1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2023 Loongson Technology Corporation Limited 4 */ 5 #define pr_fmt(fmt) "kasan: " fmt 6 #include <linux/kasan.h> 7 #include <linux/memblock.h> 8 #include <linux/sched/task.h> 9 10 #include <asm/tlbflush.h> 11 #include <asm/pgalloc.h> 12 #include <asm-generic/sections.h> 13 14 static pgd_t kasan_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE); 15 16 #ifdef __PAGETABLE_PUD_FOLDED 17 #define __p4d_none(early, p4d) (0) 18 #else 19 #define __p4d_none(early, p4d) (early ? (p4d_val(p4d) == 0) : \ 20 (__pa(p4d_val(p4d)) == (unsigned long)__pa(kasan_early_shadow_pud))) 21 #endif 22 23 #ifdef __PAGETABLE_PMD_FOLDED 24 #define __pud_none(early, pud) (0) 25 #else 26 #define __pud_none(early, pud) (early ? (pud_val(pud) == 0) : \ 27 (__pa(pud_val(pud)) == (unsigned long)__pa(kasan_early_shadow_pmd))) 28 #endif 29 30 #define __pmd_none(early, pmd) (early ? (pmd_val(pmd) == 0) : \ 31 (__pa(pmd_val(pmd)) == (unsigned long)__pa(kasan_early_shadow_pte))) 32 33 #define __pte_none(early, pte) (early ? pte_none(pte) : \ 34 ((pte_val(pte) & _PFN_MASK) == (unsigned long)__pa(kasan_early_shadow_page))) 35 36 bool kasan_early_stage = true; 37 38 /* 39 * Alloc memory for shadow memory page table. 40 */ 41 static phys_addr_t __init kasan_alloc_zeroed_page(int node) 42 { 43 void *p = memblock_alloc_try_nid(PAGE_SIZE, PAGE_SIZE, 44 __pa(MAX_DMA_ADDRESS), MEMBLOCK_ALLOC_ACCESSIBLE, node); 45 if (!p) 46 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n", 47 __func__, PAGE_SIZE, PAGE_SIZE, node, __pa(MAX_DMA_ADDRESS)); 48 49 return __pa(p); 50 } 51 52 static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node, bool early) 53 { 54 if (__pmd_none(early, READ_ONCE(*pmdp))) { 55 phys_addr_t pte_phys = early ? 56 __pa_symbol(kasan_early_shadow_pte) : kasan_alloc_zeroed_page(node); 57 if (!early) 58 memcpy(__va(pte_phys), kasan_early_shadow_pte, sizeof(kasan_early_shadow_pte)); 59 pmd_populate_kernel(NULL, pmdp, (pte_t *)__va(pte_phys)); 60 } 61 62 return pte_offset_kernel(pmdp, addr); 63 } 64 65 static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node, bool early) 66 { 67 if (__pud_none(early, READ_ONCE(*pudp))) { 68 phys_addr_t pmd_phys = early ? 69 __pa_symbol(kasan_early_shadow_pmd) : kasan_alloc_zeroed_page(node); 70 if (!early) 71 memcpy(__va(pmd_phys), kasan_early_shadow_pmd, sizeof(kasan_early_shadow_pmd)); 72 pud_populate(&init_mm, pudp, (pmd_t *)__va(pmd_phys)); 73 } 74 75 return pmd_offset(pudp, addr); 76 } 77 78 static pud_t *__init kasan_pud_offset(p4d_t *p4dp, unsigned long addr, int node, bool early) 79 { 80 if (__p4d_none(early, READ_ONCE(*p4dp))) { 81 phys_addr_t pud_phys = early ? 82 __pa_symbol(kasan_early_shadow_pud) : kasan_alloc_zeroed_page(node); 83 if (!early) 84 memcpy(__va(pud_phys), kasan_early_shadow_pud, sizeof(kasan_early_shadow_pud)); 85 p4d_populate(&init_mm, p4dp, (pud_t *)__va(pud_phys)); 86 } 87 88 return pud_offset(p4dp, addr); 89 } 90 91 static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr, 92 unsigned long end, int node, bool early) 93 { 94 unsigned long next; 95 pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early); 96 97 do { 98 phys_addr_t page_phys = early ? 99 __pa_symbol(kasan_early_shadow_page) 100 : kasan_alloc_zeroed_page(node); 101 next = addr + PAGE_SIZE; 102 set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL)); 103 } while (ptep++, addr = next, addr != end && __pte_none(early, READ_ONCE(*ptep))); 104 } 105 106 static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr, 107 unsigned long end, int node, bool early) 108 { 109 unsigned long next; 110 pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early); 111 112 do { 113 next = pmd_addr_end(addr, end); 114 kasan_pte_populate(pmdp, addr, next, node, early); 115 } while (pmdp++, addr = next, addr != end && __pmd_none(early, READ_ONCE(*pmdp))); 116 } 117 118 static void __init kasan_pud_populate(p4d_t *p4dp, unsigned long addr, 119 unsigned long end, int node, bool early) 120 { 121 unsigned long next; 122 pud_t *pudp = kasan_pud_offset(p4dp, addr, node, early); 123 124 do { 125 next = pud_addr_end(addr, end); 126 kasan_pmd_populate(pudp, addr, next, node, early); 127 } while (pudp++, addr = next, addr != end); 128 } 129 130 static void __init kasan_p4d_populate(pgd_t *pgdp, unsigned long addr, 131 unsigned long end, int node, bool early) 132 { 133 unsigned long next; 134 p4d_t *p4dp = p4d_offset(pgdp, addr); 135 136 do { 137 next = p4d_addr_end(addr, end); 138 kasan_pud_populate(p4dp, addr, next, node, early); 139 } while (p4dp++, addr = next, addr != end); 140 } 141 142 static void __init kasan_pgd_populate(unsigned long addr, unsigned long end, 143 int node, bool early) 144 { 145 unsigned long next; 146 pgd_t *pgdp; 147 148 pgdp = pgd_offset_k(addr); 149 150 do { 151 next = pgd_addr_end(addr, end); 152 kasan_p4d_populate(pgdp, addr, next, node, early); 153 } while (pgdp++, addr = next, addr != end); 154 155 } 156 157 /* Set up full kasan mappings, ensuring that the mapped pages are zeroed */ 158 static void __init kasan_map_populate(unsigned long start, unsigned long end, 159 int node) 160 { 161 kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false); 162 } 163 164 asmlinkage void __init kasan_early_init(void) 165 { 166 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE)); 167 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE)); 168 } 169 170 static inline void kasan_set_pgd(pgd_t *pgdp, pgd_t pgdval) 171 { 172 WRITE_ONCE(*pgdp, pgdval); 173 } 174 175 static void __init clear_pgds(unsigned long start, unsigned long end) 176 { 177 /* 178 * Remove references to kasan page tables from 179 * swapper_pg_dir. pgd_clear() can't be used 180 * here because it's nop on 2,3-level pagetable setups 181 */ 182 for (; start < end; start += PGDIR_SIZE) 183 kasan_set_pgd((pgd_t *)pgd_offset_k(start), __pgd(0)); 184 } 185 186 void __init kasan_init(void) 187 { 188 u64 i; 189 phys_addr_t pa_start, pa_end; 190 191 /* 192 * PGD was populated as invalid_pmd_table or invalid_pud_table 193 * in pagetable_init() which depends on how many levels of page 194 * table you are using, but we had to clean the gpd of kasan 195 * shadow memory, as the pgd value is none-zero. 196 * The assertion pgd_none is going to be false and the formal populate 197 * afterwards is not going to create any new pgd at all. 198 */ 199 memcpy(kasan_pg_dir, swapper_pg_dir, sizeof(kasan_pg_dir)); 200 csr_write64(__pa_symbol(kasan_pg_dir), LOONGARCH_CSR_PGDH); 201 local_flush_tlb_all(); 202 203 clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END); 204 205 /* Maps everything to a single page of zeroes */ 206 kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE, true); 207 208 kasan_populate_early_shadow(kasan_mem_to_shadow((void *)VMALLOC_START), 209 kasan_mem_to_shadow((void *)KFENCE_AREA_END)); 210 211 kasan_early_stage = false; 212 213 /* Populate the linear mapping */ 214 for_each_mem_range(i, &pa_start, &pa_end) { 215 void *start = (void *)phys_to_virt(pa_start); 216 void *end = (void *)phys_to_virt(pa_end); 217 218 if (start >= end) 219 break; 220 221 kasan_map_populate((unsigned long)kasan_mem_to_shadow(start), 222 (unsigned long)kasan_mem_to_shadow(end), NUMA_NO_NODE); 223 } 224 225 /* Populate modules mapping */ 226 kasan_map_populate((unsigned long)kasan_mem_to_shadow((void *)MODULES_VADDR), 227 (unsigned long)kasan_mem_to_shadow((void *)MODULES_END), NUMA_NO_NODE); 228 /* 229 * KAsan may reuse the contents of kasan_early_shadow_pte directly, so we 230 * should make sure that it maps the zero page read-only. 231 */ 232 for (i = 0; i < PTRS_PER_PTE; i++) 233 set_pte(&kasan_early_shadow_pte[i], 234 pfn_pte(__phys_to_pfn(__pa_symbol(kasan_early_shadow_page)), PAGE_KERNEL_RO)); 235 236 memset(kasan_early_shadow_page, 0, PAGE_SIZE); 237 csr_write64(__pa_symbol(swapper_pg_dir), LOONGARCH_CSR_PGDH); 238 local_flush_tlb_all(); 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