2 * This file contains kasan initialization code for ARM64.
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 #define pr_fmt(fmt) "kasan: " fmt
14 #include <linux/kasan.h>
15 #include <linux/kernel.h>
16 #include <linux/memblock.h>
17 #include <linux/start_kernel.h>
20 #include <asm/mmu_context.h>
21 #include <asm/kernel-pgtable.h>
23 #include <asm/pgalloc.h>
24 #include <asm/pgtable.h>
25 #include <asm/sections.h>
26 #include <asm/tlbflush.h>
28 static pgd_t tmp_pg_dir[PTRS_PER_PGD] __initdata __aligned(PGD_SIZE);
31 * The p*d_populate functions call virt_to_phys implicitly so they can't be used
32 * directly on kernel symbols (bm_p*d). All the early functions are called too
33 * early to use lm_alias so __p*d_populate functions must be used to populate
34 * with the physical address from __pa_symbol.
37 static void __init kasan_early_pte_populate(pmd_t *pmd, unsigned long addr,
44 __pmd_populate(pmd, __pa_symbol(kasan_zero_pte), PMD_TYPE_TABLE);
46 pte = pte_offset_kimg(pmd, addr);
48 next = addr + PAGE_SIZE;
49 set_pte(pte, pfn_pte(sym_to_pfn(kasan_zero_page),
51 } while (pte++, addr = next, addr != end && pte_none(*pte));
54 static void __init kasan_early_pmd_populate(pud_t *pud,
62 __pud_populate(pud, __pa_symbol(kasan_zero_pmd), PMD_TYPE_TABLE);
64 pmd = pmd_offset_kimg(pud, addr);
66 next = pmd_addr_end(addr, end);
67 kasan_early_pte_populate(pmd, addr, next);
68 } while (pmd++, addr = next, addr != end && pmd_none(*pmd));
71 static void __init kasan_early_pud_populate(pgd_t *pgd,
79 __pgd_populate(pgd, __pa_symbol(kasan_zero_pud), PUD_TYPE_TABLE);
81 pud = pud_offset_kimg(pgd, addr);
83 next = pud_addr_end(addr, end);
84 kasan_early_pmd_populate(pud, addr, next);
85 } while (pud++, addr = next, addr != end && pud_none(*pud));
88 static void __init kasan_map_early_shadow(void)
90 unsigned long addr = KASAN_SHADOW_START;
91 unsigned long end = KASAN_SHADOW_END;
95 pgd = pgd_offset_k(addr);
97 next = pgd_addr_end(addr, end);
98 kasan_early_pud_populate(pgd, addr, next);
99 } while (pgd++, addr = next, addr != end);
102 asmlinkage void __init kasan_early_init(void)
104 BUILD_BUG_ON(KASAN_SHADOW_OFFSET != KASAN_SHADOW_END - (1UL << 61));
105 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE));
106 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE));
107 kasan_map_early_shadow();
111 * Copy the current shadow region into a new pgdir.
113 void __init kasan_copy_shadow(pgd_t *pgdir)
115 pgd_t *pgd, *pgd_new, *pgd_end;
117 pgd = pgd_offset_k(KASAN_SHADOW_START);
118 pgd_end = pgd_offset_k(KASAN_SHADOW_END);
119 pgd_new = pgd_offset_raw(pgdir, KASAN_SHADOW_START);
121 set_pgd(pgd_new, *pgd);
122 } while (pgd++, pgd_new++, pgd != pgd_end);
125 static void __init clear_pgds(unsigned long start,
129 * Remove references to kasan page tables from
130 * swapper_pg_dir. pgd_clear() can't be used
131 * here because it's nop on 2,3-level pagetable setups
133 for (; start < end; start += PGDIR_SIZE)
134 set_pgd(pgd_offset_k(start), __pgd(0));
137 void __init kasan_init(void)
139 u64 kimg_shadow_start, kimg_shadow_end;
140 u64 mod_shadow_start, mod_shadow_end;
141 struct memblock_region *reg;
144 kimg_shadow_start = (u64)kasan_mem_to_shadow(_text);
145 kimg_shadow_end = (u64)kasan_mem_to_shadow(_end);
147 mod_shadow_start = (u64)kasan_mem_to_shadow((void *)MODULES_VADDR);
148 mod_shadow_end = (u64)kasan_mem_to_shadow((void *)MODULES_END);
151 * We are going to perform proper setup of shadow memory.
152 * At first we should unmap early shadow (clear_pgds() call bellow).
153 * However, instrumented code couldn't execute without shadow memory.
154 * tmp_pg_dir used to keep early shadow mapped until full shadow
155 * setup will be finished.
157 memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(tmp_pg_dir));
159 cpu_replace_ttbr1(lm_alias(tmp_pg_dir));
161 clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
163 vmemmap_populate(kimg_shadow_start, kimg_shadow_end,
164 pfn_to_nid(virt_to_pfn(_text)));
167 * vmemmap_populate() has populated the shadow region that covers the
168 * kernel image with SWAPPER_BLOCK_SIZE mappings, so we have to round
169 * the start and end addresses to SWAPPER_BLOCK_SIZE as well, to prevent
170 * kasan_populate_zero_shadow() from replacing the page table entries
171 * (PMD or PTE) at the edges of the shadow region for the kernel
174 kimg_shadow_start = round_down(kimg_shadow_start, SWAPPER_BLOCK_SIZE);
175 kimg_shadow_end = round_up(kimg_shadow_end, SWAPPER_BLOCK_SIZE);
177 kasan_populate_zero_shadow((void *)KASAN_SHADOW_START,
178 (void *)mod_shadow_start);
179 kasan_populate_zero_shadow((void *)kimg_shadow_end,
180 kasan_mem_to_shadow((void *)PAGE_OFFSET));
182 if (kimg_shadow_start > mod_shadow_end)
183 kasan_populate_zero_shadow((void *)mod_shadow_end,
184 (void *)kimg_shadow_start);
186 for_each_memblock(memory, reg) {
187 void *start = (void *)__phys_to_virt(reg->base);
188 void *end = (void *)__phys_to_virt(reg->base + reg->size);
194 * end + 1 here is intentional. We check several shadow bytes in
195 * advance to slightly speed up fastpath. In some rare cases
196 * we could cross boundary of mapped shadow, so we just map
199 vmemmap_populate((unsigned long)kasan_mem_to_shadow(start),
200 (unsigned long)kasan_mem_to_shadow(end) + 1,
201 pfn_to_nid(virt_to_pfn(start)));
205 * KAsan may reuse the contents of kasan_zero_pte directly, so we
206 * should make sure that it maps the zero page read-only.
208 for (i = 0; i < PTRS_PER_PTE; i++)
209 set_pte(&kasan_zero_pte[i],
210 pfn_pte(sym_to_pfn(kasan_zero_page), PAGE_KERNEL_RO));
212 memset(kasan_zero_page, 0, PAGE_SIZE);
213 cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
215 /* At this point kasan is fully initialized. Enable error messages */
216 init_task.kasan_depth = 0;
217 pr_info("KernelAddressSanitizer initialized\n");