vm_machdep.c revision 283735
1/*- 2 * Copyright (c) 1982, 1986 The Regents of the University of California. 3 * Copyright (c) 1989, 1990 William Jolitz 4 * Copyright (c) 1994 John Dyson 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * the Systems Programming Group of the University of Utah Computer 9 * Science Department, 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: @(#)vm_machdep.c 7.3 (Berkeley) 5/13/91 40 * Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$ 41 */ 42 43#include <sys/cdefs.h> 44__FBSDID("$FreeBSD: head/sys/amd64/amd64/vm_machdep.c 283735 2015-05-29 13:24:17Z kib $"); 45 46#include "opt_isa.h" 47#include "opt_cpu.h" 48#include "opt_compat.h" 49 50#include <sys/param.h> 51#include <sys/systm.h> 52#include <sys/bio.h> 53#include <sys/buf.h> 54#include <sys/kernel.h> 55#include <sys/ktr.h> 56#include <sys/lock.h> 57#include <sys/malloc.h> 58#include <sys/mbuf.h> 59#include <sys/mutex.h> 60#include <sys/pioctl.h> 61#include <sys/proc.h> 62#include <sys/smp.h> 63#include <sys/sysctl.h> 64#include <sys/sysent.h> 65#include <sys/unistd.h> 66#include <sys/vnode.h> 67#include <sys/vmmeter.h> 68 69#include <machine/cpu.h> 70#include <machine/md_var.h> 71#include <machine/pcb.h> 72#include <machine/smp.h> 73#include <machine/specialreg.h> 74#include <machine/tss.h> 75 76#include <vm/vm.h> 77#include <vm/vm_extern.h> 78#include <vm/vm_kern.h> 79#include <vm/vm_page.h> 80#include <vm/vm_map.h> 81#include <vm/vm_param.h> 82 83#include <isa/isareg.h> 84 85static void cpu_reset_real(void); 86#ifdef SMP 87static void cpu_reset_proxy(void); 88static u_int cpu_reset_proxyid; 89static volatile u_int cpu_reset_proxy_active; 90#endif 91 92_Static_assert(OFFSETOF_CURTHREAD == offsetof(struct pcpu, pc_curthread), 93 "OFFSETOF_CURTHREAD does not correspond with offset of pc_curthread."); 94_Static_assert(OFFSETOF_CURPCB == offsetof(struct pcpu, pc_curpcb), 95 "OFFSETOF_CURPCB does not correspond with offset of pc_curpcb."); 96 97struct savefpu * 98get_pcb_user_save_td(struct thread *td) 99{ 100 vm_offset_t p; 101 102 p = td->td_kstack + td->td_kstack_pages * PAGE_SIZE - 103 cpu_max_ext_state_size; 104 KASSERT((p % 64) == 0, ("Unaligned pcb_user_save area")); 105 return ((struct savefpu *)p); 106} 107 108struct savefpu * 109get_pcb_user_save_pcb(struct pcb *pcb) 110{ 111 vm_offset_t p; 112 113 p = (vm_offset_t)(pcb + 1); 114 return ((struct savefpu *)p); 115} 116 117struct pcb * 118get_pcb_td(struct thread *td) 119{ 120 vm_offset_t p; 121 122 p = td->td_kstack + td->td_kstack_pages * PAGE_SIZE - 123 cpu_max_ext_state_size - sizeof(struct pcb); 124 return ((struct pcb *)p); 125} 126 127void * 128alloc_fpusave(int flags) 129{ 130 void *res; 131 struct savefpu_ymm *sf; 132 133 res = malloc(cpu_max_ext_state_size, M_DEVBUF, flags); 134 if (use_xsave) { 135 sf = (struct savefpu_ymm *)res; 136 bzero(&sf->sv_xstate.sx_hd, sizeof(sf->sv_xstate.sx_hd)); 137 sf->sv_xstate.sx_hd.xstate_bv = xsave_mask; 138 } 139 return (res); 140} 141 142/* 143 * Finish a fork operation, with process p2 nearly set up. 144 * Copy and update the pcb, set up the stack so that the child 145 * ready to run and return to user mode. 146 */ 147void 148cpu_fork(td1, p2, td2, flags) 149 register struct thread *td1; 150 register struct proc *p2; 151 struct thread *td2; 152 int flags; 153{ 154 register struct proc *p1; 155 struct pcb *pcb2; 156 struct mdproc *mdp1, *mdp2; 157 struct proc_ldt *pldt; 158 159 p1 = td1->td_proc; 160 if ((flags & RFPROC) == 0) { 161 if ((flags & RFMEM) == 0) { 162 /* unshare user LDT */ 163 mdp1 = &p1->p_md; 164 mtx_lock(&dt_lock); 165 if ((pldt = mdp1->md_ldt) != NULL && 166 pldt->ldt_refcnt > 1 && 167 user_ldt_alloc(p1, 1) == NULL) 168 panic("could not copy LDT"); 169 mtx_unlock(&dt_lock); 170 } 171 return; 172 } 173 174 /* Ensure that td1's pcb is up to date. */ 175 fpuexit(td1); 176 177 /* Point the pcb to the top of the stack */ 178 pcb2 = get_pcb_td(td2); 179 td2->td_pcb = pcb2; 180 181 /* Copy td1's pcb */ 182 bcopy(td1->td_pcb, pcb2, sizeof(*pcb2)); 183 184 /* Properly initialize pcb_save */ 185 pcb2->pcb_save = get_pcb_user_save_pcb(pcb2); 186 bcopy(get_pcb_user_save_td(td1), get_pcb_user_save_pcb(pcb2), 187 cpu_max_ext_state_size); 188 189 /* Point mdproc and then copy over td1's contents */ 190 mdp2 = &p2->p_md; 191 bcopy(&p1->p_md, mdp2, sizeof(*mdp2)); 192 193 /* 194 * Create a new fresh stack for the new process. 195 * Copy the trap frame for the return to user mode as if from a 196 * syscall. This copies most of the user mode register values. 197 */ 198 td2->td_frame = (struct trapframe *)td2->td_pcb - 1; 199 bcopy(td1->td_frame, td2->td_frame, sizeof(struct trapframe)); 200 201 td2->td_frame->tf_rax = 0; /* Child returns zero */ 202 td2->td_frame->tf_rflags &= ~PSL_C; /* success */ 203 td2->td_frame->tf_rdx = 1; 204 205 /* 206 * If the parent process has the trap bit set (i.e. a debugger had 207 * single stepped the process to the system call), we need to clear 208 * the trap flag from the new frame unless the debugger had set PF_FORK 209 * on the parent. Otherwise, the child will receive a (likely 210 * unexpected) SIGTRAP when it executes the first instruction after 211 * returning to userland. 212 */ 213 if ((p1->p_pfsflags & PF_FORK) == 0) 214 td2->td_frame->tf_rflags &= ~PSL_T; 215 216 /* 217 * Set registers for trampoline to user mode. Leave space for the 218 * return address on stack. These are the kernel mode register values. 219 */ 220 pcb2->pcb_r12 = (register_t)fork_return; /* fork_trampoline argument */ 221 pcb2->pcb_rbp = 0; 222 pcb2->pcb_rsp = (register_t)td2->td_frame - sizeof(void *); 223 pcb2->pcb_rbx = (register_t)td2; /* fork_trampoline argument */ 224 pcb2->pcb_rip = (register_t)fork_trampoline; 225 /*- 226 * pcb2->pcb_dr*: cloned above. 227 * pcb2->pcb_savefpu: cloned above. 228 * pcb2->pcb_flags: cloned above. 229 * pcb2->pcb_onfault: cloned above (always NULL here?). 230 * pcb2->pcb_[fg]sbase: cloned above 231 */ 232 233 /* Setup to release spin count in fork_exit(). */ 234 td2->td_md.md_spinlock_count = 1; 235 td2->td_md.md_saved_flags = PSL_KERNEL | PSL_I; 236 237 /* As an i386, do not copy io permission bitmap. */ 238 pcb2->pcb_tssp = NULL; 239 240 /* New segment registers. */ 241 set_pcb_flags(pcb2, PCB_FULL_IRET); 242 243 /* Copy the LDT, if necessary. */ 244 mdp1 = &td1->td_proc->p_md; 245 mdp2 = &p2->p_md; 246 mtx_lock(&dt_lock); 247 if (mdp1->md_ldt != NULL) { 248 if (flags & RFMEM) { 249 mdp1->md_ldt->ldt_refcnt++; 250 mdp2->md_ldt = mdp1->md_ldt; 251 bcopy(&mdp1->md_ldt_sd, &mdp2->md_ldt_sd, sizeof(struct 252 system_segment_descriptor)); 253 } else { 254 mdp2->md_ldt = NULL; 255 mdp2->md_ldt = user_ldt_alloc(p2, 0); 256 if (mdp2->md_ldt == NULL) 257 panic("could not copy LDT"); 258 amd64_set_ldt_data(td2, 0, max_ldt_segment, 259 (struct user_segment_descriptor *) 260 mdp1->md_ldt->ldt_base); 261 } 262 } else 263 mdp2->md_ldt = NULL; 264 mtx_unlock(&dt_lock); 265 266 /* 267 * Now, cpu_switch() can schedule the new process. 268 * pcb_rsp is loaded pointing to the cpu_switch() stack frame 269 * containing the return address when exiting cpu_switch. 270 * This will normally be to fork_trampoline(), which will have 271 * %ebx loaded with the new proc's pointer. fork_trampoline() 272 * will set up a stack to call fork_return(p, frame); to complete 273 * the return to user-mode. 274 */ 275} 276 277/* 278 * Intercept the return address from a freshly forked process that has NOT 279 * been scheduled yet. 280 * 281 * This is needed to make kernel threads stay in kernel mode. 282 */ 283void 284cpu_set_fork_handler(td, func, arg) 285 struct thread *td; 286 void (*func)(void *); 287 void *arg; 288{ 289 /* 290 * Note that the trap frame follows the args, so the function 291 * is really called like this: func(arg, frame); 292 */ 293 td->td_pcb->pcb_r12 = (long) func; /* function */ 294 td->td_pcb->pcb_rbx = (long) arg; /* first arg */ 295} 296 297void 298cpu_exit(struct thread *td) 299{ 300 301 /* 302 * If this process has a custom LDT, release it. 303 */ 304 mtx_lock(&dt_lock); 305 if (td->td_proc->p_md.md_ldt != 0) 306 user_ldt_free(td); 307 else 308 mtx_unlock(&dt_lock); 309} 310 311void 312cpu_thread_exit(struct thread *td) 313{ 314 struct pcb *pcb; 315 316 critical_enter(); 317 if (td == PCPU_GET(fpcurthread)) 318 fpudrop(); 319 critical_exit(); 320 321 pcb = td->td_pcb; 322 323 /* Disable any hardware breakpoints. */ 324 if (pcb->pcb_flags & PCB_DBREGS) { 325 reset_dbregs(); 326 clear_pcb_flags(pcb, PCB_DBREGS); 327 } 328} 329 330void 331cpu_thread_clean(struct thread *td) 332{ 333 struct pcb *pcb; 334 335 pcb = td->td_pcb; 336 337 /* 338 * Clean TSS/iomap 339 */ 340 if (pcb->pcb_tssp != NULL) { 341 kmem_free(kernel_arena, (vm_offset_t)pcb->pcb_tssp, 342 ctob(IOPAGES + 1)); 343 pcb->pcb_tssp = NULL; 344 } 345} 346 347void 348cpu_thread_swapin(struct thread *td) 349{ 350} 351 352void 353cpu_thread_swapout(struct thread *td) 354{ 355} 356 357void 358cpu_thread_alloc(struct thread *td) 359{ 360 struct pcb *pcb; 361 struct xstate_hdr *xhdr; 362 363 td->td_pcb = pcb = get_pcb_td(td); 364 td->td_frame = (struct trapframe *)pcb - 1; 365 pcb->pcb_save = get_pcb_user_save_pcb(pcb); 366 if (use_xsave) { 367 xhdr = (struct xstate_hdr *)(pcb->pcb_save + 1); 368 bzero(xhdr, sizeof(*xhdr)); 369 xhdr->xstate_bv = xsave_mask; 370 } 371} 372 373void 374cpu_thread_free(struct thread *td) 375{ 376 377 cpu_thread_clean(td); 378} 379 380void 381cpu_set_syscall_retval(struct thread *td, int error) 382{ 383 384 switch (error) { 385 case 0: 386 td->td_frame->tf_rax = td->td_retval[0]; 387 td->td_frame->tf_rdx = td->td_retval[1]; 388 td->td_frame->tf_rflags &= ~PSL_C; 389 break; 390 391 case ERESTART: 392 /* 393 * Reconstruct pc, we know that 'syscall' is 2 bytes, 394 * lcall $X,y is 7 bytes, int 0x80 is 2 bytes. 395 * We saved this in tf_err. 396 * %r10 (which was holding the value of %rcx) is restored 397 * for the next iteration. 398 * %r10 restore is only required for freebsd/amd64 processes, 399 * but shall be innocent for any ia32 ABI. 400 * 401 * Require full context restore to get the arguments 402 * in the registers reloaded at return to usermode. 403 */ 404 td->td_frame->tf_rip -= td->td_frame->tf_err; 405 td->td_frame->tf_r10 = td->td_frame->tf_rcx; 406 set_pcb_flags(td->td_pcb, PCB_FULL_IRET); 407 break; 408 409 case EJUSTRETURN: 410 break; 411 412 default: 413 if (td->td_proc->p_sysent->sv_errsize) { 414 if (error >= td->td_proc->p_sysent->sv_errsize) 415 error = -1; /* XXX */ 416 else 417 error = td->td_proc->p_sysent->sv_errtbl[error]; 418 } 419 td->td_frame->tf_rax = error; 420 td->td_frame->tf_rflags |= PSL_C; 421 break; 422 } 423} 424 425/* 426 * Initialize machine state (pcb and trap frame) for a new thread about to 427 * upcall. Put enough state in the new thread's PCB to get it to go back 428 * userret(), where we can intercept it again to set the return (upcall) 429 * Address and stack, along with those from upcals that are from other sources 430 * such as those generated in thread_userret() itself. 431 */ 432void 433cpu_set_upcall(struct thread *td, struct thread *td0) 434{ 435 struct pcb *pcb2; 436 437 /* Point the pcb to the top of the stack. */ 438 pcb2 = td->td_pcb; 439 440 /* 441 * Copy the upcall pcb. This loads kernel regs. 442 * Those not loaded individually below get their default 443 * values here. 444 */ 445 bcopy(td0->td_pcb, pcb2, sizeof(*pcb2)); 446 clear_pcb_flags(pcb2, PCB_FPUINITDONE | PCB_USERFPUINITDONE | 447 PCB_KERNFPU); 448 pcb2->pcb_save = get_pcb_user_save_pcb(pcb2); 449 bcopy(get_pcb_user_save_td(td0), pcb2->pcb_save, 450 cpu_max_ext_state_size); 451 set_pcb_flags(pcb2, PCB_FULL_IRET); 452 453 /* 454 * Create a new fresh stack for the new thread. 455 */ 456 bcopy(td0->td_frame, td->td_frame, sizeof(struct trapframe)); 457 458 /* If the current thread has the trap bit set (i.e. a debugger had 459 * single stepped the process to the system call), we need to clear 460 * the trap flag from the new frame. Otherwise, the new thread will 461 * receive a (likely unexpected) SIGTRAP when it executes the first 462 * instruction after returning to userland. 463 */ 464 td->td_frame->tf_rflags &= ~PSL_T; 465 466 /* 467 * Set registers for trampoline to user mode. Leave space for the 468 * return address on stack. These are the kernel mode register values. 469 */ 470 pcb2->pcb_r12 = (register_t)fork_return; /* trampoline arg */ 471 pcb2->pcb_rbp = 0; 472 pcb2->pcb_rsp = (register_t)td->td_frame - sizeof(void *); /* trampoline arg */ 473 pcb2->pcb_rbx = (register_t)td; /* trampoline arg */ 474 pcb2->pcb_rip = (register_t)fork_trampoline; 475 /* 476 * If we didn't copy the pcb, we'd need to do the following registers: 477 * pcb2->pcb_dr*: cloned above. 478 * pcb2->pcb_savefpu: cloned above. 479 * pcb2->pcb_onfault: cloned above (always NULL here?). 480 * pcb2->pcb_[fg]sbase: cloned above 481 */ 482 483 /* Setup to release spin count in fork_exit(). */ 484 td->td_md.md_spinlock_count = 1; 485 td->td_md.md_saved_flags = PSL_KERNEL | PSL_I; 486} 487 488/* 489 * Set that machine state for performing an upcall that has to 490 * be done in thread_userret() so that those upcalls generated 491 * in thread_userret() itself can be done as well. 492 */ 493void 494cpu_set_upcall_kse(struct thread *td, void (*entry)(void *), void *arg, 495 stack_t *stack) 496{ 497 498 /* 499 * Do any extra cleaning that needs to be done. 500 * The thread may have optional components 501 * that are not present in a fresh thread. 502 * This may be a recycled thread so make it look 503 * as though it's newly allocated. 504 */ 505 cpu_thread_clean(td); 506 507#ifdef COMPAT_FREEBSD32 508 if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) { 509 /* 510 * Set the trap frame to point at the beginning of the uts 511 * function. 512 */ 513 td->td_frame->tf_rbp = 0; 514 td->td_frame->tf_rsp = 515 (((uintptr_t)stack->ss_sp + stack->ss_size - 4) & ~0x0f) - 4; 516 td->td_frame->tf_rip = (uintptr_t)entry; 517 518 /* 519 * Pass the address of the mailbox for this kse to the uts 520 * function as a parameter on the stack. 521 */ 522 suword32((void *)(td->td_frame->tf_rsp + sizeof(int32_t)), 523 (uint32_t)(uintptr_t)arg); 524 525 return; 526 } 527#endif 528 529 /* 530 * Set the trap frame to point at the beginning of the uts 531 * function. 532 */ 533 td->td_frame->tf_rbp = 0; 534 td->td_frame->tf_rsp = 535 ((register_t)stack->ss_sp + stack->ss_size) & ~0x0f; 536 td->td_frame->tf_rsp -= 8; 537 td->td_frame->tf_rip = (register_t)entry; 538 td->td_frame->tf_ds = _udatasel; 539 td->td_frame->tf_es = _udatasel; 540 td->td_frame->tf_fs = _ufssel; 541 td->td_frame->tf_gs = _ugssel; 542 td->td_frame->tf_flags = TF_HASSEGS; 543 544 /* 545 * Pass the address of the mailbox for this kse to the uts 546 * function as a parameter on the stack. 547 */ 548 td->td_frame->tf_rdi = (register_t)arg; 549} 550 551int 552cpu_set_user_tls(struct thread *td, void *tls_base) 553{ 554 struct pcb *pcb; 555 556 if ((u_int64_t)tls_base >= VM_MAXUSER_ADDRESS) 557 return (EINVAL); 558 559 pcb = td->td_pcb; 560 set_pcb_flags(pcb, PCB_FULL_IRET); 561#ifdef COMPAT_FREEBSD32 562 if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) { 563 pcb->pcb_gsbase = (register_t)tls_base; 564 return (0); 565 } 566#endif 567 pcb->pcb_fsbase = (register_t)tls_base; 568 return (0); 569} 570 571#ifdef SMP 572static void 573cpu_reset_proxy() 574{ 575 cpuset_t tcrp; 576 577 cpu_reset_proxy_active = 1; 578 while (cpu_reset_proxy_active == 1) 579 ia32_pause(); /* Wait for other cpu to see that we've started */ 580 581 CPU_SETOF(cpu_reset_proxyid, &tcrp); 582 stop_cpus(tcrp); 583 printf("cpu_reset_proxy: Stopped CPU %d\n", cpu_reset_proxyid); 584 DELAY(1000000); 585 cpu_reset_real(); 586} 587#endif 588 589void 590cpu_reset() 591{ 592#ifdef SMP 593 cpuset_t map; 594 u_int cnt; 595 596 if (smp_started) { 597 map = all_cpus; 598 CPU_CLR(PCPU_GET(cpuid), &map); 599 CPU_NAND(&map, &stopped_cpus); 600 if (!CPU_EMPTY(&map)) { 601 printf("cpu_reset: Stopping other CPUs\n"); 602 stop_cpus(map); 603 } 604 605 if (PCPU_GET(cpuid) != 0) { 606 cpu_reset_proxyid = PCPU_GET(cpuid); 607 cpustop_restartfunc = cpu_reset_proxy; 608 cpu_reset_proxy_active = 0; 609 printf("cpu_reset: Restarting BSP\n"); 610 611 /* Restart CPU #0. */ 612 CPU_SETOF(0, &started_cpus); 613 wmb(); 614 615 cnt = 0; 616 while (cpu_reset_proxy_active == 0 && cnt < 10000000) { 617 ia32_pause(); 618 cnt++; /* Wait for BSP to announce restart */ 619 } 620 if (cpu_reset_proxy_active == 0) 621 printf("cpu_reset: Failed to restart BSP\n"); 622 enable_intr(); 623 cpu_reset_proxy_active = 2; 624 625 while (1) 626 ia32_pause(); 627 /* NOTREACHED */ 628 } 629 630 DELAY(1000000); 631 } 632#endif 633 cpu_reset_real(); 634 /* NOTREACHED */ 635} 636 637static void 638cpu_reset_real() 639{ 640 struct region_descriptor null_idt; 641 int b; 642 643 disable_intr(); 644 645 /* 646 * Attempt to do a CPU reset via the keyboard controller, 647 * do not turn off GateA20, as any machine that fails 648 * to do the reset here would then end up in no man's land. 649 */ 650 outb(IO_KBD + 4, 0xFE); 651 DELAY(500000); /* wait 0.5 sec to see if that did it */ 652 653 /* 654 * Attempt to force a reset via the Reset Control register at 655 * I/O port 0xcf9. Bit 2 forces a system reset when it 656 * transitions from 0 to 1. Bit 1 selects the type of reset 657 * to attempt: 0 selects a "soft" reset, and 1 selects a 658 * "hard" reset. We try a "hard" reset. The first write sets 659 * bit 1 to select a "hard" reset and clears bit 2. The 660 * second write forces a 0 -> 1 transition in bit 2 to trigger 661 * a reset. 662 */ 663 outb(0xcf9, 0x2); 664 outb(0xcf9, 0x6); 665 DELAY(500000); /* wait 0.5 sec to see if that did it */ 666 667 /* 668 * Attempt to force a reset via the Fast A20 and Init register 669 * at I/O port 0x92. Bit 1 serves as an alternate A20 gate. 670 * Bit 0 asserts INIT# when set to 1. We are careful to only 671 * preserve bit 1 while setting bit 0. We also must clear bit 672 * 0 before setting it if it isn't already clear. 673 */ 674 b = inb(0x92); 675 if (b != 0xff) { 676 if ((b & 0x1) != 0) 677 outb(0x92, b & 0xfe); 678 outb(0x92, b | 0x1); 679 DELAY(500000); /* wait 0.5 sec to see if that did it */ 680 } 681 682 printf("No known reset method worked, attempting CPU shutdown\n"); 683 DELAY(1000000); /* wait 1 sec for printf to complete */ 684 685 /* Wipe the IDT. */ 686 null_idt.rd_limit = 0; 687 null_idt.rd_base = 0; 688 lidt(&null_idt); 689 690 /* "good night, sweet prince .... <THUNK!>" */ 691 breakpoint(); 692 693 /* NOTREACHED */ 694 while(1); 695} 696 697/* 698 * Software interrupt handler for queued VM system processing. 699 */ 700void 701swi_vm(void *dummy) 702{ 703 if (busdma_swi_pending != 0) 704 busdma_swi(); 705} 706 707/* 708 * Tell whether this address is in some physical memory region. 709 * Currently used by the kernel coredump code in order to avoid 710 * dumping the ``ISA memory hole'' which could cause indefinite hangs, 711 * or other unpredictable behaviour. 712 */ 713 714int 715is_physical_memory(vm_paddr_t addr) 716{ 717 718#ifdef DEV_ISA 719 /* The ISA ``memory hole''. */ 720 if (addr >= 0xa0000 && addr < 0x100000) 721 return 0; 722#endif 723 724 /* 725 * stuff other tests for known memory-mapped devices (PCI?) 726 * here 727 */ 728 729 return 1; 730} 731