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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.h>
30 #include <linux/highmem.h>
31 #include <linux/perf_event.h>
32 #include <linux/preempt.h>
33 
34 #include <asm/bug.h>
35 #include <asm/cpufeature.h>
36 #include <asm/exception.h>
37 #include <asm/debug-monitors.h>
38 #include <asm/esr.h>
39 #include <asm/sysreg.h>
40 #include <asm/system_misc.h>
41 #include <asm/pgtable.h>
42 #include <asm/tlbflush.h>
43 
44 struct fault_info {
45 	int	(*fn)(unsigned long addr, unsigned int esr,
46 		      struct pt_regs *regs);
47 	int	sig;
48 	int	code;
49 	const char *name;
50 };
51 
52 static const struct fault_info fault_info[];
53 
esr_to_fault_info(unsigned int esr)54 static inline const struct fault_info *esr_to_fault_info(unsigned int esr)
55 {
56 	return fault_info + (esr & 63);
57 }
58 
59 #ifdef CONFIG_KPROBES
notify_page_fault(struct pt_regs * regs,unsigned int esr)60 static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr)
61 {
62 	int ret = 0;
63 
64 	/* kprobe_running() needs smp_processor_id() */
65 	if (!user_mode(regs)) {
66 		preempt_disable();
67 		if (kprobe_running() && kprobe_fault_handler(regs, esr))
68 			ret = 1;
69 		preempt_enable();
70 	}
71 
72 	return ret;
73 }
74 #else
notify_page_fault(struct pt_regs * regs,unsigned int esr)75 static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr)
76 {
77 	return 0;
78 }
79 #endif
80 
81 /*
82  * Dump out the page tables associated with 'addr' in mm 'mm'.
83  */
show_pte(struct mm_struct * mm,unsigned long addr)84 void show_pte(struct mm_struct *mm, unsigned long addr)
85 {
86 	pgd_t *pgd;
87 
88 	if (!mm)
89 		mm = &init_mm;
90 
91 	pr_alert("pgd = %p\n", mm->pgd);
92 	pgd = pgd_offset(mm, addr);
93 	pr_alert("[%08lx] *pgd=%016llx", addr, pgd_val(*pgd));
94 
95 	do {
96 		pud_t *pud;
97 		pmd_t *pmd;
98 		pte_t *pte;
99 
100 		if (pgd_none(*pgd) || pgd_bad(*pgd))
101 			break;
102 
103 		pud = pud_offset(pgd, addr);
104 		pr_cont(", *pud=%016llx", pud_val(*pud));
105 		if (pud_none(*pud) || pud_bad(*pud))
106 			break;
107 
108 		pmd = pmd_offset(pud, addr);
109 		pr_cont(", *pmd=%016llx", pmd_val(*pmd));
110 		if (pmd_none(*pmd) || pmd_bad(*pmd))
111 			break;
112 
113 		pte = pte_offset_map(pmd, addr);
114 		pr_cont(", *pte=%016llx", pte_val(*pte));
115 		pte_unmap(pte);
116 	} while(0);
117 
118 	pr_cont("\n");
119 }
120 
121 #ifdef CONFIG_ARM64_HW_AFDBM
122 /*
123  * This function sets the access flags (dirty, accessed), as well as write
124  * permission, and only to a more permissive setting.
125  *
126  * It needs to cope with hardware update of the accessed/dirty state by other
127  * agents in the system and can safely skip the __sync_icache_dcache() call as,
128  * like set_pte_at(), the PTE is never changed from no-exec to exec here.
129  *
130  * Returns whether or not the PTE actually changed.
131  */
ptep_set_access_flags(struct vm_area_struct * vma,unsigned long address,pte_t * ptep,pte_t entry,int dirty)132 int ptep_set_access_flags(struct vm_area_struct *vma,
133 			  unsigned long address, pte_t *ptep,
134 			  pte_t entry, int dirty)
135 {
136 	pteval_t old_pteval;
137 	unsigned int tmp;
138 
139 	if (pte_same(*ptep, entry))
140 		return 0;
141 
142 	/* only preserve the access flags and write permission */
143 	pte_val(entry) &= PTE_AF | PTE_WRITE | PTE_DIRTY;
144 
145 	/*
146 	 * PTE_RDONLY is cleared by default in the asm below, so set it in
147 	 * back if necessary (read-only or clean PTE).
148 	 */
149 	if (!pte_write(entry) || !pte_sw_dirty(entry))
150 		pte_val(entry) |= PTE_RDONLY;
151 
152 	/*
153 	 * Setting the flags must be done atomically to avoid racing with the
154 	 * hardware update of the access/dirty state.
155 	 */
156 	asm volatile("//	ptep_set_access_flags\n"
157 	"	prfm	pstl1strm, %2\n"
158 	"1:	ldxr	%0, %2\n"
159 	"	and	%0, %0, %3		// clear PTE_RDONLY\n"
160 	"	orr	%0, %0, %4		// set flags\n"
161 	"	stxr	%w1, %0, %2\n"
162 	"	cbnz	%w1, 1b\n"
163 	: "=&r" (old_pteval), "=&r" (tmp), "+Q" (pte_val(*ptep))
164 	: "L" (~PTE_RDONLY), "r" (pte_val(entry)));
165 
166 	flush_tlb_fix_spurious_fault(vma, address);
167 	return 1;
168 }
169 #endif
170 
is_el1_instruction_abort(unsigned int esr)171 static bool is_el1_instruction_abort(unsigned int esr)
172 {
173 	return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_CUR;
174 }
175 
176 /*
177  * The kernel tried to access some page that wasn't present.
178  */
__do_kernel_fault(struct mm_struct * mm,unsigned long addr,unsigned int esr,struct pt_regs * regs)179 static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr,
180 			      unsigned int esr, struct pt_regs *regs)
181 {
182 	/*
183 	 * Are we prepared to handle this kernel fault?
184 	 * We are almost certainly not prepared to handle instruction faults.
185 	 */
186 	if (!is_el1_instruction_abort(esr) && fixup_exception(regs))
187 		return;
188 
189 	/*
190 	 * No handler, we'll have to terminate things with extreme prejudice.
191 	 */
192 	bust_spinlocks(1);
193 	pr_alert("Unable to handle kernel %s at virtual address %08lx\n",
194 		 (addr < PAGE_SIZE) ? "NULL pointer dereference" :
195 		 "paging request", addr);
196 
197 	show_pte(mm, addr);
198 	die("Oops", regs, esr);
199 	bust_spinlocks(0);
200 	do_exit(SIGKILL);
201 }
202 
203 /*
204  * Something tried to access memory that isn't in our memory map. User mode
205  * accesses just cause a SIGSEGV
206  */
__do_user_fault(struct task_struct * tsk,unsigned long addr,unsigned int esr,unsigned int sig,int code,struct pt_regs * regs)207 static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
208 			    unsigned int esr, unsigned int sig, int code,
209 			    struct pt_regs *regs)
210 {
211 	struct siginfo si;
212 	const struct fault_info *inf;
213 
214 	if (unhandled_signal(tsk, sig) && show_unhandled_signals_ratelimited()) {
215 		inf = esr_to_fault_info(esr);
216 		pr_info("%s[%d]: unhandled %s (%d) at 0x%08lx, esr 0x%03x\n",
217 			tsk->comm, task_pid_nr(tsk), inf->name, sig,
218 			addr, esr);
219 		show_pte(tsk->mm, addr);
220 		show_regs(regs);
221 	}
222 
223 	tsk->thread.fault_address = addr;
224 	tsk->thread.fault_code = esr;
225 	si.si_signo = sig;
226 	si.si_errno = 0;
227 	si.si_code = code;
228 	si.si_addr = (void __user *)addr;
229 	force_sig_info(sig, &si, tsk);
230 }
231 
do_bad_area(unsigned long addr,unsigned int esr,struct pt_regs * regs)232 static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *regs)
233 {
234 	struct task_struct *tsk = current;
235 	struct mm_struct *mm = tsk->active_mm;
236 	const struct fault_info *inf;
237 
238 	/*
239 	 * If we are in kernel mode at this point, we have no context to
240 	 * handle this fault with.
241 	 */
242 	if (user_mode(regs)) {
243 		inf = esr_to_fault_info(esr);
244 		__do_user_fault(tsk, addr, esr, inf->sig, inf->code, regs);
245 	} else
246 		__do_kernel_fault(mm, addr, esr, regs);
247 }
248 
249 #define VM_FAULT_BADMAP		0x010000
250 #define VM_FAULT_BADACCESS	0x020000
251 
__do_page_fault(struct mm_struct * mm,unsigned long addr,unsigned int mm_flags,unsigned long vm_flags,struct task_struct * tsk)252 static int __do_page_fault(struct mm_struct *mm, unsigned long addr,
253 			   unsigned int mm_flags, unsigned long vm_flags,
254 			   struct task_struct *tsk)
255 {
256 	struct vm_area_struct *vma;
257 	int fault;
258 
259 	vma = find_vma(mm, addr);
260 	fault = VM_FAULT_BADMAP;
261 	if (unlikely(!vma))
262 		goto out;
263 	if (unlikely(vma->vm_start > addr))
264 		goto check_stack;
265 
266 	/*
267 	 * Ok, we have a good vm_area for this memory access, so we can handle
268 	 * it.
269 	 */
270 good_area:
271 	/*
272 	 * Check that the permissions on the VMA allow for the fault which
273 	 * occurred.
274 	 */
275 	if (!(vma->vm_flags & vm_flags)) {
276 		fault = VM_FAULT_BADACCESS;
277 		goto out;
278 	}
279 
280 	return handle_mm_fault(vma, addr & PAGE_MASK, mm_flags);
281 
282 check_stack:
283 	if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
284 		goto good_area;
285 out:
286 	return fault;
287 }
288 
is_permission_fault(unsigned int esr,struct pt_regs * regs)289 static inline bool is_permission_fault(unsigned int esr, struct pt_regs *regs)
290 {
291 	unsigned int ec       = ESR_ELx_EC(esr);
292 	unsigned int fsc_type = esr & ESR_ELx_FSC_TYPE;
293 
294 	if (ec != ESR_ELx_EC_DABT_CUR && ec != ESR_ELx_EC_IABT_CUR)
295 		return false;
296 
297 	if (system_uses_ttbr0_pan())
298 		return fsc_type == ESR_ELx_FSC_FAULT &&
299 			(regs->pstate & PSR_PAN_BIT);
300 	else
301 		return fsc_type == ESR_ELx_FSC_PERM;
302 }
303 
is_el0_instruction_abort(unsigned int esr)304 static bool is_el0_instruction_abort(unsigned int esr)
305 {
306 	return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_LOW;
307 }
308 
do_page_fault(unsigned long addr,unsigned int esr,struct pt_regs * regs)309 static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
310 				   struct pt_regs *regs)
311 {
312 	struct task_struct *tsk;
313 	struct mm_struct *mm;
314 	int fault, sig, code;
315 	unsigned long vm_flags = VM_READ | VM_WRITE;
316 	unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
317 
318 	if (notify_page_fault(regs, esr))
319 		return 0;
320 
321 	tsk = current;
322 	mm  = tsk->mm;
323 
324 	/*
325 	 * If we're in an interrupt or have no user context, we must not take
326 	 * the fault.
327 	 */
328 	if (faulthandler_disabled() || !mm)
329 		goto no_context;
330 
331 	if (user_mode(regs))
332 		mm_flags |= FAULT_FLAG_USER;
333 
334 	if (is_el0_instruction_abort(esr)) {
335 		vm_flags = VM_EXEC;
336 	} else if ((esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM)) {
337 		vm_flags = VM_WRITE;
338 		mm_flags |= FAULT_FLAG_WRITE;
339 	}
340 
341 	if (addr < TASK_SIZE && is_permission_fault(esr, regs)) {
342 		/* regs->orig_addr_limit may be 0 if we entered from EL0 */
343 		if (regs->orig_addr_limit == KERNEL_DS)
344 			die("Accessing user space memory with fs=KERNEL_DS", regs, esr);
345 
346 		if (is_el1_instruction_abort(esr))
347 			die("Attempting to execute userspace memory", regs, esr);
348 
349 		if (!search_exception_tables(regs->pc))
350 			die("Accessing user space memory outside uaccess.h routines", regs, esr);
351 	}
352 
353 	/*
354 	 * As per x86, we may deadlock here. However, since the kernel only
355 	 * validly references user space from well defined areas of the code,
356 	 * we can bug out early if this is from code which shouldn't.
357 	 */
358 	if (!down_read_trylock(&mm->mmap_sem)) {
359 		if (!user_mode(regs) && !search_exception_tables(regs->pc))
360 			goto no_context;
361 retry:
362 		down_read(&mm->mmap_sem);
363 	} else {
364 		/*
365 		 * The above down_read_trylock() might have succeeded in which
366 		 * case, we'll have missed the might_sleep() from down_read().
367 		 */
368 		might_sleep();
369 #ifdef CONFIG_DEBUG_VM
370 		if (!user_mode(regs) && !search_exception_tables(regs->pc))
371 			goto no_context;
372 #endif
373 	}
374 
375 	fault = __do_page_fault(mm, addr, mm_flags, vm_flags, tsk);
376 
377 	/*
378 	 * If we need to retry but a fatal signal is pending, handle the
379 	 * signal first. We do not need to release the mmap_sem because it
380 	 * would already be released in __lock_page_or_retry in mm/filemap.c.
381 	 */
382 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) {
383 		if (!user_mode(regs))
384 			goto no_context;
385 		return 0;
386 	}
387 
388 	/*
389 	 * Major/minor page fault accounting is only done on the initial
390 	 * attempt. If we go through a retry, it is extremely likely that the
391 	 * page will be found in page cache at that point.
392 	 */
393 
394 	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
395 	if (mm_flags & FAULT_FLAG_ALLOW_RETRY) {
396 		if (fault & VM_FAULT_MAJOR) {
397 			tsk->maj_flt++;
398 			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs,
399 				      addr);
400 		} else {
401 			tsk->min_flt++;
402 			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs,
403 				      addr);
404 		}
405 		if (fault & VM_FAULT_RETRY) {
406 			/*
407 			 * Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk of
408 			 * starvation.
409 			 */
410 			mm_flags &= ~FAULT_FLAG_ALLOW_RETRY;
411 			mm_flags |= FAULT_FLAG_TRIED;
412 			goto retry;
413 		}
414 	}
415 
416 	up_read(&mm->mmap_sem);
417 
418 	/*
419 	 * Handle the "normal" case first - VM_FAULT_MAJOR
420 	 */
421 	if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP |
422 			      VM_FAULT_BADACCESS))))
423 		return 0;
424 
425 	/*
426 	 * If we are in kernel mode at this point, we have no context to
427 	 * handle this fault with.
428 	 */
429 	if (!user_mode(regs))
430 		goto no_context;
431 
432 	if (fault & VM_FAULT_OOM) {
433 		/*
434 		 * We ran out of memory, call the OOM killer, and return to
435 		 * userspace (which will retry the fault, or kill us if we got
436 		 * oom-killed).
437 		 */
438 		pagefault_out_of_memory();
439 		return 0;
440 	}
441 
442 	if (fault & VM_FAULT_SIGBUS) {
443 		/*
444 		 * We had some memory, but were unable to successfully fix up
445 		 * this page fault.
446 		 */
447 		sig = SIGBUS;
448 		code = BUS_ADRERR;
449 	} else {
450 		/*
451 		 * Something tried to access memory that isn't in our memory
452 		 * map.
453 		 */
454 		sig = SIGSEGV;
455 		code = fault == VM_FAULT_BADACCESS ?
456 			SEGV_ACCERR : SEGV_MAPERR;
457 	}
458 
459 	__do_user_fault(tsk, addr, esr, sig, code, regs);
460 	return 0;
461 
462 no_context:
463 	__do_kernel_fault(mm, addr, esr, regs);
464 	return 0;
465 }
466 
467 /*
468  * First Level Translation Fault Handler
469  *
470  * We enter here because the first level page table doesn't contain a valid
471  * entry for the address.
472  *
473  * If the address is in kernel space (>= TASK_SIZE), then we are probably
474  * faulting in the vmalloc() area.
475  *
476  * If the init_task's first level page tables contains the relevant entry, we
477  * copy the it to this task.  If not, we send the process a signal, fixup the
478  * exception, or oops the kernel.
479  *
480  * NOTE! We MUST NOT take any locks for this case. We may be in an interrupt
481  * or a critical region, and should only copy the information from the master
482  * page table, nothing more.
483  */
do_translation_fault(unsigned long addr,unsigned int esr,struct pt_regs * regs)484 static int __kprobes do_translation_fault(unsigned long addr,
485 					  unsigned int esr,
486 					  struct pt_regs *regs)
487 {
488 	if (addr < TASK_SIZE)
489 		return do_page_fault(addr, esr, regs);
490 
491 	do_bad_area(addr, esr, regs);
492 	return 0;
493 }
494 
do_alignment_fault(unsigned long addr,unsigned int esr,struct pt_regs * regs)495 static int do_alignment_fault(unsigned long addr, unsigned int esr,
496 			      struct pt_regs *regs)
497 {
498 	do_bad_area(addr, esr, regs);
499 	return 0;
500 }
501 
502 /*
503  * This abort handler always returns "fault".
504  */
do_bad(unsigned long addr,unsigned int esr,struct pt_regs * regs)505 static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs)
506 {
507 	return 1;
508 }
509 
510 static const struct fault_info fault_info[] = {
511 	{ do_bad,		SIGBUS,  0,		"ttbr address size fault"	},
512 	{ do_bad,		SIGBUS,  0,		"level 1 address size fault"	},
513 	{ do_bad,		SIGBUS,  0,		"level 2 address size fault"	},
514 	{ do_bad,		SIGBUS,  0,		"level 3 address size fault"	},
515 	{ do_translation_fault,	SIGSEGV, SEGV_MAPERR,	"level 0 translation fault"	},
516 	{ do_translation_fault,	SIGSEGV, SEGV_MAPERR,	"level 1 translation fault"	},
517 	{ do_translation_fault,	SIGSEGV, SEGV_MAPERR,	"level 2 translation fault"	},
518 	{ do_translation_fault,	SIGSEGV, SEGV_MAPERR,	"level 3 translation fault"	},
519 	{ do_bad,		SIGBUS,  0,		"unknown 8"			},
520 	{ do_page_fault,	SIGSEGV, SEGV_ACCERR,	"level 1 access flag fault"	},
521 	{ do_page_fault,	SIGSEGV, SEGV_ACCERR,	"level 2 access flag fault"	},
522 	{ do_page_fault,	SIGSEGV, SEGV_ACCERR,	"level 3 access flag fault"	},
523 	{ do_bad,		SIGBUS,  0,		"unknown 12"			},
524 	{ do_page_fault,	SIGSEGV, SEGV_ACCERR,	"level 1 permission fault"	},
525 	{ do_page_fault,	SIGSEGV, SEGV_ACCERR,	"level 2 permission fault"	},
526 	{ do_page_fault,	SIGSEGV, SEGV_ACCERR,	"level 3 permission fault"	},
527 	{ do_bad,		SIGBUS,  0,		"synchronous external abort"	},
528 	{ do_bad,		SIGBUS,  0,		"unknown 17"			},
529 	{ do_bad,		SIGBUS,  0,		"unknown 18"			},
530 	{ do_bad,		SIGBUS,  0,		"unknown 19"			},
531 	{ do_bad,		SIGBUS,  0,		"synchronous abort (translation table walk)" },
532 	{ do_bad,		SIGBUS,  0,		"synchronous abort (translation table walk)" },
533 	{ do_bad,		SIGBUS,  0,		"synchronous abort (translation table walk)" },
534 	{ do_bad,		SIGBUS,  0,		"synchronous abort (translation table walk)" },
535 	{ do_bad,		SIGBUS,  0,		"synchronous parity error"	},
536 	{ do_bad,		SIGBUS,  0,		"unknown 25"			},
537 	{ do_bad,		SIGBUS,  0,		"unknown 26"			},
538 	{ do_bad,		SIGBUS,  0,		"unknown 27"			},
539 	{ do_bad,		SIGBUS,  0,		"synchronous parity error (translation table walk)" },
540 	{ do_bad,		SIGBUS,  0,		"synchronous parity error (translation table walk)" },
541 	{ do_bad,		SIGBUS,  0,		"synchronous parity error (translation table walk)" },
542 	{ do_bad,		SIGBUS,  0,		"synchronous parity error (translation table walk)" },
543 	{ do_bad,		SIGBUS,  0,		"unknown 32"			},
544 	{ do_alignment_fault,	SIGBUS,  BUS_ADRALN,	"alignment fault"		},
545 	{ do_bad,		SIGBUS,  0,		"unknown 34"			},
546 	{ do_bad,		SIGBUS,  0,		"unknown 35"			},
547 	{ do_bad,		SIGBUS,  0,		"unknown 36"			},
548 	{ do_bad,		SIGBUS,  0,		"unknown 37"			},
549 	{ do_bad,		SIGBUS,  0,		"unknown 38"			},
550 	{ do_bad,		SIGBUS,  0,		"unknown 39"			},
551 	{ do_bad,		SIGBUS,  0,		"unknown 40"			},
552 	{ do_bad,		SIGBUS,  0,		"unknown 41"			},
553 	{ do_bad,		SIGBUS,  0,		"unknown 42"			},
554 	{ do_bad,		SIGBUS,  0,		"unknown 43"			},
555 	{ do_bad,		SIGBUS,  0,		"unknown 44"			},
556 	{ do_bad,		SIGBUS,  0,		"unknown 45"			},
557 	{ do_bad,		SIGBUS,  0,		"unknown 46"			},
558 	{ do_bad,		SIGBUS,  0,		"unknown 47"			},
559 	{ do_bad,		SIGBUS,  0,		"TLB conflict abort"		},
560 	{ do_bad,		SIGBUS,  0,		"unknown 49"			},
561 	{ do_bad,		SIGBUS,  0,		"unknown 50"			},
562 	{ do_bad,		SIGBUS,  0,		"unknown 51"			},
563 	{ do_bad,		SIGBUS,  0,		"implementation fault (lockdown abort)" },
564 	{ do_bad,		SIGBUS,  0,		"implementation fault (unsupported exclusive)" },
565 	{ do_bad,		SIGBUS,  0,		"unknown 54"			},
566 	{ do_bad,		SIGBUS,  0,		"unknown 55"			},
567 	{ do_bad,		SIGBUS,  0,		"unknown 56"			},
568 	{ do_bad,		SIGBUS,  0,		"unknown 57"			},
569 	{ do_bad,		SIGBUS,  0,		"unknown 58" 			},
570 	{ do_bad,		SIGBUS,  0,		"unknown 59"			},
571 	{ do_bad,		SIGBUS,  0,		"unknown 60"			},
572 	{ do_bad,		SIGBUS,  0,		"section domain fault"		},
573 	{ do_bad,		SIGBUS,  0,		"page domain fault"		},
574 	{ do_bad,		SIGBUS,  0,		"unknown 63"			},
575 };
576 
577 /*
578  * Dispatch a data abort to the relevant handler.
579  */
do_mem_abort(unsigned long addr,unsigned int esr,struct pt_regs * regs)580 asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr,
581 					 struct pt_regs *regs)
582 {
583 	const struct fault_info *inf = esr_to_fault_info(esr);
584 	struct siginfo info;
585 
586 	if (!inf->fn(addr, esr, regs))
587 		return;
588 
589 	pr_alert("Unhandled fault: %s (0x%08x) at 0x%016lx\n",
590 		 inf->name, esr, addr);
591 
592 	info.si_signo = inf->sig;
593 	info.si_errno = 0;
594 	info.si_code  = inf->code;
595 	info.si_addr  = (void __user *)addr;
596 	arm64_notify_die("", regs, &info, esr);
597 }
598 
do_el0_irq_bp_hardening(void)599 asmlinkage void __exception do_el0_irq_bp_hardening(void)
600 {
601 	/* PC has already been checked in entry.S */
602 	arm64_apply_bp_hardening();
603 }
604 
do_el0_ia_bp_hardening(unsigned long addr,unsigned int esr,struct pt_regs * regs)605 asmlinkage void __exception do_el0_ia_bp_hardening(unsigned long addr,
606 						   unsigned int esr,
607 						   struct pt_regs *regs)
608 {
609 	/*
610 	 * We've taken an instruction abort from userspace and not yet
611 	 * re-enabled IRQs. If the address is a kernel address, apply
612 	 * BP hardening prior to enabling IRQs and pre-emption.
613 	 */
614 	if (addr > TASK_SIZE)
615 		arm64_apply_bp_hardening();
616 
617 	local_irq_enable();
618 	do_mem_abort(addr, esr, regs);
619 }
620 
621 
622 /*
623  * Handle stack alignment exceptions.
624  */
do_sp_pc_abort(unsigned long addr,unsigned int esr,struct pt_regs * regs)625 asmlinkage void __exception do_sp_pc_abort(unsigned long addr,
626 					   unsigned int esr,
627 					   struct pt_regs *regs)
628 {
629 	struct siginfo info;
630 	struct task_struct *tsk = current;
631 
632 	if (user_mode(regs)) {
633 		if (instruction_pointer(regs) > TASK_SIZE)
634 			arm64_apply_bp_hardening();
635 		local_irq_enable();
636 	}
637 
638 	if (show_unhandled_signals && unhandled_signal(tsk, SIGBUS))
639 		pr_info_ratelimited("%s[%d]: %s exception: pc=%p sp=%p\n",
640 				    tsk->comm, task_pid_nr(tsk),
641 				    esr_get_class_string(esr), (void *)regs->pc,
642 				    (void *)regs->sp);
643 
644 	info.si_signo = SIGBUS;
645 	info.si_errno = 0;
646 	info.si_code  = BUS_ADRALN;
647 	info.si_addr  = (void __user *)addr;
648 	arm64_notify_die("Oops - SP/PC alignment exception", regs, &info, esr);
649 }
650 
651 int __init early_brk64(unsigned long addr, unsigned int esr,
652 		       struct pt_regs *regs);
653 
654 /*
655  * __refdata because early_brk64 is __init, but the reference to it is
656  * clobbered at arch_initcall time.
657  * See traps.c and debug-monitors.c:debug_traps_init().
658  */
659 static struct fault_info __refdata debug_fault_info[] = {
660 	{ do_bad,	SIGTRAP,	TRAP_HWBKPT,	"hardware breakpoint"	},
661 	{ do_bad,	SIGTRAP,	TRAP_HWBKPT,	"hardware single-step"	},
662 	{ do_bad,	SIGTRAP,	TRAP_HWBKPT,	"hardware watchpoint"	},
663 	{ do_bad,	SIGBUS,		0,		"unknown 3"		},
664 	{ do_bad,	SIGTRAP,	TRAP_BRKPT,	"aarch32 BKPT"		},
665 	{ do_bad,	SIGTRAP,	0,		"aarch32 vector catch"	},
666 	{ early_brk64,	SIGTRAP,	TRAP_BRKPT,	"aarch64 BRK"		},
667 	{ do_bad,	SIGBUS,		0,		"unknown 7"		},
668 };
669 
hook_debug_fault_code(int nr,int (* fn)(unsigned long,unsigned int,struct pt_regs *),int sig,int code,const char * name)670 void __init hook_debug_fault_code(int nr,
671 				  int (*fn)(unsigned long, unsigned int, struct pt_regs *),
672 				  int sig, int code, const char *name)
673 {
674 	BUG_ON(nr < 0 || nr >= ARRAY_SIZE(debug_fault_info));
675 
676 	debug_fault_info[nr].fn		= fn;
677 	debug_fault_info[nr].sig	= sig;
678 	debug_fault_info[nr].code	= code;
679 	debug_fault_info[nr].name	= name;
680 }
681 
do_debug_exception(unsigned long addr,unsigned int esr,struct pt_regs * regs)682 asmlinkage int __exception do_debug_exception(unsigned long addr,
683 					      unsigned int esr,
684 					      struct pt_regs *regs)
685 {
686 	const struct fault_info *inf = debug_fault_info + DBG_ESR_EVT(esr);
687 	struct siginfo info;
688 	int rv;
689 
690 	/*
691 	 * Tell lockdep we disabled irqs in entry.S. Do nothing if they were
692 	 * already disabled to preserve the last enabled/disabled addresses.
693 	 */
694 	if (interrupts_enabled(regs))
695 		trace_hardirqs_off();
696 
697 	if (user_mode(regs) && instruction_pointer(regs) > TASK_SIZE)
698 		arm64_apply_bp_hardening();
699 
700 	if (!inf->fn(addr, esr, regs)) {
701 		rv = 1;
702 	} else {
703 		pr_alert("Unhandled debug exception: %s (0x%08x) at 0x%016lx\n",
704 			 inf->name, esr, addr);
705 
706 		info.si_signo = inf->sig;
707 		info.si_errno = 0;
708 		info.si_code  = inf->code;
709 		info.si_addr  = (void __user *)addr;
710 		arm64_notify_die("", regs, &info, 0);
711 		rv = 0;
712 	}
713 
714 	if (interrupts_enabled(regs))
715 		trace_hardirqs_on();
716 
717 	return rv;
718 }
719 NOKPROBE_SYMBOL(do_debug_exception);
720 
721 #ifdef CONFIG_ARM64_PAN
cpu_enable_pan(void * __unused)722 int cpu_enable_pan(void *__unused)
723 {
724 	/*
725 	 * We modify PSTATE. This won't work from irq context as the PSTATE
726 	 * is discarded once we return from the exception.
727 	 */
728 	WARN_ON_ONCE(in_interrupt());
729 
730 	config_sctlr_el1(SCTLR_EL1_SPAN, 0);
731 	asm(SET_PSTATE_PAN(1));
732 	return 0;
733 }
734 #endif /* CONFIG_ARM64_PAN */
735 
736 #ifdef CONFIG_ARM64_UAO
737 /*
738  * Kernel threads have fs=KERNEL_DS by default, and don't need to call
739  * set_fs(), devtmpfs in particular relies on this behaviour.
740  * We need to enable the feature at runtime (instead of adding it to
741  * PSR_MODE_EL1h) as the feature may not be implemented by the cpu.
742  */
cpu_enable_uao(void * __unused)743 int cpu_enable_uao(void *__unused)
744 {
745 	asm(SET_PSTATE_UAO(1));
746 	return 0;
747 }
748 #endif /* CONFIG_ARM64_UAO */
749