1 // SPDX-License-Identifier: GPL-2.0
3 * This file contains some kasan initialization code.
5 * Copyright (c) 2015 Samsung Electronics Co., Ltd.
6 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
14 #include <linux/memblock.h>
15 #include <linux/init.h>
16 #include <linux/kasan.h>
17 #include <linux/kernel.h>
19 #include <linux/pfn.h>
20 #include <linux/slab.h>
23 #include <asm/pgalloc.h>
28 * This page serves two purposes:
29 * - It used as early shadow memory. The entire shadow region populated
30 * with this page, before we will be able to setup normal shadow memory.
31 * - Latter it reused it as zero shadow to cover large ranges of memory
32 * that allowed to access, but not handled by kasan (vmalloc/vmemmap ...).
34 unsigned char kasan_early_shadow_page
[PAGE_SIZE
] __page_aligned_bss
;
36 #if CONFIG_PGTABLE_LEVELS > 4
37 p4d_t kasan_early_shadow_p4d
[MAX_PTRS_PER_P4D
] __page_aligned_bss
;
38 static inline bool kasan_p4d_table(pgd_t pgd
)
40 return pgd_page(pgd
) == virt_to_page(lm_alias(kasan_early_shadow_p4d
));
43 static inline bool kasan_p4d_table(pgd_t pgd
)
48 #if CONFIG_PGTABLE_LEVELS > 3
49 pud_t kasan_early_shadow_pud
[PTRS_PER_PUD
] __page_aligned_bss
;
50 static inline bool kasan_pud_table(p4d_t p4d
)
52 return p4d_page(p4d
) == virt_to_page(lm_alias(kasan_early_shadow_pud
));
55 static inline bool kasan_pud_table(p4d_t p4d
)
60 #if CONFIG_PGTABLE_LEVELS > 2
61 pmd_t kasan_early_shadow_pmd
[PTRS_PER_PMD
] __page_aligned_bss
;
62 static inline bool kasan_pmd_table(pud_t pud
)
64 return pud_page(pud
) == virt_to_page(lm_alias(kasan_early_shadow_pmd
));
67 static inline bool kasan_pmd_table(pud_t pud
)
72 pte_t kasan_early_shadow_pte
[PTRS_PER_PTE
] __page_aligned_bss
;
74 static inline bool kasan_pte_table(pmd_t pmd
)
76 return pmd_page(pmd
) == virt_to_page(lm_alias(kasan_early_shadow_pte
));
79 static inline bool kasan_early_shadow_page_entry(pte_t pte
)
81 return pte_page(pte
) == virt_to_page(lm_alias(kasan_early_shadow_page
));
84 static __init
void *early_alloc(size_t size
, int node
)
86 return memblock_alloc_try_nid(size
, size
, __pa(MAX_DMA_ADDRESS
),
87 MEMBLOCK_ALLOC_ACCESSIBLE
, node
);
90 static void __ref
zero_pte_populate(pmd_t
*pmd
, unsigned long addr
,
93 pte_t
*pte
= pte_offset_kernel(pmd
, addr
);
96 zero_pte
= pfn_pte(PFN_DOWN(__pa_symbol(kasan_early_shadow_page
)),
98 zero_pte
= pte_wrprotect(zero_pte
);
100 while (addr
+ PAGE_SIZE
<= end
) {
101 set_pte_at(&init_mm
, addr
, pte
, zero_pte
);
103 pte
= pte_offset_kernel(pmd
, addr
);
107 static int __ref
zero_pmd_populate(pud_t
*pud
, unsigned long addr
,
110 pmd_t
*pmd
= pmd_offset(pud
, addr
);
114 next
= pmd_addr_end(addr
, end
);
116 if (IS_ALIGNED(addr
, PMD_SIZE
) && end
- addr
>= PMD_SIZE
) {
117 pmd_populate_kernel(&init_mm
, pmd
,
118 lm_alias(kasan_early_shadow_pte
));
122 if (pmd_none(*pmd
)) {
125 if (slab_is_available())
126 p
= pte_alloc_one_kernel(&init_mm
, addr
);
128 p
= early_alloc(PAGE_SIZE
, NUMA_NO_NODE
);
132 pmd_populate_kernel(&init_mm
, pmd
, p
);
134 zero_pte_populate(pmd
, addr
, next
);
135 } while (pmd
++, addr
= next
, addr
!= end
);
140 static int __ref
zero_pud_populate(p4d_t
*p4d
, unsigned long addr
,
143 pud_t
*pud
= pud_offset(p4d
, addr
);
147 next
= pud_addr_end(addr
, end
);
148 if (IS_ALIGNED(addr
, PUD_SIZE
) && end
- addr
>= PUD_SIZE
) {
151 pud_populate(&init_mm
, pud
,
152 lm_alias(kasan_early_shadow_pmd
));
153 pmd
= pmd_offset(pud
, addr
);
154 pmd_populate_kernel(&init_mm
, pmd
,
155 lm_alias(kasan_early_shadow_pte
));
159 if (pud_none(*pud
)) {
162 if (slab_is_available()) {
163 p
= pmd_alloc(&init_mm
, pud
, addr
);
167 pud_populate(&init_mm
, pud
,
168 early_alloc(PAGE_SIZE
, NUMA_NO_NODE
));
171 zero_pmd_populate(pud
, addr
, next
);
172 } while (pud
++, addr
= next
, addr
!= end
);
177 static int __ref
zero_p4d_populate(pgd_t
*pgd
, unsigned long addr
,
180 p4d_t
*p4d
= p4d_offset(pgd
, addr
);
184 next
= p4d_addr_end(addr
, end
);
185 if (IS_ALIGNED(addr
, P4D_SIZE
) && end
- addr
>= P4D_SIZE
) {
189 p4d_populate(&init_mm
, p4d
,
190 lm_alias(kasan_early_shadow_pud
));
191 pud
= pud_offset(p4d
, addr
);
192 pud_populate(&init_mm
, pud
,
193 lm_alias(kasan_early_shadow_pmd
));
194 pmd
= pmd_offset(pud
, addr
);
195 pmd_populate_kernel(&init_mm
, pmd
,
196 lm_alias(kasan_early_shadow_pte
));
200 if (p4d_none(*p4d
)) {
203 if (slab_is_available()) {
204 p
= pud_alloc(&init_mm
, p4d
, addr
);
208 p4d_populate(&init_mm
, p4d
,
209 early_alloc(PAGE_SIZE
, NUMA_NO_NODE
));
212 zero_pud_populate(p4d
, addr
, next
);
213 } while (p4d
++, addr
= next
, addr
!= end
);
219 * kasan_populate_early_shadow - populate shadow memory region with
220 * kasan_early_shadow_page
221 * @shadow_start - start of the memory range to populate
222 * @shadow_end - end of the memory range to populate
224 int __ref
kasan_populate_early_shadow(const void *shadow_start
,
225 const void *shadow_end
)
227 unsigned long addr
= (unsigned long)shadow_start
;
228 unsigned long end
= (unsigned long)shadow_end
;
229 pgd_t
*pgd
= pgd_offset_k(addr
);
233 next
= pgd_addr_end(addr
, end
);
235 if (IS_ALIGNED(addr
, PGDIR_SIZE
) && end
- addr
>= PGDIR_SIZE
) {
241 * kasan_early_shadow_pud should be populated with pmds
243 * [pud,pmd]_populate*() below needed only for
244 * 3,2 - level page tables where we don't have
245 * puds,pmds, so pgd_populate(), pud_populate()
248 * The ifndef is required to avoid build breakage.
250 * With 5level-fixup.h, pgd_populate() is not nop and
251 * we reference kasan_early_shadow_p4d. It's not defined
252 * unless 5-level paging enabled.
254 * The ifndef can be dropped once all KASAN-enabled
255 * architectures will switch to pgtable-nop4d.h.
257 #ifndef __ARCH_HAS_5LEVEL_HACK
258 pgd_populate(&init_mm
, pgd
,
259 lm_alias(kasan_early_shadow_p4d
));
261 p4d
= p4d_offset(pgd
, addr
);
262 p4d_populate(&init_mm
, p4d
,
263 lm_alias(kasan_early_shadow_pud
));
264 pud
= pud_offset(p4d
, addr
);
265 pud_populate(&init_mm
, pud
,
266 lm_alias(kasan_early_shadow_pmd
));
267 pmd
= pmd_offset(pud
, addr
);
268 pmd_populate_kernel(&init_mm
, pmd
,
269 lm_alias(kasan_early_shadow_pte
));
273 if (pgd_none(*pgd
)) {
276 if (slab_is_available()) {
277 p
= p4d_alloc(&init_mm
, pgd
, addr
);
281 pgd_populate(&init_mm
, pgd
,
282 early_alloc(PAGE_SIZE
, NUMA_NO_NODE
));
285 zero_p4d_populate(pgd
, addr
, next
);
286 } while (pgd
++, addr
= next
, addr
!= end
);
291 static void kasan_free_pte(pte_t
*pte_start
, pmd_t
*pmd
)
296 for (i
= 0; i
< PTRS_PER_PTE
; i
++) {
302 pte_free_kernel(&init_mm
, (pte_t
*)page_to_virt(pmd_page(*pmd
)));
306 static void kasan_free_pmd(pmd_t
*pmd_start
, pud_t
*pud
)
311 for (i
= 0; i
< PTRS_PER_PMD
; i
++) {
317 pmd_free(&init_mm
, (pmd_t
*)page_to_virt(pud_page(*pud
)));
321 static void kasan_free_pud(pud_t
*pud_start
, p4d_t
*p4d
)
326 for (i
= 0; i
< PTRS_PER_PUD
; i
++) {
332 pud_free(&init_mm
, (pud_t
*)page_to_virt(p4d_page(*p4d
)));
336 static void kasan_free_p4d(p4d_t
*p4d_start
, pgd_t
*pgd
)
341 for (i
= 0; i
< PTRS_PER_P4D
; i
++) {
347 p4d_free(&init_mm
, (p4d_t
*)page_to_virt(pgd_page(*pgd
)));
351 static void kasan_remove_pte_table(pte_t
*pte
, unsigned long addr
,
356 for (; addr
< end
; addr
= next
, pte
++) {
357 next
= (addr
+ PAGE_SIZE
) & PAGE_MASK
;
361 if (!pte_present(*pte
))
364 if (WARN_ON(!kasan_early_shadow_page_entry(*pte
)))
366 pte_clear(&init_mm
, addr
, pte
);
370 static void kasan_remove_pmd_table(pmd_t
*pmd
, unsigned long addr
,
375 for (; addr
< end
; addr
= next
, pmd
++) {
378 next
= pmd_addr_end(addr
, end
);
380 if (!pmd_present(*pmd
))
383 if (kasan_pte_table(*pmd
)) {
384 if (IS_ALIGNED(addr
, PMD_SIZE
) &&
385 IS_ALIGNED(next
, PMD_SIZE
))
389 pte
= pte_offset_kernel(pmd
, addr
);
390 kasan_remove_pte_table(pte
, addr
, next
);
391 kasan_free_pte(pte_offset_kernel(pmd
, 0), pmd
);
395 static void kasan_remove_pud_table(pud_t
*pud
, unsigned long addr
,
400 for (; addr
< end
; addr
= next
, pud
++) {
401 pmd_t
*pmd
, *pmd_base
;
403 next
= pud_addr_end(addr
, end
);
405 if (!pud_present(*pud
))
408 if (kasan_pmd_table(*pud
)) {
409 if (IS_ALIGNED(addr
, PUD_SIZE
) &&
410 IS_ALIGNED(next
, PUD_SIZE
))
414 pmd
= pmd_offset(pud
, addr
);
415 pmd_base
= pmd_offset(pud
, 0);
416 kasan_remove_pmd_table(pmd
, addr
, next
);
417 kasan_free_pmd(pmd_base
, pud
);
421 static void kasan_remove_p4d_table(p4d_t
*p4d
, unsigned long addr
,
426 for (; addr
< end
; addr
= next
, p4d
++) {
429 next
= p4d_addr_end(addr
, end
);
431 if (!p4d_present(*p4d
))
434 if (kasan_pud_table(*p4d
)) {
435 if (IS_ALIGNED(addr
, P4D_SIZE
) &&
436 IS_ALIGNED(next
, P4D_SIZE
))
440 pud
= pud_offset(p4d
, addr
);
441 kasan_remove_pud_table(pud
, addr
, next
);
442 kasan_free_pud(pud_offset(p4d
, 0), p4d
);
446 void kasan_remove_zero_shadow(void *start
, unsigned long size
)
448 unsigned long addr
, end
, next
;
451 addr
= (unsigned long)kasan_mem_to_shadow(start
);
452 end
= addr
+ (size
>> KASAN_SHADOW_SCALE_SHIFT
);
454 if (WARN_ON((unsigned long)start
%
455 (KASAN_SHADOW_SCALE_SIZE
* PAGE_SIZE
)) ||
456 WARN_ON(size
% (KASAN_SHADOW_SCALE_SIZE
* PAGE_SIZE
)))
459 for (; addr
< end
; addr
= next
) {
462 next
= pgd_addr_end(addr
, end
);
464 pgd
= pgd_offset_k(addr
);
465 if (!pgd_present(*pgd
))
468 if (kasan_p4d_table(*pgd
)) {
469 if (IS_ALIGNED(addr
, PGDIR_SIZE
) &&
470 IS_ALIGNED(next
, PGDIR_SIZE
))
475 p4d
= p4d_offset(pgd
, addr
);
476 kasan_remove_p4d_table(p4d
, addr
, next
);
477 kasan_free_p4d(p4d_offset(pgd
, 0), pgd
);
481 int kasan_add_zero_shadow(void *start
, unsigned long size
)
484 void *shadow_start
, *shadow_end
;
486 shadow_start
= kasan_mem_to_shadow(start
);
487 shadow_end
= shadow_start
+ (size
>> KASAN_SHADOW_SCALE_SHIFT
);
489 if (WARN_ON((unsigned long)start
%
490 (KASAN_SHADOW_SCALE_SIZE
* PAGE_SIZE
)) ||
491 WARN_ON(size
% (KASAN_SHADOW_SCALE_SIZE
* PAGE_SIZE
)))
494 ret
= kasan_populate_early_shadow(shadow_start
, shadow_end
);
496 kasan_remove_zero_shadow(shadow_start
,
497 size
>> KASAN_SHADOW_SCALE_SHIFT
);