From: Michael Jeanson Date: Thu, 8 Apr 2021 21:08:47 +0000 (-0400) Subject: Move liblttng-ust-tracepoint to 'src/lib/' X-Git-Tag: v2.13.0-rc1~111 X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=8f51c684b1c9fde5d26b24515c03c04e8e4be515;p=lttng-ust.git Move liblttng-ust-tracepoint to 'src/lib/' Change-Id: I589e48d787e4a72c0511746bde5d5f43d9d2633e Signed-off-by: Michael Jeanson Signed-off-by: Mathieu Desnoyers --- diff --git a/.gitignore b/.gitignore index b836c4c2..f409ce70 100644 --- a/.gitignore +++ b/.gitignore @@ -143,6 +143,7 @@ cscope.* /src/lib/lttng-ust-java-agent/jni/log4j/Makefile /src/lib/lttng-ust-java/Makefile /src/lib/lttng-ust-libc-wrapper/Makefile +/src/lib/lttng-ust-tracepoint/Makefile /src/lib/lttng-ust-python-agent/Makefile /src/lib/Makefile /src/lib/lttng-ust/Makefile diff --git a/configure.ac b/configure.ac index 89b909af..be707b0f 100644 --- a/configure.ac +++ b/configure.ac @@ -537,6 +537,7 @@ AC_CONFIG_FILES([ src/lib/lttng-ust-java-agent/Makefile src/lib/lttng-ust-java/Makefile src/lib/lttng-ust-libc-wrapper/Makefile + src/lib/lttng-ust-tracepoint/Makefile src/lib/lttng-ust/Makefile src/lib/lttng-ust-python-agent/Makefile src/lib/Makefile diff --git a/src/common/Makefile.am b/src/common/Makefile.am index f5345041..078ec9ee 100644 --- a/src/common/Makefile.am +++ b/src/common/Makefile.am @@ -24,6 +24,7 @@ noinst_HEADERS = \ patient.h \ procname.h \ safe-snprintf.h \ + tracepoint.h \ wait.h noinst_HEADERS += \ diff --git a/src/common/tracepoint.h b/src/common/tracepoint.h new file mode 100644 index 00000000..11c2b8f3 --- /dev/null +++ b/src/common/tracepoint.h @@ -0,0 +1,26 @@ +/* + * SPDX-License-Identifier: LGPL-2.1-only + * + * Copyright (C) 2011 Mathieu Desnoyers + */ + +#ifndef _UST_COMMON_TRACEPOINT_H +#define _UST_COMMON_TRACEPOINT_H + +#define TRACE_DEFAULT TRACE_DEBUG_LINE + +/* + * These symbols are ABI between liblttng-ust-tracepoint and liblttng-ust, + * which is why they are not hidden and not part of the public API. + */ +int lttng_ust_tp_probe_register_queue_release(const char *name, + void (*func)(void), void *data, const char *signature); +int lttng_ust_tp_probe_unregister_queue_release(const char *name, + void (*func)(void), void *data); +void lttng_ust_tp_probe_prune_release_queue(void); + +void lttng_ust_tp_init(void); +void lttng_ust_tp_exit(void); + + +#endif /* _UST_COMMON_TRACEPOINT_H */ diff --git a/src/lib/Makefile.am b/src/lib/Makefile.am index 0a27437b..49fbd75d 100644 --- a/src/lib/Makefile.am +++ b/src/lib/Makefile.am @@ -2,6 +2,7 @@ SUBDIRS = \ lttng-ust-common \ + lttng-ust-tracepoint \ lttng-ust \ lttng-ust-ctl \ lttng-ust-fd \ diff --git a/src/lib/lttng-ust-tracepoint/Makefile.am b/src/lib/lttng-ust-tracepoint/Makefile.am new file mode 100644 index 00000000..e4f274d8 --- /dev/null +++ b/src/lib/lttng-ust-tracepoint/Makefile.am @@ -0,0 +1,16 @@ +# SPDX-License-Identifier: LGPL-2.1-only + +lib_LTLIBRARIES = liblttng-ust-tracepoint.la + +liblttng_ust_tracepoint_la_SOURCES = \ + tracepoint.c \ + tracepoint.h \ + tracepoint-weak-test.c + +liblttng_ust_tracepoint_la_LIBADD = \ + $(top_builddir)/src/lib/lttng-ust-common/liblttng-ust-common.la \ + $(top_builddir)/src/common/libcommon.la \ + $(DL_LIBS) + +liblttng_ust_tracepoint_la_LDFLAGS = -no-undefined -version-info $(LTTNG_UST_LIBRARY_VERSION) +liblttng_ust_tracepoint_la_CFLAGS = -DUST_COMPONENT="liblttng_ust_tracepoint" $(AM_CFLAGS) diff --git a/src/lib/lttng-ust-tracepoint/tracepoint-weak-test.c b/src/lib/lttng-ust-tracepoint/tracepoint-weak-test.c new file mode 100644 index 00000000..fcfb5838 --- /dev/null +++ b/src/lib/lttng-ust-tracepoint/tracepoint-weak-test.c @@ -0,0 +1,29 @@ +/* + * SPDX-License-Identifier: LGPL-2.1-only + * + * Copyright (C) 2016 Mathieu Desnoyers + */ + +#include "lib/lttng-ust-tracepoint/tracepoint.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"))); + +void *lttng_ust_tp_check_weak_hidden1(void) +{ + return &__tracepoint_test_symbol1; +} + +void *lttng_ust_tp_check_weak_hidden2(void) +{ + return &__tracepoint_test_symbol2; +} + +void *lttng_ust_tp_check_weak_hidden3(void) +{ + return &__tracepoint_test_symbol3; +} diff --git a/src/lib/lttng-ust-tracepoint/tracepoint.c b/src/lib/lttng-ust-tracepoint/tracepoint.c new file mode 100644 index 00000000..03e1e0bb --- /dev/null +++ b/src/lib/lttng-ust-tracepoint/tracepoint.c @@ -0,0 +1,1020 @@ +/* + * SPDX-License-Identifier: LGPL-2.1-only + * + * Copyright (C) 2008-2011 Mathieu Desnoyers + * Copyright (C) 2009 Pierre-Marc Fournier + * + * Ported to userspace by Pierre-Marc Fournier. + */ + +#define _LGPL_SOURCE +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include + +#include +#include /* for LTTNG_UST_ABI_SYM_NAME_LEN */ + +#include "common/logging.h" +#include "common/macros.h" + +#include "lib/lttng-ust-tracepoint/tracepoint.h" +#include "common/tracepoint.h" +#include "common/jhash.h" +#include "common/err-ptr.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; + +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 */ +}; + +/* 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_urcu_synchronize_rcu(); + 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_ABI_SYM_NAME_LEN - 1) { + WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name, LTTNG_UST_ABI_SYM_NAME_LEN - 1); + name_len = LTTNG_UST_ABI_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_ABI_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_ABI_SYM_NAME_LEN - 1) { + WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name, LTTNG_UST_ABI_SYM_NAME_LEN - 1); + name_len = LTTNG_UST_ABI_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_ABI_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_ABI_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_ABI_SYM_NAME_LEN - 1) { + WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name, LTTNG_UST_ABI_SYM_NAME_LEN - 1); + name_len = LTTNG_UST_ABI_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_ABI_SYM_NAME_LEN - 1) { + WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name, LTTNG_UST_ABI_SYM_NAME_LEN - 1); + name_len = LTTNG_UST_ABI_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_ABI_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 lttng_ust_tp_probe_register_queue_release() one or multiple + * times to ensure it does not leak memory. + */ +int lttng_ust_tp_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 lttng_ust_tp_probe_unregister_queue_release() one or multiple + * times to ensure it does not leak memory. + */ +int lttng_ust_tp_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 lttng_ust_tp_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_urcu_synchronize_rcu(); + + 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_urcu_synchronize_rcu(); + 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 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_lib(struct lttng_ust_tracepoint * const *tracepoints_start, + int tracepoints_count); +int tracepoint_register_lib(struct lttng_ust_tracepoint * const *tracepoints_start, + int tracepoints_count) +{ + struct tracepoint_lib *pl, *iter; + + lttng_ust_tp_init(); + + 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 (lttng_ust_logging_debug_enabled()) { + int i; + + for (i = 0; i < tracepoints_count; i++) { + DBG("registered tracepoint: %s", tracepoints_start[i]->name); + } + } + + return 0; +} + +int tracepoint_unregister_lib(struct lttng_ust_tracepoint * const *tracepoints_start); +int tracepoint_unregister_lib(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; +} + +/* + * 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 lttng_ust_tp_init(void) +{ + if (uatomic_xchg(&initialized, 1) == 1) + return; + lttng_ust_logging_init(); + check_weak_hidden(); +} + +void lttng_ust_tp_exit(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); +void tp_rcu_read_lock(void) +{ + lttng_ust_urcu_read_lock(); +} + +void tp_rcu_read_unlock(void); +void tp_rcu_read_unlock(void) +{ + lttng_ust_urcu_read_unlock(); +} + +void *tp_rcu_dereference_sym(void *p); +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); +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); +int tp_get_destructors_state(void) +{ + return uatomic_read(&tracepoint_destructors_state); +} diff --git a/src/lib/lttng-ust-tracepoint/tracepoint.h b/src/lib/lttng-ust-tracepoint/tracepoint.h new file mode 100644 index 00000000..ebc25441 --- /dev/null +++ b/src/lib/lttng-ust-tracepoint/tracepoint.h @@ -0,0 +1,43 @@ +/* + * SPDX-License-Identifier: LGPL-2.1-only + * + * Copyright (C) 2011 Mathieu Desnoyers + */ + +#ifndef _LTTNG_TRACEPOINT_INTERNAL_H +#define _LTTNG_TRACEPOINT_INTERNAL_H + +#include +#include +#include + +struct tracepoint_lib { + struct cds_list_head list; /* list of registered libs */ + struct lttng_ust_tracepoint * const *tracepoints_start; + int tracepoints_count; + struct cds_list_head callsites; +}; + +int tracepoint_probe_register_noupdate(const char *name, + void (*callback)(void), void *priv, + const char *signature) + __attribute__((visibility("hidden"))); + +int tracepoint_probe_unregister_noupdate(const char *name, + void (*callback)(void), void *priv) + __attribute__((visibility("hidden"))); + +void tracepoint_probe_update_all(void) + __attribute__((visibility("hidden"))); + + +void *lttng_ust_tp_check_weak_hidden1(void) + __attribute__((visibility("hidden"))); + +void *lttng_ust_tp_check_weak_hidden2(void) + __attribute__((visibility("hidden"))); + +void *lttng_ust_tp_check_weak_hidden3(void) + __attribute__((visibility("hidden"))); + +#endif /* _LTTNG_TRACEPOINT_INTERNAL_H */ diff --git a/src/lib/lttng-ust/Makefile.am b/src/lib/lttng-ust/Makefile.am index 5fcfb5f5..a935bdbe 100644 --- a/src/lib/lttng-ust/Makefile.am +++ b/src/lib/lttng-ust/Makefile.am @@ -2,23 +2,11 @@ AM_CFLAGS += -I$(srcdir) -fno-strict-aliasing -noinst_LTLIBRARIES = liblttng-ust-runtime.la liblttng-ust-support.la +lib_LTLIBRARIES = liblttng-ust.la -lib_LTLIBRARIES = liblttng-ust-tracepoint.la liblttng-ust.la - -liblttng_ust_tracepoint_la_SOURCES = \ - tracepoint.c \ - tracepoint-weak-test.c \ - tracepoint-internal.h \ - lttng-tracer-core.h - -liblttng_ust_tracepoint_la_LIBADD = \ - $(top_builddir)/src/lib/lttng-ust-common/liblttng-ust-common.la \ - $(top_builddir)/src/common/libcommon.la \ - $(DL_LIBS) - -liblttng_ust_tracepoint_la_LDFLAGS = -no-undefined -version-info $(LTTNG_UST_LIBRARY_VERSION) -liblttng_ust_tracepoint_la_CFLAGS = -DUST_COMPONENT="liblttng_ust_tracepoint" $(AM_CFLAGS) +noinst_LTLIBRARIES = \ + liblttng-ust-runtime.la \ + liblttng-ust-support.la liblttng_ust_runtime_la_SOURCES = \ bytecode.h \ @@ -62,7 +50,6 @@ liblttng_ust_runtime_la_SOURCES = \ ust_lib.h \ context-internal.h \ context-provider-internal.h \ - tracepoint-internal.h \ events.h \ clock.h \ lttng-ust-uuid.h \ @@ -116,7 +103,7 @@ liblttng_ust_la_LIBADD = \ $(top_builddir)/src/lib/lttng-ust-common/liblttng-ust-common.la \ $(top_builddir)/src/common/libustcomm.la \ $(top_builddir)/src/common/libcommon.la \ - liblttng-ust-tracepoint.la \ + $(top_builddir)/src/lib/lttng-ust-tracepoint/liblttng-ust-tracepoint.la \ liblttng-ust-runtime.la liblttng-ust-support.la \ $(DL_LIBS) diff --git a/src/lib/lttng-ust/lttng-context.c b/src/lib/lttng-ust/lttng-context.c index aeafa9fc..26d458a8 100644 --- a/src/lib/lttng-ust/lttng-context.c +++ b/src/lib/lttng-ust/lttng-context.c @@ -18,7 +18,7 @@ #include #include #include -#include "tracepoint-internal.h" +#include "common/tracepoint.h" #include "context-internal.h" diff --git a/src/lib/lttng-ust/lttng-events.c b/src/lib/lttng-ust/lttng-events.c index bff03a8e..1981726f 100644 --- a/src/lib/lttng-ust/lttng-events.c +++ b/src/lib/lttng-ust/lttng-events.c @@ -41,7 +41,7 @@ #include "common/ust-context-provider.h" #include "lttng-ust-uuid.h" -#include "tracepoint-internal.h" +#include "common/tracepoint.h" #include "common/strutils.h" #include "lttng-bytecode.h" #include "lttng-tracer.h" diff --git a/src/lib/lttng-ust/lttng-probes.c b/src/lib/lttng-ust/lttng-probes.c index 7781811b..edc042f3 100644 --- a/src/lib/lttng-ust/lttng-probes.c +++ b/src/lib/lttng-ust/lttng-probes.c @@ -13,7 +13,7 @@ #include #include #include -#include "tracepoint-internal.h" +#include "common/tracepoint.h" #include #include "common/macros.h" #include diff --git a/src/lib/lttng-ust/lttng-ust-abi.c b/src/lib/lttng-ust/lttng-ust-abi.c index 4b876811..b6d49547 100644 --- a/src/lib/lttng-ust/lttng-ust-abi.c +++ b/src/lib/lttng-ust/lttng-ust-abi.c @@ -43,7 +43,7 @@ #include "common/ringbuffer/frontend.h" #include "common/ringbuffer/shm.h" #include "common/counter/counter.h" -#include "tracepoint-internal.h" +#include "common/tracepoint.h" #include "lttng-tracer.h" #include "common/strutils.h" #include "lib/lttng-ust/events.h" diff --git a/src/lib/lttng-ust/lttng-ust-comm.c b/src/lib/lttng-ust/lttng-ust-comm.c index 083de26d..e02cffd2 100644 --- a/src/lib/lttng-ust/lttng-ust-comm.c +++ b/src/lib/lttng-ust/lttng-ust-comm.c @@ -43,7 +43,7 @@ #include "common/ust-fd.h" #include "common/logging.h" #include "common/macros.h" -#include "tracepoint-internal.h" +#include "common/tracepoint.h" #include "lttng-tracer-core.h" #include "common/compat/pthread.h" #include "common/procname.h" diff --git a/src/lib/lttng-ust/tracepoint-internal.h b/src/lib/lttng-ust/tracepoint-internal.h deleted file mode 100644 index a4f8fc42..00000000 --- a/src/lib/lttng-ust/tracepoint-internal.h +++ /dev/null @@ -1,59 +0,0 @@ -/* - * SPDX-License-Identifier: LGPL-2.1-only - * - * Copyright (C) 2011 Mathieu Desnoyers - */ - -#ifndef _LTTNG_TRACEPOINT_INTERNAL_H -#define _LTTNG_TRACEPOINT_INTERNAL_H - -#include -#include -#include - -#define TRACE_DEFAULT TRACE_DEBUG_LINE - -struct tracepoint_lib { - struct cds_list_head list; /* list of registered libs */ - struct lttng_ust_tracepoint * const *tracepoints_start; - int tracepoints_count; - struct cds_list_head callsites; -}; - -int tracepoint_probe_register_noupdate(const char *name, - void (*callback)(void), void *priv, - const char *signature) - __attribute__((visibility("hidden"))); - -int tracepoint_probe_unregister_noupdate(const char *name, - void (*callback)(void), void *priv) - __attribute__((visibility("hidden"))); - -void tracepoint_probe_update_all(void) - __attribute__((visibility("hidden"))); - - -void *lttng_ust_tp_check_weak_hidden1(void) - __attribute__((visibility("hidden"))); - -void *lttng_ust_tp_check_weak_hidden2(void) - __attribute__((visibility("hidden"))); - -void *lttng_ust_tp_check_weak_hidden3(void) - __attribute__((visibility("hidden"))); - -/* - * These symbols are ABI between liblttng-ust-tracepoint and liblttng-ust, - * which is why they are not hidden and not part of the public API. - */ -int lttng_ust_tp_probe_register_queue_release(const char *name, - void (*func)(void), void *data, const char *signature); -int lttng_ust_tp_probe_unregister_queue_release(const char *name, - void (*func)(void), void *data); -void lttng_ust_tp_probe_prune_release_queue(void); - -void lttng_ust_tp_init(void); -void lttng_ust_tp_exit(void); - - -#endif /* _LTTNG_TRACEPOINT_INTERNAL_H */ diff --git a/src/lib/lttng-ust/tracepoint-weak-test.c b/src/lib/lttng-ust/tracepoint-weak-test.c deleted file mode 100644 index abca8319..00000000 --- a/src/lib/lttng-ust/tracepoint-weak-test.c +++ /dev/null @@ -1,29 +0,0 @@ -/* - * SPDX-License-Identifier: LGPL-2.1-only - * - * Copyright (C) 2016 Mathieu Desnoyers - */ - -#include "tracepoint-internal.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"))); - -void *lttng_ust_tp_check_weak_hidden1(void) -{ - return &__tracepoint_test_symbol1; -} - -void *lttng_ust_tp_check_weak_hidden2(void) -{ - return &__tracepoint_test_symbol2; -} - -void *lttng_ust_tp_check_weak_hidden3(void) -{ - return &__tracepoint_test_symbol3; -} diff --git a/src/lib/lttng-ust/tracepoint.c b/src/lib/lttng-ust/tracepoint.c deleted file mode 100644 index 8d89d144..00000000 --- a/src/lib/lttng-ust/tracepoint.c +++ /dev/null @@ -1,1020 +0,0 @@ -/* - * SPDX-License-Identifier: LGPL-2.1-only - * - * Copyright (C) 2008-2011 Mathieu Desnoyers - * Copyright (C) 2009 Pierre-Marc Fournier - * - * Ported to userspace by Pierre-Marc Fournier. - */ - -#define _LGPL_SOURCE -#include -#include -#include -#include - -#include -#include -#include -#include -#include -#include - -#include -#include /* for LTTNG_UST_ABI_SYM_NAME_LEN */ - -#include "common/logging.h" -#include "common/macros.h" - -#include "tracepoint-internal.h" -#include "lttng-tracer-core.h" -#include "common/jhash.h" -#include "common/err-ptr.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; - -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 */ -}; - -/* 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_urcu_synchronize_rcu(); - 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_ABI_SYM_NAME_LEN - 1) { - WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name, LTTNG_UST_ABI_SYM_NAME_LEN - 1); - name_len = LTTNG_UST_ABI_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_ABI_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_ABI_SYM_NAME_LEN - 1) { - WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name, LTTNG_UST_ABI_SYM_NAME_LEN - 1); - name_len = LTTNG_UST_ABI_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_ABI_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_ABI_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_ABI_SYM_NAME_LEN - 1) { - WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name, LTTNG_UST_ABI_SYM_NAME_LEN - 1); - name_len = LTTNG_UST_ABI_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_ABI_SYM_NAME_LEN - 1) { - WARN("Truncating tracepoint name %s which exceeds size limits of %u chars", name, LTTNG_UST_ABI_SYM_NAME_LEN - 1); - name_len = LTTNG_UST_ABI_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_ABI_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 lttng_ust_tp_probe_register_queue_release() one or multiple - * times to ensure it does not leak memory. - */ -int lttng_ust_tp_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 lttng_ust_tp_probe_unregister_queue_release() one or multiple - * times to ensure it does not leak memory. - */ -int lttng_ust_tp_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 lttng_ust_tp_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_urcu_synchronize_rcu(); - - 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_urcu_synchronize_rcu(); - 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 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_lib(struct lttng_ust_tracepoint * const *tracepoints_start, - int tracepoints_count); -int tracepoint_register_lib(struct lttng_ust_tracepoint * const *tracepoints_start, - int tracepoints_count) -{ - struct tracepoint_lib *pl, *iter; - - lttng_ust_tp_init(); - - 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 (lttng_ust_logging_debug_enabled()) { - int i; - - for (i = 0; i < tracepoints_count; i++) { - DBG("registered tracepoint: %s", tracepoints_start[i]->name); - } - } - - return 0; -} - -int tracepoint_unregister_lib(struct lttng_ust_tracepoint * const *tracepoints_start); -int tracepoint_unregister_lib(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; -} - -/* - * 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 lttng_ust_tp_init(void) -{ - if (uatomic_xchg(&initialized, 1) == 1) - return; - lttng_ust_logging_init(); - check_weak_hidden(); -} - -void lttng_ust_tp_exit(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); -void tp_rcu_read_lock(void) -{ - lttng_ust_urcu_read_lock(); -} - -void tp_rcu_read_unlock(void); -void tp_rcu_read_unlock(void) -{ - lttng_ust_urcu_read_unlock(); -} - -void *tp_rcu_dereference_sym(void *p); -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); -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); -int tp_get_destructors_state(void) -{ - return uatomic_read(&tracepoint_destructors_state); -}