Release 4.7 samples/kprobes/kretprobe_example.c
/*
* kretprobe_example.c
*
* Here's a sample kernel module showing the use of return probes to
* report the return value and total time taken for probed function
* to run.
*
* usage: insmod kretprobe_example.ko func=<func_name>
*
* If no func_name is specified, _do_fork is instrumented
*
* For more information on theory of operation of kretprobes, see
* Documentation/kprobes.txt
*
* Build and insert the kernel module as done in the kprobe example.
* You will see the trace data in /var/log/messages and on the console
* whenever the probed function returns. (Some messages may be suppressed
* if syslogd is configured to eliminate duplicate messages.)
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/kprobes.h>
#include <linux/ktime.h>
#include <linux/limits.h>
#include <linux/sched.h>
static char func_name[NAME_MAX] = "_do_fork";
module_param_string(func, func_name, NAME_MAX, S_IRUGO);
MODULE_PARM_DESC(func, "Function to kretprobe; this module will report the"
" function's execution time");
/* per-instance private data */
struct my_data {
ktime_t entry_stamp;
};
/* Here we use the entry_hanlder to timestamp function entry */
static int entry_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
{
struct my_data *data;
if (!current->mm)
return 1; /* Skip kernel threads */
data = (struct my_data *)ri->data;
data->entry_stamp = ktime_get();
return 0;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ananth n. mavinakayanahalli | ananth n. mavinakayanahalli | 53 | 100.00% | 1 | 100.00% |
| Total | 53 | 100.00% | 1 | 100.00% |
/*
* Return-probe handler: Log the return value and duration. Duration may turn
* out to be zero consistently, depending upon the granularity of time
* accounting on the platform.
*/
static int ret_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
{
int retval = regs_return_value(regs);
struct my_data *data = (struct my_data *)ri->data;
s64 delta;
ktime_t now;
now = ktime_get();
delta = ktime_to_ns(ktime_sub(now, data->entry_stamp));
printk(KERN_INFO "%s returned %d and took %lld ns to execute\n",
func_name, retval, (long long)delta);
return 0;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ananth n. mavinakayanahalli | ananth n. mavinakayanahalli | 82 | 100.00% | 1 | 100.00% |
| Total | 82 | 100.00% | 1 | 100.00% |
static struct kretprobe my_kretprobe = {
.handler = ret_handler,
.entry_handler = entry_handler,
.data_size = sizeof(struct my_data),
/* Probe up to 20 instances concurrently. */
.maxactive = 20,
};
static int __init kretprobe_init(void)
{
int ret;
my_kretprobe.kp.symbol_name = func_name;
ret = register_kretprobe(&my_kretprobe);
if (ret < 0) {
printk(KERN_INFO "register_kretprobe failed, returned %d\n",
ret);
return -1;
}
printk(KERN_INFO "Planted return probe at %s: %p\n",
my_kretprobe.kp.symbol_name, my_kretprobe.kp.addr);
return 0;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ananth n. mavinakayanahalli | ananth n. mavinakayanahalli | 69 | 100.00% | 1 | 100.00% |
| Total | 69 | 100.00% | 1 | 100.00% |
static void __exit kretprobe_exit(void)
{
unregister_kretprobe(&my_kretprobe);
printk(KERN_INFO "kretprobe at %p unregistered\n",
my_kretprobe.kp.addr);
/* nmissed > 0 suggests that maxactive was set too low. */
printk(KERN_INFO "Missed probing %d instances of %s\n",
my_kretprobe.nmissed, my_kretprobe.kp.symbol_name);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ananth n. mavinakayanahalli | ananth n. mavinakayanahalli | 44 | 100.00% | 1 | 100.00% |
| Total | 44 | 100.00% | 1 | 100.00% |
module_init(kretprobe_init)
module_exit(kretprobe_exit)
MODULE_LICENSE("GPL");
Overall Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| ananth n. mavinakayanahalli | ananth n. mavinakayanahalli | 346 | 98.58% | 1 | 33.33% |
| alexey dobriyan | alexey dobriyan | 3 | 0.85% | 1 | 33.33% |
| petr mladek | petr mladek | 2 | 0.57% | 1 | 33.33% |
| Total | 351 | 100.00% | 3 | 100.00% |
Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.