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_errno = 0; 254 si.si_code = si_code; 255 si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK); 256 force_sig_info(SIGSEGV, &si, current); 257 } 258 259 static noinline void do_no_context(struct pt_regs *regs) 260 { 261 const struct exception_table_entry *fixup; 262 263 /* Are we prepared to handle this kernel fault? */ 264 fixup = search_exception_tables(regs->psw.addr); 265 if (fixup) { 266 regs->psw.addr = extable_fixup(fixup); 267 return; 268 } 269 270 /* 271 * Oops. The kernel tried to access some bad page. We'll have to 272 * terminate things with extreme prejudice. 273 */ 274 if (!user_space_fault(regs)) 275 printk(KERN_ALERT "Unable to handle kernel pointer dereference" 276 " in virtual kernel address space\n"); 277 else 278 printk(KERN_ALERT "Unable to handle kernel paging request" 279 " in virtual user address space\n"); 280 dump_fault_info(regs); 281 die(regs, "Oops"); 282 do_exit(SIGKILL); 283 } 284 285 static noinline void do_low_address(struct pt_regs *regs) 286 { 287 /* Low-address protection hit in kernel mode means 288 NULL pointer write access in kernel mode. */ 289 if (regs->psw.mask & PSW_MASK_PSTATE) { 290 /* Low-address protection hit in user mode 'cannot happen'. */ 291 die (regs, "Low-address protection"); 292 do_exit(SIGKILL); 293 } 294 295 do_no_context(regs); 296 } 297 298 static noinline void do_sigbus(struct pt_regs *regs) 299 { 300 struct task_struct *tsk = current; 301 struct siginfo si; 302 303 /* 304 * Send a sigbus, regardless of whether we were in kernel 305 * or user mode. 306 */ 307 si.si_signo = SIGBUS; 308 si.si_errno = 0; 309 si.si_code = BUS_ADRERR; 310 si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK); 311 force_sig_info(SIGBUS, &si, tsk); 312 } 313 314 static noinline void do_fault_error(struct pt_regs *regs, int fault) 315 { 316 int si_code; 317 318 switch (fault) { 319 case VM_FAULT_BADACCESS: 320 case VM_FAULT_BADMAP: 321 /* Bad memory access. Check if it is kernel or user space. */ 322 if (user_mode(regs)) { 323 /* User mode accesses just cause a SIGSEGV */ 324 si_code = (fault == VM_FAULT_BADMAP) ? 325 SEGV_MAPERR : SEGV_ACCERR; 326 do_sigsegv(regs, si_code); 327 return; 328 } 329 case VM_FAULT_BADCONTEXT: 330 case VM_FAULT_PFAULT: 331 do_no_context(regs); 332 break; 333 case VM_FAULT_SIGNAL: 334 if (!user_mode(regs)) 335 do_no_context(regs); 336 break; 337 default: /* fault & VM_FAULT_ERROR */ 338 if (fault & VM_FAULT_OOM) { 339 if (!user_mode(regs)) 340 do_no_context(regs); 341 else 342 pagefault_out_of_memory(); 343 } else if (fault & VM_FAULT_SIGSEGV) { 344 /* Kernel mode? Handle exceptions or die */ 345 if (!user_mode(regs)) 346 do_no_context(regs); 347 else 348 do_sigsegv(regs, SEGV_MAPERR); 349 } else if (fault & VM_FAULT_SIGBUS) { 350 /* Kernel mode? Handle exceptions or die */ 351 if (!user_mode(regs)) 352 do_no_context(regs); 353 else 354 do_sigbus(regs); 355 } else 356 BUG(); 357 break; 358 } 359 } 360 361 /* 362 * This routine handles page faults. It determines the address, 363 * and the problem, and then passes it off to one of the appropriate 364 * routines. 365 * 366 * interruption code (int_code): 367 * 04 Protection -> Write-Protection (suprression) 368 * 10 Segment translation -> Not present (nullification) 369 * 11 Page translation -> Not present (nullification) 370 * 3b Region third trans. -> Not present (nullification) 371 */ 372 static inline int do_exception(struct pt_regs *regs, int access) 373 { 374 #ifdef CONFIG_PGSTE 375 struct gmap *gmap; 376 #endif 377 struct task_struct *tsk; 378 struct mm_struct *mm; 379 struct vm_area_struct *vma; 380 unsigned long trans_exc_code; 381 unsigned long address; 382 unsigned int flags; 383 int fault; 384 385 tsk = current; 386 /* 387 * The instruction that caused the program check has 388 * been nullified. Don't signal single step via SIGTRAP. 389 */ 390 clear_pt_regs_flag(regs, PIF_PER_TRAP); 391 392 if (notify_page_fault(regs)) 393 return 0; 394 395 mm = tsk->mm; 396 trans_exc_code = regs->int_parm_long; 397 398 /* 399 * Verify that the fault happened in user space, that 400 * we are not in an interrupt and that there is a 401 * user context. 402 */ 403 fault = VM_FAULT_BADCONTEXT; 404 if (unlikely(!user_space_fault(regs) || faulthandler_disabled() || !mm)) 405 goto out; 406 407 address = trans_exc_code & __FAIL_ADDR_MASK; 408 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 409 flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; 410 if (user_mode(regs)) 411 flags |= FAULT_FLAG_USER; 412 if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400) 413 flags |= FAULT_FLAG_WRITE; 414 down_read(&mm->mmap_sem); 415 416 #ifdef CONFIG_PGSTE 417 gmap = (current->flags & PF_VCPU) ? 418 (struct gmap *) S390_lowcore.gmap : NULL; 419 if (gmap) { 420 current->thread.gmap_addr = address; 421 current->thread.gmap_write_flag = !!(flags & FAULT_FLAG_WRITE); 422 current->thread.gmap_int_code = regs->int_code & 0xffff; 423 address = __gmap_translate(gmap, address); 424 if (address == -EFAULT) { 425 fault = VM_FAULT_BADMAP; 426 goto out_up; 427 } 428 if (gmap->pfault_enabled) 429 flags |= FAULT_FLAG_RETRY_NOWAIT; 430 } 431 #endif 432 433 retry: 434 fault = VM_FAULT_BADMAP; 435 vma = find_vma(mm, address); 436 if (!vma) 437 goto out_up; 438 439 if (unlikely(vma->vm_start > address)) { 440 if (!(vma->vm_flags & VM_GROWSDOWN)) 441 goto out_up; 442 if (expand_stack(vma, address)) 443 goto out_up; 444 } 445 446 /* 447 * Ok, we have a good vm_area for this memory access, so 448 * we can handle it.. 449 */ 450 fault = VM_FAULT_BADACCESS; 451 if (unlikely(!(vma->vm_flags & access))) 452 goto out_up; 453 454 if (is_vm_hugetlb_page(vma)) 455 address &= HPAGE_MASK; 456 /* 457 * If for any reason at all we couldn't handle the fault, 458 * make sure we exit gracefully rather than endlessly redo 459 * the fault. 460 */ 461 fault = handle_mm_fault(vma, address, flags); 462 /* No reason to continue if interrupted by SIGKILL. */ 463 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) { 464 fault = VM_FAULT_SIGNAL; 465 goto out; 466 } 467 if (unlikely(fault & VM_FAULT_ERROR)) 468 goto out_up; 469 470 /* 471 * Major/minor page fault accounting is only done on the 472 * initial attempt. If we go through a retry, it is extremely 473 * likely that the page will be found in page cache at that point. 474 */ 475 if (flags & FAULT_FLAG_ALLOW_RETRY) { 476 if (fault & VM_FAULT_MAJOR) { 477 tsk->maj_flt++; 478 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 479 regs, address); 480 } else { 481 tsk->min_flt++; 482 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 483 regs, address); 484 } 485 if (fault & VM_FAULT_RETRY) { 486 #ifdef CONFIG_PGSTE 487 if (gmap && (flags & FAULT_FLAG_RETRY_NOWAIT)) { 488 /* FAULT_FLAG_RETRY_NOWAIT has been set, 489 * mmap_sem has not been released */ 490 current->thread.gmap_pfault = 1; 491 fault = VM_FAULT_PFAULT; 492 goto out_up; 493 } 494 #endif 495 /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk 496 * of starvation. */ 497 flags &= ~(FAULT_FLAG_ALLOW_RETRY | 498 FAULT_FLAG_RETRY_NOWAIT); 499 flags |= FAULT_FLAG_TRIED; 500 down_read(&mm->mmap_sem); 501 goto retry; 502 } 503 } 504 #ifdef CONFIG_PGSTE 505 if (gmap) { 506 address = __gmap_link(gmap, current->thread.gmap_addr, 507 address); 508 if (address == -EFAULT) { 509 fault = VM_FAULT_BADMAP; 510 goto out_up; 511 } 512 if (address == -ENOMEM) { 513 fault = VM_FAULT_OOM; 514 goto out_up; 515 } 516 } 517 #endif 518 fault = 0; 519 out_up: 520 up_read(&mm->mmap_sem); 521 out: 522 return fault; 523 } 524 525 void do_protection_exception(struct pt_regs *regs) 526 { 527 unsigned long trans_exc_code; 528 int fault; 529 530 trans_exc_code = regs->int_parm_long; 531 /* 532 * Protection exceptions are suppressing, decrement psw address. 533 * The exception to this rule are aborted transactions, for these 534 * the PSW already points to the correct location. 535 */ 536 if (!(regs->int_code & 0x200)) 537 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16); 538 /* 539 * Check for low-address protection. This needs to be treated 540 * as a special case because the translation exception code 541 * field is not guaranteed to contain valid data in this case. 542 */ 543 if (unlikely(!(trans_exc_code & 4))) { 544 do_low_address(regs); 545 return; 546 } 547 fault = do_exception(regs, VM_WRITE); 548 if (unlikely(fault)) 549 do_fault_error(regs, fault); 550 } 551 NOKPROBE_SYMBOL(do_protection_exception); 552 553 void do_dat_exception(struct pt_regs *regs) 554 { 555 int access, fault; 556 557 access = VM_READ | VM_EXEC | VM_WRITE; 558 fault = do_exception(regs, access); 559 if (unlikely(fault)) 560 do_fault_error(regs, fault); 561 } 562 NOKPROBE_SYMBOL(do_dat_exception); 563 564 #ifdef CONFIG_PFAULT 565 /* 566 * 'pfault' pseudo page faults routines. 567 */ 568 static int pfault_disable; 569 570 static int __init nopfault(char *str) 571 { 572 pfault_disable = 1; 573 return 1; 574 } 575 576 __setup("nopfault", nopfault); 577 578 struct pfault_refbk { 579 u16 refdiagc; 580 u16 reffcode; 581 u16 refdwlen; 582 u16 refversn; 583 u64 refgaddr; 584 u64 refselmk; 585 u64 refcmpmk; 586 u64 reserved; 587 } __attribute__ ((packed, aligned(8))); 588 589 int pfault_init(void) 590 { 591 struct pfault_refbk refbk = { 592 .refdiagc = 0x258, 593 .reffcode = 0, 594 .refdwlen = 5, 595 .refversn = 2, 596 .refgaddr = __LC_LPP, 597 .refselmk = 1ULL << 48, 598 .refcmpmk = 1ULL << 48, 599 .reserved = __PF_RES_FIELD }; 600 int rc; 601 602 if (pfault_disable) 603 return -1; 604 diag_stat_inc(DIAG_STAT_X258); 605 asm volatile( 606 " diag %1,%0,0x258\n" 607 "0: j 2f\n" 608 "1: la %0,8\n" 609 "2:\n" 610 EX_TABLE(0b,1b) 611 : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc"); 612 return rc; 613 } 614 615 void pfault_fini(void) 616 { 617 struct pfault_refbk refbk = { 618 .refdiagc = 0x258, 619 .reffcode = 1, 620 .refdwlen = 5, 621 .refversn = 2, 622 }; 623 624 if (pfault_disable) 625 return; 626 diag_stat_inc(DIAG_STAT_X258); 627 asm volatile( 628 " diag %0,0,0x258\n" 629 "0: nopr %%r7\n" 630 EX_TABLE(0b,0b) 631 : : "a" (&refbk), "m" (refbk) : "cc"); 632 } 633 634 static DEFINE_SPINLOCK(pfault_lock); 635 static LIST_HEAD(pfault_list); 636 637 #define PF_COMPLETE 0x0080 638 639 /* 640 * The mechanism of our pfault code: if Linux is running as guest, runs a user 641 * space process and the user space process accesses a page that the host has 642 * paged out we get a pfault interrupt. 643 * 644 * This allows us, within the guest, to schedule a different process. Without 645 * this mechanism the host would have to suspend the whole virtual cpu until 646 * the page has been paged in. 647 * 648 * So when we get such an interrupt then we set the state of the current task 649 * to uninterruptible and also set the need_resched flag. Both happens within 650 * interrupt context(!). If we later on want to return to user space we 651 * recognize the need_resched flag and then call schedule(). It's not very 652 * obvious how this works... 653 * 654 * Of course we have a lot of additional fun with the completion interrupt (-> 655 * host signals that a page of a process has been paged in and the process can 656 * continue to run). This interrupt can arrive on any cpu and, since we have 657 * virtual cpus, actually appear before the interrupt that signals that a page 658 * is missing. 659 */ 660 static void pfault_interrupt(struct ext_code ext_code, 661 unsigned int param32, unsigned long param64) 662 { 663 struct task_struct *tsk; 664 __u16 subcode; 665 pid_t pid; 666 667 /* 668 * Get the external interruption subcode & pfault initial/completion 669 * signal bit. VM stores this in the 'cpu address' field associated 670 * with the external interrupt. 671 */ 672 subcode = ext_code.subcode; 673 if ((subcode & 0xff00) != __SUBCODE_MASK) 674 return; 675 inc_irq_stat(IRQEXT_PFL); 676 /* Get the token (= pid of the affected task). */ 677 pid = param64 & LPP_PFAULT_PID_MASK; 678 rcu_read_lock(); 679 tsk = find_task_by_pid_ns(pid, &init_pid_ns); 680 if (tsk) 681 get_task_struct(tsk); 682 rcu_read_unlock(); 683 if (!tsk) 684 return; 685 spin_lock(&pfault_lock); 686 if (subcode & PF_COMPLETE) { 687 /* signal bit is set -> a page has been swapped in by VM */ 688 if (tsk->thread.pfault_wait == 1) { 689 /* Initial interrupt was faster than the completion 690 * interrupt. pfault_wait is valid. Set pfault_wait 691 * back to zero and wake up the process. This can 692 * safely be done because the task is still sleeping 693 * and can't produce new pfaults. */ 694 tsk->thread.pfault_wait = 0; 695 list_del(&tsk->thread.list); 696 wake_up_process(tsk); 697 put_task_struct(tsk); 698 } else { 699 /* Completion interrupt was faster than initial 700 * interrupt. Set pfault_wait to -1 so the initial 701 * interrupt doesn't put the task to sleep. 702 * If the task is not running, ignore the completion 703 * interrupt since it must be a leftover of a PFAULT 704 * CANCEL operation which didn't remove all pending 705 * completion interrupts. */ 706 if (tsk->state == TASK_RUNNING) 707 tsk->thread.pfault_wait = -1; 708 } 709 } else { 710 /* signal bit not set -> a real page is missing. */ 711 if (WARN_ON_ONCE(tsk != current)) 712 goto out; 713 if (tsk->thread.pfault_wait == 1) { 714 /* Already on the list with a reference: put to sleep */ 715 goto block; 716 } else if (tsk->thread.pfault_wait == -1) { 717 /* Completion interrupt was faster than the initial 718 * interrupt (pfault_wait == -1). Set pfault_wait 719 * back to zero and exit. */ 720 tsk->thread.pfault_wait = 0; 721 } else { 722 /* Initial interrupt arrived before completion 723 * interrupt. Let the task sleep. 724 * An extra task reference is needed since a different 725 * cpu may set the task state to TASK_RUNNING again 726 * before the scheduler is reached. */ 727 get_task_struct(tsk); 728 tsk->thread.pfault_wait = 1; 729 list_add(&tsk->thread.list, &pfault_list); 730 block: 731 /* Since this must be a userspace fault, there 732 * is no kernel task state to trample. Rely on the 733 * return to userspace schedule() to block. */ 734 __set_current_state(TASK_UNINTERRUPTIBLE); 735 set_tsk_need_resched(tsk); 736 } 737 } 738 out: 739 spin_unlock(&pfault_lock); 740 put_task_struct(tsk); 741 } 742 743 static int pfault_cpu_notify(struct notifier_block *self, unsigned long action, 744 void *hcpu) 745 { 746 struct thread_struct *thread, *next; 747 struct task_struct *tsk; 748 749 switch (action & ~CPU_TASKS_FROZEN) { 750 case CPU_DEAD: 751 spin_lock_irq(&pfault_lock); 752 list_for_each_entry_safe(thread, next, &pfault_list, list) { 753 thread->pfault_wait = 0; 754 list_del(&thread->list); 755 tsk = container_of(thread, struct task_struct, thread); 756 wake_up_process(tsk); 757 put_task_struct(tsk); 758 } 759 spin_unlock_irq(&pfault_lock); 760 break; 761 default: 762 break; 763 } 764 return NOTIFY_OK; 765 } 766 767 static int __init pfault_irq_init(void) 768 { 769 int rc; 770 771 rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); 772 if (rc) 773 goto out_extint; 774 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP; 775 if (rc) 776 goto out_pfault; 777 irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL); 778 hotcpu_notifier(pfault_cpu_notify, 0); 779 return 0; 780 781 out_pfault: 782 unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); 783 out_extint: 784 pfault_disable = 1; 785 return rc; 786 } 787 early_initcall(pfault_irq_init); 788 789 #endif /* CONFIG_PFAULT */ 790