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-extable.h> 36 #include <asm/asm-offsets.h> 37 #include <asm/diag.h> 38 #include <asm/gmap.h> 39 #include <asm/irq.h> 40 #include <asm/mmu_context.h> 41 #include <asm/facility.h> 42 #include <asm/uv.h> 43 #include "../kernel/entry.h" 44 45 #define __FAIL_ADDR_MASK -4096L 46 #define __SUBCODE_MASK 0x0600 47 #define __PF_RES_FIELD 0x8000000000000000ULL 48 49 #define VM_FAULT_BADCONTEXT ((__force vm_fault_t) 0x010000) 50 #define VM_FAULT_BADMAP ((__force vm_fault_t) 0x020000) 51 #define VM_FAULT_BADACCESS ((__force vm_fault_t) 0x040000) 52 #define VM_FAULT_SIGNAL ((__force vm_fault_t) 0x080000) 53 #define VM_FAULT_PFAULT ((__force vm_fault_t) 0x100000) 54 55 enum fault_type { 56 KERNEL_FAULT, 57 USER_FAULT, 58 GMAP_FAULT, 59 }; 60 61 static unsigned long store_indication __read_mostly; 62 63 static int __init fault_init(void) 64 { 65 if (test_facility(75)) 66 store_indication = 0xc00; 67 return 0; 68 } 69 early_initcall(fault_init); 70 71 /* 72 * Find out which address space caused the exception. 73 */ 74 static enum fault_type get_fault_type(struct pt_regs *regs) 75 { 76 unsigned long trans_exc_code; 77 78 trans_exc_code = regs->int_parm_long & 3; 79 if (likely(trans_exc_code == 0)) { 80 /* primary space exception */ 81 if (user_mode(regs)) 82 return USER_FAULT; 83 if (!IS_ENABLED(CONFIG_PGSTE)) 84 return KERNEL_FAULT; 85 if (test_pt_regs_flag(regs, PIF_GUEST_FAULT)) 86 return GMAP_FAULT; 87 return KERNEL_FAULT; 88 } 89 if (trans_exc_code == 2) 90 return USER_FAULT; 91 if (trans_exc_code == 1) { 92 /* access register mode, not used in the kernel */ 93 return USER_FAULT; 94 } 95 /* home space exception -> access via kernel ASCE */ 96 return KERNEL_FAULT; 97 } 98 99 static int bad_address(void *p) 100 { 101 unsigned long dummy; 102 103 return get_kernel_nofault(dummy, (unsigned long *)p); 104 } 105 106 static void dump_pagetable(unsigned long asce, unsigned long address) 107 { 108 unsigned long *table = __va(asce & _ASCE_ORIGIN); 109 110 pr_alert("AS:%016lx ", asce); 111 switch (asce & _ASCE_TYPE_MASK) { 112 case _ASCE_TYPE_REGION1: 113 table += (address & _REGION1_INDEX) >> _REGION1_SHIFT; 114 if (bad_address(table)) 115 goto bad; 116 pr_cont("R1:%016lx ", *table); 117 if (*table & _REGION_ENTRY_INVALID) 118 goto out; 119 table = __va(*table & _REGION_ENTRY_ORIGIN); 120 fallthrough; 121 case _ASCE_TYPE_REGION2: 122 table += (address & _REGION2_INDEX) >> _REGION2_SHIFT; 123 if (bad_address(table)) 124 goto bad; 125 pr_cont("R2:%016lx ", *table); 126 if (*table & _REGION_ENTRY_INVALID) 127 goto out; 128 table = __va(*table & _REGION_ENTRY_ORIGIN); 129 fallthrough; 130 case _ASCE_TYPE_REGION3: 131 table += (address & _REGION3_INDEX) >> _REGION3_SHIFT; 132 if (bad_address(table)) 133 goto bad; 134 pr_cont("R3:%016lx ", *table); 135 if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE)) 136 goto out; 137 table = __va(*table & _REGION_ENTRY_ORIGIN); 138 fallthrough; 139 case _ASCE_TYPE_SEGMENT: 140 table += (address & _SEGMENT_INDEX) >> _SEGMENT_SHIFT; 141 if (bad_address(table)) 142 goto bad; 143 pr_cont("S:%016lx ", *table); 144 if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE)) 145 goto out; 146 table = __va(*table & _SEGMENT_ENTRY_ORIGIN); 147 } 148 table += (address & _PAGE_INDEX) >> _PAGE_SHIFT; 149 if (bad_address(table)) 150 goto bad; 151 pr_cont("P:%016lx ", *table); 152 out: 153 pr_cont("\n"); 154 return; 155 bad: 156 pr_cont("BAD\n"); 157 } 158 159 static void dump_fault_info(struct pt_regs *regs) 160 { 161 unsigned long asce; 162 163 pr_alert("Failing address: %016lx TEID: %016lx\n", 164 regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long); 165 pr_alert("Fault in "); 166 switch (regs->int_parm_long & 3) { 167 case 3: 168 pr_cont("home space "); 169 break; 170 case 2: 171 pr_cont("secondary space "); 172 break; 173 case 1: 174 pr_cont("access register "); 175 break; 176 case 0: 177 pr_cont("primary space "); 178 break; 179 } 180 pr_cont("mode while using "); 181 switch (get_fault_type(regs)) { 182 case USER_FAULT: 183 asce = S390_lowcore.user_asce; 184 pr_cont("user "); 185 break; 186 case GMAP_FAULT: 187 asce = ((struct gmap *) S390_lowcore.gmap)->asce; 188 pr_cont("gmap "); 189 break; 190 case KERNEL_FAULT: 191 asce = S390_lowcore.kernel_asce; 192 pr_cont("kernel "); 193 break; 194 default: 195 unreachable(); 196 } 197 pr_cont("ASCE.\n"); 198 dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK); 199 } 200 201 int show_unhandled_signals = 1; 202 203 void report_user_fault(struct pt_regs *regs, long signr, int is_mm_fault) 204 { 205 if ((task_pid_nr(current) > 1) && !show_unhandled_signals) 206 return; 207 if (!unhandled_signal(current, signr)) 208 return; 209 if (!printk_ratelimit()) 210 return; 211 printk(KERN_ALERT "User process fault: interruption code %04x ilc:%d ", 212 regs->int_code & 0xffff, regs->int_code >> 17); 213 print_vma_addr(KERN_CONT "in ", regs->psw.addr); 214 printk(KERN_CONT "\n"); 215 if (is_mm_fault) 216 dump_fault_info(regs); 217 show_regs(regs); 218 } 219 220 /* 221 * Send SIGSEGV to task. This is an external routine 222 * to keep the stack usage of do_page_fault small. 223 */ 224 static noinline void do_sigsegv(struct pt_regs *regs, int si_code) 225 { 226 report_user_fault(regs, SIGSEGV, 1); 227 force_sig_fault(SIGSEGV, si_code, 228 (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK)); 229 } 230 231 static noinline void do_no_context(struct pt_regs *regs) 232 { 233 if (fixup_exception(regs)) 234 return; 235 /* 236 * Oops. The kernel tried to access some bad page. We'll have to 237 * terminate things with extreme prejudice. 238 */ 239 if (get_fault_type(regs) == KERNEL_FAULT) 240 printk(KERN_ALERT "Unable to handle kernel pointer dereference" 241 " in virtual kernel address space\n"); 242 else 243 printk(KERN_ALERT "Unable to handle kernel paging request" 244 " in virtual user address space\n"); 245 dump_fault_info(regs); 246 die(regs, "Oops"); 247 } 248 249 static noinline void do_low_address(struct pt_regs *regs) 250 { 251 /* Low-address protection hit in kernel mode means 252 NULL pointer write access in kernel mode. */ 253 if (regs->psw.mask & PSW_MASK_PSTATE) { 254 /* Low-address protection hit in user mode 'cannot happen'. */ 255 die (regs, "Low-address protection"); 256 } 257 258 do_no_context(regs); 259 } 260 261 static noinline void do_sigbus(struct pt_regs *regs) 262 { 263 /* 264 * Send a sigbus, regardless of whether we were in kernel 265 * or user mode. 266 */ 267 force_sig_fault(SIGBUS, BUS_ADRERR, 268 (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK)); 269 } 270 271 static noinline void do_fault_error(struct pt_regs *regs, int access, 272 vm_fault_t fault) 273 { 274 int si_code; 275 276 switch (fault) { 277 case VM_FAULT_BADACCESS: 278 case VM_FAULT_BADMAP: 279 /* Bad memory access. Check if it is kernel or user space. */ 280 if (user_mode(regs)) { 281 /* User mode accesses just cause a SIGSEGV */ 282 si_code = (fault == VM_FAULT_BADMAP) ? 283 SEGV_MAPERR : SEGV_ACCERR; 284 do_sigsegv(regs, si_code); 285 break; 286 } 287 fallthrough; 288 case VM_FAULT_BADCONTEXT: 289 case VM_FAULT_PFAULT: 290 do_no_context(regs); 291 break; 292 case VM_FAULT_SIGNAL: 293 if (!user_mode(regs)) 294 do_no_context(regs); 295 break; 296 default: /* fault & VM_FAULT_ERROR */ 297 if (fault & VM_FAULT_OOM) { 298 if (!user_mode(regs)) 299 do_no_context(regs); 300 else 301 pagefault_out_of_memory(); 302 } else if (fault & VM_FAULT_SIGSEGV) { 303 /* Kernel mode? Handle exceptions or die */ 304 if (!user_mode(regs)) 305 do_no_context(regs); 306 else 307 do_sigsegv(regs, SEGV_MAPERR); 308 } else if (fault & VM_FAULT_SIGBUS) { 309 /* Kernel mode? Handle exceptions or die */ 310 if (!user_mode(regs)) 311 do_no_context(regs); 312 else 313 do_sigbus(regs); 314 } else 315 BUG(); 316 break; 317 } 318 } 319 320 /* 321 * This routine handles page faults. It determines the address, 322 * and the problem, and then passes it off to one of the appropriate 323 * routines. 324 * 325 * interruption code (int_code): 326 * 04 Protection -> Write-Protection (suppression) 327 * 10 Segment translation -> Not present (nullification) 328 * 11 Page translation -> Not present (nullification) 329 * 3b Region third trans. -> Not present (nullification) 330 */ 331 static inline vm_fault_t do_exception(struct pt_regs *regs, int access) 332 { 333 struct gmap *gmap; 334 struct task_struct *tsk; 335 struct mm_struct *mm; 336 struct vm_area_struct *vma; 337 enum fault_type type; 338 unsigned long trans_exc_code; 339 unsigned long address; 340 unsigned int flags; 341 vm_fault_t fault; 342 bool is_write; 343 344 tsk = current; 345 /* 346 * The instruction that caused the program check has 347 * been nullified. Don't signal single step via SIGTRAP. 348 */ 349 clear_thread_flag(TIF_PER_TRAP); 350 351 if (kprobe_page_fault(regs, 14)) 352 return 0; 353 354 mm = tsk->mm; 355 trans_exc_code = regs->int_parm_long; 356 address = trans_exc_code & __FAIL_ADDR_MASK; 357 is_write = (trans_exc_code & store_indication) == 0x400; 358 359 /* 360 * Verify that the fault happened in user space, that 361 * we are not in an interrupt and that there is a 362 * user context. 363 */ 364 fault = VM_FAULT_BADCONTEXT; 365 type = get_fault_type(regs); 366 switch (type) { 367 case KERNEL_FAULT: 368 if (kfence_handle_page_fault(address, is_write, regs)) 369 return 0; 370 goto out; 371 case USER_FAULT: 372 case GMAP_FAULT: 373 if (faulthandler_disabled() || !mm) 374 goto out; 375 break; 376 } 377 378 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 379 flags = FAULT_FLAG_DEFAULT; 380 if (user_mode(regs)) 381 flags |= FAULT_FLAG_USER; 382 if (is_write) 383 access = VM_WRITE; 384 if (access == VM_WRITE) 385 flags |= FAULT_FLAG_WRITE; 386 mmap_read_lock(mm); 387 388 gmap = NULL; 389 if (IS_ENABLED(CONFIG_PGSTE) && type == GMAP_FAULT) { 390 gmap = (struct gmap *) S390_lowcore.gmap; 391 current->thread.gmap_addr = address; 392 current->thread.gmap_write_flag = !!(flags & FAULT_FLAG_WRITE); 393 current->thread.gmap_int_code = regs->int_code & 0xffff; 394 address = __gmap_translate(gmap, address); 395 if (address == -EFAULT) { 396 fault = VM_FAULT_BADMAP; 397 goto out_up; 398 } 399 if (gmap->pfault_enabled) 400 flags |= FAULT_FLAG_RETRY_NOWAIT; 401 } 402 403 retry: 404 fault = VM_FAULT_BADMAP; 405 vma = find_vma(mm, address); 406 if (!vma) 407 goto out_up; 408 409 if (unlikely(vma->vm_start > address)) { 410 if (!(vma->vm_flags & VM_GROWSDOWN)) 411 goto out_up; 412 if (expand_stack(vma, address)) 413 goto out_up; 414 } 415 416 /* 417 * Ok, we have a good vm_area for this memory access, so 418 * we can handle it.. 419 */ 420 fault = VM_FAULT_BADACCESS; 421 if (unlikely(!(vma->vm_flags & access))) 422 goto out_up; 423 424 if (is_vm_hugetlb_page(vma)) 425 address &= HPAGE_MASK; 426 /* 427 * If for any reason at all we couldn't handle the fault, 428 * make sure we exit gracefully rather than endlessly redo 429 * the fault. 430 */ 431 fault = handle_mm_fault(vma, address, flags, regs); 432 if (fault_signal_pending(fault, regs)) { 433 fault = VM_FAULT_SIGNAL; 434 if (flags & FAULT_FLAG_RETRY_NOWAIT) 435 goto out_up; 436 goto out; 437 } 438 439 /* The fault is fully completed (including releasing mmap lock) */ 440 if (fault & VM_FAULT_COMPLETED) { 441 if (gmap) { 442 mmap_read_lock(mm); 443 goto out_gmap; 444 } 445 fault = 0; 446 goto out; 447 } 448 449 if (unlikely(fault & VM_FAULT_ERROR)) 450 goto out_up; 451 452 if (fault & VM_FAULT_RETRY) { 453 if (IS_ENABLED(CONFIG_PGSTE) && gmap && 454 (flags & FAULT_FLAG_RETRY_NOWAIT)) { 455 /* 456 * FAULT_FLAG_RETRY_NOWAIT has been set, mmap_lock has 457 * not been released 458 */ 459 current->thread.gmap_pfault = 1; 460 fault = VM_FAULT_PFAULT; 461 goto out_up; 462 } 463 flags &= ~FAULT_FLAG_RETRY_NOWAIT; 464 flags |= FAULT_FLAG_TRIED; 465 mmap_read_lock(mm); 466 goto retry; 467 } 468 out_gmap: 469 if (IS_ENABLED(CONFIG_PGSTE) && gmap) { 470 address = __gmap_link(gmap, current->thread.gmap_addr, 471 address); 472 if (address == -EFAULT) { 473 fault = VM_FAULT_BADMAP; 474 goto out_up; 475 } 476 if (address == -ENOMEM) { 477 fault = VM_FAULT_OOM; 478 goto out_up; 479 } 480 } 481 fault = 0; 482 out_up: 483 mmap_read_unlock(mm); 484 out: 485 return fault; 486 } 487 488 void do_protection_exception(struct pt_regs *regs) 489 { 490 unsigned long trans_exc_code; 491 int access; 492 vm_fault_t fault; 493 494 trans_exc_code = regs->int_parm_long; 495 /* 496 * Protection exceptions are suppressing, decrement psw address. 497 * The exception to this rule are aborted transactions, for these 498 * the PSW already points to the correct location. 499 */ 500 if (!(regs->int_code & 0x200)) 501 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16); 502 /* 503 * Check for low-address protection. This needs to be treated 504 * as a special case because the translation exception code 505 * field is not guaranteed to contain valid data in this case. 506 */ 507 if (unlikely(!(trans_exc_code & 4))) { 508 do_low_address(regs); 509 return; 510 } 511 if (unlikely(MACHINE_HAS_NX && (trans_exc_code & 0x80))) { 512 regs->int_parm_long = (trans_exc_code & ~PAGE_MASK) | 513 (regs->psw.addr & PAGE_MASK); 514 access = VM_EXEC; 515 fault = VM_FAULT_BADACCESS; 516 } else { 517 access = VM_WRITE; 518 fault = do_exception(regs, access); 519 } 520 if (unlikely(fault)) 521 do_fault_error(regs, access, fault); 522 } 523 NOKPROBE_SYMBOL(do_protection_exception); 524 525 void do_dat_exception(struct pt_regs *regs) 526 { 527 int access; 528 vm_fault_t fault; 529 530 access = VM_ACCESS_FLAGS; 531 fault = do_exception(regs, access); 532 if (unlikely(fault)) 533 do_fault_error(regs, access, fault); 534 } 535 NOKPROBE_SYMBOL(do_dat_exception); 536 537 #ifdef CONFIG_PFAULT 538 /* 539 * 'pfault' pseudo page faults routines. 540 */ 541 static int pfault_disable; 542 543 static int __init nopfault(char *str) 544 { 545 pfault_disable = 1; 546 return 1; 547 } 548 549 __setup("nopfault", nopfault); 550 551 struct pfault_refbk { 552 u16 refdiagc; 553 u16 reffcode; 554 u16 refdwlen; 555 u16 refversn; 556 u64 refgaddr; 557 u64 refselmk; 558 u64 refcmpmk; 559 u64 reserved; 560 } __attribute__ ((packed, aligned(8))); 561 562 static struct pfault_refbk pfault_init_refbk = { 563 .refdiagc = 0x258, 564 .reffcode = 0, 565 .refdwlen = 5, 566 .refversn = 2, 567 .refgaddr = __LC_LPP, 568 .refselmk = 1ULL << 48, 569 .refcmpmk = 1ULL << 48, 570 .reserved = __PF_RES_FIELD 571 }; 572 573 int pfault_init(void) 574 { 575 int rc; 576 577 if (pfault_disable) 578 return -1; 579 diag_stat_inc(DIAG_STAT_X258); 580 asm volatile( 581 " diag %1,%0,0x258\n" 582 "0: j 2f\n" 583 "1: la %0,8\n" 584 "2:\n" 585 EX_TABLE(0b,1b) 586 : "=d" (rc) 587 : "a" (&pfault_init_refbk), "m" (pfault_init_refbk) : "cc"); 588 return rc; 589 } 590 591 static struct pfault_refbk pfault_fini_refbk = { 592 .refdiagc = 0x258, 593 .reffcode = 1, 594 .refdwlen = 5, 595 .refversn = 2, 596 }; 597 598 void pfault_fini(void) 599 { 600 601 if (pfault_disable) 602 return; 603 diag_stat_inc(DIAG_STAT_X258); 604 asm volatile( 605 " diag %0,0,0x258\n" 606 "0: nopr %%r7\n" 607 EX_TABLE(0b,0b) 608 : : "a" (&pfault_fini_refbk), "m" (pfault_fini_refbk) : "cc"); 609 } 610 611 static DEFINE_SPINLOCK(pfault_lock); 612 static LIST_HEAD(pfault_list); 613 614 #define PF_COMPLETE 0x0080 615 616 /* 617 * The mechanism of our pfault code: if Linux is running as guest, runs a user 618 * space process and the user space process accesses a page that the host has 619 * paged out we get a pfault interrupt. 620 * 621 * This allows us, within the guest, to schedule a different process. Without 622 * this mechanism the host would have to suspend the whole virtual cpu until 623 * the page has been paged in. 624 * 625 * So when we get such an interrupt then we set the state of the current task 626 * to uninterruptible and also set the need_resched flag. Both happens within 627 * interrupt context(!). If we later on want to return to user space we 628 * recognize the need_resched flag and then call schedule(). It's not very 629 * obvious how this works... 630 * 631 * Of course we have a lot of additional fun with the completion interrupt (-> 632 * host signals that a page of a process has been paged in and the process can 633 * continue to run). This interrupt can arrive on any cpu and, since we have 634 * virtual cpus, actually appear before the interrupt that signals that a page 635 * is missing. 636 */ 637 static void pfault_interrupt(struct ext_code ext_code, 638 unsigned int param32, unsigned long param64) 639 { 640 struct task_struct *tsk; 641 __u16 subcode; 642 pid_t pid; 643 644 /* 645 * Get the external interruption subcode & pfault initial/completion 646 * signal bit. VM stores this in the 'cpu address' field associated 647 * with the external interrupt. 648 */ 649 subcode = ext_code.subcode; 650 if ((subcode & 0xff00) != __SUBCODE_MASK) 651 return; 652 inc_irq_stat(IRQEXT_PFL); 653 /* Get the token (= pid of the affected task). */ 654 pid = param64 & LPP_PID_MASK; 655 rcu_read_lock(); 656 tsk = find_task_by_pid_ns(pid, &init_pid_ns); 657 if (tsk) 658 get_task_struct(tsk); 659 rcu_read_unlock(); 660 if (!tsk) 661 return; 662 spin_lock(&pfault_lock); 663 if (subcode & PF_COMPLETE) { 664 /* signal bit is set -> a page has been swapped in by VM */ 665 if (tsk->thread.pfault_wait == 1) { 666 /* Initial interrupt was faster than the completion 667 * interrupt. pfault_wait is valid. Set pfault_wait 668 * back to zero and wake up the process. This can 669 * safely be done because the task is still sleeping 670 * and can't produce new pfaults. */ 671 tsk->thread.pfault_wait = 0; 672 list_del(&tsk->thread.list); 673 wake_up_process(tsk); 674 put_task_struct(tsk); 675 } else { 676 /* Completion interrupt was faster than initial 677 * interrupt. Set pfault_wait to -1 so the initial 678 * interrupt doesn't put the task to sleep. 679 * If the task is not running, ignore the completion 680 * interrupt since it must be a leftover of a PFAULT 681 * CANCEL operation which didn't remove all pending 682 * completion interrupts. */ 683 if (task_is_running(tsk)) 684 tsk->thread.pfault_wait = -1; 685 } 686 } else { 687 /* signal bit not set -> a real page is missing. */ 688 if (WARN_ON_ONCE(tsk != current)) 689 goto out; 690 if (tsk->thread.pfault_wait == 1) { 691 /* Already on the list with a reference: put to sleep */ 692 goto block; 693 } else if (tsk->thread.pfault_wait == -1) { 694 /* Completion interrupt was faster than the initial 695 * interrupt (pfault_wait == -1). Set pfault_wait 696 * back to zero and exit. */ 697 tsk->thread.pfault_wait = 0; 698 } else { 699 /* Initial interrupt arrived before completion 700 * interrupt. Let the task sleep. 701 * An extra task reference is needed since a different 702 * cpu may set the task state to TASK_RUNNING again 703 * before the scheduler is reached. */ 704 get_task_struct(tsk); 705 tsk->thread.pfault_wait = 1; 706 list_add(&tsk->thread.list, &pfault_list); 707 block: 708 /* Since this must be a userspace fault, there 709 * is no kernel task state to trample. Rely on the 710 * return to userspace schedule() to block. */ 711 __set_current_state(TASK_UNINTERRUPTIBLE); 712 set_tsk_need_resched(tsk); 713 set_preempt_need_resched(); 714 } 715 } 716 out: 717 spin_unlock(&pfault_lock); 718 put_task_struct(tsk); 719 } 720 721 static int pfault_cpu_dead(unsigned int cpu) 722 { 723 struct thread_struct *thread, *next; 724 struct task_struct *tsk; 725 726 spin_lock_irq(&pfault_lock); 727 list_for_each_entry_safe(thread, next, &pfault_list, list) { 728 thread->pfault_wait = 0; 729 list_del(&thread->list); 730 tsk = container_of(thread, struct task_struct, thread); 731 wake_up_process(tsk); 732 put_task_struct(tsk); 733 } 734 spin_unlock_irq(&pfault_lock); 735 return 0; 736 } 737 738 static int __init pfault_irq_init(void) 739 { 740 int rc; 741 742 rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); 743 if (rc) 744 goto out_extint; 745 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP; 746 if (rc) 747 goto out_pfault; 748 irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL); 749 cpuhp_setup_state_nocalls(CPUHP_S390_PFAULT_DEAD, "s390/pfault:dead", 750 NULL, pfault_cpu_dead); 751 return 0; 752 753 out_pfault: 754 unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); 755 out_extint: 756 pfault_disable = 1; 757 return rc; 758 } 759 early_initcall(pfault_irq_init); 760 761 #endif /* CONFIG_PFAULT */ 762 763 #if IS_ENABLED(CONFIG_PGSTE) 764 765 void do_secure_storage_access(struct pt_regs *regs) 766 { 767 unsigned long addr = regs->int_parm_long & __FAIL_ADDR_MASK; 768 struct vm_area_struct *vma; 769 struct mm_struct *mm; 770 struct page *page; 771 struct gmap *gmap; 772 int rc; 773 774 /* 775 * bit 61 tells us if the address is valid, if it's not we 776 * have a major problem and should stop the kernel or send a 777 * SIGSEGV to the process. Unfortunately bit 61 is not 778 * reliable without the misc UV feature so we need to check 779 * for that as well. 780 */ 781 if (test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications) && 782 !test_bit_inv(61, ®s->int_parm_long)) { 783 /* 784 * When this happens, userspace did something that it 785 * was not supposed to do, e.g. branching into secure 786 * memory. Trigger a segmentation fault. 787 */ 788 if (user_mode(regs)) { 789 send_sig(SIGSEGV, current, 0); 790 return; 791 } 792 793 /* 794 * The kernel should never run into this case and we 795 * have no way out of this situation. 796 */ 797 panic("Unexpected PGM 0x3d with TEID bit 61=0"); 798 } 799 800 switch (get_fault_type(regs)) { 801 case GMAP_FAULT: 802 mm = current->mm; 803 gmap = (struct gmap *)S390_lowcore.gmap; 804 mmap_read_lock(mm); 805 addr = __gmap_translate(gmap, addr); 806 mmap_read_unlock(mm); 807 if (IS_ERR_VALUE(addr)) { 808 do_fault_error(regs, VM_ACCESS_FLAGS, VM_FAULT_BADMAP); 809 break; 810 } 811 fallthrough; 812 case USER_FAULT: 813 mm = current->mm; 814 mmap_read_lock(mm); 815 vma = find_vma(mm, addr); 816 if (!vma) { 817 mmap_read_unlock(mm); 818 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP); 819 break; 820 } 821 page = follow_page(vma, addr, FOLL_WRITE | FOLL_GET); 822 if (IS_ERR_OR_NULL(page)) { 823 mmap_read_unlock(mm); 824 break; 825 } 826 if (arch_make_page_accessible(page)) 827 send_sig(SIGSEGV, current, 0); 828 put_page(page); 829 mmap_read_unlock(mm); 830 break; 831 case KERNEL_FAULT: 832 page = phys_to_page(addr); 833 if (unlikely(!try_get_page(page))) 834 break; 835 rc = arch_make_page_accessible(page); 836 put_page(page); 837 if (rc) 838 BUG(); 839 break; 840 default: 841 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP); 842 WARN_ON_ONCE(1); 843 } 844 } 845 NOKPROBE_SYMBOL(do_secure_storage_access); 846 847 void do_non_secure_storage_access(struct pt_regs *regs) 848 { 849 unsigned long gaddr = regs->int_parm_long & __FAIL_ADDR_MASK; 850 struct gmap *gmap = (struct gmap *)S390_lowcore.gmap; 851 852 if (get_fault_type(regs) != GMAP_FAULT) { 853 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP); 854 WARN_ON_ONCE(1); 855 return; 856 } 857 858 if (gmap_convert_to_secure(gmap, gaddr) == -EINVAL) 859 send_sig(SIGSEGV, current, 0); 860 } 861 NOKPROBE_SYMBOL(do_non_secure_storage_access); 862 863 void do_secure_storage_violation(struct pt_regs *regs) 864 { 865 unsigned long gaddr = regs->int_parm_long & __FAIL_ADDR_MASK; 866 struct gmap *gmap = (struct gmap *)S390_lowcore.gmap; 867 868 /* 869 * If the VM has been rebooted, its address space might still contain 870 * secure pages from the previous boot. 871 * Clear the page so it can be reused. 872 */ 873 if (!gmap_destroy_page(gmap, gaddr)) 874 return; 875 /* 876 * Either KVM messed up the secure guest mapping or the same 877 * page is mapped into multiple secure guests. 878 * 879 * This exception is only triggered when a guest 2 is running 880 * and can therefore never occur in kernel context. 881 */ 882 printk_ratelimited(KERN_WARNING 883 "Secure storage violation in task: %s, pid %d\n", 884 current->comm, current->pid); 885 send_sig(SIGSEGV, current, 0); 886 } 887 888 #endif /* CONFIG_PGSTE */ 889