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 VDSO_FAULT, 57 GMAP_FAULT, 58 }; 59 60 static unsigned long store_indication __read_mostly; 61 62 static int __init fault_init(void) 63 { 64 if (test_facility(75)) 65 store_indication = 0xc00; 66 return 0; 67 } 68 early_initcall(fault_init); 69 70 /* 71 * Find out which address space caused the exception. 72 */ 73 static enum fault_type get_fault_type(struct pt_regs *regs) 74 { 75 unsigned long trans_exc_code; 76 77 trans_exc_code = regs->int_parm_long & 3; 78 if (likely(trans_exc_code == 0)) { 79 /* primary space exception */ 80 if (IS_ENABLED(CONFIG_PGSTE) && 81 test_pt_regs_flag(regs, PIF_GUEST_FAULT)) 82 return GMAP_FAULT; 83 if (current->thread.mm_segment == USER_DS) 84 return USER_FAULT; 85 return KERNEL_FAULT; 86 } 87 if (trans_exc_code == 2) { 88 /* secondary space exception */ 89 if (current->thread.mm_segment & 1) { 90 if (current->thread.mm_segment == USER_DS_SACF) 91 return USER_FAULT; 92 return KERNEL_FAULT; 93 } 94 return VDSO_FAULT; 95 } 96 if (trans_exc_code == 1) { 97 /* access register mode, not used in the kernel */ 98 return USER_FAULT; 99 } 100 /* home space exception -> access via kernel ASCE */ 101 return KERNEL_FAULT; 102 } 103 104 static int bad_address(void *p) 105 { 106 unsigned long dummy; 107 108 return get_kernel_nofault(dummy, (unsigned long *)p); 109 } 110 111 static void dump_pagetable(unsigned long asce, unsigned long address) 112 { 113 unsigned long *table = __va(asce & _ASCE_ORIGIN); 114 115 pr_alert("AS:%016lx ", asce); 116 switch (asce & _ASCE_TYPE_MASK) { 117 case _ASCE_TYPE_REGION1: 118 table += (address & _REGION1_INDEX) >> _REGION1_SHIFT; 119 if (bad_address(table)) 120 goto bad; 121 pr_cont("R1:%016lx ", *table); 122 if (*table & _REGION_ENTRY_INVALID) 123 goto out; 124 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); 125 fallthrough; 126 case _ASCE_TYPE_REGION2: 127 table += (address & _REGION2_INDEX) >> _REGION2_SHIFT; 128 if (bad_address(table)) 129 goto bad; 130 pr_cont("R2:%016lx ", *table); 131 if (*table & _REGION_ENTRY_INVALID) 132 goto out; 133 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); 134 fallthrough; 135 case _ASCE_TYPE_REGION3: 136 table += (address & _REGION3_INDEX) >> _REGION3_SHIFT; 137 if (bad_address(table)) 138 goto bad; 139 pr_cont("R3:%016lx ", *table); 140 if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE)) 141 goto out; 142 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); 143 fallthrough; 144 case _ASCE_TYPE_SEGMENT: 145 table += (address & _SEGMENT_INDEX) >> _SEGMENT_SHIFT; 146 if (bad_address(table)) 147 goto bad; 148 pr_cont("S:%016lx ", *table); 149 if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE)) 150 goto out; 151 table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN); 152 } 153 table += (address & _PAGE_INDEX) >> _PAGE_SHIFT; 154 if (bad_address(table)) 155 goto bad; 156 pr_cont("P:%016lx ", *table); 157 out: 158 pr_cont("\n"); 159 return; 160 bad: 161 pr_cont("BAD\n"); 162 } 163 164 static void dump_fault_info(struct pt_regs *regs) 165 { 166 unsigned long asce; 167 168 pr_alert("Failing address: %016lx TEID: %016lx\n", 169 regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long); 170 pr_alert("Fault in "); 171 switch (regs->int_parm_long & 3) { 172 case 3: 173 pr_cont("home space "); 174 break; 175 case 2: 176 pr_cont("secondary space "); 177 break; 178 case 1: 179 pr_cont("access register "); 180 break; 181 case 0: 182 pr_cont("primary space "); 183 break; 184 } 185 pr_cont("mode while using "); 186 switch (get_fault_type(regs)) { 187 case USER_FAULT: 188 asce = S390_lowcore.user_asce; 189 pr_cont("user "); 190 break; 191 case VDSO_FAULT: 192 asce = S390_lowcore.vdso_asce; 193 pr_cont("vdso "); 194 break; 195 case GMAP_FAULT: 196 asce = ((struct gmap *) S390_lowcore.gmap)->asce; 197 pr_cont("gmap "); 198 break; 199 case KERNEL_FAULT: 200 asce = S390_lowcore.kernel_asce; 201 pr_cont("kernel "); 202 break; 203 default: 204 unreachable(); 205 } 206 pr_cont("ASCE.\n"); 207 dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK); 208 } 209 210 int show_unhandled_signals = 1; 211 212 void report_user_fault(struct pt_regs *regs, long signr, int is_mm_fault) 213 { 214 if ((task_pid_nr(current) > 1) && !show_unhandled_signals) 215 return; 216 if (!unhandled_signal(current, signr)) 217 return; 218 if (!printk_ratelimit()) 219 return; 220 printk(KERN_ALERT "User process fault: interruption code %04x ilc:%d ", 221 regs->int_code & 0xffff, regs->int_code >> 17); 222 print_vma_addr(KERN_CONT "in ", regs->psw.addr); 223 printk(KERN_CONT "\n"); 224 if (is_mm_fault) 225 dump_fault_info(regs); 226 show_regs(regs); 227 } 228 229 /* 230 * Send SIGSEGV to task. This is an external routine 231 * to keep the stack usage of do_page_fault small. 232 */ 233 static noinline void do_sigsegv(struct pt_regs *regs, int si_code) 234 { 235 report_user_fault(regs, SIGSEGV, 1); 236 force_sig_fault(SIGSEGV, si_code, 237 (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK)); 238 } 239 240 const struct exception_table_entry *s390_search_extables(unsigned long addr) 241 { 242 const struct exception_table_entry *fixup; 243 244 fixup = search_extable(__start_dma_ex_table, 245 __stop_dma_ex_table - __start_dma_ex_table, 246 addr); 247 if (!fixup) 248 fixup = search_exception_tables(addr); 249 return fixup; 250 } 251 252 static noinline void do_no_context(struct pt_regs *regs) 253 { 254 const struct exception_table_entry *fixup; 255 256 /* Are we prepared to handle this kernel fault? */ 257 fixup = s390_search_extables(regs->psw.addr); 258 if (fixup && ex_handle(fixup, regs)) 259 return; 260 261 /* 262 * Oops. The kernel tried to access some bad page. We'll have to 263 * terminate things with extreme prejudice. 264 */ 265 if (get_fault_type(regs) == KERNEL_FAULT) 266 printk(KERN_ALERT "Unable to handle kernel pointer dereference" 267 " in virtual kernel address space\n"); 268 else 269 printk(KERN_ALERT "Unable to handle kernel paging request" 270 " in virtual user address space\n"); 271 dump_fault_info(regs); 272 die(regs, "Oops"); 273 do_exit(SIGKILL); 274 } 275 276 static noinline void do_low_address(struct pt_regs *regs) 277 { 278 /* Low-address protection hit in kernel mode means 279 NULL pointer write access in kernel mode. */ 280 if (regs->psw.mask & PSW_MASK_PSTATE) { 281 /* Low-address protection hit in user mode 'cannot happen'. */ 282 die (regs, "Low-address protection"); 283 do_exit(SIGKILL); 284 } 285 286 do_no_context(regs); 287 } 288 289 static noinline void do_sigbus(struct pt_regs *regs) 290 { 291 /* 292 * Send a sigbus, regardless of whether we were in kernel 293 * or user mode. 294 */ 295 force_sig_fault(SIGBUS, BUS_ADRERR, 296 (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK)); 297 } 298 299 static noinline int signal_return(struct pt_regs *regs) 300 { 301 u16 instruction; 302 int rc; 303 304 rc = __get_user(instruction, (u16 __user *) regs->psw.addr); 305 if (rc) 306 return rc; 307 if (instruction == 0x0a77) { 308 set_pt_regs_flag(regs, PIF_SYSCALL); 309 regs->int_code = 0x00040077; 310 return 0; 311 } else if (instruction == 0x0aad) { 312 set_pt_regs_flag(regs, PIF_SYSCALL); 313 regs->int_code = 0x000400ad; 314 return 0; 315 } 316 return -EACCES; 317 } 318 319 static noinline void do_fault_error(struct pt_regs *regs, int access, 320 vm_fault_t fault) 321 { 322 int si_code; 323 324 switch (fault) { 325 case VM_FAULT_BADACCESS: 326 if (access == VM_EXEC && signal_return(regs) == 0) 327 break; 328 fallthrough; 329 case VM_FAULT_BADMAP: 330 /* Bad memory access. Check if it is kernel or user space. */ 331 if (user_mode(regs)) { 332 /* User mode accesses just cause a SIGSEGV */ 333 si_code = (fault == VM_FAULT_BADMAP) ? 334 SEGV_MAPERR : SEGV_ACCERR; 335 do_sigsegv(regs, si_code); 336 break; 337 } 338 fallthrough; 339 case VM_FAULT_BADCONTEXT: 340 case VM_FAULT_PFAULT: 341 do_no_context(regs); 342 break; 343 case VM_FAULT_SIGNAL: 344 if (!user_mode(regs)) 345 do_no_context(regs); 346 break; 347 default: /* fault & VM_FAULT_ERROR */ 348 if (fault & VM_FAULT_OOM) { 349 if (!user_mode(regs)) 350 do_no_context(regs); 351 else 352 pagefault_out_of_memory(); 353 } else if (fault & VM_FAULT_SIGSEGV) { 354 /* Kernel mode? Handle exceptions or die */ 355 if (!user_mode(regs)) 356 do_no_context(regs); 357 else 358 do_sigsegv(regs, SEGV_MAPERR); 359 } else if (fault & VM_FAULT_SIGBUS) { 360 /* Kernel mode? Handle exceptions or die */ 361 if (!user_mode(regs)) 362 do_no_context(regs); 363 else 364 do_sigbus(regs); 365 } else 366 BUG(); 367 break; 368 } 369 } 370 371 /* 372 * This routine handles page faults. It determines the address, 373 * and the problem, and then passes it off to one of the appropriate 374 * routines. 375 * 376 * interruption code (int_code): 377 * 04 Protection -> Write-Protection (suppression) 378 * 10 Segment translation -> Not present (nullification) 379 * 11 Page translation -> Not present (nullification) 380 * 3b Region third trans. -> Not present (nullification) 381 */ 382 static inline vm_fault_t do_exception(struct pt_regs *regs, int access) 383 { 384 struct gmap *gmap; 385 struct task_struct *tsk; 386 struct mm_struct *mm; 387 struct vm_area_struct *vma; 388 enum fault_type type; 389 unsigned long trans_exc_code; 390 unsigned long address; 391 unsigned int flags; 392 vm_fault_t fault; 393 394 tsk = current; 395 /* 396 * The instruction that caused the program check has 397 * been nullified. Don't signal single step via SIGTRAP. 398 */ 399 clear_pt_regs_flag(regs, PIF_PER_TRAP); 400 401 if (kprobe_page_fault(regs, 14)) 402 return 0; 403 404 mm = tsk->mm; 405 trans_exc_code = regs->int_parm_long; 406 407 /* 408 * Verify that the fault happened in user space, that 409 * we are not in an interrupt and that there is a 410 * user context. 411 */ 412 fault = VM_FAULT_BADCONTEXT; 413 type = get_fault_type(regs); 414 switch (type) { 415 case KERNEL_FAULT: 416 goto out; 417 case VDSO_FAULT: 418 fault = VM_FAULT_BADMAP; 419 goto out; 420 case USER_FAULT: 421 case GMAP_FAULT: 422 if (faulthandler_disabled() || !mm) 423 goto out; 424 break; 425 } 426 427 address = trans_exc_code & __FAIL_ADDR_MASK; 428 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 429 flags = FAULT_FLAG_DEFAULT; 430 if (user_mode(regs)) 431 flags |= FAULT_FLAG_USER; 432 if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400) 433 flags |= FAULT_FLAG_WRITE; 434 mmap_read_lock(mm); 435 436 gmap = NULL; 437 if (IS_ENABLED(CONFIG_PGSTE) && type == GMAP_FAULT) { 438 gmap = (struct gmap *) S390_lowcore.gmap; 439 current->thread.gmap_addr = address; 440 current->thread.gmap_write_flag = !!(flags & FAULT_FLAG_WRITE); 441 current->thread.gmap_int_code = regs->int_code & 0xffff; 442 address = __gmap_translate(gmap, address); 443 if (address == -EFAULT) { 444 fault = VM_FAULT_BADMAP; 445 goto out_up; 446 } 447 if (gmap->pfault_enabled) 448 flags |= FAULT_FLAG_RETRY_NOWAIT; 449 } 450 451 retry: 452 fault = VM_FAULT_BADMAP; 453 vma = find_vma(mm, address); 454 if (!vma) 455 goto out_up; 456 457 if (unlikely(vma->vm_start > address)) { 458 if (!(vma->vm_flags & VM_GROWSDOWN)) 459 goto out_up; 460 if (expand_stack(vma, address)) 461 goto out_up; 462 } 463 464 /* 465 * Ok, we have a good vm_area for this memory access, so 466 * we can handle it.. 467 */ 468 fault = VM_FAULT_BADACCESS; 469 if (unlikely(!(vma->vm_flags & access))) 470 goto out_up; 471 472 if (is_vm_hugetlb_page(vma)) 473 address &= HPAGE_MASK; 474 /* 475 * If for any reason at all we couldn't handle the fault, 476 * make sure we exit gracefully rather than endlessly redo 477 * the fault. 478 */ 479 fault = handle_mm_fault(vma, address, flags, regs); 480 if (fault_signal_pending(fault, regs)) { 481 fault = VM_FAULT_SIGNAL; 482 if (flags & FAULT_FLAG_RETRY_NOWAIT) 483 goto out_up; 484 goto out; 485 } 486 if (unlikely(fault & VM_FAULT_ERROR)) 487 goto out_up; 488 489 if (flags & FAULT_FLAG_ALLOW_RETRY) { 490 if (fault & VM_FAULT_RETRY) { 491 if (IS_ENABLED(CONFIG_PGSTE) && gmap && 492 (flags & FAULT_FLAG_RETRY_NOWAIT)) { 493 /* FAULT_FLAG_RETRY_NOWAIT has been set, 494 * mmap_lock has not been released */ 495 current->thread.gmap_pfault = 1; 496 fault = VM_FAULT_PFAULT; 497 goto out_up; 498 } 499 flags &= ~FAULT_FLAG_RETRY_NOWAIT; 500 flags |= FAULT_FLAG_TRIED; 501 mmap_read_lock(mm); 502 goto retry; 503 } 504 } 505 if (IS_ENABLED(CONFIG_PGSTE) && 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 fault = 0; 518 out_up: 519 mmap_read_unlock(mm); 520 out: 521 return fault; 522 } 523 524 void do_protection_exception(struct pt_regs *regs) 525 { 526 unsigned long trans_exc_code; 527 int access; 528 vm_fault_t 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 if (unlikely(MACHINE_HAS_NX && (trans_exc_code & 0x80))) { 548 regs->int_parm_long = (trans_exc_code & ~PAGE_MASK) | 549 (regs->psw.addr & PAGE_MASK); 550 access = VM_EXEC; 551 fault = VM_FAULT_BADACCESS; 552 } else { 553 access = VM_WRITE; 554 fault = do_exception(regs, access); 555 } 556 if (unlikely(fault)) 557 do_fault_error(regs, access, fault); 558 } 559 NOKPROBE_SYMBOL(do_protection_exception); 560 561 void do_dat_exception(struct pt_regs *regs) 562 { 563 int access; 564 vm_fault_t fault; 565 566 access = VM_ACCESS_FLAGS; 567 fault = do_exception(regs, access); 568 if (unlikely(fault)) 569 do_fault_error(regs, access, fault); 570 } 571 NOKPROBE_SYMBOL(do_dat_exception); 572 573 #ifdef CONFIG_PFAULT 574 /* 575 * 'pfault' pseudo page faults routines. 576 */ 577 static int pfault_disable; 578 579 static int __init nopfault(char *str) 580 { 581 pfault_disable = 1; 582 return 1; 583 } 584 585 __setup("nopfault", nopfault); 586 587 struct pfault_refbk { 588 u16 refdiagc; 589 u16 reffcode; 590 u16 refdwlen; 591 u16 refversn; 592 u64 refgaddr; 593 u64 refselmk; 594 u64 refcmpmk; 595 u64 reserved; 596 } __attribute__ ((packed, aligned(8))); 597 598 static struct pfault_refbk pfault_init_refbk = { 599 .refdiagc = 0x258, 600 .reffcode = 0, 601 .refdwlen = 5, 602 .refversn = 2, 603 .refgaddr = __LC_LPP, 604 .refselmk = 1ULL << 48, 605 .refcmpmk = 1ULL << 48, 606 .reserved = __PF_RES_FIELD 607 }; 608 609 int pfault_init(void) 610 { 611 int rc; 612 613 if (pfault_disable) 614 return -1; 615 diag_stat_inc(DIAG_STAT_X258); 616 asm volatile( 617 " diag %1,%0,0x258\n" 618 "0: j 2f\n" 619 "1: la %0,8\n" 620 "2:\n" 621 EX_TABLE(0b,1b) 622 : "=d" (rc) 623 : "a" (&pfault_init_refbk), "m" (pfault_init_refbk) : "cc"); 624 return rc; 625 } 626 627 static struct pfault_refbk pfault_fini_refbk = { 628 .refdiagc = 0x258, 629 .reffcode = 1, 630 .refdwlen = 5, 631 .refversn = 2, 632 }; 633 634 void pfault_fini(void) 635 { 636 637 if (pfault_disable) 638 return; 639 diag_stat_inc(DIAG_STAT_X258); 640 asm volatile( 641 " diag %0,0,0x258\n" 642 "0: nopr %%r7\n" 643 EX_TABLE(0b,0b) 644 : : "a" (&pfault_fini_refbk), "m" (pfault_fini_refbk) : "cc"); 645 } 646 647 static DEFINE_SPINLOCK(pfault_lock); 648 static LIST_HEAD(pfault_list); 649 650 #define PF_COMPLETE 0x0080 651 652 /* 653 * The mechanism of our pfault code: if Linux is running as guest, runs a user 654 * space process and the user space process accesses a page that the host has 655 * paged out we get a pfault interrupt. 656 * 657 * This allows us, within the guest, to schedule a different process. Without 658 * this mechanism the host would have to suspend the whole virtual cpu until 659 * the page has been paged in. 660 * 661 * So when we get such an interrupt then we set the state of the current task 662 * to uninterruptible and also set the need_resched flag. Both happens within 663 * interrupt context(!). If we later on want to return to user space we 664 * recognize the need_resched flag and then call schedule(). It's not very 665 * obvious how this works... 666 * 667 * Of course we have a lot of additional fun with the completion interrupt (-> 668 * host signals that a page of a process has been paged in and the process can 669 * continue to run). This interrupt can arrive on any cpu and, since we have 670 * virtual cpus, actually appear before the interrupt that signals that a page 671 * is missing. 672 */ 673 static void pfault_interrupt(struct ext_code ext_code, 674 unsigned int param32, unsigned long param64) 675 { 676 struct task_struct *tsk; 677 __u16 subcode; 678 pid_t pid; 679 680 /* 681 * Get the external interruption subcode & pfault initial/completion 682 * signal bit. VM stores this in the 'cpu address' field associated 683 * with the external interrupt. 684 */ 685 subcode = ext_code.subcode; 686 if ((subcode & 0xff00) != __SUBCODE_MASK) 687 return; 688 inc_irq_stat(IRQEXT_PFL); 689 /* Get the token (= pid of the affected task). */ 690 pid = param64 & LPP_PID_MASK; 691 rcu_read_lock(); 692 tsk = find_task_by_pid_ns(pid, &init_pid_ns); 693 if (tsk) 694 get_task_struct(tsk); 695 rcu_read_unlock(); 696 if (!tsk) 697 return; 698 spin_lock(&pfault_lock); 699 if (subcode & PF_COMPLETE) { 700 /* signal bit is set -> a page has been swapped in by VM */ 701 if (tsk->thread.pfault_wait == 1) { 702 /* Initial interrupt was faster than the completion 703 * interrupt. pfault_wait is valid. Set pfault_wait 704 * back to zero and wake up the process. This can 705 * safely be done because the task is still sleeping 706 * and can't produce new pfaults. */ 707 tsk->thread.pfault_wait = 0; 708 list_del(&tsk->thread.list); 709 wake_up_process(tsk); 710 put_task_struct(tsk); 711 } else { 712 /* Completion interrupt was faster than initial 713 * interrupt. Set pfault_wait to -1 so the initial 714 * interrupt doesn't put the task to sleep. 715 * If the task is not running, ignore the completion 716 * interrupt since it must be a leftover of a PFAULT 717 * CANCEL operation which didn't remove all pending 718 * completion interrupts. */ 719 if (tsk->state == TASK_RUNNING) 720 tsk->thread.pfault_wait = -1; 721 } 722 } else { 723 /* signal bit not set -> a real page is missing. */ 724 if (WARN_ON_ONCE(tsk != current)) 725 goto out; 726 if (tsk->thread.pfault_wait == 1) { 727 /* Already on the list with a reference: put to sleep */ 728 goto block; 729 } else if (tsk->thread.pfault_wait == -1) { 730 /* Completion interrupt was faster than the initial 731 * interrupt (pfault_wait == -1). Set pfault_wait 732 * back to zero and exit. */ 733 tsk->thread.pfault_wait = 0; 734 } else { 735 /* Initial interrupt arrived before completion 736 * interrupt. Let the task sleep. 737 * An extra task reference is needed since a different 738 * cpu may set the task state to TASK_RUNNING again 739 * before the scheduler is reached. */ 740 get_task_struct(tsk); 741 tsk->thread.pfault_wait = 1; 742 list_add(&tsk->thread.list, &pfault_list); 743 block: 744 /* Since this must be a userspace fault, there 745 * is no kernel task state to trample. Rely on the 746 * return to userspace schedule() to block. */ 747 __set_current_state(TASK_UNINTERRUPTIBLE); 748 set_tsk_need_resched(tsk); 749 set_preempt_need_resched(); 750 } 751 } 752 out: 753 spin_unlock(&pfault_lock); 754 put_task_struct(tsk); 755 } 756 757 static int pfault_cpu_dead(unsigned int cpu) 758 { 759 struct thread_struct *thread, *next; 760 struct task_struct *tsk; 761 762 spin_lock_irq(&pfault_lock); 763 list_for_each_entry_safe(thread, next, &pfault_list, list) { 764 thread->pfault_wait = 0; 765 list_del(&thread->list); 766 tsk = container_of(thread, struct task_struct, thread); 767 wake_up_process(tsk); 768 put_task_struct(tsk); 769 } 770 spin_unlock_irq(&pfault_lock); 771 return 0; 772 } 773 774 static int __init pfault_irq_init(void) 775 { 776 int rc; 777 778 rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); 779 if (rc) 780 goto out_extint; 781 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP; 782 if (rc) 783 goto out_pfault; 784 irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL); 785 cpuhp_setup_state_nocalls(CPUHP_S390_PFAULT_DEAD, "s390/pfault:dead", 786 NULL, pfault_cpu_dead); 787 return 0; 788 789 out_pfault: 790 unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); 791 out_extint: 792 pfault_disable = 1; 793 return rc; 794 } 795 early_initcall(pfault_irq_init); 796 797 #endif /* CONFIG_PFAULT */ 798 799 #if IS_ENABLED(CONFIG_PGSTE) 800 void do_secure_storage_access(struct pt_regs *regs) 801 { 802 unsigned long addr = regs->int_parm_long & __FAIL_ADDR_MASK; 803 struct vm_area_struct *vma; 804 struct mm_struct *mm; 805 struct page *page; 806 int rc; 807 808 switch (get_fault_type(regs)) { 809 case USER_FAULT: 810 mm = current->mm; 811 mmap_read_lock(mm); 812 vma = find_vma(mm, addr); 813 if (!vma) { 814 mmap_read_unlock(mm); 815 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP); 816 break; 817 } 818 page = follow_page(vma, addr, FOLL_WRITE | FOLL_GET); 819 if (IS_ERR_OR_NULL(page)) { 820 mmap_read_unlock(mm); 821 break; 822 } 823 if (arch_make_page_accessible(page)) 824 send_sig(SIGSEGV, current, 0); 825 put_page(page); 826 mmap_read_unlock(mm); 827 break; 828 case KERNEL_FAULT: 829 page = phys_to_page(addr); 830 if (unlikely(!try_get_page(page))) 831 break; 832 rc = arch_make_page_accessible(page); 833 put_page(page); 834 if (rc) 835 BUG(); 836 break; 837 case VDSO_FAULT: 838 case GMAP_FAULT: 839 default: 840 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP); 841 WARN_ON_ONCE(1); 842 } 843 } 844 NOKPROBE_SYMBOL(do_secure_storage_access); 845 846 void do_non_secure_storage_access(struct pt_regs *regs) 847 { 848 unsigned long gaddr = regs->int_parm_long & __FAIL_ADDR_MASK; 849 struct gmap *gmap = (struct gmap *)S390_lowcore.gmap; 850 851 if (get_fault_type(regs) != GMAP_FAULT) { 852 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP); 853 WARN_ON_ONCE(1); 854 return; 855 } 856 857 if (gmap_convert_to_secure(gmap, gaddr) == -EINVAL) 858 send_sig(SIGSEGV, current, 0); 859 } 860 NOKPROBE_SYMBOL(do_non_secure_storage_access); 861 862 void do_secure_storage_violation(struct pt_regs *regs) 863 { 864 /* 865 * Either KVM messed up the secure guest mapping or the same 866 * page is mapped into multiple secure guests. 867 * 868 * This exception is only triggered when a guest 2 is running 869 * and can therefore never occur in kernel context. 870 */ 871 printk_ratelimited(KERN_WARNING 872 "Secure storage violation in task: %s, pid %d\n", 873 current->comm, current->pid); 874 send_sig(SIGSEGV, current, 0); 875 } 876 877 #else 878 void do_secure_storage_access(struct pt_regs *regs) 879 { 880 default_trap_handler(regs); 881 } 882 883 void do_non_secure_storage_access(struct pt_regs *regs) 884 { 885 default_trap_handler(regs); 886 } 887 888 void do_secure_storage_violation(struct pt_regs *regs) 889 { 890 default_trap_handler(regs); 891 } 892 #endif 893