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/pgtable.h> 22 #include <asm/sections.h> 23 #include <asm/tlbflush.h> 24 25 static pgd_t tmp_pg_dir[PTRS_PER_PGD] __initdata __aligned(PGD_SIZE); 26 27 /* 28 * The p*d_populate functions call virt_to_phys implicitly so they can't be used 29 * directly on kernel symbols (bm_p*d). All the early functions are called too 30 * early to use lm_alias so __p*d_populate functions must be used to populate 31 * with the physical address from __pa_symbol. 32 */ 33 34 static phys_addr_t __init kasan_alloc_zeroed_page(int node) 35 { 36 void *p = memblock_alloc_try_nid(PAGE_SIZE, PAGE_SIZE, 37 __pa(MAX_DMA_ADDRESS), 38 MEMBLOCK_ALLOC_KASAN, node); 39 if (!p) 40 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n", 41 __func__, PAGE_SIZE, PAGE_SIZE, node, 42 __pa(MAX_DMA_ADDRESS)); 43 44 return __pa(p); 45 } 46 47 static phys_addr_t __init kasan_alloc_raw_page(int node) 48 { 49 void *p = memblock_alloc_try_nid_raw(PAGE_SIZE, PAGE_SIZE, 50 __pa(MAX_DMA_ADDRESS), 51 MEMBLOCK_ALLOC_KASAN, node); 52 if (!p) 53 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n", 54 __func__, PAGE_SIZE, PAGE_SIZE, node, 55 __pa(MAX_DMA_ADDRESS)); 56 57 return __pa(p); 58 } 59 60 static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node, 61 bool early) 62 { 63 if (pmd_none(READ_ONCE(*pmdp))) { 64 phys_addr_t pte_phys = early ? 65 __pa_symbol(kasan_early_shadow_pte) 66 : kasan_alloc_zeroed_page(node); 67 __pmd_populate(pmdp, pte_phys, PMD_TYPE_TABLE); 68 } 69 70 return early ? pte_offset_kimg(pmdp, addr) 71 : pte_offset_kernel(pmdp, addr); 72 } 73 74 static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node, 75 bool early) 76 { 77 if (pud_none(READ_ONCE(*pudp))) { 78 phys_addr_t pmd_phys = early ? 79 __pa_symbol(kasan_early_shadow_pmd) 80 : kasan_alloc_zeroed_page(node); 81 __pud_populate(pudp, pmd_phys, PMD_TYPE_TABLE); 82 } 83 84 return early ? pmd_offset_kimg(pudp, addr) : pmd_offset(pudp, addr); 85 } 86 87 static pud_t *__init kasan_pud_offset(pgd_t *pgdp, unsigned long addr, int node, 88 bool early) 89 { 90 if (pgd_none(READ_ONCE(*pgdp))) { 91 phys_addr_t pud_phys = early ? 92 __pa_symbol(kasan_early_shadow_pud) 93 : kasan_alloc_zeroed_page(node); 94 __pgd_populate(pgdp, pud_phys, PMD_TYPE_TABLE); 95 } 96 97 return early ? pud_offset_kimg(pgdp, addr) : pud_offset(pgdp, addr); 98 } 99 100 static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr, 101 unsigned long end, int node, bool early) 102 { 103 unsigned long next; 104 pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early); 105 106 do { 107 phys_addr_t page_phys = early ? 108 __pa_symbol(kasan_early_shadow_page) 109 : kasan_alloc_raw_page(node); 110 if (!early) 111 memset(__va(page_phys), KASAN_SHADOW_INIT, PAGE_SIZE); 112 next = addr + PAGE_SIZE; 113 set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL)); 114 } while (ptep++, addr = next, addr != end && pte_none(READ_ONCE(*ptep))); 115 } 116 117 static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr, 118 unsigned long end, int node, bool early) 119 { 120 unsigned long next; 121 pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early); 122 123 do { 124 next = pmd_addr_end(addr, end); 125 kasan_pte_populate(pmdp, addr, next, node, early); 126 } while (pmdp++, addr = next, addr != end && pmd_none(READ_ONCE(*pmdp))); 127 } 128 129 static void __init kasan_pud_populate(pgd_t *pgdp, unsigned long addr, 130 unsigned long end, int node, bool early) 131 { 132 unsigned long next; 133 pud_t *pudp = kasan_pud_offset(pgdp, addr, node, early); 134 135 do { 136 next = pud_addr_end(addr, end); 137 kasan_pmd_populate(pudp, addr, next, node, early); 138 } while (pudp++, addr = next, addr != end && pud_none(READ_ONCE(*pudp))); 139 } 140 141 static void __init kasan_pgd_populate(unsigned long addr, unsigned long end, 142 int node, bool early) 143 { 144 unsigned long next; 145 pgd_t *pgdp; 146 147 pgdp = pgd_offset_k(addr); 148 do { 149 next = pgd_addr_end(addr, end); 150 kasan_pud_populate(pgdp, addr, next, node, early); 151 } while (pgdp++, addr = next, addr != end); 152 } 153 154 /* The early shadow maps everything to a single page of zeroes */ 155 asmlinkage void __init kasan_early_init(void) 156 { 157 BUILD_BUG_ON(KASAN_SHADOW_OFFSET != 158 KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT))); 159 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE)); 160 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE)); 161 kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE, 162 true); 163 } 164 165 /* Set up full kasan mappings, ensuring that the mapped pages are zeroed */ 166 static void __init kasan_map_populate(unsigned long start, unsigned long end, 167 int node) 168 { 169 kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false); 170 } 171 172 /* 173 * Copy the current shadow region into a new pgdir. 174 */ 175 void __init kasan_copy_shadow(pgd_t *pgdir) 176 { 177 pgd_t *pgdp, *pgdp_new, *pgdp_end; 178 179 pgdp = pgd_offset_k(KASAN_SHADOW_START); 180 pgdp_end = pgd_offset_k(KASAN_SHADOW_END); 181 pgdp_new = pgd_offset_raw(pgdir, KASAN_SHADOW_START); 182 do { 183 set_pgd(pgdp_new, READ_ONCE(*pgdp)); 184 } while (pgdp++, pgdp_new++, pgdp != pgdp_end); 185 } 186 187 static void __init clear_pgds(unsigned long start, 188 unsigned long end) 189 { 190 /* 191 * Remove references to kasan page tables from 192 * swapper_pg_dir. pgd_clear() can't be used 193 * here because it's nop on 2,3-level pagetable setups 194 */ 195 for (; start < end; start += PGDIR_SIZE) 196 set_pgd(pgd_offset_k(start), __pgd(0)); 197 } 198 199 void __init kasan_init(void) 200 { 201 u64 kimg_shadow_start, kimg_shadow_end; 202 u64 mod_shadow_start, mod_shadow_end; 203 struct memblock_region *reg; 204 int i; 205 206 kimg_shadow_start = (u64)kasan_mem_to_shadow(_text) & PAGE_MASK; 207 kimg_shadow_end = PAGE_ALIGN((u64)kasan_mem_to_shadow(_end)); 208 209 mod_shadow_start = (u64)kasan_mem_to_shadow((void *)MODULES_VADDR); 210 mod_shadow_end = (u64)kasan_mem_to_shadow((void *)MODULES_END); 211 212 /* 213 * We are going to perform proper setup of shadow memory. 214 * At first we should unmap early shadow (clear_pgds() call below). 215 * However, instrumented code couldn't execute without shadow memory. 216 * tmp_pg_dir used to keep early shadow mapped until full shadow 217 * setup will be finished. 218 */ 219 memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(tmp_pg_dir)); 220 dsb(ishst); 221 cpu_replace_ttbr1(lm_alias(tmp_pg_dir)); 222 223 clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END); 224 225 kasan_map_populate(kimg_shadow_start, kimg_shadow_end, 226 early_pfn_to_nid(virt_to_pfn(lm_alias(_text)))); 227 228 kasan_populate_early_shadow((void *)KASAN_SHADOW_START, 229 (void *)mod_shadow_start); 230 kasan_populate_early_shadow((void *)kimg_shadow_end, 231 kasan_mem_to_shadow((void *)PAGE_OFFSET)); 232 233 if (kimg_shadow_start > mod_shadow_end) 234 kasan_populate_early_shadow((void *)mod_shadow_end, 235 (void *)kimg_shadow_start); 236 237 for_each_memblock(memory, reg) { 238 void *start = (void *)__phys_to_virt(reg->base); 239 void *end = (void *)__phys_to_virt(reg->base + reg->size); 240 241 if (start >= end) 242 break; 243 244 kasan_map_populate((unsigned long)kasan_mem_to_shadow(start), 245 (unsigned long)kasan_mem_to_shadow(end), 246 early_pfn_to_nid(virt_to_pfn(start))); 247 } 248 249 /* 250 * KAsan may reuse the contents of kasan_early_shadow_pte directly, 251 * so we should make sure that it maps the zero page read-only. 252 */ 253 for (i = 0; i < PTRS_PER_PTE; i++) 254 set_pte(&kasan_early_shadow_pte[i], 255 pfn_pte(sym_to_pfn(kasan_early_shadow_page), 256 PAGE_KERNEL_RO)); 257 258 memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE); 259 cpu_replace_ttbr1(lm_alias(swapper_pg_dir)); 260 261 /* At this point kasan is fully initialized. Enable error messages */ 262 init_task.kasan_depth = 0; 263 pr_info("KernelAddressSanitizer initialized\n"); 264 } 265