#include <errno.h>
#include <stdint.h>
#include <stddef.h>
+#include <stdio.h>
#include <urcu/arch.h>
#include <urcu-bp.h>
#include <urcu/compiler.h>
#include <lttng/tracepoint.h>
+#include <lttng/ust-abi.h> /* for LTTNG_UST_SYM_NAME_LEN */
#include <usterr-signal-safe.h>
#include <helper.h>
static int initialized;
static void (*new_tracepoint_cb)(struct tracepoint *);
-/* libraries that contain tracepoints (struct tracepoint_lib) */
+/*
+ * 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_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS)
* 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;
int refcount; /* Number of times armed. 0 if disarmed. */
+ const char *signature;
char name[0];
};
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];
};
-static inline void *allocate_probes(int count)
+static void *allocate_probes(int count)
{
struct tp_probes *p = zmalloc(count * sizeof(struct tracepoint_probe)
+ sizeof(struct tp_probes));
return p == NULL ? NULL : p->probes;
}
-static inline void release_probes(void *old)
+static void release_probes(void *old)
{
if (old) {
struct tp_probes *tp_probes = caa_container_of(old,
/*
* 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;
- uint32_t 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;
- uint32_t hash = jhash(name, name_len-1, 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)) {
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.
*/
- e = zmalloc(sizeof(struct tracepoint_entry) + name_len);
+ e = zmalloc(sizeof(struct tracepoint_entry) + name_len + 1);
if (!e)
return ERR_PTR(-ENOMEM);
- memcpy(&e->name[0], name, name_len);
+ memcpy(&e->name[0], name, name_len + 1);
+ e->name[name_len] = '\0';
e->probes = NULL;
e->refcount = 0;
+ e->signature = signature;
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);
static void set_tracepoint(struct tracepoint_entry **entry,
struct 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
}
static struct tracepoint_probe *
-tracepoint_add_probe(const char *name, void *probe, void *data)
+tracepoint_add_probe(const char *name, void *probe, void *data,
+ const char *signature)
{
struct tracepoint_entry *entry;
struct tracepoint_probe *old;
entry = get_tracepoint(name);
if (!entry) {
- entry = add_tracepoint(name);
+ entry = add_tracepoint(name, signature);
if (IS_ERR(entry))
return (struct tracepoint_probe *)entry;
}
*
* 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 *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 */
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)
* @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)
{
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);
+ pthread_mutex_lock(&tracepoint_mutex);
+ old = tracepoint_remove_probe(name, probe, data);
+ if (IS_ERR(old)) {
+ ret = PTR_ERR(old);
+ goto end;
+ }
tracepoint_update_probes(); /* may update entry */
release_probes(old);
- return 0;
+end:
+ pthread_mutex_unlock(&tracepoint_mutex);
+ return ret;
}
static void tracepoint_add_old_probes(void *old)
* @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)
+ 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,
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);
synchronize_rcu();
free(pos);
}
-}
-
-/*
- * Returns 0 if current not found.
- * Returns 1 if current found.
- *
- * Called with UST lock 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 UST lock 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 UST lock 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 library 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;
+end:
+ pthread_mutex_unlock(&tracepoint_mutex);
}
void tracepoint_set_new_tracepoint_cb(void (*cb)(struct tracepoint *))
}
}
+static
+void lib_disable_tracepoints(struct tracepoint * const *begin,
+ struct tracepoint * const *end)
+{
+ struct tracepoint * const *iter;
+
+ for (iter = begin; iter < end; iter++) {
+ if (!*iter)
+ continue; /* skip dummy */
+ disable_tracepoint(*iter);
+ }
+
+}
+
int tracepoint_register_lib(struct tracepoint * const *tracepoints_start,
int tracepoints_count)
{
pl->tracepoints_start = tracepoints_start;
pl->tracepoints_count = tracepoints_count;
- ust_lock();
+ pthread_mutex_lock(&tracepoint_mutex);
/*
* We sort the libs by struct lib pointer address.
*/
/* TODO: update just the loaded lib */
lib_update_tracepoints();
- ust_unlock();
+ 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)
{
struct tracepoint_lib *lib;
+ int tracepoints_count;
- 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);
+ tracepoints_count = lib->tracepoints_count;
free(lib2free);
- break;
+ goto found;
}
}
- ust_unlock();
-
+ goto end;
+found:
+ /*
+ * Force tracepoint disarm for all tracepoints of this lib.
+ * This takes care of destructor of library that would leave a
+ * LD_PRELOAD wrapper override function enabled for tracing, but
+ * the session teardown would not be able to reach the
+ * tracepoint anymore to disable it.
+ */
+ lib_disable_tracepoints(tracepoints_start,
+ tracepoints_start + tracepoints_count);
+ DBG("just unregistered a tracepoints section from %p",
+ tracepoints_start);
+end:
+ pthread_mutex_unlock(&tracepoint_mutex);
return 0;
}
{
initialized = 0;
}
+
+/*
+ * Create the wrapper symbols.
+ */
+#undef tp_rcu_read_lock_bp
+#undef tp_rcu_read_unlock_bp
+#undef tp_rcu_dereference_bp
+
+void tp_rcu_read_lock_bp(void)
+{
+ rcu_read_lock_bp();
+}
+
+void tp_rcu_read_unlock_bp(void)
+{
+ rcu_read_unlock_bp();
+}
+
+void *tp_rcu_dereference_sym_bp(void *p)
+{
+ return rcu_dereference_bp(p);
+}
projects / lttng-ust.git / blobdiff