1 /*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * Copyright (C) 1994, David Greenman 5 * Copyright (c) 2008-2018 The DragonFly Project. 6 * Copyright (c) 2008 Jordan Gordeev. 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 * $FreeBSD: src/sys/i386/i386/trap.c,v 1.147.2.11 2003/02/27 19:09:59 luoqi Exp $ 41 */ 42 43 /* 44 * x86_64 Trap and System call handling 45 */ 46 47 #include "use_isa.h" 48 49 #include "opt_ddb.h" 50 #include "opt_ktrace.h" 51 52 #include <machine/frame.h> 53 #include <sys/param.h> 54 #include <sys/systm.h> 55 #include <sys/kernel.h> 56 #include <sys/kerneldump.h> 57 #include <sys/proc.h> 58 #include <sys/pioctl.h> 59 #include <sys/types.h> 60 #include <sys/signal2.h> 61 #include <sys/syscall.h> 62 #include <sys/sysctl.h> 63 #include <sys/sysent.h> 64 #ifdef KTRACE 65 #include <sys/ktrace.h> 66 #endif 67 #include <sys/ktr.h> 68 #include <sys/sysmsg.h> 69 70 #include <vm/pmap.h> 71 #include <vm/vm.h> 72 #include <vm/vm_extern.h> 73 #include <vm/vm_kern.h> 74 #include <vm/vm_param.h> 75 #include <machine/cpu.h> 76 #include <machine/pcb.h> 77 #include <machine/smp.h> 78 #include <machine/thread.h> 79 #include <machine/clock.h> 80 #include <machine/vmparam.h> 81 #include <machine/md_var.h> 82 #include <machine_base/isa/isa_intr.h> 83 #include <machine_base/apic/lapic.h> 84 85 #include <ddb/ddb.h> 86 87 #include <sys/thread2.h> 88 #include <sys/spinlock2.h> 89 90 /* 91 * These %rip's are used to detect a historical CPU artifact on syscall or 92 * int $3 entry, if not shortcutted in exception.S via 93 * DIRECT_DISALLOW_SS_CPUBUG. 94 */ 95 extern void Xbpt(void); 96 extern void Xfast_syscall(void); 97 #define IDTVEC(vec) X##vec 98 99 extern void trap(struct trapframe *frame); 100 101 static int trap_pfault(struct trapframe *, int); 102 static void trap_fatal(struct trapframe *, vm_offset_t); 103 void dblfault_handler(struct trapframe *frame); 104 105 #define MAX_TRAP_MSG 30 106 static char *trap_msg[] = { 107 "", /* 0 unused */ 108 "privileged instruction fault", /* 1 T_PRIVINFLT */ 109 "", /* 2 unused */ 110 "breakpoint instruction fault", /* 3 T_BPTFLT */ 111 "", /* 4 unused */ 112 "", /* 5 unused */ 113 "arithmetic trap", /* 6 T_ARITHTRAP */ 114 "system forced exception", /* 7 T_ASTFLT */ 115 "", /* 8 unused */ 116 "general protection fault", /* 9 T_PROTFLT */ 117 "trace trap", /* 10 T_TRCTRAP */ 118 "", /* 11 unused */ 119 "page fault", /* 12 T_PAGEFLT */ 120 "", /* 13 unused */ 121 "alignment fault", /* 14 T_ALIGNFLT */ 122 "", /* 15 unused */ 123 "", /* 16 unused */ 124 "", /* 17 unused */ 125 "integer divide fault", /* 18 T_DIVIDE */ 126 "non-maskable interrupt trap", /* 19 T_NMI */ 127 "overflow trap", /* 20 T_OFLOW */ 128 "FPU bounds check fault", /* 21 T_BOUND */ 129 "FPU device not available", /* 22 T_DNA */ 130 "double fault", /* 23 T_DOUBLEFLT */ 131 "FPU operand fetch fault", /* 24 T_FPOPFLT */ 132 "invalid TSS fault", /* 25 T_TSSFLT */ 133 "segment not present fault", /* 26 T_SEGNPFLT */ 134 "stack fault", /* 27 T_STKFLT */ 135 "machine check trap", /* 28 T_MCHK */ 136 "SIMD floating-point exception", /* 29 T_XMMFLT */ 137 "reserved (unknown) fault", /* 30 T_RESERVED */ 138 }; 139 140 #ifdef DDB 141 static int ddb_on_nmi = 1; 142 SYSCTL_INT(_machdep, OID_AUTO, ddb_on_nmi, CTLFLAG_RW, 143 &ddb_on_nmi, 0, "Go to DDB on NMI"); 144 static int ddb_on_seg_fault = 0; 145 SYSCTL_INT(_machdep, OID_AUTO, ddb_on_seg_fault, CTLFLAG_RW, 146 &ddb_on_seg_fault, 0, "Go to DDB on user seg-fault"); 147 __read_mostly static int freeze_on_seg_fault = 0; 148 SYSCTL_INT(_machdep, OID_AUTO, freeze_on_seg_fault, CTLFLAG_RW, 149 &freeze_on_seg_fault, 0, "Go to DDB on user seg-fault"); 150 #endif 151 static int panic_on_nmi = 1; 152 SYSCTL_INT(_machdep, OID_AUTO, panic_on_nmi, CTLFLAG_RW, 153 &panic_on_nmi, 0, "Panic on NMI"); 154 155 /* 156 * System call debugging records the worst-case system call 157 * overhead (inclusive of blocking), but may be inaccurate. 158 */ 159 /*#define SYSCALL_DEBUG*/ 160 #ifdef SYSCALL_DEBUG 161 162 #define SCWC_MAXT 30 163 164 struct syscallwc { 165 uint32_t idx; 166 uint32_t dummy; 167 uint64_t tot[SYS_MAXSYSCALL]; 168 uint64_t timings[SYS_MAXSYSCALL][SCWC_MAXT]; 169 } __cachealign; 170 171 struct syscallwc SysCallsWorstCase[MAXCPU]; 172 173 #endif 174 175 /* 176 * Passively intercepts the thread switch function to increase 177 * the thread priority from a user priority to a kernel priority, reducing 178 * syscall and trap overhead for the case where no switch occurs. 179 * 180 * Synchronizes td_ucred with p_ucred. This is used by system calls, 181 * signal handling, faults, AST traps, and anything else that enters the 182 * kernel from userland and provides the kernel with a stable read-only 183 * copy of the process ucred. 184 * 185 * To avoid races with another thread updating p_ucred we obtain p_spin. 186 * The other thread doing the update will obtain both p_token and p_spin. 187 * In the case where the cached cred pointer matches, we will already have 188 * the ref and we don't have to do one blessed thing. 189 */ 190 static __inline void 191 userenter(struct thread *curtd, struct proc *curp) 192 { 193 struct ucred *ocred; 194 struct ucred *ncred; 195 196 curtd->td_release = lwkt_passive_release; 197 198 if (__predict_false(curtd->td_ucred != curp->p_ucred)) { 199 spin_lock(&curp->p_spin); 200 ncred = crhold(curp->p_ucred); 201 spin_unlock(&curp->p_spin); 202 ocred = curtd->td_ucred; 203 curtd->td_ucred = ncred; 204 if (ocred) 205 crfree(ocred); 206 } 207 } 208 209 /* 210 * Handle signals, upcalls, profiling, and other AST's and/or tasks that 211 * must be completed before we can return to or try to return to userland. 212 * 213 * Note that td_sticks is a 64 bit quantity, but there's no point doing 64 214 * arithmatic on the delta calculation so the absolute tick values are 215 * truncated to an integer. 216 */ 217 static void 218 userret(struct lwp *lp, struct trapframe *frame, int sticks) 219 { 220 struct proc *p = lp->lwp_proc; 221 int sig; 222 int ptok; 223 224 /* 225 * Charge system time if profiling. Note: times are in microseconds. 226 * This may do a copyout and block, so do it first even though it 227 * means some system time will be charged as user time. 228 */ 229 if (__predict_false(p->p_flags & P_PROFIL)) { 230 addupc_task(p, frame->tf_rip, 231 (u_int)((int)lp->lwp_thread->td_sticks - sticks)); 232 } 233 234 recheck: 235 /* 236 * Specific on-return-to-usermode checks (LWP_MP_WEXIT, 237 * LWP_MP_VNLRU, etc). 238 */ 239 if (lp->lwp_mpflags & LWP_MP_URETMASK) 240 lwpuserret(lp); 241 242 /* 243 * Block here if we are in a stopped state. 244 */ 245 if (__predict_false(STOPLWP(p, lp))) { 246 lwkt_gettoken(&p->p_token); 247 tstop(); 248 lwkt_reltoken(&p->p_token); 249 goto recheck; 250 } 251 while (__predict_false(dump_stop_usertds)) { 252 tsleep(&dump_stop_usertds, 0, "dumpstp", 0); 253 } 254 255 /* 256 * Post any pending upcalls. If running a virtual kernel be sure 257 * to restore the virtual kernel's vmspace before posting the upcall. 258 */ 259 if (__predict_false(p->p_flags & (P_SIGVTALRM | P_SIGPROF))) { 260 lwkt_gettoken(&p->p_token); 261 if (p->p_flags & P_SIGVTALRM) { 262 p->p_flags &= ~P_SIGVTALRM; 263 ksignal(p, SIGVTALRM); 264 } 265 if (p->p_flags & P_SIGPROF) { 266 p->p_flags &= ~P_SIGPROF; 267 ksignal(p, SIGPROF); 268 } 269 lwkt_reltoken(&p->p_token); 270 goto recheck; 271 } 272 273 /* 274 * Post any pending signals. If running a virtual kernel be sure 275 * to restore the virtual kernel's vmspace before posting the signal. 276 * 277 * WARNING! postsig() can exit and not return. 278 */ 279 if (__predict_false((sig = CURSIG_LCK_TRACE(lp, &ptok)) != 0)) { 280 postsig(sig, ptok); 281 goto recheck; 282 } 283 284 /* 285 * In a multi-threaded program it is possible for a thread to change 286 * signal state during a system call which temporarily changes the 287 * signal mask. In this case postsig() might not be run and we 288 * have to restore the mask ourselves. 289 */ 290 if (__predict_false(lp->lwp_flags & LWP_OLDMASK)) { 291 lp->lwp_flags &= ~LWP_OLDMASK; 292 lp->lwp_sigmask = lp->lwp_oldsigmask; 293 goto recheck; 294 } 295 } 296 297 /* 298 * Cleanup from userenter and any passive release that might have occured. 299 * We must reclaim the current-process designation before we can return 300 * to usermode. We also handle both LWKT and USER reschedule requests. 301 */ 302 static __inline void 303 userexit(struct lwp *lp) 304 { 305 struct thread *td = lp->lwp_thread; 306 /* globaldata_t gd = td->td_gd; */ 307 308 /* 309 * Handle stop requests at kernel priority. Any requests queued 310 * after this loop will generate another AST. 311 */ 312 while (__predict_false(STOPLWP(lp->lwp_proc, lp))) { 313 lwkt_gettoken(&lp->lwp_proc->p_token); 314 tstop(); 315 lwkt_reltoken(&lp->lwp_proc->p_token); 316 } 317 318 /* 319 * Reduce our priority in preparation for a return to userland. If 320 * our passive release function was still in place, our priority was 321 * never raised and does not need to be reduced. 322 */ 323 lwkt_passive_recover(td); 324 325 /* WARNING: we may have migrated cpu's */ 326 /* gd = td->td_gd; */ 327 328 /* 329 * Become the current user scheduled process if we aren't already, 330 * and deal with reschedule requests and other factors. 331 * 332 * Do a silly hack to avoid RETPOLINE nonsense. 333 */ 334 if (lp->lwp_proc->p_usched == &usched_dfly) 335 dfly_acquire_curproc(lp); 336 else 337 lp->lwp_proc->p_usched->acquire_curproc(lp); 338 } 339 340 /* 341 * A page fault on a userspace address is classified as SMAP-induced 342 * if: 343 * - SMAP is supported 344 * - kernel mode accessed present data page 345 * - rflags.AC was cleared 346 */ 347 static int 348 trap_is_smap(struct trapframe *frame) 349 { 350 if ((cpu_stdext_feature & CPUID_STDEXT_SMAP) != 0 && 351 (frame->tf_err & (PGEX_P | PGEX_U | PGEX_I | PGEX_RSV)) == PGEX_P && 352 (frame->tf_rflags & PSL_AC) == 0) { 353 return 1; 354 } else { 355 return 0; 356 } 357 } 358 359 #if !defined(KTR_KERNENTRY) 360 #define KTR_KERNENTRY KTR_ALL 361 #endif 362 KTR_INFO_MASTER(kernentry); 363 KTR_INFO(KTR_KERNENTRY, kernentry, trap, 0, 364 "TRAP(pid %d, tid %d, trapno %ld, eva %lu)", 365 pid_t pid, lwpid_t tid, register_t trapno, vm_offset_t eva); 366 KTR_INFO(KTR_KERNENTRY, kernentry, trap_ret, 0, "TRAP_RET(pid %d, tid %d)", 367 pid_t pid, lwpid_t tid); 368 KTR_INFO(KTR_KERNENTRY, kernentry, syscall, 0, "SYSC(pid %d, tid %d, nr %ld)", 369 pid_t pid, lwpid_t tid, register_t trapno); 370 KTR_INFO(KTR_KERNENTRY, kernentry, syscall_ret, 0, "SYSRET(pid %d, tid %d, err %d)", 371 pid_t pid, lwpid_t tid, int err); 372 KTR_INFO(KTR_KERNENTRY, kernentry, fork_ret, 0, "FORKRET(pid %d, tid %d)", 373 pid_t pid, lwpid_t tid); 374 375 /* 376 * Exception, fault, and trap interface to the kernel. 377 * This common code is called from assembly language IDT gate entry 378 * routines that prepare a suitable stack frame, and restore this 379 * frame after the exception has been processed. 380 * 381 * This function is also called from doreti in an interlock to handle ASTs. 382 * For example: hardwareint->INTROUTINE->(set ast)->doreti->trap 383 * 384 * NOTE! We have to retrieve the fault address prior to potentially 385 * blocking, including blocking on any token. 386 * 387 * NOTE! NMI and kernel DBG traps remain on their respective pcpu IST 388 * stacks if taken from a kernel RPL. trap() cannot block in this 389 * situation. DDB entry or a direct report-and-return is ok. 390 * 391 * XXX gd_trap_nesting_level currently prevents lwkt_switch() from panicing 392 * if an attempt is made to switch from a fast interrupt or IPI. 393 */ 394 void 395 trap(struct trapframe *frame) 396 { 397 static struct krate sscpubugrate = { 1 }; 398 struct globaldata *gd = mycpu; 399 struct thread *td = gd->gd_curthread; 400 struct lwp *lp = td->td_lwp; 401 struct proc *p; 402 int sticks = 0; 403 int i = 0, ucode = 0, type, code; 404 #ifdef INVARIANTS 405 int crit_count = td->td_critcount; 406 lwkt_tokref_t curstop = td->td_toks_stop; 407 #endif 408 vm_offset_t eva; 409 410 p = td->td_proc; 411 clear_quickret(); 412 413 #ifdef DDB 414 /* 415 * We need to allow T_DNA faults when the debugger is active since 416 * some dumping paths do large bcopy() which use the floating 417 * point registers for faster copying. 418 */ 419 if (db_active && frame->tf_trapno != T_DNA) { 420 eva = (frame->tf_trapno == T_PAGEFLT ? frame->tf_addr : 0); 421 ++gd->gd_trap_nesting_level; 422 trap_fatal(frame, eva); 423 --gd->gd_trap_nesting_level; 424 goto out2; 425 } 426 #endif 427 428 eva = 0; 429 430 if ((frame->tf_rflags & PSL_I) == 0) { 431 /* 432 * Buggy application or kernel code has disabled interrupts 433 * and then trapped. Enabling interrupts now is wrong, but 434 * it is better than running with interrupts disabled until 435 * they are accidentally enabled later. 436 */ 437 438 type = frame->tf_trapno; 439 if (ISPL(frame->tf_cs) == SEL_UPL) { 440 /* JG curproc can be NULL */ 441 kprintf( 442 "pid %ld (%s): trap %d with interrupts disabled\n", 443 (long)curproc->p_pid, curproc->p_comm, type); 444 } else if ((type == T_STKFLT || type == T_PROTFLT || 445 type == T_SEGNPFLT) && 446 frame->tf_rip == (long)doreti_iret) { 447 /* 448 * iretq fault from kernel mode during return to 449 * userland. 450 * 451 * This situation is expected, don't complain. 452 */ 453 } else if (type != T_NMI && type != T_BPTFLT && 454 type != T_TRCTRAP) { 455 /* 456 * XXX not quite right, since this may be for a 457 * multiple fault in user mode. 458 */ 459 kprintf("kernel trap %d (%s @ 0x%016jx) with " 460 "interrupts disabled\n", 461 type, 462 td->td_comm, 463 frame->tf_rip); 464 } 465 cpu_enable_intr(); 466 } 467 468 type = frame->tf_trapno; 469 code = frame->tf_err; 470 471 if (ISPL(frame->tf_cs) == SEL_UPL) { 472 /* user trap */ 473 474 KTR_LOG(kernentry_trap, p->p_pid, lp->lwp_tid, 475 frame->tf_trapno, eva); 476 477 userenter(td, p); 478 479 sticks = (int)td->td_sticks; 480 KASSERT(lp->lwp_md.md_regs == frame, 481 ("Frame mismatch %p %p", lp->lwp_md.md_regs, frame)); 482 483 switch (type) { 484 case T_PRIVINFLT: /* privileged instruction fault */ 485 i = SIGILL; 486 ucode = ILL_PRVOPC; 487 break; 488 489 case T_BPTFLT: /* bpt instruction fault */ 490 case T_TRCTRAP: /* trace trap */ 491 frame->tf_rflags &= ~PSL_T; 492 i = SIGTRAP; 493 ucode = (type == T_TRCTRAP ? TRAP_TRACE : TRAP_BRKPT); 494 break; 495 496 case T_ARITHTRAP: /* arithmetic trap */ 497 ucode = code; 498 i = SIGFPE; 499 break; 500 501 case T_ASTFLT: /* Allow process switch */ 502 mycpu->gd_cnt.v_soft++; 503 if (mycpu->gd_reqflags & RQF_AST_OWEUPC) { 504 atomic_clear_int(&mycpu->gd_reqflags, 505 RQF_AST_OWEUPC); 506 addupc_task(p, p->p_prof.pr_addr, 507 p->p_prof.pr_ticks); 508 } 509 goto out; 510 511 case T_PROTFLT: /* general protection fault */ 512 i = SIGBUS; 513 ucode = BUS_OBJERR; 514 break; 515 case T_STKFLT: /* stack fault */ 516 case T_SEGNPFLT: /* segment not present fault */ 517 i = SIGBUS; 518 ucode = BUS_ADRERR; 519 break; 520 case T_TSSFLT: /* invalid TSS fault */ 521 case T_DOUBLEFLT: /* double fault */ 522 default: 523 i = SIGBUS; 524 ucode = BUS_OBJERR; 525 break; 526 527 case T_PAGEFLT: /* page fault */ 528 i = trap_pfault(frame, TRUE); 529 #ifdef DDB 530 if (frame->tf_rip == 0) { 531 /* used for kernel debugging only */ 532 while (freeze_on_seg_fault) 533 tsleep(p, 0, "freeze", hz * 20); 534 } 535 #endif 536 if (i == -1 || i == 0) 537 goto out; 538 if (i == SIGSEGV) { 539 ucode = SEGV_MAPERR; 540 } else { 541 i = SIGSEGV; 542 ucode = SEGV_ACCERR; 543 } 544 break; 545 546 case T_DIVIDE: /* integer divide fault */ 547 ucode = FPE_INTDIV; 548 i = SIGFPE; 549 break; 550 551 #if NISA > 0 552 case T_NMI: 553 /* machine/parity/power fail/"kitchen sink" faults */ 554 if (isa_nmi(code) == 0) { 555 #ifdef DDB 556 /* 557 * NMI can be hooked up to a pushbutton 558 * for debugging. 559 */ 560 if (ddb_on_nmi) { 561 kprintf ("NMI ... going to debugger\n"); 562 kdb_trap(type, 0, frame); 563 } 564 #endif /* DDB */ 565 goto out2; 566 } else if (panic_on_nmi) 567 panic("NMI indicates hardware failure"); 568 break; 569 #endif /* NISA > 0 */ 570 571 case T_OFLOW: /* integer overflow fault */ 572 ucode = FPE_INTOVF; 573 i = SIGFPE; 574 break; 575 576 case T_BOUND: /* bounds check fault */ 577 ucode = FPE_FLTSUB; 578 i = SIGFPE; 579 break; 580 581 case T_DNA: 582 /* 583 * Virtual kernel intercept - pass the DNA exception 584 * to the virtual kernel if it asked to handle it. 585 * This occurs when the virtual kernel is holding 586 * onto the FP context for a different emulated 587 * process then the one currently running. 588 * 589 * We must still call npxdna() since we may have 590 * saved FP state that the virtual kernel needs 591 * to hand over to a different emulated process. 592 */ 593 if (lp->lwp_vkernel && lp->lwp_vkernel->ve && 594 (td->td_pcb->pcb_flags & FP_VIRTFP) 595 ) { 596 npxdna(); 597 break; 598 } 599 600 /* 601 * The kernel may have switched out the FP unit's 602 * state, causing the user process to take a fault 603 * when it tries to use the FP unit. Restore the 604 * state here 605 */ 606 if (npxdna()) { 607 gd->gd_cnt.v_trap++; 608 goto out; 609 } 610 i = SIGFPE; 611 ucode = FPE_FPU_NP_TRAP; 612 break; 613 614 case T_FPOPFLT: /* FPU operand fetch fault */ 615 ucode = ILL_COPROC; 616 i = SIGILL; 617 break; 618 619 case T_XMMFLT: /* SIMD floating-point exception */ 620 ucode = 0; /* XXX */ 621 i = SIGFPE; 622 break; 623 } 624 } else { 625 /* kernel trap */ 626 627 switch (type) { 628 case T_PAGEFLT: /* page fault */ 629 trap_pfault(frame, FALSE); 630 goto out2; 631 632 case T_DNA: 633 /* 634 * The kernel is apparently using fpu for copying. 635 * XXX this should be fatal unless the kernel has 636 * registered such use. 637 */ 638 if (npxdna()) { 639 gd->gd_cnt.v_trap++; 640 goto out2; 641 } 642 break; 643 644 case T_STKFLT: /* stack fault */ 645 case T_PROTFLT: /* general protection fault */ 646 case T_SEGNPFLT: /* segment not present fault */ 647 /* 648 * Invalid segment selectors and out of bounds 649 * %rip's and %rsp's can be set up in user mode. 650 * This causes a fault in kernel mode when the 651 * kernel tries to return to user mode. We want 652 * to get this fault so that we can fix the 653 * problem here and not have to check all the 654 * selectors and pointers when the user changes 655 * them. 656 */ 657 if (mycpu->gd_intr_nesting_level == 0) { 658 /* 659 * NOTE: in 64-bit mode traps push rsp/ss 660 * even if no ring change occurs. 661 */ 662 if (td->td_pcb->pcb_onfault && 663 td->td_pcb->pcb_onfault_sp == 664 frame->tf_rsp) { 665 frame->tf_rip = (register_t) 666 td->td_pcb->pcb_onfault; 667 goto out2; 668 } 669 670 /* 671 * If the iretq in doreti faults during 672 * return to user, it will be special-cased 673 * in IDTVEC(prot) to get here. We want 674 * to 'return' to doreti_iret_fault in 675 * ipl.s in approximately the same state we 676 * were in at the iretq. 677 */ 678 if (frame->tf_rip == (long)doreti_iret) { 679 frame->tf_rip = (long)doreti_iret_fault; 680 goto out2; 681 } 682 } 683 break; 684 685 case T_TSSFLT: 686 /* 687 * PSL_NT can be set in user mode and isn't cleared 688 * automatically when the kernel is entered. This 689 * causes a TSS fault when the kernel attempts to 690 * `iret' because the TSS link is uninitialized. We 691 * want to get this fault so that we can fix the 692 * problem here and not every time the kernel is 693 * entered. 694 */ 695 if (frame->tf_rflags & PSL_NT) { 696 frame->tf_rflags &= ~PSL_NT; 697 #if 0 698 /* do we need this? */ 699 if (frame->tf_rip == (long)doreti_iret) 700 frame->tf_rip = (long)doreti_iret_fault; 701 #endif 702 goto out2; 703 } 704 break; 705 706 case T_TRCTRAP: /* trace trap */ 707 /* 708 * Detect historical CPU artifact on syscall or int $3 709 * entry (if not shortcutted in exception.s via 710 * DIRECT_DISALLOW_SS_CPUBUG). 711 */ 712 gd->gd_cnt.v_trap++; 713 if (frame->tf_rip == (register_t)IDTVEC(fast_syscall)) { 714 krateprintf(&sscpubugrate, 715 "Caught #DB at syscall cpu artifact\n"); 716 goto out2; 717 } 718 if (frame->tf_rip == (register_t)IDTVEC(bpt)) { 719 krateprintf(&sscpubugrate, 720 "Caught #DB at int $N cpu artifact\n"); 721 goto out2; 722 } 723 724 /* 725 * Ignore debug register trace traps due to 726 * accesses in the user's address space, which 727 * can happen under several conditions such as 728 * if a user sets a watchpoint on a buffer and 729 * then passes that buffer to a system call. 730 * We still want to get TRCTRAPS for addresses 731 * in kernel space because that is useful when 732 * debugging the kernel. 733 */ 734 if (user_dbreg_trap()) { 735 /* 736 * Reset breakpoint bits because the 737 * processor doesn't 738 */ 739 load_dr6(rdr6() & ~0xf); 740 goto out2; 741 } 742 /* 743 * FALLTHROUGH (TRCTRAP kernel mode, kernel address) 744 */ 745 case T_BPTFLT: 746 /* 747 * If DDB is enabled, let it handle the debugger trap. 748 * Otherwise, debugger traps "can't happen". 749 */ 750 ucode = TRAP_BRKPT; 751 #ifdef DDB 752 if (kdb_trap(type, 0, frame)) 753 goto out2; 754 #endif 755 break; 756 757 #if NISA > 0 758 case T_NMI: 759 /* machine/parity/power fail/"kitchen sink" faults */ 760 if (isa_nmi(code) == 0) { 761 #ifdef DDB 762 /* 763 * NMI can be hooked up to a pushbutton 764 * for debugging. 765 */ 766 if (ddb_on_nmi) { 767 kprintf ("NMI ... going to debugger\n"); 768 kdb_trap(type, 0, frame); 769 } 770 #endif /* DDB */ 771 goto out2; 772 } else if (panic_on_nmi == 0) 773 goto out2; 774 #endif /* NISA > 0 */ 775 break; 776 default: 777 if (type >= T_RESERVED && type < T_RESERVED + 256) { 778 kprintf("Ignoring spurious unknown " 779 "cpu trap T_RESERVED+%d\n", 780 type - T_RESERVED); 781 gd->gd_cnt.v_trap++; 782 goto out2; 783 } 784 break; 785 } 786 trap_fatal(frame, 0); 787 goto out2; 788 } 789 790 /* 791 * Fault from user mode, virtual kernel interecept. 792 * 793 * If the fault is directly related to a VM context managed by a 794 * virtual kernel then let the virtual kernel handle it. 795 */ 796 if (lp->lwp_vkernel && lp->lwp_vkernel->ve) { 797 vkernel_trap(lp, frame); 798 goto out; 799 } 800 801 /* Translate fault for emulators (e.g. Linux) */ 802 if (*p->p_sysent->sv_transtrap) 803 i = (*p->p_sysent->sv_transtrap)(i, type); 804 805 gd->gd_cnt.v_trap++; 806 trapsignal(lp, i, ucode); 807 808 #ifdef DEBUG 809 if (type <= MAX_TRAP_MSG) { 810 uprintf("fatal process exception: %s", 811 trap_msg[type]); 812 if ((type == T_PAGEFLT) || (type == T_PROTFLT)) 813 uprintf(", fault VA = 0x%lx", frame->tf_addr); 814 uprintf("\n"); 815 } 816 #endif 817 818 out: 819 userret(lp, frame, sticks); 820 userexit(lp); 821 out2: ; 822 if (p != NULL && lp != NULL) 823 KTR_LOG(kernentry_trap_ret, p->p_pid, lp->lwp_tid); 824 #ifdef INVARIANTS 825 KASSERT(crit_count == td->td_critcount, 826 ("trap: critical section count mismatch! %d/%d", 827 crit_count, td->td_pri)); 828 KASSERT(curstop == td->td_toks_stop, 829 ("trap: extra tokens held after trap! %ld/%ld (%s)", 830 curstop - &td->td_toks_base, 831 td->td_toks_stop - &td->td_toks_base, 832 td->td_toks_stop[-1].tr_tok->t_desc)); 833 #endif 834 } 835 836 void 837 trap_handle_userenter(struct thread *td) 838 { 839 userenter(td, td->td_proc); 840 } 841 842 void 843 trap_handle_userexit(struct trapframe *frame, int sticks) 844 { 845 struct lwp *lp = curthread->td_lwp; 846 847 if (lp) { 848 userret(lp, frame, sticks); 849 userexit(lp); 850 } 851 } 852 853 static int 854 trap_pfault(struct trapframe *frame, int usermode) 855 { 856 vm_offset_t va; 857 struct vmspace *vm = NULL; 858 vm_map_t map; 859 int rv = 0; 860 int fault_flags; 861 vm_prot_t ftype; 862 thread_t td = curthread; 863 struct lwp *lp = td->td_lwp; 864 struct proc *p; 865 866 va = trunc_page(frame->tf_addr); 867 if (va >= VM_MIN_KERNEL_ADDRESS) { 868 /* 869 * Don't allow user-mode faults in kernel address space. 870 */ 871 if (usermode) { 872 fault_flags = -1; 873 ftype = -1; 874 goto nogo; 875 } 876 877 map = kernel_map; 878 } else { 879 /* 880 * This is a fault on non-kernel virtual memory. 881 * vm is initialized above to NULL. If curproc is NULL 882 * or curproc->p_vmspace is NULL the fault is fatal. 883 */ 884 if (lp != NULL) 885 vm = lp->lwp_vmspace; 886 887 if (vm == NULL) { 888 fault_flags = -1; 889 ftype = -1; 890 goto nogo; 891 } 892 893 if (usermode == 0) { 894 #ifdef DDB 895 /* 896 * Debugging, catch kernel faults on the user address 897 * space when not inside on onfault (e.g. copyin/ 898 * copyout) routine. 899 */ 900 if (td->td_pcb == NULL || 901 td->td_pcb->pcb_onfault == NULL) { 902 if (freeze_on_seg_fault) { 903 kprintf("trap_pfault: user address " 904 "fault from kernel mode " 905 "%016lx\n", 906 (long)frame->tf_addr); 907 while (freeze_on_seg_fault) { 908 tsleep(&freeze_on_seg_fault, 909 0, 910 "frzseg", 911 hz * 20); 912 } 913 } 914 } 915 #endif 916 if (td->td_gd->gd_intr_nesting_level || 917 trap_is_smap(frame) || 918 td->td_pcb == NULL || 919 td->td_pcb->pcb_onfault == NULL) { 920 kprintf("Fatal user address access " 921 "from kernel mode from %s at %016jx\n", 922 td->td_comm, frame->tf_rip); 923 trap_fatal(frame, frame->tf_addr); 924 return (-1); 925 } 926 } 927 map = &vm->vm_map; 928 } 929 930 /* 931 * PGEX_I is defined only if the execute disable bit capability is 932 * supported and enabled. 933 */ 934 if (frame->tf_err & PGEX_W) 935 ftype = VM_PROT_WRITE; 936 else if (frame->tf_err & PGEX_I) 937 ftype = VM_PROT_EXECUTE; 938 else 939 ftype = VM_PROT_READ; 940 941 lwkt_tokref_t stop = td->td_toks_stop; 942 943 if (map != kernel_map) { 944 /* 945 * Keep swapout from messing with us during this 946 * critical time. 947 */ 948 PHOLD(lp->lwp_proc); 949 950 /* 951 * Issue fault 952 */ 953 fault_flags = 0; 954 if (usermode) 955 fault_flags |= VM_FAULT_BURST | VM_FAULT_USERMODE; 956 if (ftype & VM_PROT_WRITE) 957 fault_flags |= VM_FAULT_DIRTY; 958 else 959 fault_flags |= VM_FAULT_NORMAL; 960 rv = vm_fault(map, va, ftype, fault_flags); 961 if (td->td_toks_stop != stop) { 962 stop = td->td_toks_stop - 1; 963 kprintf("A-HELD TOKENS DURING PFAULT td=%p(%s) map=%p va=%p ftype=%d fault_flags=%d\n", td, td->td_comm, map, (void *)va, ftype, fault_flags); 964 panic("held tokens"); 965 } 966 967 PRELE(lp->lwp_proc); 968 } else { 969 /* 970 * Don't have to worry about process locking or stacks in the 971 * kernel. 972 */ 973 fault_flags = VM_FAULT_NORMAL; 974 rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL); 975 if (td->td_toks_stop != stop) { 976 stop = td->td_toks_stop - 1; 977 kprintf("B-HELD TOKENS DURING PFAULT td=%p(%s) map=%p va=%p ftype=%d fault_flags=%d\n", td, td->td_comm, map, (void *)va, ftype, VM_FAULT_NORMAL); 978 panic("held tokens"); 979 } 980 } 981 if (rv == KERN_SUCCESS) 982 return (0); 983 nogo: 984 if (!usermode) { 985 /* 986 * NOTE: in 64-bit mode traps push rsp/ss 987 * even if no ring change occurs. 988 */ 989 if (td->td_pcb->pcb_onfault && 990 td->td_pcb->pcb_onfault_sp == frame->tf_rsp && 991 td->td_gd->gd_intr_nesting_level == 0) { 992 frame->tf_rip = (register_t)td->td_pcb->pcb_onfault; 993 return (0); 994 } 995 trap_fatal(frame, frame->tf_addr); 996 return (-1); 997 } 998 999 /* 1000 * NOTE: on x86_64 we have a tf_addr field in the trapframe, no 1001 * kludge is needed to pass the fault address to signal handlers. 1002 */ 1003 p = td->td_proc; 1004 #ifdef DDB 1005 if (td->td_lwp->lwp_vkernel == NULL) { 1006 while (freeze_on_seg_fault) { 1007 tsleep(p, 0, "freeze", hz * 20); 1008 } 1009 if (ddb_on_seg_fault) 1010 Debugger("ddb_on_seg_fault"); 1011 } 1012 #endif 1013 1014 return((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV); 1015 } 1016 1017 static void 1018 trap_fatal(struct trapframe *frame, vm_offset_t eva) 1019 { 1020 int code, ss; 1021 u_int type; 1022 long rsp; 1023 struct soft_segment_descriptor softseg; 1024 1025 code = frame->tf_err; 1026 type = frame->tf_trapno; 1027 sdtossd(&mdcpu->gd_gdt[IDXSEL(frame->tf_cs & 0xffff)], &softseg); 1028 1029 kprintf("\n\nFatal trap %d: ", type); 1030 if (type <= MAX_TRAP_MSG) 1031 kprintf("%s ", trap_msg[type]); 1032 else 1033 kprintf("rsvd(%d) ", type - T_RESERVED); 1034 1035 kprintf("while in %s mode\n", 1036 ISPL(frame->tf_cs) == SEL_UPL ? "user" : "kernel"); 1037 1038 /* three separate prints in case of a trap on an unmapped page */ 1039 kprintf("cpuid = %d; ", mycpu->gd_cpuid); 1040 if (lapic_usable) 1041 kprintf("lapic id = %u\n", LAPIC_READID); 1042 if (type == T_PAGEFLT) { 1043 kprintf("fault virtual address = 0x%lx\n", eva); 1044 kprintf("fault code = %s %s %s, %s\n", 1045 code & PGEX_U ? "user" : "supervisor", 1046 code & PGEX_W ? "write" : "read", 1047 code & PGEX_I ? "instruction" : "data", 1048 code & PGEX_P ? "protection violation" : "page not present"); 1049 } 1050 kprintf("instruction pointer = 0x%lx:0x%lx\n", 1051 frame->tf_cs & 0xffff, frame->tf_rip); 1052 if (ISPL(frame->tf_cs) == SEL_UPL) { 1053 ss = frame->tf_ss & 0xffff; 1054 rsp = frame->tf_rsp; 1055 } else { 1056 /* 1057 * NOTE: in 64-bit mode traps push rsp/ss even if no ring 1058 * change occurs. 1059 */ 1060 ss = GSEL(GDATA_SEL, SEL_KPL); 1061 rsp = frame->tf_rsp; 1062 } 1063 kprintf("stack pointer = 0x%x:0x%lx\n", ss, rsp); 1064 kprintf("frame pointer = 0x%x:0x%lx\n", ss, frame->tf_rbp); 1065 kprintf("code segment = base 0x%lx, limit 0x%lx, type 0x%x\n", 1066 softseg.ssd_base, softseg.ssd_limit, softseg.ssd_type); 1067 kprintf(" = DPL %d, pres %d, long %d, def32 %d, gran %d\n", 1068 softseg.ssd_dpl, softseg.ssd_p, softseg.ssd_long, softseg.ssd_def32, 1069 softseg.ssd_gran); 1070 kprintf("processor eflags = "); 1071 if (frame->tf_rflags & PSL_T) 1072 kprintf("trace trap, "); 1073 if (frame->tf_rflags & PSL_I) 1074 kprintf("interrupt enabled, "); 1075 if (frame->tf_rflags & PSL_NT) 1076 kprintf("nested task, "); 1077 if (frame->tf_rflags & PSL_RF) 1078 kprintf("resume, "); 1079 if (frame->tf_rflags & PSL_AC) 1080 kprintf("smap_open, "); 1081 kprintf("IOPL = %ld\n", (frame->tf_rflags & PSL_IOPL) >> 12); 1082 kprintf("current process = "); 1083 if (curproc) { 1084 kprintf("%lu\n", 1085 (u_long)curproc->p_pid); 1086 } else { 1087 kprintf("Idle\n"); 1088 } 1089 kprintf("current thread = pri %d ", curthread->td_pri); 1090 if (curthread->td_critcount) 1091 kprintf("(CRIT)"); 1092 kprintf("\n"); 1093 1094 #ifdef DDB 1095 if ((debugger_on_panic || db_active) && kdb_trap(type, code, frame)) 1096 return; 1097 #endif 1098 kprintf("trap number = %d\n", type); 1099 if (type <= MAX_TRAP_MSG) 1100 panic("%s", trap_msg[type]); 1101 else 1102 panic("unknown/reserved trap"); 1103 } 1104 1105 /* 1106 * Double fault handler. Called when a fault occurs while writing 1107 * a frame for a trap/exception onto the stack. This usually occurs 1108 * when the stack overflows (such is the case with infinite recursion, 1109 * for example). 1110 */ 1111 static __inline 1112 int 1113 in_kstack_guard(register_t rptr) 1114 { 1115 thread_t td = curthread; 1116 1117 if ((char *)rptr >= td->td_kstack && 1118 (char *)rptr < td->td_kstack + PAGE_SIZE) { 1119 return 1; 1120 } 1121 return 0; 1122 } 1123 1124 void 1125 dblfault_handler(struct trapframe *frame) 1126 { 1127 thread_t td = curthread; 1128 1129 if (in_kstack_guard(frame->tf_rsp) || in_kstack_guard(frame->tf_rbp)) { 1130 kprintf("DOUBLE FAULT - KERNEL STACK GUARD HIT!\n"); 1131 if (in_kstack_guard(frame->tf_rsp)) 1132 frame->tf_rsp = (register_t)(td->td_kstack + PAGE_SIZE); 1133 if (in_kstack_guard(frame->tf_rbp)) 1134 frame->tf_rbp = (register_t)(td->td_kstack + PAGE_SIZE); 1135 } else { 1136 kprintf("DOUBLE FAULT\n"); 1137 } 1138 kprintf("\nFatal double fault\n"); 1139 kprintf("rip = 0x%lx\n", frame->tf_rip); 1140 kprintf("rsp = 0x%lx\n", frame->tf_rsp); 1141 kprintf("rbp = 0x%lx\n", frame->tf_rbp); 1142 /* three separate prints in case of a trap on an unmapped page */ 1143 kprintf("cpuid = %d; ", mycpu->gd_cpuid); 1144 if (lapic_usable) 1145 kprintf("lapic id = %u\n", LAPIC_READID); 1146 panic("double fault"); 1147 } 1148 1149 /* 1150 * syscall2 - MP aware system call request C handler 1151 * 1152 * A system call is essentially treated as a trap except that the 1153 * MP lock is not held on entry or return. We are responsible for 1154 * obtaining the MP lock if necessary and for handling ASTs 1155 * (e.g. a task switch) prior to return. 1156 */ 1157 void 1158 syscall2(struct trapframe *frame) 1159 { 1160 struct thread *td = curthread; 1161 struct proc *p = td->td_proc; 1162 struct lwp *lp = td->td_lwp; 1163 struct sysent *callp; 1164 register_t orig_tf_rflags; 1165 int sticks; 1166 int error; 1167 int narg; 1168 #ifdef INVARIANTS 1169 int crit_count = td->td_critcount; 1170 #endif 1171 struct sysmsg sysmsg; 1172 union sysunion *argp; 1173 u_int code; 1174 const int regcnt = 6; /* number of args passed in registers */ 1175 1176 mycpu->gd_cnt.v_syscall++; 1177 1178 #ifdef DIAGNOSTIC 1179 if (__predict_false(ISPL(frame->tf_cs) != SEL_UPL)) { 1180 panic("syscall"); 1181 /* NOT REACHED */ 1182 } 1183 #endif 1184 1185 KTR_LOG(kernentry_syscall, p->p_pid, lp->lwp_tid, 1186 frame->tf_rax); 1187 1188 userenter(td, p); /* lazy raise our priority */ 1189 1190 /* 1191 * Misc 1192 */ 1193 sticks = (int)td->td_sticks; 1194 orig_tf_rflags = frame->tf_rflags; 1195 1196 /* 1197 * Virtual kernel intercept - if a VM context managed by a virtual 1198 * kernel issues a system call the virtual kernel handles it, not us. 1199 * Restore the virtual kernel context and return from its system 1200 * call. The current frame is copied out to the virtual kernel. 1201 */ 1202 if (__predict_false(lp->lwp_vkernel && lp->lwp_vkernel->ve)) { 1203 vkernel_trap(lp, frame); 1204 error = EJUSTRETURN; 1205 callp = NULL; 1206 code = 0; 1207 goto out; 1208 } 1209 1210 /* 1211 * Get the system call parameters and account for time 1212 */ 1213 #ifdef DIAGNOSTIC 1214 KASSERT(lp->lwp_md.md_regs == frame, 1215 ("Frame mismatch %p %p", lp->lwp_md.md_regs, frame)); 1216 #endif 1217 1218 code = (u_int)frame->tf_rax; 1219 if (code >= p->p_sysent->sv_size) 1220 code = SYS___nosys; 1221 1222 argp = (union sysunion *)&frame->tf_rdi; 1223 callp = &p->p_sysent->sv_table[code]; 1224 1225 /* 1226 * On x86_64 we get up to six arguments in registers. The rest are 1227 * on the stack. The first six members of 'struct trapframe' happen 1228 * to be the registers used to pass arguments, in exactly the right 1229 * order. 1230 * 1231 * Any arguments beyond available argument-passing registers must 1232 * be copyin()'d from the user stack. 1233 */ 1234 narg = callp->sy_narg; 1235 if (__predict_false(narg > regcnt)) { 1236 register_t *argsdst; 1237 caddr_t params; 1238 1239 argsdst = (register_t *)&sysmsg.extargs; 1240 bcopy(argp, argsdst, sizeof(register_t) * regcnt); 1241 params = (caddr_t)frame->tf_rsp + sizeof(register_t); 1242 error = copyin(params, &argsdst[regcnt], 1243 (narg - regcnt) * sizeof(register_t)); 1244 argp = (void *)argsdst; 1245 if (error) { 1246 #ifdef KTRACE 1247 if (KTRPOINTP(p, td, KTR_SYSCALL)) { 1248 ktrsyscall(lp, code, narg, argp); 1249 } 1250 #endif 1251 goto bad; 1252 } 1253 } 1254 1255 #ifdef KTRACE 1256 if (KTRPOINTP(p, td, KTR_SYSCALL)) { 1257 ktrsyscall(lp, code, narg, argp); 1258 } 1259 #endif 1260 1261 /* 1262 * Default return value is 0 (will be copied to %rax). Double-value 1263 * returns use %rax and %rdx. %rdx is left unchanged for system 1264 * calls which return only one result. 1265 */ 1266 sysmsg.sysmsg_fds[0] = 0; 1267 sysmsg.sysmsg_fds[1] = frame->tf_rdx; 1268 1269 /* 1270 * The syscall might manipulate the trap frame. If it does it 1271 * will probably return EJUSTRETURN. 1272 */ 1273 sysmsg.sysmsg_frame = frame; 1274 1275 STOPEVENT(p, S_SCE, narg); /* MP aware */ 1276 1277 /* 1278 * NOTE: All system calls run MPSAFE now. The system call itself 1279 * is responsible for getting the MP lock. 1280 */ 1281 #ifdef SYSCALL_DEBUG 1282 tsc_uclock_t tscval = rdtsc(); 1283 #endif 1284 error = (*callp->sy_call)(&sysmsg, argp); 1285 #ifdef SYSCALL_DEBUG 1286 tscval = rdtsc() - tscval; 1287 tscval = tscval * 1000000 / (tsc_frequency / 1000); /* ns */ 1288 { 1289 struct syscallwc *scwc = &SysCallsWorstCase[mycpu->gd_cpuid]; 1290 int idx = scwc->idx++ % SCWC_MAXT; 1291 1292 scwc->tot[code] += tscval - scwc->timings[code][idx]; 1293 scwc->timings[code][idx] = tscval; 1294 } 1295 #endif 1296 1297 out: 1298 /* 1299 * MP SAFE (we may or may not have the MP lock at this point) 1300 */ 1301 //kprintf("SYSMSG %d ", error); 1302 if (__predict_true(error == 0)) { 1303 /* 1304 * Reinitialize proc pointer `p' as it may be different 1305 * if this is a child returning from fork syscall. 1306 */ 1307 p = curproc; 1308 lp = curthread->td_lwp; 1309 frame->tf_rax = sysmsg.sysmsg_fds[0]; 1310 frame->tf_rdx = sysmsg.sysmsg_fds[1]; 1311 frame->tf_rflags &= ~PSL_C; 1312 } else if (error == ERESTART) { 1313 /* 1314 * Reconstruct pc, we know that 'syscall' is 2 bytes. 1315 * We have to do a full context restore so that %r10 1316 * (which was holding the value of %rcx) is restored for 1317 * the next iteration. 1318 */ 1319 if (frame->tf_err != 0 && frame->tf_err != 2) 1320 kprintf("lp %s:%d frame->tf_err is weird %ld\n", 1321 td->td_comm, lp->lwp_proc->p_pid, frame->tf_err); 1322 frame->tf_rip -= frame->tf_err; 1323 frame->tf_r10 = frame->tf_rcx; 1324 } else if (error == EJUSTRETURN) { 1325 /* do nothing */ 1326 } else if (error == EASYNC) { 1327 panic("Unexpected EASYNC return value (for now)"); 1328 } else { 1329 bad: 1330 if (p->p_sysent->sv_errsize) { 1331 if (error >= p->p_sysent->sv_errsize) 1332 error = -1; /* XXX */ 1333 else 1334 error = p->p_sysent->sv_errtbl[error]; 1335 } 1336 frame->tf_rax = error; 1337 frame->tf_rflags |= PSL_C; 1338 } 1339 1340 /* 1341 * Traced syscall. trapsignal() should now be MP aware 1342 */ 1343 if (__predict_false(orig_tf_rflags & PSL_T)) { 1344 frame->tf_rflags &= ~PSL_T; 1345 trapsignal(lp, SIGTRAP, TRAP_TRACE); 1346 } 1347 1348 /* 1349 * Handle reschedule and other end-of-syscall issues 1350 */ 1351 userret(lp, frame, sticks); 1352 1353 #ifdef KTRACE 1354 if (KTRPOINTP(p, td, KTR_SYSRET)) { 1355 ktrsysret(lp, code, error, sysmsg.sysmsg_result); 1356 } 1357 #endif 1358 1359 /* 1360 * This works because errno is findable through the 1361 * register set. If we ever support an emulation where this 1362 * is not the case, this code will need to be revisited. 1363 */ 1364 STOPEVENT(p, S_SCX, code); 1365 1366 userexit(lp); 1367 KTR_LOG(kernentry_syscall_ret, p->p_pid, lp->lwp_tid, error); 1368 #ifdef INVARIANTS 1369 KASSERT(crit_count == td->td_critcount, 1370 ("syscall: critical section count mismatch! " 1371 "%d/%d in %s sysno=%d", 1372 crit_count, td->td_pri, td->td_comm, code)); 1373 KASSERT(&td->td_toks_base == td->td_toks_stop, 1374 ("syscall: %ld extra tokens held after trap! syscall %p", 1375 td->td_toks_stop - &td->td_toks_base, 1376 callp->sy_call)); 1377 #endif 1378 } 1379 1380 /* 1381 * Handles the syscall() and __syscall() API 1382 */ 1383 void xsyscall(struct sysmsg *sysmsg, struct nosys_args *uap); 1384 1385 int 1386 sys_xsyscall(struct sysmsg *sysmsg, const struct nosys_args *uap) 1387 { 1388 struct trapframe *frame; 1389 struct sysent *callp; 1390 union sysunion *argp; 1391 struct thread *td; 1392 struct proc *p; 1393 const int regcnt = 5; /* number of args passed in registers */ 1394 u_int code; 1395 int error; 1396 int narg; 1397 1398 td = curthread; 1399 p = td->td_proc; 1400 frame = sysmsg->sysmsg_frame; 1401 code = (u_int)frame->tf_rdi; 1402 if (code >= p->p_sysent->sv_size) 1403 code = SYS___nosys; 1404 argp = (union sysunion *)(&frame->tf_rdi + 1); 1405 callp = &p->p_sysent->sv_table[code]; 1406 narg = callp->sy_narg; 1407 1408 /* 1409 * On x86_64 we get up to six arguments in registers. The rest are 1410 * on the stack. However, for syscall() and __syscall() the syscall 1411 * number is inserted as the first argument, so the limit is reduced 1412 * by one to five. 1413 */ 1414 if (__predict_false(narg > regcnt)) { 1415 register_t *argsdst; 1416 caddr_t params; 1417 1418 argsdst = (register_t *)&sysmsg->extargs; 1419 bcopy(argp, argsdst, sizeof(register_t) * regcnt); 1420 params = (caddr_t)frame->tf_rsp + sizeof(register_t); 1421 error = copyin(params, &argsdst[regcnt], 1422 (narg - regcnt) * sizeof(register_t)); 1423 argp = (void *)argsdst; 1424 if (error) { 1425 #ifdef KTRACE 1426 if (KTRPOINTP(p, td, KTR_SYSCALL)) { 1427 ktrsyscall(td->td_lwp, code, narg, argp); 1428 } 1429 if (KTRPOINTP(p, td, KTR_SYSRET)) { 1430 ktrsysret(td->td_lwp, code, error, 1431 sysmsg->sysmsg_result); 1432 } 1433 #endif 1434 return error; 1435 } 1436 } 1437 1438 #ifdef KTRACE 1439 if (KTRPOINTP(p, td, KTR_SYSCALL)) { 1440 ktrsyscall(td->td_lwp, code, narg, argp); 1441 } 1442 #endif 1443 1444 error = (*callp->sy_call)(sysmsg, argp); 1445 1446 #ifdef KTRACE 1447 if (KTRPOINTP(p, td, KTR_SYSRET)) { 1448 register_t rval; 1449 1450 rval = (callp->sy_rsize <= 4) ? sysmsg->sysmsg_result : 1451 sysmsg->sysmsg_lresult; 1452 ktrsysret(td->td_lwp, code, error, rval); 1453 } 1454 #endif 1455 1456 return error; 1457 } 1458 1459 void 1460 fork_return(struct lwp *lp, struct trapframe *frame) 1461 { 1462 frame->tf_rax = 0; /* Child returns zero */ 1463 frame->tf_rflags &= ~PSL_C; /* success */ 1464 frame->tf_rdx = 1; 1465 1466 generic_lwp_return(lp, frame); 1467 KTR_LOG(kernentry_fork_ret, lp->lwp_proc->p_pid, lp->lwp_tid); 1468 } 1469 1470 /* 1471 * Simplified back end of syscall(), used when returning from fork() 1472 * directly into user mode. 1473 * 1474 * This code will return back into the fork trampoline code which then 1475 * runs doreti. 1476 */ 1477 void 1478 generic_lwp_return(struct lwp *lp, struct trapframe *frame) 1479 { 1480 struct proc *p = lp->lwp_proc; 1481 1482 /* 1483 * Check for exit-race. If one lwp exits the process concurrent with 1484 * another lwp creating a new thread, the two operations may cross 1485 * each other resulting in the newly-created lwp not receiving a 1486 * KILL signal. 1487 */ 1488 if (p->p_flags & P_WEXIT) { 1489 lwpsignal(p, lp, SIGKILL); 1490 } 1491 1492 /* 1493 * Newly forked processes are given a kernel priority. We have to 1494 * adjust the priority to a normal user priority and fake entry 1495 * into the kernel (call userenter()) to install a passive release 1496 * function just in case userret() decides to stop the process. This 1497 * can occur when ^Z races a fork. If we do not install the passive 1498 * release function the current process designation will not be 1499 * released when the thread goes to sleep. 1500 */ 1501 lwkt_setpri_self(TDPRI_USER_NORM); 1502 userenter(lp->lwp_thread, p); 1503 userret(lp, frame, 0); 1504 #ifdef KTRACE 1505 if (KTRPOINTP(p, lp->lwp_thread, KTR_SYSRET)) 1506 ktrsysret(lp, SYS_fork, 0, 0); 1507 #endif 1508 lp->lwp_flags |= LWP_PASSIVE_ACQ; 1509 userexit(lp); 1510 lp->lwp_flags &= ~LWP_PASSIVE_ACQ; 1511 } 1512 1513 /* 1514 * If PGEX_FPFAULT is set then set FP_VIRTFP in the PCB to force a T_DNA 1515 * fault (which is then passed back to the virtual kernel) if an attempt is 1516 * made to use the FP unit. 1517 * 1518 * XXX this is a fairly big hack. 1519 */ 1520 void 1521 set_vkernel_fp(struct trapframe *frame) 1522 { 1523 struct thread *td = curthread; 1524 1525 if (frame->tf_xflags & PGEX_FPFAULT) { 1526 td->td_pcb->pcb_flags |= FP_VIRTFP; 1527 if (mdcpu->gd_npxthread == td) 1528 npxexit(); 1529 } else { 1530 td->td_pcb->pcb_flags &= ~FP_VIRTFP; 1531 } 1532 } 1533 1534 /* 1535 * Called from vkernel_trap() to fixup the vkernel's syscall 1536 * frame for vmspace_ctl() return. 1537 */ 1538 void 1539 cpu_vkernel_trap(struct trapframe *frame, int error) 1540 { 1541 frame->tf_rax = error; 1542 if (error) 1543 frame->tf_rflags |= PSL_C; 1544 else 1545 frame->tf_rflags &= ~PSL_C; 1546 } 1547