On Sun, 14 Apr 2013 21:12:05 +0200, Oleg Nesterov wrote:
> Jan, Frederic, et all. What do you think we should do?
>
> 1. Change ptrace_write_dr7() to do register_user_hw_breakpoint()
> if necessary.
>
> This is what I was going to do, but I am no longer sure
> we want this. For what? Unlikely it is very useful to use
> the "default" addr == 0 for debugging.
I do not understand how these functions map to the PTRACE_* syscall.
But this was a regression from the application point of view as some
application did/do:
* waitpid - get the process to: t (tracing stop)
* PTRACE_POKEUSER DR7, enableDR0
* PTRACE_POKEUSER DR0, address
* PTRACE_CONT
This was perfectly valid before, there is no "default" addr == 0 used for any
debugging. Just the applications did not care about PTRACE_POKEUSER ordering.
This is also how the bug was found.
Thanks,
Jan
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