Add vmalloc sync all calls in ftrace and kprobes modules

[lttng-modules.git] / probes / lttng-ftrace.c

diff --git a/probes/lttng-ftrace.c b/probes/lttng-ftrace.c
index 4b7be18336c07d8b8eecd1f745a64da00a6ebc7a..27f4e2bef81117b6bb1e0dc257b838f1c97162c0 100644 (file)
--- a/probes/lttng-ftrace.c
+++ b/probes/lttng-ftrace.c
@@ -7,15 +7,23 @@
  * Dual LGPL v2.1/GPL v2 license.
  */
 
+/*
+ * Ftrace function tracer does not seem to provide synchronization between probe
+ * teardown and callback execution. Therefore, we make this module permanently
+ * loaded (unloadable).
+ */
+
 #include <linux/module.h>
 #include <linux/ftrace.h>
 #include <linux/slab.h>
 #include "../ltt-events.h"
 #include "../wrapper/ringbuffer/frontend_types.h"
+#include "../wrapper/ftrace.h"
+#include "../wrapper/vmalloc.h"
 #include "../ltt-tracer.h"
 
 static
-int lttng_ftrace_handler(unsigned long ip, unsigned long parent_ip, void **data)
+void lttng_ftrace_handler(unsigned long ip, unsigned long parent_ip, void **data)
 {
        struct ltt_event *event = *data;
        struct ltt_channel *chan = event->chan;
@@ -27,18 +35,18 @@ int lttng_ftrace_handler(unsigned long ip, unsigned long parent_ip, void **data)
        int ret;
 
        if (!ACCESS_ONCE(chan->session->active))
-               return 0;
+               return;
        lib_ring_buffer_ctx_init(&ctx, chan->chan, NULL,
                                 sizeof(payload), ltt_alignof(payload), -1);
        ret = chan->ops->event_reserve(&ctx);
        if (ret < 0)
-               return 0;
+               return;
        payload.ip = ip;
        payload.parent_ip = parent_ip;
        lib_ring_buffer_align_ctx(&ctx, ltt_alignof(payload));
        chan->ops->event_write(&ctx, &payload, sizeof(payload));
        chan->ops->event_commit(&ctx);
-       return 0;
+       return;
 }
 
 /*
@@ -108,7 +116,10 @@ int lttng_ftrace_register(const char *name,
        if (!event->u.ftrace.symbol_name)
                goto name_error;
 
-       ret = register_ftrace_function_probe(symbol_name,
+       /* Ensure the memory we just allocated don't trigger page faults */
+       wrapper_vmalloc_sync_all();
+
+       ret = wrapper_register_ftrace_function_probe(event->u.ftrace.symbol_name,
                        &lttng_ftrace_ops, event);
        if (ret)
                goto register_error;
@@ -126,7 +137,7 @@ EXPORT_SYMBOL_GPL(lttng_ftrace_register);
 
 void lttng_ftrace_unregister(struct ltt_event *event)
 {
-       unregister_ftrace_function_probe(event->u.ftrace.symbol_name,
+       wrapper_unregister_ftrace_function_probe(event->u.ftrace.symbol_name,
                        &lttng_ftrace_ops, event);
        kfree(event->u.ftrace.symbol_name);
        kfree(event->desc->name);
@@ -134,6 +145,14 @@ void lttng_ftrace_unregister(struct ltt_event *event)
 }
 EXPORT_SYMBOL_GPL(lttng_ftrace_unregister);
 
+/* This module is permanent. */
+int lttng_ftrace_init(void)
+{
+       wrapper_vmalloc_sync_all();
+       return 0;
+}
+module_init(lttng_ftrace_init)
+
 MODULE_LICENSE("GPL and additional rights");
 MODULE_AUTHOR("Mathieu Desnoyers");
 MODULE_DESCRIPTION("Linux Trace Toolkit Ftrace Support");