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    SubjectRe: [PATCH v3 1/7] arm64: introduce basic aarch64 instruction decoding helpers
    On Wed, Oct 16, 2013 at 06:14:50PM +0100, Jiang Liu wrote:
    > On 10/16/2013 11:36 PM, Jiang Liu wrote:
    > > On 10/16/2013 06:51 PM, Will Deacon wrote:
    > >> Take care here:
    > >>
    > >> - This doesn't guarantee that CPUs exclusively see new_insn (they
    > >> may see old_insn, even after patching)
    > > Good point. Still need some synchronization mechanism lighter than
    > > stop_machine(). How about kick_all_cpus_sync(), which should be lighter
    > > than stop_machine()?
    > For jump label, x86 uses three smp_call_function() to replace a
    > stop_machine(). Seems it's valuable for us to use just one
    > kick_all_cpus_sync() to avoid a stop_machine().

    Yes, the exception return after handling the IPI from kick_all_cpus_sync
    should be enough to synchronise the pipeline, providing that all cache
    maintenance by the CPU writing the new instructions has completed (if you're
    using flush_icache_range then you're fine).

    Will


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