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/poll.h>
7 #include <linux/ring_buffer_types.h>
8 #include <linux/seq_file.h>
9
10 #include <uapi/linux/trace_mmap.h>
11
12 struct trace_buffer;
13 struct ring_buffer_iter;
14
15 /*
16 * Don't refer to this struct directly, use functions below.
17 */
18 struct ring_buffer_event {
19 u32 type_len:5, time_delta:27;
20
21 u32 array[];
22 };
23
24 /**
25 * enum ring_buffer_type - internal ring buffer types
26 *
27 * @RINGBUF_TYPE_PADDING: Left over page padding or discarded event
28 * If time_delta is 0:
29 * array is ignored
30 * size is variable depending on how much
31 * padding is needed
32 * If time_delta is non zero:
33 * array[0] holds the actual length
34 * size = 4 + length (bytes)
35 *
36 * @RINGBUF_TYPE_TIME_EXTEND: Extend the time delta
37 * array[0] = time delta (28 .. 59)
38 * size = 8 bytes
39 *
40 * @RINGBUF_TYPE_TIME_STAMP: Absolute timestamp
41 * Same format as TIME_EXTEND except that the
42 * value is an absolute timestamp, not a delta
43 * event.time_delta contains bottom 27 bits
44 * array[0] = top (28 .. 59) bits
45 * size = 8 bytes
46 *
47 * <= @RINGBUF_TYPE_DATA_TYPE_LEN_MAX:
48 * Data record
49 * If type_len is zero:
50 * array[0] holds the actual length
51 * array[1..(length+3)/4] holds data
52 * size = 4 + length (bytes)
53 * else
54 * length = type_len << 2
55 * array[0..(length+3)/4-1] holds data
56 * size = 4 + length (bytes)
57 */
58 enum ring_buffer_type {
59 RINGBUF_TYPE_DATA_TYPE_LEN_MAX = 28,
60 RINGBUF_TYPE_PADDING,
61 RINGBUF_TYPE_TIME_EXTEND,
62 RINGBUF_TYPE_TIME_STAMP,
63 };
64
65 unsigned ring_buffer_event_length(struct ring_buffer_event *event);
66 void *ring_buffer_event_data(struct ring_buffer_event *event);
67 u64 ring_buffer_event_time_stamp(struct trace_buffer *buffer,
68 struct ring_buffer_event *event);
69
70 /*
71 * ring_buffer_discard_commit will remove an event that has not
72 * been committed yet. If this is used, then ring_buffer_unlock_commit
73 * must not be called on the discarded event. This function
74 * will try to remove the event from the ring buffer completely
75 * if another event has not been written after it.
76 *
77 * Example use:
78 *
79 * if (some_condition)
80 * ring_buffer_discard_commit(buffer, event);
81 * else
82 * ring_buffer_unlock_commit(buffer, event);
83 */
84 void ring_buffer_discard_commit(struct trace_buffer *buffer,
85 struct ring_buffer_event *event);
86
87 /*
88 * size is in bytes for each per CPU buffer.
89 */
90 struct trace_buffer *
91 __ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key);
92
93 struct trace_buffer *__ring_buffer_alloc_range(unsigned long size, unsigned flags,
94 int order, unsigned long start,
95 unsigned long range_size,
96 unsigned long scratch_size,
97 struct lock_class_key *key);
98
99 void *ring_buffer_meta_scratch(struct trace_buffer *buffer, unsigned int *size);
100
101 /*
102 * Because the ring buffer is generic, if other users of the ring buffer get
103 * traced by ftrace, it can produce lockdep warnings. We need to keep each
104 * ring buffer's lock class separate.
105 */
106 #define ring_buffer_alloc(size, flags) \
107 ({ \
108 static struct lock_class_key __key; \
109 __ring_buffer_alloc((size), (flags), &__key); \
110 })
111
112 /*
113 * Because the ring buffer is generic, if other users of the ring buffer get
114 * traced by ftrace, it can produce lockdep warnings. We need to keep each
115 * ring buffer's lock class separate.
116 */
117 #define ring_buffer_alloc_range(size, flags, order, start, range_size, s_size) \
118 ({ \
119 static struct lock_class_key __key; \
120 __ring_buffer_alloc_range((size), (flags), (order), (start), \
121 (range_size), (s_size), &__key); \
122 })
123
124 typedef bool (*ring_buffer_cond_fn)(void *data);
125 int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full,
126 ring_buffer_cond_fn cond, void *data);
127 __poll_t ring_buffer_poll_wait(struct trace_buffer *buffer, int cpu,
128 struct file *filp, poll_table *poll_table, int full);
129 void ring_buffer_wake_waiters(struct trace_buffer *buffer, int cpu);
130
131 #define RING_BUFFER_ALL_CPUS -1
132
133 void ring_buffer_free(struct trace_buffer *buffer);
134
135 int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size, int cpu);
136
137 void ring_buffer_change_overwrite(struct trace_buffer *buffer, int val);
138
139 struct ring_buffer_event *ring_buffer_lock_reserve(struct trace_buffer *buffer,
140 unsigned long length);
141 int ring_buffer_unlock_commit(struct trace_buffer *buffer);
142 int ring_buffer_write(struct trace_buffer *buffer,
143 unsigned long length, void *data);
144
145 void ring_buffer_nest_start(struct trace_buffer *buffer);
146 void ring_buffer_nest_end(struct trace_buffer *buffer);
147
148 DEFINE_GUARD(ring_buffer_nest, struct trace_buffer *,
149 ring_buffer_nest_start(_T), ring_buffer_nest_end(_T))
150
151 struct ring_buffer_event *
152 ring_buffer_peek(struct trace_buffer *buffer, int cpu, u64 *ts,
153 unsigned long *lost_events);
154 struct ring_buffer_event *
155 ring_buffer_consume(struct trace_buffer *buffer, int cpu, u64 *ts,
156 unsigned long *lost_events);
157
158 struct ring_buffer_iter *
159 ring_buffer_read_start(struct trace_buffer *buffer, int cpu, gfp_t flags);
160 void ring_buffer_read_finish(struct ring_buffer_iter *iter);
161
162 struct ring_buffer_event *
163 ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
164 void ring_buffer_iter_advance(struct ring_buffer_iter *iter);
165 void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
166 int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
167 bool ring_buffer_iter_dropped(struct ring_buffer_iter *iter);
168
169 unsigned long ring_buffer_size(struct trace_buffer *buffer, int cpu);
170 unsigned long ring_buffer_max_event_size(struct trace_buffer *buffer);
171
172 void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu);
173 void ring_buffer_reset_online_cpus(struct trace_buffer *buffer);
174 void ring_buffer_reset(struct trace_buffer *buffer);
175
176 #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP
177 int ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
178 struct trace_buffer *buffer_b, int cpu);
179 #else
180 static inline int
ring_buffer_swap_cpu(struct trace_buffer * buffer_a,struct trace_buffer * buffer_b,int cpu)181 ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
182 struct trace_buffer *buffer_b, int cpu)
183 {
184 return -ENODEV;
185 }
186 #endif
187
188 bool ring_buffer_empty(struct trace_buffer *buffer);
189 bool ring_buffer_empty_cpu(struct trace_buffer *buffer, int cpu);
190
191 void ring_buffer_record_disable(struct trace_buffer *buffer);
192 void ring_buffer_record_enable(struct trace_buffer *buffer);
193 void ring_buffer_record_off(struct trace_buffer *buffer);
194 void ring_buffer_record_on(struct trace_buffer *buffer);
195 bool ring_buffer_record_is_on(struct trace_buffer *buffer);
196 bool ring_buffer_record_is_set_on(struct trace_buffer *buffer);
197 bool ring_buffer_record_is_on_cpu(struct trace_buffer *buffer, int cpu);
198 void ring_buffer_record_disable_cpu(struct trace_buffer *buffer, int cpu);
199 void ring_buffer_record_enable_cpu(struct trace_buffer *buffer, int cpu);
200
201 u64 ring_buffer_oldest_event_ts(struct trace_buffer *buffer, int cpu);
202 unsigned long ring_buffer_bytes_cpu(struct trace_buffer *buffer, int cpu);
203 unsigned long ring_buffer_entries(struct trace_buffer *buffer);
204 unsigned long ring_buffer_overruns(struct trace_buffer *buffer);
205 unsigned long ring_buffer_entries_cpu(struct trace_buffer *buffer, int cpu);
206 unsigned long ring_buffer_overrun_cpu(struct trace_buffer *buffer, int cpu);
207 unsigned long ring_buffer_commit_overrun_cpu(struct trace_buffer *buffer, int cpu);
208 unsigned long ring_buffer_dropped_events_cpu(struct trace_buffer *buffer, int cpu);
209 unsigned long ring_buffer_read_events_cpu(struct trace_buffer *buffer, int cpu);
210
211 u64 ring_buffer_time_stamp(struct trace_buffer *buffer);
212 void ring_buffer_normalize_time_stamp(struct trace_buffer *buffer,
213 int cpu, u64 *ts);
214 void ring_buffer_set_clock(struct trace_buffer *buffer,
215 u64 (*clock)(void));
216 void ring_buffer_set_time_stamp_abs(struct trace_buffer *buffer, bool abs);
217 bool ring_buffer_time_stamp_abs(struct trace_buffer *buffer);
218
219 size_t ring_buffer_nr_dirty_pages(struct trace_buffer *buffer, int cpu);
220
221 struct buffer_data_read_page;
222 int ring_buffer_alloc_read_page(struct trace_buffer *buffer, int cpu,
223 struct buffer_data_read_page **rpage);
224 void ring_buffer_free_read_page(struct trace_buffer *buffer, int cpu,
225 struct buffer_data_read_page *page);
226 int ring_buffer_read_page(struct trace_buffer *buffer,
227 struct buffer_data_read_page *data_page,
228 size_t len, int cpu, int full);
229 void *ring_buffer_read_page_data(struct buffer_data_read_page *page);
230 unsigned int ring_buffer_read_page_size(struct buffer_data_read_page *rpage);
231
232 struct trace_seq;
233
234 int ring_buffer_print_entry_header(struct trace_seq *s);
235 int ring_buffer_print_page_header(struct trace_buffer *buffer, struct trace_seq *s);
236
237 int ring_buffer_subbuf_order_get(struct trace_buffer *buffer);
238 int ring_buffer_subbuf_order_set(struct trace_buffer *buffer, int order);
239 int ring_buffer_subbuf_size_get(struct trace_buffer *buffer);
240
241 enum ring_buffer_flags {
242 RB_FL_OVERWRITE = 1 << 0,
243 RB_FL_TESTING = 1 << 1,
244 };
245
246 #ifdef CONFIG_RING_BUFFER
247 int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node);
248 #else
249 #define trace_rb_cpu_prepare NULL
250 #endif
251
252 int ring_buffer_map(struct trace_buffer *buffer, int cpu,
253 struct vm_area_struct *vma);
254 void ring_buffer_map_dup(struct trace_buffer *buffer, int cpu);
255 int ring_buffer_unmap(struct trace_buffer *buffer, int cpu);
256 int ring_buffer_map_get_reader(struct trace_buffer *buffer, int cpu);
257
258 struct ring_buffer_desc {
259 int cpu;
260 unsigned int nr_page_va; /* excludes the meta page */
261 unsigned long meta_va;
262 unsigned long page_va[] __counted_by(nr_page_va);
263 };
264
265 struct trace_buffer_desc {
266 int nr_cpus;
267 size_t struct_len;
268 char __data[]; /* list of ring_buffer_desc */
269 };
270
__next_ring_buffer_desc(struct ring_buffer_desc * desc)271 static inline struct ring_buffer_desc *__next_ring_buffer_desc(struct ring_buffer_desc *desc)
272 {
273 size_t len = struct_size(desc, page_va, desc->nr_page_va);
274
275 return (struct ring_buffer_desc *)((void *)desc + len);
276 }
277
__first_ring_buffer_desc(struct trace_buffer_desc * desc)278 static inline struct ring_buffer_desc *__first_ring_buffer_desc(struct trace_buffer_desc *desc)
279 {
280 return (struct ring_buffer_desc *)(&desc->__data[0]);
281 }
282
283 /*
284 * Returns the number of pages for a ring_buffer_desc. The caller must ensure it
285 * does not overflow ring_buffer_desc::nr_page_va.
286 */
__calc_nr_pages_ring_buffer_desc(size_t size)287 static inline unsigned long __calc_nr_pages_ring_buffer_desc(size_t size)
288 {
289 /* Takes into account the reader page */
290 return max(DIV_ROUND_UP(size, PAGE_SIZE - BUF_PAGE_HDR_SIZE), 2UL) + 1;
291 }
292
trace_buffer_desc_size(size_t buffer_size,unsigned int nr_cpus)293 static inline size_t trace_buffer_desc_size(size_t buffer_size, unsigned int nr_cpus)
294 {
295 unsigned long nr_pages = __calc_nr_pages_ring_buffer_desc(buffer_size);
296 struct ring_buffer_desc *rbdesc;
297
298 /* Capped by ring_buffer_desc::nr_page_va */
299 if (nr_pages > UINT_MAX)
300 return SIZE_MAX;
301
302 return size_add(offsetof(struct trace_buffer_desc, __data),
303 size_mul(nr_cpus, struct_size(rbdesc, page_va, nr_pages)));
304 }
305
306 #define for_each_ring_buffer_desc(__pdesc, __cpu, __trace_pdesc) \
307 for (__pdesc = __first_ring_buffer_desc(__trace_pdesc), __cpu = 0; \
308 (__cpu) < (__trace_pdesc)->nr_cpus; \
309 (__cpu)++, __pdesc = __next_ring_buffer_desc(__pdesc))
310
311 struct ring_buffer_remote {
312 struct trace_buffer_desc *desc;
313 int (*swap_reader_page)(unsigned int cpu, void *priv);
314 int (*reset)(unsigned int cpu, void *priv);
315 void *priv;
316 };
317
318 int ring_buffer_poll_remote(struct trace_buffer *buffer, int cpu);
319
320 struct trace_buffer *
321 __ring_buffer_alloc_remote(struct ring_buffer_remote *remote,
322 struct lock_class_key *key);
323
324 #define ring_buffer_alloc_remote(remote) \
325 ({ \
326 static struct lock_class_key __key; \
327 __ring_buffer_alloc_remote(remote, &__key); \
328 })
329 #endif /* _LINUX_RING_BUFFER_H */
330