1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * S390 version 4 * Copyright IBM Corp. 1999 5 * Author(s): Hartmut Penner (hp@de.ibm.com) 6 * Ulrich Weigand (uweigand@de.ibm.com) 7 * 8 * Derived from "arch/i386/mm/fault.c" 9 * Copyright (C) 1995 Linus Torvalds 10 */ 11 12 #include <linux/kernel_stat.h> 13 #include <linux/perf_event.h> 14 #include <linux/signal.h> 15 #include <linux/sched.h> 16 #include <linux/sched/debug.h> 17 #include <linux/kernel.h> 18 #include <linux/errno.h> 19 #include <linux/string.h> 20 #include <linux/types.h> 21 #include <linux/ptrace.h> 22 #include <linux/mman.h> 23 #include <linux/mm.h> 24 #include <linux/compat.h> 25 #include <linux/smp.h> 26 #include <linux/kdebug.h> 27 #include <linux/init.h> 28 #include <linux/console.h> 29 #include <linux/extable.h> 30 #include <linux/hardirq.h> 31 #include <linux/kprobes.h> 32 #include <linux/uaccess.h> 33 #include <linux/hugetlb.h> 34 #include <asm/asm-offsets.h> 35 #include <asm/diag.h> 36 #include <asm/gmap.h> 37 #include <asm/irq.h> 38 #include <asm/mmu_context.h> 39 #include <asm/facility.h> 40 #include <asm/uv.h> 41 #include "../kernel/entry.h" 42 43 #define __FAIL_ADDR_MASK -4096L 44 #define __SUBCODE_MASK 0x0600 45 #define __PF_RES_FIELD 0x8000000000000000ULL 46 47 #define VM_FAULT_BADCONTEXT ((__force vm_fault_t) 0x010000) 48 #define VM_FAULT_BADMAP ((__force vm_fault_t) 0x020000) 49 #define VM_FAULT_BADACCESS ((__force vm_fault_t) 0x040000) 50 #define VM_FAULT_SIGNAL ((__force vm_fault_t) 0x080000) 51 #define VM_FAULT_PFAULT ((__force vm_fault_t) 0x100000) 52 53 enum fault_type { 54 KERNEL_FAULT, 55 USER_FAULT, 56 GMAP_FAULT, 57 }; 58 59 static unsigned long store_indication __read_mostly; 60 61 static int __init fault_init(void) 62 { 63 if (test_facility(75)) 64 store_indication = 0xc00; 65 return 0; 66 } 67 early_initcall(fault_init); 68 69 /* 70 * Find out which address space caused the exception. 71 */ 72 static enum fault_type get_fault_type(struct pt_regs *regs) 73 { 74 unsigned long trans_exc_code; 75 76 trans_exc_code = regs->int_parm_long & 3; 77 if (likely(trans_exc_code == 0)) { 78 /* primary space exception */ 79 if (user_mode(regs)) 80 return USER_FAULT; 81 if (!IS_ENABLED(CONFIG_PGSTE)) 82 return KERNEL_FAULT; 83 if (test_pt_regs_flag(regs, PIF_GUEST_FAULT)) 84 return GMAP_FAULT; 85 return KERNEL_FAULT; 86 } 87 if (trans_exc_code == 2) 88 return USER_FAULT; 89 if (trans_exc_code == 1) { 90 /* access register mode, not used in the kernel */ 91 return USER_FAULT; 92 } 93 /* home space exception -> access via kernel ASCE */ 94 return KERNEL_FAULT; 95 } 96 97 static int bad_address(void *p) 98 { 99 unsigned long dummy; 100 101 return get_kernel_nofault(dummy, (unsigned long *)p); 102 } 103 104 static void dump_pagetable(unsigned long asce, unsigned long address) 105 { 106 unsigned long *table = __va(asce & _ASCE_ORIGIN); 107 108 pr_alert("AS:%016lx ", asce); 109 switch (asce & _ASCE_TYPE_MASK) { 110 case _ASCE_TYPE_REGION1: 111 table += (address & _REGION1_INDEX) >> _REGION1_SHIFT; 112 if (bad_address(table)) 113 goto bad; 114 pr_cont("R1:%016lx ", *table); 115 if (*table & _REGION_ENTRY_INVALID) 116 goto out; 117 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); 118 fallthrough; 119 case _ASCE_TYPE_REGION2: 120 table += (address & _REGION2_INDEX) >> _REGION2_SHIFT; 121 if (bad_address(table)) 122 goto bad; 123 pr_cont("R2:%016lx ", *table); 124 if (*table & _REGION_ENTRY_INVALID) 125 goto out; 126 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); 127 fallthrough; 128 case _ASCE_TYPE_REGION3: 129 table += (address & _REGION3_INDEX) >> _REGION3_SHIFT; 130 if (bad_address(table)) 131 goto bad; 132 pr_cont("R3:%016lx ", *table); 133 if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE)) 134 goto out; 135 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); 136 fallthrough; 137 case _ASCE_TYPE_SEGMENT: 138 table += (address & _SEGMENT_INDEX) >> _SEGMENT_SHIFT; 139 if (bad_address(table)) 140 goto bad; 141 pr_cont("S:%016lx ", *table); 142 if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE)) 143 goto out; 144 table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN); 145 } 146 table += (address & _PAGE_INDEX) >> _PAGE_SHIFT; 147 if (bad_address(table)) 148 goto bad; 149 pr_cont("P:%016lx ", *table); 150 out: 151 pr_cont("\n"); 152 return; 153 bad: 154 pr_cont("BAD\n"); 155 } 156 157 static void dump_fault_info(struct pt_regs *regs) 158 { 159 unsigned long asce; 160 161 pr_alert("Failing address: %016lx TEID: %016lx\n", 162 regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long); 163 pr_alert("Fault in "); 164 switch (regs->int_parm_long & 3) { 165 case 3: 166 pr_cont("home space "); 167 break; 168 case 2: 169 pr_cont("secondary space "); 170 break; 171 case 1: 172 pr_cont("access register "); 173 break; 174 case 0: 175 pr_cont("primary space "); 176 break; 177 } 178 pr_cont("mode while using "); 179 switch (get_fault_type(regs)) { 180 case USER_FAULT: 181 asce = S390_lowcore.user_asce; 182 pr_cont("user "); 183 break; 184 case GMAP_FAULT: 185 asce = ((struct gmap *) S390_lowcore.gmap)->asce; 186 pr_cont("gmap "); 187 break; 188 case KERNEL_FAULT: 189 asce = S390_lowcore.kernel_asce; 190 pr_cont("kernel "); 191 break; 192 default: 193 unreachable(); 194 } 195 pr_cont("ASCE.\n"); 196 dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK); 197 } 198 199 int show_unhandled_signals = 1; 200 201 void report_user_fault(struct pt_regs *regs, long signr, int is_mm_fault) 202 { 203 if ((task_pid_nr(current) > 1) && !show_unhandled_signals) 204 return; 205 if (!unhandled_signal(current, signr)) 206 return; 207 if (!printk_ratelimit()) 208 return; 209 printk(KERN_ALERT "User process fault: interruption code %04x ilc:%d ", 210 regs->int_code & 0xffff, regs->int_code >> 17); 211 print_vma_addr(KERN_CONT "in ", regs->psw.addr); 212 printk(KERN_CONT "\n"); 213 if (is_mm_fault) 214 dump_fault_info(regs); 215 show_regs(regs); 216 } 217 218 /* 219 * Send SIGSEGV to task. This is an external routine 220 * to keep the stack usage of do_page_fault small. 221 */ 222 static noinline void do_sigsegv(struct pt_regs *regs, int si_code) 223 { 224 report_user_fault(regs, SIGSEGV, 1); 225 force_sig_fault(SIGSEGV, si_code, 226 (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK)); 227 } 228 229 const struct exception_table_entry *s390_search_extables(unsigned long addr) 230 { 231 const struct exception_table_entry *fixup; 232 233 fixup = search_extable(__start_dma_ex_table, 234 __stop_dma_ex_table - __start_dma_ex_table, 235 addr); 236 if (!fixup) 237 fixup = search_exception_tables(addr); 238 return fixup; 239 } 240 241 static noinline void do_no_context(struct pt_regs *regs) 242 { 243 const struct exception_table_entry *fixup; 244 245 /* Are we prepared to handle this kernel fault? */ 246 fixup = s390_search_extables(regs->psw.addr); 247 if (fixup && ex_handle(fixup, regs)) 248 return; 249 250 /* 251 * Oops. The kernel tried to access some bad page. We'll have to 252 * terminate things with extreme prejudice. 253 */ 254 if (get_fault_type(regs) == KERNEL_FAULT) 255 printk(KERN_ALERT "Unable to handle kernel pointer dereference" 256 " in virtual kernel address space\n"); 257 else 258 printk(KERN_ALERT "Unable to handle kernel paging request" 259 " in virtual user address space\n"); 260 dump_fault_info(regs); 261 die(regs, "Oops"); 262 do_exit(SIGKILL); 263 } 264 265 static noinline void do_low_address(struct pt_regs *regs) 266 { 267 /* Low-address protection hit in kernel mode means 268 NULL pointer write access in kernel mode. */ 269 if (regs->psw.mask & PSW_MASK_PSTATE) { 270 /* Low-address protection hit in user mode 'cannot happen'. */ 271 die (regs, "Low-address protection"); 272 do_exit(SIGKILL); 273 } 274 275 do_no_context(regs); 276 } 277 278 static noinline void do_sigbus(struct pt_regs *regs) 279 { 280 /* 281 * Send a sigbus, regardless of whether we were in kernel 282 * or user mode. 283 */ 284 force_sig_fault(SIGBUS, BUS_ADRERR, 285 (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK)); 286 } 287 288 static noinline int signal_return(struct pt_regs *regs) 289 { 290 u16 instruction; 291 int rc; 292 293 rc = __get_user(instruction, (u16 __user *) regs->psw.addr); 294 if (rc) 295 return rc; 296 if (instruction == 0x0a77) { 297 set_pt_regs_flag(regs, PIF_SYSCALL); 298 regs->int_code = 0x00040077; 299 return 0; 300 } else if (instruction == 0x0aad) { 301 set_pt_regs_flag(regs, PIF_SYSCALL); 302 regs->int_code = 0x000400ad; 303 return 0; 304 } 305 return -EACCES; 306 } 307 308 static noinline void do_fault_error(struct pt_regs *regs, int access, 309 vm_fault_t fault) 310 { 311 int si_code; 312 313 switch (fault) { 314 case VM_FAULT_BADACCESS: 315 if (access == VM_EXEC && signal_return(regs) == 0) 316 break; 317 fallthrough; 318 case VM_FAULT_BADMAP: 319 /* Bad memory access. Check if it is kernel or user space. */ 320 if (user_mode(regs)) { 321 /* User mode accesses just cause a SIGSEGV */ 322 si_code = (fault == VM_FAULT_BADMAP) ? 323 SEGV_MAPERR : SEGV_ACCERR; 324 do_sigsegv(regs, si_code); 325 break; 326 } 327 fallthrough; 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 (suppression) 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 vm_fault_t do_exception(struct pt_regs *regs, int access) 372 { 373 struct gmap *gmap; 374 struct task_struct *tsk; 375 struct mm_struct *mm; 376 struct vm_area_struct *vma; 377 enum fault_type type; 378 unsigned long trans_exc_code; 379 unsigned long address; 380 unsigned int flags; 381 vm_fault_t fault; 382 383 tsk = current; 384 /* 385 * The instruction that caused the program check has 386 * been nullified. Don't signal single step via SIGTRAP. 387 */ 388 clear_thread_flag(TIF_PER_TRAP); 389 390 if (kprobe_page_fault(regs, 14)) 391 return 0; 392 393 mm = tsk->mm; 394 trans_exc_code = regs->int_parm_long; 395 396 /* 397 * Verify that the fault happened in user space, that 398 * we are not in an interrupt and that there is a 399 * user context. 400 */ 401 fault = VM_FAULT_BADCONTEXT; 402 type = get_fault_type(regs); 403 switch (type) { 404 case KERNEL_FAULT: 405 goto out; 406 case USER_FAULT: 407 case GMAP_FAULT: 408 if (faulthandler_disabled() || !mm) 409 goto out; 410 break; 411 } 412 413 address = trans_exc_code & __FAIL_ADDR_MASK; 414 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 415 flags = FAULT_FLAG_DEFAULT; 416 if (user_mode(regs)) 417 flags |= FAULT_FLAG_USER; 418 if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400) 419 flags |= FAULT_FLAG_WRITE; 420 mmap_read_lock(mm); 421 422 gmap = NULL; 423 if (IS_ENABLED(CONFIG_PGSTE) && type == GMAP_FAULT) { 424 gmap = (struct gmap *) S390_lowcore.gmap; 425 current->thread.gmap_addr = address; 426 current->thread.gmap_write_flag = !!(flags & FAULT_FLAG_WRITE); 427 current->thread.gmap_int_code = regs->int_code & 0xffff; 428 address = __gmap_translate(gmap, address); 429 if (address == -EFAULT) { 430 fault = VM_FAULT_BADMAP; 431 goto out_up; 432 } 433 if (gmap->pfault_enabled) 434 flags |= FAULT_FLAG_RETRY_NOWAIT; 435 } 436 437 retry: 438 fault = VM_FAULT_BADMAP; 439 vma = find_vma(mm, address); 440 if (!vma) 441 goto out_up; 442 443 if (unlikely(vma->vm_start > address)) { 444 if (!(vma->vm_flags & VM_GROWSDOWN)) 445 goto out_up; 446 if (expand_stack(vma, address)) 447 goto out_up; 448 } 449 450 /* 451 * Ok, we have a good vm_area for this memory access, so 452 * we can handle it.. 453 */ 454 fault = VM_FAULT_BADACCESS; 455 if (unlikely(!(vma->vm_flags & access))) 456 goto out_up; 457 458 if (is_vm_hugetlb_page(vma)) 459 address &= HPAGE_MASK; 460 /* 461 * If for any reason at all we couldn't handle the fault, 462 * make sure we exit gracefully rather than endlessly redo 463 * the fault. 464 */ 465 fault = handle_mm_fault(vma, address, flags, regs); 466 if (fault_signal_pending(fault, regs)) { 467 fault = VM_FAULT_SIGNAL; 468 if (flags & FAULT_FLAG_RETRY_NOWAIT) 469 goto out_up; 470 goto out; 471 } 472 if (unlikely(fault & VM_FAULT_ERROR)) 473 goto out_up; 474 475 if (flags & FAULT_FLAG_ALLOW_RETRY) { 476 if (fault & VM_FAULT_RETRY) { 477 if (IS_ENABLED(CONFIG_PGSTE) && gmap && 478 (flags & FAULT_FLAG_RETRY_NOWAIT)) { 479 /* FAULT_FLAG_RETRY_NOWAIT has been set, 480 * mmap_lock has not been released */ 481 current->thread.gmap_pfault = 1; 482 fault = VM_FAULT_PFAULT; 483 goto out_up; 484 } 485 flags &= ~FAULT_FLAG_RETRY_NOWAIT; 486 flags |= FAULT_FLAG_TRIED; 487 mmap_read_lock(mm); 488 goto retry; 489 } 490 } 491 if (IS_ENABLED(CONFIG_PGSTE) && gmap) { 492 address = __gmap_link(gmap, current->thread.gmap_addr, 493 address); 494 if (address == -EFAULT) { 495 fault = VM_FAULT_BADMAP; 496 goto out_up; 497 } 498 if (address == -ENOMEM) { 499 fault = VM_FAULT_OOM; 500 goto out_up; 501 } 502 } 503 fault = 0; 504 out_up: 505 mmap_read_unlock(mm); 506 out: 507 return fault; 508 } 509 510 void do_protection_exception(struct pt_regs *regs) 511 { 512 unsigned long trans_exc_code; 513 int access; 514 vm_fault_t fault; 515 516 trans_exc_code = regs->int_parm_long; 517 /* 518 * Protection exceptions are suppressing, decrement psw address. 519 * The exception to this rule are aborted transactions, for these 520 * the PSW already points to the correct location. 521 */ 522 if (!(regs->int_code & 0x200)) 523 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16); 524 /* 525 * Check for low-address protection. This needs to be treated 526 * as a special case because the translation exception code 527 * field is not guaranteed to contain valid data in this case. 528 */ 529 if (unlikely(!(trans_exc_code & 4))) { 530 do_low_address(regs); 531 return; 532 } 533 if (unlikely(MACHINE_HAS_NX && (trans_exc_code & 0x80))) { 534 regs->int_parm_long = (trans_exc_code & ~PAGE_MASK) | 535 (regs->psw.addr & PAGE_MASK); 536 access = VM_EXEC; 537 fault = VM_FAULT_BADACCESS; 538 } else { 539 access = VM_WRITE; 540 fault = do_exception(regs, access); 541 } 542 if (unlikely(fault)) 543 do_fault_error(regs, access, fault); 544 } 545 NOKPROBE_SYMBOL(do_protection_exception); 546 547 void do_dat_exception(struct pt_regs *regs) 548 { 549 int access; 550 vm_fault_t fault; 551 552 access = VM_ACCESS_FLAGS; 553 fault = do_exception(regs, access); 554 if (unlikely(fault)) 555 do_fault_error(regs, access, fault); 556 } 557 NOKPROBE_SYMBOL(do_dat_exception); 558 559 #ifdef CONFIG_PFAULT 560 /* 561 * 'pfault' pseudo page faults routines. 562 */ 563 static int pfault_disable; 564 565 static int __init nopfault(char *str) 566 { 567 pfault_disable = 1; 568 return 1; 569 } 570 571 __setup("nopfault", nopfault); 572 573 struct pfault_refbk { 574 u16 refdiagc; 575 u16 reffcode; 576 u16 refdwlen; 577 u16 refversn; 578 u64 refgaddr; 579 u64 refselmk; 580 u64 refcmpmk; 581 u64 reserved; 582 } __attribute__ ((packed, aligned(8))); 583 584 static struct pfault_refbk pfault_init_refbk = { 585 .refdiagc = 0x258, 586 .reffcode = 0, 587 .refdwlen = 5, 588 .refversn = 2, 589 .refgaddr = __LC_LPP, 590 .refselmk = 1ULL << 48, 591 .refcmpmk = 1ULL << 48, 592 .reserved = __PF_RES_FIELD 593 }; 594 595 int pfault_init(void) 596 { 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) 609 : "a" (&pfault_init_refbk), "m" (pfault_init_refbk) : "cc"); 610 return rc; 611 } 612 613 static struct pfault_refbk pfault_fini_refbk = { 614 .refdiagc = 0x258, 615 .reffcode = 1, 616 .refdwlen = 5, 617 .refversn = 2, 618 }; 619 620 void pfault_fini(void) 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: nopr %%r7\n" 629 EX_TABLE(0b,0b) 630 : : "a" (&pfault_fini_refbk), "m" (pfault_fini_refbk) : "cc"); 631 } 632 633 static DEFINE_SPINLOCK(pfault_lock); 634 static LIST_HEAD(pfault_list); 635 636 #define PF_COMPLETE 0x0080 637 638 /* 639 * The mechanism of our pfault code: if Linux is running as guest, runs a user 640 * space process and the user space process accesses a page that the host has 641 * paged out we get a pfault interrupt. 642 * 643 * This allows us, within the guest, to schedule a different process. Without 644 * this mechanism the host would have to suspend the whole virtual cpu until 645 * the page has been paged in. 646 * 647 * So when we get such an interrupt then we set the state of the current task 648 * to uninterruptible and also set the need_resched flag. Both happens within 649 * interrupt context(!). If we later on want to return to user space we 650 * recognize the need_resched flag and then call schedule(). It's not very 651 * obvious how this works... 652 * 653 * Of course we have a lot of additional fun with the completion interrupt (-> 654 * host signals that a page of a process has been paged in and the process can 655 * continue to run). This interrupt can arrive on any cpu and, since we have 656 * virtual cpus, actually appear before the interrupt that signals that a page 657 * is missing. 658 */ 659 static void pfault_interrupt(struct ext_code ext_code, 660 unsigned int param32, unsigned long param64) 661 { 662 struct task_struct *tsk; 663 __u16 subcode; 664 pid_t pid; 665 666 /* 667 * Get the external interruption subcode & pfault initial/completion 668 * signal bit. VM stores this in the 'cpu address' field associated 669 * with the external interrupt. 670 */ 671 subcode = ext_code.subcode; 672 if ((subcode & 0xff00) != __SUBCODE_MASK) 673 return; 674 inc_irq_stat(IRQEXT_PFL); 675 /* Get the token (= pid of the affected task). */ 676 pid = param64 & LPP_PID_MASK; 677 rcu_read_lock(); 678 tsk = find_task_by_pid_ns(pid, &init_pid_ns); 679 if (tsk) 680 get_task_struct(tsk); 681 rcu_read_unlock(); 682 if (!tsk) 683 return; 684 spin_lock(&pfault_lock); 685 if (subcode & PF_COMPLETE) { 686 /* signal bit is set -> a page has been swapped in by VM */ 687 if (tsk->thread.pfault_wait == 1) { 688 /* Initial interrupt was faster than the completion 689 * interrupt. pfault_wait is valid. Set pfault_wait 690 * back to zero and wake up the process. This can 691 * safely be done because the task is still sleeping 692 * and can't produce new pfaults. */ 693 tsk->thread.pfault_wait = 0; 694 list_del(&tsk->thread.list); 695 wake_up_process(tsk); 696 put_task_struct(tsk); 697 } else { 698 /* Completion interrupt was faster than initial 699 * interrupt. Set pfault_wait to -1 so the initial 700 * interrupt doesn't put the task to sleep. 701 * If the task is not running, ignore the completion 702 * interrupt since it must be a leftover of a PFAULT 703 * CANCEL operation which didn't remove all pending 704 * completion interrupts. */ 705 if (tsk->state == TASK_RUNNING) 706 tsk->thread.pfault_wait = -1; 707 } 708 } else { 709 /* signal bit not set -> a real page is missing. */ 710 if (WARN_ON_ONCE(tsk != current)) 711 goto out; 712 if (tsk->thread.pfault_wait == 1) { 713 /* Already on the list with a reference: put to sleep */ 714 goto block; 715 } else if (tsk->thread.pfault_wait == -1) { 716 /* Completion interrupt was faster than the initial 717 * interrupt (pfault_wait == -1). Set pfault_wait 718 * back to zero and exit. */ 719 tsk->thread.pfault_wait = 0; 720 } else { 721 /* Initial interrupt arrived before completion 722 * interrupt. Let the task sleep. 723 * An extra task reference is needed since a different 724 * cpu may set the task state to TASK_RUNNING again 725 * before the scheduler is reached. */ 726 get_task_struct(tsk); 727 tsk->thread.pfault_wait = 1; 728 list_add(&tsk->thread.list, &pfault_list); 729 block: 730 /* Since this must be a userspace fault, there 731 * is no kernel task state to trample. Rely on the 732 * return to userspace schedule() to block. */ 733 __set_current_state(TASK_UNINTERRUPTIBLE); 734 set_tsk_need_resched(tsk); 735 set_preempt_need_resched(); 736 } 737 } 738 out: 739 spin_unlock(&pfault_lock); 740 put_task_struct(tsk); 741 } 742 743 static int pfault_cpu_dead(unsigned int cpu) 744 { 745 struct thread_struct *thread, *next; 746 struct task_struct *tsk; 747 748 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 return 0; 758 } 759 760 static int __init pfault_irq_init(void) 761 { 762 int rc; 763 764 rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); 765 if (rc) 766 goto out_extint; 767 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP; 768 if (rc) 769 goto out_pfault; 770 irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL); 771 cpuhp_setup_state_nocalls(CPUHP_S390_PFAULT_DEAD, "s390/pfault:dead", 772 NULL, pfault_cpu_dead); 773 return 0; 774 775 out_pfault: 776 unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); 777 out_extint: 778 pfault_disable = 1; 779 return rc; 780 } 781 early_initcall(pfault_irq_init); 782 783 #endif /* CONFIG_PFAULT */ 784 785 #if IS_ENABLED(CONFIG_PGSTE) 786 void do_secure_storage_access(struct pt_regs *regs) 787 { 788 unsigned long addr = regs->int_parm_long & __FAIL_ADDR_MASK; 789 struct vm_area_struct *vma; 790 struct mm_struct *mm; 791 struct page *page; 792 int rc; 793 794 switch (get_fault_type(regs)) { 795 case USER_FAULT: 796 mm = current->mm; 797 mmap_read_lock(mm); 798 vma = find_vma(mm, addr); 799 if (!vma) { 800 mmap_read_unlock(mm); 801 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP); 802 break; 803 } 804 page = follow_page(vma, addr, FOLL_WRITE | FOLL_GET); 805 if (IS_ERR_OR_NULL(page)) { 806 mmap_read_unlock(mm); 807 break; 808 } 809 if (arch_make_page_accessible(page)) 810 send_sig(SIGSEGV, current, 0); 811 put_page(page); 812 mmap_read_unlock(mm); 813 break; 814 case KERNEL_FAULT: 815 page = phys_to_page(addr); 816 if (unlikely(!try_get_page(page))) 817 break; 818 rc = arch_make_page_accessible(page); 819 put_page(page); 820 if (rc) 821 BUG(); 822 break; 823 case GMAP_FAULT: 824 default: 825 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP); 826 WARN_ON_ONCE(1); 827 } 828 } 829 NOKPROBE_SYMBOL(do_secure_storage_access); 830 831 void do_non_secure_storage_access(struct pt_regs *regs) 832 { 833 unsigned long gaddr = regs->int_parm_long & __FAIL_ADDR_MASK; 834 struct gmap *gmap = (struct gmap *)S390_lowcore.gmap; 835 836 if (get_fault_type(regs) != GMAP_FAULT) { 837 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP); 838 WARN_ON_ONCE(1); 839 return; 840 } 841 842 if (gmap_convert_to_secure(gmap, gaddr) == -EINVAL) 843 send_sig(SIGSEGV, current, 0); 844 } 845 NOKPROBE_SYMBOL(do_non_secure_storage_access); 846 847 void do_secure_storage_violation(struct pt_regs *regs) 848 { 849 /* 850 * Either KVM messed up the secure guest mapping or the same 851 * page is mapped into multiple secure guests. 852 * 853 * This exception is only triggered when a guest 2 is running 854 * and can therefore never occur in kernel context. 855 */ 856 printk_ratelimited(KERN_WARNING 857 "Secure storage violation in task: %s, pid %d\n", 858 current->comm, current->pid); 859 send_sig(SIGSEGV, current, 0); 860 } 861 862 #else 863 void do_secure_storage_access(struct pt_regs *regs) 864 { 865 default_trap_handler(regs); 866 } 867 868 void do_non_secure_storage_access(struct pt_regs *regs) 869 { 870 default_trap_handler(regs); 871 } 872 873 void do_secure_storage_violation(struct pt_regs *regs) 874 { 875 default_trap_handler(regs); 876 } 877 #endif 878