kretprobe: implement lttng_kretprobes_match_check

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I7a4584c3fa524664097a262d7b5f74eb93d2a335

diff --git a/include/lttng/events-internal.h b/include/lttng/events-internal.h
index 550c8e45efd1c9f36470a7ec619bae240be61f10..d94d25415798b1727f4603ebdcabfeccac330fbc 100644 (file)
--- a/include/lttng/events-internal.h
+++ b/include/lttng/events-internal.h
@@ -1109,6 +1109,7 @@ void lttng_kretprobes_unregister(struct lttng_kernel_event_common *event);
 void lttng_kretprobes_destroy_private(struct lttng_kernel_event_common *event);
 int lttng_kretprobes_event_enable_state(struct lttng_kernel_event_common *event,
        int enable);
+int lttng_kretprobes_match_check(const char *symbol_name, uint64_t offset, uint64_t addr);
 #else
 static inline
 struct lttng_kernel_event_desc *lttng_create_kretprobes_event_desc(const char *name)
@@ -1141,6 +1142,11 @@ int lttng_kretprobes_event_enable_state(struct lttng_kernel_event_common *event,
 {
        return -ENOSYS;
 }
+static inline
+int lttng_kretprobes_match_check(const char *symbol_name, uint64_t offset, uint64_t addr)
+{
+       return -ENOENT;
+}
 #endif
 
 void lttng_lock_sessions(void);

diff --git a/src/lttng-kretprobes.c b/src/lttng-kretprobes.c
index d59bd0de629565b12b777b000cc3625767878607..54ef1df4bc260990d22a799735fea65f0a0a77fa 100644 (file)
--- a/src/lttng-kretprobes.c
+++ b/src/lttng-kretprobes.c
@@ -184,24 +184,23 @@ error_str:
        return NULL;
 }
 
-int lttng_kretprobes_register(const char *symbol_name,
+static
+int _lttng_kretprobes_register(const char *symbol_name,
                           uint64_t offset,
                           uint64_t addr,
+                          struct lttng_krp *lttng_krp,
+                          kretprobe_handler_t entry_handler,
+                          kretprobe_handler_t exit_handler,
                           struct lttng_kernel_event_common *event_entry,
                           struct lttng_kernel_event_common *event_exit)
 {
        int ret;
-       struct lttng_krp *lttng_krp;
 
        /* Kprobes expects a NULL symbol name if unused */
        if (symbol_name[0] == '\0')
                symbol_name = NULL;
-
-       lttng_krp = kzalloc(sizeof(*lttng_krp), GFP_KERNEL);
-       if (!lttng_krp)
-               goto krp_error;
-       lttng_krp->krp.entry_handler = lttng_kretprobes_handler_entry;
-       lttng_krp->krp.handler = lttng_kretprobes_handler_exit;
+       lttng_krp->krp.entry_handler = entry_handler;
+       lttng_krp->krp.handler = exit_handler;
        if (symbol_name) {
                char *alloc_symbol;
 
@@ -211,8 +210,10 @@ int lttng_kretprobes_register(const char *symbol_name,
                        goto name_error;
                }
                lttng_krp->krp.kp.symbol_name = alloc_symbol;
-               event_entry->priv->u.kretprobe.symbol_name = alloc_symbol;
-               event_exit->priv->u.kretprobe.symbol_name = alloc_symbol;
+               if (event_entry)
+                       event_entry->priv->u.kretprobe.symbol_name = alloc_symbol;
+               if (event_exit)
+                       event_exit->priv->u.kretprobe.symbol_name = alloc_symbol;
        }
        lttng_krp->krp.kp.offset = offset;
        lttng_krp->krp.kp.addr = (void *) (unsigned long) addr;
@@ -220,8 +221,10 @@ int lttng_kretprobes_register(const char *symbol_name,
        /* Allow probe handler to find event structures */
        lttng_krp->event[EVENT_ENTRY] = event_entry;
        lttng_krp->event[EVENT_EXIT] = event_exit;
-       event_entry->priv->u.kretprobe.lttng_krp = lttng_krp;
-       event_exit->priv->u.kretprobe.lttng_krp = lttng_krp;
+       if (event_entry)
+               event_entry->priv->u.kretprobe.lttng_krp = lttng_krp;
+       if (event_exit)
+               event_exit->priv->u.kretprobe.lttng_krp = lttng_krp;
 
        /*
         * Both events must be unregistered before the kretprobe is
@@ -247,6 +250,29 @@ int lttng_kretprobes_register(const char *symbol_name,
 register_error:
        kfree(lttng_krp->krp.kp.symbol_name);
 name_error:
+       return ret;
+}
+
+int lttng_kretprobes_register(const char *symbol_name,
+                          uint64_t offset,
+                          uint64_t addr,
+                          struct lttng_kernel_event_common *event_entry,
+                          struct lttng_kernel_event_common *event_exit)
+{
+       int ret = -ENOMEM;
+       struct lttng_krp *lttng_krp;
+
+       lttng_krp = kzalloc(sizeof(*lttng_krp), GFP_KERNEL);
+       if (!lttng_krp)
+               goto krp_error;
+       ret = _lttng_kretprobes_register(symbol_name, offset, addr, lttng_krp,
+                       lttng_kretprobes_handler_entry, lttng_kretprobes_handler_exit,
+                       event_entry, event_exit);
+       if (ret)
+               goto register_error;
+       return 0;
+
+register_error:
        kfree(lttng_krp);
 krp_error:
        return ret;
@@ -274,6 +300,21 @@ void _lttng_kretprobes_release(struct kref *kref)
        kfree(lttng_krp->krp.kp.symbol_name);
 }
 
+int lttng_kretprobes_match_check(const char *symbol_name, uint64_t offset, uint64_t addr)
+{
+       struct lttng_krp lttng_krp;
+       int ret;
+
+       memset(&lttng_krp, 0, sizeof(lttng_krp));
+       ret = _lttng_kretprobes_register(symbol_name, offset, addr, &lttng_krp, NULL, NULL,
+                       NULL, NULL);
+       if (ret)
+               return -ENOENT;
+       unregister_kretprobe(&lttng_krp.krp);
+       kfree(lttng_krp.krp.kp.symbol_name);
+       return 0;
+}
+
 void lttng_kretprobes_destroy_private(struct lttng_kernel_event_common *event)
 {
        kfree(event->priv->desc->event_name);