+/*
+ * Keep the natural field alignment for _each field_ within this structure if
+ * you ever add/remove a field from this header. Packed attribute is not used
+ * because gcc generates poor code on at least powerpc and mips. Don't ever
+ * let gcc add padding between the structure elements.
+ */
+struct packet_header {
+ uint32_t magic; /*
+ * Trace magic number.
+ * contains endianness information.
+ */
+ uint8_t uuid[16];
+ uint32_t stream_id;
+ uint64_t timestamp_begin; /* Cycle count at subbuffer start */
+ uint64_t timestamp_end; /* Cycle count at subbuffer end */
+ uint32_t content_size; /* Size of data in subbuffer */
+ uint32_t packet_size; /* Subbuffer size (include padding) */
+ uint32_t events_lost; /*
+ * Events lost in this subbuffer since
+ * the beginning of the trace.
+ * (may overflow)
+ */
+#if 0
+ uint64_t start_time_sec; /* NTP-corrected start time */
+ uint64_t start_time_usec;
+ uint64_t start_freq; /*
+ * Frequency at trace start,
+ * used all along the trace.
+ */
+ uint32_t freq_scale; /* Frequency scaling (divisor) */
+#endif //0
+ uint8_t header_end[0]; /* End of header */
+};
+
+
+static inline notrace u64 lib_ring_buffer_clock_read(struct channel *chan)
+{
+ return trace_clock_read64();
+}
+
+/*
+ * record_header_size - Calculate the header size and padding necessary.
+ * @config: ring buffer instance configuration
+ * @chan: channel
+ * @offset: offset in the write buffer
+ * @data_size: size of the payload
+ * @pre_header_padding: padding to add before the header (output)
+ * @rflags: reservation flags
+ * @ctx: reservation context
+ *
+ * Returns the event header size (including padding).
+ *
+ * Important note :
+ * The event header must be 32-bits. The total offset calculated here :
+ *
+ * Alignment of header struct on 32 bits (min arch size, header size)
+ * + sizeof(header struct) (32-bits)
+ * + (opt) u16 (ext. event id)
+ * + (opt) u16 (event_size)
+ * (if event_size == LTT_MAX_SMALL_SIZE, has ext. event size)
+ * + (opt) u32 (ext. event size)
+ * + (opt) u64 full TSC (aligned on min(64-bits, arch size))
+ *
+ * The payload must itself determine its own alignment from the biggest type it
+ * contains.
+ */
+static __inline__
+unsigned char record_header_size(const struct lib_ring_buffer_config *config,
+ struct channel *chan, size_t offset,
+ size_t data_size, size_t *pre_header_padding,
+ unsigned int rflags,
+ struct lib_ring_buffer_ctx *ctx)
+{
+ size_t orig_offset = offset;
+ size_t padding;
+
+ BUILD_BUG_ON(sizeof(struct event_header) != sizeof(u32));
+
+ padding = lib_ring_buffer_align(offset,
+ sizeof(struct event_header));
+ offset += padding;
+ offset += sizeof(struct event_header);
+
+ if (unlikely(rflags)) {
+ switch (rflags) {
+ case LTT_RFLAG_ID_SIZE_TSC:
+ offset += sizeof(u16) + sizeof(u16);
+ if (data_size >= LTT_MAX_SMALL_SIZE)
+ offset += sizeof(u32);
+ offset += lib_ring_buffer_align(offset, sizeof(u64));
+ offset += sizeof(u64);
+ break;
+ case LTT_RFLAG_ID_SIZE:
+ offset += sizeof(u16) + sizeof(u16);
+ if (data_size >= LTT_MAX_SMALL_SIZE)
+ offset += sizeof(u32);
+ break;
+ case LTT_RFLAG_ID:
+ offset += sizeof(u16);
+ break;
+ }
+ }
+
+ *pre_header_padding = padding;
+ return offset - orig_offset;
+}
+
+#include "wrapper/ringbuffer/api.h"
+
+extern
+void ltt_write_event_header_slow(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer_ctx *ctx,
+ u16 eID, u32 event_size);
+
+/*
+ * ltt_write_event_header
+ *
+ * Writes the event header to the offset (already aligned on 32-bits).
+ *
+ * @config: ring buffer instance configuration
+ * @ctx: reservation context
+ * @eID : event ID
+ * @event_size : size of the event, excluding the event header.
+ */
+static __inline__
+void ltt_write_event_header(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer_ctx *ctx,
+ u16 eID, u32 event_size)
+{
+ struct event_header header;
+
+ if (unlikely(ctx->rflags))
+ goto slow_path;
+
+ header.id_time = eID << LTT_TSC_BITS;
+ header.id_time |= (u32)ctx->tsc & LTT_TSC_MASK;
+ lib_ring_buffer_write(config, ctx, &header, sizeof(header));
+
+slow_path:
+ ltt_write_event_header_slow(config, ctx, eID, event_size);
+}
+
+void ltt_write_event_header_slow(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer_ctx *ctx,
+ u16 eID, u32 event_size)
+{
+ struct event_header header;
+ u16 small_size;
+
+ switch (ctx->rflags) {
+ case LTT_RFLAG_ID_SIZE_TSC:
+ header.id_time = 29 << LTT_TSC_BITS;
+ break;
+ case LTT_RFLAG_ID_SIZE:
+ header.id_time = 30 << LTT_TSC_BITS;
+ break;
+ case LTT_RFLAG_ID:
+ header.id_time = 31 << LTT_TSC_BITS;
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ header.id_time = 0;
+ }
+
+ header.id_time |= (u32)ctx->tsc & LTT_TSC_MASK;
+ lib_ring_buffer_write(config, ctx, &header, sizeof(header));
+
+ switch (ctx->rflags) {
+ case LTT_RFLAG_ID_SIZE_TSC:
+ small_size = (u16)min_t(u32, event_size, LTT_MAX_SMALL_SIZE);
+ lib_ring_buffer_write(config, ctx, &eID, sizeof(u16));
+ lib_ring_buffer_write(config, ctx, &small_size, sizeof(u16));
+ if (small_size == LTT_MAX_SMALL_SIZE)
+ lib_ring_buffer_write(config, ctx, &event_size,
+ sizeof(u32));
+ lib_ring_buffer_align_ctx(ctx, sizeof(u64));
+ lib_ring_buffer_write(config, ctx, &ctx->tsc, sizeof(u64));
+ break;
+ case LTT_RFLAG_ID_SIZE:
+ small_size = (u16)min_t(u32, event_size, LTT_MAX_SMALL_SIZE);
+ lib_ring_buffer_write(config, ctx, &eID, sizeof(u16));
+ lib_ring_buffer_write(config, ctx, &small_size, sizeof(u16));
+ if (small_size == LTT_MAX_SMALL_SIZE)
+ lib_ring_buffer_write(config, ctx, &event_size,
+ sizeof(u32));
+ break;
+ case LTT_RFLAG_ID:
+ lib_ring_buffer_write(config, ctx, &eID, sizeof(u16));
+ break;
+ }
+}
+