Implement event notifiers for uprobes

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I28ec581f412c1633d0cdb675020ad2c642c6c768

diff --git a/include/lttng/events.h b/include/lttng/events.h
index ff0a48ff1f6b766054edf2b1209fe03b4271a70a..0e04b6ebd3f6e1fdc84ff6b42c9a91caafcc74fc 100644 (file)
--- a/include/lttng/events.h
+++ b/include/lttng/events.h
@@ -272,6 +272,7 @@ struct lttng_enabler_ref {
 struct lttng_uprobe_handler {
        union {
                struct lttng_event *event;
+               struct lttng_event_notifier *event_notifier;
        } u;
        loff_t offset;
        struct uprobe_consumer up_consumer;
@@ -349,6 +350,7 @@ struct lttng_event_notifier {
        enum lttng_kernel_instrumentation instrumentation;
        union {
                struct lttng_kprobe kprobe;
+               struct lttng_uprobe uprobe;
        } u;
 
        /* Backward references: list of lttng_enabler_ref (ref to enablers) */
@@ -1074,6 +1076,9 @@ void lttng_kprobes_destroy_event_notifier_private(struct lttng_event_notifier *e
 int lttng_event_add_callsite(struct lttng_event *event,
        struct lttng_kernel_event_callsite *callsite);
 
+int lttng_event_notifier_add_callsite(struct lttng_event_notifier *event_notifier,
+       struct lttng_kernel_event_callsite *callsite);
+
 #ifdef CONFIG_UPROBES
 int lttng_uprobes_register_event(const char *name,
        int fd, struct lttng_event *event);
@@ -1081,6 +1086,12 @@ int lttng_uprobes_event_add_callsite(struct lttng_event *event,
        struct lttng_kernel_event_callsite *callsite);
 void lttng_uprobes_unregister_event(struct lttng_event *event);
 void lttng_uprobes_destroy_event_private(struct lttng_event *event);
+int lttng_uprobes_register_event_notifier(const char *name,
+       int fd, struct lttng_event_notifier *event_notifier);
+int lttng_uprobes_event_notifier_add_callsite(struct lttng_event_notifier *event_notifier,
+       struct lttng_kernel_event_callsite *callsite);
+void lttng_uprobes_unregister_event_notifier(struct lttng_event_notifier *event_notifier);
+void lttng_uprobes_destroy_event_notifier_private(struct lttng_event_notifier *event_notifier);
 #else
 static inline
 int lttng_uprobes_register_event(const char *name,
@@ -1105,6 +1116,30 @@ static inline
 void lttng_uprobes_destroy_event_private(struct lttng_event *event)
 {
 }
+
+static inline
+int lttng_uprobes_register_event_notifier(const char *name,
+       int fd, struct lttng_event_notifier *event_notifier)
+{
+       return -ENOSYS;
+}
+
+static inline
+int lttng_uprobes_event_notifier_add_callsite(struct lttng_event_notifier *event_notifier,
+       struct lttng_kernel_event_callsite *callsite)
+{
+       return -ENOSYS;
+}
+
+static inline
+void lttng_uprobes_unregister_event_notifier(struct lttng_event_notifier *event_notifier)
+{
+}
+
+static inline
+void lttng_uprobes_destroy_event_notifier_private(struct lttng_event_notifier *event_notifier)
+{
+}
 #endif
 
 #ifdef CONFIG_KRETPROBES

diff --git a/src/lttng-abi.c b/src/lttng-abi.c
index 1407d41bd218de7685fceaa677770f189fb3e437..f9e4422d24ee41b2fde52121e5c7af618e5c710d 100644 (file)
--- a/src/lttng-abi.c
+++ b/src/lttng-abi.c
@@ -1752,6 +1752,18 @@ long lttng_event_notifier_ioctl(struct file *file, unsigned int cmd, unsigned lo
                        WARN_ON_ONCE(1);
                        return -ENOSYS;
                }
+       case LTTNG_KERNEL_ADD_CALLSITE:
+               switch (*evtype) {
+               case LTTNG_TYPE_EVENT:
+                       event_notifier = file->private_data;
+                       return lttng_event_notifier_add_callsite(event_notifier,
+                               (struct lttng_kernel_event_callsite __user *) arg);
+               case LTTNG_TYPE_ENABLER:
+                       return -EINVAL;
+               default:
+                       WARN_ON_ONCE(1);
+                       return -ENOSYS;
+               }
        default:
                return -ENOIOCTLCMD;
        }
@@ -1807,13 +1819,13 @@ int lttng_abi_create_event_notifier(struct file *event_notifier_group_file,
 
        switch (event_notifier_param->event.instrumentation) {
        case LTTNG_KERNEL_TRACEPOINT:
+       case LTTNG_KERNEL_UPROBE:
                break;
        case LTTNG_KERNEL_KPROBE:
                event_notifier_param->event.u.kprobe.symbol_name[LTTNG_KERNEL_SYM_NAME_LEN - 1] = '\0';
                break;
        case LTTNG_KERNEL_KRETPROBE:
-               /* Placing a trigger on kretprobe is not supported. */
-       case LTTNG_KERNEL_UPROBE:
+               /* Placing an event notifier on kretprobe is not supported. */
        case LTTNG_KERNEL_FUNCTION:
        case LTTNG_KERNEL_NOOP:
        case LTTNG_KERNEL_SYSCALL:

diff --git a/src/lttng-events.c b/src/lttng-events.c
index 0e11c5d86fce094ea0ce31c0c9c46f3e3cb11be8..379a7e7e1d4a39a3a574514cbd6c0b5881e88292 100644 (file)
--- a/src/lttng-events.c
+++ b/src/lttng-events.c
@@ -615,11 +615,11 @@ int lttng_event_notifier_enable(struct lttng_event_notifier *event_notifier)
                ret = -EINVAL;
                break;
        case LTTNG_KERNEL_KPROBE:
+       case LTTNG_KERNEL_UPROBE:
                WRITE_ONCE(event_notifier->enabled, 1);
                break;
        case LTTNG_KERNEL_SYSCALL:
        case LTTNG_KERNEL_FUNCTION:
-       case LTTNG_KERNEL_UPROBE:
        case LTTNG_KERNEL_NOOP:
        case LTTNG_KERNEL_KRETPROBE:
        default:
@@ -645,11 +645,11 @@ int lttng_event_notifier_disable(struct lttng_event_notifier *event_notifier)
                ret = -EINVAL;
                break;
        case LTTNG_KERNEL_KPROBE:
+       case LTTNG_KERNEL_UPROBE:
                WRITE_ONCE(event_notifier->enabled, 0);
                break;
        case LTTNG_KERNEL_SYSCALL:
        case LTTNG_KERNEL_FUNCTION:
-       case LTTNG_KERNEL_UPROBE:
        case LTTNG_KERNEL_NOOP:
        case LTTNG_KERNEL_KRETPROBE:
        default:
@@ -1008,9 +1008,9 @@ struct lttng_event_notifier *_lttng_event_notifier_create(
                event_name = event_desc->name;
                break;
        case LTTNG_KERNEL_KPROBE:
+       case LTTNG_KERNEL_UPROBE:
                event_name = event_notifier_param->event.name;
                break;
-       case LTTNG_KERNEL_UPROBE:
        case LTTNG_KERNEL_KRETPROBE:
        case LTTNG_KERNEL_FUNCTION:
        case LTTNG_KERNEL_NOOP:
@@ -1087,6 +1087,28 @@ struct lttng_event_notifier *_lttng_event_notifier_create(
                WARN_ON_ONCE(!ret);
                break;
        case LTTNG_KERNEL_UPROBE:
+               /*
+                * Needs to be explicitly enabled after creation, since
+                * we may want to apply filters.
+                */
+               event_notifier->enabled = 0;
+               event_notifier->registered = 1;
+
+               /*
+                * Populate lttng_event_notifier structure before
+                * event_notifier registration.
+                */
+               smp_wmb();
+
+               ret = lttng_uprobes_register_event_notifier(
+                               event_notifier_param->event.name,
+                               event_notifier_param->event.u.uprobe.fd,
+                               event_notifier);
+               if (ret)
+                       goto register_error;
+               ret = try_module_get(event_notifier->desc->owner);
+               WARN_ON_ONCE(!ret);
+               break;
        case LTTNG_KERNEL_KRETPROBE:
        case LTTNG_KERNEL_FUNCTION:
        case LTTNG_KERNEL_NOOP:
@@ -1236,10 +1258,10 @@ void register_event_notifier(struct lttng_event_notifier *event_notifier)
                                                  event_notifier);
                break;
        case LTTNG_KERNEL_KPROBE:
+       case LTTNG_KERNEL_UPROBE:
                ret = 0;
                break;
        case LTTNG_KERNEL_SYSCALL:
-       case LTTNG_KERNEL_UPROBE:
        case LTTNG_KERNEL_KRETPROBE:
        case LTTNG_KERNEL_FUNCTION:
        case LTTNG_KERNEL_NOOP:
@@ -1271,11 +1293,14 @@ int _lttng_event_notifier_unregister(
                lttng_kprobes_unregister_event_notifier(event_notifier);
                ret = 0;
                break;
+       case LTTNG_KERNEL_UPROBE:
+               lttng_uprobes_unregister_event_notifier(event_notifier);
+               ret = 0;
+               break;
        case LTTNG_KERNEL_KRETPROBE:
        case LTTNG_KERNEL_FUNCTION:
        case LTTNG_KERNEL_SYSCALL:
        case LTTNG_KERNEL_NOOP:
-       case LTTNG_KERNEL_UPROBE:
        default:
                WARN_ON_ONCE(1);
        }
@@ -1332,11 +1357,14 @@ void _lttng_event_notifier_destroy(struct lttng_event_notifier *event_notifier)
                module_put(event_notifier->desc->owner);
                lttng_kprobes_destroy_event_notifier_private(event_notifier);
                break;
+       case LTTNG_KERNEL_UPROBE:
+               module_put(event_notifier->desc->owner);
+               lttng_uprobes_destroy_event_notifier_private(event_notifier);
+               break;
        case LTTNG_KERNEL_KRETPROBE:
        case LTTNG_KERNEL_FUNCTION:
        case LTTNG_KERNEL_NOOP:
        case LTTNG_KERNEL_SYSCALL:
-       case LTTNG_KERNEL_UPROBE:
        default:
                WARN_ON_ONCE(1);
        }
@@ -2270,6 +2298,19 @@ error:
        return ret;
 }
 
+int lttng_event_notifier_add_callsite(struct lttng_event_notifier *event_notifier,
+               struct lttng_kernel_event_callsite __user *callsite)
+{
+
+       switch (event_notifier->instrumentation) {
+       case LTTNG_KERNEL_UPROBE:
+               return lttng_uprobes_event_notifier_add_callsite(event_notifier,
+                               callsite);
+       default:
+               return -EINVAL;
+       }
+}
+
 int lttng_event_notifier_enabler_attach_context(
                struct lttng_event_notifier_enabler *event_notifier_enabler,
                struct lttng_kernel_context *context_param)

diff --git a/src/probes/lttng-uprobes.c b/src/probes/lttng-uprobes.c
index d23653202782318473508ec02e0f088861414d63..368828e350f79cddbb87dde44980457a792cdeff 100644 (file)
--- a/src/probes/lttng-uprobes.c
+++ b/src/probes/lttng-uprobes.c
@@ -63,6 +63,20 @@ int lttng_uprobes_event_handler_pre(struct uprobe_consumer *uc, struct pt_regs *
        return 0;
 }
 
+static
+int lttng_uprobes_event_notifier_handler_pre(struct uprobe_consumer *uc, struct pt_regs *regs)
+{
+       struct lttng_uprobe_handler *uprobe_handler =
+               container_of(uc, struct lttng_uprobe_handler, up_consumer);
+       struct lttng_event_notifier *event_notifier = uprobe_handler->u.event_notifier;
+
+       if (unlikely(!READ_ONCE(event_notifier->enabled)))
+               return 0;
+
+       event_notifier->send_notification(event_notifier);
+       return 0;
+}
+
 /*
  * Create event description.
  */
@@ -111,6 +125,36 @@ error_str:
        return ret;
 }
 
+/*
+ * Create event_notifier description.
+ */
+static
+int lttng_create_uprobe_event_notifier(const char *name, struct lttng_event_notifier *event_notifier)
+{
+       struct lttng_event_desc *desc;
+       int ret;
+
+       desc = kzalloc(sizeof(*event_notifier->desc), GFP_KERNEL);
+       if (!desc)
+               return -ENOMEM;
+       desc->name = kstrdup(name, GFP_KERNEL);
+       if (!desc->name) {
+               ret = -ENOMEM;
+               goto error_str;
+       }
+
+       desc->nr_fields = 0;
+
+       desc->owner = THIS_MODULE;
+       event_notifier->desc = desc;
+
+       return 0;
+
+error_str:
+       kfree(desc);
+       return ret;
+}
+
 /*
  * Returns the inode struct from the current task and an fd. The inode is
  * grabbed by this function and must be put once we are done with it using
@@ -164,7 +208,7 @@ int lttng_uprobes_add_callsite(struct lttng_uprobe *uprobe,
                goto end;
        }
 
-       /* Ensure the memory we just allocated don't trigger page faults. */
+       /* Ensure the memory we just allocated don't event_notifier page faults. */
        wrapper_vmalloc_sync_mappings();
 
        uprobe_handler->u.event = priv_data;
@@ -203,6 +247,14 @@ int lttng_uprobes_event_add_callsite(struct lttng_event *event,
 }
 EXPORT_SYMBOL_GPL(lttng_uprobes_event_add_callsite);
 
+int lttng_uprobes_event_notifier_add_callsite(struct lttng_event_notifier *event_notifier,
+       struct lttng_kernel_event_callsite __user *callsite)
+{
+       return lttng_uprobes_add_callsite(&event_notifier->u.uprobe, callsite,
+               lttng_uprobes_event_notifier_handler_pre, event_notifier);
+}
+EXPORT_SYMBOL_GPL(lttng_uprobes_event_notifier_add_callsite);
+
 static
 int lttng_uprobes_register(struct lttng_uprobe *uprobe, int fd)
 {
@@ -244,7 +296,31 @@ error:
 }
 EXPORT_SYMBOL_GPL(lttng_uprobes_register_event);
 
-void lttng_uprobes_unregister_event(struct lttng_event *event)
+int lttng_uprobes_register_event_notifier(const char *name, int fd,
+               struct lttng_event_notifier *event_notifier)
+{
+       int ret = 0;
+
+       ret = lttng_create_uprobe_event_notifier(name, event_notifier);
+       if (ret)
+               goto error;
+
+       ret = lttng_uprobes_register(&event_notifier->u.uprobe, fd);
+       if (ret)
+               goto register_error;
+
+       return 0;
+
+register_error:
+       kfree(event_notifier->desc->name);
+       kfree(event_notifier->desc);
+error:
+       return ret;
+}
+EXPORT_SYMBOL_GPL(lttng_uprobes_register_event_notifier);
+
+static
+void lttng_uprobes_unregister(struct inode *inode, struct list_head *head)
 {
        struct lttng_uprobe_handler *iter, *tmp;
 
@@ -252,15 +328,26 @@ void lttng_uprobes_unregister_event(struct lttng_event *event)
         * Iterate over the list of handler, remove each handler from the list
         * and free the struct.
         */
-       list_for_each_entry_safe(iter, tmp, &event->u.uprobe.head, node) {
-               wrapper_uprobe_unregister(event->u.uprobe.inode, iter->offset,
-                       &iter->up_consumer);
+       list_for_each_entry_safe(iter, tmp, head, node) {
+               wrapper_uprobe_unregister(inode, iter->offset, &iter->up_consumer);
                list_del(&iter->node);
                kfree(iter);
        }
+
+}
+
+void lttng_uprobes_unregister_event(struct lttng_event *event)
+{
+       lttng_uprobes_unregister(event->u.uprobe.inode, &event->u.uprobe.head);
 }
 EXPORT_SYMBOL_GPL(lttng_uprobes_unregister_event);
 
+void lttng_uprobes_unregister_event_notifier(struct lttng_event_notifier *event_notifier)
+{
+       lttng_uprobes_unregister(event_notifier->u.uprobe.inode, &event_notifier->u.uprobe.head);
+}
+EXPORT_SYMBOL_GPL(lttng_uprobes_unregister_event_notifier);
+
 void lttng_uprobes_destroy_event_private(struct lttng_event *event)
 {
        iput(event->u.uprobe.inode);
@@ -269,6 +356,14 @@ void lttng_uprobes_destroy_event_private(struct lttng_event *event)
 }
 EXPORT_SYMBOL_GPL(lttng_uprobes_destroy_event_private);
 
+void lttng_uprobes_destroy_event_notifier_private(struct lttng_event_notifier *event_notifier)
+{
+       iput(event_notifier->u.uprobe.inode);
+       kfree(event_notifier->desc->name);
+       kfree(event_notifier->desc);
+}
+EXPORT_SYMBOL_GPL(lttng_uprobes_destroy_event_notifier_private);
+
 MODULE_LICENSE("GPL and additional rights");
 MODULE_AUTHOR("Yannick Brosseau");
 MODULE_DESCRIPTION("Linux Trace Toolkit Uprobes Support");