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Subject[PATCH mm v3 14/38] kasan, page_alloc: simplify kasan_unpoison_pages call site
Date
From: Andrey Konovalov <andreyknvl@google.com>

Simplify the checks around kasan_unpoison_pages() call in
post_alloc_hook().

The logical condition for calling this function is:

- If a software KASAN mode is enabled, we need to mark shadow memory.
- Otherwise, HW_TAGS KASAN is enabled, and it only makes sense to
set tags if they haven't already been cleared by tag_clear_highpage(),
which is indicated by init_tags.

This patch concludes the simplifications for post_alloc_hook().

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
mm/page_alloc.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 90a2f353d230..497db24ed169 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2433,15 +2433,18 @@ inline void post_alloc_hook(struct page *page, unsigned int order,
/* Note that memory is already initialized by the loop above. */
init = false;
}
- if (kasan_has_integrated_init()) {
- if (!init_tags) {
- kasan_unpoison_pages(page, order, init);
+ /*
+ * If either a software KASAN mode is enabled, or,
+ * in the case of hardware tag-based KASAN,
+ * if memory tags have not been cleared via tag_clear_highpage().
+ */
+ if (!IS_ENABLED(CONFIG_KASAN_HW_TAGS) || !init_tags) {
+ /* Mark shadow memory or set memory tags. */
+ kasan_unpoison_pages(page, order, init);

- /* Note that memory is already initialized by KASAN. */
+ /* Note that memory is already initialized by KASAN. */
+ if (kasan_has_integrated_init())
init = false;
- }
- } else {
- kasan_unpoison_pages(page, order, init);
}
/* If memory is still not initialized, do it now. */
if (init)
--
2.25.1
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