?  search:
summary | log | graphiclog1 | graphiclog2 | commit | commitdiff | tree | refs | edit | fork
blame | history | raw | HEAD
Staging: Panel: panel: Fixed checkpatch line length warnings
[linux/fpc-iii.git] / arch / arm64 / mm / fault.c
blob98af6e760cce6781a5b117d786bcd16fc136a0b1
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/exception.h>
34 #include <asm/debug-monitors.h>
35 #include <asm/system_misc.h>
36 #include <asm/pgtable.h>
37 #include <asm/tlbflush.h>
38
39 static const char *fault_name(unsigned int esr);
40
41 /*
42 * Dump out the page tables associated with 'addr' in mm 'mm'.
43 */
44 void show_pte(struct mm_struct *mm, unsigned long addr)
45 {
46 pgd_t *pgd;
47
48 if (!mm)
49 mm = &init_mm;
50
51 pr_alert("pgd = %p\n", mm->pgd);
52 pgd = pgd_offset(mm, addr);
53 pr_alert("[%08lx] *pgd=%016llx", addr, pgd_val(*pgd));
54
55 do {
56 pud_t *pud;
57 pmd_t *pmd;
58 pte_t *pte;
59
60 if (pgd_none(*pgd) || pgd_bad(*pgd))
61 break;
62
63 pud = pud_offset(pgd, addr);
64 if (pud_none(*pud) || pud_bad(*pud))
65 break;
66
67 pmd = pmd_offset(pud, addr);
68 printk(", *pmd=%016llx", pmd_val(*pmd));
69 if (pmd_none(*pmd) || pmd_bad(*pmd))
70 break;
71
72 pte = pte_offset_map(pmd, addr);
73 printk(", *pte=%016llx", pte_val(*pte));
74 pte_unmap(pte);
75 } while(0);
76
77 printk("\n");
78 }
79
80 /*
81 * The kernel tried to access some page that wasn't present.
82 */
83 static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr,
84 unsigned int esr, struct pt_regs *regs)
85 {
86 /*
87 * Are we prepared to handle this kernel fault?
88 */
89 if (fixup_exception(regs))
90 return;
91
92 /*
93 * No handler, we'll have to terminate things with extreme prejudice.
94 */
95 bust_spinlocks(1);
96 pr_alert("Unable to handle kernel %s at virtual address %08lx\n",
97 (addr < PAGE_SIZE) ? "NULL pointer dereference" :
98 "paging request", addr);
99
100 show_pte(mm, addr);
101 die("Oops", regs, esr);
102 bust_spinlocks(0);
103 do_exit(SIGKILL);
104 }
105
106 /*
107 * Something tried to access memory that isn't in our memory map. User mode
108 * accesses just cause a SIGSEGV
109 */
110 static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
111 unsigned int esr, unsigned int sig, int code,
112 struct pt_regs *regs)
113 {
114 struct siginfo si;
115
116 if (show_unhandled_signals) {
117 pr_info("%s[%d]: unhandled %s (%d) at 0x%08lx, esr 0x%03x\n",
118 tsk->comm, task_pid_nr(tsk), fault_name(esr), sig,
119 addr, esr);
120 show_pte(tsk->mm, addr);
121 show_regs(regs);
122 }
123
124 tsk->thread.fault_address = addr;
125 si.si_signo = sig;
126 si.si_errno = 0;
127 si.si_code = code;
128 si.si_addr = (void __user *)addr;
129 force_sig_info(sig, &si, tsk);
130 }
131
132 void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *regs)
133 {
134 struct task_struct *tsk = current;
135 struct mm_struct *mm = tsk->active_mm;
136
137 /*
138 * If we are in kernel mode at this point, we have no context to
139 * handle this fault with.
140 */
141 if (user_mode(regs))
142 __do_user_fault(tsk, addr, esr, SIGSEGV, SEGV_MAPERR, regs);
143 else
144 __do_kernel_fault(mm, addr, esr, regs);
145 }
146
147 #define VM_FAULT_BADMAP 0x010000
148 #define VM_FAULT_BADACCESS 0x020000
149
150 #define ESR_WRITE (1 << 6)
151 #define ESR_CM (1 << 8)
152 #define ESR_LNX_EXEC (1 << 24)
153
154 /*
155 * Check that the permissions on the VMA allow for the fault which occurred.
156 * If we encountered a write fault, we must have write permission, otherwise
157 * we allow any permission.
158 */
159 static inline bool access_error(unsigned int esr, struct vm_area_struct *vma)
160 {
161 unsigned int mask = VM_READ | VM_WRITE | VM_EXEC;
162
163 if (esr & ESR_WRITE)
164 mask = VM_WRITE;
165 if (esr & ESR_LNX_EXEC)
166 mask = VM_EXEC;
167
168 return vma->vm_flags & mask ? false : true;
169 }
170
171 static int __do_page_fault(struct mm_struct *mm, unsigned long addr,
172 unsigned int esr, unsigned int flags,
173 struct task_struct *tsk)
174 {
175 struct vm_area_struct *vma;
176 int fault;
177
178 vma = find_vma(mm, addr);
179 fault = VM_FAULT_BADMAP;
180 if (unlikely(!vma))
181 goto out;
182 if (unlikely(vma->vm_start > addr))
183 goto check_stack;
184
185 /*
186 * Ok, we have a good vm_area for this memory access, so we can handle
187 * it.
188 */
189 good_area:
190 if (access_error(esr, vma)) {
191 fault = VM_FAULT_BADACCESS;
192 goto out;
193 }
194
195 return handle_mm_fault(mm, vma, addr & PAGE_MASK, flags);
196
197 check_stack:
198 if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
199 goto good_area;
200 out:
201 return fault;
202 }
203
204 static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
205 struct pt_regs *regs)
206 {
207 struct task_struct *tsk;
208 struct mm_struct *mm;
209 int fault, sig, code;
210 bool write = (esr & ESR_WRITE) && !(esr & ESR_CM);
211 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
212 (write ? FAULT_FLAG_WRITE : 0);
213
214 tsk = current;
215 mm = tsk->mm;
216
217 /* Enable interrupts if they were enabled in the parent context. */
218 if (interrupts_enabled(regs))
219 local_irq_enable();
220
221 /*
222 * If we're in an interrupt or have no user context, we must not take
223 * the fault.
224 */
225 if (in_atomic() || !mm)
226 goto no_context;
227
228 /*
229 * As per x86, we may deadlock here. However, since the kernel only
230 * validly references user space from well defined areas of the code,
231 * we can bug out early if this is from code which shouldn't.
232 */
233 if (!down_read_trylock(&mm->mmap_sem)) {
234 if (!user_mode(regs) && !search_exception_tables(regs->pc))
235 goto no_context;
236 retry:
237 down_read(&mm->mmap_sem);
238 } else {
239 /*
240 * The above down_read_trylock() might have succeeded in which
241 * case, we'll have missed the might_sleep() from down_read().
242 */
243 might_sleep();
244 #ifdef CONFIG_DEBUG_VM
245 if (!user_mode(regs) && !search_exception_tables(regs->pc))
246 goto no_context;
247 #endif
248 }
249
250 fault = __do_page_fault(mm, addr, esr, flags, tsk);
251
252 /*
253 * If we need to retry but a fatal signal is pending, handle the
254 * signal first. We do not need to release the mmap_sem because it
255 * would already be released in __lock_page_or_retry in mm/filemap.c.
256 */
257 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
258 return 0;
259
260 /*
261 * Major/minor page fault accounting is only done on the initial
262 * attempt. If we go through a retry, it is extremely likely that the
263 * page will be found in page cache at that point.
264 */
265
266 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
267 if (flags & FAULT_FLAG_ALLOW_RETRY) {
268 if (fault & VM_FAULT_MAJOR) {
269 tsk->maj_flt++;
270 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs,
271 addr);
272 } else {
273 tsk->min_flt++;
274 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs,
275 addr);
276 }
277 if (fault & VM_FAULT_RETRY) {
278 /*
279 * Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk of
280 * starvation.
281 */
282 flags &= ~FAULT_FLAG_ALLOW_RETRY;
283 goto retry;
284 }
285 }
286
287 up_read(&mm->mmap_sem);
288
289 /*
290 * Handle the "normal" case first - VM_FAULT_MAJOR / VM_FAULT_MINOR
291 */
292 if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP |
293 VM_FAULT_BADACCESS))))
294 return 0;
295
296 if (fault & VM_FAULT_OOM) {
297 /*
298 * We ran out of memory, call the OOM killer, and return to
299 * userspace (which will retry the fault, or kill us if we got
300 * oom-killed).
301 */
302 pagefault_out_of_memory();
303 return 0;
304 }
305
306 /*
307 * If we are in kernel mode at this point, we have no context to
308 * handle this fault with.
309 */
310 if (!user_mode(regs))
311 goto no_context;
312
313 if (fault & VM_FAULT_SIGBUS) {
314 /*
315 * We had some memory, but were unable to successfully fix up
316 * this page fault.
317 */
318 sig = SIGBUS;
319 code = BUS_ADRERR;
320 } else {
321 /*
322 * Something tried to access memory that isn't in our memory
323 * map.
324 */
325 sig = SIGSEGV;
326 code = fault == VM_FAULT_BADACCESS ?
327 SEGV_ACCERR : SEGV_MAPERR;
328 }
329
330 __do_user_fault(tsk, addr, esr, sig, code, regs);
331 return 0;
332
333 no_context:
334 __do_kernel_fault(mm, addr, esr, regs);
335 return 0;
336 }
337
338 /*
339 * First Level Translation Fault Handler
340 *
341 * We enter here because the first level page table doesn't contain a valid
342 * entry for the address.
343 *
344 * If the address is in kernel space (>= TASK_SIZE), then we are probably
345 * faulting in the vmalloc() area.
346 *
347 * If the init_task's first level page tables contains the relevant entry, we
348 * copy the it to this task. If not, we send the process a signal, fixup the
349 * exception, or oops the kernel.
350 *
351 * NOTE! We MUST NOT take any locks for this case. We may be in an interrupt
352 * or a critical region, and should only copy the information from the master
353 * page table, nothing more.
354 */
355 static int __kprobes do_translation_fault(unsigned long addr,
356 unsigned int esr,
357 struct pt_regs *regs)
358 {
359 if (addr < TASK_SIZE)
360 return do_page_fault(addr, esr, regs);
361
362 do_bad_area(addr, esr, regs);
363 return 0;
364 }
365
366 /*
367 * Some section permission faults need to be handled gracefully. They can
368 * happen due to a __{get,put}_user during an oops.
369 */
370 static int do_sect_fault(unsigned long addr, unsigned int esr,
371 struct pt_regs *regs)
372 {
373 do_bad_area(addr, esr, regs);
374 return 0;
375 }
376
377 /*
378 * This abort handler always returns "fault".
379 */
380 static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs)
381 {
382 return 1;
383 }
384
385 static struct fault_info {
386 int (*fn)(unsigned long addr, unsigned int esr, struct pt_regs *regs);
387 int sig;
388 int code;
389 const char *name;
390 } fault_info[] = {
391 { do_bad, SIGBUS, 0, "ttbr address size fault" },
392 { do_bad, SIGBUS, 0, "level 1 address size fault" },
393 { do_bad, SIGBUS, 0, "level 2 address size fault" },
394 { do_bad, SIGBUS, 0, "level 3 address size fault" },
395 { do_translation_fault, SIGSEGV, SEGV_MAPERR, "input address range fault" },
396 { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 1 translation fault" },
397 { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 2 translation fault" },
398 { do_page_fault, SIGSEGV, SEGV_MAPERR, "level 3 translation fault" },
399 { do_bad, SIGBUS, 0, "reserved access flag fault" },
400 { do_bad, SIGSEGV, SEGV_ACCERR, "level 1 access flag fault" },
401 { do_bad, SIGSEGV, SEGV_ACCERR, "level 2 access flag fault" },
402 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 3 access flag fault" },
403 { do_bad, SIGBUS, 0, "reserved permission fault" },
404 { do_bad, SIGSEGV, SEGV_ACCERR, "level 1 permission fault" },
405 { do_sect_fault, SIGSEGV, SEGV_ACCERR, "level 2 permission fault" },
406 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 3 permission fault" },
407 { do_bad, SIGBUS, 0, "synchronous external abort" },
408 { do_bad, SIGBUS, 0, "asynchronous external abort" },
409 { do_bad, SIGBUS, 0, "unknown 18" },
410 { do_bad, SIGBUS, 0, "unknown 19" },
411 { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" },
412 { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" },
413 { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" },
414 { do_bad, SIGBUS, 0, "synchronous abort (translation table walk)" },
415 { do_bad, SIGBUS, 0, "synchronous parity error" },
416 { do_bad, SIGBUS, 0, "asynchronous parity error" },
417 { do_bad, SIGBUS, 0, "unknown 26" },
418 { do_bad, SIGBUS, 0, "unknown 27" },
419 { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk" },
420 { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk" },
421 { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk" },
422 { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk" },
423 { do_bad, SIGBUS, 0, "unknown 32" },
424 { do_bad, SIGBUS, BUS_ADRALN, "alignment fault" },
425 { do_bad, SIGBUS, 0, "debug event" },
426 { do_bad, SIGBUS, 0, "unknown 35" },
427 { do_bad, SIGBUS, 0, "unknown 36" },
428 { do_bad, SIGBUS, 0, "unknown 37" },
429 { do_bad, SIGBUS, 0, "unknown 38" },
430 { do_bad, SIGBUS, 0, "unknown 39" },
431 { do_bad, SIGBUS, 0, "unknown 40" },
432 { do_bad, SIGBUS, 0, "unknown 41" },
433 { do_bad, SIGBUS, 0, "unknown 42" },
434 { do_bad, SIGBUS, 0, "unknown 43" },
435 { do_bad, SIGBUS, 0, "unknown 44" },
436 { do_bad, SIGBUS, 0, "unknown 45" },
437 { do_bad, SIGBUS, 0, "unknown 46" },
438 { do_bad, SIGBUS, 0, "unknown 47" },
439 { do_bad, SIGBUS, 0, "unknown 48" },
440 { do_bad, SIGBUS, 0, "unknown 49" },
441 { do_bad, SIGBUS, 0, "unknown 50" },
442 { do_bad, SIGBUS, 0, "unknown 51" },
443 { do_bad, SIGBUS, 0, "implementation fault (lockdown abort)" },
444 { do_bad, SIGBUS, 0, "unknown 53" },
445 { do_bad, SIGBUS, 0, "unknown 54" },
446 { do_bad, SIGBUS, 0, "unknown 55" },
447 { do_bad, SIGBUS, 0, "unknown 56" },
448 { do_bad, SIGBUS, 0, "unknown 57" },
449 { do_bad, SIGBUS, 0, "implementation fault (coprocessor abort)" },
450 { do_bad, SIGBUS, 0, "unknown 59" },
451 { do_bad, SIGBUS, 0, "unknown 60" },
452 { do_bad, SIGBUS, 0, "unknown 61" },
453 { do_bad, SIGBUS, 0, "unknown 62" },
454 { do_bad, SIGBUS, 0, "unknown 63" },
455 };
456
457 static const char *fault_name(unsigned int esr)
458 {
459 const struct fault_info *inf = fault_info + (esr & 63);
460 return inf->name;
461 }
462
463 /*
464 * Dispatch a data abort to the relevant handler.
465 */
466 asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr,
467 struct pt_regs *regs)
468 {
469 const struct fault_info *inf = fault_info + (esr & 63);
470 struct siginfo info;
471
472 if (!inf->fn(addr, esr, regs))
473 return;
474
475 pr_alert("Unhandled fault: %s (0x%08x) at 0x%016lx\n",
476 inf->name, esr, addr);
477
478 info.si_signo = inf->sig;
479 info.si_errno = 0;
480 info.si_code = inf->code;
481 info.si_addr = (void __user *)addr;
482 arm64_notify_die("", regs, &info, esr);
483 }
484
485 /*
486 * Handle stack alignment exceptions.
487 */
488 asmlinkage void __exception do_sp_pc_abort(unsigned long addr,
489 unsigned int esr,
490 struct pt_regs *regs)
491 {
492 struct siginfo info;
493
494 info.si_signo = SIGBUS;
495 info.si_errno = 0;
496 info.si_code = BUS_ADRALN;
497 info.si_addr = (void __user *)addr;
498 arm64_notify_die("", regs, &info, esr);
499 }
500
501 static struct fault_info debug_fault_info[] = {
502 { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware breakpoint" },
503 { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware single-step" },
504 { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware watchpoint" },
505 { do_bad, SIGBUS, 0, "unknown 3" },
506 { do_bad, SIGTRAP, TRAP_BRKPT, "aarch32 BKPT" },
507 { do_bad, SIGTRAP, 0, "aarch32 vector catch" },
508 { do_bad, SIGTRAP, TRAP_BRKPT, "aarch64 BRK" },
509 { do_bad, SIGBUS, 0, "unknown 7" },
510 };
511
512 void __init hook_debug_fault_code(int nr,
513 int (*fn)(unsigned long, unsigned int, struct pt_regs *),
514 int sig, int code, const char *name)
515 {
516 BUG_ON(nr < 0 || nr >= ARRAY_SIZE(debug_fault_info));
517
518 debug_fault_info[nr].fn = fn;
519 debug_fault_info[nr].sig = sig;
520 debug_fault_info[nr].code = code;
521 debug_fault_info[nr].name = name;
522 }
523
524 asmlinkage int __exception do_debug_exception(unsigned long addr,
525 unsigned int esr,
526 struct pt_regs *regs)
527 {
528 const struct fault_info *inf = debug_fault_info + DBG_ESR_EVT(esr);
529 struct siginfo info;
530
531 if (!inf->fn(addr, esr, regs))
532 return 1;
533
534 pr_alert("Unhandled debug exception: %s (0x%08x) at 0x%016lx\n",
535 inf->name, esr, addr);
536
537 info.si_signo = inf->sig;
538 info.si_errno = 0;
539 info.si_code = inf->code;
540 info.si_addr = (void __user *)addr;
541 arm64_notify_die("", regs, &info, esr);
542
543 return 0;
544 }
Linux with added FPC-III support