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blk: rq_data_dir() should not return a boolean
[cris-mirror.git] / arch / arm64 / mm / fault.c
blobaba9ead1384c036a0d6a441c92ced63cfd7ed4ae
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/module.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
33 #include <asm/cpufeature.h>
34 #include <asm/exception.h>
35 #include <asm/debug-monitors.h>
36 #include <asm/esr.h>
37 #include <asm/sysreg.h>
38 #include <asm/system_misc.h>
39 #include <asm/pgtable.h>
40 #include <asm/tlbflush.h>
41
42 static const char *fault_name(unsigned int esr);
43
44 /*
45 * Dump out the page tables associated with 'addr' in mm 'mm'.
46 */
47 void show_pte(struct mm_struct *mm, unsigned long addr)
48 {
49 pgd_t *pgd;
50
51 if (!mm)
52 mm = &init_mm;
53
54 pr_alert("pgd = %p\n", mm->pgd);
55 pgd = pgd_offset(mm, addr);
56 pr_alert("[%08lx] *pgd=%016llx", addr, pgd_val(*pgd));
57
58 do {
59 pud_t *pud;
60 pmd_t *pmd;
61 pte_t *pte;
62
63 if (pgd_none(*pgd) || pgd_bad(*pgd))
64 break;
65
66 pud = pud_offset(pgd, addr);
67 printk(", *pud=%016llx", pud_val(*pud));
68 if (pud_none(*pud) || pud_bad(*pud))
69 break;
70
71 pmd = pmd_offset(pud, addr);
72 printk(", *pmd=%016llx", pmd_val(*pmd));
73 if (pmd_none(*pmd) || pmd_bad(*pmd))
74 break;
75
76 pte = pte_offset_map(pmd, addr);
77 printk(", *pte=%016llx", pte_val(*pte));
78 pte_unmap(pte);
79 } while(0);
80
81 printk("\n");
82 }
83
84 /*
85 * The kernel tried to access some page that wasn't present.
86 */
87 static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr,
88 unsigned int esr, struct pt_regs *regs)
89 {
90 /*
91 * Are we prepared to handle this kernel fault?
92 */
93 if (fixup_exception(regs))
94 return;
95
96 /*
97 * No handler, we'll have to terminate things with extreme prejudice.
98 */
99 bust_spinlocks(1);
100 pr_alert("Unable to handle kernel %s at virtual address %08lx\n",
101 (addr < PAGE_SIZE) ? "NULL pointer dereference" :
102 "paging request", addr);
103
104 show_pte(mm, addr);
105 die("Oops", regs, esr);
106 bust_spinlocks(0);
107 do_exit(SIGKILL);
108 }
109
110 /*
111 * Something tried to access memory that isn't in our memory map. User mode
112 * accesses just cause a SIGSEGV
113 */
114 static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
115 unsigned int esr, unsigned int sig, int code,
116 struct pt_regs *regs)
117 {
118 struct siginfo si;
119
120 if (unhandled_signal(tsk, sig) && show_unhandled_signals_ratelimited()) {
121 pr_info("%s[%d]: unhandled %s (%d) at 0x%08lx, esr 0x%03x\n",
122 tsk->comm, task_pid_nr(tsk), fault_name(esr), sig,
123 addr, esr);
124 show_pte(tsk->mm, addr);
125 show_regs(regs);
126 }
127
128 tsk->thread.fault_address = addr;
129 tsk->thread.fault_code = esr;
130 si.si_signo = sig;
131 si.si_errno = 0;
132 si.si_code = code;
133 si.si_addr = (void __user *)addr;
134 force_sig_info(sig, &si, tsk);
135 }
136
137 static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *regs)
138 {
139 struct task_struct *tsk = current;
140 struct mm_struct *mm = tsk->active_mm;
141
142 /*
143 * If we are in kernel mode at this point, we have no context to
144 * handle this fault with.
145 */
146 if (user_mode(regs))
147 __do_user_fault(tsk, addr, esr, SIGSEGV, SEGV_MAPERR, regs);
148 else
149 __do_kernel_fault(mm, addr, esr, regs);
150 }
151
152 #define VM_FAULT_BADMAP 0x010000
153 #define VM_FAULT_BADACCESS 0x020000
154
155 #define ESR_LNX_EXEC (1 << 24)
156
157 static int __do_page_fault(struct mm_struct *mm, unsigned long addr,
158 unsigned int mm_flags, unsigned long vm_flags,
159 struct task_struct *tsk)
160 {
161 struct vm_area_struct *vma;
162 int fault;
163
164 vma = find_vma(mm, addr);
165 fault = VM_FAULT_BADMAP;
166 if (unlikely(!vma))
167 goto out;
168 if (unlikely(vma->vm_start > addr))
169 goto check_stack;
170
171 /*
172 * Ok, we have a good vm_area for this memory access, so we can handle
173 * it.
174 */
175 good_area:
176 /*
177 * Check that the permissions on the VMA allow for the fault which
178 * occurred. If we encountered a write or exec fault, we must have
179 * appropriate permissions, otherwise we allow any permission.
180 */
181 if (!(vma->vm_flags & vm_flags)) {
182 fault = VM_FAULT_BADACCESS;
183 goto out;
184 }
185
186 return handle_mm_fault(mm, vma, addr & PAGE_MASK, mm_flags);
187
188 check_stack:
189 if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
190 goto good_area;
191 out:
192 return fault;
193 }
194
195 static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
196 struct pt_regs *regs)
197 {
198 struct task_struct *tsk;
199 struct mm_struct *mm;
200 int fault, sig, code;
201 unsigned long vm_flags = VM_READ | VM_WRITE | VM_EXEC;
202 unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
203
204 tsk = current;
205 mm = tsk->mm;
206
207 /* Enable interrupts if they were enabled in the parent context. */
208 if (interrupts_enabled(regs))
209 local_irq_enable();
210
211 /*
212 * If we're in an interrupt or have no user context, we must not take
213 * the fault.
214 */
215 if (faulthandler_disabled() || !mm)
216 goto no_context;
217
218 if (user_mode(regs))
219 mm_flags |= FAULT_FLAG_USER;
220
221 if (esr & ESR_LNX_EXEC) {
222 vm_flags = VM_EXEC;
223 } else if ((esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM)) {
224 vm_flags = VM_WRITE;
225 mm_flags |= FAULT_FLAG_WRITE;
226 }
227
228 /*
229 * PAN bit set implies the fault happened in kernel space, but not
230 * in the arch's user access functions.
231 */
232 if (IS_ENABLED(CONFIG_ARM64_PAN) && (regs->pstate & PSR_PAN_BIT))
233 goto no_context;
234
235 /*
236 * As per x86, we may deadlock here. However, since the kernel only
237 * validly references user space from well defined areas of the code,
238 * we can bug out early if this is from code which shouldn't.
239 */
240 if (!down_read_trylock(&mm->mmap_sem)) {
241 if (!user_mode(regs) && !search_exception_tables(regs->pc))
242 goto no_context;
243 retry:
244 down_read(&mm->mmap_sem);
245 } else {
246 /*
247 * The above down_read_trylock() might have succeeded in which
248 * case, we'll have missed the might_sleep() from down_read().
249 */
250 might_sleep();
251 #ifdef CONFIG_DEBUG_VM
252 if (!user_mode(regs) && !search_exception_tables(regs->pc))
253 goto no_context;
254 #endif
255 }
256
257 fault = __do_page_fault(mm, addr, mm_flags, vm_flags, tsk);
258
259 /*
260 * If we need to retry but a fatal signal is pending, handle the
261 * signal first. We do not need to release the mmap_sem because it
262 * would already be released in __lock_page_or_retry in mm/filemap.c.
263 */
264 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
265 return 0;
266
267 /*
268 * Major/minor page fault accounting is only done on the initial
269 * attempt. If we go through a retry, it is extremely likely that the
270 * page will be found in page cache at that point.
271 */
272
273 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
274 if (mm_flags & FAULT_FLAG_ALLOW_RETRY) {
275 if (fault & VM_FAULT_MAJOR) {
276 tsk->maj_flt++;
277 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs,
278 addr);
279 } else {
280 tsk->min_flt++;
281 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs,
282 addr);
283 }
284 if (fault & VM_FAULT_RETRY) {
285 /*
286 * Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk of
287 * starvation.
288 */
289 mm_flags &= ~FAULT_FLAG_ALLOW_RETRY;
290 goto retry;
291 }
292 }
293
294 up_read(&mm->mmap_sem);
295
296 /*
297 * Handle the "normal" case first - VM_FAULT_MAJOR / VM_FAULT_MINOR
298 */
299 if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP |
300 VM_FAULT_BADACCESS))))
301 return 0;
302
303 /*
304 * If we are in kernel mode at this point, we have no context to
305 * handle this fault with.
306 */
307 if (!user_mode(regs))
308 goto no_context;
309
310 if (fault & VM_FAULT_OOM) {
311 /*
312 * We ran out of memory, call the OOM killer, and return to
313 * userspace (which will retry the fault, or kill us if we got
314 * oom-killed).
315 */
316 pagefault_out_of_memory();
317 return 0;
318 }
319
320 if (fault & VM_FAULT_SIGBUS) {
321 /*
322 * We had some memory, but were unable to successfully fix up
323 * this page fault.
324 */
325 sig = SIGBUS;
326 code = BUS_ADRERR;
327 } else {
328 /*
329 * Something tried to access memory that isn't in our memory
330 * map.
331 */
332 sig = SIGSEGV;
333 code = fault == VM_FAULT_BADACCESS ?
334 SEGV_ACCERR : SEGV_MAPERR;
335 }
336
337 __do_user_fault(tsk, addr, esr, sig, code, regs);
338 return 0;
339
340 no_context:
341 __do_kernel_fault(mm, addr, esr, regs);
342 return 0;
343 }
344
345 /*
346 * First Level Translation Fault Handler
347 *
348 * We enter here because the first level page table doesn't contain a valid
349 * entry for the address.
350 *
351 * If the address is in kernel space (>= TASK_SIZE), then we are probably
352 * faulting in the vmalloc() area.
353 *
354 * If the init_task's first level page tables contains the relevant entry, we
355 * copy the it to this task. If not, we send the process a signal, fixup the
356 * exception, or oops the kernel.
357 *
358 * NOTE! We MUST NOT take any locks for this case. We may be in an interrupt
359 * or a critical region, and should only copy the information from the master
360 * page table, nothing more.
361 */
362 static int __kprobes do_translation_fault(unsigned long addr,
363 unsigned int esr,
364 struct pt_regs *regs)
365 {
366 if (addr < TASK_SIZE)
367 return do_page_fault(addr, esr, regs);
368
369 do_bad_area(addr, esr, regs);
370 return 0;
371 }
372
373 /*
374 * This abort handler always returns "fault".
375 */
376 static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs)
377 {
378 return 1;
379 }
380
381 static struct fault_info {
382 int (*fn)(unsigned long addr, unsigned int esr, struct pt_regs *regs);
383 int sig;
384 int code;
385 const char *name;
386 } fault_info[] = {
387 { do_bad, SIGBUS, 0, "ttbr address size fault" },
388 { do_bad, SIGBUS, 0, "level 1 address size fault" },
389 { do_bad, SIGBUS, 0, "level 2 address size fault" },
390 { do_bad, SIGBUS, 0, "level 3 address size fault" },
391 { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 0 translation fault" },
392 { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 1 translation fault" },
393 { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 2 translation fault" },
394 { do_page_fault, SIGSEGV, SEGV_MAPERR, "level 3 translation fault" },
395 { do_bad, SIGBUS, 0, "reserved access flag fault" },
396 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 1 access flag fault" },
397 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 2 access flag fault" },
398 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 3 access flag fault" },
399 { do_bad, SIGBUS, 0, "reserved permission fault" },
400 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 1 permission fault" },
401 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 2 permission fault" },
402 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 3 permission fault" },
403 { do_bad, SIGBUS, 0, "synchronous external abort" },
404 { do_bad, SIGBUS, 0, "asynchronous external abort" },
405 { do_bad, SIGBUS, 0, "unknown 18" },
406 { do_bad, SIGBUS, 0, "unknown 19" },
407 { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" },
408 { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" },
409 { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" },
410 { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" },
411 { do_bad, SIGBUS, 0, "synchronous parity error" },
412 { do_bad, SIGBUS, 0, "asynchronous parity error" },
413 { do_bad, SIGBUS, 0, "unknown 26" },
414 { do_bad, SIGBUS, 0, "unknown 27" },
415 { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk" },
416 { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk" },
417 { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk" },
418 { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk" },
419 { do_bad, SIGBUS, 0, "unknown 32" },
420 { do_bad, SIGBUS, BUS_ADRALN, "alignment fault" },
421 { do_bad, SIGBUS, 0, "debug event" },
422 { do_bad, SIGBUS, 0, "unknown 35" },
423 { do_bad, SIGBUS, 0, "unknown 36" },
424 { do_bad, SIGBUS, 0, "unknown 37" },
425 { do_bad, SIGBUS, 0, "unknown 38" },
426 { do_bad, SIGBUS, 0, "unknown 39" },
427 { do_bad, SIGBUS, 0, "unknown 40" },
428 { do_bad, SIGBUS, 0, "unknown 41" },
429 { do_bad, SIGBUS, 0, "unknown 42" },
430 { do_bad, SIGBUS, 0, "unknown 43" },
431 { do_bad, SIGBUS, 0, "unknown 44" },
432 { do_bad, SIGBUS, 0, "unknown 45" },
433 { do_bad, SIGBUS, 0, "unknown 46" },
434 { do_bad, SIGBUS, 0, "unknown 47" },
435 { do_bad, SIGBUS, 0, "unknown 48" },
436 { do_bad, SIGBUS, 0, "unknown 49" },
437 { do_bad, SIGBUS, 0, "unknown 50" },
438 { do_bad, SIGBUS, 0, "unknown 51" },
439 { do_bad, SIGBUS, 0, "implementation fault (lockdown abort)" },
440 { do_bad, SIGBUS, 0, "unknown 53" },
441 { do_bad, SIGBUS, 0, "unknown 54" },
442 { do_bad, SIGBUS, 0, "unknown 55" },
443 { do_bad, SIGBUS, 0, "unknown 56" },
444 { do_bad, SIGBUS, 0, "unknown 57" },
445 { do_bad, SIGBUS, 0, "implementation fault (coprocessor abort)" },
446 { do_bad, SIGBUS, 0, "unknown 59" },
447 { do_bad, SIGBUS, 0, "unknown 60" },
448 { do_bad, SIGBUS, 0, "unknown 61" },
449 { do_bad, SIGBUS, 0, "unknown 62" },
450 { do_bad, SIGBUS, 0, "unknown 63" },
451 };
452
453 static const char *fault_name(unsigned int esr)
454 {
455 const struct fault_info *inf = fault_info + (esr & 63);
456 return inf->name;
457 }
458
459 /*
460 * Dispatch a data abort to the relevant handler.
461 */
462 asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr,
463 struct pt_regs *regs)
464 {
465 const struct fault_info *inf = fault_info + (esr & 63);
466 struct siginfo info;
467
468 if (!inf->fn(addr, esr, regs))
469 return;
470
471 pr_alert("Unhandled fault: %s (0x%08x) at 0x%016lx\n",
472 inf->name, esr, addr);
473
474 info.si_signo = inf->sig;
475 info.si_errno = 0;
476 info.si_code = inf->code;
477 info.si_addr = (void __user *)addr;
478 arm64_notify_die("", regs, &info, esr);
479 }
480
481 /*
482 * Handle stack alignment exceptions.
483 */
484 asmlinkage void __exception do_sp_pc_abort(unsigned long addr,
485 unsigned int esr,
486 struct pt_regs *regs)
487 {
488 struct siginfo info;
489 struct task_struct *tsk = current;
490
491 if (show_unhandled_signals && unhandled_signal(tsk, SIGBUS))
492 pr_info_ratelimited("%s[%d]: %s exception: pc=%p sp=%p\n",
493 tsk->comm, task_pid_nr(tsk),
494 esr_get_class_string(esr), (void *)regs->pc,
495 (void *)regs->sp);
496
497 info.si_signo = SIGBUS;
498 info.si_errno = 0;
499 info.si_code = BUS_ADRALN;
500 info.si_addr = (void __user *)addr;
501 arm64_notify_die("Oops - SP/PC alignment exception", regs, &info, esr);
502 }
503
504 int __init early_brk64(unsigned long addr, unsigned int esr,
505 struct pt_regs *regs);
506
507 /*
508 * __refdata because early_brk64 is __init, but the reference to it is
509 * clobbered at arch_initcall time.
510 * See traps.c and debug-monitors.c:debug_traps_init().
511 */
512 static struct fault_info __refdata debug_fault_info[] = {
513 { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware breakpoint" },
514 { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware single-step" },
515 { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware watchpoint" },
516 { do_bad, SIGBUS, 0, "unknown 3" },
517 { do_bad, SIGTRAP, TRAP_BRKPT, "aarch32 BKPT" },
518 { do_bad, SIGTRAP, 0, "aarch32 vector catch" },
519 { early_brk64, SIGTRAP, TRAP_BRKPT, "aarch64 BRK" },
520 { do_bad, SIGBUS, 0, "unknown 7" },
521 };
522
523 void __init hook_debug_fault_code(int nr,
524 int (*fn)(unsigned long, unsigned int, struct pt_regs *),
525 int sig, int code, const char *name)
526 {
527 BUG_ON(nr < 0 || nr >= ARRAY_SIZE(debug_fault_info));
528
529 debug_fault_info[nr].fn = fn;
530 debug_fault_info[nr].sig = sig;
531 debug_fault_info[nr].code = code;
532 debug_fault_info[nr].name = name;
533 }
534
535 asmlinkage int __exception do_debug_exception(unsigned long addr,
536 unsigned int esr,
537 struct pt_regs *regs)
538 {
539 const struct fault_info *inf = debug_fault_info + DBG_ESR_EVT(esr);
540 struct siginfo info;
541
542 if (!inf->fn(addr, esr, regs))
543 return 1;
544
545 pr_alert("Unhandled debug exception: %s (0x%08x) at 0x%016lx\n",
546 inf->name, esr, addr);
547
548 info.si_signo = inf->sig;
549 info.si_errno = 0;
550 info.si_code = inf->code;
551 info.si_addr = (void __user *)addr;
552 arm64_notify_die("", regs, &info, 0);
553
554 return 0;
555 }
556
557 #ifdef CONFIG_ARM64_PAN
558 void cpu_enable_pan(void)
559 {
560 config_sctlr_el1(SCTLR_EL1_SPAN, 0);
561 }
562 #endif /* CONFIG_ARM64_PAN */
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