xen: arm32: resync bitops with Linux v3.14-rc7

xen: arm32: resync bitops with Linux v3.14-rc7

This pulls in the following Linux commits:

commit c36ef4b1762302a493c6cb754073bded084700e2
Author: Will Deacon <will.deacon@arm.com>
Date:   Wed Nov 23 11:28:25 2011 +0100

    ARM: 7171/1: unwind: add unwind directives to bitops assembly macros

    The bitops functions (e.g. _test_and_set_bit) on ARM do not have unwind
    annotations and therefore the kernel cannot backtrace out of them on a
    fatal error (for example, NULL pointer dereference).

    This patch annotates the bitops assembly macros with UNWIND annotations
    so that we can produce a meaningful backtrace on error. Callers of the
    macros are modified to pass their function name as a macro parameter,
    enforcing that the macros are used as standalone function implementations.

    Acked-by: Dave Martin <dave.martin@linaro.org>
    Signed-off-by: Will Deacon <will.deacon@arm.com>
    Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
commit d779c07dd72098a7416d907494f958213b7726f3
Author: Will Deacon <will.deacon@arm.com>
Date:   Thu Jun 27 12:01:51 2013 +0100

    ARM: bitops: prefetch the destination word for write prior to strex

    The cost of changing a cacheline from shared to exclusive state can be
    significant, especially when this is triggered by an exclusive store,
    since it may result in having to retry the transaction.

    This patch prefixes our atomic bitops implementation with prefetchw,
    to try and grab the line in exclusive state from the start. The testop
    macro is left alone, since the barrier semantics limit the usefulness
    of prefetching data.

    Acked-by: Nicolas Pitre <nico@linaro.org>
    Signed-off-by: Will Deacon <will.deacon@arm.com>
commit b7ec699405f55667caeb46d96229d75bf33a83ad
Author: Will Deacon <will.deacon@arm.com>
Date:   Tue Nov 19 15:46:11 2013 +0100

    ARM: 7893/1: bitops: only emit .arch_extension mp if CONFIG_SMP

    Uwe reported a build failure when targetting a NOMMU platform with my
    recent prefetch changes:

      arch/arm/lib/changebit.S: Assembler messages:
      arch/arm/lib/changebit.S:15: Error: architectural extension `mp' is
                        not allowed for the current base architecture

    This is due to use of the .arch_extension mp directive immediately prior
    to an ALT_SMP(...) instruction. Whilst the ALT_SMP macro will expand to
    nothing if !CONFIG_SMP, gas will still choke on the directive.

    This patch fixes the issue by only emitting the sequence (including the
    directive) if CONFIG_SMP=y.

    Tested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
    Signed-off-by: Will Deacon <will.deacon@arm.com>
    Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Tim Deegan <tim@xen.org>