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: releng/9.2/sys/amd64/amd64/vm_machdep.c 239945 2012-08-31 11:48:04Z 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/sf_buf.h>
63 #include <sys/smp.h>
64 #include <sys/sysctl.h>
65 #include <sys/sysent.h>
66 #include <sys/unistd.h>
67 #include <sys/vnode.h>
68 #include <sys/vmmeter.h>
69
70 #include <machine/cpu.h>
71 #include <machine/md_var.h>
72 #include <machine/pcb.h>
73 #include <machine/smp.h>
74 #include <machine/specialreg.h>
75 #include <machine/tss.h>
76
77 #include <vm/vm.h>
78 #include <vm/vm_extern.h>
79 #include <vm/vm_kern.h>
80 #include <vm/vm_page.h>
81 #include <vm/vm_map.h>
82 #include <vm/vm_param.h>
83
84 #include <x86/isa/isa.h>
85
86 static void cpu_reset_real(void);
87 #ifdef SMP
88 static void cpu_reset_proxy(void);
89 static u_int cpu_reset_proxyid;
90 static volatile u_int cpu_reset_proxy_active;
91 #endif
92
93 CTASSERT((struct thread **)OFFSETOF_CURTHREAD ==
94 &((struct pcpu *)NULL)->pc_curthread);
95 CTASSERT((struct pcb **)OFFSETOF_CURPCB == &((struct pcpu *)NULL)->pc_curpcb);
96
97 struct savefpu *
98 get_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
108 struct savefpu *
109 get_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
117 struct pcb *
118 get_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
127 void *
128 alloc_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 */
147 void
148 cpu_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 = DMAP_TO_PHYS((vm_offset_t)pmap2->pm_pml4);
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 */
286 void
287 cpu_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
300 void
301 cpu_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
314 void
315 cpu_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
333 void
334 cpu_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 kmem_free(kernel_map, (vm_offset_t)pcb->pcb_tssp,
345 ctob(IOPAGES + 1));
346 pcb->pcb_tssp = NULL;
347 }
348 }
349
350 void
351 cpu_thread_swapin(struct thread *td)
352 {
353 }
354
355 void
356 cpu_thread_swapout(struct thread *td)
357 {
358 }
359
360 void
361 cpu_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
376 void
377 cpu_thread_free(struct thread *td)
378 {
379
380 cpu_thread_clean(td);
381 }
382
383 void
384 cpu_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 */
431 void
432 cpu_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 */
492 void
493 cpu_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
550 int
551 cpu_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
571 static void
572 cpu_reset_proxy()
573 {
574 cpuset_t tcrp;
575
576 cpu_reset_proxy_active = 1;
577 while (cpu_reset_proxy_active == 1)
578 ; /* Wait for other cpu to see that we've started */
579 CPU_SETOF(cpu_reset_proxyid, &tcrp);
580 stop_cpus(tcrp);
581 printf("cpu_reset_proxy: Stopped CPU %d\n", cpu_reset_proxyid);
582 DELAY(1000000);
583 cpu_reset_real();
584 }
585 #endif
586
587 void
588 cpu_reset()
589 {
590 #ifdef SMP
591 cpuset_t map;
592 u_int cnt;
593
594 if (smp_active) {
595 map = all_cpus;
596 CPU_CLR(PCPU_GET(cpuid), &map);
597 CPU_NAND(&map, &stopped_cpus);
598 if (!CPU_EMPTY(&map)) {
599 printf("cpu_reset: Stopping other CPUs\n");
600 stop_cpus(map);
601 }
602
603 if (PCPU_GET(cpuid) != 0) {
604 cpu_reset_proxyid = PCPU_GET(cpuid);
605 cpustop_restartfunc = cpu_reset_proxy;
606 cpu_reset_proxy_active = 0;
607 printf("cpu_reset: Restarting BSP\n");
608
609 /* Restart CPU #0. */
610 CPU_SETOF(0, &started_cpus);
611 wmb();
612
613 cnt = 0;
614 while (cpu_reset_proxy_active == 0 && cnt < 10000000)
615 cnt++; /* Wait for BSP to announce restart */
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 /* NOTREACHED */
623 }
624
625 DELAY(1000000);
626 }
627 #endif
628 cpu_reset_real();
629 /* NOTREACHED */
630 }
631
632 static void
633 cpu_reset_real()
634 {
635 struct region_descriptor null_idt;
636 int b;
637
638 disable_intr();
639
640 /*
641 * Attempt to do a CPU reset via the keyboard controller,
642 * do not turn off GateA20, as any machine that fails
643 * to do the reset here would then end up in no man's land.
644 */
645 outb(IO_KBD + 4, 0xFE);
646 DELAY(500000); /* wait 0.5 sec to see if that did it */
647
648 /*
649 * Attempt to force a reset via the Reset Control register at
650 * I/O port 0xcf9. Bit 2 forces a system reset when it
651 * transitions from 0 to 1. Bit 1 selects the type of reset
652 * to attempt: 0 selects a "soft" reset, and 1 selects a
653 * "hard" reset. We try a "hard" reset. The first write sets
654 * bit 1 to select a "hard" reset and clears bit 2. The
655 * second write forces a 0 -> 1 transition in bit 2 to trigger
656 * a reset.
657 */
658 outb(0xcf9, 0x2);
659 outb(0xcf9, 0x6);
660 DELAY(500000); /* wait 0.5 sec to see if that did it */
661
662 /*
663 * Attempt to force a reset via the Fast A20 and Init register
664 * at I/O port 0x92. Bit 1 serves as an alternate A20 gate.
665 * Bit 0 asserts INIT# when set to 1. We are careful to only
666 * preserve bit 1 while setting bit 0. We also must clear bit
667 * 0 before setting it if it isn't already clear.
668 */
669 b = inb(0x92);
670 if (b != 0xff) {
671 if ((b & 0x1) != 0)
672 outb(0x92, b & 0xfe);
673 outb(0x92, b | 0x1);
674 DELAY(500000); /* wait 0.5 sec to see if that did it */
675 }
676
677 printf("No known reset method worked, attempting CPU shutdown\n");
678 DELAY(1000000); /* wait 1 sec for printf to complete */
679
680 /* Wipe the IDT. */
681 null_idt.rd_limit = 0;
682 null_idt.rd_base = 0;
683 lidt(&null_idt);
684
685 /* "good night, sweet prince .... <THUNK!>" */
686 breakpoint();
687
688 /* NOTREACHED */
689 while(1);
690 }
691
692 /*
693 * Allocate an sf_buf for the given vm_page. On this machine, however, there
694 * is no sf_buf object. Instead, an opaque pointer to the given vm_page is
695 * returned.
696 */
697 struct sf_buf *
698 sf_buf_alloc(struct vm_page *m, int pri)
699 {
700
701 return ((struct sf_buf *)m);
702 }
703
704 /*
705 * Free the sf_buf. In fact, do nothing because there are no resources
706 * associated with the sf_buf.
707 */
708 void
709 sf_buf_free(struct sf_buf *sf)
710 {
711 }
712
713 /*
714 * Software interrupt handler for queued VM system processing.
715 */
716 void
717 swi_vm(void *dummy)
718 {
719 if (busdma_swi_pending != 0)
720 busdma_swi();
721 }
722
723 /*
724 * Tell whether this address is in some physical memory region.
725 * Currently used by the kernel coredump code in order to avoid
726 * dumping the ``ISA memory hole'' which could cause indefinite hangs,
727 * or other unpredictable behaviour.
728 */
729
730 int
731 is_physical_memory(vm_paddr_t addr)
732 {
733
734 #ifdef DEV_ISA
735 /* The ISA ``memory hole''. */
736 if (addr >= 0xa0000 && addr < 0x100000)
737 return 0;
738 #endif
739
740 /*
741 * stuff other tests for known memory-mapped devices (PCI?)
742 * here
743 */
744
745 return 1;
746 }
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