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 #include <sys/systm.h> 65 #ifdef KTRACE 66 #include <sys/ktrace.h> 67 #endif 68 #include <sys/ktr.h> 69 #include <sys/sysmsg.h> 70 #include <sys/sysproto.h> 71 #include <sys/sysunion.h> 72 73 #include <vm/pmap.h> 74 #include <vm/vm.h> 75 #include <vm/vm_extern.h> 76 #include <vm/vm_kern.h> 77 #include <vm/vm_param.h> 78 #include <machine/cpu.h> 79 #include <machine/pcb.h> 80 #include <machine/smp.h> 81 #include <machine/thread.h> 82 #include <machine/clock.h> 83 #include <machine/vmparam.h> 84 #include <machine/md_var.h> 85 #include <machine_base/isa/isa_intr.h> 86 #include <machine_base/apic/lapic.h> 87 88 #include <ddb/ddb.h> 89 90 #include <sys/thread2.h> 91 #include <sys/mplock2.h> 92 93 #define MAKEMPSAFE(have_mplock) \ 94 if (have_mplock == 0) { \ 95 get_mplock(); \ 96 have_mplock = 1; \ 97 } 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 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 static int fast_release; 155 SYSCTL_INT(_machdep, OID_AUTO, fast_release, CTLFLAG_RW, 156 &fast_release, 0, "Passive Release was optimal"); 157 static int slow_release; 158 SYSCTL_INT(_machdep, OID_AUTO, slow_release, CTLFLAG_RW, 159 &slow_release, 0, "Passive Release was nonoptimal"); 160 161 /* 162 * System call debugging records the worst-case system call 163 * overhead (inclusive of blocking), but may be inaccurate. 164 */ 165 /*#define SYSCALL_DEBUG*/ 166 #ifdef SYSCALL_DEBUG 167 uint64_t SysCallsWorstCase[SYS_MAXSYSCALL]; 168 #endif 169 170 /* 171 * Passively intercepts the thread switch function to increase 172 * the thread priority from a user priority to a kernel priority, reducing 173 * syscall and trap overhead for the case where no switch occurs. 174 * 175 * Synchronizes td_ucred with p_ucred. This is used by system calls, 176 * signal handling, faults, AST traps, and anything else that enters the 177 * kernel from userland and provides the kernel with a stable read-only 178 * copy of the process ucred. 179 */ 180 static __inline void 181 userenter(struct thread *curtd, struct proc *curp) 182 { 183 struct ucred *ocred; 184 struct ucred *ncred; 185 186 curtd->td_release = lwkt_passive_release; 187 188 if (curtd->td_ucred != curp->p_ucred) { 189 ncred = crhold(curp->p_ucred); 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; 221 222 /* 223 * Charge system time if profiling. Note: times are in microseconds. 224 * This may do a copyout and block, so do it first even though it 225 * means some system time will be charged as user time. 226 */ 227 if (p->p_flags & P_PROFIL) { 228 addupc_task(p, frame->tf_rip, 229 (u_int)((int)lp->lwp_thread->td_sticks - sticks)); 230 } 231 232 recheck: 233 /* 234 * If the jungle wants us dead, so be it. 235 */ 236 if (lp->lwp_mpflags & LWP_MP_WEXIT) { 237 lwkt_gettoken(&p->p_token); 238 lwp_exit(0); 239 lwkt_reltoken(&p->p_token); /* NOT REACHED */ 240 } 241 242 /* 243 * Block here if we are in a stopped state. 244 */ 245 if (p->p_stat == SSTOP || dump_stop_usertds) { 246 lwkt_gettoken(&p->p_token); 247 tstop(); 248 lwkt_reltoken(&p->p_token); 249 goto recheck; 250 } 251 252 /* 253 * Post any pending upcalls. If running a virtual kernel be sure 254 * to restore the virtual kernel's vmspace before posting the upcall. 255 */ 256 if (p->p_flags & (P_SIGVTALRM | P_SIGPROF | P_UPCALLPEND)) { 257 lwkt_gettoken(&p->p_token); 258 if (p->p_flags & P_SIGVTALRM) { 259 p->p_flags &= ~P_SIGVTALRM; 260 ksignal(p, SIGVTALRM); 261 } 262 if (p->p_flags & P_SIGPROF) { 263 p->p_flags &= ~P_SIGPROF; 264 ksignal(p, SIGPROF); 265 } 266 if (p->p_flags & P_UPCALLPEND) { 267 p->p_flags &= ~P_UPCALLPEND; 268 postupcall(lp); 269 } 270 lwkt_reltoken(&p->p_token); 271 goto recheck; 272 } 273 274 /* 275 * Post any pending signals. If running a virtual kernel be sure 276 * to restore the virtual kernel's vmspace before posting the signal. 277 * 278 * WARNING! postsig() can exit and not return. 279 */ 280 if ((sig = CURSIG_TRACE(lp)) != 0) { 281 lwkt_gettoken(&p->p_token); 282 postsig(sig); 283 lwkt_reltoken(&p->p_token); 284 goto recheck; 285 } 286 287 /* 288 * block here if we are swapped out, but still process signals 289 * (such as SIGKILL). proc0 (the swapin scheduler) is already 290 * aware of our situation, we do not have to wake it up. 291 */ 292 if (p->p_flags & P_SWAPPEDOUT) { 293 lwkt_gettoken(&p->p_token); 294 get_mplock(); 295 p->p_flags |= P_SWAPWAIT; 296 swapin_request(); 297 if (p->p_flags & P_SWAPWAIT) 298 tsleep(p, PCATCH, "SWOUT", 0); 299 p->p_flags &= ~P_SWAPWAIT; 300 rel_mplock(); 301 lwkt_reltoken(&p->p_token); 302 goto recheck; 303 } 304 305 /* 306 * In a multi-threaded program it is possible for a thread to change 307 * signal state during a system call which temporarily changes the 308 * signal mask. In this case postsig() might not be run and we 309 * have to restore the mask ourselves. 310 */ 311 if (lp->lwp_flags & LWP_OLDMASK) { 312 lp->lwp_flags &= ~LWP_OLDMASK; 313 lp->lwp_sigmask = lp->lwp_oldsigmask; 314 goto recheck; 315 } 316 } 317 318 /* 319 * Cleanup from userenter and any passive release that might have occured. 320 * We must reclaim the current-process designation before we can return 321 * to usermode. We also handle both LWKT and USER reschedule requests. 322 */ 323 static __inline void 324 userexit(struct lwp *lp) 325 { 326 struct thread *td = lp->lwp_thread; 327 /* globaldata_t gd = td->td_gd; */ 328 329 /* 330 * Handle stop requests at kernel priority. Any requests queued 331 * after this loop will generate another AST. 332 */ 333 while (lp->lwp_proc->p_stat == SSTOP) { 334 lwkt_gettoken(&lp->lwp_proc->p_token); 335 tstop(); 336 lwkt_reltoken(&lp->lwp_proc->p_token); 337 } 338 339 /* 340 * Reduce our priority in preparation for a return to userland. If 341 * our passive release function was still in place, our priority was 342 * never raised and does not need to be reduced. 343 */ 344 lwkt_passive_recover(td); 345 346 /* WARNING: we may have migrated cpu's */ 347 /* gd = td->td_gd; */ 348 349 /* 350 * Become the current user scheduled process if we aren't already, 351 * and deal with reschedule requests and other factors. 352 */ 353 lp->lwp_proc->p_usched->acquire_curproc(lp); 354 } 355 356 #if !defined(KTR_KERNENTRY) 357 #define KTR_KERNENTRY KTR_ALL 358 #endif 359 KTR_INFO_MASTER(kernentry); 360 KTR_INFO(KTR_KERNENTRY, kernentry, trap, 0, 361 "TRAP(pid %d, tid %d, trapno %ld, eva %lu)", 362 pid_t pid, lwpid_t tid, register_t trapno, vm_offset_t eva); 363 KTR_INFO(KTR_KERNENTRY, kernentry, trap_ret, 0, "TRAP_RET(pid %d, tid %d)", 364 pid_t pid, lwpid_t tid); 365 KTR_INFO(KTR_KERNENTRY, kernentry, syscall, 0, "SYSC(pid %d, tid %d, nr %ld)", 366 pid_t pid, lwpid_t tid, register_t trapno); 367 KTR_INFO(KTR_KERNENTRY, kernentry, syscall_ret, 0, "SYSRET(pid %d, tid %d, err %d)", 368 pid_t pid, lwpid_t tid, int err); 369 KTR_INFO(KTR_KERNENTRY, kernentry, fork_ret, 0, "FORKRET(pid %d, tid %d)", 370 pid_t pid, lwpid_t tid); 371 372 /* 373 * Exception, fault, and trap interface to the kernel. 374 * This common code is called from assembly language IDT gate entry 375 * routines that prepare a suitable stack frame, and restore this 376 * frame after the exception has been processed. 377 * 378 * This function is also called from doreti in an interlock to handle ASTs. 379 * For example: hardwareint->INTROUTINE->(set ast)->doreti->trap 380 * 381 * NOTE! We have to retrieve the fault address prior to obtaining the 382 * MP lock because get_mplock() may switch out. YYY cr2 really ought 383 * to be retrieved by the assembly code, not here. 384 * 385 * XXX gd_trap_nesting_level currently prevents lwkt_switch() from panicing 386 * if an attempt is made to switch from a fast interrupt or IPI. This is 387 * necessary to properly take fatal kernel traps on SMP machines if 388 * get_mplock() has to block. 389 */ 390 391 void 392 trap(struct trapframe *frame) 393 { 394 struct globaldata *gd = mycpu; 395 struct thread *td = gd->gd_curthread; 396 struct lwp *lp = td->td_lwp; 397 struct proc *p; 398 int sticks = 0; 399 int i = 0, ucode = 0, type, code; 400 int have_mplock = 0; 401 #ifdef INVARIANTS 402 int crit_count = td->td_critcount; 403 lwkt_tokref_t curstop = td->td_toks_stop; 404 #endif 405 vm_offset_t eva; 406 407 p = td->td_proc; 408 clear_quickret(); 409 410 #ifdef DDB 411 /* 412 * We need to allow T_DNA faults when the debugger is active since 413 * some dumping paths do large bcopy() which use the floating 414 * point registers for faster copying. 415 */ 416 if (db_active && frame->tf_trapno != T_DNA) { 417 eva = (frame->tf_trapno == T_PAGEFLT ? frame->tf_addr : 0); 418 ++gd->gd_trap_nesting_level; 419 MAKEMPSAFE(have_mplock); 420 trap_fatal(frame, eva); 421 --gd->gd_trap_nesting_level; 422 goto out2; 423 } 424 #endif 425 426 eva = 0; 427 428 if ((frame->tf_rflags & PSL_I) == 0) { 429 /* 430 * Buggy application or kernel code has disabled interrupts 431 * and then trapped. Enabling interrupts now is wrong, but 432 * it is better than running with interrupts disabled until 433 * they are accidentally enabled later. 434 */ 435 type = frame->tf_trapno; 436 if (ISPL(frame->tf_cs) == SEL_UPL) { 437 MAKEMPSAFE(have_mplock); 438 /* JG curproc can be NULL */ 439 kprintf( 440 "pid %ld (%s): trap %d with interrupts disabled\n", 441 (long)curproc->p_pid, curproc->p_comm, type); 442 } else if (type != T_NMI && type != T_BPTFLT && 443 type != T_TRCTRAP) { 444 /* 445 * XXX not quite right, since this may be for a 446 * multiple fault in user mode. 447 */ 448 MAKEMPSAFE(have_mplock); 449 kprintf("kernel trap %d with interrupts disabled\n", 450 type); 451 } 452 cpu_enable_intr(); 453 } 454 455 type = frame->tf_trapno; 456 code = frame->tf_err; 457 458 if (ISPL(frame->tf_cs) == SEL_UPL) { 459 /* user trap */ 460 461 KTR_LOG(kernentry_trap, p->p_pid, lp->lwp_tid, 462 frame->tf_trapno, eva); 463 464 userenter(td, p); 465 466 sticks = (int)td->td_sticks; 467 KASSERT(lp->lwp_md.md_regs == frame, 468 ("Frame mismatch %p %p", lp->lwp_md.md_regs, frame)); 469 470 switch (type) { 471 case T_PRIVINFLT: /* privileged instruction fault */ 472 i = SIGILL; 473 ucode = ILL_PRVOPC; 474 break; 475 476 case T_BPTFLT: /* bpt instruction fault */ 477 case T_TRCTRAP: /* trace trap */ 478 frame->tf_rflags &= ~PSL_T; 479 i = SIGTRAP; 480 ucode = (type == T_TRCTRAP ? TRAP_TRACE : TRAP_BRKPT); 481 break; 482 483 case T_ARITHTRAP: /* arithmetic trap */ 484 ucode = code; 485 i = SIGFPE; 486 break; 487 488 case T_ASTFLT: /* Allow process switch */ 489 mycpu->gd_cnt.v_soft++; 490 if (mycpu->gd_reqflags & RQF_AST_OWEUPC) { 491 atomic_clear_int(&mycpu->gd_reqflags, 492 RQF_AST_OWEUPC); 493 addupc_task(p, p->p_prof.pr_addr, 494 p->p_prof.pr_ticks); 495 } 496 goto out; 497 498 case T_PROTFLT: /* general protection fault */ 499 i = SIGBUS; 500 ucode = BUS_OBJERR; 501 break; 502 case T_STKFLT: /* stack fault */ 503 case T_SEGNPFLT: /* segment not present fault */ 504 i = SIGBUS; 505 ucode = BUS_ADRERR; 506 break; 507 case T_TSSFLT: /* invalid TSS fault */ 508 case T_DOUBLEFLT: /* double fault */ 509 default: 510 i = SIGBUS; 511 ucode = BUS_OBJERR; 512 break; 513 514 case T_PAGEFLT: /* page fault */ 515 i = trap_pfault(frame, TRUE); 516 if (frame->tf_rip == 0) { 517 kprintf("T_PAGEFLT: Warning %%rip == 0!\n"); 518 #ifdef DDB 519 while (freeze_on_seg_fault) 520 tsleep(p, 0, "freeze", hz * 20); 521 #endif 522 } 523 if (i == -1 || i == 0) 524 goto out; 525 526 527 if (i == SIGSEGV) 528 ucode = SEGV_MAPERR; 529 else { 530 i = SIGSEGV; 531 ucode = SEGV_ACCERR; 532 } 533 break; 534 535 case T_DIVIDE: /* integer divide fault */ 536 ucode = FPE_INTDIV; 537 i = SIGFPE; 538 break; 539 540 #if NISA > 0 541 case T_NMI: 542 MAKEMPSAFE(have_mplock); 543 /* machine/parity/power fail/"kitchen sink" faults */ 544 if (isa_nmi(code) == 0) { 545 #ifdef DDB 546 /* 547 * NMI can be hooked up to a pushbutton 548 * for debugging. 549 */ 550 if (ddb_on_nmi) { 551 kprintf ("NMI ... going to debugger\n"); 552 kdb_trap(type, 0, frame); 553 } 554 #endif /* DDB */ 555 goto out2; 556 } else if (panic_on_nmi) 557 panic("NMI indicates hardware failure"); 558 break; 559 #endif /* NISA > 0 */ 560 561 case T_OFLOW: /* integer overflow fault */ 562 ucode = FPE_INTOVF; 563 i = SIGFPE; 564 break; 565 566 case T_BOUND: /* bounds check fault */ 567 ucode = FPE_FLTSUB; 568 i = SIGFPE; 569 break; 570 571 case T_DNA: 572 /* 573 * Virtual kernel intercept - pass the DNA exception 574 * to the virtual kernel if it asked to handle it. 575 * This occurs when the virtual kernel is holding 576 * onto the FP context for a different emulated 577 * process then the one currently running. 578 * 579 * We must still call npxdna() since we may have 580 * saved FP state that the virtual kernel needs 581 * to hand over to a different emulated process. 582 */ 583 if (lp->lwp_vkernel && lp->lwp_vkernel->ve && 584 (td->td_pcb->pcb_flags & FP_VIRTFP) 585 ) { 586 npxdna(); 587 break; 588 } 589 590 /* 591 * The kernel may have switched out the FP unit's 592 * state, causing the user process to take a fault 593 * when it tries to use the FP unit. Restore the 594 * state here 595 */ 596 if (npxdna()) 597 goto out; 598 i = SIGFPE; 599 ucode = FPE_FPU_NP_TRAP; 600 break; 601 602 case T_FPOPFLT: /* FPU operand fetch fault */ 603 ucode = ILL_COPROC; 604 i = SIGILL; 605 break; 606 607 case T_XMMFLT: /* SIMD floating-point exception */ 608 ucode = 0; /* XXX */ 609 i = SIGFPE; 610 break; 611 } 612 } else { 613 /* kernel trap */ 614 615 switch (type) { 616 case T_PAGEFLT: /* page fault */ 617 trap_pfault(frame, FALSE); 618 goto out2; 619 620 case T_DNA: 621 /* 622 * The kernel is apparently using fpu for copying. 623 * XXX this should be fatal unless the kernel has 624 * registered such use. 625 */ 626 if (npxdna()) 627 goto out2; 628 break; 629 630 case T_STKFLT: /* stack fault */ 631 break; 632 633 case T_PROTFLT: /* general protection fault */ 634 case T_SEGNPFLT: /* segment not present fault */ 635 /* 636 * Invalid segment selectors and out of bounds 637 * %rip's and %rsp's can be set up in user mode. 638 * This causes a fault in kernel mode when the 639 * kernel tries to return to user mode. We want 640 * to get this fault so that we can fix the 641 * problem here and not have to check all the 642 * selectors and pointers when the user changes 643 * them. 644 */ 645 if (mycpu->gd_intr_nesting_level == 0) { 646 /* 647 * NOTE: in 64-bit mode traps push rsp/ss 648 * even if no ring change occurs. 649 */ 650 if (td->td_pcb->pcb_onfault && 651 td->td_pcb->pcb_onfault_sp == 652 frame->tf_rsp) { 653 frame->tf_rip = (register_t) 654 td->td_pcb->pcb_onfault; 655 goto out2; 656 } 657 if (frame->tf_rip == (long)doreti_iret) { 658 frame->tf_rip = (long)doreti_iret_fault; 659 goto out2; 660 } 661 } 662 break; 663 664 case T_TSSFLT: 665 /* 666 * PSL_NT can be set in user mode and isn't cleared 667 * automatically when the kernel is entered. This 668 * causes a TSS fault when the kernel attempts to 669 * `iret' because the TSS link is uninitialized. We 670 * want to get this fault so that we can fix the 671 * problem here and not every time the kernel is 672 * entered. 673 */ 674 if (frame->tf_rflags & PSL_NT) { 675 frame->tf_rflags &= ~PSL_NT; 676 goto out2; 677 } 678 break; 679 680 case T_TRCTRAP: /* trace trap */ 681 #if 0 682 if (frame->tf_rip == (int)IDTVEC(syscall)) { 683 /* 684 * We've just entered system mode via the 685 * syscall lcall. Continue single stepping 686 * silently until the syscall handler has 687 * saved the flags. 688 */ 689 goto out2; 690 } 691 if (frame->tf_rip == (int)IDTVEC(syscall) + 1) { 692 /* 693 * The syscall handler has now saved the 694 * flags. Stop single stepping it. 695 */ 696 frame->tf_rflags &= ~PSL_T; 697 goto out2; 698 } 699 #endif 700 701 /* 702 * Ignore debug register trace traps due to 703 * accesses in the user's address space, which 704 * can happen under several conditions such as 705 * if a user sets a watchpoint on a buffer and 706 * then passes that buffer to a system call. 707 * We still want to get TRCTRAPS for addresses 708 * in kernel space because that is useful when 709 * debugging the kernel. 710 */ 711 #if JG 712 if (user_dbreg_trap()) { 713 /* 714 * Reset breakpoint bits because the 715 * processor doesn't 716 */ 717 /* XXX check upper bits here */ 718 load_dr6(rdr6() & 0xfffffff0); 719 goto out2; 720 } 721 #endif 722 /* 723 * FALLTHROUGH (TRCTRAP kernel mode, kernel address) 724 */ 725 case T_BPTFLT: 726 /* 727 * If DDB is enabled, let it handle the debugger trap. 728 * Otherwise, debugger traps "can't happen". 729 */ 730 ucode = TRAP_BRKPT; 731 #ifdef DDB 732 MAKEMPSAFE(have_mplock); 733 if (kdb_trap(type, 0, frame)) 734 goto out2; 735 #endif 736 break; 737 738 #if NISA > 0 739 case T_NMI: 740 MAKEMPSAFE(have_mplock); 741 /* machine/parity/power fail/"kitchen sink" faults */ 742 if (isa_nmi(code) == 0) { 743 #ifdef DDB 744 /* 745 * NMI can be hooked up to a pushbutton 746 * for debugging. 747 */ 748 if (ddb_on_nmi) { 749 kprintf ("NMI ... going to debugger\n"); 750 kdb_trap(type, 0, frame); 751 } 752 #endif /* DDB */ 753 goto out2; 754 } else if (panic_on_nmi == 0) 755 goto out2; 756 /* FALL THROUGH */ 757 #endif /* NISA > 0 */ 758 } 759 MAKEMPSAFE(have_mplock); 760 trap_fatal(frame, 0); 761 goto out2; 762 } 763 764 /* 765 * Virtual kernel intercept - if the fault is directly related to a 766 * VM context managed by a virtual kernel then let the virtual kernel 767 * handle it. 768 */ 769 if (lp->lwp_vkernel && lp->lwp_vkernel->ve) { 770 vkernel_trap(lp, frame); 771 goto out; 772 } 773 774 /* Translate fault for emulators (e.g. Linux) */ 775 if (*p->p_sysent->sv_transtrap) 776 i = (*p->p_sysent->sv_transtrap)(i, type); 777 778 MAKEMPSAFE(have_mplock); 779 trapsignal(lp, i, ucode); 780 781 #ifdef DEBUG 782 if (type <= MAX_TRAP_MSG) { 783 uprintf("fatal process exception: %s", 784 trap_msg[type]); 785 if ((type == T_PAGEFLT) || (type == T_PROTFLT)) 786 uprintf(", fault VA = 0x%lx", frame->tf_addr); 787 uprintf("\n"); 788 } 789 #endif 790 791 out: 792 userret(lp, frame, sticks); 793 userexit(lp); 794 out2: ; 795 if (have_mplock) 796 rel_mplock(); 797 if (p != NULL && lp != NULL) 798 KTR_LOG(kernentry_trap_ret, p->p_pid, lp->lwp_tid); 799 #ifdef INVARIANTS 800 KASSERT(crit_count == td->td_critcount, 801 ("trap: critical section count mismatch! %d/%d", 802 crit_count, td->td_pri)); 803 KASSERT(curstop == td->td_toks_stop, 804 ("trap: extra tokens held after trap! %ld/%ld", 805 curstop - &td->td_toks_base, 806 td->td_toks_stop - &td->td_toks_base)); 807 #endif 808 } 809 810 static int 811 trap_pfault(struct trapframe *frame, int usermode) 812 { 813 vm_offset_t va; 814 struct vmspace *vm = NULL; 815 vm_map_t map; 816 int rv = 0; 817 int fault_flags; 818 vm_prot_t ftype; 819 thread_t td = curthread; 820 struct lwp *lp = td->td_lwp; 821 struct proc *p; 822 823 va = trunc_page(frame->tf_addr); 824 if (va >= VM_MIN_KERNEL_ADDRESS) { 825 /* 826 * Don't allow user-mode faults in kernel address space. 827 */ 828 if (usermode) { 829 fault_flags = -1; 830 ftype = -1; 831 goto nogo; 832 } 833 834 map = &kernel_map; 835 } else { 836 /* 837 * This is a fault on non-kernel virtual memory. 838 * vm is initialized above to NULL. If curproc is NULL 839 * or curproc->p_vmspace is NULL the fault is fatal. 840 */ 841 if (lp != NULL) 842 vm = lp->lwp_vmspace; 843 844 if (vm == NULL) { 845 fault_flags = -1; 846 ftype = -1; 847 goto nogo; 848 } 849 850 /* 851 * Debugging, try to catch kernel faults on the user address space when not inside 852 * on onfault (e.g. copyin/copyout) routine. 853 */ 854 if (usermode == 0 && (td->td_pcb == NULL || 855 td->td_pcb->pcb_onfault == NULL)) { 856 #ifdef DDB 857 if (freeze_on_seg_fault) { 858 kprintf("trap_pfault: user address fault from kernel mode " 859 "%016lx\n", (long)frame->tf_addr); 860 while (freeze_on_seg_fault) 861 tsleep(&freeze_on_seg_fault, 0, "frzseg", hz * 20); 862 } 863 #endif 864 } 865 map = &vm->vm_map; 866 } 867 868 /* 869 * PGEX_I is defined only if the execute disable bit capability is 870 * supported and enabled. 871 */ 872 if (frame->tf_err & PGEX_W) 873 ftype = VM_PROT_WRITE; 874 #if JG 875 else if ((frame->tf_err & PGEX_I) && pg_nx != 0) 876 ftype = VM_PROT_EXECUTE; 877 #endif 878 else 879 ftype = VM_PROT_READ; 880 881 if (map != &kernel_map) { 882 /* 883 * Keep swapout from messing with us during this 884 * critical time. 885 */ 886 PHOLD(lp->lwp_proc); 887 888 /* 889 * Issue fault 890 */ 891 fault_flags = 0; 892 if (usermode) 893 fault_flags |= VM_FAULT_BURST; 894 if (ftype & VM_PROT_WRITE) 895 fault_flags |= VM_FAULT_DIRTY; 896 else 897 fault_flags |= VM_FAULT_NORMAL; 898 rv = vm_fault(map, va, ftype, fault_flags); 899 900 PRELE(lp->lwp_proc); 901 } else { 902 /* 903 * Don't have to worry about process locking or stacks in the 904 * kernel. 905 */ 906 fault_flags = VM_FAULT_NORMAL; 907 rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL); 908 } 909 if (rv == KERN_SUCCESS) 910 return (0); 911 nogo: 912 if (!usermode) { 913 /* 914 * NOTE: in 64-bit mode traps push rsp/ss 915 * even if no ring change occurs. 916 */ 917 if (td->td_pcb->pcb_onfault && 918 td->td_pcb->pcb_onfault_sp == frame->tf_rsp && 919 td->td_gd->gd_intr_nesting_level == 0) { 920 frame->tf_rip = (register_t)td->td_pcb->pcb_onfault; 921 return (0); 922 } 923 trap_fatal(frame, frame->tf_addr); 924 return (-1); 925 } 926 927 /* 928 * NOTE: on x86_64 we have a tf_addr field in the trapframe, no 929 * kludge is needed to pass the fault address to signal handlers. 930 */ 931 p = td->td_proc; 932 if (td->td_lwp->lwp_vkernel == NULL) { 933 #ifdef DDB 934 if (bootverbose || freeze_on_seg_fault || ddb_on_seg_fault) { 935 #else 936 if (bootverbose) { 937 #endif 938 kprintf("seg-fault ft=%04x ff=%04x addr=%p rip=%p " 939 "pid=%d cpu=%d p_comm=%s\n", 940 ftype, fault_flags, 941 (void *)frame->tf_addr, 942 (void *)frame->tf_rip, 943 p->p_pid, mycpu->gd_cpuid, p->p_comm); 944 } 945 #ifdef DDB 946 while (freeze_on_seg_fault) { 947 tsleep(p, 0, "freeze", hz * 20); 948 } 949 if (ddb_on_seg_fault) 950 Debugger("ddb_on_seg_fault"); 951 #endif 952 } 953 954 return((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV); 955 } 956 957 static void 958 trap_fatal(struct trapframe *frame, vm_offset_t eva) 959 { 960 int code, ss; 961 u_int type; 962 long rsp; 963 struct soft_segment_descriptor softseg; 964 char *msg; 965 966 code = frame->tf_err; 967 type = frame->tf_trapno; 968 sdtossd(&gdt[IDXSEL(frame->tf_cs & 0xffff)], &softseg); 969 970 if (type <= MAX_TRAP_MSG) 971 msg = trap_msg[type]; 972 else 973 msg = "UNKNOWN"; 974 kprintf("\n\nFatal trap %d: %s while in %s mode\n", type, msg, 975 ISPL(frame->tf_cs) == SEL_UPL ? "user" : "kernel"); 976 /* three separate prints in case of a trap on an unmapped page */ 977 kprintf("cpuid = %d; ", mycpu->gd_cpuid); 978 kprintf("lapic->id = %08x\n", lapic->id); 979 if (type == T_PAGEFLT) { 980 kprintf("fault virtual address = 0x%lx\n", eva); 981 kprintf("fault code = %s %s %s, %s\n", 982 code & PGEX_U ? "user" : "supervisor", 983 code & PGEX_W ? "write" : "read", 984 code & PGEX_I ? "instruction" : "data", 985 code & PGEX_P ? "protection violation" : "page not present"); 986 } 987 kprintf("instruction pointer = 0x%lx:0x%lx\n", 988 frame->tf_cs & 0xffff, frame->tf_rip); 989 if (ISPL(frame->tf_cs) == SEL_UPL) { 990 ss = frame->tf_ss & 0xffff; 991 rsp = frame->tf_rsp; 992 } else { 993 /* 994 * NOTE: in 64-bit mode traps push rsp/ss even if no ring 995 * change occurs. 996 */ 997 ss = GSEL(GDATA_SEL, SEL_KPL); 998 rsp = frame->tf_rsp; 999 } 1000 kprintf("stack pointer = 0x%x:0x%lx\n", ss, rsp); 1001 kprintf("frame pointer = 0x%x:0x%lx\n", ss, frame->tf_rbp); 1002 kprintf("code segment = base 0x%lx, limit 0x%lx, type 0x%x\n", 1003 softseg.ssd_base, softseg.ssd_limit, softseg.ssd_type); 1004 kprintf(" = DPL %d, pres %d, long %d, def32 %d, gran %d\n", 1005 softseg.ssd_dpl, softseg.ssd_p, softseg.ssd_long, softseg.ssd_def32, 1006 softseg.ssd_gran); 1007 kprintf("processor eflags = "); 1008 if (frame->tf_rflags & PSL_T) 1009 kprintf("trace trap, "); 1010 if (frame->tf_rflags & PSL_I) 1011 kprintf("interrupt enabled, "); 1012 if (frame->tf_rflags & PSL_NT) 1013 kprintf("nested task, "); 1014 if (frame->tf_rflags & PSL_RF) 1015 kprintf("resume, "); 1016 kprintf("IOPL = %ld\n", (frame->tf_rflags & PSL_IOPL) >> 12); 1017 kprintf("current process = "); 1018 if (curproc) { 1019 kprintf("%lu\n", 1020 (u_long)curproc->p_pid); 1021 } else { 1022 kprintf("Idle\n"); 1023 } 1024 kprintf("current thread = pri %d ", curthread->td_pri); 1025 if (curthread->td_critcount) 1026 kprintf("(CRIT)"); 1027 kprintf("\n"); 1028 1029 #ifdef DDB 1030 if ((debugger_on_panic || db_active) && kdb_trap(type, code, frame)) 1031 return; 1032 #endif 1033 kprintf("trap number = %d\n", type); 1034 if (type <= MAX_TRAP_MSG) 1035 panic("%s", trap_msg[type]); 1036 else 1037 panic("unknown/reserved trap"); 1038 } 1039 1040 /* 1041 * Double fault handler. Called when a fault occurs while writing 1042 * a frame for a trap/exception onto the stack. This usually occurs 1043 * when the stack overflows (such is the case with infinite recursion, 1044 * for example). 1045 */ 1046 static __inline 1047 int 1048 in_kstack_guard(register_t rptr) 1049 { 1050 thread_t td = curthread; 1051 1052 if ((char *)rptr >= td->td_kstack && 1053 (char *)rptr < td->td_kstack + PAGE_SIZE) { 1054 return 1; 1055 } 1056 return 0; 1057 } 1058 1059 void 1060 dblfault_handler(struct trapframe *frame) 1061 { 1062 thread_t td = curthread; 1063 1064 if (in_kstack_guard(frame->tf_rsp) || in_kstack_guard(frame->tf_rbp)) { 1065 kprintf("DOUBLE FAULT - KERNEL STACK GUARD HIT!\n"); 1066 if (in_kstack_guard(frame->tf_rsp)) 1067 frame->tf_rsp = (register_t)(td->td_kstack + PAGE_SIZE); 1068 if (in_kstack_guard(frame->tf_rbp)) 1069 frame->tf_rbp = (register_t)(td->td_kstack + PAGE_SIZE); 1070 } else { 1071 kprintf("DOUBLE FAULT\n"); 1072 } 1073 kprintf("\nFatal double fault\n"); 1074 kprintf("rip = 0x%lx\n", frame->tf_rip); 1075 kprintf("rsp = 0x%lx\n", frame->tf_rsp); 1076 kprintf("rbp = 0x%lx\n", frame->tf_rbp); 1077 /* three separate prints in case of a trap on an unmapped page */ 1078 kprintf("cpuid = %d; ", mycpu->gd_cpuid); 1079 kprintf("lapic->id = %08x\n", lapic->id); 1080 panic("double fault"); 1081 } 1082 1083 /* 1084 * syscall2 - MP aware system call request C handler 1085 * 1086 * A system call is essentially treated as a trap except that the 1087 * MP lock is not held on entry or return. We are responsible for 1088 * obtaining the MP lock if necessary and for handling ASTs 1089 * (e.g. a task switch) prior to return. 1090 * 1091 * MPSAFE 1092 */ 1093 void 1094 syscall2(struct trapframe *frame) 1095 { 1096 struct thread *td = curthread; 1097 struct proc *p = td->td_proc; 1098 struct lwp *lp = td->td_lwp; 1099 caddr_t params; 1100 struct sysent *callp; 1101 register_t orig_tf_rflags; 1102 int sticks; 1103 int error; 1104 int narg; 1105 #ifdef INVARIANTS 1106 int crit_count = td->td_critcount; 1107 #endif 1108 int have_mplock = 0; 1109 register_t *argp; 1110 u_int code; 1111 int reg, regcnt; 1112 union sysunion args; 1113 register_t *argsdst; 1114 1115 mycpu->gd_cnt.v_syscall++; 1116 1117 #ifdef DIAGNOSTIC 1118 if (ISPL(frame->tf_cs) != SEL_UPL) { 1119 get_mplock(); 1120 panic("syscall"); 1121 /* NOT REACHED */ 1122 } 1123 #endif 1124 1125 KTR_LOG(kernentry_syscall, p->p_pid, lp->lwp_tid, 1126 frame->tf_rax); 1127 1128 userenter(td, p); /* lazy raise our priority */ 1129 1130 reg = 0; 1131 regcnt = 6; 1132 /* 1133 * Misc 1134 */ 1135 sticks = (int)td->td_sticks; 1136 orig_tf_rflags = frame->tf_rflags; 1137 1138 /* 1139 * Virtual kernel intercept - if a VM context managed by a virtual 1140 * kernel issues a system call the virtual kernel handles it, not us. 1141 * Restore the virtual kernel context and return from its system 1142 * call. The current frame is copied out to the virtual kernel. 1143 */ 1144 if (lp->lwp_vkernel && lp->lwp_vkernel->ve) { 1145 vkernel_trap(lp, frame); 1146 error = EJUSTRETURN; 1147 goto out; 1148 } 1149 1150 /* 1151 * Get the system call parameters and account for time 1152 */ 1153 KASSERT(lp->lwp_md.md_regs == frame, 1154 ("Frame mismatch %p %p", lp->lwp_md.md_regs, frame)); 1155 params = (caddr_t)frame->tf_rsp + sizeof(register_t); 1156 code = frame->tf_rax; 1157 1158 if (p->p_sysent->sv_prepsyscall) { 1159 (*p->p_sysent->sv_prepsyscall)( 1160 frame, (int *)(&args.nosys.sysmsg + 1), 1161 &code, ¶ms); 1162 } else { 1163 if (code == SYS_syscall || code == SYS___syscall) { 1164 code = frame->tf_rdi; 1165 reg++; 1166 regcnt--; 1167 } 1168 } 1169 1170 if (p->p_sysent->sv_mask) 1171 code &= p->p_sysent->sv_mask; 1172 1173 if (code >= p->p_sysent->sv_size) 1174 callp = &p->p_sysent->sv_table[0]; 1175 else 1176 callp = &p->p_sysent->sv_table[code]; 1177 1178 narg = callp->sy_narg & SYF_ARGMASK; 1179 1180 /* 1181 * On x86_64 we get up to six arguments in registers. The rest are 1182 * on the stack. The first six members of 'struct trapframe' happen 1183 * to be the registers used to pass arguments, in exactly the right 1184 * order. 1185 */ 1186 argp = &frame->tf_rdi; 1187 argp += reg; 1188 argsdst = (register_t *)(&args.nosys.sysmsg + 1); 1189 /* 1190 * JG can we overflow the space pointed to by 'argsdst' 1191 * either with 'bcopy' or with 'copyin'? 1192 */ 1193 bcopy(argp, argsdst, sizeof(register_t) * regcnt); 1194 /* 1195 * copyin is MP aware, but the tracing code is not 1196 */ 1197 if (narg > regcnt) { 1198 KASSERT(params != NULL, ("copyin args with no params!")); 1199 error = copyin(params, &argsdst[regcnt], 1200 (narg - regcnt) * sizeof(register_t)); 1201 if (error) { 1202 #ifdef KTRACE 1203 if (KTRPOINT(td, KTR_SYSCALL)) { 1204 MAKEMPSAFE(have_mplock); 1205 1206 ktrsyscall(lp, code, narg, 1207 (void *)(&args.nosys.sysmsg + 1)); 1208 } 1209 #endif 1210 goto bad; 1211 } 1212 } 1213 1214 #ifdef KTRACE 1215 if (KTRPOINT(td, KTR_SYSCALL)) { 1216 MAKEMPSAFE(have_mplock); 1217 ktrsyscall(lp, code, narg, (void *)(&args.nosys.sysmsg + 1)); 1218 } 1219 #endif 1220 1221 /* 1222 * Default return value is 0 (will be copied to %rax). Double-value 1223 * returns use %rax and %rdx. %rdx is left unchanged for system 1224 * calls which return only one result. 1225 */ 1226 args.sysmsg_fds[0] = 0; 1227 args.sysmsg_fds[1] = frame->tf_rdx; 1228 1229 /* 1230 * The syscall might manipulate the trap frame. If it does it 1231 * will probably return EJUSTRETURN. 1232 */ 1233 args.sysmsg_frame = frame; 1234 1235 STOPEVENT(p, S_SCE, narg); /* MP aware */ 1236 1237 /* 1238 * NOTE: All system calls run MPSAFE now. The system call itself 1239 * is responsible for getting the MP lock. 1240 */ 1241 #ifdef SYSCALL_DEBUG 1242 uint64_t tscval = rdtsc(); 1243 #endif 1244 error = (*callp->sy_call)(&args); 1245 #ifdef SYSCALL_DEBUG 1246 tscval = rdtsc() - tscval; 1247 tscval = tscval * 1000000 / tsc_frequency; 1248 if (SysCallsWorstCase[code] < tscval) 1249 SysCallsWorstCase[code] = tscval; 1250 #endif 1251 1252 out: 1253 /* 1254 * MP SAFE (we may or may not have the MP lock at this point) 1255 */ 1256 //kprintf("SYSMSG %d ", error); 1257 switch (error) { 1258 case 0: 1259 /* 1260 * Reinitialize proc pointer `p' as it may be different 1261 * if this is a child returning from fork syscall. 1262 */ 1263 p = curproc; 1264 lp = curthread->td_lwp; 1265 frame->tf_rax = args.sysmsg_fds[0]; 1266 frame->tf_rdx = args.sysmsg_fds[1]; 1267 frame->tf_rflags &= ~PSL_C; 1268 break; 1269 case ERESTART: 1270 /* 1271 * Reconstruct pc, we know that 'syscall' is 2 bytes. 1272 * We have to do a full context restore so that %r10 1273 * (which was holding the value of %rcx) is restored for 1274 * the next iteration. 1275 */ 1276 if (frame->tf_err != 0 && frame->tf_err != 2) 1277 kprintf("lp %s:%d frame->tf_err is weird %ld\n", 1278 td->td_comm, lp->lwp_proc->p_pid, frame->tf_err); 1279 frame->tf_rip -= frame->tf_err; 1280 frame->tf_r10 = frame->tf_rcx; 1281 break; 1282 case EJUSTRETURN: 1283 break; 1284 case EASYNC: 1285 panic("Unexpected EASYNC return value (for now)"); 1286 default: 1287 bad: 1288 if (p->p_sysent->sv_errsize) { 1289 if (error >= p->p_sysent->sv_errsize) 1290 error = -1; /* XXX */ 1291 else 1292 error = p->p_sysent->sv_errtbl[error]; 1293 } 1294 frame->tf_rax = error; 1295 frame->tf_rflags |= PSL_C; 1296 break; 1297 } 1298 1299 /* 1300 * Traced syscall. trapsignal() is not MP aware. 1301 */ 1302 if (orig_tf_rflags & PSL_T) { 1303 MAKEMPSAFE(have_mplock); 1304 frame->tf_rflags &= ~PSL_T; 1305 trapsignal(lp, SIGTRAP, TRAP_TRACE); 1306 } 1307 1308 /* 1309 * Handle reschedule and other end-of-syscall issues 1310 */ 1311 userret(lp, frame, sticks); 1312 1313 #ifdef KTRACE 1314 if (KTRPOINT(td, KTR_SYSRET)) { 1315 MAKEMPSAFE(have_mplock); 1316 ktrsysret(lp, code, error, args.sysmsg_result); 1317 } 1318 #endif 1319 1320 /* 1321 * This works because errno is findable through the 1322 * register set. If we ever support an emulation where this 1323 * is not the case, this code will need to be revisited. 1324 */ 1325 STOPEVENT(p, S_SCX, code); 1326 1327 userexit(lp); 1328 /* 1329 * Release the MP lock if we had to get it 1330 */ 1331 if (have_mplock) 1332 rel_mplock(); 1333 KTR_LOG(kernentry_syscall_ret, p->p_pid, lp->lwp_tid, error); 1334 #ifdef INVARIANTS 1335 KASSERT(crit_count == td->td_critcount, 1336 ("syscall: critical section count mismatch! %d/%d", 1337 crit_count, td->td_pri)); 1338 KASSERT(&td->td_toks_base == td->td_toks_stop, 1339 ("syscall: extra tokens held after trap! %ld", 1340 td->td_toks_stop - &td->td_toks_base)); 1341 #endif 1342 } 1343 1344 /* 1345 * NOTE: mplock not held at any point 1346 */ 1347 void 1348 fork_return(struct lwp *lp, struct trapframe *frame) 1349 { 1350 frame->tf_rax = 0; /* Child returns zero */ 1351 frame->tf_rflags &= ~PSL_C; /* success */ 1352 frame->tf_rdx = 1; 1353 1354 generic_lwp_return(lp, frame); 1355 KTR_LOG(kernentry_fork_ret, lp->lwp_proc->p_pid, lp->lwp_tid); 1356 } 1357 1358 /* 1359 * Simplified back end of syscall(), used when returning from fork() 1360 * directly into user mode. 1361 * 1362 * This code will return back into the fork trampoline code which then 1363 * runs doreti. 1364 * 1365 * NOTE: The mplock is not held at any point. 1366 */ 1367 void 1368 generic_lwp_return(struct lwp *lp, struct trapframe *frame) 1369 { 1370 struct proc *p = lp->lwp_proc; 1371 1372 /* 1373 * Newly forked processes are given a kernel priority. We have to 1374 * adjust the priority to a normal user priority and fake entry 1375 * into the kernel (call userenter()) to install a passive release 1376 * function just in case userret() decides to stop the process. This 1377 * can occur when ^Z races a fork. If we do not install the passive 1378 * release function the current process designation will not be 1379 * released when the thread goes to sleep. 1380 */ 1381 lwkt_setpri_self(TDPRI_USER_NORM); 1382 userenter(lp->lwp_thread, p); 1383 userret(lp, frame, 0); 1384 #ifdef KTRACE 1385 if (KTRPOINT(lp->lwp_thread, KTR_SYSRET)) 1386 ktrsysret(lp, SYS_fork, 0, 0); 1387 #endif 1388 lp->lwp_flags |= LWP_PASSIVE_ACQ; 1389 userexit(lp); 1390 lp->lwp_flags &= ~LWP_PASSIVE_ACQ; 1391 } 1392 1393 /* 1394 * If PGEX_FPFAULT is set then set FP_VIRTFP in the PCB to force a T_DNA 1395 * fault (which is then passed back to the virtual kernel) if an attempt is 1396 * made to use the FP unit. 1397 * 1398 * XXX this is a fairly big hack. 1399 */ 1400 void 1401 set_vkernel_fp(struct trapframe *frame) 1402 { 1403 struct thread *td = curthread; 1404 1405 if (frame->tf_xflags & PGEX_FPFAULT) { 1406 td->td_pcb->pcb_flags |= FP_VIRTFP; 1407 if (mdcpu->gd_npxthread == td) 1408 npxexit(); 1409 } else { 1410 td->td_pcb->pcb_flags &= ~FP_VIRTFP; 1411 } 1412 } 1413 1414 /* 1415 * Called from vkernel_trap() to fixup the vkernel's syscall 1416 * frame for vmspace_ctl() return. 1417 */ 1418 void 1419 cpu_vkernel_trap(struct trapframe *frame, int error) 1420 { 1421 frame->tf_rax = error; 1422 if (error) 1423 frame->tf_rflags |= PSL_C; 1424 else 1425 frame->tf_rflags &= ~PSL_C; 1426 } 1427