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From:   John Stultz <john.stultz@linaro.org>
Date:   Tue, 18 May 2021 11:21:55 -0700
Message-ID: <CALAqxLXzvZ++1eCtSiuxpSxA=-M86JWj_+FbRbvq1mDkgq-hMw@mail.gmail.com>
Subject: Re: REGRESSION: kernel BUG at arch/arm64/kernel/alternative.c:157!
To:     Mark Rutland <mark.rutland@arm.com>
Cc:     Marc Zyngier <maz@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Kees Cook <keescook@chromium.org>,
        Will Deacon <will@kernel.org>,
        Sami Tolvanen <samitolvanen@google.com>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        YongQin Liu <yongqin.liu@linaro.org>,
        Amit Pundir <amit.pundir@linaro.org>,
        Michael Walle <michael@walle.cc>,
        Mark Brown <broonie@kernel.org>,
        Masahiro Yamada <masahiroy@kernel.org>
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On Tue, May 18, 2021 at 2:59 AM Mark Rutland <mark.rutland@arm.com> wrote:
>
> Adding Mark Brown and Mazahiro Yamada.
>
> It looks like there's a dependency issue where assembly files don't get rebuilt
> when a generated header they depend upon is rebuilt, and from commit:
>
>   0c6c2d3615efb7c2 ("arm64: Generate cpucaps.h")
>
> ... we can have stale objects with old cpucap values.


Thanks for confirming! I've also verified that things do get back to
booting ok w/ v5.13-rc2 after a make clean, so it does seem like some
sort of dependency, which explains the inconsistent bisection.

thanks
-john