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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
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
21#include <asm/system_misc.h>
22#include <asm/system_info.h>
23#include <asm/tlbflush.h>
24
25#include "fault.h"
26
27#ifdef CONFIG_MMU
28
29/*
30 * This is useful to dump out the page tables associated with
31 * 'addr' in mm 'mm'.
32 */
33void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr)
34{
35 pgd_t *pgd;
36
37 if (!mm)
38 mm = &init_mm;
39
40 printk("%spgd = %p\n", lvl, mm->pgd);
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 pr_cont(", *pte=%08llx", (long long)pte_val(*pte));
89#ifndef CONFIG_ARM_LPAE
90 pr_cont(", *ppte=%08llx",
91 (long long)pte_val(pte[PTE_HWTABLE_PTRS]));
92#endif
93 pte_unmap(pte);
94 } while(0);
95
96 pr_cont("\n");
97}
98#else /* CONFIG_MMU */
99void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr)
100{ }
101#endif /* CONFIG_MMU */
102
103/*
104 * Oops. The kernel tried to access some page that wasn't present.
105 */
106static void
107__do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
108 struct pt_regs *regs)
109{
110 /*
111 * Are we prepared to handle this kernel fault?
112 */
113 if (fixup_exception(regs))
114 return;
115
116 /*
117 * No handler, we'll have to terminate things with extreme prejudice.
118 */
119 bust_spinlocks(1);
120 pr_alert("8<--- cut here ---\n");
121 pr_alert("Unable to handle kernel %s at virtual address %08lx\n",
122 (addr < PAGE_SIZE) ? "NULL pointer dereference" :
123 "paging request", addr);
124
125 show_pte(KERN_ALERT, mm, addr);
126 die("Oops", regs, fsr);
127 bust_spinlocks(0);
128 do_exit(SIGKILL);
129}
130
131/*
132 * Something tried to access memory that isn't in our memory map..
133 * User mode accesses just cause a SIGSEGV
134 */
135static void
136__do_user_fault(unsigned long addr, unsigned int fsr, unsigned int sig,
137 int code, struct pt_regs *regs)
138{
139 struct task_struct *tsk = current;
140
141 if (addr > TASK_SIZE)
142 harden_branch_predictor();
143
144#ifdef CONFIG_DEBUG_USER
145 if (((user_debug & UDBG_SEGV) && (sig == SIGSEGV)) ||
146 ((user_debug & UDBG_BUS) && (sig == SIGBUS))) {
147 pr_err("8<--- cut here ---\n");
148 pr_err("%s: unhandled page fault (%d) at 0x%08lx, code 0x%03x\n",
149 tsk->comm, sig, addr, fsr);
150 show_pte(KERN_ERR, tsk->mm, addr);
151 show_regs(regs);
152 }
153#endif
154#ifndef CONFIG_KUSER_HELPERS
155 if ((sig == SIGSEGV) && ((addr & PAGE_MASK) == 0xffff0000))
156 printk_ratelimited(KERN_DEBUG
157 "%s: CONFIG_KUSER_HELPERS disabled at 0x%08lx\n",
158 tsk->comm, addr);
159#endif
160
161 tsk->thread.address = addr;
162 tsk->thread.error_code = fsr;
163 tsk->thread.trap_no = 14;
164 force_sig_fault(sig, code, (void __user *)addr);
165}
166
167void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
168{
169 struct task_struct *tsk = current;
170 struct mm_struct *mm = tsk->active_mm;
171
172 /*
173 * If we are in kernel mode at this point, we
174 * have no context to handle this fault with.
175 */
176 if (user_mode(regs))
177 __do_user_fault(addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
178 else
179 __do_kernel_fault(mm, addr, fsr, regs);
180}
181
182#ifdef CONFIG_MMU
183#define VM_FAULT_BADMAP 0x010000
184#define VM_FAULT_BADACCESS 0x020000
185
186/*
187 * Check that the permissions on the VMA allow for the fault which occurred.
188 * If we encountered a write fault, we must have write permission, otherwise
189 * we allow any permission.
190 */
191static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma)
192{
193 unsigned int mask = VM_ACCESS_FLAGS;
194
195 if ((fsr & FSR_WRITE) && !(fsr & FSR_CM))
196 mask = VM_WRITE;
197 if (fsr & FSR_LNX_PF)
198 mask = VM_EXEC;
199
200 return vma->vm_flags & mask ? false : true;
201}
202
203static vm_fault_t __kprobes
204__do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
205 unsigned int flags, struct task_struct *tsk,
206 struct pt_regs *regs)
207{
208 struct vm_area_struct *vma;
209 vm_fault_t fault;
210
211 vma = find_vma(mm, addr);
212 fault = VM_FAULT_BADMAP;
213 if (unlikely(!vma))
214 goto out;
215 if (unlikely(vma->vm_start > addr))
216 goto check_stack;
217
218 /*
219 * Ok, we have a good vm_area for this
220 * memory access, so we can handle it.
221 */
222good_area:
223 if (access_error(fsr, vma)) {
224 fault = VM_FAULT_BADACCESS;
225 goto out;
226 }
227
228 return handle_mm_fault(vma, addr & PAGE_MASK, flags, regs);
229
230check_stack:
231 /* Don't allow expansion below FIRST_USER_ADDRESS */
232 if (vma->vm_flags & VM_GROWSDOWN &&
233 addr >= FIRST_USER_ADDRESS && !expand_stack(vma, addr))
234 goto good_area;
235out:
236 return fault;
237}
238
239static int __kprobes
240do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
241{
242 struct task_struct *tsk;
243 struct mm_struct *mm;
244 int sig, code;
245 vm_fault_t fault;
246 unsigned int flags = FAULT_FLAG_DEFAULT;
247
248 if (kprobe_page_fault(regs, fsr))
249 return 0;
250
251 tsk = current;
252 mm = tsk->mm;
253
254 /* Enable interrupts if they were enabled in the parent context. */
255 if (interrupts_enabled(regs))
256 local_irq_enable();
257
258 /*
259 * If we're in an interrupt or have no user
260 * context, we must not take the fault..
261 */
262 if (faulthandler_disabled() || !mm)
263 goto no_context;
264
265 if (user_mode(regs))
266 flags |= FAULT_FLAG_USER;
267 if ((fsr & FSR_WRITE) && !(fsr & FSR_CM))
268 flags |= FAULT_FLAG_WRITE;
269
270 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
271
272 /*
273 * As per x86, we may deadlock here. However, since the kernel only
274 * validly references user space from well defined areas of the code,
275 * we can bug out early if this is from code which shouldn't.
276 */
277 if (!mmap_read_trylock(mm)) {
278 if (!user_mode(regs) && !search_exception_tables(regs->ARM_pc))
279 goto no_context;
280retry:
281 mmap_read_lock(mm);
282 } else {
283 /*
284 * The above down_read_trylock() might have succeeded in
285 * which case, we'll have missed the might_sleep() from
286 * down_read()
287 */
288 might_sleep();
289#ifdef CONFIG_DEBUG_VM
290 if (!user_mode(regs) &&
291 !search_exception_tables(regs->ARM_pc))
292 goto no_context;
293#endif
294 }
295
296 fault = __do_page_fault(mm, addr, fsr, flags, tsk, regs);
297
298 /* If we need to retry but a fatal signal is pending, handle the
299 * signal first. We do not need to release the mmap_lock because
300 * it would already be released in __lock_page_or_retry in
301 * mm/filemap.c. */
302 if (fault_signal_pending(fault, regs)) {
303 if (!user_mode(regs))
304 goto no_context;
305 return 0;
306 }
307
308 if (!(fault & VM_FAULT_ERROR) && flags & FAULT_FLAG_ALLOW_RETRY) {
309 if (fault & VM_FAULT_RETRY) {
310 flags |= FAULT_FLAG_TRIED;
311 goto retry;
312 }
313 }
314
315 mmap_read_unlock(mm);
316
317 /*
318 * Handle the "normal" case first - VM_FAULT_MAJOR
319 */
320 if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS))))
321 return 0;
322
323 /*
324 * If we are in kernel mode at this point, we
325 * have no context to handle this fault with.
326 */
327 if (!user_mode(regs))
328 goto no_context;
329
330 if (fault & VM_FAULT_OOM) {
331 /*
332 * We ran out of memory, call the OOM killer, and return to
333 * userspace (which will retry the fault, or kill us if we
334 * got oom-killed)
335 */
336 pagefault_out_of_memory();
337 return 0;
338 }
339
340 if (fault & VM_FAULT_SIGBUS) {
341 /*
342 * We had some memory, but were unable to
343 * successfully fix up this page fault.
344 */
345 sig = SIGBUS;
346 code = BUS_ADRERR;
347 } else {
348 /*
349 * Something tried to access memory that
350 * isn't in our memory map..
351 */
352 sig = SIGSEGV;
353 code = fault == VM_FAULT_BADACCESS ?
354 SEGV_ACCERR : SEGV_MAPERR;
355 }
356
357 __do_user_fault(addr, fsr, sig, code, regs);
358 return 0;
359
360no_context:
361 __do_kernel_fault(mm, addr, fsr, regs);
362 return 0;
363}
364#else /* CONFIG_MMU */
365static int
366do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
367{
368 return 0;
369}
370#endif /* CONFIG_MMU */
371
372/*
373 * First Level Translation Fault Handler
374 *
375 * We enter here because the first level page table doesn't contain
376 * a valid entry for the address.
377 *
378 * If the address is in kernel space (>= TASK_SIZE), then we are
379 * probably faulting in the vmalloc() area.
380 *
381 * If the init_task's first level page tables contains the relevant
382 * entry, we copy the it to this task. If not, we send the process
383 * a signal, fixup the exception, or oops the kernel.
384 *
385 * NOTE! We MUST NOT take any locks for this case. We may be in an
386 * interrupt or a critical region, and should only copy the information
387 * from the master page table, nothing more.
388 */
389#ifdef CONFIG_MMU
390static int __kprobes
391do_translation_fault(unsigned long addr, unsigned int fsr,
392 struct pt_regs *regs)
393{
394 unsigned int index;
395 pgd_t *pgd, *pgd_k;
396 p4d_t *p4d, *p4d_k;
397 pud_t *pud, *pud_k;
398 pmd_t *pmd, *pmd_k;
399
400 if (addr < TASK_SIZE)
401 return do_page_fault(addr, fsr, regs);
402
403 if (user_mode(regs))
404 goto bad_area;
405
406 index = pgd_index(addr);
407
408 pgd = cpu_get_pgd() + index;
409 pgd_k = init_mm.pgd + index;
410
411 p4d = p4d_offset(pgd, addr);
412 p4d_k = p4d_offset(pgd_k, addr);
413
414 if (p4d_none(*p4d_k))
415 goto bad_area;
416 if (!p4d_present(*p4d))
417 set_p4d(p4d, *p4d_k);
418
419 pud = pud_offset(p4d, addr);
420 pud_k = pud_offset(p4d_k, addr);
421
422 if (pud_none(*pud_k))
423 goto bad_area;
424 if (!pud_present(*pud))
425 set_pud(pud, *pud_k);
426
427 pmd = pmd_offset(pud, addr);
428 pmd_k = pmd_offset(pud_k, addr);
429
430#ifdef CONFIG_ARM_LPAE
431 /*
432 * Only one hardware entry per PMD with LPAE.
433 */
434 index = 0;
435#else
436 /*
437 * On ARM one Linux PGD entry contains two hardware entries (see page
438 * tables layout in pgtable.h). We normally guarantee that we always
439 * fill both L1 entries. But create_mapping() doesn't follow the rule.
440 * It can create inidividual L1 entries, so here we have to call
441 * pmd_none() check for the entry really corresponded to address, not
442 * for the first of pair.
443 */
444 index = (addr >> SECTION_SHIFT) & 1;
445#endif
446 if (pmd_none(pmd_k[index]))
447 goto bad_area;
448
449 copy_pmd(pmd, pmd_k);
450 return 0;
451
452bad_area:
453 do_bad_area(addr, fsr, regs);
454 return 0;
455}
456#else /* CONFIG_MMU */
457static int
458do_translation_fault(unsigned long addr, unsigned int fsr,
459 struct pt_regs *regs)
460{
461 return 0;
462}
463#endif /* CONFIG_MMU */
464
465/*
466 * Some section permission faults need to be handled gracefully.
467 * They can happen due to a __{get,put}_user during an oops.
468 */
469#ifndef CONFIG_ARM_LPAE
470static int
471do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
472{
473 do_bad_area(addr, fsr, regs);
474 return 0;
475}
476#endif /* CONFIG_ARM_LPAE */
477
478/*
479 * This abort handler always returns "fault".
480 */
481static int
482do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
483{
484 return 1;
485}
486
487struct fsr_info {
488 int (*fn)(unsigned long addr, unsigned int fsr, struct pt_regs *regs);
489 int sig;
490 int code;
491 const char *name;
492};
493
494/* FSR definition */
495#ifdef CONFIG_ARM_LPAE
496#include "fsr-3level.c"
497#else
498#include "fsr-2level.c"
499#endif
500
501void __init
502hook_fault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *),
503 int sig, int code, const char *name)
504{
505 if (nr < 0 || nr >= ARRAY_SIZE(fsr_info))
506 BUG();
507
508 fsr_info[nr].fn = fn;
509 fsr_info[nr].sig = sig;
510 fsr_info[nr].code = code;
511 fsr_info[nr].name = name;
512}
513
514/*
515 * Dispatch a data abort to the relevant handler.
516 */
517asmlinkage void
518do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
519{
520 const struct fsr_info *inf = fsr_info + fsr_fs(fsr);
521
522 if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs))
523 return;
524
525 pr_alert("8<--- cut here ---\n");
526 pr_alert("Unhandled fault: %s (0x%03x) at 0x%08lx\n",
527 inf->name, fsr, addr);
528 show_pte(KERN_ALERT, current->mm, addr);
529
530 arm_notify_die("", regs, inf->sig, inf->code, (void __user *)addr,
531 fsr, 0);
532}
533
534void __init
535hook_ifault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *),
536 int sig, int code, const char *name)
537{
538 if (nr < 0 || nr >= ARRAY_SIZE(ifsr_info))
539 BUG();
540
541 ifsr_info[nr].fn = fn;
542 ifsr_info[nr].sig = sig;
543 ifsr_info[nr].code = code;
544 ifsr_info[nr].name = name;
545}
546
547asmlinkage void
548do_PrefetchAbort(unsigned long addr, unsigned int ifsr, struct pt_regs *regs)
549{
550 const struct fsr_info *inf = ifsr_info + fsr_fs(ifsr);
551
552 if (!inf->fn(addr, ifsr | FSR_LNX_PF, regs))
553 return;
554
555 pr_alert("Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n",
556 inf->name, ifsr, addr);
557
558 arm_notify_die("", regs, inf->sig, inf->code, (void __user *)addr,
559 ifsr, 0);
560}
561
562/*
563 * Abort handler to be used only during first unmasking of asynchronous aborts
564 * on the boot CPU. This makes sure that the machine will not die if the
565 * firmware/bootloader left an imprecise abort pending for us to trip over.
566 */
567static int __init early_abort_handler(unsigned long addr, unsigned int fsr,
568 struct pt_regs *regs)
569{
570 pr_warn("Hit pending asynchronous external abort (FSR=0x%08x) during "
571 "first unmask, this is most likely caused by a "
572 "firmware/bootloader bug.\n", fsr);
573
574 return 0;
575}
576
577void __init early_abt_enable(void)
578{
579 fsr_info[FSR_FS_AEA].fn = early_abort_handler;
580 local_abt_enable();
581 fsr_info[FSR_FS_AEA].fn = do_bad;
582}
583
584#ifndef CONFIG_ARM_LPAE
585static int __init exceptions_init(void)
586{
587 if (cpu_architecture() >= CPU_ARCH_ARMv6) {
588 hook_fault_code(4, do_translation_fault, SIGSEGV, SEGV_MAPERR,
589 "I-cache maintenance fault");
590 }
591
592 if (cpu_architecture() >= CPU_ARCH_ARMv7) {
593 /*
594 * TODO: Access flag faults introduced in ARMv6K.
595 * Runtime check for 'K' extension is needed
596 */
597 hook_fault_code(3, do_bad, SIGSEGV, SEGV_MAPERR,
598 "section access flag fault");
599 hook_fault_code(6, do_bad, SIGSEGV, SEGV_MAPERR,
600 "section access flag fault");
601 }
602
603 return 0;
604}
605
606arch_initcall(exceptions_init);
607#endif