From 57105fc258cabb75b3a579aaba53b2024fd340e0 Mon Sep 17 00:00:00 2001
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Fri, 29 Jul 2011 12:06:10 -0400
Subject: [PATCH] Add calibration ioctl

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---
 Makefile          |  2 +-
 ltt-debugfs-abi.c | 14 ++++++++++++++
 ltt-debugfs-abi.h | 15 +++++++++++++++
 ltt-events.h      |  2 ++
 lttng-calibrate.c | 28 ++++++++++++++++++++++++++++
 5 files changed, 60 insertions(+), 1 deletion(-)
 create mode 100644 lttng-calibrate.c

diff --git a/Makefile b/Makefile
index e93792c8..07c32268 100644
--- a/Makefile
+++ b/Makefile
@@ -19,7 +19,7 @@ ltt-relay-objs :=  ltt-events.o ltt-debugfs-abi.o \
 			lttng-context-prio.o lttng-context-nice.o \
 			lttng-context-vpid.o lttng-context-tid.o \
 			lttng-context-vtid.o lttng-context-ppid.o \
-			lttng-context-vppid.o
+			lttng-context-vppid.o lttng-calibrate.o
 
 ifneq ($(CONFIG_PERF_EVENTS),)
 ltt-relay-objs += $(shell \
diff --git a/ltt-debugfs-abi.c b/ltt-debugfs-abi.c
index a5f8e7ac..31465d83 100644
--- a/ltt-debugfs-abi.c
+++ b/ltt-debugfs-abi.c
@@ -220,6 +220,20 @@ long lttng_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	case LTTNG_KERNEL_WAIT_QUIESCENT:
 		synchronize_trace();
 		return 0;
+	case LTTNG_KERNEL_CALIBRATE:
+	{
+		struct lttng_calibrate __user *ucalibrate =
+			(struct lttng_calibrate __user *) arg;
+		struct lttng_calibrate calibrate;
+		int ret;
+
+		if (copy_from_user(&calibrate, ucalibrate, sizeof(calibrate)))
+			return -EFAULT;
+		ret = lttng_calibrate(&calibrate);
+		if (copy_to_user(ucalibrate, &calibrate, sizeof(calibrate)))
+			return -EFAULT;
+		return ret;
+	}
 	default:
 		return -ENOIOCTLCMD;
 	}
diff --git a/ltt-debugfs-abi.h b/ltt-debugfs-abi.h
index 3b8e72ea..3a2b81f1 100644
--- a/ltt-debugfs-abi.h
+++ b/ltt-debugfs-abi.h
@@ -81,6 +81,19 @@ struct lttng_kernel_tracer_version {
 	uint32_t sublevel;
 };
 
+enum lttng_calibrate_type {
+	LTTNG_CALIBRATE_KRETPROBE,
+};
+
+struct lttng_calibrate {
+	enum lttng_calibrate_type type;	/* type (input) */
+	union {
+		struct {
+			uint64_t addr;	/* address to probe (output) */
+		} kretprobe;
+	} u;
+};
+
 enum lttng_kernel_context_type {
 	LTTNG_KERNEL_CONTEXT_PID		= 0,
 	LTTNG_KERNEL_CONTEXT_PERF_COUNTER	= 1,
@@ -113,6 +126,8 @@ struct lttng_kernel_context {
 	_IOR(0xF6, 0x41, struct lttng_kernel_tracer_version)
 #define LTTNG_KERNEL_TRACEPOINT_LIST		_IO(0xF6, 0x42)
 #define LTTNG_KERNEL_WAIT_QUIESCENT		_IO(0xF6, 0x43)
+#define LTTNG_KERNEL_CALIBRATE			\
+	_IOWR(0xF6, 0x44, struct lttng_calibrate)
 
 /* Session FD ioctl */
 #define LTTNG_KERNEL_METADATA			\
diff --git a/ltt-events.h b/ltt-events.h
index 6cc4ea3f..525fc982 100644
--- a/ltt-events.h
+++ b/ltt-events.h
@@ -415,6 +415,8 @@ void lttng_ftrace_destroy_private(struct ltt_event *event)
 }
 #endif
 
+int lttng_calibrate(struct lttng_calibrate *calibrate);
+
 extern const struct file_operations lttng_tracepoint_list_fops;
 
 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,35))
diff --git a/lttng-calibrate.c b/lttng-calibrate.c
new file mode 100644
index 00000000..45c01e32
--- /dev/null
+++ b/lttng-calibrate.c
@@ -0,0 +1,28 @@
+/*
+ * lttng-calibrate.c
+ *
+ * Copyright 2011 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng probe calibration.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include "ltt-debugfs-abi.h"
+#include "ltt-events.h"
+
+void lttng_calibrate_kretprobe(void)
+{
+}
+
+int lttng_calibrate(struct lttng_calibrate *calibrate)
+{
+	switch (calibrate->type) {
+	case LTTNG_CALIBRATE_KRETPROBE:
+		calibrate->u.kretprobe.addr = &lttng_calibrate_kretprobe;
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
-- 
2.34.1