1 /*- 2 * Copyright (C) 1994, David Greenman 3 * Copyright (c) 1990, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * This code is derived from software contributed to Berkeley by 7 * the University of Utah, and William Jolitz. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. All advertising materials mentioning features or use of this software 18 * must display the following acknowledgement: 19 * This product includes software developed by the University of 20 * California, Berkeley and its contributors. 21 * 4. Neither the name of the University nor the names of its contributors 22 * may be used to endorse or promote products derived from this software 23 * without specific prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 * 37 * from: @(#)trap.c 7.4 (Berkeley) 5/13/91 38 * $FreeBSD: src/sys/i386/i386/trap.c,v 1.147.2.11 2003/02/27 19:09:59 luoqi Exp $ 39 */ 40 41 /* 42 * x86_64 Trap and System call handling 43 */ 44 45 #include "use_isa.h" 46 47 #include "opt_ddb.h" 48 #include "opt_ktrace.h" 49 50 #include <sys/param.h> 51 #include <sys/systm.h> 52 #include <sys/proc.h> 53 #include <sys/pioctl.h> 54 #include <sys/kernel.h> 55 #include <sys/resourcevar.h> 56 #include <sys/signalvar.h> 57 #include <sys/signal2.h> 58 #include <sys/syscall.h> 59 #include <sys/sysctl.h> 60 #include <sys/sysent.h> 61 #include <sys/uio.h> 62 #include <sys/vmmeter.h> 63 #include <sys/malloc.h> 64 #ifdef KTRACE 65 #include <sys/ktrace.h> 66 #endif 67 #include <sys/ktr.h> 68 #include <sys/upcall.h> 69 #include <sys/vkernel.h> 70 #include <sys/sysproto.h> 71 #include <sys/sysunion.h> 72 #include <sys/vmspace.h> 73 74 #include <vm/vm.h> 75 #include <vm/vm_param.h> 76 #include <sys/lock.h> 77 #include <vm/pmap.h> 78 #include <vm/vm_kern.h> 79 #include <vm/vm_map.h> 80 #include <vm/vm_page.h> 81 #include <vm/vm_extern.h> 82 83 #include <machine/cpu.h> 84 #include <machine/md_var.h> 85 #include <machine/pcb.h> 86 #include <machine/smp.h> 87 #include <machine/tss.h> 88 #include <machine/globaldata.h> 89 90 #include <ddb/ddb.h> 91 92 #include <sys/msgport2.h> 93 #include <sys/thread2.h> 94 #include <sys/mplock2.h> 95 96 #ifdef SMP 97 98 #define MAKEMPSAFE(have_mplock) \ 99 if (have_mplock == 0) { \ 100 get_mplock(); \ 101 have_mplock = 1; \ 102 } 103 104 #else 105 106 #define MAKEMPSAFE(have_mplock) 107 108 #endif 109 110 int (*pmath_emulate) (struct trapframe *); 111 112 extern int trapwrite (unsigned addr); 113 114 static int trap_pfault (struct trapframe *, int, vm_offset_t); 115 static void trap_fatal (struct trapframe *, int, vm_offset_t); 116 void dblfault_handler (void); 117 118 #if 0 119 extern inthand_t IDTVEC(syscall); 120 #endif 121 122 #define MAX_TRAP_MSG 30 123 static char *trap_msg[] = { 124 "", /* 0 unused */ 125 "privileged instruction fault", /* 1 T_PRIVINFLT */ 126 "", /* 2 unused */ 127 "breakpoint instruction fault", /* 3 T_BPTFLT */ 128 "", /* 4 unused */ 129 "", /* 5 unused */ 130 "arithmetic trap", /* 6 T_ARITHTRAP */ 131 "system forced exception", /* 7 T_ASTFLT */ 132 "", /* 8 unused */ 133 "general protection fault", /* 9 T_PROTFLT */ 134 "trace trap", /* 10 T_TRCTRAP */ 135 "", /* 11 unused */ 136 "page fault", /* 12 T_PAGEFLT */ 137 "", /* 13 unused */ 138 "alignment fault", /* 14 T_ALIGNFLT */ 139 "", /* 15 unused */ 140 "", /* 16 unused */ 141 "", /* 17 unused */ 142 "integer divide fault", /* 18 T_DIVIDE */ 143 "non-maskable interrupt trap", /* 19 T_NMI */ 144 "overflow trap", /* 20 T_OFLOW */ 145 "FPU bounds check fault", /* 21 T_BOUND */ 146 "FPU device not available", /* 22 T_DNA */ 147 "double fault", /* 23 T_DOUBLEFLT */ 148 "FPU operand fetch fault", /* 24 T_FPOPFLT */ 149 "invalid TSS fault", /* 25 T_TSSFLT */ 150 "segment not present fault", /* 26 T_SEGNPFLT */ 151 "stack fault", /* 27 T_STKFLT */ 152 "machine check trap", /* 28 T_MCHK */ 153 "SIMD floating-point exception", /* 29 T_XMMFLT */ 154 "reserved (unknown) fault", /* 30 T_RESERVED */ 155 }; 156 157 #ifdef DDB 158 static int ddb_on_nmi = 1; 159 SYSCTL_INT(_machdep, OID_AUTO, ddb_on_nmi, CTLFLAG_RW, 160 &ddb_on_nmi, 0, "Go to DDB on NMI"); 161 #endif 162 static int panic_on_nmi = 1; 163 SYSCTL_INT(_machdep, OID_AUTO, panic_on_nmi, CTLFLAG_RW, 164 &panic_on_nmi, 0, "Panic on NMI"); 165 static int fast_release; 166 SYSCTL_INT(_machdep, OID_AUTO, fast_release, CTLFLAG_RW, 167 &fast_release, 0, "Passive Release was optimal"); 168 static int slow_release; 169 SYSCTL_INT(_machdep, OID_AUTO, slow_release, CTLFLAG_RW, 170 &slow_release, 0, "Passive Release was nonoptimal"); 171 172 MALLOC_DEFINE(M_SYSMSG, "sysmsg", "sysmsg structure"); 173 extern int max_sysmsg; 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 static __inline void 186 userenter(struct thread *curtd, struct proc *curp) 187 { 188 struct ucred *ocred; 189 struct ucred *ncred; 190 191 curtd->td_release = lwkt_passive_release; 192 193 if (curtd->td_ucred != curp->p_ucred) { 194 ncred = crhold(curp->p_ucred); 195 ocred = curtd->td_ucred; 196 curtd->td_ucred = ncred; 197 if (ocred) 198 crfree(ocred); 199 } 200 } 201 202 /* 203 * Handle signals, upcalls, profiling, and other AST's and/or tasks that 204 * must be completed before we can return to or try to return to userland. 205 * 206 * Note that td_sticks is a 64 bit quantity, but there's no point doing 64 207 * arithmatic on the delta calculation so the absolute tick values are 208 * truncated to an integer. 209 */ 210 static void 211 userret(struct lwp *lp, struct trapframe *frame, int sticks) 212 { 213 struct proc *p = lp->lwp_proc; 214 int sig; 215 216 /* 217 * Charge system time if profiling. Note: times are in microseconds. 218 * This may do a copyout and block, so do it first even though it 219 * means some system time will be charged as user time. 220 */ 221 if (p->p_flags & P_PROFIL) { 222 addupc_task(p, frame->tf_rip, 223 (u_int)((int)lp->lwp_thread->td_sticks - sticks)); 224 } 225 226 recheck: 227 /* 228 * If the jungle wants us dead, so be it. 229 */ 230 if (lp->lwp_mpflags & LWP_MP_WEXIT) { 231 lwkt_gettoken(&p->p_token); 232 lwp_exit(0); 233 lwkt_reltoken(&p->p_token); /* NOT REACHED */ 234 } 235 236 /* 237 * Block here if we are in a stopped state. 238 */ 239 if (p->p_stat == SSTOP) { 240 lwkt_gettoken(&p->p_token); 241 tstop(); 242 lwkt_reltoken(&p->p_token); 243 goto recheck; 244 } 245 246 /* 247 * Post any pending upcalls. If running a virtual kernel be sure 248 * to restore the virtual kernel's vmspace before posting the upcall. 249 */ 250 if (p->p_flags & (P_SIGVTALRM | P_SIGPROF | P_UPCALLPEND)) { 251 lwkt_gettoken(&p->p_token); 252 if (p->p_flags & P_SIGVTALRM) { 253 p->p_flags &= ~P_SIGVTALRM; 254 ksignal(p, SIGVTALRM); 255 } 256 if (p->p_flags & P_SIGPROF) { 257 p->p_flags &= ~P_SIGPROF; 258 ksignal(p, SIGPROF); 259 } 260 if (p->p_flags & P_UPCALLPEND) { 261 p->p_flags &= ~P_UPCALLPEND; 262 postupcall(lp); 263 } 264 lwkt_reltoken(&p->p_token); 265 goto recheck; 266 } 267 268 /* 269 * Post any pending signals 270 * 271 * WARNING! postsig() can exit and not return. 272 */ 273 if ((sig = CURSIG_TRACE(lp)) != 0) { 274 lwkt_gettoken(&p->p_token); 275 postsig(sig); 276 lwkt_reltoken(&p->p_token); 277 goto recheck; 278 } 279 280 /* 281 * block here if we are swapped out, but still process signals 282 * (such as SIGKILL). proc0 (the swapin scheduler) is already 283 * aware of our situation, we do not have to wake it up. 284 */ 285 if (p->p_flags & P_SWAPPEDOUT) { 286 lwkt_gettoken(&p->p_token); 287 get_mplock(); 288 p->p_flags |= P_SWAPWAIT; 289 swapin_request(); 290 if (p->p_flags & P_SWAPWAIT) 291 tsleep(p, PCATCH, "SWOUT", 0); 292 p->p_flags &= ~P_SWAPWAIT; 293 rel_mplock(); 294 lwkt_reltoken(&p->p_token); 295 goto recheck; 296 } 297 298 /* 299 * In a multi-threaded program it is possible for a thread to change 300 * signal state during a system call which temporarily changes the 301 * signal mask. In this case postsig() might not be run and we 302 * have to restore the mask ourselves. 303 */ 304 if (lp->lwp_flags & LWP_OLDMASK) { 305 lp->lwp_flags &= ~LWP_OLDMASK; 306 lp->lwp_sigmask = lp->lwp_oldsigmask; 307 goto recheck; 308 } 309 } 310 311 /* 312 * Cleanup from userenter and any passive release that might have occured. 313 * We must reclaim the current-process designation before we can return 314 * to usermode. We also handle both LWKT and USER reschedule requests. 315 */ 316 static __inline void 317 userexit(struct lwp *lp) 318 { 319 struct thread *td = lp->lwp_thread; 320 /* globaldata_t gd = td->td_gd; */ 321 322 /* 323 * Handle stop requests at kernel priority. Any requests queued 324 * after this loop will generate another AST. 325 */ 326 while (lp->lwp_proc->p_stat == SSTOP) { 327 lwkt_gettoken(&lp->lwp_proc->p_token); 328 tstop(); 329 lwkt_reltoken(&lp->lwp_proc->p_token); 330 } 331 332 /* 333 * Reduce our priority in preparation for a return to userland. If 334 * our passive release function was still in place, our priority was 335 * never raised and does not need to be reduced. 336 */ 337 lwkt_passive_recover(td); 338 339 /* 340 * Become the current user scheduled process if we aren't already, 341 * and deal with reschedule requests and other factors. 342 */ 343 lp->lwp_proc->p_usched->acquire_curproc(lp); 344 /* WARNING: we may have migrated cpu's */ 345 /* gd = td->td_gd; */ 346 } 347 348 #if !defined(KTR_KERNENTRY) 349 #define KTR_KERNENTRY KTR_ALL 350 #endif 351 KTR_INFO_MASTER(kernentry); 352 KTR_INFO(KTR_KERNENTRY, kernentry, trap, 0, 353 "TRAP(pid %hd, tid %hd, trapno %ld, eva %lu)", 354 pid_t pid, lwpid_t tid, register_t trapno, vm_offset_t eva); 355 KTR_INFO(KTR_KERNENTRY, kernentry, trap_ret, 0, "TRAP_RET(pid %hd, tid %hd)", 356 pid_t pid, lwpid_t tid); 357 KTR_INFO(KTR_KERNENTRY, kernentry, syscall, 0, "SYSC(pid %hd, tid %hd, nr %ld)", 358 pid_t pid, lwpid_t tid, register_t trapno); 359 KTR_INFO(KTR_KERNENTRY, kernentry, syscall_ret, 0, "SYSRET(pid %hd, tid %hd, err %d)", 360 pid_t pid, lwpid_t tid, int err); 361 KTR_INFO(KTR_KERNENTRY, kernentry, fork_ret, 0, "FORKRET(pid %hd, tid %hd)", 362 pid_t pid, lwpid_t tid); 363 364 /* 365 * Exception, fault, and trap interface to the kernel. 366 * This common code is called from assembly language IDT gate entry 367 * routines that prepare a suitable stack frame, and restore this 368 * frame after the exception has been processed. 369 * 370 * This function is also called from doreti in an interlock to handle ASTs. 371 * For example: hardwareint->INTROUTINE->(set ast)->doreti->trap 372 * 373 * NOTE! We have to retrieve the fault address prior to obtaining the 374 * MP lock because get_mplock() may switch out. YYY cr2 really ought 375 * to be retrieved by the assembly code, not here. 376 * 377 * XXX gd_trap_nesting_level currently prevents lwkt_switch() from panicing 378 * if an attempt is made to switch from a fast interrupt or IPI. This is 379 * necessary to properly take fatal kernel traps on SMP machines if 380 * get_mplock() has to block. 381 */ 382 383 void 384 user_trap(struct trapframe *frame) 385 { 386 struct globaldata *gd = mycpu; 387 struct thread *td = gd->gd_curthread; 388 struct lwp *lp = td->td_lwp; 389 struct proc *p; 390 int sticks = 0; 391 int i = 0, ucode = 0, type, code; 392 #ifdef SMP 393 int have_mplock = 0; 394 #endif 395 #ifdef INVARIANTS 396 int crit_count = td->td_critcount; 397 lwkt_tokref_t curstop = td->td_toks_stop; 398 #endif 399 vm_offset_t eva; 400 401 p = td->td_proc; 402 403 if (frame->tf_trapno == T_PAGEFLT) 404 eva = frame->tf_addr; 405 else 406 eva = 0; 407 #if 0 408 kprintf("USER_TRAP AT %08lx xflags %ld trapno %ld eva %08lx\n", 409 frame->tf_rip, frame->tf_xflags, frame->tf_trapno, eva); 410 #endif 411 412 /* 413 * Everything coming from user mode runs through user_trap, 414 * including system calls. 415 */ 416 if (frame->tf_trapno == T_FAST_SYSCALL) { 417 syscall2(frame); 418 return; 419 } 420 421 KTR_LOG(kernentry_trap, lp->lwp_proc->p_pid, lp->lwp_tid, 422 frame->tf_trapno, eva); 423 424 #ifdef DDB 425 if (db_active) { 426 eva = (frame->tf_trapno == T_PAGEFLT ? rcr2() : 0); 427 ++gd->gd_trap_nesting_level; 428 MAKEMPSAFE(have_mplock); 429 trap_fatal(frame, TRUE, eva); 430 --gd->gd_trap_nesting_level; 431 goto out2; 432 } 433 #endif 434 435 type = frame->tf_trapno; 436 code = frame->tf_err; 437 438 userenter(td, p); 439 440 sticks = (int)td->td_sticks; 441 lp->lwp_md.md_regs = frame; 442 443 switch (type) { 444 case T_PRIVINFLT: /* privileged instruction fault */ 445 i = SIGILL; 446 ucode = ILL_PRVOPC; 447 break; 448 449 case T_BPTFLT: /* bpt instruction fault */ 450 case T_TRCTRAP: /* trace trap */ 451 frame->tf_rflags &= ~PSL_T; 452 i = SIGTRAP; 453 ucode = (type == T_TRCTRAP ? TRAP_TRACE : TRAP_BRKPT); 454 break; 455 456 case T_ARITHTRAP: /* arithmetic trap */ 457 ucode = code; 458 i = SIGFPE; 459 break; 460 461 case T_ASTFLT: /* Allow process switch */ 462 mycpu->gd_cnt.v_soft++; 463 if (mycpu->gd_reqflags & RQF_AST_OWEUPC) { 464 atomic_clear_int(&mycpu->gd_reqflags, RQF_AST_OWEUPC); 465 addupc_task(p, p->p_prof.pr_addr, p->p_prof.pr_ticks); 466 } 467 goto out; 468 469 /* 470 * The following two traps can happen in 471 * vm86 mode, and, if so, we want to handle 472 * them specially. 473 */ 474 case T_PROTFLT: /* general protection fault */ 475 case T_STKFLT: /* stack fault */ 476 #if 0 477 if (frame->tf_eflags & PSL_VM) { 478 i = vm86_emulate((struct vm86frame *)frame); 479 if (i == 0) 480 goto out; 481 break; 482 } 483 #endif 484 /* FALL THROUGH */ 485 486 case T_SEGNPFLT: /* segment not present fault */ 487 case T_TSSFLT: /* invalid TSS fault */ 488 case T_DOUBLEFLT: /* double fault */ 489 default: 490 i = SIGBUS; 491 ucode = code + BUS_SEGM_FAULT ; 492 break; 493 494 case T_PAGEFLT: /* page fault */ 495 MAKEMPSAFE(have_mplock); 496 i = trap_pfault(frame, TRUE, eva); 497 if (i == -1 || i == 0) 498 goto out; 499 500 501 if (i == SIGSEGV) 502 ucode = SEGV_MAPERR; 503 else { 504 i = SIGSEGV; 505 ucode = SEGV_ACCERR; 506 } 507 break; 508 509 case T_DIVIDE: /* integer divide fault */ 510 ucode = FPE_INTDIV; 511 i = SIGFPE; 512 break; 513 514 #if NISA > 0 515 case T_NMI: 516 MAKEMPSAFE(have_mplock); 517 /* machine/parity/power fail/"kitchen sink" faults */ 518 if (isa_nmi(code) == 0) { 519 #ifdef DDB 520 /* 521 * NMI can be hooked up to a pushbutton 522 * for debugging. 523 */ 524 if (ddb_on_nmi) { 525 kprintf ("NMI ... going to debugger\n"); 526 kdb_trap(type, 0, frame); 527 } 528 #endif /* DDB */ 529 goto out2; 530 } else if (panic_on_nmi) 531 panic("NMI indicates hardware failure"); 532 break; 533 #endif /* NISA > 0 */ 534 535 case T_OFLOW: /* integer overflow fault */ 536 ucode = FPE_INTOVF; 537 i = SIGFPE; 538 break; 539 540 case T_BOUND: /* bounds check fault */ 541 ucode = FPE_FLTSUB; 542 i = SIGFPE; 543 break; 544 545 case T_DNA: 546 /* 547 * Virtual kernel intercept - pass the DNA exception 548 * to the (emulated) virtual kernel if it asked to handle 549 * it. This occurs when the virtual kernel is holding 550 * onto the FP context for a different emulated 551 * process then the one currently running. 552 * 553 * We must still call npxdna() since we may have 554 * saved FP state that the (emulated) virtual kernel 555 * needs to hand over to a different emulated process. 556 */ 557 if (lp->lwp_vkernel && lp->lwp_vkernel->ve && 558 (td->td_pcb->pcb_flags & FP_VIRTFP) 559 ) { 560 npxdna(frame); 561 break; 562 } 563 564 /* 565 * The kernel may have switched out the FP unit's 566 * state, causing the user process to take a fault 567 * when it tries to use the FP unit. Restore the 568 * state here 569 */ 570 if (npxdna(frame)) 571 goto out; 572 if (!pmath_emulate) { 573 i = SIGFPE; 574 ucode = FPE_FPU_NP_TRAP; 575 break; 576 } 577 i = (*pmath_emulate)(frame); 578 if (i == 0) { 579 if (!(frame->tf_rflags & PSL_T)) 580 goto out2; 581 frame->tf_rflags &= ~PSL_T; 582 i = SIGTRAP; 583 } 584 /* else ucode = emulator_only_knows() XXX */ 585 break; 586 587 case T_FPOPFLT: /* FPU operand fetch fault */ 588 ucode = T_FPOPFLT; 589 i = SIGILL; 590 break; 591 592 case T_XMMFLT: /* SIMD floating-point exception */ 593 ucode = 0; /* XXX */ 594 i = SIGFPE; 595 break; 596 } 597 598 /* 599 * Virtual kernel intercept - if the fault is directly related to a 600 * VM context managed by a virtual kernel then let the virtual kernel 601 * handle it. 602 */ 603 if (lp->lwp_vkernel && lp->lwp_vkernel->ve) { 604 vkernel_trap(lp, frame); 605 goto out; 606 } 607 608 /* 609 * Translate fault for emulators (e.g. Linux) 610 */ 611 if (*p->p_sysent->sv_transtrap) 612 i = (*p->p_sysent->sv_transtrap)(i, type); 613 614 MAKEMPSAFE(have_mplock); 615 trapsignal(lp, i, ucode); 616 617 #ifdef DEBUG 618 if (type <= MAX_TRAP_MSG) { 619 uprintf("fatal process exception: %s", 620 trap_msg[type]); 621 if ((type == T_PAGEFLT) || (type == T_PROTFLT)) 622 uprintf(", fault VA = 0x%lx", (u_long)eva); 623 uprintf("\n"); 624 } 625 #endif 626 627 out: 628 userret(lp, frame, sticks); 629 userexit(lp); 630 out2: ; 631 #ifdef SMP 632 if (have_mplock) 633 rel_mplock(); 634 #endif 635 KTR_LOG(kernentry_trap_ret, lp->lwp_proc->p_pid, lp->lwp_tid); 636 #ifdef INVARIANTS 637 KASSERT(crit_count == td->td_critcount, 638 ("trap: critical section count mismatch! %d/%d", 639 crit_count, td->td_pri)); 640 KASSERT(curstop == td->td_toks_stop, 641 ("trap: extra tokens held after trap! %ld/%ld", 642 curstop - &td->td_toks_base, 643 td->td_toks_stop - &td->td_toks_base)); 644 #endif 645 } 646 647 void 648 kern_trap(struct trapframe *frame) 649 { 650 struct globaldata *gd = mycpu; 651 struct thread *td = gd->gd_curthread; 652 struct lwp *lp; 653 struct proc *p; 654 int i = 0, ucode = 0, type, code; 655 #ifdef SMP 656 int have_mplock = 0; 657 #endif 658 #ifdef INVARIANTS 659 int crit_count = td->td_critcount; 660 lwkt_tokref_t curstop = td->td_toks_stop; 661 #endif 662 vm_offset_t eva; 663 664 lp = td->td_lwp; 665 p = td->td_proc; 666 667 if (frame->tf_trapno == T_PAGEFLT) 668 eva = frame->tf_addr; 669 else 670 eva = 0; 671 672 #ifdef DDB 673 if (db_active) { 674 ++gd->gd_trap_nesting_level; 675 MAKEMPSAFE(have_mplock); 676 trap_fatal(frame, FALSE, eva); 677 --gd->gd_trap_nesting_level; 678 goto out2; 679 } 680 #endif 681 682 type = frame->tf_trapno; 683 code = frame->tf_err; 684 685 #if 0 686 kernel_trap: 687 #endif 688 /* kernel trap */ 689 690 switch (type) { 691 case T_PAGEFLT: /* page fault */ 692 MAKEMPSAFE(have_mplock); 693 trap_pfault(frame, FALSE, eva); 694 goto out2; 695 696 case T_DNA: 697 /* 698 * The kernel may be using npx for copying or other 699 * purposes. 700 */ 701 panic("kernel NPX should not happen"); 702 if (npxdna(frame)) 703 goto out2; 704 break; 705 706 case T_PROTFLT: /* general protection fault */ 707 case T_SEGNPFLT: /* segment not present fault */ 708 /* 709 * Invalid segment selectors and out of bounds 710 * %eip's and %esp's can be set up in user mode. 711 * This causes a fault in kernel mode when the 712 * kernel tries to return to user mode. We want 713 * to get this fault so that we can fix the 714 * problem here and not have to check all the 715 * selectors and pointers when the user changes 716 * them. 717 */ 718 if (mycpu->gd_intr_nesting_level == 0) { 719 if (td->td_pcb->pcb_onfault) { 720 frame->tf_rip = 721 (register_t)td->td_pcb->pcb_onfault; 722 goto out2; 723 } 724 } 725 break; 726 727 case T_TSSFLT: 728 /* 729 * PSL_NT can be set in user mode and isn't cleared 730 * automatically when the kernel is entered. This 731 * causes a TSS fault when the kernel attempts to 732 * `iret' because the TSS link is uninitialized. We 733 * want to get this fault so that we can fix the 734 * problem here and not every time the kernel is 735 * entered. 736 */ 737 if (frame->tf_rflags & PSL_NT) { 738 frame->tf_rflags &= ~PSL_NT; 739 goto out2; 740 } 741 break; 742 743 case T_TRCTRAP: /* trace trap */ 744 #if 0 745 if (frame->tf_eip == (int)IDTVEC(syscall)) { 746 /* 747 * We've just entered system mode via the 748 * syscall lcall. Continue single stepping 749 * silently until the syscall handler has 750 * saved the flags. 751 */ 752 goto out2; 753 } 754 if (frame->tf_eip == (int)IDTVEC(syscall) + 1) { 755 /* 756 * The syscall handler has now saved the 757 * flags. Stop single stepping it. 758 */ 759 frame->tf_eflags &= ~PSL_T; 760 goto out2; 761 } 762 #endif 763 #if 0 764 /* 765 * Ignore debug register trace traps due to 766 * accesses in the user's address space, which 767 * can happen under several conditions such as 768 * if a user sets a watchpoint on a buffer and 769 * then passes that buffer to a system call. 770 * We still want to get TRCTRAPS for addresses 771 * in kernel space because that is useful when 772 * debugging the kernel. 773 */ 774 if (user_dbreg_trap()) { 775 /* 776 * Reset breakpoint bits because the 777 * processor doesn't 778 */ 779 load_dr6(rdr6() & 0xfffffff0); 780 goto out2; 781 } 782 #endif 783 /* 784 * Fall through (TRCTRAP kernel mode, kernel address) 785 */ 786 case T_BPTFLT: 787 /* 788 * If DDB is enabled, let it handle the debugger trap. 789 * Otherwise, debugger traps "can't happen". 790 */ 791 #ifdef DDB 792 MAKEMPSAFE(have_mplock); 793 if (kdb_trap (type, 0, frame)) 794 goto out2; 795 #endif 796 break; 797 case T_DIVIDE: 798 MAKEMPSAFE(have_mplock); 799 trap_fatal(frame, FALSE, eva); 800 goto out2; 801 case T_NMI: 802 MAKEMPSAFE(have_mplock); 803 trap_fatal(frame, FALSE, eva); 804 goto out2; 805 case T_SYSCALL80: 806 case T_FAST_SYSCALL: 807 /* 808 * Ignore this trap generated from a spurious SIGTRAP. 809 * 810 * single stepping in / syscalls leads to spurious / SIGTRAP 811 * so ignore 812 * 813 * Haiku (c) 2007 Simon 'corecode' Schubert 814 */ 815 goto out2; 816 } 817 818 /* 819 * Translate fault for emulators (e.g. Linux) 820 */ 821 if (*p->p_sysent->sv_transtrap) 822 i = (*p->p_sysent->sv_transtrap)(i, type); 823 824 MAKEMPSAFE(have_mplock); 825 trapsignal(lp, i, ucode); 826 827 #ifdef DEBUG 828 if (type <= MAX_TRAP_MSG) { 829 uprintf("fatal process exception: %s", 830 trap_msg[type]); 831 if ((type == T_PAGEFLT) || (type == T_PROTFLT)) 832 uprintf(", fault VA = 0x%lx", (u_long)eva); 833 uprintf("\n"); 834 } 835 #endif 836 837 out2: 838 ; 839 #ifdef SMP 840 if (have_mplock) 841 rel_mplock(); 842 #endif 843 #ifdef INVARIANTS 844 KASSERT(crit_count == td->td_critcount, 845 ("trap: critical section count mismatch! %d/%d", 846 crit_count, td->td_pri)); 847 KASSERT(curstop == td->td_toks_stop, 848 ("trap: extra tokens held after trap! %ld/%ld", 849 curstop - &td->td_toks_base, 850 td->td_toks_stop - &td->td_toks_base)); 851 #endif 852 } 853 854 int 855 trap_pfault(struct trapframe *frame, int usermode, vm_offset_t eva) 856 { 857 vm_offset_t va; 858 struct vmspace *vm = NULL; 859 vm_map_t map = 0; 860 int rv = 0; 861 vm_prot_t ftype; 862 thread_t td = curthread; 863 struct lwp *lp = td->td_lwp; 864 int fault_flags; 865 866 va = trunc_page(eva); 867 if (usermode == FALSE) { 868 /* 869 * This is a fault on kernel virtual memory. 870 */ 871 map = &kernel_map; 872 } else { 873 /* 874 * This is a fault on non-kernel virtual memory. 875 * vm is initialized above to NULL. If curproc is NULL 876 * or curproc->p_vmspace is NULL the fault is fatal. 877 */ 878 if (lp != NULL) 879 vm = lp->lwp_vmspace; 880 881 if (vm == NULL) 882 goto nogo; 883 884 map = &vm->vm_map; 885 } 886 887 if (frame->tf_err & PGEX_W) 888 ftype = VM_PROT_READ | VM_PROT_WRITE; 889 else 890 ftype = VM_PROT_READ; 891 892 if (map != &kernel_map) { 893 /* 894 * Keep swapout from messing with us during this 895 * critical time. 896 */ 897 PHOLD(lp->lwp_proc); 898 899 /* 900 * Grow the stack if necessary 901 */ 902 /* grow_stack returns false only if va falls into 903 * a growable stack region and the stack growth 904 * fails. It returns true if va was not within 905 * a growable stack region, or if the stack 906 * growth succeeded. 907 */ 908 if (!grow_stack (lp->lwp_proc, va)) { 909 rv = KERN_FAILURE; 910 PRELE(lp->lwp_proc); 911 goto nogo; 912 } 913 914 fault_flags = 0; 915 if (usermode) 916 fault_flags |= VM_FAULT_BURST; 917 if (ftype & VM_PROT_WRITE) 918 fault_flags |= VM_FAULT_DIRTY; 919 else 920 fault_flags |= VM_FAULT_NORMAL; 921 rv = vm_fault(map, va, ftype, fault_flags); 922 923 PRELE(lp->lwp_proc); 924 } else { 925 /* 926 * Don't have to worry about process locking or stacks in the kernel. 927 */ 928 rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL); 929 } 930 931 if (rv == KERN_SUCCESS) 932 return (0); 933 nogo: 934 if (!usermode) { 935 if (td->td_gd->gd_intr_nesting_level == 0 && 936 td->td_pcb->pcb_onfault) { 937 frame->tf_rip = (register_t)td->td_pcb->pcb_onfault; 938 return (0); 939 } 940 trap_fatal(frame, usermode, eva); 941 return (-1); 942 } 943 944 /* 945 * NOTE: on x86_64 we have a tf_addr field in the trapframe, no 946 * kludge is needed to pass the fault address to signal handlers. 947 */ 948 struct proc *p = td->td_proc; 949 kprintf("seg-fault accessing address %p rip=%p pid=%d p_comm=%s\n", 950 (void *)va, (void *)frame->tf_rip, p->p_pid, p->p_comm); 951 /* Debugger("seg-fault"); */ 952 953 return((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV); 954 } 955 956 static void 957 trap_fatal(struct trapframe *frame, int usermode, vm_offset_t eva) 958 { 959 int code, type, ss; 960 long rsp; 961 962 code = frame->tf_xflags; 963 type = frame->tf_trapno; 964 965 if (type <= MAX_TRAP_MSG) { 966 kprintf("\n\nFatal trap %d: %s while in %s mode\n", 967 type, trap_msg[type], 968 (usermode ? "user" : "kernel")); 969 } 970 #ifdef SMP 971 /* two separate prints in case of a trap on an unmapped page */ 972 kprintf("cpuid = %d\n", mycpu->gd_cpuid); 973 #endif 974 if (type == T_PAGEFLT) { 975 kprintf("fault virtual address = %p\n", (void *)eva); 976 kprintf("fault code = %s %s, %s\n", 977 usermode ? "user" : "supervisor", 978 code & PGEX_W ? "write" : "read", 979 code & PGEX_P ? "protection violation" : "page not present"); 980 } 981 kprintf("instruction pointer = 0x%lx:0x%lx\n", 982 frame->tf_cs & 0xffff, frame->tf_rip); 983 if (usermode) { 984 ss = frame->tf_ss & 0xffff; 985 rsp = frame->tf_rsp; 986 } else { 987 ss = GSEL(GDATA_SEL, SEL_KPL); 988 rsp = (long)&frame->tf_rsp; 989 } 990 kprintf("stack pointer = 0x%x:0x%lx\n", ss, rsp); 991 kprintf("frame pointer = 0x%x:0x%lx\n", ss, frame->tf_rbp); 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 #if 0 1002 if (frame->tf_eflags & PSL_VM) 1003 kprintf("vm86, "); 1004 #endif 1005 kprintf("IOPL = %jd\n", (intmax_t)((frame->tf_rflags & PSL_IOPL) >> 12)); 1006 kprintf("current process = "); 1007 if (curproc) { 1008 kprintf("%lu (%s)\n", 1009 (u_long)curproc->p_pid, curproc->p_comm ? 1010 curproc->p_comm : ""); 1011 } else { 1012 kprintf("Idle\n"); 1013 } 1014 kprintf("current thread = pri %d ", curthread->td_pri); 1015 if (curthread->td_critcount) 1016 kprintf("(CRIT)"); 1017 kprintf("\n"); 1018 #ifdef SMP 1019 /** 1020 * XXX FIXME: 1021 * we probably SHOULD have stopped the other CPUs before now! 1022 * another CPU COULD have been touching cpl at this moment... 1023 */ 1024 kprintf(" <- SMP: XXX"); 1025 #endif 1026 kprintf("\n"); 1027 1028 #ifdef KDB 1029 if (kdb_trap(&psl)) 1030 return; 1031 #endif 1032 #ifdef DDB 1033 if ((debugger_on_panic || db_active) && kdb_trap(type, code, frame)) 1034 return; 1035 #endif 1036 kprintf("trap number = %d\n", type); 1037 if (type <= MAX_TRAP_MSG) 1038 panic("%s", trap_msg[type]); 1039 else 1040 panic("unknown/reserved trap"); 1041 } 1042 1043 /* 1044 * Double fault handler. Called when a fault occurs while writing 1045 * a frame for a trap/exception onto the stack. This usually occurs 1046 * when the stack overflows (such is the case with infinite recursion, 1047 * for example). 1048 * 1049 * XXX Note that the current PTD gets replaced by IdlePTD when the 1050 * task switch occurs. This means that the stack that was active at 1051 * the time of the double fault is not available at <kstack> unless 1052 * the machine was idle when the double fault occurred. The downside 1053 * of this is that "trace <ebp>" in ddb won't work. 1054 */ 1055 void 1056 dblfault_handler(void) 1057 { 1058 #if JG 1059 struct mdglobaldata *gd = mdcpu; 1060 #endif 1061 1062 kprintf("\nFatal double fault:\n"); 1063 #if JG 1064 kprintf("rip = 0x%lx\n", gd->gd_common_tss.tss_rip); 1065 kprintf("rsp = 0x%lx\n", gd->gd_common_tss.tss_rsp); 1066 kprintf("rbp = 0x%lx\n", gd->gd_common_tss.tss_rbp); 1067 #endif 1068 #ifdef SMP 1069 /* two separate prints in case of a trap on an unmapped page */ 1070 kprintf("cpuid = %d\n", mycpu->gd_cpuid); 1071 #endif 1072 panic("double fault"); 1073 } 1074 1075 /* 1076 * Compensate for 386 brain damage (missing URKR). 1077 * This is a little simpler than the pagefault handler in trap() because 1078 * it the page tables have already been faulted in and high addresses 1079 * are thrown out early for other reasons. 1080 */ 1081 int 1082 trapwrite(unsigned addr) 1083 { 1084 struct lwp *lp; 1085 vm_offset_t va; 1086 struct vmspace *vm; 1087 int rv; 1088 1089 va = trunc_page((vm_offset_t)addr); 1090 /* 1091 * XXX - MAX is END. Changed > to >= for temp. fix. 1092 */ 1093 if (va >= VM_MAX_USER_ADDRESS) 1094 return (1); 1095 1096 lp = curthread->td_lwp; 1097 vm = lp->lwp_vmspace; 1098 1099 PHOLD(lp->lwp_proc); 1100 1101 if (!grow_stack (lp->lwp_proc, va)) { 1102 PRELE(lp->lwp_proc); 1103 return (1); 1104 } 1105 1106 /* 1107 * fault the data page 1108 */ 1109 rv = vm_fault(&vm->vm_map, va, VM_PROT_WRITE, VM_FAULT_DIRTY); 1110 1111 PRELE(lp->lwp_proc); 1112 1113 if (rv != KERN_SUCCESS) 1114 return 1; 1115 1116 return (0); 1117 } 1118 1119 /* 1120 * syscall2 - MP aware system call request C handler 1121 * 1122 * A system call is essentially treated as a trap except that the 1123 * MP lock is not held on entry or return. We are responsible for 1124 * obtaining the MP lock if necessary and for handling ASTs 1125 * (e.g. a task switch) prior to return. 1126 * 1127 * In general, only simple access and manipulation of curproc and 1128 * the current stack is allowed without having to hold MP lock. 1129 * 1130 * MPSAFE - note that large sections of this routine are run without 1131 * the MP lock. 1132 */ 1133 void 1134 syscall2(struct trapframe *frame) 1135 { 1136 struct thread *td = curthread; 1137 struct proc *p = td->td_proc; 1138 struct lwp *lp = td->td_lwp; 1139 caddr_t params; 1140 struct sysent *callp; 1141 register_t orig_tf_rflags; 1142 int sticks; 1143 int error; 1144 int narg; 1145 #ifdef INVARIANTS 1146 int crit_count = td->td_critcount; 1147 lwkt_tokref_t curstop = td->td_toks_stop; 1148 #endif 1149 #ifdef SMP 1150 int have_mplock = 0; 1151 #endif 1152 register_t *argp; 1153 u_int code; 1154 int reg, regcnt; 1155 union sysunion args; 1156 register_t *argsdst; 1157 1158 mycpu->gd_cnt.v_syscall++; 1159 1160 KTR_LOG(kernentry_syscall, lp->lwp_proc->p_pid, lp->lwp_tid, 1161 frame->tf_rax); 1162 1163 userenter(td, p); /* lazy raise our priority */ 1164 1165 reg = 0; 1166 regcnt = 6; 1167 /* 1168 * Misc 1169 */ 1170 sticks = (int)td->td_sticks; 1171 orig_tf_rflags = frame->tf_rflags; 1172 1173 /* 1174 * Virtual kernel intercept - if a VM context managed by a virtual 1175 * kernel issues a system call the virtual kernel handles it, not us. 1176 * Restore the virtual kernel context and return from its system 1177 * call. The current frame is copied out to the virtual kernel. 1178 */ 1179 if (lp->lwp_vkernel && lp->lwp_vkernel->ve) { 1180 vkernel_trap(lp, frame); 1181 error = EJUSTRETURN; 1182 goto out; 1183 } 1184 1185 /* 1186 * Get the system call parameters and account for time 1187 */ 1188 lp->lwp_md.md_regs = frame; 1189 params = (caddr_t)frame->tf_rsp + sizeof(register_t); 1190 code = frame->tf_rax; 1191 1192 if (p->p_sysent->sv_prepsyscall) { 1193 (*p->p_sysent->sv_prepsyscall)( 1194 frame, (int *)(&args.nosys.sysmsg + 1), 1195 &code, ¶ms); 1196 } else { 1197 if (code == SYS_syscall || code == SYS___syscall) { 1198 code = frame->tf_rdi; 1199 reg++; 1200 regcnt--; 1201 } 1202 } 1203 1204 if (p->p_sysent->sv_mask) 1205 code &= p->p_sysent->sv_mask; 1206 1207 if (code >= p->p_sysent->sv_size) 1208 callp = &p->p_sysent->sv_table[0]; 1209 else 1210 callp = &p->p_sysent->sv_table[code]; 1211 1212 narg = callp->sy_narg & SYF_ARGMASK; 1213 1214 /* 1215 * On x86_64 we get up to six arguments in registers. The rest are 1216 * on the stack. The first six members of 'struct trapframe' happen 1217 * to be the registers used to pass arguments, in exactly the right 1218 * order. 1219 */ 1220 argp = &frame->tf_rdi; 1221 argp += reg; 1222 argsdst = (register_t *)(&args.nosys.sysmsg + 1); 1223 /* 1224 * JG can we overflow the space pointed to by 'argsdst' 1225 * either with 'bcopy' or with 'copyin'? 1226 */ 1227 bcopy(argp, argsdst, sizeof(register_t) * regcnt); 1228 /* 1229 * copyin is MP aware, but the tracing code is not 1230 */ 1231 if (narg > regcnt) { 1232 KASSERT(params != NULL, ("copyin args with no params!")); 1233 error = copyin(params, &argsdst[regcnt], 1234 (narg - regcnt) * sizeof(register_t)); 1235 if (error) { 1236 #ifdef KTRACE 1237 if (KTRPOINT(td, KTR_SYSCALL)) { 1238 MAKEMPSAFE(have_mplock); 1239 1240 ktrsyscall(lp, code, narg, 1241 (void *)(&args.nosys.sysmsg + 1)); 1242 } 1243 #endif 1244 goto bad; 1245 } 1246 } 1247 1248 #ifdef KTRACE 1249 if (KTRPOINT(td, KTR_SYSCALL)) { 1250 MAKEMPSAFE(have_mplock); 1251 ktrsyscall(lp, code, narg, (void *)(&args.nosys.sysmsg + 1)); 1252 } 1253 #endif 1254 1255 /* 1256 * Default return value is 0 (will be copied to %rax). Double-value 1257 * returns use %rax and %rdx. %rdx is left unchanged for system 1258 * calls which return only one result. 1259 */ 1260 args.sysmsg_fds[0] = 0; 1261 args.sysmsg_fds[1] = frame->tf_rdx; 1262 1263 /* 1264 * The syscall might manipulate the trap frame. If it does it 1265 * will probably return EJUSTRETURN. 1266 */ 1267 args.sysmsg_frame = frame; 1268 1269 STOPEVENT(p, S_SCE, narg); /* MP aware */ 1270 1271 /* 1272 * NOTE: All system calls run MPSAFE now. The system call itself 1273 * is responsible for getting the MP lock. 1274 */ 1275 error = (*callp->sy_call)(&args); 1276 1277 #if 0 1278 kprintf("system call %d returned %d\n", code, error); 1279 #endif 1280 1281 out: 1282 /* 1283 * MP SAFE (we may or may not have the MP lock at this point) 1284 */ 1285 switch (error) { 1286 case 0: 1287 /* 1288 * Reinitialize proc pointer `p' as it may be different 1289 * if this is a child returning from fork syscall. 1290 */ 1291 p = curproc; 1292 lp = curthread->td_lwp; 1293 frame->tf_rax = args.sysmsg_fds[0]; 1294 frame->tf_rdx = args.sysmsg_fds[1]; 1295 frame->tf_rflags &= ~PSL_C; 1296 break; 1297 case ERESTART: 1298 /* 1299 * Reconstruct pc, we know that 'syscall' is 2 bytes. 1300 * We have to do a full context restore so that %r10 1301 * (which was holding the value of %rcx) is restored for 1302 * the next iteration. 1303 */ 1304 frame->tf_rip -= frame->tf_err; 1305 frame->tf_r10 = frame->tf_rcx; 1306 break; 1307 case EJUSTRETURN: 1308 break; 1309 case EASYNC: 1310 panic("Unexpected EASYNC return value (for now)"); 1311 default: 1312 bad: 1313 if (p->p_sysent->sv_errsize) { 1314 if (error >= p->p_sysent->sv_errsize) 1315 error = -1; /* XXX */ 1316 else 1317 error = p->p_sysent->sv_errtbl[error]; 1318 } 1319 frame->tf_rax = error; 1320 frame->tf_rflags |= PSL_C; 1321 break; 1322 } 1323 1324 /* 1325 * Traced syscall. trapsignal() is not MP aware. 1326 */ 1327 if (orig_tf_rflags & PSL_T) { 1328 MAKEMPSAFE(have_mplock); 1329 frame->tf_rflags &= ~PSL_T; 1330 trapsignal(lp, SIGTRAP, 0); 1331 } 1332 1333 /* 1334 * Handle reschedule and other end-of-syscall issues 1335 */ 1336 userret(lp, frame, sticks); 1337 1338 #ifdef KTRACE 1339 if (KTRPOINT(td, KTR_SYSRET)) { 1340 MAKEMPSAFE(have_mplock); 1341 ktrsysret(lp, code, error, args.sysmsg_result); 1342 } 1343 #endif 1344 1345 /* 1346 * This works because errno is findable through the 1347 * register set. If we ever support an emulation where this 1348 * is not the case, this code will need to be revisited. 1349 */ 1350 STOPEVENT(p, S_SCX, code); 1351 1352 userexit(lp); 1353 #ifdef SMP 1354 /* 1355 * Release the MP lock if we had to get it 1356 */ 1357 if (have_mplock) 1358 rel_mplock(); 1359 #endif 1360 KTR_LOG(kernentry_syscall_ret, lp->lwp_proc->p_pid, lp->lwp_tid, error); 1361 #ifdef INVARIANTS 1362 KASSERT(&td->td_toks_base == td->td_toks_stop, 1363 ("syscall: critical section count mismatch! %d/%d", 1364 crit_count, td->td_pri)); 1365 KASSERT(curstop == td->td_toks_stop, 1366 ("syscall: extra tokens held after trap! %ld", 1367 td->td_toks_stop - &td->td_toks_base)); 1368 #endif 1369 } 1370 1371 /* 1372 * NOTE: mplock not held at any point 1373 */ 1374 void 1375 fork_return(struct lwp *lp, struct trapframe *frame) 1376 { 1377 frame->tf_rax = 0; /* Child returns zero */ 1378 frame->tf_rflags &= ~PSL_C; /* success */ 1379 frame->tf_rdx = 1; 1380 1381 generic_lwp_return(lp, frame); 1382 KTR_LOG(kernentry_fork_ret, lp->lwp_proc->p_pid, lp->lwp_tid); 1383 } 1384 1385 /* 1386 * Simplified back end of syscall(), used when returning from fork() 1387 * directly into user mode. 1388 * 1389 * This code will return back into the fork trampoline code which then 1390 * runs doreti. 1391 * 1392 * NOTE: The mplock is not held at any point. 1393 */ 1394 void 1395 generic_lwp_return(struct lwp *lp, struct trapframe *frame) 1396 { 1397 struct proc *p = lp->lwp_proc; 1398 1399 /* 1400 * Newly forked processes are given a kernel priority. We have to 1401 * adjust the priority to a normal user priority and fake entry 1402 * into the kernel (call userenter()) to install a passive release 1403 * function just in case userret() decides to stop the process. This 1404 * can occur when ^Z races a fork. If we do not install the passive 1405 * release function the current process designation will not be 1406 * released when the thread goes to sleep. 1407 */ 1408 lwkt_setpri_self(TDPRI_USER_NORM); 1409 userenter(lp->lwp_thread, p); 1410 userret(lp, frame, 0); 1411 #ifdef KTRACE 1412 if (KTRPOINT(lp->lwp_thread, KTR_SYSRET)) 1413 ktrsysret(lp, SYS_fork, 0, 0); 1414 #endif 1415 lp->lwp_flags |= LWP_PASSIVE_ACQ; 1416 userexit(lp); 1417 lp->lwp_flags &= ~LWP_PASSIVE_ACQ; 1418 } 1419 1420 /* 1421 * doreti has turned into this. The frame is directly on the stack. We 1422 * pull everything else we need (fpu and tls context) from the current 1423 * thread. 1424 * 1425 * Note on fpu interactions: In a virtual kernel, the fpu context for 1426 * an emulated user mode process is not shared with the virtual kernel's 1427 * fpu context, so we only have to 'stack' fpu contexts within the virtual 1428 * kernel itself, and not even then since the signal() contexts that we care 1429 * about save and restore the FPU state (I think anyhow). 1430 * 1431 * vmspace_ctl() returns an error only if it had problems instaling the 1432 * context we supplied or problems copying data to/from our VM space. 1433 */ 1434 void 1435 go_user(struct intrframe *frame) 1436 { 1437 struct trapframe *tf = (void *)&frame->if_rdi; 1438 int r; 1439 1440 /* 1441 * Interrupts may be disabled on entry, make sure all signals 1442 * can be received before beginning our loop. 1443 */ 1444 sigsetmask(0); 1445 1446 /* 1447 * Switch to the current simulated user process, then call 1448 * user_trap() when we break out of it (usually due to a signal). 1449 */ 1450 for (;;) { 1451 /* 1452 * Tell the real kernel whether it is ok to use the FP 1453 * unit or not. 1454 */ 1455 if (mdcpu->gd_npxthread == curthread) { 1456 tf->tf_xflags &= ~PGEX_FPFAULT; 1457 } else { 1458 tf->tf_xflags |= PGEX_FPFAULT; 1459 } 1460 1461 /* 1462 * Run emulated user process context. This call interlocks 1463 * with new mailbox signals. 1464 * 1465 * Set PGEX_U unconditionally, indicating a user frame (the 1466 * bit is normally set only by T_PAGEFLT). 1467 */ 1468 r = vmspace_ctl(&curproc->p_vmspace->vm_pmap, VMSPACE_CTL_RUN, 1469 tf, &curthread->td_savevext); 1470 frame->if_xflags |= PGEX_U; 1471 #if 0 1472 kprintf("GO USER %d trap %ld EVA %08lx RIP %08lx RSP %08lx XFLAGS %02lx/%02lx\n", 1473 r, tf->tf_trapno, tf->tf_addr, tf->tf_rip, tf->tf_rsp, 1474 tf->tf_xflags, frame->if_xflags); 1475 #endif 1476 if (r < 0) { 1477 if (errno != EINTR) 1478 panic("vmspace_ctl failed error %d", errno); 1479 } else { 1480 if (tf->tf_trapno) { 1481 user_trap(tf); 1482 } 1483 } 1484 if (mycpu->gd_reqflags & RQF_AST_MASK) { 1485 tf->tf_trapno = T_ASTFLT; 1486 user_trap(tf); 1487 } 1488 tf->tf_trapno = 0; 1489 } 1490 } 1491 1492 /* 1493 * If PGEX_FPFAULT is set then set FP_VIRTFP in the PCB to force a T_DNA 1494 * fault (which is then passed back to the virtual kernel) if an attempt is 1495 * made to use the FP unit. 1496 * 1497 * XXX this is a fairly big hack. 1498 */ 1499 void 1500 set_vkernel_fp(struct trapframe *frame) 1501 { 1502 struct thread *td = curthread; 1503 1504 if (frame->tf_xflags & PGEX_FPFAULT) { 1505 td->td_pcb->pcb_flags |= FP_VIRTFP; 1506 if (mdcpu->gd_npxthread == td) 1507 npxexit(); 1508 } else { 1509 td->td_pcb->pcb_flags &= ~FP_VIRTFP; 1510 } 1511 } 1512 1513 /* 1514 * Called from vkernel_trap() to fixup the vkernel's syscall 1515 * frame for vmspace_ctl() return. 1516 */ 1517 void 1518 cpu_vkernel_trap(struct trapframe *frame, int error) 1519 { 1520 frame->tf_rax = error; 1521 if (error) 1522 frame->tf_rflags |= PSL_C; 1523 else 1524 frame->tf_rflags &= ~PSL_C; 1525 } 1526