1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * S390 version
4 * Copyright IBM Corp. 1999
5 * Author(s): Hartmut Penner (hp@de.ibm.com)
6 * Ulrich Weigand (uweigand@de.ibm.com)
7 *
8 * Derived from "arch/i386/mm/fault.c"
9 * Copyright (C) 1995 Linus Torvalds
10 */
11
12 #include <linux/kernel_stat.h>
13 #include <linux/perf_event.h>
14 #include <linux/signal.h>
15 #include <linux/sched.h>
16 #include <linux/sched/debug.h>
17 #include <linux/kernel.h>
18 #include <linux/errno.h>
19 #include <linux/string.h>
20 #include <linux/types.h>
21 #include <linux/ptrace.h>
22 #include <linux/mman.h>
23 #include <linux/mm.h>
24 #include <linux/compat.h>
25 #include <linux/smp.h>
26 #include <linux/kdebug.h>
27 #include <linux/init.h>
28 #include <linux/console.h>
29 #include <linux/extable.h>
30 #include <linux/hardirq.h>
31 #include <linux/kprobes.h>
32 #include <linux/uaccess.h>
33 #include <linux/hugetlb.h>
34 #include <asm/asm-offsets.h>
35 #include <asm/diag.h>
36 #include <asm/gmap.h>
37 #include <asm/irq.h>
38 #include <asm/mmu_context.h>
39 #include <asm/facility.h>
40 #include <asm/uv.h>
41 #include "../kernel/entry.h"
42
43 #define __FAIL_ADDR_MASK -4096L
44 #define __SUBCODE_MASK 0x0600
45 #define __PF_RES_FIELD 0x8000000000000000ULL
46
47 #define VM_FAULT_BADCONTEXT ((__force vm_fault_t) 0x010000)
48 #define VM_FAULT_BADMAP ((__force vm_fault_t) 0x020000)
49 #define VM_FAULT_BADACCESS ((__force vm_fault_t) 0x040000)
50 #define VM_FAULT_SIGNAL ((__force vm_fault_t) 0x080000)
51 #define VM_FAULT_PFAULT ((__force vm_fault_t) 0x100000)
52
53 enum fault_type {
54 KERNEL_FAULT,
55 USER_FAULT,
56 VDSO_FAULT,
57 GMAP_FAULT,
58 };
59
60 static unsigned long store_indication __read_mostly;
61
fault_init(void)62 static int __init fault_init(void)
63 {
64 if (test_facility(75))
65 store_indication = 0xc00;
66 return 0;
67 }
68 early_initcall(fault_init);
69
70 /*
71 * Find out which address space caused the exception.
72 */
get_fault_type(struct pt_regs * regs)73 static enum fault_type get_fault_type(struct pt_regs *regs)
74 {
75 unsigned long trans_exc_code;
76
77 trans_exc_code = regs->int_parm_long & 3;
78 if (likely(trans_exc_code == 0)) {
79 /* primary space exception */
80 if (IS_ENABLED(CONFIG_PGSTE) &&
81 test_pt_regs_flag(regs, PIF_GUEST_FAULT))
82 return GMAP_FAULT;
83 if (current->thread.mm_segment == USER_DS)
84 return USER_FAULT;
85 return KERNEL_FAULT;
86 }
87 if (trans_exc_code == 2) {
88 /* secondary space exception */
89 if (current->thread.mm_segment & 1) {
90 if (current->thread.mm_segment == USER_DS_SACF)
91 return USER_FAULT;
92 return KERNEL_FAULT;
93 }
94 return VDSO_FAULT;
95 }
96 if (trans_exc_code == 1) {
97 /* access register mode, not used in the kernel */
98 return USER_FAULT;
99 }
100 /* home space exception -> access via kernel ASCE */
101 return KERNEL_FAULT;
102 }
103
bad_address(void * p)104 static int bad_address(void *p)
105 {
106 unsigned long dummy;
107
108 return get_kernel_nofault(dummy, (unsigned long *)p);
109 }
110
dump_pagetable(unsigned long asce,unsigned long address)111 static void dump_pagetable(unsigned long asce, unsigned long address)
112 {
113 unsigned long *table = __va(asce & _ASCE_ORIGIN);
114
115 pr_alert("AS:%016lx ", asce);
116 switch (asce & _ASCE_TYPE_MASK) {
117 case _ASCE_TYPE_REGION1:
118 table += (address & _REGION1_INDEX) >> _REGION1_SHIFT;
119 if (bad_address(table))
120 goto bad;
121 pr_cont("R1:%016lx ", *table);
122 if (*table & _REGION_ENTRY_INVALID)
123 goto out;
124 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
125 fallthrough;
126 case _ASCE_TYPE_REGION2:
127 table += (address & _REGION2_INDEX) >> _REGION2_SHIFT;
128 if (bad_address(table))
129 goto bad;
130 pr_cont("R2:%016lx ", *table);
131 if (*table & _REGION_ENTRY_INVALID)
132 goto out;
133 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
134 fallthrough;
135 case _ASCE_TYPE_REGION3:
136 table += (address & _REGION3_INDEX) >> _REGION3_SHIFT;
137 if (bad_address(table))
138 goto bad;
139 pr_cont("R3:%016lx ", *table);
140 if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE))
141 goto out;
142 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
143 fallthrough;
144 case _ASCE_TYPE_SEGMENT:
145 table += (address & _SEGMENT_INDEX) >> _SEGMENT_SHIFT;
146 if (bad_address(table))
147 goto bad;
148 pr_cont("S:%016lx ", *table);
149 if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE))
150 goto out;
151 table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
152 }
153 table += (address & _PAGE_INDEX) >> _PAGE_SHIFT;
154 if (bad_address(table))
155 goto bad;
156 pr_cont("P:%016lx ", *table);
157 out:
158 pr_cont("\n");
159 return;
160 bad:
161 pr_cont("BAD\n");
162 }
163
dump_fault_info(struct pt_regs * regs)164 static void dump_fault_info(struct pt_regs *regs)
165 {
166 unsigned long asce;
167
168 pr_alert("Failing address: %016lx TEID: %016lx\n",
169 regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long);
170 pr_alert("Fault in ");
171 switch (regs->int_parm_long & 3) {
172 case 3:
173 pr_cont("home space ");
174 break;
175 case 2:
176 pr_cont("secondary space ");
177 break;
178 case 1:
179 pr_cont("access register ");
180 break;
181 case 0:
182 pr_cont("primary space ");
183 break;
184 }
185 pr_cont("mode while using ");
186 switch (get_fault_type(regs)) {
187 case USER_FAULT:
188 asce = S390_lowcore.user_asce;
189 pr_cont("user ");
190 break;
191 case VDSO_FAULT:
192 asce = S390_lowcore.vdso_asce;
193 pr_cont("vdso ");
194 break;
195 case GMAP_FAULT:
196 asce = ((struct gmap *) S390_lowcore.gmap)->asce;
197 pr_cont("gmap ");
198 break;
199 case KERNEL_FAULT:
200 asce = S390_lowcore.kernel_asce;
201 pr_cont("kernel ");
202 break;
203 default:
204 unreachable();
205 }
206 pr_cont("ASCE.\n");
207 dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK);
208 }
209
210 int show_unhandled_signals = 1;
211
report_user_fault(struct pt_regs * regs,long signr,int is_mm_fault)212 void report_user_fault(struct pt_regs *regs, long signr, int is_mm_fault)
213 {
214 if ((task_pid_nr(current) > 1) && !show_unhandled_signals)
215 return;
216 if (!unhandled_signal(current, signr))
217 return;
218 if (!printk_ratelimit())
219 return;
220 printk(KERN_ALERT "User process fault: interruption code %04x ilc:%d ",
221 regs->int_code & 0xffff, regs->int_code >> 17);
222 print_vma_addr(KERN_CONT "in ", regs->psw.addr);
223 printk(KERN_CONT "\n");
224 if (is_mm_fault)
225 dump_fault_info(regs);
226 show_regs(regs);
227 }
228
229 /*
230 * Send SIGSEGV to task. This is an external routine
231 * to keep the stack usage of do_page_fault small.
232 */
do_sigsegv(struct pt_regs * regs,int si_code)233 static noinline void do_sigsegv(struct pt_regs *regs, int si_code)
234 {
235 report_user_fault(regs, SIGSEGV, 1);
236 force_sig_fault(SIGSEGV, si_code,
237 (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK));
238 }
239
s390_search_extables(unsigned long addr)240 const struct exception_table_entry *s390_search_extables(unsigned long addr)
241 {
242 const struct exception_table_entry *fixup;
243
244 fixup = search_extable(__start_dma_ex_table,
245 __stop_dma_ex_table - __start_dma_ex_table,
246 addr);
247 if (!fixup)
248 fixup = search_exception_tables(addr);
249 return fixup;
250 }
251
do_no_context(struct pt_regs * regs)252 static noinline void do_no_context(struct pt_regs *regs)
253 {
254 const struct exception_table_entry *fixup;
255
256 /* Are we prepared to handle this kernel fault? */
257 fixup = s390_search_extables(regs->psw.addr);
258 if (fixup && ex_handle(fixup, regs))
259 return;
260
261 /*
262 * Oops. The kernel tried to access some bad page. We'll have to
263 * terminate things with extreme prejudice.
264 */
265 if (get_fault_type(regs) == KERNEL_FAULT)
266 printk(KERN_ALERT "Unable to handle kernel pointer dereference"
267 " in virtual kernel address space\n");
268 else
269 printk(KERN_ALERT "Unable to handle kernel paging request"
270 " in virtual user address space\n");
271 dump_fault_info(regs);
272 die(regs, "Oops");
273 do_exit(SIGKILL);
274 }
275
do_low_address(struct pt_regs * regs)276 static noinline void do_low_address(struct pt_regs *regs)
277 {
278 /* Low-address protection hit in kernel mode means
279 NULL pointer write access in kernel mode. */
280 if (regs->psw.mask & PSW_MASK_PSTATE) {
281 /* Low-address protection hit in user mode 'cannot happen'. */
282 die (regs, "Low-address protection");
283 do_exit(SIGKILL);
284 }
285
286 do_no_context(regs);
287 }
288
do_sigbus(struct pt_regs * regs)289 static noinline void do_sigbus(struct pt_regs *regs)
290 {
291 /*
292 * Send a sigbus, regardless of whether we were in kernel
293 * or user mode.
294 */
295 force_sig_fault(SIGBUS, BUS_ADRERR,
296 (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK));
297 }
298
signal_return(struct pt_regs * regs)299 static noinline int signal_return(struct pt_regs *regs)
300 {
301 u16 instruction;
302 int rc;
303
304 rc = __get_user(instruction, (u16 __user *) regs->psw.addr);
305 if (rc)
306 return rc;
307 if (instruction == 0x0a77) {
308 set_pt_regs_flag(regs, PIF_SYSCALL);
309 regs->int_code = 0x00040077;
310 return 0;
311 } else if (instruction == 0x0aad) {
312 set_pt_regs_flag(regs, PIF_SYSCALL);
313 regs->int_code = 0x000400ad;
314 return 0;
315 }
316 return -EACCES;
317 }
318
do_fault_error(struct pt_regs * regs,int access,vm_fault_t fault)319 static noinline void do_fault_error(struct pt_regs *regs, int access,
320 vm_fault_t fault)
321 {
322 int si_code;
323
324 switch (fault) {
325 case VM_FAULT_BADACCESS:
326 if (access == VM_EXEC && signal_return(regs) == 0)
327 break;
328 fallthrough;
329 case VM_FAULT_BADMAP:
330 /* Bad memory access. Check if it is kernel or user space. */
331 if (user_mode(regs)) {
332 /* User mode accesses just cause a SIGSEGV */
333 si_code = (fault == VM_FAULT_BADMAP) ?
334 SEGV_MAPERR : SEGV_ACCERR;
335 do_sigsegv(regs, si_code);
336 break;
337 }
338 fallthrough;
339 case VM_FAULT_BADCONTEXT:
340 case VM_FAULT_PFAULT:
341 do_no_context(regs);
342 break;
343 case VM_FAULT_SIGNAL:
344 if (!user_mode(regs))
345 do_no_context(regs);
346 break;
347 default: /* fault & VM_FAULT_ERROR */
348 if (fault & VM_FAULT_OOM) {
349 if (!user_mode(regs))
350 do_no_context(regs);
351 else
352 pagefault_out_of_memory();
353 } else if (fault & VM_FAULT_SIGSEGV) {
354 /* Kernel mode? Handle exceptions or die */
355 if (!user_mode(regs))
356 do_no_context(regs);
357 else
358 do_sigsegv(regs, SEGV_MAPERR);
359 } else if (fault & VM_FAULT_SIGBUS) {
360 /* Kernel mode? Handle exceptions or die */
361 if (!user_mode(regs))
362 do_no_context(regs);
363 else
364 do_sigbus(regs);
365 } else
366 BUG();
367 break;
368 }
369 }
370
371 /*
372 * This routine handles page faults. It determines the address,
373 * and the problem, and then passes it off to one of the appropriate
374 * routines.
375 *
376 * interruption code (int_code):
377 * 04 Protection -> Write-Protection (suppression)
378 * 10 Segment translation -> Not present (nullification)
379 * 11 Page translation -> Not present (nullification)
380 * 3b Region third trans. -> Not present (nullification)
381 */
do_exception(struct pt_regs * regs,int access)382 static inline vm_fault_t do_exception(struct pt_regs *regs, int access)
383 {
384 struct gmap *gmap;
385 struct task_struct *tsk;
386 struct mm_struct *mm;
387 struct vm_area_struct *vma;
388 enum fault_type type;
389 unsigned long trans_exc_code;
390 unsigned long address;
391 unsigned int flags;
392 vm_fault_t fault;
393
394 tsk = current;
395 /*
396 * The instruction that caused the program check has
397 * been nullified. Don't signal single step via SIGTRAP.
398 */
399 clear_pt_regs_flag(regs, PIF_PER_TRAP);
400
401 if (kprobe_page_fault(regs, 14))
402 return 0;
403
404 mm = tsk->mm;
405 trans_exc_code = regs->int_parm_long;
406
407 /*
408 * Verify that the fault happened in user space, that
409 * we are not in an interrupt and that there is a
410 * user context.
411 */
412 fault = VM_FAULT_BADCONTEXT;
413 type = get_fault_type(regs);
414 switch (type) {
415 case KERNEL_FAULT:
416 goto out;
417 case VDSO_FAULT:
418 fault = VM_FAULT_BADMAP;
419 goto out;
420 case USER_FAULT:
421 case GMAP_FAULT:
422 if (faulthandler_disabled() || !mm)
423 goto out;
424 break;
425 }
426
427 address = trans_exc_code & __FAIL_ADDR_MASK;
428 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
429 flags = FAULT_FLAG_DEFAULT;
430 if (user_mode(regs))
431 flags |= FAULT_FLAG_USER;
432 if ((trans_exc_code & store_indication) == 0x400)
433 access = VM_WRITE;
434 if (access == VM_WRITE)
435 flags |= FAULT_FLAG_WRITE;
436 mmap_read_lock(mm);
437
438 gmap = NULL;
439 if (IS_ENABLED(CONFIG_PGSTE) && type == GMAP_FAULT) {
440 gmap = (struct gmap *) S390_lowcore.gmap;
441 current->thread.gmap_addr = address;
442 current->thread.gmap_write_flag = !!(flags & FAULT_FLAG_WRITE);
443 current->thread.gmap_int_code = regs->int_code & 0xffff;
444 address = __gmap_translate(gmap, address);
445 if (address == -EFAULT) {
446 fault = VM_FAULT_BADMAP;
447 goto out_up;
448 }
449 if (gmap->pfault_enabled)
450 flags |= FAULT_FLAG_RETRY_NOWAIT;
451 }
452
453 retry:
454 fault = VM_FAULT_BADMAP;
455 vma = find_vma(mm, address);
456 if (!vma)
457 goto out_up;
458
459 if (unlikely(vma->vm_start > address)) {
460 if (!(vma->vm_flags & VM_GROWSDOWN))
461 goto out_up;
462 if (expand_stack(vma, address))
463 goto out_up;
464 }
465
466 /*
467 * Ok, we have a good vm_area for this memory access, so
468 * we can handle it..
469 */
470 fault = VM_FAULT_BADACCESS;
471 if (unlikely(!(vma->vm_flags & access)))
472 goto out_up;
473
474 if (is_vm_hugetlb_page(vma))
475 address &= HPAGE_MASK;
476 /*
477 * If for any reason at all we couldn't handle the fault,
478 * make sure we exit gracefully rather than endlessly redo
479 * the fault.
480 */
481 fault = handle_mm_fault(vma, address, flags, regs);
482 if (fault_signal_pending(fault, regs)) {
483 fault = VM_FAULT_SIGNAL;
484 if (flags & FAULT_FLAG_RETRY_NOWAIT)
485 goto out_up;
486 goto out;
487 }
488 if (unlikely(fault & VM_FAULT_ERROR))
489 goto out_up;
490
491 if (flags & FAULT_FLAG_ALLOW_RETRY) {
492 if (fault & VM_FAULT_RETRY) {
493 if (IS_ENABLED(CONFIG_PGSTE) && gmap &&
494 (flags & FAULT_FLAG_RETRY_NOWAIT)) {
495 /* FAULT_FLAG_RETRY_NOWAIT has been set,
496 * mmap_lock has not been released */
497 current->thread.gmap_pfault = 1;
498 fault = VM_FAULT_PFAULT;
499 goto out_up;
500 }
501 flags &= ~FAULT_FLAG_RETRY_NOWAIT;
502 flags |= FAULT_FLAG_TRIED;
503 mmap_read_lock(mm);
504 goto retry;
505 }
506 }
507 if (IS_ENABLED(CONFIG_PGSTE) && gmap) {
508 address = __gmap_link(gmap, current->thread.gmap_addr,
509 address);
510 if (address == -EFAULT) {
511 fault = VM_FAULT_BADMAP;
512 goto out_up;
513 }
514 if (address == -ENOMEM) {
515 fault = VM_FAULT_OOM;
516 goto out_up;
517 }
518 }
519 fault = 0;
520 out_up:
521 mmap_read_unlock(mm);
522 out:
523 return fault;
524 }
525
do_protection_exception(struct pt_regs * regs)526 void do_protection_exception(struct pt_regs *regs)
527 {
528 unsigned long trans_exc_code;
529 int access;
530 vm_fault_t fault;
531
532 trans_exc_code = regs->int_parm_long;
533 /*
534 * Protection exceptions are suppressing, decrement psw address.
535 * The exception to this rule are aborted transactions, for these
536 * the PSW already points to the correct location.
537 */
538 if (!(regs->int_code & 0x200))
539 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
540 /*
541 * Check for low-address protection. This needs to be treated
542 * as a special case because the translation exception code
543 * field is not guaranteed to contain valid data in this case.
544 */
545 if (unlikely(!(trans_exc_code & 4))) {
546 do_low_address(regs);
547 return;
548 }
549 if (unlikely(MACHINE_HAS_NX && (trans_exc_code & 0x80))) {
550 regs->int_parm_long = (trans_exc_code & ~PAGE_MASK) |
551 (regs->psw.addr & PAGE_MASK);
552 access = VM_EXEC;
553 fault = VM_FAULT_BADACCESS;
554 } else {
555 access = VM_WRITE;
556 fault = do_exception(regs, access);
557 }
558 if (unlikely(fault))
559 do_fault_error(regs, access, fault);
560 }
561 NOKPROBE_SYMBOL(do_protection_exception);
562
do_dat_exception(struct pt_regs * regs)563 void do_dat_exception(struct pt_regs *regs)
564 {
565 int access;
566 vm_fault_t fault;
567
568 access = VM_ACCESS_FLAGS;
569 fault = do_exception(regs, access);
570 if (unlikely(fault))
571 do_fault_error(regs, access, fault);
572 }
573 NOKPROBE_SYMBOL(do_dat_exception);
574
575 #ifdef CONFIG_PFAULT
576 /*
577 * 'pfault' pseudo page faults routines.
578 */
579 static int pfault_disable;
580
nopfault(char * str)581 static int __init nopfault(char *str)
582 {
583 pfault_disable = 1;
584 return 1;
585 }
586
587 __setup("nopfault", nopfault);
588
589 struct pfault_refbk {
590 u16 refdiagc;
591 u16 reffcode;
592 u16 refdwlen;
593 u16 refversn;
594 u64 refgaddr;
595 u64 refselmk;
596 u64 refcmpmk;
597 u64 reserved;
598 } __attribute__ ((packed, aligned(8)));
599
600 static struct pfault_refbk pfault_init_refbk = {
601 .refdiagc = 0x258,
602 .reffcode = 0,
603 .refdwlen = 5,
604 .refversn = 2,
605 .refgaddr = __LC_LPP,
606 .refselmk = 1ULL << 48,
607 .refcmpmk = 1ULL << 48,
608 .reserved = __PF_RES_FIELD
609 };
610
pfault_init(void)611 int pfault_init(void)
612 {
613 int rc;
614
615 if (pfault_disable)
616 return -1;
617 diag_stat_inc(DIAG_STAT_X258);
618 asm volatile(
619 " diag %1,%0,0x258\n"
620 "0: j 2f\n"
621 "1: la %0,8\n"
622 "2:\n"
623 EX_TABLE(0b,1b)
624 : "=d" (rc)
625 : "a" (&pfault_init_refbk), "m" (pfault_init_refbk) : "cc");
626 return rc;
627 }
628
629 static struct pfault_refbk pfault_fini_refbk = {
630 .refdiagc = 0x258,
631 .reffcode = 1,
632 .refdwlen = 5,
633 .refversn = 2,
634 };
635
pfault_fini(void)636 void pfault_fini(void)
637 {
638
639 if (pfault_disable)
640 return;
641 diag_stat_inc(DIAG_STAT_X258);
642 asm volatile(
643 " diag %0,0,0x258\n"
644 "0: nopr %%r7\n"
645 EX_TABLE(0b,0b)
646 : : "a" (&pfault_fini_refbk), "m" (pfault_fini_refbk) : "cc");
647 }
648
649 static DEFINE_SPINLOCK(pfault_lock);
650 static LIST_HEAD(pfault_list);
651
652 #define PF_COMPLETE 0x0080
653
654 /*
655 * The mechanism of our pfault code: if Linux is running as guest, runs a user
656 * space process and the user space process accesses a page that the host has
657 * paged out we get a pfault interrupt.
658 *
659 * This allows us, within the guest, to schedule a different process. Without
660 * this mechanism the host would have to suspend the whole virtual cpu until
661 * the page has been paged in.
662 *
663 * So when we get such an interrupt then we set the state of the current task
664 * to uninterruptible and also set the need_resched flag. Both happens within
665 * interrupt context(!). If we later on want to return to user space we
666 * recognize the need_resched flag and then call schedule(). It's not very
667 * obvious how this works...
668 *
669 * Of course we have a lot of additional fun with the completion interrupt (->
670 * host signals that a page of a process has been paged in and the process can
671 * continue to run). This interrupt can arrive on any cpu and, since we have
672 * virtual cpus, actually appear before the interrupt that signals that a page
673 * is missing.
674 */
pfault_interrupt(struct ext_code ext_code,unsigned int param32,unsigned long param64)675 static void pfault_interrupt(struct ext_code ext_code,
676 unsigned int param32, unsigned long param64)
677 {
678 struct task_struct *tsk;
679 __u16 subcode;
680 pid_t pid;
681
682 /*
683 * Get the external interruption subcode & pfault initial/completion
684 * signal bit. VM stores this in the 'cpu address' field associated
685 * with the external interrupt.
686 */
687 subcode = ext_code.subcode;
688 if ((subcode & 0xff00) != __SUBCODE_MASK)
689 return;
690 inc_irq_stat(IRQEXT_PFL);
691 /* Get the token (= pid of the affected task). */
692 pid = param64 & LPP_PID_MASK;
693 rcu_read_lock();
694 tsk = find_task_by_pid_ns(pid, &init_pid_ns);
695 if (tsk)
696 get_task_struct(tsk);
697 rcu_read_unlock();
698 if (!tsk)
699 return;
700 spin_lock(&pfault_lock);
701 if (subcode & PF_COMPLETE) {
702 /* signal bit is set -> a page has been swapped in by VM */
703 if (tsk->thread.pfault_wait == 1) {
704 /* Initial interrupt was faster than the completion
705 * interrupt. pfault_wait is valid. Set pfault_wait
706 * back to zero and wake up the process. This can
707 * safely be done because the task is still sleeping
708 * and can't produce new pfaults. */
709 tsk->thread.pfault_wait = 0;
710 list_del(&tsk->thread.list);
711 wake_up_process(tsk);
712 put_task_struct(tsk);
713 } else {
714 /* Completion interrupt was faster than initial
715 * interrupt. Set pfault_wait to -1 so the initial
716 * interrupt doesn't put the task to sleep.
717 * If the task is not running, ignore the completion
718 * interrupt since it must be a leftover of a PFAULT
719 * CANCEL operation which didn't remove all pending
720 * completion interrupts. */
721 if (tsk->state == TASK_RUNNING)
722 tsk->thread.pfault_wait = -1;
723 }
724 } else {
725 /* signal bit not set -> a real page is missing. */
726 if (WARN_ON_ONCE(tsk != current))
727 goto out;
728 if (tsk->thread.pfault_wait == 1) {
729 /* Already on the list with a reference: put to sleep */
730 goto block;
731 } else if (tsk->thread.pfault_wait == -1) {
732 /* Completion interrupt was faster than the initial
733 * interrupt (pfault_wait == -1). Set pfault_wait
734 * back to zero and exit. */
735 tsk->thread.pfault_wait = 0;
736 } else {
737 /* Initial interrupt arrived before completion
738 * interrupt. Let the task sleep.
739 * An extra task reference is needed since a different
740 * cpu may set the task state to TASK_RUNNING again
741 * before the scheduler is reached. */
742 get_task_struct(tsk);
743 tsk->thread.pfault_wait = 1;
744 list_add(&tsk->thread.list, &pfault_list);
745 block:
746 /* Since this must be a userspace fault, there
747 * is no kernel task state to trample. Rely on the
748 * return to userspace schedule() to block. */
749 __set_current_state(TASK_UNINTERRUPTIBLE);
750 set_tsk_need_resched(tsk);
751 set_preempt_need_resched();
752 }
753 }
754 out:
755 spin_unlock(&pfault_lock);
756 put_task_struct(tsk);
757 }
758
pfault_cpu_dead(unsigned int cpu)759 static int pfault_cpu_dead(unsigned int cpu)
760 {
761 struct thread_struct *thread, *next;
762 struct task_struct *tsk;
763
764 spin_lock_irq(&pfault_lock);
765 list_for_each_entry_safe(thread, next, &pfault_list, list) {
766 thread->pfault_wait = 0;
767 list_del(&thread->list);
768 tsk = container_of(thread, struct task_struct, thread);
769 wake_up_process(tsk);
770 put_task_struct(tsk);
771 }
772 spin_unlock_irq(&pfault_lock);
773 return 0;
774 }
775
pfault_irq_init(void)776 static int __init pfault_irq_init(void)
777 {
778 int rc;
779
780 rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt);
781 if (rc)
782 goto out_extint;
783 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP;
784 if (rc)
785 goto out_pfault;
786 irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL);
787 cpuhp_setup_state_nocalls(CPUHP_S390_PFAULT_DEAD, "s390/pfault:dead",
788 NULL, pfault_cpu_dead);
789 return 0;
790
791 out_pfault:
792 unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt);
793 out_extint:
794 pfault_disable = 1;
795 return rc;
796 }
797 early_initcall(pfault_irq_init);
798
799 #endif /* CONFIG_PFAULT */
800
801 #if IS_ENABLED(CONFIG_PGSTE)
do_secure_storage_access(struct pt_regs * regs)802 void do_secure_storage_access(struct pt_regs *regs)
803 {
804 unsigned long addr = regs->int_parm_long & __FAIL_ADDR_MASK;
805 struct vm_area_struct *vma;
806 struct mm_struct *mm;
807 struct page *page;
808 int rc;
809
810 /*
811 * bit 61 tells us if the address is valid, if it's not we
812 * have a major problem and should stop the kernel or send a
813 * SIGSEGV to the process. Unfortunately bit 61 is not
814 * reliable without the misc UV feature so we need to check
815 * for that as well.
816 */
817 if (test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications) &&
818 !test_bit_inv(61, ®s->int_parm_long)) {
819 /*
820 * When this happens, userspace did something that it
821 * was not supposed to do, e.g. branching into secure
822 * memory. Trigger a segmentation fault.
823 */
824 if (user_mode(regs)) {
825 send_sig(SIGSEGV, current, 0);
826 return;
827 }
828
829 /*
830 * The kernel should never run into this case and we
831 * have no way out of this situation.
832 */
833 panic("Unexpected PGM 0x3d with TEID bit 61=0");
834 }
835
836 switch (get_fault_type(regs)) {
837 case USER_FAULT:
838 mm = current->mm;
839 mmap_read_lock(mm);
840 vma = find_vma(mm, addr);
841 if (!vma) {
842 mmap_read_unlock(mm);
843 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP);
844 break;
845 }
846 page = follow_page(vma, addr, FOLL_WRITE | FOLL_GET);
847 if (IS_ERR_OR_NULL(page)) {
848 mmap_read_unlock(mm);
849 break;
850 }
851 if (arch_make_page_accessible(page))
852 send_sig(SIGSEGV, current, 0);
853 put_page(page);
854 mmap_read_unlock(mm);
855 break;
856 case KERNEL_FAULT:
857 page = phys_to_page(addr);
858 if (unlikely(!try_get_page(page)))
859 break;
860 rc = arch_make_page_accessible(page);
861 put_page(page);
862 if (rc)
863 BUG();
864 break;
865 case VDSO_FAULT:
866 case GMAP_FAULT:
867 default:
868 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP);
869 WARN_ON_ONCE(1);
870 }
871 }
872 NOKPROBE_SYMBOL(do_secure_storage_access);
873
do_non_secure_storage_access(struct pt_regs * regs)874 void do_non_secure_storage_access(struct pt_regs *regs)
875 {
876 unsigned long gaddr = regs->int_parm_long & __FAIL_ADDR_MASK;
877 struct gmap *gmap = (struct gmap *)S390_lowcore.gmap;
878
879 if (get_fault_type(regs) != GMAP_FAULT) {
880 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP);
881 WARN_ON_ONCE(1);
882 return;
883 }
884
885 if (gmap_convert_to_secure(gmap, gaddr) == -EINVAL)
886 send_sig(SIGSEGV, current, 0);
887 }
888 NOKPROBE_SYMBOL(do_non_secure_storage_access);
889
do_secure_storage_violation(struct pt_regs * regs)890 void do_secure_storage_violation(struct pt_regs *regs)
891 {
892 /*
893 * Either KVM messed up the secure guest mapping or the same
894 * page is mapped into multiple secure guests.
895 *
896 * This exception is only triggered when a guest 2 is running
897 * and can therefore never occur in kernel context.
898 */
899 printk_ratelimited(KERN_WARNING
900 "Secure storage violation in task: %s, pid %d\n",
901 current->comm, current->pid);
902 send_sig(SIGSEGV, current, 0);
903 }
904
905 #else
do_secure_storage_access(struct pt_regs * regs)906 void do_secure_storage_access(struct pt_regs *regs)
907 {
908 default_trap_handler(regs);
909 }
910
do_non_secure_storage_access(struct pt_regs * regs)911 void do_non_secure_storage_access(struct pt_regs *regs)
912 {
913 default_trap_handler(regs);
914 }
915
do_secure_storage_violation(struct pt_regs * regs)916 void do_secure_storage_violation(struct pt_regs *regs)
917 {
918 default_trap_handler(regs);
919 }
920 #endif
921