[PATCH v4 2/5] arm: add new asm macro update_sctlr

[Will Deacon]

On Thu, Jan 30, 2014 at 01:12:47PM +0000, Leif Lindholm wrote:
> Oh, that's neat - thanks!
> 
> Well, given that, I can think of two less horrible options:
> 1)
> 	.macro  update_sctlr, tmp:req, set=, clear=
>         mrc	p15, 0, \tmp, c1, c0, 0
> 	.ifnc	\set,
>         orr	\tmp, \set
> 	.endif
> 	.ifnc	\clear,
> 	mvn	\clear, \clear
> 	and	\tmp, \tmp, \clear

Can't you use bic here?

> 	.endif
>         mcr	p15, 0, \tmp, c1, c0, 0
> 	.endm
> 
> With the two call sites in uefi_phys.S as:
> 
> 	ldr	r5, =(CR_M)
> 	update_sctlr	r12, , r5
> and
> 	ldr	r4, =(CR_I | CR_C | CR_M)
> 	update_sctlr	r12, r4

These ldr= could be movs, right?

If so, I definitely prefer this to putting an ldr = into the macro itself
(option 2).

Cheers,

Will