Re: [1/5 PATCH] Kprobes fix for broken fault handling for i386

[Prasanna S Panchamukhi <prasanna@in.ibm.com>]

Anil,

You can use the test script mentioned by Hien below.
Also to test the fault handling, you need to just
call copy_from_user(), that will generate a page fault.
In the post/pre handler allocate a buffer and 
copy some data from the user address space.

copy_from_user(&buf, (unsigned long *)0xbff2d020, 10);

where the from address should be a valid user space address.


Thanks
Prasanna

On Tue, Mar 07, 2006 at 02:23:58PM -0800, Hien Nguyen wrote:
> Keshavamurthy Anil S wrote:
> 
> >On Tue, Mar 07, 2006 at 05:38:32AM -0800, Prasanna S Panchamukhi wrote:
> > 
> >
> >>  Hi,
> >>
> >>  Below is the set of patches to fix broken fault handling
> >>  for i386, x86_64, ppc64, ia64 and sparc64 architectures
> >>  against 2.6.16-rc5-mm2.
> >>
> >>  These patches are tested for i386 and x86_64 architectures.
> >>  Could you please test it for ia64 and ppc64.
> >>   
> >>
> >
> >Prasanna,
> >	Can you share your test module code here,
> >so that the same can be used(with minor tweak, if requred)
> >for testing other architecture. Also in you testing, did 
> >you cover fault handling during pre/post/singlestep
> >cases?
> >
> >Thanks,
> >Anil
> >
> > 
> >
> I tested Prasanna's fault handling patch with the current syscalls 
> tapset (latest from CVS) which does lots of user copies. Without the 
> patch the system crashes right away, but with this patch I finally can 
> test the system calls tapset.
> 
> I use Martin's sys.stp script below
> 
> probe syscall.*, syscall.*.return {
>        if (pid() == target()) {
>                if (returnp)
>                        printf("%d\n", returnval())
>                else
>                        printf("%s (%s) = ", name, argstr)
>        }
> }
> 
> Invoke the script as follow
> stap -c bash sys.stp
> to exit the script, just type exit.
> 
> Hien.
> 
> 
> 

-- 
Prasanna S Panchamukhi
Linux Technology Center
India Software Labs, IBM Bangalore
Email: prasanna@in.ibm.com
Ph: 91-80-51776329