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>

arch/xtensa/mm/kasan_init.c

@@ -24,12 +24,13 @@ void __init kasan_early_init(void)
 	int i;
 
 	for (i = 0; i < PTRS_PER_PTE; ++i)
-		set_pte(kasan_zero_pte + i,
-			mk_pte(virt_to_page(kasan_zero_page), PAGE_KERNEL));
+		set_pte(kasan_early_shadow_pte + i,
+			mk_pte(virt_to_page(kasan_early_shadow_page),
+				PAGE_KERNEL));
 
 	for (vaddr = 0; vaddr < KASAN_SHADOW_SIZE; vaddr += PMD_SIZE, ++pmd) {
 		BUG_ON(!pmd_none(*pmd));
-		set_pmd(pmd, __pmd((unsigned long)kasan_zero_pte));
+		set_pmd(pmd, __pmd((unsigned long)kasan_early_shadow_pte));
 	}
 	early_trap_init();
 }
@@ -80,13 +81,16 @@ void __init kasan_init(void)
 	populate(kasan_mem_to_shadow((void *)VMALLOC_START),
 		 kasan_mem_to_shadow((void *)XCHAL_KSEG_BYPASS_VADDR));
 
-	/* Write protect kasan_zero_page and zero-initialize it again. */
+	/*
+	 * Write protect kasan_early_shadow_page and zero-initialize it again.
+	 */
 	for (i = 0; i < PTRS_PER_PTE; ++i)
-		set_pte(kasan_zero_pte + i,
-			mk_pte(virt_to_page(kasan_zero_page), PAGE_KERNEL_RO));
+		set_pte(kasan_early_shadow_pte + i,
+			mk_pte(virt_to_page(kasan_early_shadow_page),
+				PAGE_KERNEL_RO));
 
 	local_flush_tlb_all();
-	memset(kasan_zero_page, 0, PAGE_SIZE);
+	memset(kasan_early_shadow_page, 0, PAGE_SIZE);
 
 	/* At this point kasan is fully initialized. Enable error messages. */
 	current->kasan_depth = 0;