1 files changed, 47 insertions, 0 deletions
diff --git a/arch/s390/include/asm/kasan.h b/arch/s390/include/asm/kasan.h
new file mode 100644
index 000000000..e5cfc81d5
--- /dev/null
+++ b/arch/s390/include/asm/kasan.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_KASAN_H
+#define __ASM_KASAN_H
+
+#include <asm/pgtable.h>
+
+#ifdef CONFIG_KASAN
+
+#define KASAN_SHADOW_SCALE_SHIFT 3
+#define KASAN_SHADOW_SIZE						       \
+	(_AC(1, UL) << (_REGION1_SHIFT - KASAN_SHADOW_SCALE_SHIFT))
+#define KASAN_SHADOW_OFFSET	_AC(CONFIG_KASAN_SHADOW_OFFSET, UL)
+#define KASAN_SHADOW_START	KASAN_SHADOW_OFFSET
+#define KASAN_SHADOW_END	(KASAN_SHADOW_START + KASAN_SHADOW_SIZE)
+
+extern void kasan_early_init(void);
+
+/*
+ * Estimate kasan memory requirements, which it will reserve
+ * at the very end of available physical memory. To estimate
+ * that, we take into account that kasan would require
+ * 1/8 of available physical memory (for shadow memory) +
+ * creating page tables for the shadow memory region.
+ * To keep page tables estimates simple take the double of
+ * combined ptes size.
+ *
+ * physmem parameter has to be already adjusted if not entire physical memory
+ * would be used (e.g. due to effect of "mem=" option).
+ */
+static inline unsigned long kasan_estimate_memory_needs(unsigned long physmem)
+{
+	unsigned long kasan_needs;
+	unsigned long pages;
+	/* for shadow memory */
+	kasan_needs = round_up(physmem / 8, PAGE_SIZE);
+	/* for paging structures */
+	pages = DIV_ROUND_UP(kasan_needs, PAGE_SIZE);
+	kasan_needs += DIV_ROUND_UP(pages, _PAGE_ENTRIES) * _PAGE_TABLE_SIZE * 2;
+
+	return kasan_needs;
+}
+#else
+static inline void kasan_early_init(void) { }
+static inline unsigned long kasan_estimate_memory_needs(unsigned long physmem) { return 0; }
+#endif
+
+#endif