arch/s390/mm/vmem.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *    Copyright IBM Corp. 2006
   4  *    Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
   5  */
   6
   7 #include <linux/memory_hotplug.h>
   8 #include <linux/memblock.h>
   9 #include <linux/pfn.h>
  10 #include <linux/mm.h>
  11 #include <linux/init.h>
  12 #include <linux/list.h>
  13 #include <linux/hugetlb.h>
  14 #include <linux/slab.h>
  15 #include <asm/cacheflush.h>
  16 #include <asm/pgalloc.h>
  17 #include <asm/setup.h>
  18 #include <asm/tlbflush.h>
  19 #include <asm/sections.h>
  20 #include <asm/set_memory.h>
  21
  22 static DEFINE_MUTEX(vmem_mutex);
  23
  24 static void __ref *vmem_alloc_pages(unsigned int order)
  25 {
  26         unsigned long size = PAGE_SIZE << order;
  27
  28         if (slab_is_available())
  29                 return (void *)__get_free_pages(GFP_KERNEL, order);
  30         return memblock_alloc(size, size);
  31 }
  32
  33 static void vmem_free_pages(unsigned long addr, int order)
  34 {
  35         /* We don't expect boot memory to be removed ever. */
  36         if (!slab_is_available() ||
  37             WARN_ON_ONCE(PageReserved(virt_to_page(addr))))
  38                 return;
  39         free_pages(addr, order);
  40 }
  41
  42 void *vmem_crst_alloc(unsigned long val)
  43 {
  44         unsigned long *table;
  45
  46         table = vmem_alloc_pages(CRST_ALLOC_ORDER);
  47         if (table)
  48                 crst_table_init(table, val);
  49         return table;
  50 }
  51
  52 pte_t __ref *vmem_pte_alloc(void)
  53 {
  54         unsigned long size = PTRS_PER_PTE * sizeof(pte_t);
  55         pte_t *pte;
  56
  57         if (slab_is_available())
  58                 pte = (pte_t *) page_table_alloc(&init_mm);
  59         else
  60                 pte = (pte_t *) memblock_alloc(size, size);
  61         if (!pte)
  62                 return NULL;
  63         memset64((u64 *)pte, _PAGE_INVALID, PTRS_PER_PTE);
  64         return pte;
  65 }
  66
  67 static void vmem_pte_free(unsigned long *table)
  68 {
  69         /* We don't expect boot memory to be removed ever. */
  70         if (!slab_is_available() ||
  71             WARN_ON_ONCE(PageReserved(virt_to_page(table))))
  72                 return;
  73         page_table_free(&init_mm, table);
  74 }
  75
  76 #define PAGE_UNUSED 0xFD
  77
  78 /*
  79  * The unused vmemmap range, which was not yet memset(PAGE_UNUSED) ranges
  80  * from unused_sub_pmd_start to next PMD_SIZE boundary.
  81  */
  82 static unsigned long unused_sub_pmd_start;
  83
  84 static void vmemmap_flush_unused_sub_pmd(void)
  85 {
  86         if (!unused_sub_pmd_start)
  87                 return;
  88         memset((void *)unused_sub_pmd_start, PAGE_UNUSED,
  89                ALIGN(unused_sub_pmd_start, PMD_SIZE) - unused_sub_pmd_start);
  90         unused_sub_pmd_start = 0;
  91 }
  92
  93 static void vmemmap_mark_sub_pmd_used(unsigned long start, unsigned long end)
  94 {
  95         /*
  96          * As we expect to add in the same granularity as we remove, it's
  97          * sufficient to mark only some piece used to block the memmap page from
  98          * getting removed (just in case the memmap never gets initialized,
  99          * e.g., because the memory block never gets onlined).
 100          */
 101         memset((void *)start, 0, sizeof(struct page));
 102 }
 103
 104 static void vmemmap_use_sub_pmd(unsigned long start, unsigned long end)
 105 {
 106         /*
 107          * We only optimize if the new used range directly follows the
 108          * previously unused range (esp., when populating consecutive sections).
 109          */
 110         if (unused_sub_pmd_start == start) {
 111                 unused_sub_pmd_start = end;
 112                 if (likely(IS_ALIGNED(unused_sub_pmd_start, PMD_SIZE)))
 113                         unused_sub_pmd_start = 0;
 114                 return;
 115         }
 116         vmemmap_flush_unused_sub_pmd();
 117         vmemmap_mark_sub_pmd_used(start, end);
 118 }
 119
 120 static void vmemmap_use_new_sub_pmd(unsigned long start, unsigned long end)
 121 {
 122         unsigned long page = ALIGN_DOWN(start, PMD_SIZE);
 123
 124         vmemmap_flush_unused_sub_pmd();
 125
 126         /* Could be our memmap page is filled with PAGE_UNUSED already ... */
 127         vmemmap_mark_sub_pmd_used(start, end);
 128
 129         /* Mark the unused parts of the new memmap page PAGE_UNUSED. */
 130         if (!IS_ALIGNED(start, PMD_SIZE))
 131                 memset((void *)page, PAGE_UNUSED, start - page);
 132         /*
 133          * We want to avoid memset(PAGE_UNUSED) when populating the vmemmap of
 134          * consecutive sections. Remember for the last added PMD the last
 135          * unused range in the populated PMD.
 136          */
 137         if (!IS_ALIGNED(end, PMD_SIZE))
 138                 unused_sub_pmd_start = end;
 139 }
 140
 141 /* Returns true if the PMD is completely unused and can be freed. */
 142 static bool vmemmap_unuse_sub_pmd(unsigned long start, unsigned long end)
 143 {
 144         unsigned long page = ALIGN_DOWN(start, PMD_SIZE);
 145
 146         vmemmap_flush_unused_sub_pmd();
 147         memset((void *)start, PAGE_UNUSED, end - start);
 148         return !memchr_inv((void *)page, PAGE_UNUSED, PMD_SIZE);
 149 }
 150
 151 /* __ref: we'll only call vmemmap_alloc_block() via vmemmap_populate() */
 152 static int __ref modify_pte_table(pmd_t *pmd, unsigned long addr,
 153                                   unsigned long end, bool add, bool direct)
 154 {
 155         unsigned long prot, pages = 0;
 156         int ret = -ENOMEM;
 157         pte_t *pte;
 158
 159         prot = pgprot_val(PAGE_KERNEL);
 160         if (!MACHINE_HAS_NX)
 161                 prot &= ~_PAGE_NOEXEC;
 162
 163         pte = pte_offset_kernel(pmd, addr);
 164         for (; addr < end; addr += PAGE_SIZE, pte++) {
 165                 if (!add) {
 166                         if (pte_none(*pte))
 167                                 continue;
 168                         if (!direct)
 169                                 vmem_free_pages((unsigned long) pfn_to_virt(pte_pfn(*pte)), 0);
 170                         pte_clear(&init_mm, addr, pte);
 171                 } else if (pte_none(*pte)) {
 172                         if (!direct) {
 173                                 void *new_page = vmemmap_alloc_block(PAGE_SIZE, NUMA_NO_NODE);
 174
 175                                 if (!new_page)
 176                                         goto out;
 177                                 pte_val(*pte) = __pa(new_page) | prot;
 178                         } else {
 179                                 pte_val(*pte) = __pa(addr) | prot;
 180                         }
 181                 } else {
 182                         continue;
 183                 }
 184                 pages++;
 185         }
 186         ret = 0;
 187 out:
 188         if (direct)
 189                 update_page_count(PG_DIRECT_MAP_4K, add ? pages : -pages);
 190         return ret;
 191 }
 192
 193 static void try_free_pte_table(pmd_t *pmd, unsigned long start)
 194 {
 195         pte_t *pte;
 196         int i;
 197
 198         /* We can safely assume this is fully in 1:1 mapping & vmemmap area */
 199         pte = pte_offset_kernel(pmd, start);
 200         for (i = 0; i < PTRS_PER_PTE; i++, pte++) {
 201                 if (!pte_none(*pte))
 202                         return;
 203         }
 204         vmem_pte_free((unsigned long *) pmd_deref(*pmd));
 205         pmd_clear(pmd);
 206 }
 207
 208 /* __ref: we'll only call vmemmap_alloc_block() via vmemmap_populate() */
 209 static int __ref modify_pmd_table(pud_t *pud, unsigned long addr,
 210                                   unsigned long end, bool add, bool direct)
 211 {
 212         unsigned long next, prot, pages = 0;
 213         int ret = -ENOMEM;
 214         pmd_t *pmd;
 215         pte_t *pte;
 216
 217         prot = pgprot_val(SEGMENT_KERNEL);
 218         if (!MACHINE_HAS_NX)
 219                 prot &= ~_SEGMENT_ENTRY_NOEXEC;
 220
 221         pmd = pmd_offset(pud, addr);
 222         for (; addr < end; addr = next, pmd++) {
 223                 next = pmd_addr_end(addr, end);
 224                 if (!add) {
 225                         if (pmd_none(*pmd))
 226                                 continue;
 227                         if (pmd_large(*pmd)) {
 228                                 if (IS_ALIGNED(addr, PMD_SIZE) &&
 229                                     IS_ALIGNED(next, PMD_SIZE)) {
 230                                         if (!direct)
 231                                                 vmem_free_pages(pmd_deref(*pmd), get_order(PMD_SIZE));
 232                                         pmd_clear(pmd);
 233                                         pages++;
 234                                 } else if (!direct && vmemmap_unuse_sub_pmd(addr, next)) {
 235                                         vmem_free_pages(pmd_deref(*pmd), get_order(PMD_SIZE));
 236                                         pmd_clear(pmd);
 237                                 }
 238                                 continue;
 239                         }
 240                 } else if (pmd_none(*pmd)) {
 241                         if (IS_ALIGNED(addr, PMD_SIZE) &&
 242                             IS_ALIGNED(next, PMD_SIZE) &&
 243                             MACHINE_HAS_EDAT1 && addr && direct &&
 244                             !debug_pagealloc_enabled()) {
 245                                 pmd_val(*pmd) = __pa(addr) | prot;
 246                                 pages++;
 247                                 continue;
 248                         } else if (!direct && MACHINE_HAS_EDAT1) {
 249                                 void *new_page;
 250
 251                                 /*
 252                                  * Use 1MB frames for vmemmap if available. We
 253                                  * always use large frames even if they are only
 254                                  * partially used. Otherwise we would have also
 255                                  * page tables since vmemmap_populate gets
 256                                  * called for each section separately.
 257                                  */
 258                                 new_page = vmemmap_alloc_block(PMD_SIZE, NUMA_NO_NODE);
 259                                 if (new_page) {
 260                                         pmd_val(*pmd) = __pa(new_page) | prot;
 261                                         if (!IS_ALIGNED(addr, PMD_SIZE) ||
 262                                             !IS_ALIGNED(next, PMD_SIZE)) {
 263                                                 vmemmap_use_new_sub_pmd(addr, next);
 264                                         }
 265                                         continue;
 266                                 }
 267                         }
 268                         pte = vmem_pte_alloc();
 269                         if (!pte)
 270                                 goto out;
 271                         pmd_populate(&init_mm, pmd, pte);
 272                 } else if (pmd_large(*pmd)) {
 273                         if (!direct)
 274                                 vmemmap_use_sub_pmd(addr, next);
 275                         continue;
 276                 }
 277                 ret = modify_pte_table(pmd, addr, next, add, direct);
 278                 if (ret)
 279                         goto out;
 280                 if (!add)
 281                         try_free_pte_table(pmd, addr & PMD_MASK);
 282         }
 283         ret = 0;
 284 out:
 285         if (direct)
 286                 update_page_count(PG_DIRECT_MAP_1M, add ? pages : -pages);
 287         return ret;
 288 }
 289
 290 static void try_free_pmd_table(pud_t *pud, unsigned long start)
 291 {
 292         const unsigned long end = start + PUD_SIZE;
 293         pmd_t *pmd;
 294         int i;
 295
 296         /* Don't mess with any tables not fully in 1:1 mapping & vmemmap area */
 297         if (end > VMALLOC_START)
 298                 return;
 299 #ifdef CONFIG_KASAN
 300         if (start < KASAN_SHADOW_END && KASAN_SHADOW_START > end)
 301                 return;
 302 #endif
 303         pmd = pmd_offset(pud, start);
 304         for (i = 0; i < PTRS_PER_PMD; i++, pmd++)
 305                 if (!pmd_none(*pmd))
 306                         return;
 307         vmem_free_pages(pud_deref(*pud), CRST_ALLOC_ORDER);
 308         pud_clear(pud);
 309 }
 310
 311 static int modify_pud_table(p4d_t *p4d, unsigned long addr, unsigned long end,
 312                             bool add, bool direct)
 313 {
 314         unsigned long next, prot, pages = 0;
 315         int ret = -ENOMEM;
 316         pud_t *pud;
 317         pmd_t *pmd;
 318
 319         prot = pgprot_val(REGION3_KERNEL);
 320         if (!MACHINE_HAS_NX)
 321                 prot &= ~_REGION_ENTRY_NOEXEC;
 322         pud = pud_offset(p4d, addr);
 323         for (; addr < end; addr = next, pud++) {
 324                 next = pud_addr_end(addr, end);
 325                 if (!add) {
 326                         if (pud_none(*pud))
 327                                 continue;
 328                         if (pud_large(*pud)) {
 329                                 if (IS_ALIGNED(addr, PUD_SIZE) &&
 330                                     IS_ALIGNED(next, PUD_SIZE)) {
 331                                         pud_clear(pud);
 332                                         pages++;
 333                                 }
 334                                 continue;
 335                         }
 336                 } else if (pud_none(*pud)) {
 337                         if (IS_ALIGNED(addr, PUD_SIZE) &&
 338                             IS_ALIGNED(next, PUD_SIZE) &&
 339                             MACHINE_HAS_EDAT2 && addr && direct &&
 340                             !debug_pagealloc_enabled()) {
 341                                 pud_val(*pud) = __pa(addr) | prot;
 342                                 pages++;
 343                                 continue;
 344                         }
 345                         pmd = vmem_crst_alloc(_SEGMENT_ENTRY_EMPTY);
 346                         if (!pmd)
 347                                 goto out;
 348                         pud_populate(&init_mm, pud, pmd);
 349                 } else if (pud_large(*pud)) {
 350                         continue;
 351                 }
 352                 ret = modify_pmd_table(pud, addr, next, add, direct);
 353                 if (ret)
 354                         goto out;
 355                 if (!add)
 356                         try_free_pmd_table(pud, addr & PUD_MASK);
 357         }
 358         ret = 0;
 359 out:
 360         if (direct)
 361                 update_page_count(PG_DIRECT_MAP_2G, add ? pages : -pages);
 362         return ret;
 363 }
 364
 365 static void try_free_pud_table(p4d_t *p4d, unsigned long start)
 366 {
 367         const unsigned long end = start + P4D_SIZE;
 368         pud_t *pud;
 369         int i;
 370
 371         /* Don't mess with any tables not fully in 1:1 mapping & vmemmap area */
 372         if (end > VMALLOC_START)
 373                 return;
 374 #ifdef CONFIG_KASAN
 375         if (start < KASAN_SHADOW_END && KASAN_SHADOW_START > end)
 376                 return;
 377 #endif
 378
 379         pud = pud_offset(p4d, start);
 380         for (i = 0; i < PTRS_PER_PUD; i++, pud++) {
 381                 if (!pud_none(*pud))
 382                         return;
 383         }
 384         vmem_free_pages(p4d_deref(*p4d), CRST_ALLOC_ORDER);
 385         p4d_clear(p4d);
 386 }
 387
 388 static int modify_p4d_table(pgd_t *pgd, unsigned long addr, unsigned long end,
 389                             bool add, bool direct)
 390 {
 391         unsigned long next;
 392         int ret = -ENOMEM;
 393         p4d_t *p4d;
 394         pud_t *pud;
 395
 396         p4d = p4d_offset(pgd, addr);
 397         for (; addr < end; addr = next, p4d++) {
 398                 next = p4d_addr_end(addr, end);
 399                 if (!add) {
 400                         if (p4d_none(*p4d))
 401                                 continue;
 402                 } else if (p4d_none(*p4d)) {
 403                         pud = vmem_crst_alloc(_REGION3_ENTRY_EMPTY);
 404                         if (!pud)
 405                                 goto out;
 406                         p4d_populate(&init_mm, p4d, pud);
 407                 }
 408                 ret = modify_pud_table(p4d, addr, next, add, direct);
 409                 if (ret)
 410                         goto out;
 411                 if (!add)
 412                         try_free_pud_table(p4d, addr & P4D_MASK);
 413         }
 414         ret = 0;
 415 out:
 416         return ret;
 417 }
 418
 419 static void try_free_p4d_table(pgd_t *pgd, unsigned long start)
 420 {
 421         const unsigned long end = start + PGDIR_SIZE;
 422         p4d_t *p4d;
 423         int i;
 424
 425         /* Don't mess with any tables not fully in 1:1 mapping & vmemmap area */
 426         if (end > VMALLOC_START)
 427                 return;
 428 #ifdef CONFIG_KASAN
 429         if (start < KASAN_SHADOW_END && KASAN_SHADOW_START > end)
 430                 return;
 431 #endif
 432
 433         p4d = p4d_offset(pgd, start);
 434         for (i = 0; i < PTRS_PER_P4D; i++, p4d++) {
 435                 if (!p4d_none(*p4d))
 436                         return;
 437         }
 438         vmem_free_pages(pgd_deref(*pgd), CRST_ALLOC_ORDER);
 439         pgd_clear(pgd);
 440 }
 441
 442 static int modify_pagetable(unsigned long start, unsigned long end, bool add,
 443                             bool direct)
 444 {
 445         unsigned long addr, next;
 446         int ret = -ENOMEM;
 447         pgd_t *pgd;
 448         p4d_t *p4d;
 449
 450         if (WARN_ON_ONCE(!PAGE_ALIGNED(start | end)))
 451                 return -EINVAL;
 452         for (addr = start; addr < end; addr = next) {
 453                 next = pgd_addr_end(addr, end);
 454                 pgd = pgd_offset_k(addr);
 455
 456                 if (!add) {
 457                         if (pgd_none(*pgd))
 458                                 continue;
 459                 } else if (pgd_none(*pgd)) {
 460                         p4d = vmem_crst_alloc(_REGION2_ENTRY_EMPTY);
 461                         if (!p4d)
 462                                 goto out;
 463                         pgd_populate(&init_mm, pgd, p4d);
 464                 }
 465                 ret = modify_p4d_table(pgd, addr, next, add, direct);
 466                 if (ret)
 467                         goto out;
 468                 if (!add)
 469                         try_free_p4d_table(pgd, addr & PGDIR_MASK);
 470         }
 471         ret = 0;
 472 out:
 473         if (!add)
 474                 flush_tlb_kernel_range(start, end);
 475         return ret;
 476 }
 477
 478 static int add_pagetable(unsigned long start, unsigned long end, bool direct)
 479 {
 480         return modify_pagetable(start, end, true, direct);
 481 }
 482
 483 static int remove_pagetable(unsigned long start, unsigned long end, bool direct)
 484 {
 485         return modify_pagetable(start, end, false, direct);
 486 }
 487
 488 /*
 489  * Add a physical memory range to the 1:1 mapping.
 490  */
 491 static int vmem_add_range(unsigned long start, unsigned long size)
 492 {
 493         return add_pagetable(start, start + size, true);
 494 }
 495
 496 /*
 497  * Remove a physical memory range from the 1:1 mapping.
 498  */
 499 static void vmem_remove_range(unsigned long start, unsigned long size)
 500 {
 501         remove_pagetable(start, start + size, true);
 502 }
 503
 504 /*
 505  * Add a backed mem_map array to the virtual mem_map array.
 506  */
 507 int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
 508                                struct vmem_altmap *altmap)
 509 {
 510         int ret;
 511
 512         mutex_lock(&vmem_mutex);
 513         /* We don't care about the node, just use NUMA_NO_NODE on allocations */
 514         ret = add_pagetable(start, end, false);
 515         if (ret)
 516                 remove_pagetable(start, end, false);
 517         mutex_unlock(&vmem_mutex);
 518         return ret;
 519 }
 520
 521 void vmemmap_free(unsigned long start, unsigned long end,
 522                   struct vmem_altmap *altmap)
 523 {
 524         mutex_lock(&vmem_mutex);
 525         remove_pagetable(start, end, false);
 526         mutex_unlock(&vmem_mutex);
 527 }
 528
 529 void vmem_remove_mapping(unsigned long start, unsigned long size)
 530 {
 531         mutex_lock(&vmem_mutex);
 532         vmem_remove_range(start, size);
 533         mutex_unlock(&vmem_mutex);
 534 }
 535
 536 struct range arch_get_mappable_range(void)
 537 {
 538         struct range mhp_range;
 539
 540         mhp_range.start = 0;
 541         mhp_range.end =  VMEM_MAX_PHYS - 1;
 542         return mhp_range;
 543 }
 544
 545 int vmem_add_mapping(unsigned long start, unsigned long size)
 546 {
 547         struct range range = arch_get_mappable_range();
 548         int ret;
 549
 550         if (start < range.start ||
 551             start + size > range.end + 1 ||
 552             start + size < start)
 553                 return -ERANGE;
 554
 555         mutex_lock(&vmem_mutex);
 556         ret = vmem_add_range(start, size);
 557         if (ret)
 558                 vmem_remove_range(start, size);
 559         mutex_unlock(&vmem_mutex);
 560         return ret;
 561 }
 562
 563 /*
 564  * map whole physical memory to virtual memory (identity mapping)
 565  * we reserve enough space in the vmalloc area for vmemmap to hotplug
 566  * additional memory segments.
 567  */
 568 void __init vmem_map_init(void)
 569 {
 570         phys_addr_t base, end;
 571         u64 i;
 572
 573         for_each_mem_range(i, &base, &end)
 574                 vmem_add_range(base, end - base);
 575         __set_memory((unsigned long)_stext,
 576                      (unsigned long)(_etext - _stext) >> PAGE_SHIFT,
 577                      SET_MEMORY_RO | SET_MEMORY_X);
 578         __set_memory((unsigned long)_etext,
 579                      (unsigned long)(__end_rodata - _etext) >> PAGE_SHIFT,
 580                      SET_MEMORY_RO);
 581         __set_memory((unsigned long)_sinittext,
 582                      (unsigned long)(_einittext - _sinittext) >> PAGE_SHIFT,
 583                      SET_MEMORY_RO | SET_MEMORY_X);
 584         __set_memory(__stext_amode31, (__etext_amode31 - __stext_amode31) >> PAGE_SHIFT,
 585                      SET_MEMORY_RO | SET_MEMORY_X);
 586
 587         /* we need lowcore executable for our LPSWE instructions */
 588         set_memory_x(0, 1);
 589
 590         pr_info("Write protected kernel read-only data: %luk\n",
 591                 (unsigned long)(__end_rodata - _stext) >> 10);
 592 }