ring_buffer.h

  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
147DEFINE_GUARD(ring_buffer_nest, struct trace_buffer *,
148	     ring_buffer_nest_start(_T), ring_buffer_nest_end(_T))
149
150struct ring_buffer_event *
151ring_buffer_peek(struct trace_buffer *buffer, int cpu, u64 *ts,
152		 unsigned long *lost_events);
153struct ring_buffer_event *
154ring_buffer_consume(struct trace_buffer *buffer, int cpu, u64 *ts,
155		    unsigned long *lost_events);
156
157struct ring_buffer_iter *
158ring_buffer_read_start(struct trace_buffer *buffer, int cpu, gfp_t flags);
159void ring_buffer_read_finish(struct ring_buffer_iter *iter);
160
161struct ring_buffer_event *
162ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
163void ring_buffer_iter_advance(struct ring_buffer_iter *iter);
164void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
165int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
166bool ring_buffer_iter_dropped(struct ring_buffer_iter *iter);
167
168unsigned long ring_buffer_size(struct trace_buffer *buffer, int cpu);
169unsigned long ring_buffer_max_event_size(struct trace_buffer *buffer);
170
171void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu);
172void ring_buffer_reset_online_cpus(struct trace_buffer *buffer);
173void ring_buffer_reset(struct trace_buffer *buffer);
174
175#ifdef CONFIG_RING_BUFFER_ALLOW_SWAP
176int ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
177			 struct trace_buffer *buffer_b, int cpu);
178#else
179static inline int
180ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
181		     struct trace_buffer *buffer_b, int cpu)
182{
183	return -ENODEV;
184}
185#endif
186
187bool ring_buffer_empty(struct trace_buffer *buffer);
188bool ring_buffer_empty_cpu(struct trace_buffer *buffer, int cpu);
189
190void ring_buffer_record_disable(struct trace_buffer *buffer);
191void ring_buffer_record_enable(struct trace_buffer *buffer);
192void ring_buffer_record_off(struct trace_buffer *buffer);
193void ring_buffer_record_on(struct trace_buffer *buffer);
194bool ring_buffer_record_is_on(struct trace_buffer *buffer);
195bool ring_buffer_record_is_set_on(struct trace_buffer *buffer);
196bool ring_buffer_record_is_on_cpu(struct trace_buffer *buffer, int cpu);
197void ring_buffer_record_disable_cpu(struct trace_buffer *buffer, int cpu);
198void ring_buffer_record_enable_cpu(struct trace_buffer *buffer, int cpu);
199
200u64 ring_buffer_oldest_event_ts(struct trace_buffer *buffer, int cpu);
201unsigned long ring_buffer_bytes_cpu(struct trace_buffer *buffer, int cpu);
202unsigned long ring_buffer_entries(struct trace_buffer *buffer);
203unsigned long ring_buffer_overruns(struct trace_buffer *buffer);
204unsigned long ring_buffer_entries_cpu(struct trace_buffer *buffer, int cpu);
205unsigned long ring_buffer_overrun_cpu(struct trace_buffer *buffer, int cpu);
206unsigned long ring_buffer_commit_overrun_cpu(struct trace_buffer *buffer, int cpu);
207unsigned long ring_buffer_dropped_events_cpu(struct trace_buffer *buffer, int cpu);
208unsigned long ring_buffer_read_events_cpu(struct trace_buffer *buffer, int cpu);
209
210u64 ring_buffer_time_stamp(struct trace_buffer *buffer);
211void ring_buffer_normalize_time_stamp(struct trace_buffer *buffer,
212				      int cpu, u64 *ts);
213void ring_buffer_set_clock(struct trace_buffer *buffer,
214			   u64 (*clock)(void));
215void ring_buffer_set_time_stamp_abs(struct trace_buffer *buffer, bool abs);
216bool ring_buffer_time_stamp_abs(struct trace_buffer *buffer);
217
218size_t ring_buffer_nr_dirty_pages(struct trace_buffer *buffer, int cpu);
219
220struct buffer_data_read_page;
221struct buffer_data_read_page *
222ring_buffer_alloc_read_page(struct trace_buffer *buffer, int cpu);
223void ring_buffer_free_read_page(struct trace_buffer *buffer, int cpu,
224				struct buffer_data_read_page *page);
225int ring_buffer_read_page(struct trace_buffer *buffer,
226			  struct buffer_data_read_page *data_page,
227			  size_t len, int cpu, int full);
228void *ring_buffer_read_page_data(struct buffer_data_read_page *page);
229
230struct trace_seq;
231
232int ring_buffer_print_entry_header(struct trace_seq *s);
233int ring_buffer_print_page_header(struct trace_buffer *buffer, struct trace_seq *s);
234
235int ring_buffer_subbuf_order_get(struct trace_buffer *buffer);
236int ring_buffer_subbuf_order_set(struct trace_buffer *buffer, int order);
237int ring_buffer_subbuf_size_get(struct trace_buffer *buffer);
238
239enum ring_buffer_flags {
240	RB_FL_OVERWRITE		= 1 << 0,
241};
242
243#ifdef CONFIG_RING_BUFFER
244int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node);
245#else
246#define trace_rb_cpu_prepare	NULL
247#endif
248
249int ring_buffer_map(struct trace_buffer *buffer, int cpu,
250		    struct vm_area_struct *vma);
251void ring_buffer_map_dup(struct trace_buffer *buffer, int cpu);
252int ring_buffer_unmap(struct trace_buffer *buffer, int cpu);
253int ring_buffer_map_get_reader(struct trace_buffer *buffer, int cpu);
254#endif /* _LINUX_RING_BUFFER_H */