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    SubjectRe: [PATCH v5 0/2] arm64: Fix pending single-step debugging issues
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    Hi,

    Is this expected to change single-stepping operation in usespace for debuggers (gdb/lldb)? If so, it would be nice to at least
    test it a little to make sure it works.

    On 1/24/23 18:04, Daniel Thompson wrote:
    > On Thu, Jan 12, 2023 at 02:52:49PM +0530, Sumit Garg wrote:
    >> Hi Will, Catalin,
    >>
    >> On Mon, 19 Dec 2022 at 15:55, Sumit Garg <sumit.garg@linaro.org> wrote:
    >>>
    >>> This patch-set reworks pending fixes from Wei's series [1] to make
    >>> single-step debugging via kgdb/kdb on arm64 work as expected. There was
    >>> a prior discussion on ML [2] regarding if we should keep the interrupts
    >>> enabled during single-stepping. So patch #1 follows suggestion from Will
    >>> [3] to not disable interrupts during single stepping but rather skip
    >>> single stepping within interrupt handler.
    >>>
    >>> [1] https://lore.kernel.org/all/20200509214159.19680-1-liwei391@huawei.com/
    >>> [2] https://lore.kernel.org/all/CAD=FV=Voyfq3Qz0T3RY+aYWYJ0utdH=P_AweB=13rcV8GDBeyQ@mail.gmail.com/
    >>> [3] https://lore.kernel.org/all/20200626095551.GA9312@willie-the-truck/
    >>>
    >>> Changes in v5:
    >>> - Incorporated misc. comments from Mark.
    >>>
    >>
    >> Since patch #1 has already been reviewed/acked by Mark and the
    >> complete patchset has been tested by Doug, would it be fine for you to
    >> pick up this patchset? It fixes a real single stepping problem for
    >> kgdb on arm64.
    >
    > Sorry to be quiet for so long.
    >
    > Testing this patch set has proven to be a little difficult.
    >
    > It certainly fixes the single step tests in the kgdbtest suite.
    > That's a good start.
    >
    > Unfortunately when testing using qemu/KVM (hosted on NXP
    > 2k/Solidrun Honeycomb) the patch set is resulting in instability
    > running the built-in self tests (specifically this one:
    > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/misc/kgdbts.c#n74 ). Running this test using the kgdbtest harness
    > results in the test failing roughly a third of the time.
    >
    > The error reported is that the trap handler tried to unlock a spinlock
    > that isn't currently locked. To be honest I suspect this is a generic
    > problem that the new feature happens to tickle (this test has
    > historically been unreliable on x86 too... and x86 is noteworthy for
    > being the only other platform I test using KVM rather than pure qemu).
    > Of course the only way to prove that would be to find and fix the
    > problem in the trap handler (which probably involves rewriting it) and I
    > haven't managed to do that yet.
    >
    > In short, I think the debugger is more useful with this patchset than
    > without so, although it is caveated by the above, I'd call this:
    >
    > Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
    > Tested-by: Daniel Thompson <daniel.thompson@linaro.org>
    >
    >
    > Daniel.
    >
    > _______________________________________________
    > linux-arm-kernel mailing list
    > linux-arm-kernel@lists.infradead.org
    > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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