linux-kernel - How can I check creator of probe point?

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Date:	Tue, 14 Oct 2014 11:16:39 +0900
From:	Gioh Kim <gioh.kim@....com>
To:	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>,
	"David S. Miller" <davem@...emloft.net>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: How can I check creator of probe point?


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;
 }


-- 
Thanks,
Gioh Kim
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