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    SubjectRe: [PATCHv3 4/4] ARM: kprobes: make more tests conditional
    On Thu, Aug 23, 2012 at 12:51:01AM +0100, Tixy wrote:
    > On Wed, 2012-08-22 at 18:41 +0000, Arnd Bergmann wrote:
    > > On Wednesday 22 August 2012, Nicolas Pitre wrote:
    > > > On Wed, 22 Aug 2012, Arnd Bergmann wrote:
    > > > > >
    > > > > > The ldrex/strex instructions are available on ARMv6. It's only the d
    > > > > > variants (strexd/ldrexd) which are only available from ARMv6k.
    > > > >
    > > > > Ok. How is the version below then? I haven't tested this one yet.
    > > >
    > > > In fact, I think the b variants are ARMv6k+ as well. Only the plain
    > > > (non b non d) variants are available on ARMv6.
    > >
    > > Ok, third attempt then. This leaves ldrex for ARMv6 but marks
    > > {st,ld}rex{b,h,d} as V6K specific (which includes ARMv7).
    >
    > ARMv7 does set CPU_32v6K, because arch/arm/mm/Kconfig has
    >
    > config CPU_V7
    > bool "Support ARM V7 processor" if ARCH_INTEGRATOR || MACH_REALVIEW_EB || MACH_REALVIEW_PBX
    > select CPU_32v6K
    > select CPU_32v7
    >
    > but this seems more for peripheral reasons not because all the various
    > CPU configs systematically select the earlier architecture variants,
    > e.g. CPU_V7 doesn't select CPU_32v6.
    >
    > So I would have been inclined to test for
    >
    > #if defined(CONFIG_CPU_32v6K) || (__LINUX_ARM_ARCH__ >= 7)

    FWIW, the selection of the optimised atomic64 implementation for ARM (which
    uses the double-word exclusive instructions) boils down to CONFIG_CPU_32v6K,
    so I think the additional __LINUX_ARM_ARCH__ check is probably overkill.

    Will


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