xref: /freebsd/sys/i386/i386/vm_machdep.c (revision a521f2116473fbd8c09db395518f060a27d02334)
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("$FreeBSD$");
47 
48 #include "opt_isa.h"
49 #include "opt_npx.h"
50 #include "opt_reset.h"
51 #include "opt_cpu.h"
52 
53 #include <sys/param.h>
54 #include <sys/systm.h>
55 #include <sys/bio.h>
56 #include <sys/buf.h>
57 #include <sys/kernel.h>
58 #include <sys/ktr.h>
59 #include <sys/lock.h>
60 #include <sys/malloc.h>
61 #include <sys/mbuf.h>
62 #include <sys/mutex.h>
63 #include <sys/proc.h>
64 #include <sys/sysent.h>
65 #include <sys/sf_buf.h>
66 #include <sys/smp.h>
67 #include <sys/sched.h>
68 #include <sys/sysctl.h>
69 #include <sys/unistd.h>
70 #include <sys/vnode.h>
71 #include <sys/vmmeter.h>
72 
73 #include <machine/cpu.h>
74 #include <machine/cputypes.h>
75 #include <machine/md_var.h>
76 #include <machine/pcb.h>
77 #include <machine/pcb_ext.h>
78 #include <machine/smp.h>
79 #include <machine/vm86.h>
80 
81 #include <vm/vm.h>
82 #include <vm/vm_extern.h>
83 #include <vm/vm_kern.h>
84 #include <vm/vm_page.h>
85 #include <vm/vm_map.h>
86 #include <vm/vm_param.h>
87 
88 _Static_assert(__OFFSETOF_MONITORBUF == offsetof(struct pcpu, pc_monitorbuf),
89     "__OFFSETOF_MONITORBUF does not correspond with offset of pc_monitorbuf.");
90 
91 union savefpu *
92 get_pcb_user_save_td(struct thread *td)
93 {
94 	vm_offset_t p;
95 
96 	p = td->td_kstack + td->td_kstack_pages * PAGE_SIZE -
97 	    roundup2(cpu_max_ext_state_size, XSAVE_AREA_ALIGN);
98 	KASSERT((p % XSAVE_AREA_ALIGN) == 0, ("Unaligned pcb_user_save area"));
99 	return ((union savefpu *)p);
100 }
101 
102 union savefpu *
103 get_pcb_user_save_pcb(struct pcb *pcb)
104 {
105 	vm_offset_t p;
106 
107 	p = (vm_offset_t)(pcb + 1);
108 	return ((union savefpu *)p);
109 }
110 
111 struct pcb *
112 get_pcb_td(struct thread *td)
113 {
114 	vm_offset_t p;
115 
116 	p = td->td_kstack + td->td_kstack_pages * PAGE_SIZE -
117 	    roundup2(cpu_max_ext_state_size, XSAVE_AREA_ALIGN) -
118 	    sizeof(struct pcb);
119 	return ((struct pcb *)p);
120 }
121 
122 void *
123 alloc_fpusave(int flags)
124 {
125 	void *res;
126 	struct savefpu_ymm *sf;
127 
128 	res = malloc(cpu_max_ext_state_size, M_DEVBUF, flags);
129 	if (use_xsave) {
130 		sf = (struct savefpu_ymm *)res;
131 		bzero(&sf->sv_xstate.sx_hd, sizeof(sf->sv_xstate.sx_hd));
132 		sf->sv_xstate.sx_hd.xstate_bv = xsave_mask;
133 	}
134 	return (res);
135 }
136 /*
137  * Finish a fork operation, with process p2 nearly set up.
138  * Copy and update the pcb, set up the stack so that the child
139  * ready to run and return to user mode.
140  */
141 void
142 cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
143 {
144 	struct proc *p1;
145 	struct pcb *pcb2;
146 	struct mdproc *mdp2;
147 
148 	p1 = td1->td_proc;
149 	if ((flags & RFPROC) == 0) {
150 		if ((flags & RFMEM) == 0) {
151 			/* unshare user LDT */
152 			struct mdproc *mdp1 = &p1->p_md;
153 			struct proc_ldt *pldt, *pldt1;
154 
155 			mtx_lock_spin(&dt_lock);
156 			if ((pldt1 = mdp1->md_ldt) != NULL &&
157 			    pldt1->ldt_refcnt > 1) {
158 				pldt = user_ldt_alloc(mdp1, pldt1->ldt_len);
159 				if (pldt == NULL)
160 					panic("could not copy LDT");
161 				mdp1->md_ldt = pldt;
162 				set_user_ldt(mdp1);
163 				user_ldt_deref(pldt1);
164 			} else
165 				mtx_unlock_spin(&dt_lock);
166 		}
167 		return;
168 	}
169 
170 	/* Ensure that td1's pcb is up to date. */
171 	if (td1 == curthread)
172 		td1->td_pcb->pcb_gs = rgs();
173 	critical_enter();
174 	if (PCPU_GET(fpcurthread) == td1)
175 		npxsave(td1->td_pcb->pcb_save);
176 	critical_exit();
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 	 * The -VM86_STACK_SPACE (-16) is so we can expand the trapframe
199 	 * if we go to vm86.
200 	 */
201 	td2->td_frame = (struct trapframe *)((caddr_t)td2->td_pcb -
202 	    VM86_STACK_SPACE) - 1;
203 	bcopy(td1->td_frame, td2->td_frame, sizeof(struct trapframe));
204 
205 	td2->td_frame->tf_eax = 0;		/* Child returns zero */
206 	td2->td_frame->tf_eflags &= ~PSL_C;	/* success */
207 	td2->td_frame->tf_edx = 1;
208 
209 	/*
210 	 * If the parent process has the trap bit set (i.e. a debugger
211 	 * had single stepped the process to the system call), we need
212 	 * to clear the trap flag from the new frame.
213 	 */
214 	td2->td_frame->tf_eflags &= ~PSL_T;
215 
216 	/*
217 	 * Set registers for trampoline to user mode.  Leave space for the
218 	 * return address on stack.  These are the kernel mode register values.
219 	 */
220 	pcb2->pcb_cr3 = pmap_get_cr3(vmspace_pmap(p2->p_vmspace));
221 	pcb2->pcb_edi = 0;
222 	pcb2->pcb_esi = (int)fork_return;	/* fork_trampoline argument */
223 	pcb2->pcb_ebp = 0;
224 	pcb2->pcb_esp = (int)td2->td_frame - sizeof(void *);
225 	pcb2->pcb_ebx = (int)td2;		/* fork_trampoline argument */
226 	pcb2->pcb_eip = (int)fork_trampoline + setidt_disp;
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_gs:	cloned above.
233 	 * pcb2->pcb_ext:	cleared below.
234 	 */
235 
236 	/*
237 	 * XXX don't copy the i/o pages.  this should probably be fixed.
238 	 */
239 	pcb2->pcb_ext = 0;
240 
241 	/* Copy the LDT, if necessary. */
242 	mtx_lock_spin(&dt_lock);
243 	if (mdp2->md_ldt != NULL) {
244 		if (flags & RFMEM) {
245 			mdp2->md_ldt->ldt_refcnt++;
246 		} else {
247 			mdp2->md_ldt = user_ldt_alloc(mdp2,
248 			    mdp2->md_ldt->ldt_len);
249 			if (mdp2->md_ldt == NULL)
250 				panic("could not copy LDT");
251 		}
252 	}
253 	mtx_unlock_spin(&dt_lock);
254 
255 	/* Setup to release spin count in fork_exit(). */
256 	td2->td_md.md_spinlock_count = 1;
257 	td2->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
258 
259 	/*
260 	 * Now, cpu_switch() can schedule the new process.
261 	 * pcb_esp is loaded pointing to the cpu_switch() stack frame
262 	 * containing the return address when exiting cpu_switch.
263 	 * This will normally be to fork_trampoline(), which will have
264 	 * %ebx loaded with the new proc's pointer.  fork_trampoline()
265 	 * will set up a stack to call fork_return(p, frame); to complete
266 	 * the return to user-mode.
267 	 */
268 }
269 
270 /*
271  * Intercept the return address from a freshly forked process that has NOT
272  * been scheduled yet.
273  *
274  * This is needed to make kernel threads stay in kernel mode.
275  */
276 void
277 cpu_fork_kthread_handler(struct thread *td, void (*func)(void *), void *arg)
278 {
279 	/*
280 	 * Note that the trap frame follows the args, so the function
281 	 * is really called like this:  func(arg, frame);
282 	 */
283 	td->td_pcb->pcb_esi = (int) func;	/* function */
284 	td->td_pcb->pcb_ebx = (int) arg;	/* first arg */
285 }
286 
287 void
288 cpu_exit(struct thread *td)
289 {
290 
291 	/*
292 	 * If this process has a custom LDT, release it.  Reset pc->pcb_gs
293 	 * and %gs before we free it in case they refer to an LDT entry.
294 	 */
295 	mtx_lock_spin(&dt_lock);
296 	if (td->td_proc->p_md.md_ldt) {
297 		td->td_pcb->pcb_gs = _udatasel;
298 		load_gs(_udatasel);
299 		user_ldt_free(td);
300 	} else
301 		mtx_unlock_spin(&dt_lock);
302 }
303 
304 void
305 cpu_thread_exit(struct thread *td)
306 {
307 
308 	critical_enter();
309 	if (td == PCPU_GET(fpcurthread))
310 		npxdrop();
311 	critical_exit();
312 
313 	/* Disable any hardware breakpoints. */
314 	if (td->td_pcb->pcb_flags & PCB_DBREGS) {
315 		reset_dbregs();
316 		td->td_pcb->pcb_flags &= ~PCB_DBREGS;
317 	}
318 }
319 
320 void
321 cpu_thread_clean(struct thread *td)
322 {
323 	struct pcb *pcb;
324 
325 	pcb = td->td_pcb;
326 	if (pcb->pcb_ext != NULL) {
327 		/* if (pcb->pcb_ext->ext_refcount-- == 1) ?? */
328 		/*
329 		 * XXX do we need to move the TSS off the allocated pages
330 		 * before freeing them?  (not done here)
331 		 */
332 		pmap_trm_free(pcb->pcb_ext, ctob(IOPAGES + 1));
333 		pcb->pcb_ext = NULL;
334 	}
335 }
336 
337 void
338 cpu_thread_swapin(struct thread *td)
339 {
340 }
341 
342 void
343 cpu_thread_swapout(struct thread *td)
344 {
345 }
346 
347 void
348 cpu_thread_alloc(struct thread *td)
349 {
350 	struct pcb *pcb;
351 	struct xstate_hdr *xhdr;
352 
353 	td->td_pcb = pcb = get_pcb_td(td);
354 	td->td_frame = (struct trapframe *)((caddr_t)pcb -
355 	    VM86_STACK_SPACE) - 1;
356 	pcb->pcb_ext = NULL;
357 	pcb->pcb_save = get_pcb_user_save_pcb(pcb);
358 	if (use_xsave) {
359 		xhdr = (struct xstate_hdr *)(pcb->pcb_save + 1);
360 		bzero(xhdr, sizeof(*xhdr));
361 		xhdr->xstate_bv = xsave_mask;
362 	}
363 }
364 
365 void
366 cpu_thread_free(struct thread *td)
367 {
368 
369 	cpu_thread_clean(td);
370 }
371 
372 bool
373 cpu_exec_vmspace_reuse(struct proc *p __unused, vm_map_t map __unused)
374 {
375 
376 	return (true);
377 }
378 
379 int
380 cpu_procctl(struct thread *td __unused, int idtype __unused, id_t id __unused,
381     int com __unused, void *data __unused)
382 {
383 
384 	return (EINVAL);
385 }
386 
387 void
388 cpu_set_syscall_retval(struct thread *td, int error)
389 {
390 
391 	switch (error) {
392 	case 0:
393 		td->td_frame->tf_eax = td->td_retval[0];
394 		td->td_frame->tf_edx = td->td_retval[1];
395 		td->td_frame->tf_eflags &= ~PSL_C;
396 		break;
397 
398 	case ERESTART:
399 		/*
400 		 * Reconstruct pc, assuming lcall $X,y is 7 bytes, int
401 		 * 0x80 is 2 bytes. We saved this in tf_err.
402 		 */
403 		td->td_frame->tf_eip -= td->td_frame->tf_err;
404 		break;
405 
406 	case EJUSTRETURN:
407 		break;
408 
409 	default:
410 		td->td_frame->tf_eax = error;
411 		td->td_frame->tf_eflags |= PSL_C;
412 		break;
413 	}
414 }
415 
416 /*
417  * Initialize machine state, mostly pcb and trap frame for a new
418  * thread, about to return to userspace.  Put enough state in the new
419  * thread's PCB to get it to go back to the fork_return(), which
420  * finalizes the thread state and handles peculiarities of the first
421  * return to userspace for the new thread.
422  */
423 void
424 cpu_copy_thread(struct thread *td, struct thread *td0)
425 {
426 	struct pcb *pcb2;
427 
428 	/* Point the pcb to the top of the stack. */
429 	pcb2 = td->td_pcb;
430 
431 	/*
432 	 * Copy the upcall pcb.  This loads kernel regs.
433 	 * Those not loaded individually below get their default
434 	 * values here.
435 	 */
436 	bcopy(td0->td_pcb, pcb2, sizeof(*pcb2));
437 	pcb2->pcb_flags &= ~(PCB_NPXINITDONE | PCB_NPXUSERINITDONE |
438 	    PCB_KERNNPX);
439 	pcb2->pcb_save = get_pcb_user_save_pcb(pcb2);
440 	bcopy(get_pcb_user_save_td(td0), pcb2->pcb_save,
441 	    cpu_max_ext_state_size);
442 
443 	/*
444 	 * Create a new fresh stack for the new thread.
445 	 */
446 	bcopy(td0->td_frame, td->td_frame, sizeof(struct trapframe));
447 
448 	/* If the current thread has the trap bit set (i.e. a debugger had
449 	 * single stepped the process to the system call), we need to clear
450 	 * the trap flag from the new frame. Otherwise, the new thread will
451 	 * receive a (likely unexpected) SIGTRAP when it executes the first
452 	 * instruction after returning to userland.
453 	 */
454 	td->td_frame->tf_eflags &= ~PSL_T;
455 
456 	/*
457 	 * Set registers for trampoline to user mode.  Leave space for the
458 	 * return address on stack.  These are the kernel mode register values.
459 	 */
460 	pcb2->pcb_edi = 0;
461 	pcb2->pcb_esi = (int)fork_return;		    /* trampoline arg */
462 	pcb2->pcb_ebp = 0;
463 	pcb2->pcb_esp = (int)td->td_frame - sizeof(void *); /* trampoline arg */
464 	pcb2->pcb_ebx = (int)td;			    /* trampoline arg */
465 	pcb2->pcb_eip = (int)fork_trampoline + setidt_disp;
466 	pcb2->pcb_gs = rgs();
467 	/*
468 	 * If we didn't copy the pcb, we'd need to do the following registers:
469 	 * pcb2->pcb_cr3:	cloned above.
470 	 * pcb2->pcb_dr*:	cloned above.
471 	 * pcb2->pcb_savefpu:	cloned above.
472 	 * pcb2->pcb_flags:	cloned above.
473 	 * pcb2->pcb_onfault:	cloned above (always NULL here?).
474 	 * pcb2->pcb_gs:	cloned above.
475 	 * pcb2->pcb_ext:	cleared below.
476 	 */
477 	pcb2->pcb_ext = NULL;
478 
479 	/* Setup to release spin count in fork_exit(). */
480 	td->td_md.md_spinlock_count = 1;
481 	td->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
482 }
483 
484 /*
485  * Set that machine state for performing an upcall that starts
486  * the entry function with the given argument.
487  */
488 void
489 cpu_set_upcall(struct thread *td, void (*entry)(void *), void *arg,
490     stack_t *stack)
491 {
492 
493 	/*
494 	 * Do any extra cleaning that needs to be done.
495 	 * The thread may have optional components
496 	 * that are not present in a fresh thread.
497 	 * This may be a recycled thread so make it look
498 	 * as though it's newly allocated.
499 	 */
500 	cpu_thread_clean(td);
501 
502 	/*
503 	 * Set the trap frame to point at the beginning of the entry
504 	 * function.
505 	 */
506 	td->td_frame->tf_ebp = 0;
507 	td->td_frame->tf_esp =
508 	    (((int)stack->ss_sp + stack->ss_size - 4) & ~0x0f) - 4;
509 	td->td_frame->tf_eip = (int)entry;
510 
511 	/* Return address sentinel value to stop stack unwinding. */
512 	suword((void *)td->td_frame->tf_esp, 0);
513 
514 	/* Pass the argument to the entry point. */
515 	suword((void *)(td->td_frame->tf_esp + sizeof(void *)),
516 	    (int)arg);
517 }
518 
519 int
520 cpu_set_user_tls(struct thread *td, void *tls_base)
521 {
522 	struct segment_descriptor sd;
523 	uint32_t base;
524 
525 	/*
526 	 * Construct a descriptor and store it in the pcb for
527 	 * the next context switch.  Also store it in the gdt
528 	 * so that the load of tf_fs into %fs will activate it
529 	 * at return to userland.
530 	 */
531 	base = (uint32_t)tls_base;
532 	sd.sd_lobase = base & 0xffffff;
533 	sd.sd_hibase = (base >> 24) & 0xff;
534 	sd.sd_lolimit = 0xffff;	/* 4GB limit, wraps around */
535 	sd.sd_hilimit = 0xf;
536 	sd.sd_type  = SDT_MEMRWA;
537 	sd.sd_dpl   = SEL_UPL;
538 	sd.sd_p     = 1;
539 	sd.sd_xx    = 0;
540 	sd.sd_def32 = 1;
541 	sd.sd_gran  = 1;
542 	critical_enter();
543 	/* set %gs */
544 	td->td_pcb->pcb_gsd = sd;
545 	if (td == curthread) {
546 		PCPU_GET(fsgs_gdt)[1] = sd;
547 		load_gs(GSEL(GUGS_SEL, SEL_UPL));
548 	}
549 	critical_exit();
550 	return (0);
551 }
552 
553 /*
554  * Convert kernel VA to physical address
555  */
556 vm_paddr_t
557 kvtop(void *addr)
558 {
559 	vm_paddr_t pa;
560 
561 	pa = pmap_kextract((vm_offset_t)addr);
562 	if (pa == 0)
563 		panic("kvtop: zero page frame");
564 	return (pa);
565 }
566 
567 /*
568  * Get an sf_buf from the freelist.  May block if none are available.
569  */
570 void
571 sf_buf_map(struct sf_buf *sf, int flags)
572 {
573 
574 	pmap_sf_buf_map(sf);
575 #ifdef SMP
576 	sf_buf_shootdown(sf, flags);
577 #endif
578 }
579 
580 #ifdef SMP
581 static void
582 sf_buf_shootdown_curcpu_cb(pmap_t pmap __unused,
583     vm_offset_t addr1 __unused, vm_offset_t addr2 __unused)
584 {
585 }
586 
587 void
588 sf_buf_shootdown(struct sf_buf *sf, int flags)
589 {
590 	cpuset_t other_cpus;
591 	u_int cpuid;
592 
593 	sched_pin();
594 	cpuid = PCPU_GET(cpuid);
595 	if (!CPU_ISSET(cpuid, &sf->cpumask)) {
596 		CPU_SET(cpuid, &sf->cpumask);
597 		invlpg(sf->kva);
598 	}
599 	if ((flags & SFB_CPUPRIVATE) == 0) {
600 		other_cpus = all_cpus;
601 		CPU_CLR(cpuid, &other_cpus);
602 		CPU_ANDNOT(&other_cpus, &sf->cpumask);
603 		if (!CPU_EMPTY(&other_cpus)) {
604 			CPU_OR(&sf->cpumask, &other_cpus);
605 			smp_masked_invlpg(other_cpus, sf->kva, kernel_pmap,
606 			    sf_buf_shootdown_curcpu_cb);
607 		}
608 	}
609 	sched_unpin();
610 }
611 #endif
612 
613 /*
614  * MD part of sf_buf_free().
615  */
616 int
617 sf_buf_unmap(struct sf_buf *sf)
618 {
619 
620 	return (0);
621 }
622 
623 static void
624 sf_buf_invalidate(struct sf_buf *sf)
625 {
626 	vm_page_t m = sf->m;
627 
628 	/*
629 	 * Use pmap_qenter to update the pte for
630 	 * existing mapping, in particular, the PAT
631 	 * settings are recalculated.
632 	 */
633 	pmap_qenter(sf->kva, &m, 1);
634 	pmap_invalidate_cache_range(sf->kva, sf->kva + PAGE_SIZE);
635 }
636 
637 /*
638  * Invalidate the cache lines that may belong to the page, if
639  * (possibly old) mapping of the page by sf buffer exists.  Returns
640  * TRUE when mapping was found and cache invalidated.
641  */
642 boolean_t
643 sf_buf_invalidate_cache(vm_page_t m)
644 {
645 
646 	return (sf_buf_process_page(m, sf_buf_invalidate));
647 }
648 
649 /*
650  * Software interrupt handler for queued VM system processing.
651  */
652 void
653 swi_vm(void *dummy)
654 {
655 	if (busdma_swi_pending != 0)
656 		busdma_swi();
657 }
658 
659 /*
660  * Tell whether this address is in some physical memory region.
661  * Currently used by the kernel coredump code in order to avoid
662  * dumping the ``ISA memory hole'' which could cause indefinite hangs,
663  * or other unpredictable behaviour.
664  */
665 
666 int
667 is_physical_memory(vm_paddr_t addr)
668 {
669 
670 #ifdef DEV_ISA
671 	/* The ISA ``memory hole''. */
672 	if (addr >= 0xa0000 && addr < 0x100000)
673 		return 0;
674 #endif
675 
676 	/*
677 	 * stuff other tests for known memory-mapped devices (PCI?)
678 	 * here
679 	 */
680 
681 	return 1;
682 }
683