vm_machdep.c revision 255289
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 255289 2013-09-06 05:37:49Z glebius $"); 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 <x86/isa/isa.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 struct pcb *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 pmap_t pmap2; 159 160 p1 = td1->td_proc; 161 if ((flags & RFPROC) == 0) { 162 if ((flags & RFMEM) == 0) { 163 /* unshare user LDT */ 164 mdp1 = &p1->p_md; 165 mtx_lock(&dt_lock); 166 if ((pldt = mdp1->md_ldt) != NULL && 167 pldt->ldt_refcnt > 1 && 168 user_ldt_alloc(p1, 1) == NULL) 169 panic("could not copy LDT"); 170 mtx_unlock(&dt_lock); 171 } 172 return; 173 } 174 175 /* Ensure that td1's pcb is up to date. */ 176 fpuexit(td1); 177 178 /* Point the pcb to the top of the stack */ 179 pcb2 = get_pcb_td(td2); 180 td2->td_pcb = pcb2; 181 182 /* Copy td1's pcb */ 183 bcopy(td1->td_pcb, pcb2, sizeof(*pcb2)); 184 185 /* Properly initialize pcb_save */ 186 pcb2->pcb_save = get_pcb_user_save_pcb(pcb2); 187 bcopy(get_pcb_user_save_td(td1), get_pcb_user_save_pcb(pcb2), 188 cpu_max_ext_state_size); 189 190 /* Point mdproc and then copy over td1's contents */ 191 mdp2 = &p2->p_md; 192 bcopy(&p1->p_md, mdp2, sizeof(*mdp2)); 193 194 /* 195 * Create a new fresh stack for the new process. 196 * Copy the trap frame for the return to user mode as if from a 197 * syscall. This copies most of the user mode register values. 198 */ 199 td2->td_frame = (struct trapframe *)td2->td_pcb - 1; 200 bcopy(td1->td_frame, td2->td_frame, sizeof(struct trapframe)); 201 202 td2->td_frame->tf_rax = 0; /* Child returns zero */ 203 td2->td_frame->tf_rflags &= ~PSL_C; /* success */ 204 td2->td_frame->tf_rdx = 1; 205 206 /* 207 * If the parent process has the trap bit set (i.e. a debugger had 208 * single stepped the process to the system call), we need to clear 209 * the trap flag from the new frame unless the debugger had set PF_FORK 210 * on the parent. Otherwise, the child will receive a (likely 211 * unexpected) SIGTRAP when it executes the first instruction after 212 * returning to userland. 213 */ 214 if ((p1->p_pfsflags & PF_FORK) == 0) 215 td2->td_frame->tf_rflags &= ~PSL_T; 216 217 /* 218 * Set registers for trampoline to user mode. Leave space for the 219 * return address on stack. These are the kernel mode register values. 220 */ 221 pmap2 = vmspace_pmap(p2->p_vmspace); 222 pcb2->pcb_cr3 = pmap2->pm_cr3; 223 pcb2->pcb_r12 = (register_t)fork_return; /* fork_trampoline argument */ 224 pcb2->pcb_rbp = 0; 225 pcb2->pcb_rsp = (register_t)td2->td_frame - sizeof(void *); 226 pcb2->pcb_rbx = (register_t)td2; /* fork_trampoline argument */ 227 pcb2->pcb_rip = (register_t)fork_trampoline; 228 /*- 229 * pcb2->pcb_dr*: cloned above. 230 * pcb2->pcb_savefpu: cloned above. 231 * pcb2->pcb_flags: cloned above. 232 * pcb2->pcb_onfault: cloned above (always NULL here?). 233 * pcb2->pcb_[fg]sbase: cloned above 234 */ 235 236 /* Setup to release spin count in fork_exit(). */ 237 td2->td_md.md_spinlock_count = 1; 238 td2->td_md.md_saved_flags = PSL_KERNEL | PSL_I; 239 240 /* As an i386, do not copy io permission bitmap. */ 241 pcb2->pcb_tssp = NULL; 242 243 /* New segment registers. */ 244 set_pcb_flags(pcb2, PCB_FULL_IRET); 245 246 /* Copy the LDT, if necessary. */ 247 mdp1 = &td1->td_proc->p_md; 248 mdp2 = &p2->p_md; 249 mtx_lock(&dt_lock); 250 if (mdp1->md_ldt != NULL) { 251 if (flags & RFMEM) { 252 mdp1->md_ldt->ldt_refcnt++; 253 mdp2->md_ldt = mdp1->md_ldt; 254 bcopy(&mdp1->md_ldt_sd, &mdp2->md_ldt_sd, sizeof(struct 255 system_segment_descriptor)); 256 } else { 257 mdp2->md_ldt = NULL; 258 mdp2->md_ldt = user_ldt_alloc(p2, 0); 259 if (mdp2->md_ldt == NULL) 260 panic("could not copy LDT"); 261 amd64_set_ldt_data(td2, 0, max_ldt_segment, 262 (struct user_segment_descriptor *) 263 mdp1->md_ldt->ldt_base); 264 } 265 } else 266 mdp2->md_ldt = NULL; 267 mtx_unlock(&dt_lock); 268 269 /* 270 * Now, cpu_switch() can schedule the new process. 271 * pcb_rsp is loaded pointing to the cpu_switch() stack frame 272 * containing the return address when exiting cpu_switch. 273 * This will normally be to fork_trampoline(), which will have 274 * %ebx loaded with the new proc's pointer. fork_trampoline() 275 * will set up a stack to call fork_return(p, frame); to complete 276 * the return to user-mode. 277 */ 278} 279 280/* 281 * Intercept the return address from a freshly forked process that has NOT 282 * been scheduled yet. 283 * 284 * This is needed to make kernel threads stay in kernel mode. 285 */ 286void 287cpu_set_fork_handler(td, func, arg) 288 struct thread *td; 289 void (*func)(void *); 290 void *arg; 291{ 292 /* 293 * Note that the trap frame follows the args, so the function 294 * is really called like this: func(arg, frame); 295 */ 296 td->td_pcb->pcb_r12 = (long) func; /* function */ 297 td->td_pcb->pcb_rbx = (long) arg; /* first arg */ 298} 299 300void 301cpu_exit(struct thread *td) 302{ 303 304 /* 305 * If this process has a custom LDT, release it. 306 */ 307 mtx_lock(&dt_lock); 308 if (td->td_proc->p_md.md_ldt != 0) 309 user_ldt_free(td); 310 else 311 mtx_unlock(&dt_lock); 312} 313 314void 315cpu_thread_exit(struct thread *td) 316{ 317 struct pcb *pcb; 318 319 critical_enter(); 320 if (td == PCPU_GET(fpcurthread)) 321 fpudrop(); 322 critical_exit(); 323 324 pcb = td->td_pcb; 325 326 /* Disable any hardware breakpoints. */ 327 if (pcb->pcb_flags & PCB_DBREGS) { 328 reset_dbregs(); 329 clear_pcb_flags(pcb, PCB_DBREGS); 330 } 331} 332 333void 334cpu_thread_clean(struct thread *td) 335{ 336 struct pcb *pcb; 337 338 pcb = td->td_pcb; 339 340 /* 341 * Clean TSS/iomap 342 */ 343 if (pcb->pcb_tssp != NULL) { 344 kva_free((vm_offset_t)pcb->pcb_tssp, 345 ctob(IOPAGES + 1)); 346 pcb->pcb_tssp = NULL; 347 } 348} 349 350void 351cpu_thread_swapin(struct thread *td) 352{ 353} 354 355void 356cpu_thread_swapout(struct thread *td) 357{ 358} 359 360void 361cpu_thread_alloc(struct thread *td) 362{ 363 struct pcb *pcb; 364 struct xstate_hdr *xhdr; 365 366 td->td_pcb = pcb = get_pcb_td(td); 367 td->td_frame = (struct trapframe *)pcb - 1; 368 pcb->pcb_save = get_pcb_user_save_pcb(pcb); 369 if (use_xsave) { 370 xhdr = (struct xstate_hdr *)(pcb->pcb_save + 1); 371 bzero(xhdr, sizeof(*xhdr)); 372 xhdr->xstate_bv = xsave_mask; 373 } 374} 375 376void 377cpu_thread_free(struct thread *td) 378{ 379 380 cpu_thread_clean(td); 381} 382 383void 384cpu_set_syscall_retval(struct thread *td, int error) 385{ 386 387 switch (error) { 388 case 0: 389 td->td_frame->tf_rax = td->td_retval[0]; 390 td->td_frame->tf_rdx = td->td_retval[1]; 391 td->td_frame->tf_rflags &= ~PSL_C; 392 break; 393 394 case ERESTART: 395 /* 396 * Reconstruct pc, we know that 'syscall' is 2 bytes, 397 * lcall $X,y is 7 bytes, int 0x80 is 2 bytes. 398 * We saved this in tf_err. 399 * %r10 (which was holding the value of %rcx) is restored 400 * for the next iteration. 401 * %r10 restore is only required for freebsd/amd64 processes, 402 * but shall be innocent for any ia32 ABI. 403 */ 404 td->td_frame->tf_rip -= td->td_frame->tf_err; 405 td->td_frame->tf_r10 = td->td_frame->tf_rcx; 406 break; 407 408 case EJUSTRETURN: 409 break; 410 411 default: 412 if (td->td_proc->p_sysent->sv_errsize) { 413 if (error >= td->td_proc->p_sysent->sv_errsize) 414 error = -1; /* XXX */ 415 else 416 error = td->td_proc->p_sysent->sv_errtbl[error]; 417 } 418 td->td_frame->tf_rax = error; 419 td->td_frame->tf_rflags |= PSL_C; 420 break; 421 } 422} 423 424/* 425 * Initialize machine state (pcb and trap frame) for a new thread about to 426 * upcall. Put enough state in the new thread's PCB to get it to go back 427 * userret(), where we can intercept it again to set the return (upcall) 428 * Address and stack, along with those from upcals that are from other sources 429 * such as those generated in thread_userret() itself. 430 */ 431void 432cpu_set_upcall(struct thread *td, struct thread *td0) 433{ 434 struct pcb *pcb2; 435 436 /* Point the pcb to the top of the stack. */ 437 pcb2 = td->td_pcb; 438 439 /* 440 * Copy the upcall pcb. This loads kernel regs. 441 * Those not loaded individually below get their default 442 * values here. 443 */ 444 bcopy(td0->td_pcb, pcb2, sizeof(*pcb2)); 445 clear_pcb_flags(pcb2, PCB_FPUINITDONE | PCB_USERFPUINITDONE); 446 pcb2->pcb_save = get_pcb_user_save_pcb(pcb2); 447 bcopy(get_pcb_user_save_td(td0), pcb2->pcb_save, 448 cpu_max_ext_state_size); 449 set_pcb_flags(pcb2, PCB_FULL_IRET); 450 451 /* 452 * Create a new fresh stack for the new thread. 453 */ 454 bcopy(td0->td_frame, td->td_frame, sizeof(struct trapframe)); 455 456 /* If the current thread has the trap bit set (i.e. a debugger had 457 * single stepped the process to the system call), we need to clear 458 * the trap flag from the new frame. Otherwise, the new thread will 459 * receive a (likely unexpected) SIGTRAP when it executes the first 460 * instruction after returning to userland. 461 */ 462 td->td_frame->tf_rflags &= ~PSL_T; 463 464 /* 465 * Set registers for trampoline to user mode. Leave space for the 466 * return address on stack. These are the kernel mode register values. 467 */ 468 pcb2->pcb_r12 = (register_t)fork_return; /* trampoline arg */ 469 pcb2->pcb_rbp = 0; 470 pcb2->pcb_rsp = (register_t)td->td_frame - sizeof(void *); /* trampoline arg */ 471 pcb2->pcb_rbx = (register_t)td; /* trampoline arg */ 472 pcb2->pcb_rip = (register_t)fork_trampoline; 473 /* 474 * If we didn't copy the pcb, we'd need to do the following registers: 475 * pcb2->pcb_cr3: cloned above. 476 * pcb2->pcb_dr*: cloned above. 477 * pcb2->pcb_savefpu: cloned above. 478 * pcb2->pcb_onfault: cloned above (always NULL here?). 479 * pcb2->pcb_[fg]sbase: cloned above 480 */ 481 482 /* Setup to release spin count in fork_exit(). */ 483 td->td_md.md_spinlock_count = 1; 484 td->td_md.md_saved_flags = PSL_KERNEL | PSL_I; 485} 486 487/* 488 * Set that machine state for performing an upcall that has to 489 * be done in thread_userret() so that those upcalls generated 490 * in thread_userret() itself can be done as well. 491 */ 492void 493cpu_set_upcall_kse(struct thread *td, void (*entry)(void *), void *arg, 494 stack_t *stack) 495{ 496 497 /* 498 * Do any extra cleaning that needs to be done. 499 * The thread may have optional components 500 * that are not present in a fresh thread. 501 * This may be a recycled thread so make it look 502 * as though it's newly allocated. 503 */ 504 cpu_thread_clean(td); 505 506#ifdef COMPAT_FREEBSD32 507 if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) { 508 /* 509 * Set the trap frame to point at the beginning of the uts 510 * function. 511 */ 512 td->td_frame->tf_rbp = 0; 513 td->td_frame->tf_rsp = 514 (((uintptr_t)stack->ss_sp + stack->ss_size - 4) & ~0x0f) - 4; 515 td->td_frame->tf_rip = (uintptr_t)entry; 516 517 /* 518 * Pass the address of the mailbox for this kse to the uts 519 * function as a parameter on the stack. 520 */ 521 suword32((void *)(td->td_frame->tf_rsp + sizeof(int32_t)), 522 (uint32_t)(uintptr_t)arg); 523 524 return; 525 } 526#endif 527 528 /* 529 * Set the trap frame to point at the beginning of the uts 530 * function. 531 */ 532 td->td_frame->tf_rbp = 0; 533 td->td_frame->tf_rsp = 534 ((register_t)stack->ss_sp + stack->ss_size) & ~0x0f; 535 td->td_frame->tf_rsp -= 8; 536 td->td_frame->tf_rip = (register_t)entry; 537 td->td_frame->tf_ds = _udatasel; 538 td->td_frame->tf_es = _udatasel; 539 td->td_frame->tf_fs = _ufssel; 540 td->td_frame->tf_gs = _ugssel; 541 td->td_frame->tf_flags = TF_HASSEGS; 542 543 /* 544 * Pass the address of the mailbox for this kse to the uts 545 * function as a parameter on the stack. 546 */ 547 td->td_frame->tf_rdi = (register_t)arg; 548} 549 550int 551cpu_set_user_tls(struct thread *td, void *tls_base) 552{ 553 struct pcb *pcb; 554 555 if ((u_int64_t)tls_base >= VM_MAXUSER_ADDRESS) 556 return (EINVAL); 557 558 pcb = td->td_pcb; 559 set_pcb_flags(pcb, PCB_FULL_IRET); 560#ifdef COMPAT_FREEBSD32 561 if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) { 562 pcb->pcb_gsbase = (register_t)tls_base; 563 return (0); 564 } 565#endif 566 pcb->pcb_fsbase = (register_t)tls_base; 567 return (0); 568} 569 570#ifdef SMP 571static void 572cpu_reset_proxy() 573{ 574 cpuset_t tcrp; 575 576 cpu_reset_proxy_active = 1; 577 while (cpu_reset_proxy_active == 1) 578 ia32_pause(); /* Wait for other cpu to see that we've started */ 579 580 CPU_SETOF(cpu_reset_proxyid, &tcrp); 581 stop_cpus(tcrp); 582 printf("cpu_reset_proxy: Stopped CPU %d\n", cpu_reset_proxyid); 583 DELAY(1000000); 584 cpu_reset_real(); 585} 586#endif 587 588void 589cpu_reset() 590{ 591#ifdef SMP 592 cpuset_t map; 593 u_int cnt; 594 595 if (smp_active) { 596 map = all_cpus; 597 CPU_CLR(PCPU_GET(cpuid), &map); 598 CPU_NAND(&map, &stopped_cpus); 599 if (!CPU_EMPTY(&map)) { 600 printf("cpu_reset: Stopping other CPUs\n"); 601 stop_cpus(map); 602 } 603 604 if (PCPU_GET(cpuid) != 0) { 605 cpu_reset_proxyid = PCPU_GET(cpuid); 606 cpustop_restartfunc = cpu_reset_proxy; 607 cpu_reset_proxy_active = 0; 608 printf("cpu_reset: Restarting BSP\n"); 609 610 /* Restart CPU #0. */ 611 CPU_SETOF(0, &started_cpus); 612 wmb(); 613 614 cnt = 0; 615 while (cpu_reset_proxy_active == 0 && cnt < 10000000) { 616 ia32_pause(); 617 cnt++; /* Wait for BSP to announce restart */ 618 } 619 if (cpu_reset_proxy_active == 0) 620 printf("cpu_reset: Failed to restart BSP\n"); 621 enable_intr(); 622 cpu_reset_proxy_active = 2; 623 624 while (1) 625 ia32_pause(); 626 /* NOTREACHED */ 627 } 628 629 DELAY(1000000); 630 } 631#endif 632 cpu_reset_real(); 633 /* NOTREACHED */ 634} 635 636static void 637cpu_reset_real() 638{ 639 struct region_descriptor null_idt; 640 int b; 641 642 disable_intr(); 643 644 /* 645 * Attempt to do a CPU reset via the keyboard controller, 646 * do not turn off GateA20, as any machine that fails 647 * to do the reset here would then end up in no man's land. 648 */ 649 outb(IO_KBD + 4, 0xFE); 650 DELAY(500000); /* wait 0.5 sec to see if that did it */ 651 652 /* 653 * Attempt to force a reset via the Reset Control register at 654 * I/O port 0xcf9. Bit 2 forces a system reset when it 655 * transitions from 0 to 1. Bit 1 selects the type of reset 656 * to attempt: 0 selects a "soft" reset, and 1 selects a 657 * "hard" reset. We try a "hard" reset. The first write sets 658 * bit 1 to select a "hard" reset and clears bit 2. The 659 * second write forces a 0 -> 1 transition in bit 2 to trigger 660 * a reset. 661 */ 662 outb(0xcf9, 0x2); 663 outb(0xcf9, 0x6); 664 DELAY(500000); /* wait 0.5 sec to see if that did it */ 665 666 /* 667 * Attempt to force a reset via the Fast A20 and Init register 668 * at I/O port 0x92. Bit 1 serves as an alternate A20 gate. 669 * Bit 0 asserts INIT# when set to 1. We are careful to only 670 * preserve bit 1 while setting bit 0. We also must clear bit 671 * 0 before setting it if it isn't already clear. 672 */ 673 b = inb(0x92); 674 if (b != 0xff) { 675 if ((b & 0x1) != 0) 676 outb(0x92, b & 0xfe); 677 outb(0x92, b | 0x1); 678 DELAY(500000); /* wait 0.5 sec to see if that did it */ 679 } 680 681 printf("No known reset method worked, attempting CPU shutdown\n"); 682 DELAY(1000000); /* wait 1 sec for printf to complete */ 683 684 /* Wipe the IDT. */ 685 null_idt.rd_limit = 0; 686 null_idt.rd_base = 0; 687 lidt(&null_idt); 688 689 /* "good night, sweet prince .... <THUNK!>" */ 690 breakpoint(); 691 692 /* NOTREACHED */ 693 while(1); 694} 695 696/* 697 * Software interrupt handler for queued VM system processing. 698 */ 699void 700swi_vm(void *dummy) 701{ 702 if (busdma_swi_pending != 0) 703 busdma_swi(); 704} 705 706/* 707 * Tell whether this address is in some physical memory region. 708 * Currently used by the kernel coredump code in order to avoid 709 * dumping the ``ISA memory hole'' which could cause indefinite hangs, 710 * or other unpredictable behaviour. 711 */ 712 713int 714is_physical_memory(vm_paddr_t addr) 715{ 716 717#ifdef DEV_ISA 718 /* The ISA ``memory hole''. */ 719 if (addr >= 0xa0000 && addr < 0x100000) 720 return 0; 721#endif 722 723 /* 724 * stuff other tests for known memory-mapped devices (PCI?) 725 * here 726 */ 727 728 return 1; 729} 730