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/5.2/sys/i386/i386/trap.c 121986 2003-11-03 21:53:38Z jhb $"); 42 43 /* 44 * 386 Trap and System call handling 45 */ 46 47 #include "opt_clock.h" 48 #include "opt_cpu.h" 49 #include "opt_ddb.h" 50 #include "opt_isa.h" 51 #include "opt_ktrace.h" 52 #include "opt_npx.h" 53 #include "opt_trap.h" 54 55 #include <sys/param.h> 56 #include <sys/bus.h> 57 #include <sys/systm.h> 58 #include <sys/proc.h> 59 #include <sys/pioctl.h> 60 #include <sys/ptrace.h> 61 #include <sys/kernel.h> 62 #include <sys/ktr.h> 63 #include <sys/lock.h> 64 #include <sys/mutex.h> 65 #include <sys/resourcevar.h> 66 #include <sys/signalvar.h> 67 #include <sys/syscall.h> 68 #include <sys/sysctl.h> 69 #include <sys/sysent.h> 70 #include <sys/uio.h> 71 #include <sys/vmmeter.h> 72 #ifdef KTRACE 73 #include <sys/ktrace.h> 74 #endif 75 76 #include <vm/vm.h> 77 #include <vm/vm_param.h> 78 #include <vm/pmap.h> 79 #include <vm/vm_kern.h> 80 #include <vm/vm_map.h> 81 #include <vm/vm_page.h> 82 #include <vm/vm_extern.h> 83 84 #include <machine/cpu.h> 85 #include <machine/intr_machdep.h> 86 #include <machine/md_var.h> 87 #include <machine/pcb.h> 88 #ifdef SMP 89 #include <machine/smp.h> 90 #endif 91 #include <machine/tss.h> 92 #include <machine/vm86.h> 93 94 #ifdef POWERFAIL_NMI 95 #include <sys/syslog.h> 96 #include <machine/clock.h> 97 #endif 98 99 #include <ddb/ddb.h> 100 101 extern void trap(struct trapframe frame); 102 #ifdef I386_CPU 103 extern int trapwrite(unsigned addr); 104 #endif 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 28 114 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 }; 145 146 #if defined(I586_CPU) && !defined(NO_F00F_HACK) 147 extern int has_f00f_bug; 148 #endif 149 150 #ifdef DDB 151 static int ddb_on_nmi = 1; 152 SYSCTL_INT(_machdep, OID_AUTO, ddb_on_nmi, CTLFLAG_RW, 153 &ddb_on_nmi, 0, "Go to DDB on NMI"); 154 #endif 155 static int panic_on_nmi = 1; 156 SYSCTL_INT(_machdep, OID_AUTO, panic_on_nmi, CTLFLAG_RW, 157 &panic_on_nmi, 0, "Panic on NMI"); 158 159 #ifdef WITNESS 160 extern char *syscallnames[]; 161 #endif 162 163 #ifdef DEVICE_POLLING 164 extern u_int32_t poll_in_trap; 165 extern int ether_poll(int count); 166 #endif /* DEVICE_POLLING */ 167 168 /* 169 * Exception, fault, and trap interface to the FreeBSD kernel. 170 * This common code is called from assembly language IDT gate entry 171 * routines that prepare a suitable stack frame, and restore this 172 * frame after the exception has been processed. 173 */ 174 175 void 176 trap(frame) 177 struct trapframe frame; 178 { 179 struct thread *td = curthread; 180 struct proc *p = td->td_proc; 181 u_int sticks = 0; 182 int i = 0, ucode = 0, type, code; 183 vm_offset_t eva; 184 #ifdef POWERFAIL_NMI 185 static int lastalert = 0; 186 #endif 187 188 atomic_add_int(&cnt.v_trap, 1); 189 type = frame.tf_trapno; 190 191 #ifdef DDB 192 if (db_active) { 193 eva = (type == T_PAGEFLT ? rcr2() : 0); 194 trap_fatal(&frame, eva); 195 goto out; 196 } 197 #endif 198 199 if ((frame.tf_eflags & PSL_I) == 0) { 200 /* 201 * Buggy application or kernel code has disabled 202 * interrupts and then trapped. Enabling interrupts 203 * now is wrong, but it is better than running with 204 * interrupts disabled until they are accidentally 205 * enabled later. 206 */ 207 if (ISPL(frame.tf_cs) == SEL_UPL || (frame.tf_eflags & PSL_VM)) 208 printf( 209 "pid %ld (%s): trap %d with interrupts disabled\n", 210 (long)curproc->p_pid, curproc->p_comm, type); 211 else if (type != T_BPTFLT && type != T_TRCTRAP && 212 frame.tf_eip != (int)cpu_switch_load_gs) { 213 /* 214 * XXX not quite right, since this may be for a 215 * multiple fault in user mode. 216 */ 217 printf("kernel trap %d with interrupts disabled\n", 218 type); 219 /* 220 * Page faults need interrupts diasabled until later, 221 * and we shouldn't enable interrupts while in a 222 * critical section. 223 */ 224 if (type != T_PAGEFLT && td->td_critnest == 0) 225 enable_intr(); 226 } 227 } 228 229 eva = 0; 230 code = frame.tf_err; 231 if (type == T_PAGEFLT) { 232 /* 233 * For some Cyrix CPUs, %cr2 is clobbered by 234 * interrupts. This problem is worked around by using 235 * an interrupt gate for the pagefault handler. We 236 * are finally ready to read %cr2 and then must 237 * reenable interrupts. 238 * 239 * If we get a page fault while in a critical section, then 240 * it is most likely a fatal kernel page fault. The kernel 241 * is already going to panic trying to get a sleep lock to 242 * do the VM lookup, so just consider it a fatal trap so the 243 * kernel can print out a useful trap message and even get 244 * to the debugger. 245 */ 246 eva = rcr2(); 247 if (td->td_critnest == 0) 248 enable_intr(); 249 else 250 trap_fatal(&frame, eva); 251 } 252 253 #ifdef DEVICE_POLLING 254 if (poll_in_trap) 255 ether_poll(poll_in_trap); 256 #endif /* DEVICE_POLLING */ 257 258 if ((ISPL(frame.tf_cs) == SEL_UPL) || 259 ((frame.tf_eflags & PSL_VM) && 260 !(PCPU_GET(curpcb)->pcb_flags & PCB_VM86CALL))) { 261 /* user trap */ 262 263 sticks = td->td_sticks; 264 td->td_frame = &frame; 265 if (td->td_ucred != p->p_ucred) 266 cred_update_thread(td); 267 268 switch (type) { 269 case T_PRIVINFLT: /* privileged instruction fault */ 270 ucode = type; 271 i = SIGILL; 272 break; 273 274 case T_BPTFLT: /* bpt instruction fault */ 275 case T_TRCTRAP: /* trace trap */ 276 enable_intr(); 277 frame.tf_eflags &= ~PSL_T; 278 i = SIGTRAP; 279 break; 280 281 case T_ARITHTRAP: /* arithmetic trap */ 282 #ifdef DEV_NPX 283 ucode = npxtrap(); 284 if (ucode == -1) 285 goto userout; 286 #else 287 ucode = code; 288 #endif 289 i = SIGFPE; 290 break; 291 292 /* 293 * The following two traps can happen in 294 * vm86 mode, and, if so, we want to handle 295 * them specially. 296 */ 297 case T_PROTFLT: /* general protection fault */ 298 case T_STKFLT: /* stack fault */ 299 if (frame.tf_eflags & PSL_VM) { 300 i = vm86_emulate((struct vm86frame *)&frame); 301 if (i == 0) 302 goto user; 303 break; 304 } 305 /* FALLTHROUGH */ 306 307 case T_SEGNPFLT: /* segment not present fault */ 308 case T_TSSFLT: /* invalid TSS fault */ 309 case T_DOUBLEFLT: /* double fault */ 310 default: 311 ucode = code + BUS_SEGM_FAULT ; 312 i = SIGBUS; 313 break; 314 315 case T_PAGEFLT: /* page fault */ 316 if (td->td_flags & TDF_SA) 317 thread_user_enter(p, td); 318 319 i = trap_pfault(&frame, TRUE, eva); 320 #if defined(I586_CPU) && !defined(NO_F00F_HACK) 321 if (i == -2) { 322 /* 323 * The f00f hack workaround has triggered, so 324 * treat the fault as an illegal instruction 325 * (T_PRIVINFLT) instead of a page fault. 326 */ 327 type = frame.tf_trapno = T_PRIVINFLT; 328 329 /* Proceed as in that case. */ 330 ucode = type; 331 i = SIGILL; 332 break; 333 } 334 #endif 335 if (i == -1) 336 goto userout; 337 if (i == 0) 338 goto user; 339 340 ucode = T_PAGEFLT; 341 break; 342 343 case T_DIVIDE: /* integer divide fault */ 344 ucode = FPE_INTDIV; 345 i = SIGFPE; 346 break; 347 348 #ifdef DEV_ISA 349 case T_NMI: 350 #ifdef POWERFAIL_NMI 351 #ifndef TIMER_FREQ 352 # define TIMER_FREQ 1193182 353 #endif 354 mtx_lock(&Giant); 355 if (time_second - lastalert > 10) { 356 log(LOG_WARNING, "NMI: power fail\n"); 357 sysbeep(TIMER_FREQ/880, hz); 358 lastalert = time_second; 359 } 360 mtx_unlock(&Giant); 361 goto userout; 362 #else /* !POWERFAIL_NMI */ 363 /* machine/parity/power fail/"kitchen sink" faults */ 364 /* XXX Giant */ 365 if (isa_nmi(code) == 0) { 366 #ifdef DDB 367 /* 368 * NMI can be hooked up to a pushbutton 369 * for debugging. 370 */ 371 if (ddb_on_nmi) { 372 printf ("NMI ... going to debugger\n"); 373 kdb_trap (type, 0, &frame); 374 } 375 #endif /* DDB */ 376 goto userout; 377 } else if (panic_on_nmi) 378 panic("NMI indicates hardware failure"); 379 break; 380 #endif /* POWERFAIL_NMI */ 381 #endif /* DEV_ISA */ 382 383 case T_OFLOW: /* integer overflow fault */ 384 ucode = FPE_INTOVF; 385 i = SIGFPE; 386 break; 387 388 case T_BOUND: /* bounds check fault */ 389 ucode = FPE_FLTSUB; 390 i = SIGFPE; 391 break; 392 393 case T_DNA: 394 #ifdef DEV_NPX 395 /* transparent fault (due to context switch "late") */ 396 if (npxdna()) 397 goto userout; 398 #endif 399 i = SIGFPE; 400 ucode = FPE_FPU_NP_TRAP; 401 break; 402 403 case T_FPOPFLT: /* FPU operand fetch fault */ 404 ucode = T_FPOPFLT; 405 i = SIGILL; 406 break; 407 408 case T_XMMFLT: /* SIMD floating-point exception */ 409 ucode = 0; /* XXX */ 410 i = SIGFPE; 411 break; 412 } 413 } else { 414 /* kernel trap */ 415 416 KASSERT(cold || td->td_ucred != NULL, 417 ("kernel trap doesn't have ucred")); 418 switch (type) { 419 case T_PAGEFLT: /* page fault */ 420 (void) trap_pfault(&frame, FALSE, eva); 421 goto out; 422 423 case T_DNA: 424 #ifdef DEV_NPX 425 /* 426 * The kernel is apparently using npx for copying. 427 * XXX this should be fatal unless the kernel has 428 * registered such use. 429 */ 430 if (npxdna()) 431 goto out; 432 #endif 433 break; 434 435 /* 436 * The following two traps can happen in 437 * vm86 mode, and, if so, we want to handle 438 * them specially. 439 */ 440 case T_PROTFLT: /* general protection fault */ 441 case T_STKFLT: /* stack fault */ 442 if (frame.tf_eflags & PSL_VM) { 443 i = vm86_emulate((struct vm86frame *)&frame); 444 if (i != 0) 445 /* 446 * returns to original process 447 */ 448 vm86_trap((struct vm86frame *)&frame); 449 goto out; 450 } 451 if (type == T_STKFLT) 452 break; 453 454 /* FALL THROUGH */ 455 456 case T_SEGNPFLT: /* segment not present fault */ 457 if (PCPU_GET(curpcb)->pcb_flags & PCB_VM86CALL) 458 break; 459 460 /* 461 * Invalid %fs's and %gs's can be created using 462 * procfs or PT_SETREGS or by invalidating the 463 * underlying LDT entry. This causes a fault 464 * in kernel mode when the kernel attempts to 465 * switch contexts. Lose the bad context 466 * (XXX) so that we can continue, and generate 467 * a signal. 468 */ 469 if (frame.tf_eip == (int)cpu_switch_load_gs) { 470 PCPU_GET(curpcb)->pcb_gs = 0; 471 #if 0 472 PROC_LOCK(p); 473 psignal(p, SIGBUS); 474 PROC_UNLOCK(p); 475 #endif 476 goto out; 477 } 478 479 if (td->td_intr_nesting_level != 0) 480 break; 481 482 /* 483 * Invalid segment selectors and out of bounds 484 * %eip's and %esp's can be set up in user mode. 485 * This causes a fault in kernel mode when the 486 * kernel tries to return to user mode. We want 487 * to get this fault so that we can fix the 488 * problem here and not have to check all the 489 * selectors and pointers when the user changes 490 * them. 491 */ 492 if (frame.tf_eip == (int)doreti_iret) { 493 frame.tf_eip = (int)doreti_iret_fault; 494 goto out; 495 } 496 if (frame.tf_eip == (int)doreti_popl_ds) { 497 frame.tf_eip = (int)doreti_popl_ds_fault; 498 goto out; 499 } 500 if (frame.tf_eip == (int)doreti_popl_es) { 501 frame.tf_eip = (int)doreti_popl_es_fault; 502 goto out; 503 } 504 if (frame.tf_eip == (int)doreti_popl_fs) { 505 frame.tf_eip = (int)doreti_popl_fs_fault; 506 goto out; 507 } 508 if (PCPU_GET(curpcb) != NULL && 509 PCPU_GET(curpcb)->pcb_onfault != NULL) { 510 frame.tf_eip = 511 (int)PCPU_GET(curpcb)->pcb_onfault; 512 goto out; 513 } 514 break; 515 516 case T_TSSFLT: 517 /* 518 * PSL_NT can be set in user mode and isn't cleared 519 * automatically when the kernel is entered. This 520 * causes a TSS fault when the kernel attempts to 521 * `iret' because the TSS link is uninitialized. We 522 * want to get this fault so that we can fix the 523 * problem here and not every time the kernel is 524 * entered. 525 */ 526 if (frame.tf_eflags & PSL_NT) { 527 frame.tf_eflags &= ~PSL_NT; 528 goto out; 529 } 530 break; 531 532 case T_TRCTRAP: /* trace trap */ 533 if (frame.tf_eip == (int)IDTVEC(lcall_syscall)) { 534 /* 535 * We've just entered system mode via the 536 * syscall lcall. Continue single stepping 537 * silently until the syscall handler has 538 * saved the flags. 539 */ 540 goto out; 541 } 542 if (frame.tf_eip == (int)IDTVEC(lcall_syscall) + 1) { 543 /* 544 * The syscall handler has now saved the 545 * flags. Stop single stepping it. 546 */ 547 frame.tf_eflags &= ~PSL_T; 548 goto out; 549 } 550 /* 551 * Ignore debug register trace traps due to 552 * accesses in the user's address space, which 553 * can happen under several conditions such as 554 * if a user sets a watchpoint on a buffer and 555 * then passes that buffer to a system call. 556 * We still want to get TRCTRAPS for addresses 557 * in kernel space because that is useful when 558 * debugging the kernel. 559 */ 560 /* XXX Giant */ 561 if (user_dbreg_trap() && 562 !(PCPU_GET(curpcb)->pcb_flags & PCB_VM86CALL)) { 563 /* 564 * Reset breakpoint bits because the 565 * processor doesn't 566 */ 567 load_dr6(rdr6() & 0xfffffff0); 568 goto out; 569 } 570 /* 571 * FALLTHROUGH (TRCTRAP kernel mode, kernel address) 572 */ 573 case T_BPTFLT: 574 /* 575 * If DDB is enabled, let it handle the debugger trap. 576 * Otherwise, debugger traps "can't happen". 577 */ 578 #ifdef DDB 579 /* XXX Giant */ 580 if (kdb_trap (type, 0, &frame)) 581 goto out; 582 #endif 583 break; 584 585 #ifdef DEV_ISA 586 case T_NMI: 587 #ifdef POWERFAIL_NMI 588 mtx_lock(&Giant); 589 if (time_second - lastalert > 10) { 590 log(LOG_WARNING, "NMI: power fail\n"); 591 sysbeep(TIMER_FREQ/880, hz); 592 lastalert = time_second; 593 } 594 mtx_unlock(&Giant); 595 goto out; 596 #else /* !POWERFAIL_NMI */ 597 /* XXX Giant */ 598 /* machine/parity/power fail/"kitchen sink" faults */ 599 if (isa_nmi(code) == 0) { 600 #ifdef DDB 601 /* 602 * NMI can be hooked up to a pushbutton 603 * for debugging. 604 */ 605 if (ddb_on_nmi) { 606 printf ("NMI ... going to debugger\n"); 607 kdb_trap (type, 0, &frame); 608 } 609 #endif /* DDB */ 610 goto out; 611 } else if (panic_on_nmi == 0) 612 goto out; 613 /* FALLTHROUGH */ 614 #endif /* POWERFAIL_NMI */ 615 #endif /* DEV_ISA */ 616 } 617 618 trap_fatal(&frame, eva); 619 goto out; 620 } 621 622 /* Translate fault for emulators (e.g. Linux) */ 623 if (*p->p_sysent->sv_transtrap) 624 i = (*p->p_sysent->sv_transtrap)(i, type); 625 626 trapsignal(td, i, ucode); 627 628 #ifdef DEBUG 629 if (type <= MAX_TRAP_MSG) { 630 uprintf("fatal process exception: %s", 631 trap_msg[type]); 632 if ((type == T_PAGEFLT) || (type == T_PROTFLT)) 633 uprintf(", fault VA = 0x%lx", (u_long)eva); 634 uprintf("\n"); 635 } 636 #endif 637 638 user: 639 userret(td, &frame, sticks); 640 mtx_assert(&Giant, MA_NOTOWNED); 641 userout: 642 #ifdef DIAGNOSTIC 643 cred_free_thread(td); 644 #endif 645 out: 646 return; 647 } 648 649 static int 650 trap_pfault(frame, usermode, eva) 651 struct trapframe *frame; 652 int usermode; 653 vm_offset_t eva; 654 { 655 vm_offset_t va; 656 struct vmspace *vm = NULL; 657 vm_map_t map = 0; 658 int rv = 0; 659 vm_prot_t ftype; 660 struct thread *td = curthread; 661 struct proc *p = td->td_proc; 662 663 va = trunc_page(eva); 664 if (va >= KERNBASE) { 665 /* 666 * Don't allow user-mode faults in kernel address space. 667 * An exception: if the faulting address is the invalid 668 * instruction entry in the IDT, then the Intel Pentium 669 * F00F bug workaround was triggered, and we need to 670 * treat it is as an illegal instruction, and not a page 671 * fault. 672 */ 673 #if defined(I586_CPU) && !defined(NO_F00F_HACK) 674 if ((eva == (unsigned int)&idt[6]) && has_f00f_bug) 675 return -2; 676 #endif 677 if (usermode) 678 goto nogo; 679 680 map = kernel_map; 681 } else { 682 /* 683 * This is a fault on non-kernel virtual memory. 684 * vm is initialized above to NULL. If curproc is NULL 685 * or curproc->p_vmspace is NULL the fault is fatal. 686 */ 687 if (p != NULL) 688 vm = p->p_vmspace; 689 690 if (vm == NULL) 691 goto nogo; 692 693 map = &vm->vm_map; 694 } 695 696 if (frame->tf_err & PGEX_W) 697 ftype = VM_PROT_WRITE; 698 else 699 ftype = VM_PROT_READ; 700 701 if (map != kernel_map) { 702 /* 703 * Keep swapout from messing with us during this 704 * critical time. 705 */ 706 PROC_LOCK(p); 707 ++p->p_lock; 708 PROC_UNLOCK(p); 709 710 /* Fault in the user page: */ 711 rv = vm_fault(map, va, ftype, 712 (ftype & VM_PROT_WRITE) ? VM_FAULT_DIRTY 713 : VM_FAULT_NORMAL); 714 715 PROC_LOCK(p); 716 --p->p_lock; 717 PROC_UNLOCK(p); 718 } else { 719 /* 720 * Don't have to worry about process locking or stacks in the 721 * kernel. 722 */ 723 rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL); 724 } 725 if (rv == KERN_SUCCESS) 726 return (0); 727 nogo: 728 if (!usermode) { 729 if (td->td_intr_nesting_level == 0 && 730 PCPU_GET(curpcb) != NULL && 731 PCPU_GET(curpcb)->pcb_onfault != NULL) { 732 frame->tf_eip = (int)PCPU_GET(curpcb)->pcb_onfault; 733 return (0); 734 } 735 trap_fatal(frame, eva); 736 return (-1); 737 } 738 739 /* kludge to pass faulting virtual address to sendsig */ 740 frame->tf_err = eva; 741 742 return((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV); 743 } 744 745 static void 746 trap_fatal(frame, eva) 747 struct trapframe *frame; 748 vm_offset_t eva; 749 { 750 int code, type, ss, esp; 751 struct soft_segment_descriptor softseg; 752 753 code = frame->tf_err; 754 type = frame->tf_trapno; 755 sdtossd(&gdt[IDXSEL(frame->tf_cs & 0xffff)].sd, &softseg); 756 757 if (type <= MAX_TRAP_MSG) 758 printf("\n\nFatal trap %d: %s while in %s mode\n", 759 type, trap_msg[type], 760 frame->tf_eflags & PSL_VM ? "vm86" : 761 ISPL(frame->tf_cs) == SEL_UPL ? "user" : "kernel"); 762 #ifdef SMP 763 /* two separate prints in case of a trap on an unmapped page */ 764 printf("cpuid = %d; ", PCPU_GET(cpuid)); 765 printf("apic id = %02x\n", PCPU_GET(apic_id)); 766 #endif 767 if (type == T_PAGEFLT) { 768 printf("fault virtual address = 0x%x\n", eva); 769 printf("fault code = %s %s, %s\n", 770 code & PGEX_U ? "user" : "supervisor", 771 code & PGEX_W ? "write" : "read", 772 code & PGEX_P ? "protection violation" : "page not present"); 773 } 774 printf("instruction pointer = 0x%x:0x%x\n", 775 frame->tf_cs & 0xffff, frame->tf_eip); 776 if ((ISPL(frame->tf_cs) == SEL_UPL) || (frame->tf_eflags & PSL_VM)) { 777 ss = frame->tf_ss & 0xffff; 778 esp = frame->tf_esp; 779 } else { 780 ss = GSEL(GDATA_SEL, SEL_KPL); 781 esp = (int)&frame->tf_esp; 782 } 783 printf("stack pointer = 0x%x:0x%x\n", ss, esp); 784 printf("frame pointer = 0x%x:0x%x\n", ss, frame->tf_ebp); 785 printf("code segment = base 0x%x, limit 0x%x, type 0x%x\n", 786 softseg.ssd_base, softseg.ssd_limit, softseg.ssd_type); 787 printf(" = DPL %d, pres %d, def32 %d, gran %d\n", 788 softseg.ssd_dpl, softseg.ssd_p, softseg.ssd_def32, 789 softseg.ssd_gran); 790 printf("processor eflags = "); 791 if (frame->tf_eflags & PSL_T) 792 printf("trace trap, "); 793 if (frame->tf_eflags & PSL_I) 794 printf("interrupt enabled, "); 795 if (frame->tf_eflags & PSL_NT) 796 printf("nested task, "); 797 if (frame->tf_eflags & PSL_RF) 798 printf("resume, "); 799 if (frame->tf_eflags & PSL_VM) 800 printf("vm86, "); 801 printf("IOPL = %d\n", (frame->tf_eflags & PSL_IOPL) >> 12); 802 printf("current process = "); 803 if (curproc) { 804 printf("%lu (%s)\n", 805 (u_long)curproc->p_pid, curproc->p_comm ? 806 curproc->p_comm : ""); 807 } else { 808 printf("Idle\n"); 809 } 810 811 #ifdef KDB 812 if (kdb_trap(&psl)) 813 return; 814 #endif 815 #ifdef DDB 816 if ((debugger_on_panic || db_active) && kdb_trap(type, 0, frame)) 817 return; 818 #endif 819 printf("trap number = %d\n", type); 820 if (type <= MAX_TRAP_MSG) 821 panic("%s", trap_msg[type]); 822 else 823 panic("unknown/reserved trap"); 824 } 825 826 /* 827 * Double fault handler. Called when a fault occurs while writing 828 * a frame for a trap/exception onto the stack. This usually occurs 829 * when the stack overflows (such is the case with infinite recursion, 830 * for example). 831 * 832 * XXX Note that the current PTD gets replaced by IdlePTD when the 833 * task switch occurs. This means that the stack that was active at 834 * the time of the double fault is not available at <kstack> unless 835 * the machine was idle when the double fault occurred. The downside 836 * of this is that "trace <ebp>" in ddb won't work. 837 */ 838 void 839 dblfault_handler() 840 { 841 printf("\nFatal double fault:\n"); 842 printf("eip = 0x%x\n", PCPU_GET(common_tss.tss_eip)); 843 printf("esp = 0x%x\n", PCPU_GET(common_tss.tss_esp)); 844 printf("ebp = 0x%x\n", PCPU_GET(common_tss.tss_ebp)); 845 #ifdef SMP 846 /* two separate prints in case of a trap on an unmapped page */ 847 printf("cpuid = %d; ", PCPU_GET(cpuid)); 848 printf("apic id = %02x\n", PCPU_GET(apic_id)); 849 #endif 850 panic("double fault"); 851 } 852 853 #ifdef I386_CPU 854 /* 855 * Compensate for 386 brain damage (missing URKR). 856 * This is a little simpler than the pagefault handler in trap() because 857 * it the page tables have already been faulted in and high addresses 858 * are thrown out early for other reasons. 859 */ 860 int trapwrite(addr) 861 unsigned addr; 862 { 863 struct thread *td; 864 struct proc *p; 865 vm_offset_t va; 866 struct vmspace *vm; 867 int rv; 868 869 va = trunc_page((vm_offset_t)addr); 870 /* 871 * XXX - MAX is END. Changed > to >= for temp. fix. 872 */ 873 if (va >= VM_MAXUSER_ADDRESS) 874 return (1); 875 876 td = curthread; 877 p = td->td_proc; 878 vm = p->p_vmspace; 879 880 PROC_LOCK(p); 881 ++p->p_lock; 882 PROC_UNLOCK(p); 883 884 /* 885 * fault the data page 886 */ 887 rv = vm_fault(&vm->vm_map, va, VM_PROT_WRITE, VM_FAULT_DIRTY); 888 889 PROC_LOCK(p); 890 --p->p_lock; 891 PROC_UNLOCK(p); 892 893 if (rv != KERN_SUCCESS) 894 return 1; 895 896 return (0); 897 } 898 #endif 899 900 /* 901 * syscall - system call request C handler 902 * 903 * A system call is essentially treated as a trap. 904 */ 905 void 906 syscall(frame) 907 struct trapframe frame; 908 { 909 caddr_t params; 910 struct sysent *callp; 911 struct thread *td = curthread; 912 struct proc *p = td->td_proc; 913 register_t orig_tf_eflags; 914 u_int sticks; 915 int error; 916 int narg; 917 int args[8]; 918 u_int code; 919 920 /* 921 * note: PCPU_LAZY_INC() can only be used if we can afford 922 * occassional inaccuracy in the count. 923 */ 924 PCPU_LAZY_INC(cnt.v_syscall); 925 926 #ifdef DIAGNOSTIC 927 if (ISPL(frame.tf_cs) != SEL_UPL) { 928 mtx_lock(&Giant); /* try to stabilize the system XXX */ 929 panic("syscall"); 930 /* NOT REACHED */ 931 mtx_unlock(&Giant); 932 } 933 #endif 934 935 sticks = td->td_sticks; 936 td->td_frame = &frame; 937 if (td->td_ucred != p->p_ucred) 938 cred_update_thread(td); 939 if (p->p_flag & P_SA) 940 thread_user_enter(p, td); 941 params = (caddr_t)frame.tf_esp + sizeof(int); 942 code = frame.tf_eax; 943 orig_tf_eflags = frame.tf_eflags; 944 945 if (p->p_sysent->sv_prepsyscall) { 946 /* 947 * The prep code is MP aware. 948 */ 949 (*p->p_sysent->sv_prepsyscall)(&frame, args, &code, ¶ms); 950 } else { 951 /* 952 * Need to check if this is a 32 bit or 64 bit syscall. 953 * fuword is MP aware. 954 */ 955 if (code == SYS_syscall) { 956 /* 957 * Code is first argument, followed by actual args. 958 */ 959 code = fuword(params); 960 params += sizeof(int); 961 } else if (code == SYS___syscall) { 962 /* 963 * Like syscall, but code is a quad, so as to maintain 964 * quad alignment for the rest of the arguments. 965 */ 966 code = fuword(params); 967 params += sizeof(quad_t); 968 } 969 } 970 971 if (p->p_sysent->sv_mask) 972 code &= p->p_sysent->sv_mask; 973 974 if (code >= p->p_sysent->sv_size) 975 callp = &p->p_sysent->sv_table[0]; 976 else 977 callp = &p->p_sysent->sv_table[code]; 978 979 narg = callp->sy_narg & SYF_ARGMASK; 980 981 /* 982 * copyin and the ktrsyscall()/ktrsysret() code is MP-aware 983 */ 984 if (params != NULL && narg != 0) 985 error = copyin(params, (caddr_t)args, 986 (u_int)(narg * sizeof(int))); 987 else 988 error = 0; 989 990 #ifdef KTRACE 991 if (KTRPOINT(td, KTR_SYSCALL)) 992 ktrsyscall(code, narg, args); 993 #endif 994 995 /* 996 * Try to run the syscall without Giant if the syscall 997 * is MP safe. 998 */ 999 if ((callp->sy_narg & SYF_MPSAFE) == 0) 1000 mtx_lock(&Giant); 1001 1002 if (error == 0) { 1003 td->td_retval[0] = 0; 1004 td->td_retval[1] = frame.tf_edx; 1005 1006 STOPEVENT(p, S_SCE, narg); 1007 1008 PTRACESTOP_SC(p, td, S_PT_SCE); 1009 1010 error = (*callp->sy_call)(td, args); 1011 } 1012 1013 switch (error) { 1014 case 0: 1015 frame.tf_eax = td->td_retval[0]; 1016 frame.tf_edx = td->td_retval[1]; 1017 frame.tf_eflags &= ~PSL_C; 1018 break; 1019 1020 case ERESTART: 1021 /* 1022 * Reconstruct pc, assuming lcall $X,y is 7 bytes, 1023 * int 0x80 is 2 bytes. We saved this in tf_err. 1024 */ 1025 frame.tf_eip -= frame.tf_err; 1026 break; 1027 1028 case EJUSTRETURN: 1029 break; 1030 1031 default: 1032 if (p->p_sysent->sv_errsize) { 1033 if (error >= p->p_sysent->sv_errsize) 1034 error = -1; /* XXX */ 1035 else 1036 error = p->p_sysent->sv_errtbl[error]; 1037 } 1038 frame.tf_eax = error; 1039 frame.tf_eflags |= PSL_C; 1040 break; 1041 } 1042 1043 /* 1044 * Release Giant if we previously set it. 1045 */ 1046 if ((callp->sy_narg & SYF_MPSAFE) == 0) 1047 mtx_unlock(&Giant); 1048 1049 /* 1050 * Traced syscall. 1051 */ 1052 if ((orig_tf_eflags & PSL_T) && !(orig_tf_eflags & PSL_VM)) { 1053 frame.tf_eflags &= ~PSL_T; 1054 trapsignal(td, SIGTRAP, 0); 1055 } 1056 1057 /* 1058 * Handle reschedule and other end-of-syscall issues 1059 */ 1060 userret(td, &frame, sticks); 1061 1062 #ifdef KTRACE 1063 if (KTRPOINT(td, KTR_SYSRET)) 1064 ktrsysret(code, error, td->td_retval[0]); 1065 #endif 1066 1067 /* 1068 * This works because errno is findable through the 1069 * register set. If we ever support an emulation where this 1070 * is not the case, this code will need to be revisited. 1071 */ 1072 STOPEVENT(p, S_SCX, code); 1073 1074 PTRACESTOP_SC(p, td, S_PT_SCX); 1075 1076 #ifdef DIAGNOSTIC 1077 cred_free_thread(td); 1078 #endif 1079 WITNESS_WARN(WARN_PANIC, NULL, "System call %s returning", 1080 (code >= 0 && code < SYS_MAXSYSCALL) ? syscallnames[code] : "???"); 1081 mtx_assert(&sched_lock, MA_NOTOWNED); 1082 mtx_assert(&Giant, MA_NOTOWNED); 1083 } 1084
Cache object: effc05f266187519b051f119898c9e9f
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