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    SubjectRe: [PATCH] arm64: kasan: clear stale stack poison
    On Thu, Feb 18, 2016 at 06:03:54PM +0000, Will Deacon wrote:
    > On Thu, Feb 18, 2016 at 05:54:47PM +0000, Catalin Marinas wrote:
    > > On Thu, Feb 18, 2016 at 05:27:38PM +0000, Mark Rutland wrote:
    > > > @@ -145,6 +146,7 @@ ENTRY(cpu_resume_mmu)
    > > > ENDPROC(cpu_resume_mmu)
    > > > .popsection
    > > > cpu_resume_after_mmu:
    > > > + kasan_unpoison_stack 96
    > >
    > > I don't think the 96 here is needed since we populate the stack in
    > > assembly (__cpu_suspend_enter) and unwind it again still in assembly
    > > (cpu_resume_after_mmu), so no KASAN shadow writes/reads.
    > >
    > > Otherwise the patch looks fine.
    >
    > I'd much rather it was written in C -- is there a reason we can't do
    > that if we use a separate compilation unit where the compiler will
    > honour the fno-sanitize flag?

    A simple, non-sanitised C wrapper around __cpu_suspend_enter() would
    probably work. We need to make sure it is static inline when !KASAN to
    avoid an unnecessary function call. Or we just move cpu_suspend() to a
    different compilation unit, though that's a slightly larger function
    which we may want to track under KASAN.

    --
    Catalin

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