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 if (!p) 44 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n", 45 __func__, PAGE_SIZE, PAGE_SIZE, node, 46 __pa(MAX_DMA_ADDRESS)); 47 48 return __pa(p); 49 } 50 51 static phys_addr_t __init kasan_alloc_raw_page(int node) 52 { 53 void *p = memblock_alloc_try_nid_raw(PAGE_SIZE, PAGE_SIZE, 54 __pa(MAX_DMA_ADDRESS), 55 MEMBLOCK_ALLOC_KASAN, node); 56 if (!p) 57 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n", 58 __func__, PAGE_SIZE, PAGE_SIZE, node, 59 __pa(MAX_DMA_ADDRESS)); 60 61 return __pa(p); 62 } 63 64 static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node, 65 bool early) 66 { 67 if (pmd_none(READ_ONCE(*pmdp))) { 68 phys_addr_t pte_phys = early ? 69 __pa_symbol(kasan_early_shadow_pte) 70 : kasan_alloc_zeroed_page(node); 71 __pmd_populate(pmdp, pte_phys, PMD_TYPE_TABLE); 72 } 73 74 return early ? pte_offset_kimg(pmdp, addr) 75 : pte_offset_kernel(pmdp, addr); 76 } 77 78 static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node, 79 bool early) 80 { 81 if (pud_none(READ_ONCE(*pudp))) { 82 phys_addr_t pmd_phys = early ? 83 __pa_symbol(kasan_early_shadow_pmd) 84 : kasan_alloc_zeroed_page(node); 85 __pud_populate(pudp, pmd_phys, PMD_TYPE_TABLE); 86 } 87 88 return early ? pmd_offset_kimg(pudp, addr) : pmd_offset(pudp, addr); 89 } 90 91 static pud_t *__init kasan_pud_offset(pgd_t *pgdp, unsigned long addr, int node, 92 bool early) 93 { 94 if (pgd_none(READ_ONCE(*pgdp))) { 95 phys_addr_t pud_phys = early ? 96 __pa_symbol(kasan_early_shadow_pud) 97 : kasan_alloc_zeroed_page(node); 98 __pgd_populate(pgdp, pud_phys, PMD_TYPE_TABLE); 99 } 100 101 return early ? pud_offset_kimg(pgdp, addr) : pud_offset(pgdp, addr); 102 } 103 104 static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr, 105 unsigned long end, int node, bool early) 106 { 107 unsigned long next; 108 pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early); 109 110 do { 111 phys_addr_t page_phys = early ? 112 __pa_symbol(kasan_early_shadow_page) 113 : kasan_alloc_raw_page(node); 114 if (!early) 115 memset(__va(page_phys), KASAN_SHADOW_INIT, PAGE_SIZE); 116 next = addr + PAGE_SIZE; 117 set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL)); 118 } while (ptep++, addr = next, addr != end && pte_none(READ_ONCE(*ptep))); 119 } 120 121 static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr, 122 unsigned long end, int node, bool early) 123 { 124 unsigned long next; 125 pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early); 126 127 do { 128 next = pmd_addr_end(addr, end); 129 kasan_pte_populate(pmdp, addr, next, node, early); 130 } while (pmdp++, addr = next, addr != end && pmd_none(READ_ONCE(*pmdp))); 131 } 132 133 static void __init kasan_pud_populate(pgd_t *pgdp, unsigned long addr, 134 unsigned long end, int node, bool early) 135 { 136 unsigned long next; 137 pud_t *pudp = kasan_pud_offset(pgdp, addr, node, early); 138 139 do { 140 next = pud_addr_end(addr, end); 141 kasan_pmd_populate(pudp, addr, next, node, early); 142 } while (pudp++, addr = next, addr != end && pud_none(READ_ONCE(*pudp))); 143 } 144 145 static void __init kasan_pgd_populate(unsigned long addr, unsigned long end, 146 int node, bool early) 147 { 148 unsigned long next; 149 pgd_t *pgdp; 150 151 pgdp = pgd_offset_k(addr); 152 do { 153 next = pgd_addr_end(addr, end); 154 kasan_pud_populate(pgdp, addr, next, node, early); 155 } while (pgdp++, addr = next, addr != end); 156 } 157 158 /* The early shadow maps everything to a single page of zeroes */ 159 asmlinkage void __init kasan_early_init(void) 160 { 161 BUILD_BUG_ON(KASAN_SHADOW_OFFSET != 162 KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT))); 163 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE)); 164 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE)); 165 kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE, 166 true); 167 } 168 169 /* Set up full kasan mappings, ensuring that the mapped pages are zeroed */ 170 static void __init kasan_map_populate(unsigned long start, unsigned long end, 171 int node) 172 { 173 kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false); 174 } 175 176 /* 177 * Copy the current shadow region into a new pgdir. 178 */ 179 void __init kasan_copy_shadow(pgd_t *pgdir) 180 { 181 pgd_t *pgdp, *pgdp_new, *pgdp_end; 182 183 pgdp = pgd_offset_k(KASAN_SHADOW_START); 184 pgdp_end = pgd_offset_k(KASAN_SHADOW_END); 185 pgdp_new = pgd_offset_raw(pgdir, KASAN_SHADOW_START); 186 do { 187 set_pgd(pgdp_new, READ_ONCE(*pgdp)); 188 } while (pgdp++, pgdp_new++, pgdp != pgdp_end); 189 } 190 191 static void __init clear_pgds(unsigned long start, 192 unsigned long end) 193 { 194 /* 195 * Remove references to kasan page tables from 196 * swapper_pg_dir. pgd_clear() can't be used 197 * here because it's nop on 2,3-level pagetable setups 198 */ 199 for (; start < end; start += PGDIR_SIZE) 200 set_pgd(pgd_offset_k(start), __pgd(0)); 201 } 202 203 void __init kasan_init(void) 204 { 205 u64 kimg_shadow_start, kimg_shadow_end; 206 u64 mod_shadow_start, mod_shadow_end; 207 struct memblock_region *reg; 208 int i; 209 210 kimg_shadow_start = (u64)kasan_mem_to_shadow(_text) & PAGE_MASK; 211 kimg_shadow_end = PAGE_ALIGN((u64)kasan_mem_to_shadow(_end)); 212 213 mod_shadow_start = (u64)kasan_mem_to_shadow((void *)MODULES_VADDR); 214 mod_shadow_end = (u64)kasan_mem_to_shadow((void *)MODULES_END); 215 216 /* 217 * We are going to perform proper setup of shadow memory. 218 * At first we should unmap early shadow (clear_pgds() call below). 219 * However, instrumented code couldn't execute without shadow memory. 220 * tmp_pg_dir used to keep early shadow mapped until full shadow 221 * setup will be finished. 222 */ 223 memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(tmp_pg_dir)); 224 dsb(ishst); 225 cpu_replace_ttbr1(lm_alias(tmp_pg_dir)); 226 227 clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END); 228 229 kasan_map_populate(kimg_shadow_start, kimg_shadow_end, 230 early_pfn_to_nid(virt_to_pfn(lm_alias(_text)))); 231 232 kasan_populate_early_shadow((void *)KASAN_SHADOW_START, 233 (void *)mod_shadow_start); 234 kasan_populate_early_shadow((void *)kimg_shadow_end, 235 kasan_mem_to_shadow((void *)PAGE_OFFSET)); 236 237 if (kimg_shadow_start > mod_shadow_end) 238 kasan_populate_early_shadow((void *)mod_shadow_end, 239 (void *)kimg_shadow_start); 240 241 for_each_memblock(memory, reg) { 242 void *start = (void *)__phys_to_virt(reg->base); 243 void *end = (void *)__phys_to_virt(reg->base + reg->size); 244 245 if (start >= end) 246 break; 247 248 kasan_map_populate((unsigned long)kasan_mem_to_shadow(start), 249 (unsigned long)kasan_mem_to_shadow(end), 250 early_pfn_to_nid(virt_to_pfn(start))); 251 } 252 253 /* 254 * KAsan may reuse the contents of kasan_early_shadow_pte directly, 255 * so we should make sure that it maps the zero page read-only. 256 */ 257 for (i = 0; i < PTRS_PER_PTE; i++) 258 set_pte(&kasan_early_shadow_pte[i], 259 pfn_pte(sym_to_pfn(kasan_early_shadow_page), 260 PAGE_KERNEL_RO)); 261 262 memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE); 263 cpu_replace_ttbr1(lm_alias(swapper_pg_dir)); 264 265 /* At this point kasan is fully initialized. Enable error messages */ 266 init_task.kasan_depth = 0; 267 pr_info("KernelAddressSanitizer initialized\n"); 268 } 269