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/11.0/sys/amd64/amd64/vm_machdep.c 301961 2016-06-16 12:05:44Z 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 <isa/isareg.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 _Static_assert(OFFSETOF_MONITORBUF == offsetof(struct pcpu, pc_monitorbuf),
97 "OFFSETOF_MONINORBUF does not correspond with offset of pc_monitorbuf.");
98
99 struct savefpu *
100 get_pcb_user_save_td(struct thread *td)
101 {
102 vm_offset_t p;
103
104 p = td->td_kstack + td->td_kstack_pages * PAGE_SIZE -
105 roundup2(cpu_max_ext_state_size, XSAVE_AREA_ALIGN);
106 KASSERT((p % XSAVE_AREA_ALIGN) == 0, ("Unaligned pcb_user_save area"));
107 return ((struct savefpu *)p);
108 }
109
110 struct savefpu *
111 get_pcb_user_save_pcb(struct pcb *pcb)
112 {
113 vm_offset_t p;
114
115 p = (vm_offset_t)(pcb + 1);
116 return ((struct savefpu *)p);
117 }
118
119 struct pcb *
120 get_pcb_td(struct thread *td)
121 {
122 vm_offset_t p;
123
124 p = td->td_kstack + td->td_kstack_pages * PAGE_SIZE -
125 roundup2(cpu_max_ext_state_size, XSAVE_AREA_ALIGN) -
126 sizeof(struct pcb);
127 return ((struct pcb *)p);
128 }
129
130 void *
131 alloc_fpusave(int flags)
132 {
133 void *res;
134 struct savefpu_ymm *sf;
135
136 res = malloc(cpu_max_ext_state_size, M_DEVBUF, flags);
137 if (use_xsave) {
138 sf = (struct savefpu_ymm *)res;
139 bzero(&sf->sv_xstate.sx_hd, sizeof(sf->sv_xstate.sx_hd));
140 sf->sv_xstate.sx_hd.xstate_bv = xsave_mask;
141 }
142 return (res);
143 }
144
145 /*
146 * Finish a fork operation, with process p2 nearly set up.
147 * Copy and update the pcb, set up the stack so that the child
148 * ready to run and return to user mode.
149 */
150 void
151 cpu_fork(td1, p2, td2, flags)
152 register struct thread *td1;
153 register struct proc *p2;
154 struct thread *td2;
155 int flags;
156 {
157 register struct proc *p1;
158 struct pcb *pcb2;
159 struct mdproc *mdp1, *mdp2;
160 struct proc_ldt *pldt;
161
162 p1 = td1->td_proc;
163 if ((flags & RFPROC) == 0) {
164 if ((flags & RFMEM) == 0) {
165 /* unshare user LDT */
166 mdp1 = &p1->p_md;
167 mtx_lock(&dt_lock);
168 if ((pldt = mdp1->md_ldt) != NULL &&
169 pldt->ldt_refcnt > 1 &&
170 user_ldt_alloc(p1, 1) == NULL)
171 panic("could not copy LDT");
172 mtx_unlock(&dt_lock);
173 }
174 return;
175 }
176
177 /* Ensure that td1's pcb is up to date. */
178 fpuexit(td1);
179
180 /* Point the pcb to the top of the stack */
181 pcb2 = get_pcb_td(td2);
182 td2->td_pcb = pcb2;
183
184 /* Copy td1's pcb */
185 bcopy(td1->td_pcb, pcb2, sizeof(*pcb2));
186
187 /* Properly initialize pcb_save */
188 pcb2->pcb_save = get_pcb_user_save_pcb(pcb2);
189 bcopy(get_pcb_user_save_td(td1), get_pcb_user_save_pcb(pcb2),
190 cpu_max_ext_state_size);
191
192 /* Point mdproc and then copy over td1's contents */
193 mdp2 = &p2->p_md;
194 bcopy(&p1->p_md, mdp2, sizeof(*mdp2));
195
196 /*
197 * Create a new fresh stack for the new process.
198 * Copy the trap frame for the return to user mode as if from a
199 * syscall. This copies most of the user mode register values.
200 */
201 td2->td_frame = (struct trapframe *)td2->td_pcb - 1;
202 bcopy(td1->td_frame, td2->td_frame, sizeof(struct trapframe));
203
204 td2->td_frame->tf_rax = 0; /* Child returns zero */
205 td2->td_frame->tf_rflags &= ~PSL_C; /* success */
206 td2->td_frame->tf_rdx = 1;
207
208 /*
209 * If the parent process has the trap bit set (i.e. a debugger had
210 * single stepped the process to the system call), we need to clear
211 * the trap flag from the new frame unless the debugger had set PF_FORK
212 * on the parent. Otherwise, the child will receive a (likely
213 * unexpected) SIGTRAP when it executes the first instruction after
214 * returning to userland.
215 */
216 if ((p1->p_pfsflags & PF_FORK) == 0)
217 td2->td_frame->tf_rflags &= ~PSL_T;
218
219 /*
220 * Set registers for trampoline to user mode. Leave space for the
221 * return address on stack. These are the kernel mode register values.
222 */
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 td2->td_md.md_invl_gen.gen = 0;
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_fork_kthread_handler(struct thread *td, void (*func)(void *), void *arg)
289 {
290 /*
291 * Note that the trap frame follows the args, so the function
292 * is really called like this: func(arg, frame);
293 */
294 td->td_pcb->pcb_r12 = (long) func; /* function */
295 td->td_pcb->pcb_rbx = (long) arg; /* first arg */
296 }
297
298 void
299 cpu_exit(struct thread *td)
300 {
301
302 /*
303 * If this process has a custom LDT, release it.
304 */
305 mtx_lock(&dt_lock);
306 if (td->td_proc->p_md.md_ldt != 0)
307 user_ldt_free(td);
308 else
309 mtx_unlock(&dt_lock);
310 }
311
312 void
313 cpu_thread_exit(struct thread *td)
314 {
315 struct pcb *pcb;
316
317 critical_enter();
318 if (td == PCPU_GET(fpcurthread))
319 fpudrop();
320 critical_exit();
321
322 pcb = td->td_pcb;
323
324 /* Disable any hardware breakpoints. */
325 if (pcb->pcb_flags & PCB_DBREGS) {
326 reset_dbregs();
327 clear_pcb_flags(pcb, PCB_DBREGS);
328 }
329 }
330
331 void
332 cpu_thread_clean(struct thread *td)
333 {
334 struct pcb *pcb;
335
336 pcb = td->td_pcb;
337
338 /*
339 * Clean TSS/iomap
340 */
341 if (pcb->pcb_tssp != NULL) {
342 kmem_free(kernel_arena, (vm_offset_t)pcb->pcb_tssp,
343 ctob(IOPAGES + 1));
344 pcb->pcb_tssp = NULL;
345 }
346 }
347
348 void
349 cpu_thread_swapin(struct thread *td)
350 {
351 }
352
353 void
354 cpu_thread_swapout(struct thread *td)
355 {
356 }
357
358 void
359 cpu_thread_alloc(struct thread *td)
360 {
361 struct pcb *pcb;
362 struct xstate_hdr *xhdr;
363
364 td->td_pcb = pcb = get_pcb_td(td);
365 td->td_frame = (struct trapframe *)pcb - 1;
366 pcb->pcb_save = get_pcb_user_save_pcb(pcb);
367 if (use_xsave) {
368 xhdr = (struct xstate_hdr *)(pcb->pcb_save + 1);
369 bzero(xhdr, sizeof(*xhdr));
370 xhdr->xstate_bv = xsave_mask;
371 }
372 }
373
374 void
375 cpu_thread_free(struct thread *td)
376 {
377
378 cpu_thread_clean(td);
379 }
380
381 void
382 cpu_set_syscall_retval(struct thread *td, int error)
383 {
384
385 switch (error) {
386 case 0:
387 td->td_frame->tf_rax = td->td_retval[0];
388 td->td_frame->tf_rdx = td->td_retval[1];
389 td->td_frame->tf_rflags &= ~PSL_C;
390 break;
391
392 case ERESTART:
393 /*
394 * Reconstruct pc, we know that 'syscall' is 2 bytes,
395 * lcall $X,y is 7 bytes, int 0x80 is 2 bytes.
396 * We saved this in tf_err.
397 * %r10 (which was holding the value of %rcx) is restored
398 * for the next iteration.
399 * %r10 restore is only required for freebsd/amd64 processes,
400 * but shall be innocent for any ia32 ABI.
401 *
402 * Require full context restore to get the arguments
403 * in the registers reloaded at return to usermode.
404 */
405 td->td_frame->tf_rip -= td->td_frame->tf_err;
406 td->td_frame->tf_r10 = td->td_frame->tf_rcx;
407 set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
408 break;
409
410 case EJUSTRETURN:
411 break;
412
413 default:
414 td->td_frame->tf_rax = SV_ABI_ERRNO(td->td_proc, error);
415 td->td_frame->tf_rflags |= PSL_C;
416 break;
417 }
418 }
419
420 /*
421 * Initialize machine state, mostly pcb and trap frame for a new
422 * thread, about to return to userspace. Put enough state in the new
423 * thread's PCB to get it to go back to the fork_return(), which
424 * finalizes the thread state and handles peculiarities of the first
425 * return to userspace for the new thread.
426 */
427 void
428 cpu_copy_thread(struct thread *td, struct thread *td0)
429 {
430 struct pcb *pcb2;
431
432 /* Point the pcb to the top of the stack. */
433 pcb2 = td->td_pcb;
434
435 /*
436 * Copy the upcall pcb. This loads kernel regs.
437 * Those not loaded individually below get their default
438 * values here.
439 */
440 bcopy(td0->td_pcb, pcb2, sizeof(*pcb2));
441 clear_pcb_flags(pcb2, PCB_FPUINITDONE | PCB_USERFPUINITDONE |
442 PCB_KERNFPU);
443 pcb2->pcb_save = get_pcb_user_save_pcb(pcb2);
444 bcopy(get_pcb_user_save_td(td0), pcb2->pcb_save,
445 cpu_max_ext_state_size);
446 set_pcb_flags(pcb2, PCB_FULL_IRET);
447
448 /*
449 * Create a new fresh stack for the new thread.
450 */
451 bcopy(td0->td_frame, td->td_frame, sizeof(struct trapframe));
452
453 /* If the current thread has the trap bit set (i.e. a debugger had
454 * single stepped the process to the system call), we need to clear
455 * the trap flag from the new frame. Otherwise, the new thread will
456 * receive a (likely unexpected) SIGTRAP when it executes the first
457 * instruction after returning to userland.
458 */
459 td->td_frame->tf_rflags &= ~PSL_T;
460
461 /*
462 * Set registers for trampoline to user mode. Leave space for the
463 * return address on stack. These are the kernel mode register values.
464 */
465 pcb2->pcb_r12 = (register_t)fork_return; /* trampoline arg */
466 pcb2->pcb_rbp = 0;
467 pcb2->pcb_rsp = (register_t)td->td_frame - sizeof(void *); /* trampoline arg */
468 pcb2->pcb_rbx = (register_t)td; /* trampoline arg */
469 pcb2->pcb_rip = (register_t)fork_trampoline;
470 /*
471 * If we didn't copy the pcb, we'd need to do the following registers:
472 * pcb2->pcb_dr*: cloned above.
473 * pcb2->pcb_savefpu: cloned above.
474 * pcb2->pcb_onfault: cloned above (always NULL here?).
475 * pcb2->pcb_[fg]sbase: cloned above
476 */
477
478 /* Setup to release spin count in fork_exit(). */
479 td->td_md.md_spinlock_count = 1;
480 td->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
481 }
482
483 /*
484 * Set that machine state for performing an upcall that starts
485 * the entry function with the given argument.
486 */
487 void
488 cpu_set_upcall(struct thread *td, void (*entry)(void *), void *arg,
489 stack_t *stack)
490 {
491
492 /*
493 * Do any extra cleaning that needs to be done.
494 * The thread may have optional components
495 * that are not present in a fresh thread.
496 * This may be a recycled thread so make it look
497 * as though it's newly allocated.
498 */
499 cpu_thread_clean(td);
500
501 #ifdef COMPAT_FREEBSD32
502 if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) {
503 /*
504 * Set the trap frame to point at the beginning of the entry
505 * function.
506 */
507 td->td_frame->tf_rbp = 0;
508 td->td_frame->tf_rsp =
509 (((uintptr_t)stack->ss_sp + stack->ss_size - 4) & ~0x0f) - 4;
510 td->td_frame->tf_rip = (uintptr_t)entry;
511
512 /* Pass the argument to the entry point. */
513 suword32((void *)(td->td_frame->tf_rsp + sizeof(int32_t)),
514 (uint32_t)(uintptr_t)arg);
515
516 return;
517 }
518 #endif
519
520 /*
521 * Set the trap frame to point at the beginning of the uts
522 * function.
523 */
524 td->td_frame->tf_rbp = 0;
525 td->td_frame->tf_rsp =
526 ((register_t)stack->ss_sp + stack->ss_size) & ~0x0f;
527 td->td_frame->tf_rsp -= 8;
528 td->td_frame->tf_rip = (register_t)entry;
529 td->td_frame->tf_ds = _udatasel;
530 td->td_frame->tf_es = _udatasel;
531 td->td_frame->tf_fs = _ufssel;
532 td->td_frame->tf_gs = _ugssel;
533 td->td_frame->tf_flags = TF_HASSEGS;
534
535 /* Pass the argument to the entry point. */
536 td->td_frame->tf_rdi = (register_t)arg;
537 }
538
539 int
540 cpu_set_user_tls(struct thread *td, void *tls_base)
541 {
542 struct pcb *pcb;
543
544 if ((u_int64_t)tls_base >= VM_MAXUSER_ADDRESS)
545 return (EINVAL);
546
547 pcb = td->td_pcb;
548 set_pcb_flags(pcb, PCB_FULL_IRET);
549 #ifdef COMPAT_FREEBSD32
550 if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) {
551 pcb->pcb_gsbase = (register_t)tls_base;
552 return (0);
553 }
554 #endif
555 pcb->pcb_fsbase = (register_t)tls_base;
556 return (0);
557 }
558
559 #ifdef SMP
560 static void
561 cpu_reset_proxy()
562 {
563 cpuset_t tcrp;
564
565 cpu_reset_proxy_active = 1;
566 while (cpu_reset_proxy_active == 1)
567 ia32_pause(); /* Wait for other cpu to see that we've started */
568
569 CPU_SETOF(cpu_reset_proxyid, &tcrp);
570 stop_cpus(tcrp);
571 printf("cpu_reset_proxy: Stopped CPU %d\n", cpu_reset_proxyid);
572 DELAY(1000000);
573 cpu_reset_real();
574 }
575 #endif
576
577 void
578 cpu_reset()
579 {
580 #ifdef SMP
581 cpuset_t map;
582 u_int cnt;
583
584 if (smp_started) {
585 map = all_cpus;
586 CPU_CLR(PCPU_GET(cpuid), &map);
587 CPU_NAND(&map, &stopped_cpus);
588 if (!CPU_EMPTY(&map)) {
589 printf("cpu_reset: Stopping other CPUs\n");
590 stop_cpus(map);
591 }
592
593 if (PCPU_GET(cpuid) != 0) {
594 cpu_reset_proxyid = PCPU_GET(cpuid);
595 cpustop_restartfunc = cpu_reset_proxy;
596 cpu_reset_proxy_active = 0;
597 printf("cpu_reset: Restarting BSP\n");
598
599 /* Restart CPU #0. */
600 CPU_SETOF(0, &started_cpus);
601 wmb();
602
603 cnt = 0;
604 while (cpu_reset_proxy_active == 0 && cnt < 10000000) {
605 ia32_pause();
606 cnt++; /* Wait for BSP to announce restart */
607 }
608 if (cpu_reset_proxy_active == 0)
609 printf("cpu_reset: Failed to restart BSP\n");
610 enable_intr();
611 cpu_reset_proxy_active = 2;
612
613 while (1)
614 ia32_pause();
615 /* NOTREACHED */
616 }
617
618 DELAY(1000000);
619 }
620 #endif
621 cpu_reset_real();
622 /* NOTREACHED */
623 }
624
625 static void
626 cpu_reset_real()
627 {
628 struct region_descriptor null_idt;
629 int b;
630
631 disable_intr();
632
633 /*
634 * Attempt to do a CPU reset via the keyboard controller,
635 * do not turn off GateA20, as any machine that fails
636 * to do the reset here would then end up in no man's land.
637 */
638 outb(IO_KBD + 4, 0xFE);
639 DELAY(500000); /* wait 0.5 sec to see if that did it */
640
641 /*
642 * Attempt to force a reset via the Reset Control register at
643 * I/O port 0xcf9. Bit 2 forces a system reset when it
644 * transitions from 0 to 1. Bit 1 selects the type of reset
645 * to attempt: 0 selects a "soft" reset, and 1 selects a
646 * "hard" reset. We try a "hard" reset. The first write sets
647 * bit 1 to select a "hard" reset and clears bit 2. The
648 * second write forces a 0 -> 1 transition in bit 2 to trigger
649 * a reset.
650 */
651 outb(0xcf9, 0x2);
652 outb(0xcf9, 0x6);
653 DELAY(500000); /* wait 0.5 sec to see if that did it */
654
655 /*
656 * Attempt to force a reset via the Fast A20 and Init register
657 * at I/O port 0x92. Bit 1 serves as an alternate A20 gate.
658 * Bit 0 asserts INIT# when set to 1. We are careful to only
659 * preserve bit 1 while setting bit 0. We also must clear bit
660 * 0 before setting it if it isn't already clear.
661 */
662 b = inb(0x92);
663 if (b != 0xff) {
664 if ((b & 0x1) != 0)
665 outb(0x92, b & 0xfe);
666 outb(0x92, b | 0x1);
667 DELAY(500000); /* wait 0.5 sec to see if that did it */
668 }
669
670 printf("No known reset method worked, attempting CPU shutdown\n");
671 DELAY(1000000); /* wait 1 sec for printf to complete */
672
673 /* Wipe the IDT. */
674 null_idt.rd_limit = 0;
675 null_idt.rd_base = 0;
676 lidt(&null_idt);
677
678 /* "good night, sweet prince .... <THUNK!>" */
679 breakpoint();
680
681 /* NOTREACHED */
682 while(1);
683 }
684
685 /*
686 * Software interrupt handler for queued VM system processing.
687 */
688 void
689 swi_vm(void *dummy)
690 {
691 if (busdma_swi_pending != 0)
692 busdma_swi();
693 }
694
695 /*
696 * Tell whether this address is in some physical memory region.
697 * Currently used by the kernel coredump code in order to avoid
698 * dumping the ``ISA memory hole'' which could cause indefinite hangs,
699 * or other unpredictable behaviour.
700 */
701
702 int
703 is_physical_memory(vm_paddr_t addr)
704 {
705
706 #ifdef DEV_ISA
707 /* The ISA ``memory hole''. */
708 if (addr >= 0xa0000 && addr < 0x100000)
709 return 0;
710 #endif
711
712 /*
713 * stuff other tests for known memory-mapped devices (PCI?)
714 * here
715 */
716
717 return 1;
718 }
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