What can I access in return probe

[Kevin Stafford]

Kevin Stafford wrote:

> Badari Pulavarty wrote:
>
>> Hi,
>>
>> I am wondering if I can access arguments in my return probe ?
>>  
>>
> No, by the time the return probe fires, the stack has been torn down 
> and thus
> have no reference to you arguments, which causes the deref fault. 
> There have
> been a couple of proposed solutions to this problem. See
> http://sources.redhat.com/bugzilla/show_bug.cgi?id=1382
>
>> And also, how do I access return value ?
>>  
>>
> Tapset function retval() should do this for you.
> See /usr/local/share/systemtap/tapset/return.stp
>
>>
>> Whats wrong here ?
>>
>> # stap -g pagecache.stp
>> ERROR: pointer dereference fault near identifier 'page_cache_pages' at
>> pagecache.stp:8:2
>>
>>
>> Thanks,
>> Badari
>>  
>>


-- 
Kevin Stafford
DES 2 | MS 2M3
Beaverton - OR
Linux Technology Center
IBM Systems & Technology
Phone: 1-503-578-3039
Email: kevinrs@us.ibm.com