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
   5 /* cpu_feature_enabled() cannot be used this early */
   6 #define USE_EARLY_PGTABLE_L5
   7
   8 #include <linux/memblock.h>
   9 #include <linux/kasan.h>
  10 #include <linux/kdebug.h>
  11 #include <linux/mm.h>
  12 #include <linux/sched.h>
  13 #include <linux/sched/task.h>
  14 #include <linux/vmalloc.h>
  15
  16 #include <asm/e820/types.h>
  17 #include <asm/pgalloc.h>
  18 #include <asm/tlbflush.h>
  19 #include <asm/sections.h>
  20 #include <asm/pgtable.h>
  21 #include <asm/cpu_entry_area.h>
  22
  23 extern struct range pfn_mapped[E820_MAX_ENTRIES];
  24
  25 static p4d_t tmp_p4d_table[MAX_PTRS_PER_P4D] __initdata __aligned(PAGE_SIZE);
  26
  27 static __init void *early_alloc(size_t size, int nid, bool should_panic)
  28 {
  29         void *ptr = memblock_alloc_try_nid(size, size,
  30                         __pa(MAX_DMA_ADDRESS), MEMBLOCK_ALLOC_ACCESSIBLE, nid);
  31
  32         if (!ptr && should_panic)
  33                 panic("%pS: Failed to allocate page, nid=%d from=%lx\n",
  34                       (void *)_RET_IP_, nid, __pa(MAX_DMA_ADDRESS));
  35
  36         return ptr;
  37 }
  38
  39 static void __init kasan_populate_pmd(pmd_t *pmd, unsigned long addr,
  40                                       unsigned long end, int nid)
  41 {
  42         pte_t *pte;
  43
  44         if (pmd_none(*pmd)) {
  45                 void *p;
  46
  47                 if (boot_cpu_has(X86_FEATURE_PSE) &&
  48                     ((end - addr) == PMD_SIZE) &&
  49                     IS_ALIGNED(addr, PMD_SIZE)) {
  50                         p = early_alloc(PMD_SIZE, nid, false);
  51                         if (p && pmd_set_huge(pmd, __pa(p), PAGE_KERNEL))
  52                                 return;
  53                         else if (p)
  54                                 memblock_free(__pa(p), PMD_SIZE);
  55                 }
  56
  57                 p = early_alloc(PAGE_SIZE, nid, true);
  58                 pmd_populate_kernel(&init_mm, pmd, p);
  59         }
  60
  61         pte = pte_offset_kernel(pmd, addr);
  62         do {
  63                 pte_t entry;
  64                 void *p;
  65
  66                 if (!pte_none(*pte))
  67                         continue;
  68
  69                 p = early_alloc(PAGE_SIZE, nid, true);
  70                 entry = pfn_pte(PFN_DOWN(__pa(p)), PAGE_KERNEL);
  71                 set_pte_at(&init_mm, addr, pte, entry);
  72         } while (pte++, addr += PAGE_SIZE, addr != end);
  73 }
  74
  75 static void __init kasan_populate_pud(pud_t *pud, unsigned long addr,
  76                                       unsigned long end, int nid)
  77 {
  78         pmd_t *pmd;
  79         unsigned long next;
  80
  81         if (pud_none(*pud)) {
  82                 void *p;
  83
  84                 if (boot_cpu_has(X86_FEATURE_GBPAGES) &&
  85                     ((end - addr) == PUD_SIZE) &&
  86                     IS_ALIGNED(addr, PUD_SIZE)) {
  87                         p = early_alloc(PUD_SIZE, nid, false);
  88                         if (p && pud_set_huge(pud, __pa(p), PAGE_KERNEL))
  89                                 return;
  90                         else if (p)
  91                                 memblock_free(__pa(p), PUD_SIZE);
  92                 }
  93
  94                 p = early_alloc(PAGE_SIZE, nid, true);
  95                 pud_populate(&init_mm, pud, p);
  96         }
  97
  98         pmd = pmd_offset(pud, addr);
  99         do {
 100                 next = pmd_addr_end(addr, end);
 101                 if (!pmd_large(*pmd))
 102                         kasan_populate_pmd(pmd, addr, next, nid);
 103         } while (pmd++, addr = next, addr != end);
 104 }
 105
 106 static void __init kasan_populate_p4d(p4d_t *p4d, unsigned long addr,
 107                                       unsigned long end, int nid)
 108 {
 109         pud_t *pud;
 110         unsigned long next;
 111
 112         if (p4d_none(*p4d)) {
 113                 void *p = early_alloc(PAGE_SIZE, nid, true);
 114
 115                 p4d_populate(&init_mm, p4d, p);
 116         }
 117
 118         pud = pud_offset(p4d, addr);
 119         do {
 120                 next = pud_addr_end(addr, end);
 121                 if (!pud_large(*pud))
 122                         kasan_populate_pud(pud, addr, next, nid);
 123         } while (pud++, addr = next, addr != end);
 124 }
 125
 126 static void __init kasan_populate_pgd(pgd_t *pgd, unsigned long addr,
 127                                       unsigned long end, int nid)
 128 {
 129         void *p;
 130         p4d_t *p4d;
 131         unsigned long next;
 132
 133         if (pgd_none(*pgd)) {
 134                 p = early_alloc(PAGE_SIZE, nid, true);
 135                 pgd_populate(&init_mm, pgd, p);
 136         }
 137
 138         p4d = p4d_offset(pgd, addr);
 139         do {
 140                 next = p4d_addr_end(addr, end);
 141                 kasan_populate_p4d(p4d, addr, next, nid);
 142         } while (p4d++, addr = next, addr != end);
 143 }
 144
 145 static void __init kasan_populate_shadow(unsigned long addr, unsigned long end,
 146                                          int nid)
 147 {
 148         pgd_t *pgd;
 149         unsigned long next;
 150
 151         addr = addr & PAGE_MASK;
 152         end = round_up(end, PAGE_SIZE);
 153         pgd = pgd_offset_k(addr);
 154         do {
 155                 next = pgd_addr_end(addr, end);
 156                 kasan_populate_pgd(pgd, addr, next, nid);
 157         } while (pgd++, addr = next, addr != end);
 158 }
 159
 160 static void __init map_range(struct range *range)
 161 {
 162         unsigned long start;
 163         unsigned long end;
 164
 165         start = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->start));
 166         end = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->end));
 167
 168         kasan_populate_shadow(start, end, early_pfn_to_nid(range->start));
 169 }
 170
 171 static void __init clear_pgds(unsigned long start,
 172                         unsigned long end)
 173 {
 174         pgd_t *pgd;
 175         /* See comment in kasan_init() */
 176         unsigned long pgd_end = end & PGDIR_MASK;
 177
 178         for (; start < pgd_end; start += PGDIR_SIZE) {
 179                 pgd = pgd_offset_k(start);
 180                 /*
 181                  * With folded p4d, pgd_clear() is nop, use p4d_clear()
 182                  * instead.
 183                  */
 184                 if (pgtable_l5_enabled())
 185                         pgd_clear(pgd);
 186                 else
 187                         p4d_clear(p4d_offset(pgd, start));
 188         }
 189
 190         pgd = pgd_offset_k(start);
 191         for (; start < end; start += P4D_SIZE)
 192                 p4d_clear(p4d_offset(pgd, start));
 193 }
 194
 195 static inline p4d_t *early_p4d_offset(pgd_t *pgd, unsigned long addr)
 196 {
 197         unsigned long p4d;
 198
 199         if (!pgtable_l5_enabled())
 200                 return (p4d_t *)pgd;
 201
 202         p4d = pgd_val(*pgd) & PTE_PFN_MASK;
 203         p4d += __START_KERNEL_map - phys_base;
 204         return (p4d_t *)p4d + p4d_index(addr);
 205 }
 206
 207 static void __init kasan_early_p4d_populate(pgd_t *pgd,
 208                 unsigned long addr,
 209                 unsigned long end)
 210 {
 211         pgd_t pgd_entry;
 212         p4d_t *p4d, p4d_entry;
 213         unsigned long next;
 214
 215         if (pgd_none(*pgd)) {
 216                 pgd_entry = __pgd(_KERNPG_TABLE |
 217                                         __pa_nodebug(kasan_early_shadow_p4d));
 218                 set_pgd(pgd, pgd_entry);
 219         }
 220
 221         p4d = early_p4d_offset(pgd, addr);
 222         do {
 223                 next = p4d_addr_end(addr, end);
 224
 225                 if (!p4d_none(*p4d))
 226                         continue;
 227
 228                 p4d_entry = __p4d(_KERNPG_TABLE |
 229                                         __pa_nodebug(kasan_early_shadow_pud));
 230                 set_p4d(p4d, p4d_entry);
 231         } while (p4d++, addr = next, addr != end && p4d_none(*p4d));
 232 }
 233
 234 static void __init kasan_map_early_shadow(pgd_t *pgd)
 235 {
 236         /* See comment in kasan_init() */
 237         unsigned long addr = KASAN_SHADOW_START & PGDIR_MASK;
 238         unsigned long end = KASAN_SHADOW_END;
 239         unsigned long next;
 240
 241         pgd += pgd_index(addr);
 242         do {
 243                 next = pgd_addr_end(addr, end);
 244                 kasan_early_p4d_populate(pgd, addr, next);
 245         } while (pgd++, addr = next, addr != end);
 246 }
 247
 248 #ifdef CONFIG_KASAN_INLINE
 249 static int kasan_die_handler(struct notifier_block *self,
 250                              unsigned long val,
 251                              void *data)
 252 {
 253         if (val == DIE_GPF) {
 254                 pr_emerg("CONFIG_KASAN_INLINE enabled\n");
 255                 pr_emerg("GPF could be caused by NULL-ptr deref or user memory access\n");
 256         }
 257         return NOTIFY_OK;
 258 }
 259
 260 static struct notifier_block kasan_die_notifier = {
 261         .notifier_call = kasan_die_handler,
 262 };
 263 #endif
 264
 265 void __init kasan_early_init(void)
 266 {
 267         int i;
 268         pteval_t pte_val = __pa_nodebug(kasan_early_shadow_page) |
 269                                 __PAGE_KERNEL | _PAGE_ENC;
 270         pmdval_t pmd_val = __pa_nodebug(kasan_early_shadow_pte) | _KERNPG_TABLE;
 271         pudval_t pud_val = __pa_nodebug(kasan_early_shadow_pmd) | _KERNPG_TABLE;
 272         p4dval_t p4d_val = __pa_nodebug(kasan_early_shadow_pud) | _KERNPG_TABLE;
 273
 274         /* Mask out unsupported __PAGE_KERNEL bits: */
 275         pte_val &= __default_kernel_pte_mask;
 276         pmd_val &= __default_kernel_pte_mask;
 277         pud_val &= __default_kernel_pte_mask;
 278         p4d_val &= __default_kernel_pte_mask;
 279
 280         for (i = 0; i < PTRS_PER_PTE; i++)
 281                 kasan_early_shadow_pte[i] = __pte(pte_val);
 282
 283         for (i = 0; i < PTRS_PER_PMD; i++)
 284                 kasan_early_shadow_pmd[i] = __pmd(pmd_val);
 285
 286         for (i = 0; i < PTRS_PER_PUD; i++)
 287                 kasan_early_shadow_pud[i] = __pud(pud_val);
 288
 289         for (i = 0; pgtable_l5_enabled() && i < PTRS_PER_P4D; i++)
 290                 kasan_early_shadow_p4d[i] = __p4d(p4d_val);
 291
 292         kasan_map_early_shadow(early_top_pgt);
 293         kasan_map_early_shadow(init_top_pgt);
 294 }
 295
 296 void __init kasan_init(void)
 297 {
 298         int i;
 299         void *shadow_cpu_entry_begin, *shadow_cpu_entry_end;
 300
 301 #ifdef CONFIG_KASAN_INLINE
 302         register_die_notifier(&kasan_die_notifier);
 303 #endif
 304
 305         memcpy(early_top_pgt, init_top_pgt, sizeof(early_top_pgt));
 306
 307         /*
 308          * We use the same shadow offset for 4- and 5-level paging to
 309          * facilitate boot-time switching between paging modes.
 310          * As result in 5-level paging mode KASAN_SHADOW_START and
 311          * KASAN_SHADOW_END are not aligned to PGD boundary.
 312          *
 313          * KASAN_SHADOW_START doesn't share PGD with anything else.
 314          * We claim whole PGD entry to make things easier.
 315          *
 316          * KASAN_SHADOW_END lands in the last PGD entry and it collides with
 317          * bunch of things like kernel code, modules, EFI mapping, etc.
 318          * We need to take extra steps to not overwrite them.
 319          */
 320         if (pgtable_l5_enabled()) {
 321                 void *ptr;
 322
 323                 ptr = (void *)pgd_page_vaddr(*pgd_offset_k(KASAN_SHADOW_END));
 324                 memcpy(tmp_p4d_table, (void *)ptr, sizeof(tmp_p4d_table));
 325                 set_pgd(&early_top_pgt[pgd_index(KASAN_SHADOW_END)],
 326                                 __pgd(__pa(tmp_p4d_table) | _KERNPG_TABLE));
 327         }
 328
 329         load_cr3(early_top_pgt);
 330         __flush_tlb_all();
 331
 332         clear_pgds(KASAN_SHADOW_START & PGDIR_MASK, KASAN_SHADOW_END);
 333
 334         kasan_populate_early_shadow((void *)(KASAN_SHADOW_START & PGDIR_MASK),
 335                         kasan_mem_to_shadow((void *)PAGE_OFFSET));
 336
 337         for (i = 0; i < E820_MAX_ENTRIES; i++) {
 338                 if (pfn_mapped[i].end == 0)
 339                         break;
 340
 341                 map_range(&pfn_mapped[i]);
 342         }
 343
 344         shadow_cpu_entry_begin = (void *)CPU_ENTRY_AREA_BASE;
 345         shadow_cpu_entry_begin = kasan_mem_to_shadow(shadow_cpu_entry_begin);
 346         shadow_cpu_entry_begin = (void *)round_down(
 347                         (unsigned long)shadow_cpu_entry_begin, PAGE_SIZE);
 348
 349         shadow_cpu_entry_end = (void *)(CPU_ENTRY_AREA_BASE +
 350                                         CPU_ENTRY_AREA_MAP_SIZE);
 351         shadow_cpu_entry_end = kasan_mem_to_shadow(shadow_cpu_entry_end);
 352         shadow_cpu_entry_end = (void *)round_up(
 353                         (unsigned long)shadow_cpu_entry_end, PAGE_SIZE);
 354
 355         kasan_populate_early_shadow(
 356                 kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
 357                 shadow_cpu_entry_begin);
 358
 359         kasan_populate_shadow((unsigned long)shadow_cpu_entry_begin,
 360                               (unsigned long)shadow_cpu_entry_end, 0);
 361
 362         kasan_populate_early_shadow(shadow_cpu_entry_end,
 363                         kasan_mem_to_shadow((void *)__START_KERNEL_map));
 364
 365         kasan_populate_shadow((unsigned long)kasan_mem_to_shadow(_stext),
 366                               (unsigned long)kasan_mem_to_shadow(_end),
 367                               early_pfn_to_nid(__pa(_stext)));
 368
 369         kasan_populate_early_shadow(kasan_mem_to_shadow((void *)MODULES_END),
 370                                         (void *)KASAN_SHADOW_END);
 371
 372         load_cr3(init_top_pgt);
 373         __flush_tlb_all();
 374
 375         /*
 376          * kasan_early_shadow_page has been used as early shadow memory, thus
 377          * it may contain some garbage. Now we can clear and write protect it,
 378          * since after the TLB flush no one should write to it.
 379          */
 380         memset(kasan_early_shadow_page, 0, PAGE_SIZE);
 381         for (i = 0; i < PTRS_PER_PTE; i++) {
 382                 pte_t pte;
 383                 pgprot_t prot;
 384
 385                 prot = __pgprot(__PAGE_KERNEL_RO | _PAGE_ENC);
 386                 pgprot_val(prot) &= __default_kernel_pte_mask;
 387
 388                 pte = __pte(__pa(kasan_early_shadow_page) | pgprot_val(prot));
 389                 set_pte(&kasan_early_shadow_pte[i], pte);
 390         }
 391         /* Flush TLBs again to be sure that write protection applied. */
 392         __flush_tlb_all();
 393
 394         init_task.kasan_depth = 0;
 395         pr_info("KernelAddressSanitizer initialized\n");
 396 }