kasan: rename kasan_zero_page to kasan_early_shadow_page

With tag based KASAN mode the early shadow value is 0xff and not 0x00, so
this patch renames kasan_zero_(page|pte|pmd|pud|p4d) to
kasan_early_shadow_(page|pte|pmd|pud|p4d) to avoid confusion.

Link: http://lkml.kernel.org/r/3fed313280ebf4f88645f5b89ccbc066d320e177.1544099024.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Suggested-by: Mark Rutland <mark.rutland@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index b66fdf5..ec22d54 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -14,13 +14,13 @@
 #include <asm/kasan.h>
 #include <asm/pgtable.h>
 
-extern unsigned char kasan_zero_page[PAGE_SIZE];
-extern pte_t kasan_zero_pte[PTRS_PER_PTE];
-extern pmd_t kasan_zero_pmd[PTRS_PER_PMD];
-extern pud_t kasan_zero_pud[PTRS_PER_PUD];
-extern p4d_t kasan_zero_p4d[MAX_PTRS_PER_P4D];
+extern unsigned char kasan_early_shadow_page[PAGE_SIZE];
+extern pte_t kasan_early_shadow_pte[PTRS_PER_PTE];
+extern pmd_t kasan_early_shadow_pmd[PTRS_PER_PMD];
+extern pud_t kasan_early_shadow_pud[PTRS_PER_PUD];
+extern p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D];
 
-int kasan_populate_zero_shadow(const void *shadow_start,
+int kasan_populate_early_shadow(const void *shadow_start,
 				const void *shadow_end);
 
 static inline void *kasan_mem_to_shadow(const void *addr)