Re: [PATCH 28/31] kasan: add kasan.vmalloc command line flag

[Andrey Konovalov]

On Fri, Dec 3, 2021 at 1:09 PM Marco Elver <elver@xxxxxxxxxx> wrote:
>
> On Tue, Nov 30, 2021 at 11:08PM +0100, andrey.konovalov@xxxxxxxxx wrote:
> [...]
> >  enum kasan_arg_stacktrace {
> >       KASAN_ARG_STACKTRACE_DEFAULT,
> >       KASAN_ARG_STACKTRACE_OFF,
> > @@ -40,6 +46,7 @@ enum kasan_arg_stacktrace {
> >
> >  static enum kasan_arg kasan_arg __ro_after_init;
> >  static enum kasan_arg_mode kasan_arg_mode __ro_after_init;
> > +static enum kasan_arg_vmalloc kasan_arg_vmalloc __ro_after_init;
> >  static enum kasan_arg_stacktrace kasan_arg_stacktrace __ro_after_init;
>
> It just occurred to me that all of these (except kasan_arg_mode) are
> only used by __init functions, so they could actually be marked
> __initdata instead of __ro_after_init to free up some bytes after init.

*Except kasan_arg_mode and kasan_arg. Both are accessed by
kasan_init_hw_tags_cpu(), which is not __init to support hot-plugged
CPUs.

However, kasan_arg_stacktrace and kasan_arg_vmalloc can indeed be
marked as __initdata, will do in v2.

> [...]
> > +     switch (kasan_arg_vmalloc) {
> > +     case KASAN_ARG_VMALLOC_DEFAULT:
> > +             /* Default to enabling vmalloc tagging. */
> > +             static_branch_enable(&kasan_flag_vmalloc);
> > +             break;
> > +     case KASAN_ARG_VMALLOC_OFF:
> > +             /* Do nothing, kasan_flag_vmalloc keeps its default value. */
> > +             break;
> > +     case KASAN_ARG_VMALLOC_ON:
> > +             static_branch_enable(&kasan_flag_vmalloc);
> > +             break;
> > +     }
>
> The KASAN_ARG_STACKTRACE_DEFAULT and KASAN_ARG_VMALLOC_ON cases can be
> combined.

Will do in v2.

Thanks!