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/10.4/sys/i386/i386/trap.c 333371 2018-05-08 17:12:10Z gordon $"); 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_kdtrace.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 HWPMC_HOOKS 75 #include <sys/pmckern.h> 76 PMC_SOFT_DEFINE( , , page_fault, all); 77 PMC_SOFT_DEFINE( , , page_fault, read); 78 PMC_SOFT_DEFINE( , , page_fault, write); 79 #endif 80 #include <security/audit/audit.h> 81 82 #include <vm/vm.h> 83 #include <vm/vm_param.h> 84 #include <vm/pmap.h> 85 #include <vm/vm_kern.h> 86 #include <vm/vm_map.h> 87 #include <vm/vm_page.h> 88 #include <vm/vm_extern.h> 89 90 #include <machine/cpu.h> 91 #include <machine/intr_machdep.h> 92 #include <x86/mca.h> 93 #include <machine/md_var.h> 94 #include <machine/pcb.h> 95 #ifdef SMP 96 #include <machine/smp.h> 97 #endif 98 #include <machine/tss.h> 99 #include <machine/vm86.h> 100 101 #ifdef POWERFAIL_NMI 102 #include <sys/syslog.h> 103 #include <machine/clock.h> 104 #endif 105 106 #ifdef KDTRACE_HOOKS 107 #include <sys/dtrace_bsd.h> 108 #endif 109 110 extern void trap(struct trapframe *frame); 111 extern void syscall(struct trapframe *frame); 112 113 static int trap_pfault(struct trapframe *, int, vm_offset_t); 114 static void trap_fatal(struct trapframe *, vm_offset_t); 115 void dblfault_handler(void); 116 117 extern inthand_t IDTVEC(lcall_syscall); 118 119 extern inthand_t IDTVEC(bpt), IDTVEC(dbg), IDTVEC(int0x80_syscall); 120 121 #define MAX_TRAP_MSG 32 122 static char *trap_msg[] = { 123 "", /* 0 unused */ 124 "privileged instruction fault", /* 1 T_PRIVINFLT */ 125 "", /* 2 unused */ 126 "breakpoint instruction fault", /* 3 T_BPTFLT */ 127 "", /* 4 unused */ 128 "", /* 5 unused */ 129 "arithmetic trap", /* 6 T_ARITHTRAP */ 130 "", /* 7 unused */ 131 "", /* 8 unused */ 132 "general protection fault", /* 9 T_PROTFLT */ 133 "trace trap", /* 10 T_TRCTRAP */ 134 "", /* 11 unused */ 135 "page fault", /* 12 T_PAGEFLT */ 136 "", /* 13 unused */ 137 "alignment fault", /* 14 T_ALIGNFLT */ 138 "", /* 15 unused */ 139 "", /* 16 unused */ 140 "", /* 17 unused */ 141 "integer divide fault", /* 18 T_DIVIDE */ 142 "non-maskable interrupt trap", /* 19 T_NMI */ 143 "overflow trap", /* 20 T_OFLOW */ 144 "FPU bounds check fault", /* 21 T_BOUND */ 145 "FPU device not available", /* 22 T_DNA */ 146 "double fault", /* 23 T_DOUBLEFLT */ 147 "FPU operand fetch fault", /* 24 T_FPOPFLT */ 148 "invalid TSS fault", /* 25 T_TSSFLT */ 149 "segment not present fault", /* 26 T_SEGNPFLT */ 150 "stack fault", /* 27 T_STKFLT */ 151 "machine check trap", /* 28 T_MCHK */ 152 "SIMD floating-point exception", /* 29 T_XMMFLT */ 153 "reserved (unknown) fault", /* 30 T_RESERVED */ 154 "", /* 31 unused (reserved) */ 155 "DTrace pid return trap", /* 32 T_DTRACE_RET */ 156 }; 157 158 #if defined(I586_CPU) && !defined(NO_F00F_HACK) 159 int has_f00f_bug = 0; /* Initialized so that it can be patched. */ 160 #endif 161 162 #ifdef KDB 163 static int kdb_on_nmi = 1; 164 SYSCTL_INT(_machdep, OID_AUTO, kdb_on_nmi, CTLFLAG_RW, 165 &kdb_on_nmi, 0, "Go to KDB on NMI"); 166 TUNABLE_INT("machdep.kdb_on_nmi", &kdb_on_nmi); 167 #endif 168 static int panic_on_nmi = 1; 169 SYSCTL_INT(_machdep, OID_AUTO, panic_on_nmi, CTLFLAG_RW, 170 &panic_on_nmi, 0, "Panic on NMI"); 171 TUNABLE_INT("machdep.panic_on_nmi", &panic_on_nmi); 172 static int prot_fault_translation = 0; 173 SYSCTL_INT(_machdep, OID_AUTO, prot_fault_translation, CTLFLAG_RW, 174 &prot_fault_translation, 0, "Select signal to deliver on protection fault"); 175 static int uprintf_signal; 176 SYSCTL_INT(_machdep, OID_AUTO, uprintf_signal, CTLFLAG_RW, 177 &uprintf_signal, 0, 178 "Print debugging information on trap signal to ctty"); 179 180 /* 181 * Exception, fault, and trap interface to the FreeBSD kernel. 182 * This common code is called from assembly language IDT gate entry 183 * routines that prepare a suitable stack frame, and restore this 184 * frame after the exception has been processed. 185 */ 186 187 void 188 trap(struct trapframe *frame) 189 { 190 #ifdef KDTRACE_HOOKS 191 struct reg regs; 192 #endif 193 struct thread *td = curthread; 194 struct proc *p = td->td_proc; 195 int i = 0, ucode = 0, code; 196 u_int type; 197 register_t addr = 0; 198 vm_offset_t eva; 199 ksiginfo_t ksi; 200 #ifdef POWERFAIL_NMI 201 static int lastalert = 0; 202 #endif 203 204 PCPU_INC(cnt.v_trap); 205 type = frame->tf_trapno; 206 207 #ifdef SMP 208 /* Handler for NMI IPIs used for stopping CPUs. */ 209 if (type == T_NMI) { 210 if (ipi_nmi_handler() == 0) 211 goto out; 212 } 213 #endif /* SMP */ 214 215 #ifdef KDB 216 if (kdb_active) { 217 kdb_reenter(); 218 goto out; 219 } 220 #endif 221 222 if (type == T_RESERVED) { 223 trap_fatal(frame, 0); 224 goto out; 225 } 226 227 #ifdef HWPMC_HOOKS 228 /* 229 * CPU PMCs interrupt using an NMI so we check for that first. 230 * If the HWPMC module is active, 'pmc_hook' will point to 231 * the function to be called. A return value of '1' from the 232 * hook means that the NMI was handled by it and that we can 233 * return immediately. 234 */ 235 if (type == T_NMI && pmc_intr && 236 (*pmc_intr)(PCPU_GET(cpuid), frame)) 237 goto out; 238 #endif 239 240 if (type == T_MCHK) { 241 mca_intr(); 242 goto out; 243 } 244 245 #ifdef KDTRACE_HOOKS 246 /* 247 * A trap can occur while DTrace executes a probe. Before 248 * executing the probe, DTrace blocks re-scheduling and sets 249 * a flag in its per-cpu flags to indicate that it doesn't 250 * want to fault. On returning from the probe, the no-fault 251 * flag is cleared and finally re-scheduling is enabled. 252 */ 253 if ((type == T_PROTFLT || type == T_PAGEFLT) && 254 dtrace_trap_func != NULL && (*dtrace_trap_func)(frame, type)) 255 goto out; 256 #endif 257 258 if ((frame->tf_eflags & PSL_I) == 0) { 259 /* 260 * Buggy application or kernel code has disabled 261 * interrupts and then trapped. Enabling interrupts 262 * now is wrong, but it is better than running with 263 * interrupts disabled until they are accidentally 264 * enabled later. 265 */ 266 if (ISPL(frame->tf_cs) == SEL_UPL || (frame->tf_eflags & PSL_VM)) 267 uprintf( 268 "pid %ld (%s): trap %d with interrupts disabled\n", 269 (long)curproc->p_pid, curthread->td_name, type); 270 else if (type != T_NMI && type != T_BPTFLT && 271 type != T_TRCTRAP && 272 frame->tf_eip != (int)cpu_switch_load_gs) { 273 /* 274 * XXX not quite right, since this may be for a 275 * multiple fault in user mode. 276 */ 277 printf("kernel trap %d with interrupts disabled\n", 278 type); 279 /* 280 * Page faults need interrupts disabled until later, 281 * and we shouldn't enable interrupts while holding 282 * a spin lock. 283 */ 284 if (type != T_PAGEFLT && 285 td->td_md.md_spinlock_count == 0) 286 enable_intr(); 287 } 288 } 289 eva = 0; 290 code = frame->tf_err; 291 if (type == T_PAGEFLT) { 292 /* 293 * For some Cyrix CPUs, %cr2 is clobbered by 294 * interrupts. This problem is worked around by using 295 * an interrupt gate for the pagefault handler. We 296 * are finally ready to read %cr2 and conditionally 297 * reenable interrupts. If we hold a spin lock, then 298 * we must not reenable interrupts. This might be a 299 * spurious page fault. 300 */ 301 eva = rcr2(); 302 if (td->td_md.md_spinlock_count == 0) 303 enable_intr(); 304 } 305 306 if ((ISPL(frame->tf_cs) == SEL_UPL) || 307 ((frame->tf_eflags & PSL_VM) && 308 !(curpcb->pcb_flags & PCB_VM86CALL))) { 309 /* user trap */ 310 311 td->td_pticks = 0; 312 td->td_frame = frame; 313 addr = frame->tf_eip; 314 if (td->td_ucred != p->p_ucred) 315 cred_update_thread(td); 316 317 switch (type) { 318 case T_PRIVINFLT: /* privileged instruction fault */ 319 i = SIGILL; 320 ucode = ILL_PRVOPC; 321 break; 322 323 case T_BPTFLT: /* bpt instruction fault */ 324 case T_TRCTRAP: /* trace trap */ 325 enable_intr(); 326 #ifdef KDTRACE_HOOKS 327 if (type == T_BPTFLT) { 328 fill_frame_regs(frame, ®s); 329 if (dtrace_pid_probe_ptr != NULL && 330 dtrace_pid_probe_ptr(®s) == 0) 331 goto out; 332 } 333 #endif 334 frame->tf_eflags &= ~PSL_T; 335 i = SIGTRAP; 336 ucode = (type == T_TRCTRAP ? TRAP_TRACE : TRAP_BRKPT); 337 break; 338 339 case T_ARITHTRAP: /* arithmetic trap */ 340 #ifdef DEV_NPX 341 ucode = npxtrap_x87(); 342 if (ucode == -1) 343 goto userout; 344 #else 345 ucode = 0; 346 #endif 347 i = SIGFPE; 348 break; 349 350 /* 351 * The following two traps can happen in 352 * vm86 mode, and, if so, we want to handle 353 * them specially. 354 */ 355 case T_PROTFLT: /* general protection fault */ 356 case T_STKFLT: /* stack fault */ 357 if (frame->tf_eflags & PSL_VM) { 358 i = vm86_emulate((struct vm86frame *)frame); 359 if (i == 0) 360 goto user; 361 break; 362 } 363 i = SIGBUS; 364 ucode = (type == T_PROTFLT) ? BUS_OBJERR : BUS_ADRERR; 365 break; 366 case T_SEGNPFLT: /* segment not present fault */ 367 i = SIGBUS; 368 ucode = BUS_ADRERR; 369 break; 370 case T_TSSFLT: /* invalid TSS fault */ 371 i = SIGBUS; 372 ucode = BUS_OBJERR; 373 break; 374 case T_ALIGNFLT: 375 i = SIGBUS; 376 ucode = BUS_ADRALN; 377 break; 378 case T_DOUBLEFLT: /* double fault */ 379 default: 380 i = SIGBUS; 381 ucode = BUS_OBJERR; 382 break; 383 384 case T_PAGEFLT: /* page fault */ 385 386 i = trap_pfault(frame, TRUE, eva); 387 #if defined(I586_CPU) && !defined(NO_F00F_HACK) 388 if (i == -2) { 389 /* 390 * The f00f hack workaround has triggered, so 391 * treat the fault as an illegal instruction 392 * (T_PRIVINFLT) instead of a page fault. 393 */ 394 type = frame->tf_trapno = T_PRIVINFLT; 395 396 /* Proceed as in that case. */ 397 ucode = ILL_PRVOPC; 398 i = SIGILL; 399 break; 400 } 401 #endif 402 if (i == -1) 403 goto userout; 404 if (i == 0) 405 goto user; 406 407 if (i == SIGSEGV) 408 ucode = SEGV_MAPERR; 409 else { 410 if (prot_fault_translation == 0) { 411 /* 412 * Autodetect. 413 * This check also covers the images 414 * without the ABI-tag ELF note. 415 */ 416 if (SV_CURPROC_ABI() == SV_ABI_FREEBSD 417 && p->p_osrel >= P_OSREL_SIGSEGV) { 418 i = SIGSEGV; 419 ucode = SEGV_ACCERR; 420 } else { 421 i = SIGBUS; 422 ucode = BUS_PAGE_FAULT; 423 } 424 } else if (prot_fault_translation == 1) { 425 /* 426 * Always compat mode. 427 */ 428 i = SIGBUS; 429 ucode = BUS_PAGE_FAULT; 430 } else { 431 /* 432 * Always SIGSEGV mode. 433 */ 434 i = SIGSEGV; 435 ucode = SEGV_ACCERR; 436 } 437 } 438 addr = eva; 439 break; 440 441 case T_DIVIDE: /* integer divide fault */ 442 ucode = FPE_INTDIV; 443 i = SIGFPE; 444 break; 445 446 #ifdef DEV_ISA 447 case T_NMI: 448 #ifdef POWERFAIL_NMI 449 #ifndef TIMER_FREQ 450 # define TIMER_FREQ 1193182 451 #endif 452 if (time_second - lastalert > 10) { 453 log(LOG_WARNING, "NMI: power fail\n"); 454 sysbeep(880, hz); 455 lastalert = time_second; 456 } 457 goto userout; 458 #else /* !POWERFAIL_NMI */ 459 /* machine/parity/power fail/"kitchen sink" faults */ 460 if (isa_nmi(code) == 0) { 461 #ifdef KDB 462 /* 463 * NMI can be hooked up to a pushbutton 464 * for debugging. 465 */ 466 if (kdb_on_nmi) { 467 printf ("NMI ... going to debugger\n"); 468 kdb_trap(type, 0, frame); 469 } 470 #endif /* KDB */ 471 goto userout; 472 } else if (panic_on_nmi) 473 panic("NMI indicates hardware failure"); 474 goto out; 475 #endif /* POWERFAIL_NMI */ 476 #endif /* DEV_ISA */ 477 478 case T_OFLOW: /* integer overflow fault */ 479 ucode = FPE_INTOVF; 480 i = SIGFPE; 481 break; 482 483 case T_BOUND: /* bounds check fault */ 484 ucode = FPE_FLTSUB; 485 i = SIGFPE; 486 break; 487 488 case T_DNA: 489 #ifdef DEV_NPX 490 KASSERT(PCB_USER_FPU(td->td_pcb), 491 ("kernel FPU ctx has leaked")); 492 /* transparent fault (due to context switch "late") */ 493 if (npxdna()) 494 goto userout; 495 #endif 496 uprintf("pid %d killed due to lack of floating point\n", 497 p->p_pid); 498 i = SIGKILL; 499 ucode = 0; 500 break; 501 502 case T_FPOPFLT: /* FPU operand fetch fault */ 503 ucode = ILL_COPROC; 504 i = SIGILL; 505 break; 506 507 case T_XMMFLT: /* SIMD floating-point exception */ 508 #if defined(DEV_NPX) && !defined(CPU_DISABLE_SSE) && defined(I686_CPU) 509 ucode = npxtrap_sse(); 510 if (ucode == -1) 511 goto userout; 512 #else 513 ucode = 0; 514 #endif 515 i = SIGFPE; 516 break; 517 #ifdef KDTRACE_HOOKS 518 case T_DTRACE_RET: 519 enable_intr(); 520 fill_frame_regs(frame, ®s); 521 if (dtrace_return_probe_ptr != NULL && 522 dtrace_return_probe_ptr(®s) == 0) 523 goto out; 524 goto userout; 525 #endif 526 } 527 } else { 528 /* kernel trap */ 529 530 KASSERT(cold || td->td_ucred != NULL, 531 ("kernel trap doesn't have ucred")); 532 switch (type) { 533 case T_PAGEFLT: /* page fault */ 534 (void) trap_pfault(frame, FALSE, eva); 535 goto out; 536 537 case T_DNA: 538 #ifdef DEV_NPX 539 if (PCB_USER_FPU(td->td_pcb)) 540 panic("Unregistered use of FPU in kernel"); 541 if (npxdna()) 542 goto out; 543 #endif 544 break; 545 546 case T_ARITHTRAP: /* arithmetic trap */ 547 case T_XMMFLT: /* SIMD floating-point exception */ 548 case T_FPOPFLT: /* FPU operand fetch fault */ 549 /* 550 * XXXKIB for now disable any FPU traps in kernel 551 * handler registration seems to be overkill 552 */ 553 trap_fatal(frame, 0); 554 goto out; 555 556 /* 557 * The following two traps can happen in 558 * vm86 mode, and, if so, we want to handle 559 * them specially. 560 */ 561 case T_PROTFLT: /* general protection fault */ 562 case T_STKFLT: /* stack fault */ 563 if (frame->tf_eflags & PSL_VM) { 564 i = vm86_emulate((struct vm86frame *)frame); 565 if (i != 0) 566 /* 567 * returns to original process 568 */ 569 vm86_trap((struct vm86frame *)frame); 570 goto out; 571 } 572 /* FALL THROUGH */ 573 case T_SEGNPFLT: /* segment not present fault */ 574 if (curpcb->pcb_flags & PCB_VM86CALL) 575 break; 576 577 /* 578 * Invalid %fs's and %gs's can be created using 579 * procfs or PT_SETREGS or by invalidating the 580 * underlying LDT entry. This causes a fault 581 * in kernel mode when the kernel attempts to 582 * switch contexts. Lose the bad context 583 * (XXX) so that we can continue, and generate 584 * a signal. 585 */ 586 if (frame->tf_eip == (int)cpu_switch_load_gs) { 587 curpcb->pcb_gs = 0; 588 #if 0 589 PROC_LOCK(p); 590 kern_psignal(p, SIGBUS); 591 PROC_UNLOCK(p); 592 #endif 593 goto out; 594 } 595 596 if (td->td_intr_nesting_level != 0) 597 break; 598 599 /* 600 * Invalid segment selectors and out of bounds 601 * %eip's and %esp's can be set up in user mode. 602 * This causes a fault in kernel mode when the 603 * kernel tries to return to user mode. We want 604 * to get this fault so that we can fix the 605 * problem here and not have to check all the 606 * selectors and pointers when the user changes 607 * them. 608 */ 609 if (frame->tf_eip == (int)doreti_iret) { 610 frame->tf_eip = (int)doreti_iret_fault; 611 goto out; 612 } 613 if (type == T_STKFLT) 614 break; 615 616 if (frame->tf_eip == (int)doreti_popl_ds) { 617 frame->tf_eip = (int)doreti_popl_ds_fault; 618 goto out; 619 } 620 if (frame->tf_eip == (int)doreti_popl_es) { 621 frame->tf_eip = (int)doreti_popl_es_fault; 622 goto out; 623 } 624 if (frame->tf_eip == (int)doreti_popl_fs) { 625 frame->tf_eip = (int)doreti_popl_fs_fault; 626 goto out; 627 } 628 if (curpcb->pcb_onfault != NULL) { 629 frame->tf_eip = 630 (int)curpcb->pcb_onfault; 631 goto out; 632 } 633 break; 634 635 case T_TSSFLT: 636 /* 637 * PSL_NT can be set in user mode and isn't cleared 638 * automatically when the kernel is entered. This 639 * causes a TSS fault when the kernel attempts to 640 * `iret' because the TSS link is uninitialized. We 641 * want to get this fault so that we can fix the 642 * problem here and not every time the kernel is 643 * entered. 644 */ 645 if (frame->tf_eflags & PSL_NT) { 646 frame->tf_eflags &= ~PSL_NT; 647 goto out; 648 } 649 break; 650 651 case T_TRCTRAP: /* trace trap */ 652 if (frame->tf_eip == (int)IDTVEC(lcall_syscall)) { 653 /* 654 * We've just entered system mode via the 655 * syscall lcall. Continue single stepping 656 * silently until the syscall handler has 657 * saved the flags. 658 */ 659 goto out; 660 } 661 if (frame->tf_eip == (int)IDTVEC(lcall_syscall) + 1) { 662 /* 663 * The syscall handler has now saved the 664 * flags. Stop single stepping it. 665 */ 666 frame->tf_eflags &= ~PSL_T; 667 goto out; 668 } 669 /* 670 * Ignore debug register trace traps due to 671 * accesses in the user's address space, which 672 * can happen under several conditions such as 673 * if a user sets a watchpoint on a buffer and 674 * then passes that buffer to a system call. 675 * We still want to get TRCTRAPS for addresses 676 * in kernel space because that is useful when 677 * debugging the kernel. 678 */ 679 if (user_dbreg_trap() && 680 !(curpcb->pcb_flags & PCB_VM86CALL)) { 681 /* 682 * Reset breakpoint bits because the 683 * processor doesn't 684 */ 685 load_dr6(rdr6() & 0xfffffff0); 686 goto out; 687 } 688 689 /* 690 * Malicious user code can configure a debug 691 * register watchpoint to trap on data access 692 * to the top of stack and then execute 'pop 693 * %ss; int 3'. Due to exception deferral for 694 * 'pop %ss', the CPU will not interrupt 'int 695 * 3' to raise the DB# exception for the debug 696 * register but will postpone the DB# until 697 * execution of the first instruction of the 698 * BP# handler (in kernel mode). Normally the 699 * previous check would ignore DB# exceptions 700 * for watchpoints on user addresses raised in 701 * kernel mode. However, some CPU errata 702 * include cases where DB# exceptions do not 703 * properly set bits in %dr6, e.g. Haswell 704 * HSD23 and Skylake-X SKZ24. 705 * 706 * A deferred DB# can also be raised on the 707 * first instructions of system call entry 708 * points or single-step traps via similar use 709 * of 'pop %ss' or 'mov xxx, %ss'. 710 */ 711 if (frame->tf_eip == 712 (uintptr_t)IDTVEC(int0x80_syscall) || 713 frame->tf_eip == (uintptr_t)IDTVEC(bpt) || 714 frame->tf_eip == (uintptr_t)IDTVEC(dbg)) 715 return; 716 /* 717 * FALLTHROUGH (TRCTRAP kernel mode, kernel address) 718 */ 719 case T_BPTFLT: 720 /* 721 * If KDB is enabled, let it handle the debugger trap. 722 * Otherwise, debugger traps "can't happen". 723 */ 724 #ifdef KDB 725 if (kdb_trap(type, 0, frame)) 726 goto out; 727 #endif 728 break; 729 730 #ifdef DEV_ISA 731 case T_NMI: 732 #ifdef POWERFAIL_NMI 733 if (time_second - lastalert > 10) { 734 log(LOG_WARNING, "NMI: power fail\n"); 735 sysbeep(880, hz); 736 lastalert = time_second; 737 } 738 goto out; 739 #else /* !POWERFAIL_NMI */ 740 /* machine/parity/power fail/"kitchen sink" faults */ 741 if (isa_nmi(code) == 0) { 742 #ifdef KDB 743 /* 744 * NMI can be hooked up to a pushbutton 745 * for debugging. 746 */ 747 if (kdb_on_nmi) { 748 printf ("NMI ... going to debugger\n"); 749 kdb_trap(type, 0, frame); 750 } 751 #endif /* KDB */ 752 goto out; 753 } else if (panic_on_nmi == 0) 754 goto out; 755 /* FALLTHROUGH */ 756 #endif /* POWERFAIL_NMI */ 757 #endif /* DEV_ISA */ 758 } 759 760 trap_fatal(frame, eva); 761 goto out; 762 } 763 764 /* Translate fault for emulators (e.g. Linux) */ 765 if (*p->p_sysent->sv_transtrap) 766 i = (*p->p_sysent->sv_transtrap)(i, type); 767 768 ksiginfo_init_trap(&ksi); 769 ksi.ksi_signo = i; 770 ksi.ksi_code = ucode; 771 ksi.ksi_addr = (void *)addr; 772 ksi.ksi_trapno = type; 773 if (uprintf_signal) { 774 uprintf("pid %d comm %s: signal %d err %x code %d type %d " 775 "addr 0x%x esp 0x%08x eip 0x%08x " 776 "<%02x %02x %02x %02x %02x %02x %02x %02x>\n", 777 p->p_pid, p->p_comm, i, frame->tf_err, ucode, type, addr, 778 frame->tf_esp, frame->tf_eip, 779 fubyte((void *)(frame->tf_eip + 0)), 780 fubyte((void *)(frame->tf_eip + 1)), 781 fubyte((void *)(frame->tf_eip + 2)), 782 fubyte((void *)(frame->tf_eip + 3)), 783 fubyte((void *)(frame->tf_eip + 4)), 784 fubyte((void *)(frame->tf_eip + 5)), 785 fubyte((void *)(frame->tf_eip + 6)), 786 fubyte((void *)(frame->tf_eip + 7))); 787 } 788 KASSERT((read_eflags() & PSL_I) != 0, ("interrupts disabled")); 789 trapsignal(td, &ksi); 790 791 #ifdef DEBUG 792 if (type <= MAX_TRAP_MSG) { 793 uprintf("fatal process exception: %s", 794 trap_msg[type]); 795 if ((type == T_PAGEFLT) || (type == T_PROTFLT)) 796 uprintf(", fault VA = 0x%lx", (u_long)eva); 797 uprintf("\n"); 798 } 799 #endif 800 801 user: 802 userret(td, frame); 803 KASSERT(PCB_USER_FPU(td->td_pcb), 804 ("Return from trap with kernel FPU ctx leaked")); 805 userout: 806 out: 807 return; 808 } 809 810 static int 811 trap_pfault(frame, usermode, eva) 812 struct trapframe *frame; 813 int usermode; 814 vm_offset_t eva; 815 { 816 vm_offset_t va; 817 struct vmspace *vm; 818 vm_map_t map; 819 int rv = 0; 820 vm_prot_t ftype; 821 struct thread *td = curthread; 822 struct proc *p = td->td_proc; 823 824 if (__predict_false((td->td_pflags & TDP_NOFAULTING) != 0)) { 825 /* 826 * Due to both processor errata and lazy TLB invalidation when 827 * access restrictions are removed from virtual pages, memory 828 * accesses that are allowed by the physical mapping layer may 829 * nonetheless cause one spurious page fault per virtual page. 830 * When the thread is executing a "no faulting" section that 831 * is bracketed by vm_fault_{disable,enable}_pagefaults(), 832 * every page fault is treated as a spurious page fault, 833 * unless it accesses the same virtual address as the most 834 * recent page fault within the same "no faulting" section. 835 */ 836 if (td->td_md.md_spurflt_addr != eva || 837 (td->td_pflags & TDP_RESETSPUR) != 0) { 838 /* 839 * Do nothing to the TLB. A stale TLB entry is 840 * flushed automatically by a page fault. 841 */ 842 td->td_md.md_spurflt_addr = eva; 843 td->td_pflags &= ~TDP_RESETSPUR; 844 return (0); 845 } 846 } else { 847 /* 848 * If we get a page fault while in a critical section, then 849 * it is most likely a fatal kernel page fault. The kernel 850 * is already going to panic trying to get a sleep lock to 851 * do the VM lookup, so just consider it a fatal trap so the 852 * kernel can print out a useful trap message and even get 853 * to the debugger. 854 * 855 * If we get a page fault while holding a non-sleepable 856 * lock, then it is most likely a fatal kernel page fault. 857 * If WITNESS is enabled, then it's going to whine about 858 * bogus LORs with various VM locks, so just skip to the 859 * fatal trap handling directly. 860 */ 861 if (td->td_critnest != 0 || 862 WITNESS_CHECK(WARN_SLEEPOK | WARN_GIANTOK, NULL, 863 "Kernel page fault") != 0) { 864 trap_fatal(frame, eva); 865 return (-1); 866 } 867 } 868 va = trunc_page(eva); 869 if (va >= KERNBASE) { 870 /* 871 * Don't allow user-mode faults in kernel address space. 872 * An exception: if the faulting address is the invalid 873 * instruction entry in the IDT, then the Intel Pentium 874 * F00F bug workaround was triggered, and we need to 875 * treat it is as an illegal instruction, and not a page 876 * fault. 877 */ 878 #if defined(I586_CPU) && !defined(NO_F00F_HACK) 879 if ((eva == (unsigned int)&idt[6]) && has_f00f_bug) 880 return (-2); 881 #endif 882 if (usermode) 883 goto nogo; 884 885 map = kernel_map; 886 } else { 887 /* 888 * This is a fault on non-kernel virtual memory. If either 889 * p or p->p_vmspace is NULL, then the fault is fatal. 890 */ 891 if (p == NULL || (vm = p->p_vmspace) == NULL) 892 goto nogo; 893 894 map = &vm->vm_map; 895 896 /* 897 * When accessing a user-space address, kernel must be 898 * ready to accept the page fault, and provide a 899 * handling routine. Since accessing the address 900 * without the handler is a bug, do not try to handle 901 * it normally, and panic immediately. 902 */ 903 if (!usermode && (td->td_intr_nesting_level != 0 || 904 curpcb->pcb_onfault == NULL)) { 905 trap_fatal(frame, eva); 906 return (-1); 907 } 908 } 909 910 /* 911 * If the trap was caused by errant bits in the PTE then panic. 912 */ 913 if (frame->tf_err & PGEX_RSV) { 914 trap_fatal(frame, eva); 915 return (-1); 916 } 917 918 /* 919 * PGEX_I is defined only if the execute disable bit capability is 920 * supported and enabled. 921 */ 922 if (frame->tf_err & PGEX_W) 923 ftype = VM_PROT_WRITE; 924 #if defined(PAE) || defined(PAE_TABLES) 925 else if ((frame->tf_err & PGEX_I) && pg_nx != 0) 926 ftype = VM_PROT_EXECUTE; 927 #endif 928 else 929 ftype = VM_PROT_READ; 930 931 if (map != kernel_map) { 932 /* 933 * Keep swapout from messing with us during this 934 * critical time. 935 */ 936 PROC_LOCK(p); 937 ++p->p_lock; 938 PROC_UNLOCK(p); 939 940 /* Fault in the user page: */ 941 rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL); 942 943 PROC_LOCK(p); 944 --p->p_lock; 945 PROC_UNLOCK(p); 946 } else { 947 /* 948 * Don't have to worry about process locking or stacks in the 949 * kernel. 950 */ 951 rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL); 952 } 953 if (rv == KERN_SUCCESS) { 954 #ifdef HWPMC_HOOKS 955 if (ftype == VM_PROT_READ || ftype == VM_PROT_WRITE) { 956 PMC_SOFT_CALL_TF( , , page_fault, all, frame); 957 if (ftype == VM_PROT_READ) 958 PMC_SOFT_CALL_TF( , , page_fault, read, 959 frame); 960 else 961 PMC_SOFT_CALL_TF( , , page_fault, write, 962 frame); 963 } 964 #endif 965 return (0); 966 } 967 nogo: 968 if (!usermode) { 969 if (td->td_intr_nesting_level == 0 && 970 curpcb->pcb_onfault != NULL) { 971 frame->tf_eip = (int)curpcb->pcb_onfault; 972 return (0); 973 } 974 trap_fatal(frame, eva); 975 return (-1); 976 } 977 return ((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV); 978 } 979 980 static void 981 trap_fatal(frame, eva) 982 struct trapframe *frame; 983 vm_offset_t eva; 984 { 985 int code, ss, esp; 986 u_int type; 987 struct soft_segment_descriptor softseg; 988 char *msg; 989 990 code = frame->tf_err; 991 type = frame->tf_trapno; 992 sdtossd(&gdt[IDXSEL(frame->tf_cs & 0xffff)].sd, &softseg); 993 994 if (type <= MAX_TRAP_MSG) 995 msg = trap_msg[type]; 996 else 997 msg = "UNKNOWN"; 998 printf("\n\nFatal trap %d: %s while in %s mode\n", type, msg, 999 frame->tf_eflags & PSL_VM ? "vm86" : 1000 ISPL(frame->tf_cs) == SEL_UPL ? "user" : "kernel"); 1001 #ifdef SMP 1002 /* two separate prints in case of a trap on an unmapped page */ 1003 printf("cpuid = %d; ", PCPU_GET(cpuid)); 1004 printf("apic id = %02x\n", PCPU_GET(apic_id)); 1005 #endif 1006 if (type == T_PAGEFLT) { 1007 printf("fault virtual address = 0x%x\n", eva); 1008 printf("fault code = %s %s%s, %s\n", 1009 code & PGEX_U ? "user" : "supervisor", 1010 code & PGEX_W ? "write" : "read", 1011 #if defined(PAE) || defined(PAE_TABLES) 1012 pg_nx != 0 ? 1013 (code & PGEX_I ? " instruction" : " data") : 1014 #endif 1015 "", 1016 code & PGEX_RSV ? "reserved bits in PTE" : 1017 code & PGEX_P ? "protection violation" : "page not present"); 1018 } 1019 printf("instruction pointer = 0x%x:0x%x\n", 1020 frame->tf_cs & 0xffff, frame->tf_eip); 1021 if ((ISPL(frame->tf_cs) == SEL_UPL) || (frame->tf_eflags & PSL_VM)) { 1022 ss = frame->tf_ss & 0xffff; 1023 esp = frame->tf_esp; 1024 } else { 1025 ss = GSEL(GDATA_SEL, SEL_KPL); 1026 esp = (int)&frame->tf_esp; 1027 } 1028 printf("stack pointer = 0x%x:0x%x\n", ss, esp); 1029 printf("frame pointer = 0x%x:0x%x\n", ss, frame->tf_ebp); 1030 printf("code segment = base 0x%x, limit 0x%x, type 0x%x\n", 1031 softseg.ssd_base, softseg.ssd_limit, softseg.ssd_type); 1032 printf(" = DPL %d, pres %d, def32 %d, gran %d\n", 1033 softseg.ssd_dpl, softseg.ssd_p, softseg.ssd_def32, 1034 softseg.ssd_gran); 1035 printf("processor eflags = "); 1036 if (frame->tf_eflags & PSL_T) 1037 printf("trace trap, "); 1038 if (frame->tf_eflags & PSL_I) 1039 printf("interrupt enabled, "); 1040 if (frame->tf_eflags & PSL_NT) 1041 printf("nested task, "); 1042 if (frame->tf_eflags & PSL_RF) 1043 printf("resume, "); 1044 if (frame->tf_eflags & PSL_VM) 1045 printf("vm86, "); 1046 printf("IOPL = %d\n", (frame->tf_eflags & PSL_IOPL) >> 12); 1047 printf("current process = %d (%s)\n", 1048 curproc->p_pid, curthread->td_name); 1049 1050 #ifdef KDB 1051 if (debugger_on_panic || kdb_active) { 1052 frame->tf_err = eva; /* smuggle fault address to ddb */ 1053 if (kdb_trap(type, 0, frame)) { 1054 frame->tf_err = code; /* restore error code */ 1055 return; 1056 } 1057 frame->tf_err = code; /* restore error code */ 1058 } 1059 #endif 1060 printf("trap number = %d\n", type); 1061 if (type <= MAX_TRAP_MSG) 1062 panic("%s", trap_msg[type]); 1063 else 1064 panic("unknown/reserved trap"); 1065 } 1066 1067 /* 1068 * Double fault handler. Called when a fault occurs while writing 1069 * a frame for a trap/exception onto the stack. This usually occurs 1070 * when the stack overflows (such is the case with infinite recursion, 1071 * for example). 1072 * 1073 * XXX Note that the current PTD gets replaced by IdlePTD when the 1074 * task switch occurs. This means that the stack that was active at 1075 * the time of the double fault is not available at <kstack> unless 1076 * the machine was idle when the double fault occurred. The downside 1077 * of this is that "trace <ebp>" in ddb won't work. 1078 */ 1079 void 1080 dblfault_handler() 1081 { 1082 #ifdef KDTRACE_HOOKS 1083 if (dtrace_doubletrap_func != NULL) 1084 (*dtrace_doubletrap_func)(); 1085 #endif 1086 printf("\nFatal double fault:\n"); 1087 printf("eip = 0x%x\n", PCPU_GET(common_tss.tss_eip)); 1088 printf("esp = 0x%x\n", PCPU_GET(common_tss.tss_esp)); 1089 printf("ebp = 0x%x\n", PCPU_GET(common_tss.tss_ebp)); 1090 #ifdef SMP 1091 /* two separate prints in case of a trap on an unmapped page */ 1092 printf("cpuid = %d; ", PCPU_GET(cpuid)); 1093 printf("apic id = %02x\n", PCPU_GET(apic_id)); 1094 #endif 1095 panic("double fault"); 1096 } 1097 1098 int 1099 cpu_fetch_syscall_args(struct thread *td, struct syscall_args *sa) 1100 { 1101 struct proc *p; 1102 struct trapframe *frame; 1103 caddr_t params; 1104 long tmp; 1105 int error; 1106 1107 p = td->td_proc; 1108 frame = td->td_frame; 1109 1110 params = (caddr_t)frame->tf_esp + sizeof(int); 1111 sa->code = frame->tf_eax; 1112 1113 /* 1114 * Need to check if this is a 32 bit or 64 bit syscall. 1115 */ 1116 if (sa->code == SYS_syscall) { 1117 /* 1118 * Code is first argument, followed by actual args. 1119 */ 1120 error = fueword(params, &tmp); 1121 if (error == -1) 1122 return (EFAULT); 1123 sa->code = tmp; 1124 params += sizeof(int); 1125 } else if (sa->code == SYS___syscall) { 1126 /* 1127 * Like syscall, but code is a quad, so as to maintain 1128 * quad alignment for the rest of the arguments. 1129 */ 1130 error = fueword(params, &tmp); 1131 if (error == -1) 1132 return (EFAULT); 1133 sa->code = tmp; 1134 params += sizeof(quad_t); 1135 } 1136 1137 if (p->p_sysent->sv_mask) 1138 sa->code &= p->p_sysent->sv_mask; 1139 if (sa->code >= p->p_sysent->sv_size) 1140 sa->callp = &p->p_sysent->sv_table[0]; 1141 else 1142 sa->callp = &p->p_sysent->sv_table[sa->code]; 1143 sa->narg = sa->callp->sy_narg; 1144 1145 if (params != NULL && sa->narg != 0) 1146 error = copyin(params, (caddr_t)sa->args, 1147 (u_int)(sa->narg * sizeof(int))); 1148 else 1149 error = 0; 1150 1151 if (error == 0) { 1152 td->td_retval[0] = 0; 1153 td->td_retval[1] = frame->tf_edx; 1154 } 1155 1156 return (error); 1157 } 1158 1159 #include "../../kern/subr_syscall.c" 1160 1161 /* 1162 * syscall - system call request C handler. A system call is 1163 * essentially treated as a trap by reusing the frame layout. 1164 */ 1165 void 1166 syscall(struct trapframe *frame) 1167 { 1168 struct thread *td; 1169 struct syscall_args sa; 1170 register_t orig_tf_eflags; 1171 int error; 1172 ksiginfo_t ksi; 1173 1174 #ifdef DIAGNOSTIC 1175 if (ISPL(frame->tf_cs) != SEL_UPL) { 1176 panic("syscall"); 1177 /* NOT REACHED */ 1178 } 1179 #endif 1180 orig_tf_eflags = frame->tf_eflags; 1181 1182 td = curthread; 1183 td->td_frame = frame; 1184 1185 error = syscallenter(td, &sa); 1186 1187 /* 1188 * Traced syscall. 1189 */ 1190 if ((orig_tf_eflags & PSL_T) && !(orig_tf_eflags & PSL_VM)) { 1191 frame->tf_eflags &= ~PSL_T; 1192 ksiginfo_init_trap(&ksi); 1193 ksi.ksi_signo = SIGTRAP; 1194 ksi.ksi_code = TRAP_TRACE; 1195 ksi.ksi_addr = (void *)frame->tf_eip; 1196 trapsignal(td, &ksi); 1197 } 1198 1199 KASSERT(PCB_USER_FPU(td->td_pcb), 1200 ("System call %s returning with kernel FPU ctx leaked", 1201 syscallname(td->td_proc, sa.code))); 1202 KASSERT(td->td_pcb->pcb_save == get_pcb_user_save_td(td), 1203 ("System call %s returning with mangled pcb_save", 1204 syscallname(td->td_proc, sa.code))); 1205 1206 syscallret(td, error, &sa); 1207 }
Cache object: 1b3c51003942f2c4f7baf68272020911
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