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/5.3/sys/i386/i386/trap.c 134685 2004-09-03 06:40:26Z julian $"); 42 43 /* 44 * 386 Trap and System call handling 45 */ 46 47 #include "opt_clock.h" 48 #include "opt_cpu.h" 49 #include "opt_isa.h" 50 #include "opt_ktrace.h" 51 #include "opt_npx.h" 52 #include "opt_trap.h" 53 54 #include <sys/param.h> 55 #include <sys/bus.h> 56 #include <sys/systm.h> 57 #include <sys/proc.h> 58 #include <sys/pioctl.h> 59 #include <sys/ptrace.h> 60 #include <sys/kdb.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 extern void trap(struct trapframe frame); 100 #ifdef I386_CPU 101 extern int trapwrite(unsigned addr); 102 #endif 103 extern void syscall(struct trapframe frame); 104 105 static int trap_pfault(struct trapframe *, int, vm_offset_t); 106 static void trap_fatal(struct trapframe *, vm_offset_t); 107 void dblfault_handler(void); 108 109 extern inthand_t IDTVEC(lcall_syscall); 110 111 #define MAX_TRAP_MSG 28 112 static char *trap_msg[] = { 113 "", /* 0 unused */ 114 "privileged instruction fault", /* 1 T_PRIVINFLT */ 115 "", /* 2 unused */ 116 "breakpoint instruction fault", /* 3 T_BPTFLT */ 117 "", /* 4 unused */ 118 "", /* 5 unused */ 119 "arithmetic trap", /* 6 T_ARITHTRAP */ 120 "", /* 7 unused */ 121 "", /* 8 unused */ 122 "general protection fault", /* 9 T_PROTFLT */ 123 "trace trap", /* 10 T_TRCTRAP */ 124 "", /* 11 unused */ 125 "page fault", /* 12 T_PAGEFLT */ 126 "", /* 13 unused */ 127 "alignment fault", /* 14 T_ALIGNFLT */ 128 "", /* 15 unused */ 129 "", /* 16 unused */ 130 "", /* 17 unused */ 131 "integer divide fault", /* 18 T_DIVIDE */ 132 "non-maskable interrupt trap", /* 19 T_NMI */ 133 "overflow trap", /* 20 T_OFLOW */ 134 "FPU bounds check fault", /* 21 T_BOUND */ 135 "FPU device not available", /* 22 T_DNA */ 136 "double fault", /* 23 T_DOUBLEFLT */ 137 "FPU operand fetch fault", /* 24 T_FPOPFLT */ 138 "invalid TSS fault", /* 25 T_TSSFLT */ 139 "segment not present fault", /* 26 T_SEGNPFLT */ 140 "stack fault", /* 27 T_STKFLT */ 141 "machine check trap", /* 28 T_MCHK */ 142 }; 143 144 #if defined(I586_CPU) && !defined(NO_F00F_HACK) 145 extern int has_f00f_bug; 146 #endif 147 148 #ifdef KDB 149 static int kdb_on_nmi = 1; 150 SYSCTL_INT(_machdep, OID_AUTO, kdb_on_nmi, CTLFLAG_RW, 151 &kdb_on_nmi, 0, "Go to KDB on NMI"); 152 #endif 153 static int panic_on_nmi = 1; 154 SYSCTL_INT(_machdep, OID_AUTO, panic_on_nmi, CTLFLAG_RW, 155 &panic_on_nmi, 0, "Panic on NMI"); 156 157 #ifdef WITNESS 158 extern char *syscallnames[]; 159 #endif 160 161 #ifdef DEVICE_POLLING 162 extern u_int32_t poll_in_trap; 163 extern int ether_poll(int count); 164 #endif /* DEVICE_POLLING */ 165 166 /* 167 * Exception, fault, and trap interface to the FreeBSD kernel. 168 * This common code is called from assembly language IDT gate entry 169 * routines that prepare a suitable stack frame, and restore this 170 * frame after the exception has been processed. 171 */ 172 173 void 174 trap(frame) 175 struct trapframe frame; 176 { 177 struct thread *td = curthread; 178 struct proc *p = td->td_proc; 179 u_int sticks = 0; 180 int i = 0, ucode = 0, type, code; 181 vm_offset_t eva; 182 #ifdef POWERFAIL_NMI 183 static int lastalert = 0; 184 #endif 185 186 atomic_add_int(&cnt.v_trap, 1); 187 type = frame.tf_trapno; 188 189 #ifdef KDB 190 if (kdb_active) { 191 kdb_reenter(); 192 goto out; 193 } 194 #endif 195 196 if ((frame.tf_eflags & PSL_I) == 0) { 197 /* 198 * Buggy application or kernel code has disabled 199 * interrupts and then trapped. Enabling interrupts 200 * now is wrong, but it is better than running with 201 * interrupts disabled until they are accidentally 202 * enabled later. 203 */ 204 if (ISPL(frame.tf_cs) == SEL_UPL || (frame.tf_eflags & PSL_VM)) 205 printf( 206 "pid %ld (%s): trap %d with interrupts disabled\n", 207 (long)curproc->p_pid, curproc->p_comm, type); 208 else if (type != T_BPTFLT && type != T_TRCTRAP && 209 frame.tf_eip != (int)cpu_switch_load_gs) { 210 /* 211 * XXX not quite right, since this may be for a 212 * multiple fault in user mode. 213 */ 214 printf("kernel trap %d with interrupts disabled\n", 215 type); 216 /* 217 * Page faults need interrupts diasabled until later, 218 * and we shouldn't enable interrupts while in a 219 * critical section. 220 */ 221 if (type != T_PAGEFLT && td->td_critnest == 0) 222 enable_intr(); 223 } 224 } 225 226 eva = 0; 227 code = frame.tf_err; 228 if (type == T_PAGEFLT) { 229 /* 230 * For some Cyrix CPUs, %cr2 is clobbered by 231 * interrupts. This problem is worked around by using 232 * an interrupt gate for the pagefault handler. We 233 * are finally ready to read %cr2 and then must 234 * reenable interrupts. 235 * 236 * If we get a page fault while in a critical section, then 237 * it is most likely a fatal kernel page fault. The kernel 238 * is already going to panic trying to get a sleep lock to 239 * do the VM lookup, so just consider it a fatal trap so the 240 * kernel can print out a useful trap message and even get 241 * to the debugger. 242 */ 243 eva = rcr2(); 244 if (td->td_critnest == 0) 245 enable_intr(); 246 else 247 trap_fatal(&frame, eva); 248 } 249 250 #ifdef DEVICE_POLLING 251 if (poll_in_trap) 252 ether_poll(poll_in_trap); 253 #endif /* DEVICE_POLLING */ 254 255 if ((ISPL(frame.tf_cs) == SEL_UPL) || 256 ((frame.tf_eflags & PSL_VM) && 257 !(PCPU_GET(curpcb)->pcb_flags & PCB_VM86CALL))) { 258 /* user trap */ 259 260 sticks = td->td_sticks; 261 td->td_frame = &frame; 262 if (td->td_ucred != p->p_ucred) 263 cred_update_thread(td); 264 265 switch (type) { 266 case T_PRIVINFLT: /* privileged instruction fault */ 267 ucode = type; 268 i = SIGILL; 269 break; 270 271 case T_BPTFLT: /* bpt instruction fault */ 272 case T_TRCTRAP: /* trace trap */ 273 enable_intr(); 274 frame.tf_eflags &= ~PSL_T; 275 i = SIGTRAP; 276 break; 277 278 case T_ARITHTRAP: /* arithmetic trap */ 279 #ifdef DEV_NPX 280 ucode = npxtrap(); 281 if (ucode == -1) 282 goto userout; 283 #else 284 ucode = code; 285 #endif 286 i = SIGFPE; 287 break; 288 289 /* 290 * The following two traps can happen in 291 * vm86 mode, and, if so, we want to handle 292 * them specially. 293 */ 294 case T_PROTFLT: /* general protection fault */ 295 case T_STKFLT: /* stack fault */ 296 if (frame.tf_eflags & PSL_VM) { 297 i = vm86_emulate((struct vm86frame *)&frame); 298 if (i == 0) 299 goto user; 300 break; 301 } 302 /* FALLTHROUGH */ 303 304 case T_SEGNPFLT: /* segment not present fault */ 305 case T_TSSFLT: /* invalid TSS fault */ 306 case T_DOUBLEFLT: /* double fault */ 307 default: 308 ucode = code + BUS_SEGM_FAULT ; 309 i = SIGBUS; 310 break; 311 312 case T_PAGEFLT: /* page fault */ 313 if (td->td_pflags & TDP_SA) 314 thread_user_enter(td); 315 316 i = trap_pfault(&frame, TRUE, eva); 317 #if defined(I586_CPU) && !defined(NO_F00F_HACK) 318 if (i == -2) { 319 /* 320 * The f00f hack workaround has triggered, so 321 * treat the fault as an illegal instruction 322 * (T_PRIVINFLT) instead of a page fault. 323 */ 324 type = frame.tf_trapno = T_PRIVINFLT; 325 326 /* Proceed as in that case. */ 327 ucode = type; 328 i = SIGILL; 329 break; 330 } 331 #endif 332 if (i == -1) 333 goto userout; 334 if (i == 0) 335 goto user; 336 337 ucode = T_PAGEFLT; 338 break; 339 340 case T_DIVIDE: /* integer divide fault */ 341 ucode = FPE_INTDIV; 342 i = SIGFPE; 343 break; 344 345 #ifdef DEV_ISA 346 case T_NMI: 347 #ifdef POWERFAIL_NMI 348 #ifndef TIMER_FREQ 349 # define TIMER_FREQ 1193182 350 #endif 351 mtx_lock(&Giant); 352 if (time_second - lastalert > 10) { 353 log(LOG_WARNING, "NMI: power fail\n"); 354 sysbeep(TIMER_FREQ/880, hz); 355 lastalert = time_second; 356 } 357 mtx_unlock(&Giant); 358 goto userout; 359 #else /* !POWERFAIL_NMI */ 360 /* machine/parity/power fail/"kitchen sink" faults */ 361 /* XXX Giant */ 362 if (isa_nmi(code) == 0) { 363 #ifdef KDB 364 /* 365 * NMI can be hooked up to a pushbutton 366 * for debugging. 367 */ 368 if (kdb_on_nmi) { 369 printf ("NMI ... going to debugger\n"); 370 kdb_trap(type, 0, &frame); 371 } 372 #endif /* KDB */ 373 goto userout; 374 } else if (panic_on_nmi) 375 panic("NMI indicates hardware failure"); 376 break; 377 #endif /* POWERFAIL_NMI */ 378 #endif /* DEV_ISA */ 379 380 case T_OFLOW: /* integer overflow fault */ 381 ucode = FPE_INTOVF; 382 i = SIGFPE; 383 break; 384 385 case T_BOUND: /* bounds check fault */ 386 ucode = FPE_FLTSUB; 387 i = SIGFPE; 388 break; 389 390 case T_DNA: 391 #ifdef DEV_NPX 392 /* transparent fault (due to context switch "late") */ 393 if (npxdna()) 394 goto userout; 395 #endif 396 i = SIGFPE; 397 ucode = FPE_FPU_NP_TRAP; 398 break; 399 400 case T_FPOPFLT: /* FPU operand fetch fault */ 401 ucode = T_FPOPFLT; 402 i = SIGILL; 403 break; 404 405 case T_XMMFLT: /* SIMD floating-point exception */ 406 ucode = 0; /* XXX */ 407 i = SIGFPE; 408 break; 409 } 410 } else { 411 /* kernel trap */ 412 413 KASSERT(cold || td->td_ucred != NULL, 414 ("kernel trap doesn't have ucred")); 415 switch (type) { 416 case T_PAGEFLT: /* page fault */ 417 (void) trap_pfault(&frame, FALSE, eva); 418 goto out; 419 420 case T_DNA: 421 #ifdef DEV_NPX 422 /* 423 * The kernel is apparently using npx for copying. 424 * XXX this should be fatal unless the kernel has 425 * registered such use. 426 */ 427 if (npxdna()) 428 goto out; 429 #endif 430 break; 431 432 /* 433 * The following two traps can happen in 434 * vm86 mode, and, if so, we want to handle 435 * them specially. 436 */ 437 case T_PROTFLT: /* general protection fault */ 438 case T_STKFLT: /* stack fault */ 439 if (frame.tf_eflags & PSL_VM) { 440 i = vm86_emulate((struct vm86frame *)&frame); 441 if (i != 0) 442 /* 443 * returns to original process 444 */ 445 vm86_trap((struct vm86frame *)&frame); 446 goto out; 447 } 448 if (type == T_STKFLT) 449 break; 450 451 /* FALL THROUGH */ 452 453 case T_SEGNPFLT: /* segment not present fault */ 454 if (PCPU_GET(curpcb)->pcb_flags & PCB_VM86CALL) 455 break; 456 457 /* 458 * Invalid %fs's and %gs's can be created using 459 * procfs or PT_SETREGS or by invalidating the 460 * underlying LDT entry. This causes a fault 461 * in kernel mode when the kernel attempts to 462 * switch contexts. Lose the bad context 463 * (XXX) so that we can continue, and generate 464 * a signal. 465 */ 466 if (frame.tf_eip == (int)cpu_switch_load_gs) { 467 PCPU_GET(curpcb)->pcb_gs = 0; 468 #if 0 469 PROC_LOCK(p); 470 psignal(p, SIGBUS); 471 PROC_UNLOCK(p); 472 #endif 473 goto out; 474 } 475 476 if (td->td_intr_nesting_level != 0) 477 break; 478 479 /* 480 * Invalid segment selectors and out of bounds 481 * %eip's and %esp's can be set up in user mode. 482 * This causes a fault in kernel mode when the 483 * kernel tries to return to user mode. We want 484 * to get this fault so that we can fix the 485 * problem here and not have to check all the 486 * selectors and pointers when the user changes 487 * them. 488 */ 489 if (frame.tf_eip == (int)doreti_iret) { 490 frame.tf_eip = (int)doreti_iret_fault; 491 goto out; 492 } 493 if (frame.tf_eip == (int)doreti_popl_ds) { 494 frame.tf_eip = (int)doreti_popl_ds_fault; 495 goto out; 496 } 497 if (frame.tf_eip == (int)doreti_popl_es) { 498 frame.tf_eip = (int)doreti_popl_es_fault; 499 goto out; 500 } 501 if (frame.tf_eip == (int)doreti_popl_fs) { 502 frame.tf_eip = (int)doreti_popl_fs_fault; 503 goto out; 504 } 505 if (PCPU_GET(curpcb)->pcb_onfault != NULL) { 506 frame.tf_eip = 507 (int)PCPU_GET(curpcb)->pcb_onfault; 508 goto out; 509 } 510 break; 511 512 case T_TSSFLT: 513 /* 514 * PSL_NT can be set in user mode and isn't cleared 515 * automatically when the kernel is entered. This 516 * causes a TSS fault when the kernel attempts to 517 * `iret' because the TSS link is uninitialized. We 518 * want to get this fault so that we can fix the 519 * problem here and not every time the kernel is 520 * entered. 521 */ 522 if (frame.tf_eflags & PSL_NT) { 523 frame.tf_eflags &= ~PSL_NT; 524 goto out; 525 } 526 break; 527 528 case T_TRCTRAP: /* trace trap */ 529 if (frame.tf_eip == (int)IDTVEC(lcall_syscall)) { 530 /* 531 * We've just entered system mode via the 532 * syscall lcall. Continue single stepping 533 * silently until the syscall handler has 534 * saved the flags. 535 */ 536 goto out; 537 } 538 if (frame.tf_eip == (int)IDTVEC(lcall_syscall) + 1) { 539 /* 540 * The syscall handler has now saved the 541 * flags. Stop single stepping it. 542 */ 543 frame.tf_eflags &= ~PSL_T; 544 goto out; 545 } 546 /* 547 * Ignore debug register trace traps due to 548 * accesses in the user's address space, which 549 * can happen under several conditions such as 550 * if a user sets a watchpoint on a buffer and 551 * then passes that buffer to a system call. 552 * We still want to get TRCTRAPS for addresses 553 * in kernel space because that is useful when 554 * debugging the kernel. 555 */ 556 /* XXX Giant */ 557 if (user_dbreg_trap() && 558 !(PCPU_GET(curpcb)->pcb_flags & PCB_VM86CALL)) { 559 /* 560 * Reset breakpoint bits because the 561 * processor doesn't 562 */ 563 load_dr6(rdr6() & 0xfffffff0); 564 goto out; 565 } 566 /* 567 * FALLTHROUGH (TRCTRAP kernel mode, kernel address) 568 */ 569 case T_BPTFLT: 570 /* 571 * If KDB is enabled, let it handle the debugger trap. 572 * Otherwise, debugger traps "can't happen". 573 */ 574 #ifdef KDB 575 /* XXX Giant */ 576 if (kdb_trap(type, 0, &frame)) 577 goto out; 578 #endif 579 break; 580 581 #ifdef DEV_ISA 582 case T_NMI: 583 #ifdef POWERFAIL_NMI 584 mtx_lock(&Giant); 585 if (time_second - lastalert > 10) { 586 log(LOG_WARNING, "NMI: power fail\n"); 587 sysbeep(TIMER_FREQ/880, hz); 588 lastalert = time_second; 589 } 590 mtx_unlock(&Giant); 591 goto out; 592 #else /* !POWERFAIL_NMI */ 593 /* XXX Giant */ 594 /* machine/parity/power fail/"kitchen sink" faults */ 595 if (isa_nmi(code) == 0) { 596 #ifdef KDB 597 /* 598 * NMI can be hooked up to a pushbutton 599 * for debugging. 600 */ 601 if (kdb_on_nmi) { 602 printf ("NMI ... going to debugger\n"); 603 kdb_trap(type, 0, &frame); 604 } 605 #endif /* KDB */ 606 goto out; 607 } else if (panic_on_nmi == 0) 608 goto out; 609 /* FALLTHROUGH */ 610 #endif /* POWERFAIL_NMI */ 611 #endif /* DEV_ISA */ 612 } 613 614 trap_fatal(&frame, eva); 615 goto out; 616 } 617 618 /* Translate fault for emulators (e.g. Linux) */ 619 if (*p->p_sysent->sv_transtrap) 620 i = (*p->p_sysent->sv_transtrap)(i, type); 621 622 trapsignal(td, i, ucode); 623 624 #ifdef DEBUG 625 if (type <= MAX_TRAP_MSG) { 626 uprintf("fatal process exception: %s", 627 trap_msg[type]); 628 if ((type == T_PAGEFLT) || (type == T_PROTFLT)) 629 uprintf(", fault VA = 0x%lx", (u_long)eva); 630 uprintf("\n"); 631 } 632 #endif 633 634 user: 635 userret(td, &frame, sticks); 636 mtx_assert(&Giant, MA_NOTOWNED); 637 userout: 638 out: 639 return; 640 } 641 642 static int 643 trap_pfault(frame, usermode, eva) 644 struct trapframe *frame; 645 int usermode; 646 vm_offset_t eva; 647 { 648 vm_offset_t va; 649 struct vmspace *vm = NULL; 650 vm_map_t map = 0; 651 int rv = 0; 652 vm_prot_t ftype; 653 struct thread *td = curthread; 654 struct proc *p = td->td_proc; 655 656 va = trunc_page(eva); 657 if (va >= KERNBASE) { 658 /* 659 * Don't allow user-mode faults in kernel address space. 660 * An exception: if the faulting address is the invalid 661 * instruction entry in the IDT, then the Intel Pentium 662 * F00F bug workaround was triggered, and we need to 663 * treat it is as an illegal instruction, and not a page 664 * fault. 665 */ 666 #if defined(I586_CPU) && !defined(NO_F00F_HACK) 667 if ((eva == (unsigned int)&idt[6]) && has_f00f_bug) 668 return -2; 669 #endif 670 if (usermode) 671 goto nogo; 672 673 map = kernel_map; 674 } else { 675 /* 676 * This is a fault on non-kernel virtual memory. 677 * vm is initialized above to NULL. If curproc is NULL 678 * or curproc->p_vmspace is NULL the fault is fatal. 679 */ 680 if (p != NULL) 681 vm = p->p_vmspace; 682 683 if (vm == NULL) 684 goto nogo; 685 686 map = &vm->vm_map; 687 } 688 689 if (frame->tf_err & PGEX_W) 690 ftype = VM_PROT_WRITE; 691 else 692 ftype = VM_PROT_READ; 693 694 if (map != kernel_map) { 695 /* 696 * Keep swapout from messing with us during this 697 * critical time. 698 */ 699 PROC_LOCK(p); 700 ++p->p_lock; 701 PROC_UNLOCK(p); 702 703 /* Fault in the user page: */ 704 rv = vm_fault(map, va, ftype, 705 (ftype & VM_PROT_WRITE) ? VM_FAULT_DIRTY 706 : VM_FAULT_NORMAL); 707 708 PROC_LOCK(p); 709 --p->p_lock; 710 PROC_UNLOCK(p); 711 } else { 712 /* 713 * Don't have to worry about process locking or stacks in the 714 * kernel. 715 */ 716 rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL); 717 } 718 if (rv == KERN_SUCCESS) 719 return (0); 720 nogo: 721 if (!usermode) { 722 if (td->td_intr_nesting_level == 0 && 723 PCPU_GET(curpcb)->pcb_onfault != NULL) { 724 frame->tf_eip = (int)PCPU_GET(curpcb)->pcb_onfault; 725 return (0); 726 } 727 trap_fatal(frame, eva); 728 return (-1); 729 } 730 731 /* kludge to pass faulting virtual address to sendsig */ 732 frame->tf_err = eva; 733 734 return((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV); 735 } 736 737 static void 738 trap_fatal(frame, eva) 739 struct trapframe *frame; 740 vm_offset_t eva; 741 { 742 int code, type, ss, esp; 743 struct soft_segment_descriptor softseg; 744 745 code = frame->tf_err; 746 type = frame->tf_trapno; 747 sdtossd(&gdt[IDXSEL(frame->tf_cs & 0xffff)].sd, &softseg); 748 749 if (type <= MAX_TRAP_MSG) 750 printf("\n\nFatal trap %d: %s while in %s mode\n", 751 type, trap_msg[type], 752 frame->tf_eflags & PSL_VM ? "vm86" : 753 ISPL(frame->tf_cs) == SEL_UPL ? "user" : "kernel"); 754 #ifdef SMP 755 /* two separate prints in case of a trap on an unmapped page */ 756 printf("cpuid = %d; ", PCPU_GET(cpuid)); 757 printf("apic id = %02x\n", PCPU_GET(apic_id)); 758 #endif 759 if (type == T_PAGEFLT) { 760 printf("fault virtual address = 0x%x\n", eva); 761 printf("fault code = %s %s, %s\n", 762 code & PGEX_U ? "user" : "supervisor", 763 code & PGEX_W ? "write" : "read", 764 code & PGEX_P ? "protection violation" : "page not present"); 765 } 766 printf("instruction pointer = 0x%x:0x%x\n", 767 frame->tf_cs & 0xffff, frame->tf_eip); 768 if ((ISPL(frame->tf_cs) == SEL_UPL) || (frame->tf_eflags & PSL_VM)) { 769 ss = frame->tf_ss & 0xffff; 770 esp = frame->tf_esp; 771 } else { 772 ss = GSEL(GDATA_SEL, SEL_KPL); 773 esp = (int)&frame->tf_esp; 774 } 775 printf("stack pointer = 0x%x:0x%x\n", ss, esp); 776 printf("frame pointer = 0x%x:0x%x\n", ss, frame->tf_ebp); 777 printf("code segment = base 0x%x, limit 0x%x, type 0x%x\n", 778 softseg.ssd_base, softseg.ssd_limit, softseg.ssd_type); 779 printf(" = DPL %d, pres %d, def32 %d, gran %d\n", 780 softseg.ssd_dpl, softseg.ssd_p, softseg.ssd_def32, 781 softseg.ssd_gran); 782 printf("processor eflags = "); 783 if (frame->tf_eflags & PSL_T) 784 printf("trace trap, "); 785 if (frame->tf_eflags & PSL_I) 786 printf("interrupt enabled, "); 787 if (frame->tf_eflags & PSL_NT) 788 printf("nested task, "); 789 if (frame->tf_eflags & PSL_RF) 790 printf("resume, "); 791 if (frame->tf_eflags & PSL_VM) 792 printf("vm86, "); 793 printf("IOPL = %d\n", (frame->tf_eflags & PSL_IOPL) >> 12); 794 printf("current process = "); 795 if (curproc) { 796 printf("%lu (%s)\n", 797 (u_long)curproc->p_pid, curproc->p_comm ? 798 curproc->p_comm : ""); 799 } else { 800 printf("Idle\n"); 801 } 802 803 #ifdef KDB 804 if (kdb_trap(type, 0, frame)) 805 return; 806 #endif 807 printf("trap number = %d\n", type); 808 if (type <= MAX_TRAP_MSG) 809 panic("%s", trap_msg[type]); 810 else 811 panic("unknown/reserved trap"); 812 } 813 814 /* 815 * Double fault handler. Called when a fault occurs while writing 816 * a frame for a trap/exception onto the stack. This usually occurs 817 * when the stack overflows (such is the case with infinite recursion, 818 * for example). 819 * 820 * XXX Note that the current PTD gets replaced by IdlePTD when the 821 * task switch occurs. This means that the stack that was active at 822 * the time of the double fault is not available at <kstack> unless 823 * the machine was idle when the double fault occurred. The downside 824 * of this is that "trace <ebp>" in ddb won't work. 825 */ 826 void 827 dblfault_handler() 828 { 829 printf("\nFatal double fault:\n"); 830 printf("eip = 0x%x\n", PCPU_GET(common_tss.tss_eip)); 831 printf("esp = 0x%x\n", PCPU_GET(common_tss.tss_esp)); 832 printf("ebp = 0x%x\n", PCPU_GET(common_tss.tss_ebp)); 833 #ifdef SMP 834 /* two separate prints in case of a trap on an unmapped page */ 835 printf("cpuid = %d; ", PCPU_GET(cpuid)); 836 printf("apic id = %02x\n", PCPU_GET(apic_id)); 837 #endif 838 panic("double fault"); 839 } 840 841 #ifdef I386_CPU 842 /* 843 * Compensate for 386 brain damage (missing URKR). 844 * This is a little simpler than the pagefault handler in trap() because 845 * it the page tables have already been faulted in and high addresses 846 * are thrown out early for other reasons. 847 */ 848 int trapwrite(addr) 849 unsigned addr; 850 { 851 struct thread *td; 852 struct proc *p; 853 vm_offset_t va; 854 struct vmspace *vm; 855 int rv; 856 857 va = trunc_page((vm_offset_t)addr); 858 /* 859 * XXX - MAX is END. Changed > to >= for temp. fix. 860 */ 861 if (va >= VM_MAXUSER_ADDRESS) 862 return (1); 863 864 td = curthread; 865 p = td->td_proc; 866 vm = p->p_vmspace; 867 868 PROC_LOCK(p); 869 ++p->p_lock; 870 PROC_UNLOCK(p); 871 872 /* 873 * fault the data page 874 */ 875 rv = vm_fault(&vm->vm_map, va, VM_PROT_WRITE, VM_FAULT_DIRTY); 876 877 PROC_LOCK(p); 878 --p->p_lock; 879 PROC_UNLOCK(p); 880 881 if (rv != KERN_SUCCESS) 882 return 1; 883 884 return (0); 885 } 886 #endif 887 888 /* 889 * syscall - system call request C handler 890 * 891 * A system call is essentially treated as a trap. 892 */ 893 void 894 syscall(frame) 895 struct trapframe frame; 896 { 897 caddr_t params; 898 struct sysent *callp; 899 struct thread *td = curthread; 900 struct proc *p = td->td_proc; 901 register_t orig_tf_eflags; 902 u_int sticks; 903 int error; 904 int narg; 905 int args[8]; 906 u_int code; 907 908 /* 909 * note: PCPU_LAZY_INC() can only be used if we can afford 910 * occassional inaccuracy in the count. 911 */ 912 PCPU_LAZY_INC(cnt.v_syscall); 913 914 #ifdef DIAGNOSTIC 915 if (ISPL(frame.tf_cs) != SEL_UPL) { 916 mtx_lock(&Giant); /* try to stabilize the system XXX */ 917 panic("syscall"); 918 /* NOT REACHED */ 919 mtx_unlock(&Giant); 920 } 921 #endif 922 923 sticks = td->td_sticks; 924 td->td_frame = &frame; 925 if (td->td_ucred != p->p_ucred) 926 cred_update_thread(td); 927 if (p->p_flag & P_SA) 928 thread_user_enter(td); 929 params = (caddr_t)frame.tf_esp + sizeof(int); 930 code = frame.tf_eax; 931 orig_tf_eflags = frame.tf_eflags; 932 933 if (p->p_sysent->sv_prepsyscall) { 934 /* 935 * The prep code is MP aware. 936 */ 937 (*p->p_sysent->sv_prepsyscall)(&frame, args, &code, ¶ms); 938 } else { 939 /* 940 * Need to check if this is a 32 bit or 64 bit syscall. 941 * fuword is MP aware. 942 */ 943 if (code == SYS_syscall) { 944 /* 945 * Code is first argument, followed by actual args. 946 */ 947 code = fuword(params); 948 params += sizeof(int); 949 } else if (code == SYS___syscall) { 950 /* 951 * Like syscall, but code is a quad, so as to maintain 952 * quad alignment for the rest of the arguments. 953 */ 954 code = fuword(params); 955 params += sizeof(quad_t); 956 } 957 } 958 959 if (p->p_sysent->sv_mask) 960 code &= p->p_sysent->sv_mask; 961 962 if (code >= p->p_sysent->sv_size) 963 callp = &p->p_sysent->sv_table[0]; 964 else 965 callp = &p->p_sysent->sv_table[code]; 966 967 narg = callp->sy_narg & SYF_ARGMASK; 968 969 /* 970 * copyin and the ktrsyscall()/ktrsysret() code is MP-aware 971 */ 972 if (params != NULL && narg != 0) 973 error = copyin(params, (caddr_t)args, 974 (u_int)(narg * sizeof(int))); 975 else 976 error = 0; 977 978 #ifdef KTRACE 979 if (KTRPOINT(td, KTR_SYSCALL)) 980 ktrsyscall(code, narg, args); 981 #endif 982 983 CTR4(KTR_SYSC, "syscall enter thread %p pid %d proc %s code %d", td, 984 td->td_proc->p_pid, td->td_proc->p_comm, code); 985 986 /* 987 * Try to run the syscall without Giant if the syscall 988 * is MP safe. 989 */ 990 if ((callp->sy_narg & SYF_MPSAFE) == 0) 991 mtx_lock(&Giant); 992 993 if (error == 0) { 994 td->td_retval[0] = 0; 995 td->td_retval[1] = frame.tf_edx; 996 997 STOPEVENT(p, S_SCE, narg); 998 999 PTRACESTOP_SC(p, td, S_PT_SCE); 1000 1001 error = (*callp->sy_call)(td, args); 1002 } 1003 1004 switch (error) { 1005 case 0: 1006 frame.tf_eax = td->td_retval[0]; 1007 frame.tf_edx = td->td_retval[1]; 1008 frame.tf_eflags &= ~PSL_C; 1009 break; 1010 1011 case ERESTART: 1012 /* 1013 * Reconstruct pc, assuming lcall $X,y is 7 bytes, 1014 * int 0x80 is 2 bytes. We saved this in tf_err. 1015 */ 1016 frame.tf_eip -= frame.tf_err; 1017 break; 1018 1019 case EJUSTRETURN: 1020 break; 1021 1022 default: 1023 if (p->p_sysent->sv_errsize) { 1024 if (error >= p->p_sysent->sv_errsize) 1025 error = -1; /* XXX */ 1026 else 1027 error = p->p_sysent->sv_errtbl[error]; 1028 } 1029 frame.tf_eax = error; 1030 frame.tf_eflags |= PSL_C; 1031 break; 1032 } 1033 1034 /* 1035 * Release Giant if we previously set it. 1036 */ 1037 if ((callp->sy_narg & SYF_MPSAFE) == 0) 1038 mtx_unlock(&Giant); 1039 1040 /* 1041 * Traced syscall. 1042 */ 1043 if ((orig_tf_eflags & PSL_T) && !(orig_tf_eflags & PSL_VM)) { 1044 frame.tf_eflags &= ~PSL_T; 1045 trapsignal(td, SIGTRAP, 0); 1046 } 1047 1048 /* 1049 * Handle reschedule and other end-of-syscall issues 1050 */ 1051 userret(td, &frame, sticks); 1052 1053 CTR4(KTR_SYSC, "syscall exit thread %p pid %d proc %s code %d", td, 1054 td->td_proc->p_pid, td->td_proc->p_comm, code); 1055 1056 #ifdef KTRACE 1057 if (KTRPOINT(td, KTR_SYSRET)) 1058 ktrsysret(code, error, td->td_retval[0]); 1059 #endif 1060 1061 /* 1062 * This works because errno is findable through the 1063 * register set. If we ever support an emulation where this 1064 * is not the case, this code will need to be revisited. 1065 */ 1066 STOPEVENT(p, S_SCX, code); 1067 1068 PTRACESTOP_SC(p, td, S_PT_SCX); 1069 1070 WITNESS_WARN(WARN_PANIC, NULL, "System call %s returning", 1071 (code >= 0 && code < SYS_MAXSYSCALL) ? syscallnames[code] : "???"); 1072 mtx_assert(&sched_lock, MA_NOTOWNED); 1073 mtx_assert(&Giant, MA_NOTOWNED); 1074 } 1075
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