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 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) 25 26 static pgd_t tmp_pg_dir[PTRS_PER_PGD] __initdata __aligned(PGD_SIZE); 27 28 /* 29 * The p*d_populate functions call virt_to_phys implicitly so they can't be used 30 * directly on kernel symbols (bm_p*d). All the early functions are called too 31 * early to use lm_alias so __p*d_populate functions must be used to populate 32 * with the physical address from __pa_symbol. 33 */ 34 35 static phys_addr_t __init kasan_alloc_zeroed_page(int node) 36 { 37 void *p = memblock_alloc_try_nid(PAGE_SIZE, PAGE_SIZE, 38 __pa(MAX_DMA_ADDRESS), 39 MEMBLOCK_ALLOC_NOLEAKTRACE, node); 40 if (!p) 41 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n", 42 __func__, PAGE_SIZE, PAGE_SIZE, node, 43 __pa(MAX_DMA_ADDRESS)); 44 45 return __pa(p); 46 } 47 48 static phys_addr_t __init kasan_alloc_raw_page(int node) 49 { 50 void *p = memblock_alloc_try_nid_raw(PAGE_SIZE, PAGE_SIZE, 51 __pa(MAX_DMA_ADDRESS), 52 MEMBLOCK_ALLOC_NOLEAKTRACE, 53 node); 54 if (!p) 55 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n", 56 __func__, PAGE_SIZE, PAGE_SIZE, node, 57 __pa(MAX_DMA_ADDRESS)); 58 59 return __pa(p); 60 } 61 62 static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node, 63 bool early) 64 { 65 if (pmd_none(READ_ONCE(*pmdp))) { 66 phys_addr_t pte_phys = early ? 67 __pa_symbol(kasan_early_shadow_pte) 68 : kasan_alloc_zeroed_page(node); 69 __pmd_populate(pmdp, pte_phys, PMD_TYPE_TABLE); 70 } 71 72 return early ? pte_offset_kimg(pmdp, addr) 73 : pte_offset_kernel(pmdp, addr); 74 } 75 76 static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node, 77 bool early) 78 { 79 if (pud_none(READ_ONCE(*pudp))) { 80 phys_addr_t pmd_phys = early ? 81 __pa_symbol(kasan_early_shadow_pmd) 82 : kasan_alloc_zeroed_page(node); 83 __pud_populate(pudp, pmd_phys, PUD_TYPE_TABLE); 84 } 85 86 return early ? pmd_offset_kimg(pudp, addr) : pmd_offset(pudp, addr); 87 } 88 89 static pud_t *__init kasan_pud_offset(p4d_t *p4dp, unsigned long addr, int node, 90 bool early) 91 { 92 if (p4d_none(READ_ONCE(*p4dp))) { 93 phys_addr_t pud_phys = early ? 94 __pa_symbol(kasan_early_shadow_pud) 95 : kasan_alloc_zeroed_page(node); 96 __p4d_populate(p4dp, pud_phys, P4D_TYPE_TABLE); 97 } 98 99 return early ? pud_offset_kimg(p4dp, addr) : pud_offset(p4dp, addr); 100 } 101 102 static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr, 103 unsigned long end, int node, bool early) 104 { 105 unsigned long next; 106 pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early); 107 108 do { 109 phys_addr_t page_phys = early ? 110 __pa_symbol(kasan_early_shadow_page) 111 : kasan_alloc_raw_page(node); 112 if (!early) 113 memset(__va(page_phys), KASAN_SHADOW_INIT, PAGE_SIZE); 114 next = addr + PAGE_SIZE; 115 set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL)); 116 } while (ptep++, addr = next, addr != end && pte_none(READ_ONCE(*ptep))); 117 } 118 119 static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr, 120 unsigned long end, int node, bool early) 121 { 122 unsigned long next; 123 pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early); 124 125 do { 126 next = pmd_addr_end(addr, end); 127 kasan_pte_populate(pmdp, addr, next, node, early); 128 } while (pmdp++, addr = next, addr != end && pmd_none(READ_ONCE(*pmdp))); 129 } 130 131 static void __init kasan_pud_populate(p4d_t *p4dp, unsigned long addr, 132 unsigned long end, int node, bool early) 133 { 134 unsigned long next; 135 pud_t *pudp = kasan_pud_offset(p4dp, addr, node, early); 136 137 do { 138 next = pud_addr_end(addr, end); 139 kasan_pmd_populate(pudp, addr, next, node, early); 140 } while (pudp++, addr = next, addr != end && pud_none(READ_ONCE(*pudp))); 141 } 142 143 static void __init kasan_p4d_populate(pgd_t *pgdp, unsigned long addr, 144 unsigned long end, int node, bool early) 145 { 146 unsigned long next; 147 p4d_t *p4dp = p4d_offset(pgdp, addr); 148 149 do { 150 next = p4d_addr_end(addr, end); 151 kasan_pud_populate(p4dp, addr, next, node, early); 152 } while (p4dp++, addr = next, addr != end); 153 } 154 155 static void __init kasan_pgd_populate(unsigned long addr, unsigned long end, 156 int node, bool early) 157 { 158 unsigned long next; 159 pgd_t *pgdp; 160 161 pgdp = pgd_offset_k(addr); 162 do { 163 next = pgd_addr_end(addr, end); 164 kasan_p4d_populate(pgdp, addr, next, node, early); 165 } while (pgdp++, addr = next, addr != end); 166 } 167 168 /* The early shadow maps everything to a single page of zeroes */ 169 asmlinkage void __init kasan_early_init(void) 170 { 171 BUILD_BUG_ON(KASAN_SHADOW_OFFSET != 172 KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT))); 173 /* 174 * We cannot check the actual value of KASAN_SHADOW_START during build, 175 * as it depends on vabits_actual. As a best-effort approach, check 176 * potential values calculated based on VA_BITS and VA_BITS_MIN. 177 */ 178 BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS), PGDIR_SIZE)); 179 BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS_MIN), PGDIR_SIZE)); 180 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE)); 181 kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE, 182 true); 183 } 184 185 /* Set up full kasan mappings, ensuring that the mapped pages are zeroed */ 186 static void __init kasan_map_populate(unsigned long start, unsigned long end, 187 int node) 188 { 189 kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false); 190 } 191 192 /* 193 * Copy the current shadow region into a new pgdir. 194 */ 195 void __init kasan_copy_shadow(pgd_t *pgdir) 196 { 197 pgd_t *pgdp, *pgdp_new, *pgdp_end; 198 199 pgdp = pgd_offset_k(KASAN_SHADOW_START); 200 pgdp_end = pgd_offset_k(KASAN_SHADOW_END); 201 pgdp_new = pgd_offset_pgd(pgdir, KASAN_SHADOW_START); 202 do { 203 set_pgd(pgdp_new, READ_ONCE(*pgdp)); 204 } while (pgdp++, pgdp_new++, pgdp != pgdp_end); 205 } 206 207 static void __init clear_pgds(unsigned long start, 208 unsigned long end) 209 { 210 /* 211 * Remove references to kasan page tables from 212 * swapper_pg_dir. pgd_clear() can't be used 213 * here because it's nop on 2,3-level pagetable setups 214 */ 215 for (; start < end; start += PGDIR_SIZE) 216 set_pgd(pgd_offset_k(start), __pgd(0)); 217 } 218 219 static void __init kasan_init_shadow(void) 220 { 221 u64 kimg_shadow_start, kimg_shadow_end; 222 u64 mod_shadow_start; 223 u64 vmalloc_shadow_end; 224 phys_addr_t pa_start, pa_end; 225 u64 i; 226 227 kimg_shadow_start = (u64)kasan_mem_to_shadow(KERNEL_START) & PAGE_MASK; 228 kimg_shadow_end = PAGE_ALIGN((u64)kasan_mem_to_shadow(KERNEL_END)); 229 230 mod_shadow_start = (u64)kasan_mem_to_shadow((void *)MODULES_VADDR); 231 232 vmalloc_shadow_end = (u64)kasan_mem_to_shadow((void *)VMALLOC_END); 233 234 /* 235 * We are going to perform proper setup of shadow memory. 236 * At first we should unmap early shadow (clear_pgds() call below). 237 * However, instrumented code couldn't execute without shadow memory. 238 * tmp_pg_dir used to keep early shadow mapped until full shadow 239 * setup will be finished. 240 */ 241 memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(tmp_pg_dir)); 242 dsb(ishst); 243 cpu_replace_ttbr1(lm_alias(tmp_pg_dir), idmap_pg_dir); 244 245 clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END); 246 247 kasan_map_populate(kimg_shadow_start, kimg_shadow_end, 248 early_pfn_to_nid(virt_to_pfn(lm_alias(KERNEL_START)))); 249 250 kasan_populate_early_shadow(kasan_mem_to_shadow((void *)PAGE_END), 251 (void *)mod_shadow_start); 252 253 BUILD_BUG_ON(VMALLOC_START != MODULES_END); 254 kasan_populate_early_shadow((void *)vmalloc_shadow_end, 255 (void *)KASAN_SHADOW_END); 256 257 for_each_mem_range(i, &pa_start, &pa_end) { 258 void *start = (void *)__phys_to_virt(pa_start); 259 void *end = (void *)__phys_to_virt(pa_end); 260 261 if (start >= end) 262 break; 263 264 kasan_map_populate((unsigned long)kasan_mem_to_shadow(start), 265 (unsigned long)kasan_mem_to_shadow(end), 266 early_pfn_to_nid(virt_to_pfn(start))); 267 } 268 269 /* 270 * KAsan may reuse the contents of kasan_early_shadow_pte directly, 271 * so we should make sure that it maps the zero page read-only. 272 */ 273 for (i = 0; i < PTRS_PER_PTE; i++) 274 set_pte(&kasan_early_shadow_pte[i], 275 pfn_pte(sym_to_pfn(kasan_early_shadow_page), 276 PAGE_KERNEL_RO)); 277 278 memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE); 279 cpu_replace_ttbr1(lm_alias(swapper_pg_dir), idmap_pg_dir); 280 } 281 282 static void __init kasan_init_depth(void) 283 { 284 init_task.kasan_depth = 0; 285 } 286 287 #ifdef CONFIG_KASAN_VMALLOC 288 void __init kasan_populate_early_vm_area_shadow(void *start, unsigned long size) 289 { 290 unsigned long shadow_start, shadow_end; 291 292 if (!is_vmalloc_or_module_addr(start)) 293 return; 294 295 shadow_start = (unsigned long)kasan_mem_to_shadow(start); 296 shadow_start = ALIGN_DOWN(shadow_start, PAGE_SIZE); 297 shadow_end = (unsigned long)kasan_mem_to_shadow(start + size); 298 shadow_end = ALIGN(shadow_end, PAGE_SIZE); 299 kasan_map_populate(shadow_start, shadow_end, NUMA_NO_NODE); 300 } 301 #endif 302 303 void __init kasan_init(void) 304 { 305 kasan_init_shadow(); 306 kasan_init_depth(); 307 #if defined(CONFIG_KASAN_GENERIC) 308 /* 309 * Generic KASAN is now fully initialized. 310 * Software and Hardware Tag-Based modes still require 311 * kasan_init_sw_tags() and kasan_init_hw_tags() correspondingly. 312 */ 313 pr_info("KernelAddressSanitizer initialized (generic)\n"); 314 #endif 315 } 316 317 #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */ 318