[RFC PATCH 1/7] kasan: do not open-code addr_has_shadow

[Daniel Axtens <dja@axtens.net>]

We have a couple of places checking for the existence of a shadow
mapping for an address by open-coding the inverse of the check in
addr_has_shadow.

Replace the open-coded versions with the helper. This will be
needed in future to allow architectures to override the layout
of the shadow mapping.

Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 mm/kasan/generic.c | 3 +--
 mm/kasan/tags.c    | 3 +--
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
index 504c79363a34..9e5c989dab8c 100644
--- a/mm/kasan/generic.c
+++ b/mm/kasan/generic.c
@@ -173,8 +173,7 @@ static __always_inline void check_memory_region_inline(unsigned long addr,
 	if (unlikely(size == 0))
 		return;
 
-	if (unlikely((void *)addr <
-		kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
+	if (unlikely(!addr_has_shadow((void *)addr))) {
 		kasan_report(addr, size, write, ret_ip);
 		return;
 	}
diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c
index 63fca3172659..87ebee0a6aea 100644
--- a/mm/kasan/tags.c
+++ b/mm/kasan/tags.c
@@ -109,8 +109,7 @@ void check_memory_region(unsigned long addr, size_t size, bool write,
 		return;
 
 	untagged_addr = reset_tag((const void *)addr);
-	if (unlikely(untagged_addr <
-			kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
+	if (unlikely(!addr_has_shadow(untagged_addr))) {
 		kasan_report(addr, size, write, ret_ip);
 		return;
 	}
-- 
2.19.1