SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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  * Certain areas of memory on x86 require very specific protection flags,
  27  * for example the BIOS area or kernel text. Callers don't always get this
  28  * right (again, ioremap() on BIOS memory is not uncommon) so this function
  29  * checks and fixes these known static required protection bits.
  30  */
  31 static inline pgprot_t static_protections(pgprot_t prot, unsigned long address)
  32 {
  33         pgprot_t forbidden = __pgprot(0);
  34
  35         /*
  36          * The BIOS area between 640k and 1Mb needs to be executable for
  37          * PCI BIOS based config access (CONFIG_PCI_GOBIOS) support.
  38          */
  39         if (within(__pa(address), BIOS_BEGIN, BIOS_END))
  40                 pgprot_val(forbidden) |= _PAGE_NX;
  41
  42         /*
  43          * The kernel text needs to be executable for obvious reasons
  44          * Does not cover __inittext since that is gone later on
  45          */
  46         if (within(address, (unsigned long)_text, (unsigned long)_etext))
  47                 pgprot_val(forbidden) |= _PAGE_NX;
  48
  49 #ifdef CONFIG_DEBUG_RODATA
  50         /* The .rodata section needs to be read-only */
  51         if (within(address, (unsigned long)__start_rodata,
  52                                 (unsigned long)__end_rodata))
  53                 pgprot_val(forbidden) |= _PAGE_RW;
  54 #endif
  55
  56         prot = __pgprot(pgprot_val(prot) & ~pgprot_val(forbidden));
  57
  58         return prot;
  59 }
  60
  61 pte_t *lookup_address(unsigned long address, int *level)
  62 {
  63         pgd_t *pgd = pgd_offset_k(address);
  64         pud_t *pud;
  65         pmd_t *pmd;
  66
  67         *level = PG_LEVEL_NONE;
  68
  69         if (pgd_none(*pgd))
  70                 return NULL;
  71         pud = pud_offset(pgd, address);
  72         if (pud_none(*pud))
  73                 return NULL;
  74         pmd = pmd_offset(pud, address);
  75         if (pmd_none(*pmd))
  76                 return NULL;
  77
  78         *level = PG_LEVEL_2M;
  79         if (pmd_large(*pmd))
  80                 return (pte_t *)pmd;
  81
  82         *level = PG_LEVEL_4K;
  83         return pte_offset_kernel(pmd, address);
  84 }
  85
  86 static void __set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)
  87 {
  88         /* change init_mm */
  89         set_pte_atomic(kpte, pte);
  90 #ifdef CONFIG_X86_32
  91         if (!SHARED_KERNEL_PMD) {
  92                 struct page *page;
  93
  94                 for (page = pgd_list; page; page = (struct page *)page->index) {
  95                         pgd_t *pgd;
  96                         pud_t *pud;
  97                         pmd_t *pmd;
  98
  99                         pgd = (pgd_t *)page_address(page) + pgd_index(address);
 100                         pud = pud_offset(pgd, address);
 101                         pmd = pmd_offset(pud, address);
 102                         set_pte_atomic((pte_t *)pmd, pte);
 103                 }
 104         }
 105 #endif
 106 }
 107
 108 static int split_large_page(pte_t *kpte, unsigned long address)
 109 {
 110         pgprot_t ref_prot = pte_pgprot(pte_clrhuge(*kpte));
 111         gfp_t gfp_flags = GFP_KERNEL;
 112         unsigned long flags;
 113         unsigned long addr;
 114         pte_t *pbase, *tmp;
 115         struct page *base;
 116         int i, level;
 117
 118 #ifdef CONFIG_DEBUG_PAGEALLOC
 119         gfp_flags = GFP_ATOMIC;
 120 #endif
 121         base = alloc_pages(gfp_flags, 0);
 122         if (!base)
 123                 return -ENOMEM;
 124
 125         spin_lock_irqsave(&pgd_lock, flags);
 126         /*
 127          * Check for races, another CPU might have split this page
 128          * up for us already:
 129          */
 130         tmp = lookup_address(address, &level);
 131         if (tmp != kpte) {
 132                 WARN_ON_ONCE(1);
 133                 goto out_unlock;
 134         }
 135
 136         address = __pa(address);
 137         addr = address & LARGE_PAGE_MASK;
 138         pbase = (pte_t *)page_address(base);
 139 #ifdef CONFIG_X86_32
 140         paravirt_alloc_pt(&init_mm, page_to_pfn(base));
 141 #endif
 142
 143         for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE)
 144                 set_pte(&pbase[i], pfn_pte(addr >> PAGE_SHIFT, ref_prot));
 145
 146         /*
 147          * Install the new, split up pagetable. Important detail here:
 148          *
 149          * On Intel the NX bit of all levels must be cleared to make a
 150          * page executable. See section 4.13.2 of Intel 64 and IA-32
 151          * Architectures Software Developer's Manual).
 152          */
 153         ref_prot = pte_pgprot(pte_mkexec(pte_clrhuge(*kpte)));
 154         __set_pmd_pte(kpte, address, mk_pte(base, ref_prot));
 155         base = NULL;
 156
 157 out_unlock:
 158         spin_unlock_irqrestore(&pgd_lock, flags);
 159
 160         if (base)
 161                 __free_pages(base, 0);
 162
 163         return 0;
 164 }
 165
 166 static int
 167 __change_page_attr(unsigned long address, unsigned long pfn, pgprot_t prot)
 168 {
 169         struct page *kpte_page;
 170         int level, err = 0;
 171         pte_t *kpte;
 172
 173 #ifdef CONFIG_X86_32
 174         BUG_ON(pfn > max_low_pfn);
 175 #endif
 176
 177 repeat:
 178         kpte = lookup_address(address, &level);
 179         if (!kpte)
 180                 return -EINVAL;
 181
 182         kpte_page = virt_to_page(kpte);
 183         BUG_ON(PageLRU(kpte_page));
 184         BUG_ON(PageCompound(kpte_page));
 185
 186         prot = static_protections(prot, address);
 187
 188         if (level == PG_LEVEL_4K) {
 189                 set_pte_atomic(kpte, pfn_pte(pfn, canon_pgprot(prot)));
 190         } else {
 191                 err = split_large_page(kpte, address);
 192                 if (!err)
 193                         goto repeat;
 194         }
 195         return err;
 196 }
 197
 198 /**
 199  * change_page_attr_addr - Change page table attributes in linear mapping
 200  * @address: Virtual address in linear mapping.
 201  * @numpages: Number of pages to change
 202  * @prot:    New page table attribute (PAGE_*)
 203  *
 204  * Change page attributes of a page in the direct mapping. This is a variant
 205  * of change_page_attr() that also works on memory holes that do not have
 206  * mem_map entry (pfn_valid() is false).
 207  *
 208  * See change_page_attr() documentation for more details.
 209  *
 210  * Modules and drivers should use the set_memory_* APIs instead.
 211  */
 212
 213 static int change_page_attr_addr(unsigned long address, int numpages,
 214                                                                 pgprot_t prot)
 215 {
 216         int err = 0, kernel_map = 0, i;
 217
 218 #ifdef CONFIG_X86_64
 219         if (address >= __START_KERNEL_map &&
 220                         address < __START_KERNEL_map + KERNEL_TEXT_SIZE) {
 221
 222                 address = (unsigned long)__va(__pa(address));
 223                 kernel_map = 1;
 224         }
 225 #endif
 226
 227         for (i = 0; i < numpages; i++, address += PAGE_SIZE) {
 228                 unsigned long pfn = __pa(address) >> PAGE_SHIFT;
 229
 230                 if (!kernel_map || pte_present(pfn_pte(0, prot))) {
 231                         err = __change_page_attr(address, pfn, prot);
 232                         if (err)
 233                                 break;
 234                 }
 235 #ifdef CONFIG_X86_64
 236                 /*
 237                  * Handle kernel mapping too which aliases part of
 238                  * lowmem:
 239                  */
 240                 if (__pa(address) < KERNEL_TEXT_SIZE) {
 241                         unsigned long addr2;
 242                         pgprot_t prot2;
 243
 244                         addr2 = __START_KERNEL_map + __pa(address);
 245                         /* Make sure the kernel mappings stay executable */
 246                         prot2 = pte_pgprot(pte_mkexec(pfn_pte(0, prot)));
 247                         err = __change_page_attr(addr2, pfn, prot2);
 248                 }
 249 #endif
 250         }
 251
 252         return err;
 253 }
 254
 255 /**
 256  * change_page_attr_set - Change page table attributes in the linear mapping.
 257  * @addr: Virtual address in linear mapping.
 258  * @numpages: Number of pages to change
 259  * @prot: Protection/caching type bits to set (PAGE_*)
 260  *
 261  * Returns 0 on success, otherwise a negated errno.
 262  *
 263  * This should be used when a page is mapped with a different caching policy
 264  * than write-back somewhere - some CPUs do not like it when mappings with
 265  * different caching policies exist. This changes the page attributes of the
 266  * in kernel linear mapping too.
 267  *
 268  * The caller needs to ensure that there are no conflicting mappings elsewhere
 269  * (e.g. in user space) * This function only deals with the kernel linear map.
 270  *
 271  * This function is different from change_page_attr() in that only selected bits
 272  * are impacted, all other bits remain as is.
 273  */
 274 static int change_page_attr_set(unsigned long addr, int numpages,
 275                                                                 pgprot_t prot)
 276 {
 277         pgprot_t current_prot;
 278         int level;
 279         pte_t *pte;
 280
 281         pte = lookup_address(addr, &level);
 282         if (pte)
 283                 current_prot = pte_pgprot(*pte);
 284         else
 285                 pgprot_val(current_prot) = 0;
 286
 287         pgprot_val(prot) = pgprot_val(current_prot) | pgprot_val(prot);
 288
 289         return change_page_attr_addr(addr, numpages, prot);
 290 }
 291
 292 /**
 293  * change_page_attr_clear - Change page table attributes in the linear mapping.
 294  * @addr: Virtual address in linear mapping.
 295  * @numpages: Number of pages to change
 296  * @prot: Protection/caching type bits to clear (PAGE_*)
 297  *
 298  * Returns 0 on success, otherwise a negated errno.
 299  *
 300  * This should be used when a page is mapped with a different caching policy
 301  * than write-back somewhere - some CPUs do not like it when mappings with
 302  * different caching policies exist. This changes the page attributes of the
 303  * in kernel linear mapping too.
 304  *
 305  * The caller needs to ensure that there are no conflicting mappings elsewhere
 306  * (e.g. in user space) * This function only deals with the kernel linear map.
 307  *
 308  * This function is different from change_page_attr() in that only selected bits
 309  * are impacted, all other bits remain as is.
 310  */
 311 static int change_page_attr_clear(unsigned long addr, int numpages,
 312                                                                 pgprot_t prot)
 313 {
 314         pgprot_t current_prot;
 315         int level;
 316         pte_t *pte;
 317
 318         pte = lookup_address(addr, &level);
 319         if (pte)
 320                 current_prot = pte_pgprot(*pte);
 321         else
 322                 pgprot_val(current_prot) = 0;
 323
 324         pgprot_val(prot) = pgprot_val(current_prot) & ~pgprot_val(prot);
 325
 326         return change_page_attr_addr(addr, numpages, prot);
 327 }
 328
 329 int set_memory_uc(unsigned long addr, int numpages)
 330 {
 331         pgprot_t uncached;
 332
 333         pgprot_val(uncached) = _PAGE_PCD | _PAGE_PWT;
 334         return change_page_attr_set(addr, numpages, uncached);
 335 }
 336 EXPORT_SYMBOL(set_memory_uc);
 337
 338 int set_memory_wb(unsigned long addr, int numpages)
 339 {
 340         pgprot_t uncached;
 341
 342         pgprot_val(uncached) = _PAGE_PCD | _PAGE_PWT;
 343         return change_page_attr_clear(addr, numpages, uncached);
 344 }
 345 EXPORT_SYMBOL(set_memory_wb);
 346
 347 int set_memory_x(unsigned long addr, int numpages)
 348 {
 349         pgprot_t nx;
 350
 351         pgprot_val(nx) = _PAGE_NX;
 352         return change_page_attr_clear(addr, numpages, nx);
 353 }
 354 EXPORT_SYMBOL(set_memory_x);
 355
 356 int set_memory_nx(unsigned long addr, int numpages)
 357 {
 358         pgprot_t nx;
 359
 360         pgprot_val(nx) = _PAGE_NX;
 361         return change_page_attr_set(addr, numpages, nx);
 362 }
 363 EXPORT_SYMBOL(set_memory_nx);
 364
 365 int set_memory_ro(unsigned long addr, int numpages)
 366 {
 367         pgprot_t rw;
 368
 369         pgprot_val(rw) = _PAGE_RW;
 370         return change_page_attr_clear(addr, numpages, rw);
 371 }
 372
 373 int set_memory_rw(unsigned long addr, int numpages)
 374 {
 375         pgprot_t rw;
 376
 377         pgprot_val(rw) = _PAGE_RW;
 378         return change_page_attr_set(addr, numpages, rw);
 379 }
 380
 381 int set_memory_np(unsigned long addr, int numpages)
 382 {
 383         pgprot_t present;
 384
 385         pgprot_val(present) = _PAGE_PRESENT;
 386         return change_page_attr_clear(addr, numpages, present);
 387 }
 388
 389 int set_pages_uc(struct page *page, int numpages)
 390 {
 391         unsigned long addr = (unsigned long)page_address(page);
 392         pgprot_t uncached;
 393
 394         pgprot_val(uncached) = _PAGE_PCD | _PAGE_PWT;
 395         return change_page_attr_set(addr, numpages, uncached);
 396 }
 397 EXPORT_SYMBOL(set_pages_uc);
 398
 399 int set_pages_wb(struct page *page, int numpages)
 400 {
 401         unsigned long addr = (unsigned long)page_address(page);
 402         pgprot_t uncached;
 403
 404         pgprot_val(uncached) = _PAGE_PCD | _PAGE_PWT;
 405         return change_page_attr_clear(addr, numpages, uncached);
 406 }
 407 EXPORT_SYMBOL(set_pages_wb);
 408
 409 int set_pages_x(struct page *page, int numpages)
 410 {
 411         unsigned long addr = (unsigned long)page_address(page);
 412         pgprot_t nx;
 413
 414         pgprot_val(nx) = _PAGE_NX;
 415         return change_page_attr_clear(addr, numpages, nx);
 416 }
 417 EXPORT_SYMBOL(set_pages_x);
 418
 419 int set_pages_nx(struct page *page, int numpages)
 420 {
 421         unsigned long addr = (unsigned long)page_address(page);
 422         pgprot_t nx;
 423
 424         pgprot_val(nx) = _PAGE_NX;
 425         return change_page_attr_set(addr, numpages, nx);
 426 }
 427 EXPORT_SYMBOL(set_pages_nx);
 428
 429 int set_pages_ro(struct page *page, int numpages)
 430 {
 431         unsigned long addr = (unsigned long)page_address(page);
 432         pgprot_t rw;
 433
 434         pgprot_val(rw) = _PAGE_RW;
 435         return change_page_attr_clear(addr, numpages, rw);
 436 }
 437
 438 int set_pages_rw(struct page *page, int numpages)
 439 {
 440         unsigned long addr = (unsigned long)page_address(page);
 441         pgprot_t rw;
 442
 443         pgprot_val(rw) = _PAGE_RW;
 444         return change_page_attr_set(addr, numpages, rw);
 445 }
 446
 447 void clflush_cache_range(void *addr, int size)
 448 {
 449         int i;
 450
 451         for (i = 0; i < size; i += boot_cpu_data.x86_clflush_size)
 452                 clflush(addr+i);
 453 }
 454
 455 static void flush_kernel_map(void *arg)
 456 {
 457         /*
 458          * Flush all to work around Errata in early athlons regarding
 459          * large page flushing.
 460          */
 461         __flush_tlb_all();
 462
 463         if (boot_cpu_data.x86_model >= 4)
 464                 wbinvd();
 465 }
 466
 467 void global_flush_tlb(void)
 468 {
 469         BUG_ON(irqs_disabled());
 470
 471         on_each_cpu(flush_kernel_map, NULL, 1, 1);
 472 }
 473 EXPORT_SYMBOL(global_flush_tlb);
 474
 475 #ifdef CONFIG_DEBUG_PAGEALLOC
 476
 477 static int __set_pages_p(struct page *page, int numpages)
 478 {
 479         unsigned long addr = (unsigned long)page_address(page);
 480         return change_page_attr_set(addr, numpages,
 481                                 __pgprot(_PAGE_PRESENT | _PAGE_RW));
 482 }
 483
 484 static int __set_pages_np(struct page *page, int numpages)
 485 {
 486         unsigned long addr = (unsigned long)page_address(page);
 487         return change_page_attr_clear(addr, numpages, __pgprot(_PAGE_PRESENT));
 488 }
 489
 490 void kernel_map_pages(struct page *page, int numpages, int enable)
 491 {
 492         if (PageHighMem(page))
 493                 return;
 494         if (!enable) {
 495                 debug_check_no_locks_freed(page_address(page),
 496                                            numpages * PAGE_SIZE);
 497         }
 498
 499         /*
 500          * If page allocator is not up yet then do not call c_p_a():
 501          */
 502         if (!debug_pagealloc_enabled)
 503                 return;
 504
 505         /*
 506          * The return value is ignored - the calls cannot fail,
 507          * large pages are disabled at boot time:
 508          */
 509         if (enable)
 510                 __set_pages_p(page, numpages);
 511         else
 512                 __set_pages_np(page, numpages);
 513
 514         /*
 515          * We should perform an IPI and flush all tlbs,
 516          * but that can deadlock->flush only current cpu:
 517          */
 518         __flush_tlb_all();
 519 }
 520 #endif
 521
 522 /*
 523  * The testcases use internal knowledge of the implementation that shouldn't
 524  * be exposed to the rest of the kernel. Include these directly here.
 525  */
 526 #ifdef CONFIG_CPA_DEBUG
 527 #include "pageattr-test.c"
 528 #endif