[PATCH v2 13/20] arm64: cmpxchg_dbl: patch in lse instructions when supported by the CPU

[Catalin Marinas]

On Fri, Jul 24, 2015 at 11:42:04AM +0100, Will Deacon wrote:
> On CPUs which support the LSE atomic instructions introduced in ARMv8.1,
> it makes sense to use them in preference to ll/sc sequences.
> 
> This patch introduces runtime patching of our cmpxchg_double primitives
> so that the LSE casp instruction is used instead.
> 
> Signed-off-by: Will Deacon <will.deacon at arm.com>

Reviewed-by: Catalin Marinas <catalin.marinas at arm.com>