1
2
3
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/mmiotrace.h>
14#include <linux/mman.h>
15#include <linux/mm.h>
16#include <linux/smp.h>
17#include <linux/interrupt.h>
18#include <linux/init.h>
19#include <linux/tty.h>
20#include <linux/vt_kern.h>
21#include <linux/compiler.h>
22#include <linux/highmem.h>
23#include <linux/bootmem.h>
24#include <linux/vmalloc.h>
25#include <linux/module.h>
26#include <linux/kprobes.h>
27#include <linux/uaccess.h>
28#include <linux/kdebug.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#include <asm/traps.h>
39
40
41
42
43
44
45
46
47
48#define PF_PROT (1<<0)
49#define PF_WRITE (1<<1)
50#define PF_USER (1<<2)
51#define PF_RSVD (1<<3)
52#define PF_INSTR (1<<4)
53
54static inline int kmmio_fault(struct pt_regs *regs, unsigned long addr)
55{
56#ifdef CONFIG_MMIOTRACE_HOOKS
57 if (unlikely(is_kmmio_active()))
58 if (kmmio_handler(regs, addr) == 1)
59 return -1;
60#endif
61 return 0;
62}
63
64static inline int notify_page_fault(struct pt_regs *regs)
65{
66#ifdef CONFIG_KPROBES
67 int ret = 0;
68
69
70 if (!user_mode_vm(regs)) {
71 preempt_disable();
72 if (kprobe_running() && kprobe_fault_handler(regs, 14))
73 ret = 1;
74 preempt_enable();
75 }
76
77 return ret;
78#else
79 return 0;
80#endif
81}
82
83
84
85
86
87
88
89
90
91
92
93
94static int is_prefetch(struct pt_regs *regs, unsigned long addr,
95 unsigned long error_code)
96{
97 unsigned char *instr;
98 int scan_more = 1;
99 int prefetch = 0;
100 unsigned char *max_instr;
101
102
103
104
105
106 if (error_code & PF_INSTR)
107 return 0;
108
109 instr = (unsigned char *)convert_ip_to_linear(current, regs);
110 max_instr = instr + 15;
111
112 if (user_mode(regs) && instr >= (unsigned char *)TASK_SIZE)
113 return 0;
114
115 while (scan_more && instr < max_instr) {
116 unsigned char opcode;
117 unsigned char instr_hi;
118 unsigned char instr_lo;
119
120 if (probe_kernel_address(instr, opcode))
121 break;
122
123 instr_hi = opcode & 0xf0;
124 instr_lo = opcode & 0x0f;
125 instr++;
126
127 switch (instr_hi) {
128 case 0x20:
129 case 0x30:
130
131
132
133
134
135
136 scan_more = ((instr_lo & 7) == 0x6);
137 break;
138#ifdef CONFIG_X86_64
139 case 0x40:
140
141
142
143
144
145
146
147 scan_more = (!user_mode(regs)) || (regs->cs == __USER_CS);
148 break;
149#endif
150 case 0x60:
151
152 scan_more = (instr_lo & 0xC) == 0x4;
153 break;
154 case 0xF0:
155
156 scan_more = !instr_lo || (instr_lo>>1) == 1;
157 break;
158 case 0x00:
159
160 scan_more = 0;
161
162 if (probe_kernel_address(instr, opcode))
163 break;
164 prefetch = (instr_lo == 0xF) &&
165 (opcode == 0x0D || opcode == 0x18);
166 break;
167 default:
168 scan_more = 0;
169 break;
170 }
171 }
172 return prefetch;
173}
174
175static void force_sig_info_fault(int si_signo, int si_code,
176 unsigned long address, struct task_struct *tsk)
177{
178 siginfo_t info;
179
180 info.si_signo = si_signo;
181 info.si_errno = 0;
182 info.si_code = si_code;
183 info.si_addr = (void __user *)address;
184 force_sig_info(si_signo, &info, tsk);
185}
186
187#ifdef CONFIG_X86_64
188static int bad_address(void *p)
189{
190 unsigned long dummy;
191 return probe_kernel_address((unsigned long *)p, dummy);
192}
193#endif
194
195static void dump_pagetable(unsigned long address)
196{
197#ifdef CONFIG_X86_32
198 __typeof__(pte_val(__pte(0))) page;
199
200 page = read_cr3();
201 page = ((__typeof__(page) *) __va(page))[address >> PGDIR_SHIFT];
202#ifdef CONFIG_X86_PAE
203 printk("*pdpt = %016Lx ", page);
204 if ((page >> PAGE_SHIFT) < max_low_pfn
205 && page & _PAGE_PRESENT) {
206 page &= PAGE_MASK;
207 page = ((__typeof__(page) *) __va(page))[(address >> PMD_SHIFT)
208 & (PTRS_PER_PMD - 1)];
209 printk(KERN_CONT "*pde = %016Lx ", page);
210 page &= ~_PAGE_NX;
211 }
212#else
213 printk("*pde = %08lx ", page);
214#endif
215
216
217
218
219
220
221
222 if ((page >> PAGE_SHIFT) < max_low_pfn
223 && (page & _PAGE_PRESENT)
224 && !(page & _PAGE_PSE)) {
225 page &= PAGE_MASK;
226 page = ((__typeof__(page) *) __va(page))[(address >> PAGE_SHIFT)
227 & (PTRS_PER_PTE - 1)];
228 printk("*pte = %0*Lx ", sizeof(page)*2, (u64)page);
229 }
230
231 printk("\n");
232#else
233 pgd_t *pgd;
234 pud_t *pud;
235 pmd_t *pmd;
236 pte_t *pte;
237
238 pgd = (pgd_t *)read_cr3();
239
240 pgd = __va((unsigned long)pgd & PHYSICAL_PAGE_MASK);
241 pgd += pgd_index(address);
242 if (bad_address(pgd)) goto bad;
243 printk("PGD %lx ", pgd_val(*pgd));
244 if (!pgd_present(*pgd)) goto ret;
245
246 pud = pud_offset(pgd, address);
247 if (bad_address(pud)) goto bad;
248 printk("PUD %lx ", pud_val(*pud));
249 if (!pud_present(*pud) || pud_large(*pud))
250 goto ret;
251
252 pmd = pmd_offset(pud, address);
253 if (bad_address(pmd)) goto bad;
254 printk("PMD %lx ", pmd_val(*pmd));
255 if (!pmd_present(*pmd) || pmd_large(*pmd)) goto ret;
256
257 pte = pte_offset_kernel(pmd, address);
258 if (bad_address(pte)) goto bad;
259 printk("PTE %lx", pte_val(*pte));
260ret:
261 printk("\n");
262 return;
263bad:
264 printk("BAD\n");
265#endif
266}
267
268#ifdef CONFIG_X86_32
269static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
270{
271 unsigned index = pgd_index(address);
272 pgd_t *pgd_k;
273 pud_t *pud, *pud_k;
274 pmd_t *pmd, *pmd_k;
275
276 pgd += index;
277 pgd_k = init_mm.pgd + index;
278
279 if (!pgd_present(*pgd_k))
280 return NULL;
281
282
283
284
285
286
287
288 pud = pud_offset(pgd, address);
289 pud_k = pud_offset(pgd_k, address);
290 if (!pud_present(*pud_k))
291 return NULL;
292
293 pmd = pmd_offset(pud, address);
294 pmd_k = pmd_offset(pud_k, address);
295 if (!pmd_present(*pmd_k))
296 return NULL;
297 if (!pmd_present(*pmd)) {
298 set_pmd(pmd, *pmd_k);
299 arch_flush_lazy_mmu_mode();
300 } else
301 BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k));
302 return pmd_k;
303}
304#endif
305
306#ifdef CONFIG_X86_64
307static const char errata93_warning[] =
308KERN_ERR "******* Your BIOS seems to not contain a fix for K8 errata #93\n"
309KERN_ERR "******* Working around it, but it may cause SEGVs or burn power.\n"
310KERN_ERR "******* Please consider a BIOS update.\n"
311KERN_ERR "******* Disabling USB legacy in the BIOS may also help.\n";
312#endif
313
314
315
316
317
318
319
320
321
322
323static int is_errata93(struct pt_regs *regs, unsigned long address)
324{
325#ifdef CONFIG_X86_64
326 static int warned;
327 if (address != regs->ip)
328 return 0;
329 if ((address >> 32) != 0)
330 return 0;
331 address |= 0xffffffffUL << 32;
332 if ((address >= (u64)_stext && address <= (u64)_etext) ||
333 (address >= MODULES_VADDR && address <= MODULES_END)) {
334 if (!warned) {
335 printk(errata93_warning);
336 warned = 1;
337 }
338 regs->ip = address;
339 return 1;
340 }
341#endif
342 return 0;
343}
344
345
346
347
348
349
350
351static int is_errata100(struct pt_regs *regs, unsigned long address)
352{
353#ifdef CONFIG_X86_64
354 if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) &&
355 (address >> 32))
356 return 1;
357#endif
358 return 0;
359}
360
361static int is_f00f_bug(struct pt_regs *regs, unsigned long address)
362{
363#ifdef CONFIG_X86_F00F_BUG
364 unsigned long nr;
365
366
367
368 if (boot_cpu_data.f00f_bug) {
369 nr = (address - idt_descr.address) >> 3;
370
371 if (nr == 6) {
372 do_invalid_op(regs, 0);
373 return 1;
374 }
375 }
376#endif
377 return 0;
378}
379
380static void show_fault_oops(struct pt_regs *regs, unsigned long error_code,
381 unsigned long address)
382{
383#ifdef CONFIG_X86_32
384 if (!oops_may_print())
385 return;
386#endif
387
388#ifdef CONFIG_X86_PAE
389 if (error_code & PF_INSTR) {
390 unsigned int level;
391 pte_t *pte = lookup_address(address, &level);
392
393 if (pte && pte_present(*pte) && !pte_exec(*pte))
394 printk(KERN_CRIT "kernel tried to execute "
395 "NX-protected page - exploit attempt? "
396 "(uid: %d)\n", current->uid);
397 }
398#endif
399
400 printk(KERN_ALERT "BUG: unable to handle kernel ");
401 if (address < PAGE_SIZE)
402 printk(KERN_CONT "NULL pointer dereference");
403 else
404 printk(KERN_CONT "paging request");
405 printk(KERN_CONT " at %p\n", (void *) address);
406 printk(KERN_ALERT "IP:");
407 printk_address(regs->ip, 1);
408 dump_pagetable(address);
409}
410
411#ifdef CONFIG_X86_64
412static 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
431static 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
443
444
445
446
447
448
449
450static 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
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
489
490
491
492
493
494
495
496static 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
504 if (!(address >= VMALLOC_START && address < VMALLOC_END))
505 return -1;
506
507
508
509
510
511
512
513
514 pgd_paddr = read_cr3();
515 pmd_k = vmalloc_sync_one(__va(pgd_paddr), address);
516 if (!pmd_k)
517 return -1;
518 pte_k = pte_offset_kernel(pmd_k, address);
519 if (!pte_present(*pte_k))
520 return -1;
521 return 0;
522#else
523 pgd_t *pgd, *pgd_ref;
524 pud_t *pud, *pud_ref;
525 pmd_t *pmd, *pmd_ref;
526 pte_t *pte, *pte_ref;
527
528
529 if (!(address >= VMALLOC_START && address < VMALLOC_END))
530 return -1;
531
532
533
534
535
536 pgd = pgd_offset(current->active_mm, address);
537 pgd_ref = pgd_offset_k(address);
538 if (pgd_none(*pgd_ref))
539 return -1;
540 if (pgd_none(*pgd))
541 set_pgd(pgd, *pgd_ref);
542 else
543 BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref));
544
545
546
547
548 pud = pud_offset(pgd, address);
549 pud_ref = pud_offset(pgd_ref, address);
550 if (pud_none(*pud_ref))
551 return -1;
552 if (pud_none(*pud) || pud_page_vaddr(*pud) != pud_page_vaddr(*pud_ref))
553 BUG();
554 pmd = pmd_offset(pud, address);
555 pmd_ref = pmd_offset(pud_ref, address);
556 if (pmd_none(*pmd_ref))
557 return -1;
558 if (pmd_none(*pmd) || pmd_page(*pmd) != pmd_page(*pmd_ref))
559 BUG();
560 pte_ref = pte_offset_kernel(pmd_ref, address);
561 if (!pte_present(*pte_ref))
562 return -1;
563 pte = pte_offset_kernel(pmd, address);
564
565
566
567 if (!pte_present(*pte) || pte_pfn(*pte) != pte_pfn(*pte_ref))
568 BUG();
569 return 0;
570#endif
571}
572
573int show_unhandled_signals = 1;
574
575
576
577
578
579
580#ifdef CONFIG_X86_64
581asmlinkage
582#endif
583void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
584{
585 struct task_struct *tsk;
586 struct mm_struct *mm;
587 struct vm_area_struct *vma;
588 unsigned long address;
589 int write, si_code;
590 int fault;
591#ifdef CONFIG_X86_64
592 unsigned long flags;
593#endif
594
595 tsk = current;
596 mm = tsk->mm;
597 prefetchw(&mm->mmap_sem);
598
599
600 address = read_cr2();
601
602 si_code = SEGV_MAPERR;
603
604 if (notify_page_fault(regs))
605 return;
606 if (unlikely(kmmio_fault(regs, address)))
607 return;
608
609
610
611
612
613
614
615
616
617
618
619
620
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
632 if (spurious_fault(address, error_code))
633 return;
634
635
636
637
638
639 goto bad_area_nosemaphore;
640 }
641
642
643
644
645
646
647
648
649
650 if (user_mode_vm(regs)) {
651 local_irq_enable();
652 error_code |= PF_USER;
653 } else if (regs->flags & X86_EFLAGS_IF)
654 local_irq_enable();
655
656#ifdef CONFIG_X86_64
657 if (unlikely(error_code & PF_RSVD))
658 pgtable_bad(address, regs, error_code);
659#endif
660
661
662
663
664
665 if (unlikely(in_atomic() || !mm))
666 goto bad_area_nosemaphore;
667
668again:
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685 if (!down_read_trylock(&mm->mmap_sem)) {
686 if ((error_code & PF_USER) == 0 &&
687 !search_exception_tables(regs->ip))
688 goto bad_area_nosemaphore;
689 down_read(&mm->mmap_sem);
690 }
691
692 vma = find_vma(mm, address);
693 if (!vma)
694 goto bad_area;
695 if (vma->vm_start <= address)
696 goto good_area;
697 if (!(vma->vm_flags & VM_GROWSDOWN))
698 goto bad_area;
699 if (error_code & PF_USER) {
700
701
702
703
704
705
706 if (address + 65536 + 32 * sizeof(unsigned long) < regs->sp)
707 goto bad_area;
708 }
709 if (expand_stack(vma, address))
710 goto bad_area;
711
712
713
714
715good_area:
716 si_code = SEGV_ACCERR;
717 write = 0;
718 switch (error_code & (PF_PROT|PF_WRITE)) {
719 default:
720
721 case PF_WRITE:
722 if (!(vma->vm_flags & VM_WRITE))
723 goto bad_area;
724 write++;
725 break;
726 case PF_PROT:
727 goto bad_area;
728 case 0:
729 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
730 goto bad_area;
731 }
732
733
734
735
736
737
738 fault = handle_mm_fault(mm, vma, address, write);
739 if (unlikely(fault & VM_FAULT_ERROR)) {
740 if (fault & VM_FAULT_OOM)
741 goto out_of_memory;
742 else if (fault & VM_FAULT_SIGBUS)
743 goto do_sigbus;
744 BUG();
745 }
746 if (fault & VM_FAULT_MAJOR)
747 tsk->maj_flt++;
748 else
749 tsk->min_flt++;
750
751#ifdef CONFIG_X86_32
752
753
754
755 if (v8086_mode(regs)) {
756 unsigned long bit = (address - 0xA0000) >> PAGE_SHIFT;
757 if (bit < 32)
758 tsk->thread.screen_bitmap |= 1 << bit;
759 }
760#endif
761 up_read(&mm->mmap_sem);
762 return;
763
764
765
766
767
768bad_area:
769 up_read(&mm->mmap_sem);
770
771bad_area_nosemaphore:
772
773 if (error_code & PF_USER) {
774
775
776
777 local_irq_enable();
778
779
780
781
782
783 if (is_prefetch(regs, address, error_code))
784 return;
785
786 if (is_errata100(regs, address))
787 return;
788
789 if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
790 printk_ratelimit()) {
791 printk(
792 "%s%s[%d]: segfault at %lx ip %p sp %p error %lx",
793 task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
794 tsk->comm, task_pid_nr(tsk), address,
795 (void *) regs->ip, (void *) regs->sp, error_code);
796 print_vma_addr(" in ", regs->ip);
797 printk("\n");
798 }
799
800 tsk->thread.cr2 = address;
801
802 tsk->thread.error_code = error_code | (address >= TASK_SIZE);
803 tsk->thread.trap_no = 14;
804 force_sig_info_fault(SIGSEGV, si_code, address, tsk);
805 return;
806 }
807
808 if (is_f00f_bug(regs, address))
809 return;
810
811no_context:
812
813 if (fixup_exception(regs))
814 return;
815
816
817
818
819
820
821
822
823
824
825 if (is_prefetch(regs, address, error_code))
826 return;
827
828 if (is_errata93(regs, address))
829 return;
830
831
832
833
834
835#ifdef CONFIG_X86_32
836 bust_spinlocks(1);
837#else
838 flags = oops_begin();
839#endif
840
841 show_fault_oops(regs, error_code, address);
842
843 tsk->thread.cr2 = address;
844 tsk->thread.trap_no = 14;
845 tsk->thread.error_code = error_code;
846
847#ifdef CONFIG_X86_32
848 die("Oops", regs, error_code);
849 bust_spinlocks(0);
850 do_exit(SIGKILL);
851#else
852 if (__die("Oops", regs, error_code))
853 regs = NULL;
854
855 printk(KERN_EMERG "CR2: %016lx\n", address);
856 oops_end(flags, regs, SIGKILL);
857#endif
858
859
860
861
862
863out_of_memory:
864 up_read(&mm->mmap_sem);
865 if (is_global_init(tsk)) {
866 yield();
867
868
869
870
871 goto again;
872 }
873
874 printk("VM: killing process %s\n", tsk->comm);
875 if (error_code & PF_USER)
876 do_group_exit(SIGKILL);
877 goto no_context;
878
879do_sigbus:
880 up_read(&mm->mmap_sem);
881
882
883 if (!(error_code & PF_USER))
884 goto no_context;
885#ifdef CONFIG_X86_32
886
887 if (is_prefetch(regs, address, error_code))
888 return;
889#endif
890 tsk->thread.cr2 = address;
891 tsk->thread.error_code = error_code;
892 tsk->thread.trap_no = 14;
893 force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk);
894}
895
896DEFINE_SPINLOCK(pgd_lock);
897LIST_HEAD(pgd_list);
898
899void vmalloc_sync_all(void)
900{
901 unsigned long address;
902
903#ifdef CONFIG_X86_32
904 if (SHARED_KERNEL_PMD)
905 return;
906
907 for (address = VMALLOC_START & PMD_MASK;
908 address >= TASK_SIZE && address < FIXADDR_TOP;
909 address += PMD_SIZE) {
910 unsigned long flags;
911 struct page *page;
912
913 spin_lock_irqsave(&pgd_lock, flags);
914 list_for_each_entry(page, &pgd_list, lru) {
915 if (!vmalloc_sync_one(page_address(page),
916 address))
917 break;
918 }
919 spin_unlock_irqrestore(&pgd_lock, flags);
920 }
921#else
922 for (address = VMALLOC_START & PGDIR_MASK; address <= VMALLOC_END;
923 address += PGDIR_SIZE) {
924 const pgd_t *pgd_ref = pgd_offset_k(address);
925 unsigned long flags;
926 struct page *page;
927
928 if (pgd_none(*pgd_ref))
929 continue;
930 spin_lock_irqsave(&pgd_lock, flags);
931 list_for_each_entry(page, &pgd_list, lru) {
932 pgd_t *pgd;
933 pgd = (pgd_t *)page_address(page) + pgd_index(address);
934 if (pgd_none(*pgd))
935 set_pgd(pgd, *pgd_ref);
936 else
937 BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref));
938 }
939 spin_unlock_irqrestore(&pgd_lock, flags);
940 }
941#endif
942}
943