libust/header-inline.h

   1 #ifndef UST_HEADER_INLINE_H
   2 #define UST_HEADER_INLINE_H
   3
   4 #include "tracercore.h"
   5
   6 /*
   7  * ust_get_header_size
   8  *
   9  * Calculate alignment offset to 32-bits. This is the alignment offset of the
  10  * event header.
  11  *
  12  * Important note :
  13  * The event header must be 32-bits. The total offset calculated here :
  14  *
  15  * Alignment of header struct on 32 bits (min arch size, header size)
  16  * + sizeof(header struct)  (32-bits)
  17  * + (opt) u16 (ext. event id)
  18  * + (opt) u16 (event_size) (if event_size == 0xFFFFUL, has ext. event size)
  19  * + (opt) u32 (ext. event size)
  20  * + (opt) u64 full TSC (aligned on min(64-bits, arch size))
  21  *
  22  * The payload must itself determine its own alignment from the biggest type it
  23  * contains.
  24  * */
  25 static __inline__ unsigned char ust_get_header_size(
  26                 struct ust_channel *channel,
  27                 size_t offset,
  28                 size_t data_size,
  29                 size_t *before_hdr_pad,
  30                 unsigned int rflags)
  31 {
  32         size_t orig_offset = offset;
  33         size_t padding;
  34
  35         padding = ltt_align(offset, sizeof(struct ltt_event_header));
  36         offset += padding;
  37         offset += sizeof(struct ltt_event_header);
  38
  39         if(unlikely(rflags)) {
  40                 switch (rflags) {
  41                 case LTT_RFLAG_ID_SIZE_TSC:
  42                         offset += sizeof(u16) + sizeof(u16);
  43                         if (data_size >= 0xFFFFU)
  44                                 offset += sizeof(u32);
  45                         offset += ltt_align(offset, sizeof(u64));
  46                         offset += sizeof(u64);
  47                         break;
  48                 case LTT_RFLAG_ID_SIZE:
  49                         offset += sizeof(u16) + sizeof(u16);
  50                         if (data_size >= 0xFFFFU)
  51                                 offset += sizeof(u32);
  52                         break;
  53                 case LTT_RFLAG_ID:
  54                         offset += sizeof(u16);
  55                         break;
  56                 }
  57         }
  58
  59         *before_hdr_pad = padding;
  60         return offset - orig_offset;
  61 }
  62
  63 #endif /* UST_HEADER_INLINE_H */