Hi Leif, On Wed, Jan 29, 2014 at 06:28:05PM +0000, Leif Lindholm wrote: > On Wed, Jan 22, 2014 at 11:20:55AM +0000, Will Deacon wrote: > > > +#ifdef CONFIG_CPU_CP15 > > > +/* Macro for setting/clearing bits in sctlr */ > > > + .macro update_sctlr, set:req, clear:req, tmp:req, tmp2:req > > > + mrc p15, 0, \tmp, c1, c0, 0 > > > + ldr \tmp2, =\set > > > + orr \tmp, \tmp, \tmp2 > > > + ldr \tmp2, =\clear > > > + mvn \tmp2, \tmp2 > > > + and \tmp, \tmp, \tmp2 > > > + mcr p15, 0, \tmp, c1, c0, 0 > > > > I think this would be cleaner if you force the caller to put set and clear > > into registers beforehand, rather than have to do the literal load every > > time. Also, I don't think set and clear should be required (and then you can > > lose tmp2 as well). > > I can't figure out how to make register-parameters non-required > (i.e. conditionalise on whether an optional parameter was provided), > so my attempt of refactoring actually ends up using an additional > register: > > #ifdef CONFIG_CPU_CP15 > /* Macro for setting/clearing bits in sctlr */ > .macro update_sctlr, set:req, clear:req, tmp:req > mrc p15, 0, \tmp, c1, c0, 0 > orr \tmp, \set > mvn \clear, \clear > and \tmp, \tmp, \clear > mcr p15, 0, \tmp, c1, c0, 0 > .endm > #endif > > If you think that's an improvement I can do that, and I have (just) > enough registers to spare. > If I'm being daft with my macro issues, do point it out. I was thinking along the lines of: .macro update_sctlr, tmp:req, set=0, clear=0 .if \set orr ... .endif .if \clear bic ... .endif .endm however, that puts us back to the problem of having to pass immediates instead of registers. Gas *does* seem to accept the following: .macro update_sctlr, tmp:req, set=0, clear=0 .if \set != 0 orr ... .endif .if \clear != 0 bic ... .endif .endm which is filthy, so we'd need to see how beautiful the caller ends up being to justify that! Will -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
