1 /*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * Copyright (C) 1994, David Greenman 5 * Copyright (c) 2008-2018 The DragonFly Project. 6 * Copyright (c) 2008 Jordan Gordeev. 7 * 8 * This code is derived from software contributed to Berkeley by 9 * the University of Utah, and William Jolitz. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the University of 22 * California, Berkeley and its contributors. 23 * 4. Neither the name of the University nor the names of its contributors 24 * may be used to endorse or promote products derived from this software 25 * without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37 * SUCH DAMAGE. 38 * 39 * from: @(#)trap.c 7.4 (Berkeley) 5/13/91 40 * $FreeBSD: src/sys/i386/i386/trap.c,v 1.147.2.11 2003/02/27 19:09:59 luoqi Exp $ 41 */ 42 43 /* 44 * x86_64 Trap and System call handling 45 */ 46 47 #include "use_isa.h" 48 49 #include "opt_ddb.h" 50 #include "opt_ktrace.h" 51 52 #include <machine/frame.h> 53 #include <sys/param.h> 54 #include <sys/systm.h> 55 #include <sys/kernel.h> 56 #include <sys/kerneldump.h> 57 #include <sys/proc.h> 58 #include <sys/pioctl.h> 59 #include <sys/types.h> 60 #include <sys/signal2.h> 61 #include <sys/syscall.h> 62 #include <sys/sysctl.h> 63 #include <sys/sysent.h> 64 #ifdef KTRACE 65 #include <sys/ktrace.h> 66 #endif 67 #include <sys/ktr.h> 68 #include <sys/sysmsg.h> 69 #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 /* 93 * These %rip's are used to detect a historical CPU artifact on syscall or 94 * int $3 entry, if not shortcutted in exception.S via 95 * DIRECT_DISALLOW_SS_CPUBUG. 96 */ 97 extern void Xbpt(void); 98 extern void Xfast_syscall(void); 99 #define IDTVEC(vec) X##vec 100 101 extern void trap(struct trapframe *frame); 102 103 static int trap_pfault(struct trapframe *, int); 104 static void trap_fatal(struct trapframe *, vm_offset_t); 105 void dblfault_handler(struct trapframe *frame); 106 107 #define MAX_TRAP_MSG 30 108 static char *trap_msg[] = { 109 "", /* 0 unused */ 110 "privileged instruction fault", /* 1 T_PRIVINFLT */ 111 "", /* 2 unused */ 112 "breakpoint instruction fault", /* 3 T_BPTFLT */ 113 "", /* 4 unused */ 114 "", /* 5 unused */ 115 "arithmetic trap", /* 6 T_ARITHTRAP */ 116 "system forced exception", /* 7 T_ASTFLT */ 117 "", /* 8 unused */ 118 "general protection fault", /* 9 T_PROTFLT */ 119 "trace trap", /* 10 T_TRCTRAP */ 120 "", /* 11 unused */ 121 "page fault", /* 12 T_PAGEFLT */ 122 "", /* 13 unused */ 123 "alignment fault", /* 14 T_ALIGNFLT */ 124 "", /* 15 unused */ 125 "", /* 16 unused */ 126 "", /* 17 unused */ 127 "integer divide fault", /* 18 T_DIVIDE */ 128 "non-maskable interrupt trap", /* 19 T_NMI */ 129 "overflow trap", /* 20 T_OFLOW */ 130 "FPU bounds check fault", /* 21 T_BOUND */ 131 "FPU device not available", /* 22 T_DNA */ 132 "double fault", /* 23 T_DOUBLEFLT */ 133 "FPU operand fetch fault", /* 24 T_FPOPFLT */ 134 "invalid TSS fault", /* 25 T_TSSFLT */ 135 "segment not present fault", /* 26 T_SEGNPFLT */ 136 "stack fault", /* 27 T_STKFLT */ 137 "machine check trap", /* 28 T_MCHK */ 138 "SIMD floating-point exception", /* 29 T_XMMFLT */ 139 "reserved (unknown) fault", /* 30 T_RESERVED */ 140 }; 141 142 #ifdef DDB 143 static int ddb_on_nmi = 1; 144 SYSCTL_INT(_machdep, OID_AUTO, ddb_on_nmi, CTLFLAG_RW, 145 &ddb_on_nmi, 0, "Go to DDB on NMI"); 146 static int ddb_on_seg_fault = 0; 147 SYSCTL_INT(_machdep, OID_AUTO, ddb_on_seg_fault, CTLFLAG_RW, 148 &ddb_on_seg_fault, 0, "Go to DDB on user seg-fault"); 149 static int freeze_on_seg_fault = 0; 150 SYSCTL_INT(_machdep, OID_AUTO, freeze_on_seg_fault, CTLFLAG_RW, 151 &freeze_on_seg_fault, 0, "Go to DDB on user seg-fault"); 152 #endif 153 static int panic_on_nmi = 1; 154 SYSCTL_INT(_machdep, OID_AUTO, panic_on_nmi, CTLFLAG_RW, 155 &panic_on_nmi, 0, "Panic on NMI"); 156 static int fast_release; 157 SYSCTL_INT(_machdep, OID_AUTO, fast_release, CTLFLAG_RW, 158 &fast_release, 0, "Passive Release was optimal"); 159 static int slow_release; 160 SYSCTL_INT(_machdep, OID_AUTO, slow_release, CTLFLAG_RW, 161 &slow_release, 0, "Passive Release was nonoptimal"); 162 163 /* 164 * System call debugging records the worst-case system call 165 * overhead (inclusive of blocking), but may be inaccurate. 166 */ 167 /*#define SYSCALL_DEBUG*/ 168 #ifdef SYSCALL_DEBUG 169 uint64_t SysCallsWorstCase[SYS_MAXSYSCALL]; 170 #endif 171 172 /* 173 * Passively intercepts the thread switch function to increase 174 * the thread priority from a user priority to a kernel priority, reducing 175 * syscall and trap overhead for the case where no switch occurs. 176 * 177 * Synchronizes td_ucred with p_ucred. This is used by system calls, 178 * signal handling, faults, AST traps, and anything else that enters the 179 * kernel from userland and provides the kernel with a stable read-only 180 * copy of the process ucred. 181 * 182 * To avoid races with another thread updating p_ucred we obtain p_spin. 183 * The other thread doing the update will obtain both p_token and p_spin. 184 * In the case where the cached cred pointer matches, we will already have 185 * the ref and we don't have to do one blessed thing. 186 */ 187 static __inline void 188 userenter(struct thread *curtd, struct proc *curp) 189 { 190 struct ucred *ocred; 191 struct ucred *ncred; 192 193 curtd->td_release = lwkt_passive_release; 194 195 if (curtd->td_ucred != curp->p_ucred) { 196 spin_lock(&curp->p_spin); 197 ncred = crhold(curp->p_ucred); 198 spin_unlock(&curp->p_spin); 199 ocred = curtd->td_ucred; 200 curtd->td_ucred = ncred; 201 if (ocred) 202 crfree(ocred); 203 } 204 205 #ifdef DDB 206 /* 207 * Debugging, remove top two user stack pages to catch kernel faults 208 */ 209 if (freeze_on_seg_fault > 1 && curtd->td_lwp) { 210 pmap_remove(vmspace_pmap(curtd->td_lwp->lwp_vmspace), 211 0x00007FFFFFFFD000LU, 212 0x0000800000000000LU); 213 } 214 #endif 215 } 216 217 /* 218 * Handle signals, upcalls, profiling, and other AST's and/or tasks that 219 * must be completed before we can return to or try to return to userland. 220 * 221 * Note that td_sticks is a 64 bit quantity, but there's no point doing 64 222 * arithmatic on the delta calculation so the absolute tick values are 223 * truncated to an integer. 224 */ 225 static void 226 userret(struct lwp *lp, struct trapframe *frame, int sticks) 227 { 228 struct proc *p = lp->lwp_proc; 229 int sig; 230 int ptok; 231 232 /* 233 * Charge system time if profiling. Note: times are in microseconds. 234 * This may do a copyout and block, so do it first even though it 235 * means some system time will be charged as user time. 236 */ 237 if (p->p_flags & P_PROFIL) { 238 addupc_task(p, frame->tf_rip, 239 (u_int)((int)lp->lwp_thread->td_sticks - sticks)); 240 } 241 242 recheck: 243 /* 244 * Specific on-return-to-usermode checks (LWP_MP_WEXIT, 245 * LWP_MP_VNLRU, etc). 246 */ 247 if (lp->lwp_mpflags & LWP_MP_URETMASK) 248 lwpuserret(lp); 249 250 /* 251 * Block here if we are in a stopped state. 252 */ 253 if (STOPLWP(p, lp)) { 254 lwkt_gettoken(&p->p_token); 255 tstop(); 256 lwkt_reltoken(&p->p_token); 257 goto recheck; 258 } 259 while (dump_stop_usertds) { 260 tsleep(&dump_stop_usertds, 0, "dumpstp", 0); 261 } 262 263 /* 264 * Post any pending upcalls. If running a virtual kernel be sure 265 * to restore the virtual kernel's vmspace before posting the upcall. 266 */ 267 if (p->p_flags & (P_SIGVTALRM | P_SIGPROF)) { 268 lwkt_gettoken(&p->p_token); 269 if (p->p_flags & P_SIGVTALRM) { 270 p->p_flags &= ~P_SIGVTALRM; 271 ksignal(p, SIGVTALRM); 272 } 273 if (p->p_flags & P_SIGPROF) { 274 p->p_flags &= ~P_SIGPROF; 275 ksignal(p, SIGPROF); 276 } 277 lwkt_reltoken(&p->p_token); 278 goto recheck; 279 } 280 281 /* 282 * Post any pending signals. If running a virtual kernel be sure 283 * to restore the virtual kernel's vmspace before posting the signal. 284 * 285 * WARNING! postsig() can exit and not return. 286 */ 287 if ((sig = CURSIG_LCK_TRACE(lp, &ptok)) != 0) { 288 postsig(sig, ptok); 289 goto recheck; 290 } 291 292 /* 293 * block here if we are swapped out, but still process signals 294 * (such as SIGKILL). proc0 (the swapin scheduler) is already 295 * aware of our situation, we do not have to wake it up. 296 */ 297 if (p->p_flags & P_SWAPPEDOUT) { 298 lwkt_gettoken(&p->p_token); 299 p->p_flags |= P_SWAPWAIT; 300 swapin_request(); 301 if (p->p_flags & P_SWAPWAIT) 302 tsleep(p, PCATCH, "SWOUT", 0); 303 p->p_flags &= ~P_SWAPWAIT; 304 lwkt_reltoken(&p->p_token); 305 goto recheck; 306 } 307 308 /* 309 * In a multi-threaded program it is possible for a thread to change 310 * signal state during a system call which temporarily changes the 311 * signal mask. In this case postsig() might not be run and we 312 * have to restore the mask ourselves. 313 */ 314 if (lp->lwp_flags & LWP_OLDMASK) { 315 lp->lwp_flags &= ~LWP_OLDMASK; 316 lp->lwp_sigmask = lp->lwp_oldsigmask; 317 goto recheck; 318 } 319 } 320 321 /* 322 * Cleanup from userenter and any passive release that might have occured. 323 * We must reclaim the current-process designation before we can return 324 * to usermode. We also handle both LWKT and USER reschedule requests. 325 */ 326 static __inline void 327 userexit(struct lwp *lp) 328 { 329 struct thread *td = lp->lwp_thread; 330 /* globaldata_t gd = td->td_gd; */ 331 332 /* 333 * Handle stop requests at kernel priority. Any requests queued 334 * after this loop will generate another AST. 335 */ 336 while (STOPLWP(lp->lwp_proc, lp)) { 337 lwkt_gettoken(&lp->lwp_proc->p_token); 338 tstop(); 339 lwkt_reltoken(&lp->lwp_proc->p_token); 340 } 341 342 /* 343 * Reduce our priority in preparation for a return to userland. If 344 * our passive release function was still in place, our priority was 345 * never raised and does not need to be reduced. 346 */ 347 lwkt_passive_recover(td); 348 349 /* WARNING: we may have migrated cpu's */ 350 /* gd = td->td_gd; */ 351 352 /* 353 * Become the current user scheduled process if we aren't already, 354 * and deal with reschedule requests and other factors. 355 */ 356 lp->lwp_proc->p_usched->acquire_curproc(lp); 357 } 358 359 /* 360 * A page fault on a userspace address is classified as SMAP-induced 361 * if: 362 * - SMAP is supported 363 * - kernel mode accessed present data page 364 * - rflags.AC was cleared 365 */ 366 static int 367 trap_is_smap(struct trapframe *frame) 368 { 369 if ((cpu_stdext_feature & CPUID_STDEXT_SMAP) != 0 && 370 (frame->tf_err & (PGEX_P | PGEX_U | PGEX_I | PGEX_RSV)) == PGEX_P && 371 (frame->tf_rflags & PSL_AC) == 0) { 372 return 1; 373 } else { 374 return 0; 375 } 376 } 377 378 #if !defined(KTR_KERNENTRY) 379 #define KTR_KERNENTRY KTR_ALL 380 #endif 381 KTR_INFO_MASTER(kernentry); 382 KTR_INFO(KTR_KERNENTRY, kernentry, trap, 0, 383 "TRAP(pid %d, tid %d, trapno %ld, eva %lu)", 384 pid_t pid, lwpid_t tid, register_t trapno, vm_offset_t eva); 385 KTR_INFO(KTR_KERNENTRY, kernentry, trap_ret, 0, "TRAP_RET(pid %d, tid %d)", 386 pid_t pid, lwpid_t tid); 387 KTR_INFO(KTR_KERNENTRY, kernentry, syscall, 0, "SYSC(pid %d, tid %d, nr %ld)", 388 pid_t pid, lwpid_t tid, register_t trapno); 389 KTR_INFO(KTR_KERNENTRY, kernentry, syscall_ret, 0, "SYSRET(pid %d, tid %d, err %d)", 390 pid_t pid, lwpid_t tid, int err); 391 KTR_INFO(KTR_KERNENTRY, kernentry, fork_ret, 0, "FORKRET(pid %d, tid %d)", 392 pid_t pid, lwpid_t tid); 393 394 /* 395 * Exception, fault, and trap interface to the kernel. 396 * This common code is called from assembly language IDT gate entry 397 * routines that prepare a suitable stack frame, and restore this 398 * frame after the exception has been processed. 399 * 400 * This function is also called from doreti in an interlock to handle ASTs. 401 * For example: hardwareint->INTROUTINE->(set ast)->doreti->trap 402 * 403 * NOTE! We have to retrieve the fault address prior to potentially 404 * blocking, including blocking on any token. 405 * 406 * NOTE! NMI and kernel DBG traps remain on their respective pcpu IST 407 * stacks if taken from a kernel RPL. trap() cannot block in this 408 * situation. DDB entry or a direct report-and-return is ok. 409 * 410 * XXX gd_trap_nesting_level currently prevents lwkt_switch() from panicing 411 * if an attempt is made to switch from a fast interrupt or IPI. 412 */ 413 void 414 trap(struct trapframe *frame) 415 { 416 static struct krate sscpubugrate = { 1 }; 417 struct globaldata *gd = mycpu; 418 struct thread *td = gd->gd_curthread; 419 struct lwp *lp = td->td_lwp; 420 struct proc *p; 421 int sticks = 0; 422 int i = 0, ucode = 0, type, code; 423 #ifdef INVARIANTS 424 int crit_count = td->td_critcount; 425 lwkt_tokref_t curstop = td->td_toks_stop; 426 #endif 427 vm_offset_t eva; 428 429 p = td->td_proc; 430 clear_quickret(); 431 432 #ifdef DDB 433 /* 434 * We need to allow T_DNA faults when the debugger is active since 435 * some dumping paths do large bcopy() which use the floating 436 * point registers for faster copying. 437 */ 438 if (db_active && frame->tf_trapno != T_DNA) { 439 eva = (frame->tf_trapno == T_PAGEFLT ? frame->tf_addr : 0); 440 ++gd->gd_trap_nesting_level; 441 trap_fatal(frame, eva); 442 --gd->gd_trap_nesting_level; 443 goto out2; 444 } 445 #endif 446 447 eva = 0; 448 449 if ((frame->tf_rflags & PSL_I) == 0) { 450 /* 451 * Buggy application or kernel code has disabled interrupts 452 * and then trapped. Enabling interrupts now is wrong, but 453 * it is better than running with interrupts disabled until 454 * they are accidentally enabled later. 455 */ 456 457 type = frame->tf_trapno; 458 if (ISPL(frame->tf_cs) == SEL_UPL) { 459 /* JG curproc can be NULL */ 460 kprintf( 461 "pid %ld (%s): trap %d with interrupts disabled\n", 462 (long)curproc->p_pid, curproc->p_comm, type); 463 } else if ((type == T_STKFLT || type == T_PROTFLT || 464 type == T_SEGNPFLT) && 465 frame->tf_rip == (long)doreti_iret) { 466 /* 467 * iretq fault from kernel mode during return to 468 * userland. 469 * 470 * This situation is expected, don't complain. 471 */ 472 } else if (type != T_NMI && type != T_BPTFLT && 473 type != T_TRCTRAP) { 474 /* 475 * XXX not quite right, since this may be for a 476 * multiple fault in user mode. 477 */ 478 kprintf("kernel trap %d (%s @ 0x%016jx) with " 479 "interrupts disabled\n", 480 type, 481 td->td_comm, 482 frame->tf_rip); 483 } 484 cpu_enable_intr(); 485 } 486 487 type = frame->tf_trapno; 488 code = frame->tf_err; 489 490 if (ISPL(frame->tf_cs) == SEL_UPL) { 491 /* user trap */ 492 493 KTR_LOG(kernentry_trap, p->p_pid, lp->lwp_tid, 494 frame->tf_trapno, eva); 495 496 userenter(td, p); 497 498 sticks = (int)td->td_sticks; 499 KASSERT(lp->lwp_md.md_regs == frame, 500 ("Frame mismatch %p %p", lp->lwp_md.md_regs, frame)); 501 502 switch (type) { 503 case T_PRIVINFLT: /* privileged instruction fault */ 504 i = SIGILL; 505 ucode = ILL_PRVOPC; 506 break; 507 508 case T_BPTFLT: /* bpt instruction fault */ 509 case T_TRCTRAP: /* trace trap */ 510 frame->tf_rflags &= ~PSL_T; 511 i = SIGTRAP; 512 ucode = (type == T_TRCTRAP ? TRAP_TRACE : TRAP_BRKPT); 513 break; 514 515 case T_ARITHTRAP: /* arithmetic trap */ 516 ucode = code; 517 i = SIGFPE; 518 break; 519 520 case T_ASTFLT: /* Allow process switch */ 521 mycpu->gd_cnt.v_soft++; 522 if (mycpu->gd_reqflags & RQF_AST_OWEUPC) { 523 atomic_clear_int(&mycpu->gd_reqflags, 524 RQF_AST_OWEUPC); 525 addupc_task(p, p->p_prof.pr_addr, 526 p->p_prof.pr_ticks); 527 } 528 goto out; 529 530 case T_PROTFLT: /* general protection fault */ 531 i = SIGBUS; 532 ucode = BUS_OBJERR; 533 break; 534 case T_STKFLT: /* stack fault */ 535 case T_SEGNPFLT: /* segment not present fault */ 536 i = SIGBUS; 537 ucode = BUS_ADRERR; 538 break; 539 case T_TSSFLT: /* invalid TSS fault */ 540 case T_DOUBLEFLT: /* double fault */ 541 default: 542 i = SIGBUS; 543 ucode = BUS_OBJERR; 544 break; 545 546 case T_PAGEFLT: /* page fault */ 547 i = trap_pfault(frame, TRUE); 548 #ifdef DDB 549 if (frame->tf_rip == 0) { 550 /* used for kernel debugging only */ 551 while (freeze_on_seg_fault) 552 tsleep(p, 0, "freeze", hz * 20); 553 } 554 #endif 555 if (i == -1 || i == 0) 556 goto out; 557 if (i == SIGSEGV) { 558 ucode = SEGV_MAPERR; 559 } else { 560 i = SIGSEGV; 561 ucode = SEGV_ACCERR; 562 } 563 break; 564 565 case T_DIVIDE: /* integer divide fault */ 566 ucode = FPE_INTDIV; 567 i = SIGFPE; 568 break; 569 570 #if NISA > 0 571 case T_NMI: 572 /* machine/parity/power fail/"kitchen sink" faults */ 573 if (isa_nmi(code) == 0) { 574 #ifdef DDB 575 /* 576 * NMI can be hooked up to a pushbutton 577 * for debugging. 578 */ 579 if (ddb_on_nmi) { 580 kprintf ("NMI ... going to debugger\n"); 581 kdb_trap(type, 0, frame); 582 } 583 #endif /* DDB */ 584 goto out2; 585 } else if (panic_on_nmi) 586 panic("NMI indicates hardware failure"); 587 break; 588 #endif /* NISA > 0 */ 589 590 case T_OFLOW: /* integer overflow fault */ 591 ucode = FPE_INTOVF; 592 i = SIGFPE; 593 break; 594 595 case T_BOUND: /* bounds check fault */ 596 ucode = FPE_FLTSUB; 597 i = SIGFPE; 598 break; 599 600 case T_DNA: 601 /* 602 * Virtual kernel intercept - pass the DNA exception 603 * to the virtual kernel if it asked to handle it. 604 * This occurs when the virtual kernel is holding 605 * onto the FP context for a different emulated 606 * process then the one currently running. 607 * 608 * We must still call npxdna() since we may have 609 * saved FP state that the virtual kernel needs 610 * to hand over to a different emulated process. 611 */ 612 if (lp->lwp_vkernel && lp->lwp_vkernel->ve && 613 (td->td_pcb->pcb_flags & FP_VIRTFP) 614 ) { 615 npxdna(); 616 break; 617 } 618 619 /* 620 * The kernel may have switched out the FP unit's 621 * state, causing the user process to take a fault 622 * when it tries to use the FP unit. Restore the 623 * state here 624 */ 625 if (npxdna()) { 626 gd->gd_cnt.v_trap++; 627 goto out; 628 } 629 i = SIGFPE; 630 ucode = FPE_FPU_NP_TRAP; 631 break; 632 633 case T_FPOPFLT: /* FPU operand fetch fault */ 634 ucode = ILL_COPROC; 635 i = SIGILL; 636 break; 637 638 case T_XMMFLT: /* SIMD floating-point exception */ 639 ucode = 0; /* XXX */ 640 i = SIGFPE; 641 break; 642 } 643 } else { 644 /* kernel trap */ 645 646 switch (type) { 647 case T_PAGEFLT: /* page fault */ 648 trap_pfault(frame, FALSE); 649 goto out2; 650 651 case T_DNA: 652 /* 653 * The kernel is apparently using fpu for copying. 654 * XXX this should be fatal unless the kernel has 655 * registered such use. 656 */ 657 if (npxdna()) { 658 gd->gd_cnt.v_trap++; 659 goto out2; 660 } 661 break; 662 663 case T_STKFLT: /* stack fault */ 664 case T_PROTFLT: /* general protection fault */ 665 case T_SEGNPFLT: /* segment not present fault */ 666 /* 667 * Invalid segment selectors and out of bounds 668 * %rip's and %rsp's can be set up in user mode. 669 * This causes a fault in kernel mode when the 670 * kernel tries to return to user mode. We want 671 * to get this fault so that we can fix the 672 * problem here and not have to check all the 673 * selectors and pointers when the user changes 674 * them. 675 */ 676 if (mycpu->gd_intr_nesting_level == 0) { 677 /* 678 * NOTE: in 64-bit mode traps push rsp/ss 679 * even if no ring change occurs. 680 */ 681 if (td->td_pcb->pcb_onfault && 682 td->td_pcb->pcb_onfault_sp == 683 frame->tf_rsp) { 684 frame->tf_rip = (register_t) 685 td->td_pcb->pcb_onfault; 686 goto out2; 687 } 688 689 /* 690 * If the iretq in doreti faults during 691 * return to user, it will be special-cased 692 * in IDTVEC(prot) to get here. We want 693 * to 'return' to doreti_iret_fault in 694 * ipl.s in approximately the same state we 695 * were in at the iretq. 696 */ 697 if (frame->tf_rip == (long)doreti_iret) { 698 frame->tf_rip = (long)doreti_iret_fault; 699 goto out2; 700 } 701 } 702 break; 703 704 case T_TSSFLT: 705 /* 706 * PSL_NT can be set in user mode and isn't cleared 707 * automatically when the kernel is entered. This 708 * causes a TSS fault when the kernel attempts to 709 * `iret' because the TSS link is uninitialized. We 710 * want to get this fault so that we can fix the 711 * problem here and not every time the kernel is 712 * entered. 713 */ 714 if (frame->tf_rflags & PSL_NT) { 715 frame->tf_rflags &= ~PSL_NT; 716 #if 0 717 /* do we need this? */ 718 if (frame->tf_rip == (long)doreti_iret) 719 frame->tf_rip = (long)doreti_iret_fault; 720 #endif 721 goto out2; 722 } 723 break; 724 725 case T_TRCTRAP: /* trace trap */ 726 /* 727 * Detect historical CPU artifact on syscall or int $3 728 * entry (if not shortcutted in exception.s via 729 * DIRECT_DISALLOW_SS_CPUBUG). 730 */ 731 gd->gd_cnt.v_trap++; 732 if (frame->tf_rip == (register_t)IDTVEC(fast_syscall)) { 733 krateprintf(&sscpubugrate, 734 "Caught #DB at syscall cpu artifact\n"); 735 goto out2; 736 } 737 if (frame->tf_rip == (register_t)IDTVEC(bpt)) { 738 krateprintf(&sscpubugrate, 739 "Caught #DB at int $N cpu artifact\n"); 740 goto out2; 741 } 742 743 /* 744 * Ignore debug register trace traps due to 745 * accesses in the user's address space, which 746 * can happen under several conditions such as 747 * if a user sets a watchpoint on a buffer and 748 * then passes that buffer to a system call. 749 * We still want to get TRCTRAPS for addresses 750 * in kernel space because that is useful when 751 * debugging the kernel. 752 */ 753 if (user_dbreg_trap()) { 754 /* 755 * Reset breakpoint bits because the 756 * processor doesn't 757 */ 758 load_dr6(rdr6() & ~0xf); 759 goto out2; 760 } 761 /* 762 * FALLTHROUGH (TRCTRAP kernel mode, kernel address) 763 */ 764 case T_BPTFLT: 765 /* 766 * If DDB is enabled, let it handle the debugger trap. 767 * Otherwise, debugger traps "can't happen". 768 */ 769 ucode = TRAP_BRKPT; 770 #ifdef DDB 771 if (kdb_trap(type, 0, frame)) 772 goto out2; 773 #endif 774 break; 775 776 #if NISA > 0 777 case T_NMI: 778 /* machine/parity/power fail/"kitchen sink" faults */ 779 if (isa_nmi(code) == 0) { 780 #ifdef DDB 781 /* 782 * NMI can be hooked up to a pushbutton 783 * for debugging. 784 */ 785 if (ddb_on_nmi) { 786 kprintf ("NMI ... going to debugger\n"); 787 kdb_trap(type, 0, frame); 788 } 789 #endif /* DDB */ 790 goto out2; 791 } else if (panic_on_nmi == 0) 792 goto out2; 793 /* FALL THROUGH */ 794 #endif /* NISA > 0 */ 795 } 796 trap_fatal(frame, 0); 797 goto out2; 798 } 799 800 /* 801 * Fault from user mode, virtual kernel interecept. 802 * 803 * If the fault is directly related to a VM context managed by a 804 * virtual kernel then let the virtual kernel handle it. 805 */ 806 if (lp->lwp_vkernel && lp->lwp_vkernel->ve) { 807 vkernel_trap(lp, frame); 808 goto out; 809 } 810 811 /* Translate fault for emulators (e.g. Linux) */ 812 if (*p->p_sysent->sv_transtrap) 813 i = (*p->p_sysent->sv_transtrap)(i, type); 814 815 gd->gd_cnt.v_trap++; 816 trapsignal(lp, i, ucode); 817 818 #ifdef DEBUG 819 if (type <= MAX_TRAP_MSG) { 820 uprintf("fatal process exception: %s", 821 trap_msg[type]); 822 if ((type == T_PAGEFLT) || (type == T_PROTFLT)) 823 uprintf(", fault VA = 0x%lx", frame->tf_addr); 824 uprintf("\n"); 825 } 826 #endif 827 828 out: 829 userret(lp, frame, sticks); 830 userexit(lp); 831 out2: ; 832 if (p != NULL && lp != NULL) 833 KTR_LOG(kernentry_trap_ret, p->p_pid, lp->lwp_tid); 834 #ifdef INVARIANTS 835 KASSERT(crit_count == td->td_critcount, 836 ("trap: critical section count mismatch! %d/%d", 837 crit_count, td->td_pri)); 838 KASSERT(curstop == td->td_toks_stop, 839 ("trap: extra tokens held after trap! %ld/%ld (%s)", 840 curstop - &td->td_toks_base, 841 td->td_toks_stop - &td->td_toks_base, 842 td->td_toks_stop[-1].tr_tok->t_desc)); 843 #endif 844 } 845 846 void 847 trap_handle_userenter(struct thread *td) 848 { 849 userenter(td, td->td_proc); 850 } 851 852 void 853 trap_handle_userexit(struct trapframe *frame, int sticks) 854 { 855 struct lwp *lp = curthread->td_lwp; 856 857 if (lp) { 858 userret(lp, frame, sticks); 859 userexit(lp); 860 } 861 } 862 863 static int 864 trap_pfault(struct trapframe *frame, int usermode) 865 { 866 vm_offset_t va; 867 struct vmspace *vm = NULL; 868 vm_map_t map; 869 int rv = 0; 870 int fault_flags; 871 vm_prot_t ftype; 872 thread_t td = curthread; 873 struct lwp *lp = td->td_lwp; 874 struct proc *p; 875 876 va = trunc_page(frame->tf_addr); 877 if (va >= VM_MIN_KERNEL_ADDRESS) { 878 /* 879 * Don't allow user-mode faults in kernel address space. 880 */ 881 if (usermode) { 882 fault_flags = -1; 883 ftype = -1; 884 goto nogo; 885 } 886 887 map = &kernel_map; 888 } else { 889 /* 890 * This is a fault on non-kernel virtual memory. 891 * vm is initialized above to NULL. If curproc is NULL 892 * or curproc->p_vmspace is NULL the fault is fatal. 893 */ 894 if (lp != NULL) 895 vm = lp->lwp_vmspace; 896 897 if (vm == NULL) { 898 fault_flags = -1; 899 ftype = -1; 900 goto nogo; 901 } 902 903 if (usermode == 0) { 904 #ifdef DDB 905 /* 906 * Debugging, catch kernel faults on the user address 907 * space when not inside on onfault (e.g. copyin/ 908 * copyout) routine. 909 */ 910 if (td->td_pcb == NULL || 911 td->td_pcb->pcb_onfault == NULL) { 912 if (freeze_on_seg_fault) { 913 kprintf("trap_pfault: user address " 914 "fault from kernel mode " 915 "%016lx\n", 916 (long)frame->tf_addr); 917 while (freeze_on_seg_fault) { 918 tsleep(&freeze_on_seg_fault, 919 0, 920 "frzseg", 921 hz * 20); 922 } 923 } 924 } 925 #endif 926 if (td->td_gd->gd_intr_nesting_level || 927 trap_is_smap(frame) || 928 td->td_pcb == NULL || 929 td->td_pcb->pcb_onfault == NULL) { 930 kprintf("Fatal user address access " 931 "from kernel mode from %s at %016jx\n", 932 td->td_comm, frame->tf_rip); 933 trap_fatal(frame, frame->tf_addr); 934 return (-1); 935 } 936 } 937 map = &vm->vm_map; 938 } 939 940 /* 941 * PGEX_I is defined only if the execute disable bit capability is 942 * supported and enabled. 943 */ 944 if (frame->tf_err & PGEX_W) 945 ftype = VM_PROT_WRITE; 946 else if (frame->tf_err & PGEX_I) 947 ftype = VM_PROT_EXECUTE; 948 else 949 ftype = VM_PROT_READ; 950 951 lwkt_tokref_t stop = td->td_toks_stop; 952 953 if (map != &kernel_map) { 954 /* 955 * Keep swapout from messing with us during this 956 * critical time. 957 */ 958 PHOLD(lp->lwp_proc); 959 960 /* 961 * Issue fault 962 */ 963 fault_flags = 0; 964 if (usermode) 965 fault_flags |= VM_FAULT_BURST | VM_FAULT_USERMODE; 966 if (ftype & VM_PROT_WRITE) 967 fault_flags |= VM_FAULT_DIRTY; 968 else 969 fault_flags |= VM_FAULT_NORMAL; 970 rv = vm_fault(map, va, ftype, fault_flags); 971 if (td->td_toks_stop != stop) { 972 stop = td->td_toks_stop - 1; 973 kprintf("A-HELD TOKENS DURING PFAULT td=%p(%s) map=%p va=%p ftype=%d fault_flags=%d\n", td, td->td_comm, map, (void *)va, ftype, fault_flags); 974 panic("held tokens"); 975 } 976 977 PRELE(lp->lwp_proc); 978 } else { 979 /* 980 * Don't have to worry about process locking or stacks in the 981 * kernel. 982 */ 983 fault_flags = VM_FAULT_NORMAL; 984 rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL); 985 if (td->td_toks_stop != stop) { 986 stop = td->td_toks_stop - 1; 987 kprintf("B-HELD TOKENS DURING PFAULT td=%p(%s) map=%p va=%p ftype=%d fault_flags=%d\n", td, td->td_comm, map, (void *)va, ftype, VM_FAULT_NORMAL); 988 panic("held tokens"); 989 } 990 } 991 if (rv == KERN_SUCCESS) 992 return (0); 993 nogo: 994 if (!usermode) { 995 /* 996 * NOTE: in 64-bit mode traps push rsp/ss 997 * even if no ring change occurs. 998 */ 999 if (td->td_pcb->pcb_onfault && 1000 td->td_pcb->pcb_onfault_sp == frame->tf_rsp && 1001 td->td_gd->gd_intr_nesting_level == 0) { 1002 frame->tf_rip = (register_t)td->td_pcb->pcb_onfault; 1003 return (0); 1004 } 1005 trap_fatal(frame, frame->tf_addr); 1006 return (-1); 1007 } 1008 1009 /* 1010 * NOTE: on x86_64 we have a tf_addr field in the trapframe, no 1011 * kludge is needed to pass the fault address to signal handlers. 1012 */ 1013 p = td->td_proc; 1014 #ifdef DDB 1015 if (td->td_lwp->lwp_vkernel == NULL) { 1016 while (freeze_on_seg_fault) { 1017 tsleep(p, 0, "freeze", hz * 20); 1018 } 1019 if (ddb_on_seg_fault) 1020 Debugger("ddb_on_seg_fault"); 1021 } 1022 #endif 1023 1024 return((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV); 1025 } 1026 1027 static void 1028 trap_fatal(struct trapframe *frame, vm_offset_t eva) 1029 { 1030 int code, ss; 1031 u_int type; 1032 long rsp; 1033 struct soft_segment_descriptor softseg; 1034 char *msg; 1035 1036 code = frame->tf_err; 1037 type = frame->tf_trapno; 1038 sdtossd(&gdt[IDXSEL(frame->tf_cs & 0xffff)], &softseg); 1039 1040 if (type <= MAX_TRAP_MSG) 1041 msg = trap_msg[type]; 1042 else 1043 msg = "UNKNOWN"; 1044 kprintf("\n\nFatal trap %d: %s while in %s mode\n", type, msg, 1045 ISPL(frame->tf_cs) == SEL_UPL ? "user" : "kernel"); 1046 /* three separate prints in case of a trap on an unmapped page */ 1047 kprintf("cpuid = %d; ", mycpu->gd_cpuid); 1048 if (lapic_usable) 1049 kprintf("lapic id = %u\n", LAPIC_READID); 1050 if (type == T_PAGEFLT) { 1051 kprintf("fault virtual address = 0x%lx\n", eva); 1052 kprintf("fault code = %s %s %s, %s\n", 1053 code & PGEX_U ? "user" : "supervisor", 1054 code & PGEX_W ? "write" : "read", 1055 code & PGEX_I ? "instruction" : "data", 1056 code & PGEX_P ? "protection violation" : "page not present"); 1057 } 1058 kprintf("instruction pointer = 0x%lx:0x%lx\n", 1059 frame->tf_cs & 0xffff, frame->tf_rip); 1060 if (ISPL(frame->tf_cs) == SEL_UPL) { 1061 ss = frame->tf_ss & 0xffff; 1062 rsp = frame->tf_rsp; 1063 } else { 1064 /* 1065 * NOTE: in 64-bit mode traps push rsp/ss even if no ring 1066 * change occurs. 1067 */ 1068 ss = GSEL(GDATA_SEL, SEL_KPL); 1069 rsp = frame->tf_rsp; 1070 } 1071 kprintf("stack pointer = 0x%x:0x%lx\n", ss, rsp); 1072 kprintf("frame pointer = 0x%x:0x%lx\n", ss, frame->tf_rbp); 1073 kprintf("code segment = base 0x%lx, limit 0x%lx, type 0x%x\n", 1074 softseg.ssd_base, softseg.ssd_limit, softseg.ssd_type); 1075 kprintf(" = DPL %d, pres %d, long %d, def32 %d, gran %d\n", 1076 softseg.ssd_dpl, softseg.ssd_p, softseg.ssd_long, softseg.ssd_def32, 1077 softseg.ssd_gran); 1078 kprintf("processor eflags = "); 1079 if (frame->tf_rflags & PSL_T) 1080 kprintf("trace trap, "); 1081 if (frame->tf_rflags & PSL_I) 1082 kprintf("interrupt enabled, "); 1083 if (frame->tf_rflags & PSL_NT) 1084 kprintf("nested task, "); 1085 if (frame->tf_rflags & PSL_RF) 1086 kprintf("resume, "); 1087 kprintf("IOPL = %ld\n", (frame->tf_rflags & PSL_IOPL) >> 12); 1088 kprintf("current process = "); 1089 if (curproc) { 1090 kprintf("%lu\n", 1091 (u_long)curproc->p_pid); 1092 } else { 1093 kprintf("Idle\n"); 1094 } 1095 kprintf("current thread = pri %d ", curthread->td_pri); 1096 if (curthread->td_critcount) 1097 kprintf("(CRIT)"); 1098 kprintf("\n"); 1099 1100 #ifdef DDB 1101 if ((debugger_on_panic || db_active) && kdb_trap(type, code, frame)) 1102 return; 1103 #endif 1104 kprintf("trap number = %d\n", type); 1105 if (type <= MAX_TRAP_MSG) 1106 panic("%s", trap_msg[type]); 1107 else 1108 panic("unknown/reserved trap"); 1109 } 1110 1111 /* 1112 * Double fault handler. Called when a fault occurs while writing 1113 * a frame for a trap/exception onto the stack. This usually occurs 1114 * when the stack overflows (such is the case with infinite recursion, 1115 * for example). 1116 */ 1117 static __inline 1118 int 1119 in_kstack_guard(register_t rptr) 1120 { 1121 thread_t td = curthread; 1122 1123 if ((char *)rptr >= td->td_kstack && 1124 (char *)rptr < td->td_kstack + PAGE_SIZE) { 1125 return 1; 1126 } 1127 return 0; 1128 } 1129 1130 void 1131 dblfault_handler(struct trapframe *frame) 1132 { 1133 thread_t td = curthread; 1134 1135 if (in_kstack_guard(frame->tf_rsp) || in_kstack_guard(frame->tf_rbp)) { 1136 kprintf("DOUBLE FAULT - KERNEL STACK GUARD HIT!\n"); 1137 if (in_kstack_guard(frame->tf_rsp)) 1138 frame->tf_rsp = (register_t)(td->td_kstack + PAGE_SIZE); 1139 if (in_kstack_guard(frame->tf_rbp)) 1140 frame->tf_rbp = (register_t)(td->td_kstack + PAGE_SIZE); 1141 } else { 1142 kprintf("DOUBLE FAULT\n"); 1143 } 1144 kprintf("\nFatal double fault\n"); 1145 kprintf("rip = 0x%lx\n", frame->tf_rip); 1146 kprintf("rsp = 0x%lx\n", frame->tf_rsp); 1147 kprintf("rbp = 0x%lx\n", frame->tf_rbp); 1148 /* three separate prints in case of a trap on an unmapped page */ 1149 kprintf("cpuid = %d; ", mycpu->gd_cpuid); 1150 if (lapic_usable) 1151 kprintf("lapic id = %u\n", LAPIC_READID); 1152 panic("double fault"); 1153 } 1154 1155 /* 1156 * syscall2 - MP aware system call request C handler 1157 * 1158 * A system call is essentially treated as a trap except that the 1159 * MP lock is not held on entry or return. We are responsible for 1160 * obtaining the MP lock if necessary and for handling ASTs 1161 * (e.g. a task switch) prior to return. 1162 * 1163 * MPSAFE 1164 */ 1165 void 1166 syscall2(struct trapframe *frame) 1167 { 1168 struct thread *td = curthread; 1169 struct proc *p = td->td_proc; 1170 struct lwp *lp = td->td_lwp; 1171 struct sysent *callp; 1172 register_t orig_tf_rflags; 1173 int sticks; 1174 int error; 1175 int narg; 1176 #ifdef INVARIANTS 1177 int crit_count = td->td_critcount; 1178 #endif 1179 register_t *argp; 1180 u_int code; 1181 int regcnt, optimized_regcnt; 1182 union sysunion args; 1183 register_t *argsdst; 1184 1185 mycpu->gd_cnt.v_syscall++; 1186 1187 #ifdef DIAGNOSTIC 1188 if (ISPL(frame->tf_cs) != SEL_UPL) { 1189 panic("syscall"); 1190 /* NOT REACHED */ 1191 } 1192 #endif 1193 1194 KTR_LOG(kernentry_syscall, p->p_pid, lp->lwp_tid, 1195 frame->tf_rax); 1196 1197 userenter(td, p); /* lazy raise our priority */ 1198 1199 regcnt = 6; 1200 optimized_regcnt = 6; 1201 1202 /* 1203 * Misc 1204 */ 1205 sticks = (int)td->td_sticks; 1206 orig_tf_rflags = frame->tf_rflags; 1207 1208 /* 1209 * Virtual kernel intercept - if a VM context managed by a virtual 1210 * kernel issues a system call the virtual kernel handles it, not us. 1211 * Restore the virtual kernel context and return from its system 1212 * call. The current frame is copied out to the virtual kernel. 1213 */ 1214 if (lp->lwp_vkernel && lp->lwp_vkernel->ve) { 1215 vkernel_trap(lp, frame); 1216 error = EJUSTRETURN; 1217 callp = NULL; 1218 code = 0; 1219 goto out; 1220 } 1221 1222 /* 1223 * Get the system call parameters and account for time 1224 */ 1225 KASSERT(lp->lwp_md.md_regs == frame, 1226 ("Frame mismatch %p %p", lp->lwp_md.md_regs, frame)); 1227 code = (u_int)frame->tf_rax; 1228 1229 if (code == SYS_syscall || code == SYS___syscall) { 1230 code = frame->tf_rdi; 1231 regcnt--; 1232 argp = &frame->tf_rdi + 1; 1233 } else { 1234 argp = &frame->tf_rdi; 1235 } 1236 1237 if (code >= p->p_sysent->sv_size) 1238 callp = &p->p_sysent->sv_table[0]; 1239 else 1240 callp = &p->p_sysent->sv_table[code]; 1241 1242 narg = callp->sy_narg & SYF_ARGMASK; 1243 1244 /* 1245 * On x86_64 we get up to six arguments in registers. The rest are 1246 * on the stack. The first six members of 'struct trapframe' happen 1247 * to be the registers used to pass arguments, in exactly the right 1248 * order. 1249 */ 1250 argsdst = (register_t *)(&args.nosys.sysmsg + 1); 1251 1252 /* 1253 * Its easier to copy up to the highest number of syscall arguments 1254 * passed in registers, which is 6, than to conditionalize it. 1255 */ 1256 bcopy(argp, argsdst, sizeof(register_t) * optimized_regcnt); 1257 1258 /* 1259 * Any arguments beyond available argument-passing registers must 1260 * be copyin()'d from the user stack. 1261 */ 1262 if (narg > regcnt) { 1263 caddr_t params; 1264 1265 params = (caddr_t)frame->tf_rsp + sizeof(register_t); 1266 error = copyin(params, &argsdst[regcnt], 1267 (narg - regcnt) * sizeof(register_t)); 1268 if (error) { 1269 #ifdef KTRACE 1270 if (KTRPOINT(td, KTR_SYSCALL)) { 1271 ktrsyscall(lp, code, narg, 1272 (void *)(&args.nosys.sysmsg + 1)); 1273 } 1274 #endif 1275 goto bad; 1276 } 1277 } 1278 1279 #ifdef KTRACE 1280 if (KTRPOINT(td, KTR_SYSCALL)) { 1281 ktrsyscall(lp, code, narg, (void *)(&args.nosys.sysmsg + 1)); 1282 } 1283 #endif 1284 1285 /* 1286 * Default return value is 0 (will be copied to %rax). Double-value 1287 * returns use %rax and %rdx. %rdx is left unchanged for system 1288 * calls which return only one result. 1289 */ 1290 args.sysmsg_fds[0] = 0; 1291 args.sysmsg_fds[1] = frame->tf_rdx; 1292 1293 /* 1294 * The syscall might manipulate the trap frame. If it does it 1295 * will probably return EJUSTRETURN. 1296 */ 1297 args.sysmsg_frame = frame; 1298 1299 STOPEVENT(p, S_SCE, narg); /* MP aware */ 1300 1301 /* 1302 * NOTE: All system calls run MPSAFE now. The system call itself 1303 * is responsible for getting the MP lock. 1304 */ 1305 #ifdef SYSCALL_DEBUG 1306 tsc_uclock_t tscval = rdtsc(); 1307 #endif 1308 error = (*callp->sy_call)(&args); 1309 #ifdef SYSCALL_DEBUG 1310 tscval = rdtsc() - tscval; 1311 tscval = tscval * 1000000 / tsc_frequency; 1312 if (SysCallsWorstCase[code] < tscval) 1313 SysCallsWorstCase[code] = tscval; 1314 #endif 1315 1316 out: 1317 /* 1318 * MP SAFE (we may or may not have the MP lock at this point) 1319 */ 1320 //kprintf("SYSMSG %d ", error); 1321 switch (error) { 1322 case 0: 1323 /* 1324 * Reinitialize proc pointer `p' as it may be different 1325 * if this is a child returning from fork syscall. 1326 */ 1327 p = curproc; 1328 lp = curthread->td_lwp; 1329 frame->tf_rax = args.sysmsg_fds[0]; 1330 frame->tf_rdx = args.sysmsg_fds[1]; 1331 frame->tf_rflags &= ~PSL_C; 1332 break; 1333 case ERESTART: 1334 /* 1335 * Reconstruct pc, we know that 'syscall' is 2 bytes. 1336 * We have to do a full context restore so that %r10 1337 * (which was holding the value of %rcx) is restored for 1338 * the next iteration. 1339 */ 1340 if (frame->tf_err != 0 && frame->tf_err != 2) 1341 kprintf("lp %s:%d frame->tf_err is weird %ld\n", 1342 td->td_comm, lp->lwp_proc->p_pid, frame->tf_err); 1343 frame->tf_rip -= frame->tf_err; 1344 frame->tf_r10 = frame->tf_rcx; 1345 break; 1346 case EJUSTRETURN: 1347 break; 1348 case EASYNC: 1349 panic("Unexpected EASYNC return value (for now)"); 1350 default: 1351 bad: 1352 if (p->p_sysent->sv_errsize) { 1353 if (error >= p->p_sysent->sv_errsize) 1354 error = -1; /* XXX */ 1355 else 1356 error = p->p_sysent->sv_errtbl[error]; 1357 } 1358 frame->tf_rax = error; 1359 frame->tf_rflags |= PSL_C; 1360 break; 1361 } 1362 1363 /* 1364 * Traced syscall. trapsignal() should now be MP aware 1365 */ 1366 if (orig_tf_rflags & PSL_T) { 1367 frame->tf_rflags &= ~PSL_T; 1368 trapsignal(lp, SIGTRAP, TRAP_TRACE); 1369 } 1370 1371 /* 1372 * Handle reschedule and other end-of-syscall issues 1373 */ 1374 userret(lp, frame, sticks); 1375 1376 #ifdef KTRACE 1377 if (KTRPOINT(td, KTR_SYSRET)) { 1378 ktrsysret(lp, code, error, args.sysmsg_result); 1379 } 1380 #endif 1381 1382 /* 1383 * This works because errno is findable through the 1384 * register set. If we ever support an emulation where this 1385 * is not the case, this code will need to be revisited. 1386 */ 1387 STOPEVENT(p, S_SCX, code); 1388 1389 userexit(lp); 1390 KTR_LOG(kernentry_syscall_ret, p->p_pid, lp->lwp_tid, error); 1391 #ifdef INVARIANTS 1392 KASSERT(crit_count == td->td_critcount, 1393 ("syscall: critical section count mismatch! %d/%d", 1394 crit_count, td->td_pri)); 1395 KASSERT(&td->td_toks_base == td->td_toks_stop, 1396 ("syscall: %ld extra tokens held after trap! syscall %p", 1397 td->td_toks_stop - &td->td_toks_base, 1398 callp->sy_call)); 1399 #endif 1400 } 1401 1402 void 1403 fork_return(struct lwp *lp, struct trapframe *frame) 1404 { 1405 frame->tf_rax = 0; /* Child returns zero */ 1406 frame->tf_rflags &= ~PSL_C; /* success */ 1407 frame->tf_rdx = 1; 1408 1409 generic_lwp_return(lp, frame); 1410 KTR_LOG(kernentry_fork_ret, lp->lwp_proc->p_pid, lp->lwp_tid); 1411 } 1412 1413 /* 1414 * Simplified back end of syscall(), used when returning from fork() 1415 * directly into user mode. 1416 * 1417 * This code will return back into the fork trampoline code which then 1418 * runs doreti. 1419 */ 1420 void 1421 generic_lwp_return(struct lwp *lp, struct trapframe *frame) 1422 { 1423 struct proc *p = lp->lwp_proc; 1424 1425 /* 1426 * Check for exit-race. If one lwp exits the process concurrent with 1427 * another lwp creating a new thread, the two operations may cross 1428 * each other resulting in the newly-created lwp not receiving a 1429 * KILL signal. 1430 */ 1431 if (p->p_flags & P_WEXIT) { 1432 lwpsignal(p, lp, SIGKILL); 1433 } 1434 1435 /* 1436 * Newly forked processes are given a kernel priority. We have to 1437 * adjust the priority to a normal user priority and fake entry 1438 * into the kernel (call userenter()) to install a passive release 1439 * function just in case userret() decides to stop the process. This 1440 * can occur when ^Z races a fork. If we do not install the passive 1441 * release function the current process designation will not be 1442 * released when the thread goes to sleep. 1443 */ 1444 lwkt_setpri_self(TDPRI_USER_NORM); 1445 userenter(lp->lwp_thread, p); 1446 userret(lp, frame, 0); 1447 #ifdef KTRACE 1448 if (KTRPOINT(lp->lwp_thread, KTR_SYSRET)) 1449 ktrsysret(lp, SYS_fork, 0, 0); 1450 #endif 1451 lp->lwp_flags |= LWP_PASSIVE_ACQ; 1452 userexit(lp); 1453 lp->lwp_flags &= ~LWP_PASSIVE_ACQ; 1454 } 1455 1456 /* 1457 * If PGEX_FPFAULT is set then set FP_VIRTFP in the PCB to force a T_DNA 1458 * fault (which is then passed back to the virtual kernel) if an attempt is 1459 * made to use the FP unit. 1460 * 1461 * XXX this is a fairly big hack. 1462 */ 1463 void 1464 set_vkernel_fp(struct trapframe *frame) 1465 { 1466 struct thread *td = curthread; 1467 1468 if (frame->tf_xflags & PGEX_FPFAULT) { 1469 td->td_pcb->pcb_flags |= FP_VIRTFP; 1470 if (mdcpu->gd_npxthread == td) 1471 npxexit(); 1472 } else { 1473 td->td_pcb->pcb_flags &= ~FP_VIRTFP; 1474 } 1475 } 1476 1477 /* 1478 * Called from vkernel_trap() to fixup the vkernel's syscall 1479 * frame for vmspace_ctl() return. 1480 */ 1481 void 1482 cpu_vkernel_trap(struct trapframe *frame, int error) 1483 { 1484 frame->tf_rax = error; 1485 if (error) 1486 frame->tf_rflags |= PSL_C; 1487 else 1488 frame->tf_rflags &= ~PSL_C; 1489 } 1490