Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/i386/i386/trap.c
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1 /*- 2 * Copyright (C) 1994, David Greenman 3 * Copyright (c) 1990, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * This code is derived from software contributed to Berkeley by 7 * the University of Utah, and William Jolitz. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. All advertising materials mentioning features or use of this software 18 * must display the following acknowledgement: 19 * This product includes software developed by the University of 20 * California, Berkeley and its contributors. 21 * 4. Neither the name of the University nor the names of its contributors 22 * may be used to endorse or promote products derived from this software 23 * without specific prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 * 37 * from: @(#)trap.c 7.4 (Berkeley) 5/13/91 38 */ 39 40 #include <sys/cdefs.h> 41 __FBSDID("$FreeBSD: releng/6.1/sys/i386/i386/trap.c 158179 2006-04-30 16:44:43Z cvs2svn $"); 42 43 /* 44 * 386 Trap and System call handling 45 */ 46 47 #include "opt_clock.h" 48 #include "opt_cpu.h" 49 #include "opt_hwpmc_hooks.h" 50 #include "opt_isa.h" 51 #include "opt_kdb.h" 52 #include "opt_ktrace.h" 53 #include "opt_npx.h" 54 #include "opt_trap.h" 55 56 #include <sys/param.h> 57 #include <sys/bus.h> 58 #include <sys/systm.h> 59 #include <sys/proc.h> 60 #include <sys/pioctl.h> 61 #include <sys/ptrace.h> 62 #include <sys/kdb.h> 63 #include <sys/kernel.h> 64 #include <sys/ktr.h> 65 #include <sys/lock.h> 66 #include <sys/mutex.h> 67 #include <sys/resourcevar.h> 68 #include <sys/signalvar.h> 69 #include <sys/syscall.h> 70 #include <sys/sysctl.h> 71 #include <sys/sysent.h> 72 #include <sys/uio.h> 73 #include <sys/vmmeter.h> 74 #ifdef KTRACE 75 #include <sys/ktrace.h> 76 #endif 77 #ifdef HWPMC_HOOKS 78 #include <sys/pmckern.h> 79 #endif 80 81 #include <vm/vm.h> 82 #include <vm/vm_param.h> 83 #include <vm/pmap.h> 84 #include <vm/vm_kern.h> 85 #include <vm/vm_map.h> 86 #include <vm/vm_page.h> 87 #include <vm/vm_extern.h> 88 89 #include <machine/cpu.h> 90 #include <machine/intr_machdep.h> 91 #include <machine/md_var.h> 92 #include <machine/pcb.h> 93 #ifdef SMP 94 #include <machine/smp.h> 95 #endif 96 #include <machine/tss.h> 97 #include <machine/vm86.h> 98 99 #ifdef POWERFAIL_NMI 100 #include <sys/syslog.h> 101 #include <machine/clock.h> 102 #endif 103 104 extern void trap(struct trapframe frame); 105 extern void syscall(struct trapframe frame); 106 107 static int trap_pfault(struct trapframe *, int, vm_offset_t); 108 static void trap_fatal(struct trapframe *, vm_offset_t); 109 void dblfault_handler(void); 110 111 extern inthand_t IDTVEC(lcall_syscall); 112 113 #define MAX_TRAP_MSG 30 114 static char *trap_msg[] = { 115 "", /* 0 unused */ 116 "privileged instruction fault", /* 1 T_PRIVINFLT */ 117 "", /* 2 unused */ 118 "breakpoint instruction fault", /* 3 T_BPTFLT */ 119 "", /* 4 unused */ 120 "", /* 5 unused */ 121 "arithmetic trap", /* 6 T_ARITHTRAP */ 122 "", /* 7 unused */ 123 "", /* 8 unused */ 124 "general protection fault", /* 9 T_PROTFLT */ 125 "trace trap", /* 10 T_TRCTRAP */ 126 "", /* 11 unused */ 127 "page fault", /* 12 T_PAGEFLT */ 128 "", /* 13 unused */ 129 "alignment fault", /* 14 T_ALIGNFLT */ 130 "", /* 15 unused */ 131 "", /* 16 unused */ 132 "", /* 17 unused */ 133 "integer divide fault", /* 18 T_DIVIDE */ 134 "non-maskable interrupt trap", /* 19 T_NMI */ 135 "overflow trap", /* 20 T_OFLOW */ 136 "FPU bounds check fault", /* 21 T_BOUND */ 137 "FPU device not available", /* 22 T_DNA */ 138 "double fault", /* 23 T_DOUBLEFLT */ 139 "FPU operand fetch fault", /* 24 T_FPOPFLT */ 140 "invalid TSS fault", /* 25 T_TSSFLT */ 141 "segment not present fault", /* 26 T_SEGNPFLT */ 142 "stack fault", /* 27 T_STKFLT */ 143 "machine check trap", /* 28 T_MCHK */ 144 "SIMD floating-point exception", /* 29 T_XMMFLT */ 145 "reserved (unknown) fault", /* 30 T_RESERVED */ 146 }; 147 148 #if defined(I586_CPU) && !defined(NO_F00F_HACK) 149 extern int has_f00f_bug; 150 #endif 151 152 #ifdef KDB 153 static int kdb_on_nmi = 1; 154 SYSCTL_INT(_machdep, OID_AUTO, kdb_on_nmi, CTLFLAG_RW, 155 &kdb_on_nmi, 0, "Go to KDB on NMI"); 156 #endif 157 static int panic_on_nmi = 1; 158 SYSCTL_INT(_machdep, OID_AUTO, panic_on_nmi, CTLFLAG_RW, 159 &panic_on_nmi, 0, "Panic on NMI"); 160 161 #ifdef WITNESS 162 extern char *syscallnames[]; 163 #endif 164 165 /* 166 * Exception, fault, and trap interface to the FreeBSD kernel. 167 * This common code is called from assembly language IDT gate entry 168 * routines that prepare a suitable stack frame, and restore this 169 * frame after the exception has been processed. 170 */ 171 172 void 173 trap(frame) 174 struct trapframe frame; 175 { 176 struct thread *td = curthread; 177 struct proc *p = td->td_proc; 178 u_int sticks = 0; 179 int i = 0, ucode = 0, type, code; 180 vm_offset_t eva; 181 #ifdef POWERFAIL_NMI 182 static int lastalert = 0; 183 #endif 184 185 PCPU_LAZY_INC(cnt.v_trap); 186 type = frame.tf_trapno; 187 188 #ifdef KDB_STOP_NMI 189 /* Handler for NMI IPIs used for debugging */ 190 if (type == T_NMI) { 191 if (ipi_nmi_handler() == 0) 192 goto out; 193 } 194 #endif /* KDB_STOP_NMI */ 195 196 #ifdef KDB 197 if (kdb_active) { 198 kdb_reenter(); 199 goto out; 200 } 201 #endif 202 203 #ifdef HWPMC_HOOKS 204 /* 205 * CPU PMCs interrupt using an NMI so we check for that first. 206 * If the HWPMC module is active, 'pmc_hook' will point to 207 * the function to be called. A return value of '1' from the 208 * hook means that the NMI was handled by it and that we can 209 * return immediately. 210 */ 211 if (type == T_NMI && pmc_intr && 212 (*pmc_intr)(PCPU_GET(cpuid), (uintptr_t) frame.tf_eip, 213 TRAPF_USERMODE(&frame))) 214 goto out; 215 #endif 216 217 if ((frame.tf_eflags & PSL_I) == 0) { 218 /* 219 * Buggy application or kernel code has disabled 220 * interrupts and then trapped. Enabling interrupts 221 * now is wrong, but it is better than running with 222 * interrupts disabled until they are accidentally 223 * enabled later. 224 */ 225 if (ISPL(frame.tf_cs) == SEL_UPL || (frame.tf_eflags & PSL_VM)) 226 printf( 227 "pid %ld (%s): trap %d with interrupts disabled\n", 228 (long)curproc->p_pid, curproc->p_comm, type); 229 else if (type != T_BPTFLT && type != T_TRCTRAP && 230 frame.tf_eip != (int)cpu_switch_load_gs) { 231 /* 232 * XXX not quite right, since this may be for a 233 * multiple fault in user mode. 234 */ 235 printf("kernel trap %d with interrupts disabled\n", 236 type); 237 /* 238 * Page faults need interrupts disabled until later, 239 * and we shouldn't enable interrupts while in a 240 * critical section or if servicing an NMI. 241 */ 242 if (type != T_NMI && type != T_PAGEFLT && 243 td->td_critnest == 0) 244 enable_intr(); 245 } 246 } 247 248 eva = 0; 249 code = frame.tf_err; 250 if (type == T_PAGEFLT) { 251 /* 252 * For some Cyrix CPUs, %cr2 is clobbered by 253 * interrupts. This problem is worked around by using 254 * an interrupt gate for the pagefault handler. We 255 * are finally ready to read %cr2 and then must 256 * reenable interrupts. 257 * 258 * If we get a page fault while in a critical section, then 259 * it is most likely a fatal kernel page fault. The kernel 260 * is already going to panic trying to get a sleep lock to 261 * do the VM lookup, so just consider it a fatal trap so the 262 * kernel can print out a useful trap message and even get 263 * to the debugger. 264 */ 265 eva = rcr2(); 266 if (td->td_critnest == 0) 267 enable_intr(); 268 else 269 trap_fatal(&frame, eva); 270 } 271 272 if ((ISPL(frame.tf_cs) == SEL_UPL) || 273 ((frame.tf_eflags & PSL_VM) && 274 !(PCPU_GET(curpcb)->pcb_flags & PCB_VM86CALL))) { 275 /* user trap */ 276 277 sticks = td->td_sticks; 278 td->td_frame = &frame; 279 if (td->td_ucred != p->p_ucred) 280 cred_update_thread(td); 281 282 switch (type) { 283 case T_PRIVINFLT: /* privileged instruction fault */ 284 ucode = type; 285 i = SIGILL; 286 break; 287 288 case T_BPTFLT: /* bpt instruction fault */ 289 case T_TRCTRAP: /* trace trap */ 290 enable_intr(); 291 frame.tf_eflags &= ~PSL_T; 292 i = SIGTRAP; 293 break; 294 295 case T_ARITHTRAP: /* arithmetic trap */ 296 #ifdef DEV_NPX 297 ucode = npxtrap(); 298 if (ucode == -1) 299 goto userout; 300 #else 301 ucode = code; 302 #endif 303 i = SIGFPE; 304 break; 305 306 /* 307 * The following two traps can happen in 308 * vm86 mode, and, if so, we want to handle 309 * them specially. 310 */ 311 case T_PROTFLT: /* general protection fault */ 312 case T_STKFLT: /* stack fault */ 313 if (frame.tf_eflags & PSL_VM) { 314 i = vm86_emulate((struct vm86frame *)&frame); 315 if (i == 0) 316 goto user; 317 break; 318 } 319 /* FALLTHROUGH */ 320 321 case T_SEGNPFLT: /* segment not present fault */ 322 case T_TSSFLT: /* invalid TSS fault */ 323 case T_DOUBLEFLT: /* double fault */ 324 default: 325 ucode = code + BUS_SEGM_FAULT ; 326 i = SIGBUS; 327 break; 328 329 case T_PAGEFLT: /* page fault */ 330 if (td->td_pflags & TDP_SA) 331 thread_user_enter(td); 332 333 i = trap_pfault(&frame, TRUE, eva); 334 #if defined(I586_CPU) && !defined(NO_F00F_HACK) 335 if (i == -2) { 336 /* 337 * The f00f hack workaround has triggered, so 338 * treat the fault as an illegal instruction 339 * (T_PRIVINFLT) instead of a page fault. 340 */ 341 type = frame.tf_trapno = T_PRIVINFLT; 342 343 /* Proceed as in that case. */ 344 ucode = type; 345 i = SIGILL; 346 break; 347 } 348 #endif 349 if (i == -1) 350 goto userout; 351 if (i == 0) 352 goto user; 353 354 ucode = T_PAGEFLT; 355 break; 356 357 case T_DIVIDE: /* integer divide fault */ 358 ucode = FPE_INTDIV; 359 i = SIGFPE; 360 break; 361 362 #ifdef DEV_ISA 363 case T_NMI: 364 #ifdef POWERFAIL_NMI 365 #ifndef TIMER_FREQ 366 # define TIMER_FREQ 1193182 367 #endif 368 mtx_lock(&Giant); 369 if (time_second - lastalert > 10) { 370 log(LOG_WARNING, "NMI: power fail\n"); 371 sysbeep(TIMER_FREQ/880, hz); 372 lastalert = time_second; 373 } 374 mtx_unlock(&Giant); 375 goto userout; 376 #else /* !POWERFAIL_NMI */ 377 /* machine/parity/power fail/"kitchen sink" faults */ 378 /* XXX Giant */ 379 if (isa_nmi(code) == 0) { 380 #ifdef KDB 381 /* 382 * NMI can be hooked up to a pushbutton 383 * for debugging. 384 */ 385 if (kdb_on_nmi) { 386 printf ("NMI ... going to debugger\n"); 387 kdb_trap(type, 0, &frame); 388 } 389 #endif /* KDB */ 390 goto userout; 391 } else if (panic_on_nmi) 392 panic("NMI indicates hardware failure"); 393 break; 394 #endif /* POWERFAIL_NMI */ 395 #endif /* DEV_ISA */ 396 397 case T_OFLOW: /* integer overflow fault */ 398 ucode = FPE_INTOVF; 399 i = SIGFPE; 400 break; 401 402 case T_BOUND: /* bounds check fault */ 403 ucode = FPE_FLTSUB; 404 i = SIGFPE; 405 break; 406 407 case T_DNA: 408 #ifdef DEV_NPX 409 /* transparent fault (due to context switch "late") */ 410 if (npxdna()) 411 goto userout; 412 #endif 413 i = SIGFPE; 414 ucode = FPE_FPU_NP_TRAP; 415 break; 416 417 case T_FPOPFLT: /* FPU operand fetch fault */ 418 ucode = T_FPOPFLT; 419 i = SIGILL; 420 break; 421 422 case T_XMMFLT: /* SIMD floating-point exception */ 423 ucode = 0; /* XXX */ 424 i = SIGFPE; 425 break; 426 } 427 } else { 428 /* kernel trap */ 429 430 KASSERT(cold || td->td_ucred != NULL, 431 ("kernel trap doesn't have ucred")); 432 switch (type) { 433 case T_PAGEFLT: /* page fault */ 434 (void) trap_pfault(&frame, FALSE, eva); 435 goto out; 436 437 case T_DNA: 438 #ifdef DEV_NPX 439 /* 440 * The kernel is apparently using npx for copying. 441 * XXX this should be fatal unless the kernel has 442 * registered such use. 443 */ 444 if (npxdna()) 445 goto out; 446 #endif 447 break; 448 449 /* 450 * The following two traps can happen in 451 * vm86 mode, and, if so, we want to handle 452 * them specially. 453 */ 454 case T_PROTFLT: /* general protection fault */ 455 case T_STKFLT: /* stack fault */ 456 if (frame.tf_eflags & PSL_VM) { 457 i = vm86_emulate((struct vm86frame *)&frame); 458 if (i != 0) 459 /* 460 * returns to original process 461 */ 462 vm86_trap((struct vm86frame *)&frame); 463 goto out; 464 } 465 if (type == T_STKFLT) 466 break; 467 468 /* FALL THROUGH */ 469 470 case T_SEGNPFLT: /* segment not present fault */ 471 if (PCPU_GET(curpcb)->pcb_flags & PCB_VM86CALL) 472 break; 473 474 /* 475 * Invalid %fs's and %gs's can be created using 476 * procfs or PT_SETREGS or by invalidating the 477 * underlying LDT entry. This causes a fault 478 * in kernel mode when the kernel attempts to 479 * switch contexts. Lose the bad context 480 * (XXX) so that we can continue, and generate 481 * a signal. 482 */ 483 if (frame.tf_eip == (int)cpu_switch_load_gs) { 484 PCPU_GET(curpcb)->pcb_gs = 0; 485 #if 0 486 PROC_LOCK(p); 487 psignal(p, SIGBUS); 488 PROC_UNLOCK(p); 489 #endif 490 goto out; 491 } 492 493 if (td->td_intr_nesting_level != 0) 494 break; 495 496 /* 497 * Invalid segment selectors and out of bounds 498 * %eip's and %esp's can be set up in user mode. 499 * This causes a fault in kernel mode when the 500 * kernel tries to return to user mode. We want 501 * to get this fault so that we can fix the 502 * problem here and not have to check all the 503 * selectors and pointers when the user changes 504 * them. 505 */ 506 if (frame.tf_eip == (int)doreti_iret) { 507 frame.tf_eip = (int)doreti_iret_fault; 508 goto out; 509 } 510 if (frame.tf_eip == (int)doreti_popl_ds) { 511 frame.tf_eip = (int)doreti_popl_ds_fault; 512 goto out; 513 } 514 if (frame.tf_eip == (int)doreti_popl_es) { 515 frame.tf_eip = (int)doreti_popl_es_fault; 516 goto out; 517 } 518 if (frame.tf_eip == (int)doreti_popl_fs) { 519 frame.tf_eip = (int)doreti_popl_fs_fault; 520 goto out; 521 } 522 if (PCPU_GET(curpcb)->pcb_onfault != NULL) { 523 frame.tf_eip = 524 (int)PCPU_GET(curpcb)->pcb_onfault; 525 goto out; 526 } 527 break; 528 529 case T_TSSFLT: 530 /* 531 * PSL_NT can be set in user mode and isn't cleared 532 * automatically when the kernel is entered. This 533 * causes a TSS fault when the kernel attempts to 534 * `iret' because the TSS link is uninitialized. We 535 * want to get this fault so that we can fix the 536 * problem here and not every time the kernel is 537 * entered. 538 */ 539 if (frame.tf_eflags & PSL_NT) { 540 frame.tf_eflags &= ~PSL_NT; 541 goto out; 542 } 543 break; 544 545 case T_TRCTRAP: /* trace trap */ 546 if (frame.tf_eip == (int)IDTVEC(lcall_syscall)) { 547 /* 548 * We've just entered system mode via the 549 * syscall lcall. Continue single stepping 550 * silently until the syscall handler has 551 * saved the flags. 552 */ 553 goto out; 554 } 555 if (frame.tf_eip == (int)IDTVEC(lcall_syscall) + 1) { 556 /* 557 * The syscall handler has now saved the 558 * flags. Stop single stepping it. 559 */ 560 frame.tf_eflags &= ~PSL_T; 561 goto out; 562 } 563 /* 564 * Ignore debug register trace traps due to 565 * accesses in the user's address space, which 566 * can happen under several conditions such as 567 * if a user sets a watchpoint on a buffer and 568 * then passes that buffer to a system call. 569 * We still want to get TRCTRAPS for addresses 570 * in kernel space because that is useful when 571 * debugging the kernel. 572 */ 573 /* XXX Giant */ 574 if (user_dbreg_trap() && 575 !(PCPU_GET(curpcb)->pcb_flags & PCB_VM86CALL)) { 576 /* 577 * Reset breakpoint bits because the 578 * processor doesn't 579 */ 580 load_dr6(rdr6() & 0xfffffff0); 581 goto out; 582 } 583 /* 584 * FALLTHROUGH (TRCTRAP kernel mode, kernel address) 585 */ 586 case T_BPTFLT: 587 /* 588 * If KDB is enabled, let it handle the debugger trap. 589 * Otherwise, debugger traps "can't happen". 590 */ 591 #ifdef KDB 592 /* XXX Giant */ 593 if (kdb_trap(type, 0, &frame)) 594 goto out; 595 #endif 596 break; 597 598 #ifdef DEV_ISA 599 case T_NMI: 600 #ifdef POWERFAIL_NMI 601 mtx_lock(&Giant); 602 if (time_second - lastalert > 10) { 603 log(LOG_WARNING, "NMI: power fail\n"); 604 sysbeep(TIMER_FREQ/880, hz); 605 lastalert = time_second; 606 } 607 mtx_unlock(&Giant); 608 goto out; 609 #else /* !POWERFAIL_NMI */ 610 /* XXX Giant */ 611 /* machine/parity/power fail/"kitchen sink" faults */ 612 if (isa_nmi(code) == 0) { 613 #ifdef KDB 614 /* 615 * NMI can be hooked up to a pushbutton 616 * for debugging. 617 */ 618 if (kdb_on_nmi) { 619 printf ("NMI ... going to debugger\n"); 620 kdb_trap(type, 0, &frame); 621 } 622 #endif /* KDB */ 623 goto out; 624 } else if (panic_on_nmi == 0) 625 goto out; 626 /* FALLTHROUGH */ 627 #endif /* POWERFAIL_NMI */ 628 #endif /* DEV_ISA */ 629 } 630 631 trap_fatal(&frame, eva); 632 goto out; 633 } 634 635 /* Translate fault for emulators (e.g. Linux) */ 636 if (*p->p_sysent->sv_transtrap) 637 i = (*p->p_sysent->sv_transtrap)(i, type); 638 639 trapsignal(td, i, ucode); 640 641 #ifdef DEBUG 642 if (type <= MAX_TRAP_MSG) { 643 uprintf("fatal process exception: %s", 644 trap_msg[type]); 645 if ((type == T_PAGEFLT) || (type == T_PROTFLT)) 646 uprintf(", fault VA = 0x%lx", (u_long)eva); 647 uprintf("\n"); 648 } 649 #endif 650 651 user: 652 userret(td, &frame, sticks); 653 mtx_assert(&Giant, MA_NOTOWNED); 654 userout: 655 out: 656 return; 657 } 658 659 static int 660 trap_pfault(frame, usermode, eva) 661 struct trapframe *frame; 662 int usermode; 663 vm_offset_t eva; 664 { 665 vm_offset_t va; 666 struct vmspace *vm = NULL; 667 vm_map_t map = 0; 668 int rv = 0; 669 vm_prot_t ftype; 670 struct thread *td = curthread; 671 struct proc *p = td->td_proc; 672 673 va = trunc_page(eva); 674 if (va >= KERNBASE) { 675 /* 676 * Don't allow user-mode faults in kernel address space. 677 * An exception: if the faulting address is the invalid 678 * instruction entry in the IDT, then the Intel Pentium 679 * F00F bug workaround was triggered, and we need to 680 * treat it is as an illegal instruction, and not a page 681 * fault. 682 */ 683 #if defined(I586_CPU) && !defined(NO_F00F_HACK) 684 if ((eva == (unsigned int)&idt[6]) && has_f00f_bug) 685 return -2; 686 #endif 687 if (usermode) 688 goto nogo; 689 690 map = kernel_map; 691 } else { 692 /* 693 * This is a fault on non-kernel virtual memory. 694 * vm is initialized above to NULL. If curproc is NULL 695 * or curproc->p_vmspace is NULL the fault is fatal. 696 */ 697 if (p != NULL) 698 vm = p->p_vmspace; 699 700 if (vm == NULL) 701 goto nogo; 702 703 map = &vm->vm_map; 704 } 705 706 if (frame->tf_err & PGEX_W) 707 ftype = VM_PROT_WRITE; 708 else 709 ftype = VM_PROT_READ; 710 711 if (map != kernel_map) { 712 /* 713 * Keep swapout from messing with us during this 714 * critical time. 715 */ 716 PROC_LOCK(p); 717 ++p->p_lock; 718 PROC_UNLOCK(p); 719 720 /* Fault in the user page: */ 721 rv = vm_fault(map, va, ftype, 722 (ftype & VM_PROT_WRITE) ? VM_FAULT_DIRTY 723 : VM_FAULT_NORMAL); 724 725 PROC_LOCK(p); 726 --p->p_lock; 727 PROC_UNLOCK(p); 728 } else { 729 /* 730 * Don't have to worry about process locking or stacks in the 731 * kernel. 732 */ 733 rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL); 734 } 735 if (rv == KERN_SUCCESS) 736 return (0); 737 nogo: 738 if (!usermode) { 739 if (td->td_intr_nesting_level == 0 && 740 PCPU_GET(curpcb)->pcb_onfault != NULL) { 741 frame->tf_eip = (int)PCPU_GET(curpcb)->pcb_onfault; 742 return (0); 743 } 744 trap_fatal(frame, eva); 745 return (-1); 746 } 747 748 /* kludge to pass faulting virtual address to sendsig */ 749 frame->tf_err = eva; 750 751 return((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV); 752 } 753 754 static void 755 trap_fatal(frame, eva) 756 struct trapframe *frame; 757 vm_offset_t eva; 758 { 759 int code, type, ss, esp; 760 struct soft_segment_descriptor softseg; 761 char *msg; 762 763 code = frame->tf_err; 764 type = frame->tf_trapno; 765 sdtossd(&gdt[IDXSEL(frame->tf_cs & 0xffff)].sd, &softseg); 766 767 if (type <= MAX_TRAP_MSG) 768 msg = trap_msg[type]; 769 else 770 msg = "UNKNOWN"; 771 printf("\n\nFatal trap %d: %s while in %s mode\n", type, msg, 772 frame->tf_eflags & PSL_VM ? "vm86" : 773 ISPL(frame->tf_cs) == SEL_UPL ? "user" : "kernel"); 774 #ifdef SMP 775 /* two separate prints in case of a trap on an unmapped page */ 776 printf("cpuid = %d; ", PCPU_GET(cpuid)); 777 printf("apic id = %02x\n", PCPU_GET(apic_id)); 778 #endif 779 if (type == T_PAGEFLT) { 780 printf("fault virtual address = 0x%x\n", eva); 781 printf("fault code = %s %s, %s\n", 782 code & PGEX_U ? "user" : "supervisor", 783 code & PGEX_W ? "write" : "read", 784 code & PGEX_P ? "protection violation" : "page not present"); 785 } 786 printf("instruction pointer = 0x%x:0x%x\n", 787 frame->tf_cs & 0xffff, frame->tf_eip); 788 if ((ISPL(frame->tf_cs) == SEL_UPL) || (frame->tf_eflags & PSL_VM)) { 789 ss = frame->tf_ss & 0xffff; 790 esp = frame->tf_esp; 791 } else { 792 ss = GSEL(GDATA_SEL, SEL_KPL); 793 esp = (int)&frame->tf_esp; 794 } 795 printf("stack pointer = 0x%x:0x%x\n", ss, esp); 796 printf("frame pointer = 0x%x:0x%x\n", ss, frame->tf_ebp); 797 printf("code segment = base 0x%x, limit 0x%x, type 0x%x\n", 798 softseg.ssd_base, softseg.ssd_limit, softseg.ssd_type); 799 printf(" = DPL %d, pres %d, def32 %d, gran %d\n", 800 softseg.ssd_dpl, softseg.ssd_p, softseg.ssd_def32, 801 softseg.ssd_gran); 802 printf("processor eflags = "); 803 if (frame->tf_eflags & PSL_T) 804 printf("trace trap, "); 805 if (frame->tf_eflags & PSL_I) 806 printf("interrupt enabled, "); 807 if (frame->tf_eflags & PSL_NT) 808 printf("nested task, "); 809 if (frame->tf_eflags & PSL_RF) 810 printf("resume, "); 811 if (frame->tf_eflags & PSL_VM) 812 printf("vm86, "); 813 printf("IOPL = %d\n", (frame->tf_eflags & PSL_IOPL) >> 12); 814 printf("current process = "); 815 if (curproc) { 816 printf("%lu (%s)\n", 817 (u_long)curproc->p_pid, curproc->p_comm ? 818 curproc->p_comm : ""); 819 } else { 820 printf("Idle\n"); 821 } 822 823 #ifdef KDB 824 if (debugger_on_panic || kdb_active) { 825 register_t eflags; 826 eflags = intr_disable(); 827 if (kdb_trap(type, 0, frame)) { 828 intr_restore(eflags); 829 return; 830 } 831 intr_restore(eflags); 832 } 833 #endif 834 printf("trap number = %d\n", type); 835 if (type <= MAX_TRAP_MSG) 836 panic("%s", trap_msg[type]); 837 else 838 panic("unknown/reserved trap"); 839 } 840 841 /* 842 * Double fault handler. Called when a fault occurs while writing 843 * a frame for a trap/exception onto the stack. This usually occurs 844 * when the stack overflows (such is the case with infinite recursion, 845 * for example). 846 * 847 * XXX Note that the current PTD gets replaced by IdlePTD when the 848 * task switch occurs. This means that the stack that was active at 849 * the time of the double fault is not available at <kstack> unless 850 * the machine was idle when the double fault occurred. The downside 851 * of this is that "trace <ebp>" in ddb won't work. 852 */ 853 void 854 dblfault_handler() 855 { 856 printf("\nFatal double fault:\n"); 857 printf("eip = 0x%x\n", PCPU_GET(common_tss.tss_eip)); 858 printf("esp = 0x%x\n", PCPU_GET(common_tss.tss_esp)); 859 printf("ebp = 0x%x\n", PCPU_GET(common_tss.tss_ebp)); 860 #ifdef SMP 861 /* two separate prints in case of a trap on an unmapped page */ 862 printf("cpuid = %d; ", PCPU_GET(cpuid)); 863 printf("apic id = %02x\n", PCPU_GET(apic_id)); 864 #endif 865 panic("double fault"); 866 } 867 868 /* 869 * syscall - system call request C handler 870 * 871 * A system call is essentially treated as a trap. 872 */ 873 void 874 syscall(frame) 875 struct trapframe frame; 876 { 877 caddr_t params; 878 struct sysent *callp; 879 struct thread *td = curthread; 880 struct proc *p = td->td_proc; 881 register_t orig_tf_eflags; 882 u_int sticks; 883 int error; 884 int narg; 885 int args[8]; 886 u_int code; 887 888 /* 889 * note: PCPU_LAZY_INC() can only be used if we can afford 890 * occassional inaccuracy in the count. 891 */ 892 PCPU_LAZY_INC(cnt.v_syscall); 893 894 #ifdef DIAGNOSTIC 895 if (ISPL(frame.tf_cs) != SEL_UPL) { 896 mtx_lock(&Giant); /* try to stabilize the system XXX */ 897 panic("syscall"); 898 /* NOT REACHED */ 899 mtx_unlock(&Giant); 900 } 901 #endif 902 903 sticks = td->td_sticks; 904 td->td_frame = &frame; 905 if (td->td_ucred != p->p_ucred) 906 cred_update_thread(td); 907 if (p->p_flag & P_SA) 908 thread_user_enter(td); 909 params = (caddr_t)frame.tf_esp + sizeof(int); 910 code = frame.tf_eax; 911 orig_tf_eflags = frame.tf_eflags; 912 913 if (p->p_sysent->sv_prepsyscall) { 914 /* 915 * The prep code is MP aware. 916 */ 917 (*p->p_sysent->sv_prepsyscall)(&frame, args, &code, ¶ms); 918 } else { 919 /* 920 * Need to check if this is a 32 bit or 64 bit syscall. 921 * fuword is MP aware. 922 */ 923 if (code == SYS_syscall) { 924 /* 925 * Code is first argument, followed by actual args. 926 */ 927 code = fuword(params); 928 params += sizeof(int); 929 } else if (code == SYS___syscall) { 930 /* 931 * Like syscall, but code is a quad, so as to maintain 932 * quad alignment for the rest of the arguments. 933 */ 934 code = fuword(params); 935 params += sizeof(quad_t); 936 } 937 } 938 939 if (p->p_sysent->sv_mask) 940 code &= p->p_sysent->sv_mask; 941 942 if (code >= p->p_sysent->sv_size) 943 callp = &p->p_sysent->sv_table[0]; 944 else 945 callp = &p->p_sysent->sv_table[code]; 946 947 narg = callp->sy_narg & SYF_ARGMASK; 948 949 /* 950 * copyin and the ktrsyscall()/ktrsysret() code is MP-aware 951 */ 952 if (params != NULL && narg != 0) 953 error = copyin(params, (caddr_t)args, 954 (u_int)(narg * sizeof(int))); 955 else 956 error = 0; 957 958 #ifdef KTRACE 959 if (KTRPOINT(td, KTR_SYSCALL)) 960 ktrsyscall(code, narg, args); 961 #endif 962 963 CTR4(KTR_SYSC, "syscall enter thread %p pid %d proc %s code %d", td, 964 td->td_proc->p_pid, td->td_proc->p_comm, code); 965 966 /* 967 * Try to run the syscall without Giant if the syscall 968 * is MP safe. 969 */ 970 if ((callp->sy_narg & SYF_MPSAFE) == 0) 971 mtx_lock(&Giant); 972 973 if (error == 0) { 974 td->td_retval[0] = 0; 975 td->td_retval[1] = frame.tf_edx; 976 977 STOPEVENT(p, S_SCE, narg); 978 979 PTRACESTOP_SC(p, td, S_PT_SCE); 980 981 error = (*callp->sy_call)(td, args); 982 } 983 984 switch (error) { 985 case 0: 986 frame.tf_eax = td->td_retval[0]; 987 frame.tf_edx = td->td_retval[1]; 988 frame.tf_eflags &= ~PSL_C; 989 break; 990 991 case ERESTART: 992 /* 993 * Reconstruct pc, assuming lcall $X,y is 7 bytes, 994 * int 0x80 is 2 bytes. We saved this in tf_err. 995 */ 996 frame.tf_eip -= frame.tf_err; 997 break; 998 999 case EJUSTRETURN: 1000 break; 1001 1002 default: 1003 if (p->p_sysent->sv_errsize) { 1004 if (error >= p->p_sysent->sv_errsize) 1005 error = -1; /* XXX */ 1006 else 1007 error = p->p_sysent->sv_errtbl[error]; 1008 } 1009 frame.tf_eax = error; 1010 frame.tf_eflags |= PSL_C; 1011 break; 1012 } 1013 1014 /* 1015 * Release Giant if we previously set it. 1016 */ 1017 if ((callp->sy_narg & SYF_MPSAFE) == 0) 1018 mtx_unlock(&Giant); 1019 1020 /* 1021 * Traced syscall. 1022 */ 1023 if ((orig_tf_eflags & PSL_T) && !(orig_tf_eflags & PSL_VM)) { 1024 frame.tf_eflags &= ~PSL_T; 1025 trapsignal(td, SIGTRAP, 0); 1026 } 1027 1028 /* 1029 * Handle reschedule and other end-of-syscall issues 1030 */ 1031 userret(td, &frame, sticks); 1032 1033 CTR4(KTR_SYSC, "syscall exit thread %p pid %d proc %s code %d", td, 1034 td->td_proc->p_pid, td->td_proc->p_comm, code); 1035 1036 #ifdef KTRACE 1037 if (KTRPOINT(td, KTR_SYSRET)) 1038 ktrsysret(code, error, td->td_retval[0]); 1039 #endif 1040 1041 /* 1042 * This works because errno is findable through the 1043 * register set. If we ever support an emulation where this 1044 * is not the case, this code will need to be revisited. 1045 */ 1046 STOPEVENT(p, S_SCX, code); 1047 1048 PTRACESTOP_SC(p, td, S_PT_SCX); 1049 1050 WITNESS_WARN(WARN_PANIC, NULL, "System call %s returning", 1051 (code >= 0 && code < SYS_MAXSYSCALL) ? syscallnames[code] : "???"); 1052 mtx_assert(&sched_lock, MA_NOTOWNED); 1053 mtx_assert(&Giant, MA_NOTOWNED); 1054 } 1055
Cache object: 1bef77e292e4c0963f1834a7a2120b29
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