linux-kernel - Re: [RFC PATCH] ARM: UNWINDER_FRAME

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Message-ID: <CAJkfWY5EL+MyRzSfcfJF2H8WoX73FEO0bOrwcoR4c4ekvaWvOQ@mail.gmail.com>
Date:   Tue, 6 Aug 2019 14:29:16 -0700
From:   Nathan Huckleberry <nhuck@...gle.com>
To:     Dave Martin <Dave.Martin@....com>
Cc:     Robin Murphy <robin.murphy@....com>,
        clang-built-linux <clang-built-linux@...glegroups.com>,
        Tri Vo <trong@...gle.com>, linux@...linux.org.uk,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] ARM: UNWINDER_FRAME_POINTER implementation for Clang

I'm not sure that we should disable a broken feature instead of
attempting a fix.

CONFIG_FUNCTION_GRAPH_TRACER is dependent on CONFIG_FRAME_POINTER and
there have been reports by MediaTek that the frame pointer unwinder is
faster in some cases.

On Mon, Aug 5, 2019 at 6:39 AM Dave Martin <Dave.Martin@....com> wrote:
>
> On Fri, Aug 02, 2019 at 10:27:30AM -0700, Nathan Huckleberry wrote:
> > You're right. Would pushing an extra register be an adequate fix?
>
> Would forcing CONFIG_ARM_UNWIND=y for clang work as an alternative to
> this?
>
> Assuming clang supports -funwind-tables or equivalent, this may just
> work.
>
> [...]
>
> Cheers
> ---Dave