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 /* 50 * Allocate private vm_fault_reason from top. Please make sure it won't 51 * collide with vm_fault_reason. 52 */ 53 #define VM_FAULT_BADCONTEXT ((__force vm_fault_t)0x80000000) 54 #define VM_FAULT_BADMAP ((__force vm_fault_t)0x40000000) 55 #define VM_FAULT_BADACCESS ((__force vm_fault_t)0x20000000) 56 #define VM_FAULT_SIGNAL ((__force vm_fault_t)0x10000000) 57 #define VM_FAULT_PFAULT ((__force vm_fault_t)0x8000000) 58 59 enum fault_type { 60 KERNEL_FAULT, 61 USER_FAULT, 62 GMAP_FAULT, 63 }; 64 65 static unsigned long store_indication __read_mostly; 66 67 static int __init fault_init(void) 68 { 69 if (test_facility(75)) 70 store_indication = 0xc00; 71 return 0; 72 } 73 early_initcall(fault_init); 74 75 /* 76 * Find out which address space caused the exception. 77 */ 78 static enum fault_type get_fault_type(struct pt_regs *regs) 79 { 80 unsigned long trans_exc_code; 81 82 trans_exc_code = regs->int_parm_long & 3; 83 if (likely(trans_exc_code == 0)) { 84 /* primary space exception */ 85 if (user_mode(regs)) 86 return USER_FAULT; 87 if (!IS_ENABLED(CONFIG_PGSTE)) 88 return KERNEL_FAULT; 89 if (test_pt_regs_flag(regs, PIF_GUEST_FAULT)) 90 return GMAP_FAULT; 91 return KERNEL_FAULT; 92 } 93 if (trans_exc_code == 2) 94 return USER_FAULT; 95 if (trans_exc_code == 1) { 96 /* access register mode, not used in the kernel */ 97 return USER_FAULT; 98 } 99 /* home space exception -> access via kernel ASCE */ 100 return KERNEL_FAULT; 101 } 102 103 static unsigned long get_fault_address(struct pt_regs *regs) 104 { 105 unsigned long trans_exc_code = regs->int_parm_long; 106 107 return trans_exc_code & __FAIL_ADDR_MASK; 108 } 109 110 static bool fault_is_write(struct pt_regs *regs) 111 { 112 unsigned long trans_exc_code = regs->int_parm_long; 113 114 return (trans_exc_code & store_indication) == 0x400; 115 } 116 117 static int bad_address(void *p) 118 { 119 unsigned long dummy; 120 121 return get_kernel_nofault(dummy, (unsigned long *)p); 122 } 123 124 static void dump_pagetable(unsigned long asce, unsigned long address) 125 { 126 unsigned long *table = __va(asce & _ASCE_ORIGIN); 127 128 pr_alert("AS:%016lx ", asce); 129 switch (asce & _ASCE_TYPE_MASK) { 130 case _ASCE_TYPE_REGION1: 131 table += (address & _REGION1_INDEX) >> _REGION1_SHIFT; 132 if (bad_address(table)) 133 goto bad; 134 pr_cont("R1:%016lx ", *table); 135 if (*table & _REGION_ENTRY_INVALID) 136 goto out; 137 table = __va(*table & _REGION_ENTRY_ORIGIN); 138 fallthrough; 139 case _ASCE_TYPE_REGION2: 140 table += (address & _REGION2_INDEX) >> _REGION2_SHIFT; 141 if (bad_address(table)) 142 goto bad; 143 pr_cont("R2:%016lx ", *table); 144 if (*table & _REGION_ENTRY_INVALID) 145 goto out; 146 table = __va(*table & _REGION_ENTRY_ORIGIN); 147 fallthrough; 148 case _ASCE_TYPE_REGION3: 149 table += (address & _REGION3_INDEX) >> _REGION3_SHIFT; 150 if (bad_address(table)) 151 goto bad; 152 pr_cont("R3:%016lx ", *table); 153 if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE)) 154 goto out; 155 table = __va(*table & _REGION_ENTRY_ORIGIN); 156 fallthrough; 157 case _ASCE_TYPE_SEGMENT: 158 table += (address & _SEGMENT_INDEX) >> _SEGMENT_SHIFT; 159 if (bad_address(table)) 160 goto bad; 161 pr_cont("S:%016lx ", *table); 162 if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE)) 163 goto out; 164 table = __va(*table & _SEGMENT_ENTRY_ORIGIN); 165 } 166 table += (address & _PAGE_INDEX) >> _PAGE_SHIFT; 167 if (bad_address(table)) 168 goto bad; 169 pr_cont("P:%016lx ", *table); 170 out: 171 pr_cont("\n"); 172 return; 173 bad: 174 pr_cont("BAD\n"); 175 } 176 177 static void dump_fault_info(struct pt_regs *regs) 178 { 179 unsigned long asce; 180 181 pr_alert("Failing address: %016lx TEID: %016lx\n", 182 regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long); 183 pr_alert("Fault in "); 184 switch (regs->int_parm_long & 3) { 185 case 3: 186 pr_cont("home space "); 187 break; 188 case 2: 189 pr_cont("secondary space "); 190 break; 191 case 1: 192 pr_cont("access register "); 193 break; 194 case 0: 195 pr_cont("primary space "); 196 break; 197 } 198 pr_cont("mode while using "); 199 switch (get_fault_type(regs)) { 200 case USER_FAULT: 201 asce = S390_lowcore.user_asce; 202 pr_cont("user "); 203 break; 204 case GMAP_FAULT: 205 asce = ((struct gmap *) S390_lowcore.gmap)->asce; 206 pr_cont("gmap "); 207 break; 208 case KERNEL_FAULT: 209 asce = S390_lowcore.kernel_asce; 210 pr_cont("kernel "); 211 break; 212 default: 213 unreachable(); 214 } 215 pr_cont("ASCE.\n"); 216 dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK); 217 } 218 219 int show_unhandled_signals = 1; 220 221 void report_user_fault(struct pt_regs *regs, long signr, int is_mm_fault) 222 { 223 if ((task_pid_nr(current) > 1) && !show_unhandled_signals) 224 return; 225 if (!unhandled_signal(current, signr)) 226 return; 227 if (!printk_ratelimit()) 228 return; 229 printk(KERN_ALERT "User process fault: interruption code %04x ilc:%d ", 230 regs->int_code & 0xffff, regs->int_code >> 17); 231 print_vma_addr(KERN_CONT "in ", regs->psw.addr); 232 printk(KERN_CONT "\n"); 233 if (is_mm_fault) 234 dump_fault_info(regs); 235 show_regs(regs); 236 } 237 238 /* 239 * Send SIGSEGV to task. This is an external routine 240 * to keep the stack usage of do_page_fault small. 241 */ 242 static noinline void do_sigsegv(struct pt_regs *regs, int si_code) 243 { 244 report_user_fault(regs, SIGSEGV, 1); 245 force_sig_fault(SIGSEGV, si_code, 246 (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK)); 247 } 248 249 static noinline void do_no_context(struct pt_regs *regs, vm_fault_t fault) 250 { 251 enum fault_type fault_type; 252 unsigned long address; 253 bool is_write; 254 255 if (fixup_exception(regs)) 256 return; 257 fault_type = get_fault_type(regs); 258 if ((fault_type == KERNEL_FAULT) && (fault == VM_FAULT_BADCONTEXT)) { 259 address = get_fault_address(regs); 260 is_write = fault_is_write(regs); 261 if (kfence_handle_page_fault(address, is_write, regs)) 262 return; 263 } 264 /* 265 * Oops. The kernel tried to access some bad page. We'll have to 266 * terminate things with extreme prejudice. 267 */ 268 if (fault_type == KERNEL_FAULT) 269 printk(KERN_ALERT "Unable to handle kernel pointer dereference" 270 " in virtual kernel address space\n"); 271 else 272 printk(KERN_ALERT "Unable to handle kernel paging request" 273 " in virtual user address space\n"); 274 dump_fault_info(regs); 275 die(regs, "Oops"); 276 } 277 278 static noinline void do_low_address(struct pt_regs *regs) 279 { 280 /* Low-address protection hit in kernel mode means 281 NULL pointer write access in kernel mode. */ 282 if (regs->psw.mask & PSW_MASK_PSTATE) { 283 /* Low-address protection hit in user mode 'cannot happen'. */ 284 die (regs, "Low-address protection"); 285 } 286 287 do_no_context(regs, VM_FAULT_BADACCESS); 288 } 289 290 static noinline void do_sigbus(struct pt_regs *regs) 291 { 292 /* 293 * Send a sigbus, regardless of whether we were in kernel 294 * or user mode. 295 */ 296 force_sig_fault(SIGBUS, BUS_ADRERR, 297 (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK)); 298 } 299 300 static noinline void do_fault_error(struct pt_regs *regs, vm_fault_t fault) 301 { 302 int si_code; 303 304 switch (fault) { 305 case VM_FAULT_BADACCESS: 306 case VM_FAULT_BADMAP: 307 /* Bad memory access. Check if it is kernel or user space. */ 308 if (user_mode(regs)) { 309 /* User mode accesses just cause a SIGSEGV */ 310 si_code = (fault == VM_FAULT_BADMAP) ? 311 SEGV_MAPERR : SEGV_ACCERR; 312 do_sigsegv(regs, si_code); 313 break; 314 } 315 fallthrough; 316 case VM_FAULT_BADCONTEXT: 317 case VM_FAULT_PFAULT: 318 do_no_context(regs, fault); 319 break; 320 case VM_FAULT_SIGNAL: 321 if (!user_mode(regs)) 322 do_no_context(regs, fault); 323 break; 324 default: /* fault & VM_FAULT_ERROR */ 325 if (fault & VM_FAULT_OOM) { 326 if (!user_mode(regs)) 327 do_no_context(regs, fault); 328 else 329 pagefault_out_of_memory(); 330 } else if (fault & VM_FAULT_SIGSEGV) { 331 /* Kernel mode? Handle exceptions or die */ 332 if (!user_mode(regs)) 333 do_no_context(regs, fault); 334 else 335 do_sigsegv(regs, SEGV_MAPERR); 336 } else if (fault & VM_FAULT_SIGBUS) { 337 /* Kernel mode? Handle exceptions or die */ 338 if (!user_mode(regs)) 339 do_no_context(regs, fault); 340 else 341 do_sigbus(regs); 342 } else 343 BUG(); 344 break; 345 } 346 } 347 348 /* 349 * This routine handles page faults. It determines the address, 350 * and the problem, and then passes it off to one of the appropriate 351 * routines. 352 * 353 * interruption code (int_code): 354 * 04 Protection -> Write-Protection (suppression) 355 * 10 Segment translation -> Not present (nullification) 356 * 11 Page translation -> Not present (nullification) 357 * 3b Region third trans. -> Not present (nullification) 358 */ 359 static inline vm_fault_t do_exception(struct pt_regs *regs, int access) 360 { 361 struct gmap *gmap; 362 struct task_struct *tsk; 363 struct mm_struct *mm; 364 struct vm_area_struct *vma; 365 enum fault_type type; 366 unsigned long address; 367 unsigned int flags; 368 vm_fault_t fault; 369 bool is_write; 370 371 tsk = current; 372 /* 373 * The instruction that caused the program check has 374 * been nullified. Don't signal single step via SIGTRAP. 375 */ 376 clear_thread_flag(TIF_PER_TRAP); 377 378 if (kprobe_page_fault(regs, 14)) 379 return 0; 380 381 mm = tsk->mm; 382 address = get_fault_address(regs); 383 is_write = fault_is_write(regs); 384 385 /* 386 * Verify that the fault happened in user space, that 387 * we are not in an interrupt and that there is a 388 * user context. 389 */ 390 fault = VM_FAULT_BADCONTEXT; 391 type = get_fault_type(regs); 392 switch (type) { 393 case KERNEL_FAULT: 394 goto out; 395 case USER_FAULT: 396 case GMAP_FAULT: 397 if (faulthandler_disabled() || !mm) 398 goto out; 399 break; 400 } 401 402 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 403 flags = FAULT_FLAG_DEFAULT; 404 if (user_mode(regs)) 405 flags |= FAULT_FLAG_USER; 406 if (is_write) 407 access = VM_WRITE; 408 if (access == VM_WRITE) 409 flags |= FAULT_FLAG_WRITE; 410 mmap_read_lock(mm); 411 412 gmap = NULL; 413 if (IS_ENABLED(CONFIG_PGSTE) && type == GMAP_FAULT) { 414 gmap = (struct gmap *) S390_lowcore.gmap; 415 current->thread.gmap_addr = address; 416 current->thread.gmap_write_flag = !!(flags & FAULT_FLAG_WRITE); 417 current->thread.gmap_int_code = regs->int_code & 0xffff; 418 address = __gmap_translate(gmap, address); 419 if (address == -EFAULT) { 420 fault = VM_FAULT_BADMAP; 421 goto out_up; 422 } 423 if (gmap->pfault_enabled) 424 flags |= FAULT_FLAG_RETRY_NOWAIT; 425 } 426 427 retry: 428 fault = VM_FAULT_BADMAP; 429 vma = find_vma(mm, address); 430 if (!vma) 431 goto out_up; 432 433 if (unlikely(vma->vm_start > address)) { 434 if (!(vma->vm_flags & VM_GROWSDOWN)) 435 goto out_up; 436 if (expand_stack(vma, address)) 437 goto out_up; 438 } 439 440 /* 441 * Ok, we have a good vm_area for this memory access, so 442 * we can handle it.. 443 */ 444 fault = VM_FAULT_BADACCESS; 445 if (unlikely(!(vma->vm_flags & access))) 446 goto out_up; 447 448 /* 449 * If for any reason at all we couldn't handle the fault, 450 * make sure we exit gracefully rather than endlessly redo 451 * the fault. 452 */ 453 fault = handle_mm_fault(vma, address, flags, regs); 454 if (fault_signal_pending(fault, regs)) { 455 fault = VM_FAULT_SIGNAL; 456 if (flags & FAULT_FLAG_RETRY_NOWAIT) 457 goto out_up; 458 goto out; 459 } 460 461 /* The fault is fully completed (including releasing mmap lock) */ 462 if (fault & VM_FAULT_COMPLETED) { 463 if (gmap) { 464 mmap_read_lock(mm); 465 goto out_gmap; 466 } 467 fault = 0; 468 goto out; 469 } 470 471 if (unlikely(fault & VM_FAULT_ERROR)) 472 goto out_up; 473 474 if (fault & VM_FAULT_RETRY) { 475 if (IS_ENABLED(CONFIG_PGSTE) && gmap && 476 (flags & FAULT_FLAG_RETRY_NOWAIT)) { 477 /* 478 * FAULT_FLAG_RETRY_NOWAIT has been set, mmap_lock has 479 * not been released 480 */ 481 current->thread.gmap_pfault = 1; 482 fault = VM_FAULT_PFAULT; 483 goto out_up; 484 } 485 flags &= ~FAULT_FLAG_RETRY_NOWAIT; 486 flags |= FAULT_FLAG_TRIED; 487 mmap_read_lock(mm); 488 goto retry; 489 } 490 out_gmap: 491 if (IS_ENABLED(CONFIG_PGSTE) && gmap) { 492 address = __gmap_link(gmap, current->thread.gmap_addr, 493 address); 494 if (address == -EFAULT) { 495 fault = VM_FAULT_BADMAP; 496 goto out_up; 497 } 498 if (address == -ENOMEM) { 499 fault = VM_FAULT_OOM; 500 goto out_up; 501 } 502 } 503 fault = 0; 504 out_up: 505 mmap_read_unlock(mm); 506 out: 507 return fault; 508 } 509 510 void do_protection_exception(struct pt_regs *regs) 511 { 512 unsigned long trans_exc_code; 513 int access; 514 vm_fault_t fault; 515 516 trans_exc_code = regs->int_parm_long; 517 /* 518 * Protection exceptions are suppressing, decrement psw address. 519 * The exception to this rule are aborted transactions, for these 520 * the PSW already points to the correct location. 521 */ 522 if (!(regs->int_code & 0x200)) 523 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16); 524 /* 525 * Check for low-address protection. This needs to be treated 526 * as a special case because the translation exception code 527 * field is not guaranteed to contain valid data in this case. 528 */ 529 if (unlikely(!(trans_exc_code & 4))) { 530 do_low_address(regs); 531 return; 532 } 533 if (unlikely(MACHINE_HAS_NX && (trans_exc_code & 0x80))) { 534 regs->int_parm_long = (trans_exc_code & ~PAGE_MASK) | 535 (regs->psw.addr & PAGE_MASK); 536 access = VM_EXEC; 537 fault = VM_FAULT_BADACCESS; 538 } else { 539 access = VM_WRITE; 540 fault = do_exception(regs, access); 541 } 542 if (unlikely(fault)) 543 do_fault_error(regs, fault); 544 } 545 NOKPROBE_SYMBOL(do_protection_exception); 546 547 void do_dat_exception(struct pt_regs *regs) 548 { 549 int access; 550 vm_fault_t fault; 551 552 access = VM_ACCESS_FLAGS; 553 fault = do_exception(regs, access); 554 if (unlikely(fault)) 555 do_fault_error(regs, fault); 556 } 557 NOKPROBE_SYMBOL(do_dat_exception); 558 559 #ifdef CONFIG_PFAULT 560 /* 561 * 'pfault' pseudo page faults routines. 562 */ 563 static int pfault_disable; 564 565 static int __init nopfault(char *str) 566 { 567 pfault_disable = 1; 568 return 1; 569 } 570 571 __setup("nopfault", nopfault); 572 573 struct pfault_refbk { 574 u16 refdiagc; 575 u16 reffcode; 576 u16 refdwlen; 577 u16 refversn; 578 u64 refgaddr; 579 u64 refselmk; 580 u64 refcmpmk; 581 u64 reserved; 582 } __attribute__ ((packed, aligned(8))); 583 584 static struct pfault_refbk pfault_init_refbk = { 585 .refdiagc = 0x258, 586 .reffcode = 0, 587 .refdwlen = 5, 588 .refversn = 2, 589 .refgaddr = __LC_LPP, 590 .refselmk = 1ULL << 48, 591 .refcmpmk = 1ULL << 48, 592 .reserved = __PF_RES_FIELD 593 }; 594 595 int pfault_init(void) 596 { 597 int rc; 598 599 if (pfault_disable) 600 return -1; 601 diag_stat_inc(DIAG_STAT_X258); 602 asm volatile( 603 " diag %1,%0,0x258\n" 604 "0: j 2f\n" 605 "1: la %0,8\n" 606 "2:\n" 607 EX_TABLE(0b,1b) 608 : "=d" (rc) 609 : "a" (&pfault_init_refbk), "m" (pfault_init_refbk) : "cc"); 610 return rc; 611 } 612 613 static struct pfault_refbk pfault_fini_refbk = { 614 .refdiagc = 0x258, 615 .reffcode = 1, 616 .refdwlen = 5, 617 .refversn = 2, 618 }; 619 620 void pfault_fini(void) 621 { 622 623 if (pfault_disable) 624 return; 625 diag_stat_inc(DIAG_STAT_X258); 626 asm volatile( 627 " diag %0,0,0x258\n" 628 "0: nopr %%r7\n" 629 EX_TABLE(0b,0b) 630 : : "a" (&pfault_fini_refbk), "m" (pfault_fini_refbk) : "cc"); 631 } 632 633 static DEFINE_SPINLOCK(pfault_lock); 634 static LIST_HEAD(pfault_list); 635 636 #define PF_COMPLETE 0x0080 637 638 /* 639 * The mechanism of our pfault code: if Linux is running as guest, runs a user 640 * space process and the user space process accesses a page that the host has 641 * paged out we get a pfault interrupt. 642 * 643 * This allows us, within the guest, to schedule a different process. Without 644 * this mechanism the host would have to suspend the whole virtual cpu until 645 * the page has been paged in. 646 * 647 * So when we get such an interrupt then we set the state of the current task 648 * to uninterruptible and also set the need_resched flag. Both happens within 649 * interrupt context(!). If we later on want to return to user space we 650 * recognize the need_resched flag and then call schedule(). It's not very 651 * obvious how this works... 652 * 653 * Of course we have a lot of additional fun with the completion interrupt (-> 654 * host signals that a page of a process has been paged in and the process can 655 * continue to run). This interrupt can arrive on any cpu and, since we have 656 * virtual cpus, actually appear before the interrupt that signals that a page 657 * is missing. 658 */ 659 static void pfault_interrupt(struct ext_code ext_code, 660 unsigned int param32, unsigned long param64) 661 { 662 struct task_struct *tsk; 663 __u16 subcode; 664 pid_t pid; 665 666 /* 667 * Get the external interruption subcode & pfault initial/completion 668 * signal bit. VM stores this in the 'cpu address' field associated 669 * with the external interrupt. 670 */ 671 subcode = ext_code.subcode; 672 if ((subcode & 0xff00) != __SUBCODE_MASK) 673 return; 674 inc_irq_stat(IRQEXT_PFL); 675 /* Get the token (= pid of the affected task). */ 676 pid = param64 & LPP_PID_MASK; 677 rcu_read_lock(); 678 tsk = find_task_by_pid_ns(pid, &init_pid_ns); 679 if (tsk) 680 get_task_struct(tsk); 681 rcu_read_unlock(); 682 if (!tsk) 683 return; 684 spin_lock(&pfault_lock); 685 if (subcode & PF_COMPLETE) { 686 /* signal bit is set -> a page has been swapped in by VM */ 687 if (tsk->thread.pfault_wait == 1) { 688 /* Initial interrupt was faster than the completion 689 * interrupt. pfault_wait is valid. Set pfault_wait 690 * back to zero and wake up the process. This can 691 * safely be done because the task is still sleeping 692 * and can't produce new pfaults. */ 693 tsk->thread.pfault_wait = 0; 694 list_del(&tsk->thread.list); 695 wake_up_process(tsk); 696 put_task_struct(tsk); 697 } else { 698 /* Completion interrupt was faster than initial 699 * interrupt. Set pfault_wait to -1 so the initial 700 * interrupt doesn't put the task to sleep. 701 * If the task is not running, ignore the completion 702 * interrupt since it must be a leftover of a PFAULT 703 * CANCEL operation which didn't remove all pending 704 * completion interrupts. */ 705 if (task_is_running(tsk)) 706 tsk->thread.pfault_wait = -1; 707 } 708 } else { 709 /* signal bit not set -> a real page is missing. */ 710 if (WARN_ON_ONCE(tsk != current)) 711 goto out; 712 if (tsk->thread.pfault_wait == 1) { 713 /* Already on the list with a reference: put to sleep */ 714 goto block; 715 } else if (tsk->thread.pfault_wait == -1) { 716 /* Completion interrupt was faster than the initial 717 * interrupt (pfault_wait == -1). Set pfault_wait 718 * back to zero and exit. */ 719 tsk->thread.pfault_wait = 0; 720 } else { 721 /* Initial interrupt arrived before completion 722 * interrupt. Let the task sleep. 723 * An extra task reference is needed since a different 724 * cpu may set the task state to TASK_RUNNING again 725 * before the scheduler is reached. */ 726 get_task_struct(tsk); 727 tsk->thread.pfault_wait = 1; 728 list_add(&tsk->thread.list, &pfault_list); 729 block: 730 /* Since this must be a userspace fault, there 731 * is no kernel task state to trample. Rely on the 732 * return to userspace schedule() to block. */ 733 __set_current_state(TASK_UNINTERRUPTIBLE); 734 set_tsk_need_resched(tsk); 735 set_preempt_need_resched(); 736 } 737 } 738 out: 739 spin_unlock(&pfault_lock); 740 put_task_struct(tsk); 741 } 742 743 static int pfault_cpu_dead(unsigned int cpu) 744 { 745 struct thread_struct *thread, *next; 746 struct task_struct *tsk; 747 748 spin_lock_irq(&pfault_lock); 749 list_for_each_entry_safe(thread, next, &pfault_list, list) { 750 thread->pfault_wait = 0; 751 list_del(&thread->list); 752 tsk = container_of(thread, struct task_struct, thread); 753 wake_up_process(tsk); 754 put_task_struct(tsk); 755 } 756 spin_unlock_irq(&pfault_lock); 757 return 0; 758 } 759 760 static int __init pfault_irq_init(void) 761 { 762 int rc; 763 764 rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); 765 if (rc) 766 goto out_extint; 767 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP; 768 if (rc) 769 goto out_pfault; 770 irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL); 771 cpuhp_setup_state_nocalls(CPUHP_S390_PFAULT_DEAD, "s390/pfault:dead", 772 NULL, pfault_cpu_dead); 773 return 0; 774 775 out_pfault: 776 unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); 777 out_extint: 778 pfault_disable = 1; 779 return rc; 780 } 781 early_initcall(pfault_irq_init); 782 783 #endif /* CONFIG_PFAULT */ 784 785 #if IS_ENABLED(CONFIG_PGSTE) 786 787 void do_secure_storage_access(struct pt_regs *regs) 788 { 789 unsigned long addr = regs->int_parm_long & __FAIL_ADDR_MASK; 790 struct vm_area_struct *vma; 791 struct mm_struct *mm; 792 struct page *page; 793 struct gmap *gmap; 794 int rc; 795 796 /* 797 * bit 61 tells us if the address is valid, if it's not we 798 * have a major problem and should stop the kernel or send a 799 * SIGSEGV to the process. Unfortunately bit 61 is not 800 * reliable without the misc UV feature so we need to check 801 * for that as well. 802 */ 803 if (test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications) && 804 !test_bit_inv(61, ®s->int_parm_long)) { 805 /* 806 * When this happens, userspace did something that it 807 * was not supposed to do, e.g. branching into secure 808 * memory. Trigger a segmentation fault. 809 */ 810 if (user_mode(regs)) { 811 send_sig(SIGSEGV, current, 0); 812 return; 813 } 814 815 /* 816 * The kernel should never run into this case and we 817 * have no way out of this situation. 818 */ 819 panic("Unexpected PGM 0x3d with TEID bit 61=0"); 820 } 821 822 switch (get_fault_type(regs)) { 823 case GMAP_FAULT: 824 mm = current->mm; 825 gmap = (struct gmap *)S390_lowcore.gmap; 826 mmap_read_lock(mm); 827 addr = __gmap_translate(gmap, addr); 828 mmap_read_unlock(mm); 829 if (IS_ERR_VALUE(addr)) { 830 do_fault_error(regs, VM_FAULT_BADMAP); 831 break; 832 } 833 fallthrough; 834 case USER_FAULT: 835 mm = current->mm; 836 mmap_read_lock(mm); 837 vma = find_vma(mm, addr); 838 if (!vma) { 839 mmap_read_unlock(mm); 840 do_fault_error(regs, VM_FAULT_BADMAP); 841 break; 842 } 843 page = follow_page(vma, addr, FOLL_WRITE | FOLL_GET); 844 if (IS_ERR_OR_NULL(page)) { 845 mmap_read_unlock(mm); 846 break; 847 } 848 if (arch_make_page_accessible(page)) 849 send_sig(SIGSEGV, current, 0); 850 put_page(page); 851 mmap_read_unlock(mm); 852 break; 853 case KERNEL_FAULT: 854 page = phys_to_page(addr); 855 if (unlikely(!try_get_page(page))) 856 break; 857 rc = arch_make_page_accessible(page); 858 put_page(page); 859 if (rc) 860 BUG(); 861 break; 862 default: 863 do_fault_error(regs, VM_FAULT_BADMAP); 864 WARN_ON_ONCE(1); 865 } 866 } 867 NOKPROBE_SYMBOL(do_secure_storage_access); 868 869 void do_non_secure_storage_access(struct pt_regs *regs) 870 { 871 unsigned long gaddr = regs->int_parm_long & __FAIL_ADDR_MASK; 872 struct gmap *gmap = (struct gmap *)S390_lowcore.gmap; 873 874 if (get_fault_type(regs) != GMAP_FAULT) { 875 do_fault_error(regs, VM_FAULT_BADMAP); 876 WARN_ON_ONCE(1); 877 return; 878 } 879 880 if (gmap_convert_to_secure(gmap, gaddr) == -EINVAL) 881 send_sig(SIGSEGV, current, 0); 882 } 883 NOKPROBE_SYMBOL(do_non_secure_storage_access); 884 885 void do_secure_storage_violation(struct pt_regs *regs) 886 { 887 unsigned long gaddr = regs->int_parm_long & __FAIL_ADDR_MASK; 888 struct gmap *gmap = (struct gmap *)S390_lowcore.gmap; 889 890 /* 891 * If the VM has been rebooted, its address space might still contain 892 * secure pages from the previous boot. 893 * Clear the page so it can be reused. 894 */ 895 if (!gmap_destroy_page(gmap, gaddr)) 896 return; 897 /* 898 * Either KVM messed up the secure guest mapping or the same 899 * page is mapped into multiple secure guests. 900 * 901 * This exception is only triggered when a guest 2 is running 902 * and can therefore never occur in kernel context. 903 */ 904 printk_ratelimited(KERN_WARNING 905 "Secure storage violation in task: %s, pid %d\n", 906 current->comm, current->pid); 907 send_sig(SIGSEGV, current, 0); 908 } 909 910 #endif /* CONFIG_PGSTE */ 911