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 struct trace_buffer *__ring_buffer_alloc_range(unsigned long size, unsigned flags,
  93                                                int order, unsigned long start,
  94                                                unsigned long range_size,
  95                                                struct lock_class_key *key);
  96
  97 bool ring_buffer_last_boot_delta(struct trace_buffer *buffer, long *text,
  98                                  long *data);
  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)  \
 117 ({                                                                      \
 118         static struct lock_class_key __key;                             \
 119         __ring_buffer_alloc_range((size), (flags), (order), (start),    \
 120                                   (range_size), &__key);                \
 121 })
 122
 123 typedef bool (*ring_buffer_cond_fn)(void *data);
 124 int 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);
 128 void ring_buffer_wake_waiters(struct trace_buffer *buffer, int cpu);
 129
 130 #define RING_BUFFER_ALL_CPUS -1
 131
 132 void ring_buffer_free(struct trace_buffer *buffer);
 133
 134 int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size, int cpu);
 135
 136 void ring_buffer_change_overwrite(struct trace_buffer *buffer, int val);
 137
 138 struct ring_buffer_event *ring_buffer_lock_reserve(struct trace_buffer *buffer,
 139                                                    unsigned long length);
 140 int ring_buffer_unlock_commit(struct trace_buffer *buffer);
 141 int ring_buffer_write(struct trace_buffer *buffer,
 142                       unsigned long length, void *data);
 143
 144 void ring_buffer_nest_start(struct trace_buffer *buffer);
 145 void ring_buffer_nest_end(struct trace_buffer *buffer);
 146
 147 struct ring_buffer_event *
 148 ring_buffer_peek(struct trace_buffer *buffer, int cpu, u64 *ts,
 149                  unsigned long *lost_events);
 150 struct ring_buffer_event *
 151 ring_buffer_consume(struct trace_buffer *buffer, int cpu, u64 *ts,
 152                     unsigned long *lost_events);
 153
 154 struct ring_buffer_iter *
 155 ring_buffer_read_prepare(struct trace_buffer *buffer, int cpu, gfp_t flags);
 156 void ring_buffer_read_prepare_sync(void);
 157 void ring_buffer_read_start(struct ring_buffer_iter *iter);
 158 void ring_buffer_read_finish(struct ring_buffer_iter *iter);
 159
 160 struct ring_buffer_event *
 161 ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
 162 void ring_buffer_iter_advance(struct ring_buffer_iter *iter);
 163 void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
 164 int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
 165 bool ring_buffer_iter_dropped(struct ring_buffer_iter *iter);
 166
 167 unsigned long ring_buffer_size(struct trace_buffer *buffer, int cpu);
 168 unsigned long ring_buffer_max_event_size(struct trace_buffer *buffer);
 169
 170 void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu);
 171 void ring_buffer_reset_online_cpus(struct trace_buffer *buffer);
 172 void ring_buffer_reset(struct trace_buffer *buffer);
 173
 174 #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP
 175 int ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
 176                          struct trace_buffer *buffer_b, int cpu);
 177 #else
 178 static inline int
 179 ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
 180                      struct trace_buffer *buffer_b, int cpu)
 181 {
 182         return -ENODEV;
 183 }
 184 #endif
 185
 186 bool ring_buffer_empty(struct trace_buffer *buffer);
 187 bool ring_buffer_empty_cpu(struct trace_buffer *buffer, int cpu);
 188
 189 void ring_buffer_record_disable(struct trace_buffer *buffer);
 190 void ring_buffer_record_enable(struct trace_buffer *buffer);
 191 void ring_buffer_record_off(struct trace_buffer *buffer);
 192 void ring_buffer_record_on(struct trace_buffer *buffer);
 193 bool ring_buffer_record_is_on(struct trace_buffer *buffer);
 194 bool ring_buffer_record_is_set_on(struct trace_buffer *buffer);
 195 void ring_buffer_record_disable_cpu(struct trace_buffer *buffer, int cpu);
 196 void ring_buffer_record_enable_cpu(struct trace_buffer *buffer, int cpu);
 197
 198 u64 ring_buffer_oldest_event_ts(struct trace_buffer *buffer, int cpu);
 199 unsigned long ring_buffer_bytes_cpu(struct trace_buffer *buffer, int cpu);
 200 unsigned long ring_buffer_entries(struct trace_buffer *buffer);
 201 unsigned long ring_buffer_overruns(struct trace_buffer *buffer);
 202 unsigned long ring_buffer_entries_cpu(struct trace_buffer *buffer, int cpu);
 203 unsigned long ring_buffer_overrun_cpu(struct trace_buffer *buffer, int cpu);
 204 unsigned long ring_buffer_commit_overrun_cpu(struct trace_buffer *buffer, int cpu);
 205 unsigned long ring_buffer_dropped_events_cpu(struct trace_buffer *buffer, int cpu);
 206 unsigned long ring_buffer_read_events_cpu(struct trace_buffer *buffer, int cpu);
 207
 208 u64 ring_buffer_time_stamp(struct trace_buffer *buffer);
 209 void ring_buffer_normalize_time_stamp(struct trace_buffer *buffer,
 210                                       int cpu, u64 *ts);
 211 void ring_buffer_set_clock(struct trace_buffer *buffer,
 212                            u64 (*clock)(void));
 213 void ring_buffer_set_time_stamp_abs(struct trace_buffer *buffer, bool abs);
 214 bool ring_buffer_time_stamp_abs(struct trace_buffer *buffer);
 215
 216 size_t ring_buffer_nr_dirty_pages(struct trace_buffer *buffer, int cpu);
 217
 218 struct buffer_data_read_page;
 219 struct buffer_data_read_page *
 220 ring_buffer_alloc_read_page(struct trace_buffer *buffer, int cpu);
 221 void ring_buffer_free_read_page(struct trace_buffer *buffer, int cpu,
 222                                 struct buffer_data_read_page *page);
 223 int ring_buffer_read_page(struct trace_buffer *buffer,
 224                           struct buffer_data_read_page *data_page,
 225                           size_t len, int cpu, int full);
 226 void *ring_buffer_read_page_data(struct buffer_data_read_page *page);
 227
 228 struct trace_seq;
 229
 230 int ring_buffer_print_entry_header(struct trace_seq *s);
 231 int ring_buffer_print_page_header(struct trace_buffer *buffer, struct trace_seq *s);
 232
 233 int ring_buffer_subbuf_order_get(struct trace_buffer *buffer);
 234 int ring_buffer_subbuf_order_set(struct trace_buffer *buffer, int order);
 235 int ring_buffer_subbuf_size_get(struct trace_buffer *buffer);
 236
 237 enum ring_buffer_flags {
 238         RB_FL_OVERWRITE         = 1 << 0,
 239 };
 240
 241 #ifdef CONFIG_RING_BUFFER
 242 int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node);
 243 #else
 244 #define trace_rb_cpu_prepare    NULL
 245 #endif
 246
 247 int ring_buffer_map(struct trace_buffer *buffer, int cpu,
 248                     struct vm_area_struct *vma);
 249 int ring_buffer_unmap(struct trace_buffer *buffer, int cpu);
 250 int ring_buffer_map_get_reader(struct trace_buffer *buffer, int cpu);
 251 #endif /* _LINUX_RING_BUFFER_H */