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-offsets.h> 36 #include <asm/diag.h> 37 #include <asm/gmap.h> 38 #include <asm/irq.h> 39 #include <asm/mmu_context.h> 40 #include <asm/facility.h> 41 #include <asm/uv.h> 42 #include "../kernel/entry.h" 43 44 #define __FAIL_ADDR_MASK -4096L 45 #define __SUBCODE_MASK 0x0600 46 #define __PF_RES_FIELD 0x8000000000000000ULL 47 48 #define VM_FAULT_BADCONTEXT ((__force vm_fault_t) 0x010000) 49 #define VM_FAULT_BADMAP ((__force vm_fault_t) 0x020000) 50 #define VM_FAULT_BADACCESS ((__force vm_fault_t) 0x040000) 51 #define VM_FAULT_SIGNAL ((__force vm_fault_t) 0x080000) 52 #define VM_FAULT_PFAULT ((__force vm_fault_t) 0x100000) 53 54 enum fault_type { 55 KERNEL_FAULT, 56 USER_FAULT, 57 GMAP_FAULT, 58 }; 59 60 static unsigned long store_indication __read_mostly; 61 62 static int __init fault_init(void) 63 { 64 if (test_facility(75)) 65 store_indication = 0xc00; 66 return 0; 67 } 68 early_initcall(fault_init); 69 70 /* 71 * Find out which address space caused the exception. 72 */ 73 static enum fault_type get_fault_type(struct pt_regs *regs) 74 { 75 unsigned long trans_exc_code; 76 77 trans_exc_code = regs->int_parm_long & 3; 78 if (likely(trans_exc_code == 0)) { 79 /* primary space exception */ 80 if (user_mode(regs)) 81 return USER_FAULT; 82 if (!IS_ENABLED(CONFIG_PGSTE)) 83 return KERNEL_FAULT; 84 if (test_pt_regs_flag(regs, PIF_GUEST_FAULT)) 85 return GMAP_FAULT; 86 return KERNEL_FAULT; 87 } 88 if (trans_exc_code == 2) 89 return USER_FAULT; 90 if (trans_exc_code == 1) { 91 /* access register mode, not used in the kernel */ 92 return USER_FAULT; 93 } 94 /* home space exception -> access via kernel ASCE */ 95 return KERNEL_FAULT; 96 } 97 98 static int bad_address(void *p) 99 { 100 unsigned long dummy; 101 102 return get_kernel_nofault(dummy, (unsigned long *)p); 103 } 104 105 static void dump_pagetable(unsigned long asce, unsigned long address) 106 { 107 unsigned long *table = __va(asce & _ASCE_ORIGIN); 108 109 pr_alert("AS:%016lx ", asce); 110 switch (asce & _ASCE_TYPE_MASK) { 111 case _ASCE_TYPE_REGION1: 112 table += (address & _REGION1_INDEX) >> _REGION1_SHIFT; 113 if (bad_address(table)) 114 goto bad; 115 pr_cont("R1:%016lx ", *table); 116 if (*table & _REGION_ENTRY_INVALID) 117 goto out; 118 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); 119 fallthrough; 120 case _ASCE_TYPE_REGION2: 121 table += (address & _REGION2_INDEX) >> _REGION2_SHIFT; 122 if (bad_address(table)) 123 goto bad; 124 pr_cont("R2:%016lx ", *table); 125 if (*table & _REGION_ENTRY_INVALID) 126 goto out; 127 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); 128 fallthrough; 129 case _ASCE_TYPE_REGION3: 130 table += (address & _REGION3_INDEX) >> _REGION3_SHIFT; 131 if (bad_address(table)) 132 goto bad; 133 pr_cont("R3:%016lx ", *table); 134 if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE)) 135 goto out; 136 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); 137 fallthrough; 138 case _ASCE_TYPE_SEGMENT: 139 table += (address & _SEGMENT_INDEX) >> _SEGMENT_SHIFT; 140 if (bad_address(table)) 141 goto bad; 142 pr_cont("S:%016lx ", *table); 143 if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE)) 144 goto out; 145 table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN); 146 } 147 table += (address & _PAGE_INDEX) >> _PAGE_SHIFT; 148 if (bad_address(table)) 149 goto bad; 150 pr_cont("P:%016lx ", *table); 151 out: 152 pr_cont("\n"); 153 return; 154 bad: 155 pr_cont("BAD\n"); 156 } 157 158 static void dump_fault_info(struct pt_regs *regs) 159 { 160 unsigned long asce; 161 162 pr_alert("Failing address: %016lx TEID: %016lx\n", 163 regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long); 164 pr_alert("Fault in "); 165 switch (regs->int_parm_long & 3) { 166 case 3: 167 pr_cont("home space "); 168 break; 169 case 2: 170 pr_cont("secondary space "); 171 break; 172 case 1: 173 pr_cont("access register "); 174 break; 175 case 0: 176 pr_cont("primary space "); 177 break; 178 } 179 pr_cont("mode while using "); 180 switch (get_fault_type(regs)) { 181 case USER_FAULT: 182 asce = S390_lowcore.user_asce; 183 pr_cont("user "); 184 break; 185 case GMAP_FAULT: 186 asce = ((struct gmap *) S390_lowcore.gmap)->asce; 187 pr_cont("gmap "); 188 break; 189 case KERNEL_FAULT: 190 asce = S390_lowcore.kernel_asce; 191 pr_cont("kernel "); 192 break; 193 default: 194 unreachable(); 195 } 196 pr_cont("ASCE.\n"); 197 dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK); 198 } 199 200 int show_unhandled_signals = 1; 201 202 void report_user_fault(struct pt_regs *regs, long signr, int is_mm_fault) 203 { 204 if ((task_pid_nr(current) > 1) && !show_unhandled_signals) 205 return; 206 if (!unhandled_signal(current, signr)) 207 return; 208 if (!printk_ratelimit()) 209 return; 210 printk(KERN_ALERT "User process fault: interruption code %04x ilc:%d ", 211 regs->int_code & 0xffff, regs->int_code >> 17); 212 print_vma_addr(KERN_CONT "in ", regs->psw.addr); 213 printk(KERN_CONT "\n"); 214 if (is_mm_fault) 215 dump_fault_info(regs); 216 show_regs(regs); 217 } 218 219 /* 220 * Send SIGSEGV to task. This is an external routine 221 * to keep the stack usage of do_page_fault small. 222 */ 223 static noinline void do_sigsegv(struct pt_regs *regs, int si_code) 224 { 225 report_user_fault(regs, SIGSEGV, 1); 226 force_sig_fault(SIGSEGV, si_code, 227 (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK)); 228 } 229 230 const struct exception_table_entry *s390_search_extables(unsigned long addr) 231 { 232 const struct exception_table_entry *fixup; 233 234 fixup = search_extable(__start_amode31_ex_table, 235 __stop_amode31_ex_table - __start_amode31_ex_table, 236 addr); 237 if (!fixup) 238 fixup = search_exception_tables(addr); 239 return fixup; 240 } 241 242 static noinline void do_no_context(struct pt_regs *regs) 243 { 244 const struct exception_table_entry *fixup; 245 246 /* Are we prepared to handle this kernel fault? */ 247 fixup = s390_search_extables(regs->psw.addr); 248 if (fixup && ex_handle(fixup, regs)) 249 return; 250 251 /* 252 * Oops. The kernel tried to access some bad page. We'll have to 253 * terminate things with extreme prejudice. 254 */ 255 if (get_fault_type(regs) == KERNEL_FAULT) 256 printk(KERN_ALERT "Unable to handle kernel pointer dereference" 257 " in virtual kernel address space\n"); 258 else 259 printk(KERN_ALERT "Unable to handle kernel paging request" 260 " in virtual user address space\n"); 261 dump_fault_info(regs); 262 die(regs, "Oops"); 263 } 264 265 static noinline void do_low_address(struct pt_regs *regs) 266 { 267 /* Low-address protection hit in kernel mode means 268 NULL pointer write access in kernel mode. */ 269 if (regs->psw.mask & PSW_MASK_PSTATE) { 270 /* Low-address protection hit in user mode 'cannot happen'. */ 271 die (regs, "Low-address protection"); 272 } 273 274 do_no_context(regs); 275 } 276 277 static noinline void do_sigbus(struct pt_regs *regs) 278 { 279 /* 280 * Send a sigbus, regardless of whether we were in kernel 281 * or user mode. 282 */ 283 force_sig_fault(SIGBUS, BUS_ADRERR, 284 (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK)); 285 } 286 287 static noinline void do_fault_error(struct pt_regs *regs, int access, 288 vm_fault_t fault) 289 { 290 int si_code; 291 292 switch (fault) { 293 case VM_FAULT_BADACCESS: 294 case VM_FAULT_BADMAP: 295 /* Bad memory access. Check if it is kernel or user space. */ 296 if (user_mode(regs)) { 297 /* User mode accesses just cause a SIGSEGV */ 298 si_code = (fault == VM_FAULT_BADMAP) ? 299 SEGV_MAPERR : SEGV_ACCERR; 300 do_sigsegv(regs, si_code); 301 break; 302 } 303 fallthrough; 304 case VM_FAULT_BADCONTEXT: 305 case VM_FAULT_PFAULT: 306 do_no_context(regs); 307 break; 308 case VM_FAULT_SIGNAL: 309 if (!user_mode(regs)) 310 do_no_context(regs); 311 break; 312 default: /* fault & VM_FAULT_ERROR */ 313 if (fault & VM_FAULT_OOM) { 314 if (!user_mode(regs)) 315 do_no_context(regs); 316 else 317 pagefault_out_of_memory(); 318 } else if (fault & VM_FAULT_SIGSEGV) { 319 /* Kernel mode? Handle exceptions or die */ 320 if (!user_mode(regs)) 321 do_no_context(regs); 322 else 323 do_sigsegv(regs, SEGV_MAPERR); 324 } else if (fault & VM_FAULT_SIGBUS) { 325 /* Kernel mode? Handle exceptions or die */ 326 if (!user_mode(regs)) 327 do_no_context(regs); 328 else 329 do_sigbus(regs); 330 } else 331 BUG(); 332 break; 333 } 334 } 335 336 /* 337 * This routine handles page faults. It determines the address, 338 * and the problem, and then passes it off to one of the appropriate 339 * routines. 340 * 341 * interruption code (int_code): 342 * 04 Protection -> Write-Protection (suppression) 343 * 10 Segment translation -> Not present (nullification) 344 * 11 Page translation -> Not present (nullification) 345 * 3b Region third trans. -> Not present (nullification) 346 */ 347 static inline vm_fault_t do_exception(struct pt_regs *regs, int access) 348 { 349 struct gmap *gmap; 350 struct task_struct *tsk; 351 struct mm_struct *mm; 352 struct vm_area_struct *vma; 353 enum fault_type type; 354 unsigned long trans_exc_code; 355 unsigned long address; 356 unsigned int flags; 357 vm_fault_t fault; 358 bool is_write; 359 360 tsk = current; 361 /* 362 * The instruction that caused the program check has 363 * been nullified. Don't signal single step via SIGTRAP. 364 */ 365 clear_thread_flag(TIF_PER_TRAP); 366 367 if (kprobe_page_fault(regs, 14)) 368 return 0; 369 370 mm = tsk->mm; 371 trans_exc_code = regs->int_parm_long; 372 address = trans_exc_code & __FAIL_ADDR_MASK; 373 is_write = (trans_exc_code & store_indication) == 0x400; 374 375 /* 376 * Verify that the fault happened in user space, that 377 * we are not in an interrupt and that there is a 378 * user context. 379 */ 380 fault = VM_FAULT_BADCONTEXT; 381 type = get_fault_type(regs); 382 switch (type) { 383 case KERNEL_FAULT: 384 if (kfence_handle_page_fault(address, is_write, regs)) 385 return 0; 386 goto out; 387 case USER_FAULT: 388 case GMAP_FAULT: 389 if (faulthandler_disabled() || !mm) 390 goto out; 391 break; 392 } 393 394 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 395 flags = FAULT_FLAG_DEFAULT; 396 if (user_mode(regs)) 397 flags |= FAULT_FLAG_USER; 398 if (access == VM_WRITE || is_write) 399 flags |= FAULT_FLAG_WRITE; 400 mmap_read_lock(mm); 401 402 gmap = NULL; 403 if (IS_ENABLED(CONFIG_PGSTE) && type == GMAP_FAULT) { 404 gmap = (struct gmap *) S390_lowcore.gmap; 405 current->thread.gmap_addr = address; 406 current->thread.gmap_write_flag = !!(flags & FAULT_FLAG_WRITE); 407 current->thread.gmap_int_code = regs->int_code & 0xffff; 408 address = __gmap_translate(gmap, address); 409 if (address == -EFAULT) { 410 fault = VM_FAULT_BADMAP; 411 goto out_up; 412 } 413 if (gmap->pfault_enabled) 414 flags |= FAULT_FLAG_RETRY_NOWAIT; 415 } 416 417 retry: 418 fault = VM_FAULT_BADMAP; 419 vma = find_vma(mm, address); 420 if (!vma) 421 goto out_up; 422 423 if (unlikely(vma->vm_start > address)) { 424 if (!(vma->vm_flags & VM_GROWSDOWN)) 425 goto out_up; 426 if (expand_stack(vma, address)) 427 goto out_up; 428 } 429 430 /* 431 * Ok, we have a good vm_area for this memory access, so 432 * we can handle it.. 433 */ 434 fault = VM_FAULT_BADACCESS; 435 if (unlikely(!(vma->vm_flags & access))) 436 goto out_up; 437 438 if (is_vm_hugetlb_page(vma)) 439 address &= HPAGE_MASK; 440 /* 441 * If for any reason at all we couldn't handle the fault, 442 * make sure we exit gracefully rather than endlessly redo 443 * the fault. 444 */ 445 fault = handle_mm_fault(vma, address, flags, regs); 446 if (fault_signal_pending(fault, regs)) { 447 fault = VM_FAULT_SIGNAL; 448 if (flags & FAULT_FLAG_RETRY_NOWAIT) 449 goto out_up; 450 goto out; 451 } 452 if (unlikely(fault & VM_FAULT_ERROR)) 453 goto out_up; 454 455 if (flags & FAULT_FLAG_ALLOW_RETRY) { 456 if (fault & VM_FAULT_RETRY) { 457 if (IS_ENABLED(CONFIG_PGSTE) && gmap && 458 (flags & FAULT_FLAG_RETRY_NOWAIT)) { 459 /* FAULT_FLAG_RETRY_NOWAIT has been set, 460 * mmap_lock has not been released */ 461 current->thread.gmap_pfault = 1; 462 fault = VM_FAULT_PFAULT; 463 goto out_up; 464 } 465 flags &= ~FAULT_FLAG_RETRY_NOWAIT; 466 flags |= FAULT_FLAG_TRIED; 467 mmap_read_lock(mm); 468 goto retry; 469 } 470 } 471 if (IS_ENABLED(CONFIG_PGSTE) && gmap) { 472 address = __gmap_link(gmap, current->thread.gmap_addr, 473 address); 474 if (address == -EFAULT) { 475 fault = VM_FAULT_BADMAP; 476 goto out_up; 477 } 478 if (address == -ENOMEM) { 479 fault = VM_FAULT_OOM; 480 goto out_up; 481 } 482 } 483 fault = 0; 484 out_up: 485 mmap_read_unlock(mm); 486 out: 487 return fault; 488 } 489 490 void do_protection_exception(struct pt_regs *regs) 491 { 492 unsigned long trans_exc_code; 493 int access; 494 vm_fault_t fault; 495 496 trans_exc_code = regs->int_parm_long; 497 /* 498 * Protection exceptions are suppressing, decrement psw address. 499 * The exception to this rule are aborted transactions, for these 500 * the PSW already points to the correct location. 501 */ 502 if (!(regs->int_code & 0x200)) 503 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16); 504 /* 505 * Check for low-address protection. This needs to be treated 506 * as a special case because the translation exception code 507 * field is not guaranteed to contain valid data in this case. 508 */ 509 if (unlikely(!(trans_exc_code & 4))) { 510 do_low_address(regs); 511 return; 512 } 513 if (unlikely(MACHINE_HAS_NX && (trans_exc_code & 0x80))) { 514 regs->int_parm_long = (trans_exc_code & ~PAGE_MASK) | 515 (regs->psw.addr & PAGE_MASK); 516 access = VM_EXEC; 517 fault = VM_FAULT_BADACCESS; 518 } else { 519 access = VM_WRITE; 520 fault = do_exception(regs, access); 521 } 522 if (unlikely(fault)) 523 do_fault_error(regs, access, fault); 524 } 525 NOKPROBE_SYMBOL(do_protection_exception); 526 527 void do_dat_exception(struct pt_regs *regs) 528 { 529 int access; 530 vm_fault_t fault; 531 532 access = VM_ACCESS_FLAGS; 533 fault = do_exception(regs, access); 534 if (unlikely(fault)) 535 do_fault_error(regs, access, fault); 536 } 537 NOKPROBE_SYMBOL(do_dat_exception); 538 539 #ifdef CONFIG_PFAULT 540 /* 541 * 'pfault' pseudo page faults routines. 542 */ 543 static int pfault_disable; 544 545 static int __init nopfault(char *str) 546 { 547 pfault_disable = 1; 548 return 1; 549 } 550 551 __setup("nopfault", nopfault); 552 553 struct pfault_refbk { 554 u16 refdiagc; 555 u16 reffcode; 556 u16 refdwlen; 557 u16 refversn; 558 u64 refgaddr; 559 u64 refselmk; 560 u64 refcmpmk; 561 u64 reserved; 562 } __attribute__ ((packed, aligned(8))); 563 564 static struct pfault_refbk pfault_init_refbk = { 565 .refdiagc = 0x258, 566 .reffcode = 0, 567 .refdwlen = 5, 568 .refversn = 2, 569 .refgaddr = __LC_LPP, 570 .refselmk = 1ULL << 48, 571 .refcmpmk = 1ULL << 48, 572 .reserved = __PF_RES_FIELD 573 }; 574 575 int pfault_init(void) 576 { 577 int rc; 578 579 if (pfault_disable) 580 return -1; 581 diag_stat_inc(DIAG_STAT_X258); 582 asm volatile( 583 " diag %1,%0,0x258\n" 584 "0: j 2f\n" 585 "1: la %0,8\n" 586 "2:\n" 587 EX_TABLE(0b,1b) 588 : "=d" (rc) 589 : "a" (&pfault_init_refbk), "m" (pfault_init_refbk) : "cc"); 590 return rc; 591 } 592 593 static struct pfault_refbk pfault_fini_refbk = { 594 .refdiagc = 0x258, 595 .reffcode = 1, 596 .refdwlen = 5, 597 .refversn = 2, 598 }; 599 600 void pfault_fini(void) 601 { 602 603 if (pfault_disable) 604 return; 605 diag_stat_inc(DIAG_STAT_X258); 606 asm volatile( 607 " diag %0,0,0x258\n" 608 "0: nopr %%r7\n" 609 EX_TABLE(0b,0b) 610 : : "a" (&pfault_fini_refbk), "m" (pfault_fini_refbk) : "cc"); 611 } 612 613 static DEFINE_SPINLOCK(pfault_lock); 614 static LIST_HEAD(pfault_list); 615 616 #define PF_COMPLETE 0x0080 617 618 /* 619 * The mechanism of our pfault code: if Linux is running as guest, runs a user 620 * space process and the user space process accesses a page that the host has 621 * paged out we get a pfault interrupt. 622 * 623 * This allows us, within the guest, to schedule a different process. Without 624 * this mechanism the host would have to suspend the whole virtual cpu until 625 * the page has been paged in. 626 * 627 * So when we get such an interrupt then we set the state of the current task 628 * to uninterruptible and also set the need_resched flag. Both happens within 629 * interrupt context(!). If we later on want to return to user space we 630 * recognize the need_resched flag and then call schedule(). It's not very 631 * obvious how this works... 632 * 633 * Of course we have a lot of additional fun with the completion interrupt (-> 634 * host signals that a page of a process has been paged in and the process can 635 * continue to run). This interrupt can arrive on any cpu and, since we have 636 * virtual cpus, actually appear before the interrupt that signals that a page 637 * is missing. 638 */ 639 static void pfault_interrupt(struct ext_code ext_code, 640 unsigned int param32, unsigned long param64) 641 { 642 struct task_struct *tsk; 643 __u16 subcode; 644 pid_t pid; 645 646 /* 647 * Get the external interruption subcode & pfault initial/completion 648 * signal bit. VM stores this in the 'cpu address' field associated 649 * with the external interrupt. 650 */ 651 subcode = ext_code.subcode; 652 if ((subcode & 0xff00) != __SUBCODE_MASK) 653 return; 654 inc_irq_stat(IRQEXT_PFL); 655 /* Get the token (= pid of the affected task). */ 656 pid = param64 & LPP_PID_MASK; 657 rcu_read_lock(); 658 tsk = find_task_by_pid_ns(pid, &init_pid_ns); 659 if (tsk) 660 get_task_struct(tsk); 661 rcu_read_unlock(); 662 if (!tsk) 663 return; 664 spin_lock(&pfault_lock); 665 if (subcode & PF_COMPLETE) { 666 /* signal bit is set -> a page has been swapped in by VM */ 667 if (tsk->thread.pfault_wait == 1) { 668 /* Initial interrupt was faster than the completion 669 * interrupt. pfault_wait is valid. Set pfault_wait 670 * back to zero and wake up the process. This can 671 * safely be done because the task is still sleeping 672 * and can't produce new pfaults. */ 673 tsk->thread.pfault_wait = 0; 674 list_del(&tsk->thread.list); 675 wake_up_process(tsk); 676 put_task_struct(tsk); 677 } else { 678 /* Completion interrupt was faster than initial 679 * interrupt. Set pfault_wait to -1 so the initial 680 * interrupt doesn't put the task to sleep. 681 * If the task is not running, ignore the completion 682 * interrupt since it must be a leftover of a PFAULT 683 * CANCEL operation which didn't remove all pending 684 * completion interrupts. */ 685 if (task_is_running(tsk)) 686 tsk->thread.pfault_wait = -1; 687 } 688 } else { 689 /* signal bit not set -> a real page is missing. */ 690 if (WARN_ON_ONCE(tsk != current)) 691 goto out; 692 if (tsk->thread.pfault_wait == 1) { 693 /* Already on the list with a reference: put to sleep */ 694 goto block; 695 } else if (tsk->thread.pfault_wait == -1) { 696 /* Completion interrupt was faster than the initial 697 * interrupt (pfault_wait == -1). Set pfault_wait 698 * back to zero and exit. */ 699 tsk->thread.pfault_wait = 0; 700 } else { 701 /* Initial interrupt arrived before completion 702 * interrupt. Let the task sleep. 703 * An extra task reference is needed since a different 704 * cpu may set the task state to TASK_RUNNING again 705 * before the scheduler is reached. */ 706 get_task_struct(tsk); 707 tsk->thread.pfault_wait = 1; 708 list_add(&tsk->thread.list, &pfault_list); 709 block: 710 /* Since this must be a userspace fault, there 711 * is no kernel task state to trample. Rely on the 712 * return to userspace schedule() to block. */ 713 __set_current_state(TASK_UNINTERRUPTIBLE); 714 set_tsk_need_resched(tsk); 715 set_preempt_need_resched(); 716 } 717 } 718 out: 719 spin_unlock(&pfault_lock); 720 put_task_struct(tsk); 721 } 722 723 static int pfault_cpu_dead(unsigned int cpu) 724 { 725 struct thread_struct *thread, *next; 726 struct task_struct *tsk; 727 728 spin_lock_irq(&pfault_lock); 729 list_for_each_entry_safe(thread, next, &pfault_list, list) { 730 thread->pfault_wait = 0; 731 list_del(&thread->list); 732 tsk = container_of(thread, struct task_struct, thread); 733 wake_up_process(tsk); 734 put_task_struct(tsk); 735 } 736 spin_unlock_irq(&pfault_lock); 737 return 0; 738 } 739 740 static int __init pfault_irq_init(void) 741 { 742 int rc; 743 744 rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); 745 if (rc) 746 goto out_extint; 747 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP; 748 if (rc) 749 goto out_pfault; 750 irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL); 751 cpuhp_setup_state_nocalls(CPUHP_S390_PFAULT_DEAD, "s390/pfault:dead", 752 NULL, pfault_cpu_dead); 753 return 0; 754 755 out_pfault: 756 unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); 757 out_extint: 758 pfault_disable = 1; 759 return rc; 760 } 761 early_initcall(pfault_irq_init); 762 763 #endif /* CONFIG_PFAULT */ 764 765 #if IS_ENABLED(CONFIG_PGSTE) 766 767 void do_secure_storage_access(struct pt_regs *regs) 768 { 769 unsigned long addr = regs->int_parm_long & __FAIL_ADDR_MASK; 770 struct vm_area_struct *vma; 771 struct mm_struct *mm; 772 struct page *page; 773 int rc; 774 775 /* 776 * bit 61 tells us if the address is valid, if it's not we 777 * have a major problem and should stop the kernel or send a 778 * SIGSEGV to the process. Unfortunately bit 61 is not 779 * reliable without the misc UV feature so we need to check 780 * for that as well. 781 */ 782 if (test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications) && 783 !test_bit_inv(61, ®s->int_parm_long)) { 784 /* 785 * When this happens, userspace did something that it 786 * was not supposed to do, e.g. branching into secure 787 * memory. Trigger a segmentation fault. 788 */ 789 if (user_mode(regs)) { 790 send_sig(SIGSEGV, current, 0); 791 return; 792 } 793 794 /* 795 * The kernel should never run into this case and we 796 * have no way out of this situation. 797 */ 798 panic("Unexpected PGM 0x3d with TEID bit 61=0"); 799 } 800 801 switch (get_fault_type(regs)) { 802 case USER_FAULT: 803 mm = current->mm; 804 mmap_read_lock(mm); 805 vma = find_vma(mm, addr); 806 if (!vma) { 807 mmap_read_unlock(mm); 808 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP); 809 break; 810 } 811 page = follow_page(vma, addr, FOLL_WRITE | FOLL_GET); 812 if (IS_ERR_OR_NULL(page)) { 813 mmap_read_unlock(mm); 814 break; 815 } 816 if (arch_make_page_accessible(page)) 817 send_sig(SIGSEGV, current, 0); 818 put_page(page); 819 mmap_read_unlock(mm); 820 break; 821 case KERNEL_FAULT: 822 page = phys_to_page(addr); 823 if (unlikely(!try_get_page(page))) 824 break; 825 rc = arch_make_page_accessible(page); 826 put_page(page); 827 if (rc) 828 BUG(); 829 break; 830 case GMAP_FAULT: 831 default: 832 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP); 833 WARN_ON_ONCE(1); 834 } 835 } 836 NOKPROBE_SYMBOL(do_secure_storage_access); 837 838 void do_non_secure_storage_access(struct pt_regs *regs) 839 { 840 unsigned long gaddr = regs->int_parm_long & __FAIL_ADDR_MASK; 841 struct gmap *gmap = (struct gmap *)S390_lowcore.gmap; 842 843 if (get_fault_type(regs) != GMAP_FAULT) { 844 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP); 845 WARN_ON_ONCE(1); 846 return; 847 } 848 849 if (gmap_convert_to_secure(gmap, gaddr) == -EINVAL) 850 send_sig(SIGSEGV, current, 0); 851 } 852 NOKPROBE_SYMBOL(do_non_secure_storage_access); 853 854 void do_secure_storage_violation(struct pt_regs *regs) 855 { 856 /* 857 * Either KVM messed up the secure guest mapping or the same 858 * page is mapped into multiple secure guests. 859 * 860 * This exception is only triggered when a guest 2 is running 861 * and can therefore never occur in kernel context. 862 */ 863 printk_ratelimited(KERN_WARNING 864 "Secure storage violation in task: %s, pid %d\n", 865 current->comm, current->pid); 866 send_sig(SIGSEGV, current, 0); 867 } 868 869 #endif /* CONFIG_PGSTE */ 870