Re: [PATCH v3 06/15] powerpc/32: prepare for CONFIG_VMAP_STACK

[Andrew Donnellan]

On 18/10/19 5:46 pm, Christophe Leroy wrote:
> Le 17/10/2019 Ã 09:36, Andrew Donnellan a ÃcritÂ:
> > On 10/9/19 7:16 pm, Christophe Leroy wrote:
> > > +#if defined(CONFIG_VMAP_STACK) && CONFIG_THREAD_SHIFT < PAGE_SHIFT
> > > +#define THREAD_SHIFTÂÂÂÂÂÂÂ PAGE_SHIFT
> > > +#else
> > > Â #define THREAD_SHIFTÂÂÂÂÂÂÂ CONFIG_THREAD_SHIFT
> > > +#endif
> > >
> > > Â #define THREAD_SIZEÂÂÂÂÂÂÂ (1 << THREAD_SHIFT)
> >
> > Looking at 64-bit book3s: with 64K pages, this results in a 
> > THREAD_SIZE that's too large for immediate mode arithmetic operations, 
> > which is annoying. Hmm.
>
> Which operation are you thinking about ?
>
> For instance, 'addi' can't be used anymore, but 'addis' can.

Right, I didn't look too closely - yes, they're "addi"s. But also 
DS-form stores:

	stdu	r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r3)

Anyway, this is just the first thing that broke when I wondered whether 
a ppc64le_defconfig would even build if I just switched on VMAP_STACK, 
I'll work around it

--
Andrew Donnellan              OzLabs, ADL Canberra
ajd@xxxxxxxxxxxxx             IBM Australia Limited