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 <asm/asm-offsets.h> 35#include <asm/diag.h> 36#include <asm/gmap.h> 37#include <asm/irq.h> 38#include <asm/mmu_context.h> 39#include <asm/facility.h> 40#include <asm/uv.h> 41#include "../kernel/entry.h" 42 43#define __FAIL_ADDR_MASK -4096L 44#define __SUBCODE_MASK 0x0600 45#define __PF_RES_FIELD 0x8000000000000000ULL 46 47#define VM_FAULT_BADCONTEXT ((__force vm_fault_t) 0x010000) 48#define VM_FAULT_BADMAP ((__force vm_fault_t) 0x020000) 49#define VM_FAULT_BADACCESS ((__force vm_fault_t) 0x040000) 50#define VM_FAULT_SIGNAL ((__force vm_fault_t) 0x080000) 51#define VM_FAULT_PFAULT ((__force vm_fault_t) 0x100000) 52 53enum fault_type { 54 KERNEL_FAULT, 55 USER_FAULT, 56 VDSO_FAULT, 57 GMAP_FAULT, 58}; 59 60static unsigned long store_indication __read_mostly; 61 62static int __init fault_init(void) 63{ 64 if (test_facility(75)) 65 store_indication = 0xc00; 66 return 0; 67} 68early_initcall(fault_init); 69 70/* 71 * Find out which address space caused the exception. 72 */ 73static 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 (IS_ENABLED(CONFIG_PGSTE) && 81 test_pt_regs_flag(regs, PIF_GUEST_FAULT)) 82 return GMAP_FAULT; 83 if (current->thread.mm_segment == USER_DS) 84 return USER_FAULT; 85 return KERNEL_FAULT; 86 } 87 if (trans_exc_code == 2) { 88 /* secondary space exception */ 89 if (current->thread.mm_segment & 1) { 90 if (current->thread.mm_segment == USER_DS_SACF) 91 return USER_FAULT; 92 return KERNEL_FAULT; 93 } 94 return VDSO_FAULT; 95 } 96 if (trans_exc_code == 1) { 97 /* access register mode, not used in the kernel */ 98 return USER_FAULT; 99 } 100 /* home space exception -> access via kernel ASCE */ 101 return KERNEL_FAULT; 102} 103 104static int bad_address(void *p) 105{ 106 unsigned long dummy; 107 108 return get_kernel_nofault(dummy, (unsigned long *)p); 109} 110 111static void dump_pagetable(unsigned long asce, unsigned long address) 112{ 113 unsigned long *table = __va(asce & _ASCE_ORIGIN); 114 115 pr_alert("AS:%016lx ", asce); 116 switch (asce & _ASCE_TYPE_MASK) { 117 case _ASCE_TYPE_REGION1: 118 table += (address & _REGION1_INDEX) >> _REGION1_SHIFT; 119 if (bad_address(table)) 120 goto bad; 121 pr_cont("R1:%016lx ", *table); 122 if (*table & _REGION_ENTRY_INVALID) 123 goto out; 124 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); 125 fallthrough; 126 case _ASCE_TYPE_REGION2: 127 table += (address & _REGION2_INDEX) >> _REGION2_SHIFT; 128 if (bad_address(table)) 129 goto bad; 130 pr_cont("R2:%016lx ", *table); 131 if (*table & _REGION_ENTRY_INVALID) 132 goto out; 133 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); 134 fallthrough; 135 case _ASCE_TYPE_REGION3: 136 table += (address & _REGION3_INDEX) >> _REGION3_SHIFT; 137 if (bad_address(table)) 138 goto bad; 139 pr_cont("R3:%016lx ", *table); 140 if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE)) 141 goto out; 142 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN); 143 fallthrough; 144 case _ASCE_TYPE_SEGMENT: 145 table += (address & _SEGMENT_INDEX) >> _SEGMENT_SHIFT; 146 if (bad_address(table)) 147 goto bad; 148 pr_cont("S:%016lx ", *table); 149 if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE)) 150 goto out; 151 table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN); 152 } 153 table += (address & _PAGE_INDEX) >> _PAGE_SHIFT; 154 if (bad_address(table)) 155 goto bad; 156 pr_cont("P:%016lx ", *table); 157out: 158 pr_cont("\n"); 159 return; 160bad: 161 pr_cont("BAD\n"); 162} 163 164static void dump_fault_info(struct pt_regs *regs) 165{ 166 unsigned long asce; 167 168 pr_alert("Failing address: %016lx TEID: %016lx\n", 169 regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long); 170 pr_alert("Fault in "); 171 switch (regs->int_parm_long & 3) { 172 case 3: 173 pr_cont("home space "); 174 break; 175 case 2: 176 pr_cont("secondary space "); 177 break; 178 case 1: 179 pr_cont("access register "); 180 break; 181 case 0: 182 pr_cont("primary space "); 183 break; 184 } 185 pr_cont("mode while using "); 186 switch (get_fault_type(regs)) { 187 case USER_FAULT: 188 asce = S390_lowcore.user_asce; 189 pr_cont("user "); 190 break; 191 case VDSO_FAULT: 192 asce = S390_lowcore.vdso_asce; 193 pr_cont("vdso "); 194 break; 195 case GMAP_FAULT: 196 asce = ((struct gmap *) S390_lowcore.gmap)->asce; 197 pr_cont("gmap "); 198 break; 199 case KERNEL_FAULT: 200 asce = S390_lowcore.kernel_asce; 201 pr_cont("kernel "); 202 break; 203 default: 204 unreachable(); 205 } 206 pr_cont("ASCE.\n"); 207 dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK); 208} 209 210int show_unhandled_signals = 1; 211 212void report_user_fault(struct pt_regs *regs, long signr, int is_mm_fault) 213{ 214 if ((task_pid_nr(current) > 1) && !show_unhandled_signals) 215 return; 216 if (!unhandled_signal(current, signr)) 217 return; 218 if (!printk_ratelimit()) 219 return; 220 printk(KERN_ALERT "User process fault: interruption code %04x ilc:%d ", 221 regs->int_code & 0xffff, regs->int_code >> 17); 222 print_vma_addr(KERN_CONT "in ", regs->psw.addr); 223 printk(KERN_CONT "\n"); 224 if (is_mm_fault) 225 dump_fault_info(regs); 226 show_regs(regs); 227} 228 229/* 230 * Send SIGSEGV to task. This is an external routine 231 * to keep the stack usage of do_page_fault small. 232 */ 233static noinline void do_sigsegv(struct pt_regs *regs, int si_code) 234{ 235 report_user_fault(regs, SIGSEGV, 1); 236 force_sig_fault(SIGSEGV, si_code, 237 (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK)); 238} 239 240const struct exception_table_entry *s390_search_extables(unsigned long addr) 241{ 242 const struct exception_table_entry *fixup; 243 244 fixup = search_extable(__start_dma_ex_table, 245 __stop_dma_ex_table - __start_dma_ex_table, 246 addr); 247 if (!fixup) 248 fixup = search_exception_tables(addr); 249 return fixup; 250} 251 252static noinline void do_no_context(struct pt_regs *regs) 253{ 254 const struct exception_table_entry *fixup; 255 256 /* Are we prepared to handle this kernel fault? */ 257 fixup = s390_search_extables(regs->psw.addr); 258 if (fixup && ex_handle(fixup, regs)) 259 return; 260 261 /* 262 * Oops. The kernel tried to access some bad page. We'll have to 263 * terminate things with extreme prejudice. 264 */ 265 if (get_fault_type(regs) == KERNEL_FAULT) 266 printk(KERN_ALERT "Unable to handle kernel pointer dereference" 267 " in virtual kernel address space\n"); 268 else 269 printk(KERN_ALERT "Unable to handle kernel paging request" 270 " in virtual user address space\n"); 271 dump_fault_info(regs); 272 die(regs, "Oops"); 273 do_exit(SIGKILL); 274} 275 276static noinline void do_low_address(struct pt_regs *regs) 277{ 278 /* Low-address protection hit in kernel mode means 279 NULL pointer write access in kernel mode. */ 280 if (regs->psw.mask & PSW_MASK_PSTATE) { 281 /* Low-address protection hit in user mode 'cannot happen'. */ 282 die (regs, "Low-address protection"); 283 do_exit(SIGKILL); 284 } 285 286 do_no_context(regs); 287} 288 289static noinline void do_sigbus(struct pt_regs *regs) 290{ 291 /* 292 * Send a sigbus, regardless of whether we were in kernel 293 * or user mode. 294 */ 295 force_sig_fault(SIGBUS, BUS_ADRERR, 296 (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK)); 297} 298 299static noinline int signal_return(struct pt_regs *regs) 300{ 301 u16 instruction; 302 int rc; 303 304 rc = __get_user(instruction, (u16 __user *) regs->psw.addr); 305 if (rc) 306 return rc; 307 if (instruction == 0x0a77) { 308 set_pt_regs_flag(regs, PIF_SYSCALL); 309 regs->int_code = 0x00040077; 310 return 0; 311 } else if (instruction == 0x0aad) { 312 set_pt_regs_flag(regs, PIF_SYSCALL); 313 regs->int_code = 0x000400ad; 314 return 0; 315 } 316 return -EACCES; 317} 318 319static noinline void do_fault_error(struct pt_regs *regs, int access, 320 vm_fault_t fault) 321{ 322 int si_code; 323 324 switch (fault) { 325 case VM_FAULT_BADACCESS: 326 if (access == VM_EXEC && signal_return(regs) == 0) 327 break; 328 fallthrough; 329 case VM_FAULT_BADMAP: 330 /* Bad memory access. Check if it is kernel or user space. */ 331 if (user_mode(regs)) { 332 /* User mode accesses just cause a SIGSEGV */ 333 si_code = (fault == VM_FAULT_BADMAP) ? 334 SEGV_MAPERR : SEGV_ACCERR; 335 do_sigsegv(regs, si_code); 336 break; 337 } 338 fallthrough; 339 case VM_FAULT_BADCONTEXT: 340 case VM_FAULT_PFAULT: 341 do_no_context(regs); 342 break; 343 case VM_FAULT_SIGNAL: 344 if (!user_mode(regs)) 345 do_no_context(regs); 346 break; 347 default: /* fault & VM_FAULT_ERROR */ 348 if (fault & VM_FAULT_OOM) { 349 if (!user_mode(regs)) 350 do_no_context(regs); 351 else 352 pagefault_out_of_memory(); 353 } else if (fault & VM_FAULT_SIGSEGV) { 354 /* Kernel mode? Handle exceptions or die */ 355 if (!user_mode(regs)) 356 do_no_context(regs); 357 else 358 do_sigsegv(regs, SEGV_MAPERR); 359 } else if (fault & VM_FAULT_SIGBUS) { 360 /* Kernel mode? Handle exceptions or die */ 361 if (!user_mode(regs)) 362 do_no_context(regs); 363 else 364 do_sigbus(regs); 365 } else 366 BUG(); 367 break; 368 } 369} 370 371/* 372 * This routine handles page faults. It determines the address, 373 * and the problem, and then passes it off to one of the appropriate 374 * routines. 375 * 376 * interruption code (int_code): 377 * 04 Protection -> Write-Protection (suppression) 378 * 10 Segment translation -> Not present (nullification) 379 * 11 Page translation -> Not present (nullification) 380 * 3b Region third trans. -> Not present (nullification) 381 */ 382static inline vm_fault_t do_exception(struct pt_regs *regs, int access) 383{ 384 struct gmap *gmap; 385 struct task_struct *tsk; 386 struct mm_struct *mm; 387 struct vm_area_struct *vma; 388 enum fault_type type; 389 unsigned long trans_exc_code; 390 unsigned long address; 391 unsigned int flags; 392 vm_fault_t fault; 393 394 tsk = current; 395 /* 396 * The instruction that caused the program check has 397 * been nullified. Don't signal single step via SIGTRAP. 398 */ 399 clear_pt_regs_flag(regs, PIF_PER_TRAP); 400 401 if (kprobe_page_fault(regs, 14)) 402 return 0; 403 404 mm = tsk->mm; 405 trans_exc_code = regs->int_parm_long; 406 407 /* 408 * Verify that the fault happened in user space, that 409 * we are not in an interrupt and that there is a 410 * user context. 411 */ 412 fault = VM_FAULT_BADCONTEXT; 413 type = get_fault_type(regs); 414 switch (type) { 415 case KERNEL_FAULT: 416 goto out; 417 case VDSO_FAULT: 418 fault = VM_FAULT_BADMAP; 419 goto out; 420 case USER_FAULT: 421 case GMAP_FAULT: 422 if (faulthandler_disabled() || !mm) 423 goto out; 424 break; 425 } 426 427 address = trans_exc_code & __FAIL_ADDR_MASK; 428 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 429 flags = FAULT_FLAG_DEFAULT; 430 if (user_mode(regs)) 431 flags |= FAULT_FLAG_USER; 432 if ((trans_exc_code & store_indication) == 0x400) 433 access = VM_WRITE; 434 if (access == VM_WRITE) 435 flags |= FAULT_FLAG_WRITE; 436 mmap_read_lock(mm); 437 438 gmap = NULL; 439 if (IS_ENABLED(CONFIG_PGSTE) && type == GMAP_FAULT) { 440 gmap = (struct gmap *) S390_lowcore.gmap; 441 current->thread.gmap_addr = address; 442 current->thread.gmap_write_flag = !!(flags & FAULT_FLAG_WRITE); 443 current->thread.gmap_int_code = regs->int_code & 0xffff; 444 address = __gmap_translate(gmap, address); 445 if (address == -EFAULT) { 446 fault = VM_FAULT_BADMAP; 447 goto out_up; 448 } 449 if (gmap->pfault_enabled) 450 flags |= FAULT_FLAG_RETRY_NOWAIT; 451 } 452 453retry: 454 fault = VM_FAULT_BADMAP; 455 vma = find_vma(mm, address); 456 if (!vma) 457 goto out_up; 458 459 if (unlikely(vma->vm_start > address)) { 460 if (!(vma->vm_flags & VM_GROWSDOWN)) 461 goto out_up; 462 if (expand_stack(vma, address)) 463 goto out_up; 464 } 465 466 /* 467 * Ok, we have a good vm_area for this memory access, so 468 * we can handle it.. 469 */ 470 fault = VM_FAULT_BADACCESS; 471 if (unlikely(!(vma->vm_flags & access))) 472 goto out_up; 473 474 if (is_vm_hugetlb_page(vma)) 475 address &= HPAGE_MASK; 476 /* 477 * If for any reason at all we couldn't handle the fault, 478 * make sure we exit gracefully rather than endlessly redo 479 * the fault. 480 */ 481 fault = handle_mm_fault(vma, address, flags, regs); 482 if (fault_signal_pending(fault, regs)) { 483 fault = VM_FAULT_SIGNAL; 484 if (flags & FAULT_FLAG_RETRY_NOWAIT) 485 goto out_up; 486 goto out; 487 } 488 if (unlikely(fault & VM_FAULT_ERROR)) 489 goto out_up; 490 491 if (flags & FAULT_FLAG_ALLOW_RETRY) { 492 if (fault & VM_FAULT_RETRY) { 493 if (IS_ENABLED(CONFIG_PGSTE) && gmap && 494 (flags & FAULT_FLAG_RETRY_NOWAIT)) { 495 /* FAULT_FLAG_RETRY_NOWAIT has been set, 496 * mmap_lock has not been released */ 497 current->thread.gmap_pfault = 1; 498 fault = VM_FAULT_PFAULT; 499 goto out_up; 500 } 501 flags &= ~FAULT_FLAG_RETRY_NOWAIT; 502 flags |= FAULT_FLAG_TRIED; 503 mmap_read_lock(mm); 504 goto retry; 505 } 506 } 507 if (IS_ENABLED(CONFIG_PGSTE) && gmap) { 508 address = __gmap_link(gmap, current->thread.gmap_addr, 509 address); 510 if (address == -EFAULT) { 511 fault = VM_FAULT_BADMAP; 512 goto out_up; 513 } 514 if (address == -ENOMEM) { 515 fault = VM_FAULT_OOM; 516 goto out_up; 517 } 518 } 519 fault = 0; 520out_up: 521 mmap_read_unlock(mm); 522out: 523 return fault; 524} 525 526void do_protection_exception(struct pt_regs *regs) 527{ 528 unsigned long trans_exc_code; 529 int access; 530 vm_fault_t fault; 531 532 trans_exc_code = regs->int_parm_long; 533 /* 534 * Protection exceptions are suppressing, decrement psw address. 535 * The exception to this rule are aborted transactions, for these 536 * the PSW already points to the correct location. 537 */ 538 if (!(regs->int_code & 0x200)) 539 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16); 540 /* 541 * Check for low-address protection. This needs to be treated 542 * as a special case because the translation exception code 543 * field is not guaranteed to contain valid data in this case. 544 */ 545 if (unlikely(!(trans_exc_code & 4))) { 546 do_low_address(regs); 547 return; 548 } 549 if (unlikely(MACHINE_HAS_NX && (trans_exc_code & 0x80))) { 550 regs->int_parm_long = (trans_exc_code & ~PAGE_MASK) | 551 (regs->psw.addr & PAGE_MASK); 552 access = VM_EXEC; 553 fault = VM_FAULT_BADACCESS; 554 } else { 555 access = VM_WRITE; 556 fault = do_exception(regs, access); 557 } 558 if (unlikely(fault)) 559 do_fault_error(regs, access, fault); 560} 561NOKPROBE_SYMBOL(do_protection_exception); 562 563void do_dat_exception(struct pt_regs *regs) 564{ 565 int access; 566 vm_fault_t fault; 567 568 access = VM_ACCESS_FLAGS; 569 fault = do_exception(regs, access); 570 if (unlikely(fault)) 571 do_fault_error(regs, access, fault); 572} 573NOKPROBE_SYMBOL(do_dat_exception); 574 575#ifdef CONFIG_PFAULT 576/* 577 * 'pfault' pseudo page faults routines. 578 */ 579static int pfault_disable; 580 581static int __init nopfault(char *str) 582{ 583 pfault_disable = 1; 584 return 1; 585} 586 587__setup("nopfault", nopfault); 588 589struct pfault_refbk { 590 u16 refdiagc; 591 u16 reffcode; 592 u16 refdwlen; 593 u16 refversn; 594 u64 refgaddr; 595 u64 refselmk; 596 u64 refcmpmk; 597 u64 reserved; 598} __attribute__ ((packed, aligned(8))); 599 600static struct pfault_refbk pfault_init_refbk = { 601 .refdiagc = 0x258, 602 .reffcode = 0, 603 .refdwlen = 5, 604 .refversn = 2, 605 .refgaddr = __LC_LPP, 606 .refselmk = 1ULL << 48, 607 .refcmpmk = 1ULL << 48, 608 .reserved = __PF_RES_FIELD 609}; 610 611int pfault_init(void) 612{ 613 int rc; 614 615 if (pfault_disable) 616 return -1; 617 diag_stat_inc(DIAG_STAT_X258); 618 asm volatile( 619 " diag %1,%0,0x258\n" 620 "0: j 2f\n" 621 "1: la %0,8\n" 622 "2:\n" 623 EX_TABLE(0b,1b) 624 : "=d" (rc) 625 : "a" (&pfault_init_refbk), "m" (pfault_init_refbk) : "cc"); 626 return rc; 627} 628 629static struct pfault_refbk pfault_fini_refbk = { 630 .refdiagc = 0x258, 631 .reffcode = 1, 632 .refdwlen = 5, 633 .refversn = 2, 634}; 635 636void pfault_fini(void) 637{ 638 639 if (pfault_disable) 640 return; 641 diag_stat_inc(DIAG_STAT_X258); 642 asm volatile( 643 " diag %0,0,0x258\n" 644 "0: nopr %%r7\n" 645 EX_TABLE(0b,0b) 646 : : "a" (&pfault_fini_refbk), "m" (pfault_fini_refbk) : "cc"); 647} 648 649static DEFINE_SPINLOCK(pfault_lock); 650static LIST_HEAD(pfault_list); 651 652#define PF_COMPLETE 0x0080 653 654/* 655 * The mechanism of our pfault code: if Linux is running as guest, runs a user 656 * space process and the user space process accesses a page that the host has 657 * paged out we get a pfault interrupt. 658 * 659 * This allows us, within the guest, to schedule a different process. Without 660 * this mechanism the host would have to suspend the whole virtual cpu until 661 * the page has been paged in. 662 * 663 * So when we get such an interrupt then we set the state of the current task 664 * to uninterruptible and also set the need_resched flag. Both happens within 665 * interrupt context(!). If we later on want to return to user space we 666 * recognize the need_resched flag and then call schedule(). It's not very 667 * obvious how this works... 668 * 669 * Of course we have a lot of additional fun with the completion interrupt (-> 670 * host signals that a page of a process has been paged in and the process can 671 * continue to run). This interrupt can arrive on any cpu and, since we have 672 * virtual cpus, actually appear before the interrupt that signals that a page 673 * is missing. 674 */ 675static void pfault_interrupt(struct ext_code ext_code, 676 unsigned int param32, unsigned long param64) 677{ 678 struct task_struct *tsk; 679 __u16 subcode; 680 pid_t pid; 681 682 /* 683 * Get the external interruption subcode & pfault initial/completion 684 * signal bit. VM stores this in the 'cpu address' field associated 685 * with the external interrupt. 686 */ 687 subcode = ext_code.subcode; 688 if ((subcode & 0xff00) != __SUBCODE_MASK) 689 return; 690 inc_irq_stat(IRQEXT_PFL); 691 /* Get the token (= pid of the affected task). */ 692 pid = param64 & LPP_PID_MASK; 693 rcu_read_lock(); 694 tsk = find_task_by_pid_ns(pid, &init_pid_ns); 695 if (tsk) 696 get_task_struct(tsk); 697 rcu_read_unlock(); 698 if (!tsk) 699 return; 700 spin_lock(&pfault_lock); 701 if (subcode & PF_COMPLETE) { 702 /* signal bit is set -> a page has been swapped in by VM */ 703 if (tsk->thread.pfault_wait == 1) { 704 /* Initial interrupt was faster than the completion 705 * interrupt. pfault_wait is valid. Set pfault_wait 706 * back to zero and wake up the process. This can 707 * safely be done because the task is still sleeping 708 * and can't produce new pfaults. */ 709 tsk->thread.pfault_wait = 0; 710 list_del(&tsk->thread.list); 711 wake_up_process(tsk); 712 put_task_struct(tsk); 713 } else { 714 /* Completion interrupt was faster than initial 715 * interrupt. Set pfault_wait to -1 so the initial 716 * interrupt doesn't put the task to sleep. 717 * If the task is not running, ignore the completion 718 * interrupt since it must be a leftover of a PFAULT 719 * CANCEL operation which didn't remove all pending 720 * completion interrupts. */ 721 if (tsk->state == TASK_RUNNING) 722 tsk->thread.pfault_wait = -1; 723 } 724 } else { 725 /* signal bit not set -> a real page is missing. */ 726 if (WARN_ON_ONCE(tsk != current)) 727 goto out; 728 if (tsk->thread.pfault_wait == 1) { 729 /* Already on the list with a reference: put to sleep */ 730 goto block; 731 } else if (tsk->thread.pfault_wait == -1) { 732 /* Completion interrupt was faster than the initial 733 * interrupt (pfault_wait == -1). Set pfault_wait 734 * back to zero and exit. */ 735 tsk->thread.pfault_wait = 0; 736 } else { 737 /* Initial interrupt arrived before completion 738 * interrupt. Let the task sleep. 739 * An extra task reference is needed since a different 740 * cpu may set the task state to TASK_RUNNING again 741 * before the scheduler is reached. */ 742 get_task_struct(tsk); 743 tsk->thread.pfault_wait = 1; 744 list_add(&tsk->thread.list, &pfault_list); 745block: 746 /* Since this must be a userspace fault, there 747 * is no kernel task state to trample. Rely on the 748 * return to userspace schedule() to block. */ 749 __set_current_state(TASK_UNINTERRUPTIBLE); 750 set_tsk_need_resched(tsk); 751 set_preempt_need_resched(); 752 } 753 } 754out: 755 spin_unlock(&pfault_lock); 756 put_task_struct(tsk); 757} 758 759static int pfault_cpu_dead(unsigned int cpu) 760{ 761 struct thread_struct *thread, *next; 762 struct task_struct *tsk; 763 764 spin_lock_irq(&pfault_lock); 765 list_for_each_entry_safe(thread, next, &pfault_list, list) { 766 thread->pfault_wait = 0; 767 list_del(&thread->list); 768 tsk = container_of(thread, struct task_struct, thread); 769 wake_up_process(tsk); 770 put_task_struct(tsk); 771 } 772 spin_unlock_irq(&pfault_lock); 773 return 0; 774} 775 776static int __init pfault_irq_init(void) 777{ 778 int rc; 779 780 rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); 781 if (rc) 782 goto out_extint; 783 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP; 784 if (rc) 785 goto out_pfault; 786 irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL); 787 cpuhp_setup_state_nocalls(CPUHP_S390_PFAULT_DEAD, "s390/pfault:dead", 788 NULL, pfault_cpu_dead); 789 return 0; 790 791out_pfault: 792 unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt); 793out_extint: 794 pfault_disable = 1; 795 return rc; 796} 797early_initcall(pfault_irq_init); 798 799#endif /* CONFIG_PFAULT */ 800 801#if IS_ENABLED(CONFIG_PGSTE) 802void do_secure_storage_access(struct pt_regs *regs) 803{ 804 unsigned long addr = regs->int_parm_long & __FAIL_ADDR_MASK; 805 struct vm_area_struct *vma; 806 struct mm_struct *mm; 807 struct page *page; 808 int rc; 809 810 /* 811 * bit 61 tells us if the address is valid, if it's not we 812 * have a major problem and should stop the kernel or send a 813 * SIGSEGV to the process. Unfortunately bit 61 is not 814 * reliable without the misc UV feature so we need to check 815 * for that as well. 816 */ 817 if (test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications) && 818 !test_bit_inv(61, ®s->int_parm_long)) { 819 /* 820 * When this happens, userspace did something that it 821 * was not supposed to do, e.g. branching into secure 822 * memory. Trigger a segmentation fault. 823 */ 824 if (user_mode(regs)) { 825 send_sig(SIGSEGV, current, 0); 826 return; 827 } 828 829 /* 830 * The kernel should never run into this case and we 831 * have no way out of this situation. 832 */ 833 panic("Unexpected PGM 0x3d with TEID bit 61=0"); 834 } 835 836 switch (get_fault_type(regs)) { 837 case USER_FAULT: 838 mm = current->mm; 839 mmap_read_lock(mm); 840 vma = find_vma(mm, addr); 841 if (!vma) { 842 mmap_read_unlock(mm); 843 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP); 844 break; 845 } 846 page = follow_page(vma, addr, FOLL_WRITE | FOLL_GET); 847 if (IS_ERR_OR_NULL(page)) { 848 mmap_read_unlock(mm); 849 break; 850 } 851 if (arch_make_page_accessible(page)) 852 send_sig(SIGSEGV, current, 0); 853 put_page(page); 854 mmap_read_unlock(mm); 855 break; 856 case KERNEL_FAULT: 857 page = phys_to_page(addr); 858 if (unlikely(!try_get_page(page))) 859 break; 860 rc = arch_make_page_accessible(page); 861 put_page(page); 862 if (rc) 863 BUG(); 864 break; 865 case VDSO_FAULT: 866 case GMAP_FAULT: 867 default: 868 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP); 869 WARN_ON_ONCE(1); 870 } 871} 872NOKPROBE_SYMBOL(do_secure_storage_access); 873 874void do_non_secure_storage_access(struct pt_regs *regs) 875{ 876 unsigned long gaddr = regs->int_parm_long & __FAIL_ADDR_MASK; 877 struct gmap *gmap = (struct gmap *)S390_lowcore.gmap; 878 879 if (get_fault_type(regs) != GMAP_FAULT) { 880 do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP); 881 WARN_ON_ONCE(1); 882 return; 883 } 884 885 if (gmap_convert_to_secure(gmap, gaddr) == -EINVAL) 886 send_sig(SIGSEGV, current, 0); 887} 888NOKPROBE_SYMBOL(do_non_secure_storage_access); 889 890void do_secure_storage_violation(struct pt_regs *regs) 891{ 892 /* 893 * Either KVM messed up the secure guest mapping or the same 894 * page is mapped into multiple secure guests. 895 * 896 * This exception is only triggered when a guest 2 is running 897 * and can therefore never occur in kernel context. 898 */ 899 printk_ratelimited(KERN_WARNING 900 "Secure storage violation in task: %s, pid %d\n", 901 current->comm, current->pid); 902 send_sig(SIGSEGV, current, 0); 903} 904 905#else 906void do_secure_storage_access(struct pt_regs *regs) 907{ 908 default_trap_handler(regs); 909} 910 911void do_non_secure_storage_access(struct pt_regs *regs) 912{ 913 default_trap_handler(regs); 914} 915 916void do_secure_storage_violation(struct pt_regs *regs) 917{ 918 default_trap_handler(regs); 919} 920#endif 921