Re: [PATCH v2 0/4] kasan, arm64, scs, stacktrace: collect stack traces from Shadow Call Stack

[Andrey Konovalov]

On Tue, Mar 29, 2022 at 8:36 PM Andrey Konovalov <andreyknvl@xxxxxxxxx> wrote:
>
> On Mon, Mar 28, 2022 at 2:36 PM Marco Elver <elver@xxxxxxxxxx> wrote:
> >
> > > Changes v1->v2:
> > > - Provide a kernel-wide stack_trace_save_shadow() interface for collecting
> > >   stack traces from shadow stack.
> > > - Use ptrauth_strip_insn_pac() and READ_ONCE_NOCHECK, see the comments.
> > > - Get SCS pointer from x18, as per-task value is meant to save the SCS
> > >   value on CPU switches.
> > > - Collect stack frames from SDEI and IRQ contexts.
> >
> > Do any of these new changes introduce new (noticeable) overhead (in
> > particular patch 2)?
>
> I'll measure the overheads and include the results into v3. Thanks!

Hm, looks like the overhead is overly significant: ~5%. I'll explore a
different approach in v3 instead.