vm_machdep.c revision 330897
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 330897 2018-03-14 03:19:51Z eadler $"); 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(td1, p2, td2, flags) 154 register struct thread *td1; 155 register struct proc *p2; 156 struct thread *td2; 157 int flags; 158{ 159 register struct proc *p1; 160 struct pcb *pcb2; 161 struct mdproc *mdp1, *mdp2; 162 struct proc_ldt *pldt; 163 164 p1 = td1->td_proc; 165 if ((flags & RFPROC) == 0) { 166 if ((flags & RFMEM) == 0) { 167 /* unshare user LDT */ 168 mdp1 = &p1->p_md; 169 mtx_lock(&dt_lock); 170 if ((pldt = mdp1->md_ldt) != NULL && 171 pldt->ldt_refcnt > 1 && 172 user_ldt_alloc(p1, 1) == NULL) 173 panic("could not copy LDT"); 174 mtx_unlock(&dt_lock); 175 } 176 return; 177 } 178 179 /* Ensure that td1's pcb is up to date. */ 180 fpuexit(td1); 181 update_pcb_bases(td1->td_pcb); 182 183 /* Point the pcb to the top of the stack */ 184 pcb2 = get_pcb_td(td2); 185 td2->td_pcb = pcb2; 186 187 /* Copy td1's pcb */ 188 bcopy(td1->td_pcb, pcb2, sizeof(*pcb2)); 189 190 /* Properly initialize pcb_save */ 191 pcb2->pcb_save = get_pcb_user_save_pcb(pcb2); 192 bcopy(get_pcb_user_save_td(td1), get_pcb_user_save_pcb(pcb2), 193 cpu_max_ext_state_size); 194 195 /* Point mdproc and then copy over td1's contents */ 196 mdp2 = &p2->p_md; 197 bcopy(&p1->p_md, mdp2, sizeof(*mdp2)); 198 199 /* 200 * Create a new fresh stack for the new process. 201 * Copy the trap frame for the return to user mode as if from a 202 * syscall. This copies most of the user mode register values. 203 */ 204 td2->td_frame = (struct trapframe *)td2->td_pcb - 1; 205 bcopy(td1->td_frame, td2->td_frame, sizeof(struct trapframe)); 206 207 td2->td_frame->tf_rax = 0; /* Child returns zero */ 208 td2->td_frame->tf_rflags &= ~PSL_C; /* success */ 209 td2->td_frame->tf_rdx = 1; 210 211 /* 212 * If the parent process has the trap bit set (i.e. a debugger had 213 * single stepped the process to the system call), we need to clear 214 * the trap flag from the new frame unless the debugger had set PF_FORK 215 * on the parent. Otherwise, the child will receive a (likely 216 * unexpected) SIGTRAP when it executes the first instruction after 217 * returning to userland. 218 */ 219 if ((p1->p_pfsflags & PF_FORK) == 0) 220 td2->td_frame->tf_rflags &= ~PSL_T; 221 222 /* 223 * Set registers for trampoline to user mode. Leave space for the 224 * return address on stack. These are the kernel mode register values. 225 */ 226 pcb2->pcb_r12 = (register_t)fork_return; /* fork_trampoline argument */ 227 pcb2->pcb_rbp = 0; 228 pcb2->pcb_rsp = (register_t)td2->td_frame - sizeof(void *); 229 pcb2->pcb_rbx = (register_t)td2; /* fork_trampoline argument */ 230 pcb2->pcb_rip = (register_t)fork_trampoline; 231 /*- 232 * pcb2->pcb_dr*: cloned above. 233 * pcb2->pcb_savefpu: cloned above. 234 * pcb2->pcb_flags: cloned above. 235 * pcb2->pcb_onfault: cloned above (always NULL here?). 236 * pcb2->pcb_[fg]sbase: cloned above 237 */ 238 239 /* Setup to release spin count in fork_exit(). */ 240 td2->td_md.md_spinlock_count = 1; 241 td2->td_md.md_saved_flags = PSL_KERNEL | PSL_I; 242 td2->td_md.md_invl_gen.gen = 0; 243 244 /* As an i386, do not copy io permission bitmap. */ 245 pcb2->pcb_tssp = NULL; 246 247 /* New segment registers. */ 248 set_pcb_flags_raw(pcb2, PCB_FULL_IRET); 249 250 /* Copy the LDT, if necessary. */ 251 mdp1 = &td1->td_proc->p_md; 252 mdp2 = &p2->p_md; 253 mtx_lock(&dt_lock); 254 if (mdp1->md_ldt != NULL) { 255 if (flags & RFMEM) { 256 mdp1->md_ldt->ldt_refcnt++; 257 mdp2->md_ldt = mdp1->md_ldt; 258 bcopy(&mdp1->md_ldt_sd, &mdp2->md_ldt_sd, sizeof(struct 259 system_segment_descriptor)); 260 } else { 261 mdp2->md_ldt = NULL; 262 mdp2->md_ldt = user_ldt_alloc(p2, 0); 263 if (mdp2->md_ldt == NULL) 264 panic("could not copy LDT"); 265 amd64_set_ldt_data(td2, 0, max_ldt_segment, 266 (struct user_segment_descriptor *) 267 mdp1->md_ldt->ldt_base); 268 } 269 } else 270 mdp2->md_ldt = NULL; 271 mtx_unlock(&dt_lock); 272 273 /* 274 * Now, cpu_switch() can schedule the new process. 275 * pcb_rsp is loaded pointing to the cpu_switch() stack frame 276 * containing the return address when exiting cpu_switch. 277 * This will normally be to fork_trampoline(), which will have 278 * %ebx loaded with the new proc's pointer. fork_trampoline() 279 * will set up a stack to call fork_return(p, frame); to complete 280 * the return to user-mode. 281 */ 282} 283 284/* 285 * Intercept the return address from a freshly forked process that has NOT 286 * been scheduled yet. 287 * 288 * This is needed to make kernel threads stay in kernel mode. 289 */ 290void 291cpu_fork_kthread_handler(struct thread *td, void (*func)(void *), void *arg) 292{ 293 /* 294 * Note that the trap frame follows the args, so the function 295 * is really called like this: func(arg, frame); 296 */ 297 td->td_pcb->pcb_r12 = (long) func; /* function */ 298 td->td_pcb->pcb_rbx = (long) arg; /* first arg */ 299} 300 301void 302cpu_exit(struct thread *td) 303{ 304 305 /* 306 * If this process has a custom LDT, release it. 307 */ 308 mtx_lock(&dt_lock); 309 if (td->td_proc->p_md.md_ldt != 0) 310 user_ldt_free(td); 311 else 312 mtx_unlock(&dt_lock); 313} 314 315void 316cpu_thread_exit(struct thread *td) 317{ 318 struct pcb *pcb; 319 320 critical_enter(); 321 if (td == PCPU_GET(fpcurthread)) 322 fpudrop(); 323 critical_exit(); 324 325 pcb = td->td_pcb; 326 327 /* Disable any hardware breakpoints. */ 328 if (pcb->pcb_flags & PCB_DBREGS) { 329 reset_dbregs(); 330 clear_pcb_flags(pcb, PCB_DBREGS); 331 } 332} 333 334void 335cpu_thread_clean(struct thread *td) 336{ 337 struct pcb *pcb; 338 339 pcb = td->td_pcb; 340 341 /* 342 * Clean TSS/iomap 343 */ 344 if (pcb->pcb_tssp != NULL) { 345 pmap_pti_remove_kva((vm_offset_t)pcb->pcb_tssp, 346 (vm_offset_t)pcb->pcb_tssp + ctob(IOPAGES + 1)); 347 kmem_free(kernel_arena, (vm_offset_t)pcb->pcb_tssp, 348 ctob(IOPAGES + 1)); 349 pcb->pcb_tssp = NULL; 350 } 351} 352 353void 354cpu_thread_swapin(struct thread *td) 355{ 356} 357 358void 359cpu_thread_swapout(struct thread *td) 360{ 361} 362 363void 364cpu_thread_alloc(struct thread *td) 365{ 366 struct pcb *pcb; 367 struct xstate_hdr *xhdr; 368 369 td->td_pcb = pcb = get_pcb_td(td); 370 td->td_frame = (struct trapframe *)pcb - 1; 371 pcb->pcb_save = get_pcb_user_save_pcb(pcb); 372 if (use_xsave) { 373 xhdr = (struct xstate_hdr *)(pcb->pcb_save + 1); 374 bzero(xhdr, sizeof(*xhdr)); 375 xhdr->xstate_bv = xsave_mask; 376 } 377} 378 379void 380cpu_thread_free(struct thread *td) 381{ 382 383 cpu_thread_clean(td); 384} 385 386void 387cpu_set_syscall_retval(struct thread *td, int error) 388{ 389 390 switch (error) { 391 case 0: 392 td->td_frame->tf_rax = td->td_retval[0]; 393 td->td_frame->tf_rdx = td->td_retval[1]; 394 td->td_frame->tf_rflags &= ~PSL_C; 395 break; 396 397 case ERESTART: 398 /* 399 * Reconstruct pc, we know that 'syscall' is 2 bytes, 400 * lcall $X,y is 7 bytes, int 0x80 is 2 bytes. 401 * We saved this in tf_err. 402 * %r10 (which was holding the value of %rcx) is restored 403 * for the next iteration. 404 * %r10 restore is only required for freebsd/amd64 processes, 405 * but shall be innocent for any ia32 ABI. 406 * 407 * Require full context restore to get the arguments 408 * in the registers reloaded at return to usermode. 409 */ 410 td->td_frame->tf_rip -= td->td_frame->tf_err; 411 td->td_frame->tf_r10 = td->td_frame->tf_rcx; 412 set_pcb_flags(td->td_pcb, PCB_FULL_IRET); 413 break; 414 415 case EJUSTRETURN: 416 break; 417 418 default: 419 td->td_frame->tf_rax = SV_ABI_ERRNO(td->td_proc, error); 420 td->td_frame->tf_rflags |= PSL_C; 421 break; 422 } 423} 424 425/* 426 * Initialize machine state, mostly pcb and trap frame for a new 427 * thread, about to return to userspace. Put enough state in the new 428 * thread's PCB to get it to go back to the fork_return(), which 429 * finalizes the thread state and handles peculiarities of the first 430 * return to userspace for the new thread. 431 */ 432void 433cpu_copy_thread(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 update_pcb_bases(td0->td_pcb); 446 bcopy(td0->td_pcb, pcb2, sizeof(*pcb2)); 447 clear_pcb_flags(pcb2, PCB_FPUINITDONE | PCB_USERFPUINITDONE | 448 PCB_KERNFPU); 449 pcb2->pcb_save = get_pcb_user_save_pcb(pcb2); 450 bcopy(get_pcb_user_save_td(td0), pcb2->pcb_save, 451 cpu_max_ext_state_size); 452 set_pcb_flags_raw(pcb2, PCB_FULL_IRET); 453 454 /* 455 * Create a new fresh stack for the new thread. 456 */ 457 bcopy(td0->td_frame, td->td_frame, sizeof(struct trapframe)); 458 459 /* If the current thread has the trap bit set (i.e. a debugger had 460 * single stepped the process to the system call), we need to clear 461 * the trap flag from the new frame. Otherwise, the new thread will 462 * receive a (likely unexpected) SIGTRAP when it executes the first 463 * instruction after returning to userland. 464 */ 465 td->td_frame->tf_rflags &= ~PSL_T; 466 467 /* 468 * Set registers for trampoline to user mode. Leave space for the 469 * return address on stack. These are the kernel mode register values. 470 */ 471 pcb2->pcb_r12 = (register_t)fork_return; /* trampoline arg */ 472 pcb2->pcb_rbp = 0; 473 pcb2->pcb_rsp = (register_t)td->td_frame - sizeof(void *); /* trampoline arg */ 474 pcb2->pcb_rbx = (register_t)td; /* trampoline arg */ 475 pcb2->pcb_rip = (register_t)fork_trampoline; 476 /* 477 * If we didn't copy the pcb, we'd need to do the following registers: 478 * pcb2->pcb_dr*: cloned above. 479 * pcb2->pcb_savefpu: cloned above. 480 * pcb2->pcb_onfault: cloned above (always NULL here?). 481 * pcb2->pcb_[fg]sbase: cloned above 482 */ 483 484 /* Setup to release spin count in fork_exit(). */ 485 td->td_md.md_spinlock_count = 1; 486 td->td_md.md_saved_flags = PSL_KERNEL | PSL_I; 487} 488 489/* 490 * Set that machine state for performing an upcall that starts 491 * the entry function with the given argument. 492 */ 493void 494cpu_set_upcall(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 entry 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 /* Return address sentinel value to stop stack unwinding. */ 519 suword32((void *)td->td_frame->tf_rsp, 0); 520 521 /* Pass the argument to the entry point. */ 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 /* Return address sentinel value to stop stack unwinding. */ 545 suword((void *)td->td_frame->tf_rsp, 0); 546 547 /* Pass the argument to the entry point. */ 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