On Thu, Aug 29, 2024 at 08:39:29AM -0700, Suren Baghdasaryan wrote:
> On Fri, Aug 9, 2024 at 12:33 AM Kees Cook <kees@xxxxxxxxxx> wrote:
> >
> > In order to process builtin alloc_tags much earlier during boot (before
> > register_codetag() is processed), provide codetag_early_walk() that
> > perform a lockless walk with a specified callback function. This will be
> > used to allocate required caches that cannot be allocated on demand.
> >
> > Signed-off-by: Kees Cook <kees@xxxxxxxxxx>
> > ---
> > Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
> > Cc: Kent Overstreet <kent.overstreet@xxxxxxxxx>
> > Cc: Vlastimil Babka <vbabka@xxxxxxx>
> > Cc: Christoph Lameter <cl@xxxxxxxxx>
> > Cc: Pekka Enberg <penberg@xxxxxxxxxx>
> > Cc: David Rientjes <rientjes@xxxxxxxxxx>
> > Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > Cc: Roman Gushchin <roman.gushchin@xxxxxxxxx>
> > Cc: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
> > Cc: linux-mm@xxxxxxxxx
> > ---
> > include/linux/codetag.h | 2 ++
> > lib/codetag.c | 16 ++++++++++++++++
> > 2 files changed, 18 insertions(+)
> >
> > diff --git a/include/linux/codetag.h b/include/linux/codetag.h
> > index c2a579ccd455..9eb1fcd90570 100644
> > --- a/include/linux/codetag.h
> > +++ b/include/linux/codetag.h
> > @@ -64,6 +64,8 @@ void codetag_lock_module_list(struct codetag_type *cttype, bool lock);
> > bool codetag_trylock_module_list(struct codetag_type *cttype);
> > struct codetag_iterator codetag_get_ct_iter(struct codetag_type *cttype);
> > struct codetag *codetag_next_ct(struct codetag_iterator *iter);
> > +void codetag_early_walk(const struct codetag_type_desc *desc,
> > + void (*callback)(struct codetag *ct));
> >
> > void codetag_to_text(struct seq_buf *out, struct codetag *ct);
> >
> > diff --git a/lib/codetag.c b/lib/codetag.c
> > index ef7634c7ee18..9d563c8c088a 100644
> > --- a/lib/codetag.c
> > +++ b/lib/codetag.c
> > @@ -154,6 +154,22 @@ static struct codetag_range get_section_range(struct module *mod,
> > };
> > }
> >
> > +void codetag_early_walk(const struct codetag_type_desc *desc,
> > + void (*callback)(struct codetag *ct))
> > +{
> > + struct codetag_range range;
> > + struct codetag *ct;
> > +
> > + range = get_section_range(NULL, desc->section);
> > + if (!range.start || !range.stop ||
> > + range.start == range.stop ||
> > + range.start > range.stop)
> > + return;
>
> I think this check can be simplified to:
>
> if (!range.start || range.start >= range.stop)
> return;
>
> nit: Technically (!range.start) should also never trigger. In a valid
> image these symbols are either missing (range.start == range.stop ==
> NULL) or both are defined and (range.start < range.stop).
Yeah, all true. I was mainly copying all the checks that existed in the
"slow path" version.
I will adjust this for the next version.
--
Kees Cook
