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 * $FreeBSD: releng/5.1/sys/i386/i386/trap.c 115184 2003-05-20 20:50:33Z jhb $ 39 */ 40 41 /* 42 * 386 Trap and System call handling 43 */ 44 45 #include "opt_clock.h" 46 #include "opt_cpu.h" 47 #include "opt_ddb.h" 48 #include "opt_isa.h" 49 #include "opt_ktrace.h" 50 #include "opt_npx.h" 51 #include "opt_trap.h" 52 53 #include <sys/param.h> 54 #include <sys/bus.h> 55 #include <sys/systm.h> 56 #include <sys/proc.h> 57 #include <sys/pioctl.h> 58 #include <sys/kernel.h> 59 #include <sys/ktr.h> 60 #include <sys/lock.h> 61 #include <sys/mutex.h> 62 #include <sys/resourcevar.h> 63 #include <sys/signalvar.h> 64 #include <sys/syscall.h> 65 #include <sys/sysctl.h> 66 #include <sys/sysent.h> 67 #include <sys/uio.h> 68 #include <sys/vmmeter.h> 69 #ifdef KTRACE 70 #include <sys/ktrace.h> 71 #endif 72 73 #include <vm/vm.h> 74 #include <vm/vm_param.h> 75 #include <vm/pmap.h> 76 #include <vm/vm_kern.h> 77 #include <vm/vm_map.h> 78 #include <vm/vm_page.h> 79 #include <vm/vm_extern.h> 80 81 #include <machine/cpu.h> 82 #include <machine/md_var.h> 83 #include <machine/pcb.h> 84 #ifdef SMP 85 #include <machine/smp.h> 86 #endif 87 #include <machine/tss.h> 88 89 #include <i386/isa/icu.h> 90 #include <i386/isa/intr_machdep.h> 91 92 #ifdef POWERFAIL_NMI 93 #include <sys/syslog.h> 94 #include <machine/clock.h> 95 #endif 96 97 #include <machine/vm86.h> 98 99 #include <ddb/ddb.h> 100 101 #include <sys/sysctl.h> 102 103 int (*pmath_emulate)(struct trapframe *); 104 105 extern void trap(struct trapframe frame); 106 #ifdef I386_CPU 107 extern int trapwrite(unsigned addr); 108 #endif 109 extern void syscall(struct trapframe frame); 110 111 static int trap_pfault(struct trapframe *, int, vm_offset_t); 112 static void trap_fatal(struct trapframe *, vm_offset_t); 113 void dblfault_handler(void); 114 115 extern inthand_t IDTVEC(lcall_syscall); 116 117 #define MAX_TRAP_MSG 28 118 static char *trap_msg[] = { 119 "", /* 0 unused */ 120 "privileged instruction fault", /* 1 T_PRIVINFLT */ 121 "", /* 2 unused */ 122 "breakpoint instruction fault", /* 3 T_BPTFLT */ 123 "", /* 4 unused */ 124 "", /* 5 unused */ 125 "arithmetic trap", /* 6 T_ARITHTRAP */ 126 "", /* 7 unused */ 127 "", /* 8 unused */ 128 "general protection fault", /* 9 T_PROTFLT */ 129 "trace trap", /* 10 T_TRCTRAP */ 130 "", /* 11 unused */ 131 "page fault", /* 12 T_PAGEFLT */ 132 "", /* 13 unused */ 133 "alignment fault", /* 14 T_ALIGNFLT */ 134 "", /* 15 unused */ 135 "", /* 16 unused */ 136 "", /* 17 unused */ 137 "integer divide fault", /* 18 T_DIVIDE */ 138 "non-maskable interrupt trap", /* 19 T_NMI */ 139 "overflow trap", /* 20 T_OFLOW */ 140 "FPU bounds check fault", /* 21 T_BOUND */ 141 "FPU device not available", /* 22 T_DNA */ 142 "double fault", /* 23 T_DOUBLEFLT */ 143 "FPU operand fetch fault", /* 24 T_FPOPFLT */ 144 "invalid TSS fault", /* 25 T_TSSFLT */ 145 "segment not present fault", /* 26 T_SEGNPFLT */ 146 "stack fault", /* 27 T_STKFLT */ 147 "machine check trap", /* 28 T_MCHK */ 148 }; 149 150 #if defined(I586_CPU) && !defined(NO_F00F_HACK) 151 extern int has_f00f_bug; 152 #endif 153 154 #ifdef DDB 155 static int ddb_on_nmi = 1; 156 SYSCTL_INT(_machdep, OID_AUTO, ddb_on_nmi, CTLFLAG_RW, 157 &ddb_on_nmi, 0, "Go to DDB on NMI"); 158 #endif 159 static int panic_on_nmi = 1; 160 SYSCTL_INT(_machdep, OID_AUTO, panic_on_nmi, CTLFLAG_RW, 161 &panic_on_nmi, 0, "Panic on NMI"); 162 163 #ifdef WITNESS 164 extern char *syscallnames[]; 165 #endif 166 167 #ifdef DEVICE_POLLING 168 extern u_int32_t poll_in_trap; 169 extern int ether_poll(int count); 170 #endif /* DEVICE_POLLING */ 171 172 /* 173 * Exception, fault, and trap interface to the FreeBSD kernel. 174 * This common code is called from assembly language IDT gate entry 175 * routines that prepare a suitable stack frame, and restore this 176 * frame after the exception has been processed. 177 */ 178 179 void 180 trap(frame) 181 struct trapframe frame; 182 { 183 struct thread *td = curthread; 184 struct proc *p = td->td_proc; 185 u_int sticks = 0; 186 int i = 0, ucode = 0, type, code; 187 vm_offset_t eva; 188 #ifdef POWERFAIL_NMI 189 static int lastalert = 0; 190 #endif 191 192 atomic_add_int(&cnt.v_trap, 1); 193 type = frame.tf_trapno; 194 195 #ifdef DDB 196 if (db_active) { 197 eva = (type == T_PAGEFLT ? rcr2() : 0); 198 trap_fatal(&frame, eva); 199 goto out; 200 } 201 #endif 202 203 if ((frame.tf_eflags & PSL_I) == 0) { 204 /* 205 * Buggy application or kernel code has disabled 206 * interrupts and then trapped. Enabling interrupts 207 * now is wrong, but it is better than running with 208 * interrupts disabled until they are accidentally 209 * enabled later. 210 */ 211 if (ISPL(frame.tf_cs) == SEL_UPL || (frame.tf_eflags & PSL_VM)) 212 printf( 213 "pid %ld (%s): trap %d with interrupts disabled\n", 214 (long)curproc->p_pid, curproc->p_comm, type); 215 else if (type != T_BPTFLT && type != T_TRCTRAP && 216 frame.tf_eip != (int)cpu_switch_load_gs) { 217 /* 218 * XXX not quite right, since this may be for a 219 * multiple fault in user mode. 220 */ 221 printf("kernel trap %d with interrupts disabled\n", 222 type); 223 /* 224 * Page faults need interrupts diasabled until later, 225 * and we shouldn't enable interrupts while in a 226 * critical section. 227 */ 228 if (type != T_PAGEFLT && td->td_critnest == 0) 229 enable_intr(); 230 } 231 } 232 233 eva = 0; 234 code = frame.tf_err; 235 if (type == T_PAGEFLT) { 236 /* 237 * For some Cyrix CPUs, %cr2 is clobbered by 238 * interrupts. This problem is worked around by using 239 * an interrupt gate for the pagefault handler. We 240 * are finally ready to read %cr2 and then must 241 * reenable interrupts. 242 * 243 * If we get a page fault while in a critical section, then 244 * it is most likely a fatal kernel page fault. The kernel 245 * is already going to panic trying to get a sleep lock to 246 * do the VM lookup, so just consider it a fatal trap so the 247 * kernel can print out a useful trap message and even get 248 * to the debugger. 249 */ 250 eva = rcr2(); 251 if (td->td_critnest == 0) 252 enable_intr(); 253 else 254 trap_fatal(&frame, eva); 255 } 256 257 #ifdef DEVICE_POLLING 258 if (poll_in_trap) 259 ether_poll(poll_in_trap); 260 #endif /* DEVICE_POLLING */ 261 262 if ((ISPL(frame.tf_cs) == SEL_UPL) || 263 ((frame.tf_eflags & PSL_VM) && 264 !(PCPU_GET(curpcb)->pcb_flags & PCB_VM86CALL))) { 265 /* user trap */ 266 267 sticks = td->td_sticks; 268 td->td_frame = &frame; 269 if (td->td_ucred != p->p_ucred) 270 cred_update_thread(td); 271 272 switch (type) { 273 case T_PRIVINFLT: /* privileged instruction fault */ 274 ucode = type; 275 i = SIGILL; 276 break; 277 278 case T_BPTFLT: /* bpt instruction fault */ 279 case T_TRCTRAP: /* trace trap */ 280 frame.tf_eflags &= ~PSL_T; 281 i = SIGTRAP; 282 break; 283 284 case T_ARITHTRAP: /* arithmetic trap */ 285 #ifdef DEV_NPX 286 ucode = npxtrap(); 287 if (ucode == -1) 288 goto userout; 289 #else 290 ucode = code; 291 #endif 292 i = SIGFPE; 293 break; 294 295 /* 296 * The following two traps can happen in 297 * vm86 mode, and, if so, we want to handle 298 * them specially. 299 */ 300 case T_PROTFLT: /* general protection fault */ 301 case T_STKFLT: /* stack fault */ 302 if (frame.tf_eflags & PSL_VM) { 303 i = vm86_emulate((struct vm86frame *)&frame); 304 if (i == 0) 305 goto user; 306 break; 307 } 308 /* FALLTHROUGH */ 309 310 case T_SEGNPFLT: /* segment not present fault */ 311 case T_TSSFLT: /* invalid TSS fault */ 312 case T_DOUBLEFLT: /* double fault */ 313 default: 314 ucode = code + BUS_SEGM_FAULT ; 315 i = SIGBUS; 316 break; 317 318 case T_PAGEFLT: /* page fault */ 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 if (!pmath_emulate) { 400 i = SIGFPE; 401 ucode = FPE_FPU_NP_TRAP; 402 break; 403 } 404 mtx_lock(&Giant); 405 i = (*pmath_emulate)(&frame); 406 mtx_unlock(&Giant); 407 if (i == 0) { 408 if (!(frame.tf_eflags & PSL_T)) 409 goto userout; 410 frame.tf_eflags &= ~PSL_T; 411 i = SIGTRAP; 412 } 413 /* else ucode = emulator_only_knows() XXX */ 414 break; 415 416 case T_FPOPFLT: /* FPU operand fetch fault */ 417 ucode = T_FPOPFLT; 418 i = SIGILL; 419 break; 420 421 case T_XMMFLT: /* SIMD floating-point exception */ 422 ucode = 0; /* XXX */ 423 i = SIGFPE; 424 break; 425 } 426 } else { 427 /* kernel trap */ 428 429 KASSERT(cold || td->td_ucred != NULL, 430 ("kernel trap doesn't have ucred")); 431 switch (type) { 432 case T_PAGEFLT: /* page fault */ 433 (void) trap_pfault(&frame, FALSE, eva); 434 goto out; 435 436 case T_DNA: 437 #ifdef DEV_NPX 438 /* 439 * The kernel is apparently using npx for copying. 440 * XXX this should be fatal unless the kernel has 441 * registered such use. 442 */ 443 if (npxdna()) 444 goto out; 445 #endif 446 break; 447 448 /* 449 * The following two traps can happen in 450 * vm86 mode, and, if so, we want to handle 451 * them specially. 452 */ 453 case T_PROTFLT: /* general protection fault */ 454 case T_STKFLT: /* stack fault */ 455 if (frame.tf_eflags & PSL_VM) { 456 i = vm86_emulate((struct vm86frame *)&frame); 457 if (i != 0) 458 /* 459 * returns to original process 460 */ 461 vm86_trap((struct vm86frame *)&frame); 462 goto out; 463 } 464 if (type == T_STKFLT) 465 break; 466 467 /* FALL THROUGH */ 468 469 case T_SEGNPFLT: /* segment not present fault */ 470 if (PCPU_GET(curpcb)->pcb_flags & PCB_VM86CALL) 471 break; 472 473 /* 474 * Invalid %fs's and %gs's can be created using 475 * procfs or PT_SETREGS or by invalidating the 476 * underlying LDT entry. This causes a fault 477 * in kernel mode when the kernel attempts to 478 * switch contexts. Lose the bad context 479 * (XXX) so that we can continue, and generate 480 * a signal. 481 */ 482 if (frame.tf_eip == (int)cpu_switch_load_gs) { 483 PCPU_GET(curpcb)->pcb_gs = 0; 484 #if 0 485 PROC_LOCK(p); 486 psignal(p, SIGBUS); 487 PROC_UNLOCK(p); 488 #endif 489 goto out; 490 } 491 492 if (td->td_intr_nesting_level != 0) 493 break; 494 495 /* 496 * Invalid segment selectors and out of bounds 497 * %eip's and %esp's can be set up in user mode. 498 * This causes a fault in kernel mode when the 499 * kernel tries to return to user mode. We want 500 * to get this fault so that we can fix the 501 * problem here and not have to check all the 502 * selectors and pointers when the user changes 503 * them. 504 */ 505 if (frame.tf_eip == (int)doreti_iret) { 506 frame.tf_eip = (int)doreti_iret_fault; 507 goto out; 508 } 509 if (frame.tf_eip == (int)doreti_popl_ds) { 510 frame.tf_eip = (int)doreti_popl_ds_fault; 511 goto out; 512 } 513 if (frame.tf_eip == (int)doreti_popl_es) { 514 frame.tf_eip = (int)doreti_popl_es_fault; 515 goto out; 516 } 517 if (frame.tf_eip == (int)doreti_popl_fs) { 518 frame.tf_eip = (int)doreti_popl_fs_fault; 519 goto out; 520 } 521 if (PCPU_GET(curpcb) != NULL && 522 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 DDB is enabled, let it handle the debugger trap. 589 * Otherwise, debugger traps "can't happen". 590 */ 591 #ifdef DDB 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 DDB 614 /* 615 * NMI can be hooked up to a pushbutton 616 * for debugging. 617 */ 618 if (ddb_on_nmi) { 619 printf ("NMI ... going to debugger\n"); 620 kdb_trap (type, 0, &frame); 621 } 622 #endif /* DDB */ 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 #ifdef DIAGNOSTIC 656 cred_free_thread(td); 657 #endif 658 out: 659 return; 660 } 661 662 static int 663 trap_pfault(frame, usermode, eva) 664 struct trapframe *frame; 665 int usermode; 666 vm_offset_t eva; 667 { 668 vm_offset_t va; 669 struct vmspace *vm = NULL; 670 vm_map_t map = 0; 671 int rv = 0; 672 vm_prot_t ftype; 673 struct thread *td = curthread; 674 struct proc *p = td->td_proc; 675 676 va = trunc_page(eva); 677 if (va >= KERNBASE) { 678 /* 679 * Don't allow user-mode faults in kernel address space. 680 * An exception: if the faulting address is the invalid 681 * instruction entry in the IDT, then the Intel Pentium 682 * F00F bug workaround was triggered, and we need to 683 * treat it is as an illegal instruction, and not a page 684 * fault. 685 */ 686 #if defined(I586_CPU) && !defined(NO_F00F_HACK) 687 if ((eva == (unsigned int)&idt[6]) && has_f00f_bug) 688 return -2; 689 #endif 690 if (usermode) 691 goto nogo; 692 693 map = kernel_map; 694 } else { 695 /* 696 * This is a fault on non-kernel virtual memory. 697 * vm is initialized above to NULL. If curproc is NULL 698 * or curproc->p_vmspace is NULL the fault is fatal. 699 */ 700 if (p != NULL) 701 vm = p->p_vmspace; 702 703 if (vm == NULL) 704 goto nogo; 705 706 map = &vm->vm_map; 707 } 708 709 if (frame->tf_err & PGEX_W) 710 ftype = VM_PROT_WRITE; 711 else 712 ftype = VM_PROT_READ; 713 714 if (map != kernel_map) { 715 /* 716 * Keep swapout from messing with us during this 717 * critical time. 718 */ 719 PROC_LOCK(p); 720 ++p->p_lock; 721 PROC_UNLOCK(p); 722 723 /* Fault in the user page: */ 724 rv = vm_fault(map, va, ftype, 725 (ftype & VM_PROT_WRITE) ? VM_FAULT_DIRTY 726 : VM_FAULT_NORMAL); 727 728 PROC_LOCK(p); 729 --p->p_lock; 730 PROC_UNLOCK(p); 731 } else { 732 /* 733 * Don't have to worry about process locking or stacks in the 734 * kernel. 735 */ 736 rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL); 737 } 738 if (rv == KERN_SUCCESS) 739 return (0); 740 nogo: 741 if (!usermode) { 742 if (td->td_intr_nesting_level == 0 && 743 PCPU_GET(curpcb) != NULL && 744 PCPU_GET(curpcb)->pcb_onfault != NULL) { 745 frame->tf_eip = (int)PCPU_GET(curpcb)->pcb_onfault; 746 return (0); 747 } 748 trap_fatal(frame, eva); 749 return (-1); 750 } 751 752 /* kludge to pass faulting virtual address to sendsig */ 753 frame->tf_err = eva; 754 755 return((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV); 756 } 757 758 static void 759 trap_fatal(frame, eva) 760 struct trapframe *frame; 761 vm_offset_t eva; 762 { 763 int code, type, ss, esp; 764 struct soft_segment_descriptor softseg; 765 766 code = frame->tf_err; 767 type = frame->tf_trapno; 768 sdtossd(&gdt[IDXSEL(frame->tf_cs & 0xffff)].sd, &softseg); 769 770 if (type <= MAX_TRAP_MSG) 771 printf("\n\nFatal trap %d: %s while in %s mode\n", 772 type, trap_msg[type], 773 frame->tf_eflags & PSL_VM ? "vm86" : 774 ISPL(frame->tf_cs) == SEL_UPL ? "user" : "kernel"); 775 #ifdef SMP 776 /* two separate prints in case of a trap on an unmapped page */ 777 printf("cpuid = %d; ", PCPU_GET(cpuid)); 778 printf("lapic.id = %08x\n", lapic.id); 779 #endif 780 if (type == T_PAGEFLT) { 781 printf("fault virtual address = 0x%x\n", eva); 782 printf("fault code = %s %s, %s\n", 783 code & PGEX_U ? "user" : "supervisor", 784 code & PGEX_W ? "write" : "read", 785 code & PGEX_P ? "protection violation" : "page not present"); 786 } 787 printf("instruction pointer = 0x%x:0x%x\n", 788 frame->tf_cs & 0xffff, frame->tf_eip); 789 if ((ISPL(frame->tf_cs) == SEL_UPL) || (frame->tf_eflags & PSL_VM)) { 790 ss = frame->tf_ss & 0xffff; 791 esp = frame->tf_esp; 792 } else { 793 ss = GSEL(GDATA_SEL, SEL_KPL); 794 esp = (int)&frame->tf_esp; 795 } 796 printf("stack pointer = 0x%x:0x%x\n", ss, esp); 797 printf("frame pointer = 0x%x:0x%x\n", ss, frame->tf_ebp); 798 printf("code segment = base 0x%x, limit 0x%x, type 0x%x\n", 799 softseg.ssd_base, softseg.ssd_limit, softseg.ssd_type); 800 printf(" = DPL %d, pres %d, def32 %d, gran %d\n", 801 softseg.ssd_dpl, softseg.ssd_p, softseg.ssd_def32, 802 softseg.ssd_gran); 803 printf("processor eflags = "); 804 if (frame->tf_eflags & PSL_T) 805 printf("trace trap, "); 806 if (frame->tf_eflags & PSL_I) 807 printf("interrupt enabled, "); 808 if (frame->tf_eflags & PSL_NT) 809 printf("nested task, "); 810 if (frame->tf_eflags & PSL_RF) 811 printf("resume, "); 812 if (frame->tf_eflags & PSL_VM) 813 printf("vm86, "); 814 printf("IOPL = %d\n", (frame->tf_eflags & PSL_IOPL) >> 12); 815 printf("current process = "); 816 if (curproc) { 817 printf("%lu (%s)\n", 818 (u_long)curproc->p_pid, curproc->p_comm ? 819 curproc->p_comm : ""); 820 } else { 821 printf("Idle\n"); 822 } 823 824 #ifdef KDB 825 if (kdb_trap(&psl)) 826 return; 827 #endif 828 #ifdef DDB 829 if ((debugger_on_panic || db_active) && kdb_trap(type, 0, frame)) 830 return; 831 #endif 832 printf("trap number = %d\n", type); 833 if (type <= MAX_TRAP_MSG) 834 panic("%s", trap_msg[type]); 835 else 836 panic("unknown/reserved trap"); 837 } 838 839 /* 840 * Double fault handler. Called when a fault occurs while writing 841 * a frame for a trap/exception onto the stack. This usually occurs 842 * when the stack overflows (such is the case with infinite recursion, 843 * for example). 844 * 845 * XXX Note that the current PTD gets replaced by IdlePTD when the 846 * task switch occurs. This means that the stack that was active at 847 * the time of the double fault is not available at <kstack> unless 848 * the machine was idle when the double fault occurred. The downside 849 * of this is that "trace <ebp>" in ddb won't work. 850 */ 851 void 852 dblfault_handler() 853 { 854 printf("\nFatal double fault:\n"); 855 printf("eip = 0x%x\n", PCPU_GET(common_tss.tss_eip)); 856 printf("esp = 0x%x\n", PCPU_GET(common_tss.tss_esp)); 857 printf("ebp = 0x%x\n", PCPU_GET(common_tss.tss_ebp)); 858 #ifdef SMP 859 /* two separate prints in case of a trap on an unmapped page */ 860 printf("cpuid = %d; ", PCPU_GET(cpuid)); 861 printf("lapic.id = %08x\n", lapic.id); 862 #endif 863 panic("double fault"); 864 } 865 866 #ifdef I386_CPU 867 /* 868 * Compensate for 386 brain damage (missing URKR). 869 * This is a little simpler than the pagefault handler in trap() because 870 * it the page tables have already been faulted in and high addresses 871 * are thrown out early for other reasons. 872 */ 873 int trapwrite(addr) 874 unsigned addr; 875 { 876 struct thread *td; 877 struct proc *p; 878 vm_offset_t va; 879 struct vmspace *vm; 880 int rv; 881 882 va = trunc_page((vm_offset_t)addr); 883 /* 884 * XXX - MAX is END. Changed > to >= for temp. fix. 885 */ 886 if (va >= VM_MAXUSER_ADDRESS) 887 return (1); 888 889 td = curthread; 890 p = td->td_proc; 891 vm = p->p_vmspace; 892 893 PROC_LOCK(p); 894 ++p->p_lock; 895 PROC_UNLOCK(p); 896 897 /* 898 * fault the data page 899 */ 900 rv = vm_fault(&vm->vm_map, va, VM_PROT_WRITE, VM_FAULT_DIRTY); 901 902 PROC_LOCK(p); 903 --p->p_lock; 904 PROC_UNLOCK(p); 905 906 if (rv != KERN_SUCCESS) 907 return 1; 908 909 return (0); 910 } 911 #endif 912 913 /* 914 * syscall - system call request C handler 915 * 916 * A system call is essentially treated as a trap. 917 */ 918 void 919 syscall(frame) 920 struct trapframe frame; 921 { 922 caddr_t params; 923 struct sysent *callp; 924 struct thread *td = curthread; 925 struct proc *p = td->td_proc; 926 register_t orig_tf_eflags; 927 u_int sticks; 928 int error; 929 int narg; 930 int args[8]; 931 u_int code; 932 933 /* 934 * note: PCPU_LAZY_INC() can only be used if we can afford 935 * occassional inaccuracy in the count. 936 */ 937 PCPU_LAZY_INC(cnt.v_syscall); 938 939 #ifdef DIAGNOSTIC 940 if (ISPL(frame.tf_cs) != SEL_UPL) { 941 mtx_lock(&Giant); /* try to stabilize the system XXX */ 942 panic("syscall"); 943 /* NOT REACHED */ 944 mtx_unlock(&Giant); 945 } 946 #endif 947 948 sticks = td->td_sticks; 949 td->td_frame = &frame; 950 if (td->td_ucred != p->p_ucred) 951 cred_update_thread(td); 952 if (p->p_flag & P_THREADED) 953 thread_user_enter(p, td); 954 params = (caddr_t)frame.tf_esp + sizeof(int); 955 code = frame.tf_eax; 956 orig_tf_eflags = frame.tf_eflags; 957 958 if (p->p_sysent->sv_prepsyscall) { 959 /* 960 * The prep code is MP aware. 961 */ 962 (*p->p_sysent->sv_prepsyscall)(&frame, args, &code, ¶ms); 963 } else { 964 /* 965 * Need to check if this is a 32 bit or 64 bit syscall. 966 * fuword is MP aware. 967 */ 968 if (code == SYS_syscall) { 969 /* 970 * Code is first argument, followed by actual args. 971 */ 972 code = fuword(params); 973 params += sizeof(int); 974 } else if (code == SYS___syscall) { 975 /* 976 * Like syscall, but code is a quad, so as to maintain 977 * quad alignment for the rest of the arguments. 978 */ 979 code = fuword(params); 980 params += sizeof(quad_t); 981 } 982 } 983 984 if (p->p_sysent->sv_mask) 985 code &= p->p_sysent->sv_mask; 986 987 if (code >= p->p_sysent->sv_size) 988 callp = &p->p_sysent->sv_table[0]; 989 else 990 callp = &p->p_sysent->sv_table[code]; 991 992 narg = callp->sy_narg & SYF_ARGMASK; 993 994 /* 995 * copyin and the ktrsyscall()/ktrsysret() code is MP-aware 996 */ 997 if (params != NULL && narg != 0) 998 error = copyin(params, (caddr_t)args, 999 (u_int)(narg * sizeof(int))); 1000 else 1001 error = 0; 1002 1003 #ifdef KTRACE 1004 if (KTRPOINT(td, KTR_SYSCALL)) 1005 ktrsyscall(code, narg, args); 1006 #endif 1007 1008 /* 1009 * Try to run the syscall without Giant if the syscall 1010 * is MP safe. 1011 */ 1012 if ((callp->sy_narg & SYF_MPSAFE) == 0) 1013 mtx_lock(&Giant); 1014 1015 if (error == 0) { 1016 td->td_retval[0] = 0; 1017 td->td_retval[1] = frame.tf_edx; 1018 1019 STOPEVENT(p, S_SCE, narg); 1020 1021 error = (*callp->sy_call)(td, args); 1022 } 1023 1024 switch (error) { 1025 case 0: 1026 frame.tf_eax = td->td_retval[0]; 1027 frame.tf_edx = td->td_retval[1]; 1028 frame.tf_eflags &= ~PSL_C; 1029 break; 1030 1031 case ERESTART: 1032 /* 1033 * Reconstruct pc, assuming lcall $X,y is 7 bytes, 1034 * int 0x80 is 2 bytes. We saved this in tf_err. 1035 */ 1036 frame.tf_eip -= frame.tf_err; 1037 break; 1038 1039 case EJUSTRETURN: 1040 break; 1041 1042 default: 1043 if (p->p_sysent->sv_errsize) { 1044 if (error >= p->p_sysent->sv_errsize) 1045 error = -1; /* XXX */ 1046 else 1047 error = p->p_sysent->sv_errtbl[error]; 1048 } 1049 frame.tf_eax = error; 1050 frame.tf_eflags |= PSL_C; 1051 break; 1052 } 1053 1054 /* 1055 * Release Giant if we previously set it. 1056 */ 1057 if ((callp->sy_narg & SYF_MPSAFE) == 0) 1058 mtx_unlock(&Giant); 1059 1060 /* 1061 * Traced syscall. 1062 */ 1063 if ((orig_tf_eflags & PSL_T) && !(orig_tf_eflags & PSL_VM)) { 1064 frame.tf_eflags &= ~PSL_T; 1065 trapsignal(td, SIGTRAP, 0); 1066 } 1067 1068 /* 1069 * Handle reschedule and other end-of-syscall issues 1070 */ 1071 userret(td, &frame, sticks); 1072 1073 #ifdef KTRACE 1074 if (KTRPOINT(td, KTR_SYSRET)) 1075 ktrsysret(code, error, td->td_retval[0]); 1076 #endif 1077 1078 /* 1079 * This works because errno is findable through the 1080 * register set. If we ever support an emulation where this 1081 * is not the case, this code will need to be revisited. 1082 */ 1083 STOPEVENT(p, S_SCX, code); 1084 1085 #ifdef DIAGNOSTIC 1086 cred_free_thread(td); 1087 #endif 1088 WITNESS_WARN(WARN_PANIC, NULL, "System call %s returning", 1089 (code >= 0 && code < SYS_MAXSYSCALL) ? syscallnames[code] : "???"); 1090 mtx_assert(&sched_lock, MA_NOTOWNED); 1091 mtx_assert(&Giant, MA_NOTOWNED); 1092 } 1093
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