Commit 31155bc0 authored by Mathieu Desnoyers's avatar Mathieu Desnoyers Committed by Linus Torvalds

Linux Kernel Markers - Samples

Module example showing how to use the Linux Kernel Markers.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: default avatarMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 267c4025
......@@ -61,7 +61,6 @@ struct marker {
__attribute__((section("__markers"), aligned(8))) = \
{ __mstrtab_name_##name, __mstrtab_format_##name, \
0, __mark_empty_function, NULL }; \
asm volatile("" : : "i" (&__mark_##name)); \
__mark_check_format(format, ## args); \
if (unlikely(__mark_##name.state)) { \
preempt_disable(); \
......
......@@ -7,5 +7,10 @@ menuconfig SAMPLES
if SAMPLES
config SAMPLE_MARKERS
tristate "Build markers examples -- loadable modules only"
depends on MARKERS && m
help
This build markers example modules.
endif # SAMPLES
# Makefile for Linux samples code
obj-$(CONFIG_SAMPLES) += markers/
# builds the kprobes example kernel modules;
# then to use one (as root): insmod <module_name.ko>
obj-$(CONFIG_SAMPLE_MARKERS) += probe-example.o marker-example.o
/* marker-example.c
*
* Executes a marker when /proc/marker-example is opened.
*
* (C) Copyright 2007 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
*
* This file is released under the GPLv2.
* See the file COPYING for more details.
*/
#include <linux/module.h>
#include <linux/marker.h>
#include <linux/sched.h>
#include <linux/proc_fs.h>
struct proc_dir_entry *pentry_example;
static int my_open(struct inode *inode, struct file *file)
{
int i;
trace_mark(subsystem_event, "%d %s", 123, "example string");
for (i = 0; i < 10; i++)
trace_mark(subsystem_eventb, MARK_NOARGS);
return -EPERM;
}
static struct file_operations mark_ops = {
.open = my_open,
};
static int example_init(void)
{
printk(KERN_ALERT "example init\n");
pentry_example = create_proc_entry("marker-example", 0444, NULL);
if (pentry_example)
pentry_example->proc_fops = &mark_ops;
else
return -EPERM;
return 0;
}
static void example_exit(void)
{
printk(KERN_ALERT "example exit\n");
remove_proc_entry("marker-example", NULL);
}
module_init(example_init)
module_exit(example_exit)
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Mathieu Desnoyers");
MODULE_DESCRIPTION("Marker example");
/* probe-example.c
*
* Connects two functions to marker call sites.
*
* (C) Copyright 2007 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
*
* This file is released under the GPLv2.
* See the file COPYING for more details.
*/
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/marker.h>
#include <asm/atomic.h>
struct probe_data {
const char *name;
const char *format;
marker_probe_func *probe_func;
};
void probe_subsystem_event(const struct marker *mdata, void *private,
const char *format, ...)
{
va_list ap;
/* Declare args */
unsigned int value;
const char *mystr;
/* Assign args */
va_start(ap, format);
value = va_arg(ap, typeof(value));
mystr = va_arg(ap, typeof(mystr));
/* Call printk */
printk(KERN_DEBUG "Value %u, string %s\n", value, mystr);
/* or count, check rights, serialize data in a buffer */
va_end(ap);
}
atomic_t eventb_count = ATOMIC_INIT(0);
void probe_subsystem_eventb(const struct marker *mdata, void *private,
const char *format, ...)
{
/* Increment counter */
atomic_inc(&eventb_count);
}
static struct probe_data probe_array[] =
{
{ .name = "subsystem_event",
.format = "%d %s",
.probe_func = probe_subsystem_event },
{ .name = "subsystem_eventb",
.format = MARK_NOARGS,
.probe_func = probe_subsystem_eventb },
};
static int __init probe_init(void)
{
int result;
int i;
for (i = 0; i < ARRAY_SIZE(probe_array); i++) {
result = marker_probe_register(probe_array[i].name,
probe_array[i].format,
probe_array[i].probe_func, &probe_array[i]);
if (result)
printk(KERN_INFO "Unable to register probe %s\n",
probe_array[i].name);
result = marker_arm(probe_array[i].name);
if (result)
printk(KERN_INFO "Unable to arm probe %s\n",
probe_array[i].name);
}
return 0;
}
static void __exit probe_fini(void)
{
int i;
for (i = 0; i < ARRAY_SIZE(probe_array); i++)
marker_probe_unregister(probe_array[i].name);
printk(KERN_INFO "Number of event b : %u\n",
atomic_read(&eventb_count));
}
module_init(probe_init);
module_exit(probe_fini);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Mathieu Desnoyers");
MODULE_DESCRIPTION("SUBSYSTEM Probe");
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