1 /*
2 * S390 version
3 * Copyright IBM Corp. 1999
4 * Author(s): Hartmut Penner (hp@de.ibm.com)
5 * Ulrich Weigand (uweigand@de.ibm.com)
6 *
7 * Derived from "arch/i386/mm/fault.c"
8 * Copyright (C) 1995 Linus Torvalds
9 */
10
11 #include <linux/kernel_stat.h>
12 #include <linux/perf_event.h>
13 #include <linux/signal.h>
14 #include <linux/sched.h>
15 #include <linux/kernel.h>
16 #include <linux/errno.h>
17 #include <linux/string.h>
18 #include <linux/types.h>
19 #include <linux/ptrace.h>
20 #include <linux/mman.h>
21 #include <linux/mm.h>
22 #include <linux/compat.h>
23 #include <linux/smp.h>
24 #include <linux/kdebug.h>
25 #include <linux/init.h>
26 #include <linux/console.h>
27 #include <linux/module.h>
28 #include <linux/hardirq.h>
29 #include <linux/kprobes.h>
30 #include <linux/uaccess.h>
31 #include <linux/hugetlb.h>
32 #include <asm/asm-offsets.h>
33 #include <asm/pgtable.h>
34 #include <asm/irq.h>
35 #include <asm/mmu_context.h>
36 #include <asm/facility.h>
37 #include "../kernel/entry.h"
38
39 #ifndef CONFIG_64BIT
40 #define __FAIL_ADDR_MASK 0x7ffff000
41 #define __SUBCODE_MASK 0x0200
42 #define __PF_RES_FIELD 0ULL
43 #else /* CONFIG_64BIT */
44 #define __FAIL_ADDR_MASK -4096L
45 #define __SUBCODE_MASK 0x0600
46 #define __PF_RES_FIELD 0x8000000000000000ULL
47 #endif /* CONFIG_64BIT */
48
49 #define VM_FAULT_BADCONTEXT 0x010000
50 #define VM_FAULT_BADMAP 0x020000
51 #define VM_FAULT_BADACCESS 0x040000
52 #define VM_FAULT_SIGNAL 0x080000
53 #define VM_FAULT_PFAULT 0x100000
54
55 static unsigned long store_indication __read_mostly;
56
57 #ifdef CONFIG_64BIT
fault_init(void)58 static int __init fault_init(void)
59 {
60 if (test_facility(75))
61 store_indication = 0xc00;
62 return 0;
63 }
64 early_initcall(fault_init);
65 #endif
66
notify_page_fault(struct pt_regs * regs)67 static inline int notify_page_fault(struct pt_regs *regs)
68 {
69 int ret = 0;
70
71 /* kprobe_running() needs smp_processor_id() */
72 if (kprobes_built_in() && !user_mode(regs)) {
73 preempt_disable();
74 if (kprobe_running() && kprobe_fault_handler(regs, 14))
75 ret = 1;
76 preempt_enable();
77 }
78 return ret;
79 }
80
81
82 /*
83 * Unlock any spinlocks which will prevent us from getting the
84 * message out.
85 */
bust_spinlocks(int yes)86 void bust_spinlocks(int yes)
87 {
88 if (yes) {
89 oops_in_progress = 1;
90 } else {
91 int loglevel_save = console_loglevel;
92 console_unblank();
93 oops_in_progress = 0;
94 /*
95 * OK, the message is on the console. Now we call printk()
96 * without oops_in_progress set so that printk will give klogd
97 * a poke. Hold onto your hats...
98 */
99 console_loglevel = 15;
100 printk(" ");
101 console_loglevel = loglevel_save;
102 }
103 }
104
105 /*
106 * Returns the address space associated with the fault.
107 * Returns 0 for kernel space and 1 for user space.
108 */
user_space_fault(struct pt_regs * regs)109 static inline int user_space_fault(struct pt_regs *regs)
110 {
111 unsigned long trans_exc_code;
112
113 /*
114 * The lowest two bits of the translation exception
115 * identification indicate which paging table was used.
116 */
117 trans_exc_code = regs->int_parm_long & 3;
118 if (trans_exc_code == 3) /* home space -> kernel */
119 return 0;
120 if (user_mode(regs))
121 return 1;
122 if (trans_exc_code == 2) /* secondary space -> set_fs */
123 return current->thread.mm_segment.ar4;
124 if (current->flags & PF_VCPU)
125 return 1;
126 return 0;
127 }
128
bad_address(void * p)129 static int bad_address(void *p)
130 {
131 unsigned long dummy;
132
133 return probe_kernel_address((unsigned long *)p, dummy);
134 }
135
136 #ifdef CONFIG_64BIT
dump_pagetable(unsigned long asce,unsigned long address)137 static void dump_pagetable(unsigned long asce, unsigned long address)
138 {
139 unsigned long *table = __va(asce & PAGE_MASK);
140
141 pr_alert("AS:%016lx ", asce);
142 switch (asce & _ASCE_TYPE_MASK) {
143 case _ASCE_TYPE_REGION1:
144 table = table + ((address >> 53) & 0x7ff);
145 if (bad_address(table))
146 goto bad;
147 pr_cont("R1:%016lx ", *table);
148 if (*table & _REGION_ENTRY_INVALID)
149 goto out;
150 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
151 /* fallthrough */
152 case _ASCE_TYPE_REGION2:
153 table = table + ((address >> 42) & 0x7ff);
154 if (bad_address(table))
155 goto bad;
156 pr_cont("R2:%016lx ", *table);
157 if (*table & _REGION_ENTRY_INVALID)
158 goto out;
159 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
160 /* fallthrough */
161 case _ASCE_TYPE_REGION3:
162 table = table + ((address >> 31) & 0x7ff);
163 if (bad_address(table))
164 goto bad;
165 pr_cont("R3:%016lx ", *table);
166 if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE))
167 goto out;
168 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
169 /* fallthrough */
170 case _ASCE_TYPE_SEGMENT:
171 table = table + ((address >> 20) & 0x7ff);
172 if (bad_address(table))
173 goto bad;
174 pr_cont(KERN_CONT "S:%016lx ", *table);
175 if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE))
176 goto out;
177 table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
178 }
179 table = table + ((address >> 12) & 0xff);
180 if (bad_address(table))
181 goto bad;
182 pr_cont("P:%016lx ", *table);
183 out:
184 pr_cont("\n");
185 return;
186 bad:
187 pr_cont("BAD\n");
188 }
189
190 #else /* CONFIG_64BIT */
191
dump_pagetable(unsigned long asce,unsigned long address)192 static void dump_pagetable(unsigned long asce, unsigned long address)
193 {
194 unsigned long *table = __va(asce & PAGE_MASK);
195
196 pr_alert("AS:%08lx ", asce);
197 table = table + ((address >> 20) & 0x7ff);
198 if (bad_address(table))
199 goto bad;
200 pr_cont("S:%08lx ", *table);
201 if (*table & _SEGMENT_ENTRY_INVALID)
202 goto out;
203 table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
204 table = table + ((address >> 12) & 0xff);
205 if (bad_address(table))
206 goto bad;
207 pr_cont("P:%08lx ", *table);
208 out:
209 pr_cont("\n");
210 return;
211 bad:
212 pr_cont("BAD\n");
213 }
214
215 #endif /* CONFIG_64BIT */
216
dump_fault_info(struct pt_regs * regs)217 static void dump_fault_info(struct pt_regs *regs)
218 {
219 unsigned long asce;
220
221 pr_alert("Fault in ");
222 switch (regs->int_parm_long & 3) {
223 case 3:
224 pr_cont("home space ");
225 break;
226 case 2:
227 pr_cont("secondary space ");
228 break;
229 case 1:
230 pr_cont("access register ");
231 break;
232 case 0:
233 pr_cont("primary space ");
234 break;
235 }
236 pr_cont("mode while using ");
237 if (!user_space_fault(regs)) {
238 asce = S390_lowcore.kernel_asce;
239 pr_cont("kernel ");
240 }
241 #ifdef CONFIG_PGSTE
242 else if ((current->flags & PF_VCPU) && S390_lowcore.gmap) {
243 struct gmap *gmap = (struct gmap *)S390_lowcore.gmap;
244 asce = gmap->asce;
245 pr_cont("gmap ");
246 }
247 #endif
248 else {
249 asce = S390_lowcore.user_asce;
250 pr_cont("user ");
251 }
252 pr_cont("ASCE.\n");
253 dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK);
254 }
255
report_user_fault(struct pt_regs * regs,long signr)256 static inline void report_user_fault(struct pt_regs *regs, long signr)
257 {
258 if ((task_pid_nr(current) > 1) && !show_unhandled_signals)
259 return;
260 if (!unhandled_signal(current, signr))
261 return;
262 if (!printk_ratelimit())
263 return;
264 printk(KERN_ALERT "User process fault: interruption code 0x%X ",
265 regs->int_code);
266 print_vma_addr(KERN_CONT "in ", regs->psw.addr & PSW_ADDR_INSN);
267 printk(KERN_CONT "\n");
268 printk(KERN_ALERT "failing address: %016lx TEID: %016lx\n",
269 regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long);
270 dump_fault_info(regs);
271 show_regs(regs);
272 }
273
274 /*
275 * Send SIGSEGV to task. This is an external routine
276 * to keep the stack usage of do_page_fault small.
277 */
do_sigsegv(struct pt_regs * regs,int si_code)278 static noinline void do_sigsegv(struct pt_regs *regs, int si_code)
279 {
280 struct siginfo si;
281
282 report_user_fault(regs, SIGSEGV);
283 si.si_signo = SIGSEGV;
284 si.si_code = si_code;
285 si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
286 force_sig_info(SIGSEGV, &si, current);
287 }
288
do_no_context(struct pt_regs * regs)289 static noinline void do_no_context(struct pt_regs *regs)
290 {
291 const struct exception_table_entry *fixup;
292 unsigned long address;
293
294 /* Are we prepared to handle this kernel fault? */
295 fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
296 if (fixup) {
297 regs->psw.addr = extable_fixup(fixup) | PSW_ADDR_AMODE;
298 return;
299 }
300
301 /*
302 * Oops. The kernel tried to access some bad page. We'll have to
303 * terminate things with extreme prejudice.
304 */
305 address = regs->int_parm_long & __FAIL_ADDR_MASK;
306 if (!user_space_fault(regs))
307 printk(KERN_ALERT "Unable to handle kernel pointer dereference"
308 " in virtual kernel address space\n");
309 else
310 printk(KERN_ALERT "Unable to handle kernel paging request"
311 " in virtual user address space\n");
312 printk(KERN_ALERT "failing address: %016lx TEID: %016lx\n",
313 regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long);
314 dump_fault_info(regs);
315 die(regs, "Oops");
316 do_exit(SIGKILL);
317 }
318
do_low_address(struct pt_regs * regs)319 static noinline void do_low_address(struct pt_regs *regs)
320 {
321 /* Low-address protection hit in kernel mode means
322 NULL pointer write access in kernel mode. */
323 if (regs->psw.mask & PSW_MASK_PSTATE) {
324 /* Low-address protection hit in user mode 'cannot happen'. */
325 die (regs, "Low-address protection");
326 do_exit(SIGKILL);
327 }
328
329 do_no_context(regs);
330 }
331
do_sigbus(struct pt_regs * regs)332 static noinline void do_sigbus(struct pt_regs *regs)
333 {
334 struct task_struct *tsk = current;
335 struct siginfo si;
336
337 /*
338 * Send a sigbus, regardless of whether we were in kernel
339 * or user mode.
340 */
341 si.si_signo = SIGBUS;
342 si.si_errno = 0;
343 si.si_code = BUS_ADRERR;
344 si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
345 force_sig_info(SIGBUS, &si, tsk);
346 }
347
do_fault_error(struct pt_regs * regs,int fault)348 static noinline void do_fault_error(struct pt_regs *regs, int fault)
349 {
350 int si_code;
351
352 switch (fault) {
353 case VM_FAULT_BADACCESS:
354 case VM_FAULT_BADMAP:
355 /* Bad memory access. Check if it is kernel or user space. */
356 if (user_mode(regs)) {
357 /* User mode accesses just cause a SIGSEGV */
358 si_code = (fault == VM_FAULT_BADMAP) ?
359 SEGV_MAPERR : SEGV_ACCERR;
360 do_sigsegv(regs, si_code);
361 return;
362 }
363 case VM_FAULT_BADCONTEXT:
364 case VM_FAULT_PFAULT:
365 do_no_context(regs);
366 break;
367 case VM_FAULT_SIGNAL:
368 if (!user_mode(regs))
369 do_no_context(regs);
370 break;
371 default: /* fault & VM_FAULT_ERROR */
372 if (fault & VM_FAULT_OOM) {
373 if (!user_mode(regs))
374 do_no_context(regs);
375 else
376 pagefault_out_of_memory();
377 } else if (fault & VM_FAULT_SIGSEGV) {
378 /* Kernel mode? Handle exceptions or die */
379 if (!user_mode(regs))
380 do_no_context(regs);
381 else
382 do_sigsegv(regs, SEGV_MAPERR);
383 } else if (fault & VM_FAULT_SIGBUS) {
384 /* Kernel mode? Handle exceptions or die */
385 if (!user_mode(regs))
386 do_no_context(regs);
387 else
388 do_sigbus(regs);
389 } else
390 BUG();
391 break;
392 }
393 }
394
395 /*
396 * This routine handles page faults. It determines the address,
397 * and the problem, and then passes it off to one of the appropriate
398 * routines.
399 *
400 * interruption code (int_code):
401 * 04 Protection -> Write-Protection (suprression)
402 * 10 Segment translation -> Not present (nullification)
403 * 11 Page translation -> Not present (nullification)
404 * 3b Region third trans. -> Not present (nullification)
405 */
do_exception(struct pt_regs * regs,int access)406 static inline int do_exception(struct pt_regs *regs, int access)
407 {
408 #ifdef CONFIG_PGSTE
409 struct gmap *gmap;
410 #endif
411 struct task_struct *tsk;
412 struct mm_struct *mm;
413 struct vm_area_struct *vma;
414 unsigned long trans_exc_code;
415 unsigned long address;
416 unsigned int flags;
417 int fault;
418
419 tsk = current;
420 /*
421 * The instruction that caused the program check has
422 * been nullified. Don't signal single step via SIGTRAP.
423 */
424 clear_pt_regs_flag(regs, PIF_PER_TRAP);
425
426 if (notify_page_fault(regs))
427 return 0;
428
429 mm = tsk->mm;
430 trans_exc_code = regs->int_parm_long;
431
432 /*
433 * Verify that the fault happened in user space, that
434 * we are not in an interrupt and that there is a
435 * user context.
436 */
437 fault = VM_FAULT_BADCONTEXT;
438 if (unlikely(!user_space_fault(regs) || in_atomic() || !mm))
439 goto out;
440
441 address = trans_exc_code & __FAIL_ADDR_MASK;
442 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
443 flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
444 if (user_mode(regs))
445 flags |= FAULT_FLAG_USER;
446 if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
447 flags |= FAULT_FLAG_WRITE;
448 down_read(&mm->mmap_sem);
449
450 #ifdef CONFIG_PGSTE
451 gmap = (current->flags & PF_VCPU) ?
452 (struct gmap *) S390_lowcore.gmap : NULL;
453 if (gmap) {
454 current->thread.gmap_addr = address;
455 address = __gmap_translate(gmap, address);
456 if (address == -EFAULT) {
457 fault = VM_FAULT_BADMAP;
458 goto out_up;
459 }
460 if (gmap->pfault_enabled)
461 flags |= FAULT_FLAG_RETRY_NOWAIT;
462 }
463 #endif
464
465 retry:
466 fault = VM_FAULT_BADMAP;
467 vma = find_vma(mm, address);
468 if (!vma)
469 goto out_up;
470
471 if (unlikely(vma->vm_start > address)) {
472 if (!(vma->vm_flags & VM_GROWSDOWN))
473 goto out_up;
474 if (expand_stack(vma, address))
475 goto out_up;
476 }
477
478 /*
479 * Ok, we have a good vm_area for this memory access, so
480 * we can handle it..
481 */
482 fault = VM_FAULT_BADACCESS;
483 if (unlikely(!(vma->vm_flags & access)))
484 goto out_up;
485
486 if (is_vm_hugetlb_page(vma))
487 address &= HPAGE_MASK;
488 /*
489 * If for any reason at all we couldn't handle the fault,
490 * make sure we exit gracefully rather than endlessly redo
491 * the fault.
492 */
493 fault = handle_mm_fault(mm, vma, address, flags);
494 /* No reason to continue if interrupted by SIGKILL. */
495 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) {
496 fault = VM_FAULT_SIGNAL;
497 goto out;
498 }
499 if (unlikely(fault & VM_FAULT_ERROR))
500 goto out_up;
501
502 /*
503 * Major/minor page fault accounting is only done on the
504 * initial attempt. If we go through a retry, it is extremely
505 * likely that the page will be found in page cache at that point.
506 */
507 if (flags & FAULT_FLAG_ALLOW_RETRY) {
508 if (fault & VM_FAULT_MAJOR) {
509 tsk->maj_flt++;
510 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
511 regs, address);
512 } else {
513 tsk->min_flt++;
514 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
515 regs, address);
516 }
517 if (fault & VM_FAULT_RETRY) {
518 #ifdef CONFIG_PGSTE
519 if (gmap && (flags & FAULT_FLAG_RETRY_NOWAIT)) {
520 /* FAULT_FLAG_RETRY_NOWAIT has been set,
521 * mmap_sem has not been released */
522 current->thread.gmap_pfault = 1;
523 fault = VM_FAULT_PFAULT;
524 goto out_up;
525 }
526 #endif
527 /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
528 * of starvation. */
529 flags &= ~(FAULT_FLAG_ALLOW_RETRY |
530 FAULT_FLAG_RETRY_NOWAIT);
531 flags |= FAULT_FLAG_TRIED;
532 down_read(&mm->mmap_sem);
533 goto retry;
534 }
535 }
536 #ifdef CONFIG_PGSTE
537 if (gmap) {
538 address = __gmap_link(gmap, current->thread.gmap_addr,
539 address);
540 if (address == -EFAULT) {
541 fault = VM_FAULT_BADMAP;
542 goto out_up;
543 }
544 if (address == -ENOMEM) {
545 fault = VM_FAULT_OOM;
546 goto out_up;
547 }
548 }
549 #endif
550 fault = 0;
551 out_up:
552 up_read(&mm->mmap_sem);
553 out:
554 return fault;
555 }
556
do_protection_exception(struct pt_regs * regs)557 void __kprobes do_protection_exception(struct pt_regs *regs)
558 {
559 unsigned long trans_exc_code;
560 int fault;
561
562 trans_exc_code = regs->int_parm_long;
563 /*
564 * Protection exceptions are suppressing, decrement psw address.
565 * The exception to this rule are aborted transactions, for these
566 * the PSW already points to the correct location.
567 */
568 if (!(regs->int_code & 0x200))
569 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
570 /*
571 * Check for low-address protection. This needs to be treated
572 * as a special case because the translation exception code
573 * field is not guaranteed to contain valid data in this case.
574 */
575 if (unlikely(!(trans_exc_code & 4))) {
576 do_low_address(regs);
577 return;
578 }
579 fault = do_exception(regs, VM_WRITE);
580 if (unlikely(fault))
581 do_fault_error(regs, fault);
582 }
583
do_dat_exception(struct pt_regs * regs)584 void __kprobes do_dat_exception(struct pt_regs *regs)
585 {
586 int access, fault;
587
588 access = VM_READ | VM_EXEC | VM_WRITE;
589 fault = do_exception(regs, access);
590 if (unlikely(fault))
591 do_fault_error(regs, fault);
592 }
593
594 #ifdef CONFIG_PFAULT
595 /*
596 * 'pfault' pseudo page faults routines.
597 */
598 static int pfault_disable;
599
nopfault(char * str)600 static int __init nopfault(char *str)
601 {
602 pfault_disable = 1;
603 return 1;
604 }
605
606 __setup("nopfault", nopfault);
607
608 struct pfault_refbk {
609 u16 refdiagc;
610 u16 reffcode;
611 u16 refdwlen;
612 u16 refversn;
613 u64 refgaddr;
614 u64 refselmk;
615 u64 refcmpmk;
616 u64 reserved;
617 } __attribute__ ((packed, aligned(8)));
618
pfault_init(void)619 int pfault_init(void)
620 {
621 struct pfault_refbk refbk = {
622 .refdiagc = 0x258,
623 .reffcode = 0,
624 .refdwlen = 5,
625 .refversn = 2,
626 .refgaddr = __LC_CURRENT_PID,
627 .refselmk = 1ULL << 48,
628 .refcmpmk = 1ULL << 48,
629 .reserved = __PF_RES_FIELD };
630 int rc;
631
632 if (pfault_disable)
633 return -1;
634 asm volatile(
635 " diag %1,%0,0x258\n"
636 "0: j 2f\n"
637 "1: la %0,8\n"
638 "2:\n"
639 EX_TABLE(0b,1b)
640 : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc");
641 return rc;
642 }
643
pfault_fini(void)644 void pfault_fini(void)
645 {
646 struct pfault_refbk refbk = {
647 .refdiagc = 0x258,
648 .reffcode = 1,
649 .refdwlen = 5,
650 .refversn = 2,
651 };
652
653 if (pfault_disable)
654 return;
655 asm volatile(
656 " diag %0,0,0x258\n"
657 "0:\n"
658 EX_TABLE(0b,0b)
659 : : "a" (&refbk), "m" (refbk) : "cc");
660 }
661
662 static DEFINE_SPINLOCK(pfault_lock);
663 static LIST_HEAD(pfault_list);
664
pfault_interrupt(struct ext_code ext_code,unsigned int param32,unsigned long param64)665 static void pfault_interrupt(struct ext_code ext_code,
666 unsigned int param32, unsigned long param64)
667 {
668 struct task_struct *tsk;
669 __u16 subcode;
670 pid_t pid;
671
672 /*
673 * Get the external interruption subcode & pfault
674 * initial/completion signal bit. VM stores this
675 * in the 'cpu address' field associated with the
676 * external interrupt.
677 */
678 subcode = ext_code.subcode;
679 if ((subcode & 0xff00) != __SUBCODE_MASK)
680 return;
681 inc_irq_stat(IRQEXT_PFL);
682 /* Get the token (= pid of the affected task). */
683 pid = sizeof(void *) == 4 ? param32 : param64;
684 rcu_read_lock();
685 tsk = find_task_by_pid_ns(pid, &init_pid_ns);
686 if (tsk)
687 get_task_struct(tsk);
688 rcu_read_unlock();
689 if (!tsk)
690 return;
691 spin_lock(&pfault_lock);
692 if (subcode & 0x0080) {
693 /* signal bit is set -> a page has been swapped in by VM */
694 if (tsk->thread.pfault_wait == 1) {
695 /* Initial interrupt was faster than the completion
696 * interrupt. pfault_wait is valid. Set pfault_wait
697 * back to zero and wake up the process. This can
698 * safely be done because the task is still sleeping
699 * and can't produce new pfaults. */
700 tsk->thread.pfault_wait = 0;
701 list_del(&tsk->thread.list);
702 wake_up_process(tsk);
703 put_task_struct(tsk);
704 } else {
705 /* Completion interrupt was faster than initial
706 * interrupt. Set pfault_wait to -1 so the initial
707 * interrupt doesn't put the task to sleep.
708 * If the task is not running, ignore the completion
709 * interrupt since it must be a leftover of a PFAULT
710 * CANCEL operation which didn't remove all pending
711 * completion interrupts. */
712 if (tsk->state == TASK_RUNNING)
713 tsk->thread.pfault_wait = -1;
714 }
715 } else {
716 /* signal bit not set -> a real page is missing. */
717 if (WARN_ON_ONCE(tsk != current))
718 goto out;
719 if (tsk->thread.pfault_wait == 1) {
720 /* Already on the list with a reference: put to sleep */
721 __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
722 set_tsk_need_resched(tsk);
723 } else if (tsk->thread.pfault_wait == -1) {
724 /* Completion interrupt was faster than the initial
725 * interrupt (pfault_wait == -1). Set pfault_wait
726 * back to zero and exit. */
727 tsk->thread.pfault_wait = 0;
728 } else {
729 /* Initial interrupt arrived before completion
730 * interrupt. Let the task sleep.
731 * An extra task reference is needed since a different
732 * cpu may set the task state to TASK_RUNNING again
733 * before the scheduler is reached. */
734 get_task_struct(tsk);
735 tsk->thread.pfault_wait = 1;
736 list_add(&tsk->thread.list, &pfault_list);
737 __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
738 set_tsk_need_resched(tsk);
739 }
740 }
741 out:
742 spin_unlock(&pfault_lock);
743 put_task_struct(tsk);
744 }
745
pfault_cpu_notify(struct notifier_block * self,unsigned long action,void * hcpu)746 static int pfault_cpu_notify(struct notifier_block *self, unsigned long action,
747 void *hcpu)
748 {
749 struct thread_struct *thread, *next;
750 struct task_struct *tsk;
751
752 switch (action & ~CPU_TASKS_FROZEN) {
753 case CPU_DEAD:
754 spin_lock_irq(&pfault_lock);
755 list_for_each_entry_safe(thread, next, &pfault_list, list) {
756 thread->pfault_wait = 0;
757 list_del(&thread->list);
758 tsk = container_of(thread, struct task_struct, thread);
759 wake_up_process(tsk);
760 put_task_struct(tsk);
761 }
762 spin_unlock_irq(&pfault_lock);
763 break;
764 default:
765 break;
766 }
767 return NOTIFY_OK;
768 }
769
pfault_irq_init(void)770 static int __init pfault_irq_init(void)
771 {
772 int rc;
773
774 rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt);
775 if (rc)
776 goto out_extint;
777 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP;
778 if (rc)
779 goto out_pfault;
780 irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL);
781 hotcpu_notifier(pfault_cpu_notify, 0);
782 return 0;
783
784 out_pfault:
785 unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt);
786 out_extint:
787 pfault_disable = 1;
788 return rc;
789 }
790 early_initcall(pfault_irq_init);
791
792 #endif /* CONFIG_PFAULT */
793