From: Michael Jeanson <mjeanson@efficios.com>
Date: Thu, 25 May 2017 20:56:52 +0000 (-0400)
Subject: Fix: update ftrace probe for kernel 4.12
X-Git-Tag: v2.10.0-rc2~3
X-Git-Url: http://git.liburcu.org/?p=lttng-modules.git;a=commitdiff_plain;h=6fddace8d3387e9c95d1f9a1c1454cf38a89f736

Fix: update ftrace probe for kernel 4.12

Follow changes introduced by Linux upstream commits:
  ec19b85913486993d7d6f747beed1a711afd47d8
  bca6c8d0480a8aa5c86f8f416db96c71f6b79e29
  b5f081b563a6cdcb85a543df8c851951a8978275
  6e4443199e5354255e8a4c1e8e5cfc8ef064c3ce

Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/probes/Kbuild b/probes/Kbuild
index 2f6c7c76..fe869d05 100644
--- a/probes/Kbuild
+++ b/probes/Kbuild
@@ -259,7 +259,21 @@ ifneq ($(CONFIG_KRETPROBES),)
 endif # CONFIG_KRETPROBES
 
 ifneq ($(CONFIG_DYNAMIC_FTRACE),)
-  obj-$(CONFIG_LTTNG) += lttng-ftrace.o
+  ftrace_dep = $(srctree)/kernel/trace/trace.h
+  ftrace_dep_check = $(wildcard $(ftrace_dep))
+  ftrace = $(shell \
+    if [ $(VERSION) -ge 5 -o \( $(VERSION) -eq 4 -a $(PATCHLEVEL) -ge 12 \) ] ; then \
+      if [ -z "$(ftrace_dep_check)" ] ; then \
+        echo "warn" ; \
+        exit ; \
+      fi; \
+      echo "lttng-ftrace.o" ; \
+    fi;)
+  ifeq ($(ftrace),warn)
+    $(warning Files $(ftrace_dep) not found. Probe "ftrace" is disabled. Use full kernel source tree to enable it.)
+    ftrace =
+  endif # $(ftrace),warn
+  obj-$(CONFIG_LTTNG) += $(ftrace)
 endif # CONFIG_DYNAMIC_FTRACE
 
 # vim:syntax=make
diff --git a/probes/lttng-ftrace.c b/probes/lttng-ftrace.c
index d8523198..9ec326ee 100644
--- a/probes/lttng-ftrace.c
+++ b/probes/lttng-ftrace.c
@@ -39,6 +39,45 @@
 #include <wrapper/vmalloc.h>
 #include <lttng-tracer.h>
 
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,12,0))
+static
+void lttng_ftrace_handler(unsigned long ip, unsigned long parent_ip,
+		struct trace_array *tr, struct ftrace_probe_ops *ops,
+		void *data)
+{
+	struct lttng_event *event = data;
+	struct lttng_probe_ctx lttng_probe_ctx = {
+		.event = event,
+		.interruptible = !irqs_disabled(),
+	};
+	struct lttng_channel *chan = event->chan;
+	struct lib_ring_buffer_ctx ctx;
+	struct {
+		unsigned long ip;
+		unsigned long parent_ip;
+	} payload;
+	int ret;
+
+	if (unlikely(!ACCESS_ONCE(chan->session->active)))
+		return;
+	if (unlikely(!ACCESS_ONCE(chan->enabled)))
+		return;
+	if (unlikely(!ACCESS_ONCE(event->enabled)))
+		return;
+
+	lib_ring_buffer_ctx_init(&ctx, chan->chan, &lttng_probe_ctx,
+				 sizeof(payload), lttng_alignof(payload), -1);
+	ret = chan->ops->event_reserve(&ctx, event->id);
+	if (ret < 0)
+		return;
+	payload.ip = ip;
+	payload.parent_ip = parent_ip;
+	lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload));
+	chan->ops->event_write(&ctx, &payload, sizeof(payload));
+	chan->ops->event_commit(&ctx);
+	return;
+}
+#else
 static
 void lttng_ftrace_handler(unsigned long ip, unsigned long parent_ip, void **data)
 {
@@ -74,6 +113,7 @@ void lttng_ftrace_handler(unsigned long ip, unsigned long parent_ip, void **data
 	chan->ops->event_commit(&ctx);
 	return;
 }
+#endif
 
 /*
  * Create event description
diff --git a/wrapper/ftrace.h b/wrapper/ftrace.h
index 5a964387..de618734 100644
--- a/wrapper/ftrace.h
+++ b/wrapper/ftrace.h
@@ -26,6 +26,10 @@
  */
 
 #include <linux/ftrace.h>
+#include <linux/version.h>
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,12,0))
+#include <../kernel/trace/trace.h>
+#endif
 
 #ifdef CONFIG_KALLSYMS