Log in

View Full Version : Qustion about Hardware Breakpoint


jon
June 15th, 2005, 06:15
I would like to know about how Olly implements Hardware Breakpoint..
I read the Olly help file, and also intel documentation about debug registers + Win internals, but I didnt understands exactly what happen.

I want to place Hardware Breakpoint in my proc (Not with Olly! I'll do that with Get\SetThreadContex) and to be able to catch it in my proc, somthing like raise exception and to catch it in my Exception Handler.

Example: I put H-BP on DWORD x (in memory.) ,the RD0 is set to &x and RD7 is set to break on write.

when I run this program with a debuger, it stopped after the attempt to write into x ( Olly think it was step over and stopped).

But if I run it without debuger, the execution stopped, without any exception(at least that is what im thinking now, becouse My handler is the first one, and it do nothing...)

help?

xcracx
June 20th, 2005, 14:25
go to ollydbg and go To options.. breakpoints

mark all the checks Ignore ....
all of them

then try it out
if its not working when olly breaks go to options then breakpoints
and click add_last

if i got you right its gonna work goodluck

xcracx

bud_gd
July 11th, 2005, 20:11
Is it not at all possible to set a hardware BP in order to follow through w/ unpacking if running win9x ? or must I rely on using scripts only to achieve my goal? thanx.

joe
July 12th, 2005, 11:29
Is it not at all possible to set a hardware BP in order to follow through w/ unpacking if running win9x ?
I don't test it, but OllyGhost can make kernel writeablein 9x, then can be set BP.

bud_gd
July 19th, 2005, 20:57
thanks i'll give ollyghost a try. im currently on other projects but let know how worked for me, thanx.