1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * This file contains kasan initialization code for ARM64. 4 * 5 * Copyright (c) 2015 Samsung Electronics Co., Ltd. 6 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com> 7 */ 8 9 #define pr_fmt(fmt) "kasan: " fmt 10 #include <linux/kasan.h> 11 #include <linux/kernel.h> 12 #include <linux/sched/task.h> 13 #include <linux/memblock.h> 14 #include <linux/start_kernel.h> 15 #include <linux/mm.h> 16 17 #include <asm/mmu_context.h> 18 #include <asm/kernel-pgtable.h> 19 #include <asm/page.h> 20 #include <asm/pgalloc.h> 21 #include <asm/sections.h> 22 #include <asm/tlbflush.h> 23 24 static pgd_t tmp_pg_dir[PTRS_PER_PGD] __initdata __aligned(PGD_SIZE); 25 26 /* 27 * The p*d_populate functions call virt_to_phys implicitly so they can't be used 28 * directly on kernel symbols (bm_p*d). All the early functions are called too 29 * early to use lm_alias so __p*d_populate functions must be used to populate 30 * with the physical address from __pa_symbol. 31 */ 32 33 static phys_addr_t __init kasan_alloc_zeroed_page(int node) 34 { 35 void *p = memblock_alloc_try_nid(PAGE_SIZE, PAGE_SIZE, 36 __pa(MAX_DMA_ADDRESS), 37 MEMBLOCK_ALLOC_KASAN, node); 38 if (!p) 39 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n", 40 __func__, PAGE_SIZE, PAGE_SIZE, node, 41 __pa(MAX_DMA_ADDRESS)); 42 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 if (!p) 52 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n", 53 __func__, PAGE_SIZE, PAGE_SIZE, node, 54 __pa(MAX_DMA_ADDRESS)); 55 56 return __pa(p); 57 } 58 59 static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node, 60 bool early) 61 { 62 if (pmd_none(READ_ONCE(*pmdp))) { 63 phys_addr_t pte_phys = early ? 64 __pa_symbol(kasan_early_shadow_pte) 65 : kasan_alloc_zeroed_page(node); 66 __pmd_populate(pmdp, pte_phys, PMD_TYPE_TABLE); 67 } 68 69 return early ? pte_offset_kimg(pmdp, addr) 70 : pte_offset_kernel(pmdp, addr); 71 } 72 73 static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node, 74 bool early) 75 { 76 if (pud_none(READ_ONCE(*pudp))) { 77 phys_addr_t pmd_phys = early ? 78 __pa_symbol(kasan_early_shadow_pmd) 79 : kasan_alloc_zeroed_page(node); 80 __pud_populate(pudp, pmd_phys, PMD_TYPE_TABLE); 81 } 82 83 return early ? pmd_offset_kimg(pudp, addr) : pmd_offset(pudp, addr); 84 } 85 86 static pud_t *__init kasan_pud_offset(p4d_t *p4dp, unsigned long addr, int node, 87 bool early) 88 { 89 if (p4d_none(READ_ONCE(*p4dp))) { 90 phys_addr_t pud_phys = early ? 91 __pa_symbol(kasan_early_shadow_pud) 92 : kasan_alloc_zeroed_page(node); 93 __p4d_populate(p4dp, pud_phys, PMD_TYPE_TABLE); 94 } 95 96 return early ? pud_offset_kimg(p4dp, addr) : pud_offset(p4dp, addr); 97 } 98 99 static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr, 100 unsigned long end, int node, bool early) 101 { 102 unsigned long next; 103 pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early); 104 105 do { 106 phys_addr_t page_phys = early ? 107 __pa_symbol(kasan_early_shadow_page) 108 : kasan_alloc_raw_page(node); 109 if (!early) 110 memset(__va(page_phys), KASAN_SHADOW_INIT, PAGE_SIZE); 111 next = addr + PAGE_SIZE; 112 set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL)); 113 } while (ptep++, addr = next, addr != end && pte_none(READ_ONCE(*ptep))); 114 } 115 116 static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr, 117 unsigned long end, int node, bool early) 118 { 119 unsigned long next; 120 pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early); 121 122 do { 123 next = pmd_addr_end(addr, end); 124 kasan_pte_populate(pmdp, addr, next, node, early); 125 } while (pmdp++, addr = next, addr != end && pmd_none(READ_ONCE(*pmdp))); 126 } 127 128 static void __init kasan_pud_populate(p4d_t *p4dp, unsigned long addr, 129 unsigned long end, int node, bool early) 130 { 131 unsigned long next; 132 pud_t *pudp = kasan_pud_offset(p4dp, addr, node, early); 133 134 do { 135 next = pud_addr_end(addr, end); 136 kasan_pmd_populate(pudp, addr, next, node, early); 137 } while (pudp++, addr = next, addr != end && pud_none(READ_ONCE(*pudp))); 138 } 139 140 static void __init kasan_p4d_populate(pgd_t *pgdp, unsigned long addr, 141 unsigned long end, int node, bool early) 142 { 143 unsigned long next; 144 p4d_t *p4dp = p4d_offset(pgdp, addr); 145 146 do { 147 next = p4d_addr_end(addr, end); 148 kasan_pud_populate(p4dp, addr, next, node, early); 149 } while (p4dp++, addr = next, addr != end); 150 } 151 152 static void __init kasan_pgd_populate(unsigned long addr, unsigned long end, 153 int node, bool early) 154 { 155 unsigned long next; 156 pgd_t *pgdp; 157 158 pgdp = pgd_offset_k(addr); 159 do { 160 next = pgd_addr_end(addr, end); 161 kasan_p4d_populate(pgdp, addr, next, node, early); 162 } while (pgdp++, addr = next, addr != end); 163 } 164 165 /* The early shadow maps everything to a single page of zeroes */ 166 asmlinkage void __init kasan_early_init(void) 167 { 168 BUILD_BUG_ON(KASAN_SHADOW_OFFSET != 169 KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT))); 170 BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS), PGDIR_SIZE)); 171 BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS_MIN), PGDIR_SIZE)); 172 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE)); 173 kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE, 174 true); 175 } 176 177 /* Set up full kasan mappings, ensuring that the mapped pages are zeroed */ 178 static void __init kasan_map_populate(unsigned long start, unsigned long end, 179 int node) 180 { 181 kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false); 182 } 183 184 /* 185 * Copy the current shadow region into a new pgdir. 186 */ 187 void __init kasan_copy_shadow(pgd_t *pgdir) 188 { 189 pgd_t *pgdp, *pgdp_new, *pgdp_end; 190 191 pgdp = pgd_offset_k(KASAN_SHADOW_START); 192 pgdp_end = pgd_offset_k(KASAN_SHADOW_END); 193 pgdp_new = pgd_offset_pgd(pgdir, KASAN_SHADOW_START); 194 do { 195 set_pgd(pgdp_new, READ_ONCE(*pgdp)); 196 } while (pgdp++, pgdp_new++, pgdp != pgdp_end); 197 } 198 199 static void __init clear_pgds(unsigned long start, 200 unsigned long end) 201 { 202 /* 203 * Remove references to kasan page tables from 204 * swapper_pg_dir. pgd_clear() can't be used 205 * here because it's nop on 2,3-level pagetable setups 206 */ 207 for (; start < end; start += PGDIR_SIZE) 208 set_pgd(pgd_offset_k(start), __pgd(0)); 209 } 210 211 void __init kasan_init(void) 212 { 213 u64 kimg_shadow_start, kimg_shadow_end; 214 u64 mod_shadow_start, mod_shadow_end; 215 struct memblock_region *reg; 216 int i; 217 218 kimg_shadow_start = (u64)kasan_mem_to_shadow(_text) & PAGE_MASK; 219 kimg_shadow_end = PAGE_ALIGN((u64)kasan_mem_to_shadow(_end)); 220 221 mod_shadow_start = (u64)kasan_mem_to_shadow((void *)MODULES_VADDR); 222 mod_shadow_end = (u64)kasan_mem_to_shadow((void *)MODULES_END); 223 224 /* 225 * We are going to perform proper setup of shadow memory. 226 * At first we should unmap early shadow (clear_pgds() call below). 227 * However, instrumented code couldn't execute without shadow memory. 228 * tmp_pg_dir used to keep early shadow mapped until full shadow 229 * setup will be finished. 230 */ 231 memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(tmp_pg_dir)); 232 dsb(ishst); 233 cpu_replace_ttbr1(lm_alias(tmp_pg_dir)); 234 235 clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END); 236 237 kasan_map_populate(kimg_shadow_start, kimg_shadow_end, 238 early_pfn_to_nid(virt_to_pfn(lm_alias(_text)))); 239 240 kasan_populate_early_shadow(kasan_mem_to_shadow((void *)PAGE_END), 241 (void *)mod_shadow_start); 242 kasan_populate_early_shadow((void *)kimg_shadow_end, 243 (void *)KASAN_SHADOW_END); 244 245 if (kimg_shadow_start > mod_shadow_end) 246 kasan_populate_early_shadow((void *)mod_shadow_end, 247 (void *)kimg_shadow_start); 248 249 for_each_memblock(memory, reg) { 250 void *start = (void *)__phys_to_virt(reg->base); 251 void *end = (void *)__phys_to_virt(reg->base + reg->size); 252 253 if (start >= end) 254 break; 255 256 kasan_map_populate((unsigned long)kasan_mem_to_shadow(start), 257 (unsigned long)kasan_mem_to_shadow(end), 258 early_pfn_to_nid(virt_to_pfn(start))); 259 } 260 261 /* 262 * KAsan may reuse the contents of kasan_early_shadow_pte directly, 263 * so we should make sure that it maps the zero page read-only. 264 */ 265 for (i = 0; i < PTRS_PER_PTE; i++) 266 set_pte(&kasan_early_shadow_pte[i], 267 pfn_pte(sym_to_pfn(kasan_early_shadow_page), 268 PAGE_KERNEL_RO)); 269 270 memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE); 271 cpu_replace_ttbr1(lm_alias(swapper_pg_dir)); 272 273 /* At this point kasan is fully initialized. Enable error messages */ 274 init_task.kasan_depth = 0; 275 pr_info("KernelAddressSanitizer initialized\n"); 276 } 277