Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/amd64/amd64/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/11.1/sys/amd64/amd64/trap.c 333371 2018-05-08 17:12:10Z gordon $"); 42 43 /* 44 * AMD64 Trap and System call handling 45 */ 46 47 #include "opt_clock.h" 48 #include "opt_compat.h" 49 #include "opt_cpu.h" 50 #include "opt_hwpmc_hooks.h" 51 #include "opt_isa.h" 52 #include "opt_kdb.h" 53 #include "opt_stack.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 80 #include <vm/vm.h> 81 #include <vm/vm_param.h> 82 #include <vm/pmap.h> 83 #include <vm/vm_kern.h> 84 #include <vm/vm_map.h> 85 #include <vm/vm_page.h> 86 #include <vm/vm_extern.h> 87 88 #include <machine/cpu.h> 89 #include <machine/intr_machdep.h> 90 #include <x86/mca.h> 91 #include <machine/md_var.h> 92 #include <machine/pcb.h> 93 #ifdef SMP 94 #include <machine/smp.h> 95 #endif 96 #include <machine/stack.h> 97 #include <machine/tss.h> 98 99 #ifdef KDTRACE_HOOKS 100 #include <sys/dtrace_bsd.h> 101 #endif 102 103 extern inthand_t IDTVEC(bpt), IDTVEC(bpt_pti), IDTVEC(dbg), 104 IDTVEC(fast_syscall), IDTVEC(fast_syscall_pti), IDTVEC(fast_syscall32), 105 IDTVEC(int0x80_syscall_pti), IDTVEC(int0x80_syscall); 106 107 108 extern void __noinline trap(struct trapframe *frame); 109 extern void trap_check(struct trapframe *frame); 110 extern void syscall(struct trapframe *frame); 111 void dblfault_handler(struct trapframe *frame); 112 113 static int trap_pfault(struct trapframe *, int); 114 static void trap_fatal(struct trapframe *, vm_offset_t); 115 116 #define MAX_TRAP_MSG 32 117 static char *trap_msg[] = { 118 "", /* 0 unused */ 119 "privileged instruction fault", /* 1 T_PRIVINFLT */ 120 "", /* 2 unused */ 121 "breakpoint instruction fault", /* 3 T_BPTFLT */ 122 "", /* 4 unused */ 123 "", /* 5 unused */ 124 "arithmetic trap", /* 6 T_ARITHTRAP */ 125 "", /* 7 unused */ 126 "", /* 8 unused */ 127 "general protection fault", /* 9 T_PROTFLT */ 128 "trace trap", /* 10 T_TRCTRAP */ 129 "", /* 11 unused */ 130 "page fault", /* 12 T_PAGEFLT */ 131 "", /* 13 unused */ 132 "alignment fault", /* 14 T_ALIGNFLT */ 133 "", /* 15 unused */ 134 "", /* 16 unused */ 135 "", /* 17 unused */ 136 "integer divide fault", /* 18 T_DIVIDE */ 137 "non-maskable interrupt trap", /* 19 T_NMI */ 138 "overflow trap", /* 20 T_OFLOW */ 139 "FPU bounds check fault", /* 21 T_BOUND */ 140 "FPU device not available", /* 22 T_DNA */ 141 "double fault", /* 23 T_DOUBLEFLT */ 142 "FPU operand fetch fault", /* 24 T_FPOPFLT */ 143 "invalid TSS fault", /* 25 T_TSSFLT */ 144 "segment not present fault", /* 26 T_SEGNPFLT */ 145 "stack fault", /* 27 T_STKFLT */ 146 "machine check trap", /* 28 T_MCHK */ 147 "SIMD floating-point exception", /* 29 T_XMMFLT */ 148 "reserved (unknown) fault", /* 30 T_RESERVED */ 149 "", /* 31 unused (reserved) */ 150 "DTrace pid return trap", /* 32 T_DTRACE_RET */ 151 }; 152 153 static int prot_fault_translation; 154 SYSCTL_INT(_machdep, OID_AUTO, prot_fault_translation, CTLFLAG_RWTUN, 155 &prot_fault_translation, 0, 156 "Select signal to deliver on protection fault"); 157 static int uprintf_signal; 158 SYSCTL_INT(_machdep, OID_AUTO, uprintf_signal, CTLFLAG_RWTUN, 159 &uprintf_signal, 0, 160 "Print debugging information on trap signal to ctty"); 161 162 /* 163 * Exception, fault, and trap interface to the FreeBSD kernel. 164 * This common code is called from assembly language IDT gate entry 165 * routines that prepare a suitable stack frame, and restore this 166 * frame after the exception has been processed. 167 */ 168 169 void 170 trap(struct trapframe *frame) 171 { 172 #ifdef KDTRACE_HOOKS 173 struct reg regs; 174 #endif 175 struct thread *td = curthread; 176 struct proc *p = td->td_proc; 177 #ifdef KDB 178 register_t dr6; 179 #endif 180 int i = 0, ucode = 0; 181 u_int type; 182 register_t addr = 0; 183 ksiginfo_t ksi; 184 185 PCPU_INC(cnt.v_trap); 186 type = frame->tf_trapno; 187 188 #ifdef SMP 189 /* Handler for NMI IPIs used for stopping CPUs. */ 190 if (type == T_NMI) { 191 if (ipi_nmi_handler() == 0) 192 goto out; 193 } 194 #endif /* SMP */ 195 196 #ifdef KDB 197 if (kdb_active) { 198 kdb_reenter(); 199 goto out; 200 } 201 #endif 202 203 if (type == T_RESERVED) { 204 trap_fatal(frame, 0); 205 goto out; 206 } 207 208 if (type == T_NMI) { 209 #ifdef HWPMC_HOOKS 210 /* 211 * CPU PMCs interrupt using an NMI. If the PMC module is 212 * active, pass the 'rip' value to the PMC module's interrupt 213 * handler. A non-zero return value from the handler means that 214 * the NMI was consumed by it and we can return immediately. 215 */ 216 if (pmc_intr != NULL && 217 (*pmc_intr)(PCPU_GET(cpuid), frame) != 0) 218 goto out; 219 #endif 220 221 #ifdef STACK 222 if (stack_nmi_handler(frame) != 0) 223 goto out; 224 #endif 225 } 226 227 if ((frame->tf_rflags & PSL_I) == 0) { 228 /* 229 * Buggy application or kernel code has disabled 230 * interrupts and then trapped. Enabling interrupts 231 * now is wrong, but it is better than running with 232 * interrupts disabled until they are accidentally 233 * enabled later. 234 */ 235 if (TRAPF_USERMODE(frame)) 236 uprintf( 237 "pid %ld (%s): trap %d with interrupts disabled\n", 238 (long)curproc->p_pid, curthread->td_name, type); 239 else if (type != T_NMI && type != T_BPTFLT && 240 type != T_TRCTRAP) { 241 /* 242 * XXX not quite right, since this may be for a 243 * multiple fault in user mode. 244 */ 245 printf("kernel trap %d with interrupts disabled\n", 246 type); 247 248 /* 249 * We shouldn't enable interrupts while holding a 250 * spin lock. 251 */ 252 if (td->td_md.md_spinlock_count == 0) 253 enable_intr(); 254 } 255 } 256 257 if (TRAPF_USERMODE(frame)) { 258 /* user trap */ 259 260 td->td_pticks = 0; 261 td->td_frame = frame; 262 addr = frame->tf_rip; 263 if (td->td_cowgen != p->p_cowgen) 264 thread_cow_update(td); 265 266 switch (type) { 267 case T_PRIVINFLT: /* privileged instruction fault */ 268 i = SIGILL; 269 ucode = ILL_PRVOPC; 270 break; 271 272 case T_BPTFLT: /* bpt instruction fault */ 273 case T_TRCTRAP: /* trace trap */ 274 enable_intr(); 275 #ifdef KDTRACE_HOOKS 276 if (type == T_BPTFLT) { 277 fill_frame_regs(frame, ®s); 278 if (dtrace_pid_probe_ptr != NULL && 279 dtrace_pid_probe_ptr(®s) == 0) 280 goto out; 281 } 282 #endif 283 frame->tf_rflags &= ~PSL_T; 284 i = SIGTRAP; 285 ucode = (type == T_TRCTRAP ? TRAP_TRACE : TRAP_BRKPT); 286 break; 287 288 case T_ARITHTRAP: /* arithmetic trap */ 289 ucode = fputrap_x87(); 290 if (ucode == -1) 291 goto userout; 292 i = SIGFPE; 293 break; 294 295 case T_PROTFLT: /* general protection fault */ 296 i = SIGBUS; 297 ucode = BUS_OBJERR; 298 break; 299 case T_STKFLT: /* stack fault */ 300 case T_SEGNPFLT: /* segment not present fault */ 301 i = SIGBUS; 302 ucode = BUS_ADRERR; 303 break; 304 case T_TSSFLT: /* invalid TSS fault */ 305 i = SIGBUS; 306 ucode = BUS_OBJERR; 307 break; 308 case T_ALIGNFLT: 309 i = SIGBUS; 310 ucode = BUS_ADRALN; 311 break; 312 case T_DOUBLEFLT: /* double fault */ 313 default: 314 i = SIGBUS; 315 ucode = BUS_OBJERR; 316 break; 317 318 case T_PAGEFLT: /* page fault */ 319 /* 320 * Emulator can take care about this trap? 321 */ 322 if (*p->p_sysent->sv_trap != NULL && 323 (*p->p_sysent->sv_trap)(td) == 0) 324 goto userout; 325 326 addr = frame->tf_addr; 327 i = trap_pfault(frame, TRUE); 328 if (i == -1) 329 goto userout; 330 if (i == 0) 331 goto user; 332 333 if (i == SIGSEGV) 334 ucode = SEGV_MAPERR; 335 else { 336 if (prot_fault_translation == 0) { 337 /* 338 * Autodetect. 339 * This check also covers the images 340 * without the ABI-tag ELF note. 341 */ 342 if (SV_CURPROC_ABI() == SV_ABI_FREEBSD 343 && p->p_osrel >= P_OSREL_SIGSEGV) { 344 i = SIGSEGV; 345 ucode = SEGV_ACCERR; 346 } else { 347 i = SIGBUS; 348 ucode = BUS_PAGE_FAULT; 349 } 350 } else if (prot_fault_translation == 1) { 351 /* 352 * Always compat mode. 353 */ 354 i = SIGBUS; 355 ucode = BUS_PAGE_FAULT; 356 } else { 357 /* 358 * Always SIGSEGV mode. 359 */ 360 i = SIGSEGV; 361 ucode = SEGV_ACCERR; 362 } 363 } 364 break; 365 366 case T_DIVIDE: /* integer divide fault */ 367 ucode = FPE_INTDIV; 368 i = SIGFPE; 369 break; 370 371 #ifdef DEV_ISA 372 case T_NMI: 373 nmi_handle_intr(type, frame); 374 break; 375 #endif /* DEV_ISA */ 376 377 case T_OFLOW: /* integer overflow fault */ 378 ucode = FPE_INTOVF; 379 i = SIGFPE; 380 break; 381 382 case T_BOUND: /* bounds check fault */ 383 ucode = FPE_FLTSUB; 384 i = SIGFPE; 385 break; 386 387 case T_DNA: 388 /* transparent fault (due to context switch "late") */ 389 KASSERT(PCB_USER_FPU(td->td_pcb), 390 ("kernel FPU ctx has leaked")); 391 fpudna(); 392 goto userout; 393 394 case T_FPOPFLT: /* FPU operand fetch fault */ 395 ucode = ILL_COPROC; 396 i = SIGILL; 397 break; 398 399 case T_XMMFLT: /* SIMD floating-point exception */ 400 ucode = fputrap_sse(); 401 if (ucode == -1) 402 goto userout; 403 i = SIGFPE; 404 break; 405 #ifdef KDTRACE_HOOKS 406 case T_DTRACE_RET: 407 enable_intr(); 408 fill_frame_regs(frame, ®s); 409 if (dtrace_return_probe_ptr != NULL && 410 dtrace_return_probe_ptr(®s) == 0) 411 goto out; 412 break; 413 #endif 414 } 415 } else { 416 /* kernel trap */ 417 418 KASSERT(cold || td->td_ucred != NULL, 419 ("kernel trap doesn't have ucred")); 420 switch (type) { 421 case T_PAGEFLT: /* page fault */ 422 (void) trap_pfault(frame, FALSE); 423 goto out; 424 425 case T_DNA: 426 if (PCB_USER_FPU(td->td_pcb)) 427 panic("Unregistered use of FPU in kernel"); 428 fpudna(); 429 goto out; 430 431 case T_ARITHTRAP: /* arithmetic trap */ 432 case T_XMMFLT: /* SIMD floating-point exception */ 433 case T_FPOPFLT: /* FPU operand fetch fault */ 434 /* 435 * For now, supporting kernel handler 436 * registration for FPU traps is overkill. 437 */ 438 trap_fatal(frame, 0); 439 goto out; 440 441 case T_STKFLT: /* stack fault */ 442 case T_PROTFLT: /* general protection fault */ 443 case T_SEGNPFLT: /* segment not present fault */ 444 if (td->td_intr_nesting_level != 0) 445 break; 446 447 /* 448 * Invalid segment selectors and out of bounds 449 * %rip's and %rsp's can be set up in user mode. 450 * This causes a fault in kernel mode when the 451 * kernel tries to return to user mode. We want 452 * to get this fault so that we can fix the 453 * problem here and not have to check all the 454 * selectors and pointers when the user changes 455 * them. 456 * 457 * In case of PTI, the IRETQ faulted while the 458 * kernel used the pti stack, and exception 459 * frame records %rsp value pointing to that 460 * stack. If we return normally to 461 * doreti_iret_fault, the trapframe is 462 * reconstructed on pti stack, and calltrap() 463 * called on it as well. Due to the very 464 * limited pti stack size, kernel does not 465 * survive for too long. Switch to the normal 466 * thread stack for the trap handling. 467 * 468 * Magic '5' is the number of qwords occupied by 469 * the hardware trap frame. 470 */ 471 if (frame->tf_rip == (long)doreti_iret) { 472 frame->tf_rip = (long)doreti_iret_fault; 473 if (pti && frame->tf_rsp == (uintptr_t)PCPU_PTR( 474 pti_stack) + (PC_PTI_STACK_SZ - 5) * 475 sizeof(register_t)) 476 frame->tf_rsp = PCPU_GET(rsp0) - 5 * 477 sizeof(register_t); 478 goto out; 479 } 480 if (frame->tf_rip == (long)ld_ds) { 481 frame->tf_rip = (long)ds_load_fault; 482 goto out; 483 } 484 if (frame->tf_rip == (long)ld_es) { 485 frame->tf_rip = (long)es_load_fault; 486 goto out; 487 } 488 if (frame->tf_rip == (long)ld_fs) { 489 frame->tf_rip = (long)fs_load_fault; 490 goto out; 491 } 492 if (frame->tf_rip == (long)ld_gs) { 493 frame->tf_rip = (long)gs_load_fault; 494 goto out; 495 } 496 if (frame->tf_rip == (long)ld_gsbase) { 497 frame->tf_rip = (long)gsbase_load_fault; 498 goto out; 499 } 500 if (frame->tf_rip == (long)ld_fsbase) { 501 frame->tf_rip = (long)fsbase_load_fault; 502 goto out; 503 } 504 if (curpcb->pcb_onfault != NULL) { 505 frame->tf_rip = (long)curpcb->pcb_onfault; 506 goto out; 507 } 508 break; 509 510 case T_TSSFLT: 511 /* 512 * PSL_NT can be set in user mode and isn't cleared 513 * automatically when the kernel is entered. This 514 * causes a TSS fault when the kernel attempts to 515 * `iret' because the TSS link is uninitialized. We 516 * want to get this fault so that we can fix the 517 * problem here and not every time the kernel is 518 * entered. 519 */ 520 if (frame->tf_rflags & PSL_NT) { 521 frame->tf_rflags &= ~PSL_NT; 522 goto out; 523 } 524 break; 525 526 case T_TRCTRAP: /* trace trap */ 527 /* 528 * Ignore debug register trace traps due to 529 * accesses in the user's address space, which 530 * can happen under several conditions such as 531 * if a user sets a watchpoint on a buffer and 532 * then passes that buffer to a system call. 533 * We still want to get TRCTRAPS for addresses 534 * in kernel space because that is useful when 535 * debugging the kernel. 536 */ 537 if (user_dbreg_trap()) { 538 /* 539 * Reset breakpoint bits because the 540 * processor doesn't 541 */ 542 load_dr6(rdr6() & ~0xf); 543 goto out; 544 } 545 546 /* 547 * Malicious user code can configure a debug 548 * register watchpoint to trap on data access 549 * to the top of stack and then execute 'pop 550 * %ss; int 3'. Due to exception deferral for 551 * 'pop %ss', the CPU will not interrupt 'int 552 * 3' to raise the DB# exception for the debug 553 * register but will postpone the DB# until 554 * execution of the first instruction of the 555 * BP# handler (in kernel mode). Normally the 556 * previous check would ignore DB# exceptions 557 * for watchpoints on user addresses raised in 558 * kernel mode. However, some CPU errata 559 * include cases where DB# exceptions do not 560 * properly set bits in %dr6, e.g. Haswell 561 * HSD23 and Skylake-X SKZ24. 562 * 563 * A deferred DB# can also be raised on the 564 * first instructions of system call entry 565 * points or single-step traps via similar use 566 * of 'pop %ss' or 'mov xxx, %ss'. 567 */ 568 if (pti) { 569 if (frame->tf_rip == 570 (uintptr_t)IDTVEC(fast_syscall_pti) || 571 #ifdef COMPAT_FREEBSD32 572 frame->tf_rip == 573 (uintptr_t)IDTVEC(int0x80_syscall_pti) || 574 #endif 575 frame->tf_rip == (uintptr_t)IDTVEC(bpt_pti)) 576 return; 577 } else { 578 if (frame->tf_rip == 579 (uintptr_t)IDTVEC(fast_syscall) || 580 #ifdef COMPAT_FREEBSD32 581 frame->tf_rip == 582 (uintptr_t)IDTVEC(int0x80_syscall) || 583 #endif 584 frame->tf_rip == (uintptr_t)IDTVEC(bpt)) 585 return; 586 } 587 if (frame->tf_rip == (uintptr_t)IDTVEC(dbg) || 588 /* Needed for AMD. */ 589 frame->tf_rip == (uintptr_t)IDTVEC(fast_syscall32)) 590 return; 591 /* 592 * FALLTHROUGH (TRCTRAP kernel mode, kernel address) 593 */ 594 case T_BPTFLT: 595 /* 596 * If KDB is enabled, let it handle the debugger trap. 597 * Otherwise, debugger traps "can't happen". 598 */ 599 #ifdef KDB 600 /* XXX %dr6 is not quite reentrant. */ 601 dr6 = rdr6(); 602 load_dr6(dr6 & ~0x4000); 603 if (kdb_trap(type, dr6, frame)) 604 goto out; 605 #endif 606 break; 607 608 #ifdef DEV_ISA 609 case T_NMI: 610 nmi_handle_intr(type, frame); 611 goto out; 612 #endif /* DEV_ISA */ 613 } 614 615 trap_fatal(frame, 0); 616 goto out; 617 } 618 619 /* Translate fault for emulators (e.g. Linux) */ 620 if (*p->p_sysent->sv_transtrap) 621 i = (*p->p_sysent->sv_transtrap)(i, type); 622 623 ksiginfo_init_trap(&ksi); 624 ksi.ksi_signo = i; 625 ksi.ksi_code = ucode; 626 ksi.ksi_trapno = type; 627 ksi.ksi_addr = (void *)addr; 628 if (uprintf_signal) { 629 uprintf("pid %d comm %s: signal %d err %lx code %d type %d " 630 "addr 0x%lx rsp 0x%lx rip 0x%lx " 631 "<%02x %02x %02x %02x %02x %02x %02x %02x>\n", 632 p->p_pid, p->p_comm, i, frame->tf_err, ucode, type, addr, 633 frame->tf_rsp, frame->tf_rip, 634 fubyte((void *)(frame->tf_rip + 0)), 635 fubyte((void *)(frame->tf_rip + 1)), 636 fubyte((void *)(frame->tf_rip + 2)), 637 fubyte((void *)(frame->tf_rip + 3)), 638 fubyte((void *)(frame->tf_rip + 4)), 639 fubyte((void *)(frame->tf_rip + 5)), 640 fubyte((void *)(frame->tf_rip + 6)), 641 fubyte((void *)(frame->tf_rip + 7))); 642 } 643 KASSERT((read_rflags() & PSL_I) != 0, ("interrupts disabled")); 644 trapsignal(td, &ksi); 645 646 user: 647 userret(td, frame); 648 KASSERT(PCB_USER_FPU(td->td_pcb), 649 ("Return from trap with kernel FPU ctx leaked")); 650 userout: 651 out: 652 return; 653 } 654 655 /* 656 * Ensure that we ignore any DTrace-induced faults. This function cannot 657 * be instrumented, so it cannot generate such faults itself. 658 */ 659 void 660 trap_check(struct trapframe *frame) 661 { 662 663 #ifdef KDTRACE_HOOKS 664 if (dtrace_trap_func != NULL && 665 (*dtrace_trap_func)(frame, frame->tf_trapno) != 0) 666 return; 667 #endif 668 trap(frame); 669 } 670 671 static int 672 trap_pfault(frame, usermode) 673 struct trapframe *frame; 674 int usermode; 675 { 676 vm_offset_t va; 677 vm_map_t map; 678 int rv = 0; 679 vm_prot_t ftype; 680 struct thread *td = curthread; 681 struct proc *p = td->td_proc; 682 vm_offset_t eva = frame->tf_addr; 683 684 if (__predict_false((td->td_pflags & TDP_NOFAULTING) != 0)) { 685 /* 686 * Due to both processor errata and lazy TLB invalidation when 687 * access restrictions are removed from virtual pages, memory 688 * accesses that are allowed by the physical mapping layer may 689 * nonetheless cause one spurious page fault per virtual page. 690 * When the thread is executing a "no faulting" section that 691 * is bracketed by vm_fault_{disable,enable}_pagefaults(), 692 * every page fault is treated as a spurious page fault, 693 * unless it accesses the same virtual address as the most 694 * recent page fault within the same "no faulting" section. 695 */ 696 if (td->td_md.md_spurflt_addr != eva || 697 (td->td_pflags & TDP_RESETSPUR) != 0) { 698 /* 699 * Do nothing to the TLB. A stale TLB entry is 700 * flushed automatically by a page fault. 701 */ 702 td->td_md.md_spurflt_addr = eva; 703 td->td_pflags &= ~TDP_RESETSPUR; 704 return (0); 705 } 706 } else { 707 /* 708 * If we get a page fault while in a critical section, then 709 * it is most likely a fatal kernel page fault. The kernel 710 * is already going to panic trying to get a sleep lock to 711 * do the VM lookup, so just consider it a fatal trap so the 712 * kernel can print out a useful trap message and even get 713 * to the debugger. 714 * 715 * If we get a page fault while holding a non-sleepable 716 * lock, then it is most likely a fatal kernel page fault. 717 * If WITNESS is enabled, then it's going to whine about 718 * bogus LORs with various VM locks, so just skip to the 719 * fatal trap handling directly. 720 */ 721 if (td->td_critnest != 0 || 722 WITNESS_CHECK(WARN_SLEEPOK | WARN_GIANTOK, NULL, 723 "Kernel page fault") != 0) { 724 trap_fatal(frame, eva); 725 return (-1); 726 } 727 } 728 va = trunc_page(eva); 729 if (va >= VM_MIN_KERNEL_ADDRESS) { 730 /* 731 * Don't allow user-mode faults in kernel address space. 732 */ 733 if (usermode) 734 goto nogo; 735 736 map = kernel_map; 737 } else { 738 map = &p->p_vmspace->vm_map; 739 740 /* 741 * When accessing a usermode address, kernel must be 742 * ready to accept the page fault, and provide a 743 * handling routine. Since accessing the address 744 * without the handler is a bug, do not try to handle 745 * it normally, and panic immediately. 746 */ 747 if (!usermode && (td->td_intr_nesting_level != 0 || 748 curpcb->pcb_onfault == NULL)) { 749 trap_fatal(frame, eva); 750 return (-1); 751 } 752 } 753 754 /* 755 * If the trap was caused by errant bits in the PTE then panic. 756 */ 757 if (frame->tf_err & PGEX_RSV) { 758 trap_fatal(frame, eva); 759 return (-1); 760 } 761 762 /* 763 * If nx protection of the usermode portion of kernel page 764 * tables caused trap, panic. 765 */ 766 if (pti && usermode && pg_nx != 0 && (frame->tf_err & (PGEX_P | PGEX_W | 767 PGEX_U | PGEX_I)) == (PGEX_P | PGEX_U | PGEX_I) && 768 (curpcb->pcb_saved_ucr3 & ~CR3_PCID_MASK)== 769 (PCPU_GET(curpmap)->pm_cr3 & ~CR3_PCID_MASK)) 770 panic("PTI: pid %d comm %s tf_err %#lx\n", p->p_pid, 771 p->p_comm, frame->tf_err); 772 773 /* 774 * PGEX_I is defined only if the execute disable bit capability is 775 * supported and enabled. 776 */ 777 if (frame->tf_err & PGEX_W) 778 ftype = VM_PROT_WRITE; 779 else if ((frame->tf_err & PGEX_I) && pg_nx != 0) 780 ftype = VM_PROT_EXECUTE; 781 else 782 ftype = VM_PROT_READ; 783 784 /* Fault in the page. */ 785 rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL); 786 if (rv == KERN_SUCCESS) { 787 #ifdef HWPMC_HOOKS 788 if (ftype == VM_PROT_READ || ftype == VM_PROT_WRITE) { 789 PMC_SOFT_CALL_TF( , , page_fault, all, frame); 790 if (ftype == VM_PROT_READ) 791 PMC_SOFT_CALL_TF( , , page_fault, read, 792 frame); 793 else 794 PMC_SOFT_CALL_TF( , , page_fault, write, 795 frame); 796 } 797 #endif 798 return (0); 799 } 800 nogo: 801 if (!usermode) { 802 if (td->td_intr_nesting_level == 0 && 803 curpcb->pcb_onfault != NULL) { 804 frame->tf_rip = (long)curpcb->pcb_onfault; 805 return (0); 806 } 807 trap_fatal(frame, eva); 808 return (-1); 809 } 810 return ((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV); 811 } 812 813 static void 814 trap_fatal(frame, eva) 815 struct trapframe *frame; 816 vm_offset_t eva; 817 { 818 int code, ss; 819 u_int type; 820 struct soft_segment_descriptor softseg; 821 char *msg; 822 823 code = frame->tf_err; 824 type = frame->tf_trapno; 825 sdtossd(&gdt[NGDT * PCPU_GET(cpuid) + IDXSEL(frame->tf_cs & 0xffff)], 826 &softseg); 827 828 if (type <= MAX_TRAP_MSG) 829 msg = trap_msg[type]; 830 else 831 msg = "UNKNOWN"; 832 printf("\n\nFatal trap %d: %s while in %s mode\n", type, msg, 833 TRAPF_USERMODE(frame) ? "user" : "kernel"); 834 #ifdef SMP 835 /* two separate prints in case of a trap on an unmapped page */ 836 printf("cpuid = %d; ", PCPU_GET(cpuid)); 837 printf("apic id = %02x\n", PCPU_GET(apic_id)); 838 #endif 839 if (type == T_PAGEFLT) { 840 printf("fault virtual address = 0x%lx\n", eva); 841 printf("fault code = %s %s %s, %s\n", 842 code & PGEX_U ? "user" : "supervisor", 843 code & PGEX_W ? "write" : "read", 844 code & PGEX_I ? "instruction" : "data", 845 code & PGEX_RSV ? "reserved bits in PTE" : 846 code & PGEX_P ? "protection violation" : "page not present"); 847 } 848 printf("instruction pointer = 0x%lx:0x%lx\n", 849 frame->tf_cs & 0xffff, frame->tf_rip); 850 ss = frame->tf_ss & 0xffff; 851 printf("stack pointer = 0x%x:0x%lx\n", ss, frame->tf_rsp); 852 printf("frame pointer = 0x%x:0x%lx\n", ss, frame->tf_rbp); 853 printf("code segment = base 0x%lx, limit 0x%lx, type 0x%x\n", 854 softseg.ssd_base, softseg.ssd_limit, softseg.ssd_type); 855 printf(" = DPL %d, pres %d, long %d, def32 %d, gran %d\n", 856 softseg.ssd_dpl, softseg.ssd_p, softseg.ssd_long, softseg.ssd_def32, 857 softseg.ssd_gran); 858 printf("processor eflags = "); 859 if (frame->tf_rflags & PSL_T) 860 printf("trace trap, "); 861 if (frame->tf_rflags & PSL_I) 862 printf("interrupt enabled, "); 863 if (frame->tf_rflags & PSL_NT) 864 printf("nested task, "); 865 if (frame->tf_rflags & PSL_RF) 866 printf("resume, "); 867 printf("IOPL = %ld\n", (frame->tf_rflags & PSL_IOPL) >> 12); 868 printf("current process = %d (%s)\n", 869 curproc->p_pid, curthread->td_name); 870 871 #ifdef KDB 872 if (debugger_on_panic || kdb_active) 873 if (kdb_trap(type, 0, frame)) 874 return; 875 #endif 876 printf("trap number = %d\n", type); 877 if (type <= MAX_TRAP_MSG) 878 panic("%s", trap_msg[type]); 879 else 880 panic("unknown/reserved trap"); 881 } 882 883 /* 884 * Double fault handler. Called when a fault occurs while writing 885 * a frame for a trap/exception onto the stack. This usually occurs 886 * when the stack overflows (such is the case with infinite recursion, 887 * for example). 888 */ 889 void 890 dblfault_handler(struct trapframe *frame) 891 { 892 #ifdef KDTRACE_HOOKS 893 if (dtrace_doubletrap_func != NULL) 894 (*dtrace_doubletrap_func)(); 895 #endif 896 printf("\nFatal double fault\n"); 897 printf("rip = 0x%lx\n", frame->tf_rip); 898 printf("rsp = 0x%lx\n", frame->tf_rsp); 899 printf("rbp = 0x%lx\n", frame->tf_rbp); 900 #ifdef SMP 901 /* two separate prints in case of a trap on an unmapped page */ 902 printf("cpuid = %d; ", PCPU_GET(cpuid)); 903 printf("apic id = %02x\n", PCPU_GET(apic_id)); 904 #endif 905 panic("double fault"); 906 } 907 908 int 909 cpu_fetch_syscall_args(struct thread *td, struct syscall_args *sa) 910 { 911 struct proc *p; 912 struct trapframe *frame; 913 register_t *argp; 914 caddr_t params; 915 int reg, regcnt, error; 916 917 p = td->td_proc; 918 frame = td->td_frame; 919 reg = 0; 920 regcnt = 6; 921 922 params = (caddr_t)frame->tf_rsp + sizeof(register_t); 923 sa->code = frame->tf_rax; 924 925 if (sa->code == SYS_syscall || sa->code == SYS___syscall) { 926 sa->code = frame->tf_rdi; 927 reg++; 928 regcnt--; 929 } 930 if (p->p_sysent->sv_mask) 931 sa->code &= p->p_sysent->sv_mask; 932 933 if (sa->code >= p->p_sysent->sv_size) 934 sa->callp = &p->p_sysent->sv_table[0]; 935 else 936 sa->callp = &p->p_sysent->sv_table[sa->code]; 937 938 sa->narg = sa->callp->sy_narg; 939 KASSERT(sa->narg <= sizeof(sa->args) / sizeof(sa->args[0]), 940 ("Too many syscall arguments!")); 941 error = 0; 942 argp = &frame->tf_rdi; 943 argp += reg; 944 bcopy(argp, sa->args, sizeof(sa->args[0]) * regcnt); 945 if (sa->narg > regcnt) { 946 KASSERT(params != NULL, ("copyin args with no params!")); 947 error = copyin(params, &sa->args[regcnt], 948 (sa->narg - regcnt) * sizeof(sa->args[0])); 949 } 950 951 if (error == 0) { 952 td->td_retval[0] = 0; 953 td->td_retval[1] = frame->tf_rdx; 954 } 955 956 return (error); 957 } 958 959 #include "../../kern/subr_syscall.c" 960 961 /* 962 * System call handler for native binaries. The trap frame is already 963 * set up by the assembler trampoline and a pointer to it is saved in 964 * td_frame. 965 */ 966 void 967 amd64_syscall(struct thread *td, int traced) 968 { 969 struct syscall_args sa; 970 int error; 971 ksiginfo_t ksi; 972 973 #ifdef DIAGNOSTIC 974 if (!TRAPF_USERMODE(td->td_frame)) { 975 panic("syscall"); 976 /* NOT REACHED */ 977 } 978 #endif 979 error = syscallenter(td, &sa); 980 981 /* 982 * Traced syscall. 983 */ 984 if (__predict_false(traced)) { 985 td->td_frame->tf_rflags &= ~PSL_T; 986 ksiginfo_init_trap(&ksi); 987 ksi.ksi_signo = SIGTRAP; 988 ksi.ksi_code = TRAP_TRACE; 989 ksi.ksi_addr = (void *)td->td_frame->tf_rip; 990 trapsignal(td, &ksi); 991 } 992 993 KASSERT(PCB_USER_FPU(td->td_pcb), 994 ("System call %s returning with kernel FPU ctx leaked", 995 syscallname(td->td_proc, sa.code))); 996 KASSERT(td->td_pcb->pcb_save == get_pcb_user_save_td(td), 997 ("System call %s returning with mangled pcb_save", 998 syscallname(td->td_proc, sa.code))); 999 KASSERT(td->td_md.md_invl_gen.gen == 0, 1000 ("System call %s returning with leaked invl_gen %lu", 1001 syscallname(td->td_proc, sa.code), td->td_md.md_invl_gen.gen)); 1002 1003 syscallret(td, error, &sa); 1004 1005 /* 1006 * If the user-supplied value of %rip is not a canonical 1007 * address, then some CPUs will trigger a ring 0 #GP during 1008 * the sysret instruction. However, the fault handler would 1009 * execute in ring 0 with the user's %gs and %rsp which would 1010 * not be safe. Instead, use the full return path which 1011 * catches the problem safely. 1012 */ 1013 if (td->td_frame->tf_rip >= VM_MAXUSER_ADDRESS) 1014 set_pcb_flags(td->td_pcb, PCB_FULL_IRET); 1015 }
Cache object: 151c005a564aa6e5fe34c0438aaf3fa2
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