/*
+ * SPDX-License-Identifier: LGPL-2.1-only
+ *
* Copyright (C) 2008-2011 Mathieu Desnoyers
* Copyright (C) 2009 Pierre-Marc Fournier
*
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation;
- * version 2.1 of the License.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- *
* Ported to userspace by Pierre-Marc Fournier.
*/
#define _LGPL_SOURCE
#include <errno.h>
-#include <lttng/tracepoint.h>
-#include <lttng/tracepoint-internal.h>
-#include <lttng/core.h>
-#include <lttng/kcompat/kcompat.h>
-#include <urcu-bp.h>
+#include <stdint.h>
+#include <stddef.h>
+#include <stdio.h>
+
+#include <urcu/arch.h>
+#include <lttng/urcu/urcu-ust.h>
#include <urcu/hlist.h>
#include <urcu/uatomic.h>
+#include <urcu/compiler.h>
+#include <urcu/system.h>
+
+#include <lttng/tracepoint.h>
+#include <lttng/ust-abi.h> /* for LTTNG_UST_SYM_NAME_LEN */
-#include <lttng/usterr-signal-safe.h>
-#include "ltt-tracer-core.h"
+#include <usterr-signal-safe.h>
+#include <helper.h>
+
+#include "tracepoint-internal.h"
+#include "lttng-tracer-core.h"
+#include "jhash.h"
+#include "error.h"
+
+/* Test compiler support for weak symbols with hidden visibility. */
+int __tracepoint_test_symbol1 __attribute__((weak, visibility("hidden")));
+void *__tracepoint_test_symbol2 __attribute__((weak, visibility("hidden")));
+struct {
+ char a[24];
+} __tracepoint_test_symbol3 __attribute__((weak, visibility("hidden")));
/* Set to 1 to enable tracepoint debug output */
static const int tracepoint_debug;
static int initialized;
-static void (*new_tracepoint_cb)(struct tracepoint *);
-/* libraries that contain tracepoints (struct tracepoint_lib) */
+/*
+ * If tracepoint_destructors_state = 1, tracepoint destructors are
+ * enabled. They are disabled otherwise.
+ */
+static int tracepoint_destructors_state = 1;
+
+static void (*new_tracepoint_cb)(struct lttng_ust_tracepoint *);
+
+/*
+ * tracepoint_mutex nests inside UST mutex.
+ *
+ * Note about interaction with fork/clone: UST does not hold the
+ * tracepoint mutex across fork/clone because it is either:
+ * - nested within UST mutex, in which case holding the UST mutex across
+ * fork/clone suffice,
+ * - taken by a library constructor, which should never race with a
+ * fork/clone if the application is expected to continue running with
+ * the same memory layout (no following exec()).
+ */
+static pthread_mutex_t tracepoint_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+/*
+ * libraries that contain tracepoints (struct tracepoint_lib).
+ * Protected by tracepoint mutex.
+ */
static CDS_LIST_HEAD(libs);
/*
- * The UST lock protects the library tracepoints, the hash table, and
+ * The tracepoint mutex protects the library tracepoints, the hash table, and
* the library list.
- * All calls to the tracepoint API must be protected by the UST lock,
+ * All calls to the tracepoint API must be protected by the tracepoint mutex,
* excepts calls to tracepoint_register_lib and
- * tracepoint_unregister_lib, which take the UST lock themselves.
+ * tracepoint_unregister_lib, which take the tracepoint mutex themselves.
*/
/*
* Tracepoint hash table, containing the active tracepoints.
- * Protected by tracepoints_mutex.
+ * Protected by tracepoint mutex.
*/
-#define TRACEPOINT_HASH_BITS 6
+#define TRACEPOINT_HASH_BITS 12
#define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS)
static struct cds_hlist_head tracepoint_table[TRACEPOINT_TABLE_SIZE];
static CDS_LIST_HEAD(old_probes);
static int need_update;
+static CDS_LIST_HEAD(release_queue);
+static int release_queue_need_update;
+
/*
* Note about RCU :
* It is used to to delay the free of multiple probes array until a quiescent
* state is reached.
- * Tracepoint entries modifications are protected by the tracepoints_mutex.
+ * Tracepoint entries modifications are protected by the tracepoint mutex.
*/
struct tracepoint_entry {
struct cds_hlist_node hlist;
- struct tracepoint_probe *probes;
+ struct lttng_ust_tracepoint_probe *probes;
int refcount; /* Number of times armed. 0 if disarmed. */
- char name[0];
+ int callsite_refcount; /* how many libs use this tracepoint */
+ char *signature;
+ char *name;
};
struct tp_probes {
union {
struct cds_list_head list;
+ /* Field below only used for call_rcu scheme */
+ /* struct rcu_head head; */
} u;
- struct tracepoint_probe probes[0];
+ struct lttng_ust_tracepoint_probe probes[0];
};
-static inline void *allocate_probes(int count)
+/*
+ * Callsite hash table, containing the tracepoint call sites.
+ * Protected by tracepoint mutex.
+ */
+#define CALLSITE_HASH_BITS 12
+#define CALLSITE_TABLE_SIZE (1 << CALLSITE_HASH_BITS)
+static struct cds_hlist_head callsite_table[CALLSITE_TABLE_SIZE];
+
+struct callsite_entry {
+ struct cds_hlist_node hlist; /* hash table node */
+ struct cds_list_head node; /* lib list of callsites node */
+ struct lttng_ust_tracepoint *tp;
+ bool tp_entry_callsite_ref; /* Has a tp_entry took a ref on this callsite */
+};
+
+/* coverity[+alloc] */
+static void *allocate_probes(int count)
{
- struct tp_probes *p = zmalloc(count * sizeof(struct tracepoint_probe)
- + sizeof(struct tp_probes));
+ struct tp_probes *p =
+ zmalloc(count * sizeof(struct lttng_ust_tracepoint_probe)
+ + sizeof(struct tp_probes));
return p == NULL ? NULL : p->probes;
}
-static inline void release_probes(void *old)
+/* coverity[+free : arg-0] */
+static void release_probes(void *old)
{
if (old) {
- struct tp_probes *tp_probes = _ust_container_of(old,
+ struct tp_probes *tp_probes = caa_container_of(old,
struct tp_probes, probes[0]);
- synchronize_rcu();
+ lttng_ust_synchronize_trace();
free(tp_probes);
}
}
static void *
tracepoint_entry_add_probe(struct tracepoint_entry *entry,
- void *probe, void *data)
+ void (*probe)(void), void *data)
{
int nr_probes = 0;
- struct tracepoint_probe *old, *new;
-
- WARN_ON(!probe);
+ struct lttng_ust_tracepoint_probe *old, *new;
+ if (!probe) {
+ WARN_ON(1);
+ return ERR_PTR(-EINVAL);
+ }
debug_print_probes(entry);
old = entry->probes;
if (old) {
if (new == NULL)
return ERR_PTR(-ENOMEM);
if (old)
- memcpy(new, old, nr_probes * sizeof(struct tracepoint_probe));
+ memcpy(new, old,
+ nr_probes * sizeof(struct lttng_ust_tracepoint_probe));
new[nr_probes].func = probe;
new[nr_probes].data = data;
new[nr_probes + 1].func = NULL;
}
static void *
-tracepoint_entry_remove_probe(struct tracepoint_entry *entry, void *probe,
- void *data)
+tracepoint_entry_remove_probe(struct tracepoint_entry *entry,
+ void (*probe)(void), void *data)
{
int nr_probes = 0, nr_del = 0, i;
- struct tracepoint_probe *old, *new;
+ struct lttng_ust_tracepoint_probe *old, *new;
old = entry->probes;
debug_print_probes(entry);
/* (N -> M), (N > 1, M >= 0) probes */
- for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
- if (!probe ||
- (old[nr_probes].func == probe &&
- old[nr_probes].data == data))
- nr_del++;
+ if (probe) {
+ for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
+ if (old[nr_probes].func == probe &&
+ old[nr_probes].data == data)
+ nr_del++;
+ }
}
if (nr_probes - nr_del == 0) {
if (new == NULL)
return ERR_PTR(-ENOMEM);
for (i = 0; old[i].func; i++)
- if (probe &&
- (old[i].func != probe || old[i].data != data))
+ if (old[i].func != probe || old[i].data != data)
new[j++] = old[i];
new[nr_probes - nr_del].func = NULL;
entry->refcount = nr_probes - nr_del;
/*
* Get tracepoint if the tracepoint is present in the tracepoint hash table.
- * Must be called with tracepoints_mutex held.
+ * Must be called with tracepoint mutex held.
* Returns NULL if not present.
*/
static struct tracepoint_entry *get_tracepoint(const char *name)
struct cds_hlist_head *head;
struct cds_hlist_node *node;
struct tracepoint_entry *e;
- u32 hash = jhash(name, strlen(name), 0);
+ size_t name_len = strlen(name);
+ uint32_t hash;
+ if (name_len > LTTNG_UST_SYM_NAME_LEN - 1) {
+ WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name, LTTNG_UST_SYM_NAME_LEN - 1);
+ name_len = LTTNG_UST_SYM_NAME_LEN - 1;
+ }
+ hash = jhash(name, name_len, 0);
head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
cds_hlist_for_each_entry(e, node, head, hlist) {
- if (!strcmp(name, e->name))
+ if (!strncmp(name, e->name, LTTNG_UST_SYM_NAME_LEN - 1))
return e;
}
return NULL;
/*
* Add the tracepoint to the tracepoint hash table. Must be called with
- * tracepoints_mutex held.
+ * tracepoint mutex held.
*/
-static struct tracepoint_entry *add_tracepoint(const char *name)
+static struct tracepoint_entry *add_tracepoint(const char *name,
+ const char *signature)
{
struct cds_hlist_head *head;
struct cds_hlist_node *node;
struct tracepoint_entry *e;
- size_t name_len = strlen(name) + 1;
- u32 hash = jhash(name, name_len-1, 0);
-
+ size_t name_len = strlen(name);
+ size_t sig_len = strlen(signature);
+ size_t sig_off, name_off;
+ uint32_t hash;
+
+ if (name_len > LTTNG_UST_SYM_NAME_LEN - 1) {
+ WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name, LTTNG_UST_SYM_NAME_LEN - 1);
+ name_len = LTTNG_UST_SYM_NAME_LEN - 1;
+ }
+ hash = jhash(name, name_len, 0);
head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
cds_hlist_for_each_entry(e, node, head, hlist) {
- if (!strcmp(name, e->name)) {
+ if (!strncmp(name, e->name, LTTNG_UST_SYM_NAME_LEN - 1)) {
DBG("tracepoint %s busy", name);
return ERR_PTR(-EEXIST); /* Already there */
}
}
+
/*
- * Using zmalloc here to allocate a variable length element. Could
- * cause some memory fragmentation if overused.
+ * Using zmalloc here to allocate a variable length elements: name and
+ * signature. Could cause some memory fragmentation if overused.
*/
- e = zmalloc(sizeof(struct tracepoint_entry) + name_len);
+ name_off = sizeof(struct tracepoint_entry);
+ sig_off = name_off + name_len + 1;
+
+ e = zmalloc(sizeof(struct tracepoint_entry) + name_len + 1 + sig_len + 1);
if (!e)
return ERR_PTR(-ENOMEM);
- memcpy(&e->name[0], name, name_len);
+ e->name = (char *) e + name_off;
+ memcpy(e->name, name, name_len + 1);
+ e->name[name_len] = '\0';
+
+ e->signature = (char *) e + sig_off;
+ memcpy(e->signature, signature, sig_len + 1);
+ e->signature[sig_len] = '\0';
+
e->probes = NULL;
e->refcount = 0;
+ e->callsite_refcount = 0;
+
cds_hlist_add_head(&e->hlist, head);
return e;
}
/*
* Remove the tracepoint from the tracepoint hash table. Must be called with
- * ust_lock held.
+ * tracepoint mutex held.
*/
-static inline void remove_tracepoint(struct tracepoint_entry *e)
+static void remove_tracepoint(struct tracepoint_entry *e)
{
cds_hlist_del(&e->hlist);
free(e);
* Sets the probe callback corresponding to one tracepoint.
*/
static void set_tracepoint(struct tracepoint_entry **entry,
- struct tracepoint *elem, int active)
+ struct lttng_ust_tracepoint *elem, int active)
{
- WARN_ON(strcmp((*entry)->name, elem->name) != 0);
+ WARN_ON(strncmp((*entry)->name, elem->name, LTTNG_UST_SYM_NAME_LEN - 1) != 0);
+ /*
+ * Check that signatures match before connecting a probe to a
+ * tracepoint. Warn the user if they don't.
+ */
+ if (strcmp(elem->signature, (*entry)->signature) != 0) {
+ static int warned = 0;
+
+ /* Only print once, don't flood console. */
+ if (!warned) {
+ WARN("Tracepoint signature mismatch, not enabling one or more tracepoints. Ensure that the tracepoint probes prototypes match the application.");
+ WARN("Tracepoint \"%s\" signatures: call: \"%s\" vs probe: \"%s\".",
+ elem->name, elem->signature, (*entry)->signature);
+ warned = 1;
+ }
+ /* Don't accept connecting non-matching signatures. */
+ return;
+ }
/*
* rcu_assign_pointer has a cmm_smp_wmb() which makes sure that the new
* include/linux/tracepoints.h. A matching cmm_smp_read_barrier_depends()
* is used.
*/
- rcu_assign_pointer(elem->probes, (*entry)->probes);
- elem->state = active;
+ lttng_ust_rcu_assign_pointer(elem->probes, (*entry)->probes);
+ CMM_STORE_SHARED(elem->state, active);
}
/*
* function insures that the original callback is not used anymore. This insured
* by preempt_disable around the call site.
*/
-static void disable_tracepoint(struct tracepoint *elem)
+static void disable_tracepoint(struct lttng_ust_tracepoint *elem)
+{
+ CMM_STORE_SHARED(elem->state, 0);
+ lttng_ust_rcu_assign_pointer(elem->probes, NULL);
+}
+
+/*
+ * Add the callsite to the callsite hash table. Must be called with
+ * tracepoint mutex held.
+ */
+static void add_callsite(struct tracepoint_lib * lib, struct lttng_ust_tracepoint *tp)
+{
+ struct cds_hlist_head *head;
+ struct callsite_entry *e;
+ const char *name = tp->name;
+ size_t name_len = strlen(name);
+ uint32_t hash;
+ struct tracepoint_entry *tp_entry;
+
+ if (name_len > LTTNG_UST_SYM_NAME_LEN - 1) {
+ WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name, LTTNG_UST_SYM_NAME_LEN - 1);
+ name_len = LTTNG_UST_SYM_NAME_LEN - 1;
+ }
+ hash = jhash(name, name_len, 0);
+ head = &callsite_table[hash & (CALLSITE_TABLE_SIZE - 1)];
+ e = zmalloc(sizeof(struct callsite_entry));
+ if (!e) {
+ PERROR("Unable to add callsite for tracepoint \"%s\"", name);
+ return;
+ }
+ cds_hlist_add_head(&e->hlist, head);
+ e->tp = tp;
+ cds_list_add(&e->node, &lib->callsites);
+
+ tp_entry = get_tracepoint(name);
+ if (!tp_entry)
+ return;
+ tp_entry->callsite_refcount++;
+ e->tp_entry_callsite_ref = true;
+}
+
+/*
+ * Remove the callsite from the callsite hash table and from lib
+ * callsite list. Must be called with tracepoint mutex held.
+ */
+static void remove_callsite(struct callsite_entry *e)
+{
+ struct tracepoint_entry *tp_entry;
+
+ tp_entry = get_tracepoint(e->tp->name);
+ if (tp_entry) {
+ if (e->tp_entry_callsite_ref)
+ tp_entry->callsite_refcount--;
+ if (tp_entry->callsite_refcount == 0)
+ disable_tracepoint(e->tp);
+ }
+ cds_hlist_del(&e->hlist);
+ cds_list_del(&e->node);
+ free(e);
+}
+
+/*
+ * Enable/disable all callsites based on the state of a specific
+ * tracepoint entry.
+ * Must be called with tracepoint mutex held.
+ */
+static void tracepoint_sync_callsites(const char *name)
{
- elem->state = 0;
- rcu_assign_pointer(elem->probes, NULL);
+ struct cds_hlist_head *head;
+ struct cds_hlist_node *node;
+ struct callsite_entry *e;
+ size_t name_len = strlen(name);
+ uint32_t hash;
+ struct tracepoint_entry *tp_entry;
+
+ tp_entry = get_tracepoint(name);
+ if (name_len > LTTNG_UST_SYM_NAME_LEN - 1) {
+ WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name, LTTNG_UST_SYM_NAME_LEN - 1);
+ name_len = LTTNG_UST_SYM_NAME_LEN - 1;
+ }
+ hash = jhash(name, name_len, 0);
+ head = &callsite_table[hash & (CALLSITE_TABLE_SIZE - 1)];
+ cds_hlist_for_each_entry(e, node, head, hlist) {
+ struct lttng_ust_tracepoint *tp = e->tp;
+
+ if (strncmp(name, tp->name, LTTNG_UST_SYM_NAME_LEN - 1))
+ continue;
+ if (tp_entry) {
+ if (!e->tp_entry_callsite_ref) {
+ tp_entry->callsite_refcount++;
+ e->tp_entry_callsite_ref = true;
+ }
+ set_tracepoint(&tp_entry, tp,
+ !!tp_entry->refcount);
+ } else {
+ disable_tracepoint(tp);
+ e->tp_entry_callsite_ref = false;
+ }
+ }
}
/**
* Updates the probe callback corresponding to a range of tracepoints.
*/
static
-void tracepoint_update_probe_range(struct tracepoint * const *begin,
- struct tracepoint * const *end)
+void tracepoint_update_probe_range(struct lttng_ust_tracepoint * const *begin,
+ struct lttng_ust_tracepoint * const *end)
{
- struct tracepoint * const *iter;
+ struct lttng_ust_tracepoint * const *iter;
struct tracepoint_entry *mark_entry;
for (iter = begin; iter < end; iter++) {
}
}
-static void lib_update_tracepoints(void)
+static void lib_update_tracepoints(struct tracepoint_lib *lib)
{
- struct tracepoint_lib *lib;
+ tracepoint_update_probe_range(lib->tracepoints_start,
+ lib->tracepoints_start + lib->tracepoints_count);
+}
- cds_list_for_each_entry(lib, &libs, list) {
- tracepoint_update_probe_range(lib->tracepoints_start,
- lib->tracepoints_start + lib->tracepoints_count);
+static void lib_register_callsites(struct tracepoint_lib *lib)
+{
+ struct lttng_ust_tracepoint * const *begin;
+ struct lttng_ust_tracepoint * const *end;
+ struct lttng_ust_tracepoint * const *iter;
+
+ begin = lib->tracepoints_start;
+ end = lib->tracepoints_start + lib->tracepoints_count;
+
+ for (iter = begin; iter < end; iter++) {
+ if (!*iter)
+ continue; /* skip dummy */
+ if (!(*iter)->name) {
+ continue;
+ }
+ add_callsite(lib, *iter);
}
}
+static void lib_unregister_callsites(struct tracepoint_lib *lib)
+{
+ struct callsite_entry *callsite, *tmp;
+
+ cds_list_for_each_entry_safe(callsite, tmp, &lib->callsites, node)
+ remove_callsite(callsite);
+}
+
/*
* Update probes, removing the faulty probes.
*/
static void tracepoint_update_probes(void)
{
+ struct tracepoint_lib *lib;
+
/* tracepoints registered from libraries and executable. */
- lib_update_tracepoints();
+ cds_list_for_each_entry(lib, &libs, list)
+ lib_update_tracepoints(lib);
}
-static struct tracepoint_probe *
-tracepoint_add_probe(const char *name, void *probe, void *data)
+static struct lttng_ust_tracepoint_probe *
+tracepoint_add_probe(const char *name, void (*probe)(void), void *data,
+ const char *signature)
{
struct tracepoint_entry *entry;
- struct tracepoint_probe *old;
+ struct lttng_ust_tracepoint_probe *old;
entry = get_tracepoint(name);
- if (!entry) {
- entry = add_tracepoint(name);
+ if (entry) {
+ if (strcmp(entry->signature, signature) != 0) {
+ ERR("Tracepoint and probe signature do not match.");
+ return ERR_PTR(-EINVAL);
+ }
+ } else {
+ entry = add_tracepoint(name, signature);
if (IS_ERR(entry))
- return (struct tracepoint_probe *)entry;
+ return (struct lttng_ust_tracepoint_probe *)entry;
}
old = tracepoint_entry_add_probe(entry, probe, data);
if (IS_ERR(old) && !entry->refcount)
return old;
}
+static void tracepoint_release_queue_add_old_probes(void *old)
+{
+ release_queue_need_update = 1;
+ if (old) {
+ struct tp_probes *tp_probes = caa_container_of(old,
+ struct tp_probes, probes[0]);
+ cds_list_add(&tp_probes->u.list, &release_queue);
+ }
+}
+
/**
* __tracepoint_probe_register - Connect a probe to a tracepoint
* @name: tracepoint name
*
* Returns 0 if ok, error value on error.
* The probe address must at least be aligned on the architecture pointer size.
- * Called with the UST lock held.
+ * Called with the tracepoint mutex held.
*/
-int __tracepoint_probe_register(const char *name, void *probe, void *data)
+int __tracepoint_probe_register(const char *name, void (*probe)(void),
+ void *data, const char *signature)
{
void *old;
+ int ret = 0;
- old = tracepoint_add_probe(name, probe, data);
- if (IS_ERR(old))
- return PTR_ERR(old);
+ DBG("Registering probe to tracepoint %s", name);
+
+ pthread_mutex_lock(&tracepoint_mutex);
+ old = tracepoint_add_probe(name, probe, data, signature);
+ if (IS_ERR(old)) {
+ ret = PTR_ERR(old);
+ goto end;
+ }
- tracepoint_update_probes(); /* may update entry */
+ tracepoint_sync_callsites(name);
release_probes(old);
- return 0;
+end:
+ pthread_mutex_unlock(&tracepoint_mutex);
+ return ret;
}
-static void *tracepoint_remove_probe(const char *name, void *probe, void *data)
+/*
+ * Caller needs to invoke __tracepoint_probe_release_queue() after
+ * calling __tracepoint_probe_register_queue_release() one or multiple
+ * times to ensure it does not leak memory.
+ */
+int __tracepoint_probe_register_queue_release(const char *name,
+ void (*probe)(void), void *data, const char *signature)
+{
+ void *old;
+ int ret = 0;
+
+ DBG("Registering probe to tracepoint %s. Queuing release.", name);
+
+ pthread_mutex_lock(&tracepoint_mutex);
+ old = tracepoint_add_probe(name, probe, data, signature);
+ if (IS_ERR(old)) {
+ ret = PTR_ERR(old);
+ goto end;
+ }
+
+ tracepoint_sync_callsites(name);
+ tracepoint_release_queue_add_old_probes(old);
+end:
+ pthread_mutex_unlock(&tracepoint_mutex);
+ return ret;
+}
+
+static void *tracepoint_remove_probe(const char *name, void (*probe)(void),
+ void *data)
{
struct tracepoint_entry *entry;
void *old;
* @name: tracepoint name
* @probe: probe function pointer
* @probe: probe data pointer
- *
- * Called with the UST lock held.
*/
-int __tracepoint_probe_unregister(const char *name, void *probe, void *data)
+int __tracepoint_probe_unregister(const char *name, void (*probe)(void),
+ void *data)
{
void *old;
+ int ret = 0;
- old = tracepoint_remove_probe(name, probe, data);
- if (IS_ERR(old))
- return PTR_ERR(old);
+ DBG("Un-registering probe from tracepoint %s", name);
- tracepoint_update_probes(); /* may update entry */
+ pthread_mutex_lock(&tracepoint_mutex);
+ old = tracepoint_remove_probe(name, probe, data);
+ if (IS_ERR(old)) {
+ ret = PTR_ERR(old);
+ goto end;
+ }
+ tracepoint_sync_callsites(name);
release_probes(old);
- return 0;
+end:
+ pthread_mutex_unlock(&tracepoint_mutex);
+ return ret;
+}
+
+/*
+ * Caller needs to invoke __tracepoint_probe_release_queue() after
+ * calling __tracepoint_probe_unregister_queue_release() one or multiple
+ * times to ensure it does not leak memory.
+ */
+int __tracepoint_probe_unregister_queue_release(const char *name,
+ void (*probe)(void), void *data)
+{
+ void *old;
+ int ret = 0;
+
+ DBG("Un-registering probe from tracepoint %s. Queuing release.", name);
+
+ pthread_mutex_lock(&tracepoint_mutex);
+ old = tracepoint_remove_probe(name, probe, data);
+ if (IS_ERR(old)) {
+ ret = PTR_ERR(old);
+ goto end;
+ }
+ tracepoint_sync_callsites(name);
+ tracepoint_release_queue_add_old_probes(old);
+end:
+ pthread_mutex_unlock(&tracepoint_mutex);
+ return ret;
+}
+
+void __tracepoint_probe_prune_release_queue(void)
+{
+ CDS_LIST_HEAD(release_probes);
+ struct tp_probes *pos, *next;
+
+ DBG("Release queue of unregistered tracepoint probes.");
+
+ pthread_mutex_lock(&tracepoint_mutex);
+ if (!release_queue_need_update)
+ goto end;
+ if (!cds_list_empty(&release_queue))
+ cds_list_replace_init(&release_queue, &release_probes);
+ release_queue_need_update = 0;
+
+ /* Wait for grace period between all sync_callsites and free. */
+ lttng_ust_synchronize_trace();
+
+ cds_list_for_each_entry_safe(pos, next, &release_probes, u.list) {
+ cds_list_del(&pos->u.list);
+ free(pos);
+ }
+end:
+ pthread_mutex_unlock(&tracepoint_mutex);
}
static void tracepoint_add_old_probes(void *old)
{
need_update = 1;
if (old) {
- struct tp_probes *tp_probes = _ust_container_of(old,
+ struct tp_probes *tp_probes = caa_container_of(old,
struct tp_probes, probes[0]);
cds_list_add(&tp_probes->u.list, &old_probes);
}
* @probe: probe handler
*
* caller must call tracepoint_probe_update_all()
- * Called with the UST lock held.
*/
-int tracepoint_probe_register_noupdate(const char *name, void *probe,
- void *data)
+int tracepoint_probe_register_noupdate(const char *name, void (*probe)(void),
+ void *data, const char *signature)
{
void *old;
+ int ret = 0;
- old = tracepoint_add_probe(name, probe, data);
+ pthread_mutex_lock(&tracepoint_mutex);
+ old = tracepoint_add_probe(name, probe, data, signature);
if (IS_ERR(old)) {
- return PTR_ERR(old);
+ ret = PTR_ERR(old);
+ goto end;
}
tracepoint_add_old_probes(old);
- return 0;
+end:
+ pthread_mutex_unlock(&tracepoint_mutex);
+ return ret;
}
/**
* @probe: probe function pointer
*
* caller must call tracepoint_probe_update_all()
- * Called with the UST lock held.
+ * Called with the tracepoint mutex held.
*/
-int tracepoint_probe_unregister_noupdate(const char *name, void *probe,
+int tracepoint_probe_unregister_noupdate(const char *name, void (*probe)(void),
void *data)
{
void *old;
+ int ret = 0;
+
+ DBG("Un-registering probe from tracepoint %s", name);
+ pthread_mutex_lock(&tracepoint_mutex);
old = tracepoint_remove_probe(name, probe, data);
if (IS_ERR(old)) {
- return PTR_ERR(old);
+ ret = PTR_ERR(old);
+ goto end;
}
tracepoint_add_old_probes(old);
- return 0;
+end:
+ pthread_mutex_unlock(&tracepoint_mutex);
+ return ret;
}
/**
* tracepoint_probe_update_all - update tracepoints
- * Called with the UST lock held.
*/
void tracepoint_probe_update_all(void)
{
CDS_LIST_HEAD(release_probes);
struct tp_probes *pos, *next;
+ pthread_mutex_lock(&tracepoint_mutex);
if (!need_update) {
- return;
+ goto end;
}
if (!cds_list_empty(&old_probes))
cds_list_replace_init(&old_probes, &release_probes);
need_update = 0;
tracepoint_update_probes();
+ /* Wait for grace period between update_probes and free. */
+ lttng_ust_synchronize_trace();
cds_list_for_each_entry_safe(pos, next, &release_probes, u.list) {
cds_list_del(&pos->u.list);
- synchronize_rcu();
free(pos);
}
+end:
+ pthread_mutex_unlock(&tracepoint_mutex);
}
-/*
- * Returns 0 if current not found.
- * Returns 1 if current found.
- *
- * Called with tracepoint mutex held
- */
-int lib_get_iter_tracepoints(struct tracepoint_iter *iter)
-{
- struct tracepoint_lib *iter_lib;
- int found = 0;
-
- cds_list_for_each_entry(iter_lib, &libs, list) {
- if (iter_lib < iter->lib)
- continue;
- else if (iter_lib > iter->lib)
- iter->tracepoint = NULL;
- found = tracepoint_get_iter_range(&iter->tracepoint,
- iter_lib->tracepoints_start,
- iter_lib->tracepoints_start + iter_lib->tracepoints_count);
- if (found) {
- iter->lib = iter_lib;
- break;
- }
- }
- return found;
-}
-
-/**
- * tracepoint_get_iter_range - Get a next tracepoint iterator given a range.
- * @tracepoint: current tracepoints (in), next tracepoint (out)
- * @begin: beginning of the range
- * @end: end of the range
- *
- * Returns whether a next tracepoint has been found (1) or not (0).
- * Will return the first tracepoint in the range if the input tracepoint is
- * NULL.
- * Called with tracepoint mutex held.
- */
-int tracepoint_get_iter_range(struct tracepoint * const **tracepoint,
- struct tracepoint * const *begin, struct tracepoint * const *end)
-{
- if (!*tracepoint && begin != end)
- *tracepoint = begin;
- while (*tracepoint >= begin && *tracepoint < end) {
- if (!**tracepoint)
- (*tracepoint)++; /* skip dummy */
- else
- return 1;
- }
- return 0;
-}
-
-/*
- * Called with tracepoint mutex held.
- */
-static void tracepoint_get_iter(struct tracepoint_iter *iter)
-{
- int found = 0;
-
- /* tracepoints in libs. */
- found = lib_get_iter_tracepoints(iter);
- if (!found)
- tracepoint_iter_reset(iter);
-}
-
-/*
- * Called with UST lock held.
- */
-void tracepoint_iter_start(struct tracepoint_iter *iter)
-{
- tracepoint_get_iter(iter);
-}
-
-/*
- * Called with UST lock held.
- */
-void tracepoint_iter_next(struct tracepoint_iter *iter)
-{
- iter->tracepoint++;
- /*
- * iter->tracepoint may be invalid because we blindly incremented it.
- * Make sure it is valid by marshalling on the tracepoints, getting the
- * tracepoints from following modules if necessary.
- */
- tracepoint_get_iter(iter);
-}
-
-/*
- * Called with UST lock held.
- */
-void tracepoint_iter_stop(struct tracepoint_iter *iter)
-{
-}
-
-void tracepoint_iter_reset(struct tracepoint_iter *iter)
-{
- iter->tracepoint = NULL;
-}
-
-void tracepoint_set_new_tracepoint_cb(void (*cb)(struct tracepoint *))
+void tracepoint_set_new_tracepoint_cb(void (*cb)(struct lttng_ust_tracepoint *))
{
new_tracepoint_cb = cb;
}
-static void new_tracepoints(struct tracepoint * const *start, struct tracepoint * const *end)
+static void new_tracepoints(struct lttng_ust_tracepoint * const *start,
+ struct lttng_ust_tracepoint * const *end)
{
if (new_tracepoint_cb) {
- struct tracepoint * const *t;
+ struct lttng_ust_tracepoint * const *t;
for (t = start; t < end; t++) {
if (*t)
}
}
-int tracepoint_register_lib(struct tracepoint * const *tracepoints_start,
- int tracepoints_count)
+/*
+ * tracepoint_{un,}register_lib is meant to be looked up by instrumented
+ * applications through dlsym(). If found, those can register their
+ * tracepoints, else those tracepoints will not be available for
+ * tracing. The number at the end of those symbols acts as a major
+ * version for tracepoints.
+ *
+ * Older instrumented applications should still work with newer
+ * liblttng-ust, but it is fine that instrumented applications compiled
+ * against recent liblttng-ust headers require a recent liblttng-ust
+ * runtime for those tracepoints to be taken into account.
+ */
+int tracepoint_register_lib(struct lttng_ust_tracepoint * const *tracepoints_start,
+ int tracepoints_count)
{
struct tracepoint_lib *pl, *iter;
init_tracepoint();
pl = (struct tracepoint_lib *) zmalloc(sizeof(struct tracepoint_lib));
-
+ if (!pl) {
+ PERROR("Unable to register tracepoint lib");
+ return -1;
+ }
pl->tracepoints_start = tracepoints_start;
pl->tracepoints_count = tracepoints_count;
+ CDS_INIT_LIST_HEAD(&pl->callsites);
- ust_lock();
+ pthread_mutex_lock(&tracepoint_mutex);
/*
* We sort the libs by struct lib pointer address.
*/
cds_list_add(&pl->list, &libs);
lib_added:
new_tracepoints(tracepoints_start, tracepoints_start + tracepoints_count);
-
- /* TODO: update just the loaded lib */
- lib_update_tracepoints();
- ust_unlock();
+ lib_register_callsites(pl);
+ lib_update_tracepoints(pl);
+ pthread_mutex_unlock(&tracepoint_mutex);
DBG("just registered a tracepoints section from %p and having %d tracepoints",
tracepoints_start, tracepoints_count);
+ if (ust_debug()) {
+ int i;
+
+ for (i = 0; i < tracepoints_count; i++) {
+ DBG("registered tracepoint: %s", tracepoints_start[i]->name);
+ }
+ }
return 0;
}
-int tracepoint_unregister_lib(struct tracepoint * const *tracepoints_start)
+int tracepoint_unregister_lib(struct lttng_ust_tracepoint * const *tracepoints_start)
{
struct tracepoint_lib *lib;
- ust_lock();
+ pthread_mutex_lock(&tracepoint_mutex);
cds_list_for_each_entry(lib, &libs, list) {
- if (lib->tracepoints_start == tracepoints_start) {
- struct tracepoint_lib *lib2free = lib;
- cds_list_del(&lib->list);
- free(lib2free);
- break;
- }
- }
- ust_unlock();
+ if (lib->tracepoints_start != tracepoints_start)
+ continue;
+ cds_list_del(&lib->list);
+ /*
+ * Unregistering a callsite also decreases the
+ * callsite reference count of the corresponding
+ * tracepoint, and disables the tracepoint if
+ * the reference count drops to zero.
+ */
+ lib_unregister_callsites(lib);
+ DBG("just unregistered a tracepoints section from %p",
+ lib->tracepoints_start);
+ free(lib);
+ break;
+ }
+ pthread_mutex_unlock(&tracepoint_mutex);
return 0;
}
+/*
+ * Report in debug message whether the compiler correctly supports weak
+ * hidden symbols. This test checks that the address associated with two
+ * weak symbols with hidden visibility is the same when declared within
+ * two compile units part of the same module.
+ */
+static void check_weak_hidden(void)
+{
+ DBG("Your compiler treats weak symbols with hidden visibility for integer objects as %s between compile units part of the same module.",
+ &__tracepoint_test_symbol1 == lttng_ust_tp_check_weak_hidden1() ?
+ "SAME address" :
+ "DIFFERENT addresses");
+ DBG("Your compiler treats weak symbols with hidden visibility for pointer objects as %s between compile units part of the same module.",
+ &__tracepoint_test_symbol2 == lttng_ust_tp_check_weak_hidden2() ?
+ "SAME address" :
+ "DIFFERENT addresses");
+ DBG("Your compiler treats weak symbols with hidden visibility for 24-byte structure objects as %s between compile units part of the same module.",
+ &__tracepoint_test_symbol3 == lttng_ust_tp_check_weak_hidden3() ?
+ "SAME address" :
+ "DIFFERENT addresses");
+}
+
void init_tracepoint(void)
{
if (uatomic_xchg(&initialized, 1) == 1)
return;
init_usterr();
+ check_weak_hidden();
}
void exit_tracepoint(void)
{
initialized = 0;
}
+
+/*
+ * Create the wrapper symbols.
+ */
+#undef tp_rcu_read_lock
+#undef tp_rcu_read_unlock
+#undef tp_rcu_dereference
+
+void tp_rcu_read_lock(void)
+{
+ lttng_ust_urcu_read_lock();
+}
+
+void tp_rcu_read_unlock(void)
+{
+ lttng_ust_urcu_read_unlock();
+}
+
+void *tp_rcu_dereference_sym(void *p)
+{
+ return lttng_ust_rcu_dereference(p);
+}
+
+/*
+ * Programs that have threads that survive after they exit, and therefore call
+ * library destructors, should disable the tracepoint destructors by calling
+ * tp_disable_destructors(). This will leak the tracepoint
+ * instrumentation library shared object, leaving its teardown to the operating
+ * system process teardown.
+ *
+ * To access and/or modify this value, users need to use a combination of
+ * dlopen(3) and dlsym(3) to get an handle on the
+ * tp_disable_destructors and tp_get_destructors_state symbols below.
+ */
+void tp_disable_destructors(void)
+{
+ uatomic_set(&tracepoint_destructors_state, 0);
+}
+
+/*
+ * Returns 1 if the destructors are enabled and should be executed.
+ * Returns 0 if the destructors are disabled.
+ */
+int tp_get_destructors_state(void)
+{
+ return uatomic_read(&tracepoint_destructors_state);
+}
+
+void lttng_ust_synchronize_trace(void)
+{
+ lttng_ust_urcu_synchronize_rcu();
+}
projects / lttng-ust.git / blobdiff