2 * This file contains some kasan initialization code.
4 * Copyright (c) 2015 Samsung Electronics Co., Ltd.
5 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
13 #include <linux/bootmem.h>
14 #include <linux/init.h>
15 #include <linux/kasan.h>
16 #include <linux/kernel.h>
17 #include <linux/memblock.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_zero_page[PAGE_SIZE] __page_aligned_bss;
36 #if CONFIG_PGTABLE_LEVELS > 4
37 p4d_t kasan_zero_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_zero_p4d));
43 static inline bool kasan_p4d_table(pgd_t pgd)
48 #if CONFIG_PGTABLE_LEVELS > 3
49 pud_t kasan_zero_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_zero_pud));
55 static inline bool kasan_pud_table(p4d_t p4d)
60 #if CONFIG_PGTABLE_LEVELS > 2
61 pmd_t kasan_zero_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_zero_pmd));
67 static inline bool kasan_pmd_table(pud_t pud)
72 pte_t kasan_zero_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_zero_pte));
79 static inline bool kasan_zero_page_entry(pte_t pte)
81 return pte_page(pte) == virt_to_page(lm_alias(kasan_zero_page));
84 static __init void *early_alloc(size_t size, int node)
86 return memblock_virt_alloc_try_nid(size, size, __pa(MAX_DMA_ADDRESS),
87 BOOTMEM_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_zero_page)), PAGE_KERNEL);
97 zero_pte = pte_wrprotect(zero_pte);
99 while (addr + PAGE_SIZE <= end) {
100 set_pte_at(&init_mm, addr, pte, zero_pte);
102 pte = pte_offset_kernel(pmd, addr);
106 static int __ref zero_pmd_populate(pud_t *pud, unsigned long addr,
109 pmd_t *pmd = pmd_offset(pud, addr);
113 next = pmd_addr_end(addr, end);
115 if (IS_ALIGNED(addr, PMD_SIZE) && end - addr >= PMD_SIZE) {
116 pmd_populate_kernel(&init_mm, pmd, lm_alias(kasan_zero_pte));
120 if (pmd_none(*pmd)) {
123 if (slab_is_available())
124 p = pte_alloc_one_kernel(&init_mm, addr);
126 p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
130 pmd_populate_kernel(&init_mm, pmd, p);
132 zero_pte_populate(pmd, addr, next);
133 } while (pmd++, addr = next, addr != end);
138 static int __ref zero_pud_populate(p4d_t *p4d, unsigned long addr,
141 pud_t *pud = pud_offset(p4d, addr);
145 next = pud_addr_end(addr, end);
146 if (IS_ALIGNED(addr, PUD_SIZE) && end - addr >= PUD_SIZE) {
149 pud_populate(&init_mm, pud, lm_alias(kasan_zero_pmd));
150 pmd = pmd_offset(pud, addr);
151 pmd_populate_kernel(&init_mm, pmd, lm_alias(kasan_zero_pte));
155 if (pud_none(*pud)) {
158 if (slab_is_available()) {
159 p = pmd_alloc(&init_mm, pud, addr);
163 pud_populate(&init_mm, pud,
164 early_alloc(PAGE_SIZE, NUMA_NO_NODE));
167 zero_pmd_populate(pud, addr, next);
168 } while (pud++, addr = next, addr != end);
173 static int __ref zero_p4d_populate(pgd_t *pgd, unsigned long addr,
176 p4d_t *p4d = p4d_offset(pgd, addr);
180 next = p4d_addr_end(addr, end);
181 if (IS_ALIGNED(addr, P4D_SIZE) && end - addr >= P4D_SIZE) {
185 p4d_populate(&init_mm, p4d, lm_alias(kasan_zero_pud));
186 pud = pud_offset(p4d, addr);
187 pud_populate(&init_mm, pud, lm_alias(kasan_zero_pmd));
188 pmd = pmd_offset(pud, addr);
189 pmd_populate_kernel(&init_mm, pmd,
190 lm_alias(kasan_zero_pte));
194 if (p4d_none(*p4d)) {
197 if (slab_is_available()) {
198 p = pud_alloc(&init_mm, p4d, addr);
202 p4d_populate(&init_mm, p4d,
203 early_alloc(PAGE_SIZE, NUMA_NO_NODE));
206 zero_pud_populate(p4d, addr, next);
207 } while (p4d++, addr = next, addr != end);
213 * kasan_populate_zero_shadow - populate shadow memory region with
215 * @shadow_start - start of the memory range to populate
216 * @shadow_end - end of the memory range to populate
218 int __ref kasan_populate_zero_shadow(const void *shadow_start,
219 const void *shadow_end)
221 unsigned long addr = (unsigned long)shadow_start;
222 unsigned long end = (unsigned long)shadow_end;
223 pgd_t *pgd = pgd_offset_k(addr);
227 next = pgd_addr_end(addr, end);
229 if (IS_ALIGNED(addr, PGDIR_SIZE) && end - addr >= PGDIR_SIZE) {
235 * kasan_zero_pud should be populated with pmds
237 * [pud,pmd]_populate*() below needed only for
238 * 3,2 - level page tables where we don't have
239 * puds,pmds, so pgd_populate(), pud_populate()
242 * The ifndef is required to avoid build breakage.
244 * With 5level-fixup.h, pgd_populate() is not nop and
245 * we reference kasan_zero_p4d. It's not defined
246 * unless 5-level paging enabled.
248 * The ifndef can be dropped once all KASAN-enabled
249 * architectures will switch to pgtable-nop4d.h.
251 #ifndef __ARCH_HAS_5LEVEL_HACK
252 pgd_populate(&init_mm, pgd, lm_alias(kasan_zero_p4d));
254 p4d = p4d_offset(pgd, addr);
255 p4d_populate(&init_mm, p4d, lm_alias(kasan_zero_pud));
256 pud = pud_offset(p4d, addr);
257 pud_populate(&init_mm, pud, lm_alias(kasan_zero_pmd));
258 pmd = pmd_offset(pud, addr);
259 pmd_populate_kernel(&init_mm, pmd, lm_alias(kasan_zero_pte));
263 if (pgd_none(*pgd)) {
266 if (slab_is_available()) {
267 p = p4d_alloc(&init_mm, pgd, addr);
271 pgd_populate(&init_mm, pgd,
272 early_alloc(PAGE_SIZE, NUMA_NO_NODE));
275 zero_p4d_populate(pgd, addr, next);
276 } while (pgd++, addr = next, addr != end);
281 static void kasan_free_pte(pte_t *pte_start, pmd_t *pmd)
286 for (i = 0; i < PTRS_PER_PTE; i++) {
292 pte_free_kernel(&init_mm, (pte_t *)page_to_virt(pmd_page(*pmd)));
296 static void kasan_free_pmd(pmd_t *pmd_start, pud_t *pud)
301 for (i = 0; i < PTRS_PER_PMD; i++) {
307 pmd_free(&init_mm, (pmd_t *)page_to_virt(pud_page(*pud)));
311 static void kasan_free_pud(pud_t *pud_start, p4d_t *p4d)
316 for (i = 0; i < PTRS_PER_PUD; i++) {
322 pud_free(&init_mm, (pud_t *)page_to_virt(p4d_page(*p4d)));
326 static void kasan_free_p4d(p4d_t *p4d_start, pgd_t *pgd)
331 for (i = 0; i < PTRS_PER_P4D; i++) {
337 p4d_free(&init_mm, (p4d_t *)page_to_virt(pgd_page(*pgd)));
341 static void kasan_remove_pte_table(pte_t *pte, unsigned long addr,
346 for (; addr < end; addr = next, pte++) {
347 next = (addr + PAGE_SIZE) & PAGE_MASK;
351 if (!pte_present(*pte))
354 if (WARN_ON(!kasan_zero_page_entry(*pte)))
356 pte_clear(&init_mm, addr, pte);
360 static void kasan_remove_pmd_table(pmd_t *pmd, unsigned long addr,
365 for (; addr < end; addr = next, pmd++) {
368 next = pmd_addr_end(addr, end);
370 if (!pmd_present(*pmd))
373 if (kasan_pte_table(*pmd)) {
374 if (IS_ALIGNED(addr, PMD_SIZE) &&
375 IS_ALIGNED(next, PMD_SIZE)) {
380 pte = pte_offset_kernel(pmd, addr);
381 kasan_remove_pte_table(pte, addr, next);
382 kasan_free_pte(pte_offset_kernel(pmd, 0), pmd);
386 static void kasan_remove_pud_table(pud_t *pud, unsigned long addr,
391 for (; addr < end; addr = next, pud++) {
392 pmd_t *pmd, *pmd_base;
394 next = pud_addr_end(addr, end);
396 if (!pud_present(*pud))
399 if (kasan_pmd_table(*pud)) {
400 if (IS_ALIGNED(addr, PUD_SIZE) &&
401 IS_ALIGNED(next, PUD_SIZE)) {
406 pmd = pmd_offset(pud, addr);
407 pmd_base = pmd_offset(pud, 0);
408 kasan_remove_pmd_table(pmd, addr, next);
409 kasan_free_pmd(pmd_base, pud);
413 static void kasan_remove_p4d_table(p4d_t *p4d, unsigned long addr,
418 for (; addr < end; addr = next, p4d++) {
421 next = p4d_addr_end(addr, end);
423 if (!p4d_present(*p4d))
426 if (kasan_pud_table(*p4d)) {
427 if (IS_ALIGNED(addr, P4D_SIZE) &&
428 IS_ALIGNED(next, P4D_SIZE)) {
433 pud = pud_offset(p4d, addr);
434 kasan_remove_pud_table(pud, addr, next);
435 kasan_free_pud(pud_offset(p4d, 0), p4d);
439 void kasan_remove_zero_shadow(void *start, unsigned long size)
441 unsigned long addr, end, next;
444 addr = (unsigned long)kasan_mem_to_shadow(start);
445 end = addr + (size >> KASAN_SHADOW_SCALE_SHIFT);
447 if (WARN_ON((unsigned long)start %
448 (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)) ||
449 WARN_ON(size % (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)))
452 for (; addr < end; addr = next) {
455 next = pgd_addr_end(addr, end);
457 pgd = pgd_offset_k(addr);
458 if (!pgd_present(*pgd))
461 if (kasan_p4d_table(*pgd)) {
462 if (IS_ALIGNED(addr, PGDIR_SIZE) &&
463 IS_ALIGNED(next, PGDIR_SIZE)) {
469 p4d = p4d_offset(pgd, addr);
470 kasan_remove_p4d_table(p4d, addr, next);
471 kasan_free_p4d(p4d_offset(pgd, 0), pgd);
475 int kasan_add_zero_shadow(void *start, unsigned long size)
478 void *shadow_start, *shadow_end;
480 shadow_start = kasan_mem_to_shadow(start);
481 shadow_end = shadow_start + (size >> KASAN_SHADOW_SCALE_SHIFT);
483 if (WARN_ON((unsigned long)start %
484 (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)) ||
485 WARN_ON(size % (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)))
488 ret = kasan_populate_zero_shadow(shadow_start, shadow_end);
490 kasan_remove_zero_shadow(start, size);