--- /dev/null
+/*
+ * lttng-ust-abi.c
+ *
+ * Copyright 2010-2011 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng UST ABI
+ *
+ * Mimic system calls for:
+ * - session creation, returns an object descriptor or failure.
+ * - channel creation, returns an object descriptor or failure.
+ * - Operates on a session object descriptor
+ * - Takes all channel options as parameters.
+ * - stream get, returns an object descriptor or failure.
+ * - Operates on a channel object descriptor.
+ * - stream notifier get, returns an object descriptor or failure.
+ * - Operates on a channel object descriptor.
+ * - event creation, returns an object descriptor or failure.
+ * - Operates on a channel object descriptor
+ * - Takes an event name as parameter
+ * - Takes an instrumentation source as parameter
+ * - e.g. tracepoints, dynamic_probes...
+ * - Takes instrumentation source specific arguments.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <ust/lttng-ust-abi.h>
+#include <urcu/compiler.h>
+#include <urcu/list.h>
+#include <ust/lttng-events.h>
+#include "usterr_signal_safe.h"
+#include "ust/core.h"
+#include "ltt-tracer.h"
+
+/*
+ * Object descriptor table. Should be protected from concurrent access
+ * by the caller.
+ */
+
+struct obj;
+
+struct objd_ops {
+ long (*cmd)(int objd, unsigned int cmd, unsigned long arg);
+ int (*release)(int objd);
+};
+
+struct obj {
+ union {
+ struct {
+ void *private_data;
+ const struct objd_ops *ops;
+ int f_count;
+ } s;
+ int freelist_next; /* offset freelist. end is -1. */
+ } u;
+};
+
+struct objd_table {
+ struct obj *array;
+ unsigned int len, allocated_len;
+ int freelist_head; /* offset freelist head. end is -1 */
+};
+
+static struct objd_table objd_table = {
+ .freelist_head = -1,
+};
+
+static
+int objd_alloc(void *private_data, const struct objd_ops *ops)
+{
+ struct obj *obj;
+
+ if (objd_table.freelist_head != -1) {
+ obj = &objd_table.array[objd_table.freelist_head];
+ objd_table.freelist_head = obj->u.freelist_next;
+ goto end;
+ }
+
+ if (objd_table.len >= objd_table.allocated_len) {
+ unsigned int new_allocated_len, old_allocated_len;
+ struct obj *new_table, *old_table;
+
+ old_allocated_len = objd_table.allocated_len;
+ old_table = objd_table.array;
+ if (!old_allocated_len)
+ new_allocated_len = 1;
+ else
+ new_allocated_len = old_allocated_len << 1;
+ new_table = zmalloc(sizeof(struct obj) * new_allocated_len);
+ if (!new_table)
+ return -ENOMEM;
+ memcpy(new_table, old_table,
+ sizeof(struct obj) * old_allocated_len);
+ free(old_table);
+ objd_table.array = new_table;
+ objd_table.allocated_len = new_allocated_len;
+ }
+ obj = &objd_table.array[objd_table.len];
+ objd_table.len++;
+end:
+ obj->u.s.private_data = private_data;
+ obj->u.s.ops = ops;
+ obj->u.s.f_count = 1;
+ return obj - objd_table.array;
+}
+
+static
+struct obj *_objd_get(int id)
+{
+ if (id >= objd_table.len)
+ return NULL;
+ return &objd_table.array[id];
+}
+
+static
+void *objd_private(int id)
+{
+ struct obj *obj = _objd_get(id);
+ assert(obj);
+ return obj->u.s.private_data;
+}
+
+static
+void objd_set_private(int id, void *private_data)
+{
+ struct obj *obj = _objd_get(id);
+ assert(obj);
+ obj->u.s.private_data = private_data;
+}
+
+static
+const struct objd_ops *objd_ops(int id)
+{
+ struct obj *obj = _objd_get(id);
+ assert(obj);
+ return obj->u.s.ops;
+}
+
+static
+void objd_free(int id)
+{
+ struct obj *obj = _objd_get(id);
+
+ assert(obj);
+ obj->u.freelist_next = objd_table.freelist_head;
+ objd_table.freelist_head = obj - objd_table.array;
+}
+
+static
+void objd_ref(int id)
+{
+ struct obj *obj = _objd_get(id);
+ obj->u.s.f_count++;
+}
+
+static
+void objd_unref(int id)
+{
+ struct obj *obj = _objd_get(id);
+
+ if (!(--obj->u.s.f_count)) {
+ const struct objd_ops *ops = objd_ops(id);
+
+ if (ops->release)
+ ops->release(id);
+ objd_free(id);
+ }
+}
+
+static
+void objd_table_destroy(void)
+{
+ free(objd_table.array);
+}
+
+/*
+ * This is LTTng's own personal way to create an ABI for sessiond.
+ * We send commands over a socket.
+ */
+
+static const struct objd_ops lttng_ops;
+static const struct objd_ops lttng_session_ops;
+static const struct objd_ops lttng_channel_ops;
+static const struct objd_ops lttng_metadata_ops;
+static const struct objd_ops lttng_event_ops;
+
+enum channel_type {
+ PER_CPU_CHANNEL,
+ METADATA_CHANNEL,
+};
+
+static
+int lttng_abi_create_session(void)
+{
+ struct ltt_session *session;
+ int session_objd, ret;
+
+ session = ltt_session_create();
+ if (!session)
+ return -ENOMEM;
+ session_objd = objd_alloc(session, <tng_session_ops);
+ if (session_objd < 0) {
+ ret = session_objd;
+ goto objd_error;
+ }
+ session->objd = session_objd;
+ return session_objd;
+
+objd_error:
+ ltt_session_destroy(session);
+ return ret;
+}
+
+#if 0
+static
+int lttng_abi_tracepoint_list(void)
+{
+ int list_objd, ret;
+
+ /* TODO: Create list private data */
+ list_objd = objd_alloc(NULL, <tng_tracepoint_list_ops);
+ if (list_objd < 0) {
+ ret = list_objd;
+ goto objd_error;
+ }
+
+ return list_objd;
+
+objd_error:
+ return ret;
+}
+#endif //0
+
+static
+long lttng_abi_tracer_version(int objd,
+ struct lttng_ust_tracer_version *v)
+{
+ v->version = LTTNG_UST_VERSION;
+ v->patchlevel = LTTNG_UST_PATCHLEVEL;
+ v->sublevel = LTTNG_UST_SUBLEVEL;
+ return 0;
+}
+
+static
+long lttng_abi_add_context(int objd,
+ struct lttng_ust_context *context_param,
+ struct lttng_ctx **ctx, struct ltt_session *session)
+{
+ if (session->been_active)
+ return -EPERM;
+
+ switch (context_param->ctx) {
+ case LTTNG_UST_CONTEXT_VTID:
+ return lttng_add_vtid_to_ctx(ctx);
+ default:
+ return -EINVAL;
+ }
+}
+
+/**
+ * lttng_cmd - lttng control through socket commands
+ *
+ * @objd: the object descriptor
+ * @cmd: the command
+ * @arg: command arg
+ *
+ * This descriptor implements lttng commands:
+ * LTTNG_UST_SESSION
+ * Returns a LTTng trace session object descriptor
+ * LTTNG_UST_TRACER_VERSION
+ * Returns the LTTng kernel tracer version
+ * LTTNG_UST_TRACEPOINT_LIST
+ * Returns a file descriptor listing available tracepoints
+ * LTTNG_UST_WAIT_QUIESCENT
+ * Returns after all previously running probes have completed
+ *
+ * The returned session will be deleted when its file descriptor is closed.
+ */
+static
+long lttng_cmd(int objd, unsigned int cmd, unsigned long arg)
+{
+ switch (cmd) {
+ case LTTNG_UST_SESSION:
+ return lttng_abi_create_session();
+ case LTTNG_UST_TRACER_VERSION:
+ return lttng_abi_tracer_version(objd,
+ (struct lttng_ust_tracer_version *) arg);
+ case LTTNG_UST_TRACEPOINT_LIST:
+ return -ENOSYS; //TODO
+ //return lttng_abi_tracepoint_list();
+ case LTTNG_UST_WAIT_QUIESCENT:
+ synchronize_trace();
+ return 0;
+ default:
+ return -EINVAL;
+ }
+}
+
+static const struct objd_ops lttng_ops = {
+ .cmd = lttng_cmd,
+};
+
+/*
+ * We tolerate no failure in this function (if one happens, we print a dmesg
+ * error, but cannot return any error, because the channel information is
+ * invariant.
+ */
+static
+void lttng_metadata_create_events(int channel_objd)
+{
+ struct ltt_channel *channel = objd_private(channel_objd);
+ static struct lttng_ust_event metadata_params = {
+ .instrumentation = LTTNG_UST_TRACEPOINT,
+ .name = "lttng_metadata",
+ };
+ struct ltt_event *event;
+ int ret;
+
+ /*
+ * We tolerate no failure path after event creation. It will stay
+ * invariant for the rest of the session.
+ */
+ event = ltt_event_create(channel, &metadata_params, NULL);
+ if (!event) {
+ ret = -EINVAL;
+ goto create_error;
+ }
+ return;
+
+create_error:
+ WARN_ON(1);
+ return; /* not allowed to return error */
+}
+
+static
+int lttng_abi_create_channel(int session_objd,
+ struct lttng_ust_channel *chan_param,
+ enum channel_type channel_type)
+{
+ struct ltt_session *session = objd_private(session_objd);
+ const struct objd_ops *ops;
+ const char *transport_name;
+ struct ltt_channel *chan;
+ int chan_objd;
+ int ret = 0;
+
+ chan_objd = objd_alloc(NULL, <tng_channel_ops);
+ if (chan_objd < 0) {
+ ret = chan_objd;
+ goto objd_error;
+ }
+ switch (channel_type) {
+ case PER_CPU_CHANNEL:
+ if (chan_param->output == LTTNG_UST_MMAP) {
+ transport_name = chan_param->overwrite ?
+ "relay-overwrite-mmap" : "relay-discard-mmap";
+ } else {
+ return -EINVAL;
+ }
+ ops = <tng_channel_ops;
+ break;
+ case METADATA_CHANNEL:
+ if (chan_param->output == LTTNG_UST_MMAP)
+ transport_name = "relay-metadata-mmap";
+ else
+ return -EINVAL;
+ ops = <tng_metadata_ops;
+ break;
+ default:
+ transport_name = "<unknown>";
+ break;
+ }
+ /*
+ * We tolerate no failure path after channel creation. It will stay
+ * invariant for the rest of the session.
+ */
+ chan = ltt_channel_create(session, transport_name, NULL,
+ chan_param->subbuf_size,
+ chan_param->num_subbuf,
+ chan_param->switch_timer_interval,
+ chan_param->read_timer_interval);
+ if (!chan) {
+ ret = -EINVAL;
+ goto chan_error;
+ }
+ objd_set_private(chan_objd, chan);
+ chan->objd = chan_objd;
+ if (channel_type == METADATA_CHANNEL) {
+ session->metadata = chan;
+ lttng_metadata_create_events(chan_objd);
+ }
+
+ /* The channel created holds a reference on the session */
+ objd_ref(session_objd);
+
+ return chan_objd;
+
+chan_error:
+ objd_unref(chan_objd);
+objd_error:
+ return ret;
+}
+
+/**
+ * lttng_session_cmd - lttng session object command
+ *
+ * @obj: the object
+ * @cmd: the command
+ * @arg: command arg
+ *
+ * This descriptor implements lttng commands:
+ * LTTNG_UST_CHANNEL
+ * Returns a LTTng channel object descriptor
+ * LTTNG_UST_ENABLE
+ * Enables tracing for a session (weak enable)
+ * LTTNG_UST_DISABLE
+ * Disables tracing for a session (strong disable)
+ * LTTNG_UST_METADATA
+ * Returns a LTTng metadata object descriptor
+ *
+ * The returned channel will be deleted when its file descriptor is closed.
+ */
+static
+long lttng_session_cmd(int objd, unsigned int cmd, unsigned long arg)
+{
+ struct ltt_session *session = objd_private(objd);
+
+ switch (cmd) {
+ case LTTNG_UST_CHANNEL:
+ return lttng_abi_create_channel(objd,
+ (struct lttng_ust_channel *) arg,
+ PER_CPU_CHANNEL);
+ case LTTNG_UST_SESSION_START:
+ case LTTNG_UST_ENABLE:
+ return ltt_session_enable(session);
+ case LTTNG_UST_SESSION_STOP:
+ case LTTNG_UST_DISABLE:
+ return ltt_session_disable(session);
+ case LTTNG_UST_METADATA:
+ return lttng_abi_create_channel(objd,
+ (struct lttng_ust_channel *) arg,
+ METADATA_CHANNEL);
+ default:
+ return -EINVAL;
+ }
+}
+
+/*
+ * Called when the last file reference is dropped.
+ *
+ * Big fat note: channels and events are invariant for the whole session after
+ * their creation. So this session destruction also destroys all channel and
+ * event structures specific to this session (they are not destroyed when their
+ * individual file is released).
+ */
+static
+int lttng_session_release(int objd)
+{
+ struct ltt_session *session = objd_private(objd);
+
+ if (session)
+ ltt_session_destroy(session);
+ return 0;
+}
+
+static const struct objd_ops lttng_session_ops = {
+ .release = lttng_session_release,
+ .cmd = lttng_session_cmd,
+};
+
+#if 0
+static
+int lttng_abi_open_stream(int channel_objd)
+{
+ struct ltt_channel *channel = objd_private(channel_objd);
+ struct lib_ring_buffer *buf;
+ int stream_objd, ret;
+
+ buf = channel->ops->buffer_read_open(channel->chan);
+ if (!buf)
+ return -ENOENT;
+
+ stream_objd = objd_alloc(buf, &lib_ring_buffer_objd_ops);
+ if (stream_objd < 0) {
+ ret = stream_objd;
+ goto objd_error;
+ }
+ /*
+ * The stream holds a reference to the channel within the generic ring
+ * buffer library, so no need to hold a refcount on the channel and
+ * session files here.
+ */
+ return stream_objd;
+
+objd_error:
+ channel->ops->buffer_read_close(buf);
+ return ret;
+}
+#endif //0
+
+static
+int lttng_abi_create_event(int channel_objd,
+ struct lttng_ust_event *event_param)
+{
+ struct ltt_channel *channel = objd_private(channel_objd);
+ struct ltt_event *event;
+ int event_objd, ret;
+
+ event_param->name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
+ event_objd = objd_alloc(NULL, <tng_event_ops);
+ if (event_objd < 0) {
+ ret = event_objd;
+ goto objd_error;
+ }
+ /*
+ * We tolerate no failure path after event creation. It will stay
+ * invariant for the rest of the session.
+ */
+ event = ltt_event_create(channel, event_param, NULL);
+ if (!event) {
+ ret = -EINVAL;
+ goto event_error;
+ }
+ objd_set_private(event_objd, event);
+ /* The event holds a reference on the channel */
+ objd_ref(channel_objd);
+ return event_objd;
+
+event_error:
+ objd_unref(event_objd);
+objd_error:
+ return ret;
+}
+
+/**
+ * lttng_channel_cmd - lttng control through object descriptors
+ *
+ * @objd: the object descriptor
+ * @cmd: the command
+ * @arg: command arg
+ *
+ * This object descriptor implements lttng commands:
+ * LTTNG_UST_STREAM
+ * Returns an event stream object descriptor or failure.
+ * (typically, one event stream records events from one CPU)
+ * LTTNG_UST_EVENT
+ * Returns an event object descriptor or failure.
+ * LTTNG_UST_CONTEXT
+ * Prepend a context field to each event in the channel
+ * LTTNG_UST_ENABLE
+ * Enable recording for events in this channel (weak enable)
+ * LTTNG_UST_DISABLE
+ * Disable recording for events in this channel (strong disable)
+ *
+ * Channel and event file descriptors also hold a reference on the session.
+ */
+static
+long lttng_channel_cmd(int objd, unsigned int cmd, unsigned long arg)
+{
+ struct ltt_channel *channel = objd_private(objd);
+
+ switch (cmd) {
+ case LTTNG_UST_STREAM:
+ return -ENOSYS; //TODO
+ //return lttng_abi_open_stream(objd);
+ case LTTNG_UST_EVENT:
+ return lttng_abi_create_event(objd, (struct lttng_ust_event *) arg);
+ case LTTNG_UST_CONTEXT:
+ return lttng_abi_add_context(objd,
+ (struct lttng_ust_context *) arg,
+ &channel->ctx, channel->session);
+ case LTTNG_UST_ENABLE:
+ return ltt_channel_enable(channel);
+ case LTTNG_UST_DISABLE:
+ return ltt_channel_disable(channel);
+ default:
+ return -EINVAL;
+ }
+}
+
+/**
+ * lttng_metadata_cmd - lttng control through object descriptors
+ *
+ * @objd: the object descriptor
+ * @cmd: the command
+ * @arg: command arg
+ *
+ * This object descriptor implements lttng commands:
+ * LTTNG_UST_STREAM
+ * Returns an event stream file descriptor or failure.
+ *
+ * Channel and event file descriptors also hold a reference on the session.
+ */
+static
+long lttng_metadata_cmd(int objd, unsigned int cmd, unsigned long arg)
+{
+ switch (cmd) {
+ case LTTNG_UST_STREAM:
+ return -ENOSYS; //TODO
+ //return lttng_abi_open_stream(objd);
+ default:
+ return -EINVAL;
+ }
+}
+
+#if 0
+/**
+ * lttng_channel_poll - lttng stream addition/removal monitoring
+ *
+ * @file: the file
+ * @wait: poll table
+ */
+unsigned int lttng_channel_poll(struct file *file, poll_table *wait)
+{
+ struct ltt_channel *channel = file->private_data;
+ unsigned int mask = 0;
+
+ if (file->f_mode & FMODE_READ) {
+ poll_wait_set_exclusive(wait);
+ poll_wait(file, channel->ops->get_hp_wait_queue(channel->chan),
+ wait);
+
+ if (channel->ops->is_disabled(channel->chan))
+ return POLLERR;
+ if (channel->ops->is_finalized(channel->chan))
+ return POLLHUP;
+ if (channel->ops->buffer_has_read_closed_stream(channel->chan))
+ return POLLIN | POLLRDNORM;
+ return 0;
+ }
+ return mask;
+
+}
+#endif //0
+
+static
+int lttng_channel_release(int objd)
+{
+ struct ltt_channel *channel = objd_private(objd);
+
+ if (channel)
+ objd_unref(channel->session->objd);
+ return 0;
+}
+
+static const struct objd_ops lttng_channel_ops = {
+ .release = lttng_channel_release,
+ //.poll = lttng_channel_poll,
+ .cmd = lttng_channel_cmd,
+};
+
+static const struct objd_ops lttng_metadata_ops = {
+ .release = lttng_channel_release,
+ .cmd = lttng_metadata_cmd,
+};
+
+/**
+ * lttng_event_cmd - lttng control through object descriptors
+ *
+ * @objd: the object descriptor
+ * @cmd: the command
+ * @arg: command arg
+ *
+ * This object descriptor implements lttng commands:
+ * LTTNG_UST_CONTEXT
+ * Prepend a context field to each record of this event
+ * LTTNG_UST_ENABLE
+ * Enable recording for this event (weak enable)
+ * LTTNG_UST_DISABLE
+ * Disable recording for this event (strong disable)
+ */
+static
+long lttng_event_cmd(int objd, unsigned int cmd, unsigned long arg)
+{
+ struct ltt_event *event = objd_private(objd);
+
+ switch (cmd) {
+ case LTTNG_UST_CONTEXT:
+ return lttng_abi_add_context(objd,
+ (struct lttng_ust_context *) arg,
+ &event->ctx, event->chan->session);
+ case LTTNG_UST_ENABLE:
+ return ltt_event_enable(event);
+ case LTTNG_UST_DISABLE:
+ return ltt_event_disable(event);
+ default:
+ return -EINVAL;
+ }
+}
+
+static
+int lttng_event_release(int objd)
+{
+ struct ltt_event *event = objd_private(objd);
+
+ if (event)
+ objd_unref(event->chan->objd);
+ return 0;
+}
+
+/* TODO: filter control ioctl */
+static const struct objd_ops lttng_event_ops = {
+ .release = lttng_event_release,
+ .cmd = lttng_event_cmd,
+};
+
+void __attribute__((constructor)) lttng_ust_abi_init(void)
+{
+ /* TODO: initialize socket */
+}
+
+static
+void __attribute__((destructor)) lttng_ust_abi_exit(void)
+{
+ /* TODO: teardown socket */
+ objd_table_destroy();
+}
projects / ust.git / commitdiff
