Re: [PATCH v2 0/3] arm64: Convert to ARCH_STACKWALK

[Mark Rutland]

On Wed, Sep 02, 2020 at 06:38:03PM +0100, Mark Brown wrote:
> On Tue, Sep 01, 2020 at 05:06:26PM +0100, Mark Rutland wrote:
> 
> > Just to check, has the skipping logic been tested to work equivalently
> > to what we had before? By inspection I think it should, but since it
> > relies on function call boundaries it always strikes me as fragile.
> 
> > If you could confirm that (e.g. with LKDTM perhaps?) that'd be great.
> > Assuming that looks right, for the series:
> 
> I've tested this with LKDTM and otherwise and didn't spot any issues
> (and just did a bit of retesting) but it is a pretty manual process so
> it's possible I missed something.

It looks like the case Mirolav pointed out (self-bactrace with NULL
regs) isn't triggered by LKDTM (since it always causes a backtrace from
an exception with non-NULL regs), but we do rely on that elsewhere in
the kernel.

It might be worth adding an LKDTM test to trigger that.

I'll wait for a respin that handles that -- please drop the ack for now.

Thanks,
Mark.