lkml.org 
[lkml]   [2004]   [Dec]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
Subjecthelp with access_process_vm
Hi all.

I am trying to write/read to/from a process image (to be more
specific, replace an instruction with a 0xCC trap) from within a debug
handler. I mean, a debug handler will be fired
(via eflags) and I want to make sure the process will stop again at a
given address.

My new handler, called do_debug_new replaces the old do_debug. From inside it,
I do something like

task = current;
....
access_process_vm(task, addr, &oldvalue, sizeof(oldvalue), 0);
newvalue= oldvalue;
ptr = (char *) &newvalue;
*ptr = 0xCC;
access_process_vm(task, addr, &newvalue, sizeof(newvalue), 1);
....

But the first time a call access_process_vm, dmesg shows me:

Debug: sleeping function called from invalid context at include/linux/rwsem.h:43
in_atomic():0, irqs_disabled():1
[<c01145ac>] __might_sleep+0x8c/0xa0
[<c011c69b>] access_process_vm+0x4b/0x1d0
[<c010c830>] do_debug_new+0xd0/0x190
[<c038c755>] schedule+0x275/0x460
[<c0105c2d>] error_code+0x2d/0x40

What I am missing? Do I need some syncronization? Can the debug
handler run in the
context of a process that was not the one that caused the debug trap?

Thanks a lot
Fabiano
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 14:08    [W:0.083 / U:0.272 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site