns the amount of data written to the buffer.
43 *
44 * IMPORTANT!
45 *
46 * Use this instead of @s->seq.len if you need to pass the amount
47 * of data from the buffer to another buffer (userspace, or what not).
48 * The @s->seq.len on overflow is bigger than the buffer size and
49 * using it can cause access to undefined memory.
50 */
51static inline int trace_seq_used(struct trace_seq *s)
52{
53 return seq_buf_used(s: &s->seq);
54}
55
56/**
57 * trace_seq_buffer_ptr - return pointer to next location in buffer
58 * @s: trace sequence descriptor
59 *
60 * Returns the pointer to the buffer where the next write to
61 * the buffer will happen. This is useful to save the location
62 * that is about to be written to and then return the result
63 * of that write.
64 */
65static inline char *
66trace_seq_buffer_ptr(struct trace_seq *s)
67{
68 return s->buffer + seq_buf_used(s: &s->seq);
69}
70
71/**
72 * trace_seq_has_overflowed - return true if the trace_seq took too much
73 * @s: trace sequence descriptor
74 *
75 * Returns true if too much data was added to the trace_seq and it is
76 * now full and will not take anymore.
77 */
78static inline bool trace_seq_has_overflowed(struct trace_seq *s)
79{
80 return s->full || seq_buf_has_overflowed(s: &s->seq);
81}
82
83/**
84 * trace_seq_pop - pop off the last written character
85 * @s: trace sequence descriptor
86 *
87 * Removes the last written character to the trace_seq @s.
88 *
89 * Returns the last character or -1 if it is empty.
90 */
91static inline int trace_seq_pop(struct trace_seq *s)
92{
93 return seq_buf_pop(s: &s->seq);
94}
95
96/*
97 * Currently only defined when tracing is enabled.
98 */
99#ifdef CONFIG_TRACING
100extern __printf(2, 3)
101void trace_seq_printf(struct trace_seq *s, const char *fmt, ...);
102extern __printf(2, 0)
103void trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args);
104extern __printf(2, 0)
105void trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary);
106extern int trace_print_seq(struct seq_file *m, struct trace_seq *s);
107extern int trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
108 int cnt);
109extern void trace_seq_puts(struct trace_seq *s, const char *str);
110extern void trace_seq_putc(struct trace_seq *s, unsigned char c);
111extern void trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len);
112extern void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
113 unsigned int len);
114extern int trace_seq_path(struct trace_seq *s, const struct path *path);
115
116extern void trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
117 int nmaskbits);
118
119extern int trace_seq_hex_dump(struct trace_seq *s, const char *prefix_str,
120 int prefix_type, int rowsize, int groupsize,
121 const void *buf, size_t len, bool ascii);
122char *trace_seq_acquire(struct trace_seq *s, unsigned int len);
123
124#else /* CONFIG_TRACING */
125static inline __printf(2, 3)
126void trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
127{
128}
129static inline __printf(2, 0)
130void trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
131{
132}
133
134static inline void
135trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
136 int nmaskbits)
137{
138}
139
140static inline int trace_print_seq(struct seq_file *m, struct trace_seq *s)
141{
142 return 0;
143}
144static inline int trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
145 int cnt)
146{
147 return 0;
148}
149static inline void trace_seq_puts(struct trace_seq *s, const char *str)
150{
151}
152static inline void trace_seq_putc(struct trace_seq *s, unsigned char c)
153{
154}
155static inline void
156trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len)
157{
158}
159static inline void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
160 unsigned int len)
161{
162}
163static inline int trace_seq_path(struct trace_seq *s, const struct path *path)
164{
165 return 0;
166}
167static inline char *trace_seq_acquire(struct trace_seq *s, unsigned int len)
168{
169 return NULL;
170}
171#endif /* CONFIG_TRACING */
172
173#endif /* _LINUX_TRACE_SEQ_H */
174

source code of linux/include/linux/trace_seq.h