arch/s390/boot/vmem.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/sched/task.h>
   3 #include <linux/pgtable.h>
   4 #include <linux/kasan.h>
   5 #include <asm/pgalloc.h>
   6 #include <asm/facility.h>
   7 #include <asm/sections.h>
   8 #include <asm/physmem_info.h>
   9 #include <asm/maccess.h>
  10 #include <asm/abs_lowcore.h>
  11 #include "decompressor.h"
  12 #include "boot.h"
  13
  14 unsigned long __bootdata_preserved(s390_invalid_asce);
  15
  16 #ifdef CONFIG_PROC_FS
  17 atomic_long_t __bootdata_preserved(direct_pages_count[PG_DIRECT_MAP_MAX]);
  18 #endif
  19
  20 #define init_mm                 (*(struct mm_struct *)vmlinux.init_mm_off)
  21 #define swapper_pg_dir          vmlinux.swapper_pg_dir_off
  22 #define invalid_pg_dir          vmlinux.invalid_pg_dir_off
  23
  24 enum populate_mode {
  25         POPULATE_NONE,
  26         POPULATE_DIRECT,
  27         POPULATE_ABS_LOWCORE,
  28 #ifdef CONFIG_KASAN
  29         POPULATE_KASAN_MAP_SHADOW,
  30         POPULATE_KASAN_ZERO_SHADOW,
  31         POPULATE_KASAN_SHALLOW
  32 #endif
  33 };
  34
  35 static void pgtable_populate(unsigned long addr, unsigned long end, enum populate_mode mode);
  36
  37 #ifdef CONFIG_KASAN
  38
  39 #define kasan_early_shadow_page vmlinux.kasan_early_shadow_page_off
  40 #define kasan_early_shadow_pte  ((pte_t *)vmlinux.kasan_early_shadow_pte_off)
  41 #define kasan_early_shadow_pmd  ((pmd_t *)vmlinux.kasan_early_shadow_pmd_off)
  42 #define kasan_early_shadow_pud  ((pud_t *)vmlinux.kasan_early_shadow_pud_off)
  43 #define kasan_early_shadow_p4d  ((p4d_t *)vmlinux.kasan_early_shadow_p4d_off)
  44 #define __sha(x)                ((unsigned long)kasan_mem_to_shadow((void *)x))
  45
  46 static pte_t pte_z;
  47
  48 static inline void kasan_populate(unsigned long start, unsigned long end, enum populate_mode mode)
  49 {
  50         start = PAGE_ALIGN_DOWN(__sha(start));
  51         end = PAGE_ALIGN(__sha(end));
  52         pgtable_populate(start, end, mode);
  53 }
  54
  55 static void kasan_populate_shadow(void)
  56 {
  57         pmd_t pmd_z = __pmd(__pa(kasan_early_shadow_pte) | _SEGMENT_ENTRY);
  58         pud_t pud_z = __pud(__pa(kasan_early_shadow_pmd) | _REGION3_ENTRY);
  59         p4d_t p4d_z = __p4d(__pa(kasan_early_shadow_pud) | _REGION2_ENTRY);
  60         unsigned long untracked_end;
  61         unsigned long start, end;
  62         int i;
  63
  64         pte_z = __pte(__pa(kasan_early_shadow_page) | pgprot_val(PAGE_KERNEL_RO));
  65         if (!machine.has_nx)
  66                 pte_z = clear_pte_bit(pte_z, __pgprot(_PAGE_NOEXEC));
  67         crst_table_init((unsigned long *)kasan_early_shadow_p4d, p4d_val(p4d_z));
  68         crst_table_init((unsigned long *)kasan_early_shadow_pud, pud_val(pud_z));
  69         crst_table_init((unsigned long *)kasan_early_shadow_pmd, pmd_val(pmd_z));
  70         memset64((u64 *)kasan_early_shadow_pte, pte_val(pte_z), PTRS_PER_PTE);
  71
  72         /*
  73          * Current memory layout:
  74          * +- 0 -------------+         +- shadow start -+
  75          * |1:1 ident mapping|        /|1/8 of ident map|
  76          * |                 |       / |                |
  77          * +-end of ident map+      /  +----------------+
  78          * | ... gap ...     |     /   |    kasan       |
  79          * |                 |    /    |  zero page     |
  80          * +- vmalloc area  -+   /     |   mapping      |
  81          * | vmalloc_size    |  /      | (untracked)    |
  82          * +- modules vaddr -+ /       +----------------+
  83          * | 2Gb             |/        |    unmapped    | allocated per module
  84          * +- shadow start  -+         +----------------+
  85          * | 1/8 addr space  |         | zero pg mapping| (untracked)
  86          * +- shadow end ----+---------+- shadow end ---+
  87          *
  88          * Current memory layout (KASAN_VMALLOC):
  89          * +- 0 -------------+         +- shadow start -+
  90          * |1:1 ident mapping|        /|1/8 of ident map|
  91          * |                 |       / |                |
  92          * +-end of ident map+      /  +----------------+
  93          * | ... gap ...     |     /   | kasan zero page| (untracked)
  94          * |                 |    /    | mapping        |
  95          * +- vmalloc area  -+   /     +----------------+
  96          * | vmalloc_size    |  /      |shallow populate|
  97          * +- modules vaddr -+ /       +----------------+
  98          * | 2Gb             |/        |shallow populate|
  99          * +- shadow start  -+         +----------------+
 100          * | 1/8 addr space  |         | zero pg mapping| (untracked)
 101          * +- shadow end ----+---------+- shadow end ---+
 102          */
 103
 104         for_each_physmem_usable_range(i, &start, &end)
 105                 kasan_populate(start, end, POPULATE_KASAN_MAP_SHADOW);
 106         if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) {
 107                 untracked_end = VMALLOC_START;
 108                 /* shallowly populate kasan shadow for vmalloc and modules */
 109                 kasan_populate(VMALLOC_START, MODULES_END, POPULATE_KASAN_SHALLOW);
 110         } else {
 111                 untracked_end = MODULES_VADDR;
 112         }
 113         /* populate kasan shadow for untracked memory */
 114         kasan_populate(ident_map_size, untracked_end, POPULATE_KASAN_ZERO_SHADOW);
 115         kasan_populate(MODULES_END, _REGION1_SIZE, POPULATE_KASAN_ZERO_SHADOW);
 116 }
 117
 118 static bool kasan_pgd_populate_zero_shadow(pgd_t *pgd, unsigned long addr,
 119                                            unsigned long end, enum populate_mode mode)
 120 {
 121         if (mode == POPULATE_KASAN_ZERO_SHADOW &&
 122             IS_ALIGNED(addr, PGDIR_SIZE) && end - addr >= PGDIR_SIZE) {
 123                 pgd_populate(&init_mm, pgd, kasan_early_shadow_p4d);
 124                 return true;
 125         }
 126         return false;
 127 }
 128
 129 static bool kasan_p4d_populate_zero_shadow(p4d_t *p4d, unsigned long addr,
 130                                            unsigned long end, enum populate_mode mode)
 131 {
 132         if (mode == POPULATE_KASAN_ZERO_SHADOW &&
 133             IS_ALIGNED(addr, P4D_SIZE) && end - addr >= P4D_SIZE) {
 134                 p4d_populate(&init_mm, p4d, kasan_early_shadow_pud);
 135                 return true;
 136         }
 137         return false;
 138 }
 139
 140 static bool kasan_pud_populate_zero_shadow(pud_t *pud, unsigned long addr,
 141                                            unsigned long end, enum populate_mode mode)
 142 {
 143         if (mode == POPULATE_KASAN_ZERO_SHADOW &&
 144             IS_ALIGNED(addr, PUD_SIZE) && end - addr >= PUD_SIZE) {
 145                 pud_populate(&init_mm, pud, kasan_early_shadow_pmd);
 146                 return true;
 147         }
 148         return false;
 149 }
 150
 151 static bool kasan_pmd_populate_zero_shadow(pmd_t *pmd, unsigned long addr,
 152                                            unsigned long end, enum populate_mode mode)
 153 {
 154         if (mode == POPULATE_KASAN_ZERO_SHADOW &&
 155             IS_ALIGNED(addr, PMD_SIZE) && end - addr >= PMD_SIZE) {
 156                 pmd_populate(&init_mm, pmd, kasan_early_shadow_pte);
 157                 return true;
 158         }
 159         return false;
 160 }
 161
 162 static bool kasan_pte_populate_zero_shadow(pte_t *pte, enum populate_mode mode)
 163 {
 164         pte_t entry;
 165
 166         if (mode == POPULATE_KASAN_ZERO_SHADOW) {
 167                 set_pte(pte, pte_z);
 168                 return true;
 169         }
 170         return false;
 171 }
 172 #else
 173
 174 static inline void kasan_populate_shadow(void) {}
 175
 176 static inline bool kasan_pgd_populate_zero_shadow(pgd_t *pgd, unsigned long addr,
 177                                                   unsigned long end, enum populate_mode mode)
 178 {
 179         return false;
 180 }
 181
 182 static inline bool kasan_p4d_populate_zero_shadow(p4d_t *p4d, unsigned long addr,
 183                                                   unsigned long end, enum populate_mode mode)
 184 {
 185         return false;
 186 }
 187
 188 static inline bool kasan_pud_populate_zero_shadow(pud_t *pud, unsigned long addr,
 189                                                   unsigned long end, enum populate_mode mode)
 190 {
 191         return false;
 192 }
 193
 194 static inline bool kasan_pmd_populate_zero_shadow(pmd_t *pmd, unsigned long addr,
 195                                                   unsigned long end, enum populate_mode mode)
 196 {
 197         return false;
 198 }
 199
 200 static bool kasan_pte_populate_zero_shadow(pte_t *pte, enum populate_mode mode)
 201 {
 202         return false;
 203 }
 204
 205 #endif
 206
 207 /*
 208  * Mimic virt_to_kpte() in lack of init_mm symbol. Skip pmd NULL check though.
 209  */
 210 static inline pte_t *__virt_to_kpte(unsigned long va)
 211 {
 212         return pte_offset_kernel(pmd_offset(pud_offset(p4d_offset(pgd_offset_k(va), va), va), va), va);
 213 }
 214
 215 static void *boot_crst_alloc(unsigned long val)
 216 {
 217         unsigned long size = PAGE_SIZE << CRST_ALLOC_ORDER;
 218         unsigned long *table;
 219
 220         table = (unsigned long *)physmem_alloc_top_down(RR_VMEM, size, size);
 221         crst_table_init(table, val);
 222         return table;
 223 }
 224
 225 static pte_t *boot_pte_alloc(void)
 226 {
 227         static void *pte_leftover;
 228         pte_t *pte;
 229
 230         /*
 231          * handling pte_leftovers this way helps to avoid memory fragmentation
 232          * during POPULATE_KASAN_MAP_SHADOW when EDAT is off
 233          */
 234         if (!pte_leftover) {
 235                 pte_leftover = (void *)physmem_alloc_top_down(RR_VMEM, PAGE_SIZE, PAGE_SIZE);
 236                 pte = pte_leftover + _PAGE_TABLE_SIZE;
 237         } else {
 238                 pte = pte_leftover;
 239                 pte_leftover = NULL;
 240         }
 241
 242         memset64((u64 *)pte, _PAGE_INVALID, PTRS_PER_PTE);
 243         return pte;
 244 }
 245
 246 static unsigned long _pa(unsigned long addr, unsigned long size, enum populate_mode mode)
 247 {
 248         switch (mode) {
 249         case POPULATE_NONE:
 250                 return -1;
 251         case POPULATE_DIRECT:
 252                 return addr;
 253         case POPULATE_ABS_LOWCORE:
 254                 return __abs_lowcore_pa(addr);
 255 #ifdef CONFIG_KASAN
 256         case POPULATE_KASAN_MAP_SHADOW:
 257                 addr = physmem_alloc_top_down(RR_VMEM, size, size);
 258                 memset((void *)addr, 0, size);
 259                 return addr;
 260 #endif
 261         default:
 262                 return -1;
 263         }
 264 }
 265
 266 static bool can_large_pud(pud_t *pu_dir, unsigned long addr, unsigned long end)
 267 {
 268         return machine.has_edat2 &&
 269                IS_ALIGNED(addr, PUD_SIZE) && (end - addr) >= PUD_SIZE;
 270 }
 271
 272 static bool can_large_pmd(pmd_t *pm_dir, unsigned long addr, unsigned long end)
 273 {
 274         return machine.has_edat1 &&
 275                IS_ALIGNED(addr, PMD_SIZE) && (end - addr) >= PMD_SIZE;
 276 }
 277
 278 static void pgtable_pte_populate(pmd_t *pmd, unsigned long addr, unsigned long end,
 279                                  enum populate_mode mode)
 280 {
 281         unsigned long pages = 0;
 282         pte_t *pte, entry;
 283
 284         pte = pte_offset_kernel(pmd, addr);
 285         for (; addr < end; addr += PAGE_SIZE, pte++) {
 286                 if (pte_none(*pte)) {
 287                         if (kasan_pte_populate_zero_shadow(pte, mode))
 288                                 continue;
 289                         entry = __pte(_pa(addr, PAGE_SIZE, mode));
 290                         entry = set_pte_bit(entry, PAGE_KERNEL);
 291                         if (!machine.has_nx)
 292                                 entry = clear_pte_bit(entry, __pgprot(_PAGE_NOEXEC));
 293                         set_pte(pte, entry);
 294                         pages++;
 295                 }
 296         }
 297         if (mode == POPULATE_DIRECT)
 298                 update_page_count(PG_DIRECT_MAP_4K, pages);
 299 }
 300
 301 static void pgtable_pmd_populate(pud_t *pud, unsigned long addr, unsigned long end,
 302                                  enum populate_mode mode)
 303 {
 304         unsigned long next, pages = 0;
 305         pmd_t *pmd, entry;
 306         pte_t *pte;
 307
 308         pmd = pmd_offset(pud, addr);
 309         for (; addr < end; addr = next, pmd++) {
 310                 next = pmd_addr_end(addr, end);
 311                 if (pmd_none(*pmd)) {
 312                         if (kasan_pmd_populate_zero_shadow(pmd, addr, next, mode))
 313                                 continue;
 314                         if (can_large_pmd(pmd, addr, next)) {
 315                                 entry = __pmd(_pa(addr, _SEGMENT_SIZE, mode));
 316                                 entry = set_pmd_bit(entry, SEGMENT_KERNEL);
 317                                 if (!machine.has_nx)
 318                                         entry = clear_pmd_bit(entry, __pgprot(_SEGMENT_ENTRY_NOEXEC));
 319                                 set_pmd(pmd, entry);
 320                                 pages++;
 321                                 continue;
 322                         }
 323                         pte = boot_pte_alloc();
 324                         pmd_populate(&init_mm, pmd, pte);
 325                 } else if (pmd_large(*pmd)) {
 326                         continue;
 327                 }
 328                 pgtable_pte_populate(pmd, addr, next, mode);
 329         }
 330         if (mode == POPULATE_DIRECT)
 331                 update_page_count(PG_DIRECT_MAP_1M, pages);
 332 }
 333
 334 static void pgtable_pud_populate(p4d_t *p4d, unsigned long addr, unsigned long end,
 335                                  enum populate_mode mode)
 336 {
 337         unsigned long next, pages = 0;
 338         pud_t *pud, entry;
 339         pmd_t *pmd;
 340
 341         pud = pud_offset(p4d, addr);
 342         for (; addr < end; addr = next, pud++) {
 343                 next = pud_addr_end(addr, end);
 344                 if (pud_none(*pud)) {
 345                         if (kasan_pud_populate_zero_shadow(pud, addr, next, mode))
 346                                 continue;
 347                         if (can_large_pud(pud, addr, next)) {
 348                                 entry = __pud(_pa(addr, _REGION3_SIZE, mode));
 349                                 entry = set_pud_bit(entry, REGION3_KERNEL);
 350                                 if (!machine.has_nx)
 351                                         entry = clear_pud_bit(entry, __pgprot(_REGION_ENTRY_NOEXEC));
 352                                 set_pud(pud, entry);
 353                                 pages++;
 354                                 continue;
 355                         }
 356                         pmd = boot_crst_alloc(_SEGMENT_ENTRY_EMPTY);
 357                         pud_populate(&init_mm, pud, pmd);
 358                 } else if (pud_large(*pud)) {
 359                         continue;
 360                 }
 361                 pgtable_pmd_populate(pud, addr, next, mode);
 362         }
 363         if (mode == POPULATE_DIRECT)
 364                 update_page_count(PG_DIRECT_MAP_2G, pages);
 365 }
 366
 367 static void pgtable_p4d_populate(pgd_t *pgd, unsigned long addr, unsigned long end,
 368                                  enum populate_mode mode)
 369 {
 370         unsigned long next;
 371         p4d_t *p4d;
 372         pud_t *pud;
 373
 374         p4d = p4d_offset(pgd, addr);
 375         for (; addr < end; addr = next, p4d++) {
 376                 next = p4d_addr_end(addr, end);
 377                 if (p4d_none(*p4d)) {
 378                         if (kasan_p4d_populate_zero_shadow(p4d, addr, next, mode))
 379                                 continue;
 380                         pud = boot_crst_alloc(_REGION3_ENTRY_EMPTY);
 381                         p4d_populate(&init_mm, p4d, pud);
 382                 }
 383                 pgtable_pud_populate(p4d, addr, next, mode);
 384         }
 385 }
 386
 387 static void pgtable_populate(unsigned long addr, unsigned long end, enum populate_mode mode)
 388 {
 389         unsigned long next;
 390         pgd_t *pgd;
 391         p4d_t *p4d;
 392
 393         pgd = pgd_offset(&init_mm, addr);
 394         for (; addr < end; addr = next, pgd++) {
 395                 next = pgd_addr_end(addr, end);
 396                 if (pgd_none(*pgd)) {
 397                         if (kasan_pgd_populate_zero_shadow(pgd, addr, next, mode))
 398                                 continue;
 399                         p4d = boot_crst_alloc(_REGION2_ENTRY_EMPTY);
 400                         pgd_populate(&init_mm, pgd, p4d);
 401                 }
 402 #ifdef CONFIG_KASAN
 403                 if (mode == POPULATE_KASAN_SHALLOW)
 404                         continue;
 405 #endif
 406                 pgtable_p4d_populate(pgd, addr, next, mode);
 407         }
 408 }
 409
 410 void setup_vmem(unsigned long asce_limit)
 411 {
 412         unsigned long start, end;
 413         unsigned long asce_type;
 414         unsigned long asce_bits;
 415         int i;
 416
 417         if (asce_limit == _REGION1_SIZE) {
 418                 asce_type = _REGION2_ENTRY_EMPTY;
 419                 asce_bits = _ASCE_TYPE_REGION2 | _ASCE_TABLE_LENGTH;
 420         } else {
 421                 asce_type = _REGION3_ENTRY_EMPTY;
 422                 asce_bits = _ASCE_TYPE_REGION3 | _ASCE_TABLE_LENGTH;
 423         }
 424         s390_invalid_asce = invalid_pg_dir | _ASCE_TYPE_REGION3 | _ASCE_TABLE_LENGTH;
 425
 426         crst_table_init((unsigned long *)swapper_pg_dir, asce_type);
 427         crst_table_init((unsigned long *)invalid_pg_dir, _REGION3_ENTRY_EMPTY);
 428
 429         /*
 430          * To allow prefixing the lowcore must be mapped with 4KB pages.
 431          * To prevent creation of a large page at address 0 first map
 432          * the lowcore and create the identity mapping only afterwards.
 433          */
 434         pgtable_populate(0, sizeof(struct lowcore), POPULATE_DIRECT);
 435         for_each_physmem_usable_range(i, &start, &end)
 436                 pgtable_populate(start, end, POPULATE_DIRECT);
 437         pgtable_populate(__abs_lowcore, __abs_lowcore + sizeof(struct lowcore),
 438                          POPULATE_ABS_LOWCORE);
 439         pgtable_populate(__memcpy_real_area, __memcpy_real_area + PAGE_SIZE,
 440                          POPULATE_NONE);
 441         memcpy_real_ptep = __virt_to_kpte(__memcpy_real_area);
 442
 443         kasan_populate_shadow();
 444
 445         S390_lowcore.kernel_asce = swapper_pg_dir | asce_bits;
 446         S390_lowcore.user_asce = s390_invalid_asce;
 447
 448         __ctl_load(S390_lowcore.kernel_asce, 1, 1);
 449         __ctl_load(S390_lowcore.user_asce, 7, 7);
 450         __ctl_load(S390_lowcore.kernel_asce, 13, 13);
 451
 452         init_mm.context.asce = S390_lowcore.kernel_asce;
 453 }