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 #include <uapi/linux/trace_mmap.h>
  10
  11 struct trace_buffer;
  12 struct ring_buffer_iter;
  13
  14 /*
  15  * Don't refer to this struct directly, use functions below.
  16  */
  17 struct 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  */
  57 enum 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
  64 unsigned ring_buffer_event_length(struct ring_buffer_event *event);
  65 void *ring_buffer_event_data(struct ring_buffer_event *event);
  66 u64 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  */
  83 void 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  */
  89 struct trace_buffer *
  90 __ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key);
  91
  92 /*
  93  * Because the ring buffer is generic, if other users of the ring buffer get
  94  * traced by ftrace, it can produce lockdep warnings. We need to keep each
  95  * ring buffer's lock class separate.
  96  */
  97 #define ring_buffer_alloc(size, flags)                  \
  98 ({                                                      \
  99         static struct lock_class_key __key;             \
 100         __ring_buffer_alloc((size), (flags), &__key);   \
 101 })
 102
 103 typedef bool (*ring_buffer_cond_fn)(void *data);
 104 int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full,
 105                      ring_buffer_cond_fn cond, void *data);
 106 __poll_t ring_buffer_poll_wait(struct trace_buffer *buffer, int cpu,
 107                           struct file *filp, poll_table *poll_table, int full);
 108 void ring_buffer_wake_waiters(struct trace_buffer *buffer, int cpu);
 109
 110 #define RING_BUFFER_ALL_CPUS -1
 111
 112 void ring_buffer_free(struct trace_buffer *buffer);
 113
 114 int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size, int cpu);
 115
 116 void ring_buffer_change_overwrite(struct trace_buffer *buffer, int val);
 117
 118 struct ring_buffer_event *ring_buffer_lock_reserve(struct trace_buffer *buffer,
 119                                                    unsigned long length);
 120 int ring_buffer_unlock_commit(struct trace_buffer *buffer);
 121 int ring_buffer_write(struct trace_buffer *buffer,
 122                       unsigned long length, void *data);
 123
 124 void ring_buffer_nest_start(struct trace_buffer *buffer);
 125 void ring_buffer_nest_end(struct trace_buffer *buffer);
 126
 127 struct ring_buffer_event *
 128 ring_buffer_peek(struct trace_buffer *buffer, int cpu, u64 *ts,
 129                  unsigned long *lost_events);
 130 struct ring_buffer_event *
 131 ring_buffer_consume(struct trace_buffer *buffer, int cpu, u64 *ts,
 132                     unsigned long *lost_events);
 133
 134 struct ring_buffer_iter *
 135 ring_buffer_read_prepare(struct trace_buffer *buffer, int cpu, gfp_t flags);
 136 void ring_buffer_read_prepare_sync(void);
 137 void ring_buffer_read_start(struct ring_buffer_iter *iter);
 138 void ring_buffer_read_finish(struct ring_buffer_iter *iter);
 139
 140 struct ring_buffer_event *
 141 ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
 142 void ring_buffer_iter_advance(struct ring_buffer_iter *iter);
 143 void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
 144 int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
 145 bool ring_buffer_iter_dropped(struct ring_buffer_iter *iter);
 146
 147 unsigned long ring_buffer_size(struct trace_buffer *buffer, int cpu);
 148 unsigned long ring_buffer_max_event_size(struct trace_buffer *buffer);
 149
 150 void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu);
 151 void ring_buffer_reset_online_cpus(struct trace_buffer *buffer);
 152 void ring_buffer_reset(struct trace_buffer *buffer);
 153
 154 #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP
 155 int ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
 156                          struct trace_buffer *buffer_b, int cpu);
 157 #else
 158 static inline int
 159 ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
 160                      struct trace_buffer *buffer_b, int cpu)
 161 {
 162         return -ENODEV;
 163 }
 164 #endif
 165
 166 bool ring_buffer_empty(struct trace_buffer *buffer);
 167 bool ring_buffer_empty_cpu(struct trace_buffer *buffer, int cpu);
 168
 169 void ring_buffer_record_disable(struct trace_buffer *buffer);
 170 void ring_buffer_record_enable(struct trace_buffer *buffer);
 171 void ring_buffer_record_off(struct trace_buffer *buffer);
 172 void ring_buffer_record_on(struct trace_buffer *buffer);
 173 bool ring_buffer_record_is_on(struct trace_buffer *buffer);
 174 bool ring_buffer_record_is_set_on(struct trace_buffer *buffer);
 175 void ring_buffer_record_disable_cpu(struct trace_buffer *buffer, int cpu);
 176 void ring_buffer_record_enable_cpu(struct trace_buffer *buffer, int cpu);
 177
 178 u64 ring_buffer_oldest_event_ts(struct trace_buffer *buffer, int cpu);
 179 unsigned long ring_buffer_bytes_cpu(struct trace_buffer *buffer, int cpu);
 180 unsigned long ring_buffer_entries(struct trace_buffer *buffer);
 181 unsigned long ring_buffer_overruns(struct trace_buffer *buffer);
 182 unsigned long ring_buffer_entries_cpu(struct trace_buffer *buffer, int cpu);
 183 unsigned long ring_buffer_overrun_cpu(struct trace_buffer *buffer, int cpu);
 184 unsigned long ring_buffer_commit_overrun_cpu(struct trace_buffer *buffer, int cpu);
 185 unsigned long ring_buffer_dropped_events_cpu(struct trace_buffer *buffer, int cpu);
 186 unsigned long ring_buffer_read_events_cpu(struct trace_buffer *buffer, int cpu);
 187
 188 u64 ring_buffer_time_stamp(struct trace_buffer *buffer);
 189 void ring_buffer_normalize_time_stamp(struct trace_buffer *buffer,
 190                                       int cpu, u64 *ts);
 191 void ring_buffer_set_clock(struct trace_buffer *buffer,
 192                            u64 (*clock)(void));
 193 void ring_buffer_set_time_stamp_abs(struct trace_buffer *buffer, bool abs);
 194 bool ring_buffer_time_stamp_abs(struct trace_buffer *buffer);
 195
 196 size_t ring_buffer_nr_pages(struct trace_buffer *buffer, int cpu);
 197 size_t ring_buffer_nr_dirty_pages(struct trace_buffer *buffer, int cpu);
 198
 199 struct buffer_data_read_page;
 200 struct buffer_data_read_page *
 201 ring_buffer_alloc_read_page(struct trace_buffer *buffer, int cpu);
 202 void ring_buffer_free_read_page(struct trace_buffer *buffer, int cpu,
 203                                 struct buffer_data_read_page *page);
 204 int ring_buffer_read_page(struct trace_buffer *buffer,
 205                           struct buffer_data_read_page *data_page,
 206                           size_t len, int cpu, int full);
 207 void *ring_buffer_read_page_data(struct buffer_data_read_page *page);
 208
 209 struct trace_seq;
 210
 211 int ring_buffer_print_entry_header(struct trace_seq *s);
 212 int ring_buffer_print_page_header(struct trace_buffer *buffer, struct trace_seq *s);
 213
 214 int ring_buffer_subbuf_order_get(struct trace_buffer *buffer);
 215 int ring_buffer_subbuf_order_set(struct trace_buffer *buffer, int order);
 216 int ring_buffer_subbuf_size_get(struct trace_buffer *buffer);
 217
 218 enum ring_buffer_flags {
 219         RB_FL_OVERWRITE         = 1 << 0,
 220 };
 221
 222 #ifdef CONFIG_RING_BUFFER
 223 int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node);
 224 #else
 225 #define trace_rb_cpu_prepare    NULL
 226 #endif
 227
 228 int ring_buffer_map(struct trace_buffer *buffer, int cpu,
 229                     struct vm_area_struct *vma);
 230 int ring_buffer_unmap(struct trace_buffer *buffer, int cpu);
 231 int ring_buffer_map_get_reader(struct trace_buffer *buffer, int cpu);
 232 #endif /* _LINUX_RING_BUFFER_H */