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