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/10.3/sys/amd64/amd64/vm_machdep.c 296945 2016-03-16 17:01:24Z 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 <x86/isa/isa.h>
84
85 static void cpu_reset_real(void);
86 #ifdef SMP
87 static void cpu_reset_proxy(void);
88 static u_int cpu_reset_proxyid;
89 static 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
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 roundup2(cpu_max_ext_state_size, XSAVE_AREA_ALIGN);
104 KASSERT((p % XSAVE_AREA_ALIGN) == 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 roundup2(cpu_max_ext_state_size, XSAVE_AREA_ALIGN) -
124 sizeof(struct pcb);
125 return ((struct pcb *)p);
126 }
127
128 void *
129 alloc_fpusave(int flags)
130 {
131 void *res;
132 struct savefpu_ymm *sf;
133
134 res = malloc(cpu_max_ext_state_size, M_DEVBUF, flags);
135 if (use_xsave) {
136 sf = (struct savefpu_ymm *)res;
137 bzero(&sf->sv_xstate.sx_hd, sizeof(sf->sv_xstate.sx_hd));
138 sf->sv_xstate.sx_hd.xstate_bv = xsave_mask;
139 }
140 return (res);
141 }
142
143 /*
144 * Finish a fork operation, with process p2 nearly set up.
145 * Copy and update the pcb, set up the stack so that the child
146 * ready to run and return to user mode.
147 */
148 void
149 cpu_fork(td1, p2, td2, flags)
150 register struct thread *td1;
151 register struct proc *p2;
152 struct thread *td2;
153 int flags;
154 {
155 register struct proc *p1;
156 struct pcb *pcb2;
157 struct mdproc *mdp1, *mdp2;
158 struct proc_ldt *pldt;
159 pmap_t pmap2;
160
161 p1 = td1->td_proc;
162 if ((flags & RFPROC) == 0) {
163 if ((flags & RFMEM) == 0) {
164 /* unshare user LDT */
165 mdp1 = &p1->p_md;
166 mtx_lock(&dt_lock);
167 if ((pldt = mdp1->md_ldt) != NULL &&
168 pldt->ldt_refcnt > 1 &&
169 user_ldt_alloc(p1, 1) == NULL)
170 panic("could not copy LDT");
171 mtx_unlock(&dt_lock);
172 }
173 return;
174 }
175
176 /* Ensure that td1's pcb is up to date. */
177 fpuexit(td1);
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 pmap2 = vmspace_pmap(p2->p_vmspace);
223 pcb2->pcb_cr3 = pmap2->pm_cr3;
224 pcb2->pcb_r12 = (register_t)fork_return; /* fork_trampoline argument */
225 pcb2->pcb_rbp = 0;
226 pcb2->pcb_rsp = (register_t)td2->td_frame - sizeof(void *);
227 pcb2->pcb_rbx = (register_t)td2; /* fork_trampoline argument */
228 pcb2->pcb_rip = (register_t)fork_trampoline;
229 /*-
230 * pcb2->pcb_dr*: cloned above.
231 * pcb2->pcb_savefpu: cloned above.
232 * pcb2->pcb_flags: cloned above.
233 * pcb2->pcb_onfault: cloned above (always NULL here?).
234 * pcb2->pcb_[fg]sbase: cloned above
235 */
236
237 /* Setup to release spin count in fork_exit(). */
238 td2->td_md.md_spinlock_count = 1;
239 td2->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
240
241 /* As an i386, do not copy io permission bitmap. */
242 pcb2->pcb_tssp = NULL;
243
244 /* New segment registers. */
245 set_pcb_flags(pcb2, PCB_FULL_IRET);
246
247 /* Copy the LDT, if necessary. */
248 mdp1 = &td1->td_proc->p_md;
249 mdp2 = &p2->p_md;
250 mtx_lock(&dt_lock);
251 if (mdp1->md_ldt != NULL) {
252 if (flags & RFMEM) {
253 mdp1->md_ldt->ldt_refcnt++;
254 mdp2->md_ldt = mdp1->md_ldt;
255 bcopy(&mdp1->md_ldt_sd, &mdp2->md_ldt_sd, sizeof(struct
256 system_segment_descriptor));
257 } else {
258 mdp2->md_ldt = NULL;
259 mdp2->md_ldt = user_ldt_alloc(p2, 0);
260 if (mdp2->md_ldt == NULL)
261 panic("could not copy LDT");
262 amd64_set_ldt_data(td2, 0, max_ldt_segment,
263 (struct user_segment_descriptor *)
264 mdp1->md_ldt->ldt_base);
265 }
266 } else
267 mdp2->md_ldt = NULL;
268 mtx_unlock(&dt_lock);
269
270 /*
271 * Now, cpu_switch() can schedule the new process.
272 * pcb_rsp is loaded pointing to the cpu_switch() stack frame
273 * containing the return address when exiting cpu_switch.
274 * This will normally be to fork_trampoline(), which will have
275 * %ebx loaded with the new proc's pointer. fork_trampoline()
276 * will set up a stack to call fork_return(p, frame); to complete
277 * the return to user-mode.
278 */
279 }
280
281 /*
282 * Intercept the return address from a freshly forked process that has NOT
283 * been scheduled yet.
284 *
285 * This is needed to make kernel threads stay in kernel mode.
286 */
287 void
288 cpu_set_fork_handler(td, func, arg)
289 struct thread *td;
290 void (*func)(void *);
291 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
301 void
302 cpu_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
315 void
316 cpu_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
334 void
335 cpu_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 kmem_free(kernel_arena, (vm_offset_t)pcb->pcb_tssp,
346 ctob(IOPAGES + 1));
347 pcb->pcb_tssp = NULL;
348 }
349 }
350
351 void
352 cpu_thread_swapin(struct thread *td)
353 {
354 }
355
356 void
357 cpu_thread_swapout(struct thread *td)
358 {
359 }
360
361 void
362 cpu_thread_alloc(struct thread *td)
363 {
364 struct pcb *pcb;
365 struct xstate_hdr *xhdr;
366
367 td->td_pcb = pcb = get_pcb_td(td);
368 td->td_frame = (struct trapframe *)pcb - 1;
369 pcb->pcb_save = get_pcb_user_save_pcb(pcb);
370 if (use_xsave) {
371 xhdr = (struct xstate_hdr *)(pcb->pcb_save + 1);
372 bzero(xhdr, sizeof(*xhdr));
373 xhdr->xstate_bv = xsave_mask;
374 }
375 }
376
377 void
378 cpu_thread_free(struct thread *td)
379 {
380
381 cpu_thread_clean(td);
382 }
383
384 void
385 cpu_set_syscall_retval(struct thread *td, int error)
386 {
387
388 switch (error) {
389 case 0:
390 td->td_frame->tf_rax = td->td_retval[0];
391 td->td_frame->tf_rdx = td->td_retval[1];
392 td->td_frame->tf_rflags &= ~PSL_C;
393 break;
394
395 case ERESTART:
396 /*
397 * Reconstruct pc, we know that 'syscall' is 2 bytes,
398 * lcall $X,y is 7 bytes, int 0x80 is 2 bytes.
399 * We saved this in tf_err.
400 * %r10 (which was holding the value of %rcx) is restored
401 * for the next iteration.
402 * %r10 restore is only required for freebsd/amd64 processes,
403 * but shall be innocent for any ia32 ABI.
404 *
405 * Require full context restore to get the arguments
406 * in the registers reloaded at return to usermode.
407 */
408 td->td_frame->tf_rip -= td->td_frame->tf_err;
409 td->td_frame->tf_r10 = td->td_frame->tf_rcx;
410 set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
411 break;
412
413 case EJUSTRETURN:
414 break;
415
416 default:
417 if (td->td_proc->p_sysent->sv_errsize) {
418 if (error >= td->td_proc->p_sysent->sv_errsize)
419 error = -1; /* XXX */
420 else
421 error = td->td_proc->p_sysent->sv_errtbl[error];
422 }
423 td->td_frame->tf_rax = error;
424 td->td_frame->tf_rflags |= PSL_C;
425 break;
426 }
427 }
428
429 /*
430 * Initialize machine state (pcb and trap frame) for a new thread about to
431 * upcall. Put enough state in the new thread's PCB to get it to go back
432 * userret(), where we can intercept it again to set the return (upcall)
433 * Address and stack, along with those from upcals that are from other sources
434 * such as those generated in thread_userret() itself.
435 */
436 void
437 cpu_set_upcall(struct thread *td, struct thread *td0)
438 {
439 struct pcb *pcb2;
440
441 /* Point the pcb to the top of the stack. */
442 pcb2 = td->td_pcb;
443
444 /*
445 * Copy the upcall pcb. This loads kernel regs.
446 * Those not loaded individually below get their default
447 * values here.
448 */
449 bcopy(td0->td_pcb, pcb2, sizeof(*pcb2));
450 clear_pcb_flags(pcb2, PCB_FPUINITDONE | PCB_USERFPUINITDONE |
451 PCB_KERNFPU);
452 pcb2->pcb_save = get_pcb_user_save_pcb(pcb2);
453 bcopy(get_pcb_user_save_td(td0), pcb2->pcb_save,
454 cpu_max_ext_state_size);
455 set_pcb_flags(pcb2, PCB_FULL_IRET);
456
457 /*
458 * Create a new fresh stack for the new thread.
459 */
460 bcopy(td0->td_frame, td->td_frame, sizeof(struct trapframe));
461
462 /* If the current thread has the trap bit set (i.e. a debugger had
463 * single stepped the process to the system call), we need to clear
464 * the trap flag from the new frame. Otherwise, the new thread will
465 * receive a (likely unexpected) SIGTRAP when it executes the first
466 * instruction after returning to userland.
467 */
468 td->td_frame->tf_rflags &= ~PSL_T;
469
470 /*
471 * Set registers for trampoline to user mode. Leave space for the
472 * return address on stack. These are the kernel mode register values.
473 */
474 pcb2->pcb_r12 = (register_t)fork_return; /* trampoline arg */
475 pcb2->pcb_rbp = 0;
476 pcb2->pcb_rsp = (register_t)td->td_frame - sizeof(void *); /* trampoline arg */
477 pcb2->pcb_rbx = (register_t)td; /* trampoline arg */
478 pcb2->pcb_rip = (register_t)fork_trampoline;
479 /*
480 * If we didn't copy the pcb, we'd need to do the following registers:
481 * pcb2->pcb_cr3: cloned above.
482 * pcb2->pcb_dr*: cloned above.
483 * pcb2->pcb_savefpu: cloned above.
484 * pcb2->pcb_onfault: cloned above (always NULL here?).
485 * pcb2->pcb_[fg]sbase: cloned above
486 */
487
488 /* Setup to release spin count in fork_exit(). */
489 td->td_md.md_spinlock_count = 1;
490 td->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
491 }
492
493 /*
494 * Set that machine state for performing an upcall that has to
495 * be done in thread_userret() so that those upcalls generated
496 * in thread_userret() itself can be done as well.
497 */
498 void
499 cpu_set_upcall_kse(struct thread *td, void (*entry)(void *), void *arg,
500 stack_t *stack)
501 {
502
503 /*
504 * Do any extra cleaning that needs to be done.
505 * The thread may have optional components
506 * that are not present in a fresh thread.
507 * This may be a recycled thread so make it look
508 * as though it's newly allocated.
509 */
510 cpu_thread_clean(td);
511
512 #ifdef COMPAT_FREEBSD32
513 if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) {
514 /*
515 * Set the trap frame to point at the beginning of the uts
516 * function.
517 */
518 td->td_frame->tf_rbp = 0;
519 td->td_frame->tf_rsp =
520 (((uintptr_t)stack->ss_sp + stack->ss_size - 4) & ~0x0f) - 4;
521 td->td_frame->tf_rip = (uintptr_t)entry;
522
523 /*
524 * Pass the address of the mailbox for this kse to the uts
525 * function as a parameter on the stack.
526 */
527 suword32((void *)(td->td_frame->tf_rsp + sizeof(int32_t)),
528 (uint32_t)(uintptr_t)arg);
529
530 return;
531 }
532 #endif
533
534 /*
535 * Set the trap frame to point at the beginning of the uts
536 * function.
537 */
538 td->td_frame->tf_rbp = 0;
539 td->td_frame->tf_rsp =
540 ((register_t)stack->ss_sp + stack->ss_size) & ~0x0f;
541 td->td_frame->tf_rsp -= 8;
542 td->td_frame->tf_rip = (register_t)entry;
543 td->td_frame->tf_ds = _udatasel;
544 td->td_frame->tf_es = _udatasel;
545 td->td_frame->tf_fs = _ufssel;
546 td->td_frame->tf_gs = _ugssel;
547 td->td_frame->tf_flags = TF_HASSEGS;
548
549 /*
550 * Pass the address of the mailbox for this kse to the uts
551 * function as a parameter on the stack.
552 */
553 td->td_frame->tf_rdi = (register_t)arg;
554 }
555
556 int
557 cpu_set_user_tls(struct thread *td, void *tls_base)
558 {
559 struct pcb *pcb;
560
561 if ((u_int64_t)tls_base >= VM_MAXUSER_ADDRESS)
562 return (EINVAL);
563
564 pcb = td->td_pcb;
565 set_pcb_flags(pcb, PCB_FULL_IRET);
566 #ifdef COMPAT_FREEBSD32
567 if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) {
568 pcb->pcb_gsbase = (register_t)tls_base;
569 return (0);
570 }
571 #endif
572 pcb->pcb_fsbase = (register_t)tls_base;
573 return (0);
574 }
575
576 #ifdef SMP
577 static void
578 cpu_reset_proxy()
579 {
580 cpuset_t tcrp;
581
582 cpu_reset_proxy_active = 1;
583 while (cpu_reset_proxy_active == 1)
584 ia32_pause(); /* Wait for other cpu to see that we've started */
585
586 CPU_SETOF(cpu_reset_proxyid, &tcrp);
587 stop_cpus(tcrp);
588 printf("cpu_reset_proxy: Stopped CPU %d\n", cpu_reset_proxyid);
589 DELAY(1000000);
590 cpu_reset_real();
591 }
592 #endif
593
594 void
595 cpu_reset()
596 {
597 #ifdef SMP
598 cpuset_t map;
599 u_int cnt;
600
601 if (smp_started) {
602 map = all_cpus;
603 CPU_CLR(PCPU_GET(cpuid), &map);
604 CPU_NAND(&map, &stopped_cpus);
605 if (!CPU_EMPTY(&map)) {
606 printf("cpu_reset: Stopping other CPUs\n");
607 stop_cpus(map);
608 }
609
610 if (PCPU_GET(cpuid) != 0) {
611 cpu_reset_proxyid = PCPU_GET(cpuid);
612 cpustop_restartfunc = cpu_reset_proxy;
613 cpu_reset_proxy_active = 0;
614 printf("cpu_reset: Restarting BSP\n");
615
616 /* Restart CPU #0. */
617 CPU_SETOF(0, &started_cpus);
618 wmb();
619
620 cnt = 0;
621 while (cpu_reset_proxy_active == 0 && cnt < 10000000) {
622 ia32_pause();
623 cnt++; /* Wait for BSP to announce restart */
624 }
625 if (cpu_reset_proxy_active == 0)
626 printf("cpu_reset: Failed to restart BSP\n");
627 enable_intr();
628 cpu_reset_proxy_active = 2;
629
630 while (1)
631 ia32_pause();
632 /* NOTREACHED */
633 }
634
635 DELAY(1000000);
636 }
637 #endif
638 cpu_reset_real();
639 /* NOTREACHED */
640 }
641
642 static void
643 cpu_reset_real()
644 {
645 struct region_descriptor null_idt;
646 int b;
647
648 disable_intr();
649
650 /*
651 * Attempt to do a CPU reset via the keyboard controller,
652 * do not turn off GateA20, as any machine that fails
653 * to do the reset here would then end up in no man's land.
654 */
655 outb(IO_KBD + 4, 0xFE);
656 DELAY(500000); /* wait 0.5 sec to see if that did it */
657
658 /*
659 * Attempt to force a reset via the Reset Control register at
660 * I/O port 0xcf9. Bit 2 forces a system reset when it
661 * transitions from 0 to 1. Bit 1 selects the type of reset
662 * to attempt: 0 selects a "soft" reset, and 1 selects a
663 * "hard" reset. We try a "hard" reset. The first write sets
664 * bit 1 to select a "hard" reset and clears bit 2. The
665 * second write forces a 0 -> 1 transition in bit 2 to trigger
666 * a reset.
667 */
668 outb(0xcf9, 0x2);
669 outb(0xcf9, 0x6);
670 DELAY(500000); /* wait 0.5 sec to see if that did it */
671
672 /*
673 * Attempt to force a reset via the Fast A20 and Init register
674 * at I/O port 0x92. Bit 1 serves as an alternate A20 gate.
675 * Bit 0 asserts INIT# when set to 1. We are careful to only
676 * preserve bit 1 while setting bit 0. We also must clear bit
677 * 0 before setting it if it isn't already clear.
678 */
679 b = inb(0x92);
680 if (b != 0xff) {
681 if ((b & 0x1) != 0)
682 outb(0x92, b & 0xfe);
683 outb(0x92, b | 0x1);
684 DELAY(500000); /* wait 0.5 sec to see if that did it */
685 }
686
687 printf("No known reset method worked, attempting CPU shutdown\n");
688 DELAY(1000000); /* wait 1 sec for printf to complete */
689
690 /* Wipe the IDT. */
691 null_idt.rd_limit = 0;
692 null_idt.rd_base = 0;
693 lidt(&null_idt);
694
695 /* "good night, sweet prince .... <THUNK!>" */
696 breakpoint();
697
698 /* NOTREACHED */
699 while(1);
700 }
701
702 /*
703 * Software interrupt handler for queued VM system processing.
704 */
705 void
706 swi_vm(void *dummy)
707 {
708 if (busdma_swi_pending != 0)
709 busdma_swi();
710 }
711
712 /*
713 * Tell whether this address is in some physical memory region.
714 * Currently used by the kernel coredump code in order to avoid
715 * dumping the ``ISA memory hole'' which could cause indefinite hangs,
716 * or other unpredictable behaviour.
717 */
718
719 int
720 is_physical_memory(vm_paddr_t addr)
721 {
722
723 #ifdef DEV_ISA
724 /* The ISA ``memory hole''. */
725 if (addr >= 0xa0000 && addr < 0x100000)
726 return 0;
727 #endif
728
729 /*
730 * stuff other tests for known memory-mapped devices (PCI?)
731 * here
732 */
733
734 return 1;
735 }
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