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).
> +
> + for (ct = range.start; ct < range.stop; ct = ((void *)ct + desc->tag_size))
> + callback(ct);
> +}
> +
> static int codetag_module_init(struct codetag_type *cttype, struct module *mod)
> {
> struct codetag_range range;
> --
> 2.34.1
>
