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/diag.h>
34 #include <asm/pgtable.h>
35 #include <asm/irq.h>
36 #include <asm/mmu_context.h>
37 #include <asm/facility.h>
38 #include "../kernel/entry.h"
39
40 #define __FAIL_ADDR_MASK -4096L
41 #define __SUBCODE_MASK 0x0600
42 #define __PF_RES_FIELD 0x8000000000000000ULL
43
44 #define VM_FAULT_BADCONTEXT 0x010000
45 #define VM_FAULT_BADMAP 0x020000
46 #define VM_FAULT_BADACCESS 0x040000
47 #define VM_FAULT_SIGNAL 0x080000
48 #define VM_FAULT_PFAULT 0x100000
49
50 static unsigned long store_indication __read_mostly;
51
fault_init(void)52 static int __init fault_init(void)
53 {
54 if (test_facility(75))
55 store_indication = 0xc00;
56 return 0;
57 }
58 early_initcall(fault_init);
59
notify_page_fault(struct pt_regs * regs)60 static inline int notify_page_fault(struct pt_regs *regs)
61 {
62 int ret = 0;
63
64 /* kprobe_running() needs smp_processor_id() */
65 if (kprobes_built_in() && !user_mode(regs)) {
66 preempt_disable();
67 if (kprobe_running() && kprobe_fault_handler(regs, 14))
68 ret = 1;
69 preempt_enable();
70 }
71 return ret;
72 }
73
74
75 /*
76 * Unlock any spinlocks which will prevent us from getting the
77 * message out.
78 */
bust_spinlocks(int yes)79 void bust_spinlocks(int yes)
80 {
81 if (yes) {
82 oops_in_progress = 1;
83 } else {
84 int loglevel_save = console_loglevel;
85 console_unblank();
86 oops_in_progress = 0;
87 /*
88 * OK, the message is on the console. Now we call printk()
89 * without oops_in_progress set so that printk will give klogd
90 * a poke. Hold onto your hats...
91 */
92 console_loglevel = 15;
93 printk(" ");
94 console_loglevel = loglevel_save;
95 }
96 }
97
98 /*
99 * Returns the address space associated with the fault.
100 * Returns 0 for kernel space and 1 for user space.
101 */
user_space_fault(struct pt_regs * regs)102 static inline int user_space_fault(struct pt_regs *regs)
103 {
104 unsigned long trans_exc_code;
105
106 /*
107 * The lowest two bits of the translation exception
108 * identification indicate which paging table was used.
109 */
110 trans_exc_code = regs->int_parm_long & 3;
111 if (trans_exc_code == 3) /* home space -> kernel */
112 return 0;
113 if (user_mode(regs))
114 return 1;
115 if (trans_exc_code == 2) /* secondary space -> set_fs */
116 return current->thread.mm_segment.ar4;
117 if (current->flags & PF_VCPU)
118 return 1;
119 return 0;
120 }
121
bad_address(void * p)122 static int bad_address(void *p)
123 {
124 unsigned long dummy;
125
126 return probe_kernel_address((unsigned long *)p, dummy);
127 }
128
dump_pagetable(unsigned long asce,unsigned long address)129 static void dump_pagetable(unsigned long asce, unsigned long address)
130 {
131 unsigned long *table = __va(asce & PAGE_MASK);
132
133 pr_alert("AS:%016lx ", asce);
134 switch (asce & _ASCE_TYPE_MASK) {
135 case _ASCE_TYPE_REGION1:
136 table = table + ((address >> 53) & 0x7ff);
137 if (bad_address(table))
138 goto bad;
139 pr_cont("R1:%016lx ", *table);
140 if (*table & _REGION_ENTRY_INVALID)
141 goto out;
142 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
143 /* fallthrough */
144 case _ASCE_TYPE_REGION2:
145 table = table + ((address >> 42) & 0x7ff);
146 if (bad_address(table))
147 goto bad;
148 pr_cont("R2:%016lx ", *table);
149 if (*table & _REGION_ENTRY_INVALID)
150 goto out;
151 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
152 /* fallthrough */
153 case _ASCE_TYPE_REGION3:
154 table = table + ((address >> 31) & 0x7ff);
155 if (bad_address(table))
156 goto bad;
157 pr_cont("R3:%016lx ", *table);
158 if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE))
159 goto out;
160 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
161 /* fallthrough */
162 case _ASCE_TYPE_SEGMENT:
163 table = table + ((address >> 20) & 0x7ff);
164 if (bad_address(table))
165 goto bad;
166 pr_cont("S:%016lx ", *table);
167 if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE))
168 goto out;
169 table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
170 }
171 table = table + ((address >> 12) & 0xff);
172 if (bad_address(table))
173 goto bad;
174 pr_cont("P:%016lx ", *table);
175 out:
176 pr_cont("\n");
177 return;
178 bad:
179 pr_cont("BAD\n");
180 }
181
dump_fault_info(struct pt_regs * regs)182 static void dump_fault_info(struct pt_regs *regs)
183 {
184 unsigned long asce;
185
186 pr_alert("Fault in ");
187 switch (regs->int_parm_long & 3) {
188 case 3:
189 pr_cont("home space ");
190 break;
191 case 2:
192 pr_cont("secondary space ");
193 break;
194 case 1:
195 pr_cont("access register ");
196 break;
197 case 0:
198 pr_cont("primary space ");
199 break;
200 }
201 pr_cont("mode while using ");
202 if (!user_space_fault(regs)) {
203 asce = S390_lowcore.kernel_asce;
204 pr_cont("kernel ");
205 }
206 #ifdef CONFIG_PGSTE
207 else if ((current->flags & PF_VCPU) && S390_lowcore.gmap) {
208 struct gmap *gmap = (struct gmap *)S390_lowcore.gmap;
209 asce = gmap->asce;
210 pr_cont("gmap ");
211 }
212 #endif
213 else {
214 asce = S390_lowcore.user_asce;
215 pr_cont("user ");
216 }
217 pr_cont("ASCE.\n");
218 dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK);
219 }
220
report_user_fault(struct pt_regs * regs,long signr)221 static inline void report_user_fault(struct pt_regs *regs, long signr)
222 {
223 if ((task_pid_nr(current) > 1) && !show_unhandled_signals)
224 return;
225 if (!unhandled_signal(current, signr))
226 return;
227 if (!printk_ratelimit())
228 return;
229 printk(KERN_ALERT "User process fault: interruption code %04x ilc:%d ",
230 regs->int_code & 0xffff, regs->int_code >> 17);
231 print_vma_addr(KERN_CONT "in ", regs->psw.addr & PSW_ADDR_INSN);
232 printk(KERN_CONT "\n");
233 printk(KERN_ALERT "failing address: %016lx TEID: %016lx\n",
234 regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long);
235 dump_fault_info(regs);
236 show_regs(regs);
237 }
238
239 /*
240 * Send SIGSEGV to task. This is an external routine
241 * to keep the stack usage of do_page_fault small.
242 */
do_sigsegv(struct pt_regs * regs,int si_code)243 static noinline void do_sigsegv(struct pt_regs *regs, int si_code)
244 {
245 struct siginfo si;
246
247 report_user_fault(regs, SIGSEGV);
248 si.si_signo = SIGSEGV;
249 si.si_code = si_code;
250 si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
251 force_sig_info(SIGSEGV, &si, current);
252 }
253
do_no_context(struct pt_regs * regs)254 static noinline void do_no_context(struct pt_regs *regs)
255 {
256 const struct exception_table_entry *fixup;
257 unsigned long address;
258
259 /* Are we prepared to handle this kernel fault? */
260 fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
261 if (fixup) {
262 regs->psw.addr = extable_fixup(fixup) | PSW_ADDR_AMODE;
263 return;
264 }
265
266 /*
267 * Oops. The kernel tried to access some bad page. We'll have to
268 * terminate things with extreme prejudice.
269 */
270 address = regs->int_parm_long & __FAIL_ADDR_MASK;
271 if (!user_space_fault(regs))
272 printk(KERN_ALERT "Unable to handle kernel pointer dereference"
273 " in virtual kernel address space\n");
274 else
275 printk(KERN_ALERT "Unable to handle kernel paging request"
276 " in virtual user address space\n");
277 printk(KERN_ALERT "failing address: %016lx TEID: %016lx\n",
278 regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long);
279 dump_fault_info(regs);
280 die(regs, "Oops");
281 do_exit(SIGKILL);
282 }
283
do_low_address(struct pt_regs * regs)284 static noinline void do_low_address(struct pt_regs *regs)
285 {
286 /* Low-address protection hit in kernel mode means
287 NULL pointer write access in kernel mode. */
288 if (regs->psw.mask & PSW_MASK_PSTATE) {
289 /* Low-address protection hit in user mode 'cannot happen'. */
290 die (regs, "Low-address protection");
291 do_exit(SIGKILL);
292 }
293
294 do_no_context(regs);
295 }
296
do_sigbus(struct pt_regs * regs)297 static noinline void do_sigbus(struct pt_regs *regs)
298 {
299 struct task_struct *tsk = current;
300 struct siginfo si;
301
302 /*
303 * Send a sigbus, regardless of whether we were in kernel
304 * or user mode.
305 */
306 si.si_signo = SIGBUS;
307 si.si_errno = 0;
308 si.si_code = BUS_ADRERR;
309 si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
310 force_sig_info(SIGBUS, &si, tsk);
311 }
312
do_fault_error(struct pt_regs * regs,int fault)313 static noinline void do_fault_error(struct pt_regs *regs, int fault)
314 {
315 int si_code;
316
317 switch (fault) {
318 case VM_FAULT_BADACCESS:
319 case VM_FAULT_BADMAP:
320 /* Bad memory access. Check if it is kernel or user space. */
321 if (user_mode(regs)) {
322 /* User mode accesses just cause a SIGSEGV */
323 si_code = (fault == VM_FAULT_BADMAP) ?
324 SEGV_MAPERR : SEGV_ACCERR;
325 do_sigsegv(regs, si_code);
326 return;
327 }
328 case VM_FAULT_BADCONTEXT:
329 case VM_FAULT_PFAULT:
330 do_no_context(regs);
331 break;
332 case VM_FAULT_SIGNAL:
333 if (!user_mode(regs))
334 do_no_context(regs);
335 break;
336 default: /* fault & VM_FAULT_ERROR */
337 if (fault & VM_FAULT_OOM) {
338 if (!user_mode(regs))
339 do_no_context(regs);
340 else
341 pagefault_out_of_memory();
342 } else if (fault & VM_FAULT_SIGSEGV) {
343 /* Kernel mode? Handle exceptions or die */
344 if (!user_mode(regs))
345 do_no_context(regs);
346 else
347 do_sigsegv(regs, SEGV_MAPERR);
348 } else if (fault & VM_FAULT_SIGBUS) {
349 /* Kernel mode? Handle exceptions or die */
350 if (!user_mode(regs))
351 do_no_context(regs);
352 else
353 do_sigbus(regs);
354 } else
355 BUG();
356 break;
357 }
358 }
359
360 /*
361 * This routine handles page faults. It determines the address,
362 * and the problem, and then passes it off to one of the appropriate
363 * routines.
364 *
365 * interruption code (int_code):
366 * 04 Protection -> Write-Protection (suprression)
367 * 10 Segment translation -> Not present (nullification)
368 * 11 Page translation -> Not present (nullification)
369 * 3b Region third trans. -> Not present (nullification)
370 */
do_exception(struct pt_regs * regs,int access)371 static inline int do_exception(struct pt_regs *regs, int access)
372 {
373 #ifdef CONFIG_PGSTE
374 struct gmap *gmap;
375 #endif
376 struct task_struct *tsk;
377 struct mm_struct *mm;
378 struct vm_area_struct *vma;
379 unsigned long trans_exc_code;
380 unsigned long address;
381 unsigned int flags;
382 int fault;
383
384 tsk = current;
385 /*
386 * The instruction that caused the program check has
387 * been nullified. Don't signal single step via SIGTRAP.
388 */
389 clear_pt_regs_flag(regs, PIF_PER_TRAP);
390
391 if (notify_page_fault(regs))
392 return 0;
393
394 mm = tsk->mm;
395 trans_exc_code = regs->int_parm_long;
396
397 /*
398 * Verify that the fault happened in user space, that
399 * we are not in an interrupt and that there is a
400 * user context.
401 */
402 fault = VM_FAULT_BADCONTEXT;
403 if (unlikely(!user_space_fault(regs) || faulthandler_disabled() || !mm))
404 goto out;
405
406 address = trans_exc_code & __FAIL_ADDR_MASK;
407 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
408 flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
409 if (user_mode(regs))
410 flags |= FAULT_FLAG_USER;
411 if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
412 flags |= FAULT_FLAG_WRITE;
413 down_read(&mm->mmap_sem);
414
415 #ifdef CONFIG_PGSTE
416 gmap = (current->flags & PF_VCPU) ?
417 (struct gmap *) S390_lowcore.gmap : NULL;
418 if (gmap) {
419 current->thread.gmap_addr = address;
420 address = __gmap_translate(gmap, address);
421 if (address == -EFAULT) {
422 fault = VM_FAULT_BADMAP;
423 goto out_up;
424 }
425 if (gmap->pfault_enabled)
426 flags |= FAULT_FLAG_RETRY_NOWAIT;
427 }
428 #endif
429
430 retry:
431 fault = VM_FAULT_BADMAP;
432 vma = find_vma(mm, address);
433 if (!vma)
434 goto out_up;
435
436 if (unlikely(vma->vm_start > address)) {
437 if (!(vma->vm_flags & VM_GROWSDOWN))
438 goto out_up;
439 if (expand_stack(vma, address))
440 goto out_up;
441 }
442
443 /*
444 * Ok, we have a good vm_area for this memory access, so
445 * we can handle it..
446 */
447 fault = VM_FAULT_BADACCESS;
448 if (unlikely(!(vma->vm_flags & access)))
449 goto out_up;
450
451 if (is_vm_hugetlb_page(vma))
452 address &= HPAGE_MASK;
453 /*
454 * If for any reason at all we couldn't handle the fault,
455 * make sure we exit gracefully rather than endlessly redo
456 * the fault.
457 */
458 fault = handle_mm_fault(mm, vma, address, flags);
459 /* No reason to continue if interrupted by SIGKILL. */
460 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) {
461 fault = VM_FAULT_SIGNAL;
462 if (flags & FAULT_FLAG_RETRY_NOWAIT)
463 goto out_up;
464 goto out;
465 }
466 if (unlikely(fault & VM_FAULT_ERROR))
467 goto out_up;
468
469 /*
470 * Major/minor page fault accounting is only done on the
471 * initial attempt. If we go through a retry, it is extremely
472 * likely that the page will be found in page cache at that point.
473 */
474 if (flags & FAULT_FLAG_ALLOW_RETRY) {
475 if (fault & VM_FAULT_MAJOR) {
476 tsk->maj_flt++;
477 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
478 regs, address);
479 } else {
480 tsk->min_flt++;
481 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
482 regs, address);
483 }
484 if (fault & VM_FAULT_RETRY) {
485 #ifdef CONFIG_PGSTE
486 if (gmap && (flags & FAULT_FLAG_RETRY_NOWAIT)) {
487 /* FAULT_FLAG_RETRY_NOWAIT has been set,
488 * mmap_sem has not been released */
489 current->thread.gmap_pfault = 1;
490 fault = VM_FAULT_PFAULT;
491 goto out_up;
492 }
493 #endif
494 /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
495 * of starvation. */
496 flags &= ~(FAULT_FLAG_ALLOW_RETRY |
497 FAULT_FLAG_RETRY_NOWAIT);
498 flags |= FAULT_FLAG_TRIED;
499 down_read(&mm->mmap_sem);
500 goto retry;
501 }
502 }
503 #ifdef CONFIG_PGSTE
504 if (gmap) {
505 address = __gmap_link(gmap, current->thread.gmap_addr,
506 address);
507 if (address == -EFAULT) {
508 fault = VM_FAULT_BADMAP;
509 goto out_up;
510 }
511 if (address == -ENOMEM) {
512 fault = VM_FAULT_OOM;
513 goto out_up;
514 }
515 }
516 #endif
517 fault = 0;
518 out_up:
519 up_read(&mm->mmap_sem);
520 out:
521 return fault;
522 }
523
do_protection_exception(struct pt_regs * regs)524 void do_protection_exception(struct pt_regs *regs)
525 {
526 unsigned long trans_exc_code;
527 int fault;
528
529 trans_exc_code = regs->int_parm_long;
530 /*
531 * Protection exceptions are suppressing, decrement psw address.
532 * The exception to this rule are aborted transactions, for these
533 * the PSW already points to the correct location.
534 */
535 if (!(regs->int_code & 0x200))
536 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
537 /*
538 * Check for low-address protection. This needs to be treated
539 * as a special case because the translation exception code
540 * field is not guaranteed to contain valid data in this case.
541 */
542 if (unlikely(!(trans_exc_code & 4))) {
543 do_low_address(regs);
544 return;
545 }
546 fault = do_exception(regs, VM_WRITE);
547 if (unlikely(fault))
548 do_fault_error(regs, fault);
549 }
550 NOKPROBE_SYMBOL(do_protection_exception);
551
do_dat_exception(struct pt_regs * regs)552 void do_dat_exception(struct pt_regs *regs)
553 {
554 int access, fault;
555
556 access = VM_READ | VM_EXEC | VM_WRITE;
557 fault = do_exception(regs, access);
558 if (unlikely(fault))
559 do_fault_error(regs, fault);
560 }
561 NOKPROBE_SYMBOL(do_dat_exception);
562
563 #ifdef CONFIG_PFAULT
564 /*
565 * 'pfault' pseudo page faults routines.
566 */
567 static int pfault_disable;
568
nopfault(char * str)569 static int __init nopfault(char *str)
570 {
571 pfault_disable = 1;
572 return 1;
573 }
574
575 __setup("nopfault", nopfault);
576
577 struct pfault_refbk {
578 u16 refdiagc;
579 u16 reffcode;
580 u16 refdwlen;
581 u16 refversn;
582 u64 refgaddr;
583 u64 refselmk;
584 u64 refcmpmk;
585 u64 reserved;
586 } __attribute__ ((packed, aligned(8)));
587
pfault_init(void)588 int pfault_init(void)
589 {
590 struct pfault_refbk refbk = {
591 .refdiagc = 0x258,
592 .reffcode = 0,
593 .refdwlen = 5,
594 .refversn = 2,
595 .refgaddr = __LC_LPP,
596 .refselmk = 1ULL << 48,
597 .refcmpmk = 1ULL << 48,
598 .reserved = __PF_RES_FIELD };
599 int rc;
600
601 if (pfault_disable)
602 return -1;
603 diag_stat_inc(DIAG_STAT_X258);
604 asm volatile(
605 " diag %1,%0,0x258\n"
606 "0: j 2f\n"
607 "1: la %0,8\n"
608 "2:\n"
609 EX_TABLE(0b,1b)
610 : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc");
611 return rc;
612 }
613
pfault_fini(void)614 void pfault_fini(void)
615 {
616 struct pfault_refbk refbk = {
617 .refdiagc = 0x258,
618 .reffcode = 1,
619 .refdwlen = 5,
620 .refversn = 2,
621 };
622
623 if (pfault_disable)
624 return;
625 diag_stat_inc(DIAG_STAT_X258);
626 asm volatile(
627 " diag %0,0,0x258\n"
628 "0:\n"
629 EX_TABLE(0b,0b)
630 : : "a" (&refbk), "m" (refbk) : "cc");
631 }
632
633 static DEFINE_SPINLOCK(pfault_lock);
634 static LIST_HEAD(pfault_list);
635
pfault_interrupt(struct ext_code ext_code,unsigned int param32,unsigned long param64)636 static 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
645 * initial/completion signal bit. VM stores this
646 * in the 'cpu address' field associated with the
647 * external interrupt.
648 */
649 subcode = ext_code.subcode;
650 if ((subcode & 0xff00) != __SUBCODE_MASK)
651 return;
652 inc_irq_stat(IRQEXT_PFL);
653 /* Get the token (= pid of the affected task). */
654 pid = param64 & LPP_PFAULT_PID_MASK;
655 rcu_read_lock();
656 tsk = find_task_by_pid_ns(pid, &init_pid_ns);
657 if (tsk)
658 get_task_struct(tsk);
659 rcu_read_unlock();
660 if (!tsk)
661 return;
662 spin_lock(&pfault_lock);
663 if (subcode & 0x0080) {
664 /* signal bit is set -> a page has been swapped in by VM */
665 if (tsk->thread.pfault_wait == 1) {
666 /* Initial interrupt was faster than the completion
667 * interrupt. pfault_wait is valid. Set pfault_wait
668 * back to zero and wake up the process. This can
669 * safely be done because the task is still sleeping
670 * and can't produce new pfaults. */
671 tsk->thread.pfault_wait = 0;
672 list_del(&tsk->thread.list);
673 wake_up_process(tsk);
674 put_task_struct(tsk);
675 } else {
676 /* Completion interrupt was faster than initial
677 * interrupt. Set pfault_wait to -1 so the initial
678 * interrupt doesn't put the task to sleep.
679 * If the task is not running, ignore the completion
680 * interrupt since it must be a leftover of a PFAULT
681 * CANCEL operation which didn't remove all pending
682 * completion interrupts. */
683 if (tsk->state == TASK_RUNNING)
684 tsk->thread.pfault_wait = -1;
685 }
686 } else {
687 /* signal bit not set -> a real page is missing. */
688 if (WARN_ON_ONCE(tsk != current))
689 goto out;
690 if (tsk->thread.pfault_wait == 1) {
691 /* Already on the list with a reference: put to sleep */
692 __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
693 set_tsk_need_resched(tsk);
694 } else if (tsk->thread.pfault_wait == -1) {
695 /* Completion interrupt was faster than the initial
696 * interrupt (pfault_wait == -1). Set pfault_wait
697 * back to zero and exit. */
698 tsk->thread.pfault_wait = 0;
699 } else {
700 /* Initial interrupt arrived before completion
701 * interrupt. Let the task sleep.
702 * An extra task reference is needed since a different
703 * cpu may set the task state to TASK_RUNNING again
704 * before the scheduler is reached. */
705 get_task_struct(tsk);
706 tsk->thread.pfault_wait = 1;
707 list_add(&tsk->thread.list, &pfault_list);
708 __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
709 set_tsk_need_resched(tsk);
710 }
711 }
712 out:
713 spin_unlock(&pfault_lock);
714 put_task_struct(tsk);
715 }
716
pfault_cpu_notify(struct notifier_block * self,unsigned long action,void * hcpu)717 static int pfault_cpu_notify(struct notifier_block *self, unsigned long action,
718 void *hcpu)
719 {
720 struct thread_struct *thread, *next;
721 struct task_struct *tsk;
722
723 switch (action & ~CPU_TASKS_FROZEN) {
724 case CPU_DEAD:
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 break;
735 default:
736 break;
737 }
738 return NOTIFY_OK;
739 }
740
pfault_irq_init(void)741 static int __init pfault_irq_init(void)
742 {
743 int rc;
744
745 rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt);
746 if (rc)
747 goto out_extint;
748 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP;
749 if (rc)
750 goto out_pfault;
751 irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL);
752 hotcpu_notifier(pfault_cpu_notify, 0);
753 return 0;
754
755 out_pfault:
756 unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt);
757 out_extint:
758 pfault_disable = 1;
759 return rc;
760 }
761 early_initcall(pfault_irq_init);
762
763 #endif /* CONFIG_PFAULT */
764