ltt-event-header.c

   1 /*
   2  * ltt/ltt-event-header.c
   3  *
   4  * (C) Copyright 2010 - Mathieu Desnoyers (mathieu.desnoyers@efficios.com)
   5  *
   6  * LTTng event header.
   7  *
   8  * Author:
   9  *      Mathieu Desnoyers (mathieu.desnoyers@efficios.com)
  10  *
  11  * Dual LGPL v2.1/GPL v2 license.
  12  */
  13
  14 #include <linux/module.h>
  15 #include "ltt-tracer.h"
  16
  17 void ltt_write_event_header_slow(const struct lib_ring_buffer_config *config,
  18                                    struct lib_ring_buffer_ctx *ctx,
  19                                    u16 eID, u32 event_size)
  20 {
  21         struct event_header header;
  22         u16 small_size;
  23
  24         switch (ctx->rflags) {
  25         case LTT_RFLAG_ID_SIZE_TSC:
  26                 header.id_time = 29 << LTT_TSC_BITS;
  27                 break;
  28         case LTT_RFLAG_ID_SIZE:
  29                 header.id_time = 30 << LTT_TSC_BITS;
  30                 break;
  31         case LTT_RFLAG_ID:
  32                 header.id_time = 31 << LTT_TSC_BITS;
  33                 break;
  34         default:
  35                 WARN_ON_ONCE(1);
  36                 header.id_time = 0;
  37         }
  38
  39         header.id_time |= (u32)ctx->tsc & LTT_TSC_MASK;
  40         lib_ring_buffer_write(config, ctx, &header, sizeof(header));
  41
  42         switch (ctx->rflags) {
  43         case LTT_RFLAG_ID_SIZE_TSC:
  44                 small_size = (u16)min_t(u32, event_size, LTT_MAX_SMALL_SIZE);
  45                 lib_ring_buffer_write(config, ctx, &eID, sizeof(u16));
  46                 lib_ring_buffer_write(config, ctx, &small_size, sizeof(u16));
  47                 if (small_size == LTT_MAX_SMALL_SIZE)
  48                         lib_ring_buffer_write(config, ctx, &event_size,
  49                                               sizeof(u32));
  50                 lib_ring_buffer_align_ctx(config, ctx, sizeof(u64));
  51                 lib_ring_buffer_write(config, ctx, &ctx->tsc, sizeof(u64));
  52                 break;
  53         case LTT_RFLAG_ID_SIZE:
  54                 small_size = (u16)min_t(u32, event_size, LTT_MAX_SMALL_SIZE);
  55                 lib_ring_buffer_write(config, ctx, &eID, sizeof(u16));
  56                 lib_ring_buffer_write(config, ctx, &small_size, sizeof(u16));
  57                 if (small_size == LTT_MAX_SMALL_SIZE)
  58                         lib_ring_buffer_write(config, ctx, &event_size,
  59                                               sizeof(u32));
  60                 break;
  61         case LTT_RFLAG_ID:
  62                 lib_ring_buffer_write(config, ctx, &eID, sizeof(u16));
  63                 break;
  64         }
  65 }
  66 EXPORT_SYMBOL_GPL(ltt_write_event_header_slow);