Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/amd64/amd64/trap.c
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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: releng/5.1/sys/amd64/amd64/trap.c 115737 2003-06-02 21:57:08Z peter $ 39 */ 40 41 /* 42 * AMD64 Trap and System call handling 43 */ 44 45 #include "opt_clock.h" 46 #include "opt_cpu.h" 47 #include "opt_ddb.h" 48 #include "opt_isa.h" 49 #include "opt_ktrace.h" 50 51 #include <sys/param.h> 52 #include <sys/bus.h> 53 #include <sys/systm.h> 54 #include <sys/proc.h> 55 #include <sys/pioctl.h> 56 #include <sys/kernel.h> 57 #include <sys/ktr.h> 58 #include <sys/lock.h> 59 #include <sys/mutex.h> 60 #include <sys/resourcevar.h> 61 #include <sys/signalvar.h> 62 #include <sys/syscall.h> 63 #include <sys/sysctl.h> 64 #include <sys/sysent.h> 65 #include <sys/uio.h> 66 #include <sys/vmmeter.h> 67 #ifdef KTRACE 68 #include <sys/ktrace.h> 69 #endif 70 71 #include <vm/vm.h> 72 #include <vm/vm_param.h> 73 #include <vm/pmap.h> 74 #include <vm/vm_kern.h> 75 #include <vm/vm_map.h> 76 #include <vm/vm_page.h> 77 #include <vm/vm_extern.h> 78 79 #include <machine/cpu.h> 80 #include <machine/md_var.h> 81 #include <machine/pcb.h> 82 #include <machine/tss.h> 83 84 #include <amd64/isa/icu.h> 85 #include <amd64/isa/intr_machdep.h> 86 87 #include <ddb/ddb.h> 88 89 #include <sys/sysctl.h> 90 91 extern void trap(struct trapframe frame); 92 extern void syscall(struct trapframe frame); 93 94 static int trap_pfault(struct trapframe *, int); 95 static void trap_fatal(struct trapframe *, vm_offset_t); 96 void dblfault_handler(void); 97 98 #define MAX_TRAP_MSG 28 99 static char *trap_msg[] = { 100 "", /* 0 unused */ 101 "privileged instruction fault", /* 1 T_PRIVINFLT */ 102 "", /* 2 unused */ 103 "breakpoint instruction fault", /* 3 T_BPTFLT */ 104 "", /* 4 unused */ 105 "", /* 5 unused */ 106 "arithmetic trap", /* 6 T_ARITHTRAP */ 107 "", /* 7 unused */ 108 "", /* 8 unused */ 109 "general protection fault", /* 9 T_PROTFLT */ 110 "trace trap", /* 10 T_TRCTRAP */ 111 "", /* 11 unused */ 112 "page fault", /* 12 T_PAGEFLT */ 113 "", /* 13 unused */ 114 "alignment fault", /* 14 T_ALIGNFLT */ 115 "", /* 15 unused */ 116 "", /* 16 unused */ 117 "", /* 17 unused */ 118 "integer divide fault", /* 18 T_DIVIDE */ 119 "non-maskable interrupt trap", /* 19 T_NMI */ 120 "overflow trap", /* 20 T_OFLOW */ 121 "FPU bounds check fault", /* 21 T_BOUND */ 122 "FPU device not available", /* 22 T_DNA */ 123 "double fault", /* 23 T_DOUBLEFLT */ 124 "FPU operand fetch fault", /* 24 T_FPOPFLT */ 125 "invalid TSS fault", /* 25 T_TSSFLT */ 126 "segment not present fault", /* 26 T_SEGNPFLT */ 127 "stack fault", /* 27 T_STKFLT */ 128 "machine check trap", /* 28 T_MCHK */ 129 }; 130 131 #ifdef DDB 132 static int ddb_on_nmi = 1; 133 SYSCTL_INT(_machdep, OID_AUTO, ddb_on_nmi, CTLFLAG_RW, 134 &ddb_on_nmi, 0, "Go to DDB on NMI"); 135 #endif 136 static int panic_on_nmi = 1; 137 SYSCTL_INT(_machdep, OID_AUTO, panic_on_nmi, CTLFLAG_RW, 138 &panic_on_nmi, 0, "Panic on NMI"); 139 140 #ifdef WITNESS 141 extern char *syscallnames[]; 142 #endif 143 144 #ifdef DEVICE_POLLING 145 extern u_int32_t poll_in_trap; 146 extern int ether_poll(int count); 147 #endif /* DEVICE_POLLING */ 148 149 /* 150 * Exception, fault, and trap interface to the FreeBSD kernel. 151 * This common code is called from assembly language IDT gate entry 152 * routines that prepare a suitable stack frame, and restore this 153 * frame after the exception has been processed. 154 */ 155 156 void 157 trap(frame) 158 struct trapframe frame; 159 { 160 struct thread *td = curthread; 161 struct proc *p = td->td_proc; 162 u_int sticks = 0; 163 int i = 0, ucode = 0, type, code; 164 165 atomic_add_int(&cnt.v_trap, 1); 166 type = frame.tf_trapno; 167 168 #ifdef DDB 169 if (db_active) { 170 vm_offset_t eva; 171 eva = (type == T_PAGEFLT ? frame.tf_addr : 0); 172 trap_fatal(&frame, eva); 173 goto out; 174 } 175 #endif 176 177 if ((frame.tf_rflags & PSL_I) == 0) { 178 /* 179 * Buggy application or kernel code has disabled 180 * interrupts and then trapped. Enabling interrupts 181 * now is wrong, but it is better than running with 182 * interrupts disabled until they are accidentally 183 * enabled later. 184 */ 185 if (ISPL(frame.tf_cs) == SEL_UPL) 186 printf( 187 "pid %ld (%s): trap %d with interrupts disabled\n", 188 (long)curproc->p_pid, curproc->p_comm, type); 189 else if (type != T_BPTFLT && type != T_TRCTRAP) { 190 /* 191 * XXX not quite right, since this may be for a 192 * multiple fault in user mode. 193 */ 194 printf("kernel trap %d with interrupts disabled\n", 195 type); 196 /* 197 * We shouldn't enable interrupts while in a critical 198 * section. 199 */ 200 if (td->td_critnest == 0) 201 enable_intr(); 202 } 203 } 204 205 code = frame.tf_err; 206 if (type == T_PAGEFLT) { 207 /* 208 * If we get a page fault while in a critical section, then 209 * it is most likely a fatal kernel page fault. The kernel 210 * is already going to panic trying to get a sleep lock to 211 * do the VM lookup, so just consider it a fatal trap so the 212 * kernel can print out a useful trap message and even get 213 * to the debugger. 214 */ 215 if (td->td_critnest != 0) 216 trap_fatal(&frame, frame.tf_addr); 217 } 218 219 #ifdef DEVICE_POLLING 220 if (poll_in_trap) 221 ether_poll(poll_in_trap); 222 #endif /* DEVICE_POLLING */ 223 224 if (ISPL(frame.tf_cs) == SEL_UPL) { 225 /* user trap */ 226 227 sticks = td->td_sticks; 228 td->td_frame = &frame; 229 if (td->td_ucred != p->p_ucred) 230 cred_update_thread(td); 231 232 switch (type) { 233 case T_PRIVINFLT: /* privileged instruction fault */ 234 ucode = type; 235 i = SIGILL; 236 break; 237 238 case T_BPTFLT: /* bpt instruction fault */ 239 case T_TRCTRAP: /* trace trap */ 240 frame.tf_rflags &= ~PSL_T; 241 i = SIGTRAP; 242 break; 243 244 case T_ARITHTRAP: /* arithmetic trap */ 245 ucode = npxtrap(); 246 if (ucode == -1) 247 goto userout; 248 i = SIGFPE; 249 break; 250 251 case T_PROTFLT: /* general protection fault */ 252 case T_STKFLT: /* stack fault */ 253 case T_SEGNPFLT: /* segment not present fault */ 254 case T_TSSFLT: /* invalid TSS fault */ 255 case T_DOUBLEFLT: /* double fault */ 256 default: 257 ucode = code + BUS_SEGM_FAULT ; 258 i = SIGBUS; 259 break; 260 261 case T_PAGEFLT: /* page fault */ 262 i = trap_pfault(&frame, TRUE); 263 if (i == -1) 264 goto userout; 265 if (i == 0) 266 goto user; 267 268 ucode = T_PAGEFLT; 269 break; 270 271 case T_DIVIDE: /* integer divide fault */ 272 ucode = FPE_INTDIV; 273 i = SIGFPE; 274 break; 275 276 #ifdef DEV_ISA 277 case T_NMI: 278 /* machine/parity/power fail/"kitchen sink" faults */ 279 /* XXX Giant */ 280 if (isa_nmi(code) == 0) { 281 #ifdef DDB 282 /* 283 * NMI can be hooked up to a pushbutton 284 * for debugging. 285 */ 286 if (ddb_on_nmi) { 287 printf ("NMI ... going to debugger\n"); 288 kdb_trap (type, 0, &frame); 289 } 290 #endif /* DDB */ 291 goto userout; 292 } else if (panic_on_nmi) 293 panic("NMI indicates hardware failure"); 294 break; 295 #endif /* DEV_ISA */ 296 297 case T_OFLOW: /* integer overflow fault */ 298 ucode = FPE_INTOVF; 299 i = SIGFPE; 300 break; 301 302 case T_BOUND: /* bounds check fault */ 303 ucode = FPE_FLTSUB; 304 i = SIGFPE; 305 break; 306 307 case T_DNA: 308 /* transparent fault (due to context switch "late") */ 309 if (npxdna()) 310 goto userout; 311 i = SIGFPE; 312 ucode = FPE_FPU_NP_TRAP; 313 break; 314 315 case T_FPOPFLT: /* FPU operand fetch fault */ 316 ucode = T_FPOPFLT; 317 i = SIGILL; 318 break; 319 320 case T_XMMFLT: /* SIMD floating-point exception */ 321 ucode = 0; /* XXX */ 322 i = SIGFPE; 323 break; 324 } 325 } else { 326 /* kernel trap */ 327 328 KASSERT(cold || td->td_ucred != NULL, 329 ("kernel trap doesn't have ucred")); 330 switch (type) { 331 case T_PAGEFLT: /* page fault */ 332 (void) trap_pfault(&frame, FALSE); 333 goto out; 334 335 case T_DNA: 336 /* 337 * The kernel is apparently using npx for copying. 338 * XXX this should be fatal unless the kernel has 339 * registered such use. 340 */ 341 if (npxdna()) { 342 printf("npxdna in kernel mode!\n"); 343 goto out; 344 } 345 break; 346 347 case T_STKFLT: /* stack fault */ 348 break; 349 350 case T_PROTFLT: /* general protection fault */ 351 case T_SEGNPFLT: /* segment not present fault */ 352 if (td->td_intr_nesting_level != 0) 353 break; 354 355 /* 356 * Invalid segment selectors and out of bounds 357 * %eip's and %esp's can be set up in user mode. 358 * This causes a fault in kernel mode when the 359 * kernel tries to return to user mode. We want 360 * to get this fault so that we can fix the 361 * problem here and not have to check all the 362 * selectors and pointers when the user changes 363 * them. 364 */ 365 if (frame.tf_rip == (long)doreti_iret) { 366 frame.tf_rip = (long)doreti_iret_fault; 367 goto out; 368 } 369 if (PCPU_GET(curpcb) != NULL && 370 PCPU_GET(curpcb)->pcb_onfault != NULL) { 371 frame.tf_rip = 372 (long)PCPU_GET(curpcb)->pcb_onfault; 373 goto out; 374 } 375 break; 376 377 case T_TSSFLT: 378 /* 379 * PSL_NT can be set in user mode and isn't cleared 380 * automatically when the kernel is entered. This 381 * causes a TSS fault when the kernel attempts to 382 * `iret' because the TSS link is uninitialized. We 383 * want to get this fault so that we can fix the 384 * problem here and not every time the kernel is 385 * entered. 386 */ 387 if (frame.tf_rflags & PSL_NT) { 388 frame.tf_rflags &= ~PSL_NT; 389 goto out; 390 } 391 break; 392 393 case T_TRCTRAP: /* trace trap */ 394 /* 395 * FALLTHROUGH (TRCTRAP kernel mode, kernel address) 396 */ 397 case T_BPTFLT: 398 /* 399 * If DDB is enabled, let it handle the debugger trap. 400 * Otherwise, debugger traps "can't happen". 401 */ 402 #ifdef DDB 403 /* XXX Giant */ 404 if (kdb_trap (type, 0, &frame)) 405 goto out; 406 #endif 407 break; 408 409 #ifdef DEV_ISA 410 case T_NMI: 411 /* XXX Giant */ 412 /* machine/parity/power fail/"kitchen sink" faults */ 413 if (isa_nmi(code) == 0) { 414 #ifdef DDB 415 /* 416 * NMI can be hooked up to a pushbutton 417 * for debugging. 418 */ 419 if (ddb_on_nmi) { 420 printf ("NMI ... going to debugger\n"); 421 kdb_trap (type, 0, &frame); 422 } 423 #endif /* DDB */ 424 goto out; 425 } else if (panic_on_nmi == 0) 426 goto out; 427 /* FALLTHROUGH */ 428 #endif /* DEV_ISA */ 429 } 430 431 trap_fatal(&frame, 0); 432 goto out; 433 } 434 435 /* Translate fault for emulators (e.g. Linux) */ 436 if (*p->p_sysent->sv_transtrap) 437 i = (*p->p_sysent->sv_transtrap)(i, type); 438 439 trapsignal(td, i, ucode); 440 441 #ifdef DEBUG 442 if (type <= MAX_TRAP_MSG) { 443 uprintf("fatal process exception: %s", 444 trap_msg[type]); 445 if ((type == T_PAGEFLT) || (type == T_PROTFLT)) 446 uprintf(", fault VA = 0x%lx", frame.tf_addr); 447 uprintf("\n"); 448 } 449 #endif 450 451 user: 452 userret(td, &frame, sticks); 453 mtx_assert(&Giant, MA_NOTOWNED); 454 userout: 455 #ifdef DIAGNOSTIC 456 cred_free_thread(td); 457 #endif 458 out: 459 return; 460 } 461 462 static int 463 trap_pfault(frame, usermode) 464 struct trapframe *frame; 465 int usermode; 466 { 467 vm_offset_t va; 468 struct vmspace *vm = NULL; 469 vm_map_t map = 0; 470 int rv = 0; 471 vm_prot_t ftype; 472 struct thread *td = curthread; 473 struct proc *p = td->td_proc; 474 vm_offset_t eva = frame->tf_addr; 475 476 va = trunc_page(eva); 477 if (va >= KERNBASE) { 478 /* 479 * Don't allow user-mode faults in kernel address space. 480 */ 481 if (usermode) 482 goto nogo; 483 484 map = kernel_map; 485 } else { 486 /* 487 * This is a fault on non-kernel virtual memory. 488 * vm is initialized above to NULL. If curproc is NULL 489 * or curproc->p_vmspace is NULL the fault is fatal. 490 */ 491 if (p != NULL) 492 vm = p->p_vmspace; 493 494 if (vm == NULL) 495 goto nogo; 496 497 map = &vm->vm_map; 498 } 499 500 if (frame->tf_err & PGEX_W) 501 ftype = VM_PROT_WRITE; 502 else 503 ftype = VM_PROT_READ; 504 505 if (map != kernel_map) { 506 /* 507 * Keep swapout from messing with us during this 508 * critical time. 509 */ 510 PROC_LOCK(p); 511 ++p->p_lock; 512 PROC_UNLOCK(p); 513 514 /* Fault in the user page: */ 515 rv = vm_fault(map, va, ftype, 516 (ftype & VM_PROT_WRITE) ? VM_FAULT_DIRTY 517 : VM_FAULT_NORMAL); 518 519 PROC_LOCK(p); 520 --p->p_lock; 521 PROC_UNLOCK(p); 522 } else { 523 /* 524 * Don't have to worry about process locking or stacks in the 525 * kernel. 526 */ 527 rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL); 528 } 529 if (rv == KERN_SUCCESS) 530 return (0); 531 nogo: 532 if (!usermode) { 533 if (td->td_intr_nesting_level == 0 && 534 PCPU_GET(curpcb) != NULL && 535 PCPU_GET(curpcb)->pcb_onfault != NULL) { 536 frame->tf_rip = (long)PCPU_GET(curpcb)->pcb_onfault; 537 return (0); 538 } 539 trap_fatal(frame, eva); 540 return (-1); 541 } 542 543 return((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV); 544 } 545 546 static void 547 trap_fatal(frame, eva) 548 struct trapframe *frame; 549 vm_offset_t eva; 550 { 551 int code, type, ss; 552 long esp; 553 struct soft_segment_descriptor softseg; 554 555 code = frame->tf_err; 556 type = frame->tf_trapno; 557 sdtossd(&gdt[IDXSEL(frame->tf_cs & 0xffff)], &softseg); 558 559 if (type <= MAX_TRAP_MSG) 560 printf("\n\nFatal trap %d: %s while in %s mode\n", 561 type, trap_msg[type], 562 ISPL(frame->tf_cs) == SEL_UPL ? "user" : "kernel"); 563 if (type == T_PAGEFLT) { 564 printf("fault virtual address = 0x%lx\n", eva); 565 printf("fault code = %s %s, %s\n", 566 code & PGEX_U ? "user" : "supervisor", 567 code & PGEX_W ? "write" : "read", 568 code & PGEX_P ? "protection violation" : "page not present"); 569 } 570 printf("instruction pointer = 0x%lx:0x%lx\n", 571 frame->tf_cs & 0xffff, frame->tf_rip); 572 if (ISPL(frame->tf_cs) == SEL_UPL) { 573 ss = frame->tf_ss & 0xffff; 574 esp = frame->tf_rsp; 575 } else { 576 ss = GSEL(GDATA_SEL, SEL_KPL); 577 esp = (long)&frame->tf_rsp; 578 } 579 printf("stack pointer = 0x%x:0x%lx\n", ss, esp); 580 printf("frame pointer = 0x%x:0x%lx\n", ss, frame->tf_rbp); 581 printf("code segment = base 0x%lx, limit 0x%lx, type 0x%x\n", 582 softseg.ssd_base, softseg.ssd_limit, softseg.ssd_type); 583 printf(" = DPL %d, pres %d, long %d, def32 %d, gran %d\n", 584 softseg.ssd_dpl, softseg.ssd_p, softseg.ssd_long, softseg.ssd_def32, 585 softseg.ssd_gran); 586 printf("processor eflags = "); 587 if (frame->tf_rflags & PSL_T) 588 printf("trace trap, "); 589 if (frame->tf_rflags & PSL_I) 590 printf("interrupt enabled, "); 591 if (frame->tf_rflags & PSL_NT) 592 printf("nested task, "); 593 if (frame->tf_rflags & PSL_RF) 594 printf("resume, "); 595 printf("IOPL = %ld\n", (frame->tf_rflags & PSL_IOPL) >> 12); 596 printf("current process = "); 597 if (curproc) { 598 printf("%lu (%s)\n", 599 (u_long)curproc->p_pid, curproc->p_comm ? 600 curproc->p_comm : ""); 601 } else { 602 printf("Idle\n"); 603 } 604 605 #ifdef KDB 606 if (kdb_trap(&psl)) 607 return; 608 #endif 609 #ifdef DDB 610 if ((debugger_on_panic || db_active) && kdb_trap(type, 0, frame)) 611 return; 612 #endif 613 printf("trap number = %d\n", type); 614 if (type <= MAX_TRAP_MSG) 615 panic("%s", trap_msg[type]); 616 else 617 panic("unknown/reserved trap"); 618 } 619 620 /* 621 * Double fault handler. Called when a fault occurs while writing 622 * a frame for a trap/exception onto the stack. This usually occurs 623 * when the stack overflows (such is the case with infinite recursion, 624 * for example). 625 */ 626 void 627 dblfault_handler() 628 { 629 printf("\nFatal double fault\n"); 630 panic("double fault"); 631 } 632 633 /* 634 * syscall - system call request C handler 635 * 636 * A system call is essentially treated as a trap. 637 */ 638 void 639 syscall(frame) 640 struct trapframe frame; 641 { 642 caddr_t params; 643 struct sysent *callp; 644 struct thread *td = curthread; 645 struct proc *p = td->td_proc; 646 register_t orig_tf_rflags; 647 u_int sticks; 648 int error; 649 int narg; 650 register_t args[8]; 651 register_t *argp; 652 u_int code; 653 int reg, regcnt; 654 655 /* 656 * note: PCPU_LAZY_INC() can only be used if we can afford 657 * occassional inaccuracy in the count. 658 */ 659 PCPU_LAZY_INC(cnt.v_syscall); 660 661 #ifdef DIAGNOSTIC 662 if (ISPL(frame.tf_cs) != SEL_UPL) { 663 mtx_lock(&Giant); /* try to stabilize the system XXX */ 664 panic("syscall"); 665 /* NOT REACHED */ 666 mtx_unlock(&Giant); 667 } 668 #endif 669 670 reg = 0; 671 regcnt = 6; 672 sticks = td->td_sticks; 673 td->td_frame = &frame; 674 if (td->td_ucred != p->p_ucred) 675 cred_update_thread(td); 676 if (p->p_flag & P_THREADED) 677 thread_user_enter(p, td); 678 params = (caddr_t)frame.tf_rsp + sizeof(register_t); 679 code = frame.tf_rax; 680 orig_tf_rflags = frame.tf_rflags; 681 682 if (p->p_sysent->sv_prepsyscall) { 683 /* 684 * The prep code is MP aware. 685 */ 686 (*p->p_sysent->sv_prepsyscall)(&frame, (int *)args, &code, ¶ms); 687 } else { 688 if (code == SYS_syscall || code == SYS___syscall) { 689 code = frame.tf_rdi; 690 reg++; 691 regcnt--; 692 } 693 } 694 695 if (p->p_sysent->sv_mask) 696 code &= p->p_sysent->sv_mask; 697 698 if (code >= p->p_sysent->sv_size) 699 callp = &p->p_sysent->sv_table[0]; 700 else 701 callp = &p->p_sysent->sv_table[code]; 702 703 narg = callp->sy_narg & SYF_ARGMASK; 704 705 /* 706 * copyin and the ktrsyscall()/ktrsysret() code is MP-aware 707 */ 708 if (narg <= regcnt) { 709 argp = &frame.tf_rdi; 710 argp += reg; 711 error = 0; 712 } else { 713 KASSERT(narg <= sizeof(args) / sizeof(args[0]), 714 ("Too many syscall arguments!")); 715 KASSERT(params != NULL, ("copyin args with no params!")); 716 argp = &frame.tf_rdi; 717 argp += reg; 718 bcopy(argp, args, sizeof(args[0]) * regcnt); 719 error = copyin(params, &args[regcnt], 720 (narg - regcnt) * sizeof(args[0])); 721 argp = &args[0]; 722 } 723 724 #ifdef KTRACE 725 if (KTRPOINT(td, KTR_SYSCALL)) 726 ktrsyscall(code, narg, argp); 727 #endif 728 729 /* 730 * Try to run the syscall without Giant if the syscall 731 * is MP safe. 732 */ 733 if ((callp->sy_narg & SYF_MPSAFE) == 0) 734 mtx_lock(&Giant); 735 736 if (error == 0) { 737 td->td_retval[0] = 0; 738 td->td_retval[1] = frame.tf_rdx; 739 740 STOPEVENT(p, S_SCE, narg); 741 742 error = (*callp->sy_call)(td, argp); 743 } 744 745 switch (error) { 746 case 0: 747 frame.tf_rax = td->td_retval[0]; 748 frame.tf_rdx = td->td_retval[1]; 749 frame.tf_rflags &= ~PSL_C; 750 break; 751 752 case ERESTART: 753 /* 754 * Reconstruct pc, we know that 'syscall' is 2 bytes. 755 * We have to do a full context restore so that %r10 756 * (which was holding the value of %rcx) is restored for 757 * the next iteration. 758 */ 759 frame.tf_rip -= frame.tf_err; 760 frame.tf_r10 = frame.tf_rcx; 761 td->td_pcb->pcb_flags |= PCB_FULLCTX; 762 break; 763 764 case EJUSTRETURN: 765 break; 766 767 default: 768 if (p->p_sysent->sv_errsize) { 769 if (error >= p->p_sysent->sv_errsize) 770 error = -1; /* XXX */ 771 else 772 error = p->p_sysent->sv_errtbl[error]; 773 } 774 frame.tf_rax = error; 775 frame.tf_rflags |= PSL_C; 776 break; 777 } 778 779 /* 780 * Release Giant if we previously set it. 781 */ 782 if ((callp->sy_narg & SYF_MPSAFE) == 0) 783 mtx_unlock(&Giant); 784 785 /* 786 * Traced syscall. 787 */ 788 if (orig_tf_rflags & PSL_T) { 789 frame.tf_rflags &= ~PSL_T; 790 trapsignal(td, SIGTRAP, 0); 791 } 792 793 /* 794 * Handle reschedule and other end-of-syscall issues 795 */ 796 userret(td, &frame, sticks); 797 798 #ifdef KTRACE 799 if (KTRPOINT(td, KTR_SYSRET)) 800 ktrsysret(code, error, td->td_retval[0]); 801 #endif 802 803 /* 804 * This works because errno is findable through the 805 * register set. If we ever support an emulation where this 806 * is not the case, this code will need to be revisited. 807 */ 808 STOPEVENT(p, S_SCX, code); 809 810 #ifdef DIAGNOSTIC 811 cred_free_thread(td); 812 #endif 813 WITNESS_WARN(WARN_PANIC, NULL, "System call %s returning", 814 (code >= 0 && code < SYS_MAXSYSCALL) ? syscallnames[code] : "???"); 815 mtx_assert(&sched_lock, MA_NOTOWNED); 816 mtx_assert(&Giant, MA_NOTOWNED); 817 }
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