include/linux/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 struct ring_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  *   ben 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 ring_buffer *buffer,
  81                                 struct ring_buffer_event *event);
  82
  83 /*
  84  * size is in bytes for each per CPU buffer.
  85  */
  86 struct ring_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 ring_buffer *buffer, int cpu, bool full);
 101 __poll_t ring_buffer_poll_wait(struct ring_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 ring_buffer *buffer);
 108
 109 int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size, int cpu);
 110
 111 void ring_buffer_change_overwrite(struct ring_buffer *buffer, int val);
 112
 113 struct ring_buffer_event *ring_buffer_lock_reserve(struct ring_buffer *buffer,
 114                                                    unsigned long length);
 115 int ring_buffer_unlock_commit(struct ring_buffer *buffer,
 116                               struct ring_buffer_event *event);
 117 int ring_buffer_write(struct ring_buffer *buffer,
 118                       unsigned long length, void *data);
 119
 120 void ring_buffer_nest_start(struct ring_buffer *buffer);
 121 void ring_buffer_nest_end(struct ring_buffer *buffer);
 122
 123 struct ring_buffer_event *
 124 ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts,
 125                  unsigned long *lost_events);
 126 struct ring_buffer_event *
 127 ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts,
 128                     unsigned long *lost_events);
 129
 130 struct ring_buffer_iter *
 131 ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu);
 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 struct ring_buffer_event *
 139 ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts);
 140 void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
 141 int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
 142
 143 unsigned long ring_buffer_size(struct ring_buffer *buffer, int cpu);
 144
 145 void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu);
 146 void ring_buffer_reset(struct ring_buffer *buffer);
 147
 148 #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP
 149 int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
 150                          struct ring_buffer *buffer_b, int cpu);
 151 #else
 152 static inline int
 153 ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
 154                      struct ring_buffer *buffer_b, int cpu)
 155 {
 156         return -ENODEV;
 157 }
 158 #endif
 159
 160 bool ring_buffer_empty(struct ring_buffer *buffer);
 161 bool ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu);
 162
 163 void ring_buffer_record_disable(struct ring_buffer *buffer);
 164 void ring_buffer_record_enable(struct ring_buffer *buffer);
 165 void ring_buffer_record_off(struct ring_buffer *buffer);
 166 void ring_buffer_record_on(struct ring_buffer *buffer);
 167 int ring_buffer_record_is_on(struct ring_buffer *buffer);
 168 void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu);
 169 void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu);
 170
 171 u64 ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu);
 172 unsigned long ring_buffer_bytes_cpu(struct ring_buffer *buffer, int cpu);
 173 unsigned long ring_buffer_entries(struct ring_buffer *buffer);
 174 unsigned long ring_buffer_overruns(struct ring_buffer *buffer);
 175 unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu);
 176 unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu);
 177 unsigned long ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu);
 178 unsigned long ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu);
 179 unsigned long ring_buffer_read_events_cpu(struct ring_buffer *buffer, int cpu);
 180
 181 u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu);
 182 void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer,
 183                                       int cpu, u64 *ts);
 184 void ring_buffer_set_clock(struct ring_buffer *buffer,
 185                            u64 (*clock)(void));
 186 void ring_buffer_set_time_stamp_abs(struct ring_buffer *buffer, bool abs);
 187 bool ring_buffer_time_stamp_abs(struct ring_buffer *buffer);
 188
 189 size_t ring_buffer_page_len(void *page);
 190
 191
 192 void *ring_buffer_alloc_read_page(struct ring_buffer *buffer, int cpu);
 193 void ring_buffer_free_read_page(struct ring_buffer *buffer, int cpu, void *data);
 194 int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page,
 195                           size_t len, int cpu, int full);
 196
 197 struct trace_seq;
 198
 199 int ring_buffer_print_entry_header(struct trace_seq *s);
 200 int ring_buffer_print_page_header(struct trace_seq *s);
 201
 202 enum ring_buffer_flags {
 203         RB_FL_OVERWRITE         = 1 << 0,
 204 };
 205
 206 #ifdef CONFIG_RING_BUFFER
 207 int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node);
 208 #else
 209 #define trace_rb_cpu_prepare    NULL
 210 #endif
 211
 212 #endif /* _LINUX_RING_BUFFER_H */