Re: How can I check creator of probe point?

From: Gioh Kim
Date: Thu Oct 16 2014 - 02:45:36 EST


I'm going to try them.
Thanks a lot.


2014-10-16 오후 3:00, Masami Hiramatsu 쓴 글:
> Hello Gioh,
>
> If you can use ftrace and perftool, you can also put probes on
> caller site. perf-probe will give you source-code level probes.
> Or, just trace kmalloc event with ftrace stacktrace option, which
> gives you caller information so that you can filter your driver
> by postprocessing.
>
> Thank you,
>
> (2014/10/14 11:16), Gioh Kim wrote:
>>
>> Hi,
>>
>> I am trying to find a way to make statistics for memory allocation of my device driver.
>> I want to know how much memory it allocates and how many times it calls kmalloc().
>>
>> So I am considering to use kprobe but I think it doesn't provide a way to identify who makes the probe point.
>> Can I distinguish kmalloc() calling only from my driver?
>>
>> For example I think it could be like this:
>>
>> diff --git a/samples/kprobes/kretprobe_example.c b/samples/kprobes/kretprobe_example.c
>> index 1041b67..5322e0a 100644
>> --- a/samples/kprobes/kretprobe_example.c
>> +++ b/samples/kprobes/kretprobe_example.c
>> @@ -32,6 +32,7 @@ MODULE_PARM_DESC(func, "Function to kretprobe; this module will report the"
>>
>> /* per-instance private data */
>> struct my_data {
>> + unsigned long signature;
>> ktime_t entry_stamp;
>> };
>>
>> @@ -43,8 +44,10 @@ static int entry_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
>> if (!current->mm)
>> return 1; /* Skip kernel threads */
>>
>> - data = (struct my_data *)ri->data;
>> - data->entry_stamp = ktime_get();
>> + if (signature == 0xabcdabcd) {
>> + data = (struct my_data *)ri->data;
>> + data->entry_stamp = ktime_get();
>> + }
>> return 0;
>> }
>>
>> @@ -60,10 +63,12 @@ static int ret_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
>> 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);
>> + if (signature == 0xabcdabcd) {
>> + 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;
>> }
>>
>>
>
>
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