1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * PowerPC version
4 * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
5 *
6 * Derived from "arch/i386/mm/fault.c"
7 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
8 *
9 * Modified by Cort Dougan and Paul Mackerras.
10 *
11 * Modified for PPC64 by Dave Engebretsen (engebret@ibm.com)
12 */
13
14 #include <linux/signal.h>
15 #include <linux/sched.h>
16 #include <linux/sched/task_stack.h>
17 #include <linux/kernel.h>
18 #include <linux/errno.h>
19 #include <linux/string.h>
20 #include <linux/types.h>
21 #include <linux/pagemap.h>
22 #include <linux/ptrace.h>
23 #include <linux/mman.h>
24 #include <linux/mm.h>
25 #include <linux/interrupt.h>
26 #include <linux/highmem.h>
27 #include <linux/extable.h>
28 #include <linux/kprobes.h>
29 #include <linux/kdebug.h>
30 #include <linux/perf_event.h>
31 #include <linux/ratelimit.h>
32 #include <linux/context_tracking.h>
33 #include <linux/hugetlb.h>
34 #include <linux/uaccess.h>
35 #include <linux/kfence.h>
36 #include <linux/pkeys.h>
37
38 #include <asm/firmware.h>
39 #include <asm/interrupt.h>
40 #include <asm/page.h>
41 #include <asm/mmu.h>
42 #include <asm/mmu_context.h>
43 #include <asm/siginfo.h>
44 #include <asm/debug.h>
45 #include <asm/kup.h>
46 #include <asm/inst.h>
47
48
49 /*
50 * do_page_fault error handling helpers
51 */
52
53 static int
__bad_area_nosemaphore(struct pt_regs * regs,unsigned long address,int si_code)54 __bad_area_nosemaphore(struct pt_regs *regs, unsigned long address, int si_code)
55 {
56 /*
57 * If we are in kernel mode, bail out with a SEGV, this will
58 * be caught by the assembly which will restore the non-volatile
59 * registers before calling bad_page_fault()
60 */
61 if (!user_mode(regs))
62 return SIGSEGV;
63
64 _exception(SIGSEGV, regs, si_code, address);
65
66 return 0;
67 }
68
bad_area_nosemaphore(struct pt_regs * regs,unsigned long address)69 static noinline int bad_area_nosemaphore(struct pt_regs *regs, unsigned long address)
70 {
71 return __bad_area_nosemaphore(regs, address, SEGV_MAPERR);
72 }
73
__bad_area(struct pt_regs * regs,unsigned long address,int si_code,struct mm_struct * mm,struct vm_area_struct * vma)74 static int __bad_area(struct pt_regs *regs, unsigned long address, int si_code,
75 struct mm_struct *mm, struct vm_area_struct *vma)
76 {
77
78 /*
79 * Something tried to access memory that isn't in our memory map..
80 * Fix it, but check if it's kernel or user first..
81 */
82 if (mm)
83 mmap_read_unlock(mm);
84 else
85 vma_end_read(vma);
86
87 return __bad_area_nosemaphore(regs, address, si_code);
88 }
89
bad_access_pkey(struct pt_regs * regs,unsigned long address,struct mm_struct * mm,struct vm_area_struct * vma)90 static noinline int bad_access_pkey(struct pt_regs *regs, unsigned long address,
91 struct mm_struct *mm,
92 struct vm_area_struct *vma)
93 {
94 int pkey;
95
96 /*
97 * We don't try to fetch the pkey from page table because reading
98 * page table without locking doesn't guarantee stable pte value.
99 * Hence the pkey value that we return to userspace can be different
100 * from the pkey that actually caused access error.
101 *
102 * It does *not* guarantee that the VMA we find here
103 * was the one that we faulted on.
104 *
105 * 1. T1 : mprotect_key(foo, PAGE_SIZE, pkey=4);
106 * 2. T1 : set AMR to deny access to pkey=4, touches, page
107 * 3. T1 : faults...
108 * 4. T2: mprotect_key(foo, PAGE_SIZE, pkey=5);
109 * 5. T1 : enters fault handler, takes mmap_lock, etc...
110 * 6. T1 : reaches here, sees vma_pkey(vma)=5, when we really
111 * faulted on a pte with its pkey=4.
112 */
113 pkey = vma_pkey(vma);
114
115 if (mm)
116 mmap_read_unlock(mm);
117 else
118 vma_end_read(vma);
119
120 /*
121 * If we are in kernel mode, bail out with a SEGV, this will
122 * be caught by the assembly which will restore the non-volatile
123 * registers before calling bad_page_fault()
124 */
125 if (!user_mode(regs))
126 return SIGSEGV;
127
128 _exception_pkey(regs, address, pkey);
129
130 return 0;
131 }
132
bad_access(struct pt_regs * regs,unsigned long address,struct mm_struct * mm,struct vm_area_struct * vma)133 static noinline int bad_access(struct pt_regs *regs, unsigned long address,
134 struct mm_struct *mm, struct vm_area_struct *vma)
135 {
136 return __bad_area(regs, address, SEGV_ACCERR, mm, vma);
137 }
138
do_sigbus(struct pt_regs * regs,unsigned long address,vm_fault_t fault)139 static int do_sigbus(struct pt_regs *regs, unsigned long address,
140 vm_fault_t fault)
141 {
142 if (!user_mode(regs))
143 return SIGBUS;
144
145 current->thread.trap_nr = BUS_ADRERR;
146 #ifdef CONFIG_MEMORY_FAILURE
147 if (fault & (VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE)) {
148 unsigned int lsb = 0; /* shutup gcc */
149
150 pr_err("MCE: Killing %s:%d due to hardware memory corruption fault at %lx\n",
151 current->comm, current->pid, address);
152
153 if (fault & VM_FAULT_HWPOISON_LARGE)
154 lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault));
155 if (fault & VM_FAULT_HWPOISON)
156 lsb = PAGE_SHIFT;
157
158 force_sig_mceerr(BUS_MCEERR_AR, (void __user *)address, lsb);
159 return 0;
160 }
161
162 #endif
163 force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address);
164 return 0;
165 }
166
mm_fault_error(struct pt_regs * regs,unsigned long addr,vm_fault_t fault)167 static int mm_fault_error(struct pt_regs *regs, unsigned long addr,
168 vm_fault_t fault)
169 {
170 /*
171 * Kernel page fault interrupted by SIGKILL. We have no reason to
172 * continue processing.
173 */
174 if (fatal_signal_pending(current) && !user_mode(regs))
175 return SIGKILL;
176
177 /* Out of memory */
178 if (fault & VM_FAULT_OOM) {
179 /*
180 * We ran out of memory, or some other thing happened to us that
181 * made us unable to handle the page fault gracefully.
182 */
183 if (!user_mode(regs))
184 return SIGSEGV;
185 pagefault_out_of_memory();
186 } else {
187 if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON|
188 VM_FAULT_HWPOISON_LARGE))
189 return do_sigbus(regs, addr, fault);
190 else if (fault & VM_FAULT_SIGSEGV)
191 return bad_area_nosemaphore(regs, addr);
192 else
193 BUG();
194 }
195 return 0;
196 }
197
198 /* Is this a bad kernel fault ? */
bad_kernel_fault(struct pt_regs * regs,unsigned long error_code,unsigned long address,bool is_write)199 static bool bad_kernel_fault(struct pt_regs *regs, unsigned long error_code,
200 unsigned long address, bool is_write)
201 {
202 int is_exec = TRAP(regs) == INTERRUPT_INST_STORAGE;
203
204 if (is_exec) {
205 pr_crit_ratelimited("kernel tried to execute %s page (%lx) - exploit attempt? (uid: %d)\n",
206 address >= TASK_SIZE ? "exec-protected" : "user",
207 address,
208 from_kuid(&init_user_ns, current_uid()));
209
210 // Kernel exec fault is always bad
211 return true;
212 }
213
214 // Kernel fault on kernel address is bad
215 if (address >= TASK_SIZE)
216 return true;
217
218 // Read/write fault blocked by KUAP is bad, it can never succeed.
219 if (bad_kuap_fault(regs, address, is_write)) {
220 pr_crit_ratelimited("Kernel attempted to %s user page (%lx) - exploit attempt? (uid: %d)\n",
221 is_write ? "write" : "read", address,
222 from_kuid(&init_user_ns, current_uid()));
223
224 // Fault on user outside of certain regions (eg. copy_tofrom_user()) is bad
225 if (!search_exception_tables(regs->nip))
226 return true;
227
228 // Read/write fault in a valid region (the exception table search passed
229 // above), but blocked by KUAP is bad, it can never succeed.
230 return WARN(true, "Bug: %s fault blocked by KUAP!", is_write ? "Write" : "Read");
231 }
232
233 // What's left? Kernel fault on user and allowed by KUAP in the faulting context.
234 return false;
235 }
236
access_pkey_error(bool is_write,bool is_exec,bool is_pkey,struct vm_area_struct * vma)237 static bool access_pkey_error(bool is_write, bool is_exec, bool is_pkey,
238 struct vm_area_struct *vma)
239 {
240 /*
241 * Make sure to check the VMA so that we do not perform
242 * faults just to hit a pkey fault as soon as we fill in a
243 * page. Only called for current mm, hence foreign == 0
244 */
245 if (!arch_vma_access_permitted(vma, is_write, is_exec, 0))
246 return true;
247
248 return false;
249 }
250
access_error(bool is_write,bool is_exec,struct vm_area_struct * vma)251 static bool access_error(bool is_write, bool is_exec, struct vm_area_struct *vma)
252 {
253 /*
254 * Allow execution from readable areas if the MMU does not
255 * provide separate controls over reading and executing.
256 *
257 * Note: That code used to not be enabled for 4xx/BookE.
258 * It is now as I/D cache coherency for these is done at
259 * set_pte_at() time and I see no reason why the test
260 * below wouldn't be valid on those processors. This -may-
261 * break programs compiled with a really old ABI though.
262 */
263 if (is_exec) {
264 return !(vma->vm_flags & VM_EXEC) &&
265 (cpu_has_feature(CPU_FTR_NOEXECUTE) ||
266 !(vma->vm_flags & (VM_READ | VM_WRITE)));
267 }
268
269 if (is_write) {
270 if (unlikely(!(vma->vm_flags & VM_WRITE)))
271 return true;
272 return false;
273 }
274
275 /*
276 * VM_READ, VM_WRITE and VM_EXEC may imply read permissions, as
277 * defined in protection_map[]. In that case Read faults can only be
278 * caused by a PROT_NONE mapping. However a non exec access on a
279 * VM_EXEC only mapping is invalid anyway, so report it as such.
280 */
281 if (unlikely(!vma_is_accessible(vma)))
282 return true;
283
284 if ((vma->vm_flags & VM_ACCESS_FLAGS) == VM_EXEC)
285 return true;
286
287 /*
288 * We should ideally do the vma pkey access check here. But in the
289 * fault path, handle_mm_fault() also does the same check. To avoid
290 * these multiple checks, we skip it here and handle access error due
291 * to pkeys later.
292 */
293 return false;
294 }
295
296 #ifdef CONFIG_PPC_SMLPAR
cmo_account_page_fault(void)297 static inline void cmo_account_page_fault(void)
298 {
299 if (firmware_has_feature(FW_FEATURE_CMO)) {
300 u32 page_ins;
301
302 preempt_disable();
303 page_ins = be32_to_cpu(get_lppaca()->page_ins);
304 page_ins += 1 << PAGE_FACTOR;
305 get_lppaca()->page_ins = cpu_to_be32(page_ins);
306 preempt_enable();
307 }
308 }
309 #else
cmo_account_page_fault(void)310 static inline void cmo_account_page_fault(void) { }
311 #endif /* CONFIG_PPC_SMLPAR */
312
sanity_check_fault(bool is_write,bool is_user,unsigned long error_code,unsigned long address)313 static void sanity_check_fault(bool is_write, bool is_user,
314 unsigned long error_code, unsigned long address)
315 {
316 /*
317 * Userspace trying to access kernel address, we get PROTFAULT for that.
318 */
319 if (is_user && address >= TASK_SIZE) {
320 if ((long)address == -1)
321 return;
322
323 pr_crit_ratelimited("%s[%d]: User access of kernel address (%lx) - exploit attempt? (uid: %d)\n",
324 current->comm, current->pid, address,
325 from_kuid(&init_user_ns, current_uid()));
326 return;
327 }
328
329 if (!IS_ENABLED(CONFIG_PPC_BOOK3S))
330 return;
331
332 /*
333 * For hash translation mode, we should never get a
334 * PROTFAULT. Any update to pte to reduce access will result in us
335 * removing the hash page table entry, thus resulting in a DSISR_NOHPTE
336 * fault instead of DSISR_PROTFAULT.
337 *
338 * A pte update to relax the access will not result in a hash page table
339 * entry invalidate and hence can result in DSISR_PROTFAULT.
340 * ptep_set_access_flags() doesn't do a hpte flush. This is why we have
341 * the special !is_write in the below conditional.
342 *
343 * For platforms that doesn't supports coherent icache and do support
344 * per page noexec bit, we do setup things such that we do the
345 * sync between D/I cache via fault. But that is handled via low level
346 * hash fault code (hash_page_do_lazy_icache()) and we should not reach
347 * here in such case.
348 *
349 * For wrong access that can result in PROTFAULT, the above vma->vm_flags
350 * check should handle those and hence we should fall to the bad_area
351 * handling correctly.
352 *
353 * For embedded with per page exec support that doesn't support coherent
354 * icache we do get PROTFAULT and we handle that D/I cache sync in
355 * set_pte_at while taking the noexec/prot fault. Hence this is WARN_ON
356 * is conditional for server MMU.
357 *
358 * For radix, we can get prot fault for autonuma case, because radix
359 * page table will have them marked noaccess for user.
360 */
361 if (radix_enabled() || is_write)
362 return;
363
364 WARN_ON_ONCE(error_code & DSISR_PROTFAULT);
365 }
366
367 /*
368 * Define the correct "is_write" bit in error_code based
369 * on the processor family
370 */
371 #ifdef CONFIG_BOOKE
372 #define page_fault_is_write(__err) ((__err) & ESR_DST)
373 #else
374 #define page_fault_is_write(__err) ((__err) & DSISR_ISSTORE)
375 #endif
376
377 #ifdef CONFIG_BOOKE
378 #define page_fault_is_bad(__err) (0)
379 #elif defined(CONFIG_PPC_8xx)
380 #define page_fault_is_bad(__err) ((__err) & DSISR_NOEXEC_OR_G)
381 #elif defined(CONFIG_PPC64)
page_fault_is_bad(unsigned long err)382 static int page_fault_is_bad(unsigned long err)
383 {
384 unsigned long flag = DSISR_BAD_FAULT_64S;
385
386 /*
387 * PAPR+ v2.11 § 14.15.3.4.1 (unreleased)
388 * If byte 0, bit 3 of pi-attribute-specifier-type in
389 * ibm,pi-features property is defined, ignore the DSI error
390 * which is caused by the paste instruction on the
391 * suspended NX window.
392 */
393 if (mmu_has_feature(MMU_FTR_NX_DSI))
394 flag &= ~DSISR_BAD_COPYPASTE;
395
396 return err & flag;
397 }
398 #else
399 #define page_fault_is_bad(__err) ((__err) & DSISR_BAD_FAULT_32S)
400 #endif
401
402 /*
403 * For 600- and 800-family processors, the error_code parameter is DSISR
404 * for a data fault, SRR1 for an instruction fault.
405 * For 400-family processors the error_code parameter is ESR for a data fault,
406 * 0 for an instruction fault.
407 * For 64-bit processors, the error_code parameter is DSISR for a data access
408 * fault, SRR1 & 0x08000000 for an instruction access fault.
409 *
410 * The return value is 0 if the fault was handled, or the signal
411 * number if this is a kernel fault that can't be handled here.
412 */
___do_page_fault(struct pt_regs * regs,unsigned long address,unsigned long error_code)413 static int ___do_page_fault(struct pt_regs *regs, unsigned long address,
414 unsigned long error_code)
415 {
416 struct vm_area_struct * vma;
417 struct mm_struct *mm = current->mm;
418 unsigned int flags = FAULT_FLAG_DEFAULT;
419 int is_exec = TRAP(regs) == INTERRUPT_INST_STORAGE;
420 int is_user = user_mode(regs);
421 int is_write = page_fault_is_write(error_code);
422 vm_fault_t fault, major = 0;
423 bool kprobe_fault = kprobe_page_fault(regs, 11);
424
425 if (unlikely(debugger_fault_handler(regs) || kprobe_fault))
426 return 0;
427
428 if (unlikely(page_fault_is_bad(error_code))) {
429 if (is_user) {
430 _exception(SIGBUS, regs, BUS_OBJERR, address);
431 return 0;
432 }
433 return SIGBUS;
434 }
435
436 /* Additional sanity check(s) */
437 sanity_check_fault(is_write, is_user, error_code, address);
438
439 /*
440 * The kernel should never take an execute fault nor should it
441 * take a page fault to a kernel address or a page fault to a user
442 * address outside of dedicated places
443 */
444 if (unlikely(!is_user && bad_kernel_fault(regs, error_code, address, is_write))) {
445 if (kfence_handle_page_fault(address, is_write, regs))
446 return 0;
447
448 return SIGSEGV;
449 }
450
451 /*
452 * If we're in an interrupt, have no user context or are running
453 * in a region with pagefaults disabled then we must not take the fault
454 */
455 if (unlikely(faulthandler_disabled() || !mm)) {
456 if (is_user)
457 printk_ratelimited(KERN_ERR "Page fault in user mode"
458 " with faulthandler_disabled()=%d"
459 " mm=%p\n",
460 faulthandler_disabled(), mm);
461 return bad_area_nosemaphore(regs, address);
462 }
463
464 interrupt_cond_local_irq_enable(regs);
465
466 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
467
468 /*
469 * We want to do this outside mmap_lock, because reading code around nip
470 * can result in fault, which will cause a deadlock when called with
471 * mmap_lock held
472 */
473 if (is_user)
474 flags |= FAULT_FLAG_USER;
475 if (is_write)
476 flags |= FAULT_FLAG_WRITE;
477 if (is_exec)
478 flags |= FAULT_FLAG_INSTRUCTION;
479
480 if (!(flags & FAULT_FLAG_USER))
481 goto lock_mmap;
482
483 vma = lock_vma_under_rcu(mm, address);
484 if (!vma)
485 goto lock_mmap;
486
487 if (unlikely(access_pkey_error(is_write, is_exec,
488 (error_code & DSISR_KEYFAULT), vma))) {
489 count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
490 return bad_access_pkey(regs, address, NULL, vma);
491 }
492
493 if (unlikely(access_error(is_write, is_exec, vma))) {
494 count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
495 return bad_access(regs, address, NULL, vma);
496 }
497
498 fault = handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs);
499 if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED)))
500 vma_end_read(vma);
501
502 if (!(fault & VM_FAULT_RETRY)) {
503 count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
504 goto done;
505 }
506 count_vm_vma_lock_event(VMA_LOCK_RETRY);
507 if (fault & VM_FAULT_MAJOR)
508 flags |= FAULT_FLAG_TRIED;
509
510 if (fault_signal_pending(fault, regs))
511 return user_mode(regs) ? 0 : SIGBUS;
512
513 lock_mmap:
514
515 /* When running in the kernel we expect faults to occur only to
516 * addresses in user space. All other faults represent errors in the
517 * kernel and should generate an OOPS. Unfortunately, in the case of an
518 * erroneous fault occurring in a code path which already holds mmap_lock
519 * we will deadlock attempting to validate the fault against the
520 * address space. Luckily the kernel only validly references user
521 * space from well defined areas of code, which are listed in the
522 * exceptions table. lock_mm_and_find_vma() handles that logic.
523 */
524 retry:
525 vma = lock_mm_and_find_vma(mm, address, regs);
526 if (unlikely(!vma))
527 return bad_area_nosemaphore(regs, address);
528
529 if (unlikely(access_pkey_error(is_write, is_exec,
530 (error_code & DSISR_KEYFAULT), vma)))
531 return bad_access_pkey(regs, address, mm, vma);
532
533 if (unlikely(access_error(is_write, is_exec, vma)))
534 return bad_access(regs, address, mm, vma);
535
536 /*
537 * If for any reason at all we couldn't handle the fault,
538 * make sure we exit gracefully rather than endlessly redo
539 * the fault.
540 */
541 fault = handle_mm_fault(vma, address, flags, regs);
542
543 major |= fault & VM_FAULT_MAJOR;
544
545 if (fault_signal_pending(fault, regs))
546 return user_mode(regs) ? 0 : SIGBUS;
547
548 /* The fault is fully completed (including releasing mmap lock) */
549 if (fault & VM_FAULT_COMPLETED)
550 goto out;
551
552 /*
553 * Handle the retry right now, the mmap_lock has been released in that
554 * case.
555 */
556 if (unlikely(fault & VM_FAULT_RETRY)) {
557 flags |= FAULT_FLAG_TRIED;
558 goto retry;
559 }
560
561 mmap_read_unlock(current->mm);
562
563 done:
564 if (unlikely(fault & VM_FAULT_ERROR))
565 return mm_fault_error(regs, address, fault);
566
567 out:
568 /*
569 * Major/minor page fault accounting.
570 */
571 if (major)
572 cmo_account_page_fault();
573
574 return 0;
575 }
576 NOKPROBE_SYMBOL(___do_page_fault);
577
__do_page_fault(struct pt_regs * regs)578 static __always_inline void __do_page_fault(struct pt_regs *regs)
579 {
580 long err;
581
582 err = ___do_page_fault(regs, regs->dar, regs->dsisr);
583 if (unlikely(err))
584 bad_page_fault(regs, err);
585 }
586
DEFINE_INTERRUPT_HANDLER(do_page_fault)587 DEFINE_INTERRUPT_HANDLER(do_page_fault)
588 {
589 __do_page_fault(regs);
590 }
591
592 #ifdef CONFIG_PPC_BOOK3S_64
593 /* Same as do_page_fault but interrupt entry has already run in do_hash_fault */
hash__do_page_fault(struct pt_regs * regs)594 void hash__do_page_fault(struct pt_regs *regs)
595 {
596 __do_page_fault(regs);
597 }
598 NOKPROBE_SYMBOL(hash__do_page_fault);
599 #endif
600
601 /*
602 * bad_page_fault is called when we have a bad access from the kernel.
603 * It is called from the DSI and ISI handlers in head.S and from some
604 * of the procedures in traps.c.
605 */
__bad_page_fault(struct pt_regs * regs,int sig)606 static void __bad_page_fault(struct pt_regs *regs, int sig)
607 {
608 int is_write = page_fault_is_write(regs->dsisr);
609 const char *msg;
610
611 /* kernel has accessed a bad area */
612
613 if (regs->dar < PAGE_SIZE)
614 msg = "Kernel NULL pointer dereference";
615 else
616 msg = "Unable to handle kernel data access";
617
618 switch (TRAP(regs)) {
619 case INTERRUPT_DATA_STORAGE:
620 case INTERRUPT_H_DATA_STORAGE:
621 pr_alert("BUG: %s on %s at 0x%08lx\n", msg,
622 is_write ? "write" : "read", regs->dar);
623 break;
624 case INTERRUPT_DATA_SEGMENT:
625 pr_alert("BUG: %s at 0x%08lx\n", msg, regs->dar);
626 break;
627 case INTERRUPT_INST_STORAGE:
628 case INTERRUPT_INST_SEGMENT:
629 pr_alert("BUG: Unable to handle kernel instruction fetch%s",
630 regs->nip < PAGE_SIZE ? " (NULL pointer?)\n" : "\n");
631 break;
632 case INTERRUPT_ALIGNMENT:
633 pr_alert("BUG: Unable to handle kernel unaligned access at 0x%08lx\n",
634 regs->dar);
635 break;
636 default:
637 pr_alert("BUG: Unable to handle unknown paging fault at 0x%08lx\n",
638 regs->dar);
639 break;
640 }
641 printk(KERN_ALERT "Faulting instruction address: 0x%08lx\n",
642 regs->nip);
643
644 if (task_stack_end_corrupted(current))
645 printk(KERN_ALERT "Thread overran stack, or stack corrupted\n");
646
647 die("Kernel access of bad area", regs, sig);
648 }
649
bad_page_fault(struct pt_regs * regs,int sig)650 void bad_page_fault(struct pt_regs *regs, int sig)
651 {
652 const struct exception_table_entry *entry;
653
654 /* Are we prepared to handle this fault? */
655 entry = search_exception_tables(instruction_pointer(regs));
656 if (entry)
657 instruction_pointer_set(regs, extable_fixup(entry));
658 else
659 __bad_page_fault(regs, sig);
660 }
661
662 #ifdef CONFIG_PPC_BOOK3S_64
DEFINE_INTERRUPT_HANDLER(do_bad_page_fault_segv)663 DEFINE_INTERRUPT_HANDLER(do_bad_page_fault_segv)
664 {
665 bad_page_fault(regs, SIGSEGV);
666 }
667
668 /*
669 * In radix, segment interrupts indicate the EA is not addressable by the
670 * page table geometry, so they are always sent here.
671 *
672 * In hash, this is called if do_slb_fault returns error. Typically it is
673 * because the EA was outside the region allowed by software.
674 */
DEFINE_INTERRUPT_HANDLER(do_bad_segment_interrupt)675 DEFINE_INTERRUPT_HANDLER(do_bad_segment_interrupt)
676 {
677 int err = regs->result;
678
679 if (err == -EFAULT) {
680 if (user_mode(regs))
681 _exception(SIGSEGV, regs, SEGV_BNDERR, regs->dar);
682 else
683 bad_page_fault(regs, SIGSEGV);
684 } else if (err == -EINVAL) {
685 unrecoverable_exception(regs);
686 } else {
687 BUG();
688 }
689 }
690 #endif
691