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