1 files changed, 71 insertions, 0 deletions
diff --git a/mm/kasan/report_hw_tags.c b/mm/kasan/report_hw_tags.c
new file mode 100644
index 000000000000..065e1b2fc484
--- /dev/null
+++ b/mm/kasan/report_hw_tags.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This file contains hardware tag-based KASAN specific error reporting code.
+ *
+ * Copyright (c) 2020 Google, Inc.
+ * Author: Andrey Konovalov <andreyknvl@google.com>
+ */
+
+#include <linux/kasan.h>
+#include <linux/kernel.h>
+#include <linux/memory.h>
+#include <linux/mm.h>
+#include <linux/string.h>
+#include <linux/types.h>
+
+#include "kasan.h"
+
+const void *kasan_find_first_bad_addr(const void *addr, size_t size)
+{
+	/*
+	 * Hardware Tag-Based KASAN only calls this function for normal memory
+	 * accesses, and thus addr points precisely to the first bad address
+	 * with an invalid (and present) memory tag. Therefore:
+	 * 1. Return the address as is without walking memory tags.
+	 * 2. Skip the addr_has_metadata check.
+	 */
+	return kasan_reset_tag(addr);
+}
+
+size_t kasan_get_alloc_size(void *object, struct kmem_cache *cache)
+{
+	size_t size = 0;
+	int i = 0;
+	u8 memory_tag;
+
+	/*
+	 * Skip the addr_has_metadata check, as this function only operates on
+	 * slab memory, which must have metadata.
+	 */
+
+	/*
+	 * The loop below returns 0 for freed objects, for which KASAN cannot
+	 * calculate the allocation size based on the metadata.
+	 */
+	while (size < cache->object_size) {
+		memory_tag = hw_get_mem_tag(object + i * KASAN_GRANULE_SIZE);
+		if (memory_tag != KASAN_TAG_INVALID)
+			size += KASAN_GRANULE_SIZE;
+		else
+			return size;
+		i++;
+	}
+
+	return cache->object_size;
+}
+
+void kasan_metadata_fetch_row(char *buffer, void *row)
+{
+	int i;
+
+	for (i = 0; i < META_BYTES_PER_ROW; i++)
+		buffer[i] = hw_get_mem_tag(row + i * KASAN_GRANULE_SIZE);
+}
+
+void kasan_print_tags(u8 addr_tag, const void *addr)
+{
+	u8 memory_tag = hw_get_mem_tag((void *)addr);
+
+	pr_err("Pointer tag: [%02x], memory tag: [%02x]\n",
+		addr_tag, memory_tag);
+}