lttng: tracer control and core structures

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/lttng/ltt-endian.h

@@ -0,0 +1,31 @@
+#ifndef _LTT_ENDIAN_H
+#define _LTT_ENDIAN_H
+
+/*
+ * ltt-endian.h
+ *
+ * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#ifdef __KERNEL__
+# include <asm/byteorder.h>
+# ifdef __BIG_ENDIAN
+#  define __BYTE_ORDER __BIG_ENDIAN
+# elif defined(__LITTLE_ENDIAN)
+#  define __BYTE_ORDER __LITTLE_ENDIAN
+# else
+#  error "unknown endianness"
+# endif
+#ifndef __BIG_ENDIAN
+# define __BIG_ENDIAN 4321
+#endif
+#ifndef __LITTLE_ENDIAN
+# define __LITTLE_ENDIAN 1234
+#endif
+#else
+# include <endian.h>
+#endif
+
+#endif /* _LTT_ENDIAN_H */

drivers/staging/lttng/ltt-events.c

@@ -0,0 +1,1009 @@
+/*
+ * ltt-events.c
+ *
+ * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Holds LTTng per-session event registry.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/jiffies.h>
+#include "wrapper/uuid.h"
+#include "wrapper/vmalloc.h"	/* for wrapper_vmalloc_sync_all() */
+#include "ltt-events.h"
+#include "ltt-tracer.h"
+
+static LIST_HEAD(sessions);
+static LIST_HEAD(ltt_transport_list);
+static DEFINE_MUTEX(sessions_mutex);
+static struct kmem_cache *event_cache;
+
+static void _ltt_event_destroy(struct ltt_event *event);
+static void _ltt_channel_destroy(struct ltt_channel *chan);
+static int _ltt_event_unregister(struct ltt_event *event);
+static
+int _ltt_event_metadata_statedump(struct ltt_session *session,
+				  struct ltt_channel *chan,
+				  struct ltt_event *event);
+static
+int _ltt_session_metadata_statedump(struct ltt_session *session);
+
+void synchronize_trace(void)
+{
+	synchronize_sched();
+#ifdef CONFIG_PREEMPT_RT
+	synchronize_rcu();
+#endif
+}
+
+struct ltt_session *ltt_session_create(void)
+{
+	struct ltt_session *session;
+
+	mutex_lock(&sessions_mutex);
+	session = kzalloc(sizeof(struct ltt_session), GFP_KERNEL);
+	if (!session)
+		return NULL;
+	INIT_LIST_HEAD(&session->chan);
+	INIT_LIST_HEAD(&session->events);
+	uuid_le_gen(&session->uuid);
+	list_add(&session->list, &sessions);
+	mutex_unlock(&sessions_mutex);
+	return session;
+}
+
+void ltt_session_destroy(struct ltt_session *session)
+{
+	struct ltt_channel *chan, *tmpchan;
+	struct ltt_event *event, *tmpevent;
+	int ret;
+
+	mutex_lock(&sessions_mutex);
+	ACCESS_ONCE(session->active) = 0;
+	list_for_each_entry(chan, &session->chan, list) {
+		ret = lttng_syscalls_unregister(chan);
+		WARN_ON(ret);
+	}
+	list_for_each_entry(event, &session->events, list) {
+		ret = _ltt_event_unregister(event);
+		WARN_ON(ret);
+	}
+	synchronize_trace();	/* Wait for in-flight events to complete */
+	list_for_each_entry_safe(event, tmpevent, &session->events, list)
+		_ltt_event_destroy(event);
+	list_for_each_entry_safe(chan, tmpchan, &session->chan, list)
+		_ltt_channel_destroy(chan);
+	list_del(&session->list);
+	mutex_unlock(&sessions_mutex);
+	kfree(session);
+}
+
+int ltt_session_enable(struct ltt_session *session)
+{
+	int ret = 0;
+	struct ltt_channel *chan;
+
+	mutex_lock(&sessions_mutex);
+	if (session->active) {
+		ret = -EBUSY;
+		goto end;
+	}
+
+	/*
+	 * Snapshot the number of events per channel to know the type of header
+	 * we need to use.
+	 */
+	list_for_each_entry(chan, &session->chan, list) {
+		if (chan->header_type)
+			continue;		/* don't change it if session stop/restart */
+		if (chan->free_event_id < 31)
+			chan->header_type = 1;	/* compact */
+		else
+			chan->header_type = 2;	/* large */
+	}
+
+	ACCESS_ONCE(session->active) = 1;
+	ACCESS_ONCE(session->been_active) = 1;
+	ret = _ltt_session_metadata_statedump(session);
+	if (ret)
+		ACCESS_ONCE(session->active) = 0;
+end:
+	mutex_unlock(&sessions_mutex);
+	return ret;
+}
+
+int ltt_session_disable(struct ltt_session *session)
+{
+	int ret = 0;
+
+	mutex_lock(&sessions_mutex);
+	if (!session->active) {
+		ret = -EBUSY;
+		goto end;
+	}
+	ACCESS_ONCE(session->active) = 0;
+end:
+	mutex_unlock(&sessions_mutex);
+	return ret;
+}
+
+int ltt_channel_enable(struct ltt_channel *channel)
+{
+	int old;
+
+	if (channel == channel->session->metadata)
+		return -EPERM;
+	old = xchg(&channel->enabled, 1);
+	if (old)
+		return -EEXIST;
+	return 0;
+}
+
+int ltt_channel_disable(struct ltt_channel *channel)
+{
+	int old;
+
+	if (channel == channel->session->metadata)
+		return -EPERM;
+	old = xchg(&channel->enabled, 0);
+	if (!old)
+		return -EEXIST;
+	return 0;
+}
+
+int ltt_event_enable(struct ltt_event *event)
+{
+	int old;
+
+	if (event->chan == event->chan->session->metadata)
+		return -EPERM;
+	old = xchg(&event->enabled, 1);
+	if (old)
+		return -EEXIST;
+	return 0;
+}
+
+int ltt_event_disable(struct ltt_event *event)
+{
+	int old;
+
+	if (event->chan == event->chan->session->metadata)
+		return -EPERM;
+	old = xchg(&event->enabled, 0);
+	if (!old)
+		return -EEXIST;
+	return 0;
+}
+
+static struct ltt_transport *ltt_transport_find(const char *name)
+{
+	struct ltt_transport *transport;
+
+	list_for_each_entry(transport, &ltt_transport_list, node) {
+		if (!strcmp(transport->name, name))
+			return transport;
+	}
+	return NULL;
+}
+
+struct ltt_channel *ltt_channel_create(struct ltt_session *session,
+				       const char *transport_name,
+				       void *buf_addr,
+				       size_t subbuf_size, size_t num_subbuf,
+				       unsigned int switch_timer_interval,
+				       unsigned int read_timer_interval)
+{
+	struct ltt_channel *chan;
+	struct ltt_transport *transport = NULL;
+
+	mutex_lock(&sessions_mutex);
+	if (session->been_active)
+		goto active;	/* Refuse to add channel to active session */
+	transport = ltt_transport_find(transport_name);
+	if (!transport) {
+		printk(KERN_WARNING "LTTng transport %s not found\n",
+		       transport_name);
+		goto notransport;
+	}
+	if (!try_module_get(transport->owner)) {
+		printk(KERN_WARNING "LTT : Can't lock transport module.\n");
+		goto notransport;
+	}
+	chan = kzalloc(sizeof(struct ltt_channel), GFP_KERNEL);
+	if (!chan)
+		goto nomem;
+	chan->session = session;
+	chan->id = session->free_chan_id++;
+	/*
+	 * Note: the channel creation op already writes into the packet
+	 * headers. Therefore the "chan" information used as input
+	 * should be already accessible.
+	 */
+	chan->chan = transport->ops.channel_create("[lttng]", chan, buf_addr,
+			subbuf_size, num_subbuf, switch_timer_interval,
+			read_timer_interval);
+	if (!chan->chan)
+		goto create_error;
+	chan->enabled = 1;
+	chan->ops = &transport->ops;
+	chan->transport = transport;
+	list_add(&chan->list, &session->chan);
+	mutex_unlock(&sessions_mutex);
+	return chan;
+
+create_error:
+	kfree(chan);
+nomem:
+	if (transport)
+		module_put(transport->owner);
+notransport:
+active:
+	mutex_unlock(&sessions_mutex);
+	return NULL;
+}
+
+/*
+ * Only used internally at session destruction.
+ */
+static
+void _ltt_channel_destroy(struct ltt_channel *chan)
+{
+	chan->ops->channel_destroy(chan->chan);
+	module_put(chan->transport->owner);
+	list_del(&chan->list);
+	lttng_destroy_context(chan->ctx);
+	kfree(chan);
+}
+
+/*
+ * Supports event creation while tracing session is active.
+ */
+struct ltt_event *ltt_event_create(struct ltt_channel *chan,
+				   struct lttng_kernel_event *event_param,
+				   void *filter,
+				   const struct lttng_event_desc *internal_desc)
+{
+	struct ltt_event *event;
+	int ret;
+
+	mutex_lock(&sessions_mutex);
+	if (chan->free_event_id == -1UL)
+		goto full;
+	/*
+	 * This is O(n^2) (for each event, the loop is called at event
+	 * creation). Might require a hash if we have lots of events.
+	 */
+	list_for_each_entry(event, &chan->session->events, list)
+		if (!strcmp(event->desc->name, event_param->name))
+			goto exist;
+	event = kmem_cache_zalloc(event_cache, GFP_KERNEL);
+	if (!event)
+		goto cache_error;
+	event->chan = chan;
+	event->filter = filter;
+	event->id = chan->free_event_id++;
+	event->enabled = 1;
+	event->instrumentation = event_param->instrumentation;
+	/* Populate ltt_event structure before tracepoint registration. */
+	smp_wmb();
+	switch (event_param->instrumentation) {
+	case LTTNG_KERNEL_TRACEPOINT:
+		event->desc = ltt_event_get(event_param->name);
+		if (!event->desc)
+			goto register_error;
+		ret = tracepoint_probe_register(event_param->name,
+				event->desc->probe_callback,
+				event);
+		if (ret)
+			goto register_error;
+		break;
+	case LTTNG_KERNEL_KPROBE:
+		ret = lttng_kprobes_register(event_param->name,
+				event_param->u.kprobe.symbol_name,
+				event_param->u.kprobe.offset,
+				event_param->u.kprobe.addr,
+				event);
+		if (ret)
+			goto register_error;
+		ret = try_module_get(event->desc->owner);
+		WARN_ON_ONCE(!ret);
+		break;
+	case LTTNG_KERNEL_KRETPROBE:
+	{
+		struct ltt_event *event_return;
+
+		/* kretprobe defines 2 events */
+		event_return =
+			kmem_cache_zalloc(event_cache, GFP_KERNEL);
+		if (!event_return)
+			goto register_error;
+		event_return->chan = chan;
+		event_return->filter = filter;
+		event_return->id = chan->free_event_id++;
+		event_return->enabled = 1;
+		event_return->instrumentation = event_param->instrumentation;
+		/*
+		 * Populate ltt_event structure before kretprobe registration.
+		 */
+		smp_wmb();
+		ret = lttng_kretprobes_register(event_param->name,
+				event_param->u.kretprobe.symbol_name,
+				event_param->u.kretprobe.offset,
+				event_param->u.kretprobe.addr,
+				event, event_return);
+		if (ret) {
+			kmem_cache_free(event_cache, event_return);
+			goto register_error;
+		}
+		/* Take 2 refs on the module: one per event. */
+		ret = try_module_get(event->desc->owner);
+		WARN_ON_ONCE(!ret);
+		ret = try_module_get(event->desc->owner);
+		WARN_ON_ONCE(!ret);
+		ret = _ltt_event_metadata_statedump(chan->session, chan,
+						    event_return);
+		if (ret) {
+			kmem_cache_free(event_cache, event_return);
+			module_put(event->desc->owner);
+			module_put(event->desc->owner);
+			goto statedump_error;
+		}
+		list_add(&event_return->list, &chan->session->events);
+		break;
+	}
+	case LTTNG_KERNEL_FUNCTION:
+		ret = lttng_ftrace_register(event_param->name,
+				event_param->u.ftrace.symbol_name,
+				event);
+		if (ret)
+			goto register_error;
+		ret = try_module_get(event->desc->owner);
+		WARN_ON_ONCE(!ret);
+		break;
+	case LTTNG_KERNEL_NOOP:
+		event->desc = internal_desc;
+		if (!event->desc)
+			goto register_error;
+		break;
+	default:
+		WARN_ON_ONCE(1);
+	}
+	ret = _ltt_event_metadata_statedump(chan->session, chan, event);
+	if (ret)
+		goto statedump_error;
+	list_add(&event->list, &chan->session->events);
+	mutex_unlock(&sessions_mutex);
+	return event;
+
+statedump_error:
+	/* If a statedump error occurs, events will not be readable. */
+register_error:
+	kmem_cache_free(event_cache, event);
+cache_error:
+exist:
+full:
+	mutex_unlock(&sessions_mutex);
+	return NULL;
+}
+
+/*
+ * Only used internally at session destruction.
+ */
+int _ltt_event_unregister(struct ltt_event *event)
+{
+	int ret = -EINVAL;
+
+	switch (event->instrumentation) {
+	case LTTNG_KERNEL_TRACEPOINT:
+		ret = tracepoint_probe_unregister(event->desc->name,
+						  event->desc->probe_callback,
+						  event);
+		if (ret)
+			return ret;
+		break;
+	case LTTNG_KERNEL_KPROBE:
+		lttng_kprobes_unregister(event);
+		ret = 0;
+		break;
+	case LTTNG_KERNEL_KRETPROBE:
+		lttng_kretprobes_unregister(event);
+		ret = 0;
+		break;
+	case LTTNG_KERNEL_FUNCTION:
+		lttng_ftrace_unregister(event);
+		ret = 0;
+		break;
+	case LTTNG_KERNEL_NOOP:
+		ret = 0;
+		break;
+	default:
+		WARN_ON_ONCE(1);
+	}
+	return ret;
+}
+
+/*
+ * Only used internally at session destruction.
+ */
+static
+void _ltt_event_destroy(struct ltt_event *event)
+{
+	switch (event->instrumentation) {
+	case LTTNG_KERNEL_TRACEPOINT:
+		ltt_event_put(event->desc);
+		break;
+	case LTTNG_KERNEL_KPROBE:
+		module_put(event->desc->owner);
+		lttng_kprobes_destroy_private(event);
+		break;
+	case LTTNG_KERNEL_KRETPROBE:
+		module_put(event->desc->owner);
+		lttng_kretprobes_destroy_private(event);
+		break;
+	case LTTNG_KERNEL_FUNCTION:
+		module_put(event->desc->owner);
+		lttng_ftrace_destroy_private(event);
+		break;
+	case LTTNG_KERNEL_NOOP:
+		break;
+	default:
+		WARN_ON_ONCE(1);
+	}
+	list_del(&event->list);
+	lttng_destroy_context(event->ctx);
+	kmem_cache_free(event_cache, event);
+}
+
+/*
+ * 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_writer_buf_wait_queue(chan->chan, -1),
+			({
+				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], reserve_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:
+	return ret;
+}
+
+/**
+ * ltt_transport_register - LTT transport registration
+ * @transport: transport structure
+ *
+ * Registers a transport which can be used as output to extract the data out of
+ * LTTng. The module calling this registration function must ensure that no
+ * trap-inducing code will be executed by the transport functions. E.g.
+ * vmalloc_sync_all() must be called between a vmalloc and the moment the memory
+ * is made visible to the transport function. This registration acts as a
+ * vmalloc_sync_all. Therefore, only if the module allocates virtual memory
+ * after its registration must it synchronize the TLBs.
+ */
+void ltt_transport_register(struct ltt_transport *transport)
+{
+	/*
+	 * Make sure no page fault can be triggered by the module about to be
+	 * registered. We deal with this here so we don't have to call
+	 * vmalloc_sync_all() in each module's init.
+	 */
+	wrapper_vmalloc_sync_all();
+
+	mutex_lock(&sessions_mutex);
+	list_add_tail(&transport->node, &ltt_transport_list);
+	mutex_unlock(&sessions_mutex);
+}
+EXPORT_SYMBOL_GPL(ltt_transport_register);
+
+/**
+ * ltt_transport_unregister - LTT transport unregistration
+ * @transport: transport structure
+ */
+void ltt_transport_unregister(struct ltt_transport *transport)
+{
+	mutex_lock(&sessions_mutex);
+	list_del(&transport->node);
+	mutex_unlock(&sessions_mutex);
+}
+EXPORT_SYMBOL_GPL(ltt_transport_unregister);
+
+static int __init ltt_events_init(void)
+{
+	int ret;
+
+	event_cache = KMEM_CACHE(ltt_event, 0);
+	if (!event_cache)
+		return -ENOMEM;
+	ret = ltt_debugfs_abi_init();
+	if (ret)
+		goto error_abi;
+	return 0;
+error_abi:
+	kmem_cache_destroy(event_cache);
+	return ret;
+}
+
+module_init(ltt_events_init);
+
+static void __exit ltt_events_exit(void)
+{
+	struct ltt_session *session, *tmpsession;
+
+	ltt_debugfs_abi_exit();
+	list_for_each_entry_safe(session, tmpsession, &sessions, list)
+		ltt_session_destroy(session);
+	kmem_cache_destroy(event_cache);
+}
+
+module_exit(ltt_events_exit);
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
+MODULE_DESCRIPTION("LTTng Events");

drivers/staging/lttng/ltt-events.h

@@ -0,0 +1,452 @@
+#ifndef _LTT_EVENTS_H
+#define _LTT_EVENTS_H
+
+/*
+ * ltt-events.h
+ *
+ * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Holds LTTng per-session event registry.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/list.h>
+#include <linux/kprobes.h>
+#include "wrapper/uuid.h"
+#include "ltt-debugfs-abi.h"
+
+#undef is_signed_type
+#define is_signed_type(type)		(((type)(-1)) < 0)
+
+struct ltt_channel;
+struct ltt_session;
+struct lib_ring_buffer_ctx;
+struct perf_event;
+struct perf_event_attr;
+
+/* Type description */
+
+/* Update the astract_types name table in lttng-types.c along with this enum */
+enum abstract_types {
+	atype_integer,
+	atype_enum,
+	atype_array,
+	atype_sequence,
+	atype_string,
+	NR_ABSTRACT_TYPES,
+};
+
+/* Update the string_encodings name table in lttng-types.c along with this enum */
+enum lttng_string_encodings {
+	lttng_encode_none = 0,
+	lttng_encode_UTF8 = 1,
+	lttng_encode_ASCII = 2,
+	NR_STRING_ENCODINGS,
+};
+
+struct lttng_enum_entry {
+	unsigned long long start, end;	/* start and end are inclusive */
+	const char *string;
+};
+
+#define __type_integer(_type, _byte_order, _base, _encoding)	\
+	{							\
+	    .atype = atype_integer,				\
+	    .u.basic.integer =					\
+		{						\
+		  .size = sizeof(_type) * CHAR_BIT,		\
+		  .alignment = ltt_alignof(_type) * CHAR_BIT,	\
+		  .signedness = is_signed_type(_type),		\
+		  .reverse_byte_order = _byte_order != __BYTE_ORDER,	\
+		  .base = _base,				\
+		  .encoding = lttng_encode_##_encoding,		\
+		},						\
+	}							\
+
+struct lttng_integer_type {
+	unsigned int size;		/* in bits */
+	unsigned short alignment;	/* in bits */
+	unsigned int signedness:1;
+	unsigned int reverse_byte_order:1;
+	unsigned int base;		/* 2, 8, 10, 16, for pretty print */
+	enum lttng_string_encodings encoding;
+};
+
+union _lttng_basic_type {
+	struct lttng_integer_type integer;
+	struct {
+		const char *name;
+	} enumeration;
+	struct {
+		enum lttng_string_encodings encoding;
+	} string;
+};
+
+struct lttng_basic_type {
+	enum abstract_types atype;
+	union {
+		union _lttng_basic_type basic;
+	} u;
+};
+
+struct lttng_type {
+	enum abstract_types atype;
+	union {
+		union _lttng_basic_type basic;
+		struct {
+			struct lttng_basic_type elem_type;
+			unsigned int length;		/* num. elems. */
+		} array;
+		struct {
+			struct lttng_basic_type length_type;
+			struct lttng_basic_type elem_type;
+		} sequence;
+	} u;
+};
+
+struct lttng_enum {
+	const char *name;
+	struct lttng_type container_type;
+	const struct lttng_enum_entry *entries;
+	unsigned int len;
+};
+
+/* Event field description */
+
+struct lttng_event_field {
+	const char *name;
+	struct lttng_type type;
+};
+
+/*
+ * We need to keep this perf counter field separately from struct
+ * lttng_ctx_field because cpu hotplug needs fixed-location addresses.
+ */
+struct lttng_perf_counter_field {
+	struct notifier_block nb;
+	int hp_enable;
+	struct perf_event_attr *attr;
+	struct perf_event **e;	/* per-cpu array */
+};
+
+struct lttng_ctx_field {
+	struct lttng_event_field event_field;
+	size_t (*get_size)(size_t offset);
+	void (*record)(struct lttng_ctx_field *field,
+		       struct lib_ring_buffer_ctx *ctx,
+		       struct ltt_channel *chan);
+	union {
+		struct lttng_perf_counter_field *perf_counter;
+	} u;
+	void (*destroy)(struct lttng_ctx_field *field);
+};
+
+struct lttng_ctx {
+	struct lttng_ctx_field *fields;
+	unsigned int nr_fields;
+	unsigned int allocated_fields;
+};
+
+struct lttng_event_desc {
+	const char *name;
+	void *probe_callback;
+	const struct lttng_event_ctx *ctx;	/* context */
+	const struct lttng_event_field *fields;	/* event payload */
+	unsigned int nr_fields;
+	struct module *owner;
+};
+
+struct lttng_probe_desc {
+	const struct lttng_event_desc **event_desc;
+	unsigned int nr_events;
+	struct list_head head;			/* chain registered probes */
+};
+
+struct lttng_krp;				/* Kretprobe handling */
+
+/*
+ * ltt_event structure is referred to by the tracing fast path. It must be
+ * kept small.
+ */
+struct ltt_event {
+	unsigned int id;
+	struct ltt_channel *chan;
+	int enabled;
+	const struct lttng_event_desc *desc;
+	void *filter;
+	struct lttng_ctx *ctx;
+	enum lttng_kernel_instrumentation instrumentation;
+	union {
+		struct {
+			struct kprobe kp;
+			char *symbol_name;
+		} kprobe;
+		struct {
+			struct lttng_krp *lttng_krp;
+			char *symbol_name;
+		} kretprobe;
+		struct {
+			char *symbol_name;
+		} ftrace;
+	} u;
+	struct list_head list;		/* Event list */
+	int metadata_dumped:1;
+};
+
+struct ltt_channel_ops {
+	struct channel *(*channel_create)(const char *name,
+				struct ltt_channel *ltt_chan,
+				void *buf_addr,
+				size_t subbuf_size, size_t num_subbuf,
+				unsigned int switch_timer_interval,
+				unsigned int read_timer_interval);
+	void (*channel_destroy)(struct channel *chan);
+	struct lib_ring_buffer *(*buffer_read_open)(struct channel *chan);
+	int (*buffer_has_read_closed_stream)(struct channel *chan);
+	void (*buffer_read_close)(struct lib_ring_buffer *buf);
+	int (*event_reserve)(struct lib_ring_buffer_ctx *ctx,
+			     uint32_t event_id);
+	void (*event_commit)(struct lib_ring_buffer_ctx *ctx);
+	void (*event_write)(struct lib_ring_buffer_ctx *ctx, const void *src,
+			    size_t len);
+	void (*event_write_from_user)(struct lib_ring_buffer_ctx *ctx,
+				      const void *src, size_t len);
+	void (*event_memset)(struct lib_ring_buffer_ctx *ctx,
+			     int c, size_t len);
+	/*
+	 * packet_avail_size returns the available size in the current
+	 * packet. Note that the size returned is only a hint, since it
+	 * may change due to concurrent writes.
+	 */
+	size_t (*packet_avail_size)(struct channel *chan);
+	wait_queue_head_t *(*get_writer_buf_wait_queue)(struct channel *chan, int cpu);
+	wait_queue_head_t *(*get_hp_wait_queue)(struct channel *chan);
+	int (*is_finalized)(struct channel *chan);
+	int (*is_disabled)(struct channel *chan);
+};
+
+struct ltt_transport {
+	char *name;
+	struct module *owner;
+	struct list_head node;
+	struct ltt_channel_ops ops;
+};
+
+struct ltt_channel {
+	unsigned int id;
+	struct channel *chan;		/* Channel buffers */
+	int enabled;
+	struct lttng_ctx *ctx;
+	/* Event ID management */
+	struct ltt_session *session;
+	struct file *file;		/* File associated to channel */
+	unsigned int free_event_id;	/* Next event ID to allocate */
+	struct list_head list;		/* Channel list */
+	struct ltt_channel_ops *ops;
+	struct ltt_transport *transport;
+	struct ltt_event **sc_table;	/* for syscall tracing */
+	struct ltt_event **compat_sc_table;
+	struct ltt_event *sc_unknown;	/* for unknown syscalls */
+	struct ltt_event *sc_compat_unknown;
+	struct ltt_event *sc_exit;	/* for syscall exit */
+	int header_type;		/* 0: unset, 1: compact, 2: large */
+	int metadata_dumped:1;
+};
+
+struct ltt_session {
+	int active;			/* Is trace session active ? */
+	int been_active;		/* Has trace session been active ? */
+	struct file *file;		/* File associated to session */
+	struct ltt_channel *metadata;	/* Metadata channel */
+	struct list_head chan;		/* Channel list head */
+	struct list_head events;	/* Event list head */
+	struct list_head list;		/* Session list */
+	unsigned int free_chan_id;	/* Next chan ID to allocate */
+	uuid_le uuid;			/* Trace session unique ID */
+	int metadata_dumped:1;
+};
+
+struct ltt_session *ltt_session_create(void);
+int ltt_session_enable(struct ltt_session *session);
+int ltt_session_disable(struct ltt_session *session);
+void ltt_session_destroy(struct ltt_session *session);
+
+struct ltt_channel *ltt_channel_create(struct ltt_session *session,
+				       const char *transport_name,
+				       void *buf_addr,
+				       size_t subbuf_size, size_t num_subbuf,
+				       unsigned int switch_timer_interval,
+				       unsigned int read_timer_interval);
+struct ltt_channel *ltt_global_channel_create(struct ltt_session *session,
+				       int overwrite, void *buf_addr,
+				       size_t subbuf_size, size_t num_subbuf,
+				       unsigned int switch_timer_interval,
+				       unsigned int read_timer_interval);
+
+struct ltt_event *ltt_event_create(struct ltt_channel *chan,
+				   struct lttng_kernel_event *event_param,
+				   void *filter,
+				   const struct lttng_event_desc *internal_desc);
+
+int ltt_channel_enable(struct ltt_channel *channel);
+int ltt_channel_disable(struct ltt_channel *channel);
+int ltt_event_enable(struct ltt_event *event);
+int ltt_event_disable(struct ltt_event *event);
+
+void ltt_transport_register(struct ltt_transport *transport);
+void ltt_transport_unregister(struct ltt_transport *transport);
+
+void synchronize_trace(void);
+int ltt_debugfs_abi_init(void);
+void ltt_debugfs_abi_exit(void);
+
+int ltt_probe_register(struct lttng_probe_desc *desc);
+void ltt_probe_unregister(struct lttng_probe_desc *desc);
+const struct lttng_event_desc *ltt_event_get(const char *name);
+void ltt_event_put(const struct lttng_event_desc *desc);
+int ltt_probes_init(void);
+void ltt_probes_exit(void);
+
+#ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
+int lttng_syscalls_register(struct ltt_channel *chan, void *filter);
+int lttng_syscalls_unregister(struct ltt_channel *chan);
+#else
+static inline int lttng_syscalls_register(struct ltt_channel *chan, void *filter)
+{
+	return -ENOSYS;
+}
+
+static inline int lttng_syscalls_unregister(struct ltt_channel *chan)
+{
+	return 0;
+}
+#endif
+
+struct lttng_ctx_field *lttng_append_context(struct lttng_ctx **ctx);
+int lttng_find_context(struct lttng_ctx *ctx, const char *name);
+void lttng_remove_context_field(struct lttng_ctx **ctx,
+				struct lttng_ctx_field *field);
+void lttng_destroy_context(struct lttng_ctx *ctx);
+int lttng_add_pid_to_ctx(struct lttng_ctx **ctx);
+int lttng_add_procname_to_ctx(struct lttng_ctx **ctx);
+int lttng_add_prio_to_ctx(struct lttng_ctx **ctx);
+int lttng_add_nice_to_ctx(struct lttng_ctx **ctx);
+int lttng_add_vpid_to_ctx(struct lttng_ctx **ctx);
+int lttng_add_tid_to_ctx(struct lttng_ctx **ctx);
+int lttng_add_vtid_to_ctx(struct lttng_ctx **ctx);
+int lttng_add_ppid_to_ctx(struct lttng_ctx **ctx);
+int lttng_add_vppid_to_ctx(struct lttng_ctx **ctx);
+#if defined(CONFIG_PERF_EVENTS) && (LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,33))
+int lttng_add_perf_counter_to_ctx(uint32_t type,
+				  uint64_t config,
+				  const char *name,
+				  struct lttng_ctx **ctx);
+#else
+static inline
+int lttng_add_perf_counter_to_ctx(uint32_t type,
+				  uint64_t config,
+				  const char *name,
+				  struct lttng_ctx **ctx)
+{
+	return -ENOSYS;
+}
+#endif
+
+#ifdef CONFIG_KPROBES
+int lttng_kprobes_register(const char *name,
+		const char *symbol_name,
+		uint64_t offset,
+		uint64_t addr,
+		struct ltt_event *event);
+void lttng_kprobes_unregister(struct ltt_event *event);
+void lttng_kprobes_destroy_private(struct ltt_event *event);
+#else
+static inline
+int lttng_kprobes_register(const char *name,
+		const char *symbol_name,
+		uint64_t offset,
+		uint64_t addr,
+		struct ltt_event *event)
+{
+	return -ENOSYS;
+}
+
+static inline
+void lttng_kprobes_unregister(struct ltt_event *event)
+{
+}
+
+static inline
+void lttng_kprobes_destroy_private(struct ltt_event *event)
+{
+}
+#endif
+
+#ifdef CONFIG_KRETPROBES
+int lttng_kretprobes_register(const char *name,
+		const char *symbol_name,
+		uint64_t offset,
+		uint64_t addr,
+		struct ltt_event *event_entry,
+		struct ltt_event *event_exit);
+void lttng_kretprobes_unregister(struct ltt_event *event);
+void lttng_kretprobes_destroy_private(struct ltt_event *event);
+#else
+static inline
+int lttng_kretprobes_register(const char *name,
+		const char *symbol_name,
+		uint64_t offset,
+		uint64_t addr,
+		struct ltt_event *event_entry,
+		struct ltt_event *event_exit)
+{
+	return -ENOSYS;
+}
+
+static inline
+void lttng_kretprobes_unregister(struct ltt_event *event)
+{
+}
+
+static inline
+void lttng_kretprobes_destroy_private(struct ltt_event *event)
+{
+}
+#endif
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+int lttng_ftrace_register(const char *name,
+			  const char *symbol_name,
+			  struct ltt_event *event);
+void lttng_ftrace_unregister(struct ltt_event *event);
+void lttng_ftrace_destroy_private(struct ltt_event *event);
+#else
+static inline
+int lttng_ftrace_register(const char *name,
+			  const char *symbol_name,
+			  struct ltt_event *event)
+{
+	return -ENOSYS;
+}
+
+static inline
+void lttng_ftrace_unregister(struct ltt_event *event)
+{
+}
+
+static inline
+void lttng_ftrace_destroy_private(struct ltt_event *event)
+{
+}
+#endif
+
+int lttng_calibrate(struct lttng_kernel_calibrate *calibrate);
+
+extern const struct file_operations lttng_tracepoint_list_fops;
+
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,35))
+#define TRACEPOINT_HAS_DATA_ARG
+#endif
+
+#endif /* _LTT_EVENTS_H */

drivers/staging/lttng/ltt-probes.c

@@ -0,0 +1,164 @@
+/*
+ * ltt-probes.c
+ *
+ * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Holds LTTng probes registry.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/seq_file.h>
+
+#include "ltt-events.h"
+
+static LIST_HEAD(probe_list);
+static DEFINE_MUTEX(probe_mutex);
+
+static
+const struct lttng_event_desc *find_event(const char *name)
+{
+	struct lttng_probe_desc *probe_desc;
+	int i;
+
+	list_for_each_entry(probe_desc, &probe_list, head) {
+		for (i = 0; i < probe_desc->nr_events; i++) {
+			if (!strcmp(probe_desc->event_desc[i]->name, name))
+				return probe_desc->event_desc[i];
+		}
+	}
+	return NULL;
+}
+
+int ltt_probe_register(struct lttng_probe_desc *desc)
+{
+	int ret = 0;
+	int i;
+
+	mutex_lock(&probe_mutex);
+	/*
+	 * TODO: This is O(N^2). Turn into a hash table when probe registration
+	 * overhead becomes an issue.
+	 */
+	for (i = 0; i < desc->nr_events; i++) {
+		if (find_event(desc->event_desc[i]->name)) {
+			ret = -EEXIST;
+			goto end;
+		}
+	}
+	list_add(&desc->head, &probe_list);
+end:
+	mutex_unlock(&probe_mutex);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(ltt_probe_register);
+
+void ltt_probe_unregister(struct lttng_probe_desc *desc)
+{
+	mutex_lock(&probe_mutex);
+	list_del(&desc->head);
+	mutex_unlock(&probe_mutex);
+}
+EXPORT_SYMBOL_GPL(ltt_probe_unregister);
+
+const struct lttng_event_desc *ltt_event_get(const char *name)
+{
+	const struct lttng_event_desc *event;
+	int ret;
+
+	mutex_lock(&probe_mutex);
+	event = find_event(name);
+	mutex_unlock(&probe_mutex);
+	if (!event)
+		return NULL;
+	ret = try_module_get(event->owner);
+	WARN_ON_ONCE(!ret);
+	return event;
+}
+EXPORT_SYMBOL_GPL(ltt_event_get);
+
+void ltt_event_put(const struct lttng_event_desc *event)
+{
+	module_put(event->owner);
+}
+EXPORT_SYMBOL_GPL(ltt_event_put);
+
+static
+void *tp_list_start(struct seq_file *m, loff_t *pos)
+{
+	struct lttng_probe_desc *probe_desc;
+	int iter = 0, i;
+
+	mutex_lock(&probe_mutex);
+	list_for_each_entry(probe_desc, &probe_list, head) {
+		for (i = 0; i < probe_desc->nr_events; i++) {
+			if (iter++ >= *pos)
+				return (void *) probe_desc->event_desc[i];
+		}
+	}
+	/* End of list */
+	return NULL;
+}
+
+static
+void *tp_list_next(struct seq_file *m, void *p, loff_t *ppos)
+{
+	struct lttng_probe_desc *probe_desc;
+	int iter = 0, i;
+
+	(*ppos)++;
+	list_for_each_entry(probe_desc, &probe_list, head) {
+		for (i = 0; i < probe_desc->nr_events; i++) {
+			if (iter++ >= *ppos)
+				return (void *) probe_desc->event_desc[i];
+		}
+	}
+	/* End of list */
+	return NULL;
+}
+
+static
+void tp_list_stop(struct seq_file *m, void *p)
+{
+	mutex_unlock(&probe_mutex);
+}
+
+static
+int tp_list_show(struct seq_file *m, void *p)
+{
+	const struct lttng_event_desc *probe_desc = p;
+
+	/*
+	 * Don't export lttng internal events (metadata).
+	 */
+	if (!strncmp(probe_desc->name, "lttng_", sizeof("lttng_") - 1))
+		return 0;
+	seq_printf(m,	"event { name = %s; };\n",
+		   probe_desc->name);
+	return 0;
+}
+
+static
+const struct seq_operations lttng_tracepoint_list_seq_ops = {
+	.start = tp_list_start,
+	.next = tp_list_next,
+	.stop = tp_list_stop,
+	.show = tp_list_show,
+};
+
+static
+int lttng_tracepoint_list_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &lttng_tracepoint_list_seq_ops);
+}
+
+const struct file_operations lttng_tracepoint_list_fops = {
+	.owner = THIS_MODULE,
+	.open = lttng_tracepoint_list_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = seq_release,
+};

drivers/staging/lttng/ltt-tracer-core.h

@@ -0,0 +1,28 @@
+#ifndef LTT_TRACER_CORE_H
+#define LTT_TRACER_CORE_H
+
+/*
+ * ltt-tracer-core.h
+ *
+ * Copyright (C) 2005-2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * This contains the core definitions for the Linux Trace Toolkit.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/list.h>
+#include <linux/percpu.h>
+
+#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+/* Align data on its natural alignment */
+#define RING_BUFFER_ALIGN
+#endif
+
+#include "wrapper/ringbuffer/config.h"
+
+struct ltt_session;
+struct ltt_channel;
+struct ltt_event;
+
+#endif /* LTT_TRACER_CORE_H */

drivers/staging/lttng/ltt-tracer.h

@@ -0,0 +1,67 @@
+#ifndef _LTT_TRACER_H
+#define _LTT_TRACER_H
+
+/*
+ * ltt-tracer.h
+ *
+ * Copyright (C) 2005-2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * This contains the definitions for the Linux Trace Toolkit tracer.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <stdarg.h>
+#include <linux/types.h>
+#include <linux/limits.h>
+#include <linux/list.h>
+#include <linux/cache.h>
+#include <linux/timex.h>
+#include <linux/wait.h>
+#include <asm/atomic.h>
+#include <asm/local.h>
+
+#include "wrapper/trace-clock.h"
+#include "ltt-tracer-core.h"
+#include "ltt-events.h"
+
+#define LTTNG_VERSION 0
+#define LTTNG_PATCHLEVEL 9
+#define LTTNG_SUBLEVEL 1
+
+#ifndef CHAR_BIT
+#define CHAR_BIT 8
+#endif
+
+/* Number of bytes to log with a read/write event */
+#define LTT_LOG_RW_SIZE			32L
+#define LTT_MAX_SMALL_SIZE		0xFFFFU
+
+#ifdef RING_BUFFER_ALIGN
+#define ltt_alignof(type)	__alignof__(type)
+#else
+#define ltt_alignof(type)	1
+#endif
+
+/* Tracer properties */
+#define CTF_MAGIC_NUMBER		0xC1FC1FC1
+#define TSDL_MAGIC_NUMBER		0x75D11D57
+
+/* CTF specification version followed */
+#define CTF_SPEC_MAJOR			1
+#define CTF_SPEC_MINOR			8
+
+/* Tracer major/minor versions */
+#define CTF_VERSION_MAJOR		0
+#define CTF_VERSION_MINOR		1
+
+/*
+ * Number of milliseconds to retry before failing metadata writes on buffer full
+ * condition. (10 seconds)
+ */
+#define LTTNG_METADATA_TIMEOUT_MSEC	10000
+
+#define LTT_RFLAG_EXTENDED		RING_BUFFER_RFLAG_END
+#define LTT_RFLAG_END			(LTT_RFLAG_EXTENDED << 1)
+
+#endif /* _LTT_TRACER_H */