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

On Mon, Feb 03, 2014 at 03:55:42PM +0000, Leif Lindholm wrote:

On Mon, Feb 03, 2014 at 10:34:15AM +0000, Will Deacon wrote:

quoted

On Thu, Jan 30, 2014 at 01:12:47PM +0000, Leif Lindholm wrote:

quoted

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?

Yeah.

quoted

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	.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?

The first one could.
The second one could be movw on armv7+.

quoted

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

And your preference between 1) and 2) is?

(1), using bic and mov[tw] where possible.

Will