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1/*
2 * arch/s390/mm/fault.c
3 *
4 * S390 version
5 * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
6 * Author(s): Hartmut Penner (hp@de.ibm.com)
7 * Ulrich Weigand (uweigand@de.ibm.com)
8 *
9 * Derived from "arch/i386/mm/fault.c"
10 * Copyright (C) 1995 Linus Torvalds
11 */
12
13#include <linux/kernel_stat.h>
14#include <linux/perf_event.h>
15#include <linux/signal.h>
16#include <linux/sched.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/module.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/system.h>
36#include <asm/pgtable.h>
37#include <asm/irq.h>
38#include <asm/mmu_context.h>
39#include <asm/compat.h>
40#include "../kernel/entry.h"
41
42#ifndef CONFIG_64BIT
43#define __FAIL_ADDR_MASK 0x7ffff000
44#define __SUBCODE_MASK 0x0200
45#define __PF_RES_FIELD 0ULL
46#else /* CONFIG_64BIT */
47#define __FAIL_ADDR_MASK -4096L
48#define __SUBCODE_MASK 0x0600
49#define __PF_RES_FIELD 0x8000000000000000ULL
50#endif /* CONFIG_64BIT */
51
52#define VM_FAULT_BADCONTEXT 0x010000
53#define VM_FAULT_BADMAP 0x020000
54#define VM_FAULT_BADACCESS 0x040000
55
56static unsigned long store_indication;
57
58void fault_init(void)
59{
60 if (test_facility(2) && test_facility(75))
61 store_indication = 0xc00;
62}
63
64static inline int notify_page_fault(struct pt_regs *regs)
65{
66 int ret = 0;
67
68 /* kprobe_running() needs smp_processor_id() */
69 if (kprobes_built_in() && !user_mode(regs)) {
70 preempt_disable();
71 if (kprobe_running() && kprobe_fault_handler(regs, 14))
72 ret = 1;
73 preempt_enable();
74 }
75 return ret;
76}
77
78
79/*
80 * Unlock any spinlocks which will prevent us from getting the
81 * message out.
82 */
83void bust_spinlocks(int yes)
84{
85 if (yes) {
86 oops_in_progress = 1;
87 } else {
88 int loglevel_save = console_loglevel;
89 console_unblank();
90 oops_in_progress = 0;
91 /*
92 * OK, the message is on the console. Now we call printk()
93 * without oops_in_progress set so that printk will give klogd
94 * a poke. Hold onto your hats...
95 */
96 console_loglevel = 15;
97 printk(" ");
98 console_loglevel = loglevel_save;
99 }
100}
101
102/*
103 * Returns the address space associated with the fault.
104 * Returns 0 for kernel space and 1 for user space.
105 */
106static inline int user_space_fault(unsigned long trans_exc_code)
107{
108 /*
109 * The lowest two bits of the translation exception
110 * identification indicate which paging table was used.
111 */
112 trans_exc_code &= 3;
113 if (trans_exc_code == 2)
114 /* Access via secondary space, set_fs setting decides */
115 return current->thread.mm_segment.ar4;
116 if (user_mode == HOME_SPACE_MODE)
117 /* User space if the access has been done via home space. */
118 return trans_exc_code == 3;
119 /*
120 * If the user space is not the home space the kernel runs in home
121 * space. Access via secondary space has already been covered,
122 * access via primary space or access register is from user space
123 * and access via home space is from the kernel.
124 */
125 return trans_exc_code != 3;
126}
127
128static inline void report_user_fault(struct pt_regs *regs, long int_code,
129 int signr, unsigned long address)
130{
131 if ((task_pid_nr(current) > 1) && !show_unhandled_signals)
132 return;
133 if (!unhandled_signal(current, signr))
134 return;
135 if (!printk_ratelimit())
136 return;
137 printk("User process fault: interruption code 0x%lX ", int_code);
138 print_vma_addr(KERN_CONT "in ", regs->psw.addr & PSW_ADDR_INSN);
139 printk("\n");
140 printk("failing address: %lX\n", address);
141 show_regs(regs);
142}
143
144/*
145 * Send SIGSEGV to task. This is an external routine
146 * to keep the stack usage of do_page_fault small.
147 */
148static noinline void do_sigsegv(struct pt_regs *regs, long int_code,
149 int si_code, unsigned long trans_exc_code)
150{
151 struct siginfo si;
152 unsigned long address;
153
154 address = trans_exc_code & __FAIL_ADDR_MASK;
155 current->thread.prot_addr = address;
156 current->thread.trap_no = int_code;
157 report_user_fault(regs, int_code, SIGSEGV, address);
158 si.si_signo = SIGSEGV;
159 si.si_code = si_code;
160 si.si_addr = (void __user *) address;
161 force_sig_info(SIGSEGV, &si, current);
162}
163
164static noinline void do_no_context(struct pt_regs *regs, long int_code,
165 unsigned long trans_exc_code)
166{
167 const struct exception_table_entry *fixup;
168 unsigned long address;
169
170 /* Are we prepared to handle this kernel fault? */
171 fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
172 if (fixup) {
173 regs->psw.addr = fixup->fixup | PSW_ADDR_AMODE;
174 return;
175 }
176
177 /*
178 * Oops. The kernel tried to access some bad page. We'll have to
179 * terminate things with extreme prejudice.
180 */
181 address = trans_exc_code & __FAIL_ADDR_MASK;
182 if (!user_space_fault(trans_exc_code))
183 printk(KERN_ALERT "Unable to handle kernel pointer dereference"
184 " at virtual kernel address %p\n", (void *)address);
185 else
186 printk(KERN_ALERT "Unable to handle kernel paging request"
187 " at virtual user address %p\n", (void *)address);
188
189 die("Oops", regs, int_code);
190 do_exit(SIGKILL);
191}
192
193static noinline void do_low_address(struct pt_regs *regs, long int_code,
194 unsigned long trans_exc_code)
195{
196 /* Low-address protection hit in kernel mode means
197 NULL pointer write access in kernel mode. */
198 if (regs->psw.mask & PSW_MASK_PSTATE) {
199 /* Low-address protection hit in user mode 'cannot happen'. */
200 die ("Low-address protection", regs, int_code);
201 do_exit(SIGKILL);
202 }
203
204 do_no_context(regs, int_code, trans_exc_code);
205}
206
207static noinline void do_sigbus(struct pt_regs *regs, long int_code,
208 unsigned long trans_exc_code)
209{
210 struct task_struct *tsk = current;
211 unsigned long address;
212 struct siginfo si;
213
214 /*
215 * Send a sigbus, regardless of whether we were in kernel
216 * or user mode.
217 */
218 address = trans_exc_code & __FAIL_ADDR_MASK;
219 tsk->thread.prot_addr = address;
220 tsk->thread.trap_no = int_code;
221 si.si_signo = SIGBUS;
222 si.si_errno = 0;
223 si.si_code = BUS_ADRERR;
224 si.si_addr = (void __user *) address;
225 force_sig_info(SIGBUS, &si, tsk);
226}
227
228static noinline void do_fault_error(struct pt_regs *regs, long int_code,
229 unsigned long trans_exc_code, int fault)
230{
231 int si_code;
232
233 switch (fault) {
234 case VM_FAULT_BADACCESS:
235 case VM_FAULT_BADMAP:
236 /* Bad memory access. Check if it is kernel or user space. */
237 if (regs->psw.mask & PSW_MASK_PSTATE) {
238 /* User mode accesses just cause a SIGSEGV */
239 si_code = (fault == VM_FAULT_BADMAP) ?
240 SEGV_MAPERR : SEGV_ACCERR;
241 do_sigsegv(regs, int_code, si_code, trans_exc_code);
242 return;
243 }
244 case VM_FAULT_BADCONTEXT:
245 do_no_context(regs, int_code, trans_exc_code);
246 break;
247 default: /* fault & VM_FAULT_ERROR */
248 if (fault & VM_FAULT_OOM) {
249 if (!(regs->psw.mask & PSW_MASK_PSTATE))
250 do_no_context(regs, int_code, trans_exc_code);
251 else
252 pagefault_out_of_memory();
253 } else if (fault & VM_FAULT_SIGBUS) {
254 /* Kernel mode? Handle exceptions or die */
255 if (!(regs->psw.mask & PSW_MASK_PSTATE))
256 do_no_context(regs, int_code, trans_exc_code);
257 else
258 do_sigbus(regs, int_code, trans_exc_code);
259 } else
260 BUG();
261 break;
262 }
263}
264
265/*
266 * This routine handles page faults. It determines the address,
267 * and the problem, and then passes it off to one of the appropriate
268 * routines.
269 *
270 * interruption code (int_code):
271 * 04 Protection -> Write-Protection (suprression)
272 * 10 Segment translation -> Not present (nullification)
273 * 11 Page translation -> Not present (nullification)
274 * 3b Region third trans. -> Not present (nullification)
275 */
276static inline int do_exception(struct pt_regs *regs, int access,
277 unsigned long trans_exc_code)
278{
279 struct task_struct *tsk;
280 struct mm_struct *mm;
281 struct vm_area_struct *vma;
282 unsigned long address;
283 unsigned int flags;
284 int fault;
285
286 if (notify_page_fault(regs))
287 return 0;
288
289 tsk = current;
290 mm = tsk->mm;
291
292 /*
293 * Verify that the fault happened in user space, that
294 * we are not in an interrupt and that there is a
295 * user context.
296 */
297 fault = VM_FAULT_BADCONTEXT;
298 if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm))
299 goto out;
300
301 address = trans_exc_code & __FAIL_ADDR_MASK;
302 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
303 flags = FAULT_FLAG_ALLOW_RETRY;
304 if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
305 flags |= FAULT_FLAG_WRITE;
306 down_read(&mm->mmap_sem);
307
308#ifdef CONFIG_PGSTE
309 if (test_tsk_thread_flag(current, TIF_SIE) && S390_lowcore.gmap) {
310 address = gmap_fault(address,
311 (struct gmap *) S390_lowcore.gmap);
312 if (address == -EFAULT) {
313 fault = VM_FAULT_BADMAP;
314 goto out_up;
315 }
316 if (address == -ENOMEM) {
317 fault = VM_FAULT_OOM;
318 goto out_up;
319 }
320 }
321#endif
322
323retry:
324 fault = VM_FAULT_BADMAP;
325 vma = find_vma(mm, address);
326 if (!vma)
327 goto out_up;
328
329 if (unlikely(vma->vm_start > address)) {
330 if (!(vma->vm_flags & VM_GROWSDOWN))
331 goto out_up;
332 if (expand_stack(vma, address))
333 goto out_up;
334 }
335
336 /*
337 * Ok, we have a good vm_area for this memory access, so
338 * we can handle it..
339 */
340 fault = VM_FAULT_BADACCESS;
341 if (unlikely(!(vma->vm_flags & access)))
342 goto out_up;
343
344 if (is_vm_hugetlb_page(vma))
345 address &= HPAGE_MASK;
346 /*
347 * If for any reason at all we couldn't handle the fault,
348 * make sure we exit gracefully rather than endlessly redo
349 * the fault.
350 */
351 fault = handle_mm_fault(mm, vma, address, flags);
352 if (unlikely(fault & VM_FAULT_ERROR))
353 goto out_up;
354
355 /*
356 * Major/minor page fault accounting is only done on the
357 * initial attempt. If we go through a retry, it is extremely
358 * likely that the page will be found in page cache at that point.
359 */
360 if (flags & FAULT_FLAG_ALLOW_RETRY) {
361 if (fault & VM_FAULT_MAJOR) {
362 tsk->maj_flt++;
363 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
364 regs, address);
365 } else {
366 tsk->min_flt++;
367 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
368 regs, address);
369 }
370 if (fault & VM_FAULT_RETRY) {
371 /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
372 * of starvation. */
373 flags &= ~FAULT_FLAG_ALLOW_RETRY;
374 down_read(&mm->mmap_sem);
375 goto retry;
376 }
377 }
378 /*
379 * The instruction that caused the program check will
380 * be repeated. Don't signal single step via SIGTRAP.
381 */
382 clear_tsk_thread_flag(tsk, TIF_PER_TRAP);
383 fault = 0;
384out_up:
385 up_read(&mm->mmap_sem);
386out:
387 return fault;
388}
389
390void __kprobes do_protection_exception(struct pt_regs *regs, long pgm_int_code,
391 unsigned long trans_exc_code)
392{
393 int fault;
394
395 /* Protection exception is suppressing, decrement psw address. */
396 regs->psw.addr -= (pgm_int_code >> 16);
397 /*
398 * Check for low-address protection. This needs to be treated
399 * as a special case because the translation exception code
400 * field is not guaranteed to contain valid data in this case.
401 */
402 if (unlikely(!(trans_exc_code & 4))) {
403 do_low_address(regs, pgm_int_code, trans_exc_code);
404 return;
405 }
406 fault = do_exception(regs, VM_WRITE, trans_exc_code);
407 if (unlikely(fault))
408 do_fault_error(regs, 4, trans_exc_code, fault);
409}
410
411void __kprobes do_dat_exception(struct pt_regs *regs, long pgm_int_code,
412 unsigned long trans_exc_code)
413{
414 int access, fault;
415
416 access = VM_READ | VM_EXEC | VM_WRITE;
417 fault = do_exception(regs, access, trans_exc_code);
418 if (unlikely(fault))
419 do_fault_error(regs, pgm_int_code & 255, trans_exc_code, fault);
420}
421
422#ifdef CONFIG_64BIT
423void __kprobes do_asce_exception(struct pt_regs *regs, long pgm_int_code,
424 unsigned long trans_exc_code)
425{
426 struct mm_struct *mm = current->mm;
427 struct vm_area_struct *vma;
428
429 if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm))
430 goto no_context;
431
432 down_read(&mm->mmap_sem);
433 vma = find_vma(mm, trans_exc_code & __FAIL_ADDR_MASK);
434 up_read(&mm->mmap_sem);
435
436 if (vma) {
437 update_mm(mm, current);
438 return;
439 }
440
441 /* User mode accesses just cause a SIGSEGV */
442 if (regs->psw.mask & PSW_MASK_PSTATE) {
443 do_sigsegv(regs, pgm_int_code, SEGV_MAPERR, trans_exc_code);
444 return;
445 }
446
447no_context:
448 do_no_context(regs, pgm_int_code, trans_exc_code);
449}
450#endif
451
452int __handle_fault(unsigned long uaddr, unsigned long pgm_int_code, int write)
453{
454 struct pt_regs regs;
455 int access, fault;
456
457 regs.psw.mask = psw_kernel_bits;
458 if (!irqs_disabled())
459 regs.psw.mask |= PSW_MASK_IO | PSW_MASK_EXT;
460 regs.psw.addr = (unsigned long) __builtin_return_address(0);
461 regs.psw.addr |= PSW_ADDR_AMODE;
462 uaddr &= PAGE_MASK;
463 access = write ? VM_WRITE : VM_READ;
464 fault = do_exception(®s, access, uaddr | 2);
465 if (unlikely(fault)) {
466 if (fault & VM_FAULT_OOM)
467 return -EFAULT;
468 else if (fault & VM_FAULT_SIGBUS)
469 do_sigbus(®s, pgm_int_code, uaddr);
470 }
471 return fault ? -EFAULT : 0;
472}
473
474#ifdef CONFIG_PFAULT
475/*
476 * 'pfault' pseudo page faults routines.
477 */
478static int pfault_disable;
479
480static int __init nopfault(char *str)
481{
482 pfault_disable = 1;
483 return 1;
484}
485
486__setup("nopfault", nopfault);
487
488struct pfault_refbk {
489 u16 refdiagc;
490 u16 reffcode;
491 u16 refdwlen;
492 u16 refversn;
493 u64 refgaddr;
494 u64 refselmk;
495 u64 refcmpmk;
496 u64 reserved;
497} __attribute__ ((packed, aligned(8)));
498
499int pfault_init(void)
500{
501 struct pfault_refbk refbk = {
502 .refdiagc = 0x258,
503 .reffcode = 0,
504 .refdwlen = 5,
505 .refversn = 2,
506 .refgaddr = __LC_CURRENT_PID,
507 .refselmk = 1ULL << 48,
508 .refcmpmk = 1ULL << 48,
509 .reserved = __PF_RES_FIELD };
510 int rc;
511
512 if (!MACHINE_IS_VM || pfault_disable)
513 return -1;
514 asm volatile(
515 " diag %1,%0,0x258\n"
516 "0: j 2f\n"
517 "1: la %0,8\n"
518 "2:\n"
519 EX_TABLE(0b,1b)
520 : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc");
521 return rc;
522}
523
524void pfault_fini(void)
525{
526 struct pfault_refbk refbk = {
527 .refdiagc = 0x258,
528 .reffcode = 1,
529 .refdwlen = 5,
530 .refversn = 2,
531 };
532
533 if (!MACHINE_IS_VM || pfault_disable)
534 return;
535 asm volatile(
536 " diag %0,0,0x258\n"
537 "0:\n"
538 EX_TABLE(0b,0b)
539 : : "a" (&refbk), "m" (refbk) : "cc");
540}
541
542static DEFINE_SPINLOCK(pfault_lock);
543static LIST_HEAD(pfault_list);
544
545static void pfault_interrupt(unsigned int ext_int_code,
546 unsigned int param32, unsigned long param64)
547{
548 struct task_struct *tsk;
549 __u16 subcode;
550 pid_t pid;
551
552 /*
553 * Get the external interruption subcode & pfault
554 * initial/completion signal bit. VM stores this
555 * in the 'cpu address' field associated with the
556 * external interrupt.
557 */
558 subcode = ext_int_code >> 16;
559 if ((subcode & 0xff00) != __SUBCODE_MASK)
560 return;
561 kstat_cpu(smp_processor_id()).irqs[EXTINT_PFL]++;
562 if (subcode & 0x0080) {
563 /* Get the token (= pid of the affected task). */
564 pid = sizeof(void *) == 4 ? param32 : param64;
565 rcu_read_lock();
566 tsk = find_task_by_pid_ns(pid, &init_pid_ns);
567 if (tsk)
568 get_task_struct(tsk);
569 rcu_read_unlock();
570 if (!tsk)
571 return;
572 } else {
573 tsk = current;
574 }
575 spin_lock(&pfault_lock);
576 if (subcode & 0x0080) {
577 /* signal bit is set -> a page has been swapped in by VM */
578 if (tsk->thread.pfault_wait == 1) {
579 /* Initial interrupt was faster than the completion
580 * interrupt. pfault_wait is valid. Set pfault_wait
581 * back to zero and wake up the process. This can
582 * safely be done because the task is still sleeping
583 * and can't produce new pfaults. */
584 tsk->thread.pfault_wait = 0;
585 list_del(&tsk->thread.list);
586 wake_up_process(tsk);
587 } else {
588 /* Completion interrupt was faster than initial
589 * interrupt. Set pfault_wait to -1 so the initial
590 * interrupt doesn't put the task to sleep. */
591 tsk->thread.pfault_wait = -1;
592 }
593 put_task_struct(tsk);
594 } else {
595 /* signal bit not set -> a real page is missing. */
596 if (tsk->thread.pfault_wait == -1) {
597 /* Completion interrupt was faster than the initial
598 * interrupt (pfault_wait == -1). Set pfault_wait
599 * back to zero and exit. */
600 tsk->thread.pfault_wait = 0;
601 } else {
602 /* Initial interrupt arrived before completion
603 * interrupt. Let the task sleep. */
604 tsk->thread.pfault_wait = 1;
605 list_add(&tsk->thread.list, &pfault_list);
606 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
607 set_tsk_need_resched(tsk);
608 }
609 }
610 spin_unlock(&pfault_lock);
611}
612
613static int __cpuinit pfault_cpu_notify(struct notifier_block *self,
614 unsigned long action, void *hcpu)
615{
616 struct thread_struct *thread, *next;
617 struct task_struct *tsk;
618
619 switch (action) {
620 case CPU_DEAD:
621 case CPU_DEAD_FROZEN:
622 spin_lock_irq(&pfault_lock);
623 list_for_each_entry_safe(thread, next, &pfault_list, list) {
624 thread->pfault_wait = 0;
625 list_del(&thread->list);
626 tsk = container_of(thread, struct task_struct, thread);
627 wake_up_process(tsk);
628 }
629 spin_unlock_irq(&pfault_lock);
630 break;
631 default:
632 break;
633 }
634 return NOTIFY_OK;
635}
636
637static int __init pfault_irq_init(void)
638{
639 int rc;
640
641 if (!MACHINE_IS_VM)
642 return 0;
643 rc = register_external_interrupt(0x2603, pfault_interrupt);
644 if (rc)
645 goto out_extint;
646 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP;
647 if (rc)
648 goto out_pfault;
649 service_subclass_irq_register();
650 hotcpu_notifier(pfault_cpu_notify, 0);
651 return 0;
652
653out_pfault:
654 unregister_external_interrupt(0x2603, pfault_interrupt);
655out_extint:
656 pfault_disable = 1;
657 return rc;
658}
659early_initcall(pfault_irq_init);
660
661#endif /* CONFIG_PFAULT */
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
53enum fault_type {
54 KERNEL_FAULT,
55 USER_FAULT,
56 GMAP_FAULT,
57};
58
59static unsigned long store_indication __read_mostly;
60
61static int __init fault_init(void)
62{
63 if (test_facility(75))
64 store_indication = 0xc00;
65 return 0;
66}
67early_initcall(fault_init);
68
69/*
70 * Find out which address space caused the exception.
71 */
72static enum fault_type get_fault_type(struct pt_regs *regs)
73{
74 unsigned long trans_exc_code;
75
76 trans_exc_code = regs->int_parm_long & 3;
77 if (likely(trans_exc_code == 0)) {
78 /* primary space exception */
79 if (user_mode(regs))
80 return USER_FAULT;
81 if (!IS_ENABLED(CONFIG_PGSTE))
82 return KERNEL_FAULT;
83 if (test_pt_regs_flag(regs, PIF_GUEST_FAULT))
84 return GMAP_FAULT;
85 return KERNEL_FAULT;
86 }
87 if (trans_exc_code == 2)
88 return USER_FAULT;
89 if (trans_exc_code == 1) {
90 /* access register mode, not used in the kernel */
91 return USER_FAULT;
92 }
93 /* home space exception -> access via kernel ASCE */
94 return KERNEL_FAULT;
95}
96
97static int bad_address(void *p)
98{
99 unsigned long dummy;
100
101 return get_kernel_nofault(dummy, (unsigned long *)p);
102}
103
104static void dump_pagetable(unsigned long asce, unsigned long address)
105{
106 unsigned long *table = __va(asce & _ASCE_ORIGIN);
107
108 pr_alert("AS:%016lx ", asce);
109 switch (asce & _ASCE_TYPE_MASK) {
110 case _ASCE_TYPE_REGION1:
111 table += (address & _REGION1_INDEX) >> _REGION1_SHIFT;
112 if (bad_address(table))
113 goto bad;
114 pr_cont("R1:%016lx ", *table);
115 if (*table & _REGION_ENTRY_INVALID)
116 goto out;
117 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
118 fallthrough;
119 case _ASCE_TYPE_REGION2:
120 table += (address & _REGION2_INDEX) >> _REGION2_SHIFT;
121 if (bad_address(table))
122 goto bad;
123 pr_cont("R2:%016lx ", *table);
124 if (*table & _REGION_ENTRY_INVALID)
125 goto out;
126 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
127 fallthrough;
128 case _ASCE_TYPE_REGION3:
129 table += (address & _REGION3_INDEX) >> _REGION3_SHIFT;
130 if (bad_address(table))
131 goto bad;
132 pr_cont("R3:%016lx ", *table);
133 if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE))
134 goto out;
135 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
136 fallthrough;
137 case _ASCE_TYPE_SEGMENT:
138 table += (address & _SEGMENT_INDEX) >> _SEGMENT_SHIFT;
139 if (bad_address(table))
140 goto bad;
141 pr_cont("S:%016lx ", *table);
142 if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE))
143 goto out;
144 table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
145 }
146 table += (address & _PAGE_INDEX) >> _PAGE_SHIFT;
147 if (bad_address(table))
148 goto bad;
149 pr_cont("P:%016lx ", *table);
150out:
151 pr_cont("\n");
152 return;
153bad:
154 pr_cont("BAD\n");
155}
156
157static void dump_fault_info(struct pt_regs *regs)
158{
159 unsigned long asce;
160
161 pr_alert("Failing address: %016lx TEID: %016lx\n",
162 regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long);
163 pr_alert("Fault in ");
164 switch (regs->int_parm_long & 3) {
165 case 3:
166 pr_cont("home space ");
167 break;
168 case 2:
169 pr_cont("secondary space ");
170 break;
171 case 1:
172 pr_cont("access register ");
173 break;
174 case 0:
175 pr_cont("primary space ");
176 break;
177 }
178 pr_cont("mode while using ");
179 switch (get_fault_type(regs)) {
180 case USER_FAULT:
181 asce = S390_lowcore.user_asce;
182 pr_cont("user ");
183 break;
184 case GMAP_FAULT:
185 asce = ((struct gmap *) S390_lowcore.gmap)->asce;
186 pr_cont("gmap ");
187 break;
188 case KERNEL_FAULT:
189 asce = S390_lowcore.kernel_asce;
190 pr_cont("kernel ");
191 break;
192 default:
193 unreachable();
194 }
195 pr_cont("ASCE.\n");
196 dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK);
197}
198
199int show_unhandled_signals = 1;
200
201void report_user_fault(struct pt_regs *regs, long signr, int is_mm_fault)
202{
203 if ((task_pid_nr(current) > 1) && !show_unhandled_signals)
204 return;
205 if (!unhandled_signal(current, signr))
206 return;
207 if (!printk_ratelimit())
208 return;
209 printk(KERN_ALERT "User process fault: interruption code %04x ilc:%d ",
210 regs->int_code & 0xffff, regs->int_code >> 17);
211 print_vma_addr(KERN_CONT "in ", regs->psw.addr);
212 printk(KERN_CONT "\n");
213 if (is_mm_fault)
214 dump_fault_info(regs);
215 show_regs(regs);
216}
217
218/*
219 * Send SIGSEGV to task. This is an external routine
220 * to keep the stack usage of do_page_fault small.
221 */
222static noinline void do_sigsegv(struct pt_regs *regs, int si_code)
223{
224 report_user_fault(regs, SIGSEGV, 1);
225 force_sig_fault(SIGSEGV, si_code,
226 (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK));
227}
228
229const struct exception_table_entry *s390_search_extables(unsigned long addr)
230{
231 const struct exception_table_entry *fixup;
232
233 fixup = search_extable(__start_dma_ex_table,
234 __stop_dma_ex_table - __start_dma_ex_table,
235 addr);
236 if (!fixup)
237 fixup = search_exception_tables(addr);
238 return fixup;
239}
240
241static noinline void do_no_context(struct pt_regs *regs)
242{
243 const struct exception_table_entry *fixup;
244
245 /* Are we prepared to handle this kernel fault? */
246 fixup = s390_search_extables(regs->psw.addr);
247 if (fixup && ex_handle(fixup, regs))
248 return;
249
250 /*
251 * Oops. The kernel tried to access some bad page. We'll have to
252 * terminate things with extreme prejudice.
253 */
254 if (get_fault_type(regs) == KERNEL_FAULT)
255 printk(KERN_ALERT "Unable to handle kernel pointer dereference"
256 " in virtual kernel address space\n");
257 else
258 printk(KERN_ALERT "Unable to handle kernel paging request"
259 " in virtual user address space\n");
260 dump_fault_info(regs);
261 die(regs, "Oops");
262 do_exit(SIGKILL);
263}
264
265static noinline void do_low_address(struct pt_regs *regs)
266{
267 /* Low-address protection hit in kernel mode means
268 NULL pointer write access in kernel mode. */
269 if (regs->psw.mask & PSW_MASK_PSTATE) {
270 /* Low-address protection hit in user mode 'cannot happen'. */
271 die (regs, "Low-address protection");
272 do_exit(SIGKILL);
273 }
274
275 do_no_context(regs);
276}
277
278static noinline void do_sigbus(struct pt_regs *regs)
279{
280 /*
281 * Send a sigbus, regardless of whether we were in kernel
282 * or user mode.
283 */
284 force_sig_fault(SIGBUS, BUS_ADRERR,
285 (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK));
286}
287
288static noinline void do_fault_error(struct pt_regs *regs, int access,
289 vm_fault_t fault)
290{
291 int si_code;
292
293 switch (fault) {
294 case VM_FAULT_BADACCESS:
295 case VM_FAULT_BADMAP:
296 /* Bad memory access. Check if it is kernel or user space. */
297 if (user_mode(regs)) {
298 /* User mode accesses just cause a SIGSEGV */
299 si_code = (fault == VM_FAULT_BADMAP) ?
300 SEGV_MAPERR : SEGV_ACCERR;
301 do_sigsegv(regs, si_code);
302 break;
303 }
304 fallthrough;
305 case VM_FAULT_BADCONTEXT:
306 case VM_FAULT_PFAULT:
307 do_no_context(regs);
308 break;
309 case VM_FAULT_SIGNAL:
310 if (!user_mode(regs))
311 do_no_context(regs);
312 break;
313 default: /* fault & VM_FAULT_ERROR */
314 if (fault & VM_FAULT_OOM) {
315 if (!user_mode(regs))
316 do_no_context(regs);
317 else
318 pagefault_out_of_memory();
319 } else if (fault & VM_FAULT_SIGSEGV) {
320 /* Kernel mode? Handle exceptions or die */
321 if (!user_mode(regs))
322 do_no_context(regs);
323 else
324 do_sigsegv(regs, SEGV_MAPERR);
325 } else if (fault & VM_FAULT_SIGBUS) {
326 /* Kernel mode? Handle exceptions or die */
327 if (!user_mode(regs))
328 do_no_context(regs);
329 else
330 do_sigbus(regs);
331 } else
332 BUG();
333 break;
334 }
335}
336
337/*
338 * This routine handles page faults. It determines the address,
339 * and the problem, and then passes it off to one of the appropriate
340 * routines.
341 *
342 * interruption code (int_code):
343 * 04 Protection -> Write-Protection (suppression)
344 * 10 Segment translation -> Not present (nullification)
345 * 11 Page translation -> Not present (nullification)
346 * 3b Region third trans. -> Not present (nullification)
347 */
348static inline vm_fault_t do_exception(struct pt_regs *regs, int access)
349{
350 struct gmap *gmap;
351 struct task_struct *tsk;
352 struct mm_struct *mm;
353 struct vm_area_struct *vma;
354 enum fault_type type;
355 unsigned long trans_exc_code;
356 unsigned long address;
357 unsigned int flags;
358 vm_fault_t fault;
359
360 tsk = current;
361 /*
362 * The instruction that caused the program check has
363 * been nullified. Don't signal single step via SIGTRAP.
364 */
365 clear_thread_flag(TIF_PER_TRAP);
366
367 if (kprobe_page_fault(regs, 14))
368 return 0;
369
370 mm = tsk->mm;
371 trans_exc_code = regs->int_parm_long;
372
373 /*
374 * Verify that the fault happened in user space, that
375 * we are not in an interrupt and that there is a
376 * user context.
377 */
378 fault = VM_FAULT_BADCONTEXT;
379 type = get_fault_type(regs);
380 switch (type) {
381 case KERNEL_FAULT:
382 goto out;
383 case USER_FAULT:
384 case GMAP_FAULT:
385 if (faulthandler_disabled() || !mm)
386 goto out;
387 break;
388 }
389
390 address = trans_exc_code & __FAIL_ADDR_MASK;
391 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
392 flags = FAULT_FLAG_DEFAULT;
393 if (user_mode(regs))
394 flags |= FAULT_FLAG_USER;
395 if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
396 flags |= FAULT_FLAG_WRITE;
397 mmap_read_lock(mm);
398
399 gmap = NULL;
400 if (IS_ENABLED(CONFIG_PGSTE) && type == GMAP_FAULT) {
401 gmap = (struct gmap *) S390_lowcore.gmap;
402 current->thread.gmap_addr = address;
403 current->thread.gmap_write_flag = !!(flags & FAULT_FLAG_WRITE);
404 current->thread.gmap_int_code = regs->int_code & 0xffff;
405 address = __gmap_translate(gmap, address);
406 if (address == -EFAULT) {
407 fault = VM_FAULT_BADMAP;
408 goto out_up;
409 }
410 if (gmap->pfault_enabled)
411 flags |= FAULT_FLAG_RETRY_NOWAIT;
412 }
413
414retry:
415 fault = VM_FAULT_BADMAP;
416 vma = find_vma(mm, address);
417 if (!vma)
418 goto out_up;
419
420 if (unlikely(vma->vm_start > address)) {
421 if (!(vma->vm_flags & VM_GROWSDOWN))
422 goto out_up;
423 if (expand_stack(vma, address))
424 goto out_up;
425 }
426
427 /*
428 * Ok, we have a good vm_area for this memory access, so
429 * we can handle it..
430 */
431 fault = VM_FAULT_BADACCESS;
432 if (unlikely(!(vma->vm_flags & access)))
433 goto out_up;
434
435 if (is_vm_hugetlb_page(vma))
436 address &= HPAGE_MASK;
437 /*
438 * If for any reason at all we couldn't handle the fault,
439 * make sure we exit gracefully rather than endlessly redo
440 * the fault.
441 */
442 fault = handle_mm_fault(vma, address, flags, regs);
443 if (fault_signal_pending(fault, regs)) {
444 fault = VM_FAULT_SIGNAL;
445 if (flags & FAULT_FLAG_RETRY_NOWAIT)
446 goto out_up;
447 goto out;
448 }
449 if (unlikely(fault & VM_FAULT_ERROR))
450 goto out_up;
451
452 if (flags & FAULT_FLAG_ALLOW_RETRY) {
453 if (fault & VM_FAULT_RETRY) {
454 if (IS_ENABLED(CONFIG_PGSTE) && gmap &&
455 (flags & FAULT_FLAG_RETRY_NOWAIT)) {
456 /* FAULT_FLAG_RETRY_NOWAIT has been set,
457 * mmap_lock has not been released */
458 current->thread.gmap_pfault = 1;
459 fault = VM_FAULT_PFAULT;
460 goto out_up;
461 }
462 flags &= ~FAULT_FLAG_RETRY_NOWAIT;
463 flags |= FAULT_FLAG_TRIED;
464 mmap_read_lock(mm);
465 goto retry;
466 }
467 }
468 if (IS_ENABLED(CONFIG_PGSTE) && gmap) {
469 address = __gmap_link(gmap, current->thread.gmap_addr,
470 address);
471 if (address == -EFAULT) {
472 fault = VM_FAULT_BADMAP;
473 goto out_up;
474 }
475 if (address == -ENOMEM) {
476 fault = VM_FAULT_OOM;
477 goto out_up;
478 }
479 }
480 fault = 0;
481out_up:
482 mmap_read_unlock(mm);
483out:
484 return fault;
485}
486
487void do_protection_exception(struct pt_regs *regs)
488{
489 unsigned long trans_exc_code;
490 int access;
491 vm_fault_t fault;
492
493 trans_exc_code = regs->int_parm_long;
494 /*
495 * Protection exceptions are suppressing, decrement psw address.
496 * The exception to this rule are aborted transactions, for these
497 * the PSW already points to the correct location.
498 */
499 if (!(regs->int_code & 0x200))
500 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
501 /*
502 * Check for low-address protection. This needs to be treated
503 * as a special case because the translation exception code
504 * field is not guaranteed to contain valid data in this case.
505 */
506 if (unlikely(!(trans_exc_code & 4))) {
507 do_low_address(regs);
508 return;
509 }
510 if (unlikely(MACHINE_HAS_NX && (trans_exc_code & 0x80))) {
511 regs->int_parm_long = (trans_exc_code & ~PAGE_MASK) |
512 (regs->psw.addr & PAGE_MASK);
513 access = VM_EXEC;
514 fault = VM_FAULT_BADACCESS;
515 } else {
516 access = VM_WRITE;
517 fault = do_exception(regs, access);
518 }
519 if (unlikely(fault))
520 do_fault_error(regs, access, fault);
521}
522NOKPROBE_SYMBOL(do_protection_exception);
523
524void do_dat_exception(struct pt_regs *regs)
525{
526 int access;
527 vm_fault_t fault;
528
529 access = VM_ACCESS_FLAGS;
530 fault = do_exception(regs, access);
531 if (unlikely(fault))
532 do_fault_error(regs, access, fault);
533}
534NOKPROBE_SYMBOL(do_dat_exception);
535
536#ifdef CONFIG_PFAULT
537/*
538 * 'pfault' pseudo page faults routines.
539 */
540static int pfault_disable;
541
542static int __init nopfault(char *str)
543{
544 pfault_disable = 1;
545 return 1;
546}
547
548__setup("nopfault", nopfault);
549
550struct pfault_refbk {
551 u16 refdiagc;
552 u16 reffcode;
553 u16 refdwlen;
554 u16 refversn;
555 u64 refgaddr;
556 u64 refselmk;
557 u64 refcmpmk;
558 u64 reserved;
559} __attribute__ ((packed, aligned(8)));
560
561static struct pfault_refbk pfault_init_refbk = {
562 .refdiagc = 0x258,
563 .reffcode = 0,
564 .refdwlen = 5,
565 .refversn = 2,
566 .refgaddr = __LC_LPP,
567 .refselmk = 1ULL << 48,
568 .refcmpmk = 1ULL << 48,
569 .reserved = __PF_RES_FIELD
570};
571
572int pfault_init(void)
573{
574 int rc;
575
576 if (pfault_disable)
577 return -1;
578 diag_stat_inc(DIAG_STAT_X258);
579 asm volatile(
580 " diag %1,%0,0x258\n"
581 "0: j 2f\n"
582 "1: la %0,8\n"
583 "2:\n"
584 EX_TABLE(0b,1b)
585 : "=d" (rc)
586 : "a" (&pfault_init_refbk), "m" (pfault_init_refbk) : "cc");
587 return rc;
588}
589
590static struct pfault_refbk pfault_fini_refbk = {
591 .refdiagc = 0x258,
592 .reffcode = 1,
593 .refdwlen = 5,
594 .refversn = 2,
595};
596
597void pfault_fini(void)
598{
599
600 if (pfault_disable)
601 return;
602 diag_stat_inc(DIAG_STAT_X258);
603 asm volatile(
604 " diag %0,0,0x258\n"
605 "0: nopr %%r7\n"
606 EX_TABLE(0b,0b)
607 : : "a" (&pfault_fini_refbk), "m" (pfault_fini_refbk) : "cc");
608}
609
610static DEFINE_SPINLOCK(pfault_lock);
611static LIST_HEAD(pfault_list);
612
613#define PF_COMPLETE 0x0080
614
615/*
616 * The mechanism of our pfault code: if Linux is running as guest, runs a user
617 * space process and the user space process accesses a page that the host has
618 * paged out we get a pfault interrupt.
619 *
620 * This allows us, within the guest, to schedule a different process. Without
621 * this mechanism the host would have to suspend the whole virtual cpu until
622 * the page has been paged in.
623 *
624 * So when we get such an interrupt then we set the state of the current task
625 * to uninterruptible and also set the need_resched flag. Both happens within
626 * interrupt context(!). If we later on want to return to user space we
627 * recognize the need_resched flag and then call schedule(). It's not very
628 * obvious how this works...
629 *
630 * Of course we have a lot of additional fun with the completion interrupt (->
631 * host signals that a page of a process has been paged in and the process can
632 * continue to run). This interrupt can arrive on any cpu and, since we have
633 * virtual cpus, actually appear before the interrupt that signals that a page
634 * is missing.
635 */
636static void pfault_interrupt(struct ext_code ext_code,
637 unsigned int param32, unsigned long param64)
638{
639 struct task_struct *tsk;
640 __u16 subcode;
641 pid_t pid;
642
643 /*
644 * Get the external interruption subcode & pfault initial/completion
645 * signal bit. VM stores this in the 'cpu address' field associated
646 * with the external interrupt.
647 */
648 subcode = ext_code.subcode;
649 if ((subcode & 0xff00) != __SUBCODE_MASK)
650 return;
651 inc_irq_stat(IRQEXT_PFL);
652 /* Get the token (= pid of the affected task). */
653 pid = param64 & LPP_PID_MASK;
654 rcu_read_lock();
655 tsk = find_task_by_pid_ns(pid, &init_pid_ns);
656 if (tsk)
657 get_task_struct(tsk);
658 rcu_read_unlock();
659 if (!tsk)
660 return;
661 spin_lock(&pfault_lock);
662 if (subcode & PF_COMPLETE) {
663 /* signal bit is set -> a page has been swapped in by VM */
664 if (tsk->thread.pfault_wait == 1) {
665 /* Initial interrupt was faster than the completion
666 * interrupt. pfault_wait is valid. Set pfault_wait
667 * back to zero and wake up the process. This can
668 * safely be done because the task is still sleeping
669 * and can't produce new pfaults. */
670 tsk->thread.pfault_wait = 0;
671 list_del(&tsk->thread.list);
672 wake_up_process(tsk);
673 put_task_struct(tsk);
674 } else {
675 /* Completion interrupt was faster than initial
676 * interrupt. Set pfault_wait to -1 so the initial
677 * interrupt doesn't put the task to sleep.
678 * If the task is not running, ignore the completion
679 * interrupt since it must be a leftover of a PFAULT
680 * CANCEL operation which didn't remove all pending
681 * completion interrupts. */
682 if (task_is_running(tsk))
683 tsk->thread.pfault_wait = -1;
684 }
685 } else {
686 /* signal bit not set -> a real page is missing. */
687 if (WARN_ON_ONCE(tsk != current))
688 goto out;
689 if (tsk->thread.pfault_wait == 1) {
690 /* Already on the list with a reference: put to sleep */
691 goto block;
692 } else if (tsk->thread.pfault_wait == -1) {
693 /* Completion interrupt was faster than the initial
694 * interrupt (pfault_wait == -1). Set pfault_wait
695 * back to zero and exit. */
696 tsk->thread.pfault_wait = 0;
697 } else {
698 /* Initial interrupt arrived before completion
699 * interrupt. Let the task sleep.
700 * An extra task reference is needed since a different
701 * cpu may set the task state to TASK_RUNNING again
702 * before the scheduler is reached. */
703 get_task_struct(tsk);
704 tsk->thread.pfault_wait = 1;
705 list_add(&tsk->thread.list, &pfault_list);
706block:
707 /* Since this must be a userspace fault, there
708 * is no kernel task state to trample. Rely on the
709 * return to userspace schedule() to block. */
710 __set_current_state(TASK_UNINTERRUPTIBLE);
711 set_tsk_need_resched(tsk);
712 set_preempt_need_resched();
713 }
714 }
715out:
716 spin_unlock(&pfault_lock);
717 put_task_struct(tsk);
718}
719
720static int pfault_cpu_dead(unsigned int cpu)
721{
722 struct thread_struct *thread, *next;
723 struct task_struct *tsk;
724
725 spin_lock_irq(&pfault_lock);
726 list_for_each_entry_safe(thread, next, &pfault_list, list) {
727 thread->pfault_wait = 0;
728 list_del(&thread->list);
729 tsk = container_of(thread, struct task_struct, thread);
730 wake_up_process(tsk);
731 put_task_struct(tsk);
732 }
733 spin_unlock_irq(&pfault_lock);
734 return 0;
735}
736
737static int __init pfault_irq_init(void)
738{
739 int rc;
740
741 rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt);
742 if (rc)
743 goto out_extint;
744 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP;
745 if (rc)
746 goto out_pfault;
747 irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL);
748 cpuhp_setup_state_nocalls(CPUHP_S390_PFAULT_DEAD, "s390/pfault:dead",
749 NULL, pfault_cpu_dead);
750 return 0;
751
752out_pfault:
753 unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt);
754out_extint:
755 pfault_disable = 1;
756 return rc;
757}
758early_initcall(pfault_irq_init);
759
760#endif /* CONFIG_PFAULT */
761
762#if IS_ENABLED(CONFIG_PGSTE)
763
764void do_secure_storage_access(struct pt_regs *regs)
765{
766 unsigned long addr = regs->int_parm_long & __FAIL_ADDR_MASK;
767 struct vm_area_struct *vma;
768 struct mm_struct *mm;
769 struct page *page;
770 int rc;
771
772 /*
773 * bit 61 tells us if the address is valid, if it's not we
774 * have a major problem and should stop the kernel or send a
775 * SIGSEGV to the process. Unfortunately bit 61 is not
776 * reliable without the misc UV feature so we need to check
777 * for that as well.
778 */
779 if (test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications) &&
780 !test_bit_inv(61, ®s->int_parm_long)) {
781 /*
782 * When this happens, userspace did something that it
783 * was not supposed to do, e.g. branching into secure
784 * memory. Trigger a segmentation fault.
785 */
786 if (user_mode(regs)) {
787 send_sig(SIGSEGV, current, 0);
788 return;
789 }
790
791 /*
792 * The kernel should never run into this case and we
793 * have no way out of this situation.
794 */
795 panic("Unexpected PGM 0x3d with TEID bit 61=0");
796 }
797
798 switch (get_fault_type(regs)) {
799 case USER_FAULT:
800 mm = current->mm;
801 mmap_read_lock(mm);
802 vma = find_vma(mm, addr);
803 if (!vma) {
804 mmap_read_unlock(mm);
805 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP);
806 break;
807 }
808 page = follow_page(vma, addr, FOLL_WRITE | FOLL_GET);
809 if (IS_ERR_OR_NULL(page)) {
810 mmap_read_unlock(mm);
811 break;
812 }
813 if (arch_make_page_accessible(page))
814 send_sig(SIGSEGV, current, 0);
815 put_page(page);
816 mmap_read_unlock(mm);
817 break;
818 case KERNEL_FAULT:
819 page = phys_to_page(addr);
820 if (unlikely(!try_get_page(page)))
821 break;
822 rc = arch_make_page_accessible(page);
823 put_page(page);
824 if (rc)
825 BUG();
826 break;
827 case GMAP_FAULT:
828 default:
829 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP);
830 WARN_ON_ONCE(1);
831 }
832}
833NOKPROBE_SYMBOL(do_secure_storage_access);
834
835void do_non_secure_storage_access(struct pt_regs *regs)
836{
837 unsigned long gaddr = regs->int_parm_long & __FAIL_ADDR_MASK;
838 struct gmap *gmap = (struct gmap *)S390_lowcore.gmap;
839
840 if (get_fault_type(regs) != GMAP_FAULT) {
841 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP);
842 WARN_ON_ONCE(1);
843 return;
844 }
845
846 if (gmap_convert_to_secure(gmap, gaddr) == -EINVAL)
847 send_sig(SIGSEGV, current, 0);
848}
849NOKPROBE_SYMBOL(do_non_secure_storage_access);
850
851void do_secure_storage_violation(struct pt_regs *regs)
852{
853 /*
854 * Either KVM messed up the secure guest mapping or the same
855 * page is mapped into multiple secure guests.
856 *
857 * This exception is only triggered when a guest 2 is running
858 * and can therefore never occur in kernel context.
859 */
860 printk_ratelimited(KERN_WARNING
861 "Secure storage violation in task: %s, pid %d\n",
862 current->comm, current->pid);
863 send_sig(SIGSEGV, current, 0);
864}
865
866#endif /* CONFIG_PGSTE */