+}
+
+/*
+ * We have exclusive access to our metadata buffer (protected by the
+ * sessions_mutex), so we can do racy operations such as looking for
+ * remaining space left in packet and write, since mutual exclusion
+ * protects us from concurrent writes.
+ */
+int lttng_metadata_printf(struct ltt_session *session,
+ const char *fmt, ...)
+{
+ struct lib_ring_buffer_ctx ctx;
+ struct ltt_channel *chan = session->metadata;
+ char *str;
+ int ret = 0, waitret;
+ size_t len, reserve_len, pos;
+ va_list ap;
+
+ WARN_ON_ONCE(!ACCESS_ONCE(session->active));
+
+ va_start(ap, fmt);
+ str = kvasprintf(GFP_KERNEL, fmt, ap);
+ va_end(ap);
+ if (!str)
+ return -ENOMEM;
+
+ len = strlen(str);
+ pos = 0;
+
+ for (pos = 0; pos < len; pos += reserve_len) {
+ reserve_len = min_t(size_t,
+ chan->ops->packet_avail_size(chan->chan),
+ len - pos);
+ lib_ring_buffer_ctx_init(&ctx, chan->chan, NULL, reserve_len,
+ sizeof(char), -1);
+ /*
+ * We don't care about metadata buffer's records lost
+ * count, because we always retry here. Report error if
+ * we need to bail out after timeout or being
+ * interrupted.
+ */
+ waitret = wait_event_interruptible_timeout(*chan->ops->get_reader_wait_queue(chan),
+ ({
+ ret = chan->ops->event_reserve(&ctx, 0);
+ ret != -ENOBUFS || !ret;
+ }),
+ msecs_to_jiffies(LTTNG_METADATA_TIMEOUT_MSEC));
+ if (!waitret || waitret == -ERESTARTSYS || ret) {
+ printk(KERN_WARNING "LTTng: Failure to write metadata to buffers (%s)\n",
+ waitret == -ERESTARTSYS ? "interrupted" :
+ (ret == -ENOBUFS ? "timeout" : "I/O error"));
+ if (waitret == -ERESTARTSYS)
+ ret = waitret;
+ goto end;
+ }
+ chan->ops->event_write(&ctx, &str[pos], len);
+ chan->ops->event_commit(&ctx);
+ }
+end:
+ kfree(str);
+ return ret;
+}
+
+static
+int _ltt_field_statedump(struct ltt_session *session,
+ const struct lttng_event_field *field)
+{
+ int ret = 0;
+
+ switch (field->type.atype) {
+ case atype_integer:
+ ret = lttng_metadata_printf(session,
+ " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } %s;\n",
+ field->type.u.basic.integer.size,
+ field->type.u.basic.integer.alignment,
+ field->type.u.basic.integer.signedness,
+ (field->type.u.basic.integer.encoding == lttng_encode_none)
+ ? "none"
+ : (field->type.u.basic.integer.encoding == lttng_encode_UTF8)
+ ? "UTF8"
+ : "ASCII",
+ field->type.u.basic.integer.base,
+#ifdef __BIG_ENDIAN
+ field->type.u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
+#else
+ field->type.u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
+#endif
+ field->name);
+ break;
+ case atype_enum:
+ ret = lttng_metadata_printf(session,
+ " %s %s;\n",
+ field->type.u.basic.enumeration.name,
+ field->name);
+ break;
+ case atype_array:
+ {
+ const struct lttng_basic_type *elem_type;
+
+ elem_type = &field->type.u.array.elem_type;
+ ret = lttng_metadata_printf(session,
+ " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } %s[%u];\n",
+ elem_type->u.basic.integer.size,
+ elem_type->u.basic.integer.alignment,
+ elem_type->u.basic.integer.signedness,
+ (elem_type->u.basic.integer.encoding == lttng_encode_none)
+ ? "none"
+ : (elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
+ ? "UTF8"
+ : "ASCII",
+ elem_type->u.basic.integer.base,
+#ifdef __BIG_ENDIAN
+ elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
+#else
+ elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
+#endif
+ field->name, field->type.u.array.length);
+ break;
+ }
+ case atype_sequence:
+ {
+ const struct lttng_basic_type *elem_type;
+ const struct lttng_basic_type *length_type;
+
+ elem_type = &field->type.u.sequence.elem_type;
+ length_type = &field->type.u.sequence.length_type;
+ ret = lttng_metadata_printf(session,
+ " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } __%s_length;\n",
+ length_type->u.basic.integer.size,
+ (unsigned int) length_type->u.basic.integer.alignment,
+ length_type->u.basic.integer.signedness,
+ (length_type->u.basic.integer.encoding == lttng_encode_none)
+ ? "none"
+ : ((length_type->u.basic.integer.encoding == lttng_encode_UTF8)
+ ? "UTF8"
+ : "ASCII"),
+ length_type->u.basic.integer.base,
+#ifdef __BIG_ENDIAN
+ length_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
+#else
+ length_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
+#endif
+ field->name);
+ if (ret)
+ return ret;
+
+ ret = lttng_metadata_printf(session,
+ " integer { size = %u; align = %u; signed = %u; encoding = %s; base = %u;%s } %s[ __%s_length ];\n",
+ elem_type->u.basic.integer.size,
+ (unsigned int) elem_type->u.basic.integer.alignment,
+ elem_type->u.basic.integer.signedness,
+ (elem_type->u.basic.integer.encoding == lttng_encode_none)
+ ? "none"
+ : ((elem_type->u.basic.integer.encoding == lttng_encode_UTF8)
+ ? "UTF8"
+ : "ASCII"),
+ elem_type->u.basic.integer.base,
+#ifdef __BIG_ENDIAN
+ elem_type->u.basic.integer.reverse_byte_order ? " byte_order = le;" : "",
+#else
+ elem_type->u.basic.integer.reverse_byte_order ? " byte_order = be;" : "",
+#endif
+ field->name,
+ field->name);
+ break;
+ }
+
+ case atype_string:
+ /* Default encoding is UTF8 */
+ ret = lttng_metadata_printf(session,
+ " string%s %s;\n",
+ field->type.u.basic.string.encoding == lttng_encode_ASCII ?
+ " { encoding = ASCII; }" : "",
+ field->name);
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ return -EINVAL;
+ }
+ return ret;
+}
+
+static
+int _ltt_context_metadata_statedump(struct ltt_session *session,
+ struct lttng_ctx *ctx)
+{
+ int ret = 0;
+ int i;
+
+ if (!ctx)
+ return 0;
+ for (i = 0; i < ctx->nr_fields; i++) {
+ const struct lttng_ctx_field *field = &ctx->fields[i];
+
+ ret = _ltt_field_statedump(session, &field->event_field);
+ if (ret)
+ return ret;
+ }
+ return ret;
+}
+
+static
+int _ltt_fields_metadata_statedump(struct ltt_session *session,
+ struct ltt_event *event)
+{
+ const struct lttng_event_desc *desc = event->desc;
+ int ret = 0;
+ int i;
+
+ for (i = 0; i < desc->nr_fields; i++) {
+ const struct lttng_event_field *field = &desc->fields[i];
+
+ ret = _ltt_field_statedump(session, field);
+ if (ret)
+ return ret;
+ }
+ return ret;
+}
+
+static
+int _ltt_event_metadata_statedump(struct ltt_session *session,
+ struct ltt_channel *chan,
+ struct ltt_event *event)
+{
+ int ret = 0;
+
+ if (event->metadata_dumped || !ACCESS_ONCE(session->active))
+ return 0;
+ if (chan == session->metadata)
+ return 0;
+
+ ret = lttng_metadata_printf(session,
+ "event {\n"
+ " name = %s;\n"
+ " id = %u;\n"
+ " stream_id = %u;\n",
+ event->desc->name,
+ event->id,
+ event->chan->id);
+ if (ret)
+ goto end;
+
+ if (event->ctx) {
+ ret = lttng_metadata_printf(session,
+ " context := struct {\n");
+ if (ret)
+ goto end;
+ }
+ ret = _ltt_context_metadata_statedump(session, event->ctx);
+ if (ret)
+ goto end;
+ if (event->ctx) {
+ ret = lttng_metadata_printf(session,
+ " };\n");
+ if (ret)
+ goto end;
+ }
+
+ ret = lttng_metadata_printf(session,
+ " fields := struct {\n"
+ );
+ if (ret)
+ goto end;
+
+ ret = _ltt_fields_metadata_statedump(session, event);
+ if (ret)
+ goto end;
+
+ /*
+ * LTTng space reservation can only reserve multiples of the
+ * byte size.
+ */
+ ret = lttng_metadata_printf(session,
+ " };\n"
+ "};\n\n");
+ if (ret)
+ goto end;
+
+ event->metadata_dumped = 1;
+end:
+ return ret;
+
+}
+
+static
+int _ltt_channel_metadata_statedump(struct ltt_session *session,
+ struct ltt_channel *chan)
+{
+ int ret = 0;
+
+ if (chan->metadata_dumped || !ACCESS_ONCE(session->active))
+ return 0;
+ if (chan == session->metadata)
+ return 0;
+
+ WARN_ON_ONCE(!chan->header_type);
+ ret = lttng_metadata_printf(session,
+ "stream {\n"
+ " id = %u;\n"
+ " event.header := %s;\n"
+ " packet.context := struct packet_context;\n",
+ chan->id,
+ chan->header_type == 1 ? "struct event_header_compact" :
+ "struct event_header_large");
+ if (ret)
+ goto end;
+
+ if (chan->ctx) {
+ ret = lttng_metadata_printf(session,
+ " event.context := struct {\n");
+ if (ret)
+ goto end;
+ }
+ ret = _ltt_context_metadata_statedump(session, chan->ctx);
+ if (ret)
+ goto end;
+ if (chan->ctx) {
+ ret = lttng_metadata_printf(session,
+ " };\n");
+ if (ret)
+ goto end;
+ }
+
+ ret = lttng_metadata_printf(session,
+ "};\n\n");
+
+ chan->metadata_dumped = 1;
+end:
+ return ret;
+}
+
+static
+int _ltt_stream_packet_context_declare(struct ltt_session *session)
+{
+ return lttng_metadata_printf(session,
+ "struct packet_context {\n"
+ " uint64_t timestamp_begin;\n"
+ " uint64_t timestamp_end;\n"
+ " uint32_t events_discarded;\n"
+ " uint32_t content_size;\n"
+ " uint32_t packet_size;\n"
+ " uint32_t cpu_id;\n"
+ "};\n\n"
+ );
+}
+
+/*
+ * Compact header:
+ * id: range: 0 - 30.
+ * id 31 is reserved to indicate an extended header.
+ *
+ * Large header:
+ * id: range: 0 - 65534.
+ * id 65535 is reserved to indicate an extended header.
+ */
+static
+int _ltt_event_header_declare(struct ltt_session *session)
+{
+ return lttng_metadata_printf(session,
+ "struct event_header_compact {\n"
+ " enum : uint5_t { compact = 0 ... 30, extended = 31 } id;\n"
+ " variant <id> {\n"
+ " struct {\n"
+ " uint27_t timestamp;\n"
+ " } compact;\n"
+ " struct {\n"
+ " uint32_t id;\n"
+ " uint64_t timestamp;\n"
+ " } extended;\n"
+ " } v;\n"
+ "} align(%u);\n"
+ "\n"
+ "struct event_header_large {\n"
+ " enum : uint16_t { compact = 0 ... 65534, extended = 65535 } id;\n"
+ " variant <id> {\n"
+ " struct {\n"
+ " uint32_t timestamp;\n"
+ " } compact;\n"
+ " struct {\n"
+ " uint32_t id;\n"
+ " uint64_t timestamp;\n"
+ " } extended;\n"
+ " } v;\n"
+ "} align(%u);\n\n",
+ ltt_alignof(uint32_t) * CHAR_BIT,
+ ltt_alignof(uint16_t) * CHAR_BIT
+ );
+}
+
+/*
+ * Output metadata into this session's metadata buffers.
+ */
+static
+int _ltt_session_metadata_statedump(struct ltt_session *session)
+{
+ unsigned char *uuid_c = session->uuid.b;
+ unsigned char uuid_s[37];
+ struct ltt_channel *chan;
+ struct ltt_event *event;
+ int ret = 0;
+
+ if (!ACCESS_ONCE(session->active))
+ return 0;
+ if (session->metadata_dumped)
+ goto skip_session;
+ if (!session->metadata) {
+ printk(KERN_WARNING "LTTng: attempt to start tracing, but metadata channel is not found. Operation abort.\n");
+ return -EPERM;
+ }
+
+ snprintf(uuid_s, sizeof(uuid_s),
+ "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
+ uuid_c[0], uuid_c[1], uuid_c[2], uuid_c[3],
+ uuid_c[4], uuid_c[5], uuid_c[6], uuid_c[7],
+ uuid_c[8], uuid_c[9], uuid_c[10], uuid_c[11],
+ uuid_c[12], uuid_c[13], uuid_c[14], uuid_c[15]);
+
+ ret = lttng_metadata_printf(session,
+ "typealias integer { size = 8; align = %u; signed = false; } := uint8_t;\n"
+ "typealias integer { size = 16; align = %u; signed = false; } := uint16_t;\n"
+ "typealias integer { size = 32; align = %u; signed = false; } := uint32_t;\n"
+ "typealias integer { size = 64; align = %u; signed = false; } := uint64_t;\n"
+ "typealias integer { size = 5; align = 1; signed = false; } := uint5_t;\n"
+ "typealias integer { size = 27; align = 1; signed = false; } := uint27_t;\n"
+ "\n"
+ "trace {\n"
+ " major = %u;\n"
+ " minor = %u;\n"
+ " uuid = \"%s\";\n"
+ " byte_order = %s;\n"
+ " packet.header := struct {\n"
+ " uint32_t magic;\n"
+ " uint8_t uuid[16];\n"
+ " uint32_t stream_id;\n"
+ " };\n"
+ "};\n\n",
+ ltt_alignof(uint8_t) * CHAR_BIT,
+ ltt_alignof(uint16_t) * CHAR_BIT,
+ ltt_alignof(uint32_t) * CHAR_BIT,
+ ltt_alignof(uint64_t) * CHAR_BIT,
+ CTF_VERSION_MAJOR,
+ CTF_VERSION_MINOR,
+ uuid_s,
+#ifdef __BIG_ENDIAN
+ "be"
+#else
+ "le"
+#endif
+ );
+ if (ret)
+ goto end;
+
+ ret = _ltt_stream_packet_context_declare(session);
+ if (ret)
+ goto end;
+
+ ret = _ltt_event_header_declare(session);
+ if (ret)
+ goto end;
+
+skip_session:
+ list_for_each_entry(chan, &session->chan, list) {
+ ret = _ltt_channel_metadata_statedump(session, chan);
+ if (ret)
+ goto end;
+ }
+
+ list_for_each_entry(event, &session->events, list) {
+ ret = _ltt_event_metadata_statedump(session, event->chan, event);
+ if (ret)
+ goto end;
+ }
+ session->metadata_dumped = 1;
+end: