Re: x86_64 frame pointer via thread context

[Petr Vandrovec <vandrove@vc.cvut.cz>]

Dave Jiang wrote:
> Andi Kleen wrote:
> 
>> Dave Jiang <djiang@mvista.com> writes:
>>
>>> Am I doing something wrong, or is this intended to be this way on
>>> x86_64, or is something incorrect in the kernel? This method works
>>> fine on i386. Thanks for any help!
>>
>>
>>
>> I just tested your program on SLES9 with updated kernel and RBP
>> looks correct to me. Probably something is wrong with your user space
>> includes or your compiler.
>>
>> -Andi
> 
> 
> I revised the app a little so that it would allow the threads to start, 
> thus should prevent rBP w/ all 0's showing up. Below are some of results 
> that I've gotten from various different distros and platforms. As you 
> can see, the f's shows up on most of them, including Suse 9.2. The only 
> one showed up looking ok is the Mandrake/Mandriva distro. I'm not sure 
> how different SLES9 is from Suse9.2....

Replace call to sleep() with busy loop.  Glibc's sleep() uses %ebp for
its own data, so when you interrupt sleep(), you get rbp=(unsigned int)-1,
as rbp really contains 0x0000.0000.ffff.ffff when nanosleep() syscall
is issued.
								Petr