1/* SPDX-License-Identifier: GPL-2.0 */
 2#ifndef __ASM_KASAN_H
 3#define __ASM_KASAN_H
 4
 5#include <asm/pgtable.h>
 6
 7#ifdef CONFIG_KASAN
 8
 9#define KASAN_SHADOW_SCALE_SHIFT 3
10#define KASAN_SHADOW_SIZE						       \
11	(_AC(1, UL) << (_REGION1_SHIFT - KASAN_SHADOW_SCALE_SHIFT))
12#define KASAN_SHADOW_OFFSET	_AC(CONFIG_KASAN_SHADOW_OFFSET, UL)
13#define KASAN_SHADOW_START	KASAN_SHADOW_OFFSET
14#define KASAN_SHADOW_END	(KASAN_SHADOW_START + KASAN_SHADOW_SIZE)
15
16extern void kasan_early_init(void);
17extern void kasan_copy_shadow_mapping(void);
18extern void kasan_free_early_identity(void);
19
20/*
21 * Estimate kasan memory requirements, which it will reserve
22 * at the very end of available physical memory. To estimate
23 * that, we take into account that kasan would require
24 * 1/8 of available physical memory (for shadow memory) +
25 * creating page tables for the whole memory + shadow memory
26 * region (1 + 1/8). To keep page tables estimates simple take
27 * the double of combined ptes size.
28 *
29 * physmem parameter has to be already adjusted if not entire physical memory
30 * would be used (e.g. due to effect of "mem=" option).
31 */
32static inline unsigned long kasan_estimate_memory_needs(unsigned long physmem)
33{
34	unsigned long kasan_needs;
35	unsigned long pages;
36	/* for shadow memory */
37	kasan_needs = round_up(physmem / 8, PAGE_SIZE);
38	/* for paging structures */
39	pages = DIV_ROUND_UP(physmem + kasan_needs, PAGE_SIZE);
40	kasan_needs += DIV_ROUND_UP(pages, _PAGE_ENTRIES) * _PAGE_TABLE_SIZE * 2;
41
42	return kasan_needs;
43}
44#else
45static inline void kasan_early_init(void) { }
46static inline void kasan_copy_shadow_mapping(void) { }
47static inline void kasan_free_early_identity(void) { }
48static inline unsigned long kasan_estimate_memory_needs(unsigned long physmem) { return 0; }
49#endif
50
51#endif