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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
9struct ring_buffer;
10struct ring_buffer_iter;
11
12/*
13 * Don't refer to this struct directly, use functions below.
14 */
15struct 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: Sync time stamp with external clock
38 * array[0] = tv_nsec
39 * array[1..2] = tv_sec
40 * size = 16 bytes
41 *
42 * <= @RINGBUF_TYPE_DATA_TYPE_LEN_MAX:
43 * Data record
44 * If type_len is zero:
45 * array[0] holds the actual length
46 * array[1..(length+3)/4] holds data
47 * size = 4 + length (bytes)
48 * else
49 * length = type_len << 2
50 * array[0..(length+3)/4-1] holds data
51 * size = 4 + length (bytes)
52 */
53enum ring_buffer_type {
54 RINGBUF_TYPE_DATA_TYPE_LEN_MAX = 28,
55 RINGBUF_TYPE_PADDING,
56 RINGBUF_TYPE_TIME_EXTEND,
57 /* FIXME: RINGBUF_TYPE_TIME_STAMP not implemented */
58 RINGBUF_TYPE_TIME_STAMP,
59};
60
61unsigned ring_buffer_event_length(struct ring_buffer_event *event);
62void *ring_buffer_event_data(struct ring_buffer_event *event);
63
64/*
65 * ring_buffer_discard_commit will remove an event that has not
66 * ben committed yet. If this is used, then ring_buffer_unlock_commit
67 * must not be called on the discarded event. This function
68 * will try to remove the event from the ring buffer completely
69 * if another event has not been written after it.
70 *
71 * Example use:
72 *
73 * if (some_condition)
74 * ring_buffer_discard_commit(buffer, event);
75 * else
76 * ring_buffer_unlock_commit(buffer, event);
77 */
78void ring_buffer_discard_commit(struct ring_buffer *buffer,
79 struct ring_buffer_event *event);
80
81/*
82 * size is in bytes for each per CPU buffer.
83 */
84struct ring_buffer *
85__ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key);
86
87/*
88 * Because the ring buffer is generic, if other users of the ring buffer get
89 * traced by ftrace, it can produce lockdep warnings. We need to keep each
90 * ring buffer's lock class separate.
91 */
92#define ring_buffer_alloc(size, flags) \
93({ \
94 static struct lock_class_key __key; \
95 __ring_buffer_alloc((size), (flags), &__key); \
96})
97
98int ring_buffer_wait(struct ring_buffer *buffer, int cpu, bool full);
99__poll_t ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu,
100 struct file *filp, poll_table *poll_table);
101
102
103#define RING_BUFFER_ALL_CPUS -1
104
105void ring_buffer_free(struct ring_buffer *buffer);
106
107int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size, int cpu);
108
109void ring_buffer_change_overwrite(struct ring_buffer *buffer, int val);
110
111struct ring_buffer_event *ring_buffer_lock_reserve(struct ring_buffer *buffer,
112 unsigned long length);
113int ring_buffer_unlock_commit(struct ring_buffer *buffer,
114 struct ring_buffer_event *event);
115int ring_buffer_write(struct ring_buffer *buffer,
116 unsigned long length, void *data);
117
118struct ring_buffer_event *
119ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts,
120 unsigned long *lost_events);
121struct ring_buffer_event *
122ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts,
123 unsigned long *lost_events);
124
125struct ring_buffer_iter *
126ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu);
127void ring_buffer_read_prepare_sync(void);
128void ring_buffer_read_start(struct ring_buffer_iter *iter);
129void ring_buffer_read_finish(struct ring_buffer_iter *iter);
130
131struct ring_buffer_event *
132ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
133struct ring_buffer_event *
134ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts);
135void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
136int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
137
138unsigned long ring_buffer_size(struct ring_buffer *buffer, int cpu);
139
140void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu);
141void ring_buffer_reset(struct ring_buffer *buffer);
142
143#ifdef CONFIG_RING_BUFFER_ALLOW_SWAP
144int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
145 struct ring_buffer *buffer_b, int cpu);
146#else
147static inline int
148ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
149 struct ring_buffer *buffer_b, int cpu)
150{
151 return -ENODEV;
152}
153#endif
154
155bool ring_buffer_empty(struct ring_buffer *buffer);
156bool ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu);
157
158void ring_buffer_record_disable(struct ring_buffer *buffer);
159void ring_buffer_record_enable(struct ring_buffer *buffer);
160void ring_buffer_record_off(struct ring_buffer *buffer);
161void ring_buffer_record_on(struct ring_buffer *buffer);
162int ring_buffer_record_is_on(struct ring_buffer *buffer);
163void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu);
164void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu);
165
166u64 ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu);
167unsigned long ring_buffer_bytes_cpu(struct ring_buffer *buffer, int cpu);
168unsigned long ring_buffer_entries(struct ring_buffer *buffer);
169unsigned long ring_buffer_overruns(struct ring_buffer *buffer);
170unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu);
171unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu);
172unsigned long ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu);
173unsigned long ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu);
174unsigned long ring_buffer_read_events_cpu(struct ring_buffer *buffer, int cpu);
175
176u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu);
177void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer,
178 int cpu, u64 *ts);
179void ring_buffer_set_clock(struct ring_buffer *buffer,
180 u64 (*clock)(void));
181
182size_t ring_buffer_page_len(void *page);
183
184
185void *ring_buffer_alloc_read_page(struct ring_buffer *buffer, int cpu);
186void ring_buffer_free_read_page(struct ring_buffer *buffer, int cpu, void *data);
187int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page,
188 size_t len, int cpu, int full);
189
190struct trace_seq;
191
192int ring_buffer_print_entry_header(struct trace_seq *s);
193int ring_buffer_print_page_header(struct trace_seq *s);
194
195enum ring_buffer_flags {
196 RB_FL_OVERWRITE = 1 << 0,
197};
198
199#ifdef CONFIG_RING_BUFFER
200int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node);
201#else
202#define trace_rb_cpu_prepare NULL
203#endif
204
205#endif /* _LINUX_RING_BUFFER_H */