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#include <uapi/linux/trace_mmap.h>
10
11struct trace_buffer;
12struct ring_buffer_iter;
13
14/*
15 * Don't refer to this struct directly, use functions below.
16 */
17struct ring_buffer_event {
18 u32 type_len:5, time_delta:27;
19
20 u32 array[];
21};
22
23/**
24 * enum ring_buffer_type - internal ring buffer types
25 *
26 * @RINGBUF_TYPE_PADDING: Left over page padding or discarded event
27 * If time_delta is 0:
28 * array is ignored
29 * size is variable depending on how much
30 * padding is needed
31 * If time_delta is non zero:
32 * array[0] holds the actual length
33 * size = 4 + length (bytes)
34 *
35 * @RINGBUF_TYPE_TIME_EXTEND: Extend the time delta
36 * array[0] = time delta (28 .. 59)
37 * size = 8 bytes
38 *
39 * @RINGBUF_TYPE_TIME_STAMP: Absolute timestamp
40 * Same format as TIME_EXTEND except that the
41 * value is an absolute timestamp, not a delta
42 * event.time_delta contains bottom 27 bits
43 * array[0] = top (28 .. 59) bits
44 * size = 8 bytes
45 *
46 * <= @RINGBUF_TYPE_DATA_TYPE_LEN_MAX:
47 * Data record
48 * If type_len is zero:
49 * array[0] holds the actual length
50 * array[1..(length+3)/4] holds data
51 * size = 4 + length (bytes)
52 * else
53 * length = type_len << 2
54 * array[0..(length+3)/4-1] holds data
55 * size = 4 + length (bytes)
56 */
57enum ring_buffer_type {
58 RINGBUF_TYPE_DATA_TYPE_LEN_MAX = 28,
59 RINGBUF_TYPE_PADDING,
60 RINGBUF_TYPE_TIME_EXTEND,
61 RINGBUF_TYPE_TIME_STAMP,
62};
63
64unsigned ring_buffer_event_length(struct ring_buffer_event *event);
65void *ring_buffer_event_data(struct ring_buffer_event *event);
66u64 ring_buffer_event_time_stamp(struct trace_buffer *buffer,
67 struct ring_buffer_event *event);
68
69/*
70 * ring_buffer_discard_commit will remove an event that has not
71 * been committed yet. If this is used, then ring_buffer_unlock_commit
72 * must not be called on the discarded event. This function
73 * will try to remove the event from the ring buffer completely
74 * if another event has not been written after it.
75 *
76 * Example use:
77 *
78 * if (some_condition)
79 * ring_buffer_discard_commit(buffer, event);
80 * else
81 * ring_buffer_unlock_commit(buffer, event);
82 */
83void ring_buffer_discard_commit(struct trace_buffer *buffer,
84 struct ring_buffer_event *event);
85
86/*
87 * size is in bytes for each per CPU buffer.
88 */
89struct trace_buffer *
90__ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key);
91
92struct trace_buffer *__ring_buffer_alloc_range(unsigned long size, unsigned flags,
93 int order, unsigned long start,
94 unsigned long range_size,
95 unsigned long scratch_size,
96 struct lock_class_key *key);
97
98void *ring_buffer_meta_scratch(struct trace_buffer *buffer, unsigned int *size);
99
100/*
101 * Because the ring buffer is generic, if other users of the ring buffer get
102 * traced by ftrace, it can produce lockdep warnings. We need to keep each
103 * ring buffer's lock class separate.
104 */
105#define ring_buffer_alloc(size, flags) \
106({ \
107 static struct lock_class_key __key; \
108 __ring_buffer_alloc((size), (flags), &__key); \
109})
110
111/*
112 * Because the ring buffer is generic, if other users of the ring buffer get
113 * traced by ftrace, it can produce lockdep warnings. We need to keep each
114 * ring buffer's lock class separate.
115 */
116#define ring_buffer_alloc_range(size, flags, order, start, range_size, s_size) \
117({ \
118 static struct lock_class_key __key; \
119 __ring_buffer_alloc_range((size), (flags), (order), (start), \
120 (range_size), (s_size), &__key); \
121})
122
123typedef bool (*ring_buffer_cond_fn)(void *data);
124int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full,
125 ring_buffer_cond_fn cond, void *data);
126__poll_t ring_buffer_poll_wait(struct trace_buffer *buffer, int cpu,
127 struct file *filp, poll_table *poll_table, int full);
128void ring_buffer_wake_waiters(struct trace_buffer *buffer, int cpu);
129
130#define RING_BUFFER_ALL_CPUS -1
131
132void ring_buffer_free(struct trace_buffer *buffer);
133
134int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size, int cpu);
135
136void ring_buffer_change_overwrite(struct trace_buffer *buffer, int val);
137
138struct ring_buffer_event *ring_buffer_lock_reserve(struct trace_buffer *buffer,
139 unsigned long length);
140int ring_buffer_unlock_commit(struct trace_buffer *buffer);
141int ring_buffer_write(struct trace_buffer *buffer,
142 unsigned long length, void *data);
143
144void ring_buffer_nest_start(struct trace_buffer *buffer);
145void ring_buffer_nest_end(struct trace_buffer *buffer);
146
147struct ring_buffer_event *
148ring_buffer_peek(struct trace_buffer *buffer, int cpu, u64 *ts,
149 unsigned long *lost_events);
150struct ring_buffer_event *
151ring_buffer_consume(struct trace_buffer *buffer, int cpu, u64 *ts,
152 unsigned long *lost_events);
153
154struct ring_buffer_iter *
155ring_buffer_read_prepare(struct trace_buffer *buffer, int cpu, gfp_t flags);
156void ring_buffer_read_prepare_sync(void);
157void ring_buffer_read_start(struct ring_buffer_iter *iter);
158void ring_buffer_read_finish(struct ring_buffer_iter *iter);
159
160struct ring_buffer_event *
161ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
162void ring_buffer_iter_advance(struct ring_buffer_iter *iter);
163void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
164int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
165bool ring_buffer_iter_dropped(struct ring_buffer_iter *iter);
166
167unsigned long ring_buffer_size(struct trace_buffer *buffer, int cpu);
168unsigned long ring_buffer_max_event_size(struct trace_buffer *buffer);
169
170void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu);
171void ring_buffer_reset_online_cpus(struct trace_buffer *buffer);
172void ring_buffer_reset(struct trace_buffer *buffer);
173
174#ifdef CONFIG_RING_BUFFER_ALLOW_SWAP
175int ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
176 struct trace_buffer *buffer_b, int cpu);
177#else
178static inline int
179ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
180 struct trace_buffer *buffer_b, int cpu)
181{
182 return -ENODEV;
183}
184#endif
185
186bool ring_buffer_empty(struct trace_buffer *buffer);
187bool ring_buffer_empty_cpu(struct trace_buffer *buffer, int cpu);
188
189void ring_buffer_record_disable(struct trace_buffer *buffer);
190void ring_buffer_record_enable(struct trace_buffer *buffer);
191void ring_buffer_record_off(struct trace_buffer *buffer);
192void ring_buffer_record_on(struct trace_buffer *buffer);
193bool ring_buffer_record_is_on(struct trace_buffer *buffer);
194bool ring_buffer_record_is_set_on(struct trace_buffer *buffer);
195bool ring_buffer_record_is_on_cpu(struct trace_buffer *buffer, int cpu);
196void ring_buffer_record_disable_cpu(struct trace_buffer *buffer, int cpu);
197void ring_buffer_record_enable_cpu(struct trace_buffer *buffer, int cpu);
198
199u64 ring_buffer_oldest_event_ts(struct trace_buffer *buffer, int cpu);
200unsigned long ring_buffer_bytes_cpu(struct trace_buffer *buffer, int cpu);
201unsigned long ring_buffer_entries(struct trace_buffer *buffer);
202unsigned long ring_buffer_overruns(struct trace_buffer *buffer);
203unsigned long ring_buffer_entries_cpu(struct trace_buffer *buffer, int cpu);
204unsigned long ring_buffer_overrun_cpu(struct trace_buffer *buffer, int cpu);
205unsigned long ring_buffer_commit_overrun_cpu(struct trace_buffer *buffer, int cpu);
206unsigned long ring_buffer_dropped_events_cpu(struct trace_buffer *buffer, int cpu);
207unsigned long ring_buffer_read_events_cpu(struct trace_buffer *buffer, int cpu);
208
209u64 ring_buffer_time_stamp(struct trace_buffer *buffer);
210void ring_buffer_normalize_time_stamp(struct trace_buffer *buffer,
211 int cpu, u64 *ts);
212void ring_buffer_set_clock(struct trace_buffer *buffer,
213 u64 (*clock)(void));
214void ring_buffer_set_time_stamp_abs(struct trace_buffer *buffer, bool abs);
215bool ring_buffer_time_stamp_abs(struct trace_buffer *buffer);
216
217size_t ring_buffer_nr_dirty_pages(struct trace_buffer *buffer, int cpu);
218
219struct buffer_data_read_page;
220struct buffer_data_read_page *
221ring_buffer_alloc_read_page(struct trace_buffer *buffer, int cpu);
222void ring_buffer_free_read_page(struct trace_buffer *buffer, int cpu,
223 struct buffer_data_read_page *page);
224int ring_buffer_read_page(struct trace_buffer *buffer,
225 struct buffer_data_read_page *data_page,
226 size_t len, int cpu, int full);
227void *ring_buffer_read_page_data(struct buffer_data_read_page *page);
228
229struct trace_seq;
230
231int ring_buffer_print_entry_header(struct trace_seq *s);
232int ring_buffer_print_page_header(struct trace_buffer *buffer, struct trace_seq *s);
233
234int ring_buffer_subbuf_order_get(struct trace_buffer *buffer);
235int ring_buffer_subbuf_order_set(struct trace_buffer *buffer, int order);
236int ring_buffer_subbuf_size_get(struct trace_buffer *buffer);
237
238enum ring_buffer_flags {
239 RB_FL_OVERWRITE = 1 << 0,
240};
241
242#ifdef CONFIG_RING_BUFFER
243int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node);
244#else
245#define trace_rb_cpu_prepare NULL
246#endif
247
248int ring_buffer_map(struct trace_buffer *buffer, int cpu,
249 struct vm_area_struct *vma);
250int ring_buffer_unmap(struct trace_buffer *buffer, int cpu);
251int ring_buffer_map_get_reader(struct trace_buffer *buffer, int cpu);
252#endif /* _LINUX_RING_BUFFER_H */
253

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