On Thu, 19 Nov 2009, Linus Torvalds wrote:
> On Thu, 19 Nov 2009, Richard Guenther wrote:
> >
> > Note that I only can reproduce the issue with
> > -mincoming-stack-boundary=2, not with -mpreferred-stack-boundary=2.
>
> Since you can reproduce it with -mincoming-stack-boundary=2, I woul
> suggest just fixing mcount handling that way regardless of anything else.
> The current code generated by gcc is just insane - even for the case where
> you _want_ 16-byte stack alignment.
>
> Instead crazy code like
>
> > push %edi
> > lea 0x8(%esp),%edi
> > and $0xfffffff0,%esp
> > pushl -0x4(%edi)
> > push %ebp
> > mov %esp,%ebp
> > ...
> > call mcount
>
> the sane thing to do would be to just do it as
>
> push %ebp
> mov %esp,%ebp
> call mcount
> and $0xfffffff0,%esp
which is what the 64bit compile does except that the mcount call
happens a bit later which is fine.
ffffffff8107cd34 <timer_stats_update_stats>:
ffffffff8107cd34: 55 push %rbp
ffffffff8107cd35: 48 89 e5 mov %rsp,%rbp
ffffffff8107cd38: 48 83 e4 c0 and $0xffffffffffffffc0,%rsp
Thanks,
tglx
