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    SubjectRe: [PATCH] arm64: ftrace: stop using kstop_machine to enable/disable tracing
    On Sat, 28 Nov 2015 15:50:09 +0800
    Li Bin <huawei.libin@huawei.com> wrote:

    > On arm64, kstop_machine which is hugely disruptive to a running
    > system is not needed to convert nops to ftrace calls or back,
    > because that modifed code is a single 32bit instructions which
    > is impossible to cross cache (or page) boundaries, and the used str
    > instruction is single-copy atomic.

    Is this really true? I thought that arm (and then perhaps arm64) has
    some 2 byte instructions. If that's the case it is very well possible
    that a 4 byte instruction can cross cache lines.

    -- Steve

    >
    > Cc: <stable@vger.kernel.org> # 3.18+
    > Signed-off-by: Li Bin <huawei.libin@huawei.com>
    > ---
    > arch/arm64/kernel/ftrace.c | 5 +++++
    > 1 files changed, 5 insertions(+), 0 deletions(-)


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