arch/x86/mm/kasan_init_64.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #define DISABLE_BRANCH_PROFILING
   3 #define pr_fmt(fmt) "kasan: " fmt
   4 #include <linux/bootmem.h>
   5 #include <linux/kasan.h>
   6 #include <linux/kdebug.h>
   7 #include <linux/memblock.h>
   8 #include <linux/mm.h>
   9 #include <linux/sched.h>
  10 #include <linux/sched/task.h>
  11 #include <linux/vmalloc.h>
  12
  13 #include <asm/e820/types.h>
  14 #include <asm/pgalloc.h>
  15 #include <asm/tlbflush.h>
  16 #include <asm/sections.h>
  17 #include <asm/pgtable.h>
  18 #include <asm/cpu_entry_area.h>
  19
  20 extern struct range pfn_mapped[E820_MAX_ENTRIES];
  21
  22 static p4d_t tmp_p4d_table[PTRS_PER_P4D] __initdata __aligned(PAGE_SIZE);
  23
  24 static __init void *early_alloc(size_t size, int nid)
  25 {
  26         return memblock_virt_alloc_try_nid_nopanic(size, size,
  27                 __pa(MAX_DMA_ADDRESS), BOOTMEM_ALLOC_ACCESSIBLE, nid);
  28 }
  29
  30 static void __init kasan_populate_pmd(pmd_t *pmd, unsigned long addr,
  31                                       unsigned long end, int nid)
  32 {
  33         pte_t *pte;
  34
  35         if (pmd_none(*pmd)) {
  36                 void *p;
  37
  38                 if (boot_cpu_has(X86_FEATURE_PSE) &&
  39                     ((end - addr) == PMD_SIZE) &&
  40                     IS_ALIGNED(addr, PMD_SIZE)) {
  41                         p = early_alloc(PMD_SIZE, nid);
  42                         if (p && pmd_set_huge(pmd, __pa(p), PAGE_KERNEL))
  43                                 return;
  44                         else if (p)
  45                                 memblock_free(__pa(p), PMD_SIZE);
  46                 }
  47
  48                 p = early_alloc(PAGE_SIZE, nid);
  49                 pmd_populate_kernel(&init_mm, pmd, p);
  50         }
  51
  52         pte = pte_offset_kernel(pmd, addr);
  53         do {
  54                 pte_t entry;
  55                 void *p;
  56
  57                 if (!pte_none(*pte))
  58                         continue;
  59
  60                 p = early_alloc(PAGE_SIZE, nid);
  61                 entry = pfn_pte(PFN_DOWN(__pa(p)), PAGE_KERNEL);
  62                 set_pte_at(&init_mm, addr, pte, entry);
  63         } while (pte++, addr += PAGE_SIZE, addr != end);
  64 }
  65
  66 static void __init kasan_populate_pud(pud_t *pud, unsigned long addr,
  67                                       unsigned long end, int nid)
  68 {
  69         pmd_t *pmd;
  70         unsigned long next;
  71
  72         if (pud_none(*pud)) {
  73                 void *p;
  74
  75                 if (boot_cpu_has(X86_FEATURE_GBPAGES) &&
  76                     ((end - addr) == PUD_SIZE) &&
  77                     IS_ALIGNED(addr, PUD_SIZE)) {
  78                         p = early_alloc(PUD_SIZE, nid);
  79                         if (p && pud_set_huge(pud, __pa(p), PAGE_KERNEL))
  80                                 return;
  81                         else if (p)
  82                                 memblock_free(__pa(p), PUD_SIZE);
  83                 }
  84
  85                 p = early_alloc(PAGE_SIZE, nid);
  86                 pud_populate(&init_mm, pud, p);
  87         }
  88
  89         pmd = pmd_offset(pud, addr);
  90         do {
  91                 next = pmd_addr_end(addr, end);
  92                 if (!pmd_large(*pmd))
  93                         kasan_populate_pmd(pmd, addr, next, nid);
  94         } while (pmd++, addr = next, addr != end);
  95 }
  96
  97 static void __init kasan_populate_p4d(p4d_t *p4d, unsigned long addr,
  98                                       unsigned long end, int nid)
  99 {
 100         pud_t *pud;
 101         unsigned long next;
 102
 103         if (p4d_none(*p4d)) {
 104                 void *p = early_alloc(PAGE_SIZE, nid);
 105
 106                 p4d_populate(&init_mm, p4d, p);
 107         }
 108
 109         pud = pud_offset(p4d, addr);
 110         do {
 111                 next = pud_addr_end(addr, end);
 112                 if (!pud_large(*pud))
 113                         kasan_populate_pud(pud, addr, next, nid);
 114         } while (pud++, addr = next, addr != end);
 115 }
 116
 117 static void __init kasan_populate_pgd(pgd_t *pgd, unsigned long addr,
 118                                       unsigned long end, int nid)
 119 {
 120         void *p;
 121         p4d_t *p4d;
 122         unsigned long next;
 123
 124         if (pgd_none(*pgd)) {
 125                 p = early_alloc(PAGE_SIZE, nid);
 126                 pgd_populate(&init_mm, pgd, p);
 127         }
 128
 129         p4d = p4d_offset(pgd, addr);
 130         do {
 131                 next = p4d_addr_end(addr, end);
 132                 kasan_populate_p4d(p4d, addr, next, nid);
 133         } while (p4d++, addr = next, addr != end);
 134 }
 135
 136 static void __init kasan_populate_shadow(unsigned long addr, unsigned long end,
 137                                          int nid)
 138 {
 139         pgd_t *pgd;
 140         unsigned long next;
 141
 142         addr = addr & PAGE_MASK;
 143         end = round_up(end, PAGE_SIZE);
 144         pgd = pgd_offset_k(addr);
 145         do {
 146                 next = pgd_addr_end(addr, end);
 147                 kasan_populate_pgd(pgd, addr, next, nid);
 148         } while (pgd++, addr = next, addr != end);
 149 }
 150
 151 static void __init map_range(struct range *range)
 152 {
 153         unsigned long start;
 154         unsigned long end;
 155
 156         start = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->start));
 157         end = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->end));
 158
 159         kasan_populate_shadow(start, end, early_pfn_to_nid(range->start));
 160 }
 161
 162 static void __init clear_pgds(unsigned long start,
 163                         unsigned long end)
 164 {
 165         pgd_t *pgd;
 166         /* See comment in kasan_init() */
 167         unsigned long pgd_end = end & PGDIR_MASK;
 168
 169         for (; start < pgd_end; start += PGDIR_SIZE) {
 170                 pgd = pgd_offset_k(start);
 171                 /*
 172                  * With folded p4d, pgd_clear() is nop, use p4d_clear()
 173                  * instead.
 174                  */
 175                 if (CONFIG_PGTABLE_LEVELS < 5)
 176                         p4d_clear(p4d_offset(pgd, start));
 177                 else
 178                         pgd_clear(pgd);
 179         }
 180
 181         pgd = pgd_offset_k(start);
 182         for (; start < end; start += P4D_SIZE)
 183                 p4d_clear(p4d_offset(pgd, start));
 184 }
 185
 186 static inline p4d_t *early_p4d_offset(pgd_t *pgd, unsigned long addr)
 187 {
 188         unsigned long p4d;
 189
 190         if (!IS_ENABLED(CONFIG_X86_5LEVEL))
 191                 return (p4d_t *)pgd;
 192
 193         p4d = __pa_nodebug(pgd_val(*pgd)) & PTE_PFN_MASK;
 194         p4d += __START_KERNEL_map - phys_base;
 195         return (p4d_t *)p4d + p4d_index(addr);
 196 }
 197
 198 static void __init kasan_early_p4d_populate(pgd_t *pgd,
 199                 unsigned long addr,
 200                 unsigned long end)
 201 {
 202         pgd_t pgd_entry;
 203         p4d_t *p4d, p4d_entry;
 204         unsigned long next;
 205
 206         if (pgd_none(*pgd)) {
 207                 pgd_entry = __pgd(_KERNPG_TABLE | __pa_nodebug(kasan_zero_p4d));
 208                 set_pgd(pgd, pgd_entry);
 209         }
 210
 211         p4d = early_p4d_offset(pgd, addr);
 212         do {
 213                 next = p4d_addr_end(addr, end);
 214
 215                 if (!p4d_none(*p4d))
 216                         continue;
 217
 218                 p4d_entry = __p4d(_KERNPG_TABLE | __pa_nodebug(kasan_zero_pud));
 219                 set_p4d(p4d, p4d_entry);
 220         } while (p4d++, addr = next, addr != end && p4d_none(*p4d));
 221 }
 222
 223 static void __init kasan_map_early_shadow(pgd_t *pgd)
 224 {
 225         /* See comment in kasan_init() */
 226         unsigned long addr = KASAN_SHADOW_START & PGDIR_MASK;
 227         unsigned long end = KASAN_SHADOW_END;
 228         unsigned long next;
 229
 230         pgd += pgd_index(addr);
 231         do {
 232                 next = pgd_addr_end(addr, end);
 233                 kasan_early_p4d_populate(pgd, addr, next);
 234         } while (pgd++, addr = next, addr != end);
 235 }
 236
 237 #ifdef CONFIG_KASAN_INLINE
 238 static int kasan_die_handler(struct notifier_block *self,
 239                              unsigned long val,
 240                              void *data)
 241 {
 242         if (val == DIE_GPF) {
 243                 pr_emerg("CONFIG_KASAN_INLINE enabled\n");
 244                 pr_emerg("GPF could be caused by NULL-ptr deref or user memory access\n");
 245         }
 246         return NOTIFY_OK;
 247 }
 248
 249 static struct notifier_block kasan_die_notifier = {
 250         .notifier_call = kasan_die_handler,
 251 };
 252 #endif
 253
 254 void __init kasan_early_init(void)
 255 {
 256         int i;
 257         pteval_t pte_val = __pa_nodebug(kasan_zero_page) | __PAGE_KERNEL | _PAGE_ENC;
 258         pmdval_t pmd_val = __pa_nodebug(kasan_zero_pte) | _KERNPG_TABLE;
 259         pudval_t pud_val = __pa_nodebug(kasan_zero_pmd) | _KERNPG_TABLE;
 260         p4dval_t p4d_val = __pa_nodebug(kasan_zero_pud) | _KERNPG_TABLE;
 261
 262         for (i = 0; i < PTRS_PER_PTE; i++)
 263                 kasan_zero_pte[i] = __pte(pte_val);
 264
 265         for (i = 0; i < PTRS_PER_PMD; i++)
 266                 kasan_zero_pmd[i] = __pmd(pmd_val);
 267
 268         for (i = 0; i < PTRS_PER_PUD; i++)
 269                 kasan_zero_pud[i] = __pud(pud_val);
 270
 271         for (i = 0; IS_ENABLED(CONFIG_X86_5LEVEL) && i < PTRS_PER_P4D; i++)
 272                 kasan_zero_p4d[i] = __p4d(p4d_val);
 273
 274         kasan_map_early_shadow(early_top_pgt);
 275         kasan_map_early_shadow(init_top_pgt);
 276 }
 277
 278 void __init kasan_init(void)
 279 {
 280         int i;
 281         void *shadow_cpu_entry_begin, *shadow_cpu_entry_end;
 282
 283 #ifdef CONFIG_KASAN_INLINE
 284         register_die_notifier(&kasan_die_notifier);
 285 #endif
 286
 287         memcpy(early_top_pgt, init_top_pgt, sizeof(early_top_pgt));
 288
 289         /*
 290          * We use the same shadow offset for 4- and 5-level paging to
 291          * facilitate boot-time switching between paging modes.
 292          * As result in 5-level paging mode KASAN_SHADOW_START and
 293          * KASAN_SHADOW_END are not aligned to PGD boundary.
 294          *
 295          * KASAN_SHADOW_START doesn't share PGD with anything else.
 296          * We claim whole PGD entry to make things easier.
 297          *
 298          * KASAN_SHADOW_END lands in the last PGD entry and it collides with
 299          * bunch of things like kernel code, modules, EFI mapping, etc.
 300          * We need to take extra steps to not overwrite them.
 301          */
 302         if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
 303                 void *ptr;
 304
 305                 ptr = (void *)pgd_page_vaddr(*pgd_offset_k(KASAN_SHADOW_END));
 306                 memcpy(tmp_p4d_table, (void *)ptr, sizeof(tmp_p4d_table));
 307                 set_pgd(&early_top_pgt[pgd_index(KASAN_SHADOW_END)],
 308                                 __pgd(__pa(tmp_p4d_table) | _KERNPG_TABLE));
 309         }
 310
 311         load_cr3(early_top_pgt);
 312         __flush_tlb_all();
 313
 314         clear_pgds(KASAN_SHADOW_START & PGDIR_MASK, KASAN_SHADOW_END);
 315
 316         kasan_populate_zero_shadow((void *)(KASAN_SHADOW_START & PGDIR_MASK),
 317                         kasan_mem_to_shadow((void *)PAGE_OFFSET));
 318
 319         for (i = 0; i < E820_MAX_ENTRIES; i++) {
 320                 if (pfn_mapped[i].end == 0)
 321                         break;
 322
 323                 map_range(&pfn_mapped[i]);
 324         }
 325
 326         shadow_cpu_entry_begin = (void *)CPU_ENTRY_AREA_BASE;
 327         shadow_cpu_entry_begin = kasan_mem_to_shadow(shadow_cpu_entry_begin);
 328         shadow_cpu_entry_begin = (void *)round_down((unsigned long)shadow_cpu_entry_begin,
 329                                                 PAGE_SIZE);
 330
 331         shadow_cpu_entry_end = (void *)(CPU_ENTRY_AREA_BASE +
 332                                         CPU_ENTRY_AREA_MAP_SIZE);
 333         shadow_cpu_entry_end = kasan_mem_to_shadow(shadow_cpu_entry_end);
 334         shadow_cpu_entry_end = (void *)round_up((unsigned long)shadow_cpu_entry_end,
 335                                         PAGE_SIZE);
 336
 337         kasan_populate_zero_shadow(
 338                 kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
 339                 shadow_cpu_entry_begin);
 340
 341         kasan_populate_shadow((unsigned long)shadow_cpu_entry_begin,
 342                               (unsigned long)shadow_cpu_entry_end, 0);
 343
 344         kasan_populate_zero_shadow(shadow_cpu_entry_end,
 345                                 kasan_mem_to_shadow((void *)__START_KERNEL_map));
 346
 347         kasan_populate_shadow((unsigned long)kasan_mem_to_shadow(_stext),
 348                               (unsigned long)kasan_mem_to_shadow(_end),
 349                               early_pfn_to_nid(__pa(_stext)));
 350
 351         kasan_populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END),
 352                                 (void *)KASAN_SHADOW_END);
 353
 354         load_cr3(init_top_pgt);
 355         __flush_tlb_all();
 356
 357         /*
 358          * kasan_zero_page has been used as early shadow memory, thus it may
 359          * contain some garbage. Now we can clear and write protect it, since
 360          * after the TLB flush no one should write to it.
 361          */
 362         memset(kasan_zero_page, 0, PAGE_SIZE);
 363         for (i = 0; i < PTRS_PER_PTE; i++) {
 364                 pte_t pte = __pte(__pa(kasan_zero_page) | __PAGE_KERNEL_RO | _PAGE_ENC);
 365                 set_pte(&kasan_zero_pte[i], pte);
 366         }
 367         /* Flush TLBs again to be sure that write protection applied. */
 368         __flush_tlb_all();
 369
 370         init_task.kasan_depth = 0;
 371         pr_info("KernelAddressSanitizer initialized\n");
 372 }