Loading...
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/arch/arm/mm/fault.c
4 *
5 * Copyright (C) 1995 Linus Torvalds
6 * Modifications for ARM processor (c) 1995-2004 Russell King
7 */
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#include <linux/kfence.h>
21
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
30bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size)
31{
32 unsigned long addr = (unsigned long)unsafe_src;
33
34 return addr >= TASK_SIZE && ULONG_MAX - addr >= size;
35}
36
37/*
38 * This is useful to dump out the page tables associated with
39 * 'addr' in mm 'mm'.
40 */
41void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr)
42{
43 pgd_t *pgd;
44
45 if (!mm)
46 mm = &init_mm;
47
48 pgd = pgd_offset(mm, addr);
49 printk("%s[%08lx] *pgd=%08llx", lvl, addr, (long long)pgd_val(*pgd));
50
51 do {
52 p4d_t *p4d;
53 pud_t *pud;
54 pmd_t *pmd;
55 pte_t *pte;
56
57 p4d = p4d_offset(pgd, addr);
58 if (p4d_none(*p4d))
59 break;
60
61 if (p4d_bad(*p4d)) {
62 pr_cont("(bad)");
63 break;
64 }
65
66 pud = pud_offset(p4d, addr);
67 if (PTRS_PER_PUD != 1)
68 pr_cont(", *pud=%08llx", (long long)pud_val(*pud));
69
70 if (pud_none(*pud))
71 break;
72
73 if (pud_bad(*pud)) {
74 pr_cont("(bad)");
75 break;
76 }
77
78 pmd = pmd_offset(pud, addr);
79 if (PTRS_PER_PMD != 1)
80 pr_cont(", *pmd=%08llx", (long long)pmd_val(*pmd));
81
82 if (pmd_none(*pmd))
83 break;
84
85 if (pmd_bad(*pmd)) {
86 pr_cont("(bad)");
87 break;
88 }
89
90 /* We must not map this if we have highmem enabled */
91 if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT)))
92 break;
93
94 pte = pte_offset_map(pmd, addr);
95 if (!pte)
96 break;
97
98 pr_cont(", *pte=%08llx", (long long)pte_val(*pte));
99#ifndef CONFIG_ARM_LPAE
100 pr_cont(", *ppte=%08llx",
101 (long long)pte_val(pte[PTE_HWTABLE_PTRS]));
102#endif
103 pte_unmap(pte);
104 } while(0);
105
106 pr_cont("\n");
107}
108#else /* CONFIG_MMU */
109void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr)
110{ }
111#endif /* CONFIG_MMU */
112
113static inline bool is_write_fault(unsigned int fsr)
114{
115 return (fsr & FSR_WRITE) && !(fsr & FSR_CM);
116}
117
118static inline bool is_translation_fault(unsigned int fsr)
119{
120 int fs = fsr_fs(fsr);
121#ifdef CONFIG_ARM_LPAE
122 if ((fs & FS_MMU_NOLL_MASK) == FS_TRANS_NOLL)
123 return true;
124#else
125 if (fs == FS_L1_TRANS || fs == FS_L2_TRANS)
126 return true;
127#endif
128 return false;
129}
130
131static void die_kernel_fault(const char *msg, struct mm_struct *mm,
132 unsigned long addr, unsigned int fsr,
133 struct pt_regs *regs)
134{
135 bust_spinlocks(1);
136 pr_alert("8<--- cut here ---\n");
137 pr_alert("Unable to handle kernel %s at virtual address %08lx when %s\n",
138 msg, addr, fsr & FSR_LNX_PF ? "execute" :
139 fsr & FSR_WRITE ? "write" : "read");
140
141 show_pte(KERN_ALERT, mm, addr);
142 die("Oops", regs, fsr);
143 bust_spinlocks(0);
144 make_task_dead(SIGKILL);
145}
146
147/*
148 * Oops. The kernel tried to access some page that wasn't present.
149 */
150static void
151__do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
152 struct pt_regs *regs)
153{
154 const char *msg;
155 /*
156 * Are we prepared to handle this kernel fault?
157 */
158 if (fixup_exception(regs))
159 return;
160
161 /*
162 * No handler, we'll have to terminate things with extreme prejudice.
163 */
164 if (addr < PAGE_SIZE) {
165 msg = "NULL pointer dereference";
166 } else {
167 if (is_translation_fault(fsr) &&
168 kfence_handle_page_fault(addr, is_write_fault(fsr), regs))
169 return;
170
171 msg = "paging request";
172 }
173
174 die_kernel_fault(msg, mm, addr, fsr, regs);
175}
176
177/*
178 * Something tried to access memory that isn't in our memory map..
179 * User mode accesses just cause a SIGSEGV
180 */
181static void
182__do_user_fault(unsigned long addr, unsigned int fsr, unsigned int sig,
183 int code, struct pt_regs *regs)
184{
185 struct task_struct *tsk = current;
186
187 if (addr > TASK_SIZE)
188 harden_branch_predictor();
189
190#ifdef CONFIG_DEBUG_USER
191 if (((user_debug & UDBG_SEGV) && (sig == SIGSEGV)) ||
192 ((user_debug & UDBG_BUS) && (sig == SIGBUS))) {
193 pr_err("8<--- cut here ---\n");
194 pr_err("%s: unhandled page fault (%d) at 0x%08lx, code 0x%03x\n",
195 tsk->comm, sig, addr, fsr);
196 show_pte(KERN_ERR, tsk->mm, addr);
197 show_regs(regs);
198 }
199#endif
200#ifndef CONFIG_KUSER_HELPERS
201 if ((sig == SIGSEGV) && ((addr & PAGE_MASK) == 0xffff0000))
202 printk_ratelimited(KERN_DEBUG
203 "%s: CONFIG_KUSER_HELPERS disabled at 0x%08lx\n",
204 tsk->comm, addr);
205#endif
206
207 tsk->thread.address = addr;
208 tsk->thread.error_code = fsr;
209 tsk->thread.trap_no = 14;
210 force_sig_fault(sig, code, (void __user *)addr);
211}
212
213void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
214{
215 struct task_struct *tsk = current;
216 struct mm_struct *mm = tsk->active_mm;
217
218 /*
219 * If we are in kernel mode at this point, we
220 * have no context to handle this fault with.
221 */
222 if (user_mode(regs))
223 __do_user_fault(addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
224 else
225 __do_kernel_fault(mm, addr, fsr, regs);
226}
227
228#ifdef CONFIG_MMU
229static inline bool is_permission_fault(unsigned int fsr)
230{
231 int fs = fsr_fs(fsr);
232#ifdef CONFIG_ARM_LPAE
233 if ((fs & FS_MMU_NOLL_MASK) == FS_PERM_NOLL)
234 return true;
235#else
236 if (fs == FS_L1_PERM || fs == FS_L2_PERM)
237 return true;
238#endif
239 return false;
240}
241
242#ifdef CONFIG_CPU_TTBR0_PAN
243static inline bool ttbr0_usermode_access_allowed(struct pt_regs *regs)
244{
245 struct svc_pt_regs *svcregs;
246
247 /* If we are in user mode: permission granted */
248 if (user_mode(regs))
249 return true;
250
251 /* uaccess state saved above pt_regs on SVC exception entry */
252 svcregs = to_svc_pt_regs(regs);
253
254 return !(svcregs->ttbcr & TTBCR_EPD0);
255}
256#else
257static inline bool ttbr0_usermode_access_allowed(struct pt_regs *regs)
258{
259 return true;
260}
261#endif
262
263static int __kprobes
264do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
265{
266 struct mm_struct *mm = current->mm;
267 struct vm_area_struct *vma;
268 int sig, code;
269 vm_fault_t fault;
270 unsigned int flags = FAULT_FLAG_DEFAULT;
271 unsigned long vm_flags = VM_ACCESS_FLAGS;
272
273 if (kprobe_page_fault(regs, fsr))
274 return 0;
275
276
277 /* Enable interrupts if they were enabled in the parent context. */
278 if (interrupts_enabled(regs))
279 local_irq_enable();
280
281 /*
282 * If we're in an interrupt or have no user
283 * context, we must not take the fault..
284 */
285 if (faulthandler_disabled() || !mm)
286 goto no_context;
287
288 if (user_mode(regs))
289 flags |= FAULT_FLAG_USER;
290
291 if (is_write_fault(fsr)) {
292 flags |= FAULT_FLAG_WRITE;
293 vm_flags = VM_WRITE;
294 }
295
296 if (fsr & FSR_LNX_PF) {
297 vm_flags = VM_EXEC;
298
299 if (is_permission_fault(fsr) && !user_mode(regs))
300 die_kernel_fault("execution of memory",
301 mm, addr, fsr, regs);
302 }
303
304 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
305
306 /*
307 * Privileged access aborts with CONFIG_CPU_TTBR0_PAN enabled are
308 * routed via the translation fault mechanism. Check whether uaccess
309 * is disabled while in kernel mode.
310 */
311 if (!ttbr0_usermode_access_allowed(regs))
312 goto no_context;
313
314 if (!(flags & FAULT_FLAG_USER))
315 goto lock_mmap;
316
317 vma = lock_vma_under_rcu(mm, addr);
318 if (!vma)
319 goto lock_mmap;
320
321 if (!(vma->vm_flags & vm_flags)) {
322 vma_end_read(vma);
323 count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
324 fault = 0;
325 code = SEGV_ACCERR;
326 goto bad_area;
327 }
328 fault = handle_mm_fault(vma, addr, flags | FAULT_FLAG_VMA_LOCK, regs);
329 if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED)))
330 vma_end_read(vma);
331
332 if (!(fault & VM_FAULT_RETRY)) {
333 count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
334 goto done;
335 }
336 count_vm_vma_lock_event(VMA_LOCK_RETRY);
337 if (fault & VM_FAULT_MAJOR)
338 flags |= FAULT_FLAG_TRIED;
339
340 /* Quick path to respond to signals */
341 if (fault_signal_pending(fault, regs)) {
342 if (!user_mode(regs))
343 goto no_context;
344 return 0;
345 }
346lock_mmap:
347
348retry:
349 vma = lock_mm_and_find_vma(mm, addr, regs);
350 if (unlikely(!vma)) {
351 fault = 0;
352 code = SEGV_MAPERR;
353 goto bad_area;
354 }
355
356 /*
357 * ok, we have a good vm_area for this memory access, check the
358 * permissions on the VMA allow for the fault which occurred.
359 */
360 if (!(vma->vm_flags & vm_flags)) {
361 mmap_read_unlock(mm);
362 fault = 0;
363 code = SEGV_ACCERR;
364 goto bad_area;
365 }
366
367 fault = handle_mm_fault(vma, addr & PAGE_MASK, flags, regs);
368
369 /* If we need to retry but a fatal signal is pending, handle the
370 * signal first. We do not need to release the mmap_lock because
371 * it would already be released in __lock_page_or_retry in
372 * mm/filemap.c. */
373 if (fault_signal_pending(fault, regs)) {
374 if (!user_mode(regs))
375 goto no_context;
376 return 0;
377 }
378
379 /* The fault is fully completed (including releasing mmap lock) */
380 if (fault & VM_FAULT_COMPLETED)
381 return 0;
382
383 if (!(fault & VM_FAULT_ERROR)) {
384 if (fault & VM_FAULT_RETRY) {
385 flags |= FAULT_FLAG_TRIED;
386 goto retry;
387 }
388 }
389
390 mmap_read_unlock(mm);
391done:
392
393 /* Handle the "normal" case first */
394 if (likely(!(fault & VM_FAULT_ERROR)))
395 return 0;
396
397 code = SEGV_MAPERR;
398bad_area:
399 /*
400 * If we are in kernel mode at this point, we
401 * have no context to handle this fault with.
402 */
403 if (!user_mode(regs))
404 goto no_context;
405
406 if (fault & VM_FAULT_OOM) {
407 /*
408 * We ran out of memory, call the OOM killer, and return to
409 * userspace (which will retry the fault, or kill us if we
410 * got oom-killed)
411 */
412 pagefault_out_of_memory();
413 return 0;
414 }
415
416 if (fault & VM_FAULT_SIGBUS) {
417 /*
418 * We had some memory, but were unable to
419 * successfully fix up this page fault.
420 */
421 sig = SIGBUS;
422 code = BUS_ADRERR;
423 } else {
424 /*
425 * Something tried to access memory that
426 * isn't in our memory map..
427 */
428 sig = SIGSEGV;
429 }
430
431 __do_user_fault(addr, fsr, sig, code, regs);
432 return 0;
433
434no_context:
435 __do_kernel_fault(mm, addr, fsr, regs);
436 return 0;
437}
438#else /* CONFIG_MMU */
439static int
440do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
441{
442 return 0;
443}
444#endif /* CONFIG_MMU */
445
446/*
447 * First Level Translation Fault Handler
448 *
449 * We enter here because the first level page table doesn't contain
450 * a valid entry for the address.
451 *
452 * If the address is in kernel space (>= TASK_SIZE), then we are
453 * probably faulting in the vmalloc() area.
454 *
455 * If the init_task's first level page tables contains the relevant
456 * entry, we copy the it to this task. If not, we send the process
457 * a signal, fixup the exception, or oops the kernel.
458 *
459 * NOTE! We MUST NOT take any locks for this case. We may be in an
460 * interrupt or a critical region, and should only copy the information
461 * from the master page table, nothing more.
462 */
463#ifdef CONFIG_MMU
464static int __kprobes
465do_translation_fault(unsigned long addr, unsigned int fsr,
466 struct pt_regs *regs)
467{
468 unsigned int index;
469 pgd_t *pgd, *pgd_k;
470 p4d_t *p4d, *p4d_k;
471 pud_t *pud, *pud_k;
472 pmd_t *pmd, *pmd_k;
473
474 if (addr < TASK_SIZE)
475 return do_page_fault(addr, fsr, regs);
476
477 if (user_mode(regs))
478 goto bad_area;
479
480 index = pgd_index(addr);
481
482 pgd = cpu_get_pgd() + index;
483 pgd_k = init_mm.pgd + index;
484
485 p4d = p4d_offset(pgd, addr);
486 p4d_k = p4d_offset(pgd_k, addr);
487
488 if (p4d_none(*p4d_k))
489 goto bad_area;
490 if (!p4d_present(*p4d))
491 set_p4d(p4d, *p4d_k);
492
493 pud = pud_offset(p4d, addr);
494 pud_k = pud_offset(p4d_k, addr);
495
496 if (pud_none(*pud_k))
497 goto bad_area;
498 if (!pud_present(*pud))
499 set_pud(pud, *pud_k);
500
501 pmd = pmd_offset(pud, addr);
502 pmd_k = pmd_offset(pud_k, addr);
503
504#ifdef CONFIG_ARM_LPAE
505 /*
506 * Only one hardware entry per PMD with LPAE.
507 */
508 index = 0;
509#else
510 /*
511 * On ARM one Linux PGD entry contains two hardware entries (see page
512 * tables layout in pgtable.h). We normally guarantee that we always
513 * fill both L1 entries. But create_mapping() doesn't follow the rule.
514 * It can create inidividual L1 entries, so here we have to call
515 * pmd_none() check for the entry really corresponded to address, not
516 * for the first of pair.
517 */
518 index = (addr >> SECTION_SHIFT) & 1;
519#endif
520 if (pmd_none(pmd_k[index]))
521 goto bad_area;
522
523 copy_pmd(pmd, pmd_k);
524 return 0;
525
526bad_area:
527 do_bad_area(addr, fsr, regs);
528 return 0;
529}
530#else /* CONFIG_MMU */
531static int
532do_translation_fault(unsigned long addr, unsigned int fsr,
533 struct pt_regs *regs)
534{
535 return 0;
536}
537#endif /* CONFIG_MMU */
538
539/*
540 * Some section permission faults need to be handled gracefully.
541 * They can happen due to a __{get,put}_user during an oops.
542 */
543#ifndef CONFIG_ARM_LPAE
544static int
545do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
546{
547 do_bad_area(addr, fsr, regs);
548 return 0;
549}
550#endif /* CONFIG_ARM_LPAE */
551
552/*
553 * This abort handler always returns "fault".
554 */
555static int
556do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
557{
558 return 1;
559}
560
561struct fsr_info {
562 int (*fn)(unsigned long addr, unsigned int fsr, struct pt_regs *regs);
563 int sig;
564 int code;
565 const char *name;
566};
567
568/* FSR definition */
569#ifdef CONFIG_ARM_LPAE
570#include "fsr-3level.c"
571#else
572#include "fsr-2level.c"
573#endif
574
575void __init
576hook_fault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *),
577 int sig, int code, const char *name)
578{
579 if (nr < 0 || nr >= ARRAY_SIZE(fsr_info))
580 BUG();
581
582 fsr_info[nr].fn = fn;
583 fsr_info[nr].sig = sig;
584 fsr_info[nr].code = code;
585 fsr_info[nr].name = name;
586}
587
588/*
589 * Dispatch a data abort to the relevant handler.
590 */
591asmlinkage void
592do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
593{
594 const struct fsr_info *inf = fsr_info + fsr_fs(fsr);
595
596 if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs))
597 return;
598
599 pr_alert("8<--- cut here ---\n");
600 pr_alert("Unhandled fault: %s (0x%03x) at 0x%08lx\n",
601 inf->name, fsr, addr);
602 show_pte(KERN_ALERT, current->mm, addr);
603
604 arm_notify_die("", regs, inf->sig, inf->code, (void __user *)addr,
605 fsr, 0);
606}
607
608void __init
609hook_ifault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *),
610 int sig, int code, const char *name)
611{
612 if (nr < 0 || nr >= ARRAY_SIZE(ifsr_info))
613 BUG();
614
615 ifsr_info[nr].fn = fn;
616 ifsr_info[nr].sig = sig;
617 ifsr_info[nr].code = code;
618 ifsr_info[nr].name = name;
619}
620
621asmlinkage void
622do_PrefetchAbort(unsigned long addr, unsigned int ifsr, struct pt_regs *regs)
623{
624 const struct fsr_info *inf = ifsr_info + fsr_fs(ifsr);
625
626 if (!inf->fn(addr, ifsr | FSR_LNX_PF, regs))
627 return;
628
629 pr_alert("8<--- cut here ---\n");
630 pr_alert("Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n",
631 inf->name, ifsr, addr);
632
633 arm_notify_die("", regs, inf->sig, inf->code, (void __user *)addr,
634 ifsr, 0);
635}
636
637/*
638 * Abort handler to be used only during first unmasking of asynchronous aborts
639 * on the boot CPU. This makes sure that the machine will not die if the
640 * firmware/bootloader left an imprecise abort pending for us to trip over.
641 */
642static int __init early_abort_handler(unsigned long addr, unsigned int fsr,
643 struct pt_regs *regs)
644{
645 pr_warn("Hit pending asynchronous external abort (FSR=0x%08x) during "
646 "first unmask, this is most likely caused by a "
647 "firmware/bootloader bug.\n", fsr);
648
649 return 0;
650}
651
652void __init early_abt_enable(void)
653{
654 fsr_info[FSR_FS_AEA].fn = early_abort_handler;
655 local_abt_enable();
656 fsr_info[FSR_FS_AEA].fn = do_bad;
657}
658
659#ifndef CONFIG_ARM_LPAE
660static int __init exceptions_init(void)
661{
662 if (cpu_architecture() >= CPU_ARCH_ARMv6) {
663 hook_fault_code(4, do_translation_fault, SIGSEGV, SEGV_MAPERR,
664 "I-cache maintenance fault");
665 }
666
667 if (cpu_architecture() >= CPU_ARCH_ARMv7) {
668 /*
669 * TODO: Access flag faults introduced in ARMv6K.
670 * Runtime check for 'K' extension is needed
671 */
672 hook_fault_code(3, do_bad, SIGSEGV, SEGV_MAPERR,
673 "section access flag fault");
674 hook_fault_code(6, do_bad, SIGSEGV, SEGV_MAPERR,
675 "section access flag fault");
676 }
677
678 return 0;
679}
680
681arch_initcall(exceptions_init);
682#endif
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/arch/arm/mm/fault.c
4 *
5 * Copyright (C) 1995 Linus Torvalds
6 * Modifications for ARM processor (c) 1995-2004 Russell King
7 */
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#include <linux/kfence.h>
21
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 * This is useful to dump out the page tables associated with
32 * 'addr' in mm 'mm'.
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 pgd = pgd_offset(mm, addr);
42 printk("%s[%08lx] *pgd=%08llx", lvl, addr, (long long)pgd_val(*pgd));
43
44 do {
45 p4d_t *p4d;
46 pud_t *pud;
47 pmd_t *pmd;
48 pte_t *pte;
49
50 p4d = p4d_offset(pgd, addr);
51 if (p4d_none(*p4d))
52 break;
53
54 if (p4d_bad(*p4d)) {
55 pr_cont("(bad)");
56 break;
57 }
58
59 pud = pud_offset(p4d, addr);
60 if (PTRS_PER_PUD != 1)
61 pr_cont(", *pud=%08llx", (long long)pud_val(*pud));
62
63 if (pud_none(*pud))
64 break;
65
66 if (pud_bad(*pud)) {
67 pr_cont("(bad)");
68 break;
69 }
70
71 pmd = pmd_offset(pud, addr);
72 if (PTRS_PER_PMD != 1)
73 pr_cont(", *pmd=%08llx", (long long)pmd_val(*pmd));
74
75 if (pmd_none(*pmd))
76 break;
77
78 if (pmd_bad(*pmd)) {
79 pr_cont("(bad)");
80 break;
81 }
82
83 /* We must not map this if we have highmem enabled */
84 if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT)))
85 break;
86
87 pte = pte_offset_map(pmd, addr);
88 if (!pte)
89 break;
90
91 pr_cont(", *pte=%08llx", (long long)pte_val(*pte));
92#ifndef CONFIG_ARM_LPAE
93 pr_cont(", *ppte=%08llx",
94 (long long)pte_val(pte[PTE_HWTABLE_PTRS]));
95#endif
96 pte_unmap(pte);
97 } while(0);
98
99 pr_cont("\n");
100}
101#else /* CONFIG_MMU */
102void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr)
103{ }
104#endif /* CONFIG_MMU */
105
106static inline bool is_write_fault(unsigned int fsr)
107{
108 return (fsr & FSR_WRITE) && !(fsr & FSR_CM);
109}
110
111static inline bool is_translation_fault(unsigned int fsr)
112{
113 int fs = fsr_fs(fsr);
114#ifdef CONFIG_ARM_LPAE
115 if ((fs & FS_MMU_NOLL_MASK) == FS_TRANS_NOLL)
116 return true;
117#else
118 if (fs == FS_L1_TRANS || fs == FS_L2_TRANS)
119 return true;
120#endif
121 return false;
122}
123
124static void die_kernel_fault(const char *msg, struct mm_struct *mm,
125 unsigned long addr, unsigned int fsr,
126 struct pt_regs *regs)
127{
128 bust_spinlocks(1);
129 pr_alert("8<--- cut here ---\n");
130 pr_alert("Unable to handle kernel %s at virtual address %08lx when %s\n",
131 msg, addr, fsr & FSR_LNX_PF ? "execute" :
132 fsr & FSR_WRITE ? "write" : "read");
133
134 show_pte(KERN_ALERT, mm, addr);
135 die("Oops", regs, fsr);
136 bust_spinlocks(0);
137 make_task_dead(SIGKILL);
138}
139
140/*
141 * Oops. The kernel tried to access some page that wasn't present.
142 */
143static void
144__do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
145 struct pt_regs *regs)
146{
147 const char *msg;
148 /*
149 * Are we prepared to handle this kernel fault?
150 */
151 if (fixup_exception(regs))
152 return;
153
154 /*
155 * No handler, we'll have to terminate things with extreme prejudice.
156 */
157 if (addr < PAGE_SIZE) {
158 msg = "NULL pointer dereference";
159 } else {
160 if (is_translation_fault(fsr) &&
161 kfence_handle_page_fault(addr, is_write_fault(fsr), regs))
162 return;
163
164 msg = "paging request";
165 }
166
167 die_kernel_fault(msg, mm, addr, fsr, regs);
168}
169
170/*
171 * Something tried to access memory that isn't in our memory map..
172 * User mode accesses just cause a SIGSEGV
173 */
174static void
175__do_user_fault(unsigned long addr, unsigned int fsr, unsigned int sig,
176 int code, struct pt_regs *regs)
177{
178 struct task_struct *tsk = current;
179
180 if (addr > TASK_SIZE)
181 harden_branch_predictor();
182
183#ifdef CONFIG_DEBUG_USER
184 if (((user_debug & UDBG_SEGV) && (sig == SIGSEGV)) ||
185 ((user_debug & UDBG_BUS) && (sig == SIGBUS))) {
186 pr_err("8<--- cut here ---\n");
187 pr_err("%s: unhandled page fault (%d) at 0x%08lx, code 0x%03x\n",
188 tsk->comm, sig, addr, fsr);
189 show_pte(KERN_ERR, tsk->mm, addr);
190 show_regs(regs);
191 }
192#endif
193#ifndef CONFIG_KUSER_HELPERS
194 if ((sig == SIGSEGV) && ((addr & PAGE_MASK) == 0xffff0000))
195 printk_ratelimited(KERN_DEBUG
196 "%s: CONFIG_KUSER_HELPERS disabled at 0x%08lx\n",
197 tsk->comm, addr);
198#endif
199
200 tsk->thread.address = addr;
201 tsk->thread.error_code = fsr;
202 tsk->thread.trap_no = 14;
203 force_sig_fault(sig, code, (void __user *)addr);
204}
205
206void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
207{
208 struct task_struct *tsk = current;
209 struct mm_struct *mm = tsk->active_mm;
210
211 /*
212 * If we are in kernel mode at this point, we
213 * have no context to handle this fault with.
214 */
215 if (user_mode(regs))
216 __do_user_fault(addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
217 else
218 __do_kernel_fault(mm, addr, fsr, regs);
219}
220
221#ifdef CONFIG_MMU
222#define VM_FAULT_BADMAP ((__force vm_fault_t)0x010000)
223#define VM_FAULT_BADACCESS ((__force vm_fault_t)0x020000)
224
225static inline bool is_permission_fault(unsigned int fsr)
226{
227 int fs = fsr_fs(fsr);
228#ifdef CONFIG_ARM_LPAE
229 if ((fs & FS_MMU_NOLL_MASK) == FS_PERM_NOLL)
230 return true;
231#else
232 if (fs == FS_L1_PERM || fs == FS_L2_PERM)
233 return true;
234#endif
235 return false;
236}
237
238static int __kprobes
239do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
240{
241 struct mm_struct *mm = current->mm;
242 struct vm_area_struct *vma;
243 int sig, code;
244 vm_fault_t fault;
245 unsigned int flags = FAULT_FLAG_DEFAULT;
246 unsigned long vm_flags = VM_ACCESS_FLAGS;
247
248 if (kprobe_page_fault(regs, fsr))
249 return 0;
250
251
252 /* Enable interrupts if they were enabled in the parent context. */
253 if (interrupts_enabled(regs))
254 local_irq_enable();
255
256 /*
257 * If we're in an interrupt or have no user
258 * context, we must not take the fault..
259 */
260 if (faulthandler_disabled() || !mm)
261 goto no_context;
262
263 if (user_mode(regs))
264 flags |= FAULT_FLAG_USER;
265
266 if (is_write_fault(fsr)) {
267 flags |= FAULT_FLAG_WRITE;
268 vm_flags = VM_WRITE;
269 }
270
271 if (fsr & FSR_LNX_PF) {
272 vm_flags = VM_EXEC;
273
274 if (is_permission_fault(fsr) && !user_mode(regs))
275 die_kernel_fault("execution of memory",
276 mm, addr, fsr, regs);
277 }
278
279 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
280
281 if (!(flags & FAULT_FLAG_USER))
282 goto lock_mmap;
283
284 vma = lock_vma_under_rcu(mm, addr);
285 if (!vma)
286 goto lock_mmap;
287
288 if (!(vma->vm_flags & vm_flags)) {
289 vma_end_read(vma);
290 goto lock_mmap;
291 }
292 fault = handle_mm_fault(vma, addr, flags | FAULT_FLAG_VMA_LOCK, regs);
293 if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED)))
294 vma_end_read(vma);
295
296 if (!(fault & VM_FAULT_RETRY)) {
297 count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
298 goto done;
299 }
300 count_vm_vma_lock_event(VMA_LOCK_RETRY);
301 if (fault & VM_FAULT_MAJOR)
302 flags |= FAULT_FLAG_TRIED;
303
304 /* Quick path to respond to signals */
305 if (fault_signal_pending(fault, regs)) {
306 if (!user_mode(regs))
307 goto no_context;
308 return 0;
309 }
310lock_mmap:
311
312retry:
313 vma = lock_mm_and_find_vma(mm, addr, regs);
314 if (unlikely(!vma)) {
315 fault = VM_FAULT_BADMAP;
316 goto bad_area;
317 }
318
319 /*
320 * ok, we have a good vm_area for this memory access, check the
321 * permissions on the VMA allow for the fault which occurred.
322 */
323 if (!(vma->vm_flags & vm_flags))
324 fault = VM_FAULT_BADACCESS;
325 else
326 fault = handle_mm_fault(vma, addr & PAGE_MASK, flags, regs);
327
328 /* If we need to retry but a fatal signal is pending, handle the
329 * signal first. We do not need to release the mmap_lock because
330 * it would already be released in __lock_page_or_retry in
331 * mm/filemap.c. */
332 if (fault_signal_pending(fault, regs)) {
333 if (!user_mode(regs))
334 goto no_context;
335 return 0;
336 }
337
338 /* The fault is fully completed (including releasing mmap lock) */
339 if (fault & VM_FAULT_COMPLETED)
340 return 0;
341
342 if (!(fault & VM_FAULT_ERROR)) {
343 if (fault & VM_FAULT_RETRY) {
344 flags |= FAULT_FLAG_TRIED;
345 goto retry;
346 }
347 }
348
349 mmap_read_unlock(mm);
350done:
351
352 /*
353 * Handle the "normal" case first - VM_FAULT_MAJOR
354 */
355 if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS))))
356 return 0;
357
358bad_area:
359 /*
360 * If we are in kernel mode at this point, we
361 * have no context to handle this fault with.
362 */
363 if (!user_mode(regs))
364 goto no_context;
365
366 if (fault & VM_FAULT_OOM) {
367 /*
368 * We ran out of memory, call the OOM killer, and return to
369 * userspace (which will retry the fault, or kill us if we
370 * got oom-killed)
371 */
372 pagefault_out_of_memory();
373 return 0;
374 }
375
376 if (fault & VM_FAULT_SIGBUS) {
377 /*
378 * We had some memory, but were unable to
379 * successfully fix up this page fault.
380 */
381 sig = SIGBUS;
382 code = BUS_ADRERR;
383 } else {
384 /*
385 * Something tried to access memory that
386 * isn't in our memory map..
387 */
388 sig = SIGSEGV;
389 code = fault == VM_FAULT_BADACCESS ?
390 SEGV_ACCERR : SEGV_MAPERR;
391 }
392
393 __do_user_fault(addr, fsr, sig, code, regs);
394 return 0;
395
396no_context:
397 __do_kernel_fault(mm, addr, fsr, regs);
398 return 0;
399}
400#else /* CONFIG_MMU */
401static int
402do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
403{
404 return 0;
405}
406#endif /* CONFIG_MMU */
407
408/*
409 * First Level Translation Fault Handler
410 *
411 * We enter here because the first level page table doesn't contain
412 * a valid entry for the address.
413 *
414 * If the address is in kernel space (>= TASK_SIZE), then we are
415 * probably faulting in the vmalloc() area.
416 *
417 * If the init_task's first level page tables contains the relevant
418 * entry, we copy the it to this task. If not, we send the process
419 * a signal, fixup the exception, or oops the kernel.
420 *
421 * NOTE! We MUST NOT take any locks for this case. We may be in an
422 * interrupt or a critical region, and should only copy the information
423 * from the master page table, nothing more.
424 */
425#ifdef CONFIG_MMU
426static int __kprobes
427do_translation_fault(unsigned long addr, unsigned int fsr,
428 struct pt_regs *regs)
429{
430 unsigned int index;
431 pgd_t *pgd, *pgd_k;
432 p4d_t *p4d, *p4d_k;
433 pud_t *pud, *pud_k;
434 pmd_t *pmd, *pmd_k;
435
436 if (addr < TASK_SIZE)
437 return do_page_fault(addr, fsr, regs);
438
439 if (user_mode(regs))
440 goto bad_area;
441
442 index = pgd_index(addr);
443
444 pgd = cpu_get_pgd() + index;
445 pgd_k = init_mm.pgd + index;
446
447 p4d = p4d_offset(pgd, addr);
448 p4d_k = p4d_offset(pgd_k, addr);
449
450 if (p4d_none(*p4d_k))
451 goto bad_area;
452 if (!p4d_present(*p4d))
453 set_p4d(p4d, *p4d_k);
454
455 pud = pud_offset(p4d, addr);
456 pud_k = pud_offset(p4d_k, addr);
457
458 if (pud_none(*pud_k))
459 goto bad_area;
460 if (!pud_present(*pud))
461 set_pud(pud, *pud_k);
462
463 pmd = pmd_offset(pud, addr);
464 pmd_k = pmd_offset(pud_k, addr);
465
466#ifdef CONFIG_ARM_LPAE
467 /*
468 * Only one hardware entry per PMD with LPAE.
469 */
470 index = 0;
471#else
472 /*
473 * On ARM one Linux PGD entry contains two hardware entries (see page
474 * tables layout in pgtable.h). We normally guarantee that we always
475 * fill both L1 entries. But create_mapping() doesn't follow the rule.
476 * It can create inidividual L1 entries, so here we have to call
477 * pmd_none() check for the entry really corresponded to address, not
478 * for the first of pair.
479 */
480 index = (addr >> SECTION_SHIFT) & 1;
481#endif
482 if (pmd_none(pmd_k[index]))
483 goto bad_area;
484
485 copy_pmd(pmd, pmd_k);
486 return 0;
487
488bad_area:
489 do_bad_area(addr, fsr, regs);
490 return 0;
491}
492#else /* CONFIG_MMU */
493static int
494do_translation_fault(unsigned long addr, unsigned int fsr,
495 struct pt_regs *regs)
496{
497 return 0;
498}
499#endif /* CONFIG_MMU */
500
501/*
502 * Some section permission faults need to be handled gracefully.
503 * They can happen due to a __{get,put}_user during an oops.
504 */
505#ifndef CONFIG_ARM_LPAE
506static int
507do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
508{
509 do_bad_area(addr, fsr, regs);
510 return 0;
511}
512#endif /* CONFIG_ARM_LPAE */
513
514/*
515 * This abort handler always returns "fault".
516 */
517static int
518do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
519{
520 return 1;
521}
522
523struct fsr_info {
524 int (*fn)(unsigned long addr, unsigned int fsr, struct pt_regs *regs);
525 int sig;
526 int code;
527 const char *name;
528};
529
530/* FSR definition */
531#ifdef CONFIG_ARM_LPAE
532#include "fsr-3level.c"
533#else
534#include "fsr-2level.c"
535#endif
536
537void __init
538hook_fault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *),
539 int sig, int code, const char *name)
540{
541 if (nr < 0 || nr >= ARRAY_SIZE(fsr_info))
542 BUG();
543
544 fsr_info[nr].fn = fn;
545 fsr_info[nr].sig = sig;
546 fsr_info[nr].code = code;
547 fsr_info[nr].name = name;
548}
549
550/*
551 * Dispatch a data abort to the relevant handler.
552 */
553asmlinkage void
554do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
555{
556 const struct fsr_info *inf = fsr_info + fsr_fs(fsr);
557
558 if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs))
559 return;
560
561 pr_alert("8<--- cut here ---\n");
562 pr_alert("Unhandled fault: %s (0x%03x) at 0x%08lx\n",
563 inf->name, fsr, addr);
564 show_pte(KERN_ALERT, current->mm, addr);
565
566 arm_notify_die("", regs, inf->sig, inf->code, (void __user *)addr,
567 fsr, 0);
568}
569
570void __init
571hook_ifault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *),
572 int sig, int code, const char *name)
573{
574 if (nr < 0 || nr >= ARRAY_SIZE(ifsr_info))
575 BUG();
576
577 ifsr_info[nr].fn = fn;
578 ifsr_info[nr].sig = sig;
579 ifsr_info[nr].code = code;
580 ifsr_info[nr].name = name;
581}
582
583asmlinkage void
584do_PrefetchAbort(unsigned long addr, unsigned int ifsr, struct pt_regs *regs)
585{
586 const struct fsr_info *inf = ifsr_info + fsr_fs(ifsr);
587
588 if (!inf->fn(addr, ifsr | FSR_LNX_PF, regs))
589 return;
590
591 pr_alert("Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n",
592 inf->name, ifsr, addr);
593
594 arm_notify_die("", regs, inf->sig, inf->code, (void __user *)addr,
595 ifsr, 0);
596}
597
598/*
599 * Abort handler to be used only during first unmasking of asynchronous aborts
600 * on the boot CPU. This makes sure that the machine will not die if the
601 * firmware/bootloader left an imprecise abort pending for us to trip over.
602 */
603static int __init early_abort_handler(unsigned long addr, unsigned int fsr,
604 struct pt_regs *regs)
605{
606 pr_warn("Hit pending asynchronous external abort (FSR=0x%08x) during "
607 "first unmask, this is most likely caused by a "
608 "firmware/bootloader bug.\n", fsr);
609
610 return 0;
611}
612
613void __init early_abt_enable(void)
614{
615 fsr_info[FSR_FS_AEA].fn = early_abort_handler;
616 local_abt_enable();
617 fsr_info[FSR_FS_AEA].fn = do_bad;
618}
619
620#ifndef CONFIG_ARM_LPAE
621static int __init exceptions_init(void)
622{
623 if (cpu_architecture() >= CPU_ARCH_ARMv6) {
624 hook_fault_code(4, do_translation_fault, SIGSEGV, SEGV_MAPERR,
625 "I-cache maintenance fault");
626 }
627
628 if (cpu_architecture() >= CPU_ARCH_ARMv7) {
629 /*
630 * TODO: Access flag faults introduced in ARMv6K.
631 * Runtime check for 'K' extension is needed
632 */
633 hook_fault_code(3, do_bad, SIGSEGV, SEGV_MAPERR,
634 "section access flag fault");
635 hook_fault_code(6, do_bad, SIGSEGV, SEGV_MAPERR,
636 "section access flag fault");
637 }
638
639 return 0;
640}
641
642arch_initcall(exceptions_init);
643#endif