Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/amd64/amd64/trap.c
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1 /*- 2 * SPDX-License-Identifier: BSD-4-Clause 3 * 4 * Copyright (C) 1994, David Greenman 5 * Copyright (c) 1990, 1993 6 * The Regents of the University of California. All rights reserved. 7 * 8 * This code is derived from software contributed to Berkeley by 9 * the University of Utah, and William Jolitz. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the University of 22 * California, Berkeley and its contributors. 23 * 4. Neither the name of the University nor the names of its contributors 24 * may be used to endorse or promote products derived from this software 25 * without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37 * SUCH DAMAGE. 38 * 39 * from: @(#)trap.c 7.4 (Berkeley) 5/13/91 40 */ 41 42 #include <sys/cdefs.h> 43 __FBSDID("$FreeBSD$"); 44 45 /* 46 * AMD64 Trap and System call handling 47 */ 48 49 #include "opt_clock.h" 50 #include "opt_compat.h" 51 #include "opt_cpu.h" 52 #include "opt_hwpmc_hooks.h" 53 #include "opt_isa.h" 54 #include "opt_kdb.h" 55 56 #include <sys/param.h> 57 #include <sys/asan.h> 58 #include <sys/bus.h> 59 #include <sys/systm.h> 60 #include <sys/proc.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/msan.h> 67 #include <sys/mutex.h> 68 #include <sys/resourcevar.h> 69 #include <sys/signalvar.h> 70 #include <sys/syscall.h> 71 #include <sys/sysctl.h> 72 #include <sys/sysent.h> 73 #include <sys/uio.h> 74 #include <sys/vmmeter.h> 75 #ifdef HWPMC_HOOKS 76 #include <sys/pmckern.h> 77 PMC_SOFT_DEFINE( , , page_fault, all); 78 PMC_SOFT_DEFINE( , , page_fault, read); 79 PMC_SOFT_DEFINE( , , page_fault, write); 80 #endif 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/stack.h> 99 #include <machine/trap.h> 100 #include <machine/tss.h> 101 102 #ifdef KDTRACE_HOOKS 103 #include <sys/dtrace_bsd.h> 104 #endif 105 106 extern inthand_t IDTVEC(bpt), IDTVEC(bpt_pti), IDTVEC(dbg), 107 IDTVEC(fast_syscall), IDTVEC(fast_syscall_pti), IDTVEC(fast_syscall32), 108 IDTVEC(int0x80_syscall_pti), IDTVEC(int0x80_syscall); 109 110 void __noinline trap(struct trapframe *frame); 111 void trap_check(struct trapframe *frame); 112 void dblfault_handler(struct trapframe *frame); 113 114 static int trap_pfault(struct trapframe *, bool, int *, int *); 115 static void trap_fatal(struct trapframe *, vm_offset_t); 116 #ifdef KDTRACE_HOOKS 117 static bool trap_user_dtrace(struct trapframe *, 118 int (**hook)(struct trapframe *)); 119 #endif 120 121 static const char UNKNOWN[] = "unknown"; 122 static const char *const trap_msg[] = { 123 [0] = UNKNOWN, /* unused */ 124 [T_PRIVINFLT] = "privileged instruction fault", 125 [2] = UNKNOWN, /* unused */ 126 [T_BPTFLT] = "breakpoint instruction fault", 127 [4] = UNKNOWN, /* unused */ 128 [5] = UNKNOWN, /* unused */ 129 [T_ARITHTRAP] = "arithmetic trap", 130 [7] = UNKNOWN, /* unused */ 131 [8] = UNKNOWN, /* unused */ 132 [T_PROTFLT] = "general protection fault", 133 [T_TRCTRAP] = "debug exception", 134 [11] = UNKNOWN, /* unused */ 135 [T_PAGEFLT] = "page fault", 136 [13] = UNKNOWN, /* unused */ 137 [T_ALIGNFLT] = "alignment fault", 138 [15] = UNKNOWN, /* unused */ 139 [16] = UNKNOWN, /* unused */ 140 [17] = UNKNOWN, /* unused */ 141 [T_DIVIDE] = "integer divide fault", 142 [T_NMI] = "non-maskable interrupt trap", 143 [T_OFLOW] = "overflow trap", 144 [T_BOUND] = "FPU bounds check fault", 145 [T_DNA] = "FPU device not available", 146 [T_DOUBLEFLT] = "double fault", 147 [T_FPOPFLT] = "FPU operand fetch fault", 148 [T_TSSFLT] = "invalid TSS fault", 149 [T_SEGNPFLT] = "segment not present fault", 150 [T_STKFLT] = "stack fault", 151 [T_MCHK] = "machine check trap", 152 [T_XMMFLT] = "SIMD floating-point exception", 153 [T_RESERVED] = "reserved (unknown) fault", 154 [31] = UNKNOWN, /* reserved */ 155 [T_DTRACE_RET] = "DTrace pid return trap", 156 }; 157 158 static int uprintf_signal; 159 SYSCTL_INT(_machdep, OID_AUTO, uprintf_signal, CTLFLAG_RWTUN, 160 &uprintf_signal, 0, 161 "Print debugging information on trap signal to ctty"); 162 163 /* 164 * Control L1D flush on return from NMI. 165 * 166 * Tunable can be set to the following values: 167 * 0 - only enable flush on return from NMI if required by vmm.ko (default) 168 * >1 - always flush on return from NMI. 169 * 170 * Post-boot, the sysctl indicates if flushing is currently enabled. 171 */ 172 int nmi_flush_l1d_sw; 173 SYSCTL_INT(_machdep, OID_AUTO, nmi_flush_l1d_sw, CTLFLAG_RWTUN, 174 &nmi_flush_l1d_sw, 0, 175 "Flush L1 Data Cache on NMI exit, software bhyve L1TF mitigation assist"); 176 177 /* 178 * Table of handlers for various segment load faults. 179 */ 180 static const struct { 181 uintptr_t faddr; 182 uintptr_t fhandler; 183 } sfhandlers[] = { 184 { 185 .faddr = (uintptr_t)ld_ds, 186 .fhandler = (uintptr_t)ds_load_fault, 187 }, 188 { 189 .faddr = (uintptr_t)ld_es, 190 .fhandler = (uintptr_t)es_load_fault, 191 }, 192 { 193 .faddr = (uintptr_t)ld_fs, 194 .fhandler = (uintptr_t)fs_load_fault, 195 }, 196 { 197 .faddr = (uintptr_t)ld_gs, 198 .fhandler = (uintptr_t)gs_load_fault, 199 }, 200 { 201 .faddr = (uintptr_t)ld_gsbase, 202 .fhandler = (uintptr_t)gsbase_load_fault 203 }, 204 { 205 .faddr = (uintptr_t)ld_fsbase, 206 .fhandler = (uintptr_t)fsbase_load_fault, 207 }, 208 }; 209 210 /* 211 * Exception, fault, and trap interface to the FreeBSD kernel. 212 * This common code is called from assembly language IDT gate entry 213 * routines that prepare a suitable stack frame, and restore this 214 * frame after the exception has been processed. 215 */ 216 217 void 218 trap(struct trapframe *frame) 219 { 220 ksiginfo_t ksi; 221 struct thread *td; 222 struct proc *p; 223 register_t addr, dr6; 224 size_t i; 225 int pf, signo, ucode; 226 u_int type; 227 228 td = curthread; 229 p = td->td_proc; 230 dr6 = 0; 231 232 kasan_mark(frame, sizeof(*frame), sizeof(*frame), 0); 233 kmsan_mark(frame, sizeof(*frame), KMSAN_STATE_INITED); 234 235 VM_CNT_INC(v_trap); 236 type = frame->tf_trapno; 237 238 #ifdef SMP 239 /* Handler for NMI IPIs used for stopping CPUs. */ 240 if (type == T_NMI && ipi_nmi_handler() == 0) 241 return; 242 #endif 243 244 #ifdef KDB 245 if (kdb_active) { 246 kdb_reenter(); 247 return; 248 } 249 #endif 250 251 if (type == T_RESERVED) { 252 trap_fatal(frame, 0); 253 return; 254 } 255 256 if (type == T_NMI) { 257 #ifdef HWPMC_HOOKS 258 /* 259 * CPU PMCs interrupt using an NMI. If the PMC module is 260 * active, pass the 'rip' value to the PMC module's interrupt 261 * handler. A non-zero return value from the handler means that 262 * the NMI was consumed by it and we can return immediately. 263 */ 264 if (pmc_intr != NULL && 265 (*pmc_intr)(frame) != 0) 266 return; 267 #endif 268 } 269 270 if ((frame->tf_rflags & PSL_I) == 0) { 271 /* 272 * Buggy application or kernel code has disabled 273 * interrupts and then trapped. Enabling interrupts 274 * now is wrong, but it is better than running with 275 * interrupts disabled until they are accidentally 276 * enabled later. 277 */ 278 if (TRAPF_USERMODE(frame)) { 279 uprintf( 280 "pid %ld (%s): trap %d (%s) " 281 "with interrupts disabled\n", 282 (long)curproc->p_pid, curthread->td_name, type, 283 trap_msg[type]); 284 } else { 285 switch (type) { 286 case T_NMI: 287 case T_BPTFLT: 288 case T_TRCTRAP: 289 case T_PROTFLT: 290 case T_SEGNPFLT: 291 case T_STKFLT: 292 break; 293 default: 294 printf( 295 "kernel trap %d with interrupts disabled\n", 296 type); 297 298 /* 299 * We shouldn't enable interrupts while holding a 300 * spin lock. 301 */ 302 if (td->td_md.md_spinlock_count == 0) 303 enable_intr(); 304 } 305 } 306 } 307 308 if (TRAPF_USERMODE(frame)) { 309 /* user trap */ 310 311 td->td_pticks = 0; 312 td->td_frame = frame; 313 addr = frame->tf_rip; 314 if (td->td_cowgen != atomic_load_int(&p->p_cowgen)) 315 thread_cow_update(td); 316 317 switch (type) { 318 case T_PRIVINFLT: /* privileged instruction fault */ 319 signo = SIGILL; 320 ucode = ILL_PRVOPC; 321 break; 322 323 case T_BPTFLT: /* bpt instruction fault */ 324 #ifdef KDTRACE_HOOKS 325 if (trap_user_dtrace(frame, &dtrace_pid_probe_ptr)) 326 return; 327 #else 328 enable_intr(); 329 #endif 330 signo = SIGTRAP; 331 ucode = TRAP_BRKPT; 332 break; 333 334 case T_TRCTRAP: /* debug exception */ 335 enable_intr(); 336 signo = SIGTRAP; 337 ucode = TRAP_TRACE; 338 dr6 = rdr6(); 339 if ((dr6 & DBREG_DR6_BS) != 0) { 340 PROC_LOCK(td->td_proc); 341 if ((td->td_dbgflags & TDB_STEP) != 0) { 342 td->td_frame->tf_rflags &= ~PSL_T; 343 td->td_dbgflags &= ~TDB_STEP; 344 } 345 PROC_UNLOCK(td->td_proc); 346 } 347 break; 348 349 case T_ARITHTRAP: /* arithmetic trap */ 350 ucode = fputrap_x87(); 351 if (ucode == -1) 352 return; 353 signo = SIGFPE; 354 break; 355 356 case T_PROTFLT: /* general protection fault */ 357 signo = SIGBUS; 358 ucode = BUS_OBJERR; 359 break; 360 case T_STKFLT: /* stack fault */ 361 case T_SEGNPFLT: /* segment not present fault */ 362 signo = SIGBUS; 363 ucode = BUS_ADRERR; 364 break; 365 case T_TSSFLT: /* invalid TSS fault */ 366 signo = SIGBUS; 367 ucode = BUS_OBJERR; 368 break; 369 case T_ALIGNFLT: 370 signo = SIGBUS; 371 ucode = BUS_ADRALN; 372 break; 373 case T_DOUBLEFLT: /* double fault */ 374 default: 375 signo = SIGBUS; 376 ucode = BUS_OBJERR; 377 break; 378 379 case T_PAGEFLT: /* page fault */ 380 /* 381 * Can emulator handle this trap? 382 */ 383 if (*p->p_sysent->sv_trap != NULL && 384 (*p->p_sysent->sv_trap)(td) == 0) 385 return; 386 387 pf = trap_pfault(frame, true, &signo, &ucode); 388 if (pf == -1) 389 return; 390 if (pf == 0) 391 goto userret; 392 addr = frame->tf_addr; 393 break; 394 395 case T_DIVIDE: /* integer divide fault */ 396 ucode = FPE_INTDIV; 397 signo = SIGFPE; 398 break; 399 400 case T_NMI: 401 nmi_handle_intr(type, frame); 402 return; 403 404 case T_OFLOW: /* integer overflow fault */ 405 ucode = FPE_INTOVF; 406 signo = SIGFPE; 407 break; 408 409 case T_BOUND: /* bounds check fault */ 410 ucode = FPE_FLTSUB; 411 signo = SIGFPE; 412 break; 413 414 case T_DNA: 415 /* transparent fault (due to context switch "late") */ 416 KASSERT(PCB_USER_FPU(td->td_pcb), 417 ("kernel FPU ctx has leaked")); 418 fpudna(); 419 return; 420 421 case T_FPOPFLT: /* FPU operand fetch fault */ 422 ucode = ILL_COPROC; 423 signo = SIGILL; 424 break; 425 426 case T_XMMFLT: /* SIMD floating-point exception */ 427 ucode = fputrap_sse(); 428 if (ucode == -1) 429 return; 430 signo = SIGFPE; 431 break; 432 #ifdef KDTRACE_HOOKS 433 case T_DTRACE_RET: 434 (void)trap_user_dtrace(frame, &dtrace_return_probe_ptr); 435 return; 436 #endif 437 } 438 } else { 439 /* kernel trap */ 440 441 KASSERT(cold || td->td_ucred != NULL, 442 ("kernel trap doesn't have ucred")); 443 switch (type) { 444 case T_PAGEFLT: /* page fault */ 445 (void)trap_pfault(frame, false, NULL, NULL); 446 return; 447 448 case T_DNA: 449 if (PCB_USER_FPU(td->td_pcb)) 450 panic("Unregistered use of FPU in kernel"); 451 fpudna(); 452 return; 453 454 case T_ARITHTRAP: /* arithmetic trap */ 455 case T_XMMFLT: /* SIMD floating-point exception */ 456 case T_FPOPFLT: /* FPU operand fetch fault */ 457 /* 458 * For now, supporting kernel handler 459 * registration for FPU traps is overkill. 460 */ 461 trap_fatal(frame, 0); 462 return; 463 464 case T_STKFLT: /* stack fault */ 465 case T_PROTFLT: /* general protection fault */ 466 case T_SEGNPFLT: /* segment not present fault */ 467 if (td->td_intr_nesting_level != 0) 468 break; 469 470 /* 471 * Invalid segment selectors and out of bounds 472 * %rip's and %rsp's can be set up in user mode. 473 * This causes a fault in kernel mode when the 474 * kernel tries to return to user mode. We want 475 * to get this fault so that we can fix the 476 * problem here and not have to check all the 477 * selectors and pointers when the user changes 478 * them. 479 * 480 * In case of PTI, the IRETQ faulted while the 481 * kernel used the pti stack, and exception 482 * frame records %rsp value pointing to that 483 * stack. If we return normally to 484 * doreti_iret_fault, the trapframe is 485 * reconstructed on pti stack, and calltrap() 486 * called on it as well. Due to the very 487 * limited pti stack size, kernel does not 488 * survive for too long. Switch to the normal 489 * thread stack for the trap handling. 490 * 491 * Magic '5' is the number of qwords occupied by 492 * the hardware trap frame. 493 */ 494 if (frame->tf_rip == (long)doreti_iret) { 495 KASSERT((read_rflags() & PSL_I) == 0, 496 ("interrupts enabled")); 497 frame->tf_rip = (long)doreti_iret_fault; 498 if ((PCPU_GET(curpmap)->pm_ucr3 != 499 PMAP_NO_CR3) && 500 (frame->tf_rsp == (uintptr_t)PCPU_GET( 501 pti_rsp0) - 5 * sizeof(register_t))) { 502 frame->tf_rsp = PCPU_GET(rsp0) - 5 * 503 sizeof(register_t); 504 } 505 return; 506 } 507 508 for (i = 0; i < nitems(sfhandlers); i++) { 509 if (frame->tf_rip == sfhandlers[i].faddr) { 510 KASSERT((read_rflags() & PSL_I) == 0, 511 ("interrupts enabled")); 512 frame->tf_rip = sfhandlers[i].fhandler; 513 return; 514 } 515 } 516 517 if (curpcb->pcb_onfault != NULL) { 518 frame->tf_rip = (long)curpcb->pcb_onfault; 519 return; 520 } 521 break; 522 523 case T_TSSFLT: 524 /* 525 * PSL_NT can be set in user mode and isn't cleared 526 * automatically when the kernel is entered. This 527 * causes a TSS fault when the kernel attempts to 528 * `iret' because the TSS link is uninitialized. We 529 * want to get this fault so that we can fix the 530 * problem here and not every time the kernel is 531 * entered. 532 */ 533 if (frame->tf_rflags & PSL_NT) { 534 frame->tf_rflags &= ~PSL_NT; 535 return; 536 } 537 break; 538 539 case T_TRCTRAP: /* debug exception */ 540 /* Clear any pending debug events. */ 541 dr6 = rdr6(); 542 load_dr6(0); 543 544 /* 545 * Ignore debug register exceptions due to 546 * accesses in the user's address space, which 547 * can happen under several conditions such as 548 * if a user sets a watchpoint on a buffer and 549 * then passes that buffer to a system call. 550 * We still want to get TRCTRAPS for addresses 551 * in kernel space because that is useful when 552 * debugging the kernel. 553 */ 554 if (user_dbreg_trap(dr6)) 555 return; 556 557 /* 558 * Malicious user code can configure a debug 559 * register watchpoint to trap on data access 560 * to the top of stack and then execute 'pop 561 * %ss; int 3'. Due to exception deferral for 562 * 'pop %ss', the CPU will not interrupt 'int 563 * 3' to raise the DB# exception for the debug 564 * register but will postpone the DB# until 565 * execution of the first instruction of the 566 * BP# handler (in kernel mode). Normally the 567 * previous check would ignore DB# exceptions 568 * for watchpoints on user addresses raised in 569 * kernel mode. However, some CPU errata 570 * include cases where DB# exceptions do not 571 * properly set bits in %dr6, e.g. Haswell 572 * HSD23 and Skylake-X SKZ24. 573 * 574 * A deferred DB# can also be raised on the 575 * first instructions of system call entry 576 * points or single-step traps via similar use 577 * of 'pop %ss' or 'mov xxx, %ss'. 578 */ 579 if (pti) { 580 if (frame->tf_rip == 581 (uintptr_t)IDTVEC(fast_syscall_pti) || 582 #ifdef COMPAT_FREEBSD32 583 frame->tf_rip == 584 (uintptr_t)IDTVEC(int0x80_syscall_pti) || 585 #endif 586 frame->tf_rip == (uintptr_t)IDTVEC(bpt_pti)) 587 return; 588 } else { 589 if (frame->tf_rip == 590 (uintptr_t)IDTVEC(fast_syscall) || 591 #ifdef COMPAT_FREEBSD32 592 frame->tf_rip == 593 (uintptr_t)IDTVEC(int0x80_syscall) || 594 #endif 595 frame->tf_rip == (uintptr_t)IDTVEC(bpt)) 596 return; 597 } 598 if (frame->tf_rip == (uintptr_t)IDTVEC(dbg) || 599 /* Needed for AMD. */ 600 frame->tf_rip == (uintptr_t)IDTVEC(fast_syscall32)) 601 return; 602 /* 603 * FALLTHROUGH (TRCTRAP kernel mode, kernel address) 604 */ 605 case T_BPTFLT: 606 /* 607 * If KDB is enabled, let it handle the debugger trap. 608 * Otherwise, debugger traps "can't happen". 609 */ 610 #ifdef KDB 611 if (kdb_trap(type, dr6, frame)) 612 return; 613 #endif 614 break; 615 616 case T_NMI: 617 nmi_handle_intr(type, frame); 618 return; 619 } 620 621 trap_fatal(frame, 0); 622 return; 623 } 624 625 ksiginfo_init_trap(&ksi); 626 ksi.ksi_signo = signo; 627 ksi.ksi_code = ucode; 628 ksi.ksi_trapno = type; 629 ksi.ksi_addr = (void *)addr; 630 if (uprintf_signal) { 631 uprintf("pid %d comm %s: signal %d err %#lx code %d type %d " 632 "addr %#lx rsp %#lx rip %#lx rax %#lx" 633 "<%02x %02x %02x %02x %02x %02x %02x %02x>\n", 634 p->p_pid, p->p_comm, signo, frame->tf_err, ucode, type, 635 addr, frame->tf_rsp, frame->tf_rip, frame->tf_rax, 636 fubyte((void *)(frame->tf_rip + 0)), 637 fubyte((void *)(frame->tf_rip + 1)), 638 fubyte((void *)(frame->tf_rip + 2)), 639 fubyte((void *)(frame->tf_rip + 3)), 640 fubyte((void *)(frame->tf_rip + 4)), 641 fubyte((void *)(frame->tf_rip + 5)), 642 fubyte((void *)(frame->tf_rip + 6)), 643 fubyte((void *)(frame->tf_rip + 7))); 644 } 645 KASSERT((read_rflags() & PSL_I) != 0, ("interrupts disabled")); 646 trapsignal(td, &ksi); 647 648 userret: 649 userret(td, frame); 650 KASSERT(PCB_USER_FPU(td->td_pcb), 651 ("Return from trap with kernel FPU ctx leaked")); 652 } 653 654 /* 655 * Ensure that we ignore any DTrace-induced faults. This function cannot 656 * be instrumented, so it cannot generate such faults itself. 657 */ 658 void 659 trap_check(struct trapframe *frame) 660 { 661 662 #ifdef KDTRACE_HOOKS 663 if (dtrace_trap_func != NULL && 664 (*dtrace_trap_func)(frame, frame->tf_trapno) != 0) 665 return; 666 #endif 667 trap(frame); 668 } 669 670 static bool 671 trap_is_smap(struct trapframe *frame) 672 { 673 674 /* 675 * A page fault on a userspace address is classified as 676 * SMAP-induced if: 677 * - SMAP is supported; 678 * - kernel mode accessed present data page; 679 * - rflags.AC was cleared. 680 * Kernel must never access user space with rflags.AC cleared 681 * if SMAP is enabled. 682 */ 683 return ((cpu_stdext_feature & CPUID_STDEXT_SMAP) != 0 && 684 (frame->tf_err & (PGEX_P | PGEX_U | PGEX_I | PGEX_RSV)) == 685 PGEX_P && (frame->tf_rflags & PSL_AC) == 0); 686 } 687 688 static bool 689 trap_is_pti(struct trapframe *frame) 690 { 691 692 return (PCPU_GET(curpmap)->pm_ucr3 != PMAP_NO_CR3 && 693 pg_nx != 0 && (frame->tf_err & (PGEX_P | PGEX_W | 694 PGEX_U | PGEX_I)) == (PGEX_P | PGEX_U | PGEX_I) && 695 (curpcb->pcb_saved_ucr3 & ~CR3_PCID_MASK) == 696 (PCPU_GET(curpmap)->pm_cr3 & ~CR3_PCID_MASK)); 697 } 698 699 /* 700 * Handle all details of a page fault. 701 * Returns: 702 * -1 if this fault was fatal, typically from kernel mode 703 * (cannot happen, but we need to return something). 704 * 0 if this fault was handled by updating either the user or kernel 705 * page table, execution can continue. 706 * 1 if this fault was from usermode and it was not handled, a synchronous 707 * signal should be delivered to the thread. *signo returns the signal 708 * number, *ucode gives si_code. 709 */ 710 static int 711 trap_pfault(struct trapframe *frame, bool usermode, int *signo, int *ucode) 712 { 713 struct thread *td; 714 struct proc *p; 715 vm_map_t map; 716 vm_offset_t eva; 717 int rv; 718 vm_prot_t ftype; 719 720 MPASS(!usermode || (signo != NULL && ucode != NULL)); 721 722 td = curthread; 723 p = td->td_proc; 724 eva = frame->tf_addr; 725 726 if (__predict_false((td->td_pflags & TDP_NOFAULTING) != 0)) { 727 /* 728 * Due to both processor errata and lazy TLB invalidation when 729 * access restrictions are removed from virtual pages, memory 730 * accesses that are allowed by the physical mapping layer may 731 * nonetheless cause one spurious page fault per virtual page. 732 * When the thread is executing a "no faulting" section that 733 * is bracketed by vm_fault_{disable,enable}_pagefaults(), 734 * every page fault is treated as a spurious page fault, 735 * unless it accesses the same virtual address as the most 736 * recent page fault within the same "no faulting" section. 737 */ 738 if (td->td_md.md_spurflt_addr != eva || 739 (td->td_pflags & TDP_RESETSPUR) != 0) { 740 /* 741 * Do nothing to the TLB. A stale TLB entry is 742 * flushed automatically by a page fault. 743 */ 744 td->td_md.md_spurflt_addr = eva; 745 td->td_pflags &= ~TDP_RESETSPUR; 746 return (0); 747 } 748 } else { 749 /* 750 * If we get a page fault while in a critical section, then 751 * it is most likely a fatal kernel page fault. The kernel 752 * is already going to panic trying to get a sleep lock to 753 * do the VM lookup, so just consider it a fatal trap so the 754 * kernel can print out a useful trap message and even get 755 * to the debugger. 756 * 757 * If we get a page fault while holding a non-sleepable 758 * lock, then it is most likely a fatal kernel page fault. 759 * If WITNESS is enabled, then it's going to whine about 760 * bogus LORs with various VM locks, so just skip to the 761 * fatal trap handling directly. 762 */ 763 if (td->td_critnest != 0 || 764 WITNESS_CHECK(WARN_SLEEPOK | WARN_GIANTOK, NULL, 765 "Kernel page fault") != 0) { 766 trap_fatal(frame, eva); 767 return (-1); 768 } 769 } 770 if (eva >= VM_MIN_KERNEL_ADDRESS) { 771 /* 772 * Don't allow user-mode faults in kernel address space. 773 */ 774 if (usermode) { 775 *signo = SIGSEGV; 776 *ucode = SEGV_MAPERR; 777 return (1); 778 } 779 780 map = kernel_map; 781 } else { 782 map = &p->p_vmspace->vm_map; 783 784 /* 785 * When accessing a usermode address, kernel must be 786 * ready to accept the page fault, and provide a 787 * handling routine. Since accessing the address 788 * without the handler is a bug, do not try to handle 789 * it normally, and panic immediately. 790 * 791 * If SMAP is enabled, filter SMAP faults also, 792 * because illegal access might occur to the mapped 793 * user address, causing infinite loop. 794 */ 795 if (!usermode && (td->td_intr_nesting_level != 0 || 796 trap_is_smap(frame) || curpcb->pcb_onfault == NULL)) { 797 trap_fatal(frame, eva); 798 return (-1); 799 } 800 } 801 802 /* 803 * If the trap was caused by errant bits in the PTE then panic. 804 */ 805 if (frame->tf_err & PGEX_RSV) { 806 trap_fatal(frame, eva); 807 return (-1); 808 } 809 810 /* 811 * User-mode protection key violation (PKU). May happen 812 * either from usermode or from kernel if copyin accessed 813 * key-protected mapping. 814 */ 815 if ((frame->tf_err & PGEX_PK) != 0) { 816 if (eva > VM_MAXUSER_ADDRESS) { 817 trap_fatal(frame, eva); 818 return (-1); 819 } 820 if (usermode) { 821 *signo = SIGSEGV; 822 *ucode = SEGV_PKUERR; 823 return (1); 824 } 825 goto after_vmfault; 826 } 827 828 /* 829 * If nx protection of the usermode portion of kernel page 830 * tables caused trap, panic. 831 */ 832 if (usermode && trap_is_pti(frame)) 833 panic("PTI: pid %d comm %s tf_err %#lx", p->p_pid, 834 p->p_comm, frame->tf_err); 835 836 /* 837 * PGEX_I is defined only if the execute disable bit capability is 838 * supported and enabled. 839 */ 840 if (frame->tf_err & PGEX_W) 841 ftype = VM_PROT_WRITE; 842 else if ((frame->tf_err & PGEX_I) && pg_nx != 0) 843 ftype = VM_PROT_EXECUTE; 844 else 845 ftype = VM_PROT_READ; 846 847 /* Fault in the page. */ 848 rv = vm_fault_trap(map, eva, ftype, VM_FAULT_NORMAL, signo, ucode); 849 if (rv == KERN_SUCCESS) { 850 #ifdef HWPMC_HOOKS 851 if (ftype == VM_PROT_READ || ftype == VM_PROT_WRITE) { 852 PMC_SOFT_CALL_TF( , , page_fault, all, frame); 853 if (ftype == VM_PROT_READ) 854 PMC_SOFT_CALL_TF( , , page_fault, read, 855 frame); 856 else 857 PMC_SOFT_CALL_TF( , , page_fault, write, 858 frame); 859 } 860 #endif 861 return (0); 862 } 863 864 if (usermode) 865 return (1); 866 after_vmfault: 867 if (td->td_intr_nesting_level == 0 && 868 curpcb->pcb_onfault != NULL) { 869 frame->tf_rip = (long)curpcb->pcb_onfault; 870 return (0); 871 } 872 trap_fatal(frame, eva); 873 return (-1); 874 } 875 876 static void 877 trap_fatal(struct trapframe *frame, vm_offset_t eva) 878 { 879 int code, ss; 880 u_int type; 881 struct soft_segment_descriptor softseg; 882 struct user_segment_descriptor *gdt; 883 #ifdef KDB 884 bool handled; 885 #endif 886 887 code = frame->tf_err; 888 type = frame->tf_trapno; 889 gdt = *PCPU_PTR(gdt); 890 sdtossd(&gdt[IDXSEL(frame->tf_cs & 0xffff)], &softseg); 891 892 printf("\n\nFatal trap %d: %s while in %s mode\n", type, 893 type < nitems(trap_msg) ? trap_msg[type] : UNKNOWN, 894 TRAPF_USERMODE(frame) ? "user" : "kernel"); 895 #ifdef SMP 896 /* two separate prints in case of a trap on an unmapped page */ 897 printf("cpuid = %d; ", PCPU_GET(cpuid)); 898 printf("apic id = %02x\n", PCPU_GET(apic_id)); 899 #endif 900 if (type == T_PAGEFLT) { 901 printf("fault virtual address = 0x%lx\n", eva); 902 printf("fault code = %s %s %s%s%s, %s\n", 903 code & PGEX_U ? "user" : "supervisor", 904 code & PGEX_W ? "write" : "read", 905 code & PGEX_I ? "instruction" : "data", 906 code & PGEX_PK ? " prot key" : "", 907 code & PGEX_SGX ? " SGX" : "", 908 code & PGEX_RSV ? "reserved bits in PTE" : 909 code & PGEX_P ? "protection violation" : "page not present"); 910 } 911 printf("instruction pointer = 0x%lx:0x%lx\n", 912 frame->tf_cs & 0xffff, frame->tf_rip); 913 ss = frame->tf_ss & 0xffff; 914 printf("stack pointer = 0x%x:0x%lx\n", ss, frame->tf_rsp); 915 printf("frame pointer = 0x%x:0x%lx\n", ss, frame->tf_rbp); 916 printf("code segment = base 0x%lx, limit 0x%lx, type 0x%x\n", 917 softseg.ssd_base, softseg.ssd_limit, softseg.ssd_type); 918 printf(" = DPL %d, pres %d, long %d, def32 %d, gran %d\n", 919 softseg.ssd_dpl, softseg.ssd_p, softseg.ssd_long, softseg.ssd_def32, 920 softseg.ssd_gran); 921 printf("processor eflags = "); 922 if (frame->tf_rflags & PSL_T) 923 printf("trace trap, "); 924 if (frame->tf_rflags & PSL_I) 925 printf("interrupt enabled, "); 926 if (frame->tf_rflags & PSL_NT) 927 printf("nested task, "); 928 if (frame->tf_rflags & PSL_RF) 929 printf("resume, "); 930 printf("IOPL = %ld\n", (frame->tf_rflags & PSL_IOPL) >> 12); 931 printf("current process = %d (%s)\n", 932 curproc->p_pid, curthread->td_name); 933 934 printf("rdi: %16lx rsi: %16lx rdx: %16lx\n", frame->tf_rdi, 935 frame->tf_rsi, frame->tf_rdx); 936 printf("rcx: %16lx r8: %16lx r9: %16lx\n", frame->tf_rcx, 937 frame->tf_r8, frame->tf_r9); 938 printf("rax: %16lx rbx: %16lx rbp: %16lx\n", frame->tf_rax, 939 frame->tf_rbx, frame->tf_rbp); 940 printf("r10: %16lx r11: %16lx r12: %16lx\n", frame->tf_r10, 941 frame->tf_r11, frame->tf_r12); 942 printf("r13: %16lx r14: %16lx r15: %16lx\n", frame->tf_r13, 943 frame->tf_r14, frame->tf_r15); 944 945 #ifdef KDB 946 if (debugger_on_trap) { 947 kdb_why = KDB_WHY_TRAP; 948 handled = kdb_trap(type, 0, frame); 949 kdb_why = KDB_WHY_UNSET; 950 if (handled) 951 return; 952 } 953 #endif 954 printf("trap number = %d\n", type); 955 panic("%s", type < nitems(trap_msg) ? trap_msg[type] : 956 "unknown/reserved trap"); 957 } 958 959 #ifdef KDTRACE_HOOKS 960 /* 961 * Invoke a userspace DTrace hook. The hook pointer is cleared when no 962 * userspace probes are enabled, so we must synchronize with DTrace to ensure 963 * that a trapping thread is able to call the hook before it is cleared. 964 */ 965 static bool 966 trap_user_dtrace(struct trapframe *frame, int (**hookp)(struct trapframe *)) 967 { 968 int (*hook)(struct trapframe *); 969 970 hook = atomic_load_ptr(hookp); 971 enable_intr(); 972 if (hook != NULL) 973 return ((hook)(frame) == 0); 974 return (false); 975 } 976 #endif 977 978 /* 979 * Double fault handler. Called when a fault occurs while writing 980 * a frame for a trap/exception onto the stack. This usually occurs 981 * when the stack overflows (such is the case with infinite recursion, 982 * for example). 983 */ 984 void 985 dblfault_handler(struct trapframe *frame) 986 { 987 kmsan_mark(frame, sizeof(*frame), KMSAN_STATE_INITED); 988 #ifdef KDTRACE_HOOKS 989 if (dtrace_doubletrap_func != NULL) 990 (*dtrace_doubletrap_func)(); 991 #endif 992 printf("\nFatal double fault\n" 993 "rip %#lx rsp %#lx rbp %#lx\n" 994 "rax %#lx rdx %#lx rbx %#lx\n" 995 "rcx %#lx rsi %#lx rdi %#lx\n" 996 "r8 %#lx r9 %#lx r10 %#lx\n" 997 "r11 %#lx r12 %#lx r13 %#lx\n" 998 "r14 %#lx r15 %#lx rflags %#lx\n" 999 "cs %#lx ss %#lx ds %#hx es %#hx fs %#hx gs %#hx\n" 1000 "fsbase %#lx gsbase %#lx kgsbase %#lx\n", 1001 frame->tf_rip, frame->tf_rsp, frame->tf_rbp, 1002 frame->tf_rax, frame->tf_rdx, frame->tf_rbx, 1003 frame->tf_rcx, frame->tf_rdi, frame->tf_rsi, 1004 frame->tf_r8, frame->tf_r9, frame->tf_r10, 1005 frame->tf_r11, frame->tf_r12, frame->tf_r13, 1006 frame->tf_r14, frame->tf_r15, frame->tf_rflags, 1007 frame->tf_cs, frame->tf_ss, frame->tf_ds, frame->tf_es, 1008 frame->tf_fs, frame->tf_gs, 1009 rdmsr(MSR_FSBASE), rdmsr(MSR_GSBASE), rdmsr(MSR_KGSBASE)); 1010 #ifdef SMP 1011 /* two separate prints in case of a trap on an unmapped page */ 1012 printf("cpuid = %d; ", PCPU_GET(cpuid)); 1013 printf("apic id = %02x\n", PCPU_GET(apic_id)); 1014 #endif 1015 panic("double fault"); 1016 } 1017 1018 static int __noinline 1019 cpu_fetch_syscall_args_fallback(struct thread *td, struct syscall_args *sa) 1020 { 1021 struct proc *p; 1022 struct trapframe *frame; 1023 syscallarg_t *argp; 1024 caddr_t params; 1025 int reg, regcnt, error; 1026 1027 p = td->td_proc; 1028 frame = td->td_frame; 1029 reg = 0; 1030 regcnt = NARGREGS; 1031 1032 if (sa->code == SYS_syscall || sa->code == SYS___syscall) { 1033 sa->code = frame->tf_rdi; 1034 reg++; 1035 regcnt--; 1036 } 1037 1038 if (sa->code >= p->p_sysent->sv_size) 1039 sa->callp = &p->p_sysent->sv_table[0]; 1040 else 1041 sa->callp = &p->p_sysent->sv_table[sa->code]; 1042 1043 KASSERT(sa->callp->sy_narg <= nitems(sa->args), 1044 ("Too many syscall arguments!")); 1045 argp = &frame->tf_rdi; 1046 argp += reg; 1047 memcpy(sa->args, argp, sizeof(sa->args[0]) * NARGREGS); 1048 if (sa->callp->sy_narg > regcnt) { 1049 params = (caddr_t)frame->tf_rsp + sizeof(register_t); 1050 error = copyin(params, &sa->args[regcnt], 1051 (sa->callp->sy_narg - regcnt) * sizeof(sa->args[0])); 1052 if (__predict_false(error != 0)) 1053 return (error); 1054 } 1055 1056 td->td_retval[0] = 0; 1057 td->td_retval[1] = frame->tf_rdx; 1058 1059 return (0); 1060 } 1061 1062 int 1063 cpu_fetch_syscall_args(struct thread *td) 1064 { 1065 struct proc *p; 1066 struct trapframe *frame; 1067 struct syscall_args *sa; 1068 1069 p = td->td_proc; 1070 frame = td->td_frame; 1071 sa = &td->td_sa; 1072 1073 sa->code = frame->tf_rax; 1074 sa->original_code = sa->code; 1075 1076 if (__predict_false(sa->code == SYS_syscall || 1077 sa->code == SYS___syscall || 1078 sa->code >= p->p_sysent->sv_size)) 1079 return (cpu_fetch_syscall_args_fallback(td, sa)); 1080 1081 sa->callp = &p->p_sysent->sv_table[sa->code]; 1082 KASSERT(sa->callp->sy_narg <= nitems(sa->args), 1083 ("Too many syscall arguments!")); 1084 1085 if (__predict_false(sa->callp->sy_narg > NARGREGS)) 1086 return (cpu_fetch_syscall_args_fallback(td, sa)); 1087 1088 memcpy(sa->args, &frame->tf_rdi, sizeof(sa->args[0]) * NARGREGS); 1089 1090 td->td_retval[0] = 0; 1091 td->td_retval[1] = frame->tf_rdx; 1092 1093 return (0); 1094 } 1095 1096 #include "../../kern/subr_syscall.c" 1097 1098 static void (*syscall_ret_l1d_flush)(void); 1099 int syscall_ret_l1d_flush_mode; 1100 1101 static void 1102 flush_l1d_hw(void) 1103 { 1104 1105 wrmsr(MSR_IA32_FLUSH_CMD, IA32_FLUSH_CMD_L1D); 1106 } 1107 1108 static void __noinline 1109 amd64_syscall_ret_flush_l1d_check(int error) 1110 { 1111 void (*p)(void); 1112 1113 if (error != EEXIST && error != EAGAIN && error != EXDEV && 1114 error != ENOENT && error != ENOTCONN && error != EINPROGRESS) { 1115 p = atomic_load_ptr(&syscall_ret_l1d_flush); 1116 if (p != NULL) 1117 p(); 1118 } 1119 } 1120 1121 static void __inline 1122 amd64_syscall_ret_flush_l1d_check_inline(int error) 1123 { 1124 1125 if (__predict_false(error != 0)) 1126 amd64_syscall_ret_flush_l1d_check(error); 1127 } 1128 1129 void 1130 amd64_syscall_ret_flush_l1d(int error) 1131 { 1132 1133 amd64_syscall_ret_flush_l1d_check_inline(error); 1134 } 1135 1136 void 1137 amd64_syscall_ret_flush_l1d_recalc(void) 1138 { 1139 bool l1d_hw; 1140 1141 l1d_hw = (cpu_stdext_feature3 & CPUID_STDEXT3_L1D_FLUSH) != 0; 1142 again: 1143 switch (syscall_ret_l1d_flush_mode) { 1144 case 0: 1145 syscall_ret_l1d_flush = NULL; 1146 break; 1147 case 1: 1148 syscall_ret_l1d_flush = l1d_hw ? flush_l1d_hw : 1149 flush_l1d_sw_abi; 1150 break; 1151 case 2: 1152 syscall_ret_l1d_flush = l1d_hw ? flush_l1d_hw : NULL; 1153 break; 1154 case 3: 1155 syscall_ret_l1d_flush = flush_l1d_sw_abi; 1156 break; 1157 default: 1158 syscall_ret_l1d_flush_mode = 1; 1159 goto again; 1160 } 1161 } 1162 1163 static int 1164 machdep_syscall_ret_flush_l1d(SYSCTL_HANDLER_ARGS) 1165 { 1166 int error, val; 1167 1168 val = syscall_ret_l1d_flush_mode; 1169 error = sysctl_handle_int(oidp, &val, 0, req); 1170 if (error != 0 || req->newptr == NULL) 1171 return (error); 1172 syscall_ret_l1d_flush_mode = val; 1173 amd64_syscall_ret_flush_l1d_recalc(); 1174 return (0); 1175 } 1176 SYSCTL_PROC(_machdep, OID_AUTO, syscall_ret_flush_l1d, CTLTYPE_INT | 1177 CTLFLAG_RWTUN | CTLFLAG_NOFETCH | CTLFLAG_MPSAFE, NULL, 0, 1178 machdep_syscall_ret_flush_l1d, "I", 1179 "Flush L1D on syscall return with error (0 - off, 1 - on, " 1180 "2 - use hw only, 3 - use sw only)"); 1181 1182 /* 1183 * System call handler for native binaries. The trap frame is already 1184 * set up by the assembler trampoline and a pointer to it is saved in 1185 * td_frame. 1186 */ 1187 void 1188 amd64_syscall(struct thread *td, int traced) 1189 { 1190 ksiginfo_t ksi; 1191 1192 kmsan_mark(td->td_frame, sizeof(*td->td_frame), KMSAN_STATE_INITED); 1193 1194 #ifdef DIAGNOSTIC 1195 if (!TRAPF_USERMODE(td->td_frame)) { 1196 panic("syscall"); 1197 /* NOT REACHED */ 1198 } 1199 #endif 1200 syscallenter(td); 1201 1202 /* 1203 * Traced syscall. 1204 */ 1205 if (__predict_false(traced)) { 1206 td->td_frame->tf_rflags &= ~PSL_T; 1207 ksiginfo_init_trap(&ksi); 1208 ksi.ksi_signo = SIGTRAP; 1209 ksi.ksi_code = TRAP_TRACE; 1210 ksi.ksi_addr = (void *)td->td_frame->tf_rip; 1211 trapsignal(td, &ksi); 1212 } 1213 1214 KASSERT(PCB_USER_FPU(td->td_pcb), 1215 ("System call %s returning with kernel FPU ctx leaked", 1216 syscallname(td->td_proc, td->td_sa.code))); 1217 KASSERT(td->td_pcb->pcb_save == get_pcb_user_save_td(td), 1218 ("System call %s returning with mangled pcb_save", 1219 syscallname(td->td_proc, td->td_sa.code))); 1220 KASSERT(pmap_not_in_di(), 1221 ("System call %s returning with leaked invl_gen %lu", 1222 syscallname(td->td_proc, td->td_sa.code), 1223 td->td_md.md_invl_gen.gen)); 1224 1225 syscallret(td); 1226 1227 /* 1228 * If the user-supplied value of %rip is not a canonical 1229 * address, then some CPUs will trigger a ring 0 #GP during 1230 * the sysret instruction. However, the fault handler would 1231 * execute in ring 0 with the user's %gs and %rsp which would 1232 * not be safe. Instead, use the full return path which 1233 * catches the problem safely. 1234 */ 1235 if (__predict_false(td->td_frame->tf_rip >= (la57 ? 1236 VM_MAXUSER_ADDRESS_LA57 : VM_MAXUSER_ADDRESS_LA48))) 1237 set_pcb_flags(td->td_pcb, PCB_FULL_IRET); 1238 1239 amd64_syscall_ret_flush_l1d_check_inline(td->td_errno); 1240 }
Cache object: 95b7d5f253a48e4286f8f633d9cee716
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