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