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Dereferencing simple pointers
- From: daniel-kay at arcor dot de
- To: systemtap at sourceware dot org
- Date: Tue, 24 Nov 2009 18:27:47 +0100 (CET)
- Subject: Dereferencing simple pointers
Hello Folks,
I am playing around with systemtap and am quite impressed. But there is one thing that confuses me. Is there any way that I can derefernce a single pointer from a function parameter inside a probe?
Example:
# Function from current Kernel (drivers/char/random.c:1049):
urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
{
return extract_entropy_user(&nonblocking_pool, buf, nbytes);
}
# My Probe Attempt without success:
probe kernel.function("urandom_read") {
printf("%s\n", *($ppos));
}
I can't believe that this isn't possible...
Thanks in advance,
Daniel Kay