Fix: Add signature check in tracepoint activation

[lttng-ust.git] / liblttng-ust / tracepoint.c

diff --git a/liblttng-ust/tracepoint.c b/liblttng-ust/tracepoint.c
index 7144fab40003c586a726fff5a6b4544f14d4c36c..a14c8b34303e43dc40be48cd3aefcd89a31c2197 100644 (file)
--- a/liblttng-ust/tracepoint.c
+++ b/liblttng-ust/tracepoint.c
@@ -94,6 +94,7 @@ struct tracepoint_entry {
        struct cds_hlist_node hlist;
        struct tracepoint_probe *probes;
        int refcount;   /* Number of times armed. 0 if disarmed. */
+       const char *signature;
        char name[0];
 };
 
@@ -243,7 +244,8 @@ static struct tracepoint_entry *get_tracepoint(const char *name)
  * Add the tracepoint to the tracepoint hash table. Must be called with
  * tracepoint mutex held.
  */
-static struct tracepoint_entry *add_tracepoint(const char *name)
+static struct tracepoint_entry *add_tracepoint(const char *name,
+               const char *signature)
 {
        struct cds_hlist_head *head;
        struct cds_hlist_node *node;
@@ -274,6 +276,7 @@ static struct tracepoint_entry *add_tracepoint(const char *name)
        e->name[name_len] = '\0';
        e->probes = NULL;
        e->refcount = 0;
+       e->signature = signature;
        cds_hlist_add_head(&e->hlist, head);
        return e;
 }
@@ -295,6 +298,23 @@ static void set_tracepoint(struct tracepoint_entry **entry,
        struct 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
@@ -370,14 +390,15 @@ static void tracepoint_update_probes(void)
 }
 
 static struct tracepoint_probe *
-tracepoint_add_probe(const char *name, void *probe, void *data)
+tracepoint_add_probe(const char *name, void *probe, void *data,
+               const char *signature)
 {
        struct tracepoint_entry *entry;
        struct tracepoint_probe *old;
 
        entry = get_tracepoint(name);
        if (!entry) {
-               entry = add_tracepoint(name);
+               entry = add_tracepoint(name, signature);
                if (IS_ERR(entry))
                        return (struct tracepoint_probe *)entry;
        }
@@ -396,7 +417,8 @@ tracepoint_add_probe(const char *name, void *probe, void *data)
  * 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 *data)
+int __tracepoint_probe_register(const char *name, void *probe, void *data,
+               const char *signature)
 {
        void *old;
        int ret = 0;
@@ -404,7 +426,7 @@ int __tracepoint_probe_register(const char *name, void *probe, void *data)
        DBG("Registering probe to tracepoint %s", name);
 
        pthread_mutex_lock(&tracepoint_mutex);
-       old = tracepoint_add_probe(name, probe, data);
+       old = tracepoint_add_probe(name, probe, data, signature);
        if (IS_ERR(old)) {
                ret = PTR_ERR(old);
                goto end;
@@ -477,13 +499,13 @@ static void tracepoint_add_old_probes(void *old)
  * caller must call tracepoint_probe_update_all()
  */
 int tracepoint_probe_register_noupdate(const char *name, void *probe,
-                                      void *data)
+                                      void *data, const char *signature)
 {
        void *old;
        int ret = 0;
 
        pthread_mutex_lock(&tracepoint_mutex);
-       old = tracepoint_add_probe(name, probe, data);
+       old = tracepoint_add_probe(name, probe, data, signature);
        if (IS_ERR(old)) {
                ret = PTR_ERR(old);
                goto end;