1 /*
2 * Copyright (C) 1995 Linus Torvalds
3 * Copyright (C) 2001,2002 Andi Kleen, SuSE Labs.
4 */
5
6 #include <linux/signal.h>
7 #include <linux/sched.h>
8 #include <linux/kernel.h>
9 #include <linux/errno.h>
10 #include <linux/string.h>
11 #include <linux/types.h>
12 #include <linux/ptrace.h>
13 #include <linux/mman.h>
14 #include <linux/mm.h>
15 #include <linux/smp.h>
16 #include <linux/interrupt.h>
17 #include <linux/init.h>
18 #include <linux/tty.h>
19 #include <linux/vt_kern.h> /* For unblank_screen() */
20 #include <linux/compiler.h>
21 #include <linux/highmem.h>
22 #include <linux/bootmem.h> /* for max_low_pfn */
23 #include <linux/vmalloc.h>
24 #include <linux/module.h>
25 #include <linux/kprobes.h>
26 #include <linux/uaccess.h>
27 #include <linux/kdebug.h>
28 #include <linux/ftrace.h>
29
30 #include <asm/system.h>
31 #include <asm/desc.h>
32 #include <asm/segment.h>
33 #include <asm/pgalloc.h>
34 #include <asm/smp.h>
35 #include <asm/tlbflush.h>
36 #include <asm/proto.h>
37 #include <asm-generic/sections.h>
38
39 /*
40 * Page fault error code bits
41 * bit 0 == 0 means no page found, 1 means protection fault
42 * bit 1 == 0 means read, 1 means write
43 * bit 2 == 0 means kernel, 1 means user-mode
44 * bit 3 == 1 means use of reserved bit detected
45 * bit 4 == 1 means fault was an instruction fetch
46 */
47 #define PF_PROT (1<<0)
48 #define PF_WRITE (1<<1)
49 #define PF_USER (1<<2)
50 #define PF_RSVD (1<<3)
51 #define PF_INSTR (1<<4)
52
53 static inline int notify_page_fault(struct pt_regs *regs)
54 {
55 #ifdef CONFIG_KPROBES
56 int ret = 0;
57
58 /* kprobe_running() needs smp_processor_id() */
59 #ifdef CONFIG_X86_32
60 if (!user_mode_vm(regs)) {
61 #else
62 if (!user_mode(regs)) {
63 #endif
64 preempt_disable();
65 if (kprobe_running() && kprobe_fault_handler(regs, 14))
66 ret = 1;
67 preempt_enable();
68 }
69
70 return ret;
71 #else
72 return 0;
73 #endif
74 }
75
76 /*
77 * X86_32
78 * Sometimes AMD Athlon/Opteron CPUs report invalid exceptions on prefetch.
79 * Check that here and ignore it.
80 *
81 * X86_64
82 * Sometimes the CPU reports invalid exceptions on prefetch.
83 * Check that here and ignore it.
84 *
85 * Opcode checker based on code by Richard Brunner
86 */
87 static int is_prefetch(struct pt_regs *regs, unsigned long addr,
88 unsigned long error_code)
89 {
90 unsigned char *instr;
91 int scan_more = 1;
92 int prefetch = 0;
93 unsigned char *max_instr;
94
95 /*
96 * If it was a exec (instruction fetch) fault on NX page, then
97 * do not ignore the fault:
98 */
99 if (error_code & PF_INSTR)
100 return 0;
101
102 instr = (unsigned char *)convert_ip_to_linear(current, regs);
103 max_instr = instr + 15;
104
105 if (user_mode(regs) && instr >= (unsigned char *)TASK_SIZE)
106 return 0;
107
108 while (scan_more && instr < max_instr) {
109 unsigned char opcode;
110 unsigned char instr_hi;
111 unsigned char instr_lo;
112
113 if (probe_kernel_address(instr, opcode))
114 break;
115
116 instr_hi = opcode & 0xf0;
117 instr_lo = opcode & 0x0f;
118 instr++;
119
120 switch (instr_hi) {
121 case 0x20:
122 case 0x30:
123 /*
124 * Values 0x26,0x2E,0x36,0x3E are valid x86 prefixes.
125 * In X86_64 long mode, the CPU will signal invalid
126 * opcode if some of these prefixes are present so
127 * X86_64 will never get here anyway
128 */
129 scan_more = ((instr_lo & 7) == 0x6);
130 break;
131 #ifdef CONFIG_X86_64
132 case 0x40:
133 /*
134 * In AMD64 long mode 0x40..0x4F are valid REX prefixes
135 * Need to figure out under what instruction mode the
136 * instruction was issued. Could check the LDT for lm,
137 * but for now it's good enough to assume that long
138 * mode only uses well known segments or kernel.
139 */
140 scan_more = (!user_mode(regs)) || (regs->cs == __USER_CS);
141 break;
142 #endif
143 case 0x60:
144 /* 0x64 thru 0x67 are valid prefixes in all modes. */
145 scan_more = (instr_lo & 0xC) == 0x4;
146 break;
147 case 0xF0:
148 /* 0xF0, 0xF2, 0xF3 are valid prefixes in all modes. */
149 scan_more = !instr_lo || (instr_lo>>1) == 1;
150 break;
151 case 0x00:
152 /* Prefetch instruction is 0x0F0D or 0x0F18 */
153 scan_more = 0;
154
155 if (probe_kernel_address(instr, opcode))
156 break;
157 prefetch = (instr_lo == 0xF) &&
158 (opcode == 0x0D || opcode == 0x18);
159 break;
160 default:
161 scan_more = 0;
162 break;
163 }
164 }
165 return prefetch;
166 }
167
168 static void force_sig_info_fault(int si_signo, int si_code,
169 unsigned long address, struct task_struct *tsk)
170 {
171 siginfo_t info;
172
173 info.si_signo = si_signo;
174 info.si_errno = 0;
175 info.si_code = si_code;
176 info.si_addr = (void __user *)address;
177 force_sig_info(si_signo, &info, tsk);
178 }
179
180 #ifdef CONFIG_X86_64
181 static int bad_address(void *p)
182 {
183 unsigned long dummy;
184 return probe_kernel_address((unsigned long *)p, dummy);
185 }
186 #endif
187
188 static void dump_pagetable(unsigned long address)
189 {
190 #ifdef CONFIG_X86_32
191 __typeof__(pte_val(__pte(0))) page;
192
193 page = read_cr3();
194 page = ((__typeof__(page) *) __va(page))[address >> PGDIR_SHIFT];
195 #ifdef CONFIG_X86_PAE
196 printk("*pdpt = %016Lx ", page);
197 if ((page >> PAGE_SHIFT) < max_low_pfn
198 && page & _PAGE_PRESENT) {
199 page &= PAGE_MASK;
200 page = ((__typeof__(page) *) __va(page))[(address >> PMD_SHIFT)
201 & (PTRS_PER_PMD - 1)];
202 printk(KERN_CONT "*pde = %016Lx ", page);
203 page &= ~_PAGE_NX;
204 }
205 #else
206 printk("*pde = %08lx ", page);
207 #endif
208
209 /*
210 * We must not directly access the pte in the highpte
211 * case if the page table is located in highmem.
212 * And let's rather not kmap-atomic the pte, just in case
213 * it's allocated already.
214 */
215 if ((page >> PAGE_SHIFT) < max_low_pfn
216 && (page & _PAGE_PRESENT)
217 && !(page & _PAGE_PSE)) {
218 page &= PAGE_MASK;
219 page = ((__typeof__(page) *) __va(page))[(address >> PAGE_SHIFT)
220 & (PTRS_PER_PTE - 1)];
221 printk("*pte = %0*Lx ", sizeof(page)*2, (u64)page);
222 }
223
224 printk("\n");
225 #else /* CONFIG_X86_64 */
226 pgd_t *pgd;
227 pud_t *pud;
228 pmd_t *pmd;
229 pte_t *pte;
230
231 pgd = (pgd_t *)read_cr3();
232
233 pgd = __va((unsigned long)pgd & PHYSICAL_PAGE_MASK);
234 pgd += pgd_index(address);
235 if (bad_address(pgd)) goto bad;
236 printk("PGD %lx ", pgd_val(*pgd));
237 if (!pgd_present(*pgd)) goto ret;
238
239 pud = pud_offset(pgd, address);
240 if (bad_address(pud)) goto bad;
241 printk("PUD %lx ", pud_val(*pud));
242 if (!pud_present(*pud) || pud_large(*pud))
243 goto ret;
244
245 pmd = pmd_offset(pud, address);
246 if (bad_address(pmd)) goto bad;
247 printk("PMD %lx ", pmd_val(*pmd));
248 if (!pmd_present(*pmd) || pmd_large(*pmd)) goto ret;
249
250 pte = pte_offset_kernel(pmd, address);
251 if (bad_address(pte)) goto bad;
252 printk("PTE %lx", pte_val(*pte));
253 ret:
254 printk("\n");
255 return;
256 bad:
257 printk("BAD\n");
258 #endif
259 }
260
261 #ifdef CONFIG_X86_32
262 static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
263 {
264 unsigned index = pgd_index(address);
265 pgd_t *pgd_k;
266 pud_t *pud, *pud_k;
267 pmd_t *pmd, *pmd_k;
268
269 pgd += index;
270 pgd_k = init_mm.pgd + index;
271
272 if (!pgd_present(*pgd_k))
273 return NULL;
274
275 /*
276 * set_pgd(pgd, *pgd_k); here would be useless on PAE
277 * and redundant with the set_pmd() on non-PAE. As would
278 * set_pud.
279 */
280
281 pud = pud_offset(pgd, address);
282 pud_k = pud_offset(pgd_k, address);
283 if (!pud_present(*pud_k))
284 return NULL;
285
286 pmd = pmd_offset(pud, address);
287 pmd_k = pmd_offset(pud_k, address);
288 if (!pmd_present(*pmd_k))
289 return NULL;
290 if (!pmd_present(*pmd)) {
291 set_pmd(pmd, *pmd_k);
292 arch_flush_lazy_mmu_mode();
293 } else
294 BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k));
295 return pmd_k;
296 }
297 #endif
298
299 #ifdef CONFIG_X86_64
300 static const char errata93_warning[] =
301 KERN_ERR "******* Your BIOS seems to not contain a fix for K8 errata #93\n"
302 KERN_ERR "******* Working around it, but it may cause SEGVs or burn power.\n"
303 KERN_ERR "******* Please consider a BIOS update.\n"
304 KERN_ERR "******* Disabling USB legacy in the BIOS may also help.\n";
305 #endif
306
307 /* Workaround for K8 erratum #93 & buggy BIOS.
308 BIOS SMM functions are required to use a specific workaround
309 to avoid corruption of the 64bit RIP register on C stepping K8.
310 A lot of BIOS that didn't get tested properly miss this.
311 The OS sees this as a page fault with the upper 32bits of RIP cleared.
312 Try to work around it here.
313 Note we only handle faults in kernel here.
314 Does nothing for X86_32
315 */
316 static int is_errata93(struct pt_regs *regs, unsigned long address)
317 {
318 #ifdef CONFIG_X86_64
319 static int warned;
320 if (address != regs->ip)
321 return 0;
322 if ((address >> 32) != 0)
323 return 0;
324 address |= 0xffffffffUL << 32;
325 if ((address >= (u64)_stext && address <= (u64)_etext) ||
326 (address >= MODULES_VADDR && address <= MODULES_END)) {
327 if (!warned) {
328 printk(errata93_warning);
329 warned = 1;
330 }
331 regs->ip = address;
332 return 1;
333 }
334 #endif
335 return 0;
336 }
337
338 /*
339 * Work around K8 erratum #100 K8 in compat mode occasionally jumps to illegal
340 * addresses >4GB. We catch this in the page fault handler because these
341 * addresses are not reachable. Just detect this case and return. Any code
342 * segment in LDT is compatibility mode.
343 */
344 static int is_errata100(struct pt_regs *regs, unsigned long address)
345 {
346 #ifdef CONFIG_X86_64
347 if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) &&
348 (address >> 32))
349 return 1;
350 #endif
351 return 0;
352 }
353
354 void do_invalid_op(struct pt_regs *, unsigned long);
355
356 static int is_f00f_bug(struct pt_regs *regs, unsigned long address)
357 {
358 #ifdef CONFIG_X86_F00F_BUG
359 unsigned long nr;
360 /*
361 * Pentium F0 0F C7 C8 bug workaround.
362 */
363 if (boot_cpu_data.f00f_bug) {
364 nr = (address - idt_descr.address) >> 3;
365
366 if (nr == 6) {
367 zap_rt_locks();
368 do_invalid_op(regs, 0);
369 return 1;
370 }
371 }
372 #endif
373 return 0;
374 }
375
376 static void show_fault_oops(struct pt_regs *regs, unsigned long error_code,
377 unsigned long address)
378 {
379 #ifdef CONFIG_X86_32
380 if (!oops_may_print())
381 return;
382 #endif
383
384 #ifdef CONFIG_X86_PAE
385 if (error_code & PF_INSTR) {
386 unsigned int level;
387 pte_t *pte = lookup_address(address, &level);
388
389 if (pte && pte_present(*pte) && !pte_exec(*pte))
390 printk(KERN_CRIT "kernel tried to execute "
391 "NX-protected page - exploit attempt? "
392 "(uid: %d)\n", current->uid);
393 }
394 #endif
395
396 printk(KERN_ALERT "BUG: unable to handle kernel ");
397 if (address < PAGE_SIZE)
398 printk(KERN_CONT "NULL pointer dereference");
399 else
400 printk(KERN_CONT "paging request");
401 #ifdef CONFIG_X86_32
402 printk(KERN_CONT " at %08lx\n", address);
403 #else
404 printk(KERN_CONT " at %016lx\n", address);
405 #endif
406 printk(KERN_ALERT "IP:");
407 printk_address(regs->ip, 1);
408 dump_pagetable(address);
409 }
410
411 #ifdef CONFIG_X86_64
412 static noinline void pgtable_bad(unsigned long address, struct pt_regs *regs,
413 unsigned long error_code)
414 {
415 unsigned long flags = oops_begin();
416 struct task_struct *tsk;
417
418 printk(KERN_ALERT "%s: Corrupted page table at address %lx\n",
419 current->comm, address);
420 dump_pagetable(address);
421 tsk = current;
422 tsk->thread.cr2 = address;
423 tsk->thread.trap_no = 14;
424 tsk->thread.error_code = error_code;
425 if (__die("Bad pagetable", regs, error_code))
426 regs = NULL;
427 oops_end(flags, regs, SIGKILL);
428 }
429 #endif
430
431 static int spurious_fault_check(unsigned long error_code, pte_t *pte)
432 {
433 if ((error_code & PF_WRITE) && !pte_write(*pte))
434 return 0;
435 if ((error_code & PF_INSTR) && !pte_exec(*pte))
436 return 0;
437
438 return 1;
439 }
440
441 /*
442 * Handle a spurious fault caused by a stale TLB entry. This allows
443 * us to lazily refresh the TLB when increasing the permissions of a
444 * kernel page (RO -> RW or NX -> X). Doing it eagerly is very
445 * expensive since that implies doing a full cross-processor TLB
446 * flush, even if no stale TLB entries exist on other processors.
447 * There are no security implications to leaving a stale TLB when
448 * increasing the permissions on a page.
449 */
450 static int spurious_fault(unsigned long address,
451 unsigned long error_code)
452 {
453 pgd_t *pgd;
454 pud_t *pud;
455 pmd_t *pmd;
456 pte_t *pte;
457
458 /* Reserved-bit violation or user access to kernel space? */
459 if (error_code & (PF_USER | PF_RSVD))
460 return 0;
461
462 pgd = init_mm.pgd + pgd_index(address);
463 if (!pgd_present(*pgd))
464 return 0;
465
466 pud = pud_offset(pgd, address);
467 if (!pud_present(*pud))
468 return 0;
469
470 if (pud_large(*pud))
471 return spurious_fault_check(error_code, (pte_t *) pud);
472
473 pmd = pmd_offset(pud, address);
474 if (!pmd_present(*pmd))
475 return 0;
476
477 if (pmd_large(*pmd))
478 return spurious_fault_check(error_code, (pte_t *) pmd);
479
480 pte = pte_offset_kernel(pmd, address);
481 if (!pte_present(*pte))
482 return 0;
483
484 return spurious_fault_check(error_code, pte);
485 }
486
487 /*
488 * X86_32
489 * Handle a fault on the vmalloc or module mapping area
490 *
491 * X86_64
492 * Handle a fault on the vmalloc area
493 *
494 * This assumes no large pages in there.
495 */
496 static int vmalloc_fault(unsigned long address)
497 {
498 #ifdef CONFIG_X86_32
499 unsigned long pgd_paddr;
500 pmd_t *pmd_k;
501 pte_t *pte_k;
502 /*
503 * Synchronize this task's top level page-table
504 * with the 'reference' page table.
505 *
506 * Do _not_ use "current" here. We might be inside
507 * an interrupt in the middle of a task switch..
508 */
509 pgd_paddr = read_cr3();
510 pmd_k = vmalloc_sync_one(__va(pgd_paddr), address);
511 if (!pmd_k)
512 return -1;
513 pte_k = pte_offset_kernel(pmd_k, address);
514 if (!pte_present(*pte_k))
515 return -1;
516 return 0;
517 #else
518 pgd_t *pgd, *pgd_ref;
519 pud_t *pud, *pud_ref;
520 pmd_t *pmd, *pmd_ref;
521 pte_t *pte, *pte_ref;
522
523 /* Make sure we are in vmalloc area */
524 if (!(address >= VMALLOC_START && address < VMALLOC_END))
525 return -1;
526
527 /* Copy kernel mappings over when needed. This can also
528 happen within a race in page table update. In the later
529 case just flush. */
530
531 pgd = pgd_offset(current->mm ?: &init_mm, address);
532 pgd_ref = pgd_offset_k(address);
533 if (pgd_none(*pgd_ref))
534 return -1;
535 if (pgd_none(*pgd))
536 set_pgd(pgd, *pgd_ref);
537 else
538 BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref));
539
540 /* Below here mismatches are bugs because these lower tables
541 are shared */
542
543 pud = pud_offset(pgd, address);
544 pud_ref = pud_offset(pgd_ref, address);
545 if (pud_none(*pud_ref))
546 return -1;
547 if (pud_none(*pud) || pud_page_vaddr(*pud) != pud_page_vaddr(*pud_ref))
548 BUG();
549 pmd = pmd_offset(pud, address);
550 pmd_ref = pmd_offset(pud_ref, address);
551 if (pmd_none(*pmd_ref))
552 return -1;
553 if (pmd_none(*pmd) || pmd_page(*pmd) != pmd_page(*pmd_ref))
554 BUG();
555 pte_ref = pte_offset_kernel(pmd_ref, address);
556 if (!pte_present(*pte_ref))
557 return -1;
558 pte = pte_offset_kernel(pmd, address);
559 /* Don't use pte_page here, because the mappings can point
560 outside mem_map, and the NUMA hash lookup cannot handle
561 that. */
562 if (!pte_present(*pte) || pte_pfn(*pte) != pte_pfn(*pte_ref))
563 BUG();
564 return 0;
565 #endif
566 }
567
568 int show_unhandled_signals = 1;
569
570 /*
571 * This routine handles page faults. It determines the address,
572 * and the problem, and then passes it off to one of the appropriate
573 * routines.
574 */
575 #ifdef CONFIG_X86_64
576 asmlinkage
577 #endif
578 void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
579 {
580 struct task_struct *tsk;
581 struct mm_struct *mm;
582 struct vm_area_struct *vma;
583 unsigned long address;
584 int write, si_code;
585 int fault;
586 #ifdef CONFIG_X86_64
587 unsigned long flags;
588 #endif
589
590 /*
591 * We can fault from pretty much anywhere, with unknown IRQ state.
592 */
593 trace_hardirqs_fixup();
594
595 tsk = current;
596 mm = tsk->mm;
597 prefetchw(&mm->mmap_sem);
598
599 /* get the address */
600 address = read_cr2();
601
602 ftrace_event_fault(regs->ip, error_code, address);
603
604 si_code = SEGV_MAPERR;
605
606 if (notify_page_fault(regs))
607 return;
608
609 /*
610 * We fault-in kernel-space virtual memory on-demand. The
611 * 'reference' page table is init_mm.pgd.
612 *
613 * NOTE! We MUST NOT take any locks for this case. We may
614 * be in an interrupt or a critical region, and should
615 * only copy the information from the master page table,
616 * nothing more.
617 *
618 * This verifies that the fault happens in kernel space
619 * (error_code & 4) == 0, and that the fault was not a
620 * protection error (error_code & 9) == 0.
621 */
622 #ifdef CONFIG_X86_32
623 if (unlikely(address >= TASK_SIZE)) {
624 #else
625 if (unlikely(address >= TASK_SIZE64)) {
626 #endif
627 if (!(error_code & (PF_RSVD|PF_USER|PF_PROT)) &&
628 vmalloc_fault(address) >= 0)
629 return;
630
631 /* Can handle a stale RO->RW TLB */
632 if (spurious_fault(address, error_code))
633 return;
634
635 /*
636 * Don't take the mm semaphore here. If we fixup a prefetch
637 * fault we could otherwise deadlock.
638 */
639 goto bad_area_nosemaphore;
640 }
641
642
643 #ifdef CONFIG_X86_32
644 /* It's safe to allow irq's after cr2 has been saved and the vmalloc
645 fault has been handled. */
646 if (regs->flags & (X86_EFLAGS_IF|VM_MASK))
647 local_irq_enable();
648
649 /*
650 * If we're in an interrupt, have no user context or are running in an
651 * atomic region then we must not take the fault.
652 */
653 if (unlikely(in_atomic() || !mm || current->pagefault_disabled))
654 goto bad_area_nosemaphore;
655 #else /* CONFIG_X86_64 */
656 if (likely(regs->flags & X86_EFLAGS_IF))
657 local_irq_enable();
658
659 if (unlikely(error_code & PF_RSVD))
660 pgtable_bad(address, regs, error_code);
661
662 /*
663 * If we're in an interrupt, have no user context or are running in an
664 * atomic region then we must not take the fault.
665 */
666 if (unlikely(in_atomic() || !mm))
667 goto bad_area_nosemaphore;
668
669 /*
670 * User-mode registers count as a user access even for any
671 * potential system fault or CPU buglet.
672 */
673 if (user_mode_vm(regs))
674 error_code |= PF_USER;
675 again:
676 #endif
677 /* When running in the kernel we expect faults to occur only to
678 * addresses in user space. All other faults represent errors in the
679 * kernel and should generate an OOPS. Unfortunately, in the case of an
680 * erroneous fault occurring in a code path which already holds mmap_sem
681 * we will deadlock attempting to validate the fault against the
682 * address space. Luckily the kernel only validly references user
683 * space from well defined areas of code, which are listed in the
684 * exceptions table.
685 *
686 * As the vast majority of faults will be valid we will only perform
687 * the source reference check when there is a possibility of a deadlock.
688 * Attempt to lock the address space, if we cannot we then validate the
689 * source. If this is invalid we can skip the address space check,
690 * thus avoiding the deadlock.
691 */
692 if (!down_read_trylock(&mm->mmap_sem)) {
693 if ((error_code & PF_USER) == 0 &&
694 !search_exception_tables(regs->ip))
695 goto bad_area_nosemaphore;
696 down_read(&mm->mmap_sem);
697 }
698
699 vma = find_vma(mm, address);
700 if (!vma)
701 goto bad_area;
702 if (vma->vm_start <= address)
703 goto good_area;
704 if (!(vma->vm_flags & VM_GROWSDOWN))
705 goto bad_area;
706 if (error_code & PF_USER) {
707 /*
708 * Accessing the stack below %sp is always a bug.
709 * The large cushion allows instructions like enter
710 * and pusha to work. ("enter $65535,$31" pushes
711 * 32 pointers and then decrements %sp by 65535.)
712 */
713 if (address + 65536 + 32 * sizeof(unsigned long) < regs->sp)
714 goto bad_area;
715 }
716 if (expand_stack(vma, address))
717 goto bad_area;
718 /*
719 * Ok, we have a good vm_area for this memory access, so
720 * we can handle it..
721 */
722 good_area:
723 si_code = SEGV_ACCERR;
724 write = 0;
725 switch (error_code & (PF_PROT|PF_WRITE)) {
726 default: /* 3: write, present */
727 /* fall through */
728 case PF_WRITE: /* write, not present */
729 if (!(vma->vm_flags & VM_WRITE))
730 goto bad_area;
731 write++;
732 break;
733 case PF_PROT: /* read, present */
734 goto bad_area;
735 case 0: /* read, not present */
736 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
737 goto bad_area;
738 }
739
740 #ifdef CONFIG_X86_32
741 survive:
742 #endif
743 /*
744 * If for any reason at all we couldn't handle the fault,
745 * make sure we exit gracefully rather than endlessly redo
746 * the fault.
747 */
748 fault = handle_mm_fault(mm, vma, address, write);
749 if (unlikely(fault & VM_FAULT_ERROR)) {
750 if (fault & VM_FAULT_OOM)
751 goto out_of_memory;
752 else if (fault & VM_FAULT_SIGBUS)
753 goto do_sigbus;
754 BUG();
755 }
756 if (fault & VM_FAULT_MAJOR)
757 tsk->maj_flt++;
758 else
759 tsk->min_flt++;
760
761 #ifdef CONFIG_X86_32
762 /*
763 * Did it hit the DOS screen memory VA from vm86 mode?
764 */
765 if (v8086_mode(regs)) {
766 unsigned long bit = (address - 0xA0000) >> PAGE_SHIFT;
767 if (bit < 32)
768 tsk->thread.screen_bitmap |= 1 << bit;
769 }
770 #endif
771 up_read(&mm->mmap_sem);
772 return;
773
774 /*
775 * Something tried to access memory that isn't in our memory map..
776 * Fix it, but check if it's kernel or user first..
777 */
778 bad_area:
779 up_read(&mm->mmap_sem);
780
781 bad_area_nosemaphore:
782 /* User mode accesses just cause a SIGSEGV */
783 if (error_code & PF_USER) {
784 /*
785 * It's possible to have interrupts off here.
786 */
787 local_irq_enable();
788
789 /*
790 * Valid to do another page fault here because this one came
791 * from user space.
792 */
793 if (is_prefetch(regs, address, error_code))
794 return;
795
796 if (is_errata100(regs, address))
797 return;
798
799 if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
800 printk_ratelimit()) {
801 printk(
802 #ifdef CONFIG_X86_32
803 "%s%s[%d]: segfault at %lx ip %08lx sp %08lx error %lx",
804 #else
805 "%s%s[%d]: segfault at %lx ip %lx sp %lx error %lx",
806 #endif
807 task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
808 tsk->comm, task_pid_nr(tsk), address, regs->ip,
809 regs->sp, error_code);
810 print_vma_addr(" in ", regs->ip);
811 printk("\n");
812 }
813
814 tsk->thread.cr2 = address;
815 /* Kernel addresses are always protection faults */
816 tsk->thread.error_code = error_code | (address >= TASK_SIZE);
817 tsk->thread.trap_no = 14;
818 force_sig_info_fault(SIGSEGV, si_code, address, tsk);
819 return;
820 }
821
822 if (is_f00f_bug(regs, address))
823 return;
824
825 no_context:
826 /* Are we prepared to handle this kernel fault? */
827 if (fixup_exception(regs))
828 return;
829
830 /*
831 * X86_32
832 * Valid to do another page fault here, because if this fault
833 * had been triggered by is_prefetch fixup_exception would have
834 * handled it.
835 *
836 * X86_64
837 * Hall of shame of CPU/BIOS bugs.
838 */
839 if (is_prefetch(regs, address, error_code))
840 return;
841
842 if (is_errata93(regs, address))
843 return;
844
845 /*
846 * Oops. The kernel tried to access some bad page. We'll have to
847 * terminate things with extreme prejudice.
848 */
849 #ifdef CONFIG_X86_32
850 bust_spinlocks(1);
851 #else
852 flags = oops_begin();
853 #endif
854
855 show_fault_oops(regs, error_code, address);
856
857 tsk->thread.cr2 = address;
858 tsk->thread.trap_no = 14;
859 tsk->thread.error_code = error_code;
860
861 #ifdef CONFIG_X86_32
862 die("Oops", regs, error_code);
863 bust_spinlocks(0);
864 do_exit(SIGKILL);
865 #else
866 if (__die("Oops", regs, error_code))
867 regs = NULL;
868 /* Executive summary in case the body of the oops scrolled away */
869 printk(KERN_EMERG "CR2: %016lx\n", address);
870 oops_end(flags, regs, SIGKILL);
871 #endif
872
873 /*
874 * We ran out of memory, or some other thing happened to us that made
875 * us unable to handle the page fault gracefully.
876 */
877 out_of_memory:
878 up_read(&mm->mmap_sem);
879 if (is_global_init(tsk)) {
880 yield();
881 #ifdef CONFIG_X86_32
882 down_read(&mm->mmap_sem);
883 goto survive;
884 #else
885 goto again;
886 #endif
887 }
888
889 printk("VM: killing process %s\n", tsk->comm);
890 if (error_code & PF_USER)
891 do_group_exit(SIGKILL);
892 goto no_context;
893
894 do_sigbus:
895 up_read(&mm->mmap_sem);
896
897 /* Kernel mode? Handle exceptions or die */
898 if (!(error_code & PF_USER))
899 goto no_context;
900 #ifdef CONFIG_X86_32
901 /* User space => ok to do another page fault */
902 if (is_prefetch(regs, address, error_code))
903 return;
904 #endif
905 tsk->thread.cr2 = address;
906 tsk->thread.error_code = error_code;
907 tsk->thread.trap_no = 14;
908 force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk);
909 }
910
911 DEFINE_SPINLOCK(pgd_lock);
912 LIST_HEAD(pgd_list);
913
914 void vmalloc_sync_all(void)
915 {
916 #ifdef CONFIG_X86_32
917 /*
918 * Note that races in the updates of insync and start aren't
919 * problematic: insync can only get set bits added, and updates to
920 * start are only improving performance (without affecting correctness
921 * if undone).
922 */
923 static DECLARE_BITMAP(insync, PTRS_PER_PGD);
924 static unsigned long start = TASK_SIZE;
925 unsigned long address;
926
927 if (SHARED_KERNEL_PMD)
928 return;
929
930 BUILD_BUG_ON(TASK_SIZE & ~PGDIR_MASK);
931 for (address = start; address >= TASK_SIZE; address += PGDIR_SIZE) {
932 if (!test_bit(pgd_index(address), insync)) {
933 unsigned long flags;
934 struct page *page;
935
936 spin_lock_irqsave(&pgd_lock, flags);
937 list_for_each_entry(page, &pgd_list, lru) {
938 if (!vmalloc_sync_one(page_address(page),
939 address))
940 break;
941 }
942 spin_unlock_irqrestore(&pgd_lock, flags);
943 if (!page)
944 set_bit(pgd_index(address), insync);
945 }
946 if (address == start && test_bit(pgd_index(address), insync))
947 start = address + PGDIR_SIZE;
948 }
949 #else /* CONFIG_X86_64 */
950 /*
951 * Note that races in the updates of insync and start aren't
952 * problematic: insync can only get set bits added, and updates to
953 * start are only improving performance (without affecting correctness
954 * if undone).
955 */
956 static DECLARE_BITMAP(insync, PTRS_PER_PGD);
957 static unsigned long start = VMALLOC_START & PGDIR_MASK;
958 unsigned long address;
959
960 for (address = start; address <= VMALLOC_END; address += PGDIR_SIZE) {
961 if (!test_bit(pgd_index(address), insync)) {
962 const pgd_t *pgd_ref = pgd_offset_k(address);
963 unsigned long flags;
964 struct page *page;
965
966 if (pgd_none(*pgd_ref))
967 continue;
968 spin_lock_irqsave(&pgd_lock, flags);
969 list_for_each_entry(page, &pgd_list, lru) {
970 pgd_t *pgd;
971 pgd = (pgd_t *)page_address(page) + pgd_index(address);
972 if (pgd_none(*pgd))
973 set_pgd(pgd, *pgd_ref);
974 else
975 BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref));
976 }
977 spin_unlock_irqrestore(&pgd_lock, flags);
978 set_bit(pgd_index(address), insync);
979 }
980 if (address == start)
981 start = address + PGDIR_SIZE;
982 }
983 /* Check that there is no need to do the same for the modules area. */
984 BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL));
985 BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) ==
986 (__START_KERNEL & PGDIR_MASK)));
987 #endif
988 }
989
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