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("$FreeBSD$"); 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_stack.h" 53 #include "opt_trap.h" 54 55 #include <sys/param.h> 56 #include <sys/bus.h> 57 #include <sys/systm.h> 58 #include <sys/proc.h> 59 #include <sys/pioctl.h> 60 #include <sys/ptrace.h> 61 #include <sys/kdb.h> 62 #include <sys/kernel.h> 63 #include <sys/ktr.h> 64 #include <sys/lock.h> 65 #include <sys/mutex.h> 66 #include <sys/resourcevar.h> 67 #include <sys/signalvar.h> 68 #include <sys/syscall.h> 69 #include <sys/sysctl.h> 70 #include <sys/sysent.h> 71 #include <sys/uio.h> 72 #include <sys/vmmeter.h> 73 #ifdef HWPMC_HOOKS 74 #include <sys/pmckern.h> 75 PMC_SOFT_DEFINE( , , page_fault, all); 76 PMC_SOFT_DEFINE( , , page_fault, read); 77 PMC_SOFT_DEFINE( , , page_fault, write); 78 #endif 79 #include <security/audit/audit.h> 80 81 #include <vm/vm.h> 82 #include <vm/vm_param.h> 83 #include <vm/pmap.h> 84 #include <vm/vm_kern.h> 85 #include <vm/vm_map.h> 86 #include <vm/vm_page.h> 87 #include <vm/vm_extern.h> 88 89 #include <machine/cpu.h> 90 #include <machine/intr_machdep.h> 91 #include <x86/mca.h> 92 #include <machine/md_var.h> 93 #include <machine/pcb.h> 94 #ifdef SMP 95 #include <machine/smp.h> 96 #endif 97 #include <machine/stack.h> 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 void trap(struct trapframe *frame); 111 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 "debug exception", /* 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 static int prot_fault_translation = 0; 163 SYSCTL_INT(_machdep, OID_AUTO, prot_fault_translation, CTLFLAG_RW, 164 &prot_fault_translation, 0, "Select signal to deliver on protection fault"); 165 static int uprintf_signal; 166 SYSCTL_INT(_machdep, OID_AUTO, uprintf_signal, CTLFLAG_RW, 167 &uprintf_signal, 0, 168 "Print debugging information on trap signal to ctty"); 169 170 /* 171 * Exception, fault, and trap interface to the FreeBSD kernel. 172 * This common code is called from assembly language IDT gate entry 173 * routines that prepare a suitable stack frame, and restore this 174 * frame after the exception has been processed. 175 */ 176 177 void 178 trap(struct trapframe *frame) 179 { 180 ksiginfo_t ksi; 181 struct thread *td; 182 struct proc *p; 183 int signo, ucode; 184 u_int type; 185 register_t addr, dr6; 186 vm_offset_t eva; 187 #ifdef POWERFAIL_NMI 188 static int lastalert = 0; 189 #endif 190 191 td = curthread; 192 p = td->td_proc; 193 signo = 0; 194 ucode = 0; 195 addr = 0; 196 dr6 = 0; 197 198 PCPU_INC(cnt.v_trap); 199 type = frame->tf_trapno; 200 201 #ifdef SMP 202 /* Handler for NMI IPIs used for stopping CPUs. */ 203 if (type == T_NMI && ipi_nmi_handler() == 0) 204 return; 205 #endif /* SMP */ 206 207 #ifdef KDB 208 if (kdb_active) { 209 kdb_reenter(); 210 return; 211 } 212 #endif 213 214 if (type == T_RESERVED) { 215 trap_fatal(frame, 0); 216 return; 217 } 218 219 if (type == T_NMI) { 220 #ifdef HWPMC_HOOKS 221 /* 222 * CPU PMCs interrupt using an NMI so we check for that first. 223 * If the HWPMC module is active, 'pmc_hook' will point to 224 * the function to be called. A non-zero return value from the 225 * hook means that the NMI was consumed by it and that we can 226 * return immediately. 227 */ 228 if (pmc_intr != NULL && 229 (*pmc_intr)(PCPU_GET(cpuid), frame) != 0) 230 return; 231 #endif 232 233 #ifdef STACK 234 if (stack_nmi_handler(frame) != 0) 235 return; 236 #endif 237 } 238 239 if (type == T_MCHK) { 240 mca_intr(); 241 return; 242 } 243 244 #ifdef KDTRACE_HOOKS 245 /* 246 * A trap can occur while DTrace executes a probe. Before 247 * executing the probe, DTrace blocks re-scheduling and sets 248 * a flag in its per-cpu flags to indicate that it doesn't 249 * want to fault. On returning from the probe, the no-fault 250 * flag is cleared and finally re-scheduling is enabled. 251 */ 252 if ((type == T_PROTFLT || type == T_PAGEFLT) && 253 dtrace_trap_func != NULL && (*dtrace_trap_func)(frame, type)) 254 return; 255 #endif 256 257 if ((frame->tf_eflags & PSL_I) == 0) { 258 /* 259 * Buggy application or kernel code has disabled 260 * interrupts and then trapped. Enabling interrupts 261 * now is wrong, but it is better than running with 262 * interrupts disabled until they are accidentally 263 * enabled later. 264 */ 265 if (TRAPF_USERMODE(frame) && 266 (curpcb->pcb_flags & PCB_VM86CALL) == 0) 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 if (type == T_PAGEFLT) { 291 /* 292 * For some Cyrix CPUs, %cr2 is clobbered by 293 * interrupts. This problem is worked around by using 294 * an interrupt gate for the pagefault handler. We 295 * are finally ready to read %cr2 and conditionally 296 * reenable interrupts. If we hold a spin lock, then 297 * we must not reenable interrupts. This might be a 298 * spurious page fault. 299 */ 300 eva = rcr2(); 301 if (td->td_md.md_spinlock_count == 0) 302 enable_intr(); 303 } 304 305 if (TRAPF_USERMODE(frame) && (curpcb->pcb_flags & PCB_VM86CALL) == 0) { 306 /* user trap */ 307 308 td->td_pticks = 0; 309 td->td_frame = frame; 310 addr = frame->tf_eip; 311 if (td->td_cowgen != p->p_cowgen) 312 thread_cow_update(td); 313 314 switch (type) { 315 case T_PRIVINFLT: /* privileged instruction fault */ 316 signo = SIGILL; 317 ucode = ILL_PRVOPC; 318 break; 319 320 case T_BPTFLT: /* bpt instruction fault */ 321 enable_intr(); 322 #ifdef KDTRACE_HOOKS 323 if (dtrace_pid_probe_ptr != NULL && 324 dtrace_pid_probe_ptr(frame) == 0) 325 return; 326 #endif 327 signo = SIGTRAP; 328 ucode = TRAP_BRKPT; 329 break; 330 331 case T_TRCTRAP: /* debug exception */ 332 enable_intr(); 333 user_trctrap_out: 334 signo = SIGTRAP; 335 ucode = TRAP_TRACE; 336 dr6 = rdr6(); 337 if ((dr6 & DBREG_DR6_BS) != 0) { 338 PROC_LOCK(td->td_proc); 339 if ((td->td_dbgflags & TDB_STEP) != 0) { 340 td->td_frame->tf_eflags &= ~PSL_T; 341 td->td_dbgflags &= ~TDB_STEP; 342 } 343 PROC_UNLOCK(td->td_proc); 344 } 345 break; 346 347 case T_ARITHTRAP: /* arithmetic trap */ 348 ucode = npxtrap_x87(); 349 if (ucode == -1) 350 return; 351 signo = SIGFPE; 352 break; 353 354 /* 355 * The following two traps can happen in vm86 mode, 356 * and, if so, we want to handle them specially. 357 */ 358 case T_PROTFLT: /* general protection fault */ 359 case T_STKFLT: /* stack fault */ 360 if (frame->tf_eflags & PSL_VM) { 361 signo = vm86_emulate((struct vm86frame *)frame); 362 if (signo == SIGTRAP) { 363 type = T_TRCTRAP; 364 load_dr6(rdr6() | 0x4000); 365 goto user_trctrap_out; 366 } 367 if (signo == 0) 368 goto user; 369 break; 370 } 371 signo = SIGBUS; 372 ucode = (type == T_PROTFLT) ? BUS_OBJERR : BUS_ADRERR; 373 break; 374 case T_SEGNPFLT: /* segment not present fault */ 375 signo = SIGBUS; 376 ucode = BUS_ADRERR; 377 break; 378 case T_TSSFLT: /* invalid TSS fault */ 379 signo = SIGBUS; 380 ucode = BUS_OBJERR; 381 break; 382 case T_ALIGNFLT: 383 signo = SIGBUS; 384 ucode = BUS_ADRALN; 385 break; 386 case T_DOUBLEFLT: /* double fault */ 387 default: 388 signo = SIGBUS; 389 ucode = BUS_OBJERR; 390 break; 391 392 case T_PAGEFLT: /* page fault */ 393 signo = trap_pfault(frame, TRUE, eva); 394 #if defined(I586_CPU) && !defined(NO_F00F_HACK) 395 if (signo == -2) { 396 /* 397 * The f00f hack workaround has triggered, so 398 * treat the fault as an illegal instruction 399 * (T_PRIVINFLT) instead of a page fault. 400 */ 401 type = frame->tf_trapno = T_PRIVINFLT; 402 403 /* Proceed as in that case. */ 404 ucode = ILL_PRVOPC; 405 signo = SIGILL; 406 break; 407 } 408 #endif 409 if (signo == -1) 410 return; 411 if (signo == 0) 412 goto user; 413 414 if (signo == SIGSEGV) 415 ucode = SEGV_MAPERR; 416 else if (prot_fault_translation == 0) { 417 /* 418 * Autodetect. This check also covers 419 * the images without the ABI-tag ELF 420 * note. 421 */ 422 if (SV_CURPROC_ABI() == SV_ABI_FREEBSD && 423 p->p_osrel >= P_OSREL_SIGSEGV) { 424 signo = SIGSEGV; 425 ucode = SEGV_ACCERR; 426 } else { 427 signo = SIGBUS; 428 ucode = BUS_PAGE_FAULT; 429 } 430 } else if (prot_fault_translation == 1) { 431 /* 432 * Always compat mode. 433 */ 434 signo = SIGBUS; 435 ucode = BUS_PAGE_FAULT; 436 } else { 437 /* 438 * Always SIGSEGV mode. 439 */ 440 signo = SIGSEGV; 441 ucode = SEGV_ACCERR; 442 } 443 addr = eva; 444 break; 445 446 case T_DIVIDE: /* integer divide fault */ 447 ucode = FPE_INTDIV; 448 signo = SIGFPE; 449 break; 450 451 #ifdef DEV_ISA 452 case T_NMI: 453 #ifdef POWERFAIL_NMI 454 #ifndef TIMER_FREQ 455 # define TIMER_FREQ 1193182 456 #endif 457 if (time_second - lastalert > 10) { 458 log(LOG_WARNING, "NMI: power fail\n"); 459 sysbeep(880, hz); 460 lastalert = time_second; 461 } 462 return; 463 #else /* !POWERFAIL_NMI */ 464 nmi_handle_intr(type, frame); 465 return; 466 #endif /* POWERFAIL_NMI */ 467 #endif /* DEV_ISA */ 468 469 case T_OFLOW: /* integer overflow fault */ 470 ucode = FPE_INTOVF; 471 signo = SIGFPE; 472 break; 473 474 case T_BOUND: /* bounds check fault */ 475 ucode = FPE_FLTSUB; 476 signo = SIGFPE; 477 break; 478 479 case T_DNA: 480 KASSERT(PCB_USER_FPU(td->td_pcb), 481 ("kernel FPU ctx has leaked")); 482 /* transparent fault (due to context switch "late") */ 483 if (npxdna()) 484 return; 485 uprintf("pid %d killed due to lack of floating point\n", 486 p->p_pid); 487 signo = SIGKILL; 488 ucode = 0; 489 break; 490 491 case T_FPOPFLT: /* FPU operand fetch fault */ 492 ucode = ILL_COPROC; 493 signo = SIGILL; 494 break; 495 496 case T_XMMFLT: /* SIMD floating-point exception */ 497 ucode = npxtrap_sse(); 498 if (ucode == -1) 499 return; 500 signo = SIGFPE; 501 break; 502 #ifdef KDTRACE_HOOKS 503 case T_DTRACE_RET: 504 enable_intr(); 505 if (dtrace_return_probe_ptr != NULL) 506 dtrace_return_probe_ptr(frame); 507 return; 508 #endif 509 } 510 } else { 511 /* kernel trap */ 512 513 KASSERT(cold || td->td_ucred != NULL, 514 ("kernel trap doesn't have ucred")); 515 switch (type) { 516 case T_PAGEFLT: /* page fault */ 517 (void) trap_pfault(frame, FALSE, eva); 518 return; 519 520 case T_DNA: 521 if (PCB_USER_FPU(td->td_pcb)) 522 panic("Unregistered use of FPU in kernel"); 523 if (npxdna()) 524 return; 525 break; 526 527 case T_ARITHTRAP: /* arithmetic trap */ 528 case T_XMMFLT: /* SIMD floating-point exception */ 529 case T_FPOPFLT: /* FPU operand fetch fault */ 530 /* 531 * XXXKIB for now disable any FPU traps in kernel 532 * handler registration seems to be overkill 533 */ 534 trap_fatal(frame, 0); 535 return; 536 537 /* 538 * The following two traps can happen in 539 * vm86 mode, and, if so, we want to handle 540 * them specially. 541 */ 542 case T_PROTFLT: /* general protection fault */ 543 case T_STKFLT: /* stack fault */ 544 if (frame->tf_eflags & PSL_VM) { 545 signo = vm86_emulate((struct vm86frame *)frame); 546 if (signo == SIGTRAP) { 547 type = T_TRCTRAP; 548 load_dr6(rdr6() | 0x4000); 549 goto kernel_trctrap; 550 } 551 if (signo != 0) 552 /* 553 * returns to original process 554 */ 555 vm86_trap((struct vm86frame *)frame); 556 return; 557 } 558 /* FALL THROUGH */ 559 case T_SEGNPFLT: /* segment not present fault */ 560 if (curpcb->pcb_flags & PCB_VM86CALL) 561 break; 562 563 /* 564 * Invalid %fs's and %gs's can be created using 565 * procfs or PT_SETREGS or by invalidating the 566 * underlying LDT entry. This causes a fault 567 * in kernel mode when the kernel attempts to 568 * switch contexts. Lose the bad context 569 * (XXX) so that we can continue, and generate 570 * a signal. 571 */ 572 if (frame->tf_eip == (int)cpu_switch_load_gs) { 573 curpcb->pcb_gs = 0; 574 #if 0 575 PROC_LOCK(p); 576 kern_psignal(p, SIGBUS); 577 PROC_UNLOCK(p); 578 #endif 579 return; 580 } 581 582 if (td->td_intr_nesting_level != 0) 583 break; 584 585 /* 586 * Invalid segment selectors and out of bounds 587 * %eip's and %esp's can be set up in user mode. 588 * This causes a fault in kernel mode when the 589 * kernel tries to return to user mode. We want 590 * to get this fault so that we can fix the 591 * problem here and not have to check all the 592 * selectors and pointers when the user changes 593 * them. 594 */ 595 if (frame->tf_eip == (int)doreti_iret) { 596 frame->tf_eip = (int)doreti_iret_fault; 597 return; 598 } 599 if (type == T_STKFLT) 600 break; 601 602 if (frame->tf_eip == (int)doreti_popl_ds) { 603 frame->tf_eip = (int)doreti_popl_ds_fault; 604 return; 605 } 606 if (frame->tf_eip == (int)doreti_popl_es) { 607 frame->tf_eip = (int)doreti_popl_es_fault; 608 return; 609 } 610 if (frame->tf_eip == (int)doreti_popl_fs) { 611 frame->tf_eip = (int)doreti_popl_fs_fault; 612 return; 613 } 614 if (curpcb->pcb_onfault != NULL) { 615 frame->tf_eip = (int)curpcb->pcb_onfault; 616 return; 617 } 618 break; 619 620 case T_TSSFLT: 621 /* 622 * PSL_NT can be set in user mode and isn't cleared 623 * automatically when the kernel is entered. This 624 * causes a TSS fault when the kernel attempts to 625 * `iret' because the TSS link is uninitialized. We 626 * want to get this fault so that we can fix the 627 * problem here and not every time the kernel is 628 * entered. 629 */ 630 if (frame->tf_eflags & PSL_NT) { 631 frame->tf_eflags &= ~PSL_NT; 632 return; 633 } 634 break; 635 636 case T_TRCTRAP: /* debug exception */ 637 kernel_trctrap: 638 /* Clear any pending debug events. */ 639 dr6 = rdr6(); 640 load_dr6(0); 641 642 if (frame->tf_eip == (int)IDTVEC(lcall_syscall)) { 643 /* 644 * We've just entered system mode via the 645 * syscall lcall. Continue single stepping 646 * silently until the syscall handler has 647 * saved the flags. 648 */ 649 return; 650 } 651 if (frame->tf_eip == (int)IDTVEC(lcall_syscall) + 1) { 652 /* 653 * The syscall handler has now saved the 654 * flags. Stop single stepping it. 655 */ 656 frame->tf_eflags &= ~PSL_T; 657 return; 658 } 659 /* 660 * Ignore debug register exceptions due to 661 * accesses in the user's address space, which 662 * can happen under several conditions such as 663 * if a user sets a watchpoint on a buffer and 664 * then passes that buffer to a system call. 665 * We still want to get TRCTRAPS for addresses 666 * in kernel space because that is useful when 667 * debugging the kernel. 668 */ 669 if (user_dbreg_trap(dr6) && 670 !(curpcb->pcb_flags & PCB_VM86CALL)) 671 return; 672 673 /* 674 * Malicious user code can configure a debug 675 * register watchpoint to trap on data access 676 * to the top of stack and then execute 'pop 677 * %ss; int 3'. Due to exception deferral for 678 * 'pop %ss', the CPU will not interrupt 'int 679 * 3' to raise the DB# exception for the debug 680 * register but will postpone the DB# until 681 * execution of the first instruction of the 682 * BP# handler (in kernel mode). Normally the 683 * previous check would ignore DB# exceptions 684 * for watchpoints on user addresses raised in 685 * kernel mode. However, some CPU errata 686 * include cases where DB# exceptions do not 687 * properly set bits in %dr6, e.g. Haswell 688 * HSD23 and Skylake-X SKZ24. 689 * 690 * A deferred DB# can also be raised on the 691 * first instructions of system call entry 692 * points or single-step traps via similar use 693 * of 'pop %ss' or 'mov xxx, %ss'. 694 */ 695 if (frame->tf_eip == 696 (uintptr_t)IDTVEC(int0x80_syscall) || 697 frame->tf_eip == (uintptr_t)IDTVEC(bpt) || 698 frame->tf_eip == (uintptr_t)IDTVEC(dbg)) 699 return; 700 /* 701 * FALLTHROUGH (TRCTRAP kernel mode, kernel address) 702 */ 703 case T_BPTFLT: 704 /* 705 * If KDB is enabled, let it handle the debugger trap. 706 * Otherwise, debugger traps "can't happen". 707 */ 708 #ifdef KDB 709 if (kdb_trap(type, dr6, frame)) 710 return; 711 #endif 712 break; 713 714 #ifdef DEV_ISA 715 case T_NMI: 716 #ifdef POWERFAIL_NMI 717 if (time_second - lastalert > 10) { 718 log(LOG_WARNING, "NMI: power fail\n"); 719 sysbeep(880, hz); 720 lastalert = time_second; 721 } 722 return; 723 #else /* !POWERFAIL_NMI */ 724 nmi_handle_intr(type, frame); 725 return; 726 #endif /* POWERFAIL_NMI */ 727 #endif /* DEV_ISA */ 728 } 729 730 trap_fatal(frame, eva); 731 return; 732 } 733 734 /* Translate fault for emulators (e.g. Linux) */ 735 if (*p->p_sysent->sv_transtrap != NULL) 736 signo = (*p->p_sysent->sv_transtrap)(signo, type); 737 738 ksiginfo_init_trap(&ksi); 739 ksi.ksi_signo = signo; 740 ksi.ksi_code = ucode; 741 ksi.ksi_addr = (void *)addr; 742 ksi.ksi_trapno = type; 743 if (uprintf_signal) { 744 uprintf("pid %d comm %s: signal %d err %x code %d type %d " 745 "addr 0x%x esp 0x%08x eip 0x%08x " 746 "<%02x %02x %02x %02x %02x %02x %02x %02x>\n", 747 p->p_pid, p->p_comm, signo, frame->tf_err, ucode, type, 748 addr, frame->tf_esp, frame->tf_eip, 749 fubyte((void *)(frame->tf_eip + 0)), 750 fubyte((void *)(frame->tf_eip + 1)), 751 fubyte((void *)(frame->tf_eip + 2)), 752 fubyte((void *)(frame->tf_eip + 3)), 753 fubyte((void *)(frame->tf_eip + 4)), 754 fubyte((void *)(frame->tf_eip + 5)), 755 fubyte((void *)(frame->tf_eip + 6)), 756 fubyte((void *)(frame->tf_eip + 7))); 757 } 758 KASSERT((read_eflags() & PSL_I) != 0, ("interrupts disabled")); 759 trapsignal(td, &ksi); 760 761 user: 762 userret(td, frame); 763 KASSERT(PCB_USER_FPU(td->td_pcb), 764 ("Return from trap with kernel FPU ctx leaked")); 765 } 766 767 static int 768 trap_pfault(struct trapframe *frame, int usermode, vm_offset_t eva) 769 { 770 struct thread *td; 771 struct proc *p; 772 vm_offset_t va; 773 vm_map_t map; 774 int rv; 775 vm_prot_t ftype; 776 777 td = curthread; 778 p = td->td_proc; 779 780 if (__predict_false((td->td_pflags & TDP_NOFAULTING) != 0)) { 781 /* 782 * Due to both processor errata and lazy TLB invalidation when 783 * access restrictions are removed from virtual pages, memory 784 * accesses that are allowed by the physical mapping layer may 785 * nonetheless cause one spurious page fault per virtual page. 786 * When the thread is executing a "no faulting" section that 787 * is bracketed by vm_fault_{disable,enable}_pagefaults(), 788 * every page fault is treated as a spurious page fault, 789 * unless it accesses the same virtual address as the most 790 * recent page fault within the same "no faulting" section. 791 */ 792 if (td->td_md.md_spurflt_addr != eva || 793 (td->td_pflags & TDP_RESETSPUR) != 0) { 794 /* 795 * Do nothing to the TLB. A stale TLB entry is 796 * flushed automatically by a page fault. 797 */ 798 td->td_md.md_spurflt_addr = eva; 799 td->td_pflags &= ~TDP_RESETSPUR; 800 return (0); 801 } 802 } else { 803 /* 804 * If we get a page fault while in a critical section, then 805 * it is most likely a fatal kernel page fault. The kernel 806 * is already going to panic trying to get a sleep lock to 807 * do the VM lookup, so just consider it a fatal trap so the 808 * kernel can print out a useful trap message and even get 809 * to the debugger. 810 * 811 * If we get a page fault while holding a non-sleepable 812 * lock, then it is most likely a fatal kernel page fault. 813 * If WITNESS is enabled, then it's going to whine about 814 * bogus LORs with various VM locks, so just skip to the 815 * fatal trap handling directly. 816 */ 817 if (td->td_critnest != 0 || 818 WITNESS_CHECK(WARN_SLEEPOK | WARN_GIANTOK, NULL, 819 "Kernel page fault") != 0) { 820 trap_fatal(frame, eva); 821 return (-1); 822 } 823 } 824 va = trunc_page(eva); 825 if (va >= KERNBASE) { 826 /* 827 * Don't allow user-mode faults in kernel address space. 828 * An exception: if the faulting address is the invalid 829 * instruction entry in the IDT, then the Intel Pentium 830 * F00F bug workaround was triggered, and we need to 831 * treat it is as an illegal instruction, and not a page 832 * fault. 833 */ 834 #if defined(I586_CPU) && !defined(NO_F00F_HACK) 835 if ((eva == (unsigned int)&idt[6]) && has_f00f_bug) 836 return (-2); 837 #endif 838 if (usermode) 839 return (SIGSEGV); 840 841 map = kernel_map; 842 } else { 843 map = &p->p_vmspace->vm_map; 844 845 /* 846 * When accessing a user-space address, kernel must be 847 * ready to accept the page fault, and provide a 848 * handling routine. Since accessing the address 849 * without the handler is a bug, do not try to handle 850 * it normally, and panic immediately. 851 */ 852 if (!usermode && (td->td_intr_nesting_level != 0 || 853 curpcb->pcb_onfault == NULL)) { 854 trap_fatal(frame, eva); 855 return (-1); 856 } 857 } 858 859 /* 860 * If the trap was caused by errant bits in the PTE then panic. 861 */ 862 if (frame->tf_err & PGEX_RSV) { 863 trap_fatal(frame, eva); 864 return (-1); 865 } 866 867 /* 868 * PGEX_I is defined only if the execute disable bit capability is 869 * supported and enabled. 870 */ 871 if (frame->tf_err & PGEX_W) 872 ftype = VM_PROT_WRITE; 873 #if defined(PAE) || defined(PAE_TABLES) 874 else if ((frame->tf_err & PGEX_I) && pg_nx != 0) 875 ftype = VM_PROT_EXECUTE; 876 #endif 877 else 878 ftype = VM_PROT_READ; 879 880 /* Fault in the page. */ 881 rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL); 882 if (rv == KERN_SUCCESS) { 883 #ifdef HWPMC_HOOKS 884 if (ftype == VM_PROT_READ || ftype == VM_PROT_WRITE) { 885 PMC_SOFT_CALL_TF( , , page_fault, all, frame); 886 if (ftype == VM_PROT_READ) 887 PMC_SOFT_CALL_TF( , , page_fault, read, 888 frame); 889 else 890 PMC_SOFT_CALL_TF( , , page_fault, write, 891 frame); 892 } 893 #endif 894 return (0); 895 } 896 if (!usermode) { 897 if (td->td_intr_nesting_level == 0 && 898 curpcb->pcb_onfault != NULL) { 899 frame->tf_eip = (int)curpcb->pcb_onfault; 900 return (0); 901 } 902 trap_fatal(frame, eva); 903 return (-1); 904 } 905 return ((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV); 906 } 907 908 static void 909 trap_fatal(frame, eva) 910 struct trapframe *frame; 911 vm_offset_t eva; 912 { 913 int code, ss, esp; 914 u_int type; 915 struct soft_segment_descriptor softseg; 916 char *msg; 917 #ifdef KDB 918 bool handled; 919 #endif 920 921 code = frame->tf_err; 922 type = frame->tf_trapno; 923 sdtossd(&gdt[IDXSEL(frame->tf_cs & 0xffff)].sd, &softseg); 924 925 if (type <= MAX_TRAP_MSG) 926 msg = trap_msg[type]; 927 else 928 msg = "UNKNOWN"; 929 printf("\n\nFatal trap %d: %s while in %s mode\n", type, msg, 930 frame->tf_eflags & PSL_VM ? "vm86" : 931 ISPL(frame->tf_cs) == SEL_UPL ? "user" : "kernel"); 932 #ifdef SMP 933 /* two separate prints in case of a trap on an unmapped page */ 934 printf("cpuid = %d; ", PCPU_GET(cpuid)); 935 printf("apic id = %02x\n", PCPU_GET(apic_id)); 936 #endif 937 if (type == T_PAGEFLT) { 938 printf("fault virtual address = 0x%x\n", eva); 939 printf("fault code = %s %s%s, %s\n", 940 code & PGEX_U ? "user" : "supervisor", 941 code & PGEX_W ? "write" : "read", 942 #if defined(PAE) || defined(PAE_TABLES) 943 pg_nx != 0 ? 944 (code & PGEX_I ? " instruction" : " data") : 945 #endif 946 "", 947 code & PGEX_RSV ? "reserved bits in PTE" : 948 code & PGEX_P ? "protection violation" : "page not present"); 949 } else { 950 printf("error code = %#x\n", code); 951 } 952 printf("instruction pointer = 0x%x:0x%x\n", 953 frame->tf_cs & 0xffff, frame->tf_eip); 954 if (TF_HAS_STACKREGS(frame)) { 955 ss = frame->tf_ss & 0xffff; 956 esp = frame->tf_esp; 957 } else { 958 ss = GSEL(GDATA_SEL, SEL_KPL); 959 esp = (int)&frame->tf_esp; 960 } 961 printf("stack pointer = 0x%x:0x%x\n", ss, esp); 962 printf("frame pointer = 0x%x:0x%x\n", ss, frame->tf_ebp); 963 printf("code segment = base 0x%x, limit 0x%x, type 0x%x\n", 964 softseg.ssd_base, softseg.ssd_limit, softseg.ssd_type); 965 printf(" = DPL %d, pres %d, def32 %d, gran %d\n", 966 softseg.ssd_dpl, softseg.ssd_p, softseg.ssd_def32, 967 softseg.ssd_gran); 968 printf("processor eflags = "); 969 if (frame->tf_eflags & PSL_T) 970 printf("trace trap, "); 971 if (frame->tf_eflags & PSL_I) 972 printf("interrupt enabled, "); 973 if (frame->tf_eflags & PSL_NT) 974 printf("nested task, "); 975 if (frame->tf_eflags & PSL_RF) 976 printf("resume, "); 977 if (frame->tf_eflags & PSL_VM) 978 printf("vm86, "); 979 printf("IOPL = %d\n", (frame->tf_eflags & PSL_IOPL) >> 12); 980 printf("current process = %d (%s)\n", 981 curproc->p_pid, curthread->td_name); 982 983 #ifdef KDB 984 if (debugger_on_trap) { 985 kdb_why = KDB_WHY_TRAP; 986 frame->tf_err = eva; /* smuggle fault address to ddb */ 987 handled = kdb_trap(type, 0, frame); 988 frame->tf_err = code; /* restore error code */ 989 kdb_why = KDB_WHY_UNSET; 990 if (handled) 991 return; 992 } 993 #endif 994 printf("trap number = %d\n", type); 995 if (type <= MAX_TRAP_MSG) 996 panic("%s", trap_msg[type]); 997 else 998 panic("unknown/reserved trap"); 999 } 1000 1001 /* 1002 * Double fault handler. Called when a fault occurs while writing 1003 * a frame for a trap/exception onto the stack. This usually occurs 1004 * when the stack overflows (such is the case with infinite recursion, 1005 * for example). 1006 * 1007 * XXX Note that the current PTD gets replaced by IdlePTD when the 1008 * task switch occurs. This means that the stack that was active at 1009 * the time of the double fault is not available at <kstack> unless 1010 * the machine was idle when the double fault occurred. The downside 1011 * of this is that "trace <ebp>" in ddb won't work. 1012 */ 1013 void 1014 dblfault_handler() 1015 { 1016 #ifdef KDTRACE_HOOKS 1017 if (dtrace_doubletrap_func != NULL) 1018 (*dtrace_doubletrap_func)(); 1019 #endif 1020 printf("\nFatal double fault:\n"); 1021 printf("eip = 0x%x\n", PCPU_GET(common_tss.tss_eip)); 1022 printf("esp = 0x%x\n", PCPU_GET(common_tss.tss_esp)); 1023 printf("ebp = 0x%x\n", PCPU_GET(common_tss.tss_ebp)); 1024 #ifdef SMP 1025 /* two separate prints in case of a trap on an unmapped page */ 1026 printf("cpuid = %d; ", PCPU_GET(cpuid)); 1027 printf("apic id = %02x\n", PCPU_GET(apic_id)); 1028 #endif 1029 panic("double fault"); 1030 } 1031 1032 int 1033 cpu_fetch_syscall_args(struct thread *td) 1034 { 1035 struct proc *p; 1036 struct trapframe *frame; 1037 struct syscall_args *sa; 1038 caddr_t params; 1039 long tmp; 1040 int error; 1041 1042 p = td->td_proc; 1043 frame = td->td_frame; 1044 sa = &td->td_sa; 1045 1046 params = (caddr_t)frame->tf_esp + sizeof(int); 1047 sa->code = frame->tf_eax; 1048 1049 /* 1050 * Need to check if this is a 32 bit or 64 bit syscall. 1051 */ 1052 if (sa->code == SYS_syscall) { 1053 /* 1054 * Code is first argument, followed by actual args. 1055 */ 1056 error = fueword(params, &tmp); 1057 if (error == -1) 1058 return (EFAULT); 1059 sa->code = tmp; 1060 params += sizeof(int); 1061 } else if (sa->code == SYS___syscall) { 1062 /* 1063 * Like syscall, but code is a quad, so as to maintain 1064 * quad alignment for the rest of the arguments. 1065 */ 1066 error = fueword(params, &tmp); 1067 if (error == -1) 1068 return (EFAULT); 1069 sa->code = tmp; 1070 params += sizeof(quad_t); 1071 } 1072 1073 if (p->p_sysent->sv_mask) 1074 sa->code &= p->p_sysent->sv_mask; 1075 if (sa->code >= p->p_sysent->sv_size) 1076 sa->callp = &p->p_sysent->sv_table[0]; 1077 else 1078 sa->callp = &p->p_sysent->sv_table[sa->code]; 1079 sa->narg = sa->callp->sy_narg; 1080 1081 if (params != NULL && sa->narg != 0) 1082 error = copyin(params, (caddr_t)sa->args, 1083 (u_int)(sa->narg * sizeof(int))); 1084 else 1085 error = 0; 1086 1087 if (error == 0) { 1088 td->td_retval[0] = 0; 1089 td->td_retval[1] = frame->tf_edx; 1090 } 1091 1092 return (error); 1093 } 1094 1095 #include "../../kern/subr_syscall.c" 1096 1097 /* 1098 * syscall - system call request C handler. A system call is 1099 * essentially treated as a trap by reusing the frame layout. 1100 */ 1101 void 1102 syscall(struct trapframe *frame) 1103 { 1104 struct thread *td; 1105 register_t orig_tf_eflags; 1106 int error; 1107 ksiginfo_t ksi; 1108 1109 #ifdef DIAGNOSTIC 1110 if (!(TRAPF_USERMODE(frame) && 1111 (curpcb->pcb_flags & PCB_VM86CALL) == 0)) { 1112 panic("syscall"); 1113 /* NOT REACHED */ 1114 } 1115 #endif 1116 orig_tf_eflags = frame->tf_eflags; 1117 1118 td = curthread; 1119 td->td_frame = frame; 1120 1121 error = syscallenter(td); 1122 1123 /* 1124 * Traced syscall. 1125 */ 1126 if ((orig_tf_eflags & PSL_T) && !(orig_tf_eflags & PSL_VM)) { 1127 frame->tf_eflags &= ~PSL_T; 1128 ksiginfo_init_trap(&ksi); 1129 ksi.ksi_signo = SIGTRAP; 1130 ksi.ksi_code = TRAP_TRACE; 1131 ksi.ksi_addr = (void *)frame->tf_eip; 1132 trapsignal(td, &ksi); 1133 } 1134 1135 KASSERT(PCB_USER_FPU(td->td_pcb), 1136 ("System call %s returning with kernel FPU ctx leaked", 1137 syscallname(td->td_proc, td->td_sa.code))); 1138 KASSERT(td->td_pcb->pcb_save == get_pcb_user_save_td(td), 1139 ("System call %s returning with mangled pcb_save", 1140 syscallname(td->td_proc, td->td_sa.code))); 1141 1142 syscallret(td, error); 1143 }
Cache object: 088fdd47da4de522cef8a50634065a25
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