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    SubjectRe: [PATCH 05/11] kasan, arm64: allow using KUnit tests with HW_TAGS mode
    On Tue, Jan 05, 2021 at 07:27:49PM +0100, Andrey Konovalov wrote:
    > diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
    > index 3c40da479899..57d3f165d907 100644
    > --- a/arch/arm64/mm/fault.c
    > +++ b/arch/arm64/mm/fault.c
    > @@ -302,12 +302,20 @@ static void die_kernel_fault(const char *msg, unsigned long addr,
    > static void report_tag_fault(unsigned long addr, unsigned int esr,
    > struct pt_regs *regs)
    > {
    > - bool is_write = ((esr & ESR_ELx_WNR) >> ESR_ELx_WNR_SHIFT) != 0;
    > + static bool reported;
    > + bool is_write;
    > +
    > + if (READ_ONCE(reported))
    > + return;
    > +
    > + if (mte_report_once())
    > + WRITE_ONCE(reported, true);

    I guess the assumption here is that you don't get any report before the
    tests start and temporarily set report_once to false. It's probably
    fine, if we get a tag check failure we'd notice in the logs anyway.

    > /*
    > * SAS bits aren't set for all faults reported in EL1, so we can't
    > * find out access size.
    > */
    > + is_write = ((esr & ESR_ELx_WNR) >> ESR_ELx_WNR_SHIFT) != 0;

    I now noticed, you could write this in a shorter way:

    is_write = !!(esr & ESR_ELx_WNR);

    > kasan_report(addr, 0, is_write, regs->pc);
    > }

    The patch looks fine to me.

    Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

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