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