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SubjectRe: [PATCH v2 2/2] arm64: scs: use vmapped IRQ and SDEI shadow stacks
On Tue, Dec 01, 2020 at 10:18:19AM +0000, Will Deacon wrote:
> On Mon, Nov 30, 2020 at 01:13:07PM -0800, Sami Tolvanen wrote:
> > On Mon, Nov 30, 2020 at 3:49 AM Will Deacon <will@kernel.org> wrote:
> > > On Tue, Nov 24, 2020 at 11:59:40AM -0800, Sami Tolvanen wrote:
> > > > for_each_possible_cpu(cpu) {
> > > > - err = _init_sdei_stack(&sdei_stack_normal_ptr, cpu);
> > > > - if (err)
> > > > - break;
> > > > - err = _init_sdei_stack(&sdei_stack_critical_ptr, cpu);
> > > > - if (err)
> > > > - break;
> > > > + if (IS_ENABLED(CONFIG_VMAP_STACK)) {
> > > > + err = _init_sdei_stack(&sdei_stack_normal_ptr, cpu);
> > > > + if (err)
> > > > + break;
> > > > + err = _init_sdei_stack(&sdei_stack_critical_ptr, cpu);
> > > > + if (err)
> > > > + break;
> > > > + }
> > > > + if (IS_ENABLED(CONFIG_SHADOW_CALL_STACK)) {
> > > > + err = _init_sdei_scs(&sdei_shadow_call_stack_normal_ptr, cpu);
> > > > + if (err)
> > > > + break;
> > > > + err = _init_sdei_scs(&sdei_shadow_call_stack_critical_ptr, cpu);
> > > > + if (err)
> > > > + break;
> > >
> > > This looks ok to me, but I think it would be better to follow the same
> > > approach as you have for the IRQ stacks and instead have a separate
> > > init_sdei_scs() function (similarly for the free() path), which means
> > > you can simply the IS_ENABLED() checks too.
> >
> > OK, I can change this in v3. It makes error handling in
> > sdei_arch_get_entry_point() a bit more awkward though. We'll need
> > something like this:
> >
> > if (IS_ENABLED(CONFIG_VMAP_STACK)) {
> > if (init_sdei_stacks())
> > return 0;
> > }
> >
> > if (IS_ENABLED(CONFIG_SHADOW_CALL_STACK)) {
> > if (init_sdei_scs()) {
> > if (IS_ENABLED(CONFIG_VMAP_STACK))
> > free_sdei_stacks();
> > return 0;
> > }
>
> Can you push the IS_ENABLED() checks into their respective functions?
> Then you can do something like:
>
> if (init_sdei_stacks())
> return 0;
>
> if (init_sdei_scs())
> goto out_free_stacks;
>
> ...
>
> out_free_stacks:
> free_sdei_stacks();
> return 0;

Wait, I see you already posted a v3. Maybe I can just hack this up on top...

Will

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