kasan: define KASAN_VMALLOC_INVALID for SW_TAGS

In preparation for adding vmalloc support to SW_TAGS KASAN, provide a
KASAN_VMALLOC_INVALID definition for it.

HW_TAGS KASAN won't be using this value, as it falls back onto page_alloc
for poisoning freed vmalloc() memory.

Link: https://lkml.kernel.org/r/1daaaafeb148a7ae8285265edc97d7ca07b6a07d.1643047180.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Acked-by: Marco Elver <elver@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

mm/kasan/kasan.h

@@ -71,18 +71,19 @@ static inline bool kasan_sync_fault_possible(void)
 #define KASAN_PAGE_REDZONE      0xFE  /* redzone for kmalloc_large allocations */
 #define KASAN_KMALLOC_REDZONE   0xFC  /* redzone inside slub object */
 #define KASAN_KMALLOC_FREE      0xFB  /* object was freed (kmem_cache_free/kfree) */
+#define KASAN_VMALLOC_INVALID   0xF8  /* unallocated space in vmapped page */
 #else
 #define KASAN_FREE_PAGE         KASAN_TAG_INVALID
 #define KASAN_PAGE_REDZONE      KASAN_TAG_INVALID
 #define KASAN_KMALLOC_REDZONE   KASAN_TAG_INVALID
 #define KASAN_KMALLOC_FREE      KASAN_TAG_INVALID
+#define KASAN_VMALLOC_INVALID   KASAN_TAG_INVALID /* only for SW_TAGS */
 #endif
 
 #ifdef CONFIG_KASAN_GENERIC
 
 #define KASAN_KMALLOC_FREETRACK 0xFA  /* object was freed and has free track set */
 #define KASAN_GLOBAL_REDZONE    0xF9  /* redzone for global variable */
-#define KASAN_VMALLOC_INVALID   0xF8  /* unallocated space in vmapped page */
 
 /*
  * Stack redzone shadow values