Accessing the processor debugging registers at first seemed easy: all I had to do was to use ptrace (PTRACE_{PEEK|POKE}USR,...) and /usr/include/sys/user.h. Well, this is true but ptrace cannot be used to peek and poke at yourself. It can be used only if you are the parent of a ptraced child process and only on the child process. So, I got back to reading the kernel source to find a way to circumvent all these security checks. How sad. Me, being a cracker just because I can't do some very reasonable things...

The funny thing is that writing in my own memory-mapped executable image seems to be as hard as accessing the debugging registers. Yes, I thought I could get away from the hard stuff by writing a good old "int3" where I wanted my breakpoints to be but the only way I seem to be allowed to do this is by using ptrace, and, as explained above, ptrace cannot be used on oneself. *sigh*. So much fun...