[PATCH] ARM: implement optimized percpu variable access

[Will Deacon]

On Mon, Nov 12, 2012 at 01:03:12PM +0000, Rob Herring wrote:
> On 11/12/2012 04:23 AM, Will Deacon wrote:
> >> +static inline void set_my_cpu_offset(unsigned long off)
> >> +{
> >> +	asm volatile("mcr p15, 0, %0, c13, c0, 4	@ set TPIDRPRW" : : "r" (off) : "cc" );
> >> +}
> > 
> > You don't need the "cc" here.
> 
> You would think so, but the compiler drops this instruction if you
> don't. set_cr does the same thing.

Whoa, that sounds suspicious... if the thing is marked volatile GCC
shouldn't optimise it away if it's reachable. Which toolchain are you
using?

Will