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 54 static unsigned long store_indication; 55 56 void fault_init(void) 57 { 58 if (test_facility(2) && test_facility(75)) 59 store_indication = 0xc00; 60 } 61 62 static inline int notify_page_fault(struct pt_regs *regs) 63 { 64 int ret = 0; 65 66 /* kprobe_running() needs smp_processor_id() */ 67 if (kprobes_built_in() && !user_mode(regs)) { 68 preempt_disable(); 69 if (kprobe_running() && kprobe_fault_handler(regs, 14)) 70 ret = 1; 71 preempt_enable(); 72 } 73 return ret; 74 } 75 76 77 /* 78 * Unlock any spinlocks which will prevent us from getting the 79 * message out. 80 */ 81 void bust_spinlocks(int yes) 82 { 83 if (yes) { 84 oops_in_progress = 1; 85 } else { 86 int loglevel_save = console_loglevel; 87 console_unblank(); 88 oops_in_progress = 0; 89 /* 90 * OK, the message is on the console. Now we call printk() 91 * without oops_in_progress set so that printk will give klogd 92 * a poke. Hold onto your hats... 93 */ 94 console_loglevel = 15; 95 printk(" "); 96 console_loglevel = loglevel_save; 97 } 98 } 99 100 /* 101 * Returns the address space associated with the fault. 102 * Returns 0 for kernel space and 1 for user space. 103 */ 104 static inline int user_space_fault(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 &= 3; 111 if (trans_exc_code == 2) 112 /* Access via secondary space, set_fs setting decides */ 113 return current->thread.mm_segment.ar4; 114 if (addressing_mode == HOME_SPACE_MODE) 115 /* User space if the access has been done via home space. */ 116 return trans_exc_code == 3; 117 /* 118 * If the user space is not the home space the kernel runs in home 119 * space. Access via secondary space has already been covered, 120 * access via primary space or access register is from user space 121 * and access via home space is from the kernel. 122 */ 123 return trans_exc_code != 3; 124 } 125 126 static inline void report_user_fault(struct pt_regs *regs, long signr) 127 { 128 if ((task_pid_nr(current) > 1) && !show_unhandled_signals) 129 return; 130 if (!unhandled_signal(current, signr)) 131 return; 132 if (!printk_ratelimit()) 133 return; 134 printk(KERN_ALERT "User process fault: interruption code 0x%X ", 135 regs->int_code); 136 print_vma_addr(KERN_CONT "in ", regs->psw.addr & PSW_ADDR_INSN); 137 printk(KERN_CONT "\n"); 138 printk(KERN_ALERT "failing address: %lX\n", 139 regs->int_parm_long & __FAIL_ADDR_MASK); 140 show_regs(regs); 141 } 142 143 /* 144 * Send SIGSEGV to task. This is an external routine 145 * to keep the stack usage of do_page_fault small. 146 */ 147 static noinline void do_sigsegv(struct pt_regs *regs, int si_code) 148 { 149 struct siginfo si; 150 151 report_user_fault(regs, SIGSEGV); 152 si.si_signo = SIGSEGV; 153 si.si_code = si_code; 154 si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK); 155 force_sig_info(SIGSEGV, &si, current); 156 } 157 158 static noinline void do_no_context(struct pt_regs *regs) 159 { 160 const struct exception_table_entry *fixup; 161 unsigned long address; 162 163 /* Are we prepared to handle this kernel fault? */ 164 fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN); 165 if (fixup) { 166 regs->psw.addr = fixup->fixup | PSW_ADDR_AMODE; 167 return; 168 } 169 170 /* 171 * Oops. The kernel tried to access some bad page. We'll have to 172 * terminate things with extreme prejudice. 173 */ 174 address = regs->int_parm_long & __FAIL_ADDR_MASK; 175 if (!user_space_fault(regs->int_parm_long)) 176 printk(KERN_ALERT "Unable to handle kernel pointer dereference" 177 " at virtual kernel address %p\n", (void *)address); 178 else 179 printk(KERN_ALERT "Unable to handle kernel paging request" 180 " at virtual user address %p\n", (void *)address); 181 182 die(regs, "Oops"); 183 do_exit(SIGKILL); 184 } 185 186 static noinline void do_low_address(struct pt_regs *regs) 187 { 188 /* Low-address protection hit in kernel mode means 189 NULL pointer write access in kernel mode. */ 190 if (regs->psw.mask & PSW_MASK_PSTATE) { 191 /* Low-address protection hit in user mode 'cannot happen'. */ 192 die (regs, "Low-address protection"); 193 do_exit(SIGKILL); 194 } 195 196 do_no_context(regs); 197 } 198 199 static noinline void do_sigbus(struct pt_regs *regs) 200 { 201 struct task_struct *tsk = current; 202 struct siginfo si; 203 204 /* 205 * Send a sigbus, regardless of whether we were in kernel 206 * or user mode. 207 */ 208 si.si_signo = SIGBUS; 209 si.si_errno = 0; 210 si.si_code = BUS_ADRERR; 211 si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK); 212 force_sig_info(SIGBUS, &si, tsk); 213 } 214 215 static noinline void do_fault_error(struct pt_regs *regs, int fault) 216 { 217 int si_code; 218 219 switch (fault) { 220 case VM_FAULT_BADACCESS: 221 case VM_FAULT_BADMAP: 222 /* Bad memory access. Check if it is kernel or user space. */ 223 if (user_mode(regs)) { 224 /* User mode accesses just cause a SIGSEGV */ 225 si_code = (fault == VM_FAULT_BADMAP) ? 226 SEGV_MAPERR : SEGV_ACCERR; 227 do_sigsegv(regs, si_code); 228 return; 229 } 230 case VM_FAULT_BADCONTEXT: 231 do_no_context(regs); 232 break; 233 case VM_FAULT_SIGNAL: 234 if (!user_mode(regs)) 235 do_no_context(regs); 236 break; 237 default: /* fault & VM_FAULT_ERROR */ 238 if (fault & VM_FAULT_OOM) { 239 if (!user_mode(regs)) 240 do_no_context(regs); 241 else 242 pagefault_out_of_memory(); 243 } else if (fault & VM_FAULT_SIGBUS) { 244 /* Kernel mode? Handle exceptions or die */ 245 if (!user_mode(regs)) 246 do_no_context(regs); 247 else 248 do_sigbus(regs); 249 } else 250 BUG(); 251 break; 252 } 253 } 254 255 /* 256 * This routine handles page faults. It determines the address, 257 * and the problem, and then passes it off to one of the appropriate 258 * routines. 259 * 260 * interruption code (int_code): 261 * 04 Protection -> Write-Protection (suprression) 262 * 10 Segment translation -> Not present (nullification) 263 * 11 Page translation -> Not present (nullification) 264 * 3b Region third trans. -> Not present (nullification) 265 */ 266 static inline int do_exception(struct pt_regs *regs, int access) 267 { 268 struct task_struct *tsk; 269 struct mm_struct *mm; 270 struct vm_area_struct *vma; 271 unsigned long trans_exc_code; 272 unsigned long address; 273 unsigned int flags; 274 int fault; 275 276 if (notify_page_fault(regs)) 277 return 0; 278 279 tsk = current; 280 mm = tsk->mm; 281 trans_exc_code = regs->int_parm_long; 282 283 /* 284 * Verify that the fault happened in user space, that 285 * we are not in an interrupt and that there is a 286 * user context. 287 */ 288 fault = VM_FAULT_BADCONTEXT; 289 if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm)) 290 goto out; 291 292 address = trans_exc_code & __FAIL_ADDR_MASK; 293 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 294 flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; 295 if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400) 296 flags |= FAULT_FLAG_WRITE; 297 down_read(&mm->mmap_sem); 298 299 #ifdef CONFIG_PGSTE 300 if ((current->flags & PF_VCPU) && S390_lowcore.gmap) { 301 address = __gmap_fault(address, 302 (struct gmap *) S390_lowcore.gmap); 303 if (address == -EFAULT) { 304 fault = VM_FAULT_BADMAP; 305 goto out_up; 306 } 307 if (address == -ENOMEM) { 308 fault = VM_FAULT_OOM; 309 goto out_up; 310 } 311 } 312 #endif 313 314 retry: 315 fault = VM_FAULT_BADMAP; 316 vma = find_vma(mm, address); 317 if (!vma) 318 goto out_up; 319 320 if (unlikely(vma->vm_start > address)) { 321 if (!(vma->vm_flags & VM_GROWSDOWN)) 322 goto out_up; 323 if (expand_stack(vma, address)) 324 goto out_up; 325 } 326 327 /* 328 * Ok, we have a good vm_area for this memory access, so 329 * we can handle it.. 330 */ 331 fault = VM_FAULT_BADACCESS; 332 if (unlikely(!(vma->vm_flags & access))) 333 goto out_up; 334 335 if (is_vm_hugetlb_page(vma)) 336 address &= HPAGE_MASK; 337 /* 338 * If for any reason at all we couldn't handle the fault, 339 * make sure we exit gracefully rather than endlessly redo 340 * the fault. 341 */ 342 fault = handle_mm_fault(mm, vma, address, flags); 343 /* No reason to continue if interrupted by SIGKILL. */ 344 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) { 345 fault = VM_FAULT_SIGNAL; 346 goto out; 347 } 348 if (unlikely(fault & VM_FAULT_ERROR)) 349 goto out_up; 350 351 /* 352 * Major/minor page fault accounting is only done on the 353 * initial attempt. If we go through a retry, it is extremely 354 * likely that the page will be found in page cache at that point. 355 */ 356 if (flags & FAULT_FLAG_ALLOW_RETRY) { 357 if (fault & VM_FAULT_MAJOR) { 358 tsk->maj_flt++; 359 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 360 regs, address); 361 } else { 362 tsk->min_flt++; 363 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 364 regs, address); 365 } 366 if (fault & VM_FAULT_RETRY) { 367 /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk 368 * of starvation. */ 369 flags &= ~FAULT_FLAG_ALLOW_RETRY; 370 down_read(&mm->mmap_sem); 371 goto retry; 372 } 373 } 374 /* 375 * The instruction that caused the program check will 376 * be repeated. Don't signal single step via SIGTRAP. 377 */ 378 clear_tsk_thread_flag(tsk, TIF_PER_TRAP); 379 fault = 0; 380 out_up: 381 up_read(&mm->mmap_sem); 382 out: 383 return fault; 384 } 385 386 void __kprobes do_protection_exception(struct pt_regs *regs) 387 { 388 unsigned long trans_exc_code; 389 int fault; 390 391 trans_exc_code = regs->int_parm_long; 392 /* Protection exception is suppressing, decrement psw address. */ 393 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16); 394 /* 395 * Check for low-address protection. This needs to be treated 396 * as a special case because the translation exception code 397 * field is not guaranteed to contain valid data in this case. 398 */ 399 if (unlikely(!(trans_exc_code & 4))) { 400 do_low_address(regs); 401 return; 402 } 403 fault = do_exception(regs, VM_WRITE); 404 if (unlikely(fault)) 405 do_fault_error(regs, fault); 406 } 407 408 void __kprobes do_dat_exception(struct pt_regs *regs) 409 { 410 int access, fault; 411 412 access = VM_READ | VM_EXEC | VM_WRITE; 413 fault = do_exception(regs, access); 414 if (unlikely(fault)) 415 do_fault_error(regs, fault); 416 } 417 418 #ifdef CONFIG_64BIT 419 void __kprobes do_asce_exception(struct pt_regs *regs) 420 { 421 struct mm_struct *mm = current->mm; 422 struct vm_area_struct *vma; 423 unsigned long trans_exc_code; 424 425 trans_exc_code = regs->int_parm_long; 426 if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm)) 427 goto no_context; 428 429 down_read(&mm->mmap_sem); 430 vma = find_vma(mm, trans_exc_code & __FAIL_ADDR_MASK); 431 up_read(&mm->mmap_sem); 432 433 if (vma) { 434 update_mm(mm, current); 435 return; 436 } 437 438 /* User mode accesses just cause a SIGSEGV */ 439 if (user_mode(regs)) { 440 do_sigsegv(regs, SEGV_MAPERR); 441 return; 442 } 443 444 no_context: 445 do_no_context(regs); 446 } 447 #endif 448 449 int __handle_fault(unsigned long uaddr, unsigned long pgm_int_code, int write) 450 { 451 struct pt_regs regs; 452 int access, fault; 453 454 /* Emulate a uaccess fault from kernel mode. */ 455 regs.psw.mask = psw_kernel_bits | PSW_MASK_DAT | PSW_MASK_MCHECK; 456 if (!irqs_disabled()) 457 regs.psw.mask |= PSW_MASK_IO | PSW_MASK_EXT; 458 regs.psw.addr = (unsigned long) __builtin_return_address(0); 459 regs.psw.addr |= PSW_ADDR_AMODE; 460 regs.int_code = pgm_int_code; 461 regs.int_parm_long = (uaddr & PAGE_MASK) | 2; 462 access = write ? VM_WRITE : VM_READ; 463 fault = do_exception(®s, access); 464 /* 465 * Since the fault happened in kernel mode while performing a uaccess 466 * all we need to do now is emulating a fixup in case "fault" is not 467 * zero. 468 * For the calling uaccess functions this results always in -EFAULT. 469 */ 470 return fault ? -EFAULT : 0; 471 } 472 473 #ifdef CONFIG_PFAULT 474 /* 475 * 'pfault' pseudo page faults routines. 476 */ 477 static int pfault_disable; 478 479 static int __init nopfault(char *str) 480 { 481 pfault_disable = 1; 482 return 1; 483 } 484 485 __setup("nopfault", nopfault); 486 487 struct pfault_refbk { 488 u16 refdiagc; 489 u16 reffcode; 490 u16 refdwlen; 491 u16 refversn; 492 u64 refgaddr; 493 u64 refselmk; 494 u64 refcmpmk; 495 u64 reserved; 496 } __attribute__ ((packed, aligned(8))); 497 498 int pfault_init(void) 499 { 500 struct pfault_refbk refbk = { 501 .refdiagc = 0x258, 502 .reffcode = 0, 503 .refdwlen = 5, 504 .refversn = 2, 505 .refgaddr = __LC_CURRENT_PID, 506 .refselmk = 1ULL << 48, 507 .refcmpmk = 1ULL << 48, 508 .reserved = __PF_RES_FIELD }; 509 int rc; 510 511 if (pfault_disable) 512 return -1; 513 asm volatile( 514 " diag %1,%0,0x258\n" 515 "0: j 2f\n" 516 "1: la %0,8\n" 517 "2:\n" 518 EX_TABLE(0b,1b) 519 : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc"); 520 return rc; 521 } 522 523 void pfault_fini(void) 524 { 525 struct pfault_refbk refbk = { 526 .refdiagc = 0x258, 527 .reffcode = 1, 528 .refdwlen = 5, 529 .refversn = 2, 530 }; 531 532 if (pfault_disable) 533 return; 534 asm volatile( 535 " diag %0,0,0x258\n" 536 "0:\n" 537 EX_TABLE(0b,0b) 538 : : "a" (&refbk), "m" (refbk) : "cc"); 539 } 540 541 static DEFINE_SPINLOCK(pfault_lock); 542 static LIST_HEAD(pfault_list); 543 544 static void pfault_interrupt(struct ext_code ext_code, 545 unsigned int param32, unsigned long param64) 546 { 547 struct task_struct *tsk; 548 __u16 subcode; 549 pid_t pid; 550 551 /* 552 * Get the external interruption subcode & pfault 553 * initial/completion signal bit. VM stores this 554 * in the 'cpu address' field associated with the 555 * external interrupt. 556 */ 557 subcode = ext_code.subcode; 558 if ((subcode & 0xff00) != __SUBCODE_MASK) 559 return; 560 kstat_cpu(smp_processor_id()).irqs[EXTINT_PFL]++; 561 /* Get the token (= pid of the affected task). */ 562 pid = sizeof(void *) == 4 ? param32 : param64; 563 rcu_read_lock(); 564 tsk = find_task_by_pid_ns(pid, &init_pid_ns); 565 if (tsk) 566 get_task_struct(tsk); 567 rcu_read_unlock(); 568 if (!tsk) 569 return; 570 spin_lock(&pfault_lock); 571 if (subcode & 0x0080) { 572 /* signal bit is set -> a page has been swapped in by VM */ 573 if (tsk->thread.pfault_wait == 1) { 574 /* Initial interrupt was faster than the completion 575 * interrupt. pfault_wait is valid. Set pfault_wait 576 * back to zero and wake up the process. This can 577 * safely be done because the task is still sleeping 578 * and can't produce new pfaults. */ 579 tsk->thread.pfault_wait = 0; 580 list_del(&tsk->thread.list); 581 wake_up_process(tsk); 582 put_task_struct(tsk); 583 } else { 584 /* Completion interrupt was faster than initial 585 * interrupt. Set pfault_wait to -1 so the initial 586 * interrupt doesn't put the task to sleep. 587 * If the task is not running, ignore the completion 588 * interrupt since it must be a leftover of a PFAULT 589 * CANCEL operation which didn't remove all pending 590 * completion interrupts. */ 591 if (tsk->state == TASK_RUNNING) 592 tsk->thread.pfault_wait = -1; 593 } 594 } else { 595 /* signal bit not set -> a real page is missing. */ 596 if (WARN_ON_ONCE(tsk != current)) 597 goto out; 598 if (tsk->thread.pfault_wait == 1) { 599 /* Already on the list with a reference: put to sleep */ 600 __set_task_state(tsk, TASK_UNINTERRUPTIBLE); 601 set_tsk_need_resched(tsk); 602 } else if (tsk->thread.pfault_wait == -1) { 603 /* Completion interrupt was faster than the initial 604 * interrupt (pfault_wait == -1). Set pfault_wait 605 * back to zero and exit. */ 606 tsk->thread.pfault_wait = 0; 607 } else { 608 /* Initial interrupt arrived before completion 609 * interrupt. Let the task sleep. 610 * An extra task reference is needed since a different 611 * cpu may set the task state to TASK_RUNNING again 612 * before the scheduler is reached. */ 613 get_task_struct(tsk); 614 tsk->thread.pfault_wait = 1; 615 list_add(&tsk->thread.list, &pfault_list); 616 __set_task_state(tsk, TASK_UNINTERRUPTIBLE); 617 set_tsk_need_resched(tsk); 618 } 619 } 620 out: 621 spin_unlock(&pfault_lock); 622 put_task_struct(tsk); 623 } 624 625 static int __cpuinit pfault_cpu_notify(struct notifier_block *self, 626 unsigned long action, void *hcpu) 627 { 628 struct thread_struct *thread, *next; 629 struct task_struct *tsk; 630 631 switch (action) { 632 case CPU_DEAD: 633 case CPU_DEAD_FROZEN: 634 spin_lock_irq(&pfault_lock); 635 list_for_each_entry_safe(thread, next, &pfault_list, list) { 636 thread->pfault_wait = 0; 637 list_del(&thread->list); 638 tsk = container_of(thread, struct task_struct, thread); 639 wake_up_process(tsk); 640 put_task_struct(tsk); 641 } 642 spin_unlock_irq(&pfault_lock); 643 break; 644 default: 645 break; 646 } 647 return NOTIFY_OK; 648 } 649 650 static int __init pfault_irq_init(void) 651 { 652 int rc; 653 654 rc = register_external_interrupt(0x2603, pfault_interrupt); 655 if (rc) 656 goto out_extint; 657 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP; 658 if (rc) 659 goto out_pfault; 660 service_subclass_irq_register(); 661 hotcpu_notifier(pfault_cpu_notify, 0); 662 return 0; 663 664 out_pfault: 665 unregister_external_interrupt(0x2603, pfault_interrupt); 666 out_extint: 667 pfault_disable = 1; 668 return rc; 669 } 670 early_initcall(pfault_irq_init); 671 672 #endif /* CONFIG_PFAULT */ 673