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 <linux/kfence.h> 35 #include <asm/asm-offsets.h> 36 #include <asm/diag.h> 37 #include <asm/gmap.h> 38 #include <asm/irq.h> 39 #include <asm/mmu_context.h> 40 #include <asm/facility.h> 41 #include <asm/uv.h> 42 #include "../kernel/entry.h" 43 44 #define __FAIL_ADDR_MASK -4096L 45 #define __SUBCODE_MASK 0x0600 46 #define __PF_RES_FIELD 0x8000000000000000ULL 47 48 #define VM_FAULT_BADCONTEXT ((__force vm_fault_t) 0x010000) 49 #define VM_FAULT_BADMAP ((__force vm_fault_t) 0x020000) 50 #define VM_FAULT_BADACCESS ((__force vm_fault_t) 0x040000) 51 #define VM_FAULT_SIGNAL ((__force vm_fault_t) 0x080000) 52 #define VM_FAULT_PFAULT ((__force vm_fault_t) 0x100000) 53 54 enum fault_type { 55 KERNEL_FAULT, 56 USER_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 (user_mode(regs)) 81 return USER_FAULT; 82 if (!IS_ENABLED(CONFIG_PGSTE)) 83 return KERNEL_FAULT; 84 if (test_pt_regs_flag(regs, PIF_GUEST_FAULT)) 85 return GMAP_FAULT; 86 return KERNEL_FAULT; 87 } 88 if (trans_exc_code == 2) 89 return USER_FAULT; 90 if (trans_exc_code == 1) { 91 /* access register mode, not used in the kernel */ 92 return USER_FAULT; 93 } 94 /* home space exception -> access via kernel ASCE */ 95 return KERNEL_FAULT; 96 } 97 98 static int bad_address(void *p) 99 { 100 unsigned long dummy; 101 102 return get_kernel_nofault(dummy, (unsigned long *)p); 103 } 104 105 static void dump_pagetable(unsigned long asce, unsigned long address) 106 { 107 unsigned long *table = __va(asce & _ASCE_ORIGIN); 108 109 pr_alert("AS:%016lx ", asce); 110 switch (asce & _ASCE_TYPE_MASK) { 111 case _ASCE_TYPE_REGION1: 112 table += (address & _REGION1_INDEX) >> _REGION1_SHIFT; 113 if (bad_address(table)) 114 goto bad; 115 pr_cont("R1:%016lx ", *table); 116 if (*table & _REGION_ENTRY_INVALID) 117 goto out; 118 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); 119 fallthrough; 120 case _ASCE_TYPE_REGION2: 121 table += (address & _REGION2_INDEX) >> _REGION2_SHIFT; 122 if (bad_address(table)) 123 goto bad; 124 pr_cont("R2:%016lx ", *table); 125 if (*table & _REGION_ENTRY_INVALID) 126 goto out; 127 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); 128 fallthrough; 129 case _ASCE_TYPE_REGION3: 130 table += (address & _REGION3_INDEX) >> _REGION3_SHIFT; 131 if (bad_address(table)) 132 goto bad; 133 pr_cont("R3:%016lx ", *table); 134 if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE)) 135 goto out; 136 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); 137 fallthrough; 138 case _ASCE_TYPE_SEGMENT: 139 table += (address & _SEGMENT_INDEX) >> _SEGMENT_SHIFT; 140 if (bad_address(table)) 141 goto bad; 142 pr_cont("S:%016lx ", *table); 143 if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE)) 144 goto out; 145 table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN); 146 } 147 table += (address & _PAGE_INDEX) >> _PAGE_SHIFT; 148 if (bad_address(table)) 149 goto bad; 150 pr_cont("P:%016lx ", *table); 151 out: 152 pr_cont("\n"); 153 return; 154 bad: 155 pr_cont("BAD\n"); 156 } 157 158 static void dump_fault_info(struct pt_regs *regs) 159 { 160 unsigned long asce; 161 162 pr_alert("Failing address: %016lx TEID: %016lx\n", 163 regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long); 164 pr_alert("Fault in "); 165 switch (regs->int_parm_long & 3) { 166 case 3: 167 pr_cont("home space "); 168 break; 169 case 2: 170 pr_cont("secondary space "); 171 break; 172 case 1: 173 pr_cont("access register "); 174 break; 175 case 0: 176 pr_cont("primary space "); 177 break; 178 } 179 pr_cont("mode while using "); 180 switch (get_fault_type(regs)) { 181 case USER_FAULT: 182 asce = S390_lowcore.user_asce; 183 pr_cont("user "); 184 break; 185 case GMAP_FAULT: 186 asce = ((struct gmap *) S390_lowcore.gmap)->asce; 187 pr_cont("gmap "); 188 break; 189 case KERNEL_FAULT: 190 asce = S390_lowcore.kernel_asce; 191 pr_cont("kernel "); 192 break; 193 default: 194 unreachable(); 195 } 196 pr_cont("ASCE.\n"); 197 dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK); 198 } 199 200 int show_unhandled_signals = 1; 201 202 void report_user_fault(struct pt_regs *regs, long signr, int is_mm_fault) 203 { 204 if ((task_pid_nr(current) > 1) && !show_unhandled_signals) 205 return; 206 if (!unhandled_signal(current, signr)) 207 return; 208 if (!printk_ratelimit()) 209 return; 210 printk(KERN_ALERT "User process fault: interruption code %04x ilc:%d ", 211 regs->int_code & 0xffff, regs->int_code >> 17); 212 print_vma_addr(KERN_CONT "in ", regs->psw.addr); 213 printk(KERN_CONT "\n"); 214 if (is_mm_fault) 215 dump_fault_info(regs); 216 show_regs(regs); 217 } 218 219 /* 220 * Send SIGSEGV to task. This is an external routine 221 * to keep the stack usage of do_page_fault small. 222 */ 223 static noinline void do_sigsegv(struct pt_regs *regs, int si_code) 224 { 225 report_user_fault(regs, SIGSEGV, 1); 226 force_sig_fault(SIGSEGV, si_code, 227 (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK)); 228 } 229 230 const struct exception_table_entry *s390_search_extables(unsigned long addr) 231 { 232 const struct exception_table_entry *fixup; 233 234 fixup = search_extable(__start_amode31_ex_table, 235 __stop_amode31_ex_table - __start_amode31_ex_table, 236 addr); 237 if (!fixup) 238 fixup = search_exception_tables(addr); 239 return fixup; 240 } 241 242 static noinline void do_no_context(struct pt_regs *regs) 243 { 244 const struct exception_table_entry *fixup; 245 246 /* Are we prepared to handle this kernel fault? */ 247 fixup = s390_search_extables(regs->psw.addr); 248 if (fixup && ex_handle(fixup, regs)) 249 return; 250 251 /* 252 * Oops. The kernel tried to access some bad page. We'll have to 253 * terminate things with extreme prejudice. 254 */ 255 if (get_fault_type(regs) == KERNEL_FAULT) 256 printk(KERN_ALERT "Unable to handle kernel pointer dereference" 257 " in virtual kernel address space\n"); 258 else 259 printk(KERN_ALERT "Unable to handle kernel paging request" 260 " in virtual user address space\n"); 261 dump_fault_info(regs); 262 die(regs, "Oops"); 263 do_exit(SIGKILL); 264 } 265 266 static noinline void do_low_address(struct pt_regs *regs) 267 { 268 /* Low-address protection hit in kernel mode means 269 NULL pointer write access in kernel mode. */ 270 if (regs->psw.mask & PSW_MASK_PSTATE) { 271 /* Low-address protection hit in user mode 'cannot happen'. */ 272 die (regs, "Low-address protection"); 273 do_exit(SIGKILL); 274 } 275 276 do_no_context(regs); 277 } 278 279 static noinline void do_sigbus(struct pt_regs *regs) 280 { 281 /* 282 * Send a sigbus, regardless of whether we were in kernel 283 * or user mode. 284 */ 285 force_sig_fault(SIGBUS, BUS_ADRERR, 286 (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK)); 287 } 288 289 static noinline void do_fault_error(struct pt_regs *regs, int access, 290 vm_fault_t fault) 291 { 292 int si_code; 293 294 switch (fault) { 295 case VM_FAULT_BADACCESS: 296 case VM_FAULT_BADMAP: 297 /* Bad memory access. Check if it is kernel or user space. */ 298 if (user_mode(regs)) { 299 /* User mode accesses just cause a SIGSEGV */ 300 si_code = (fault == VM_FAULT_BADMAP) ? 301 SEGV_MAPERR : SEGV_ACCERR; 302 do_sigsegv(regs, si_code); 303 break; 304 } 305 fallthrough; 306 case VM_FAULT_BADCONTEXT: 307 case VM_FAULT_PFAULT: 308 do_no_context(regs); 309 break; 310 case VM_FAULT_SIGNAL: 311 if (!user_mode(regs)) 312 do_no_context(regs); 313 break; 314 default: /* fault & VM_FAULT_ERROR */ 315 if (fault & VM_FAULT_OOM) { 316 if (!user_mode(regs)) 317 do_no_context(regs); 318 else 319 pagefault_out_of_memory(); 320 } else if (fault & VM_FAULT_SIGSEGV) { 321 /* Kernel mode? Handle exceptions or die */ 322 if (!user_mode(regs)) 323 do_no_context(regs); 324 else 325 do_sigsegv(regs, SEGV_MAPERR); 326 } else if (fault & VM_FAULT_SIGBUS) { 327 /* Kernel mode? Handle exceptions or die */ 328 if (!user_mode(regs)) 329 do_no_context(regs); 330 else 331 do_sigbus(regs); 332 } else 333 BUG(); 334 break; 335 } 336 } 337 338 /* 339 * This routine handles page faults. It determines the address, 340 * and the problem, and then passes it off to one of the appropriate 341 * routines. 342 * 343 * interruption code (int_code): 344 * 04 Protection -> Write-Protection (suppression) 345 * 10 Segment translation -> Not present (nullification) 346 * 11 Page translation -> Not present (nullification) 347 * 3b Region third trans. -> Not present (nullification) 348 */ 349 static inline vm_fault_t do_exception(struct pt_regs *regs, int access) 350 { 351 struct gmap *gmap; 352 struct task_struct *tsk; 353 struct mm_struct *mm; 354 struct vm_area_struct *vma; 355 enum fault_type type; 356 unsigned long trans_exc_code; 357 unsigned long address; 358 unsigned int flags; 359 vm_fault_t fault; 360 bool is_write; 361 362 tsk = current; 363 /* 364 * The instruction that caused the program check has 365 * been nullified. Don't signal single step via SIGTRAP. 366 */ 367 clear_thread_flag(TIF_PER_TRAP); 368 369 if (kprobe_page_fault(regs, 14)) 370 return 0; 371 372 mm = tsk->mm; 373 trans_exc_code = regs->int_parm_long; 374 address = trans_exc_code & __FAIL_ADDR_MASK; 375 is_write = (trans_exc_code & store_indication) == 0x400; 376 377 /* 378 * Verify that the fault happened in user space, that 379 * we are not in an interrupt and that there is a 380 * user context. 381 */ 382 fault = VM_FAULT_BADCONTEXT; 383 type = get_fault_type(regs); 384 switch (type) { 385 case KERNEL_FAULT: 386 if (kfence_handle_page_fault(address, is_write, regs)) 387 return 0; 388 goto out; 389 case USER_FAULT: 390 case GMAP_FAULT: 391 if (faulthandler_disabled() || !mm) 392 goto out; 393 break; 394 } 395 396 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 397 flags = FAULT_FLAG_DEFAULT; 398 if (user_mode(regs)) 399 flags |= FAULT_FLAG_USER; 400 if (access == VM_WRITE || is_write) 401 flags |= FAULT_FLAG_WRITE; 402 mmap_read_lock(mm); 403 404 gmap = NULL; 405 if (IS_ENABLED(CONFIG_PGSTE) && type == GMAP_FAULT) { 406 gmap = (struct gmap *) S390_lowcore.gmap; 407 current->thread.gmap_addr = address; 408 current->thread.gmap_write_flag = !!(flags & FAULT_FLAG_WRITE); 409 current->thread.gmap_int_code = regs->int_code & 0xffff; 410 address = __gmap_translate(gmap, address); 411 if (address == -EFAULT) { 412 fault = VM_FAULT_BADMAP; 413 goto out_up; 414 } 415 if (gmap->pfault_enabled) 416 flags |= FAULT_FLAG_RETRY_NOWAIT; 417 } 418 419 retry: 420 fault = VM_FAULT_BADMAP; 421 vma = find_vma(mm, address); 422 if (!vma) 423 goto out_up; 424 425 if (unlikely(vma->vm_start > address)) { 426 if (!(vma->vm_flags & VM_GROWSDOWN)) 427 goto out_up; 428 if (expand_stack(vma, address)) 429 goto out_up; 430 } 431 432 /* 433 * Ok, we have a good vm_area for this memory access, so 434 * we can handle it.. 435 */ 436 fault = VM_FAULT_BADACCESS; 437 if (unlikely(!(vma->vm_flags & access))) 438 goto out_up; 439 440 if (is_vm_hugetlb_page(vma)) 441 address &= HPAGE_MASK; 442 /* 443 * If for any reason at all we couldn't handle the fault, 444 * make sure we exit gracefully rather than endlessly redo 445 * the fault. 446 */ 447 fault = handle_mm_fault(vma, address, flags, regs); 448 if (fault_signal_pending(fault, regs)) { 449 fault = VM_FAULT_SIGNAL; 450 if (flags & FAULT_FLAG_RETRY_NOWAIT) 451 goto out_up; 452 goto out; 453 } 454 if (unlikely(fault & VM_FAULT_ERROR)) 455 goto out_up; 456 457 if (flags & FAULT_FLAG_ALLOW_RETRY) { 458 if (fault & VM_FAULT_RETRY) { 459 if (IS_ENABLED(CONFIG_PGSTE) && gmap && 460 (flags & FAULT_FLAG_RETRY_NOWAIT)) { 461 /* FAULT_FLAG_RETRY_NOWAIT has been set, 462 * mmap_lock has not been released */ 463 current->thread.gmap_pfault = 1; 464 fault = VM_FAULT_PFAULT; 465 goto out_up; 466 } 467 flags &= ~FAULT_FLAG_RETRY_NOWAIT; 468 flags |= FAULT_FLAG_TRIED; 469 mmap_read_lock(mm); 470 goto retry; 471 } 472 } 473 if (IS_ENABLED(CONFIG_PGSTE) && gmap) { 474 address = __gmap_link(gmap, current->thread.gmap_addr, 475 address); 476 if (address == -EFAULT) { 477 fault = VM_FAULT_BADMAP; 478 goto out_up; 479 } 480 if (address == -ENOMEM) { 481 fault = VM_FAULT_OOM; 482 goto out_up; 483 } 484 } 485 fault = 0; 486 out_up: 487 mmap_read_unlock(mm); 488 out: 489 return fault; 490 } 491 492 void do_protection_exception(struct pt_regs *regs) 493 { 494 unsigned long trans_exc_code; 495 int access; 496 vm_fault_t fault; 497 498 trans_exc_code = regs->int_parm_long; 499 /* 500 * Protection exceptions are suppressing, decrement psw address. 501 * The exception to this rule are aborted transactions, for these 502 * the PSW already points to the correct location. 503 */ 504 if (!(regs->int_code & 0x200)) 505 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16); 506 /* 507 * Check for low-address protection. This needs to be treated 508 * as a special case because the translation exception code 509 * field is not guaranteed to contain valid data in this case. 510 */ 511 if (unlikely(!(trans_exc_code & 4))) { 512 do_low_address(regs); 513 return; 514 } 515 if (unlikely(MACHINE_HAS_NX && (trans_exc_code & 0x80))) { 516 regs->int_parm_long = (trans_exc_code & ~PAGE_MASK) | 517 (regs->psw.addr & PAGE_MASK); 518 access = VM_EXEC; 519 fault = VM_FAULT_BADACCESS; 520 } else { 521 access = VM_WRITE; 522 fault = do_exception(regs, access); 523 } 524 if (unlikely(fault)) 525 do_fault_error(regs, access, fault); 526 } 527 NOKPROBE_SYMBOL(do_protection_exception); 528 529 void do_dat_exception(struct pt_regs *regs) 530 { 531 int access; 532 vm_fault_t fault; 533 534 access = VM_ACCESS_FLAGS; 535 fault = do_exception(regs, access); 536 if (unlikely(fault)) 537 do_fault_error(regs, access, fault); 538 } 539 NOKPROBE_SYMBOL(do_dat_exception); 540 541 #ifdef CONFIG_PFAULT 542 /* 543 * 'pfault' pseudo page faults routines. 544 */ 545 static int pfault_disable; 546 547 static int __init nopfault(char *str) 548 { 549 pfault_disable = 1; 550 return 1; 551 } 552 553 __setup("nopfault", nopfault); 554 555 struct pfault_refbk { 556 u16 refdiagc; 557 u16 reffcode; 558 u16 refdwlen; 559 u16 refversn; 560 u64 refgaddr; 561 u64 refselmk; 562 u64 refcmpmk; 563 u64 reserved; 564 } __attribute__ ((packed, aligned(8))); 565 566 static struct pfault_refbk pfault_init_refbk = { 567 .refdiagc = 0x258, 568 .reffcode = 0, 569 .refdwlen = 5, 570 .refversn = 2, 571 .refgaddr = __LC_LPP, 572 .refselmk = 1ULL << 48, 573 .refcmpmk = 1ULL << 48, 574 .reserved = __PF_RES_FIELD 575 }; 576 577 int pfault_init(void) 578 { 579 int rc; 580 581 if (pfault_disable) 582 return -1; 583 diag_stat_inc(DIAG_STAT_X258); 584 asm volatile( 585 " diag %1,%0,0x258\n" 586 "0: j 2f\n" 587 "1: la %0,8\n" 588 "2:\n" 589 EX_TABLE(0b,1b) 590 : "=d" (rc) 591 : "a" (&pfault_init_refbk), "m" (pfault_init_refbk) : "cc"); 592 return rc; 593 } 594 595 static struct pfault_refbk pfault_fini_refbk = { 596 .refdiagc = 0x258, 597 .reffcode = 1, 598 .refdwlen = 5, 599 .refversn = 2, 600 }; 601 602 void pfault_fini(void) 603 { 604 605 if (pfault_disable) 606 return; 607 diag_stat_inc(DIAG_STAT_X258); 608 asm volatile( 609 " diag %0,0,0x258\n" 610 "0: nopr %%r7\n" 611 EX_TABLE(0b,0b) 612 : : "a" (&pfault_fini_refbk), "m" (pfault_fini_refbk) : "cc"); 613 } 614 615 static DEFINE_SPINLOCK(pfault_lock); 616 static LIST_HEAD(pfault_list); 617 618 #define PF_COMPLETE 0x0080 619 620 /* 621 * The mechanism of our pfault code: if Linux is running as guest, runs a user 622 * space process and the user space process accesses a page that the host has 623 * paged out we get a pfault interrupt. 624 * 625 * This allows us, within the guest, to schedule a different process. Without 626 * this mechanism the host would have to suspend the whole virtual cpu until 627 * the page has been paged in. 628 * 629 * So when we get such an interrupt then we set the state of the current task 630 * to uninterruptible and also set the need_resched flag. Both happens within 631 * interrupt context(!). If we later on want to return to user space we 632 * recognize the need_resched flag and then call schedule(). It's not very 633 * obvious how this works... 634 * 635 * Of course we have a lot of additional fun with the completion interrupt (-> 636 * host signals that a page of a process has been paged in and the process can 637 * continue to run). This interrupt can arrive on any cpu and, since we have 638 * virtual cpus, actually appear before the interrupt that signals that a page 639 * is missing. 640 */ 641 static void pfault_interrupt(struct ext_code ext_code, 642 unsigned int param32, unsigned long param64) 643 { 644 struct task_struct *tsk; 645 __u16 subcode; 646 pid_t pid; 647 648 /* 649 * Get the external interruption subcode & pfault initial/completion 650 * signal bit. VM stores this in the 'cpu address' field associated 651 * with the external interrupt. 652 */ 653 subcode = ext_code.subcode; 654 if ((subcode & 0xff00) != __SUBCODE_MASK) 655 return; 656 inc_irq_stat(IRQEXT_PFL); 657 /* Get the token (= pid of the affected task). */ 658 pid = param64 & LPP_PID_MASK; 659 rcu_read_lock(); 660 tsk = find_task_by_pid_ns(pid, &init_pid_ns); 661 if (tsk) 662 get_task_struct(tsk); 663 rcu_read_unlock(); 664 if (!tsk) 665 return; 666 spin_lock(&pfault_lock); 667 if (subcode & PF_COMPLETE) { 668 /* signal bit is set -> a page has been swapped in by VM */ 669 if (tsk->thread.pfault_wait == 1) { 670 /* Initial interrupt was faster than the completion 671 * interrupt. pfault_wait is valid. Set pfault_wait 672 * back to zero and wake up the process. This can 673 * safely be done because the task is still sleeping 674 * and can't produce new pfaults. */ 675 tsk->thread.pfault_wait = 0; 676 list_del(&tsk->thread.list); 677 wake_up_process(tsk); 678 put_task_struct(tsk); 679 } else { 680 /* Completion interrupt was faster than initial 681 * interrupt. Set pfault_wait to -1 so the initial 682 * interrupt doesn't put the task to sleep. 683 * If the task is not running, ignore the completion 684 * interrupt since it must be a leftover of a PFAULT 685 * CANCEL operation which didn't remove all pending 686 * completion interrupts. */ 687 if (task_is_running(tsk)) 688 tsk->thread.pfault_wait = -1; 689 } 690 } else { 691 /* signal bit not set -> a real page is missing. */ 692 if (WARN_ON_ONCE(tsk != current)) 693 goto out; 694 if (tsk->thread.pfault_wait == 1) { 695 /* Already on the list with a reference: put to sleep */ 696 goto block; 697 } else if (tsk->thread.pfault_wait == -1) { 698 /* Completion interrupt was faster than the initial 699 * interrupt (pfault_wait == -1). Set pfault_wait 700 * back to zero and exit. */ 701 tsk->thread.pfault_wait = 0; 702 } else { 703 /* Initial interrupt arrived before completion 704 * interrupt. Let the task sleep. 705 * An extra task reference is needed since a different 706 * cpu may set the task state to TASK_RUNNING again 707 * before the scheduler is reached. */ 708 get_task_struct(tsk); 709 tsk->thread.pfault_wait = 1; 710 list_add(&tsk->thread.list, &pfault_list); 711 block: 712 /* Since this must be a userspace fault, there 713 * is no kernel task state to trample. Rely on the 714 * return to userspace schedule() to block. */ 715 __set_current_state(TASK_UNINTERRUPTIBLE); 716 set_tsk_need_resched(tsk); 717 set_preempt_need_resched(); 718 } 719 } 720 out: 721 spin_unlock(&pfault_lock); 722 put_task_struct(tsk); 723 } 724 725 static int pfault_cpu_dead(unsigned int cpu) 726 { 727 struct thread_struct *thread, *next; 728 struct task_struct *tsk; 729 730 spin_lock_irq(&pfault_lock); 731 list_for_each_entry_safe(thread, next, &pfault_list, list) { 732 thread->pfault_wait = 0; 733 list_del(&thread->list); 734 tsk = container_of(thread, struct task_struct, thread); 735 wake_up_process(tsk); 736 put_task_struct(tsk); 737 } 738 spin_unlock_irq(&pfault_lock); 739 return 0; 740 } 741 742 static int __init pfault_irq_init(void) 743 { 744 int rc; 745 746 rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); 747 if (rc) 748 goto out_extint; 749 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP; 750 if (rc) 751 goto out_pfault; 752 irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL); 753 cpuhp_setup_state_nocalls(CPUHP_S390_PFAULT_DEAD, "s390/pfault:dead", 754 NULL, pfault_cpu_dead); 755 return 0; 756 757 out_pfault: 758 unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); 759 out_extint: 760 pfault_disable = 1; 761 return rc; 762 } 763 early_initcall(pfault_irq_init); 764 765 #endif /* CONFIG_PFAULT */ 766 767 #if IS_ENABLED(CONFIG_PGSTE) 768 769 void do_secure_storage_access(struct pt_regs *regs) 770 { 771 unsigned long addr = regs->int_parm_long & __FAIL_ADDR_MASK; 772 struct vm_area_struct *vma; 773 struct mm_struct *mm; 774 struct page *page; 775 int rc; 776 777 /* 778 * bit 61 tells us if the address is valid, if it's not we 779 * have a major problem and should stop the kernel or send a 780 * SIGSEGV to the process. Unfortunately bit 61 is not 781 * reliable without the misc UV feature so we need to check 782 * for that as well. 783 */ 784 if (test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications) && 785 !test_bit_inv(61, ®s->int_parm_long)) { 786 /* 787 * When this happens, userspace did something that it 788 * was not supposed to do, e.g. branching into secure 789 * memory. Trigger a segmentation fault. 790 */ 791 if (user_mode(regs)) { 792 send_sig(SIGSEGV, current, 0); 793 return; 794 } 795 796 /* 797 * The kernel should never run into this case and we 798 * have no way out of this situation. 799 */ 800 panic("Unexpected PGM 0x3d with TEID bit 61=0"); 801 } 802 803 switch (get_fault_type(regs)) { 804 case USER_FAULT: 805 mm = current->mm; 806 mmap_read_lock(mm); 807 vma = find_vma(mm, addr); 808 if (!vma) { 809 mmap_read_unlock(mm); 810 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP); 811 break; 812 } 813 page = follow_page(vma, addr, FOLL_WRITE | FOLL_GET); 814 if (IS_ERR_OR_NULL(page)) { 815 mmap_read_unlock(mm); 816 break; 817 } 818 if (arch_make_page_accessible(page)) 819 send_sig(SIGSEGV, current, 0); 820 put_page(page); 821 mmap_read_unlock(mm); 822 break; 823 case KERNEL_FAULT: 824 page = phys_to_page(addr); 825 if (unlikely(!try_get_page(page))) 826 break; 827 rc = arch_make_page_accessible(page); 828 put_page(page); 829 if (rc) 830 BUG(); 831 break; 832 case GMAP_FAULT: 833 default: 834 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP); 835 WARN_ON_ONCE(1); 836 } 837 } 838 NOKPROBE_SYMBOL(do_secure_storage_access); 839 840 void do_non_secure_storage_access(struct pt_regs *regs) 841 { 842 unsigned long gaddr = regs->int_parm_long & __FAIL_ADDR_MASK; 843 struct gmap *gmap = (struct gmap *)S390_lowcore.gmap; 844 845 if (get_fault_type(regs) != GMAP_FAULT) { 846 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP); 847 WARN_ON_ONCE(1); 848 return; 849 } 850 851 if (gmap_convert_to_secure(gmap, gaddr) == -EINVAL) 852 send_sig(SIGSEGV, current, 0); 853 } 854 NOKPROBE_SYMBOL(do_non_secure_storage_access); 855 856 void do_secure_storage_violation(struct pt_regs *regs) 857 { 858 /* 859 * Either KVM messed up the secure guest mapping or the same 860 * page is mapped into multiple secure guests. 861 * 862 * This exception is only triggered when a guest 2 is running 863 * and can therefore never occur in kernel context. 864 */ 865 printk_ratelimited(KERN_WARNING 866 "Secure storage violation in task: %s, pid %d\n", 867 current->comm, current->pid); 868 send_sig(SIGSEGV, current, 0); 869 } 870 871 #endif /* CONFIG_PGSTE */ 872