xref: /linux/include/linux/ring_buffer.h (revision 547f574fd9d5e3925d47fd44decbf6ab6df94b0e)
1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_RING_BUFFER_H
3 #define _LINUX_RING_BUFFER_H
4 
5 #include <linux/mm.h>
6 #include <linux/seq_file.h>
7 #include <linux/poll.h>
8 
9 struct trace_buffer;
10 struct ring_buffer_iter;
11 
12 /*
13  * Don't refer to this struct directly, use functions below.
14  */
15 struct ring_buffer_event {
16 	u32		type_len:5, time_delta:27;
17 
18 	u32		array[];
19 };
20 
21 /**
22  * enum ring_buffer_type - internal ring buffer types
23  *
24  * @RINGBUF_TYPE_PADDING:	Left over page padding or discarded event
25  *				 If time_delta is 0:
26  *				  array is ignored
27  *				  size is variable depending on how much
28  *				  padding is needed
29  *				 If time_delta is non zero:
30  *				  array[0] holds the actual length
31  *				  size = 4 + length (bytes)
32  *
33  * @RINGBUF_TYPE_TIME_EXTEND:	Extend the time delta
34  *				 array[0] = time delta (28 .. 59)
35  *				 size = 8 bytes
36  *
37  * @RINGBUF_TYPE_TIME_STAMP:	Absolute timestamp
38  *				 Same format as TIME_EXTEND except that the
39  *				 value is an absolute timestamp, not a delta
40  *				 event.time_delta contains bottom 27 bits
41  *				 array[0] = top (28 .. 59) bits
42  *				 size = 8 bytes
43  *
44  * <= @RINGBUF_TYPE_DATA_TYPE_LEN_MAX:
45  *				Data record
46  *				 If type_len is zero:
47  *				  array[0] holds the actual length
48  *				  array[1..(length+3)/4] holds data
49  *				  size = 4 + length (bytes)
50  *				 else
51  *				  length = type_len << 2
52  *				  array[0..(length+3)/4-1] holds data
53  *				  size = 4 + length (bytes)
54  */
55 enum ring_buffer_type {
56 	RINGBUF_TYPE_DATA_TYPE_LEN_MAX = 28,
57 	RINGBUF_TYPE_PADDING,
58 	RINGBUF_TYPE_TIME_EXTEND,
59 	RINGBUF_TYPE_TIME_STAMP,
60 };
61 
62 unsigned ring_buffer_event_length(struct ring_buffer_event *event);
63 void *ring_buffer_event_data(struct ring_buffer_event *event);
64 u64 ring_buffer_event_time_stamp(struct ring_buffer_event *event);
65 
66 /*
67  * ring_buffer_discard_commit will remove an event that has not
68  *   been committed yet. If this is used, then ring_buffer_unlock_commit
69  *   must not be called on the discarded event. This function
70  *   will try to remove the event from the ring buffer completely
71  *   if another event has not been written after it.
72  *
73  * Example use:
74  *
75  *  if (some_condition)
76  *    ring_buffer_discard_commit(buffer, event);
77  *  else
78  *    ring_buffer_unlock_commit(buffer, event);
79  */
80 void ring_buffer_discard_commit(struct trace_buffer *buffer,
81 				struct ring_buffer_event *event);
82 
83 /*
84  * size is in bytes for each per CPU buffer.
85  */
86 struct trace_buffer *
87 __ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key);
88 
89 /*
90  * Because the ring buffer is generic, if other users of the ring buffer get
91  * traced by ftrace, it can produce lockdep warnings. We need to keep each
92  * ring buffer's lock class separate.
93  */
94 #define ring_buffer_alloc(size, flags)			\
95 ({							\
96 	static struct lock_class_key __key;		\
97 	__ring_buffer_alloc((size), (flags), &__key);	\
98 })
99 
100 int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full);
101 __poll_t ring_buffer_poll_wait(struct trace_buffer *buffer, int cpu,
102 			  struct file *filp, poll_table *poll_table);
103 
104 
105 #define RING_BUFFER_ALL_CPUS -1
106 
107 void ring_buffer_free(struct trace_buffer *buffer);
108 
109 int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size, int cpu);
110 
111 void ring_buffer_change_overwrite(struct trace_buffer *buffer, int val);
112 
113 struct ring_buffer_event *ring_buffer_lock_reserve(struct trace_buffer *buffer,
114 						   unsigned long length);
115 int ring_buffer_unlock_commit(struct trace_buffer *buffer,
116 			      struct ring_buffer_event *event);
117 int ring_buffer_write(struct trace_buffer *buffer,
118 		      unsigned long length, void *data);
119 
120 void ring_buffer_nest_start(struct trace_buffer *buffer);
121 void ring_buffer_nest_end(struct trace_buffer *buffer);
122 
123 struct ring_buffer_event *
124 ring_buffer_peek(struct trace_buffer *buffer, int cpu, u64 *ts,
125 		 unsigned long *lost_events);
126 struct ring_buffer_event *
127 ring_buffer_consume(struct trace_buffer *buffer, int cpu, u64 *ts,
128 		    unsigned long *lost_events);
129 
130 struct ring_buffer_iter *
131 ring_buffer_read_prepare(struct trace_buffer *buffer, int cpu, gfp_t flags);
132 void ring_buffer_read_prepare_sync(void);
133 void ring_buffer_read_start(struct ring_buffer_iter *iter);
134 void ring_buffer_read_finish(struct ring_buffer_iter *iter);
135 
136 struct ring_buffer_event *
137 ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
138 void ring_buffer_iter_advance(struct ring_buffer_iter *iter);
139 void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
140 int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
141 bool ring_buffer_iter_dropped(struct ring_buffer_iter *iter);
142 
143 unsigned long ring_buffer_size(struct trace_buffer *buffer, int cpu);
144 
145 void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu);
146 void ring_buffer_reset_online_cpus(struct trace_buffer *buffer);
147 void ring_buffer_reset(struct trace_buffer *buffer);
148 
149 #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP
150 int ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
151 			 struct trace_buffer *buffer_b, int cpu);
152 #else
153 static inline int
154 ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
155 		     struct trace_buffer *buffer_b, int cpu)
156 {
157 	return -ENODEV;
158 }
159 #endif
160 
161 bool ring_buffer_empty(struct trace_buffer *buffer);
162 bool ring_buffer_empty_cpu(struct trace_buffer *buffer, int cpu);
163 
164 void ring_buffer_record_disable(struct trace_buffer *buffer);
165 void ring_buffer_record_enable(struct trace_buffer *buffer);
166 void ring_buffer_record_off(struct trace_buffer *buffer);
167 void ring_buffer_record_on(struct trace_buffer *buffer);
168 bool ring_buffer_record_is_on(struct trace_buffer *buffer);
169 bool ring_buffer_record_is_set_on(struct trace_buffer *buffer);
170 void ring_buffer_record_disable_cpu(struct trace_buffer *buffer, int cpu);
171 void ring_buffer_record_enable_cpu(struct trace_buffer *buffer, int cpu);
172 
173 u64 ring_buffer_oldest_event_ts(struct trace_buffer *buffer, int cpu);
174 unsigned long ring_buffer_bytes_cpu(struct trace_buffer *buffer, int cpu);
175 unsigned long ring_buffer_entries(struct trace_buffer *buffer);
176 unsigned long ring_buffer_overruns(struct trace_buffer *buffer);
177 unsigned long ring_buffer_entries_cpu(struct trace_buffer *buffer, int cpu);
178 unsigned long ring_buffer_overrun_cpu(struct trace_buffer *buffer, int cpu);
179 unsigned long ring_buffer_commit_overrun_cpu(struct trace_buffer *buffer, int cpu);
180 unsigned long ring_buffer_dropped_events_cpu(struct trace_buffer *buffer, int cpu);
181 unsigned long ring_buffer_read_events_cpu(struct trace_buffer *buffer, int cpu);
182 
183 u64 ring_buffer_time_stamp(struct trace_buffer *buffer, int cpu);
184 void ring_buffer_normalize_time_stamp(struct trace_buffer *buffer,
185 				      int cpu, u64 *ts);
186 void ring_buffer_set_clock(struct trace_buffer *buffer,
187 			   u64 (*clock)(void));
188 void ring_buffer_set_time_stamp_abs(struct trace_buffer *buffer, bool abs);
189 bool ring_buffer_time_stamp_abs(struct trace_buffer *buffer);
190 
191 size_t ring_buffer_nr_pages(struct trace_buffer *buffer, int cpu);
192 size_t ring_buffer_nr_dirty_pages(struct trace_buffer *buffer, int cpu);
193 
194 void *ring_buffer_alloc_read_page(struct trace_buffer *buffer, int cpu);
195 void ring_buffer_free_read_page(struct trace_buffer *buffer, int cpu, void *data);
196 int ring_buffer_read_page(struct trace_buffer *buffer, void **data_page,
197 			  size_t len, int cpu, int full);
198 
199 struct trace_seq;
200 
201 int ring_buffer_print_entry_header(struct trace_seq *s);
202 int ring_buffer_print_page_header(struct trace_seq *s);
203 
204 enum ring_buffer_flags {
205 	RB_FL_OVERWRITE		= 1 << 0,
206 };
207 
208 #ifdef CONFIG_RING_BUFFER
209 int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node);
210 #else
211 #define trace_rb_cpu_prepare	NULL
212 #endif
213 
214 #endif /* _LINUX_RING_BUFFER_H */
215