Re: [PATCH 07/39] x86/entry/32: Enter the kernel via trampoline stack

[Thomas Gleixner]

On Wed, 18 Jul 2018, Brian Gerst wrote:
> > +.Lcopy_pt_regs_\@:
> > +#endif
> > +
> > +       /* Allocate frame on task-stack */
> > +       subl    %ecx, %edi
> > +
> > +       /* Switch to task-stack */
> > +       movl    %edi, %esp
> > +
> > +       /*
> > +        * We are now on the task-stack and can safely copy over the
> > +        * stack-frame
> > +        */
> > +       shrl    $2, %ecx
> 
> This shift can be removed if you divide the constants by 4 above.
> Ditto on the exit path in the next patch.

No, the

> > +       /* Allocate frame on task-stack */
> > +       subl    %ecx, %edi

needs the full value in bytes ....

Thanks,

	tglx