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 void do_fault_error(struct pt_regs *regs, int access, 289 vm_fault_t fault) 290 { 291 int si_code; 292 293 switch (fault) { 294 case VM_FAULT_BADACCESS: 295 case VM_FAULT_BADMAP: 296 /* Bad memory access. Check if it is kernel or user space. */ 297 if (user_mode(regs)) { 298 /* User mode accesses just cause a SIGSEGV */ 299 si_code = (fault == VM_FAULT_BADMAP) ? 300 SEGV_MAPERR : SEGV_ACCERR; 301 do_sigsegv(regs, si_code); 302 break; 303 } 304 fallthrough; 305 case VM_FAULT_BADCONTEXT: 306 case VM_FAULT_PFAULT: 307 do_no_context(regs); 308 break; 309 case VM_FAULT_SIGNAL: 310 if (!user_mode(regs)) 311 do_no_context(regs); 312 break; 313 default: /* fault & VM_FAULT_ERROR */ 314 if (fault & VM_FAULT_OOM) { 315 if (!user_mode(regs)) 316 do_no_context(regs); 317 else 318 pagefault_out_of_memory(); 319 } else if (fault & VM_FAULT_SIGSEGV) { 320 /* Kernel mode? Handle exceptions or die */ 321 if (!user_mode(regs)) 322 do_no_context(regs); 323 else 324 do_sigsegv(regs, SEGV_MAPERR); 325 } else if (fault & VM_FAULT_SIGBUS) { 326 /* Kernel mode? Handle exceptions or die */ 327 if (!user_mode(regs)) 328 do_no_context(regs); 329 else 330 do_sigbus(regs); 331 } else 332 BUG(); 333 break; 334 } 335 } 336 337 /* 338 * This routine handles page faults. It determines the address, 339 * and the problem, and then passes it off to one of the appropriate 340 * routines. 341 * 342 * interruption code (int_code): 343 * 04 Protection -> Write-Protection (suppression) 344 * 10 Segment translation -> Not present (nullification) 345 * 11 Page translation -> Not present (nullification) 346 * 3b Region third trans. -> Not present (nullification) 347 */ 348 static inline vm_fault_t do_exception(struct pt_regs *regs, int access) 349 { 350 struct gmap *gmap; 351 struct task_struct *tsk; 352 struct mm_struct *mm; 353 struct vm_area_struct *vma; 354 enum fault_type type; 355 unsigned long trans_exc_code; 356 unsigned long address; 357 unsigned int flags; 358 vm_fault_t fault; 359 360 tsk = current; 361 /* 362 * The instruction that caused the program check has 363 * been nullified. Don't signal single step via SIGTRAP. 364 */ 365 clear_thread_flag(TIF_PER_TRAP); 366 367 if (kprobe_page_fault(regs, 14)) 368 return 0; 369 370 mm = tsk->mm; 371 trans_exc_code = regs->int_parm_long; 372 373 /* 374 * Verify that the fault happened in user space, that 375 * we are not in an interrupt and that there is a 376 * user context. 377 */ 378 fault = VM_FAULT_BADCONTEXT; 379 type = get_fault_type(regs); 380 switch (type) { 381 case KERNEL_FAULT: 382 goto out; 383 case USER_FAULT: 384 case GMAP_FAULT: 385 if (faulthandler_disabled() || !mm) 386 goto out; 387 break; 388 } 389 390 address = trans_exc_code & __FAIL_ADDR_MASK; 391 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 392 flags = FAULT_FLAG_DEFAULT; 393 if (user_mode(regs)) 394 flags |= FAULT_FLAG_USER; 395 if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400) 396 flags |= FAULT_FLAG_WRITE; 397 mmap_read_lock(mm); 398 399 gmap = NULL; 400 if (IS_ENABLED(CONFIG_PGSTE) && type == GMAP_FAULT) { 401 gmap = (struct gmap *) S390_lowcore.gmap; 402 current->thread.gmap_addr = address; 403 current->thread.gmap_write_flag = !!(flags & FAULT_FLAG_WRITE); 404 current->thread.gmap_int_code = regs->int_code & 0xffff; 405 address = __gmap_translate(gmap, address); 406 if (address == -EFAULT) { 407 fault = VM_FAULT_BADMAP; 408 goto out_up; 409 } 410 if (gmap->pfault_enabled) 411 flags |= FAULT_FLAG_RETRY_NOWAIT; 412 } 413 414 retry: 415 fault = VM_FAULT_BADMAP; 416 vma = find_vma(mm, address); 417 if (!vma) 418 goto out_up; 419 420 if (unlikely(vma->vm_start > address)) { 421 if (!(vma->vm_flags & VM_GROWSDOWN)) 422 goto out_up; 423 if (expand_stack(vma, address)) 424 goto out_up; 425 } 426 427 /* 428 * Ok, we have a good vm_area for this memory access, so 429 * we can handle it.. 430 */ 431 fault = VM_FAULT_BADACCESS; 432 if (unlikely(!(vma->vm_flags & access))) 433 goto out_up; 434 435 if (is_vm_hugetlb_page(vma)) 436 address &= HPAGE_MASK; 437 /* 438 * If for any reason at all we couldn't handle the fault, 439 * make sure we exit gracefully rather than endlessly redo 440 * the fault. 441 */ 442 fault = handle_mm_fault(vma, address, flags, regs); 443 if (fault_signal_pending(fault, regs)) { 444 fault = VM_FAULT_SIGNAL; 445 if (flags & FAULT_FLAG_RETRY_NOWAIT) 446 goto out_up; 447 goto out; 448 } 449 if (unlikely(fault & VM_FAULT_ERROR)) 450 goto out_up; 451 452 if (flags & FAULT_FLAG_ALLOW_RETRY) { 453 if (fault & VM_FAULT_RETRY) { 454 if (IS_ENABLED(CONFIG_PGSTE) && gmap && 455 (flags & FAULT_FLAG_RETRY_NOWAIT)) { 456 /* FAULT_FLAG_RETRY_NOWAIT has been set, 457 * mmap_lock has not been released */ 458 current->thread.gmap_pfault = 1; 459 fault = VM_FAULT_PFAULT; 460 goto out_up; 461 } 462 flags &= ~FAULT_FLAG_RETRY_NOWAIT; 463 flags |= FAULT_FLAG_TRIED; 464 mmap_read_lock(mm); 465 goto retry; 466 } 467 } 468 if (IS_ENABLED(CONFIG_PGSTE) && gmap) { 469 address = __gmap_link(gmap, current->thread.gmap_addr, 470 address); 471 if (address == -EFAULT) { 472 fault = VM_FAULT_BADMAP; 473 goto out_up; 474 } 475 if (address == -ENOMEM) { 476 fault = VM_FAULT_OOM; 477 goto out_up; 478 } 479 } 480 fault = 0; 481 out_up: 482 mmap_read_unlock(mm); 483 out: 484 return fault; 485 } 486 487 void do_protection_exception(struct pt_regs *regs) 488 { 489 unsigned long trans_exc_code; 490 int access; 491 vm_fault_t fault; 492 493 trans_exc_code = regs->int_parm_long; 494 /* 495 * Protection exceptions are suppressing, decrement psw address. 496 * The exception to this rule are aborted transactions, for these 497 * the PSW already points to the correct location. 498 */ 499 if (!(regs->int_code & 0x200)) 500 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16); 501 /* 502 * Check for low-address protection. This needs to be treated 503 * as a special case because the translation exception code 504 * field is not guaranteed to contain valid data in this case. 505 */ 506 if (unlikely(!(trans_exc_code & 4))) { 507 do_low_address(regs); 508 return; 509 } 510 if (unlikely(MACHINE_HAS_NX && (trans_exc_code & 0x80))) { 511 regs->int_parm_long = (trans_exc_code & ~PAGE_MASK) | 512 (regs->psw.addr & PAGE_MASK); 513 access = VM_EXEC; 514 fault = VM_FAULT_BADACCESS; 515 } else { 516 access = VM_WRITE; 517 fault = do_exception(regs, access); 518 } 519 if (unlikely(fault)) 520 do_fault_error(regs, access, fault); 521 } 522 NOKPROBE_SYMBOL(do_protection_exception); 523 524 void do_dat_exception(struct pt_regs *regs) 525 { 526 int access; 527 vm_fault_t fault; 528 529 access = VM_ACCESS_FLAGS; 530 fault = do_exception(regs, access); 531 if (unlikely(fault)) 532 do_fault_error(regs, access, fault); 533 } 534 NOKPROBE_SYMBOL(do_dat_exception); 535 536 #ifdef CONFIG_PFAULT 537 /* 538 * 'pfault' pseudo page faults routines. 539 */ 540 static int pfault_disable; 541 542 static int __init nopfault(char *str) 543 { 544 pfault_disable = 1; 545 return 1; 546 } 547 548 __setup("nopfault", nopfault); 549 550 struct pfault_refbk { 551 u16 refdiagc; 552 u16 reffcode; 553 u16 refdwlen; 554 u16 refversn; 555 u64 refgaddr; 556 u64 refselmk; 557 u64 refcmpmk; 558 u64 reserved; 559 } __attribute__ ((packed, aligned(8))); 560 561 static struct pfault_refbk pfault_init_refbk = { 562 .refdiagc = 0x258, 563 .reffcode = 0, 564 .refdwlen = 5, 565 .refversn = 2, 566 .refgaddr = __LC_LPP, 567 .refselmk = 1ULL << 48, 568 .refcmpmk = 1ULL << 48, 569 .reserved = __PF_RES_FIELD 570 }; 571 572 int pfault_init(void) 573 { 574 int rc; 575 576 if (pfault_disable) 577 return -1; 578 diag_stat_inc(DIAG_STAT_X258); 579 asm volatile( 580 " diag %1,%0,0x258\n" 581 "0: j 2f\n" 582 "1: la %0,8\n" 583 "2:\n" 584 EX_TABLE(0b,1b) 585 : "=d" (rc) 586 : "a" (&pfault_init_refbk), "m" (pfault_init_refbk) : "cc"); 587 return rc; 588 } 589 590 static struct pfault_refbk pfault_fini_refbk = { 591 .refdiagc = 0x258, 592 .reffcode = 1, 593 .refdwlen = 5, 594 .refversn = 2, 595 }; 596 597 void pfault_fini(void) 598 { 599 600 if (pfault_disable) 601 return; 602 diag_stat_inc(DIAG_STAT_X258); 603 asm volatile( 604 " diag %0,0,0x258\n" 605 "0: nopr %%r7\n" 606 EX_TABLE(0b,0b) 607 : : "a" (&pfault_fini_refbk), "m" (pfault_fini_refbk) : "cc"); 608 } 609 610 static DEFINE_SPINLOCK(pfault_lock); 611 static LIST_HEAD(pfault_list); 612 613 #define PF_COMPLETE 0x0080 614 615 /* 616 * The mechanism of our pfault code: if Linux is running as guest, runs a user 617 * space process and the user space process accesses a page that the host has 618 * paged out we get a pfault interrupt. 619 * 620 * This allows us, within the guest, to schedule a different process. Without 621 * this mechanism the host would have to suspend the whole virtual cpu until 622 * the page has been paged in. 623 * 624 * So when we get such an interrupt then we set the state of the current task 625 * to uninterruptible and also set the need_resched flag. Both happens within 626 * interrupt context(!). If we later on want to return to user space we 627 * recognize the need_resched flag and then call schedule(). It's not very 628 * obvious how this works... 629 * 630 * Of course we have a lot of additional fun with the completion interrupt (-> 631 * host signals that a page of a process has been paged in and the process can 632 * continue to run). This interrupt can arrive on any cpu and, since we have 633 * virtual cpus, actually appear before the interrupt that signals that a page 634 * is missing. 635 */ 636 static void pfault_interrupt(struct ext_code ext_code, 637 unsigned int param32, unsigned long param64) 638 { 639 struct task_struct *tsk; 640 __u16 subcode; 641 pid_t pid; 642 643 /* 644 * Get the external interruption subcode & pfault initial/completion 645 * signal bit. VM stores this in the 'cpu address' field associated 646 * with the external interrupt. 647 */ 648 subcode = ext_code.subcode; 649 if ((subcode & 0xff00) != __SUBCODE_MASK) 650 return; 651 inc_irq_stat(IRQEXT_PFL); 652 /* Get the token (= pid of the affected task). */ 653 pid = param64 & LPP_PID_MASK; 654 rcu_read_lock(); 655 tsk = find_task_by_pid_ns(pid, &init_pid_ns); 656 if (tsk) 657 get_task_struct(tsk); 658 rcu_read_unlock(); 659 if (!tsk) 660 return; 661 spin_lock(&pfault_lock); 662 if (subcode & PF_COMPLETE) { 663 /* signal bit is set -> a page has been swapped in by VM */ 664 if (tsk->thread.pfault_wait == 1) { 665 /* Initial interrupt was faster than the completion 666 * interrupt. pfault_wait is valid. Set pfault_wait 667 * back to zero and wake up the process. This can 668 * safely be done because the task is still sleeping 669 * and can't produce new pfaults. */ 670 tsk->thread.pfault_wait = 0; 671 list_del(&tsk->thread.list); 672 wake_up_process(tsk); 673 put_task_struct(tsk); 674 } else { 675 /* Completion interrupt was faster than initial 676 * interrupt. Set pfault_wait to -1 so the initial 677 * interrupt doesn't put the task to sleep. 678 * If the task is not running, ignore the completion 679 * interrupt since it must be a leftover of a PFAULT 680 * CANCEL operation which didn't remove all pending 681 * completion interrupts. */ 682 if (task_is_running(tsk)) 683 tsk->thread.pfault_wait = -1; 684 } 685 } else { 686 /* signal bit not set -> a real page is missing. */ 687 if (WARN_ON_ONCE(tsk != current)) 688 goto out; 689 if (tsk->thread.pfault_wait == 1) { 690 /* Already on the list with a reference: put to sleep */ 691 goto block; 692 } else if (tsk->thread.pfault_wait == -1) { 693 /* Completion interrupt was faster than the initial 694 * interrupt (pfault_wait == -1). Set pfault_wait 695 * back to zero and exit. */ 696 tsk->thread.pfault_wait = 0; 697 } else { 698 /* Initial interrupt arrived before completion 699 * interrupt. Let the task sleep. 700 * An extra task reference is needed since a different 701 * cpu may set the task state to TASK_RUNNING again 702 * before the scheduler is reached. */ 703 get_task_struct(tsk); 704 tsk->thread.pfault_wait = 1; 705 list_add(&tsk->thread.list, &pfault_list); 706 block: 707 /* Since this must be a userspace fault, there 708 * is no kernel task state to trample. Rely on the 709 * return to userspace schedule() to block. */ 710 __set_current_state(TASK_UNINTERRUPTIBLE); 711 set_tsk_need_resched(tsk); 712 set_preempt_need_resched(); 713 } 714 } 715 out: 716 spin_unlock(&pfault_lock); 717 put_task_struct(tsk); 718 } 719 720 static int pfault_cpu_dead(unsigned int cpu) 721 { 722 struct thread_struct *thread, *next; 723 struct task_struct *tsk; 724 725 spin_lock_irq(&pfault_lock); 726 list_for_each_entry_safe(thread, next, &pfault_list, list) { 727 thread->pfault_wait = 0; 728 list_del(&thread->list); 729 tsk = container_of(thread, struct task_struct, thread); 730 wake_up_process(tsk); 731 put_task_struct(tsk); 732 } 733 spin_unlock_irq(&pfault_lock); 734 return 0; 735 } 736 737 static int __init pfault_irq_init(void) 738 { 739 int rc; 740 741 rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); 742 if (rc) 743 goto out_extint; 744 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP; 745 if (rc) 746 goto out_pfault; 747 irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL); 748 cpuhp_setup_state_nocalls(CPUHP_S390_PFAULT_DEAD, "s390/pfault:dead", 749 NULL, pfault_cpu_dead); 750 return 0; 751 752 out_pfault: 753 unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); 754 out_extint: 755 pfault_disable = 1; 756 return rc; 757 } 758 early_initcall(pfault_irq_init); 759 760 #endif /* CONFIG_PFAULT */ 761 762 #if IS_ENABLED(CONFIG_PGSTE) 763 764 void do_secure_storage_access(struct pt_regs *regs) 765 { 766 unsigned long addr = regs->int_parm_long & __FAIL_ADDR_MASK; 767 struct vm_area_struct *vma; 768 struct mm_struct *mm; 769 struct page *page; 770 int rc; 771 772 /* 773 * bit 61 tells us if the address is valid, if it's not we 774 * have a major problem and should stop the kernel or send a 775 * SIGSEGV to the process. Unfortunately bit 61 is not 776 * reliable without the misc UV feature so we need to check 777 * for that as well. 778 */ 779 if (test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications) && 780 !test_bit_inv(61, ®s->int_parm_long)) { 781 /* 782 * When this happens, userspace did something that it 783 * was not supposed to do, e.g. branching into secure 784 * memory. Trigger a segmentation fault. 785 */ 786 if (user_mode(regs)) { 787 send_sig(SIGSEGV, current, 0); 788 return; 789 } 790 791 /* 792 * The kernel should never run into this case and we 793 * have no way out of this situation. 794 */ 795 panic("Unexpected PGM 0x3d with TEID bit 61=0"); 796 } 797 798 switch (get_fault_type(regs)) { 799 case USER_FAULT: 800 mm = current->mm; 801 mmap_read_lock(mm); 802 vma = find_vma(mm, addr); 803 if (!vma) { 804 mmap_read_unlock(mm); 805 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP); 806 break; 807 } 808 page = follow_page(vma, addr, FOLL_WRITE | FOLL_GET); 809 if (IS_ERR_OR_NULL(page)) { 810 mmap_read_unlock(mm); 811 break; 812 } 813 if (arch_make_page_accessible(page)) 814 send_sig(SIGSEGV, current, 0); 815 put_page(page); 816 mmap_read_unlock(mm); 817 break; 818 case KERNEL_FAULT: 819 page = phys_to_page(addr); 820 if (unlikely(!try_get_page(page))) 821 break; 822 rc = arch_make_page_accessible(page); 823 put_page(page); 824 if (rc) 825 BUG(); 826 break; 827 case GMAP_FAULT: 828 default: 829 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP); 830 WARN_ON_ONCE(1); 831 } 832 } 833 NOKPROBE_SYMBOL(do_secure_storage_access); 834 835 void do_non_secure_storage_access(struct pt_regs *regs) 836 { 837 unsigned long gaddr = regs->int_parm_long & __FAIL_ADDR_MASK; 838 struct gmap *gmap = (struct gmap *)S390_lowcore.gmap; 839 840 if (get_fault_type(regs) != GMAP_FAULT) { 841 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP); 842 WARN_ON_ONCE(1); 843 return; 844 } 845 846 if (gmap_convert_to_secure(gmap, gaddr) == -EINVAL) 847 send_sig(SIGSEGV, current, 0); 848 } 849 NOKPROBE_SYMBOL(do_non_secure_storage_access); 850 851 void do_secure_storage_violation(struct pt_regs *regs) 852 { 853 /* 854 * Either KVM messed up the secure guest mapping or the same 855 * page is mapped into multiple secure guests. 856 * 857 * This exception is only triggered when a guest 2 is running 858 * and can therefore never occur in kernel context. 859 */ 860 printk_ratelimited(KERN_WARNING 861 "Secure storage violation in task: %s, pid %d\n", 862 current->comm, current->pid); 863 send_sig(SIGSEGV, current, 0); 864 } 865 866 #endif /* CONFIG_PGSTE */ 867