arch/s390/mm/vmem.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *    Copyright IBM Corp. 2006
   4  */
   5
   6 #include <linux/memory_hotplug.h>
   7 #include <linux/memblock.h>
   8 #include <linux/pfn.h>
   9 #include <linux/mm.h>
  10 #include <linux/init.h>
  11 #include <linux/list.h>
  12 #include <linux/hugetlb.h>
  13 #include <linux/slab.h>
  14 #include <linux/sort.h>
  15 #include <asm/page-states.h>
  16 #include <asm/abs_lowcore.h>
  17 #include <asm/cacheflush.h>
  18 #include <asm/maccess.h>
  19 #include <asm/nospec-branch.h>
  20 #include <asm/ctlreg.h>
  21 #include <asm/pgalloc.h>
  22 #include <asm/setup.h>
  23 #include <asm/tlbflush.h>
  24 #include <asm/sections.h>
  25 #include <asm/set_memory.h>
  26 #include <asm/physmem_info.h>
  27
  28 static DEFINE_MUTEX(vmem_mutex);
  29
  30 static void __ref *vmem_alloc_pages(unsigned int order)
  31 {
  32         unsigned long size = PAGE_SIZE << order;
  33
  34         if (slab_is_available())
  35                 return (void *)__get_free_pages(GFP_KERNEL, order);
  36         return memblock_alloc(size, size);
  37 }
  38
  39 static void vmem_free_pages(unsigned long addr, int order, struct vmem_altmap *altmap)
  40 {
  41         if (altmap) {
  42                 vmem_altmap_free(altmap, 1 << order);
  43                 return;
  44         }
  45         /* We don't expect boot memory to be removed ever. */
  46         if (!slab_is_available() ||
  47             WARN_ON_ONCE(PageReserved(virt_to_page((void *)addr))))
  48                 return;
  49         free_pages(addr, order);
  50 }
  51
  52 void *vmem_crst_alloc(unsigned long val)
  53 {
  54         unsigned long *table;
  55
  56         table = vmem_alloc_pages(CRST_ALLOC_ORDER);
  57         if (!table)
  58                 return NULL;
  59         crst_table_init(table, val);
  60         __arch_set_page_dat(table, 1UL << CRST_ALLOC_ORDER);
  61         return table;
  62 }
  63
  64 pte_t __ref *vmem_pte_alloc(void)
  65 {
  66         unsigned long size = PTRS_PER_PTE * sizeof(pte_t);
  67         pte_t *pte;
  68
  69         if (slab_is_available())
  70                 pte = (pte_t *) page_table_alloc(&init_mm);
  71         else
  72                 pte = (pte_t *) memblock_alloc(size, size);
  73         if (!pte)
  74                 return NULL;
  75         memset64((u64 *)pte, _PAGE_INVALID, PTRS_PER_PTE);
  76         __arch_set_page_dat(pte, 1);
  77         return pte;
  78 }
  79
  80 static void vmem_pte_free(unsigned long *table)
  81 {
  82         /* We don't expect boot memory to be removed ever. */
  83         if (!slab_is_available() ||
  84             WARN_ON_ONCE(PageReserved(virt_to_page(table))))
  85                 return;
  86         page_table_free(&init_mm, table);
  87 }
  88
  89 #define PAGE_UNUSED 0xFD
  90
  91 /*
  92  * The unused vmemmap range, which was not yet memset(PAGE_UNUSED) ranges
  93  * from unused_sub_pmd_start to next PMD_SIZE boundary.
  94  */
  95 static unsigned long unused_sub_pmd_start;
  96
  97 static void vmemmap_flush_unused_sub_pmd(void)
  98 {
  99         if (!unused_sub_pmd_start)
 100                 return;
 101         memset((void *)unused_sub_pmd_start, PAGE_UNUSED,
 102                ALIGN(unused_sub_pmd_start, PMD_SIZE) - unused_sub_pmd_start);
 103         unused_sub_pmd_start = 0;
 104 }
 105
 106 static void vmemmap_mark_sub_pmd_used(unsigned long start, unsigned long end)
 107 {
 108         /*
 109          * As we expect to add in the same granularity as we remove, it's
 110          * sufficient to mark only some piece used to block the memmap page from
 111          * getting removed (just in case the memmap never gets initialized,
 112          * e.g., because the memory block never gets onlined).
 113          */
 114         memset((void *)start, 0, sizeof(struct page));
 115 }
 116
 117 static void vmemmap_use_sub_pmd(unsigned long start, unsigned long end)
 118 {
 119         /*
 120          * We only optimize if the new used range directly follows the
 121          * previously unused range (esp., when populating consecutive sections).
 122          */
 123         if (unused_sub_pmd_start == start) {
 124                 unused_sub_pmd_start = end;
 125                 if (likely(IS_ALIGNED(unused_sub_pmd_start, PMD_SIZE)))
 126                         unused_sub_pmd_start = 0;
 127                 return;
 128         }
 129         vmemmap_flush_unused_sub_pmd();
 130         vmemmap_mark_sub_pmd_used(start, end);
 131 }
 132
 133 static void vmemmap_use_new_sub_pmd(unsigned long start, unsigned long end)
 134 {
 135         unsigned long page = ALIGN_DOWN(start, PMD_SIZE);
 136
 137         vmemmap_flush_unused_sub_pmd();
 138
 139         /* Could be our memmap page is filled with PAGE_UNUSED already ... */
 140         vmemmap_mark_sub_pmd_used(start, end);
 141
 142         /* Mark the unused parts of the new memmap page PAGE_UNUSED. */
 143         if (!IS_ALIGNED(start, PMD_SIZE))
 144                 memset((void *)page, PAGE_UNUSED, start - page);
 145         /*
 146          * We want to avoid memset(PAGE_UNUSED) when populating the vmemmap of
 147          * consecutive sections. Remember for the last added PMD the last
 148          * unused range in the populated PMD.
 149          */
 150         if (!IS_ALIGNED(end, PMD_SIZE))
 151                 unused_sub_pmd_start = end;
 152 }
 153
 154 /* Returns true if the PMD is completely unused and can be freed. */
 155 static bool vmemmap_unuse_sub_pmd(unsigned long start, unsigned long end)
 156 {
 157         unsigned long page = ALIGN_DOWN(start, PMD_SIZE);
 158
 159         vmemmap_flush_unused_sub_pmd();
 160         memset((void *)start, PAGE_UNUSED, end - start);
 161         return !memchr_inv((void *)page, PAGE_UNUSED, PMD_SIZE);
 162 }
 163
 164 /* __ref: we'll only call vmemmap_alloc_block() via vmemmap_populate() */
 165 static int __ref modify_pte_table(pmd_t *pmd, unsigned long addr,
 166                                   unsigned long end, bool add, bool direct,
 167                                   struct vmem_altmap *altmap)
 168 {
 169         unsigned long prot, pages = 0;
 170         int ret = -ENOMEM;
 171         pte_t *pte;
 172
 173         prot = pgprot_val(PAGE_KERNEL);
 174         pte = pte_offset_kernel(pmd, addr);
 175         for (; addr < end; addr += PAGE_SIZE, pte++) {
 176                 if (!add) {
 177                         if (pte_none(*pte))
 178                                 continue;
 179                         if (!direct)
 180                                 vmem_free_pages((unsigned long)pfn_to_virt(pte_pfn(*pte)), get_order(PAGE_SIZE), altmap);
 181                         pte_clear(&init_mm, addr, pte);
 182                 } else if (pte_none(*pte)) {
 183                         if (!direct) {
 184                                 void *new_page = vmemmap_alloc_block_buf(PAGE_SIZE, NUMA_NO_NODE, altmap);
 185
 186                                 if (!new_page)
 187                                         goto out;
 188                                 set_pte(pte, __pte(__pa(new_page) | prot));
 189                         } else {
 190                                 set_pte(pte, __pte(__pa(addr) | prot));
 191                         }
 192                 } else {
 193                         continue;
 194                 }
 195                 pages++;
 196         }
 197         ret = 0;
 198 out:
 199         if (direct)
 200                 update_page_count(PG_DIRECT_MAP_4K, add ? pages : -pages);
 201         return ret;
 202 }
 203
 204 static void try_free_pte_table(pmd_t *pmd, unsigned long start)
 205 {
 206         pte_t *pte;
 207         int i;
 208
 209         /* We can safely assume this is fully in 1:1 mapping & vmemmap area */
 210         pte = pte_offset_kernel(pmd, start);
 211         for (i = 0; i < PTRS_PER_PTE; i++, pte++) {
 212                 if (!pte_none(*pte))
 213                         return;
 214         }
 215         vmem_pte_free((unsigned long *) pmd_deref(*pmd));
 216         pmd_clear(pmd);
 217 }
 218
 219 /* __ref: we'll only call vmemmap_alloc_block() via vmemmap_populate() */
 220 static int __ref modify_pmd_table(pud_t *pud, unsigned long addr,
 221                                   unsigned long end, bool add, bool direct,
 222                                   struct vmem_altmap *altmap)
 223 {
 224         unsigned long next, prot, pages = 0;
 225         int ret = -ENOMEM;
 226         pmd_t *pmd;
 227         pte_t *pte;
 228
 229         prot = pgprot_val(SEGMENT_KERNEL);
 230         pmd = pmd_offset(pud, addr);
 231         for (; addr < end; addr = next, pmd++) {
 232                 next = pmd_addr_end(addr, end);
 233                 if (!add) {
 234                         if (pmd_none(*pmd))
 235                                 continue;
 236                         if (pmd_leaf(*pmd)) {
 237                                 if (IS_ALIGNED(addr, PMD_SIZE) &&
 238                                     IS_ALIGNED(next, PMD_SIZE)) {
 239                                         if (!direct)
 240                                                 vmem_free_pages(pmd_deref(*pmd), get_order(PMD_SIZE), altmap);
 241                                         pmd_clear(pmd);
 242                                         pages++;
 243                                 } else if (!direct && vmemmap_unuse_sub_pmd(addr, next)) {
 244                                         vmem_free_pages(pmd_deref(*pmd), get_order(PMD_SIZE), altmap);
 245                                         pmd_clear(pmd);
 246                                 }
 247                                 continue;
 248                         }
 249                 } else if (pmd_none(*pmd)) {
 250                         if (IS_ALIGNED(addr, PMD_SIZE) &&
 251                             IS_ALIGNED(next, PMD_SIZE) &&
 252                             MACHINE_HAS_EDAT1 && direct &&
 253                             !debug_pagealloc_enabled()) {
 254                                 set_pmd(pmd, __pmd(__pa(addr) | prot));
 255                                 pages++;
 256                                 continue;
 257                         } else if (!direct && MACHINE_HAS_EDAT1) {
 258                                 void *new_page;
 259
 260                                 /*
 261                                  * Use 1MB frames for vmemmap if available. We
 262                                  * always use large frames even if they are only
 263                                  * partially used. Otherwise we would have also
 264                                  * page tables since vmemmap_populate gets
 265                                  * called for each section separately.
 266                                  */
 267                                 new_page = vmemmap_alloc_block_buf(PMD_SIZE, NUMA_NO_NODE, altmap);
 268                                 if (new_page) {
 269                                         set_pmd(pmd, __pmd(__pa(new_page) | prot));
 270                                         if (!IS_ALIGNED(addr, PMD_SIZE) ||
 271                                             !IS_ALIGNED(next, PMD_SIZE)) {
 272                                                 vmemmap_use_new_sub_pmd(addr, next);
 273                                         }
 274                                         continue;
 275                                 }
 276                         }
 277                         pte = vmem_pte_alloc();
 278                         if (!pte)
 279                                 goto out;
 280                         pmd_populate(&init_mm, pmd, pte);
 281                 } else if (pmd_leaf(*pmd)) {
 282                         if (!direct)
 283                                 vmemmap_use_sub_pmd(addr, next);
 284                         continue;
 285                 }
 286                 ret = modify_pte_table(pmd, addr, next, add, direct, altmap);
 287                 if (ret)
 288                         goto out;
 289                 if (!add)
 290                         try_free_pte_table(pmd, addr & PMD_MASK);
 291         }
 292         ret = 0;
 293 out:
 294         if (direct)
 295                 update_page_count(PG_DIRECT_MAP_1M, add ? pages : -pages);
 296         return ret;
 297 }
 298
 299 static void try_free_pmd_table(pud_t *pud, unsigned long start)
 300 {
 301         pmd_t *pmd;
 302         int i;
 303
 304         pmd = pmd_offset(pud, start);
 305         for (i = 0; i < PTRS_PER_PMD; i++, pmd++)
 306                 if (!pmd_none(*pmd))
 307                         return;
 308         vmem_free_pages(pud_deref(*pud), CRST_ALLOC_ORDER, NULL);
 309         pud_clear(pud);
 310 }
 311
 312 static int modify_pud_table(p4d_t *p4d, unsigned long addr, unsigned long end,
 313                             bool add, bool direct, struct vmem_altmap *altmap)
 314 {
 315         unsigned long next, prot, pages = 0;
 316         int ret = -ENOMEM;
 317         pud_t *pud;
 318         pmd_t *pmd;
 319
 320         prot = pgprot_val(REGION3_KERNEL);
 321         pud = pud_offset(p4d, addr);
 322         for (; addr < end; addr = next, pud++) {
 323                 next = pud_addr_end(addr, end);
 324                 if (!add) {
 325                         if (pud_none(*pud))
 326                                 continue;
 327                         if (pud_leaf(*pud)) {
 328                                 if (IS_ALIGNED(addr, PUD_SIZE) &&
 329                                     IS_ALIGNED(next, PUD_SIZE)) {
 330                                         pud_clear(pud);
 331                                         pages++;
 332                                 }
 333                                 continue;
 334                         }
 335                 } else if (pud_none(*pud)) {
 336                         if (IS_ALIGNED(addr, PUD_SIZE) &&
 337                             IS_ALIGNED(next, PUD_SIZE) &&
 338                             MACHINE_HAS_EDAT2 && direct &&
 339                             !debug_pagealloc_enabled()) {
 340                                 set_pud(pud, __pud(__pa(addr) | prot));
 341                                 pages++;
 342                                 continue;
 343                         }
 344                         pmd = vmem_crst_alloc(_SEGMENT_ENTRY_EMPTY);
 345                         if (!pmd)
 346                                 goto out;
 347                         pud_populate(&init_mm, pud, pmd);
 348                 } else if (pud_leaf(*pud)) {
 349                         continue;
 350                 }
 351                 ret = modify_pmd_table(pud, addr, next, add, direct, altmap);
 352                 if (ret)
 353                         goto out;
 354                 if (!add)
 355                         try_free_pmd_table(pud, addr & PUD_MASK);
 356         }
 357         ret = 0;
 358 out:
 359         if (direct)
 360                 update_page_count(PG_DIRECT_MAP_2G, add ? pages : -pages);
 361         return ret;
 362 }
 363
 364 static void try_free_pud_table(p4d_t *p4d, unsigned long start)
 365 {
 366         pud_t *pud;
 367         int i;
 368
 369         pud = pud_offset(p4d, start);
 370         for (i = 0; i < PTRS_PER_PUD; i++, pud++) {
 371                 if (!pud_none(*pud))
 372                         return;
 373         }
 374         vmem_free_pages(p4d_deref(*p4d), CRST_ALLOC_ORDER, NULL);
 375         p4d_clear(p4d);
 376 }
 377
 378 static int modify_p4d_table(pgd_t *pgd, unsigned long addr, unsigned long end,
 379                             bool add, bool direct, struct vmem_altmap *altmap)
 380 {
 381         unsigned long next;
 382         int ret = -ENOMEM;
 383         p4d_t *p4d;
 384         pud_t *pud;
 385
 386         p4d = p4d_offset(pgd, addr);
 387         for (; addr < end; addr = next, p4d++) {
 388                 next = p4d_addr_end(addr, end);
 389                 if (!add) {
 390                         if (p4d_none(*p4d))
 391                                 continue;
 392                 } else if (p4d_none(*p4d)) {
 393                         pud = vmem_crst_alloc(_REGION3_ENTRY_EMPTY);
 394                         if (!pud)
 395                                 goto out;
 396                         p4d_populate(&init_mm, p4d, pud);
 397                 }
 398                 ret = modify_pud_table(p4d, addr, next, add, direct, altmap);
 399                 if (ret)
 400                         goto out;
 401                 if (!add)
 402                         try_free_pud_table(p4d, addr & P4D_MASK);
 403         }
 404         ret = 0;
 405 out:
 406         return ret;
 407 }
 408
 409 static void try_free_p4d_table(pgd_t *pgd, unsigned long start)
 410 {
 411         p4d_t *p4d;
 412         int i;
 413
 414         p4d = p4d_offset(pgd, start);
 415         for (i = 0; i < PTRS_PER_P4D; i++, p4d++) {
 416                 if (!p4d_none(*p4d))
 417                         return;
 418         }
 419         vmem_free_pages(pgd_deref(*pgd), CRST_ALLOC_ORDER, NULL);
 420         pgd_clear(pgd);
 421 }
 422
 423 static int modify_pagetable(unsigned long start, unsigned long end, bool add,
 424                             bool direct, struct vmem_altmap *altmap)
 425 {
 426         unsigned long addr, next;
 427         int ret = -ENOMEM;
 428         pgd_t *pgd;
 429         p4d_t *p4d;
 430
 431         if (WARN_ON_ONCE(!PAGE_ALIGNED(start | end)))
 432                 return -EINVAL;
 433         /* Don't mess with any tables not fully in 1:1 mapping & vmemmap area */
 434         if (WARN_ON_ONCE(end > __abs_lowcore))
 435                 return -EINVAL;
 436         for (addr = start; addr < end; addr = next) {
 437                 next = pgd_addr_end(addr, end);
 438                 pgd = pgd_offset_k(addr);
 439
 440                 if (!add) {
 441                         if (pgd_none(*pgd))
 442                                 continue;
 443                 } else if (pgd_none(*pgd)) {
 444                         p4d = vmem_crst_alloc(_REGION2_ENTRY_EMPTY);
 445                         if (!p4d)
 446                                 goto out;
 447                         pgd_populate(&init_mm, pgd, p4d);
 448                 }
 449                 ret = modify_p4d_table(pgd, addr, next, add, direct, altmap);
 450                 if (ret)
 451                         goto out;
 452                 if (!add)
 453                         try_free_p4d_table(pgd, addr & PGDIR_MASK);
 454         }
 455         ret = 0;
 456 out:
 457         if (!add)
 458                 flush_tlb_kernel_range(start, end);
 459         return ret;
 460 }
 461
 462 static int add_pagetable(unsigned long start, unsigned long end, bool direct,
 463                          struct vmem_altmap *altmap)
 464 {
 465         return modify_pagetable(start, end, true, direct, altmap);
 466 }
 467
 468 static int remove_pagetable(unsigned long start, unsigned long end, bool direct,
 469                             struct vmem_altmap *altmap)
 470 {
 471         return modify_pagetable(start, end, false, direct, altmap);
 472 }
 473
 474 /*
 475  * Add a physical memory range to the 1:1 mapping.
 476  */
 477 static int vmem_add_range(unsigned long start, unsigned long size)
 478 {
 479         start = (unsigned long)__va(start);
 480         return add_pagetable(start, start + size, true, NULL);
 481 }
 482
 483 /*
 484  * Remove a physical memory range from the 1:1 mapping.
 485  */
 486 static void vmem_remove_range(unsigned long start, unsigned long size)
 487 {
 488         start = (unsigned long)__va(start);
 489         remove_pagetable(start, start + size, true, NULL);
 490 }
 491
 492 /*
 493  * Add a backed mem_map array to the virtual mem_map array.
 494  */
 495 int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
 496                                struct vmem_altmap *altmap)
 497 {
 498         int ret;
 499
 500         mutex_lock(&vmem_mutex);
 501         /* We don't care about the node, just use NUMA_NO_NODE on allocations */
 502         ret = add_pagetable(start, end, false, altmap);
 503         if (ret)
 504                 remove_pagetable(start, end, false, altmap);
 505         mutex_unlock(&vmem_mutex);
 506         return ret;
 507 }
 508
 509 #ifdef CONFIG_MEMORY_HOTPLUG
 510
 511 void vmemmap_free(unsigned long start, unsigned long end,
 512                   struct vmem_altmap *altmap)
 513 {
 514         mutex_lock(&vmem_mutex);
 515         remove_pagetable(start, end, false, altmap);
 516         mutex_unlock(&vmem_mutex);
 517 }
 518
 519 #endif
 520
 521 void vmem_remove_mapping(unsigned long start, unsigned long size)
 522 {
 523         mutex_lock(&vmem_mutex);
 524         vmem_remove_range(start, size);
 525         mutex_unlock(&vmem_mutex);
 526 }
 527
 528 struct range arch_get_mappable_range(void)
 529 {
 530         struct range mhp_range;
 531
 532         mhp_range.start = 0;
 533         mhp_range.end = max_mappable - 1;
 534         return mhp_range;
 535 }
 536
 537 int vmem_add_mapping(unsigned long start, unsigned long size)
 538 {
 539         struct range range = arch_get_mappable_range();
 540         int ret;
 541
 542         if (start < range.start ||
 543             start + size > range.end + 1 ||
 544             start + size < start)
 545                 return -ERANGE;
 546
 547         mutex_lock(&vmem_mutex);
 548         ret = vmem_add_range(start, size);
 549         if (ret)
 550                 vmem_remove_range(start, size);
 551         mutex_unlock(&vmem_mutex);
 552         return ret;
 553 }
 554
 555 /*
 556  * Allocate new or return existing page-table entry, but do not map it
 557  * to any physical address. If missing, allocate segment- and region-
 558  * table entries along. Meeting a large segment- or region-table entry
 559  * while traversing is an error, since the function is expected to be
 560  * called against virtual regions reserved for 4KB mappings only.
 561  */
 562 pte_t *vmem_get_alloc_pte(unsigned long addr, bool alloc)
 563 {
 564         pte_t *ptep = NULL;
 565         pgd_t *pgd;
 566         p4d_t *p4d;
 567         pud_t *pud;
 568         pmd_t *pmd;
 569         pte_t *pte;
 570
 571         pgd = pgd_offset_k(addr);
 572         if (pgd_none(*pgd)) {
 573                 if (!alloc)
 574                         goto out;
 575                 p4d = vmem_crst_alloc(_REGION2_ENTRY_EMPTY);
 576                 if (!p4d)
 577                         goto out;
 578                 pgd_populate(&init_mm, pgd, p4d);
 579         }
 580         p4d = p4d_offset(pgd, addr);
 581         if (p4d_none(*p4d)) {
 582                 if (!alloc)
 583                         goto out;
 584                 pud = vmem_crst_alloc(_REGION3_ENTRY_EMPTY);
 585                 if (!pud)
 586                         goto out;
 587                 p4d_populate(&init_mm, p4d, pud);
 588         }
 589         pud = pud_offset(p4d, addr);
 590         if (pud_none(*pud)) {
 591                 if (!alloc)
 592                         goto out;
 593                 pmd = vmem_crst_alloc(_SEGMENT_ENTRY_EMPTY);
 594                 if (!pmd)
 595                         goto out;
 596                 pud_populate(&init_mm, pud, pmd);
 597         } else if (WARN_ON_ONCE(pud_leaf(*pud))) {
 598                 goto out;
 599         }
 600         pmd = pmd_offset(pud, addr);
 601         if (pmd_none(*pmd)) {
 602                 if (!alloc)
 603                         goto out;
 604                 pte = vmem_pte_alloc();
 605                 if (!pte)
 606                         goto out;
 607                 pmd_populate(&init_mm, pmd, pte);
 608         } else if (WARN_ON_ONCE(pmd_leaf(*pmd))) {
 609                 goto out;
 610         }
 611         ptep = pte_offset_kernel(pmd, addr);
 612 out:
 613         return ptep;
 614 }
 615
 616 int __vmem_map_4k_page(unsigned long addr, unsigned long phys, pgprot_t prot, bool alloc)
 617 {
 618         pte_t *ptep, pte;
 619
 620         if (!IS_ALIGNED(addr, PAGE_SIZE))
 621                 return -EINVAL;
 622         ptep = vmem_get_alloc_pte(addr, alloc);
 623         if (!ptep)
 624                 return -ENOMEM;
 625         __ptep_ipte(addr, ptep, 0, 0, IPTE_GLOBAL);
 626         pte = mk_pte_phys(phys, prot);
 627         set_pte(ptep, pte);
 628         return 0;
 629 }
 630
 631 int vmem_map_4k_page(unsigned long addr, unsigned long phys, pgprot_t prot)
 632 {
 633         int rc;
 634
 635         mutex_lock(&vmem_mutex);
 636         rc = __vmem_map_4k_page(addr, phys, prot, true);
 637         mutex_unlock(&vmem_mutex);
 638         return rc;
 639 }
 640
 641 void vmem_unmap_4k_page(unsigned long addr)
 642 {
 643         pte_t *ptep;
 644
 645         mutex_lock(&vmem_mutex);
 646         ptep = virt_to_kpte(addr);
 647         __ptep_ipte(addr, ptep, 0, 0, IPTE_GLOBAL);
 648         pte_clear(&init_mm, addr, ptep);
 649         mutex_unlock(&vmem_mutex);
 650 }
 651
 652 void __init vmem_map_init(void)
 653 {
 654         __set_memory_rox(_stext, _etext);
 655         __set_memory_ro(_etext, __end_rodata);
 656         __set_memory_rox(__stext_amode31, __etext_amode31);
 657         /*
 658          * If the BEAR-enhancement facility is not installed the first
 659          * prefix page is used to return to the previous context with
 660          * an LPSWE instruction and therefore must be executable.
 661          */
 662         if (!static_key_enabled(&cpu_has_bear))
 663                 set_memory_x(0, 1);
 664         if (debug_pagealloc_enabled())
 665                 __set_memory_4k(__va(0), __va(0) + ident_map_size);
 666         pr_info("Write protected kernel read-only data: %luk\n",
 667                 (unsigned long)(__end_rodata - _stext) >> 10);
 668 }