arch/x86/mm/fault_32.c

   1 /*
   2  *  Copyright (C) 1995  Linus Torvalds
   3  */
   4
   5 #include <linux/signal.h>
   6 #include <linux/sched.h>
   7 #include <linux/kernel.h>
   8 #include <linux/errno.h>
   9 #include <linux/string.h>
  10 #include <linux/types.h>
  11 #include <linux/ptrace.h>
  12 #include <linux/mman.h>
  13 #include <linux/mm.h>
  14 #include <linux/smp.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/init.h>
  17 #include <linux/tty.h>
  18 #include <linux/vt_kern.h>              /* For unblank_screen() */
  19 #include <linux/highmem.h>
  20 #include <linux/bootmem.h>              /* for max_low_pfn */
  21 #include <linux/vmalloc.h>
  22 #include <linux/module.h>
  23 #include <linux/kprobes.h>
  24 #include <linux/uaccess.h>
  25 #include <linux/kdebug.h>
  26
  27 #include <asm/system.h>
  28 #include <asm/desc.h>
  29 #include <asm/segment.h>
  30
  31 /*
  32  * Page fault error code bits
  33  *      bit 0 == 0 means no page found, 1 means protection fault
  34  *      bit 1 == 0 means read, 1 means write
  35  *      bit 2 == 0 means kernel, 1 means user-mode
  36  *      bit 3 == 1 means use of reserved bit detected
  37  *      bit 4 == 1 means fault was an instruction fetch
  38  */
  39 #define PF_PROT         (1<<0)
  40 #define PF_WRITE        (1<<1)
  41 #define PF_USER         (1<<2)
  42 #define PF_RSVD         (1<<3)
  43 #define PF_INSTR        (1<<4)
  44
  45 static inline int notify_page_fault(struct pt_regs *regs)
  46 {
  47 #ifdef CONFIG_KPROBES
  48         int ret = 0;
  49
  50         /* kprobe_running() needs smp_processor_id() */
  51         if (!user_mode_vm(regs)) {
  52                 preempt_disable();
  53                 if (kprobe_running() && kprobe_fault_handler(regs, 14))
  54                         ret = 1;
  55                 preempt_enable();
  56         }
  57
  58         return ret;
  59 #else
  60         return 0;
  61 #endif
  62 }
  63
  64 /*
  65  * X86_32
  66  * Sometimes AMD Athlon/Opteron CPUs report invalid exceptions on prefetch.
  67  * Check that here and ignore it.
  68  *
  69  * X86_64
  70  * Sometimes the CPU reports invalid exceptions on prefetch.
  71  * Check that here and ignore it.
  72  *
  73  * Opcode checker based on code by Richard Brunner
  74  */
  75 static int is_prefetch(struct pt_regs *regs, unsigned long addr,
  76                        unsigned long error_code)
  77 {
  78         unsigned char *instr;
  79         int scan_more = 1;
  80         int prefetch = 0;
  81         unsigned char *max_instr;
  82
  83 #ifdef CONFIG_X86_32
  84         if (unlikely(boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
  85                      boot_cpu_data.x86 >= 6)) {
  86                 /* Catch an obscure case of prefetch inside an NX page. */
  87                 if (nx_enabled && (error_code & PF_INSTR))
  88                         return 0;
  89         } else {
  90                 return 0;
  91         }
  92 #else
  93         /* If it was a exec fault ignore */
  94         if (error_code & PF_INSTR)
  95                 return 0;
  96 #endif
  97
  98         instr = (unsigned char *)convert_ip_to_linear(current, regs);
  99         max_instr = instr + 15;
 100
 101         if (user_mode(regs) && instr >= (unsigned char *)TASK_SIZE)
 102                 return 0;
 103
 104         while (scan_more && instr < max_instr) {
 105                 unsigned char opcode;
 106                 unsigned char instr_hi;
 107                 unsigned char instr_lo;
 108
 109                 if (probe_kernel_address(instr, opcode))
 110                         break;
 111
 112                 instr_hi = opcode & 0xf0;
 113                 instr_lo = opcode & 0x0f;
 114                 instr++;
 115
 116                 switch (instr_hi) {
 117                 case 0x20:
 118                 case 0x30:
 119                         /*
 120                          * Values 0x26,0x2E,0x36,0x3E are valid x86 prefixes.
 121                          * In X86_64 long mode, the CPU will signal invalid
 122                          * opcode if some of these prefixes are present so
 123                          * X86_64 will never get here anyway
 124                          */
 125                         scan_more = ((instr_lo & 7) == 0x6);
 126                         break;
 127 #ifdef CONFIG_X86_64
 128                 case 0x40:
 129                         /*
 130                          * In AMD64 long mode 0x40..0x4F are valid REX prefixes
 131                          * Need to figure out under what instruction mode the
 132                          * instruction was issued. Could check the LDT for lm,
 133                          * but for now it's good enough to assume that long
 134                          * mode only uses well known segments or kernel.
 135                          */
 136                         scan_more = (!user_mode(regs)) || (regs->cs == __USER_CS);
 137                         break;
 138 #endif
 139                 case 0x60:
 140                         /* 0x64 thru 0x67 are valid prefixes in all modes. */
 141                         scan_more = (instr_lo & 0xC) == 0x4;
 142                         break;
 143                 case 0xF0:
 144                         /* 0xF0, 0xF2, 0xF3 are valid prefixes in all modes. */
 145                         scan_more = !instr_lo || (instr_lo>>1) == 1;
 146                         break;
 147                 case 0x00:
 148                         /* Prefetch instruction is 0x0F0D or 0x0F18 */
 149                         scan_more = 0;
 150
 151                         if (probe_kernel_address(instr, opcode))
 152                                 break;
 153                         prefetch = (instr_lo == 0xF) &&
 154                                 (opcode == 0x0D || opcode == 0x18);
 155                         break;
 156                 default:
 157                         scan_more = 0;
 158                         break;
 159                 }
 160         }
 161         return prefetch;
 162 }
 163
 164 static void force_sig_info_fault(int si_signo, int si_code,
 165         unsigned long address, struct task_struct *tsk)
 166 {
 167         siginfo_t info;
 168
 169         info.si_signo = si_signo;
 170         info.si_errno = 0;
 171         info.si_code = si_code;
 172         info.si_addr = (void __user *)address;
 173         force_sig_info(si_signo, &info, tsk);
 174 }
 175
 176 void dump_pagetable(unsigned long address)
 177 {
 178         __typeof__(pte_val(__pte(0))) page;
 179
 180         page = read_cr3();
 181         page = ((__typeof__(page) *) __va(page))[address >> PGDIR_SHIFT];
 182 #ifdef CONFIG_X86_PAE
 183         printk("*pdpt = %016Lx ", page);
 184         if ((page >> PAGE_SHIFT) < max_low_pfn
 185             && page & _PAGE_PRESENT) {
 186                 page &= PAGE_MASK;
 187                 page = ((__typeof__(page) *) __va(page))[(address >> PMD_SHIFT)
 188                                                          & (PTRS_PER_PMD - 1)];
 189                 printk(KERN_CONT "*pde = %016Lx ", page);
 190                 page &= ~_PAGE_NX;
 191         }
 192 #else
 193         printk("*pde = %08lx ", page);
 194 #endif
 195
 196         /*
 197          * We must not directly access the pte in the highpte
 198          * case if the page table is located in highmem.
 199          * And let's rather not kmap-atomic the pte, just in case
 200          * it's allocated already.
 201          */
 202         if ((page >> PAGE_SHIFT) < max_low_pfn
 203             && (page & _PAGE_PRESENT)
 204             && !(page & _PAGE_PSE)) {
 205                 page &= PAGE_MASK;
 206                 page = ((__typeof__(page) *) __va(page))[(address >> PAGE_SHIFT)
 207                                                          & (PTRS_PER_PTE - 1)];
 208                 printk("*pte = %0*Lx ", sizeof(page)*2, (u64)page);
 209         }
 210
 211         printk("\n");
 212 }
 213
 214 void do_invalid_op(struct pt_regs *, unsigned long);
 215
 216 static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
 217 {
 218         unsigned index = pgd_index(address);
 219         pgd_t *pgd_k;
 220         pud_t *pud, *pud_k;
 221         pmd_t *pmd, *pmd_k;
 222
 223         pgd += index;
 224         pgd_k = init_mm.pgd + index;
 225
 226         if (!pgd_present(*pgd_k))
 227                 return NULL;
 228
 229         /*
 230          * set_pgd(pgd, *pgd_k); here would be useless on PAE
 231          * and redundant with the set_pmd() on non-PAE. As would
 232          * set_pud.
 233          */
 234
 235         pud = pud_offset(pgd, address);
 236         pud_k = pud_offset(pgd_k, address);
 237         if (!pud_present(*pud_k))
 238                 return NULL;
 239
 240         pmd = pmd_offset(pud, address);
 241         pmd_k = pmd_offset(pud_k, address);
 242         if (!pmd_present(*pmd_k))
 243                 return NULL;
 244         if (!pmd_present(*pmd)) {
 245                 set_pmd(pmd, *pmd_k);
 246                 arch_flush_lazy_mmu_mode();
 247         } else
 248                 BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k));
 249         return pmd_k;
 250 }
 251
 252 #ifdef CONFIG_X86_64
 253 static const char errata93_warning[] =
 254 KERN_ERR "******* Your BIOS seems to not contain a fix for K8 errata #93\n"
 255 KERN_ERR "******* Working around it, but it may cause SEGVs or burn power.\n"
 256 KERN_ERR "******* Please consider a BIOS update.\n"
 257 KERN_ERR "******* Disabling USB legacy in the BIOS may also help.\n";
 258 #endif
 259
 260 /* Workaround for K8 erratum #93 & buggy BIOS.
 261    BIOS SMM functions are required to use a specific workaround
 262    to avoid corruption of the 64bit RIP register on C stepping K8.
 263    A lot of BIOS that didn't get tested properly miss this.
 264    The OS sees this as a page fault with the upper 32bits of RIP cleared.
 265    Try to work around it here.
 266    Note we only handle faults in kernel here.
 267    Does nothing for X86_32
 268  */
 269 static int is_errata93(struct pt_regs *regs, unsigned long address)
 270 {
 271 #ifdef CONFIG_X86_64
 272         static int warned;
 273         if (address != regs->ip)
 274                 return 0;
 275         if ((address >> 32) != 0)
 276                 return 0;
 277         address |= 0xffffffffUL << 32;
 278         if ((address >= (u64)_stext && address <= (u64)_etext) ||
 279             (address >= MODULES_VADDR && address <= MODULES_END)) {
 280                 if (!warned) {
 281                         printk(errata93_warning);
 282                         warned = 1;
 283                 }
 284                 regs->ip = address;
 285                 return 1;
 286         }
 287 #endif
 288         return 0;
 289 }
 290
 291
 292 /*
 293  * Handle a fault on the vmalloc or module mapping area
 294  *
 295  * This assumes no large pages in there.
 296  */
 297 static inline int vmalloc_fault(unsigned long address)
 298 {
 299 #ifdef CONFIG_X86_32
 300         unsigned long pgd_paddr;
 301         pmd_t *pmd_k;
 302         pte_t *pte_k;
 303         /*
 304          * Synchronize this task's top level page-table
 305          * with the 'reference' page table.
 306          *
 307          * Do _not_ use "current" here. We might be inside
 308          * an interrupt in the middle of a task switch..
 309          */
 310         pgd_paddr = read_cr3();
 311         pmd_k = vmalloc_sync_one(__va(pgd_paddr), address);
 312         if (!pmd_k)
 313                 return -1;
 314         pte_k = pte_offset_kernel(pmd_k, address);
 315         if (!pte_present(*pte_k))
 316                 return -1;
 317         return 0;
 318 #else
 319         pgd_t *pgd, *pgd_ref;
 320         pud_t *pud, *pud_ref;
 321         pmd_t *pmd, *pmd_ref;
 322         pte_t *pte, *pte_ref;
 323
 324         /* Copy kernel mappings over when needed. This can also
 325            happen within a race in page table update. In the later
 326            case just flush. */
 327
 328         pgd = pgd_offset(current->mm ?: &init_mm, address);
 329         pgd_ref = pgd_offset_k(address);
 330         if (pgd_none(*pgd_ref))
 331                 return -1;
 332         if (pgd_none(*pgd))
 333                 set_pgd(pgd, *pgd_ref);
 334         else
 335                 BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref));
 336
 337         /* Below here mismatches are bugs because these lower tables
 338            are shared */
 339
 340         pud = pud_offset(pgd, address);
 341         pud_ref = pud_offset(pgd_ref, address);
 342         if (pud_none(*pud_ref))
 343                 return -1;
 344         if (pud_none(*pud) || pud_page_vaddr(*pud) != pud_page_vaddr(*pud_ref))
 345                 BUG();
 346         pmd = pmd_offset(pud, address);
 347         pmd_ref = pmd_offset(pud_ref, address);
 348         if (pmd_none(*pmd_ref))
 349                 return -1;
 350         if (pmd_none(*pmd) || pmd_page(*pmd) != pmd_page(*pmd_ref))
 351                 BUG();
 352         pte_ref = pte_offset_kernel(pmd_ref, address);
 353         if (!pte_present(*pte_ref))
 354                 return -1;
 355         pte = pte_offset_kernel(pmd, address);
 356         /* Don't use pte_page here, because the mappings can point
 357            outside mem_map, and the NUMA hash lookup cannot handle
 358            that. */
 359         if (!pte_present(*pte) || pte_pfn(*pte) != pte_pfn(*pte_ref))
 360                 BUG();
 361         return 0;
 362 #endif
 363 }
 364
 365 int show_unhandled_signals = 1;
 366
 367 /*
 368  * This routine handles page faults.  It determines the address,
 369  * and the problem, and then passes it off to one of the appropriate
 370  * routines.
 371  */
 372 void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
 373 {
 374         struct task_struct *tsk;
 375         struct mm_struct *mm;
 376         struct vm_area_struct *vma;
 377         unsigned long address;
 378         int write, si_code;
 379         int fault;
 380
 381         /*
 382          * We can fault from pretty much anywhere, with unknown IRQ state.
 383          */
 384         trace_hardirqs_fixup();
 385
 386         tsk = current;
 387         mm = tsk->mm;
 388         prefetchw(&mm->mmap_sem);
 389
 390         /* get the address */
 391         address = read_cr2();
 392
 393         si_code = SEGV_MAPERR;
 394
 395         if (notify_page_fault(regs))
 396                 return;
 397
 398         /*
 399          * We fault-in kernel-space virtual memory on-demand. The
 400          * 'reference' page table is init_mm.pgd.
 401          *
 402          * NOTE! We MUST NOT take any locks for this case. We may
 403          * be in an interrupt or a critical region, and should
 404          * only copy the information from the master page table,
 405          * nothing more.
 406          *
 407          * This verifies that the fault happens in kernel space
 408          * (error_code & 4) == 0, and that the fault was not a
 409          * protection error (error_code & 9) == 0.
 410          */
 411         if (unlikely(address >= TASK_SIZE)) {
 412                 if (!(error_code & (PF_RSVD|PF_USER|PF_PROT)) &&
 413                     vmalloc_fault(address) >= 0)
 414                         return;
 415                 /*
 416                  * Don't take the mm semaphore here. If we fixup a prefetch
 417                  * fault we could otherwise deadlock.
 418                  */
 419                 goto bad_area_nosemaphore;
 420         }
 421
 422         /* It's safe to allow irq's after cr2 has been saved and the vmalloc
 423            fault has been handled. */
 424         if (regs->flags & (X86_EFLAGS_IF|VM_MASK))
 425                 local_irq_enable();
 426
 427         /*
 428          * If we're in an interrupt, have no user context or are running in an
 429          * atomic region then we must not take the fault.
 430          */
 431         if (in_atomic() || !mm)
 432                 goto bad_area_nosemaphore;
 433
 434         /* When running in the kernel we expect faults to occur only to
 435          * addresses in user space.  All other faults represent errors in the
 436          * kernel and should generate an OOPS.  Unfortunately, in the case of an
 437          * erroneous fault occurring in a code path which already holds mmap_sem
 438          * we will deadlock attempting to validate the fault against the
 439          * address space.  Luckily the kernel only validly references user
 440          * space from well defined areas of code, which are listed in the
 441          * exceptions table.
 442          *
 443          * As the vast majority of faults will be valid we will only perform
 444          * the source reference check when there is a possibility of a deadlock.
 445          * Attempt to lock the address space, if we cannot we then validate the
 446          * source.  If this is invalid we can skip the address space check,
 447          * thus avoiding the deadlock.
 448          */
 449         if (!down_read_trylock(&mm->mmap_sem)) {
 450                 if ((error_code & PF_USER) == 0 &&
 451                     !search_exception_tables(regs->ip))
 452                         goto bad_area_nosemaphore;
 453                 down_read(&mm->mmap_sem);
 454         }
 455
 456         vma = find_vma(mm, address);
 457         if (!vma)
 458                 goto bad_area;
 459         if (vma->vm_start <= address)
 460                 goto good_area;
 461         if (!(vma->vm_flags & VM_GROWSDOWN))
 462                 goto bad_area;
 463         if (error_code & PF_USER) {
 464                 /*
 465                  * Accessing the stack below %sp is always a bug.
 466                  * The large cushion allows instructions like enter
 467                  * and pusha to work.  ("enter $65535,$31" pushes
 468                  * 32 pointers and then decrements %sp by 65535.)
 469                  */
 470                 if (address + 65536 + 32 * sizeof(unsigned long) < regs->sp)
 471                         goto bad_area;
 472         }
 473         if (expand_stack(vma, address))
 474                 goto bad_area;
 475 /*
 476  * Ok, we have a good vm_area for this memory access, so
 477  * we can handle it..
 478  */
 479 good_area:
 480         si_code = SEGV_ACCERR;
 481         write = 0;
 482         switch (error_code & (PF_PROT|PF_WRITE)) {
 483         default:        /* 3: write, present */
 484                 /* fall through */
 485         case PF_WRITE:          /* write, not present */
 486                 if (!(vma->vm_flags & VM_WRITE))
 487                         goto bad_area;
 488                 write++;
 489                 break;
 490         case PF_PROT:           /* read, present */
 491                 goto bad_area;
 492         case 0:                 /* read, not present */
 493                 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
 494                         goto bad_area;
 495         }
 496
 497  survive:
 498         /*
 499          * If for any reason at all we couldn't handle the fault,
 500          * make sure we exit gracefully rather than endlessly redo
 501          * the fault.
 502          */
 503         fault = handle_mm_fault(mm, vma, address, write);
 504         if (unlikely(fault & VM_FAULT_ERROR)) {
 505                 if (fault & VM_FAULT_OOM)
 506                         goto out_of_memory;
 507                 else if (fault & VM_FAULT_SIGBUS)
 508                         goto do_sigbus;
 509                 BUG();
 510         }
 511         if (fault & VM_FAULT_MAJOR)
 512                 tsk->maj_flt++;
 513         else
 514                 tsk->min_flt++;
 515
 516 #ifdef CONFIG_X86_32
 517         /*
 518          * Did it hit the DOS screen memory VA from vm86 mode?
 519          */
 520         if (v8086_mode(regs)) {
 521                 unsigned long bit = (address - 0xA0000) >> PAGE_SHIFT;
 522                 if (bit < 32)
 523                         tsk->thread.screen_bitmap |= 1 << bit;
 524         }
 525 #endif
 526         up_read(&mm->mmap_sem);
 527         return;
 528
 529 /*
 530  * Something tried to access memory that isn't in our memory map..
 531  * Fix it, but check if it's kernel or user first..
 532  */
 533 bad_area:
 534         up_read(&mm->mmap_sem);
 535
 536 bad_area_nosemaphore:
 537         /* User mode accesses just cause a SIGSEGV */
 538         if (error_code & PF_USER) {
 539                 /*
 540                  * It's possible to have interrupts off here.
 541                  */
 542                 local_irq_enable();
 543
 544                 /*
 545                  * Valid to do another page fault here because this one came
 546                  * from user space.
 547                  */
 548                 if (is_prefetch(regs, address, error_code))
 549                         return;
 550
 551                 if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
 552                     printk_ratelimit()) {
 553                         printk(
 554 #ifdef CONFIG_X86_32
 555                         "%s%s[%d]: segfault at %lx ip %08lx sp %08lx error %lx",
 556 #else
 557                         "%s%s[%d]: segfault at %lx ip %lx sp %lx error %lx",
 558 #endif
 559                         task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
 560                         tsk->comm, task_pid_nr(tsk), address, regs->ip,
 561                         regs->sp, error_code);
 562                         print_vma_addr(" in ", regs->ip);
 563                         printk("\n");
 564                 }
 565                 tsk->thread.cr2 = address;
 566                 /* Kernel addresses are always protection faults */
 567                 tsk->thread.error_code = error_code | (address >= TASK_SIZE);
 568                 tsk->thread.trap_no = 14;
 569                 force_sig_info_fault(SIGSEGV, si_code, address, tsk);
 570                 return;
 571         }
 572
 573 #ifdef CONFIG_X86_F00F_BUG
 574         /*
 575          * Pentium F0 0F C7 C8 bug workaround.
 576          */
 577         if (boot_cpu_data.f00f_bug) {
 578                 unsigned long nr;
 579
 580                 nr = (address - idt_descr.address) >> 3;
 581
 582                 if (nr == 6) {
 583                         do_invalid_op(regs, 0);
 584                         return;
 585                 }
 586         }
 587 #endif
 588
 589 no_context:
 590         /* Are we prepared to handle this kernel fault?  */
 591         if (fixup_exception(regs))
 592                 return;
 593
 594         /*
 595          * Valid to do another page fault here, because if this fault
 596          * had been triggered by is_prefetch fixup_exception would have
 597          * handled it.
 598          */
 599         if (is_prefetch(regs, address, error_code))
 600                 return;
 601
 602         if (is_errata93(regs, address))
 603                 return;
 604
 605 /*
 606  * Oops. The kernel tried to access some bad page. We'll have to
 607  * terminate things with extreme prejudice.
 608  */
 609
 610         bust_spinlocks(1);
 611
 612         if (oops_may_print()) {
 613
 614 #ifdef CONFIG_X86_PAE
 615                 if (error_code & PF_INSTR) {
 616                         int level;
 617                         pte_t *pte = lookup_address(address, &level);
 618
 619                         if (pte && pte_present(*pte) && !pte_exec(*pte))
 620                                 printk(KERN_CRIT "kernel tried to execute "
 621                                         "NX-protected page - exploit attempt? "
 622                                         "(uid: %d)\n", current->uid);
 623                 }
 624 #endif
 625                 if (address < PAGE_SIZE)
 626                         printk(KERN_ALERT "BUG: unable to handle kernel NULL "
 627                                         "pointer dereference");
 628                 else
 629                         printk(KERN_ALERT "BUG: unable to handle kernel paging"
 630                                         " request");
 631                 printk(" at virtual address %08lx\n", address);
 632                 printk(KERN_ALERT "printing ip: %08lx ", regs->ip);
 633
 634                 dump_pagetable(address);
 635         }
 636
 637         tsk->thread.cr2 = address;
 638         tsk->thread.trap_no = 14;
 639         tsk->thread.error_code = error_code;
 640         die("Oops", regs, error_code);
 641         bust_spinlocks(0);
 642         do_exit(SIGKILL);
 643
 644 /*
 645  * We ran out of memory, or some other thing happened to us that made
 646  * us unable to handle the page fault gracefully.
 647  */
 648 out_of_memory:
 649         up_read(&mm->mmap_sem);
 650         if (is_global_init(tsk)) {
 651                 yield();
 652                 down_read(&mm->mmap_sem);
 653                 goto survive;
 654         }
 655         printk("VM: killing process %s\n", tsk->comm);
 656         if (error_code & PF_USER)
 657                 do_group_exit(SIGKILL);
 658         goto no_context;
 659
 660 do_sigbus:
 661         up_read(&mm->mmap_sem);
 662
 663         /* Kernel mode? Handle exceptions or die */
 664         if (!(error_code & PF_USER))
 665                 goto no_context;
 666
 667         /* User space => ok to do another page fault */
 668         if (is_prefetch(regs, address, error_code))
 669                 return;
 670
 671         tsk->thread.cr2 = address;
 672         tsk->thread.error_code = error_code;
 673         tsk->thread.trap_no = 14;
 674         force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk);
 675 }
 676
 677 void vmalloc_sync_all(void)
 678 {
 679         /*
 680          * Note that races in the updates of insync and start aren't
 681          * problematic: insync can only get set bits added, and updates to
 682          * start are only improving performance (without affecting correctness
 683          * if undone).
 684          */
 685         static DECLARE_BITMAP(insync, PTRS_PER_PGD);
 686         static unsigned long start = TASK_SIZE;
 687         unsigned long address;
 688
 689         if (SHARED_KERNEL_PMD)
 690                 return;
 691
 692         BUILD_BUG_ON(TASK_SIZE & ~PGDIR_MASK);
 693         for (address = start; address >= TASK_SIZE; address += PGDIR_SIZE) {
 694                 if (!test_bit(pgd_index(address), insync)) {
 695                         unsigned long flags;
 696                         struct page *page;
 697
 698                         spin_lock_irqsave(&pgd_lock, flags);
 699                         for (page = pgd_list; page; page =
 700                                         (struct page *)page->index)
 701                                 if (!vmalloc_sync_one(page_address(page),
 702                                                                 address)) {
 703                                         BUG_ON(page != pgd_list);
 704                                         break;
 705                                 }
 706                         spin_unlock_irqrestore(&pgd_lock, flags);
 707                         if (!page)
 708                                 set_bit(pgd_index(address), insync);
 709                 }
 710                 if (address == start && test_bit(pgd_index(address), insync))
 711                         start = address + PGDIR_SIZE;
 712         }
 713 }