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, vm_fault_t fault) 272 { 273 int si_code; 274 275 switch (fault) { 276 case VM_FAULT_BADACCESS: 277 case VM_FAULT_BADMAP: 278 /* Bad memory access. Check if it is kernel or user space. */ 279 if (user_mode(regs)) { 280 /* User mode accesses just cause a SIGSEGV */ 281 si_code = (fault == VM_FAULT_BADMAP) ? 282 SEGV_MAPERR : SEGV_ACCERR; 283 do_sigsegv(regs, si_code); 284 break; 285 } 286 fallthrough; 287 case VM_FAULT_BADCONTEXT: 288 case VM_FAULT_PFAULT: 289 do_no_context(regs); 290 break; 291 case VM_FAULT_SIGNAL: 292 if (!user_mode(regs)) 293 do_no_context(regs); 294 break; 295 default: /* fault & VM_FAULT_ERROR */ 296 if (fault & VM_FAULT_OOM) { 297 if (!user_mode(regs)) 298 do_no_context(regs); 299 else 300 pagefault_out_of_memory(); 301 } else if (fault & VM_FAULT_SIGSEGV) { 302 /* Kernel mode? Handle exceptions or die */ 303 if (!user_mode(regs)) 304 do_no_context(regs); 305 else 306 do_sigsegv(regs, SEGV_MAPERR); 307 } else if (fault & VM_FAULT_SIGBUS) { 308 /* Kernel mode? Handle exceptions or die */ 309 if (!user_mode(regs)) 310 do_no_context(regs); 311 else 312 do_sigbus(regs); 313 } else 314 BUG(); 315 break; 316 } 317 } 318 319 /* 320 * This routine handles page faults. It determines the address, 321 * and the problem, and then passes it off to one of the appropriate 322 * routines. 323 * 324 * interruption code (int_code): 325 * 04 Protection -> Write-Protection (suppression) 326 * 10 Segment translation -> Not present (nullification) 327 * 11 Page translation -> Not present (nullification) 328 * 3b Region third trans. -> Not present (nullification) 329 */ 330 static inline vm_fault_t do_exception(struct pt_regs *regs, int access) 331 { 332 struct gmap *gmap; 333 struct task_struct *tsk; 334 struct mm_struct *mm; 335 struct vm_area_struct *vma; 336 enum fault_type type; 337 unsigned long trans_exc_code; 338 unsigned long address; 339 unsigned int flags; 340 vm_fault_t fault; 341 bool is_write; 342 343 tsk = current; 344 /* 345 * The instruction that caused the program check has 346 * been nullified. Don't signal single step via SIGTRAP. 347 */ 348 clear_thread_flag(TIF_PER_TRAP); 349 350 if (kprobe_page_fault(regs, 14)) 351 return 0; 352 353 mm = tsk->mm; 354 trans_exc_code = regs->int_parm_long; 355 address = trans_exc_code & __FAIL_ADDR_MASK; 356 is_write = (trans_exc_code & store_indication) == 0x400; 357 358 /* 359 * Verify that the fault happened in user space, that 360 * we are not in an interrupt and that there is a 361 * user context. 362 */ 363 fault = VM_FAULT_BADCONTEXT; 364 type = get_fault_type(regs); 365 switch (type) { 366 case KERNEL_FAULT: 367 if (kfence_handle_page_fault(address, is_write, regs)) 368 return 0; 369 goto out; 370 case USER_FAULT: 371 case GMAP_FAULT: 372 if (faulthandler_disabled() || !mm) 373 goto out; 374 break; 375 } 376 377 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 378 flags = FAULT_FLAG_DEFAULT; 379 if (user_mode(regs)) 380 flags |= FAULT_FLAG_USER; 381 if (is_write) 382 access = VM_WRITE; 383 if (access == VM_WRITE) 384 flags |= FAULT_FLAG_WRITE; 385 mmap_read_lock(mm); 386 387 gmap = NULL; 388 if (IS_ENABLED(CONFIG_PGSTE) && type == GMAP_FAULT) { 389 gmap = (struct gmap *) S390_lowcore.gmap; 390 current->thread.gmap_addr = address; 391 current->thread.gmap_write_flag = !!(flags & FAULT_FLAG_WRITE); 392 current->thread.gmap_int_code = regs->int_code & 0xffff; 393 address = __gmap_translate(gmap, address); 394 if (address == -EFAULT) { 395 fault = VM_FAULT_BADMAP; 396 goto out_up; 397 } 398 if (gmap->pfault_enabled) 399 flags |= FAULT_FLAG_RETRY_NOWAIT; 400 } 401 402 retry: 403 fault = VM_FAULT_BADMAP; 404 vma = find_vma(mm, address); 405 if (!vma) 406 goto out_up; 407 408 if (unlikely(vma->vm_start > address)) { 409 if (!(vma->vm_flags & VM_GROWSDOWN)) 410 goto out_up; 411 if (expand_stack(vma, address)) 412 goto out_up; 413 } 414 415 /* 416 * Ok, we have a good vm_area for this memory access, so 417 * we can handle it.. 418 */ 419 fault = VM_FAULT_BADACCESS; 420 if (unlikely(!(vma->vm_flags & access))) 421 goto out_up; 422 423 /* 424 * If for any reason at all we couldn't handle the fault, 425 * make sure we exit gracefully rather than endlessly redo 426 * the fault. 427 */ 428 fault = handle_mm_fault(vma, address, flags, regs); 429 if (fault_signal_pending(fault, regs)) { 430 fault = VM_FAULT_SIGNAL; 431 if (flags & FAULT_FLAG_RETRY_NOWAIT) 432 goto out_up; 433 goto out; 434 } 435 436 /* The fault is fully completed (including releasing mmap lock) */ 437 if (fault & VM_FAULT_COMPLETED) { 438 if (gmap) { 439 mmap_read_lock(mm); 440 goto out_gmap; 441 } 442 fault = 0; 443 goto out; 444 } 445 446 if (unlikely(fault & VM_FAULT_ERROR)) 447 goto out_up; 448 449 if (fault & VM_FAULT_RETRY) { 450 if (IS_ENABLED(CONFIG_PGSTE) && gmap && 451 (flags & FAULT_FLAG_RETRY_NOWAIT)) { 452 /* 453 * FAULT_FLAG_RETRY_NOWAIT has been set, mmap_lock has 454 * not been released 455 */ 456 current->thread.gmap_pfault = 1; 457 fault = VM_FAULT_PFAULT; 458 goto out_up; 459 } 460 flags &= ~FAULT_FLAG_RETRY_NOWAIT; 461 flags |= FAULT_FLAG_TRIED; 462 mmap_read_lock(mm); 463 goto retry; 464 } 465 out_gmap: 466 if (IS_ENABLED(CONFIG_PGSTE) && gmap) { 467 address = __gmap_link(gmap, current->thread.gmap_addr, 468 address); 469 if (address == -EFAULT) { 470 fault = VM_FAULT_BADMAP; 471 goto out_up; 472 } 473 if (address == -ENOMEM) { 474 fault = VM_FAULT_OOM; 475 goto out_up; 476 } 477 } 478 fault = 0; 479 out_up: 480 mmap_read_unlock(mm); 481 out: 482 return fault; 483 } 484 485 void do_protection_exception(struct pt_regs *regs) 486 { 487 unsigned long trans_exc_code; 488 int access; 489 vm_fault_t fault; 490 491 trans_exc_code = regs->int_parm_long; 492 /* 493 * Protection exceptions are suppressing, decrement psw address. 494 * The exception to this rule are aborted transactions, for these 495 * the PSW already points to the correct location. 496 */ 497 if (!(regs->int_code & 0x200)) 498 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16); 499 /* 500 * Check for low-address protection. This needs to be treated 501 * as a special case because the translation exception code 502 * field is not guaranteed to contain valid data in this case. 503 */ 504 if (unlikely(!(trans_exc_code & 4))) { 505 do_low_address(regs); 506 return; 507 } 508 if (unlikely(MACHINE_HAS_NX && (trans_exc_code & 0x80))) { 509 regs->int_parm_long = (trans_exc_code & ~PAGE_MASK) | 510 (regs->psw.addr & PAGE_MASK); 511 access = VM_EXEC; 512 fault = VM_FAULT_BADACCESS; 513 } else { 514 access = VM_WRITE; 515 fault = do_exception(regs, access); 516 } 517 if (unlikely(fault)) 518 do_fault_error(regs, fault); 519 } 520 NOKPROBE_SYMBOL(do_protection_exception); 521 522 void do_dat_exception(struct pt_regs *regs) 523 { 524 int access; 525 vm_fault_t fault; 526 527 access = VM_ACCESS_FLAGS; 528 fault = do_exception(regs, access); 529 if (unlikely(fault)) 530 do_fault_error(regs, fault); 531 } 532 NOKPROBE_SYMBOL(do_dat_exception); 533 534 #ifdef CONFIG_PFAULT 535 /* 536 * 'pfault' pseudo page faults routines. 537 */ 538 static int pfault_disable; 539 540 static int __init nopfault(char *str) 541 { 542 pfault_disable = 1; 543 return 1; 544 } 545 546 __setup("nopfault", nopfault); 547 548 struct pfault_refbk { 549 u16 refdiagc; 550 u16 reffcode; 551 u16 refdwlen; 552 u16 refversn; 553 u64 refgaddr; 554 u64 refselmk; 555 u64 refcmpmk; 556 u64 reserved; 557 } __attribute__ ((packed, aligned(8))); 558 559 static struct pfault_refbk pfault_init_refbk = { 560 .refdiagc = 0x258, 561 .reffcode = 0, 562 .refdwlen = 5, 563 .refversn = 2, 564 .refgaddr = __LC_LPP, 565 .refselmk = 1ULL << 48, 566 .refcmpmk = 1ULL << 48, 567 .reserved = __PF_RES_FIELD 568 }; 569 570 int pfault_init(void) 571 { 572 int rc; 573 574 if (pfault_disable) 575 return -1; 576 diag_stat_inc(DIAG_STAT_X258); 577 asm volatile( 578 " diag %1,%0,0x258\n" 579 "0: j 2f\n" 580 "1: la %0,8\n" 581 "2:\n" 582 EX_TABLE(0b,1b) 583 : "=d" (rc) 584 : "a" (&pfault_init_refbk), "m" (pfault_init_refbk) : "cc"); 585 return rc; 586 } 587 588 static struct pfault_refbk pfault_fini_refbk = { 589 .refdiagc = 0x258, 590 .reffcode = 1, 591 .refdwlen = 5, 592 .refversn = 2, 593 }; 594 595 void pfault_fini(void) 596 { 597 598 if (pfault_disable) 599 return; 600 diag_stat_inc(DIAG_STAT_X258); 601 asm volatile( 602 " diag %0,0,0x258\n" 603 "0: nopr %%r7\n" 604 EX_TABLE(0b,0b) 605 : : "a" (&pfault_fini_refbk), "m" (pfault_fini_refbk) : "cc"); 606 } 607 608 static DEFINE_SPINLOCK(pfault_lock); 609 static LIST_HEAD(pfault_list); 610 611 #define PF_COMPLETE 0x0080 612 613 /* 614 * The mechanism of our pfault code: if Linux is running as guest, runs a user 615 * space process and the user space process accesses a page that the host has 616 * paged out we get a pfault interrupt. 617 * 618 * This allows us, within the guest, to schedule a different process. Without 619 * this mechanism the host would have to suspend the whole virtual cpu until 620 * the page has been paged in. 621 * 622 * So when we get such an interrupt then we set the state of the current task 623 * to uninterruptible and also set the need_resched flag. Both happens within 624 * interrupt context(!). If we later on want to return to user space we 625 * recognize the need_resched flag and then call schedule(). It's not very 626 * obvious how this works... 627 * 628 * Of course we have a lot of additional fun with the completion interrupt (-> 629 * host signals that a page of a process has been paged in and the process can 630 * continue to run). This interrupt can arrive on any cpu and, since we have 631 * virtual cpus, actually appear before the interrupt that signals that a page 632 * is missing. 633 */ 634 static void pfault_interrupt(struct ext_code ext_code, 635 unsigned int param32, unsigned long param64) 636 { 637 struct task_struct *tsk; 638 __u16 subcode; 639 pid_t pid; 640 641 /* 642 * Get the external interruption subcode & pfault initial/completion 643 * signal bit. VM stores this in the 'cpu address' field associated 644 * with the external interrupt. 645 */ 646 subcode = ext_code.subcode; 647 if ((subcode & 0xff00) != __SUBCODE_MASK) 648 return; 649 inc_irq_stat(IRQEXT_PFL); 650 /* Get the token (= pid of the affected task). */ 651 pid = param64 & LPP_PID_MASK; 652 rcu_read_lock(); 653 tsk = find_task_by_pid_ns(pid, &init_pid_ns); 654 if (tsk) 655 get_task_struct(tsk); 656 rcu_read_unlock(); 657 if (!tsk) 658 return; 659 spin_lock(&pfault_lock); 660 if (subcode & PF_COMPLETE) { 661 /* signal bit is set -> a page has been swapped in by VM */ 662 if (tsk->thread.pfault_wait == 1) { 663 /* Initial interrupt was faster than the completion 664 * interrupt. pfault_wait is valid. Set pfault_wait 665 * back to zero and wake up the process. This can 666 * safely be done because the task is still sleeping 667 * and can't produce new pfaults. */ 668 tsk->thread.pfault_wait = 0; 669 list_del(&tsk->thread.list); 670 wake_up_process(tsk); 671 put_task_struct(tsk); 672 } else { 673 /* Completion interrupt was faster than initial 674 * interrupt. Set pfault_wait to -1 so the initial 675 * interrupt doesn't put the task to sleep. 676 * If the task is not running, ignore the completion 677 * interrupt since it must be a leftover of a PFAULT 678 * CANCEL operation which didn't remove all pending 679 * completion interrupts. */ 680 if (task_is_running(tsk)) 681 tsk->thread.pfault_wait = -1; 682 } 683 } else { 684 /* signal bit not set -> a real page is missing. */ 685 if (WARN_ON_ONCE(tsk != current)) 686 goto out; 687 if (tsk->thread.pfault_wait == 1) { 688 /* Already on the list with a reference: put to sleep */ 689 goto block; 690 } else if (tsk->thread.pfault_wait == -1) { 691 /* Completion interrupt was faster than the initial 692 * interrupt (pfault_wait == -1). Set pfault_wait 693 * back to zero and exit. */ 694 tsk->thread.pfault_wait = 0; 695 } else { 696 /* Initial interrupt arrived before completion 697 * interrupt. Let the task sleep. 698 * An extra task reference is needed since a different 699 * cpu may set the task state to TASK_RUNNING again 700 * before the scheduler is reached. */ 701 get_task_struct(tsk); 702 tsk->thread.pfault_wait = 1; 703 list_add(&tsk->thread.list, &pfault_list); 704 block: 705 /* Since this must be a userspace fault, there 706 * is no kernel task state to trample. Rely on the 707 * return to userspace schedule() to block. */ 708 __set_current_state(TASK_UNINTERRUPTIBLE); 709 set_tsk_need_resched(tsk); 710 set_preempt_need_resched(); 711 } 712 } 713 out: 714 spin_unlock(&pfault_lock); 715 put_task_struct(tsk); 716 } 717 718 static int pfault_cpu_dead(unsigned int cpu) 719 { 720 struct thread_struct *thread, *next; 721 struct task_struct *tsk; 722 723 spin_lock_irq(&pfault_lock); 724 list_for_each_entry_safe(thread, next, &pfault_list, list) { 725 thread->pfault_wait = 0; 726 list_del(&thread->list); 727 tsk = container_of(thread, struct task_struct, thread); 728 wake_up_process(tsk); 729 put_task_struct(tsk); 730 } 731 spin_unlock_irq(&pfault_lock); 732 return 0; 733 } 734 735 static int __init pfault_irq_init(void) 736 { 737 int rc; 738 739 rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); 740 if (rc) 741 goto out_extint; 742 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP; 743 if (rc) 744 goto out_pfault; 745 irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL); 746 cpuhp_setup_state_nocalls(CPUHP_S390_PFAULT_DEAD, "s390/pfault:dead", 747 NULL, pfault_cpu_dead); 748 return 0; 749 750 out_pfault: 751 unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); 752 out_extint: 753 pfault_disable = 1; 754 return rc; 755 } 756 early_initcall(pfault_irq_init); 757 758 #endif /* CONFIG_PFAULT */ 759 760 #if IS_ENABLED(CONFIG_PGSTE) 761 762 void do_secure_storage_access(struct pt_regs *regs) 763 { 764 unsigned long addr = regs->int_parm_long & __FAIL_ADDR_MASK; 765 struct vm_area_struct *vma; 766 struct mm_struct *mm; 767 struct page *page; 768 struct gmap *gmap; 769 int rc; 770 771 /* 772 * bit 61 tells us if the address is valid, if it's not we 773 * have a major problem and should stop the kernel or send a 774 * SIGSEGV to the process. Unfortunately bit 61 is not 775 * reliable without the misc UV feature so we need to check 776 * for that as well. 777 */ 778 if (test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications) && 779 !test_bit_inv(61, ®s->int_parm_long)) { 780 /* 781 * When this happens, userspace did something that it 782 * was not supposed to do, e.g. branching into secure 783 * memory. Trigger a segmentation fault. 784 */ 785 if (user_mode(regs)) { 786 send_sig(SIGSEGV, current, 0); 787 return; 788 } 789 790 /* 791 * The kernel should never run into this case and we 792 * have no way out of this situation. 793 */ 794 panic("Unexpected PGM 0x3d with TEID bit 61=0"); 795 } 796 797 switch (get_fault_type(regs)) { 798 case GMAP_FAULT: 799 mm = current->mm; 800 gmap = (struct gmap *)S390_lowcore.gmap; 801 mmap_read_lock(mm); 802 addr = __gmap_translate(gmap, addr); 803 mmap_read_unlock(mm); 804 if (IS_ERR_VALUE(addr)) { 805 do_fault_error(regs, VM_FAULT_BADMAP); 806 break; 807 } 808 fallthrough; 809 case USER_FAULT: 810 mm = current->mm; 811 mmap_read_lock(mm); 812 vma = find_vma(mm, addr); 813 if (!vma) { 814 mmap_read_unlock(mm); 815 do_fault_error(regs, VM_FAULT_BADMAP); 816 break; 817 } 818 page = follow_page(vma, addr, FOLL_WRITE | FOLL_GET); 819 if (IS_ERR_OR_NULL(page)) { 820 mmap_read_unlock(mm); 821 break; 822 } 823 if (arch_make_page_accessible(page)) 824 send_sig(SIGSEGV, current, 0); 825 put_page(page); 826 mmap_read_unlock(mm); 827 break; 828 case KERNEL_FAULT: 829 page = phys_to_page(addr); 830 if (unlikely(!try_get_page(page))) 831 break; 832 rc = arch_make_page_accessible(page); 833 put_page(page); 834 if (rc) 835 BUG(); 836 break; 837 default: 838 do_fault_error(regs, VM_FAULT_BADMAP); 839 WARN_ON_ONCE(1); 840 } 841 } 842 NOKPROBE_SYMBOL(do_secure_storage_access); 843 844 void do_non_secure_storage_access(struct pt_regs *regs) 845 { 846 unsigned long gaddr = regs->int_parm_long & __FAIL_ADDR_MASK; 847 struct gmap *gmap = (struct gmap *)S390_lowcore.gmap; 848 849 if (get_fault_type(regs) != GMAP_FAULT) { 850 do_fault_error(regs, VM_FAULT_BADMAP); 851 WARN_ON_ONCE(1); 852 return; 853 } 854 855 if (gmap_convert_to_secure(gmap, gaddr) == -EINVAL) 856 send_sig(SIGSEGV, current, 0); 857 } 858 NOKPROBE_SYMBOL(do_non_secure_storage_access); 859 860 void do_secure_storage_violation(struct pt_regs *regs) 861 { 862 unsigned long gaddr = regs->int_parm_long & __FAIL_ADDR_MASK; 863 struct gmap *gmap = (struct gmap *)S390_lowcore.gmap; 864 865 /* 866 * If the VM has been rebooted, its address space might still contain 867 * secure pages from the previous boot. 868 * Clear the page so it can be reused. 869 */ 870 if (!gmap_destroy_page(gmap, gaddr)) 871 return; 872 /* 873 * Either KVM messed up the secure guest mapping or the same 874 * page is mapped into multiple secure guests. 875 * 876 * This exception is only triggered when a guest 2 is running 877 * and can therefore never occur in kernel context. 878 */ 879 printk_ratelimited(KERN_WARNING 880 "Secure storage violation in task: %s, pid %d\n", 881 current->comm, current->pid); 882 send_sig(SIGSEGV, current, 0); 883 } 884 885 #endif /* CONFIG_PGSTE */ 886