[PATCH 00/14] Fix issues with ARMv6+v6k+v7 kernels

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

This patch series reworks the ARMv6/ARMv6K support options, code
selection, and bit operations such that it's possible to safely
build a kernel which supports ARMv6, ARMv6K, ARMv7 and ARMv7 SMP
in one image.

Currently, we use CPU_V6 for both ARMv6 and ARMv6K, setting CPU_32v6K
if we have the K extensions.  CPU_32v6K directly controlled whether
we should include the ARMv6K instructions (clrex, load/store exclusive
byte, half-word, double).  As the bitops code uses the load/store
exclusive byte operations, unsetting CPU_32v6K results in these
falling back to their non-SMP local-irq-disabling variants.  These
are only safe in uniprocessor environments.

So, the first two patches convert the bitops to use the ARMv6 load/store
exclusive word operations - and ensuring correctness by ensuring that
the pointer passed in is word-aligned.

We then introduce a new CPU_V6K which indicates that we're including
an ARMv6K CPU in the build, which frees up CPU_V6 to mean that we're
including an ARMv6 non-K CPU.

We can then use CPU_V6 to ensure that the non-v6K code paths which are
still SMP safe are selected.

Without this patch set, such a kernel will be unsafe when run on
SMP platforms as it omits necessary SMP code to ensure that bit
operations are safe.