[PATCH 3/5] codetag: Introduce codetag_early_walk()

From: Kees Cook
Date: Fri Aug 09 2024 - 03:33:24 EST


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;
+
+ 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