xref: /openbmc/linux/arch/arm64/mm/fault.c (revision f7c35abe)
1 /*
2  * Based on arch/arm/mm/fault.c
3  *
4  * Copyright (C) 1995  Linus Torvalds
5  * Copyright (C) 1995-2004 Russell King
6  * Copyright (C) 2012 ARM Ltd.
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License version 2 as
10  * published by the Free Software Foundation.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License
18  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
19  */
20 
21 #include <linux/extable.h>
22 #include <linux/signal.h>
23 #include <linux/mm.h>
24 #include <linux/hardirq.h>
25 #include <linux/init.h>
26 #include <linux/kprobes.h>
27 #include <linux/uaccess.h>
28 #include <linux/page-flags.h>
29 #include <linux/sched/signal.h>
30 #include <linux/sched/debug.h>
31 #include <linux/highmem.h>
32 #include <linux/perf_event.h>
33 #include <linux/preempt.h>
34 
35 #include <asm/bug.h>
36 #include <asm/cpufeature.h>
37 #include <asm/exception.h>
38 #include <asm/debug-monitors.h>
39 #include <asm/esr.h>
40 #include <asm/sysreg.h>
41 #include <asm/system_misc.h>
42 #include <asm/pgtable.h>
43 #include <asm/tlbflush.h>
44 
45 static const char *fault_name(unsigned int esr);
46 
47 #ifdef CONFIG_KPROBES
48 static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr)
49 {
50 	int ret = 0;
51 
52 	/* kprobe_running() needs smp_processor_id() */
53 	if (!user_mode(regs)) {
54 		preempt_disable();
55 		if (kprobe_running() && kprobe_fault_handler(regs, esr))
56 			ret = 1;
57 		preempt_enable();
58 	}
59 
60 	return ret;
61 }
62 #else
63 static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr)
64 {
65 	return 0;
66 }
67 #endif
68 
69 /*
70  * Dump out the page tables associated with 'addr' in mm 'mm'.
71  */
72 void show_pte(struct mm_struct *mm, unsigned long addr)
73 {
74 	pgd_t *pgd;
75 
76 	if (!mm)
77 		mm = &init_mm;
78 
79 	pr_alert("pgd = %p\n", mm->pgd);
80 	pgd = pgd_offset(mm, addr);
81 	pr_alert("[%08lx] *pgd=%016llx", addr, pgd_val(*pgd));
82 
83 	do {
84 		pud_t *pud;
85 		pmd_t *pmd;
86 		pte_t *pte;
87 
88 		if (pgd_none(*pgd) || pgd_bad(*pgd))
89 			break;
90 
91 		pud = pud_offset(pgd, addr);
92 		pr_cont(", *pud=%016llx", pud_val(*pud));
93 		if (pud_none(*pud) || pud_bad(*pud))
94 			break;
95 
96 		pmd = pmd_offset(pud, addr);
97 		pr_cont(", *pmd=%016llx", pmd_val(*pmd));
98 		if (pmd_none(*pmd) || pmd_bad(*pmd))
99 			break;
100 
101 		pte = pte_offset_map(pmd, addr);
102 		pr_cont(", *pte=%016llx", pte_val(*pte));
103 		pte_unmap(pte);
104 	} while(0);
105 
106 	pr_cont("\n");
107 }
108 
109 #ifdef CONFIG_ARM64_HW_AFDBM
110 /*
111  * This function sets the access flags (dirty, accessed), as well as write
112  * permission, and only to a more permissive setting.
113  *
114  * It needs to cope with hardware update of the accessed/dirty state by other
115  * agents in the system and can safely skip the __sync_icache_dcache() call as,
116  * like set_pte_at(), the PTE is never changed from no-exec to exec here.
117  *
118  * Returns whether or not the PTE actually changed.
119  */
120 int ptep_set_access_flags(struct vm_area_struct *vma,
121 			  unsigned long address, pte_t *ptep,
122 			  pte_t entry, int dirty)
123 {
124 	pteval_t old_pteval;
125 	unsigned int tmp;
126 
127 	if (pte_same(*ptep, entry))
128 		return 0;
129 
130 	/* only preserve the access flags and write permission */
131 	pte_val(entry) &= PTE_AF | PTE_WRITE | PTE_DIRTY;
132 
133 	/*
134 	 * PTE_RDONLY is cleared by default in the asm below, so set it in
135 	 * back if necessary (read-only or clean PTE).
136 	 */
137 	if (!pte_write(entry) || !pte_sw_dirty(entry))
138 		pte_val(entry) |= PTE_RDONLY;
139 
140 	/*
141 	 * Setting the flags must be done atomically to avoid racing with the
142 	 * hardware update of the access/dirty state.
143 	 */
144 	asm volatile("//	ptep_set_access_flags\n"
145 	"	prfm	pstl1strm, %2\n"
146 	"1:	ldxr	%0, %2\n"
147 	"	and	%0, %0, %3		// clear PTE_RDONLY\n"
148 	"	orr	%0, %0, %4		// set flags\n"
149 	"	stxr	%w1, %0, %2\n"
150 	"	cbnz	%w1, 1b\n"
151 	: "=&r" (old_pteval), "=&r" (tmp), "+Q" (pte_val(*ptep))
152 	: "L" (~PTE_RDONLY), "r" (pte_val(entry)));
153 
154 	flush_tlb_fix_spurious_fault(vma, address);
155 	return 1;
156 }
157 #endif
158 
159 static bool is_el1_instruction_abort(unsigned int esr)
160 {
161 	return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_CUR;
162 }
163 
164 /*
165  * The kernel tried to access some page that wasn't present.
166  */
167 static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr,
168 			      unsigned int esr, struct pt_regs *regs)
169 {
170 	/*
171 	 * Are we prepared to handle this kernel fault?
172 	 * We are almost certainly not prepared to handle instruction faults.
173 	 */
174 	if (!is_el1_instruction_abort(esr) && fixup_exception(regs))
175 		return;
176 
177 	/*
178 	 * No handler, we'll have to terminate things with extreme prejudice.
179 	 */
180 	bust_spinlocks(1);
181 	pr_alert("Unable to handle kernel %s at virtual address %08lx\n",
182 		 (addr < PAGE_SIZE) ? "NULL pointer dereference" :
183 		 "paging request", addr);
184 
185 	show_pte(mm, addr);
186 	die("Oops", regs, esr);
187 	bust_spinlocks(0);
188 	do_exit(SIGKILL);
189 }
190 
191 /*
192  * Something tried to access memory that isn't in our memory map. User mode
193  * accesses just cause a SIGSEGV
194  */
195 static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
196 			    unsigned int esr, unsigned int sig, int code,
197 			    struct pt_regs *regs)
198 {
199 	struct siginfo si;
200 
201 	if (unhandled_signal(tsk, sig) && show_unhandled_signals_ratelimited()) {
202 		pr_info("%s[%d]: unhandled %s (%d) at 0x%08lx, esr 0x%03x\n",
203 			tsk->comm, task_pid_nr(tsk), fault_name(esr), sig,
204 			addr, esr);
205 		show_pte(tsk->mm, addr);
206 		show_regs(regs);
207 	}
208 
209 	tsk->thread.fault_address = addr;
210 	tsk->thread.fault_code = esr;
211 	si.si_signo = sig;
212 	si.si_errno = 0;
213 	si.si_code = code;
214 	si.si_addr = (void __user *)addr;
215 	force_sig_info(sig, &si, tsk);
216 }
217 
218 static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *regs)
219 {
220 	struct task_struct *tsk = current;
221 	struct mm_struct *mm = tsk->active_mm;
222 
223 	/*
224 	 * If we are in kernel mode at this point, we have no context to
225 	 * handle this fault with.
226 	 */
227 	if (user_mode(regs))
228 		__do_user_fault(tsk, addr, esr, SIGSEGV, SEGV_MAPERR, regs);
229 	else
230 		__do_kernel_fault(mm, addr, esr, regs);
231 }
232 
233 #define VM_FAULT_BADMAP		0x010000
234 #define VM_FAULT_BADACCESS	0x020000
235 
236 static int __do_page_fault(struct mm_struct *mm, unsigned long addr,
237 			   unsigned int mm_flags, unsigned long vm_flags,
238 			   struct task_struct *tsk)
239 {
240 	struct vm_area_struct *vma;
241 	int fault;
242 
243 	vma = find_vma(mm, addr);
244 	fault = VM_FAULT_BADMAP;
245 	if (unlikely(!vma))
246 		goto out;
247 	if (unlikely(vma->vm_start > addr))
248 		goto check_stack;
249 
250 	/*
251 	 * Ok, we have a good vm_area for this memory access, so we can handle
252 	 * it.
253 	 */
254 good_area:
255 	/*
256 	 * Check that the permissions on the VMA allow for the fault which
257 	 * occurred.
258 	 */
259 	if (!(vma->vm_flags & vm_flags)) {
260 		fault = VM_FAULT_BADACCESS;
261 		goto out;
262 	}
263 
264 	return handle_mm_fault(vma, addr & PAGE_MASK, mm_flags);
265 
266 check_stack:
267 	if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
268 		goto good_area;
269 out:
270 	return fault;
271 }
272 
273 static inline bool is_permission_fault(unsigned int esr, struct pt_regs *regs)
274 {
275 	unsigned int ec       = ESR_ELx_EC(esr);
276 	unsigned int fsc_type = esr & ESR_ELx_FSC_TYPE;
277 
278 	if (ec != ESR_ELx_EC_DABT_CUR && ec != ESR_ELx_EC_IABT_CUR)
279 		return false;
280 
281 	if (system_uses_ttbr0_pan())
282 		return fsc_type == ESR_ELx_FSC_FAULT &&
283 			(regs->pstate & PSR_PAN_BIT);
284 	else
285 		return fsc_type == ESR_ELx_FSC_PERM;
286 }
287 
288 static bool is_el0_instruction_abort(unsigned int esr)
289 {
290 	return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_LOW;
291 }
292 
293 static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
294 				   struct pt_regs *regs)
295 {
296 	struct task_struct *tsk;
297 	struct mm_struct *mm;
298 	int fault, sig, code;
299 	unsigned long vm_flags = VM_READ | VM_WRITE;
300 	unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
301 
302 	if (notify_page_fault(regs, esr))
303 		return 0;
304 
305 	tsk = current;
306 	mm  = tsk->mm;
307 
308 	/*
309 	 * If we're in an interrupt or have no user context, we must not take
310 	 * the fault.
311 	 */
312 	if (faulthandler_disabled() || !mm)
313 		goto no_context;
314 
315 	if (user_mode(regs))
316 		mm_flags |= FAULT_FLAG_USER;
317 
318 	if (is_el0_instruction_abort(esr)) {
319 		vm_flags = VM_EXEC;
320 	} else if ((esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM)) {
321 		vm_flags = VM_WRITE;
322 		mm_flags |= FAULT_FLAG_WRITE;
323 	}
324 
325 	if (addr < USER_DS && is_permission_fault(esr, regs)) {
326 		/* regs->orig_addr_limit may be 0 if we entered from EL0 */
327 		if (regs->orig_addr_limit == KERNEL_DS)
328 			die("Accessing user space memory with fs=KERNEL_DS", regs, esr);
329 
330 		if (is_el1_instruction_abort(esr))
331 			die("Attempting to execute userspace memory", regs, esr);
332 
333 		if (!search_exception_tables(regs->pc))
334 			die("Accessing user space memory outside uaccess.h routines", regs, esr);
335 	}
336 
337 	/*
338 	 * As per x86, we may deadlock here. However, since the kernel only
339 	 * validly references user space from well defined areas of the code,
340 	 * we can bug out early if this is from code which shouldn't.
341 	 */
342 	if (!down_read_trylock(&mm->mmap_sem)) {
343 		if (!user_mode(regs) && !search_exception_tables(regs->pc))
344 			goto no_context;
345 retry:
346 		down_read(&mm->mmap_sem);
347 	} else {
348 		/*
349 		 * The above down_read_trylock() might have succeeded in which
350 		 * case, we'll have missed the might_sleep() from down_read().
351 		 */
352 		might_sleep();
353 #ifdef CONFIG_DEBUG_VM
354 		if (!user_mode(regs) && !search_exception_tables(regs->pc))
355 			goto no_context;
356 #endif
357 	}
358 
359 	fault = __do_page_fault(mm, addr, mm_flags, vm_flags, tsk);
360 
361 	/*
362 	 * If we need to retry but a fatal signal is pending, handle the
363 	 * signal first. We do not need to release the mmap_sem because it
364 	 * would already be released in __lock_page_or_retry in mm/filemap.c.
365 	 */
366 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
367 		return 0;
368 
369 	/*
370 	 * Major/minor page fault accounting is only done on the initial
371 	 * attempt. If we go through a retry, it is extremely likely that the
372 	 * page will be found in page cache at that point.
373 	 */
374 
375 	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
376 	if (mm_flags & FAULT_FLAG_ALLOW_RETRY) {
377 		if (fault & VM_FAULT_MAJOR) {
378 			tsk->maj_flt++;
379 			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs,
380 				      addr);
381 		} else {
382 			tsk->min_flt++;
383 			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs,
384 				      addr);
385 		}
386 		if (fault & VM_FAULT_RETRY) {
387 			/*
388 			 * Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk of
389 			 * starvation.
390 			 */
391 			mm_flags &= ~FAULT_FLAG_ALLOW_RETRY;
392 			mm_flags |= FAULT_FLAG_TRIED;
393 			goto retry;
394 		}
395 	}
396 
397 	up_read(&mm->mmap_sem);
398 
399 	/*
400 	 * Handle the "normal" case first - VM_FAULT_MAJOR
401 	 */
402 	if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP |
403 			      VM_FAULT_BADACCESS))))
404 		return 0;
405 
406 	/*
407 	 * If we are in kernel mode at this point, we have no context to
408 	 * handle this fault with.
409 	 */
410 	if (!user_mode(regs))
411 		goto no_context;
412 
413 	if (fault & VM_FAULT_OOM) {
414 		/*
415 		 * We ran out of memory, call the OOM killer, and return to
416 		 * userspace (which will retry the fault, or kill us if we got
417 		 * oom-killed).
418 		 */
419 		pagefault_out_of_memory();
420 		return 0;
421 	}
422 
423 	if (fault & VM_FAULT_SIGBUS) {
424 		/*
425 		 * We had some memory, but were unable to successfully fix up
426 		 * this page fault.
427 		 */
428 		sig = SIGBUS;
429 		code = BUS_ADRERR;
430 	} else {
431 		/*
432 		 * Something tried to access memory that isn't in our memory
433 		 * map.
434 		 */
435 		sig = SIGSEGV;
436 		code = fault == VM_FAULT_BADACCESS ?
437 			SEGV_ACCERR : SEGV_MAPERR;
438 	}
439 
440 	__do_user_fault(tsk, addr, esr, sig, code, regs);
441 	return 0;
442 
443 no_context:
444 	__do_kernel_fault(mm, addr, esr, regs);
445 	return 0;
446 }
447 
448 /*
449  * First Level Translation Fault Handler
450  *
451  * We enter here because the first level page table doesn't contain a valid
452  * entry for the address.
453  *
454  * If the address is in kernel space (>= TASK_SIZE), then we are probably
455  * faulting in the vmalloc() area.
456  *
457  * If the init_task's first level page tables contains the relevant entry, we
458  * copy the it to this task.  If not, we send the process a signal, fixup the
459  * exception, or oops the kernel.
460  *
461  * NOTE! We MUST NOT take any locks for this case. We may be in an interrupt
462  * or a critical region, and should only copy the information from the master
463  * page table, nothing more.
464  */
465 static int __kprobes do_translation_fault(unsigned long addr,
466 					  unsigned int esr,
467 					  struct pt_regs *regs)
468 {
469 	if (addr < TASK_SIZE)
470 		return do_page_fault(addr, esr, regs);
471 
472 	do_bad_area(addr, esr, regs);
473 	return 0;
474 }
475 
476 static int do_alignment_fault(unsigned long addr, unsigned int esr,
477 			      struct pt_regs *regs)
478 {
479 	do_bad_area(addr, esr, regs);
480 	return 0;
481 }
482 
483 /*
484  * This abort handler always returns "fault".
485  */
486 static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs)
487 {
488 	return 1;
489 }
490 
491 static const struct fault_info {
492 	int	(*fn)(unsigned long addr, unsigned int esr, struct pt_regs *regs);
493 	int	sig;
494 	int	code;
495 	const char *name;
496 } fault_info[] = {
497 	{ do_bad,		SIGBUS,  0,		"ttbr address size fault"	},
498 	{ do_bad,		SIGBUS,  0,		"level 1 address size fault"	},
499 	{ do_bad,		SIGBUS,  0,		"level 2 address size fault"	},
500 	{ do_bad,		SIGBUS,  0,		"level 3 address size fault"	},
501 	{ do_translation_fault,	SIGSEGV, SEGV_MAPERR,	"level 0 translation fault"	},
502 	{ do_translation_fault,	SIGSEGV, SEGV_MAPERR,	"level 1 translation fault"	},
503 	{ do_translation_fault,	SIGSEGV, SEGV_MAPERR,	"level 2 translation fault"	},
504 	{ do_page_fault,	SIGSEGV, SEGV_MAPERR,	"level 3 translation fault"	},
505 	{ do_bad,		SIGBUS,  0,		"unknown 8"			},
506 	{ do_page_fault,	SIGSEGV, SEGV_ACCERR,	"level 1 access flag fault"	},
507 	{ do_page_fault,	SIGSEGV, SEGV_ACCERR,	"level 2 access flag fault"	},
508 	{ do_page_fault,	SIGSEGV, SEGV_ACCERR,	"level 3 access flag fault"	},
509 	{ do_bad,		SIGBUS,  0,		"unknown 12"			},
510 	{ do_page_fault,	SIGSEGV, SEGV_ACCERR,	"level 1 permission fault"	},
511 	{ do_page_fault,	SIGSEGV, SEGV_ACCERR,	"level 2 permission fault"	},
512 	{ do_page_fault,	SIGSEGV, SEGV_ACCERR,	"level 3 permission fault"	},
513 	{ do_bad,		SIGBUS,  0,		"synchronous external abort"	},
514 	{ do_bad,		SIGBUS,  0,		"unknown 17"			},
515 	{ do_bad,		SIGBUS,  0,		"unknown 18"			},
516 	{ do_bad,		SIGBUS,  0,		"unknown 19"			},
517 	{ do_bad,		SIGBUS,  0,		"synchronous external abort (translation table walk)" },
518 	{ do_bad,		SIGBUS,  0,		"synchronous external abort (translation table walk)" },
519 	{ do_bad,		SIGBUS,  0,		"synchronous external abort (translation table walk)" },
520 	{ do_bad,		SIGBUS,  0,		"synchronous external abort (translation table walk)" },
521 	{ do_bad,		SIGBUS,  0,		"synchronous parity error"	},
522 	{ do_bad,		SIGBUS,  0,		"unknown 25"			},
523 	{ do_bad,		SIGBUS,  0,		"unknown 26"			},
524 	{ do_bad,		SIGBUS,  0,		"unknown 27"			},
525 	{ do_bad,		SIGBUS,  0,		"synchronous parity error (translation table walk)" },
526 	{ do_bad,		SIGBUS,  0,		"synchronous parity error (translation table walk)" },
527 	{ do_bad,		SIGBUS,  0,		"synchronous parity error (translation table walk)" },
528 	{ do_bad,		SIGBUS,  0,		"synchronous parity error (translation table walk)" },
529 	{ do_bad,		SIGBUS,  0,		"unknown 32"			},
530 	{ do_alignment_fault,	SIGBUS,  BUS_ADRALN,	"alignment fault"		},
531 	{ do_bad,		SIGBUS,  0,		"unknown 34"			},
532 	{ do_bad,		SIGBUS,  0,		"unknown 35"			},
533 	{ do_bad,		SIGBUS,  0,		"unknown 36"			},
534 	{ do_bad,		SIGBUS,  0,		"unknown 37"			},
535 	{ do_bad,		SIGBUS,  0,		"unknown 38"			},
536 	{ do_bad,		SIGBUS,  0,		"unknown 39"			},
537 	{ do_bad,		SIGBUS,  0,		"unknown 40"			},
538 	{ do_bad,		SIGBUS,  0,		"unknown 41"			},
539 	{ do_bad,		SIGBUS,  0,		"unknown 42"			},
540 	{ do_bad,		SIGBUS,  0,		"unknown 43"			},
541 	{ do_bad,		SIGBUS,  0,		"unknown 44"			},
542 	{ do_bad,		SIGBUS,  0,		"unknown 45"			},
543 	{ do_bad,		SIGBUS,  0,		"unknown 46"			},
544 	{ do_bad,		SIGBUS,  0,		"unknown 47"			},
545 	{ do_bad,		SIGBUS,  0,		"TLB conflict abort"		},
546 	{ do_bad,		SIGBUS,  0,		"unknown 49"			},
547 	{ do_bad,		SIGBUS,  0,		"unknown 50"			},
548 	{ do_bad,		SIGBUS,  0,		"unknown 51"			},
549 	{ do_bad,		SIGBUS,  0,		"implementation fault (lockdown abort)" },
550 	{ do_bad,		SIGBUS,  0,		"implementation fault (unsupported exclusive)" },
551 	{ do_bad,		SIGBUS,  0,		"unknown 54"			},
552 	{ do_bad,		SIGBUS,  0,		"unknown 55"			},
553 	{ do_bad,		SIGBUS,  0,		"unknown 56"			},
554 	{ do_bad,		SIGBUS,  0,		"unknown 57"			},
555 	{ do_bad,		SIGBUS,  0,		"unknown 58" 			},
556 	{ do_bad,		SIGBUS,  0,		"unknown 59"			},
557 	{ do_bad,		SIGBUS,  0,		"unknown 60"			},
558 	{ do_bad,		SIGBUS,  0,		"section domain fault"		},
559 	{ do_bad,		SIGBUS,  0,		"page domain fault"		},
560 	{ do_bad,		SIGBUS,  0,		"unknown 63"			},
561 };
562 
563 static const char *fault_name(unsigned int esr)
564 {
565 	const struct fault_info *inf = fault_info + (esr & 63);
566 	return inf->name;
567 }
568 
569 /*
570  * Dispatch a data abort to the relevant handler.
571  */
572 asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr,
573 					 struct pt_regs *regs)
574 {
575 	const struct fault_info *inf = fault_info + (esr & 63);
576 	struct siginfo info;
577 
578 	if (!inf->fn(addr, esr, regs))
579 		return;
580 
581 	pr_alert("Unhandled fault: %s (0x%08x) at 0x%016lx\n",
582 		 inf->name, esr, addr);
583 
584 	info.si_signo = inf->sig;
585 	info.si_errno = 0;
586 	info.si_code  = inf->code;
587 	info.si_addr  = (void __user *)addr;
588 	arm64_notify_die("", regs, &info, esr);
589 }
590 
591 /*
592  * Handle stack alignment exceptions.
593  */
594 asmlinkage void __exception do_sp_pc_abort(unsigned long addr,
595 					   unsigned int esr,
596 					   struct pt_regs *regs)
597 {
598 	struct siginfo info;
599 	struct task_struct *tsk = current;
600 
601 	if (show_unhandled_signals && unhandled_signal(tsk, SIGBUS))
602 		pr_info_ratelimited("%s[%d]: %s exception: pc=%p sp=%p\n",
603 				    tsk->comm, task_pid_nr(tsk),
604 				    esr_get_class_string(esr), (void *)regs->pc,
605 				    (void *)regs->sp);
606 
607 	info.si_signo = SIGBUS;
608 	info.si_errno = 0;
609 	info.si_code  = BUS_ADRALN;
610 	info.si_addr  = (void __user *)addr;
611 	arm64_notify_die("Oops - SP/PC alignment exception", regs, &info, esr);
612 }
613 
614 int __init early_brk64(unsigned long addr, unsigned int esr,
615 		       struct pt_regs *regs);
616 
617 /*
618  * __refdata because early_brk64 is __init, but the reference to it is
619  * clobbered at arch_initcall time.
620  * See traps.c and debug-monitors.c:debug_traps_init().
621  */
622 static struct fault_info __refdata debug_fault_info[] = {
623 	{ do_bad,	SIGTRAP,	TRAP_HWBKPT,	"hardware breakpoint"	},
624 	{ do_bad,	SIGTRAP,	TRAP_HWBKPT,	"hardware single-step"	},
625 	{ do_bad,	SIGTRAP,	TRAP_HWBKPT,	"hardware watchpoint"	},
626 	{ do_bad,	SIGBUS,		0,		"unknown 3"		},
627 	{ do_bad,	SIGTRAP,	TRAP_BRKPT,	"aarch32 BKPT"		},
628 	{ do_bad,	SIGTRAP,	0,		"aarch32 vector catch"	},
629 	{ early_brk64,	SIGTRAP,	TRAP_BRKPT,	"aarch64 BRK"		},
630 	{ do_bad,	SIGBUS,		0,		"unknown 7"		},
631 };
632 
633 void __init hook_debug_fault_code(int nr,
634 				  int (*fn)(unsigned long, unsigned int, struct pt_regs *),
635 				  int sig, int code, const char *name)
636 {
637 	BUG_ON(nr < 0 || nr >= ARRAY_SIZE(debug_fault_info));
638 
639 	debug_fault_info[nr].fn		= fn;
640 	debug_fault_info[nr].sig	= sig;
641 	debug_fault_info[nr].code	= code;
642 	debug_fault_info[nr].name	= name;
643 }
644 
645 asmlinkage int __exception do_debug_exception(unsigned long addr,
646 					      unsigned int esr,
647 					      struct pt_regs *regs)
648 {
649 	const struct fault_info *inf = debug_fault_info + DBG_ESR_EVT(esr);
650 	struct siginfo info;
651 	int rv;
652 
653 	/*
654 	 * Tell lockdep we disabled irqs in entry.S. Do nothing if they were
655 	 * already disabled to preserve the last enabled/disabled addresses.
656 	 */
657 	if (interrupts_enabled(regs))
658 		trace_hardirqs_off();
659 
660 	if (!inf->fn(addr, esr, regs)) {
661 		rv = 1;
662 	} else {
663 		pr_alert("Unhandled debug exception: %s (0x%08x) at 0x%016lx\n",
664 			 inf->name, esr, addr);
665 
666 		info.si_signo = inf->sig;
667 		info.si_errno = 0;
668 		info.si_code  = inf->code;
669 		info.si_addr  = (void __user *)addr;
670 		arm64_notify_die("", regs, &info, 0);
671 		rv = 0;
672 	}
673 
674 	if (interrupts_enabled(regs))
675 		trace_hardirqs_on();
676 
677 	return rv;
678 }
679 NOKPROBE_SYMBOL(do_debug_exception);
680 
681 #ifdef CONFIG_ARM64_PAN
682 int cpu_enable_pan(void *__unused)
683 {
684 	/*
685 	 * We modify PSTATE. This won't work from irq context as the PSTATE
686 	 * is discarded once we return from the exception.
687 	 */
688 	WARN_ON_ONCE(in_interrupt());
689 
690 	config_sctlr_el1(SCTLR_EL1_SPAN, 0);
691 	asm(SET_PSTATE_PAN(1));
692 	return 0;
693 }
694 #endif /* CONFIG_ARM64_PAN */
695