Re: [User-mode-linux-devel] Performance enhancement idea / security issue...

[Jeff D. <jd...@ka...>]

sa...@sk... said:
> I was talking about replacing int 80's as they are found, with ud2
> (ud2 is a 2 byte opcode that generates an illegal instruction
> exception [SIGILL]).  That way any int 80s would still be trapped.

OK, that's not too different from my idea of having the system call path in 
the host generate a SIGSYSCALL.

The main difference being that ud2 could be implemented today.  Did you say 
that you might be interested in implementing it?  If so, go right ahead...

You'll have to add a SIGILL handler, have it run on the kernel stack (see 
trampoline in arch/um/kernel/process.c), and have it do essentially what 
syscall_handler does.

				Jeff