arch/x86/mm/pageattr.c

   1 /*
   2  * Copyright 2002 Andi Kleen, SuSE Labs.
   3  * Thanks to Ben LaHaise for precious feedback.
   4  */
   5 #include <linux/highmem.h>
   6 #include <linux/bootmem.h>
   7 #include <linux/module.h>
   8 #include <linux/sched.h>
   9 #include <linux/slab.h>
  10 #include <linux/mm.h>
  11
  12 #include <asm/e820.h>
  13 #include <asm/processor.h>
  14 #include <asm/tlbflush.h>
  15 #include <asm/sections.h>
  16 #include <asm/uaccess.h>
  17 #include <asm/pgalloc.h>
  18
  19 static inline int
  20 within(unsigned long addr, unsigned long start, unsigned long end)
  21 {
  22         return addr >= start && addr < end;
  23 }
  24
  25 /*
  26  * Flushing functions
  27  */
  28
  29 /**
  30  * clflush_cache_range - flush a cache range with clflush
  31  * @addr:       virtual start address
  32  * @size:       number of bytes to flush
  33  *
  34  * clflush is an unordered instruction which needs fencing with mfence
  35  * to avoid ordering issues.
  36  */
  37 void clflush_cache_range(void *vaddr, unsigned int size)
  38 {
  39         void *vend = vaddr + size - 1;
  40
  41         mb();
  42
  43         for (; vaddr < vend; vaddr += boot_cpu_data.x86_clflush_size)
  44                 clflush(vaddr);
  45         /*
  46          * Flush any possible final partial cacheline:
  47          */
  48         clflush(vend);
  49
  50         mb();
  51 }
  52
  53 static void __cpa_flush_all(void *arg)
  54 {
  55         /*
  56          * Flush all to work around Errata in early athlons regarding
  57          * large page flushing.
  58          */
  59         __flush_tlb_all();
  60
  61         if (boot_cpu_data.x86_model >= 4)
  62                 wbinvd();
  63 }
  64
  65 static void cpa_flush_all(void)
  66 {
  67         BUG_ON(irqs_disabled());
  68
  69         on_each_cpu(__cpa_flush_all, NULL, 1, 1);
  70 }
  71
  72 static void __cpa_flush_range(void *arg)
  73 {
  74         /*
  75          * We could optimize that further and do individual per page
  76          * tlb invalidates for a low number of pages. Caveat: we must
  77          * flush the high aliases on 64bit as well.
  78          */
  79         __flush_tlb_all();
  80 }
  81
  82 static void cpa_flush_range(unsigned long start, int numpages)
  83 {
  84         unsigned int i, level;
  85         unsigned long addr;
  86
  87         BUG_ON(irqs_disabled());
  88         WARN_ON(PAGE_ALIGN(start) != start);
  89
  90         on_each_cpu(__cpa_flush_range, NULL, 1, 1);
  91
  92         /*
  93          * We only need to flush on one CPU,
  94          * clflush is a MESI-coherent instruction that
  95          * will cause all other CPUs to flush the same
  96          * cachelines:
  97          */
  98         for (i = 0, addr = start; i < numpages; i++, addr += PAGE_SIZE) {
  99                 pte_t *pte = lookup_address(addr, &level);
 100
 101                 /*
 102                  * Only flush present addresses:
 103                  */
 104                 if (pte && pte_present(*pte))
 105                         clflush_cache_range((void *) addr, PAGE_SIZE);
 106         }
 107 }
 108
 109 /*
 110  * Certain areas of memory on x86 require very specific protection flags,
 111  * for example the BIOS area or kernel text. Callers don't always get this
 112  * right (again, ioremap() on BIOS memory is not uncommon) so this function
 113  * checks and fixes these known static required protection bits.
 114  */
 115 static inline pgprot_t static_protections(pgprot_t prot, unsigned long address)
 116 {
 117         pgprot_t forbidden = __pgprot(0);
 118
 119         /*
 120          * The BIOS area between 640k and 1Mb needs to be executable for
 121          * PCI BIOS based config access (CONFIG_PCI_GOBIOS) support.
 122          */
 123         if (within(__pa(address), BIOS_BEGIN, BIOS_END))
 124                 pgprot_val(forbidden) |= _PAGE_NX;
 125
 126         /*
 127          * The kernel text needs to be executable for obvious reasons
 128          * Does not cover __inittext since that is gone later on
 129          */
 130         if (within(address, (unsigned long)_text, (unsigned long)_etext))
 131                 pgprot_val(forbidden) |= _PAGE_NX;
 132
 133 #ifdef CONFIG_DEBUG_RODATA
 134         /* The .rodata section needs to be read-only */
 135         if (within(address, (unsigned long)__start_rodata,
 136                                 (unsigned long)__end_rodata))
 137                 pgprot_val(forbidden) |= _PAGE_RW;
 138 #endif
 139
 140         prot = __pgprot(pgprot_val(prot) & ~pgprot_val(forbidden));
 141
 142         return prot;
 143 }
 144
 145 pte_t *lookup_address(unsigned long address, int *level)
 146 {
 147         pgd_t *pgd = pgd_offset_k(address);
 148         pud_t *pud;
 149         pmd_t *pmd;
 150
 151         *level = PG_LEVEL_NONE;
 152
 153         if (pgd_none(*pgd))
 154                 return NULL;
 155         pud = pud_offset(pgd, address);
 156         if (pud_none(*pud))
 157                 return NULL;
 158         pmd = pmd_offset(pud, address);
 159         if (pmd_none(*pmd))
 160                 return NULL;
 161
 162         *level = PG_LEVEL_2M;
 163         if (pmd_large(*pmd))
 164                 return (pte_t *)pmd;
 165
 166         *level = PG_LEVEL_4K;
 167         return pte_offset_kernel(pmd, address);
 168 }
 169
 170 static void __set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)
 171 {
 172         /* change init_mm */
 173         set_pte_atomic(kpte, pte);
 174 #ifdef CONFIG_X86_32
 175         if (!SHARED_KERNEL_PMD) {
 176                 struct page *page;
 177
 178                 for (page = pgd_list; page; page = (struct page *)page->index) {
 179                         pgd_t *pgd;
 180                         pud_t *pud;
 181                         pmd_t *pmd;
 182
 183                         pgd = (pgd_t *)page_address(page) + pgd_index(address);
 184                         pud = pud_offset(pgd, address);
 185                         pmd = pmd_offset(pud, address);
 186                         set_pte_atomic((pte_t *)pmd, pte);
 187                 }
 188         }
 189 #endif
 190 }
 191
 192 static int split_large_page(pte_t *kpte, unsigned long address)
 193 {
 194         pgprot_t ref_prot = pte_pgprot(pte_clrhuge(*kpte));
 195         gfp_t gfp_flags = GFP_KERNEL;
 196         unsigned long flags;
 197         unsigned long addr;
 198         pte_t *pbase, *tmp;
 199         struct page *base;
 200         int i, level;
 201
 202 #ifdef CONFIG_DEBUG_PAGEALLOC
 203         gfp_flags = GFP_ATOMIC;
 204 #endif
 205         base = alloc_pages(gfp_flags, 0);
 206         if (!base)
 207                 return -ENOMEM;
 208
 209         spin_lock_irqsave(&pgd_lock, flags);
 210         /*
 211          * Check for races, another CPU might have split this page
 212          * up for us already:
 213          */
 214         tmp = lookup_address(address, &level);
 215         if (tmp != kpte) {
 216                 WARN_ON_ONCE(1);
 217                 goto out_unlock;
 218         }
 219
 220         address = __pa(address);
 221         addr = address & LARGE_PAGE_MASK;
 222         pbase = (pte_t *)page_address(base);
 223 #ifdef CONFIG_X86_32
 224         paravirt_alloc_pt(&init_mm, page_to_pfn(base));
 225 #endif
 226
 227         for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE)
 228                 set_pte(&pbase[i], pfn_pte(addr >> PAGE_SHIFT, ref_prot));
 229
 230         /*
 231          * Install the new, split up pagetable. Important detail here:
 232          *
 233          * On Intel the NX bit of all levels must be cleared to make a
 234          * page executable. See section 4.13.2 of Intel 64 and IA-32
 235          * Architectures Software Developer's Manual).
 236          */
 237         ref_prot = pte_pgprot(pte_mkexec(pte_clrhuge(*kpte)));
 238         __set_pmd_pte(kpte, address, mk_pte(base, ref_prot));
 239         base = NULL;
 240
 241 out_unlock:
 242         spin_unlock_irqrestore(&pgd_lock, flags);
 243
 244         if (base)
 245                 __free_pages(base, 0);
 246
 247         return 0;
 248 }
 249
 250 static int
 251 __change_page_attr(unsigned long address, unsigned long pfn, pgprot_t prot)
 252 {
 253         struct page *kpte_page;
 254         int level, err = 0;
 255         pte_t *kpte;
 256
 257 #ifdef CONFIG_X86_32
 258         BUG_ON(pfn > max_low_pfn);
 259 #endif
 260
 261 repeat:
 262         kpte = lookup_address(address, &level);
 263         if (!kpte)
 264                 return -EINVAL;
 265
 266         kpte_page = virt_to_page(kpte);
 267         BUG_ON(PageLRU(kpte_page));
 268         BUG_ON(PageCompound(kpte_page));
 269
 270         prot = static_protections(prot, address);
 271
 272         if (level == PG_LEVEL_4K) {
 273                 WARN_ON_ONCE(pgprot_val(prot) & _PAGE_PSE);
 274                 set_pte_atomic(kpte, pfn_pte(pfn, canon_pgprot(prot)));
 275         } else {
 276                 /* Clear the PSE bit for the 4k level pages ! */
 277                 pgprot_val(prot) = pgprot_val(prot) & ~_PAGE_PSE;
 278
 279                 err = split_large_page(kpte, address);
 280                 if (!err)
 281                         goto repeat;
 282         }
 283         return err;
 284 }
 285
 286 /**
 287  * change_page_attr_addr - Change page table attributes in linear mapping
 288  * @address: Virtual address in linear mapping.
 289  * @prot:    New page table attribute (PAGE_*)
 290  *
 291  * Change page attributes of a page in the direct mapping. This is a variant
 292  * of change_page_attr() that also works on memory holes that do not have
 293  * mem_map entry (pfn_valid() is false).
 294  *
 295  * See change_page_attr() documentation for more details.
 296  *
 297  * Modules and drivers should use the set_memory_* APIs instead.
 298  */
 299
 300 static int change_page_attr_addr(unsigned long address, pgprot_t prot)
 301 {
 302         int err = 0, kernel_map = 0;
 303         unsigned long pfn = __pa(address) >> PAGE_SHIFT;
 304
 305 #ifdef CONFIG_X86_64
 306         if (address >= __START_KERNEL_map &&
 307                         address < __START_KERNEL_map + KERNEL_TEXT_SIZE) {
 308
 309                 address = (unsigned long)__va(__pa(address));
 310                 kernel_map = 1;
 311         }
 312 #endif
 313
 314         if (!kernel_map || pte_present(pfn_pte(0, prot))) {
 315                 err = __change_page_attr(address, pfn, prot);
 316                 if (err)
 317                         return err;
 318         }
 319
 320 #ifdef CONFIG_X86_64
 321         /*
 322          * Handle kernel mapping too which aliases part of
 323          * lowmem:
 324          */
 325         if (__pa(address) < KERNEL_TEXT_SIZE) {
 326                 unsigned long addr2;
 327                 pgprot_t prot2;
 328
 329                 addr2 = __START_KERNEL_map + __pa(address);
 330                 /* Make sure the kernel mappings stay executable */
 331                 prot2 = pte_pgprot(pte_mkexec(pfn_pte(0, prot)));
 332                 err = __change_page_attr(addr2, pfn, prot2);
 333         }
 334 #endif
 335
 336         return err;
 337 }
 338
 339 static int __change_page_attr_set_clr(unsigned long addr, int numpages,
 340                                       pgprot_t mask_set, pgprot_t mask_clr)
 341 {
 342         pgprot_t new_prot;
 343         int level;
 344         pte_t *pte;
 345         int i, ret;
 346
 347         for (i = 0; i < numpages ; i++) {
 348
 349                 pte = lookup_address(addr, &level);
 350                 if (!pte)
 351                         return -EINVAL;
 352
 353                 new_prot = pte_pgprot(*pte);
 354
 355                 pgprot_val(new_prot) &= ~pgprot_val(mask_clr);
 356                 pgprot_val(new_prot) |= pgprot_val(mask_set);
 357
 358                 ret = change_page_attr_addr(addr, new_prot);
 359                 if (ret)
 360                         return ret;
 361                 addr += PAGE_SIZE;
 362         }
 363
 364         return 0;
 365 }
 366
 367 static int change_page_attr_set_clr(unsigned long addr, int numpages,
 368                                     pgprot_t mask_set, pgprot_t mask_clr)
 369 {
 370         int ret = __change_page_attr_set_clr(addr, numpages, mask_set,
 371                                              mask_clr);
 372
 373         /*
 374          * On success we use clflush, when the CPU supports it to
 375          * avoid the wbindv. If the CPU does not support it and in the
 376          * error case we fall back to cpa_flush_all (which uses
 377          * wbindv):
 378          */
 379         if (!ret && cpu_has_clflush)
 380                 cpa_flush_range(addr, numpages);
 381         else
 382                 cpa_flush_all();
 383
 384         return ret;
 385 }
 386
 387 static inline int change_page_attr_set(unsigned long addr, int numpages,
 388                                        pgprot_t mask)
 389 {
 390         return change_page_attr_set_clr(addr, numpages, mask, __pgprot(0));
 391 }
 392
 393 static inline int change_page_attr_clear(unsigned long addr, int numpages,
 394                                          pgprot_t mask)
 395 {
 396         return __change_page_attr_set_clr(addr, numpages, __pgprot(0), mask);
 397
 398 }
 399
 400 int set_memory_uc(unsigned long addr, int numpages)
 401 {
 402         return change_page_attr_set(addr, numpages,
 403                                     __pgprot(_PAGE_PCD | _PAGE_PWT));
 404 }
 405 EXPORT_SYMBOL(set_memory_uc);
 406
 407 int set_memory_wb(unsigned long addr, int numpages)
 408 {
 409         return change_page_attr_clear(addr, numpages,
 410                                       __pgprot(_PAGE_PCD | _PAGE_PWT));
 411 }
 412 EXPORT_SYMBOL(set_memory_wb);
 413
 414 int set_memory_x(unsigned long addr, int numpages)
 415 {
 416         return change_page_attr_clear(addr, numpages, __pgprot(_PAGE_NX));
 417 }
 418 EXPORT_SYMBOL(set_memory_x);
 419
 420 int set_memory_nx(unsigned long addr, int numpages)
 421 {
 422         return change_page_attr_set(addr, numpages, __pgprot(_PAGE_NX));
 423 }
 424 EXPORT_SYMBOL(set_memory_nx);
 425
 426 int set_memory_ro(unsigned long addr, int numpages)
 427 {
 428         return change_page_attr_clear(addr, numpages, __pgprot(_PAGE_RW));
 429 }
 430
 431 int set_memory_rw(unsigned long addr, int numpages)
 432 {
 433         return change_page_attr_set(addr, numpages, __pgprot(_PAGE_RW));
 434 }
 435
 436 int set_memory_np(unsigned long addr, int numpages)
 437 {
 438         return change_page_attr_clear(addr, numpages, __pgprot(_PAGE_PRESENT));
 439 }
 440
 441 int set_pages_uc(struct page *page, int numpages)
 442 {
 443         unsigned long addr = (unsigned long)page_address(page);
 444
 445         return set_memory_uc(addr, numpages);
 446 }
 447 EXPORT_SYMBOL(set_pages_uc);
 448
 449 int set_pages_wb(struct page *page, int numpages)
 450 {
 451         unsigned long addr = (unsigned long)page_address(page);
 452
 453         return set_memory_wb(addr, numpages);
 454 }
 455 EXPORT_SYMBOL(set_pages_wb);
 456
 457 int set_pages_x(struct page *page, int numpages)
 458 {
 459         unsigned long addr = (unsigned long)page_address(page);
 460
 461         return set_memory_x(addr, numpages);
 462 }
 463 EXPORT_SYMBOL(set_pages_x);
 464
 465 int set_pages_nx(struct page *page, int numpages)
 466 {
 467         unsigned long addr = (unsigned long)page_address(page);
 468
 469         return set_memory_nx(addr, numpages);
 470 }
 471 EXPORT_SYMBOL(set_pages_nx);
 472
 473 int set_pages_ro(struct page *page, int numpages)
 474 {
 475         unsigned long addr = (unsigned long)page_address(page);
 476
 477         return set_memory_ro(addr, numpages);
 478 }
 479
 480 int set_pages_rw(struct page *page, int numpages)
 481 {
 482         unsigned long addr = (unsigned long)page_address(page);
 483
 484         return set_memory_rw(addr, numpages);
 485 }
 486
 487
 488 #if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_CPA_DEBUG)
 489 static inline int __change_page_attr_set(unsigned long addr, int numpages,
 490                                          pgprot_t mask)
 491 {
 492         return __change_page_attr_set_clr(addr, numpages, mask, __pgprot(0));
 493 }
 494
 495 static inline int __change_page_attr_clear(unsigned long addr, int numpages,
 496                                            pgprot_t mask)
 497 {
 498         return __change_page_attr_set_clr(addr, numpages, __pgprot(0), mask);
 499 }
 500 #endif
 501
 502 #ifdef CONFIG_DEBUG_PAGEALLOC
 503
 504 static int __set_pages_p(struct page *page, int numpages)
 505 {
 506         unsigned long addr = (unsigned long)page_address(page);
 507
 508         return __change_page_attr_set(addr, numpages,
 509                                       __pgprot(_PAGE_PRESENT | _PAGE_RW));
 510 }
 511
 512 static int __set_pages_np(struct page *page, int numpages)
 513 {
 514         unsigned long addr = (unsigned long)page_address(page);
 515
 516         return __change_page_attr_clear(addr, numpages,
 517                                         __pgprot(_PAGE_PRESENT));
 518 }
 519
 520 void kernel_map_pages(struct page *page, int numpages, int enable)
 521 {
 522         if (PageHighMem(page))
 523                 return;
 524         if (!enable) {
 525                 debug_check_no_locks_freed(page_address(page),
 526                                            numpages * PAGE_SIZE);
 527         }
 528
 529         /*
 530          * If page allocator is not up yet then do not call c_p_a():
 531          */
 532         if (!debug_pagealloc_enabled)
 533                 return;
 534
 535         /*
 536          * The return value is ignored - the calls cannot fail,
 537          * large pages are disabled at boot time:
 538          */
 539         if (enable)
 540                 __set_pages_p(page, numpages);
 541         else
 542                 __set_pages_np(page, numpages);
 543
 544         /*
 545          * We should perform an IPI and flush all tlbs,
 546          * but that can deadlock->flush only current cpu:
 547          */
 548         __flush_tlb_all();
 549 }
 550 #endif
 551
 552 /*
 553  * The testcases use internal knowledge of the implementation that shouldn't
 554  * be exposed to the rest of the kernel. Include these directly here.
 555  */
 556 #ifdef CONFIG_CPA_DEBUG
 557 #include "pageattr-test.c"
 558 #endif