On Fri, Jan 04, 2013 at 10:39:05PM +0100, Leif Ekblad wrote:
> I just tried the patch, but it seems to produce some problems for
> me. The other patch which used a 64-bit specific register (r15)
> instead of rbx was easier to adapt to. The problem for me is that
> syscalls might clobber higher-half of all 32-bit registers, and that
> I cannot use the stack to preserve rbx in the call because of the
> red-zone.
Of course you can use the stack, just subtract the red zone size (plus
whatever you need) from %rsp first, then save to stack, do syscall,
then restore from stack and finally increment %rsp back.
Jakub
