Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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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/6.0/sys/i386/i386/trap.c 151061 2005-10-07 14:00:06Z glebius $"); 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 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 KDB 151 static int kdb_on_nmi = 1; 152 SYSCTL_INT(_machdep, OID_AUTO, kdb_on_nmi, CTLFLAG_RW, 153 &kdb_on_nmi, 0, "Go to KDB 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 /* 164 * Exception, fault, and trap interface to the FreeBSD kernel. 165 * This common code is called from assembly language IDT gate entry 166 * routines that prepare a suitable stack frame, and restore this 167 * frame after the exception has been processed. 168 */ 169 170 void 171 trap(frame) 172 struct trapframe frame; 173 { 174 struct thread *td = curthread; 175 struct proc *p = td->td_proc; 176 u_int sticks = 0; 177 int i = 0, ucode = 0, type, code; 178 vm_offset_t eva; 179 #ifdef POWERFAIL_NMI 180 static int lastalert = 0; 181 #endif 182 183 PCPU_LAZY_INC(cnt.v_trap); 184 type = frame.tf_trapno; 185 186 #ifdef KDB_STOP_NMI 187 /* Handler for NMI IPIs used for debugging */ 188 if (type == T_NMI) { 189 if (ipi_nmi_handler() == 0) 190 goto out; 191 } 192 #endif /* KDB_STOP_NMI */ 193 194 #ifdef KDB 195 if (kdb_active) { 196 kdb_reenter(); 197 goto out; 198 } 199 #endif 200 201 #ifdef HWPMC_HOOKS 202 /* 203 * CPU PMCs interrupt using an NMI so we check for that first. 204 * If the HWPMC module is active, 'pmc_hook' will point to 205 * the function to be called. A return value of '1' from the 206 * hook means that the NMI was handled by it and that we can 207 * return immediately. 208 */ 209 if (type == T_NMI && pmc_intr && 210 (*pmc_intr)(PCPU_GET(cpuid), (uintptr_t) frame.tf_eip, 211 TRAPF_USERMODE(&frame))) 212 goto out; 213 #endif 214 215 if ((frame.tf_eflags & PSL_I) == 0) { 216 /* 217 * Buggy application or kernel code has disabled 218 * interrupts and then trapped. Enabling interrupts 219 * now is wrong, but it is better than running with 220 * interrupts disabled until they are accidentally 221 * enabled later. 222 */ 223 if (ISPL(frame.tf_cs) == SEL_UPL || (frame.tf_eflags & PSL_VM)) 224 printf( 225 "pid %ld (%s): trap %d with interrupts disabled\n", 226 (long)curproc->p_pid, curproc->p_comm, type); 227 else if (type != T_BPTFLT && type != T_TRCTRAP && 228 frame.tf_eip != (int)cpu_switch_load_gs) { 229 /* 230 * XXX not quite right, since this may be for a 231 * multiple fault in user mode. 232 */ 233 printf("kernel trap %d with interrupts disabled\n", 234 type); 235 /* 236 * Page faults need interrupts disabled until later, 237 * and we shouldn't enable interrupts while in a 238 * critical section or if servicing an NMI. 239 */ 240 if (type != T_NMI && type != T_PAGEFLT && 241 td->td_critnest == 0) 242 enable_intr(); 243 } 244 } 245 246 eva = 0; 247 code = frame.tf_err; 248 if (type == T_PAGEFLT) { 249 /* 250 * For some Cyrix CPUs, %cr2 is clobbered by 251 * interrupts. This problem is worked around by using 252 * an interrupt gate for the pagefault handler. We 253 * are finally ready to read %cr2 and then must 254 * reenable interrupts. 255 * 256 * If we get a page fault while in a critical section, then 257 * it is most likely a fatal kernel page fault. The kernel 258 * is already going to panic trying to get a sleep lock to 259 * do the VM lookup, so just consider it a fatal trap so the 260 * kernel can print out a useful trap message and even get 261 * to the debugger. 262 */ 263 eva = rcr2(); 264 if (td->td_critnest == 0) 265 enable_intr(); 266 else 267 trap_fatal(&frame, eva); 268 } 269 270 if ((ISPL(frame.tf_cs) == SEL_UPL) || 271 ((frame.tf_eflags & PSL_VM) && 272 !(PCPU_GET(curpcb)->pcb_flags & PCB_VM86CALL))) { 273 /* user trap */ 274 275 sticks = td->td_sticks; 276 td->td_frame = &frame; 277 if (td->td_ucred != p->p_ucred) 278 cred_update_thread(td); 279 280 switch (type) { 281 case T_PRIVINFLT: /* privileged instruction fault */ 282 ucode = type; 283 i = SIGILL; 284 break; 285 286 case T_BPTFLT: /* bpt instruction fault */ 287 case T_TRCTRAP: /* trace trap */ 288 enable_intr(); 289 frame.tf_eflags &= ~PSL_T; 290 i = SIGTRAP; 291 break; 292 293 case T_ARITHTRAP: /* arithmetic trap */ 294 #ifdef DEV_NPX 295 ucode = npxtrap(); 296 if (ucode == -1) 297 goto userout; 298 #else 299 ucode = code; 300 #endif 301 i = SIGFPE; 302 break; 303 304 /* 305 * The following two traps can happen in 306 * vm86 mode, and, if so, we want to handle 307 * them specially. 308 */ 309 case T_PROTFLT: /* general protection fault */ 310 case T_STKFLT: /* stack fault */ 311 if (frame.tf_eflags & PSL_VM) { 312 i = vm86_emulate((struct vm86frame *)&frame); 313 if (i == 0) 314 goto user; 315 break; 316 } 317 /* FALLTHROUGH */ 318 319 case T_SEGNPFLT: /* segment not present fault */ 320 case T_TSSFLT: /* invalid TSS fault */ 321 case T_DOUBLEFLT: /* double fault */ 322 default: 323 ucode = code + BUS_SEGM_FAULT ; 324 i = SIGBUS; 325 break; 326 327 case T_PAGEFLT: /* page fault */ 328 if (td->td_pflags & TDP_SA) 329 thread_user_enter(td); 330 331 i = trap_pfault(&frame, TRUE, eva); 332 #if defined(I586_CPU) && !defined(NO_F00F_HACK) 333 if (i == -2) { 334 /* 335 * The f00f hack workaround has triggered, so 336 * treat the fault as an illegal instruction 337 * (T_PRIVINFLT) instead of a page fault. 338 */ 339 type = frame.tf_trapno = T_PRIVINFLT; 340 341 /* Proceed as in that case. */ 342 ucode = type; 343 i = SIGILL; 344 break; 345 } 346 #endif 347 if (i == -1) 348 goto userout; 349 if (i == 0) 350 goto user; 351 352 ucode = T_PAGEFLT; 353 break; 354 355 case T_DIVIDE: /* integer divide fault */ 356 ucode = FPE_INTDIV; 357 i = SIGFPE; 358 break; 359 360 #ifdef DEV_ISA 361 case T_NMI: 362 #ifdef POWERFAIL_NMI 363 #ifndef TIMER_FREQ 364 # define TIMER_FREQ 1193182 365 #endif 366 mtx_lock(&Giant); 367 if (time_second - lastalert > 10) { 368 log(LOG_WARNING, "NMI: power fail\n"); 369 sysbeep(TIMER_FREQ/880, hz); 370 lastalert = time_second; 371 } 372 mtx_unlock(&Giant); 373 goto userout; 374 #else /* !POWERFAIL_NMI */ 375 /* machine/parity/power fail/"kitchen sink" faults */ 376 /* XXX Giant */ 377 if (isa_nmi(code) == 0) { 378 #ifdef KDB 379 /* 380 * NMI can be hooked up to a pushbutton 381 * for debugging. 382 */ 383 if (kdb_on_nmi) { 384 printf ("NMI ... going to debugger\n"); 385 kdb_trap(type, 0, &frame); 386 } 387 #endif /* KDB */ 388 goto userout; 389 } else if (panic_on_nmi) 390 panic("NMI indicates hardware failure"); 391 break; 392 #endif /* POWERFAIL_NMI */ 393 #endif /* DEV_ISA */ 394 395 case T_OFLOW: /* integer overflow fault */ 396 ucode = FPE_INTOVF; 397 i = SIGFPE; 398 break; 399 400 case T_BOUND: /* bounds check fault */ 401 ucode = FPE_FLTSUB; 402 i = SIGFPE; 403 break; 404 405 case T_DNA: 406 #ifdef DEV_NPX 407 /* transparent fault (due to context switch "late") */ 408 if (npxdna()) 409 goto userout; 410 #endif 411 i = SIGFPE; 412 ucode = FPE_FPU_NP_TRAP; 413 break; 414 415 case T_FPOPFLT: /* FPU operand fetch fault */ 416 ucode = T_FPOPFLT; 417 i = SIGILL; 418 break; 419 420 case T_XMMFLT: /* SIMD floating-point exception */ 421 ucode = 0; /* XXX */ 422 i = SIGFPE; 423 break; 424 } 425 } else { 426 /* kernel trap */ 427 428 KASSERT(cold || td->td_ucred != NULL, 429 ("kernel trap doesn't have ucred")); 430 switch (type) { 431 case T_PAGEFLT: /* page fault */ 432 (void) trap_pfault(&frame, FALSE, eva); 433 goto out; 434 435 case T_DNA: 436 #ifdef DEV_NPX 437 /* 438 * The kernel is apparently using npx for copying. 439 * XXX this should be fatal unless the kernel has 440 * registered such use. 441 */ 442 if (npxdna()) 443 goto out; 444 #endif 445 break; 446 447 /* 448 * The following two traps can happen in 449 * vm86 mode, and, if so, we want to handle 450 * them specially. 451 */ 452 case T_PROTFLT: /* general protection fault */ 453 case T_STKFLT: /* stack fault */ 454 if (frame.tf_eflags & PSL_VM) { 455 i = vm86_emulate((struct vm86frame *)&frame); 456 if (i != 0) 457 /* 458 * returns to original process 459 */ 460 vm86_trap((struct vm86frame *)&frame); 461 goto out; 462 } 463 if (type == T_STKFLT) 464 break; 465 466 /* FALL THROUGH */ 467 468 case T_SEGNPFLT: /* segment not present fault */ 469 if (PCPU_GET(curpcb)->pcb_flags & PCB_VM86CALL) 470 break; 471 472 /* 473 * Invalid %fs's and %gs's can be created using 474 * procfs or PT_SETREGS or by invalidating the 475 * underlying LDT entry. This causes a fault 476 * in kernel mode when the kernel attempts to 477 * switch contexts. Lose the bad context 478 * (XXX) so that we can continue, and generate 479 * a signal. 480 */ 481 if (frame.tf_eip == (int)cpu_switch_load_gs) { 482 PCPU_GET(curpcb)->pcb_gs = 0; 483 #if 0 484 PROC_LOCK(p); 485 psignal(p, SIGBUS); 486 PROC_UNLOCK(p); 487 #endif 488 goto out; 489 } 490 491 if (td->td_intr_nesting_level != 0) 492 break; 493 494 /* 495 * Invalid segment selectors and out of bounds 496 * %eip's and %esp's can be set up in user mode. 497 * This causes a fault in kernel mode when the 498 * kernel tries to return to user mode. We want 499 * to get this fault so that we can fix the 500 * problem here and not have to check all the 501 * selectors and pointers when the user changes 502 * them. 503 */ 504 if (frame.tf_eip == (int)doreti_iret) { 505 frame.tf_eip = (int)doreti_iret_fault; 506 goto out; 507 } 508 if (frame.tf_eip == (int)doreti_popl_ds) { 509 frame.tf_eip = (int)doreti_popl_ds_fault; 510 goto out; 511 } 512 if (frame.tf_eip == (int)doreti_popl_es) { 513 frame.tf_eip = (int)doreti_popl_es_fault; 514 goto out; 515 } 516 if (frame.tf_eip == (int)doreti_popl_fs) { 517 frame.tf_eip = (int)doreti_popl_fs_fault; 518 goto out; 519 } 520 if (PCPU_GET(curpcb)->pcb_onfault != NULL) { 521 frame.tf_eip = 522 (int)PCPU_GET(curpcb)->pcb_onfault; 523 goto out; 524 } 525 break; 526 527 case T_TSSFLT: 528 /* 529 * PSL_NT can be set in user mode and isn't cleared 530 * automatically when the kernel is entered. This 531 * causes a TSS fault when the kernel attempts to 532 * `iret' because the TSS link is uninitialized. We 533 * want to get this fault so that we can fix the 534 * problem here and not every time the kernel is 535 * entered. 536 */ 537 if (frame.tf_eflags & PSL_NT) { 538 frame.tf_eflags &= ~PSL_NT; 539 goto out; 540 } 541 break; 542 543 case T_TRCTRAP: /* trace trap */ 544 if (frame.tf_eip == (int)IDTVEC(lcall_syscall)) { 545 /* 546 * We've just entered system mode via the 547 * syscall lcall. Continue single stepping 548 * silently until the syscall handler has 549 * saved the flags. 550 */ 551 goto out; 552 } 553 if (frame.tf_eip == (int)IDTVEC(lcall_syscall) + 1) { 554 /* 555 * The syscall handler has now saved the 556 * flags. Stop single stepping it. 557 */ 558 frame.tf_eflags &= ~PSL_T; 559 goto out; 560 } 561 /* 562 * Ignore debug register trace traps due to 563 * accesses in the user's address space, which 564 * can happen under several conditions such as 565 * if a user sets a watchpoint on a buffer and 566 * then passes that buffer to a system call. 567 * We still want to get TRCTRAPS for addresses 568 * in kernel space because that is useful when 569 * debugging the kernel. 570 */ 571 /* XXX Giant */ 572 if (user_dbreg_trap() && 573 !(PCPU_GET(curpcb)->pcb_flags & PCB_VM86CALL)) { 574 /* 575 * Reset breakpoint bits because the 576 * processor doesn't 577 */ 578 load_dr6(rdr6() & 0xfffffff0); 579 goto out; 580 } 581 /* 582 * FALLTHROUGH (TRCTRAP kernel mode, kernel address) 583 */ 584 case T_BPTFLT: 585 /* 586 * If KDB is enabled, let it handle the debugger trap. 587 * Otherwise, debugger traps "can't happen". 588 */ 589 #ifdef KDB 590 /* XXX Giant */ 591 if (kdb_trap(type, 0, &frame)) 592 goto out; 593 #endif 594 break; 595 596 #ifdef DEV_ISA 597 case T_NMI: 598 #ifdef POWERFAIL_NMI 599 mtx_lock(&Giant); 600 if (time_second - lastalert > 10) { 601 log(LOG_WARNING, "NMI: power fail\n"); 602 sysbeep(TIMER_FREQ/880, hz); 603 lastalert = time_second; 604 } 605 mtx_unlock(&Giant); 606 goto out; 607 #else /* !POWERFAIL_NMI */ 608 /* XXX Giant */ 609 /* machine/parity/power fail/"kitchen sink" faults */ 610 if (isa_nmi(code) == 0) { 611 #ifdef KDB 612 /* 613 * NMI can be hooked up to a pushbutton 614 * for debugging. 615 */ 616 if (kdb_on_nmi) { 617 printf ("NMI ... going to debugger\n"); 618 kdb_trap(type, 0, &frame); 619 } 620 #endif /* KDB */ 621 goto out; 622 } else if (panic_on_nmi == 0) 623 goto out; 624 /* FALLTHROUGH */ 625 #endif /* POWERFAIL_NMI */ 626 #endif /* DEV_ISA */ 627 } 628 629 trap_fatal(&frame, eva); 630 goto out; 631 } 632 633 /* Translate fault for emulators (e.g. Linux) */ 634 if (*p->p_sysent->sv_transtrap) 635 i = (*p->p_sysent->sv_transtrap)(i, type); 636 637 trapsignal(td, i, ucode); 638 639 #ifdef DEBUG 640 if (type <= MAX_TRAP_MSG) { 641 uprintf("fatal process exception: %s", 642 trap_msg[type]); 643 if ((type == T_PAGEFLT) || (type == T_PROTFLT)) 644 uprintf(", fault VA = 0x%lx", (u_long)eva); 645 uprintf("\n"); 646 } 647 #endif 648 649 user: 650 userret(td, &frame, sticks); 651 mtx_assert(&Giant, MA_NOTOWNED); 652 userout: 653 out: 654 return; 655 } 656 657 static int 658 trap_pfault(frame, usermode, eva) 659 struct trapframe *frame; 660 int usermode; 661 vm_offset_t eva; 662 { 663 vm_offset_t va; 664 struct vmspace *vm = NULL; 665 vm_map_t map = 0; 666 int rv = 0; 667 vm_prot_t ftype; 668 struct thread *td = curthread; 669 struct proc *p = td->td_proc; 670 671 va = trunc_page(eva); 672 if (va >= KERNBASE) { 673 /* 674 * Don't allow user-mode faults in kernel address space. 675 * An exception: if the faulting address is the invalid 676 * instruction entry in the IDT, then the Intel Pentium 677 * F00F bug workaround was triggered, and we need to 678 * treat it is as an illegal instruction, and not a page 679 * fault. 680 */ 681 #if defined(I586_CPU) && !defined(NO_F00F_HACK) 682 if ((eva == (unsigned int)&idt[6]) && has_f00f_bug) 683 return -2; 684 #endif 685 if (usermode) 686 goto nogo; 687 688 map = kernel_map; 689 } else { 690 /* 691 * This is a fault on non-kernel virtual memory. 692 * vm is initialized above to NULL. If curproc is NULL 693 * or curproc->p_vmspace is NULL the fault is fatal. 694 */ 695 if (p != NULL) 696 vm = p->p_vmspace; 697 698 if (vm == NULL) 699 goto nogo; 700 701 map = &vm->vm_map; 702 } 703 704 if (frame->tf_err & PGEX_W) 705 ftype = VM_PROT_WRITE; 706 else 707 ftype = VM_PROT_READ; 708 709 if (map != kernel_map) { 710 /* 711 * Keep swapout from messing with us during this 712 * critical time. 713 */ 714 PROC_LOCK(p); 715 ++p->p_lock; 716 PROC_UNLOCK(p); 717 718 /* Fault in the user page: */ 719 rv = vm_fault(map, va, ftype, 720 (ftype & VM_PROT_WRITE) ? VM_FAULT_DIRTY 721 : VM_FAULT_NORMAL); 722 723 PROC_LOCK(p); 724 --p->p_lock; 725 PROC_UNLOCK(p); 726 } else { 727 /* 728 * Don't have to worry about process locking or stacks in the 729 * kernel. 730 */ 731 rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL); 732 } 733 if (rv == KERN_SUCCESS) 734 return (0); 735 nogo: 736 if (!usermode) { 737 if (td->td_intr_nesting_level == 0 && 738 PCPU_GET(curpcb)->pcb_onfault != NULL) { 739 frame->tf_eip = (int)PCPU_GET(curpcb)->pcb_onfault; 740 return (0); 741 } 742 trap_fatal(frame, eva); 743 return (-1); 744 } 745 746 /* kludge to pass faulting virtual address to sendsig */ 747 frame->tf_err = eva; 748 749 return((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV); 750 } 751 752 static void 753 trap_fatal(frame, eva) 754 struct trapframe *frame; 755 vm_offset_t eva; 756 { 757 int code, type, ss, esp; 758 struct soft_segment_descriptor softseg; 759 760 code = frame->tf_err; 761 type = frame->tf_trapno; 762 sdtossd(&gdt[IDXSEL(frame->tf_cs & 0xffff)].sd, &softseg); 763 764 if (type <= MAX_TRAP_MSG) 765 printf("\n\nFatal trap %d: %s while in %s mode\n", 766 type, trap_msg[type], 767 frame->tf_eflags & PSL_VM ? "vm86" : 768 ISPL(frame->tf_cs) == SEL_UPL ? "user" : "kernel"); 769 #ifdef SMP 770 /* two separate prints in case of a trap on an unmapped page */ 771 printf("cpuid = %d; ", PCPU_GET(cpuid)); 772 printf("apic id = %02x\n", PCPU_GET(apic_id)); 773 #endif 774 if (type == T_PAGEFLT) { 775 printf("fault virtual address = 0x%x\n", eva); 776 printf("fault code = %s %s, %s\n", 777 code & PGEX_U ? "user" : "supervisor", 778 code & PGEX_W ? "write" : "read", 779 code & PGEX_P ? "protection violation" : "page not present"); 780 } 781 printf("instruction pointer = 0x%x:0x%x\n", 782 frame->tf_cs & 0xffff, frame->tf_eip); 783 if ((ISPL(frame->tf_cs) == SEL_UPL) || (frame->tf_eflags & PSL_VM)) { 784 ss = frame->tf_ss & 0xffff; 785 esp = frame->tf_esp; 786 } else { 787 ss = GSEL(GDATA_SEL, SEL_KPL); 788 esp = (int)&frame->tf_esp; 789 } 790 printf("stack pointer = 0x%x:0x%x\n", ss, esp); 791 printf("frame pointer = 0x%x:0x%x\n", ss, frame->tf_ebp); 792 printf("code segment = base 0x%x, limit 0x%x, type 0x%x\n", 793 softseg.ssd_base, softseg.ssd_limit, softseg.ssd_type); 794 printf(" = DPL %d, pres %d, def32 %d, gran %d\n", 795 softseg.ssd_dpl, softseg.ssd_p, softseg.ssd_def32, 796 softseg.ssd_gran); 797 printf("processor eflags = "); 798 if (frame->tf_eflags & PSL_T) 799 printf("trace trap, "); 800 if (frame->tf_eflags & PSL_I) 801 printf("interrupt enabled, "); 802 if (frame->tf_eflags & PSL_NT) 803 printf("nested task, "); 804 if (frame->tf_eflags & PSL_RF) 805 printf("resume, "); 806 if (frame->tf_eflags & PSL_VM) 807 printf("vm86, "); 808 printf("IOPL = %d\n", (frame->tf_eflags & PSL_IOPL) >> 12); 809 printf("current process = "); 810 if (curproc) { 811 printf("%lu (%s)\n", 812 (u_long)curproc->p_pid, curproc->p_comm ? 813 curproc->p_comm : ""); 814 } else { 815 printf("Idle\n"); 816 } 817 818 #ifdef KDB 819 if (debugger_on_panic || kdb_active) { 820 register_t eflags; 821 eflags = intr_disable(); 822 if (kdb_trap(type, 0, frame)) { 823 intr_restore(eflags); 824 return; 825 } 826 intr_restore(eflags); 827 } 828 #endif 829 printf("trap number = %d\n", type); 830 if (type <= MAX_TRAP_MSG) 831 panic("%s", trap_msg[type]); 832 else 833 panic("unknown/reserved trap"); 834 } 835 836 /* 837 * Double fault handler. Called when a fault occurs while writing 838 * a frame for a trap/exception onto the stack. This usually occurs 839 * when the stack overflows (such is the case with infinite recursion, 840 * for example). 841 * 842 * XXX Note that the current PTD gets replaced by IdlePTD when the 843 * task switch occurs. This means that the stack that was active at 844 * the time of the double fault is not available at <kstack> unless 845 * the machine was idle when the double fault occurred. The downside 846 * of this is that "trace <ebp>" in ddb won't work. 847 */ 848 void 849 dblfault_handler() 850 { 851 printf("\nFatal double fault:\n"); 852 printf("eip = 0x%x\n", PCPU_GET(common_tss.tss_eip)); 853 printf("esp = 0x%x\n", PCPU_GET(common_tss.tss_esp)); 854 printf("ebp = 0x%x\n", PCPU_GET(common_tss.tss_ebp)); 855 #ifdef SMP 856 /* two separate prints in case of a trap on an unmapped page */ 857 printf("cpuid = %d; ", PCPU_GET(cpuid)); 858 printf("apic id = %02x\n", PCPU_GET(apic_id)); 859 #endif 860 panic("double fault"); 861 } 862 863 /* 864 * syscall - system call request C handler 865 * 866 * A system call is essentially treated as a trap. 867 */ 868 void 869 syscall(frame) 870 struct trapframe frame; 871 { 872 caddr_t params; 873 struct sysent *callp; 874 struct thread *td = curthread; 875 struct proc *p = td->td_proc; 876 register_t orig_tf_eflags; 877 u_int sticks; 878 int error; 879 int narg; 880 int args[8]; 881 u_int code; 882 883 /* 884 * note: PCPU_LAZY_INC() can only be used if we can afford 885 * occassional inaccuracy in the count. 886 */ 887 PCPU_LAZY_INC(cnt.v_syscall); 888 889 #ifdef DIAGNOSTIC 890 if (ISPL(frame.tf_cs) != SEL_UPL) { 891 mtx_lock(&Giant); /* try to stabilize the system XXX */ 892 panic("syscall"); 893 /* NOT REACHED */ 894 mtx_unlock(&Giant); 895 } 896 #endif 897 898 sticks = td->td_sticks; 899 td->td_frame = &frame; 900 if (td->td_ucred != p->p_ucred) 901 cred_update_thread(td); 902 if (p->p_flag & P_SA) 903 thread_user_enter(td); 904 params = (caddr_t)frame.tf_esp + sizeof(int); 905 code = frame.tf_eax; 906 orig_tf_eflags = frame.tf_eflags; 907 908 if (p->p_sysent->sv_prepsyscall) { 909 /* 910 * The prep code is MP aware. 911 */ 912 (*p->p_sysent->sv_prepsyscall)(&frame, args, &code, ¶ms); 913 } else { 914 /* 915 * Need to check if this is a 32 bit or 64 bit syscall. 916 * fuword is MP aware. 917 */ 918 if (code == SYS_syscall) { 919 /* 920 * Code is first argument, followed by actual args. 921 */ 922 code = fuword(params); 923 params += sizeof(int); 924 } else if (code == SYS___syscall) { 925 /* 926 * Like syscall, but code is a quad, so as to maintain 927 * quad alignment for the rest of the arguments. 928 */ 929 code = fuword(params); 930 params += sizeof(quad_t); 931 } 932 } 933 934 if (p->p_sysent->sv_mask) 935 code &= p->p_sysent->sv_mask; 936 937 if (code >= p->p_sysent->sv_size) 938 callp = &p->p_sysent->sv_table[0]; 939 else 940 callp = &p->p_sysent->sv_table[code]; 941 942 narg = callp->sy_narg & SYF_ARGMASK; 943 944 /* 945 * copyin and the ktrsyscall()/ktrsysret() code is MP-aware 946 */ 947 if (params != NULL && narg != 0) 948 error = copyin(params, (caddr_t)args, 949 (u_int)(narg * sizeof(int))); 950 else 951 error = 0; 952 953 #ifdef KTRACE 954 if (KTRPOINT(td, KTR_SYSCALL)) 955 ktrsyscall(code, narg, args); 956 #endif 957 958 CTR4(KTR_SYSC, "syscall enter thread %p pid %d proc %s code %d", td, 959 td->td_proc->p_pid, td->td_proc->p_comm, code); 960 961 /* 962 * Try to run the syscall without Giant if the syscall 963 * is MP safe. 964 */ 965 if ((callp->sy_narg & SYF_MPSAFE) == 0) 966 mtx_lock(&Giant); 967 968 if (error == 0) { 969 td->td_retval[0] = 0; 970 td->td_retval[1] = frame.tf_edx; 971 972 STOPEVENT(p, S_SCE, narg); 973 974 PTRACESTOP_SC(p, td, S_PT_SCE); 975 976 error = (*callp->sy_call)(td, args); 977 } 978 979 switch (error) { 980 case 0: 981 frame.tf_eax = td->td_retval[0]; 982 frame.tf_edx = td->td_retval[1]; 983 frame.tf_eflags &= ~PSL_C; 984 break; 985 986 case ERESTART: 987 /* 988 * Reconstruct pc, assuming lcall $X,y is 7 bytes, 989 * int 0x80 is 2 bytes. We saved this in tf_err. 990 */ 991 frame.tf_eip -= frame.tf_err; 992 break; 993 994 case EJUSTRETURN: 995 break; 996 997 default: 998 if (p->p_sysent->sv_errsize) { 999 if (error >= p->p_sysent->sv_errsize) 1000 error = -1; /* XXX */ 1001 else 1002 error = p->p_sysent->sv_errtbl[error]; 1003 } 1004 frame.tf_eax = error; 1005 frame.tf_eflags |= PSL_C; 1006 break; 1007 } 1008 1009 /* 1010 * Release Giant if we previously set it. 1011 */ 1012 if ((callp->sy_narg & SYF_MPSAFE) == 0) 1013 mtx_unlock(&Giant); 1014 1015 /* 1016 * Traced syscall. 1017 */ 1018 if ((orig_tf_eflags & PSL_T) && !(orig_tf_eflags & PSL_VM)) { 1019 frame.tf_eflags &= ~PSL_T; 1020 trapsignal(td, SIGTRAP, 0); 1021 } 1022 1023 /* 1024 * Handle reschedule and other end-of-syscall issues 1025 */ 1026 userret(td, &frame, sticks); 1027 1028 CTR4(KTR_SYSC, "syscall exit thread %p pid %d proc %s code %d", td, 1029 td->td_proc->p_pid, td->td_proc->p_comm, code); 1030 1031 #ifdef KTRACE 1032 if (KTRPOINT(td, KTR_SYSRET)) 1033 ktrsysret(code, error, td->td_retval[0]); 1034 #endif 1035 1036 /* 1037 * This works because errno is findable through the 1038 * register set. If we ever support an emulation where this 1039 * is not the case, this code will need to be revisited. 1040 */ 1041 STOPEVENT(p, S_SCX, code); 1042 1043 PTRACESTOP_SC(p, td, S_PT_SCX); 1044 1045 WITNESS_WARN(WARN_PANIC, NULL, "System call %s returning", 1046 (code >= 0 && code < SYS_MAXSYSCALL) ? syscallnames[code] : "???"); 1047 mtx_assert(&sched_lock, MA_NOTOWNED); 1048 mtx_assert(&Giant, MA_NOTOWNED); 1049 } 1050
Cache object: 315373f2eeb15df086180b02e141bd16
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