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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 | /* * arch/s390/mm/fault.c * * S390 version * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation * Author(s): Hartmut Penner (hp@de.ibm.com) * Ulrich Weigand (uweigand@de.ibm.com) * * Derived from "arch/i386/mm/fault.c" * Copyright (C) 1995 Linus Torvalds */ #include <linux/config.h> #include <linux/signal.h> #include <linux/sched.h> #include <linux/kernel.h> #include <linux/errno.h> #include <linux/string.h> #include <linux/types.h> #include <linux/ptrace.h> #include <linux/mman.h> #include <linux/mm.h> #include <linux/smp.h> #include <linux/smp_lock.h> #include <linux/compatmac.h> #include <linux/init.h> #include <linux/console.h> #include <asm/system.h> #include <asm/uaccess.h> #include <asm/pgtable.h> #include <asm/hardirq.h> #ifdef CONFIG_SYSCTL extern int sysctl_userprocess_debug; #endif extern void die(const char *,struct pt_regs *,long); extern spinlock_t timerlist_lock; /* * Unlock any spinlocks which will prevent us from getting the * message out (timerlist_lock is acquired through the * console unblank code) */ void bust_spinlocks(int yes) { spin_lock_init(&timerlist_lock); if (yes) { oops_in_progress = 1; } else { int loglevel_save = console_loglevel; oops_in_progress = 0; console_unblank(); /* * OK, the message is on the console. Now we call printk() * without oops_in_progress set so that printk will give klogd * a poke. Hold onto your hats... */ console_loglevel = 15; printk(" "); console_loglevel = loglevel_save; } } /* * Check which address space is addressed by the access * register in S390_lowcore.exc_access_id. * Returns 1 for user space and 0 for kernel space. */ static int __check_access_register(struct pt_regs *regs, int error_code) { int areg = S390_lowcore.exc_access_id; if (areg == 0) /* Access via access register 0 -> kernel address */ return 0; if (regs && areg < NUM_ACRS && regs->acrs[areg] <= 1) /* * access register contains 0 -> kernel address, * access register contains 1 -> user space address */ return regs->acrs[areg]; /* Something unhealthy was done with the access registers... */ die("page fault via unknown access register", regs, error_code); do_exit(SIGKILL); return 0; } /* * Check which address space the address belongs to. * Returns 1 for user space and 0 for kernel space. */ static inline int check_user_space(struct pt_regs *regs, int error_code) { /* * The lowest two bits of S390_lowcore.trans_exc_code indicate * which paging table was used: * 0: Primary Segment Table Descriptor * 1: STD determined via access register * 2: Secondary Segment Table Descriptor * 3: Home Segment Table Descriptor */ int descriptor = S390_lowcore.trans_exc_code & 3; if (descriptor == 1) return __check_access_register(regs, error_code); return descriptor >> 1; } /* * Send SIGSEGV to task. This is an external routine * to keep the stack usage of do_page_fault small. */ static void force_sigsegv(struct pt_regs *regs, unsigned long error_code, int si_code, unsigned long address) { struct siginfo si; #if defined(CONFIG_SYSCTL) || defined(CONFIG_PROCESS_DEBUG) #if defined(CONFIG_SYSCTL) if (sysctl_userprocess_debug) #endif { printk("User process fault: interruption code 0x%lX\n", error_code); printk("failing address: %lX\n", address); show_regs(regs); } #endif si.si_signo = SIGSEGV; si.si_code = si_code; si.si_addr = (void *) address; force_sig_info(SIGSEGV, &si, current); } /* * This routine handles page faults. It determines the address, * and the problem, and then passes it off to one of the appropriate * routines. * * error_code: * 04 Protection -> Write-Protection (suprression) * 10 Segment translation -> Not present (nullification) * 11 Page translation -> Not present (nullification) */ extern inline void do_exception(struct pt_regs *regs, unsigned long error_code) { struct task_struct *tsk; struct mm_struct *mm; struct vm_area_struct * vma; unsigned long address; int user_address; unsigned long fixup; int si_code = SEGV_MAPERR; tsk = current; mm = tsk->mm; /* * Check for low-address protection. This needs to be treated * as a special case because the translation exception code * field is not guaranteed to contain valid data in this case. */ if (error_code == 4 && !(S390_lowcore.trans_exc_code & 4)) { /* Low-address protection hit in kernel mode means NULL pointer write access in kernel mode. */ if (!(regs->psw.mask & PSW_PROBLEM_STATE)) { address = 0; user_address = 0; goto no_context; } /* Low-address protection hit in user mode 'cannot happen'. */ die ("Low-address protection", regs, error_code); do_exit(SIGKILL); } /* * get the failing address * more specific the segment and page table portion of * the address */ address = S390_lowcore.trans_exc_code&0x7ffff000; user_address = check_user_space(regs, error_code); /* * Verify that the fault happened in user space, that * we are not in an interrupt and that there is a * user context. */ if (user_address == 0 || in_interrupt() || !mm) goto no_context; /* * When we get here, the fault happened in the current * task's user address space, so we can switch on the * interrupts again and then search the VMAs */ __sti(); down_read(&mm->mmap_sem); vma = find_vma(mm, address); if (!vma) goto bad_area; if (vma->vm_start <= address) goto good_area; if (!(vma->vm_flags & VM_GROWSDOWN)) goto bad_area; if (expand_stack(vma, address)) goto bad_area; /* * Ok, we have a good vm_area for this memory access, so * we can handle it.. */ good_area: si_code = SEGV_ACCERR; if (error_code != 4) { /* page not present, check vm flags */ if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) goto bad_area; } else { if (!(vma->vm_flags & VM_WRITE)) goto bad_area; } survive: /* * If for any reason at all we couldn't handle the fault, * make sure we exit gracefully rather than endlessly redo * the fault. */ switch (handle_mm_fault(mm, vma, address, error_code == 4)) { case 1: tsk->min_flt++; break; case 2: tsk->maj_flt++; break; case 0: goto do_sigbus; default: goto out_of_memory; } up_read(&mm->mmap_sem); return; /* * Something tried to access memory that isn't in our memory map.. * Fix it, but check if it's kernel or user first.. */ bad_area: up_read(&mm->mmap_sem); /* User mode accesses just cause a SIGSEGV */ if (regs->psw.mask & PSW_PROBLEM_STATE) { tsk->thread.prot_addr = address; tsk->thread.trap_no = error_code; force_sigsegv(regs, error_code, si_code, address); return; } no_context: /* Are we prepared to handle this kernel fault? */ if ((fixup = search_exception_table(regs->psw.addr)) != 0) { regs->psw.addr = fixup; return; } /* * Oops. The kernel tried to access some bad page. We'll have to * terminate things with extreme prejudice. */ if (user_address == 0) printk(KERN_ALERT "Unable to handle kernel pointer dereference" " at virtual kernel address %08lx\n", address); else printk(KERN_ALERT "Unable to handle kernel paging request" " at virtual user address %08lx\n", address); die("Oops", regs, error_code); do_exit(SIGKILL); /* * We ran out of memory, or some other thing happened to us that made * us unable to handle the page fault gracefully. */ out_of_memory: up_read(&mm->mmap_sem); if (tsk->pid == 1) { yield(); goto survive; } printk("VM: killing process %s\n", tsk->comm); if (regs->psw.mask & PSW_PROBLEM_STATE) do_exit(SIGKILL); goto no_context; do_sigbus: up_read(&mm->mmap_sem); /* * Send a sigbus, regardless of whether we were in kernel * or user mode. */ tsk->thread.prot_addr = address; tsk->thread.trap_no = error_code; force_sig(SIGBUS, tsk); /* Kernel mode? Handle exceptions or die */ if (!(regs->psw.mask & PSW_PROBLEM_STATE)) goto no_context; } void do_protection_exception(struct pt_regs *regs, unsigned long error_code) { regs->psw.addr -= (error_code >> 16); do_exception(regs, 4); } void do_segment_exception(struct pt_regs *regs, unsigned long error_code) { do_exception(regs, 0x10); } void do_page_exception(struct pt_regs *regs, unsigned long error_code) { do_exception(regs, 0x11); } typedef struct _pseudo_wait_t { struct _pseudo_wait_t *next; wait_queue_head_t queue; unsigned long address; int resolved; } pseudo_wait_t; static pseudo_wait_t *pseudo_lock_queue = NULL; static spinlock_t pseudo_wait_spinlock; /* spinlock to protect lock queue */ /* * This routine handles 'pagex' pseudo page faults. */ asmlinkage void do_pseudo_page_fault(struct pt_regs *regs, unsigned long error_code) { pseudo_wait_t wait_struct; pseudo_wait_t *ptr, *last, *next; unsigned long address; /* * get the failing address * more specific the segment and page table portion of * the address */ address = S390_lowcore.trans_exc_code & 0xfffff000; if (address & 0x80000000) { /* high bit set -> a page has been swapped in by VM */ address &= 0x7fffffff; spin_lock(&pseudo_wait_spinlock); last = NULL; ptr = pseudo_lock_queue; while (ptr != NULL) { next = ptr->next; if (address == ptr->address) { /* * This is one of the processes waiting * for the page. Unchain from the queue. * There can be more than one process * waiting for the same page. VM presents * an initial and a completion interrupt for * every process that tries to access a * page swapped out by VM. */ if (last == NULL) pseudo_lock_queue = next; else last->next = next; /* now wake up the process */ ptr->resolved = 1; wake_up(&ptr->queue); } else last = ptr; ptr = next; } spin_unlock(&pseudo_wait_spinlock); } else { /* Pseudo page faults in kernel mode is a bad idea */ if (!(regs->psw.mask & PSW_PROBLEM_STATE)) { /* * VM presents pseudo page faults if the interrupted * state was not disabled for interrupts. So we can * get pseudo page fault interrupts while running * in kernel mode. We simply access the page here * while we are running disabled. VM will then swap * in the page synchronously. */ if (check_user_space(regs, error_code) == 0) /* dereference a virtual kernel address */ __asm__ __volatile__ ( " ic 0,0(%0)" : : "a" (address) : "0"); else /* dereference a virtual user address */ __asm__ __volatile__ ( " la 2,0(%0)\n" " sacf 512\n" " ic 2,0(2)\n" "0:sacf 0\n" ".section __ex_table,\"a\"\n" " .align 4\n" " .long 0b,0b\n" ".previous" : : "a" (address) : "2" ); return; } /* initialize and add element to pseudo_lock_queue */ init_waitqueue_head (&wait_struct.queue); wait_struct.address = address; wait_struct.resolved = 0; spin_lock(&pseudo_wait_spinlock); wait_struct.next = pseudo_lock_queue; pseudo_lock_queue = &wait_struct; spin_unlock(&pseudo_wait_spinlock); /* go to sleep */ wait_event(wait_struct.queue, wait_struct.resolved); } } #ifdef CONFIG_PFAULT /* * 'pfault' pseudo page faults routines. */ static int pfault_disable = 0; static int __init nopfault(char *str) { pfault_disable = 1; return 1; } __setup("nopfault", nopfault); typedef struct { __u16 refdiagc; __u16 reffcode; __u16 refdwlen; __u16 refversn; __u64 refgaddr; __u64 refselmk; __u64 refcmpmk; __u64 reserved; } __attribute__ ((packed)) pfault_refbk_t; int pfault_init(void) { pfault_refbk_t refbk = { 0x258, 0, 5, 2, __LC_KERNEL_STACK, 1ULL << 48, 1ULL << 48, 0ULL }; int rc; if (pfault_disable) return -1; __asm__ __volatile__( " diag %1,%0,0x258\n" "0: j 2f\n" "1: la %0,8\n" "2:\n" ".section __ex_table,\"a\"\n" " .align 4\n" " .long 0b,1b\n" ".previous" : "=d" (rc) : "a" (&refbk) : "cc" ); __ctl_set_bit(0, 9); return rc; } void pfault_fini(void) { pfault_refbk_t refbk = { 0x258, 1, 5, 2, 0ULL, 0ULL, 0ULL, 0ULL }; if (pfault_disable) return; __ctl_clear_bit(0,9); __asm__ __volatile__( " diag %0,0,0x258\n" "0:\n" ".section __ex_table,\"a\"\n" " .align 4\n" " .long 0b,0b\n" ".previous" : : "a" (&refbk) : "cc" ); } asmlinkage void pfault_interrupt(struct pt_regs *regs, __u16 error_code) { struct task_struct *tsk; wait_queue_head_t queue; wait_queue_head_t *qp; __u16 subcode; /* * Get the external interruption subcode & pfault * initial/completion signal bit. VM stores this * in the 'cpu address' field associated with the * external interrupt. */ subcode = S390_lowcore.cpu_addr; if ((subcode & 0xff00) != 0x0200) return; /* * Get the token (= address of kernel stack of affected task). */ tsk = (struct task_struct *) (*((unsigned long *) __LC_PFAULT_INTPARM) - THREAD_SIZE); /* * We got all needed information from the lowcore and can * now safely switch on interrupts. */ if (regs->psw.mask & PSW_PROBLEM_STATE) __sti(); if (subcode & 0x0080) { /* signal bit is set -> a page has been swapped in by VM */ qp = (wait_queue_head_t *) xchg(&tsk->thread.pfault_wait, -1); if (qp != NULL) { /* Initial interrupt was faster than the completion * interrupt. pfault_wait is valid. Set pfault_wait * back to zero and wake up the process. This can * safely be done because the task is still sleeping * and can't procude new pfaults. */ tsk->thread.pfault_wait = 0ULL; wake_up(qp); } } else { /* signal bit not set -> a real page is missing. */ init_waitqueue_head (&queue); qp = (wait_queue_head_t *) xchg(&tsk->thread.pfault_wait, (addr_t) &queue); if (qp != NULL) { /* Completion interrupt was faster than the initial * interrupt (swapped in a -1 for pfault_wait). Set * pfault_wait back to zero and exit. This can be * done safely because tsk is running in kernel * mode and can't produce new pfaults. */ tsk->thread.pfault_wait = 0ULL; } /* go to sleep */ wait_event(queue, tsk->thread.pfault_wait == 0ULL); } } #endif |