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-rw-r--r--include/linux/mm.h18
1 files changed, 15 insertions, 3 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 64a71bf20536..8ba434287387 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1461,16 +1461,28 @@ static inline bool cpupid_match_pid(struct task_struct *task, int cpupid)
#if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS)
+/*
+ * KASAN per-page tags are stored xor'ed with 0xff. This allows to avoid
+ * setting tags for all pages to native kernel tag value 0xff, as the default
+ * value 0x00 maps to 0xff.
+ */
+
static inline u8 page_kasan_tag(const struct page *page)
{
- if (kasan_enabled())
- return (page->flags >> KASAN_TAG_PGSHIFT) & KASAN_TAG_MASK;
- return 0xff;
+ u8 tag = 0xff;
+
+ if (kasan_enabled()) {
+ tag = (page->flags >> KASAN_TAG_PGSHIFT) & KASAN_TAG_MASK;
+ tag ^= 0xff;
+ }
+
+ return tag;
}
static inline void page_kasan_tag_set(struct page *page, u8 tag)
{
if (kasan_enabled()) {
+ tag ^= 0xff;
page->flags &= ~(KASAN_TAG_MASK << KASAN_TAG_PGSHIFT);
page->flags |= (tag & KASAN_TAG_MASK) << KASAN_TAG_PGSHIFT;
}