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/sched/task.h>
17 #include <linux/memblock.h>
18 #include <linux/start_kernel.h>
21 #include <asm/mmu_context.h>
22 #include <asm/kernel-pgtable.h>
24 #include <asm/pgalloc.h>
25 #include <asm/pgtable.h>
26 #include <asm/sections.h>
27 #include <asm/tlbflush.h>
29 static pgd_t tmp_pg_dir[PTRS_PER_PGD] __initdata __aligned(PGD_SIZE);
32 * The p*d_populate functions call virt_to_phys implicitly so they can't be used
33 * directly on kernel symbols (bm_p*d). All the early functions are called too
34 * early to use lm_alias so __p*d_populate functions must be used to populate
35 * with the physical address from __pa_symbol.
38 static phys_addr_t __init kasan_alloc_zeroed_page(int node)
40 void *p = memblock_alloc_try_nid(PAGE_SIZE, PAGE_SIZE,
41 __pa(MAX_DMA_ADDRESS),
42 MEMBLOCK_ALLOC_ACCESSIBLE, node);
46 static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node,
49 if (pmd_none(READ_ONCE(*pmdp))) {
50 phys_addr_t pte_phys = early ? __pa_symbol(kasan_zero_pte)
51 : kasan_alloc_zeroed_page(node);
52 __pmd_populate(pmdp, pte_phys, PMD_TYPE_TABLE);
55 return early ? pte_offset_kimg(pmdp, addr)
56 : pte_offset_kernel(pmdp, addr);
59 static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node,
62 if (pud_none(READ_ONCE(*pudp))) {
63 phys_addr_t pmd_phys = early ? __pa_symbol(kasan_zero_pmd)
64 : kasan_alloc_zeroed_page(node);
65 __pud_populate(pudp, pmd_phys, PMD_TYPE_TABLE);
68 return early ? pmd_offset_kimg(pudp, addr) : pmd_offset(pudp, addr);
71 static pud_t *__init kasan_pud_offset(pgd_t *pgdp, unsigned long addr, int node,
74 if (pgd_none(READ_ONCE(*pgdp))) {
75 phys_addr_t pud_phys = early ? __pa_symbol(kasan_zero_pud)
76 : kasan_alloc_zeroed_page(node);
77 __pgd_populate(pgdp, pud_phys, PMD_TYPE_TABLE);
80 return early ? pud_offset_kimg(pgdp, addr) : pud_offset(pgdp, addr);
83 static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
84 unsigned long end, int node, bool early)
87 pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early);
90 phys_addr_t page_phys = early ? __pa_symbol(kasan_zero_page)
91 : kasan_alloc_zeroed_page(node);
92 next = addr + PAGE_SIZE;
93 set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL));
94 } while (ptep++, addr = next, addr != end && pte_none(READ_ONCE(*ptep)));
97 static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr,
98 unsigned long end, int node, bool early)
101 pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early);
104 next = pmd_addr_end(addr, end);
105 kasan_pte_populate(pmdp, addr, next, node, early);
106 } while (pmdp++, addr = next, addr != end && pmd_none(READ_ONCE(*pmdp)));
109 static void __init kasan_pud_populate(pgd_t *pgdp, unsigned long addr,
110 unsigned long end, int node, bool early)
113 pud_t *pudp = kasan_pud_offset(pgdp, addr, node, early);
116 next = pud_addr_end(addr, end);
117 kasan_pmd_populate(pudp, addr, next, node, early);
118 } while (pudp++, addr = next, addr != end && pud_none(READ_ONCE(*pudp)));
121 static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
122 int node, bool early)
127 pgdp = pgd_offset_k(addr);
129 next = pgd_addr_end(addr, end);
130 kasan_pud_populate(pgdp, addr, next, node, early);
131 } while (pgdp++, addr = next, addr != end);
134 /* The early shadow maps everything to a single page of zeroes */
135 asmlinkage void __init kasan_early_init(void)
137 BUILD_BUG_ON(KASAN_SHADOW_OFFSET !=
138 KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT)));
139 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE));
140 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE));
141 kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE,
145 /* Set up full kasan mappings, ensuring that the mapped pages are zeroed */
146 static void __init kasan_map_populate(unsigned long start, unsigned long end,
149 kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false);
153 * Copy the current shadow region into a new pgdir.
155 void __init kasan_copy_shadow(pgd_t *pgdir)
157 pgd_t *pgdp, *pgdp_new, *pgdp_end;
159 pgdp = pgd_offset_k(KASAN_SHADOW_START);
160 pgdp_end = pgd_offset_k(KASAN_SHADOW_END);
161 pgdp_new = pgd_offset_raw(pgdir, KASAN_SHADOW_START);
163 set_pgd(pgdp_new, READ_ONCE(*pgdp));
164 } while (pgdp++, pgdp_new++, pgdp != pgdp_end);
167 static void __init clear_pgds(unsigned long start,
171 * Remove references to kasan page tables from
172 * swapper_pg_dir. pgd_clear() can't be used
173 * here because it's nop on 2,3-level pagetable setups
175 for (; start < end; start += PGDIR_SIZE)
176 set_pgd(pgd_offset_k(start), __pgd(0));
179 void __init kasan_init(void)
181 u64 kimg_shadow_start, kimg_shadow_end;
182 u64 mod_shadow_start, mod_shadow_end;
183 struct memblock_region *reg;
186 kimg_shadow_start = (u64)kasan_mem_to_shadow(_text) & PAGE_MASK;
187 kimg_shadow_end = PAGE_ALIGN((u64)kasan_mem_to_shadow(_end));
189 mod_shadow_start = (u64)kasan_mem_to_shadow((void *)MODULES_VADDR);
190 mod_shadow_end = (u64)kasan_mem_to_shadow((void *)MODULES_END);
193 * We are going to perform proper setup of shadow memory.
194 * At first we should unmap early shadow (clear_pgds() call below).
195 * However, instrumented code couldn't execute without shadow memory.
196 * tmp_pg_dir used to keep early shadow mapped until full shadow
197 * setup will be finished.
199 memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(tmp_pg_dir));
201 cpu_replace_ttbr1(lm_alias(tmp_pg_dir));
203 clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
205 kasan_map_populate(kimg_shadow_start, kimg_shadow_end,
206 early_pfn_to_nid(virt_to_pfn(lm_alias(_text))));
208 kasan_populate_zero_shadow((void *)KASAN_SHADOW_START,
209 (void *)mod_shadow_start);
210 kasan_populate_zero_shadow((void *)kimg_shadow_end,
211 kasan_mem_to_shadow((void *)PAGE_OFFSET));
213 if (kimg_shadow_start > mod_shadow_end)
214 kasan_populate_zero_shadow((void *)mod_shadow_end,
215 (void *)kimg_shadow_start);
217 for_each_memblock(memory, reg) {
218 void *start = (void *)__phys_to_virt(reg->base);
219 void *end = (void *)__phys_to_virt(reg->base + reg->size);
224 kasan_map_populate((unsigned long)kasan_mem_to_shadow(start),
225 (unsigned long)kasan_mem_to_shadow(end),
226 early_pfn_to_nid(virt_to_pfn(start)));
230 * KAsan may reuse the contents of kasan_zero_pte directly, so we
231 * should make sure that it maps the zero page read-only.
233 for (i = 0; i < PTRS_PER_PTE; i++)
234 set_pte(&kasan_zero_pte[i],
235 pfn_pte(sym_to_pfn(kasan_zero_page), PAGE_KERNEL_RO));
237 memset(kasan_zero_page, 0, PAGE_SIZE);
238 cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
240 /* At this point kasan is fully initialized. Enable error messages */
241 init_task.kasan_depth = 0;
242 pr_info("KernelAddressSanitizer initialized\n");