1 // SPDX-License-Identifier: GPL-2.0 2 // Copyright (C) 2019 Andes Technology Corporation 3 4 #include <linux/pfn.h> 5 #include <linux/init_task.h> 6 #include <linux/kasan.h> 7 #include <linux/kernel.h> 8 #include <linux/memblock.h> 9 #include <linux/pgtable.h> 10 #include <asm/tlbflush.h> 11 #include <asm/fixmap.h> 12 #include <asm/pgalloc.h> 13 14 /* 15 * Kasan shadow region must lie at a fixed address across sv39, sv48 and sv57 16 * which is right before the kernel. 17 * 18 * For sv39, the region is aligned on PGDIR_SIZE so we only need to populate 19 * the page global directory with kasan_early_shadow_pmd. 20 * 21 * For sv48 and sv57, the region is not aligned on PGDIR_SIZE so the mapping 22 * must be divided as follows: 23 * - the first PGD entry, although incomplete, is populated with 24 * kasan_early_shadow_pud/p4d 25 * - the PGD entries in the middle are populated with kasan_early_shadow_pud/p4d 26 * - the last PGD entry is shared with the kernel mapping so populated at the 27 * lower levels pud/p4d 28 * 29 * In addition, when shallow populating a kasan region (for example vmalloc), 30 * this region may also not be aligned on PGDIR size, so we must go down to the 31 * pud level too. 32 */ 33 34 extern pgd_t early_pg_dir[PTRS_PER_PGD]; 35 36 static void __init kasan_populate_pte(pmd_t *pmd, unsigned long vaddr, unsigned long end) 37 { 38 phys_addr_t phys_addr; 39 pte_t *ptep, *base_pte; 40 41 if (pmd_none(*pmd)) 42 base_pte = memblock_alloc(PTRS_PER_PTE * sizeof(pte_t), PAGE_SIZE); 43 else 44 base_pte = (pte_t *)pmd_page_vaddr(*pmd); 45 46 ptep = base_pte + pte_index(vaddr); 47 48 do { 49 if (pte_none(*ptep)) { 50 phys_addr = memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE); 51 set_pte(ptep, pfn_pte(PFN_DOWN(phys_addr), PAGE_KERNEL)); 52 } 53 } while (ptep++, vaddr += PAGE_SIZE, vaddr != end); 54 55 set_pmd(pmd, pfn_pmd(PFN_DOWN(__pa(base_pte)), PAGE_TABLE)); 56 } 57 58 static void __init kasan_populate_pmd(pud_t *pud, unsigned long vaddr, unsigned long end) 59 { 60 phys_addr_t phys_addr; 61 pmd_t *pmdp, *base_pmd; 62 unsigned long next; 63 64 if (pud_none(*pud)) { 65 base_pmd = memblock_alloc(PTRS_PER_PMD * sizeof(pmd_t), PAGE_SIZE); 66 } else { 67 base_pmd = (pmd_t *)pud_pgtable(*pud); 68 if (base_pmd == lm_alias(kasan_early_shadow_pmd)) 69 base_pmd = memblock_alloc(PTRS_PER_PMD * sizeof(pmd_t), PAGE_SIZE); 70 } 71 72 pmdp = base_pmd + pmd_index(vaddr); 73 74 do { 75 next = pmd_addr_end(vaddr, end); 76 77 if (pmd_none(*pmdp) && IS_ALIGNED(vaddr, PMD_SIZE) && (next - vaddr) >= PMD_SIZE) { 78 phys_addr = memblock_phys_alloc(PMD_SIZE, PMD_SIZE); 79 if (phys_addr) { 80 set_pmd(pmdp, pfn_pmd(PFN_DOWN(phys_addr), PAGE_KERNEL)); 81 continue; 82 } 83 } 84 85 kasan_populate_pte(pmdp, vaddr, next); 86 } while (pmdp++, vaddr = next, vaddr != end); 87 88 /* 89 * Wait for the whole PGD to be populated before setting the PGD in 90 * the page table, otherwise, if we did set the PGD before populating 91 * it entirely, memblock could allocate a page at a physical address 92 * where KASAN is not populated yet and then we'd get a page fault. 93 */ 94 set_pud(pud, pfn_pud(PFN_DOWN(__pa(base_pmd)), PAGE_TABLE)); 95 } 96 97 static void __init kasan_populate_pud(pgd_t *pgd, 98 unsigned long vaddr, unsigned long end, 99 bool early) 100 { 101 phys_addr_t phys_addr; 102 pud_t *pudp, *base_pud; 103 unsigned long next; 104 105 if (early) { 106 /* 107 * We can't use pgd_page_vaddr here as it would return a linear 108 * mapping address but it is not mapped yet, but when populating 109 * early_pg_dir, we need the physical address and when populating 110 * swapper_pg_dir, we need the kernel virtual address so use 111 * pt_ops facility. 112 */ 113 base_pud = pt_ops.get_pud_virt(pfn_to_phys(_pgd_pfn(*pgd))); 114 } else { 115 base_pud = (pud_t *)pgd_page_vaddr(*pgd); 116 if (base_pud == lm_alias(kasan_early_shadow_pud)) { 117 base_pud = memblock_alloc(PTRS_PER_PUD * sizeof(pud_t), PAGE_SIZE); 118 memcpy(base_pud, (void *)kasan_early_shadow_pud, 119 sizeof(pud_t) * PTRS_PER_PUD); 120 } 121 } 122 123 pudp = base_pud + pud_index(vaddr); 124 125 do { 126 next = pud_addr_end(vaddr, end); 127 128 if (pud_none(*pudp) && IS_ALIGNED(vaddr, PUD_SIZE) && (next - vaddr) >= PUD_SIZE) { 129 if (early) { 130 phys_addr = __pa(((uintptr_t)kasan_early_shadow_pmd)); 131 set_pud(pudp, pfn_pud(PFN_DOWN(phys_addr), PAGE_TABLE)); 132 continue; 133 } else { 134 phys_addr = memblock_phys_alloc(PUD_SIZE, PUD_SIZE); 135 if (phys_addr) { 136 set_pud(pudp, pfn_pud(PFN_DOWN(phys_addr), PAGE_KERNEL)); 137 continue; 138 } 139 } 140 } 141 142 kasan_populate_pmd(pudp, vaddr, next); 143 } while (pudp++, vaddr = next, vaddr != end); 144 145 /* 146 * Wait for the whole PGD to be populated before setting the PGD in 147 * the page table, otherwise, if we did set the PGD before populating 148 * it entirely, memblock could allocate a page at a physical address 149 * where KASAN is not populated yet and then we'd get a page fault. 150 */ 151 if (!early) 152 set_pgd(pgd, pfn_pgd(PFN_DOWN(__pa(base_pud)), PAGE_TABLE)); 153 } 154 155 #define kasan_early_shadow_pgd_next (pgtable_l4_enabled ? \ 156 (uintptr_t)kasan_early_shadow_pud : \ 157 (uintptr_t)kasan_early_shadow_pmd) 158 #define kasan_populate_pgd_next(pgdp, vaddr, next, early) \ 159 (pgtable_l4_enabled ? \ 160 kasan_populate_pud(pgdp, vaddr, next, early) : \ 161 kasan_populate_pmd((pud_t *)pgdp, vaddr, next)) 162 163 static void __init kasan_populate_pgd(pgd_t *pgdp, 164 unsigned long vaddr, unsigned long end, 165 bool early) 166 { 167 phys_addr_t phys_addr; 168 unsigned long next; 169 170 do { 171 next = pgd_addr_end(vaddr, end); 172 173 if (IS_ALIGNED(vaddr, PGDIR_SIZE) && (next - vaddr) >= PGDIR_SIZE) { 174 if (early) { 175 phys_addr = __pa((uintptr_t)kasan_early_shadow_pgd_next); 176 set_pgd(pgdp, pfn_pgd(PFN_DOWN(phys_addr), PAGE_TABLE)); 177 continue; 178 } else if (pgd_page_vaddr(*pgdp) == 179 (unsigned long)lm_alias(kasan_early_shadow_pgd_next)) { 180 /* 181 * pgdp can't be none since kasan_early_init 182 * initialized all KASAN shadow region with 183 * kasan_early_shadow_pud: if this is still the 184 * case, that means we can try to allocate a 185 * hugepage as a replacement. 186 */ 187 phys_addr = memblock_phys_alloc(PGDIR_SIZE, PGDIR_SIZE); 188 if (phys_addr) { 189 set_pgd(pgdp, pfn_pgd(PFN_DOWN(phys_addr), PAGE_KERNEL)); 190 continue; 191 } 192 } 193 } 194 195 kasan_populate_pgd_next(pgdp, vaddr, next, early); 196 } while (pgdp++, vaddr = next, vaddr != end); 197 } 198 199 asmlinkage void __init kasan_early_init(void) 200 { 201 uintptr_t i; 202 203 BUILD_BUG_ON(KASAN_SHADOW_OFFSET != 204 KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT))); 205 206 for (i = 0; i < PTRS_PER_PTE; ++i) 207 set_pte(kasan_early_shadow_pte + i, 208 pfn_pte(virt_to_pfn(kasan_early_shadow_page), PAGE_KERNEL)); 209 210 for (i = 0; i < PTRS_PER_PMD; ++i) 211 set_pmd(kasan_early_shadow_pmd + i, 212 pfn_pmd(PFN_DOWN 213 (__pa((uintptr_t)kasan_early_shadow_pte)), 214 PAGE_TABLE)); 215 216 if (pgtable_l4_enabled) { 217 for (i = 0; i < PTRS_PER_PUD; ++i) 218 set_pud(kasan_early_shadow_pud + i, 219 pfn_pud(PFN_DOWN 220 (__pa(((uintptr_t)kasan_early_shadow_pmd))), 221 PAGE_TABLE)); 222 } 223 224 kasan_populate_pgd(early_pg_dir + pgd_index(KASAN_SHADOW_START), 225 KASAN_SHADOW_START, KASAN_SHADOW_END, true); 226 227 local_flush_tlb_all(); 228 } 229 230 void __init kasan_swapper_init(void) 231 { 232 kasan_populate_pgd(pgd_offset_k(KASAN_SHADOW_START), 233 KASAN_SHADOW_START, KASAN_SHADOW_END, true); 234 235 local_flush_tlb_all(); 236 } 237 238 static void __init kasan_populate(void *start, void *end) 239 { 240 unsigned long vaddr = (unsigned long)start & PAGE_MASK; 241 unsigned long vend = PAGE_ALIGN((unsigned long)end); 242 243 kasan_populate_pgd(pgd_offset_k(vaddr), vaddr, vend, false); 244 245 local_flush_tlb_all(); 246 memset(start, KASAN_SHADOW_INIT, end - start); 247 } 248 249 static void __init kasan_shallow_populate_pud(pgd_t *pgdp, 250 unsigned long vaddr, unsigned long end, 251 bool kasan_populate) 252 { 253 unsigned long next; 254 pud_t *pudp, *base_pud; 255 pmd_t *base_pmd; 256 bool is_kasan_pmd; 257 258 base_pud = (pud_t *)pgd_page_vaddr(*pgdp); 259 pudp = base_pud + pud_index(vaddr); 260 261 if (kasan_populate) 262 memcpy(base_pud, (void *)kasan_early_shadow_pgd_next, 263 sizeof(pud_t) * PTRS_PER_PUD); 264 265 do { 266 next = pud_addr_end(vaddr, end); 267 is_kasan_pmd = (pud_pgtable(*pudp) == lm_alias(kasan_early_shadow_pmd)); 268 269 if (is_kasan_pmd) { 270 base_pmd = memblock_alloc(PAGE_SIZE, PAGE_SIZE); 271 set_pud(pudp, pfn_pud(PFN_DOWN(__pa(base_pmd)), PAGE_TABLE)); 272 } 273 } while (pudp++, vaddr = next, vaddr != end); 274 } 275 276 static void __init kasan_shallow_populate_pgd(unsigned long vaddr, unsigned long end) 277 { 278 unsigned long next; 279 void *p; 280 pgd_t *pgd_k = pgd_offset_k(vaddr); 281 bool is_kasan_pgd_next; 282 283 do { 284 next = pgd_addr_end(vaddr, end); 285 is_kasan_pgd_next = (pgd_page_vaddr(*pgd_k) == 286 (unsigned long)lm_alias(kasan_early_shadow_pgd_next)); 287 288 if (is_kasan_pgd_next) { 289 p = memblock_alloc(PAGE_SIZE, PAGE_SIZE); 290 set_pgd(pgd_k, pfn_pgd(PFN_DOWN(__pa(p)), PAGE_TABLE)); 291 } 292 293 if (IS_ALIGNED(vaddr, PGDIR_SIZE) && (next - vaddr) >= PGDIR_SIZE) 294 continue; 295 296 kasan_shallow_populate_pud(pgd_k, vaddr, next, is_kasan_pgd_next); 297 } while (pgd_k++, vaddr = next, vaddr != end); 298 } 299 300 static void __init kasan_shallow_populate(void *start, void *end) 301 { 302 unsigned long vaddr = (unsigned long)start & PAGE_MASK; 303 unsigned long vend = PAGE_ALIGN((unsigned long)end); 304 305 kasan_shallow_populate_pgd(vaddr, vend); 306 local_flush_tlb_all(); 307 } 308 309 void __init kasan_init(void) 310 { 311 phys_addr_t p_start, p_end; 312 u64 i; 313 314 if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) 315 kasan_shallow_populate( 316 (void *)kasan_mem_to_shadow((void *)VMALLOC_START), 317 (void *)kasan_mem_to_shadow((void *)VMALLOC_END)); 318 319 /* Populate the linear mapping */ 320 for_each_mem_range(i, &p_start, &p_end) { 321 void *start = (void *)__va(p_start); 322 void *end = (void *)__va(p_end); 323 324 if (start >= end) 325 break; 326 327 kasan_populate(kasan_mem_to_shadow(start), kasan_mem_to_shadow(end)); 328 } 329 330 /* Populate kernel, BPF, modules mapping */ 331 kasan_populate(kasan_mem_to_shadow((const void *)MODULES_VADDR), 332 kasan_mem_to_shadow((const void *)MODULES_VADDR + SZ_2G)); 333 334 for (i = 0; i < PTRS_PER_PTE; i++) 335 set_pte(&kasan_early_shadow_pte[i], 336 mk_pte(virt_to_page(kasan_early_shadow_page), 337 __pgprot(_PAGE_PRESENT | _PAGE_READ | 338 _PAGE_ACCESSED))); 339 340 memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE); 341 init_task.kasan_depth = 0; 342 } 343