1 /* 2 * This file contains kasan initialization code for ARM64. 3 * 4 * Copyright (c) 2015 Samsung Electronics Co., Ltd. 5 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com> 6 * 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. 10 * 11 */ 12 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> 19 #include <linux/mm.h> 20 21 #include <asm/mmu_context.h> 22 #include <asm/kernel-pgtable.h> 23 #include <asm/page.h> 24 #include <asm/pgalloc.h> 25 #include <asm/pgtable.h> 26 #include <asm/sections.h> 27 #include <asm/tlbflush.h> 28 29 static pgd_t tmp_pg_dir[PTRS_PER_PGD] __initdata __aligned(PGD_SIZE); 30 31 /* 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. 36 */ 37 38 static phys_addr_t __init kasan_alloc_zeroed_page(int node) 39 { 40 void *p = memblock_alloc_try_nid(PAGE_SIZE, PAGE_SIZE, 41 __pa(MAX_DMA_ADDRESS), 42 MEMBLOCK_ALLOC_KASAN, node); 43 return __pa(p); 44 } 45 46 static phys_addr_t __init kasan_alloc_raw_page(int node) 47 { 48 void *p = memblock_alloc_try_nid_raw(PAGE_SIZE, PAGE_SIZE, 49 __pa(MAX_DMA_ADDRESS), 50 MEMBLOCK_ALLOC_KASAN, node); 51 return __pa(p); 52 } 53 54 static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node, 55 bool early) 56 { 57 if (pmd_none(READ_ONCE(*pmdp))) { 58 phys_addr_t pte_phys = early ? 59 __pa_symbol(kasan_early_shadow_pte) 60 : kasan_alloc_zeroed_page(node); 61 __pmd_populate(pmdp, pte_phys, PMD_TYPE_TABLE); 62 } 63 64 return early ? pte_offset_kimg(pmdp, addr) 65 : pte_offset_kernel(pmdp, addr); 66 } 67 68 static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node, 69 bool early) 70 { 71 if (pud_none(READ_ONCE(*pudp))) { 72 phys_addr_t pmd_phys = early ? 73 __pa_symbol(kasan_early_shadow_pmd) 74 : kasan_alloc_zeroed_page(node); 75 __pud_populate(pudp, pmd_phys, PMD_TYPE_TABLE); 76 } 77 78 return early ? pmd_offset_kimg(pudp, addr) : pmd_offset(pudp, addr); 79 } 80 81 static pud_t *__init kasan_pud_offset(pgd_t *pgdp, unsigned long addr, int node, 82 bool early) 83 { 84 if (pgd_none(READ_ONCE(*pgdp))) { 85 phys_addr_t pud_phys = early ? 86 __pa_symbol(kasan_early_shadow_pud) 87 : kasan_alloc_zeroed_page(node); 88 __pgd_populate(pgdp, pud_phys, PMD_TYPE_TABLE); 89 } 90 91 return early ? pud_offset_kimg(pgdp, addr) : pud_offset(pgdp, addr); 92 } 93 94 static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr, 95 unsigned long end, int node, bool early) 96 { 97 unsigned long next; 98 pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early); 99 100 do { 101 phys_addr_t page_phys = early ? 102 __pa_symbol(kasan_early_shadow_page) 103 : kasan_alloc_raw_page(node); 104 if (!early) 105 memset(__va(page_phys), KASAN_SHADOW_INIT, PAGE_SIZE); 106 next = addr + PAGE_SIZE; 107 set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL)); 108 } while (ptep++, addr = next, addr != end && pte_none(READ_ONCE(*ptep))); 109 } 110 111 static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr, 112 unsigned long end, int node, bool early) 113 { 114 unsigned long next; 115 pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early); 116 117 do { 118 next = pmd_addr_end(addr, end); 119 kasan_pte_populate(pmdp, addr, next, node, early); 120 } while (pmdp++, addr = next, addr != end && pmd_none(READ_ONCE(*pmdp))); 121 } 122 123 static void __init kasan_pud_populate(pgd_t *pgdp, unsigned long addr, 124 unsigned long end, int node, bool early) 125 { 126 unsigned long next; 127 pud_t *pudp = kasan_pud_offset(pgdp, addr, node, early); 128 129 do { 130 next = pud_addr_end(addr, end); 131 kasan_pmd_populate(pudp, addr, next, node, early); 132 } while (pudp++, addr = next, addr != end && pud_none(READ_ONCE(*pudp))); 133 } 134 135 static void __init kasan_pgd_populate(unsigned long addr, unsigned long end, 136 int node, bool early) 137 { 138 unsigned long next; 139 pgd_t *pgdp; 140 141 pgdp = pgd_offset_k(addr); 142 do { 143 next = pgd_addr_end(addr, end); 144 kasan_pud_populate(pgdp, addr, next, node, early); 145 } while (pgdp++, addr = next, addr != end); 146 } 147 148 /* The early shadow maps everything to a single page of zeroes */ 149 asmlinkage void __init kasan_early_init(void) 150 { 151 BUILD_BUG_ON(KASAN_SHADOW_OFFSET != 152 KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT))); 153 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE)); 154 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE)); 155 kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE, 156 true); 157 } 158 159 /* Set up full kasan mappings, ensuring that the mapped pages are zeroed */ 160 static void __init kasan_map_populate(unsigned long start, unsigned long end, 161 int node) 162 { 163 kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false); 164 } 165 166 /* 167 * Copy the current shadow region into a new pgdir. 168 */ 169 void __init kasan_copy_shadow(pgd_t *pgdir) 170 { 171 pgd_t *pgdp, *pgdp_new, *pgdp_end; 172 173 pgdp = pgd_offset_k(KASAN_SHADOW_START); 174 pgdp_end = pgd_offset_k(KASAN_SHADOW_END); 175 pgdp_new = pgd_offset_raw(pgdir, KASAN_SHADOW_START); 176 do { 177 set_pgd(pgdp_new, READ_ONCE(*pgdp)); 178 } while (pgdp++, pgdp_new++, pgdp != pgdp_end); 179 } 180 181 static void __init clear_pgds(unsigned long start, 182 unsigned long end) 183 { 184 /* 185 * Remove references to kasan page tables from 186 * swapper_pg_dir. pgd_clear() can't be used 187 * here because it's nop on 2,3-level pagetable setups 188 */ 189 for (; start < end; start += PGDIR_SIZE) 190 set_pgd(pgd_offset_k(start), __pgd(0)); 191 } 192 193 void __init kasan_init(void) 194 { 195 u64 kimg_shadow_start, kimg_shadow_end; 196 u64 mod_shadow_start, mod_shadow_end; 197 struct memblock_region *reg; 198 int i; 199 200 kimg_shadow_start = (u64)kasan_mem_to_shadow(_text) & PAGE_MASK; 201 kimg_shadow_end = PAGE_ALIGN((u64)kasan_mem_to_shadow(_end)); 202 203 mod_shadow_start = (u64)kasan_mem_to_shadow((void *)MODULES_VADDR); 204 mod_shadow_end = (u64)kasan_mem_to_shadow((void *)MODULES_END); 205 206 /* 207 * We are going to perform proper setup of shadow memory. 208 * At first we should unmap early shadow (clear_pgds() call below). 209 * However, instrumented code couldn't execute without shadow memory. 210 * tmp_pg_dir used to keep early shadow mapped until full shadow 211 * setup will be finished. 212 */ 213 memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(tmp_pg_dir)); 214 dsb(ishst); 215 cpu_replace_ttbr1(lm_alias(tmp_pg_dir)); 216 217 clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END); 218 219 kasan_map_populate(kimg_shadow_start, kimg_shadow_end, 220 early_pfn_to_nid(virt_to_pfn(lm_alias(_text)))); 221 222 kasan_populate_early_shadow((void *)KASAN_SHADOW_START, 223 (void *)mod_shadow_start); 224 kasan_populate_early_shadow((void *)kimg_shadow_end, 225 kasan_mem_to_shadow((void *)PAGE_OFFSET)); 226 227 if (kimg_shadow_start > mod_shadow_end) 228 kasan_populate_early_shadow((void *)mod_shadow_end, 229 (void *)kimg_shadow_start); 230 231 for_each_memblock(memory, reg) { 232 void *start = (void *)__phys_to_virt(reg->base); 233 void *end = (void *)__phys_to_virt(reg->base + reg->size); 234 235 if (start >= end) 236 break; 237 238 kasan_map_populate((unsigned long)kasan_mem_to_shadow(start), 239 (unsigned long)kasan_mem_to_shadow(end), 240 early_pfn_to_nid(virt_to_pfn(start))); 241 } 242 243 /* 244 * KAsan may reuse the contents of kasan_early_shadow_pte directly, 245 * so we should make sure that it maps the zero page read-only. 246 */ 247 for (i = 0; i < PTRS_PER_PTE; i++) 248 set_pte(&kasan_early_shadow_pte[i], 249 pfn_pte(sym_to_pfn(kasan_early_shadow_page), 250 PAGE_KERNEL_RO)); 251 252 memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE); 253 cpu_replace_ttbr1(lm_alias(swapper_pg_dir)); 254 255 kasan_init_tags(); 256 257 /* At this point kasan is fully initialized. Enable error messages */ 258 init_task.kasan_depth = 0; 259 pr_info("KernelAddressSanitizer initialized\n"); 260 } 261