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8#include <linux/extable.h>
9#include <linux/signal.h>
10#include <linux/mm.h>
11#include <linux/hardirq.h>
12#include <linux/init.h>
13#include <linux/kprobes.h>
14#include <linux/uaccess.h>
15#include <linux/page-flags.h>
16#include <linux/sched/signal.h>
17#include <linux/sched/debug.h>
18#include <linux/highmem.h>
19#include <linux/perf_event.h>
20
21#include <asm/pgtable.h>
22#include <asm/system_misc.h>
23#include <asm/system_info.h>
24#include <asm/tlbflush.h>
25
26#include "fault.h"
27
28#ifdef CONFIG_MMU
29
30
31
32
33
34void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr)
35{
36 pgd_t *pgd;
37
38 if (!mm)
39 mm = &init_mm;
40
41 printk("%spgd = %p\n", lvl, mm->pgd);
42 pgd = pgd_offset(mm, addr);
43 printk("%s[%08lx] *pgd=%08llx", lvl, addr, (long long)pgd_val(*pgd));
44
45 do {
46 pud_t *pud;
47 pmd_t *pmd;
48 pte_t *pte;
49
50 if (pgd_none(*pgd))
51 break;
52
53 if (pgd_bad(*pgd)) {
54 pr_cont("(bad)");
55 break;
56 }
57
58 pud = pud_offset(pgd, addr);
59 if (PTRS_PER_PUD != 1)
60 pr_cont(", *pud=%08llx", (long long)pud_val(*pud));
61
62 if (pud_none(*pud))
63 break;
64
65 if (pud_bad(*pud)) {
66 pr_cont("(bad)");
67 break;
68 }
69
70 pmd = pmd_offset(pud, addr);
71 if (PTRS_PER_PMD != 1)
72 pr_cont(", *pmd=%08llx", (long long)pmd_val(*pmd));
73
74 if (pmd_none(*pmd))
75 break;
76
77 if (pmd_bad(*pmd)) {
78 pr_cont("(bad)");
79 break;
80 }
81
82
83 if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT)))
84 break;
85
86 pte = pte_offset_map(pmd, addr);
87 pr_cont(", *pte=%08llx", (long long)pte_val(*pte));
88#ifndef CONFIG_ARM_LPAE
89 pr_cont(", *ppte=%08llx",
90 (long long)pte_val(pte[PTE_HWTABLE_PTRS]));
91#endif
92 pte_unmap(pte);
93 } while(0);
94
95 pr_cont("\n");
96}
97#else
98void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr)
99{ }
100#endif
101
102
103
104
105static void
106__do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
107 struct pt_regs *regs)
108{
109
110
111
112 if (fixup_exception(regs))
113 return;
114
115
116
117
118 bust_spinlocks(1);
119 pr_alert("8<--- cut here ---\n");
120 pr_alert("Unable to handle kernel %s at virtual address %08lx\n",
121 (addr < PAGE_SIZE) ? "NULL pointer dereference" :
122 "paging request", addr);
123
124 show_pte(KERN_ALERT, mm, addr);
125 die("Oops", regs, fsr);
126 bust_spinlocks(0);
127 do_exit(SIGKILL);
128}
129
130
131
132
133
134static void
135__do_user_fault(unsigned long addr, unsigned int fsr, unsigned int sig,
136 int code, struct pt_regs *regs)
137{
138 struct task_struct *tsk = current;
139
140 if (addr > TASK_SIZE)
141 harden_branch_predictor();
142
143#ifdef CONFIG_DEBUG_USER
144 if (((user_debug & UDBG_SEGV) && (sig == SIGSEGV)) ||
145 ((user_debug & UDBG_BUS) && (sig == SIGBUS))) {
146 pr_err("8<--- cut here ---\n");
147 pr_err("%s: unhandled page fault (%d) at 0x%08lx, code 0x%03x\n",
148 tsk->comm, sig, addr, fsr);
149 show_pte(KERN_ERR, tsk->mm, addr);
150 show_regs(regs);
151 }
152#endif
153#ifndef CONFIG_KUSER_HELPERS
154 if ((sig == SIGSEGV) && ((addr & PAGE_MASK) == 0xffff0000))
155 printk_ratelimited(KERN_DEBUG
156 "%s: CONFIG_KUSER_HELPERS disabled at 0x%08lx\n",
157 tsk->comm, addr);
158#endif
159
160 tsk->thread.address = addr;
161 tsk->thread.error_code = fsr;
162 tsk->thread.trap_no = 14;
163 force_sig_fault(sig, code, (void __user *)addr);
164}
165
166void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
167{
168 struct task_struct *tsk = current;
169 struct mm_struct *mm = tsk->active_mm;
170
171
172
173
174
175 if (user_mode(regs))
176 __do_user_fault(addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
177 else
178 __do_kernel_fault(mm, addr, fsr, regs);
179}
180
181#ifdef CONFIG_MMU
182#define VM_FAULT_BADMAP 0x010000
183#define VM_FAULT_BADACCESS 0x020000
184
185
186
187
188
189
190static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma)
191{
192 unsigned int mask = VM_READ | VM_WRITE | VM_EXEC;
193
194 if (fsr & FSR_WRITE)
195 mask = VM_WRITE;
196 if (fsr & FSR_LNX_PF)
197 mask = VM_EXEC;
198
199 return vma->vm_flags & mask ? false : true;
200}
201
202static vm_fault_t __kprobes
203__do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
204 unsigned int flags, struct task_struct *tsk)
205{
206 struct vm_area_struct *vma;
207 vm_fault_t fault;
208
209 vma = find_vma(mm, addr);
210 fault = VM_FAULT_BADMAP;
211 if (unlikely(!vma))
212 goto out;
213 if (unlikely(vma->vm_start > addr))
214 goto check_stack;
215
216
217
218
219
220good_area:
221 if (access_error(fsr, vma)) {
222 fault = VM_FAULT_BADACCESS;
223 goto out;
224 }
225
226 return handle_mm_fault(vma, addr & PAGE_MASK, flags);
227
228check_stack:
229
230 if (vma->vm_flags & VM_GROWSDOWN &&
231 addr >= FIRST_USER_ADDRESS && !expand_stack(vma, addr))
232 goto good_area;
233out:
234 return fault;
235}
236
237static int __kprobes
238do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
239{
240 struct task_struct *tsk;
241 struct mm_struct *mm;
242 int sig, code;
243 vm_fault_t fault;
244 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
245
246 if (kprobe_page_fault(regs, fsr))
247 return 0;
248
249 tsk = current;
250 mm = tsk->mm;
251
252
253 if (interrupts_enabled(regs))
254 local_irq_enable();
255
256
257
258
259
260 if (faulthandler_disabled() || !mm)
261 goto no_context;
262
263 if (user_mode(regs))
264 flags |= FAULT_FLAG_USER;
265 if (fsr & FSR_WRITE)
266 flags |= FAULT_FLAG_WRITE;
267
268
269
270
271
272
273 if (!down_read_trylock(&mm->mmap_sem)) {
274 if (!user_mode(regs) && !search_exception_tables(regs->ARM_pc))
275 goto no_context;
276retry:
277 down_read(&mm->mmap_sem);
278 } else {
279
280
281
282
283
284 might_sleep();
285#ifdef CONFIG_DEBUG_VM
286 if (!user_mode(regs) &&
287 !search_exception_tables(regs->ARM_pc))
288 goto no_context;
289#endif
290 }
291
292 fault = __do_page_fault(mm, addr, fsr, flags, tsk);
293
294
295
296
297
298 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) {
299 if (!user_mode(regs))
300 goto no_context;
301 return 0;
302 }
303
304
305
306
307
308
309
310 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
311 if (!(fault & VM_FAULT_ERROR) && flags & FAULT_FLAG_ALLOW_RETRY) {
312 if (fault & VM_FAULT_MAJOR) {
313 tsk->maj_flt++;
314 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
315 regs, addr);
316 } else {
317 tsk->min_flt++;
318 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
319 regs, addr);
320 }
321 if (fault & VM_FAULT_RETRY) {
322
323
324 flags &= ~FAULT_FLAG_ALLOW_RETRY;
325 flags |= FAULT_FLAG_TRIED;
326 goto retry;
327 }
328 }
329
330 up_read(&mm->mmap_sem);
331
332
333
334
335 if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS))))
336 return 0;
337
338
339
340
341
342 if (!user_mode(regs))
343 goto no_context;
344
345 if (fault & VM_FAULT_OOM) {
346
347
348
349
350
351 pagefault_out_of_memory();
352 return 0;
353 }
354
355 if (fault & VM_FAULT_SIGBUS) {
356
357
358
359
360 sig = SIGBUS;
361 code = BUS_ADRERR;
362 } else {
363
364
365
366
367 sig = SIGSEGV;
368 code = fault == VM_FAULT_BADACCESS ?
369 SEGV_ACCERR : SEGV_MAPERR;
370 }
371
372 __do_user_fault(addr, fsr, sig, code, regs);
373 return 0;
374
375no_context:
376 __do_kernel_fault(mm, addr, fsr, regs);
377 return 0;
378}
379#else
380static int
381do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
382{
383 return 0;
384}
385#endif
386
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398
399
400
401
402
403
404#ifdef CONFIG_MMU
405static int __kprobes
406do_translation_fault(unsigned long addr, unsigned int fsr,
407 struct pt_regs *regs)
408{
409 unsigned int index;
410 pgd_t *pgd, *pgd_k;
411 pud_t *pud, *pud_k;
412 pmd_t *pmd, *pmd_k;
413
414 if (addr < TASK_SIZE)
415 return do_page_fault(addr, fsr, regs);
416
417 if (user_mode(regs))
418 goto bad_area;
419
420 index = pgd_index(addr);
421
422 pgd = cpu_get_pgd() + index;
423 pgd_k = init_mm.pgd + index;
424
425 if (pgd_none(*pgd_k))
426 goto bad_area;
427 if (!pgd_present(*pgd))
428 set_pgd(pgd, *pgd_k);
429
430 pud = pud_offset(pgd, addr);
431 pud_k = pud_offset(pgd_k, addr);
432
433 if (pud_none(*pud_k))
434 goto bad_area;
435 if (!pud_present(*pud))
436 set_pud(pud, *pud_k);
437
438 pmd = pmd_offset(pud, addr);
439 pmd_k = pmd_offset(pud_k, addr);
440
441#ifdef CONFIG_ARM_LPAE
442
443
444
445 index = 0;
446#else
447
448
449
450
451
452
453
454
455 index = (addr >> SECTION_SHIFT) & 1;
456#endif
457 if (pmd_none(pmd_k[index]))
458 goto bad_area;
459
460 copy_pmd(pmd, pmd_k);
461 return 0;
462
463bad_area:
464 do_bad_area(addr, fsr, regs);
465 return 0;
466}
467#else
468static int
469do_translation_fault(unsigned long addr, unsigned int fsr,
470 struct pt_regs *regs)
471{
472 return 0;
473}
474#endif
475
476
477
478
479
480#ifndef CONFIG_ARM_LPAE
481static int
482do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
483{
484 do_bad_area(addr, fsr, regs);
485 return 0;
486}
487#endif
488
489
490
491
492static int
493do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
494{
495 return 1;
496}
497
498struct fsr_info {
499 int (*fn)(unsigned long addr, unsigned int fsr, struct pt_regs *regs);
500 int sig;
501 int code;
502 const char *name;
503};
504
505
506#ifdef CONFIG_ARM_LPAE
507#include "fsr-3level.c"
508#else
509#include "fsr-2level.c"
510#endif
511
512void __init
513hook_fault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *),
514 int sig, int code, const char *name)
515{
516 if (nr < 0 || nr >= ARRAY_SIZE(fsr_info))
517 BUG();
518
519 fsr_info[nr].fn = fn;
520 fsr_info[nr].sig = sig;
521 fsr_info[nr].code = code;
522 fsr_info[nr].name = name;
523}
524
525
526
527
528asmlinkage void
529do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
530{
531 const struct fsr_info *inf = fsr_info + fsr_fs(fsr);
532
533 if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs))
534 return;
535
536 pr_alert("8<--- cut here ---\n");
537 pr_alert("Unhandled fault: %s (0x%03x) at 0x%08lx\n",
538 inf->name, fsr, addr);
539 show_pte(KERN_ALERT, current->mm, addr);
540
541 arm_notify_die("", regs, inf->sig, inf->code, (void __user *)addr,
542 fsr, 0);
543}
544
545void __init
546hook_ifault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *),
547 int sig, int code, const char *name)
548{
549 if (nr < 0 || nr >= ARRAY_SIZE(ifsr_info))
550 BUG();
551
552 ifsr_info[nr].fn = fn;
553 ifsr_info[nr].sig = sig;
554 ifsr_info[nr].code = code;
555 ifsr_info[nr].name = name;
556}
557
558asmlinkage void
559do_PrefetchAbort(unsigned long addr, unsigned int ifsr, struct pt_regs *regs)
560{
561 const struct fsr_info *inf = ifsr_info + fsr_fs(ifsr);
562
563 if (!inf->fn(addr, ifsr | FSR_LNX_PF, regs))
564 return;
565
566 pr_alert("Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n",
567 inf->name, ifsr, addr);
568
569 arm_notify_die("", regs, inf->sig, inf->code, (void __user *)addr,
570 ifsr, 0);
571}
572
573
574
575
576
577
578static int __init early_abort_handler(unsigned long addr, unsigned int fsr,
579 struct pt_regs *regs)
580{
581 pr_warn("Hit pending asynchronous external abort (FSR=0x%08x) during "
582 "first unmask, this is most likely caused by a "
583 "firmware/bootloader bug.\n", fsr);
584
585 return 0;
586}
587
588void __init early_abt_enable(void)
589{
590 fsr_info[FSR_FS_AEA].fn = early_abort_handler;
591 local_abt_enable();
592 fsr_info[FSR_FS_AEA].fn = do_bad;
593}
594
595#ifndef CONFIG_ARM_LPAE
596static int __init exceptions_init(void)
597{
598 if (cpu_architecture() >= CPU_ARCH_ARMv6) {
599 hook_fault_code(4, do_translation_fault, SIGSEGV, SEGV_MAPERR,
600 "I-cache maintenance fault");
601 }
602
603 if (cpu_architecture() >= CPU_ARCH_ARMv7) {
604
605
606
607
608 hook_fault_code(3, do_bad, SIGSEGV, SEGV_MAPERR,
609 "section access flag fault");
610 hook_fault_code(6, do_bad, SIGSEGV, SEGV_MAPERR,
611 "section access flag fault");
612 }
613
614 return 0;
615}
616
617arch_initcall(exceptions_init);
618#endif
619