Add support for i2c tracepoints

This patch teaches lttng-modules about the i2c tracepoints in the Linux
kernel.

It contains the following tracepoints:

  * i2c_write
  * i2c_read
  * i2c_reply
  * i2c_result

I translated the fields and assignments from the kernel's
include/trace/events/i2c.h as well as I could.  I also tried building
this module against a kernel without CONFIG_I2C, and it built fine (the
required types are unconditionally defined).  So I don't think any "#if
CONFIG_I2C" or similar are required.

A module parameter (extract_sensitive_payload) controls the extraction
of possibly sensitive data from events.

[ With edit by Mathieu Desnoyers. ]

Signed-off-by: Simon Marchi <simon.marchi@ericsson.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/instrumentation/events/lttng-module/i2c.h b/instrumentation/events/lttng-module/i2c.h
new file mode 100644 (file)
index 0000000..4088b60
--- /dev/null
+++ b/instrumentation/events/lttng-module/i2c.h
@@ -0,0 +1,119 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM i2c
+
+#if !defined(LTTNG_TRACE_I2C_H) || defined(TRACE_HEADER_MULTI_READ)
+#define LTTNG_TRACE_I2C_H
+
+#include <probes/lttng-tracepoint-event.h>
+
+/*
+ * __i2c_transfer() write request
+ */
+LTTNG_TRACEPOINT_EVENT_CODE(i2c_write,
+
+       TP_PROTO(const struct i2c_adapter *adap, const struct i2c_msg *msg,
+               int num),
+
+       TP_ARGS(adap, msg, num),
+
+       TP_locvar(
+               int extract_sensitive_payload;
+       ),
+
+       TP_code_pre(
+               tp_locvar->extract_sensitive_payload =
+                       ACCESS_ONCE(extract_sensitive_payload);
+       ),
+
+       TP_FIELDS(
+               ctf_integer(int, adapter_nr, adap->nr)
+               ctf_integer(__u16, msg_nr, num)
+               ctf_integer(__u16, addr, msg->addr)
+               ctf_integer(__u16, flags, msg->flags)
+               ctf_integer(__u16, len, msg->len)
+               ctf_sequence_hex(__u8, buf,
+                               tp_locvar->extract_sensitive_payload ?
+                               msg->buf : NULL,
+                               __u16,
+                               tp_locvar->extract_sensitive_payload ?
+                               msg->len : 0)
+       ),
+
+       TP_code_post()
+)
+
+/*
+ * __i2c_transfer() read request
+ */
+LTTNG_TRACEPOINT_EVENT(i2c_read,
+
+       TP_PROTO(const struct i2c_adapter *adap, const struct i2c_msg *msg,
+               int num),
+
+       TP_ARGS(adap, msg, num),
+
+       TP_FIELDS(
+               ctf_integer(int, adapter_nr, adap->nr)
+               ctf_integer(__u16, msg_nr, num)
+               ctf_integer(__u16, addr, msg->addr)
+               ctf_integer(__u16, flags, msg->flags)
+               ctf_integer(__u16, len, msg->len)
+       )
+)
+
+/*
+ * __i2c_transfer() read reply
+ */
+LTTNG_TRACEPOINT_EVENT_CODE(i2c_reply,
+
+       TP_PROTO(const struct i2c_adapter *adap, const struct i2c_msg *msg,
+               int num),
+
+       TP_ARGS(adap, msg, num),
+
+       TP_locvar(
+               int extract_sensitive_payload;
+       ),
+
+       TP_code_pre(
+               tp_locvar->extract_sensitive_payload =
+                       ACCESS_ONCE(extract_sensitive_payload);
+       ),
+
+       TP_FIELDS(
+               ctf_integer(int, adapter_nr, adap->nr)
+               ctf_integer(__u16, msg_nr, num)
+               ctf_integer(__u16, addr, msg->addr)
+               ctf_integer(__u16, flags, msg->flags)
+               ctf_integer(__u16, len, msg->len)
+               ctf_sequence_hex(__u8, buf,
+                               tp_locvar->extract_sensitive_payload ?
+                               msg->buf : NULL,
+                               __u16,
+                               tp_locvar->extract_sensitive_payload ?
+                               msg->len : 0)
+       ),
+
+       TP_code_post()
+)
+
+/*
+ * __i2c_transfer() result
+ */
+LTTNG_TRACEPOINT_EVENT(i2c_result,
+
+       TP_PROTO(const struct i2c_adapter *adap, int num, int ret),
+
+       TP_ARGS(adap, num, ret),
+
+       TP_FIELDS(
+               ctf_integer(int, adapter_nr, adap->nr)
+               ctf_integer(__u16, nr_msgs, num)
+               ctf_integer(__s16, ret, ret)
+       )
+)
+
+#endif /*  LTTNG_TRACE_I2C_H */
+
+/* This part must be outside protection */
+#include <probes/define_trace.h>

diff --git a/probes/Kbuild b/probes/Kbuild
index afa3076e07c1c7e6c84786b2358ebfd90cc994d3..bd35bd75c6c57ea3d5f011ee735eeab7f9f61b01 100644 (file)
--- a/probes/Kbuild
+++ b/probes/Kbuild
@@ -5,6 +5,7 @@ include $(TOP_LTTNG_MODULES_DIR)/Makefile.ABI.workarounds
 ccflags-y += -I$(TOP_LTTNG_MODULES_DIR)
 
 obj-$(CONFIG_LTTNG) += lttng-probe-sched.o
+obj-$(CONFIG_LTTNG) += lttng-probe-i2c.o
 obj-$(CONFIG_LTTNG) += lttng-probe-irq.o
 obj-$(CONFIG_LTTNG) += lttng-probe-timer.o
 obj-$(CONFIG_LTTNG) += lttng-probe-kmem.o

diff --git a/probes/lttng-probe-i2c.c b/probes/lttng-probe-i2c.c
new file mode 100644 (file)
index 0000000..d1c1e09
--- /dev/null
+++ b/probes/lttng-probe-i2c.c
@@ -0,0 +1,55 @@
+/*
+ * probes/lttng-probe-i2c.c
+ *
+ * LTTng i2c probes.
+ *
+ * Copyright (C) 2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright (C) 2016 Simon Marchi <simon.marchi@ericsson.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; only
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <lttng-tracer.h>
+
+/*
+ * Create the tracepoint static inlines from the kernel to validate that our
+ * trace event macros match the kernel we run on.
+ */
+#include <trace/events/i2c.h>
+
+/*
+ * Create LTTng tracepoint probes.
+ */
+#define LTTNG_PACKAGE_BUILD
+#define CREATE_TRACE_POINTS
+#define TRACE_INCLUDE_PATH instrumentation/events/lttng-module
+
+static int extract_sensitive_payload;
+module_param(extract_sensitive_payload, int, 0644);
+MODULE_PARM_DESC(extract_sensitive_payload,
+               "Whether to extract possibly sensitive data from events (i2c "
+               "buffer contents) or not (1 or 0, default: 0).");
+
+#include <instrumentation/events/lttng-module/i2c.h>
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Simon Marchi <simon.marchi@ericsson.com>");
+MODULE_DESCRIPTION("LTTng i2c probes");
+MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
+       __stringify(LTTNG_MODULES_MINOR_VERSION) "."
+       __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
+       LTTNG_MODULES_EXTRAVERSION);