lttng: probe callbacks

Implement the LTTng probe callbacks. One notable file here is
lttng-events.h, which is the core implementation of the LTTng
TRACE_EVENT macros for generation of probes and tracepoint decription
from the TRACE_EVENT declarations.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/lttng/probes/Makefile

+#
+# Makefile for the LTT probes.
+#
+
+ccflags-y += -I$(PWD)/probes
+obj-m += lttng-types.o
+
+obj-m += lttng-probe-lttng.o
+
+obj-m += lttng-probe-sched.o
+obj-m += lttng-probe-irq.o
+
+ifneq ($(CONFIG_KVM),)
+obj-m += lttng-probe-kvm.o
+endif
+
+ifneq ($(CONFIG_BLOCK),)
+ifneq ($(CONFIG_EVENT_TRACING),)	# need blk_cmd_buf_len
+obj-m +=  $(shell \
+	if [ $(VERSION) -ge 3 \
+		-o \( $(VERSION) -eq 2 -a $(PATCHLEVEL) -ge 6 -a $(SUBLEVEL) -ge 38 \) ] ; then \
+		echo "lttng-probe-block.o" ; fi;)
+endif
+endif
+
+ifneq ($(CONFIG_KPROBES),)
+obj-m += lttng-kprobes.o
+endif
+
+
+ifneq ($(CONFIG_KRETPROBES),)
+obj-m += lttng-kretprobes.o
+endif
+
+ifneq ($(CONFIG_DYNAMIC_FTRACE),)
+obj-m += lttng-ftrace.o
+endif

drivers/staging/lttng/probes/define_trace.h

+/*
+ * define_trace.h
+ *
+ * Copyright (C) 2009 Steven Rostedt <rostedt@goodmis.org>
+ * Copyright (C) 2010-2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+/*
+ * Trace files that want to automate creationg of all tracepoints defined
+ * in their file should include this file. The following are macros that the
+ * trace file may define:
+ *
+ * TRACE_SYSTEM defines the system the tracepoint is for
+ *
+ * TRACE_INCLUDE_FILE if the file name is something other than TRACE_SYSTEM.h
+ *     This macro may be defined to tell define_trace.h what file to include.
+ *     Note, leave off the ".h".
+ *
+ * TRACE_INCLUDE_PATH if the path is something other than core kernel include/trace
+ *     then this macro can define the path to use. Note, the path is relative to
+ *     define_trace.h, not the file including it. Full path names for out of tree
+ *     modules must be used.
+ */
+
+#ifdef CREATE_TRACE_POINTS
+
+/* Prevent recursion */
+#undef CREATE_TRACE_POINTS
+
+#include <linux/stringify.h>
+/*
+ * module.h includes tracepoints, and because ftrace.h
+ * pulls in module.h:
+ *  trace/ftrace.h -> linux/ftrace_event.h -> linux/perf_event.h ->
+ *  linux/ftrace.h -> linux/module.h
+ * we must include module.h here before we play with any of
+ * the TRACE_EVENT() macros, otherwise the tracepoints included
+ * by module.h may break the build.
+ */
+#include <linux/module.h>
+
+#undef TRACE_EVENT
+#define TRACE_EVENT(name, proto, args, tstruct, assign, print)	\
+	DEFINE_TRACE(name)
+
+#undef TRACE_EVENT_CONDITION
+#define TRACE_EVENT_CONDITION(name, proto, args, cond, tstruct, assign, print) \
+	TRACE_EVENT(name,						\
+		PARAMS(proto),						\
+		PARAMS(args),						\
+		PARAMS(tstruct),					\
+		PARAMS(assign),						\
+		PARAMS(print))
+
+#undef TRACE_EVENT_FN
+#define TRACE_EVENT_FN(name, proto, args, tstruct,		\
+		assign, print, reg, unreg)			\
+	DEFINE_TRACE_FN(name, reg, unreg)
+
+#undef DEFINE_EVENT
+#define DEFINE_EVENT(template, name, proto, args) \
+	DEFINE_TRACE(name)
+
+#undef DEFINE_EVENT_PRINT
+#define DEFINE_EVENT_PRINT(template, name, proto, args, print)	\
+	DEFINE_TRACE(name)
+
+#undef DEFINE_EVENT_CONDITION
+#define DEFINE_EVENT_CONDITION(template, name, proto, args, cond) \
+	DEFINE_EVENT(template, name, PARAMS(proto), PARAMS(args))
+
+#undef DECLARE_TRACE
+#define DECLARE_TRACE(name, proto, args)	\
+	DEFINE_TRACE(name)
+
+#undef TRACE_INCLUDE
+#undef __TRACE_INCLUDE
+
+#ifndef TRACE_INCLUDE_FILE
+# define TRACE_INCLUDE_FILE TRACE_SYSTEM
+# define UNDEF_TRACE_INCLUDE_FILE
+#endif
+
+#ifndef TRACE_INCLUDE_PATH
+# define __TRACE_INCLUDE(system) <trace/events/system.h>
+# define UNDEF_TRACE_INCLUDE_PATH
+#else
+# define __TRACE_INCLUDE(system) __stringify(TRACE_INCLUDE_PATH/system.h)
+#endif
+
+# define TRACE_INCLUDE(system) __TRACE_INCLUDE(system)
+
+/* Let the trace headers be reread */
+#define TRACE_HEADER_MULTI_READ
+
+#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
+
+/* Make all open coded DECLARE_TRACE nops */
+#undef DECLARE_TRACE
+#define DECLARE_TRACE(name, proto, args)
+
+#ifdef LTTNG_PACKAGE_BUILD
+#include "lttng-events.h"
+#endif
+
+#undef TRACE_EVENT
+#undef TRACE_EVENT_FN
+#undef TRACE_EVENT_CONDITION
+#undef DECLARE_EVENT_CLASS
+#undef DEFINE_EVENT
+#undef DEFINE_EVENT_PRINT
+#undef DEFINE_EVENT_CONDITION
+#undef TRACE_HEADER_MULTI_READ
+#undef DECLARE_TRACE
+
+/* Only undef what we defined in this file */
+#ifdef UNDEF_TRACE_INCLUDE_FILE
+# undef TRACE_INCLUDE_FILE
+# undef UNDEF_TRACE_INCLUDE_FILE
+#endif
+
+#ifdef UNDEF_TRACE_INCLUDE_PATH
+# undef TRACE_INCLUDE_PATH
+# undef UNDEF_TRACE_INCLUDE_PATH
+#endif
+
+/* We may be processing more files */
+#define CREATE_TRACE_POINTS
+
+#endif /* CREATE_TRACE_POINTS */

drivers/staging/lttng/probes/lttng-events-reset.h

+/*
+ * lttng-events-reset.h
+ *
+ * Copyright (C) 2010-2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+/* Reset macros used within TRACE_EVENT to "nothing" */
+
+#undef __field_full
+#define __field_full(_type, _item, _order, _base)
+
+#undef __array_enc_ext
+#define __array_enc_ext(_type, _item, _length, _order, _base, _encoding)
+
+#undef __dynamic_array_enc_ext
+#define __dynamic_array_enc_ext(_type, _item, _length, _order, _base, _encoding)
+
+#undef __dynamic_array_len
+#define __dynamic_array_len(_type, _item, _length)
+
+#undef __string
+#define __string(_item, _src)
+
+#undef tp_assign
+#define tp_assign(dest, src)
+
+#undef tp_memcpy
+#define tp_memcpy(dest, src, len)
+
+#undef tp_memcpy_dyn
+#define tp_memcpy_dyn(dest, src, len)
+
+#undef tp_strcpy
+#define tp_strcpy(dest, src)
+
+#undef __get_str
+#define __get_str(field)
+
+#undef __get_dynamic_array
+#define __get_dynamic_array(field)
+
+#undef __get_dynamic_array_len
+#define __get_dynamic_array_len(field)
+
+#undef TP_PROTO
+#define TP_PROTO(args...)
+
+#undef TP_ARGS
+#define TP_ARGS(args...)
+
+#undef TP_STRUCT__entry
+#define TP_STRUCT__entry(args...)
+
+#undef TP_fast_assign
+#define TP_fast_assign(args...)
+
+#undef __perf_count
+#define __perf_count(args...)
+
+#undef __perf_addr
+#define __perf_addr(args...)
+
+#undef TP_perf_assign
+#define TP_perf_assign(args...)
+
+#undef TP_printk
+#define TP_printk(args...)
+
+#undef DECLARE_EVENT_CLASS
+#define DECLARE_EVENT_CLASS(_name, _proto, _args, _tstruct, _assign, _print)
+
+#undef DECLARE_EVENT_CLASS_NOARGS
+#define DECLARE_EVENT_CLASS_NOARGS(_name, _tstruct, _assign, _print)
+
+#undef DEFINE_EVENT
+#define DEFINE_EVENT(_template, _name, _proto, _args)
+
+#undef DEFINE_EVENT_NOARGS
+#define DEFINE_EVENT_NOARGS(_template, _name)
+
+#undef TRACE_EVENT_FLAGS
+#define TRACE_EVENT_FLAGS(name, value)

drivers/staging/lttng/probes/lttng-ftrace.c

+/*
+ * (C) Copyright	2009-2011 -
+ * 		Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng function tracer integration module.
+ *
+ * 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).
+ *
+ * TODO: Move to register_ftrace_function() (which is exported for
+ * modules) for Linux >= 3.0. It is faster (only enables the selected
+ * functions), and will stay there.
+ */
+
+#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
+void lttng_ftrace_handler(unsigned long ip, unsigned long parent_ip, void **data)
+{
+	struct ltt_event *event = *data;
+	struct ltt_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, event,
+				 sizeof(payload), ltt_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, ltt_alignof(payload));
+	chan->ops->event_write(&ctx, &payload, sizeof(payload));
+	chan->ops->event_commit(&ctx);
+	return;
+}
+
+/*
+ * Create event description
+ */
+static
+int lttng_create_ftrace_event(const char *name, struct ltt_event *event)
+{
+	struct lttng_event_field *fields;
+	struct lttng_event_desc *desc;
+	int ret;
+
+	desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
+	if (!desc)
+		return -ENOMEM;
+	desc->name = kstrdup(name, GFP_KERNEL);
+	if (!desc->name) {
+		ret = -ENOMEM;
+		goto error_str;
+	}
+	desc->nr_fields = 2;
+	desc->fields = fields =
+		kzalloc(2 * sizeof(struct lttng_event_field), GFP_KERNEL);
+	if (!desc->fields) {
+		ret = -ENOMEM;
+		goto error_fields;
+	}
+	fields[0].name = "ip";
+	fields[0].type.atype = atype_integer;
+	fields[0].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
+	fields[0].type.u.basic.integer.alignment = ltt_alignof(unsigned long) * CHAR_BIT;
+	fields[0].type.u.basic.integer.signedness = is_signed_type(unsigned long);
+	fields[0].type.u.basic.integer.reverse_byte_order = 0;
+	fields[0].type.u.basic.integer.base = 16;
+	fields[0].type.u.basic.integer.encoding = lttng_encode_none;
+
+	fields[1].name = "parent_ip";
+	fields[1].type.atype = atype_integer;
+	fields[1].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
+	fields[1].type.u.basic.integer.alignment = ltt_alignof(unsigned long) * CHAR_BIT;
+	fields[1].type.u.basic.integer.signedness = is_signed_type(unsigned long);
+	fields[1].type.u.basic.integer.reverse_byte_order = 0;
+	fields[1].type.u.basic.integer.base = 16;
+	fields[1].type.u.basic.integer.encoding = lttng_encode_none;
+
+	desc->owner = THIS_MODULE;
+	event->desc = desc;
+
+	return 0;
+
+error_fields:
+	kfree(desc->name);
+error_str:
+	kfree(desc);
+	return ret;
+}
+
+static
+struct ftrace_probe_ops lttng_ftrace_ops = {
+	.func = lttng_ftrace_handler,
+};
+
+int lttng_ftrace_register(const char *name,
+			  const char *symbol_name,
+			  struct ltt_event *event)
+{
+	int ret;
+
+	ret = lttng_create_ftrace_event(name, event);
+	if (ret)
+		goto error;
+
+	event->u.ftrace.symbol_name = kstrdup(symbol_name, GFP_KERNEL);
+	if (!event->u.ftrace.symbol_name)
+		goto name_error;
+
+	/* 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 < 0)
+		goto register_error;
+	return 0;
+
+register_error:
+	kfree(event->u.ftrace.symbol_name);
+name_error:
+	kfree(event->desc->name);
+	kfree(event->desc);
+error:
+	return ret;
+}
+EXPORT_SYMBOL_GPL(lttng_ftrace_register);
+
+void lttng_ftrace_unregister(struct ltt_event *event)
+{
+	wrapper_unregister_ftrace_function_probe(event->u.ftrace.symbol_name,
+			&lttng_ftrace_ops, event);
+}
+EXPORT_SYMBOL_GPL(lttng_ftrace_unregister);
+
+void lttng_ftrace_destroy_private(struct ltt_event *event)
+{
+	kfree(event->u.ftrace.symbol_name);
+	kfree(event->desc->fields);
+	kfree(event->desc->name);
+	kfree(event->desc);
+}
+EXPORT_SYMBOL_GPL(lttng_ftrace_destroy_private);
+
+int lttng_ftrace_init(void)
+{
+	wrapper_vmalloc_sync_all();
+	return 0;
+}
+module_init(lttng_ftrace_init)
+
+/*
+ * Ftrace takes care of waiting for a grace period (RCU sched) at probe
+ * unregistration, and disables preemption around probe call.
+ */
+void lttng_ftrace_exit(void)
+{
+}
+module_exit(lttng_ftrace_exit)
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("Linux Trace Toolkit Ftrace Support");

drivers/staging/lttng/probes/lttng-kprobes.c

+/*
+ * (C) Copyright	2009-2011 -
+ * 		Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng kprobes integration module.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/kprobes.h>
+#include <linux/slab.h>
+#include "../ltt-events.h"
+#include "../wrapper/ringbuffer/frontend_types.h"
+#include "../wrapper/vmalloc.h"
+#include "../ltt-tracer.h"
+
+static
+int lttng_kprobes_handler_pre(struct kprobe *p, struct pt_regs *regs)
+{
+	struct ltt_event *event =
+		container_of(p, struct ltt_event, u.kprobe.kp);
+	struct ltt_channel *chan = event->chan;
+	struct lib_ring_buffer_ctx ctx;
+	int ret;
+	unsigned long data = (unsigned long) p->addr;
+
+	if (unlikely(!ACCESS_ONCE(chan->session->active)))
+		return 0;
+	if (unlikely(!ACCESS_ONCE(chan->enabled)))
+		return 0;
+	if (unlikely(!ACCESS_ONCE(event->enabled)))
+		return 0;
+
+	lib_ring_buffer_ctx_init(&ctx, chan->chan, event, sizeof(data),
+				 ltt_alignof(data), -1);
+	ret = chan->ops->event_reserve(&ctx, event->id);
+	if (ret < 0)
+		return 0;
+	lib_ring_buffer_align_ctx(&ctx, ltt_alignof(data));
+	chan->ops->event_write(&ctx, &data, sizeof(data));
+	chan->ops->event_commit(&ctx);
+	return 0;
+}
+
+/*
+ * Create event description
+ */
+static
+int lttng_create_kprobe_event(const char *name, struct ltt_event *event)
+{
+	struct lttng_event_field *field;
+	struct lttng_event_desc *desc;
+	int ret;
+
+	desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
+	if (!desc)
+		return -ENOMEM;
+	desc->name = kstrdup(name, GFP_KERNEL);
+	if (!desc->name) {
+		ret = -ENOMEM;
+		goto error_str;
+	}
+	desc->nr_fields = 1;
+	desc->fields = field =
+		kzalloc(1 * sizeof(struct lttng_event_field), GFP_KERNEL);
+	if (!field) {
+		ret = -ENOMEM;
+		goto error_field;
+	}
+	field->name = "ip";
+	field->type.atype = atype_integer;
+	field->type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
+	field->type.u.basic.integer.alignment = ltt_alignof(unsigned long) * CHAR_BIT;
+	field->type.u.basic.integer.signedness = is_signed_type(unsigned long);
+	field->type.u.basic.integer.reverse_byte_order = 0;
+	field->type.u.basic.integer.base = 16;
+	field->type.u.basic.integer.encoding = lttng_encode_none;
+	desc->owner = THIS_MODULE;
+	event->desc = desc;
+
+	return 0;
+
+error_field:
+	kfree(desc->name);
+error_str:
+	kfree(desc);
+	return ret;
+}
+
+int lttng_kprobes_register(const char *name,
+			   const char *symbol_name,
+			   uint64_t offset,
+			   uint64_t addr,
+			   struct ltt_event *event)
+{
+	int ret;
+
+	/* Kprobes expects a NULL symbol name if unused */
+	if (symbol_name[0] == '\0')
+		symbol_name = NULL;
+
+	ret = lttng_create_kprobe_event(name, event);
+	if (ret)
+		goto error;
+	memset(&event->u.kprobe.kp, 0, sizeof(event->u.kprobe.kp));
+	event->u.kprobe.kp.pre_handler = lttng_kprobes_handler_pre;
+	if (symbol_name) {
+		event->u.kprobe.symbol_name =
+			kzalloc(LTTNG_SYM_NAME_LEN * sizeof(char),
+				GFP_KERNEL);
+		if (!event->u.kprobe.symbol_name) {
+			ret = -ENOMEM;
+			goto name_error;
+		}
+		memcpy(event->u.kprobe.symbol_name, symbol_name,
+		       LTTNG_SYM_NAME_LEN * sizeof(char));
+		event->u.kprobe.kp.symbol_name =
+			event->u.kprobe.symbol_name;
+	}
+	event->u.kprobe.kp.offset = offset;
+	event->u.kprobe.kp.addr = (void *) (unsigned long) addr;
+
+	/*
+	 * Ensure the memory we just allocated don't trigger page faults.
+	 * Well.. kprobes itself puts the page fault handler on the blacklist,
+	 * but we can never be too careful.
+	 */
+	wrapper_vmalloc_sync_all();
+
+	ret = register_kprobe(&event->u.kprobe.kp);
+	if (ret)
+		goto register_error;
+	return 0;
+
+register_error:
+	kfree(event->u.kprobe.symbol_name);
+name_error:
+	kfree(event->desc->fields);
+	kfree(event->desc->name);
+	kfree(event->desc);
+error:
+	return ret;
+}
+EXPORT_SYMBOL_GPL(lttng_kprobes_register);
+
+void lttng_kprobes_unregister(struct ltt_event *event)
+{
+	unregister_kprobe(&event->u.kprobe.kp);
+}
+EXPORT_SYMBOL_GPL(lttng_kprobes_unregister);
+
+void lttng_kprobes_destroy_private(struct ltt_event *event)
+{
+	kfree(event->u.kprobe.symbol_name);
+	kfree(event->desc->fields);
+	kfree(event->desc->name);
+	kfree(event->desc);
+}
+EXPORT_SYMBOL_GPL(lttng_kprobes_destroy_private);
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("Linux Trace Toolkit Kprobes Support");

drivers/staging/lttng/probes/lttng-kretprobes.c

+/*
+ * (C) Copyright	2009-2011 -
+ * 		Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng kretprobes integration module.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/kprobes.h>
+#include <linux/slab.h>
+#include <linux/kref.h>
+#include "../ltt-events.h"
+#include "../wrapper/ringbuffer/frontend_types.h"
+#include "../wrapper/vmalloc.h"
+#include "../ltt-tracer.h"
+
+enum lttng_kretprobe_type {
+	EVENT_ENTRY = 0,
+	EVENT_RETURN = 1,
+};
+
+struct lttng_krp {
+	struct kretprobe krp;
+	struct ltt_event *event[2];	/* ENTRY and RETURN */
+	struct kref kref_register;
+	struct kref kref_alloc;
+};
+
+static
+int _lttng_kretprobes_handler(struct kretprobe_instance *krpi,
+			      struct pt_regs *regs,
+			      enum lttng_kretprobe_type type)
+{
+	struct lttng_krp *lttng_krp =
+		container_of(krpi->rp, struct lttng_krp, krp);
+	struct ltt_event *event =
+		lttng_krp->event[type];
+	struct ltt_channel *chan = event->chan;
+	struct lib_ring_buffer_ctx ctx;
+	int ret;
+	struct {
+		unsigned long ip;
+		unsigned long parent_ip;
+	} payload;
+
+	if (unlikely(!ACCESS_ONCE(chan->session->active)))
+		return 0;
+	if (unlikely(!ACCESS_ONCE(chan->enabled)))
+		return 0;
+	if (unlikely(!ACCESS_ONCE(event->enabled)))
+		return 0;
+
+	payload.ip = (unsigned long) krpi->rp->kp.addr;
+	payload.parent_ip = (unsigned long) krpi->ret_addr;
+
+	lib_ring_buffer_ctx_init(&ctx, chan->chan, event, sizeof(payload),
+				 ltt_alignof(payload), -1);
+	ret = chan->ops->event_reserve(&ctx, event->id);
+	if (ret < 0)
+		return 0;
+	lib_ring_buffer_align_ctx(&ctx, ltt_alignof(payload));
+	chan->ops->event_write(&ctx, &payload, sizeof(payload));
+	chan->ops->event_commit(&ctx);
+	return 0;
+}
+
+static
+int lttng_kretprobes_handler_entry(struct kretprobe_instance *krpi,
+				   struct pt_regs *regs)
+{
+	return _lttng_kretprobes_handler(krpi, regs, EVENT_ENTRY);
+}
+
+static
+int lttng_kretprobes_handler_return(struct kretprobe_instance *krpi,
+				    struct pt_regs *regs)
+{
+	return _lttng_kretprobes_handler(krpi, regs, EVENT_RETURN);
+}
+
+/*
+ * Create event description
+ */
+static
+int lttng_create_kprobe_event(const char *name, struct ltt_event *event,
+			      enum lttng_kretprobe_type type)
+{
+	struct lttng_event_field *fields;
+	struct lttng_event_desc *desc;
+	int ret;
+	char *alloc_name;
+	size_t name_len;
+	const char *suffix = NULL;
+
+	desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
+	if (!desc)
+		return -ENOMEM;
+	name_len = strlen(name);
+	switch (type) {
+	case EVENT_ENTRY:
+		suffix = "_entry";
+		break;
+	case EVENT_RETURN:
+		suffix = "_return";
+		break;
+	}
+	name_len += strlen(suffix);
+	alloc_name = kmalloc(name_len + 1, GFP_KERNEL);
+	if (!alloc_name) {
+		ret = -ENOMEM;
+		goto error_str;
+	}
+	strcpy(alloc_name, name);
+	strcat(alloc_name, suffix);
+	desc->name = alloc_name;
+	desc->nr_fields = 2;
+	desc->fields = fields =
+		kzalloc(2 * sizeof(struct lttng_event_field), GFP_KERNEL);
+	if (!desc->fields) {
+		ret = -ENOMEM;
+		goto error_fields;
+	}
+	fields[0].name = "ip";
+	fields[0].type.atype = atype_integer;
+	fields[0].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
+	fields[0].type.u.basic.integer.alignment = ltt_alignof(unsigned long) * CHAR_BIT;
+	fields[0].type.u.basic.integer.signedness = is_signed_type(unsigned long);
+	fields[0].type.u.basic.integer.reverse_byte_order = 0;
+	fields[0].type.u.basic.integer.base = 16;
+	fields[0].type.u.basic.integer.encoding = lttng_encode_none;
+
+	fields[1].name = "parent_ip";
+	fields[1].type.atype = atype_integer;
+	fields[1].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
+	fields[1].type.u.basic.integer.alignment = ltt_alignof(unsigned long) * CHAR_BIT;
+	fields[1].type.u.basic.integer.signedness = is_signed_type(unsigned long);
+	fields[1].type.u.basic.integer.reverse_byte_order = 0;
+	fields[1].type.u.basic.integer.base = 16;
+	fields[1].type.u.basic.integer.encoding = lttng_encode_none;
+
+	desc->owner = THIS_MODULE;
+	event->desc = desc;
+
+	return 0;
+
+error_fields:
+	kfree(desc->name);
+error_str:
+	kfree(desc);
+	return ret;
+}
+
+int lttng_kretprobes_register(const char *name,
+			   const char *symbol_name,
+			   uint64_t offset,
+			   uint64_t addr,
+			   struct ltt_event *event_entry,
+			   struct ltt_event *event_return)
+{
+	int ret;
+	struct lttng_krp *lttng_krp;
+
+	/* Kprobes expects a NULL symbol name if unused */
+	if (symbol_name[0] == '\0')
+		symbol_name = NULL;
+
+	ret = lttng_create_kprobe_event(name, event_entry, EVENT_ENTRY);
+	if (ret)
+		goto error;
+	ret = lttng_create_kprobe_event(name, event_return, EVENT_RETURN);
+	if (ret)
+		goto event_return_error;
+	lttng_krp = kzalloc(sizeof(*lttng_krp), GFP_KERNEL);
+	if (!lttng_krp)
+		goto krp_error;
+	lttng_krp->krp.entry_handler = lttng_kretprobes_handler_entry;
+	lttng_krp->krp.handler = lttng_kretprobes_handler_return;
+	if (symbol_name) {
+		char *alloc_symbol;
+
+		alloc_symbol = kstrdup(symbol_name, GFP_KERNEL);
+		if (!alloc_symbol) {
+			ret = -ENOMEM;
+			goto name_error;
+		}
+		lttng_krp->krp.kp.symbol_name =
+			alloc_symbol;
+		event_entry->u.kretprobe.symbol_name =
+			alloc_symbol;
+		event_return->u.kretprobe.symbol_name =
+			alloc_symbol;
+	}
+	lttng_krp->krp.kp.offset = offset;
+	lttng_krp->krp.kp.addr = (void *) (unsigned long) addr;
+
+	/* Allow probe handler to find event structures */
+	lttng_krp->event[EVENT_ENTRY] = event_entry;
+	lttng_krp->event[EVENT_RETURN] = event_return;
+	event_entry->u.kretprobe.lttng_krp = lttng_krp;
+	event_return->u.kretprobe.lttng_krp = lttng_krp;
+
+	/*
+	 * Both events must be unregistered before the kretprobe is
+	 * unregistered. Same for memory allocation.
+	 */
+	kref_init(&lttng_krp->kref_alloc);
+	kref_get(&lttng_krp->kref_alloc);	/* inc refcount to 2 */
+	kref_init(&lttng_krp->kref_register);
+	kref_get(&lttng_krp->kref_register);	/* inc refcount to 2 */
+
+	/*
+	 * Ensure the memory we just allocated don't trigger page faults.
+	 * Well.. kprobes itself puts the page fault handler on the blacklist,
+	 * but we can never be too careful.
+	 */
+	wrapper_vmalloc_sync_all();
+
+	ret = register_kretprobe(&lttng_krp->krp);
+	if (ret)
+		goto register_error;
+	return 0;
+
+register_error:
+	kfree(lttng_krp->krp.kp.symbol_name);
+name_error:
+	kfree(lttng_krp);
+krp_error:
+	kfree(event_return->desc->fields);
+	kfree(event_return->desc->name);
+	kfree(event_return->desc);
+event_return_error:
+	kfree(event_entry->desc->fields);
+	kfree(event_entry->desc->name);
+	kfree(event_entry->desc);
+error:
+	return ret;
+}
+EXPORT_SYMBOL_GPL(lttng_kretprobes_register);
+
+static
+void _lttng_kretprobes_unregister_release(struct kref *kref)
+{
+	struct lttng_krp *lttng_krp =
+		container_of(kref, struct lttng_krp, kref_register);
+	unregister_kretprobe(&lttng_krp->krp);
+}
+
+void lttng_kretprobes_unregister(struct ltt_event *event)
+{
+	kref_put(&event->u.kretprobe.lttng_krp->kref_register,
+		_lttng_kretprobes_unregister_release);
+}
+EXPORT_SYMBOL_GPL(lttng_kretprobes_unregister);
+
+static
+void _lttng_kretprobes_release(struct kref *kref)
+{
+	struct lttng_krp *lttng_krp =
+		container_of(kref, struct lttng_krp, kref_alloc);
+	kfree(lttng_krp->krp.kp.symbol_name);
+}
+
+void lttng_kretprobes_destroy_private(struct ltt_event *event)
+{
+	kfree(event->desc->fields);
+	kfree(event->desc->name);
+	kfree(event->desc);
+	kref_put(&event->u.kretprobe.lttng_krp->kref_alloc,
+		_lttng_kretprobes_release);
+}
+EXPORT_SYMBOL_GPL(lttng_kretprobes_destroy_private);
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("Linux Trace Toolkit Kretprobes Support");

drivers/staging/lttng/probes/lttng-probe-block.c

+/*
+ * probes/lttng-probe-block.c
+ *
+ * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng block probes.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/blktrace_api.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/block.h>
+
+/*
+ * Create LTTng tracepoint probes.
+ */
+#define LTTNG_PACKAGE_BUILD
+#define CREATE_TRACE_POINTS
+#define TRACE_INCLUDE_PATH ../instrumentation/events/lttng-module
+
+#include "../instrumentation/events/lttng-module/block.h"
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
+MODULE_DESCRIPTION("LTTng block probes");

drivers/staging/lttng/probes/lttng-probe-irq.c

+/*
+ * probes/lttng-probe-irq.c
+ *
+ * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng irq probes.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/interrupt.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/irq.h>
+
+/*
+ * Create LTTng tracepoint probes.
+ */
+#define LTTNG_PACKAGE_BUILD
+#define CREATE_TRACE_POINTS
+#define TRACE_INCLUDE_PATH ../instrumentation/events/lttng-module
+
+#include "../instrumentation/events/lttng-module/irq.h"
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
+MODULE_DESCRIPTION("LTTng irq probes");

drivers/staging/lttng/probes/lttng-probe-kvm.c

+/*
+ * probes/lttng-probe-kvm.c
+ *
+ * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng kvm probes.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/kvm_host.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/kvm.h>
+
+/*
+ * Create LTTng tracepoint probes.
+ */
+#define LTTNG_PACKAGE_BUILD
+#define CREATE_TRACE_POINTS
+#define TRACE_INCLUDE_PATH ../instrumentation/events/lttng-module
+
+#include "../instrumentation/events/lttng-module/kvm.h"
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
+MODULE_DESCRIPTION("LTTng kvm probes");

drivers/staging/lttng/probes/lttng-probe-lttng.c

+/*
+ * probes/lttng-probe-core.c
+ *
+ * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng core probes.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+
+/*
+ * Create LTTng tracepoint probes.
+ */
+#define LTTNG_PACKAGE_BUILD
+#define CREATE_TRACE_POINTS
+#define TRACE_INCLUDE_PATH ../instrumentation/events/lttng-module
+
+#include "../instrumentation/events/lttng-module/lttng.h"
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
+MODULE_DESCRIPTION("LTTng core probes");

drivers/staging/lttng/probes/lttng-probe-sched.c

+/*
+ * probes/lttng-probe-sched.c
+ *
+ * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng sched probes.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.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/sched.h>
+
+/*
+ * Create LTTng tracepoint probes.
+ */
+#define LTTNG_PACKAGE_BUILD
+#define CREATE_TRACE_POINTS
+#define TRACE_INCLUDE_PATH ../instrumentation/events/lttng-module
+
+#include "../instrumentation/events/lttng-module/sched.h"
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
+MODULE_DESCRIPTION("LTTng sched probes");

drivers/staging/lttng/probes/lttng-type-list.h

+/*
+ * lttng-type-list.h
+ *
+ * Copyright (C) 2010-2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+/* Type list, used to create metadata */
+
+/* Enumerations */
+TRACE_EVENT_ENUM(hrtimer_mode,
+        V(HRTIMER_MODE_ABS),
+        V(HRTIMER_MODE_REL),
+        V(HRTIMER_MODE_PINNED),
+        V(HRTIMER_MODE_ABS_PINNED),
+        V(HRTIMER_MODE_REL_PINNED),
+	R(HRTIMER_MODE_UNDEFINED, 0x04, 0x20),	/* Example (to remove) */
+)
+
+TRACE_EVENT_TYPE(hrtimer_mode, enum, unsigned char)

drivers/staging/lttng/probes/lttng-types.c

+/*
+ * probes/lttng-types.c
+ *
+ * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng types.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include "../wrapper/vmalloc.h"	/* for wrapper_vmalloc_sync_all() */
+#include "../ltt-events.h"
+#include "lttng-types.h"
+#include <linux/hrtimer.h>
+
+#define STAGE_EXPORT_ENUMS
+#include "lttng-types.h"
+#include "lttng-type-list.h"
+#undef STAGE_EXPORT_ENUMS
+
+struct lttng_enum lttng_enums[] = {
+#define STAGE_EXPORT_TYPES
+#include "lttng-types.h"
+#include "lttng-type-list.h"
+#undef STAGE_EXPORT_TYPES
+};
+
+static int lttng_types_init(void)
+{
+	int ret = 0;
+
+	wrapper_vmalloc_sync_all();
+	/* TODO */
+	return ret;
+}
+
+module_init(lttng_types_init);
+
+static void lttng_types_exit(void)
+{
+}
+
+module_exit(lttng_types_exit);
+
+MODULE_LICENSE("GPL and additional rights");
+MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
+MODULE_DESCRIPTION("LTTng types");

drivers/staging/lttng/probes/lttng-types.h

+/*
+ * Protect against multiple inclusion of structure declarations, but run the
+ * stages below each time.
+ */
+#ifndef _LTTNG_PROBES_LTTNG_TYPES_H
+#define _LTTNG_PROBES_LTTNG_TYPES_H
+
+/*
+ * probes/lttng-types.h
+ *
+ * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng types.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/seq_file.h>
+#include "lttng.h"
+#include "../ltt-events.h"
+#include "../ltt-tracer.h"
+#include "../ltt-endian.h"
+
+#endif /* _LTTNG_PROBES_LTTNG_TYPES_H */
+
+/* Export enumerations */
+
+#ifdef STAGE_EXPORT_ENUMS
+
+#undef TRACE_EVENT_TYPE
+#define TRACE_EVENT_TYPE(_name, _abstract_type, args...)
+
+#undef TRACE_EVENT_ENUM
+#define TRACE_EVENT_ENUM(_name, _entries...)				\
+	const struct lttng_enum_entry __trace_event_enum_##_name[] = {	\
+		PARAMS(_entries)					\
+	};
+
+/* Enumeration entry (single value) */
+#undef V
+#define V(_string)		{ _string, _string, #_string}
+
+/* Enumeration entry (range) */
+#undef R
+#define R(_string, _range_start, _range_end)				\
+	{ _range_start, _range_end, #_string }
+
+#endif /* STAGE_EXPORT_ENUMS */
+
+
+/* Export named types */
+
+#ifdef STAGE_EXPORT_TYPES
+
+#undef TRACE_EVENT_TYPE___enum
+#define TRACE_EVENT_TYPE___enum(_name, _container_type)			\
+		{							\
+		  .name = #_name,					\
+		  .container_type = __type_integer(_container_type, __BYTE_ORDER, 10, none), \
+		  .entries = __trace_event_enum_##_name, \
+		  .len = ARRAY_SIZE(__trace_event_enum_##_name), \
+		},
+
+/* Local declaration */
+#undef TRACE_EVENT_TYPE
+#define TRACE_EVENT_TYPE(_name, _abstract_type, args...)	\
+		TRACE_EVENT_TYPE___##_abstract_type(_name, args)
+
+#undef TRACE_EVENT_ENUM
+#define TRACE_EVENT_ENUM(_name, _entries...)
+
+#endif /* STAGE_EXPORT_TYPES */

drivers/staging/lttng/probes/lttng.h

+#ifndef _LTTNG_PROBES_LTTNG_H
+#define _LTTNG_PROBES_LTTNG_H
+
+/*
+ * lttng.h
+ *
+ * Copyright (C) 2010-2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#undef PARAMS
+#define PARAMS(args...)		args
+
+#endif /* _LTTNG_PROBES_LTTNG_H */