Re: [PATCH 1/2] powerpc/irq: don't use current_stack_pointer() in check_stack_overflow()

[Christophe Leroy]

On 01/24/2020 06:19 AM, Christophe Leroy wrote:
> Le 24/01/2020 Ã 06:46, Michael Ellerman a ÃcritÂ:
> > If I do this it seems to work, but feels a little dicey:
> >
> > ÂÂÂÂasm ("" : "=r" (r1));
> > ÂÂÂÂsp = r1 & (THREAD_SIZE - 1);
>
>
> Or we could do add in asm/reg.h what we have in boot/reg.h:
>
> register void *__stack_pointer asm("r1");
> #define get_sp()ÂÂÂ (__stack_pointer)
>
> And use get_sp()

It works, and I guess doing it this way is acceptable as it's exactly 
what's done for current in asm/current.h with register r2.

Now I (still) get:

	sp = get_sp() & (THREAD_SIZE - 1);
 b9c:	54 24 04 fe 	clrlwi  r4,r1,19
	if (unlikely(sp < 2048)) {
 ba4:	2f 84 07 ff 	cmpwi   cr7,r4,2047





Allthough GCC 8.1 what doing exactly the same with the form CLANG don't 
like:

	register unsigned long r1 asm("r1");
	long sp = r1 & (THREAD_SIZE - 1);
 b84:	54 24 04 fe 	clrlwi  r4,r1,19
	if (unlikely(sp < 2048)) {
 b8c:	2f 84 07 ff 	cmpwi   cr7,r4,2047


Christophe