Re: [PATCH 3/6] ARM: Fix v7wbi_tlb_flags for SMP on UP

[Russell King - ARM Linux <linux@arm.linux.org.uk>]

On Mon, Sep 06, 2010 at 04:53:47PM +0100, Catalin Marinas wrote:
> On Mon, 2010-09-06 at 16:34 +0100, Russell King - ARM Linux wrote:
> > On Mon, Sep 06, 2010 at 12:46:34PM +0100, Catalin Marinas wrote:
> > > Would this work with Thumb-2 kernel builds? Maybe you can add a W(instr)
> > > in the SMP/UP macros to make sure that the instruction is always 32-bit
> > > wide.
> > 
> > Probably not, and it's not obvious how to make it work for T2 kernel
> > builds.  For the time being, I'm going to make this available only for
> > native ARM builds.  We can think about how to make this work for T2
> > sometime later.
> [...]
> > Indeed, that's only half of the problem.  On T2, some of these may be
> > 16-bit values, others may be 32-bit values, and this mechanism has no
> > way to know the size of the areas.
> 
> We can add the W() macro and they are guaranteed to be 32-bit wide or
> get a compilation error. Something like using "UP(W(nop))", though it's
> doesn't look as nice.
> 
> The usr_ret macro is always compiled to ARM mode anyway.

That's not the only place - here's another:

+       ALT_SMP(test_for_ipi r0, r6, r5, lr)
+       ALT_UP_B(9997f)

test_for_ipi may be thumb code, which could be 16-bit aligned.