+++ /dev/null
-/*
- * 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 <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 <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;
-
-/*
- * If tracepoint_destructors_state = 1, tracepoint destructors are
- * enabled. They are disabled otherwise.
- */
-static int tracepoint_destructors_state = 1;
-
-/*
- * Expose the now deprecated symbol __tracepoints__disable_destructors for
- * backward compatibility of applications built against old versions of
- * lttng-ust. We need to keep __tracepoints__disable_destructors up to date
- * within the new destructor disabling API because old applications read this
- * symbol directly.
- */
-int __tracepoints__disable_destructors __attribute__((weak));
-
-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 tracepoint mutex protects the library tracepoints, the hash table, and
- * the library list.
- * 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 tracepoint mutex themselves.
- */
-
-/*
- * Tracepoint hash table, containing the active tracepoints.
- * Protected by tracepoint mutex.
- */
-#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 tracepoint mutex.
- */
-struct tracepoint_entry {
- struct cds_hlist_node hlist;
- struct lttng_ust_tracepoint_probe *probes;
- int refcount; /* Number of times armed. 0 if disarmed. */
- 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 lttng_ust_tracepoint_probe probes[0];
-};
-
-/*
- * 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 */
-};
-
-static int tracepoint_v1_api_used;
-static void (*lttng_ust_liburcu_bp_synchronize_rcu)(void);
-static void (*lttng_ust_liburcu_bp_rcu_read_lock)(void);
-static void (*lttng_ust_liburcu_bp_rcu_read_unlock)(void);
-void (*lttng_ust_liburcu_bp_before_fork)(void);
-void (*lttng_ust_liburcu_bp_after_fork_parent)(void);
-void (*lttng_ust_liburcu_bp_after_fork_child)(void);
-
-static bool lttng_ust_tracepoint_v1_used(void)
-{
- return uatomic_read(&tracepoint_v1_api_used);
-}
-
-static void lttng_ust_tracepoint_set_v1_used(void)
-{
- if (!lttng_ust_tracepoint_v1_used()) {
- /*
- * Perform dlsym here rather than lazily on first use to
- * eliminate nesting of dynamic loader lock (used within
- * dlsym) inside the ust lock.
- */
- if (!lttng_ust_liburcu_bp_synchronize_rcu) {
- lttng_ust_liburcu_bp_synchronize_rcu = URCU_FORCE_CAST(void (*)(void),
- dlsym(RTLD_DEFAULT, "synchronize_rcu_bp"));
- if (!lttng_ust_liburcu_bp_synchronize_rcu)
- abort();
- }
- if (!lttng_ust_liburcu_bp_before_fork) {
- lttng_ust_liburcu_bp_before_fork = URCU_FORCE_CAST(void (*)(void),
- dlsym(RTLD_DEFAULT, "rcu_bp_before_fork"));
- if (!lttng_ust_liburcu_bp_before_fork)
- abort();
- }
- if (!lttng_ust_liburcu_bp_after_fork_parent) {
- lttng_ust_liburcu_bp_after_fork_parent = URCU_FORCE_CAST(void (*)(void),
- dlsym(RTLD_DEFAULT, "rcu_bp_after_fork_parent"));
- if (!lttng_ust_liburcu_bp_after_fork_parent)
- abort();
- }
- if (!lttng_ust_liburcu_bp_after_fork_child) {
- lttng_ust_liburcu_bp_after_fork_child = URCU_FORCE_CAST(void (*)(void),
- dlsym(RTLD_DEFAULT, "rcu_bp_after_fork_child"));
- if (!lttng_ust_liburcu_bp_after_fork_child)
- abort();
- }
- if (!lttng_ust_liburcu_bp_rcu_read_lock) {
- lttng_ust_liburcu_bp_rcu_read_lock = URCU_FORCE_CAST(void (*)(void),
- dlsym(RTLD_DEFAULT, "rcu_read_lock_bp"));
- if (!lttng_ust_liburcu_bp_rcu_read_lock)
- abort();
- }
- if (!lttng_ust_liburcu_bp_rcu_read_unlock) {
- lttng_ust_liburcu_bp_rcu_read_unlock = URCU_FORCE_CAST(void (*)(void),
- dlsym(RTLD_DEFAULT, "rcu_read_unlock_bp"));
- if (!lttng_ust_liburcu_bp_rcu_read_unlock)
- abort();
- }
-
- /* Fixup URCU bp TLS. */
- lttng_ust_liburcu_bp_rcu_read_lock();
- lttng_ust_liburcu_bp_rcu_read_unlock();
-
- uatomic_set(&tracepoint_v1_api_used, 1);
- }
-}
-
-/* coverity[+alloc] */
-static void *allocate_probes(int count)
-{
- struct tp_probes *p =
- zmalloc(count * sizeof(struct lttng_ust_tracepoint_probe)
- + sizeof(struct tp_probes));
- return p == NULL ? NULL : p->probes;
-}
-
-/* coverity[+free : arg-0] */
-static void release_probes(void *old)
-{
- if (old) {
- struct tp_probes *tp_probes = caa_container_of(old,
- struct tp_probes, probes[0]);
- lttng_ust_synchronize_trace();
- free(tp_probes);
- }
-}
-
-static void debug_print_probes(struct tracepoint_entry *entry)
-{
- int i;
-
- if (!tracepoint_debug || !entry->probes)
- return;
-
- for (i = 0; entry->probes[i].func; i++)
- DBG("Probe %d : %p", i, entry->probes[i].func);
-}
-
-static void *
-tracepoint_entry_add_probe(struct tracepoint_entry *entry,
- void (*probe)(void), void *data)
-{
- int nr_probes = 0;
- 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) {
- /* (N -> N+1), (N != 0, 1) probes */
- for (nr_probes = 0; old[nr_probes].func; nr_probes++)
- if (old[nr_probes].func == probe &&
- old[nr_probes].data == data)
- return ERR_PTR(-EEXIST);
- }
- /* + 2 : one for new probe, one for NULL func */
- new = allocate_probes(nr_probes + 2);
- if (new == NULL)
- return ERR_PTR(-ENOMEM);
- if (old)
- 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;
- entry->refcount = nr_probes + 1;
- entry->probes = new;
- debug_print_probes(entry);
- return old;
-}
-
-static void *
-tracepoint_entry_remove_probe(struct tracepoint_entry *entry,
- void (*probe)(void), void *data)
-{
- int nr_probes = 0, nr_del = 0, i;
- struct lttng_ust_tracepoint_probe *old, *new;
-
- old = entry->probes;
-
- if (!old)
- return ERR_PTR(-ENOENT);
-
- debug_print_probes(entry);
- /* (N -> M), (N > 1, M >= 0) probes */
- 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) {
- /* N -> 0, (N > 1) */
- entry->probes = NULL;
- entry->refcount = 0;
- debug_print_probes(entry);
- return old;
- } else {
- int j = 0;
- /* N -> M, (N > 1, M > 0) */
- /* + 1 for NULL */
- new = allocate_probes(nr_probes - nr_del + 1);
- if (new == NULL)
- return ERR_PTR(-ENOMEM);
- for (i = 0; old[i].func; i++)
- 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;
- entry->probes = new;
- }
- debug_print_probes(entry);
- return old;
-}
-
-/*
- * Get tracepoint if the tracepoint is present in the tracepoint hash table.
- * 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;
- 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 (!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
- * tracepoint mutex held.
- */
-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);
- 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 (!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 elements: name and
- * signature. Could cause some memory fragmentation if overused.
- */
- 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);
- 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
- * tracepoint mutex held.
- */
-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 lttng_ust_tracepoint *elem, int active)
-{
- 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
- * probe callbacks array is consistent before setting a pointer to it.
- * This array is referenced by __DO_TRACE from
- * include/linux/tracepoints.h. A matching cmm_smp_read_barrier_depends()
- * is used.
- */
- lttng_ust_rcu_assign_pointer(elem->probes, (*entry)->probes);
- CMM_STORE_SHARED(elem->state, active);
-}
-
-/*
- * Disable a tracepoint and its probe callback.
- * Note: only waiting an RCU period after setting elem->call to the empty
- * function insures that the original callback is not used anymore. This insured
- * by preempt_disable around the call site.
- */
-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)
-{
- 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;
- }
- }
-}
-
-/**
- * tracepoint_update_probe_range - Update a probe range
- * @begin: beginning of the range
- * @end: end of the range
- *
- * Updates the probe callback corresponding to a range of tracepoints.
- */
-static
-void tracepoint_update_probe_range(struct lttng_ust_tracepoint * const *begin,
- struct lttng_ust_tracepoint * const *end)
-{
- struct lttng_ust_tracepoint * const *iter;
- struct tracepoint_entry *mark_entry;
-
- for (iter = begin; iter < end; iter++) {
- if (!*iter)
- continue; /* skip dummy */
- if (!(*iter)->name) {
- disable_tracepoint(*iter);
- continue;
- }
- mark_entry = get_tracepoint((*iter)->name);
- if (mark_entry) {
- set_tracepoint(&mark_entry, *iter,
- !!mark_entry->refcount);
- } else {
- disable_tracepoint(*iter);
- }
- }
-}
-
-static void lib_update_tracepoints(struct tracepoint_lib *lib)
-{
- 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. */
- cds_list_for_each_entry(lib, &libs, list)
- lib_update_tracepoints(lib);
-}
-
-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 lttng_ust_tracepoint_probe *old;
-
- entry = get_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 lttng_ust_tracepoint_probe *)entry;
- }
- old = tracepoint_entry_add_probe(entry, probe, data);
- if (IS_ERR(old) && !entry->refcount)
- remove_tracepoint(entry);
- 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
- * @probe: probe handler
- *
- * Returns 0 if ok, error value on error.
- * The probe address must at least be aligned on the architecture pointer size.
- * Called with the tracepoint mutex held.
- */
-int __tracepoint_probe_register(const char *name, void (*probe)(void),
- void *data, const char *signature)
-{
- void *old;
- int ret = 0;
-
- 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_sync_callsites(name);
- release_probes(old);
-end:
- pthread_mutex_unlock(&tracepoint_mutex);
- return ret;
-}
-
-/*
- * 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;
-
- entry = get_tracepoint(name);
- if (!entry)
- return ERR_PTR(-ENOENT);
- old = tracepoint_entry_remove_probe(entry, probe, data);
- if (IS_ERR(old))
- return old;
- if (!entry->refcount)
- remove_tracepoint(entry);
- return old;
-}
-
-/**
- * tracepoint_probe_unregister - Disconnect a probe from a tracepoint
- * @name: tracepoint name
- * @probe: probe function pointer
- * @probe: probe data pointer
- */
-int __tracepoint_probe_unregister(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)) {
- ret = PTR_ERR(old);
- goto end;
- }
- tracepoint_sync_callsites(name);
- release_probes(old);
-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 = caa_container_of(old,
- struct tp_probes, probes[0]);
- cds_list_add(&tp_probes->u.list, &old_probes);
- }
-}
-
-/**
- * tracepoint_probe_register_noupdate - register a probe but not connect
- * @name: tracepoint name
- * @probe: probe handler
- *
- * caller must call tracepoint_probe_update_all()
- */
-int tracepoint_probe_register_noupdate(const char *name, void (*probe)(void),
- void *data, const char *signature)
-{
- void *old;
- int ret = 0;
-
- pthread_mutex_lock(&tracepoint_mutex);
- old = tracepoint_add_probe(name, probe, data, signature);
- if (IS_ERR(old)) {
- ret = PTR_ERR(old);
- goto end;
- }
- tracepoint_add_old_probes(old);
-end:
- pthread_mutex_unlock(&tracepoint_mutex);
- return ret;
-}
-
-/**
- * tracepoint_probe_unregister_noupdate - remove a probe but not disconnect
- * @name: tracepoint name
- * @probe: probe function pointer
- *
- * caller must call tracepoint_probe_update_all()
- * Called with the tracepoint mutex held.
- */
-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)) {
- ret = PTR_ERR(old);
- goto end;
- }
- tracepoint_add_old_probes(old);
-end:
- pthread_mutex_unlock(&tracepoint_mutex);
- return ret;
-}
-
-/**
- * tracepoint_probe_update_all - update tracepoints
- */
-void tracepoint_probe_update_all(void)
-{
- CDS_LIST_HEAD(release_probes);
- struct tp_probes *pos, *next;
-
- pthread_mutex_lock(&tracepoint_mutex);
- if (!need_update) {
- 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);
- free(pos);
- }
-end:
- pthread_mutex_unlock(&tracepoint_mutex);
-}
-
-void tracepoint_set_new_tracepoint_cb(void (*cb)(struct lttng_ust_tracepoint *))
-{
- new_tracepoint_cb = cb;
-}
-
-static void new_tracepoints(struct lttng_ust_tracepoint * const *start,
- struct lttng_ust_tracepoint * const *end)
-{
- if (new_tracepoint_cb) {
- struct lttng_ust_tracepoint * const *t;
-
- for (t = start; t < end; t++) {
- if (*t)
- new_tracepoint_cb(*t);
- }
- }
-}
-
-/*
- * 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_lib2(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);
-
- pthread_mutex_lock(&tracepoint_mutex);
- /*
- * We sort the libs by struct lib pointer address.
- */
- cds_list_for_each_entry_reverse(iter, &libs, list) {
- BUG_ON(iter == pl); /* Should never be in the list twice */
- if (iter < pl) {
- /* We belong to the location right after iter. */
- cds_list_add(&pl->list, &iter->list);
- goto lib_added;
- }
- }
- /* We should be added at the head of the list */
- cds_list_add(&pl->list, &libs);
-lib_added:
- new_tracepoints(tracepoints_start, tracepoints_start + tracepoints_count);
- 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;
-}
-
-/* Exposed for backward compatibility with old instrumented applications. */
-int tracepoint_register_lib(struct lttng_ust_tracepoint * const *tracepoints_start,
- int tracepoints_count)
-{
- lttng_ust_tracepoint_set_v1_used();
- return tracepoint_register_lib2(tracepoints_start, tracepoints_count);
-}
-
-int tracepoint_unregister_lib2(struct lttng_ust_tracepoint * const *tracepoints_start)
-{
- struct tracepoint_lib *lib;
-
- pthread_mutex_lock(&tracepoint_mutex);
- cds_list_for_each_entry(lib, &libs, list) {
- 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;
-}
-
-/* Exposed for backward compatibility with old instrumented applications. */
-int tracepoint_unregister_lib(struct lttng_ust_tracepoint * const *tracepoints_start)
-{
- lttng_ust_tracepoint_set_v1_used();
- return tracepoint_unregister_lib2(tracepoints_start);
-}
-
-/*
- * 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();
- /*
- * For legacy tracepoint instrumentation, also wait for urcu-bp
- * grace period.
- */
- if (lttng_ust_liburcu_bp_synchronize_rcu)
- lttng_ust_liburcu_bp_synchronize_rcu();
-}
-
-/*
- * Create the wrapper symbols for legacy v1 API.
- */
-void tp_rcu_read_lock_bp(void)
-{
- lttng_ust_urcu_read_lock();
-}
-
-void tp_rcu_read_unlock_bp(void)
-{
- lttng_ust_urcu_read_unlock();
-}
-
-void *tp_rcu_dereference_sym_bp(void *p)
-{
- return lttng_ust_rcu_dereference(p);
-}
projects / lttng-ust.git / blobdiff