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/gmap.h> 36 #include <asm/irq.h> 37 #include <asm/mmu_context.h> 38 #include <asm/facility.h> 39 #include "../kernel/entry.h" 40 41 #define __FAIL_ADDR_MASK -4096L 42 #define __SUBCODE_MASK 0x0600 43 #define __PF_RES_FIELD 0x8000000000000000ULL 44 45 #define VM_FAULT_BADCONTEXT 0x010000 46 #define VM_FAULT_BADMAP 0x020000 47 #define VM_FAULT_BADACCESS 0x040000 48 #define VM_FAULT_SIGNAL 0x080000 49 #define VM_FAULT_PFAULT 0x100000 50 51 static unsigned long store_indication __read_mostly; 52 53 static int __init fault_init(void) 54 { 55 if (test_facility(75)) 56 store_indication = 0xc00; 57 return 0; 58 } 59 early_initcall(fault_init); 60 61 static inline int notify_page_fault(struct pt_regs *regs) 62 { 63 int ret = 0; 64 65 /* kprobe_running() needs smp_processor_id() */ 66 if (kprobes_built_in() && !user_mode(regs)) { 67 preempt_disable(); 68 if (kprobe_running() && kprobe_fault_handler(regs, 14)) 69 ret = 1; 70 preempt_enable(); 71 } 72 return ret; 73 } 74 75 76 /* 77 * Unlock any spinlocks which will prevent us from getting the 78 * message out. 79 */ 80 void bust_spinlocks(int yes) 81 { 82 if (yes) { 83 oops_in_progress = 1; 84 } else { 85 int loglevel_save = console_loglevel; 86 console_unblank(); 87 oops_in_progress = 0; 88 /* 89 * OK, the message is on the console. Now we call printk() 90 * without oops_in_progress set so that printk will give klogd 91 * a poke. Hold onto your hats... 92 */ 93 console_loglevel = 15; 94 printk(" "); 95 console_loglevel = loglevel_save; 96 } 97 } 98 99 /* 100 * Returns the address space associated with the fault. 101 * Returns 0 for kernel space and 1 for user space. 102 */ 103 static inline int user_space_fault(struct pt_regs *regs) 104 { 105 unsigned long trans_exc_code; 106 107 /* 108 * The lowest two bits of the translation exception 109 * identification indicate which paging table was used. 110 */ 111 trans_exc_code = regs->int_parm_long & 3; 112 if (trans_exc_code == 3) /* home space -> kernel */ 113 return 0; 114 if (user_mode(regs)) 115 return 1; 116 if (trans_exc_code == 2) /* secondary space -> set_fs */ 117 return current->thread.mm_segment.ar4; 118 if (current->flags & PF_VCPU) 119 return 1; 120 return 0; 121 } 122 123 static int bad_address(void *p) 124 { 125 unsigned long dummy; 126 127 return probe_kernel_address((unsigned long *)p, dummy); 128 } 129 130 static void dump_pagetable(unsigned long asce, unsigned long address) 131 { 132 unsigned long *table = __va(asce & PAGE_MASK); 133 134 pr_alert("AS:%016lx ", asce); 135 switch (asce & _ASCE_TYPE_MASK) { 136 case _ASCE_TYPE_REGION1: 137 table = table + ((address >> 53) & 0x7ff); 138 if (bad_address(table)) 139 goto bad; 140 pr_cont("R1:%016lx ", *table); 141 if (*table & _REGION_ENTRY_INVALID) 142 goto out; 143 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); 144 /* fallthrough */ 145 case _ASCE_TYPE_REGION2: 146 table = table + ((address >> 42) & 0x7ff); 147 if (bad_address(table)) 148 goto bad; 149 pr_cont("R2:%016lx ", *table); 150 if (*table & _REGION_ENTRY_INVALID) 151 goto out; 152 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); 153 /* fallthrough */ 154 case _ASCE_TYPE_REGION3: 155 table = table + ((address >> 31) & 0x7ff); 156 if (bad_address(table)) 157 goto bad; 158 pr_cont("R3:%016lx ", *table); 159 if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE)) 160 goto out; 161 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); 162 /* fallthrough */ 163 case _ASCE_TYPE_SEGMENT: 164 table = table + ((address >> 20) & 0x7ff); 165 if (bad_address(table)) 166 goto bad; 167 pr_cont("S:%016lx ", *table); 168 if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE)) 169 goto out; 170 table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN); 171 } 172 table = table + ((address >> 12) & 0xff); 173 if (bad_address(table)) 174 goto bad; 175 pr_cont("P:%016lx ", *table); 176 out: 177 pr_cont("\n"); 178 return; 179 bad: 180 pr_cont("BAD\n"); 181 } 182 183 static void dump_fault_info(struct pt_regs *regs) 184 { 185 unsigned long asce; 186 187 pr_alert("Failing address: %016lx TEID: %016lx\n", 188 regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long); 189 pr_alert("Fault in "); 190 switch (regs->int_parm_long & 3) { 191 case 3: 192 pr_cont("home space "); 193 break; 194 case 2: 195 pr_cont("secondary space "); 196 break; 197 case 1: 198 pr_cont("access register "); 199 break; 200 case 0: 201 pr_cont("primary space "); 202 break; 203 } 204 pr_cont("mode while using "); 205 if (!user_space_fault(regs)) { 206 asce = S390_lowcore.kernel_asce; 207 pr_cont("kernel "); 208 } 209 #ifdef CONFIG_PGSTE 210 else if ((current->flags & PF_VCPU) && S390_lowcore.gmap) { 211 struct gmap *gmap = (struct gmap *)S390_lowcore.gmap; 212 asce = gmap->asce; 213 pr_cont("gmap "); 214 } 215 #endif 216 else { 217 asce = S390_lowcore.user_asce; 218 pr_cont("user "); 219 } 220 pr_cont("ASCE.\n"); 221 dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK); 222 } 223 224 int show_unhandled_signals = 1; 225 226 void report_user_fault(struct pt_regs *regs, long signr, int is_mm_fault) 227 { 228 if ((task_pid_nr(current) > 1) && !show_unhandled_signals) 229 return; 230 if (!unhandled_signal(current, signr)) 231 return; 232 if (!printk_ratelimit()) 233 return; 234 printk(KERN_ALERT "User process fault: interruption code %04x ilc:%d ", 235 regs->int_code & 0xffff, regs->int_code >> 17); 236 print_vma_addr(KERN_CONT "in ", regs->psw.addr); 237 printk(KERN_CONT "\n"); 238 if (is_mm_fault) 239 dump_fault_info(regs); 240 show_regs(regs); 241 } 242 243 /* 244 * Send SIGSEGV to task. This is an external routine 245 * to keep the stack usage of do_page_fault small. 246 */ 247 static noinline void do_sigsegv(struct pt_regs *regs, int si_code) 248 { 249 struct siginfo si; 250 251 report_user_fault(regs, SIGSEGV, 1); 252 si.si_signo = SIGSEGV; 253 si.si_code = si_code; 254 si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK); 255 force_sig_info(SIGSEGV, &si, current); 256 } 257 258 static noinline void do_no_context(struct pt_regs *regs) 259 { 260 const struct exception_table_entry *fixup; 261 262 /* Are we prepared to handle this kernel fault? */ 263 fixup = search_exception_tables(regs->psw.addr); 264 if (fixup) { 265 regs->psw.addr = extable_fixup(fixup); 266 return; 267 } 268 269 /* 270 * Oops. The kernel tried to access some bad page. We'll have to 271 * terminate things with extreme prejudice. 272 */ 273 if (!user_space_fault(regs)) 274 printk(KERN_ALERT "Unable to handle kernel pointer dereference" 275 " in virtual kernel address space\n"); 276 else 277 printk(KERN_ALERT "Unable to handle kernel paging request" 278 " in virtual user address space\n"); 279 dump_fault_info(regs); 280 die(regs, "Oops"); 281 do_exit(SIGKILL); 282 } 283 284 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 } 296 297 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 } 312 313 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 */ 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 goto out; 463 } 464 if (unlikely(fault & VM_FAULT_ERROR)) 465 goto out_up; 466 467 /* 468 * Major/minor page fault accounting is only done on the 469 * initial attempt. If we go through a retry, it is extremely 470 * likely that the page will be found in page cache at that point. 471 */ 472 if (flags & FAULT_FLAG_ALLOW_RETRY) { 473 if (fault & VM_FAULT_MAJOR) { 474 tsk->maj_flt++; 475 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 476 regs, address); 477 } else { 478 tsk->min_flt++; 479 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 480 regs, address); 481 } 482 if (fault & VM_FAULT_RETRY) { 483 #ifdef CONFIG_PGSTE 484 if (gmap && (flags & FAULT_FLAG_RETRY_NOWAIT)) { 485 /* FAULT_FLAG_RETRY_NOWAIT has been set, 486 * mmap_sem has not been released */ 487 current->thread.gmap_pfault = 1; 488 fault = VM_FAULT_PFAULT; 489 goto out_up; 490 } 491 #endif 492 /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk 493 * of starvation. */ 494 flags &= ~(FAULT_FLAG_ALLOW_RETRY | 495 FAULT_FLAG_RETRY_NOWAIT); 496 flags |= FAULT_FLAG_TRIED; 497 down_read(&mm->mmap_sem); 498 goto retry; 499 } 500 } 501 #ifdef CONFIG_PGSTE 502 if (gmap) { 503 address = __gmap_link(gmap, current->thread.gmap_addr, 504 address); 505 if (address == -EFAULT) { 506 fault = VM_FAULT_BADMAP; 507 goto out_up; 508 } 509 if (address == -ENOMEM) { 510 fault = VM_FAULT_OOM; 511 goto out_up; 512 } 513 } 514 #endif 515 fault = 0; 516 out_up: 517 up_read(&mm->mmap_sem); 518 out: 519 return fault; 520 } 521 522 void do_protection_exception(struct pt_regs *regs) 523 { 524 unsigned long trans_exc_code; 525 int fault; 526 527 trans_exc_code = regs->int_parm_long; 528 /* 529 * Protection exceptions are suppressing, decrement psw address. 530 * The exception to this rule are aborted transactions, for these 531 * the PSW already points to the correct location. 532 */ 533 if (!(regs->int_code & 0x200)) 534 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16); 535 /* 536 * Check for low-address protection. This needs to be treated 537 * as a special case because the translation exception code 538 * field is not guaranteed to contain valid data in this case. 539 */ 540 if (unlikely(!(trans_exc_code & 4))) { 541 do_low_address(regs); 542 return; 543 } 544 fault = do_exception(regs, VM_WRITE); 545 if (unlikely(fault)) 546 do_fault_error(regs, fault); 547 } 548 NOKPROBE_SYMBOL(do_protection_exception); 549 550 void do_dat_exception(struct pt_regs *regs) 551 { 552 int access, fault; 553 554 access = VM_READ | VM_EXEC | VM_WRITE; 555 fault = do_exception(regs, access); 556 if (unlikely(fault)) 557 do_fault_error(regs, fault); 558 } 559 NOKPROBE_SYMBOL(do_dat_exception); 560 561 #ifdef CONFIG_PFAULT 562 /* 563 * 'pfault' pseudo page faults routines. 564 */ 565 static int pfault_disable; 566 567 static int __init nopfault(char *str) 568 { 569 pfault_disable = 1; 570 return 1; 571 } 572 573 __setup("nopfault", nopfault); 574 575 struct pfault_refbk { 576 u16 refdiagc; 577 u16 reffcode; 578 u16 refdwlen; 579 u16 refversn; 580 u64 refgaddr; 581 u64 refselmk; 582 u64 refcmpmk; 583 u64 reserved; 584 } __attribute__ ((packed, aligned(8))); 585 586 int pfault_init(void) 587 { 588 struct pfault_refbk refbk = { 589 .refdiagc = 0x258, 590 .reffcode = 0, 591 .refdwlen = 5, 592 .refversn = 2, 593 .refgaddr = __LC_LPP, 594 .refselmk = 1ULL << 48, 595 .refcmpmk = 1ULL << 48, 596 .reserved = __PF_RES_FIELD }; 597 int rc; 598 599 if (pfault_disable) 600 return -1; 601 diag_stat_inc(DIAG_STAT_X258); 602 asm volatile( 603 " diag %1,%0,0x258\n" 604 "0: j 2f\n" 605 "1: la %0,8\n" 606 "2:\n" 607 EX_TABLE(0b,1b) 608 : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc"); 609 return rc; 610 } 611 612 void pfault_fini(void) 613 { 614 struct pfault_refbk refbk = { 615 .refdiagc = 0x258, 616 .reffcode = 1, 617 .refdwlen = 5, 618 .refversn = 2, 619 }; 620 621 if (pfault_disable) 622 return; 623 diag_stat_inc(DIAG_STAT_X258); 624 asm volatile( 625 " diag %0,0,0x258\n" 626 "0:\n" 627 EX_TABLE(0b,0b) 628 : : "a" (&refbk), "m" (refbk) : "cc"); 629 } 630 631 static DEFINE_SPINLOCK(pfault_lock); 632 static LIST_HEAD(pfault_list); 633 634 #define PF_COMPLETE 0x0080 635 636 /* 637 * The mechanism of our pfault code: if Linux is running as guest, runs a user 638 * space process and the user space process accesses a page that the host has 639 * paged out we get a pfault interrupt. 640 * 641 * This allows us, within the guest, to schedule a different process. Without 642 * this mechanism the host would have to suspend the whole virtual cpu until 643 * the page has been paged in. 644 * 645 * So when we get such an interrupt then we set the state of the current task 646 * to uninterruptible and also set the need_resched flag. Both happens within 647 * interrupt context(!). If we later on want to return to user space we 648 * recognize the need_resched flag and then call schedule(). It's not very 649 * obvious how this works... 650 * 651 * Of course we have a lot of additional fun with the completion interrupt (-> 652 * host signals that a page of a process has been paged in and the process can 653 * continue to run). This interrupt can arrive on any cpu and, since we have 654 * virtual cpus, actually appear before the interrupt that signals that a page 655 * is missing. 656 */ 657 static void pfault_interrupt(struct ext_code ext_code, 658 unsigned int param32, unsigned long param64) 659 { 660 struct task_struct *tsk; 661 __u16 subcode; 662 pid_t pid; 663 664 /* 665 * Get the external interruption subcode & pfault initial/completion 666 * signal bit. VM stores this in the 'cpu address' field associated 667 * with the external interrupt. 668 */ 669 subcode = ext_code.subcode; 670 if ((subcode & 0xff00) != __SUBCODE_MASK) 671 return; 672 inc_irq_stat(IRQEXT_PFL); 673 /* Get the token (= pid of the affected task). */ 674 pid = param64 & LPP_PFAULT_PID_MASK; 675 rcu_read_lock(); 676 tsk = find_task_by_pid_ns(pid, &init_pid_ns); 677 if (tsk) 678 get_task_struct(tsk); 679 rcu_read_unlock(); 680 if (!tsk) 681 return; 682 spin_lock(&pfault_lock); 683 if (subcode & PF_COMPLETE) { 684 /* signal bit is set -> a page has been swapped in by VM */ 685 if (tsk->thread.pfault_wait == 1) { 686 /* Initial interrupt was faster than the completion 687 * interrupt. pfault_wait is valid. Set pfault_wait 688 * back to zero and wake up the process. This can 689 * safely be done because the task is still sleeping 690 * and can't produce new pfaults. */ 691 tsk->thread.pfault_wait = 0; 692 list_del(&tsk->thread.list); 693 wake_up_process(tsk); 694 put_task_struct(tsk); 695 } else { 696 /* Completion interrupt was faster than initial 697 * interrupt. Set pfault_wait to -1 so the initial 698 * interrupt doesn't put the task to sleep. 699 * If the task is not running, ignore the completion 700 * interrupt since it must be a leftover of a PFAULT 701 * CANCEL operation which didn't remove all pending 702 * completion interrupts. */ 703 if (tsk->state == TASK_RUNNING) 704 tsk->thread.pfault_wait = -1; 705 } 706 } else { 707 /* signal bit not set -> a real page is missing. */ 708 if (WARN_ON_ONCE(tsk != current)) 709 goto out; 710 if (tsk->thread.pfault_wait == 1) { 711 /* Already on the list with a reference: put to sleep */ 712 goto block; 713 } else if (tsk->thread.pfault_wait == -1) { 714 /* Completion interrupt was faster than the initial 715 * interrupt (pfault_wait == -1). Set pfault_wait 716 * back to zero and exit. */ 717 tsk->thread.pfault_wait = 0; 718 } else { 719 /* Initial interrupt arrived before completion 720 * interrupt. Let the task sleep. 721 * An extra task reference is needed since a different 722 * cpu may set the task state to TASK_RUNNING again 723 * before the scheduler is reached. */ 724 get_task_struct(tsk); 725 tsk->thread.pfault_wait = 1; 726 list_add(&tsk->thread.list, &pfault_list); 727 block: 728 /* Since this must be a userspace fault, there 729 * is no kernel task state to trample. Rely on the 730 * return to userspace schedule() to block. */ 731 __set_current_state(TASK_UNINTERRUPTIBLE); 732 set_tsk_need_resched(tsk); 733 } 734 } 735 out: 736 spin_unlock(&pfault_lock); 737 put_task_struct(tsk); 738 } 739 740 static int pfault_cpu_notify(struct notifier_block *self, unsigned long action, 741 void *hcpu) 742 { 743 struct thread_struct *thread, *next; 744 struct task_struct *tsk; 745 746 switch (action & ~CPU_TASKS_FROZEN) { 747 case CPU_DEAD: 748 spin_lock_irq(&pfault_lock); 749 list_for_each_entry_safe(thread, next, &pfault_list, list) { 750 thread->pfault_wait = 0; 751 list_del(&thread->list); 752 tsk = container_of(thread, struct task_struct, thread); 753 wake_up_process(tsk); 754 put_task_struct(tsk); 755 } 756 spin_unlock_irq(&pfault_lock); 757 break; 758 default: 759 break; 760 } 761 return NOTIFY_OK; 762 } 763 764 static int __init pfault_irq_init(void) 765 { 766 int rc; 767 768 rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); 769 if (rc) 770 goto out_extint; 771 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP; 772 if (rc) 773 goto out_pfault; 774 irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL); 775 hotcpu_notifier(pfault_cpu_notify, 0); 776 return 0; 777 778 out_pfault: 779 unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); 780 out_extint: 781 pfault_disable = 1; 782 return rc; 783 } 784 early_initcall(pfault_irq_init); 785 786 #endif /* CONFIG_PFAULT */ 787