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/bootmem.h> 15 #include <linux/kasan.h> 16 #include <linux/kernel.h> 17 #include <linux/sched/task.h> 18 #include <linux/memblock.h> 19 #include <linux/start_kernel.h> 20 #include <linux/mm.h> 21 22 #include <asm/mmu_context.h> 23 #include <asm/kernel-pgtable.h> 24 #include <asm/page.h> 25 #include <asm/pgalloc.h> 26 #include <asm/pgtable.h> 27 #include <asm/sections.h> 28 #include <asm/tlbflush.h> 29 30 static pgd_t tmp_pg_dir[PTRS_PER_PGD] __initdata __aligned(PGD_SIZE); 31 32 /* 33 * The p*d_populate functions call virt_to_phys implicitly so they can't be used 34 * directly on kernel symbols (bm_p*d). All the early functions are called too 35 * early to use lm_alias so __p*d_populate functions must be used to populate 36 * with the physical address from __pa_symbol. 37 */ 38 39 static phys_addr_t __init kasan_alloc_zeroed_page(int node) 40 { 41 void *p = memblock_virt_alloc_try_nid(PAGE_SIZE, PAGE_SIZE, 42 __pa(MAX_DMA_ADDRESS), 43 MEMBLOCK_ALLOC_ACCESSIBLE, node); 44 return __pa(p); 45 } 46 47 static pte_t *__init kasan_pte_offset(pmd_t *pmd, unsigned long addr, int node, 48 bool early) 49 { 50 if (pmd_none(*pmd)) { 51 phys_addr_t pte_phys = early ? __pa_symbol(kasan_zero_pte) 52 : kasan_alloc_zeroed_page(node); 53 __pmd_populate(pmd, pte_phys, PMD_TYPE_TABLE); 54 } 55 56 return early ? pte_offset_kimg(pmd, addr) 57 : pte_offset_kernel(pmd, addr); 58 } 59 60 static pmd_t *__init kasan_pmd_offset(pud_t *pud, unsigned long addr, int node, 61 bool early) 62 { 63 if (pud_none(*pud)) { 64 phys_addr_t pmd_phys = early ? __pa_symbol(kasan_zero_pmd) 65 : kasan_alloc_zeroed_page(node); 66 __pud_populate(pud, pmd_phys, PMD_TYPE_TABLE); 67 } 68 69 return early ? pmd_offset_kimg(pud, addr) : pmd_offset(pud, addr); 70 } 71 72 static pud_t *__init kasan_pud_offset(pgd_t *pgd, unsigned long addr, int node, 73 bool early) 74 { 75 if (pgd_none(*pgd)) { 76 phys_addr_t pud_phys = early ? __pa_symbol(kasan_zero_pud) 77 : kasan_alloc_zeroed_page(node); 78 __pgd_populate(pgd, pud_phys, PMD_TYPE_TABLE); 79 } 80 81 return early ? pud_offset_kimg(pgd, addr) : pud_offset(pgd, addr); 82 } 83 84 static void __init kasan_pte_populate(pmd_t *pmd, unsigned long addr, 85 unsigned long end, int node, bool early) 86 { 87 unsigned long next; 88 pte_t *pte = kasan_pte_offset(pmd, addr, node, early); 89 90 do { 91 phys_addr_t page_phys = early ? __pa_symbol(kasan_zero_page) 92 : kasan_alloc_zeroed_page(node); 93 next = addr + PAGE_SIZE; 94 set_pte(pte, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL)); 95 } while (pte++, addr = next, addr != end && pte_none(*pte)); 96 } 97 98 static void __init kasan_pmd_populate(pud_t *pud, unsigned long addr, 99 unsigned long end, int node, bool early) 100 { 101 unsigned long next; 102 pmd_t *pmd = kasan_pmd_offset(pud, addr, node, early); 103 104 do { 105 next = pmd_addr_end(addr, end); 106 kasan_pte_populate(pmd, addr, next, node, early); 107 } while (pmd++, addr = next, addr != end && pmd_none(*pmd)); 108 } 109 110 static void __init kasan_pud_populate(pgd_t *pgd, unsigned long addr, 111 unsigned long end, int node, bool early) 112 { 113 unsigned long next; 114 pud_t *pud = kasan_pud_offset(pgd, addr, node, early); 115 116 do { 117 next = pud_addr_end(addr, end); 118 kasan_pmd_populate(pud, addr, next, node, early); 119 } while (pud++, addr = next, addr != end && pud_none(*pud)); 120 } 121 122 static void __init kasan_pgd_populate(unsigned long addr, unsigned long end, 123 int node, bool early) 124 { 125 unsigned long next; 126 pgd_t *pgd; 127 128 pgd = pgd_offset_k(addr); 129 do { 130 next = pgd_addr_end(addr, end); 131 kasan_pud_populate(pgd, addr, next, node, early); 132 } while (pgd++, addr = next, addr != end); 133 } 134 135 /* The early shadow maps everything to a single page of zeroes */ 136 asmlinkage void __init kasan_early_init(void) 137 { 138 BUILD_BUG_ON(KASAN_SHADOW_OFFSET != KASAN_SHADOW_END - (1UL << 61)); 139 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE)); 140 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE)); 141 kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE, 142 true); 143 } 144 145 /* Set up full kasan mappings, ensuring that the mapped pages are zeroed */ 146 static void __init kasan_map_populate(unsigned long start, unsigned long end, 147 int node) 148 { 149 kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false); 150 } 151 152 /* 153 * Copy the current shadow region into a new pgdir. 154 */ 155 void __init kasan_copy_shadow(pgd_t *pgdir) 156 { 157 pgd_t *pgd, *pgd_new, *pgd_end; 158 159 pgd = pgd_offset_k(KASAN_SHADOW_START); 160 pgd_end = pgd_offset_k(KASAN_SHADOW_END); 161 pgd_new = pgd_offset_raw(pgdir, KASAN_SHADOW_START); 162 do { 163 set_pgd(pgd_new, *pgd); 164 } while (pgd++, pgd_new++, pgd != pgd_end); 165 } 166 167 static void __init clear_pgds(unsigned long start, 168 unsigned long end) 169 { 170 /* 171 * Remove references to kasan page tables from 172 * swapper_pg_dir. pgd_clear() can't be used 173 * here because it's nop on 2,3-level pagetable setups 174 */ 175 for (; start < end; start += PGDIR_SIZE) 176 set_pgd(pgd_offset_k(start), __pgd(0)); 177 } 178 179 void __init kasan_init(void) 180 { 181 u64 kimg_shadow_start, kimg_shadow_end; 182 u64 mod_shadow_start, mod_shadow_end; 183 struct memblock_region *reg; 184 int i; 185 186 kimg_shadow_start = (u64)kasan_mem_to_shadow(_text) & PAGE_MASK; 187 kimg_shadow_end = PAGE_ALIGN((u64)kasan_mem_to_shadow(_end)); 188 189 mod_shadow_start = (u64)kasan_mem_to_shadow((void *)MODULES_VADDR); 190 mod_shadow_end = (u64)kasan_mem_to_shadow((void *)MODULES_END); 191 192 /* 193 * We are going to perform proper setup of shadow memory. 194 * At first we should unmap early shadow (clear_pgds() call bellow). 195 * However, instrumented code couldn't execute without shadow memory. 196 * tmp_pg_dir used to keep early shadow mapped until full shadow 197 * setup will be finished. 198 */ 199 memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(tmp_pg_dir)); 200 dsb(ishst); 201 cpu_replace_ttbr1(lm_alias(tmp_pg_dir)); 202 203 clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END); 204 205 kasan_map_populate(kimg_shadow_start, kimg_shadow_end, 206 pfn_to_nid(virt_to_pfn(lm_alias(_text)))); 207 208 kasan_populate_zero_shadow((void *)KASAN_SHADOW_START, 209 (void *)mod_shadow_start); 210 kasan_populate_zero_shadow((void *)kimg_shadow_end, 211 kasan_mem_to_shadow((void *)PAGE_OFFSET)); 212 213 if (kimg_shadow_start > mod_shadow_end) 214 kasan_populate_zero_shadow((void *)mod_shadow_end, 215 (void *)kimg_shadow_start); 216 217 for_each_memblock(memory, reg) { 218 void *start = (void *)__phys_to_virt(reg->base); 219 void *end = (void *)__phys_to_virt(reg->base + reg->size); 220 221 if (start >= end) 222 break; 223 224 kasan_map_populate((unsigned long)kasan_mem_to_shadow(start), 225 (unsigned long)kasan_mem_to_shadow(end), 226 pfn_to_nid(virt_to_pfn(start))); 227 } 228 229 /* 230 * KAsan may reuse the contents of kasan_zero_pte directly, so we 231 * should make sure that it maps the zero page read-only. 232 */ 233 for (i = 0; i < PTRS_PER_PTE; i++) 234 set_pte(&kasan_zero_pte[i], 235 pfn_pte(sym_to_pfn(kasan_zero_page), PAGE_KERNEL_RO)); 236 237 memset(kasan_zero_page, 0, PAGE_SIZE); 238 cpu_replace_ttbr1(lm_alias(swapper_pg_dir)); 239 240 /* At this point kasan is fully initialized. Enable error messages */ 241 init_task.kasan_depth = 0; 242 pr_info("KernelAddressSanitizer initialized\n"); 243 } 244