| 1 | /** |
| 2 | * ltt-type-serializer.c |
| 3 | * |
| 4 | * LTTng specialized type serializer. |
| 5 | * |
| 6 | * Copyright Mathieu Desnoyers, 2008. |
| 7 | * |
| 8 | * Dual LGPL v2.1/GPL v2 license. |
| 9 | */ |
| 10 | #include <linux/module.h> |
| 11 | |
| 12 | #include "ltt-type-serializer.h" |
| 13 | #include "ltt-relay-lockless.h" |
| 14 | |
| 15 | notrace |
| 16 | void _ltt_specialized_trace(void *probe_data, |
| 17 | void *serialize_private, unsigned int data_size, |
| 18 | unsigned int largest_align) |
| 19 | { |
| 20 | struct ltt_event *event = probe_data; |
| 21 | int ret; |
| 22 | uint16_t eID; |
| 23 | size_t slot_size; |
| 24 | struct ltt_chanbuf *buf; |
| 25 | struct ltt_channel *chan; |
| 26 | struct ltt_session *session; |
| 27 | uint64_t tsc; |
| 28 | long buf_offset; |
| 29 | int cpu; |
| 30 | unsigned int rflags; |
| 31 | |
| 32 | /* disabled from tracepoints rcu_read_lock_sched_notrace(); */ |
| 33 | cpu = smp_processor_id(); |
| 34 | __get_cpu_var(ltt_nesting)++; |
| 35 | /* |
| 36 | * asm volatile and "memory" clobber prevent the compiler from moving |
| 37 | * instructions out of the ltt nesting count. This is required to ensure |
| 38 | * that probe side-effects which can cause recursion (e.g. unforeseen |
| 39 | * traps, divisions by 0, ...) are triggered within the incremented |
| 40 | * nesting count section. |
| 41 | */ |
| 42 | barrier(); |
| 43 | eID = event->id; |
| 44 | chan = event->chan; |
| 45 | session = chan->session; |
| 46 | |
| 47 | if (unlikely(!session->active)) |
| 48 | goto skip; |
| 49 | if (unlikely(!ltt_run_filter(session, chan, event))) |
| 50 | goto skip; |
| 51 | #ifdef LTT_DEBUG_EVENT_SIZE |
| 52 | rflags = LTT_RFLAG_ID_SIZE; |
| 53 | #else |
| 54 | if (unlikely(eID >= LTT_FREE_EVENTS)) |
| 55 | rflags = LTT_RFLAG_ID; |
| 56 | else |
| 57 | rflags = 0; |
| 58 | #endif |
| 59 | /* reserve space : header and data */ |
| 60 | ret = ltt_reserve_slot(chan, trace, data_size, largest_align, |
| 61 | cpu, &buf, &slot_size, &buf_offset, &tsc, |
| 62 | &rflags); |
| 63 | if (unlikely(ret < 0)) |
| 64 | goto skip; /* buffer full */ |
| 65 | |
| 66 | /* Out-of-order write : header and data */ |
| 67 | buf_offset = ltt_write_event_header(&buf->a, &chan->a, |
| 68 | buf_offset, eID, data_size, |
| 69 | tsc, rflags); |
| 70 | if (data_size) { |
| 71 | buf_offset += ltt_align(buf_offset, largest_align); |
| 72 | ltt_relay_write(&buf->a, &chan->a, buf_offset, |
| 73 | serialize_private, data_size); |
| 74 | buf_offset += data_size; |
| 75 | } |
| 76 | /* Out-of-order commit */ |
| 77 | ltt_commit_slot(buf, chan, buf_offset, data_size, slot_size); |
| 78 | skip: |
| 79 | /* |
| 80 | * asm volatile and "memory" clobber prevent the compiler from moving |
| 81 | * instructions out of the ltt nesting count. This is required to ensure |
| 82 | * that probe side-effects which can cause recursion (e.g. unforeseen |
| 83 | * traps, divisions by 0, ...) are triggered within the incremented |
| 84 | * nesting count section. |
| 85 | */ |
| 86 | barrier(); |
| 87 | __get_cpu_var(ltt_nesting)--; |
| 88 | /* disabled from tracepoints rcu_read_unlock_sched_notrace(); */ |
| 89 | } |
| 90 | EXPORT_SYMBOL_GPL(_ltt_specialized_trace); |
| 91 | |
| 92 | MODULE_LICENSE("GPL and additional rights"); |
| 93 | MODULE_AUTHOR("Mathieu Desnoyers"); |
| 94 | MODULE_DESCRIPTION("LTT type serializer"); |