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