vm_machdep.c revision 331643
1/*- 2 * SPDX-License-Identifier: BSD-4-Clause 3 * 4 * Copyright (c) 1982, 1986 The Regents of the University of California. 5 * Copyright (c) 1989, 1990 William Jolitz 6 * Copyright (c) 1994 John Dyson 7 * All rights reserved. 8 * 9 * This code is derived from software contributed to Berkeley by 10 * the Systems Programming Group of the University of Utah Computer 11 * Science Department, and William Jolitz. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. All advertising materials mentioning features or use of this software 22 * must display the following acknowledgement: 23 * This product includes software developed by the University of 24 * California, Berkeley and its contributors. 25 * 4. Neither the name of the University nor the names of its contributors 26 * may be used to endorse or promote products derived from this software 27 * without specific prior written permission. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 39 * SUCH DAMAGE. 40 * 41 * from: @(#)vm_machdep.c 7.3 (Berkeley) 5/13/91 42 * Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$ 43 */ 44 45#include <sys/cdefs.h> 46__FBSDID("$FreeBSD: stable/11/sys/amd64/amd64/vm_machdep.c 331643 2018-03-27 18:52:27Z dim $"); 47 48#include "opt_isa.h" 49#include "opt_cpu.h" 50#include "opt_compat.h" 51 52#include <sys/param.h> 53#include <sys/systm.h> 54#include <sys/bio.h> 55#include <sys/buf.h> 56#include <sys/kernel.h> 57#include <sys/ktr.h> 58#include <sys/lock.h> 59#include <sys/malloc.h> 60#include <sys/mbuf.h> 61#include <sys/mutex.h> 62#include <sys/pioctl.h> 63#include <sys/proc.h> 64#include <sys/smp.h> 65#include <sys/sysctl.h> 66#include <sys/sysent.h> 67#include <sys/unistd.h> 68#include <sys/vnode.h> 69#include <sys/vmmeter.h> 70 71#include <machine/cpu.h> 72#include <machine/md_var.h> 73#include <machine/pcb.h> 74#include <machine/smp.h> 75#include <machine/specialreg.h> 76#include <machine/tss.h> 77 78#include <vm/vm.h> 79#include <vm/vm_extern.h> 80#include <vm/vm_kern.h> 81#include <vm/vm_page.h> 82#include <vm/vm_map.h> 83#include <vm/vm_param.h> 84 85#include <isa/isareg.h> 86 87static void cpu_reset_real(void); 88#ifdef SMP 89static void cpu_reset_proxy(void); 90static u_int cpu_reset_proxyid; 91static volatile u_int cpu_reset_proxy_active; 92#endif 93 94_Static_assert(OFFSETOF_CURTHREAD == offsetof(struct pcpu, pc_curthread), 95 "OFFSETOF_CURTHREAD does not correspond with offset of pc_curthread."); 96_Static_assert(OFFSETOF_CURPCB == offsetof(struct pcpu, pc_curpcb), 97 "OFFSETOF_CURPCB does not correspond with offset of pc_curpcb."); 98_Static_assert(OFFSETOF_MONITORBUF == offsetof(struct pcpu, pc_monitorbuf), 99 "OFFSETOF_MONINORBUF does not correspond with offset of pc_monitorbuf."); 100 101struct savefpu * 102get_pcb_user_save_td(struct thread *td) 103{ 104 vm_offset_t p; 105 106 p = td->td_kstack + td->td_kstack_pages * PAGE_SIZE - 107 roundup2(cpu_max_ext_state_size, XSAVE_AREA_ALIGN); 108 KASSERT((p % XSAVE_AREA_ALIGN) == 0, ("Unaligned pcb_user_save area")); 109 return ((struct savefpu *)p); 110} 111 112struct savefpu * 113get_pcb_user_save_pcb(struct pcb *pcb) 114{ 115 vm_offset_t p; 116 117 p = (vm_offset_t)(pcb + 1); 118 return ((struct savefpu *)p); 119} 120 121struct pcb * 122get_pcb_td(struct thread *td) 123{ 124 vm_offset_t p; 125 126 p = td->td_kstack + td->td_kstack_pages * PAGE_SIZE - 127 roundup2(cpu_max_ext_state_size, XSAVE_AREA_ALIGN) - 128 sizeof(struct pcb); 129 return ((struct pcb *)p); 130} 131 132void * 133alloc_fpusave(int flags) 134{ 135 void *res; 136 struct savefpu_ymm *sf; 137 138 res = malloc(cpu_max_ext_state_size, M_DEVBUF, flags); 139 if (use_xsave) { 140 sf = (struct savefpu_ymm *)res; 141 bzero(&sf->sv_xstate.sx_hd, sizeof(sf->sv_xstate.sx_hd)); 142 sf->sv_xstate.sx_hd.xstate_bv = xsave_mask; 143 } 144 return (res); 145} 146 147/* 148 * Finish a fork operation, with process p2 nearly set up. 149 * Copy and update the pcb, set up the stack so that the child 150 * ready to run and return to user mode. 151 */ 152void 153cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags) 154{ 155 struct proc *p1; 156 struct pcb *pcb2; 157 struct mdproc *mdp1, *mdp2; 158 struct proc_ldt *pldt; 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 update_pcb_bases(td1->td_pcb); 178 179 /* Point the pcb to the top of the stack */ 180 pcb2 = get_pcb_td(td2); 181 td2->td_pcb = pcb2; 182 183 /* Copy td1's pcb */ 184 bcopy(td1->td_pcb, pcb2, sizeof(*pcb2)); 185 186 /* Properly initialize pcb_save */ 187 pcb2->pcb_save = get_pcb_user_save_pcb(pcb2); 188 bcopy(get_pcb_user_save_td(td1), get_pcb_user_save_pcb(pcb2), 189 cpu_max_ext_state_size); 190 191 /* Point mdproc and then copy over td1's contents */ 192 mdp2 = &p2->p_md; 193 bcopy(&p1->p_md, mdp2, sizeof(*mdp2)); 194 195 /* 196 * Create a new fresh stack for the new process. 197 * Copy the trap frame for the return to user mode as if from a 198 * syscall. This copies most of the user mode register values. 199 */ 200 td2->td_frame = (struct trapframe *)td2->td_pcb - 1; 201 bcopy(td1->td_frame, td2->td_frame, sizeof(struct trapframe)); 202 203 td2->td_frame->tf_rax = 0; /* Child returns zero */ 204 td2->td_frame->tf_rflags &= ~PSL_C; /* success */ 205 td2->td_frame->tf_rdx = 1; 206 207 /* 208 * If the parent process has the trap bit set (i.e. a debugger had 209 * single stepped the process to the system call), we need to clear 210 * the trap flag from the new frame unless the debugger had set PF_FORK 211 * on the parent. Otherwise, the child will receive a (likely 212 * unexpected) SIGTRAP when it executes the first instruction after 213 * returning to userland. 214 */ 215 if ((p1->p_pfsflags & PF_FORK) == 0) 216 td2->td_frame->tf_rflags &= ~PSL_T; 217 218 /* 219 * Set registers for trampoline to user mode. Leave space for the 220 * return address on stack. These are the kernel mode register values. 221 */ 222 pcb2->pcb_r12 = (register_t)fork_return; /* fork_trampoline argument */ 223 pcb2->pcb_rbp = 0; 224 pcb2->pcb_rsp = (register_t)td2->td_frame - sizeof(void *); 225 pcb2->pcb_rbx = (register_t)td2; /* fork_trampoline argument */ 226 pcb2->pcb_rip = (register_t)fork_trampoline; 227 /*- 228 * pcb2->pcb_dr*: cloned above. 229 * pcb2->pcb_savefpu: cloned above. 230 * pcb2->pcb_flags: cloned above. 231 * pcb2->pcb_onfault: cloned above (always NULL here?). 232 * pcb2->pcb_[fg]sbase: cloned above 233 */ 234 235 /* Setup to release spin count in fork_exit(). */ 236 td2->td_md.md_spinlock_count = 1; 237 td2->td_md.md_saved_flags = PSL_KERNEL | PSL_I; 238 td2->td_md.md_invl_gen.gen = 0; 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_raw(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_fork_kthread_handler(struct thread *td, void (*func)(void *), 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 pmap_pti_remove_kva((vm_offset_t)pcb->pcb_tssp, 342 (vm_offset_t)pcb->pcb_tssp + ctob(IOPAGES + 1)); 343 kmem_free(kernel_arena, (vm_offset_t)pcb->pcb_tssp, 344 ctob(IOPAGES + 1)); 345 pcb->pcb_tssp = NULL; 346 } 347} 348 349void 350cpu_thread_swapin(struct thread *td) 351{ 352} 353 354void 355cpu_thread_swapout(struct thread *td) 356{ 357} 358 359void 360cpu_thread_alloc(struct thread *td) 361{ 362 struct pcb *pcb; 363 struct xstate_hdr *xhdr; 364 365 td->td_pcb = pcb = get_pcb_td(td); 366 td->td_frame = (struct trapframe *)pcb - 1; 367 pcb->pcb_save = get_pcb_user_save_pcb(pcb); 368 if (use_xsave) { 369 xhdr = (struct xstate_hdr *)(pcb->pcb_save + 1); 370 bzero(xhdr, sizeof(*xhdr)); 371 xhdr->xstate_bv = xsave_mask; 372 } 373} 374 375void 376cpu_thread_free(struct thread *td) 377{ 378 379 cpu_thread_clean(td); 380} 381 382void 383cpu_set_syscall_retval(struct thread *td, int error) 384{ 385 386 switch (error) { 387 case 0: 388 td->td_frame->tf_rax = td->td_retval[0]; 389 td->td_frame->tf_rdx = td->td_retval[1]; 390 td->td_frame->tf_rflags &= ~PSL_C; 391 break; 392 393 case ERESTART: 394 /* 395 * Reconstruct pc, we know that 'syscall' is 2 bytes, 396 * lcall $X,y is 7 bytes, int 0x80 is 2 bytes. 397 * We saved this in tf_err. 398 * %r10 (which was holding the value of %rcx) is restored 399 * for the next iteration. 400 * %r10 restore is only required for freebsd/amd64 processes, 401 * but shall be innocent for any ia32 ABI. 402 * 403 * Require full context restore to get the arguments 404 * in the registers reloaded at return to usermode. 405 */ 406 td->td_frame->tf_rip -= td->td_frame->tf_err; 407 td->td_frame->tf_r10 = td->td_frame->tf_rcx; 408 set_pcb_flags(td->td_pcb, PCB_FULL_IRET); 409 break; 410 411 case EJUSTRETURN: 412 break; 413 414 default: 415 td->td_frame->tf_rax = SV_ABI_ERRNO(td->td_proc, error); 416 td->td_frame->tf_rflags |= PSL_C; 417 break; 418 } 419} 420 421/* 422 * Initialize machine state, mostly pcb and trap frame for a new 423 * thread, about to return to userspace. Put enough state in the new 424 * thread's PCB to get it to go back to the fork_return(), which 425 * finalizes the thread state and handles peculiarities of the first 426 * return to userspace for the new thread. 427 */ 428void 429cpu_copy_thread(struct thread *td, struct thread *td0) 430{ 431 struct pcb *pcb2; 432 433 /* Point the pcb to the top of the stack. */ 434 pcb2 = td->td_pcb; 435 436 /* 437 * Copy the upcall pcb. This loads kernel regs. 438 * Those not loaded individually below get their default 439 * values here. 440 */ 441 update_pcb_bases(td0->td_pcb); 442 bcopy(td0->td_pcb, pcb2, sizeof(*pcb2)); 443 clear_pcb_flags(pcb2, PCB_FPUINITDONE | PCB_USERFPUINITDONE | 444 PCB_KERNFPU); 445 pcb2->pcb_save = get_pcb_user_save_pcb(pcb2); 446 bcopy(get_pcb_user_save_td(td0), pcb2->pcb_save, 447 cpu_max_ext_state_size); 448 set_pcb_flags_raw(pcb2, PCB_FULL_IRET); 449 450 /* 451 * Create a new fresh stack for the new thread. 452 */ 453 bcopy(td0->td_frame, td->td_frame, sizeof(struct trapframe)); 454 455 /* If the current thread has the trap bit set (i.e. a debugger had 456 * single stepped the process to the system call), we need to clear 457 * the trap flag from the new frame. Otherwise, the new thread will 458 * receive a (likely unexpected) SIGTRAP when it executes the first 459 * instruction after returning to userland. 460 */ 461 td->td_frame->tf_rflags &= ~PSL_T; 462 463 /* 464 * Set registers for trampoline to user mode. Leave space for the 465 * return address on stack. These are the kernel mode register values. 466 */ 467 pcb2->pcb_r12 = (register_t)fork_return; /* trampoline arg */ 468 pcb2->pcb_rbp = 0; 469 pcb2->pcb_rsp = (register_t)td->td_frame - sizeof(void *); /* trampoline arg */ 470 pcb2->pcb_rbx = (register_t)td; /* trampoline arg */ 471 pcb2->pcb_rip = (register_t)fork_trampoline; 472 /* 473 * If we didn't copy the pcb, we'd need to do the following registers: 474 * pcb2->pcb_dr*: cloned above. 475 * pcb2->pcb_savefpu: cloned above. 476 * pcb2->pcb_onfault: cloned above (always NULL here?). 477 * pcb2->pcb_[fg]sbase: cloned above 478 */ 479 480 /* Setup to release spin count in fork_exit(). */ 481 td->td_md.md_spinlock_count = 1; 482 td->td_md.md_saved_flags = PSL_KERNEL | PSL_I; 483} 484 485/* 486 * Set that machine state for performing an upcall that starts 487 * the entry function with the given argument. 488 */ 489void 490cpu_set_upcall(struct thread *td, void (*entry)(void *), void *arg, 491 stack_t *stack) 492{ 493 494 /* 495 * Do any extra cleaning that needs to be done. 496 * The thread may have optional components 497 * that are not present in a fresh thread. 498 * This may be a recycled thread so make it look 499 * as though it's newly allocated. 500 */ 501 cpu_thread_clean(td); 502 503#ifdef COMPAT_FREEBSD32 504 if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) { 505 /* 506 * Set the trap frame to point at the beginning of the entry 507 * function. 508 */ 509 td->td_frame->tf_rbp = 0; 510 td->td_frame->tf_rsp = 511 (((uintptr_t)stack->ss_sp + stack->ss_size - 4) & ~0x0f) - 4; 512 td->td_frame->tf_rip = (uintptr_t)entry; 513 514 /* Return address sentinel value to stop stack unwinding. */ 515 suword32((void *)td->td_frame->tf_rsp, 0); 516 517 /* Pass the argument to the entry point. */ 518 suword32((void *)(td->td_frame->tf_rsp + sizeof(int32_t)), 519 (uint32_t)(uintptr_t)arg); 520 521 return; 522 } 523#endif 524 525 /* 526 * Set the trap frame to point at the beginning of the uts 527 * function. 528 */ 529 td->td_frame->tf_rbp = 0; 530 td->td_frame->tf_rsp = 531 ((register_t)stack->ss_sp + stack->ss_size) & ~0x0f; 532 td->td_frame->tf_rsp -= 8; 533 td->td_frame->tf_rip = (register_t)entry; 534 td->td_frame->tf_ds = _udatasel; 535 td->td_frame->tf_es = _udatasel; 536 td->td_frame->tf_fs = _ufssel; 537 td->td_frame->tf_gs = _ugssel; 538 td->td_frame->tf_flags = TF_HASSEGS; 539 540 /* Return address sentinel value to stop stack unwinding. */ 541 suword((void *)td->td_frame->tf_rsp, 0); 542 543 /* Pass the argument to the entry point. */ 544 td->td_frame->tf_rdi = (register_t)arg; 545} 546 547int 548cpu_set_user_tls(struct thread *td, void *tls_base) 549{ 550 struct pcb *pcb; 551 552 if ((u_int64_t)tls_base >= VM_MAXUSER_ADDRESS) 553 return (EINVAL); 554 555 pcb = td->td_pcb; 556 set_pcb_flags(pcb, PCB_FULL_IRET); 557#ifdef COMPAT_FREEBSD32 558 if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) { 559 pcb->pcb_gsbase = (register_t)tls_base; 560 return (0); 561 } 562#endif 563 pcb->pcb_fsbase = (register_t)tls_base; 564 return (0); 565} 566 567#ifdef SMP 568static void 569cpu_reset_proxy() 570{ 571 cpuset_t tcrp; 572 573 cpu_reset_proxy_active = 1; 574 while (cpu_reset_proxy_active == 1) 575 ia32_pause(); /* Wait for other cpu to see that we've started */ 576 577 CPU_SETOF(cpu_reset_proxyid, &tcrp); 578 stop_cpus(tcrp); 579 printf("cpu_reset_proxy: Stopped CPU %d\n", cpu_reset_proxyid); 580 DELAY(1000000); 581 cpu_reset_real(); 582} 583#endif 584 585void 586cpu_reset() 587{ 588#ifdef SMP 589 cpuset_t map; 590 u_int cnt; 591 592 if (smp_started) { 593 map = all_cpus; 594 CPU_CLR(PCPU_GET(cpuid), &map); 595 CPU_NAND(&map, &stopped_cpus); 596 if (!CPU_EMPTY(&map)) { 597 printf("cpu_reset: Stopping other CPUs\n"); 598 stop_cpus(map); 599 } 600 601 if (PCPU_GET(cpuid) != 0) { 602 cpu_reset_proxyid = PCPU_GET(cpuid); 603 cpustop_restartfunc = cpu_reset_proxy; 604 cpu_reset_proxy_active = 0; 605 printf("cpu_reset: Restarting BSP\n"); 606 607 /* Restart CPU #0. */ 608 CPU_SETOF(0, &started_cpus); 609 wmb(); 610 611 cnt = 0; 612 while (cpu_reset_proxy_active == 0 && cnt < 10000000) { 613 ia32_pause(); 614 cnt++; /* Wait for BSP to announce restart */ 615 } 616 if (cpu_reset_proxy_active == 0) 617 printf("cpu_reset: Failed to restart BSP\n"); 618 enable_intr(); 619 cpu_reset_proxy_active = 2; 620 621 while (1) 622 ia32_pause(); 623 /* NOTREACHED */ 624 } 625 626 DELAY(1000000); 627 } 628#endif 629 cpu_reset_real(); 630 /* NOTREACHED */ 631} 632 633static void 634cpu_reset_real() 635{ 636 struct region_descriptor null_idt; 637 int b; 638 639 disable_intr(); 640 641 /* 642 * Attempt to do a CPU reset via the keyboard controller, 643 * do not turn off GateA20, as any machine that fails 644 * to do the reset here would then end up in no man's land. 645 */ 646 outb(IO_KBD + 4, 0xFE); 647 DELAY(500000); /* wait 0.5 sec to see if that did it */ 648 649 /* 650 * Attempt to force a reset via the Reset Control register at 651 * I/O port 0xcf9. Bit 2 forces a system reset when it 652 * transitions from 0 to 1. Bit 1 selects the type of reset 653 * to attempt: 0 selects a "soft" reset, and 1 selects a 654 * "hard" reset. We try a "hard" reset. The first write sets 655 * bit 1 to select a "hard" reset and clears bit 2. The 656 * second write forces a 0 -> 1 transition in bit 2 to trigger 657 * a reset. 658 */ 659 outb(0xcf9, 0x2); 660 outb(0xcf9, 0x6); 661 DELAY(500000); /* wait 0.5 sec to see if that did it */ 662 663 /* 664 * Attempt to force a reset via the Fast A20 and Init register 665 * at I/O port 0x92. Bit 1 serves as an alternate A20 gate. 666 * Bit 0 asserts INIT# when set to 1. We are careful to only 667 * preserve bit 1 while setting bit 0. We also must clear bit 668 * 0 before setting it if it isn't already clear. 669 */ 670 b = inb(0x92); 671 if (b != 0xff) { 672 if ((b & 0x1) != 0) 673 outb(0x92, b & 0xfe); 674 outb(0x92, b | 0x1); 675 DELAY(500000); /* wait 0.5 sec to see if that did it */ 676 } 677 678 printf("No known reset method worked, attempting CPU shutdown\n"); 679 DELAY(1000000); /* wait 1 sec for printf to complete */ 680 681 /* Wipe the IDT. */ 682 null_idt.rd_limit = 0; 683 null_idt.rd_base = 0; 684 lidt(&null_idt); 685 686 /* "good night, sweet prince .... <THUNK!>" */ 687 breakpoint(); 688 689 /* NOTREACHED */ 690 while(1); 691} 692 693/* 694 * Software interrupt handler for queued VM system processing. 695 */ 696void 697swi_vm(void *dummy) 698{ 699 if (busdma_swi_pending != 0) 700 busdma_swi(); 701} 702 703/* 704 * Tell whether this address is in some physical memory region. 705 * Currently used by the kernel coredump code in order to avoid 706 * dumping the ``ISA memory hole'' which could cause indefinite hangs, 707 * or other unpredictable behaviour. 708 */ 709 710int 711is_physical_memory(vm_paddr_t addr) 712{ 713 714#ifdef DEV_ISA 715 /* The ISA ``memory hole''. */ 716 if (addr >= 0xa0000 && addr < 0x100000) 717 return 0; 718#endif 719 720 /* 721 * stuff other tests for known memory-mapped devices (PCI?) 722 * here 723 */ 724 725 return 1; 726} 727