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_ACCESSIBLE, node); 43 return __pa(p); 44 } 45 46 static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node, 47 bool early) 48 { 49 if (pmd_none(READ_ONCE(*pmdp))) { 50 phys_addr_t pte_phys = early ? __pa_symbol(kasan_zero_pte) 51 : kasan_alloc_zeroed_page(node); 52 __pmd_populate(pmdp, pte_phys, PMD_TYPE_TABLE); 53 } 54 55 return early ? pte_offset_kimg(pmdp, addr) 56 : pte_offset_kernel(pmdp, addr); 57 } 58 59 static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node, 60 bool early) 61 { 62 if (pud_none(READ_ONCE(*pudp))) { 63 phys_addr_t pmd_phys = early ? __pa_symbol(kasan_zero_pmd) 64 : kasan_alloc_zeroed_page(node); 65 __pud_populate(pudp, pmd_phys, PMD_TYPE_TABLE); 66 } 67 68 return early ? pmd_offset_kimg(pudp, addr) : pmd_offset(pudp, addr); 69 } 70 71 static pud_t *__init kasan_pud_offset(pgd_t *pgdp, unsigned long addr, int node, 72 bool early) 73 { 74 if (pgd_none(READ_ONCE(*pgdp))) { 75 phys_addr_t pud_phys = early ? __pa_symbol(kasan_zero_pud) 76 : kasan_alloc_zeroed_page(node); 77 __pgd_populate(pgdp, pud_phys, PMD_TYPE_TABLE); 78 } 79 80 return early ? pud_offset_kimg(pgdp, addr) : pud_offset(pgdp, addr); 81 } 82 83 static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr, 84 unsigned long end, int node, bool early) 85 { 86 unsigned long next; 87 pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early); 88 89 do { 90 phys_addr_t page_phys = early ? __pa_symbol(kasan_zero_page) 91 : kasan_alloc_zeroed_page(node); 92 next = addr + PAGE_SIZE; 93 set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL)); 94 } while (ptep++, addr = next, addr != end && pte_none(READ_ONCE(*ptep))); 95 } 96 97 static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr, 98 unsigned long end, int node, bool early) 99 { 100 unsigned long next; 101 pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early); 102 103 do { 104 next = pmd_addr_end(addr, end); 105 kasan_pte_populate(pmdp, addr, next, node, early); 106 } while (pmdp++, addr = next, addr != end && pmd_none(READ_ONCE(*pmdp))); 107 } 108 109 static void __init kasan_pud_populate(pgd_t *pgdp, unsigned long addr, 110 unsigned long end, int node, bool early) 111 { 112 unsigned long next; 113 pud_t *pudp = kasan_pud_offset(pgdp, addr, node, early); 114 115 do { 116 next = pud_addr_end(addr, end); 117 kasan_pmd_populate(pudp, addr, next, node, early); 118 } while (pudp++, addr = next, addr != end && pud_none(READ_ONCE(*pudp))); 119 } 120 121 static void __init kasan_pgd_populate(unsigned long addr, unsigned long end, 122 int node, bool early) 123 { 124 unsigned long next; 125 pgd_t *pgdp; 126 127 pgdp = pgd_offset_k(addr); 128 do { 129 next = pgd_addr_end(addr, end); 130 kasan_pud_populate(pgdp, addr, next, node, early); 131 } while (pgdp++, addr = next, addr != end); 132 } 133 134 /* The early shadow maps everything to a single page of zeroes */ 135 asmlinkage void __init kasan_early_init(void) 136 { 137 BUILD_BUG_ON(KASAN_SHADOW_OFFSET != 138 KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT))); 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 *pgdp, *pgdp_new, *pgdp_end; 158 159 pgdp = pgd_offset_k(KASAN_SHADOW_START); 160 pgdp_end = pgd_offset_k(KASAN_SHADOW_END); 161 pgdp_new = pgd_offset_raw(pgdir, KASAN_SHADOW_START); 162 do { 163 set_pgd(pgdp_new, READ_ONCE(*pgdp)); 164 } while (pgdp++, pgdp_new++, pgdp != pgdp_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 below). 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 early_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 early_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