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 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 #include <sys/sysproto.h> 70 #include <sys/sysunion.h> 71 72 #include <vm/pmap.h> 73 #include <vm/vm.h> 74 #include <vm/vm_extern.h> 75 #include <vm/vm_kern.h> 76 #include <vm/vm_param.h> 77 #include <machine/cpu.h> 78 #include <machine/pcb.h> 79 #include <machine/smp.h> 80 #include <machine/thread.h> 81 #include <machine/clock.h> 82 #include <machine/vmparam.h> 83 #include <machine/md_var.h> 84 #include <machine_base/isa/isa_intr.h> 85 #include <machine_base/apic/lapic.h> 86 87 #include <ddb/ddb.h> 88 89 #include <sys/thread2.h> 90 #include <sys/spinlock2.h> 91 92 extern void trap(struct trapframe *frame); 93 94 static int trap_pfault(struct trapframe *, int); 95 static void trap_fatal(struct trapframe *, vm_offset_t); 96 void dblfault_handler(struct trapframe *frame); 97 98 #define MAX_TRAP_MSG 30 99 static char *trap_msg[] = { 100 "", /* 0 unused */ 101 "privileged instruction fault", /* 1 T_PRIVINFLT */ 102 "", /* 2 unused */ 103 "breakpoint instruction fault", /* 3 T_BPTFLT */ 104 "", /* 4 unused */ 105 "", /* 5 unused */ 106 "arithmetic trap", /* 6 T_ARITHTRAP */ 107 "system forced exception", /* 7 T_ASTFLT */ 108 "", /* 8 unused */ 109 "general protection fault", /* 9 T_PROTFLT */ 110 "trace trap", /* 10 T_TRCTRAP */ 111 "", /* 11 unused */ 112 "page fault", /* 12 T_PAGEFLT */ 113 "", /* 13 unused */ 114 "alignment fault", /* 14 T_ALIGNFLT */ 115 "", /* 15 unused */ 116 "", /* 16 unused */ 117 "", /* 17 unused */ 118 "integer divide fault", /* 18 T_DIVIDE */ 119 "non-maskable interrupt trap", /* 19 T_NMI */ 120 "overflow trap", /* 20 T_OFLOW */ 121 "FPU bounds check fault", /* 21 T_BOUND */ 122 "FPU device not available", /* 22 T_DNA */ 123 "double fault", /* 23 T_DOUBLEFLT */ 124 "FPU operand fetch fault", /* 24 T_FPOPFLT */ 125 "invalid TSS fault", /* 25 T_TSSFLT */ 126 "segment not present fault", /* 26 T_SEGNPFLT */ 127 "stack fault", /* 27 T_STKFLT */ 128 "machine check trap", /* 28 T_MCHK */ 129 "SIMD floating-point exception", /* 29 T_XMMFLT */ 130 "reserved (unknown) fault", /* 30 T_RESERVED */ 131 }; 132 133 #ifdef DDB 134 static int ddb_on_nmi = 1; 135 SYSCTL_INT(_machdep, OID_AUTO, ddb_on_nmi, CTLFLAG_RW, 136 &ddb_on_nmi, 0, "Go to DDB on NMI"); 137 static int ddb_on_seg_fault = 0; 138 SYSCTL_INT(_machdep, OID_AUTO, ddb_on_seg_fault, CTLFLAG_RW, 139 &ddb_on_seg_fault, 0, "Go to DDB on user seg-fault"); 140 static int freeze_on_seg_fault = 0; 141 SYSCTL_INT(_machdep, OID_AUTO, freeze_on_seg_fault, CTLFLAG_RW, 142 &freeze_on_seg_fault, 0, "Go to DDB on user seg-fault"); 143 #endif 144 static int panic_on_nmi = 1; 145 SYSCTL_INT(_machdep, OID_AUTO, panic_on_nmi, CTLFLAG_RW, 146 &panic_on_nmi, 0, "Panic on NMI"); 147 static int fast_release; 148 SYSCTL_INT(_machdep, OID_AUTO, fast_release, CTLFLAG_RW, 149 &fast_release, 0, "Passive Release was optimal"); 150 static int slow_release; 151 SYSCTL_INT(_machdep, OID_AUTO, slow_release, CTLFLAG_RW, 152 &slow_release, 0, "Passive Release was nonoptimal"); 153 154 /* 155 * System call debugging records the worst-case system call 156 * overhead (inclusive of blocking), but may be inaccurate. 157 */ 158 /*#define SYSCALL_DEBUG*/ 159 #ifdef SYSCALL_DEBUG 160 uint64_t SysCallsWorstCase[SYS_MAXSYSCALL]; 161 #endif 162 163 /* 164 * Passively intercepts the thread switch function to increase 165 * the thread priority from a user priority to a kernel priority, reducing 166 * syscall and trap overhead for the case where no switch occurs. 167 * 168 * Synchronizes td_ucred with p_ucred. This is used by system calls, 169 * signal handling, faults, AST traps, and anything else that enters the 170 * kernel from userland and provides the kernel with a stable read-only 171 * copy of the process ucred. 172 * 173 * To avoid races with another thread updating p_ucred we obtain p_spin. 174 * The other thread doing the update will obtain both p_token and p_spin. 175 * In the case where the cached cred pointer matches, we will already have 176 * the ref and we don't have to do one blessed thing. 177 */ 178 static __inline void 179 userenter(struct thread *curtd, struct proc *curp) 180 { 181 struct ucred *ocred; 182 struct ucred *ncred; 183 184 curtd->td_release = lwkt_passive_release; 185 186 if (curtd->td_ucred != curp->p_ucred) { 187 spin_lock(&curp->p_spin); 188 ncred = crhold(curp->p_ucred); 189 spin_unlock(&curp->p_spin); 190 ocred = curtd->td_ucred; 191 curtd->td_ucred = ncred; 192 if (ocred) 193 crfree(ocred); 194 } 195 196 #ifdef DDB 197 /* 198 * Debugging, remove top two user stack pages to catch kernel faults 199 */ 200 if (freeze_on_seg_fault > 1 && curtd->td_lwp) { 201 pmap_remove(vmspace_pmap(curtd->td_lwp->lwp_vmspace), 202 0x00007FFFFFFFD000LU, 203 0x0000800000000000LU); 204 } 205 #endif 206 } 207 208 /* 209 * Handle signals, upcalls, profiling, and other AST's and/or tasks that 210 * must be completed before we can return to or try to return to userland. 211 * 212 * Note that td_sticks is a 64 bit quantity, but there's no point doing 64 213 * arithmatic on the delta calculation so the absolute tick values are 214 * truncated to an integer. 215 */ 216 static void 217 userret(struct lwp *lp, struct trapframe *frame, int sticks) 218 { 219 struct proc *p = lp->lwp_proc; 220 int sig; 221 int ptok; 222 223 /* 224 * Charge system time if profiling. Note: times are in microseconds. 225 * This may do a copyout and block, so do it first even though it 226 * means some system time will be charged as user time. 227 */ 228 if (p->p_flags & P_PROFIL) { 229 addupc_task(p, frame->tf_rip, 230 (u_int)((int)lp->lwp_thread->td_sticks - sticks)); 231 } 232 233 recheck: 234 /* 235 * Specific on-return-to-usermode checks (LWP_MP_WEXIT, 236 * LWP_MP_VNLRU, etc). 237 */ 238 if (lp->lwp_mpflags & LWP_MP_URETMASK) 239 lwpuserret(lp); 240 241 /* 242 * Block here if we are in a stopped state. 243 */ 244 if (STOPLWP(p, lp)) { 245 lwkt_gettoken(&p->p_token); 246 tstop(); 247 lwkt_reltoken(&p->p_token); 248 goto recheck; 249 } 250 while (dump_stop_usertds) { 251 tsleep(&dump_stop_usertds, 0, "dumpstp", 0); 252 } 253 254 /* 255 * Post any pending upcalls. If running a virtual kernel be sure 256 * to restore the virtual kernel's vmspace before posting the upcall. 257 */ 258 if (p->p_flags & (P_SIGVTALRM | P_SIGPROF)) { 259 lwkt_gettoken(&p->p_token); 260 if (p->p_flags & P_SIGVTALRM) { 261 p->p_flags &= ~P_SIGVTALRM; 262 ksignal(p, SIGVTALRM); 263 } 264 if (p->p_flags & P_SIGPROF) { 265 p->p_flags &= ~P_SIGPROF; 266 ksignal(p, SIGPROF); 267 } 268 lwkt_reltoken(&p->p_token); 269 goto recheck; 270 } 271 272 /* 273 * Post any pending signals. If running a virtual kernel be sure 274 * to restore the virtual kernel's vmspace before posting the signal. 275 * 276 * WARNING! postsig() can exit and not return. 277 */ 278 if ((sig = CURSIG_LCK_TRACE(lp, &ptok)) != 0) { 279 postsig(sig, ptok); 280 goto recheck; 281 } 282 283 /* 284 * block here if we are swapped out, but still process signals 285 * (such as SIGKILL). proc0 (the swapin scheduler) is already 286 * aware of our situation, we do not have to wake it up. 287 */ 288 if (p->p_flags & P_SWAPPEDOUT) { 289 lwkt_gettoken(&p->p_token); 290 p->p_flags |= P_SWAPWAIT; 291 swapin_request(); 292 if (p->p_flags & P_SWAPWAIT) 293 tsleep(p, PCATCH, "SWOUT", 0); 294 p->p_flags &= ~P_SWAPWAIT; 295 lwkt_reltoken(&p->p_token); 296 goto recheck; 297 } 298 299 /* 300 * In a multi-threaded program it is possible for a thread to change 301 * signal state during a system call which temporarily changes the 302 * signal mask. In this case postsig() might not be run and we 303 * have to restore the mask ourselves. 304 */ 305 if (lp->lwp_flags & LWP_OLDMASK) { 306 lp->lwp_flags &= ~LWP_OLDMASK; 307 lp->lwp_sigmask = lp->lwp_oldsigmask; 308 goto recheck; 309 } 310 } 311 312 /* 313 * Cleanup from userenter and any passive release that might have occured. 314 * We must reclaim the current-process designation before we can return 315 * to usermode. We also handle both LWKT and USER reschedule requests. 316 */ 317 static __inline void 318 userexit(struct lwp *lp) 319 { 320 struct thread *td = lp->lwp_thread; 321 /* globaldata_t gd = td->td_gd; */ 322 323 /* 324 * Handle stop requests at kernel priority. Any requests queued 325 * after this loop will generate another AST. 326 */ 327 while (STOPLWP(lp->lwp_proc, lp)) { 328 lwkt_gettoken(&lp->lwp_proc->p_token); 329 tstop(); 330 lwkt_reltoken(&lp->lwp_proc->p_token); 331 } 332 333 /* 334 * Reduce our priority in preparation for a return to userland. If 335 * our passive release function was still in place, our priority was 336 * never raised and does not need to be reduced. 337 */ 338 lwkt_passive_recover(td); 339 340 /* WARNING: we may have migrated cpu's */ 341 /* gd = td->td_gd; */ 342 343 /* 344 * Become the current user scheduled process if we aren't already, 345 * and deal with reschedule requests and other factors. 346 */ 347 lp->lwp_proc->p_usched->acquire_curproc(lp); 348 } 349 350 #if !defined(KTR_KERNENTRY) 351 #define KTR_KERNENTRY KTR_ALL 352 #endif 353 KTR_INFO_MASTER(kernentry); 354 KTR_INFO(KTR_KERNENTRY, kernentry, trap, 0, 355 "TRAP(pid %d, tid %d, trapno %ld, eva %lu)", 356 pid_t pid, lwpid_t tid, register_t trapno, vm_offset_t eva); 357 KTR_INFO(KTR_KERNENTRY, kernentry, trap_ret, 0, "TRAP_RET(pid %d, tid %d)", 358 pid_t pid, lwpid_t tid); 359 KTR_INFO(KTR_KERNENTRY, kernentry, syscall, 0, "SYSC(pid %d, tid %d, nr %ld)", 360 pid_t pid, lwpid_t tid, register_t trapno); 361 KTR_INFO(KTR_KERNENTRY, kernentry, syscall_ret, 0, "SYSRET(pid %d, tid %d, err %d)", 362 pid_t pid, lwpid_t tid, int err); 363 KTR_INFO(KTR_KERNENTRY, kernentry, fork_ret, 0, "FORKRET(pid %d, tid %d)", 364 pid_t pid, lwpid_t tid); 365 366 /* 367 * Exception, fault, and trap interface to the kernel. 368 * This common code is called from assembly language IDT gate entry 369 * routines that prepare a suitable stack frame, and restore this 370 * frame after the exception has been processed. 371 * 372 * This function is also called from doreti in an interlock to handle ASTs. 373 * For example: hardwareint->INTROUTINE->(set ast)->doreti->trap 374 * 375 * NOTE! We have to retrieve the fault address prior to potentially 376 * blocking, including blocking on any token. 377 * 378 * XXX gd_trap_nesting_level currently prevents lwkt_switch() from panicing 379 * if an attempt is made to switch from a fast interrupt or IPI. 380 */ 381 void 382 trap(struct trapframe *frame) 383 { 384 struct globaldata *gd = mycpu; 385 struct thread *td = gd->gd_curthread; 386 struct lwp *lp = td->td_lwp; 387 struct proc *p; 388 int sticks = 0; 389 int i = 0, ucode = 0, type, code; 390 #ifdef INVARIANTS 391 int crit_count = td->td_critcount; 392 lwkt_tokref_t curstop = td->td_toks_stop; 393 #endif 394 vm_offset_t eva; 395 396 p = td->td_proc; 397 clear_quickret(); 398 399 #ifdef DDB 400 /* 401 * We need to allow T_DNA faults when the debugger is active since 402 * some dumping paths do large bcopy() which use the floating 403 * point registers for faster copying. 404 */ 405 if (db_active && frame->tf_trapno != T_DNA) { 406 eva = (frame->tf_trapno == T_PAGEFLT ? frame->tf_addr : 0); 407 ++gd->gd_trap_nesting_level; 408 trap_fatal(frame, eva); 409 --gd->gd_trap_nesting_level; 410 goto out2; 411 } 412 #endif 413 414 eva = 0; 415 416 if ((frame->tf_rflags & PSL_I) == 0) { 417 /* 418 * Buggy application or kernel code has disabled interrupts 419 * and then trapped. Enabling interrupts now is wrong, but 420 * it is better than running with interrupts disabled until 421 * they are accidentally enabled later. 422 */ 423 type = frame->tf_trapno; 424 if (ISPL(frame->tf_cs) == SEL_UPL) { 425 /* JG curproc can be NULL */ 426 kprintf( 427 "pid %ld (%s): trap %d with interrupts disabled\n", 428 (long)curproc->p_pid, curproc->p_comm, type); 429 } else if (type != T_NMI && type != T_BPTFLT && 430 type != T_TRCTRAP) { 431 /* 432 * XXX not quite right, since this may be for a 433 * multiple fault in user mode. 434 */ 435 kprintf("kernel trap %d (%s @ 0x%016jx) with " 436 "interrupts disabled\n", 437 type, 438 td->td_comm, 439 frame->tf_rip); 440 } 441 cpu_enable_intr(); 442 } 443 444 type = frame->tf_trapno; 445 code = frame->tf_err; 446 447 if (ISPL(frame->tf_cs) == SEL_UPL) { 448 /* user trap */ 449 450 KTR_LOG(kernentry_trap, p->p_pid, lp->lwp_tid, 451 frame->tf_trapno, eva); 452 453 userenter(td, p); 454 455 sticks = (int)td->td_sticks; 456 KASSERT(lp->lwp_md.md_regs == frame, 457 ("Frame mismatch %p %p", lp->lwp_md.md_regs, frame)); 458 459 switch (type) { 460 case T_PRIVINFLT: /* privileged instruction fault */ 461 i = SIGILL; 462 ucode = ILL_PRVOPC; 463 break; 464 465 case T_BPTFLT: /* bpt instruction fault */ 466 case T_TRCTRAP: /* trace trap */ 467 frame->tf_rflags &= ~PSL_T; 468 i = SIGTRAP; 469 ucode = (type == T_TRCTRAP ? TRAP_TRACE : TRAP_BRKPT); 470 break; 471 472 case T_ARITHTRAP: /* arithmetic trap */ 473 ucode = code; 474 i = SIGFPE; 475 break; 476 477 case T_ASTFLT: /* Allow process switch */ 478 mycpu->gd_cnt.v_soft++; 479 if (mycpu->gd_reqflags & RQF_AST_OWEUPC) { 480 atomic_clear_int(&mycpu->gd_reqflags, 481 RQF_AST_OWEUPC); 482 addupc_task(p, p->p_prof.pr_addr, 483 p->p_prof.pr_ticks); 484 } 485 goto out; 486 487 case T_PROTFLT: /* general protection fault */ 488 i = SIGBUS; 489 ucode = BUS_OBJERR; 490 break; 491 case T_STKFLT: /* stack fault */ 492 case T_SEGNPFLT: /* segment not present fault */ 493 i = SIGBUS; 494 ucode = BUS_ADRERR; 495 break; 496 case T_TSSFLT: /* invalid TSS fault */ 497 case T_DOUBLEFLT: /* double fault */ 498 default: 499 i = SIGBUS; 500 ucode = BUS_OBJERR; 501 break; 502 503 case T_PAGEFLT: /* page fault */ 504 i = trap_pfault(frame, TRUE); 505 #ifdef DDB 506 if (frame->tf_rip == 0) { 507 /* used for kernel debugging only */ 508 while (freeze_on_seg_fault) 509 tsleep(p, 0, "freeze", hz * 20); 510 } 511 #endif 512 if (i == -1 || i == 0) 513 goto out; 514 if (i == SIGSEGV) { 515 ucode = SEGV_MAPERR; 516 } else { 517 i = SIGSEGV; 518 ucode = SEGV_ACCERR; 519 } 520 break; 521 522 case T_DIVIDE: /* integer divide fault */ 523 ucode = FPE_INTDIV; 524 i = SIGFPE; 525 break; 526 527 #if NISA > 0 528 case T_NMI: 529 /* machine/parity/power fail/"kitchen sink" faults */ 530 if (isa_nmi(code) == 0) { 531 #ifdef DDB 532 /* 533 * NMI can be hooked up to a pushbutton 534 * for debugging. 535 */ 536 if (ddb_on_nmi) { 537 kprintf ("NMI ... going to debugger\n"); 538 kdb_trap(type, 0, frame); 539 } 540 #endif /* DDB */ 541 goto out2; 542 } else if (panic_on_nmi) 543 panic("NMI indicates hardware failure"); 544 break; 545 #endif /* NISA > 0 */ 546 547 case T_OFLOW: /* integer overflow fault */ 548 ucode = FPE_INTOVF; 549 i = SIGFPE; 550 break; 551 552 case T_BOUND: /* bounds check fault */ 553 ucode = FPE_FLTSUB; 554 i = SIGFPE; 555 break; 556 557 case T_DNA: 558 /* 559 * Virtual kernel intercept - pass the DNA exception 560 * to the virtual kernel if it asked to handle it. 561 * This occurs when the virtual kernel is holding 562 * onto the FP context for a different emulated 563 * process then the one currently running. 564 * 565 * We must still call npxdna() since we may have 566 * saved FP state that the virtual kernel needs 567 * to hand over to a different emulated process. 568 */ 569 if (lp->lwp_vkernel && lp->lwp_vkernel->ve && 570 (td->td_pcb->pcb_flags & FP_VIRTFP) 571 ) { 572 npxdna(); 573 break; 574 } 575 576 /* 577 * The kernel may have switched out the FP unit's 578 * state, causing the user process to take a fault 579 * when it tries to use the FP unit. Restore the 580 * state here 581 */ 582 if (npxdna()) 583 goto out; 584 i = SIGFPE; 585 ucode = FPE_FPU_NP_TRAP; 586 break; 587 588 case T_FPOPFLT: /* FPU operand fetch fault */ 589 ucode = ILL_COPROC; 590 i = SIGILL; 591 break; 592 593 case T_XMMFLT: /* SIMD floating-point exception */ 594 ucode = 0; /* XXX */ 595 i = SIGFPE; 596 break; 597 } 598 } else { 599 /* kernel trap */ 600 601 switch (type) { 602 case T_PAGEFLT: /* page fault */ 603 trap_pfault(frame, FALSE); 604 goto out2; 605 606 case T_DNA: 607 /* 608 * The kernel is apparently using fpu for copying. 609 * XXX this should be fatal unless the kernel has 610 * registered such use. 611 */ 612 if (npxdna()) 613 goto out2; 614 break; 615 616 case T_STKFLT: /* stack fault */ 617 case T_PROTFLT: /* general protection fault */ 618 case T_SEGNPFLT: /* segment not present fault */ 619 /* 620 * Invalid segment selectors and out of bounds 621 * %rip's and %rsp's can be set up in user mode. 622 * This causes a fault in kernel mode when the 623 * kernel tries to return to user mode. We want 624 * to get this fault so that we can fix the 625 * problem here and not have to check all the 626 * selectors and pointers when the user changes 627 * them. 628 */ 629 if (mycpu->gd_intr_nesting_level == 0) { 630 /* 631 * NOTE: in 64-bit mode traps push rsp/ss 632 * even if no ring change occurs. 633 */ 634 if (td->td_pcb->pcb_onfault && 635 td->td_pcb->pcb_onfault_sp == 636 frame->tf_rsp) { 637 frame->tf_rip = (register_t) 638 td->td_pcb->pcb_onfault; 639 goto out2; 640 } 641 if (frame->tf_rip == (long)doreti_iret) { 642 frame->tf_rip = (long)doreti_iret_fault; 643 goto out2; 644 } 645 } 646 break; 647 648 case T_TSSFLT: 649 /* 650 * PSL_NT can be set in user mode and isn't cleared 651 * automatically when the kernel is entered. This 652 * causes a TSS fault when the kernel attempts to 653 * `iret' because the TSS link is uninitialized. We 654 * want to get this fault so that we can fix the 655 * problem here and not every time the kernel is 656 * entered. 657 */ 658 if (frame->tf_rflags & PSL_NT) { 659 frame->tf_rflags &= ~PSL_NT; 660 goto out2; 661 } 662 break; 663 664 case T_TRCTRAP: /* trace trap */ 665 #if 0 666 if (frame->tf_rip == (int)IDTVEC(syscall)) { 667 /* 668 * We've just entered system mode via the 669 * syscall lcall. Continue single stepping 670 * silently until the syscall handler has 671 * saved the flags. 672 */ 673 goto out2; 674 } 675 if (frame->tf_rip == (int)IDTVEC(syscall) + 1) { 676 /* 677 * The syscall handler has now saved the 678 * flags. Stop single stepping it. 679 */ 680 frame->tf_rflags &= ~PSL_T; 681 goto out2; 682 } 683 #endif 684 685 /* 686 * Ignore debug register trace traps due to 687 * accesses in the user's address space, which 688 * can happen under several conditions such as 689 * if a user sets a watchpoint on a buffer and 690 * then passes that buffer to a system call. 691 * We still want to get TRCTRAPS for addresses 692 * in kernel space because that is useful when 693 * debugging the kernel. 694 */ 695 #if 0 /* JG */ 696 if (user_dbreg_trap()) { 697 /* 698 * Reset breakpoint bits because the 699 * processor doesn't 700 */ 701 /* XXX check upper bits here */ 702 load_dr6(rdr6() & 0xfffffff0); 703 goto out2; 704 } 705 #endif 706 /* 707 * FALLTHROUGH (TRCTRAP kernel mode, kernel address) 708 */ 709 case T_BPTFLT: 710 /* 711 * If DDB is enabled, let it handle the debugger trap. 712 * Otherwise, debugger traps "can't happen". 713 */ 714 ucode = TRAP_BRKPT; 715 #ifdef DDB 716 if (kdb_trap(type, 0, frame)) 717 goto out2; 718 #endif 719 break; 720 721 #if NISA > 0 722 case T_NMI: 723 /* machine/parity/power fail/"kitchen sink" faults */ 724 if (isa_nmi(code) == 0) { 725 #ifdef DDB 726 /* 727 * NMI can be hooked up to a pushbutton 728 * for debugging. 729 */ 730 if (ddb_on_nmi) { 731 kprintf ("NMI ... going to debugger\n"); 732 kdb_trap(type, 0, frame); 733 } 734 #endif /* DDB */ 735 goto out2; 736 } else if (panic_on_nmi == 0) 737 goto out2; 738 /* FALL THROUGH */ 739 #endif /* NISA > 0 */ 740 } 741 trap_fatal(frame, 0); 742 goto out2; 743 } 744 745 /* 746 * Fault from user mode, virtual kernel interecept. 747 * 748 * If the fault is directly related to a VM context managed by a 749 * virtual kernel then let the virtual kernel handle it. 750 */ 751 if (lp->lwp_vkernel && lp->lwp_vkernel->ve) { 752 vkernel_trap(lp, frame); 753 goto out; 754 } 755 756 /* Translate fault for emulators (e.g. Linux) */ 757 if (*p->p_sysent->sv_transtrap) 758 i = (*p->p_sysent->sv_transtrap)(i, type); 759 760 trapsignal(lp, i, ucode); 761 762 #ifdef DEBUG 763 if (type <= MAX_TRAP_MSG) { 764 uprintf("fatal process exception: %s", 765 trap_msg[type]); 766 if ((type == T_PAGEFLT) || (type == T_PROTFLT)) 767 uprintf(", fault VA = 0x%lx", frame->tf_addr); 768 uprintf("\n"); 769 } 770 #endif 771 772 out: 773 userret(lp, frame, sticks); 774 userexit(lp); 775 out2: ; 776 if (p != NULL && lp != NULL) 777 KTR_LOG(kernentry_trap_ret, p->p_pid, lp->lwp_tid); 778 #ifdef INVARIANTS 779 KASSERT(crit_count == td->td_critcount, 780 ("trap: critical section count mismatch! %d/%d", 781 crit_count, td->td_pri)); 782 KASSERT(curstop == td->td_toks_stop, 783 ("trap: extra tokens held after trap! %ld/%ld", 784 curstop - &td->td_toks_base, 785 td->td_toks_stop - &td->td_toks_base)); 786 #endif 787 } 788 789 void 790 trap_handle_userenter(struct thread *td) 791 { 792 userenter(td, td->td_proc); 793 } 794 795 void 796 trap_handle_userexit(struct trapframe *frame, int sticks) 797 { 798 struct lwp *lp = curthread->td_lwp; 799 800 if (lp) { 801 userret(lp, frame, sticks); 802 userexit(lp); 803 } 804 } 805 806 static int 807 trap_pfault(struct trapframe *frame, int usermode) 808 { 809 vm_offset_t va; 810 struct vmspace *vm = NULL; 811 vm_map_t map; 812 int rv = 0; 813 int fault_flags; 814 vm_prot_t ftype; 815 thread_t td = curthread; 816 struct lwp *lp = td->td_lwp; 817 struct proc *p; 818 819 va = trunc_page(frame->tf_addr); 820 if (va >= VM_MIN_KERNEL_ADDRESS) { 821 /* 822 * Don't allow user-mode faults in kernel address space. 823 */ 824 if (usermode) { 825 fault_flags = -1; 826 ftype = -1; 827 goto nogo; 828 } 829 830 map = &kernel_map; 831 } else { 832 /* 833 * This is a fault on non-kernel virtual memory. 834 * vm is initialized above to NULL. If curproc is NULL 835 * or curproc->p_vmspace is NULL the fault is fatal. 836 */ 837 if (lp != NULL) 838 vm = lp->lwp_vmspace; 839 840 if (vm == NULL) { 841 fault_flags = -1; 842 ftype = -1; 843 goto nogo; 844 } 845 846 /* 847 * Debugging, try to catch kernel faults on the user address 848 * space when not inside on onfault (e.g. copyin/copyout) 849 * routine. 850 */ 851 if (usermode == 0 && (td->td_pcb == NULL || 852 td->td_pcb->pcb_onfault == NULL)) { 853 #ifdef DDB 854 if (freeze_on_seg_fault) { 855 kprintf("trap_pfault: user address fault from kernel mode " 856 "%016lx\n", (long)frame->tf_addr); 857 while (freeze_on_seg_fault) 858 tsleep(&freeze_on_seg_fault, 0, "frzseg", hz * 20); 859 } 860 #endif 861 } 862 map = &vm->vm_map; 863 } 864 865 /* 866 * PGEX_I is defined only if the execute disable bit capability is 867 * supported and enabled. 868 */ 869 if (frame->tf_err & PGEX_W) 870 ftype = VM_PROT_WRITE; 871 #if 0 /* JG */ 872 else if ((frame->tf_err & PGEX_I) && pg_nx != 0) 873 ftype = VM_PROT_EXECUTE; 874 #endif 875 else 876 ftype = VM_PROT_READ; 877 878 if (map != &kernel_map) { 879 /* 880 * Keep swapout from messing with us during this 881 * critical time. 882 */ 883 PHOLD(lp->lwp_proc); 884 885 /* 886 * Issue fault 887 */ 888 fault_flags = 0; 889 if (usermode) 890 fault_flags |= VM_FAULT_BURST | VM_FAULT_USERMODE; 891 if (ftype & VM_PROT_WRITE) 892 fault_flags |= VM_FAULT_DIRTY; 893 else 894 fault_flags |= VM_FAULT_NORMAL; 895 rv = vm_fault(map, va, ftype, fault_flags); 896 897 PRELE(lp->lwp_proc); 898 } else { 899 /* 900 * Don't have to worry about process locking or stacks in the 901 * kernel. 902 */ 903 fault_flags = VM_FAULT_NORMAL; 904 rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL); 905 } 906 if (rv == KERN_SUCCESS) 907 return (0); 908 nogo: 909 if (!usermode) { 910 /* 911 * NOTE: in 64-bit mode traps push rsp/ss 912 * even if no ring change occurs. 913 */ 914 if (td->td_pcb->pcb_onfault && 915 td->td_pcb->pcb_onfault_sp == frame->tf_rsp && 916 td->td_gd->gd_intr_nesting_level == 0) { 917 frame->tf_rip = (register_t)td->td_pcb->pcb_onfault; 918 return (0); 919 } 920 trap_fatal(frame, frame->tf_addr); 921 return (-1); 922 } 923 924 /* 925 * NOTE: on x86_64 we have a tf_addr field in the trapframe, no 926 * kludge is needed to pass the fault address to signal handlers. 927 */ 928 p = td->td_proc; 929 #ifdef DDB 930 if (td->td_lwp->lwp_vkernel == NULL) { 931 while (freeze_on_seg_fault) { 932 tsleep(p, 0, "freeze", hz * 20); 933 } 934 if (ddb_on_seg_fault) 935 Debugger("ddb_on_seg_fault"); 936 } 937 #endif 938 939 return((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV); 940 } 941 942 static void 943 trap_fatal(struct trapframe *frame, vm_offset_t eva) 944 { 945 int code, ss; 946 u_int type; 947 long rsp; 948 struct soft_segment_descriptor softseg; 949 char *msg; 950 951 code = frame->tf_err; 952 type = frame->tf_trapno; 953 sdtossd(&gdt[IDXSEL(frame->tf_cs & 0xffff)], &softseg); 954 955 if (type <= MAX_TRAP_MSG) 956 msg = trap_msg[type]; 957 else 958 msg = "UNKNOWN"; 959 kprintf("\n\nFatal trap %d: %s while in %s mode\n", type, msg, 960 ISPL(frame->tf_cs) == SEL_UPL ? "user" : "kernel"); 961 /* three separate prints in case of a trap on an unmapped page */ 962 kprintf("cpuid = %d; ", mycpu->gd_cpuid); 963 kprintf("lapic->id = %08x\n", lapic->id); 964 if (type == T_PAGEFLT) { 965 kprintf("fault virtual address = 0x%lx\n", eva); 966 kprintf("fault code = %s %s %s, %s\n", 967 code & PGEX_U ? "user" : "supervisor", 968 code & PGEX_W ? "write" : "read", 969 code & PGEX_I ? "instruction" : "data", 970 code & PGEX_P ? "protection violation" : "page not present"); 971 } 972 kprintf("instruction pointer = 0x%lx:0x%lx\n", 973 frame->tf_cs & 0xffff, frame->tf_rip); 974 if (ISPL(frame->tf_cs) == SEL_UPL) { 975 ss = frame->tf_ss & 0xffff; 976 rsp = frame->tf_rsp; 977 } else { 978 /* 979 * NOTE: in 64-bit mode traps push rsp/ss even if no ring 980 * change occurs. 981 */ 982 ss = GSEL(GDATA_SEL, SEL_KPL); 983 rsp = frame->tf_rsp; 984 } 985 kprintf("stack pointer = 0x%x:0x%lx\n", ss, rsp); 986 kprintf("frame pointer = 0x%x:0x%lx\n", ss, frame->tf_rbp); 987 kprintf("code segment = base 0x%lx, limit 0x%lx, type 0x%x\n", 988 softseg.ssd_base, softseg.ssd_limit, softseg.ssd_type); 989 kprintf(" = DPL %d, pres %d, long %d, def32 %d, gran %d\n", 990 softseg.ssd_dpl, softseg.ssd_p, softseg.ssd_long, softseg.ssd_def32, 991 softseg.ssd_gran); 992 kprintf("processor eflags = "); 993 if (frame->tf_rflags & PSL_T) 994 kprintf("trace trap, "); 995 if (frame->tf_rflags & PSL_I) 996 kprintf("interrupt enabled, "); 997 if (frame->tf_rflags & PSL_NT) 998 kprintf("nested task, "); 999 if (frame->tf_rflags & PSL_RF) 1000 kprintf("resume, "); 1001 kprintf("IOPL = %ld\n", (frame->tf_rflags & PSL_IOPL) >> 12); 1002 kprintf("current process = "); 1003 if (curproc) { 1004 kprintf("%lu\n", 1005 (u_long)curproc->p_pid); 1006 } else { 1007 kprintf("Idle\n"); 1008 } 1009 kprintf("current thread = pri %d ", curthread->td_pri); 1010 if (curthread->td_critcount) 1011 kprintf("(CRIT)"); 1012 kprintf("\n"); 1013 1014 #ifdef DDB 1015 if ((debugger_on_panic || db_active) && kdb_trap(type, code, frame)) 1016 return; 1017 #endif 1018 kprintf("trap number = %d\n", type); 1019 if (type <= MAX_TRAP_MSG) 1020 panic("%s", trap_msg[type]); 1021 else 1022 panic("unknown/reserved trap"); 1023 } 1024 1025 /* 1026 * Double fault handler. Called when a fault occurs while writing 1027 * a frame for a trap/exception onto the stack. This usually occurs 1028 * when the stack overflows (such is the case with infinite recursion, 1029 * for example). 1030 */ 1031 static __inline 1032 int 1033 in_kstack_guard(register_t rptr) 1034 { 1035 thread_t td = curthread; 1036 1037 if ((char *)rptr >= td->td_kstack && 1038 (char *)rptr < td->td_kstack + PAGE_SIZE) { 1039 return 1; 1040 } 1041 return 0; 1042 } 1043 1044 void 1045 dblfault_handler(struct trapframe *frame) 1046 { 1047 thread_t td = curthread; 1048 1049 if (in_kstack_guard(frame->tf_rsp) || in_kstack_guard(frame->tf_rbp)) { 1050 kprintf("DOUBLE FAULT - KERNEL STACK GUARD HIT!\n"); 1051 if (in_kstack_guard(frame->tf_rsp)) 1052 frame->tf_rsp = (register_t)(td->td_kstack + PAGE_SIZE); 1053 if (in_kstack_guard(frame->tf_rbp)) 1054 frame->tf_rbp = (register_t)(td->td_kstack + PAGE_SIZE); 1055 } else { 1056 kprintf("DOUBLE FAULT\n"); 1057 } 1058 kprintf("\nFatal double fault\n"); 1059 kprintf("rip = 0x%lx\n", frame->tf_rip); 1060 kprintf("rsp = 0x%lx\n", frame->tf_rsp); 1061 kprintf("rbp = 0x%lx\n", frame->tf_rbp); 1062 /* three separate prints in case of a trap on an unmapped page */ 1063 kprintf("cpuid = %d; ", mycpu->gd_cpuid); 1064 kprintf("lapic->id = %08x\n", lapic->id); 1065 panic("double fault"); 1066 } 1067 1068 /* 1069 * syscall2 - MP aware system call request C handler 1070 * 1071 * A system call is essentially treated as a trap except that the 1072 * MP lock is not held on entry or return. We are responsible for 1073 * obtaining the MP lock if necessary and for handling ASTs 1074 * (e.g. a task switch) prior to return. 1075 * 1076 * MPSAFE 1077 */ 1078 void 1079 syscall2(struct trapframe *frame) 1080 { 1081 struct thread *td = curthread; 1082 struct proc *p = td->td_proc; 1083 struct lwp *lp = td->td_lwp; 1084 caddr_t params; 1085 struct sysent *callp; 1086 register_t orig_tf_rflags; 1087 int sticks; 1088 int error; 1089 int narg; 1090 #ifdef INVARIANTS 1091 int crit_count = td->td_critcount; 1092 #endif 1093 register_t *argp; 1094 u_int code; 1095 int reg, regcnt; 1096 union sysunion args; 1097 register_t *argsdst; 1098 1099 mycpu->gd_cnt.v_syscall++; 1100 1101 #ifdef DIAGNOSTIC 1102 if (ISPL(frame->tf_cs) != SEL_UPL) { 1103 panic("syscall"); 1104 /* NOT REACHED */ 1105 } 1106 #endif 1107 1108 KTR_LOG(kernentry_syscall, p->p_pid, lp->lwp_tid, 1109 frame->tf_rax); 1110 1111 userenter(td, p); /* lazy raise our priority */ 1112 1113 reg = 0; 1114 regcnt = 6; 1115 /* 1116 * Misc 1117 */ 1118 sticks = (int)td->td_sticks; 1119 orig_tf_rflags = frame->tf_rflags; 1120 1121 /* 1122 * Virtual kernel intercept - if a VM context managed by a virtual 1123 * kernel issues a system call the virtual kernel handles it, not us. 1124 * Restore the virtual kernel context and return from its system 1125 * call. The current frame is copied out to the virtual kernel. 1126 */ 1127 if (lp->lwp_vkernel && lp->lwp_vkernel->ve) { 1128 vkernel_trap(lp, frame); 1129 error = EJUSTRETURN; 1130 callp = NULL; 1131 goto out; 1132 } 1133 1134 /* 1135 * Get the system call parameters and account for time 1136 */ 1137 KASSERT(lp->lwp_md.md_regs == frame, 1138 ("Frame mismatch %p %p", lp->lwp_md.md_regs, frame)); 1139 params = (caddr_t)frame->tf_rsp + sizeof(register_t); 1140 code = frame->tf_rax; 1141 1142 if (p->p_sysent->sv_prepsyscall) { 1143 (*p->p_sysent->sv_prepsyscall)( 1144 frame, (int *)(&args.nosys.sysmsg + 1), 1145 &code, ¶ms); 1146 } else { 1147 if (code == SYS_syscall || code == SYS___syscall) { 1148 code = frame->tf_rdi; 1149 reg++; 1150 regcnt--; 1151 } 1152 } 1153 1154 if (p->p_sysent->sv_mask) 1155 code &= p->p_sysent->sv_mask; 1156 1157 if (code >= p->p_sysent->sv_size) 1158 callp = &p->p_sysent->sv_table[0]; 1159 else 1160 callp = &p->p_sysent->sv_table[code]; 1161 1162 narg = callp->sy_narg & SYF_ARGMASK; 1163 1164 /* 1165 * On x86_64 we get up to six arguments in registers. The rest are 1166 * on the stack. The first six members of 'struct trapframe' happen 1167 * to be the registers used to pass arguments, in exactly the right 1168 * order. 1169 */ 1170 argp = &frame->tf_rdi; 1171 argp += reg; 1172 argsdst = (register_t *)(&args.nosys.sysmsg + 1); 1173 /* 1174 * JG can we overflow the space pointed to by 'argsdst' 1175 * either with 'bcopy' or with 'copyin'? 1176 */ 1177 bcopy(argp, argsdst, sizeof(register_t) * regcnt); 1178 /* 1179 * copyin is MP aware, but the tracing code is not 1180 */ 1181 if (narg > regcnt) { 1182 KASSERT(params != NULL, ("copyin args with no params!")); 1183 error = copyin(params, &argsdst[regcnt], 1184 (narg - regcnt) * sizeof(register_t)); 1185 if (error) { 1186 #ifdef KTRACE 1187 if (KTRPOINT(td, KTR_SYSCALL)) { 1188 ktrsyscall(lp, code, narg, 1189 (void *)(&args.nosys.sysmsg + 1)); 1190 } 1191 #endif 1192 goto bad; 1193 } 1194 } 1195 1196 #ifdef KTRACE 1197 if (KTRPOINT(td, KTR_SYSCALL)) { 1198 ktrsyscall(lp, code, narg, (void *)(&args.nosys.sysmsg + 1)); 1199 } 1200 #endif 1201 1202 /* 1203 * Default return value is 0 (will be copied to %rax). Double-value 1204 * returns use %rax and %rdx. %rdx is left unchanged for system 1205 * calls which return only one result. 1206 */ 1207 args.sysmsg_fds[0] = 0; 1208 args.sysmsg_fds[1] = frame->tf_rdx; 1209 1210 /* 1211 * The syscall might manipulate the trap frame. If it does it 1212 * will probably return EJUSTRETURN. 1213 */ 1214 args.sysmsg_frame = frame; 1215 1216 STOPEVENT(p, S_SCE, narg); /* MP aware */ 1217 1218 /* 1219 * NOTE: All system calls run MPSAFE now. The system call itself 1220 * is responsible for getting the MP lock. 1221 */ 1222 #ifdef SYSCALL_DEBUG 1223 uint64_t tscval = rdtsc(); 1224 #endif 1225 error = (*callp->sy_call)(&args); 1226 #ifdef SYSCALL_DEBUG 1227 tscval = rdtsc() - tscval; 1228 tscval = tscval * 1000000 / tsc_frequency; 1229 if (SysCallsWorstCase[code] < tscval) 1230 SysCallsWorstCase[code] = tscval; 1231 #endif 1232 1233 out: 1234 /* 1235 * MP SAFE (we may or may not have the MP lock at this point) 1236 */ 1237 //kprintf("SYSMSG %d ", error); 1238 switch (error) { 1239 case 0: 1240 /* 1241 * Reinitialize proc pointer `p' as it may be different 1242 * if this is a child returning from fork syscall. 1243 */ 1244 p = curproc; 1245 lp = curthread->td_lwp; 1246 frame->tf_rax = args.sysmsg_fds[0]; 1247 frame->tf_rdx = args.sysmsg_fds[1]; 1248 frame->tf_rflags &= ~PSL_C; 1249 break; 1250 case ERESTART: 1251 /* 1252 * Reconstruct pc, we know that 'syscall' is 2 bytes. 1253 * We have to do a full context restore so that %r10 1254 * (which was holding the value of %rcx) is restored for 1255 * the next iteration. 1256 */ 1257 if (frame->tf_err != 0 && frame->tf_err != 2) 1258 kprintf("lp %s:%d frame->tf_err is weird %ld\n", 1259 td->td_comm, lp->lwp_proc->p_pid, frame->tf_err); 1260 frame->tf_rip -= frame->tf_err; 1261 frame->tf_r10 = frame->tf_rcx; 1262 break; 1263 case EJUSTRETURN: 1264 break; 1265 case EASYNC: 1266 panic("Unexpected EASYNC return value (for now)"); 1267 default: 1268 bad: 1269 if (p->p_sysent->sv_errsize) { 1270 if (error >= p->p_sysent->sv_errsize) 1271 error = -1; /* XXX */ 1272 else 1273 error = p->p_sysent->sv_errtbl[error]; 1274 } 1275 frame->tf_rax = error; 1276 frame->tf_rflags |= PSL_C; 1277 break; 1278 } 1279 1280 /* 1281 * Traced syscall. trapsignal() should now be MP aware 1282 */ 1283 if (orig_tf_rflags & PSL_T) { 1284 frame->tf_rflags &= ~PSL_T; 1285 trapsignal(lp, SIGTRAP, TRAP_TRACE); 1286 } 1287 1288 /* 1289 * Handle reschedule and other end-of-syscall issues 1290 */ 1291 userret(lp, frame, sticks); 1292 1293 #ifdef KTRACE 1294 if (KTRPOINT(td, KTR_SYSRET)) { 1295 ktrsysret(lp, code, error, args.sysmsg_result); 1296 } 1297 #endif 1298 1299 /* 1300 * This works because errno is findable through the 1301 * register set. If we ever support an emulation where this 1302 * is not the case, this code will need to be revisited. 1303 */ 1304 STOPEVENT(p, S_SCX, code); 1305 1306 userexit(lp); 1307 KTR_LOG(kernentry_syscall_ret, p->p_pid, lp->lwp_tid, error); 1308 #ifdef INVARIANTS 1309 KASSERT(crit_count == td->td_critcount, 1310 ("syscall: critical section count mismatch! %d/%d", 1311 crit_count, td->td_pri)); 1312 KASSERT(&td->td_toks_base == td->td_toks_stop, 1313 ("syscall: %ld extra tokens held after trap! syscall %p", 1314 td->td_toks_stop - &td->td_toks_base, 1315 callp->sy_call)); 1316 #endif 1317 } 1318 1319 void 1320 fork_return(struct lwp *lp, struct trapframe *frame) 1321 { 1322 frame->tf_rax = 0; /* Child returns zero */ 1323 frame->tf_rflags &= ~PSL_C; /* success */ 1324 frame->tf_rdx = 1; 1325 1326 generic_lwp_return(lp, frame); 1327 KTR_LOG(kernentry_fork_ret, lp->lwp_proc->p_pid, lp->lwp_tid); 1328 } 1329 1330 /* 1331 * Simplified back end of syscall(), used when returning from fork() 1332 * directly into user mode. 1333 * 1334 * This code will return back into the fork trampoline code which then 1335 * runs doreti. 1336 */ 1337 void 1338 generic_lwp_return(struct lwp *lp, struct trapframe *frame) 1339 { 1340 struct proc *p = lp->lwp_proc; 1341 1342 /* 1343 * Check for exit-race. If one lwp exits the process concurrent with 1344 * another lwp creating a new thread, the two operations may cross 1345 * each other resulting in the newly-created lwp not receiving a 1346 * KILL signal. 1347 */ 1348 if (p->p_flags & P_WEXIT) { 1349 lwpsignal(p, lp, SIGKILL); 1350 } 1351 1352 /* 1353 * Newly forked processes are given a kernel priority. We have to 1354 * adjust the priority to a normal user priority and fake entry 1355 * into the kernel (call userenter()) to install a passive release 1356 * function just in case userret() decides to stop the process. This 1357 * can occur when ^Z races a fork. If we do not install the passive 1358 * release function the current process designation will not be 1359 * released when the thread goes to sleep. 1360 */ 1361 lwkt_setpri_self(TDPRI_USER_NORM); 1362 userenter(lp->lwp_thread, p); 1363 userret(lp, frame, 0); 1364 #ifdef KTRACE 1365 if (KTRPOINT(lp->lwp_thread, KTR_SYSRET)) 1366 ktrsysret(lp, SYS_fork, 0, 0); 1367 #endif 1368 lp->lwp_flags |= LWP_PASSIVE_ACQ; 1369 userexit(lp); 1370 lp->lwp_flags &= ~LWP_PASSIVE_ACQ; 1371 } 1372 1373 /* 1374 * If PGEX_FPFAULT is set then set FP_VIRTFP in the PCB to force a T_DNA 1375 * fault (which is then passed back to the virtual kernel) if an attempt is 1376 * made to use the FP unit. 1377 * 1378 * XXX this is a fairly big hack. 1379 */ 1380 void 1381 set_vkernel_fp(struct trapframe *frame) 1382 { 1383 struct thread *td = curthread; 1384 1385 if (frame->tf_xflags & PGEX_FPFAULT) { 1386 td->td_pcb->pcb_flags |= FP_VIRTFP; 1387 if (mdcpu->gd_npxthread == td) 1388 npxexit(); 1389 } else { 1390 td->td_pcb->pcb_flags &= ~FP_VIRTFP; 1391 } 1392 } 1393 1394 /* 1395 * Called from vkernel_trap() to fixup the vkernel's syscall 1396 * frame for vmspace_ctl() return. 1397 */ 1398 void 1399 cpu_vkernel_trap(struct trapframe *frame, int error) 1400 { 1401 frame->tf_rax = error; 1402 if (error) 1403 frame->tf_rflags |= PSL_C; 1404 else 1405 frame->tf_rflags &= ~PSL_C; 1406 } 1407