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 (up to a max of PAGE_SIZE).
12 */
13
14 struct trace_seq {
15 char buffer[PAGE_SIZE];
16 struct seq_buf seq;
17 size_t readpos;
18 int full;
19 };
20
21 static inline void
trace_seq_init(struct trace_seq * s)22 trace_seq_init(struct trace_seq *s)
23 {
24 seq_buf_init(&s->seq, s->buffer, PAGE_SIZE);
25 s->full = 0;
26 s->readpos = 0;
27 }
28
29 /**
30 * trace_seq_used - amount of actual data written to buffer
31 * @s: trace sequence descriptor
32 *
33 * Returns the amount of data written to the buffer.
34 *
35 * IMPORTANT!
36 *
37 * Use this instead of @s->seq.len if you need to pass the amount
38 * of data from the buffer to another buffer (userspace, or what not).
39 * The @s->seq.len on overflow is bigger than the buffer size and
40 * using it can cause access to undefined memory.
41 */
trace_seq_used(struct trace_seq * s)42 static inline int trace_seq_used(struct trace_seq *s)
43 {
44 return seq_buf_used(&s->seq);
45 }
46
47 /**
48 * trace_seq_buffer_ptr - return pointer to next location in buffer
49 * @s: trace sequence descriptor
50 *
51 * Returns the pointer to the buffer where the next write to
52 * the buffer will happen. This is useful to save the location
53 * that is about to be written to and then return the result
54 * of that write.
55 */
56 static inline char *
trace_seq_buffer_ptr(struct trace_seq * s)57 trace_seq_buffer_ptr(struct trace_seq *s)
58 {
59 return s->buffer + seq_buf_used(&s->seq);
60 }
61
62 /**
63 * trace_seq_has_overflowed - return true if the trace_seq took too much
64 * @s: trace sequence descriptor
65 *
66 * Returns true if too much data was added to the trace_seq and it is
67 * now full and will not take anymore.
68 */
trace_seq_has_overflowed(struct trace_seq * s)69 static inline bool trace_seq_has_overflowed(struct trace_seq *s)
70 {
71 return s->full || seq_buf_has_overflowed(&s->seq);
72 }
73
74 /*
75 * Currently only defined when tracing is enabled.
76 */
77 #ifdef CONFIG_TRACING
78 extern __printf(2, 3)
79 void trace_seq_printf(struct trace_seq *s, const char *fmt, ...);
80 extern __printf(2, 0)
81 void trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args);
82 extern void
83 trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary);
84 extern int trace_print_seq(struct seq_file *m, struct trace_seq *s);
85 extern int trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
86 int cnt);
87 extern void trace_seq_puts(struct trace_seq *s, const char *str);
88 extern void trace_seq_putc(struct trace_seq *s, unsigned char c);
89 extern void trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len);
90 extern void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
91 unsigned int len);
92 extern int trace_seq_path(struct trace_seq *s, const struct path *path);
93
94 extern void trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
95 int nmaskbits);
96
97 extern int trace_seq_hex_dump(struct trace_seq *s, const char *prefix_str,
98 int prefix_type, int rowsize, int groupsize,
99 const void *buf, size_t len, bool ascii);
100 char *trace_seq_acquire(struct trace_seq *s, unsigned int len);
101
102 #else /* CONFIG_TRACING */
103 static inline __printf(2, 3)
trace_seq_printf(struct trace_seq * s,const char * fmt,...)104 void trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
105 {
106 }
107 static inline void
trace_seq_bprintf(struct trace_seq * s,const char * fmt,const u32 * binary)108 trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
109 {
110 }
111
112 static inline void
trace_seq_bitmask(struct trace_seq * s,const unsigned long * maskp,int nmaskbits)113 trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
114 int nmaskbits)
115 {
116 }
117
trace_print_seq(struct seq_file * m,struct trace_seq * s)118 static inline int trace_print_seq(struct seq_file *m, struct trace_seq *s)
119 {
120 return 0;
121 }
trace_seq_to_user(struct trace_seq * s,char __user * ubuf,int cnt)122 static inline int trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
123 int cnt)
124 {
125 return 0;
126 }
trace_seq_puts(struct trace_seq * s,const char * str)127 static inline void trace_seq_puts(struct trace_seq *s, const char *str)
128 {
129 }
trace_seq_putc(struct trace_seq * s,unsigned char c)130 static inline void trace_seq_putc(struct trace_seq *s, unsigned char c)
131 {
132 }
133 static inline void
trace_seq_putmem(struct trace_seq * s,const void * mem,unsigned int len)134 trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len)
135 {
136 }
trace_seq_putmem_hex(struct trace_seq * s,const void * mem,unsigned int len)137 static inline void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
138 unsigned int len)
139 {
140 }
trace_seq_path(struct trace_seq * s,const struct path * path)141 static inline int trace_seq_path(struct trace_seq *s, const struct path *path)
142 {
143 return 0;
144 }
trace_seq_acquire(struct trace_seq * s,unsigned int len)145 static inline char *trace_seq_acquire(struct trace_seq *s, unsigned int len)
146 {
147 return NULL;
148 }
149 #endif /* CONFIG_TRACING */
150
151 #endif /* _LINUX_TRACE_SEQ_H */
152