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/kmemcheck.h>
   6 #include <linux/mm.h>
   7 #include <linux/seq_file.h>
   8 #include <linux/poll.h>
   9
  10 struct ring_buffer;
  11 struct ring_buffer_iter;
  12
  13 /*
  14  * Don't refer to this struct directly, use functions below.
  15  */
  16 struct ring_buffer_event {
  17         kmemcheck_bitfield_begin(bitfield);
  18         u32             type_len:5, time_delta:27;
  19         kmemcheck_bitfield_end(bitfield);
  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:    Sync time stamp with external clock
  41  *                               array[0]    = tv_nsec
  42  *                               array[1..2] = tv_sec
  43  *                               size = 16 bytes
  44  *
  45  * <= @RINGBUF_TYPE_DATA_TYPE_LEN_MAX:
  46  *                              Data record
  47  *                               If type_len is zero:
  48  *                                array[0] holds the actual length
  49  *                                array[1..(length+3)/4] holds data
  50  *                                size = 4 + length (bytes)
  51  *                               else
  52  *                                length = type_len << 2
  53  *                                array[0..(length+3)/4-1] holds data
  54  *                                size = 4 + length (bytes)
  55  */
  56 enum ring_buffer_type {
  57         RINGBUF_TYPE_DATA_TYPE_LEN_MAX = 28,
  58         RINGBUF_TYPE_PADDING,
  59         RINGBUF_TYPE_TIME_EXTEND,
  60         /* FIXME: RINGBUF_TYPE_TIME_STAMP not implemented */
  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
  67 /*
  68  * ring_buffer_discard_commit will remove an event that has not
  69  *   ben committed yet. If this is used, then ring_buffer_unlock_commit
  70  *   must not be called on the discarded event. This function
  71  *   will try to remove the event from the ring buffer completely
  72  *   if another event has not been written after it.
  73  *
  74  * Example use:
  75  *
  76  *  if (some_condition)
  77  *    ring_buffer_discard_commit(buffer, event);
  78  *  else
  79  *    ring_buffer_unlock_commit(buffer, event);
  80  */
  81 void ring_buffer_discard_commit(struct ring_buffer *buffer,
  82                                 struct ring_buffer_event *event);
  83
  84 /*
  85  * size is in bytes for each per CPU buffer.
  86  */
  87 struct ring_buffer *
  88 __ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key);
  89
  90 /*
  91  * Because the ring buffer is generic, if other users of the ring buffer get
  92  * traced by ftrace, it can produce lockdep warnings. We need to keep each
  93  * ring buffer's lock class separate.
  94  */
  95 #define ring_buffer_alloc(size, flags)                  \
  96 ({                                                      \
  97         static struct lock_class_key __key;             \
  98         __ring_buffer_alloc((size), (flags), &__key);   \
  99 })
 100
 101 int ring_buffer_wait(struct ring_buffer *buffer, int cpu, bool full);
 102 int ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu,
 103                           struct file *filp, poll_table *poll_table);
 104
 105
 106 #define RING_BUFFER_ALL_CPUS -1
 107
 108 void ring_buffer_free(struct ring_buffer *buffer);
 109
 110 int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size, int cpu);
 111
 112 void ring_buffer_change_overwrite(struct ring_buffer *buffer, int val);
 113
 114 struct ring_buffer_event *ring_buffer_lock_reserve(struct ring_buffer *buffer,
 115                                                    unsigned long length);
 116 int ring_buffer_unlock_commit(struct ring_buffer *buffer,
 117                               struct ring_buffer_event *event);
 118 int ring_buffer_write(struct ring_buffer *buffer,
 119                       unsigned long length, void *data);
 120
 121 struct ring_buffer_event *
 122 ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts,
 123                  unsigned long *lost_events);
 124 struct ring_buffer_event *
 125 ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts,
 126                     unsigned long *lost_events);
 127
 128 struct ring_buffer_iter *
 129 ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu);
 130 void ring_buffer_read_prepare_sync(void);
 131 void ring_buffer_read_start(struct ring_buffer_iter *iter);
 132 void ring_buffer_read_finish(struct ring_buffer_iter *iter);
 133
 134 struct ring_buffer_event *
 135 ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
 136 struct ring_buffer_event *
 137 ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts);
 138 void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
 139 int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
 140
 141 unsigned long ring_buffer_size(struct ring_buffer *buffer, int cpu);
 142
 143 void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu);
 144 void ring_buffer_reset(struct ring_buffer *buffer);
 145
 146 #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP
 147 int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
 148                          struct ring_buffer *buffer_b, int cpu);
 149 #else
 150 static inline int
 151 ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
 152                      struct ring_buffer *buffer_b, int cpu)
 153 {
 154         return -ENODEV;
 155 }
 156 #endif
 157
 158 bool ring_buffer_empty(struct ring_buffer *buffer);
 159 bool ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu);
 160
 161 void ring_buffer_record_disable(struct ring_buffer *buffer);
 162 void ring_buffer_record_enable(struct ring_buffer *buffer);
 163 void ring_buffer_record_off(struct ring_buffer *buffer);
 164 void ring_buffer_record_on(struct ring_buffer *buffer);
 165 int ring_buffer_record_is_on(struct ring_buffer *buffer);
 166 void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu);
 167 void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu);
 168
 169 u64 ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu);
 170 unsigned long ring_buffer_bytes_cpu(struct ring_buffer *buffer, int cpu);
 171 unsigned long ring_buffer_entries(struct ring_buffer *buffer);
 172 unsigned long ring_buffer_overruns(struct ring_buffer *buffer);
 173 unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu);
 174 unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu);
 175 unsigned long ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu);
 176 unsigned long ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu);
 177 unsigned long ring_buffer_read_events_cpu(struct ring_buffer *buffer, int cpu);
 178
 179 u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu);
 180 void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer,
 181                                       int cpu, u64 *ts);
 182 void ring_buffer_set_clock(struct ring_buffer *buffer,
 183                            u64 (*clock)(void));
 184
 185 size_t ring_buffer_page_len(void *page);
 186
 187
 188 void *ring_buffer_alloc_read_page(struct ring_buffer *buffer, int cpu);
 189 void ring_buffer_free_read_page(struct ring_buffer *buffer, int cpu, void *data);
 190 int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page,
 191                           size_t len, int cpu, int full);
 192
 193 struct trace_seq;
 194
 195 int ring_buffer_print_entry_header(struct trace_seq *s);
 196 int ring_buffer_print_page_header(struct trace_seq *s);
 197
 198 enum ring_buffer_flags {
 199         RB_FL_OVERWRITE         = 1 << 0,
 200 };
 201
 202 #ifdef CONFIG_RING_BUFFER
 203 int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node);
 204 #else
 205 #define trace_rb_cpu_prepare    NULL
 206 #endif
 207
 208 #endif /* _LINUX_RING_BUFFER_H */