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 * Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$
41 */
42
43 #include <sys/cdefs.h>
44 #include "opt_isa.h"
45 #include "opt_npx.h"
46 #include "opt_reset.h"
47 #include "opt_cpu.h"
48
49 #include <sys/param.h>
50 #include <sys/systm.h>
51 #include <sys/bio.h>
52 #include <sys/buf.h>
53 #include <sys/kernel.h>
54 #include <sys/ktr.h>
55 #include <sys/lock.h>
56 #include <sys/malloc.h>
57 #include <sys/mbuf.h>
58 #include <sys/mutex.h>
59 #include <sys/proc.h>
60 #include <sys/sysent.h>
61 #include <sys/sf_buf.h>
62 #include <sys/smp.h>
63 #include <sys/sched.h>
64 #include <sys/sysctl.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/cputypes.h>
71 #include <machine/md_var.h>
72 #include <machine/pcb.h>
73 #include <machine/pcb_ext.h>
74 #include <machine/smp.h>
75 #include <machine/vm86.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 _Static_assert(__OFFSETOF_MONITORBUF == offsetof(struct pcpu, pc_monitorbuf),
85 "__OFFSETOF_MONITORBUF does not correspond with offset of pc_monitorbuf.");
86
87 union savefpu *
get_pcb_user_save_td(struct thread * td)88 get_pcb_user_save_td(struct thread *td)
89 {
90 vm_offset_t p;
91
92 p = td->td_kstack + td->td_kstack_pages * PAGE_SIZE -
93 roundup2(cpu_max_ext_state_size, XSAVE_AREA_ALIGN);
94 KASSERT((p % XSAVE_AREA_ALIGN) == 0, ("Unaligned pcb_user_save area"));
95 return ((union savefpu *)p);
96 }
97
98 union savefpu *
get_pcb_user_save_pcb(struct pcb * pcb)99 get_pcb_user_save_pcb(struct pcb *pcb)
100 {
101 vm_offset_t p;
102
103 p = (vm_offset_t)(pcb + 1);
104 return ((union savefpu *)p);
105 }
106
107 struct pcb *
get_pcb_td(struct thread * td)108 get_pcb_td(struct thread *td)
109 {
110 vm_offset_t p;
111
112 p = td->td_kstack + td->td_kstack_pages * PAGE_SIZE -
113 roundup2(cpu_max_ext_state_size, XSAVE_AREA_ALIGN) -
114 sizeof(struct pcb);
115 return ((struct pcb *)p);
116 }
117
118 void *
alloc_fpusave(int flags)119 alloc_fpusave(int flags)
120 {
121 void *res;
122 struct savefpu_ymm *sf;
123
124 res = malloc(cpu_max_ext_state_size, M_DEVBUF, flags);
125 if (use_xsave) {
126 sf = (struct savefpu_ymm *)res;
127 bzero(&sf->sv_xstate.sx_hd, sizeof(sf->sv_xstate.sx_hd));
128 sf->sv_xstate.sx_hd.xstate_bv = xsave_mask;
129 }
130 return (res);
131 }
132
133 /*
134 * Common code shared between cpu_fork() and cpu_copy_thread() for
135 * initializing a thread.
136 */
137 static void
copy_thread(struct thread * td1,struct thread * td2)138 copy_thread(struct thread *td1, struct thread *td2)
139 {
140 struct pcb *pcb2;
141
142 pcb2 = td2->td_pcb;
143
144 /* Ensure that td1's pcb is up to date for user threads. */
145 if ((td2->td_pflags & TDP_KTHREAD) == 0) {
146 MPASS(td1 == curthread);
147 td1->td_pcb->pcb_gs = rgs();
148 critical_enter();
149 if (PCPU_GET(fpcurthread) == td1)
150 npxsave(td1->td_pcb->pcb_save);
151 critical_exit();
152 }
153
154 /* Copy td1's pcb */
155 bcopy(td1->td_pcb, pcb2, sizeof(*pcb2));
156
157 /* Properly initialize pcb_save */
158 pcb2->pcb_save = get_pcb_user_save_pcb(pcb2);
159
160 /* Kernel threads start with clean NPX and segment bases. */
161 if ((td2->td_pflags & TDP_KTHREAD) != 0) {
162 pcb2->pcb_gs = _udatasel;
163 set_fsbase(td2, 0);
164 set_gsbase(td2, 0);
165 pcb2->pcb_flags &= ~(PCB_NPXINITDONE | PCB_NPXUSERINITDONE |
166 PCB_KERNNPX | PCB_KERNNPX_THR);
167 } else {
168 MPASS((pcb2->pcb_flags & (PCB_KERNNPX | PCB_KERNNPX_THR)) == 0);
169 bcopy(get_pcb_user_save_td(td1), get_pcb_user_save_pcb(pcb2),
170 cpu_max_ext_state_size);
171 }
172
173 /*
174 * Set registers for trampoline to user mode. Leave space for the
175 * return address on stack. These are the kernel mode register values.
176 */
177 pcb2->pcb_edi = 0;
178 pcb2->pcb_esi = (int)fork_return; /* trampoline arg */
179 pcb2->pcb_ebp = 0;
180 pcb2->pcb_esp = (int)td2->td_frame - sizeof(void *); /* trampoline arg */
181 pcb2->pcb_ebx = (int)td2; /* trampoline arg */
182 pcb2->pcb_eip = (int)fork_trampoline + setidt_disp;
183 /*
184 * If we didn't copy the pcb, we'd need to do the following registers:
185 * pcb2->pcb_cr3: cloned above.
186 * pcb2->pcb_dr*: cloned above.
187 * pcb2->pcb_savefpu: cloned above.
188 * pcb2->pcb_flags: cloned above.
189 * pcb2->pcb_onfault: cloned above (always NULL here?).
190 * pcb2->pcb_gs: cloned above.
191 * pcb2->pcb_ext: cleared below.
192 */
193 pcb2->pcb_ext = NULL;
194
195 /* Setup to release spin count in fork_exit(). */
196 td2->td_md.md_spinlock_count = 1;
197 td2->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
198 }
199
200 /*
201 * Finish a fork operation, with process p2 nearly set up.
202 * Copy and update the pcb, set up the stack so that the child
203 * ready to run and return to user mode.
204 */
205 void
cpu_fork(struct thread * td1,struct proc * p2,struct thread * td2,int flags)206 cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
207 {
208 struct proc *p1;
209 struct pcb *pcb2;
210 struct mdproc *mdp2;
211
212 p1 = td1->td_proc;
213 if ((flags & RFPROC) == 0) {
214 if ((flags & RFMEM) == 0) {
215 /* unshare user LDT */
216 struct mdproc *mdp1 = &p1->p_md;
217 struct proc_ldt *pldt, *pldt1;
218
219 mtx_lock_spin(&dt_lock);
220 if ((pldt1 = mdp1->md_ldt) != NULL &&
221 pldt1->ldt_refcnt > 1) {
222 pldt = user_ldt_alloc(mdp1, pldt1->ldt_len);
223 if (pldt == NULL)
224 panic("could not copy LDT");
225 mdp1->md_ldt = pldt;
226 set_user_ldt(mdp1);
227 user_ldt_deref(pldt1);
228 } else
229 mtx_unlock_spin(&dt_lock);
230 }
231 return;
232 }
233
234 /* Point the pcb to the top of the stack */
235 pcb2 = get_pcb_td(td2);
236 td2->td_pcb = pcb2;
237
238 copy_thread(td1, td2);
239
240 /* Reset debug registers in the new process */
241 x86_clear_dbregs(pcb2);
242
243 /* Point mdproc and then copy over td1's contents */
244 mdp2 = &p2->p_md;
245 bcopy(&p1->p_md, mdp2, sizeof(*mdp2));
246
247 /*
248 * Copy the trap frame for the return to user mode as if from a
249 * syscall. This copies most of the user mode register values.
250 * The -VM86_STACK_SPACE (-16) is so we can expand the trapframe
251 * if we go to vm86.
252 */
253 td2->td_frame = (struct trapframe *)((caddr_t)td2->td_pcb -
254 VM86_STACK_SPACE) - 1;
255 bcopy(td1->td_frame, td2->td_frame, sizeof(struct trapframe));
256
257 /* Set child return values. */
258 p2->p_sysent->sv_set_fork_retval(td2);
259
260 /*
261 * If the parent process has the trap bit set (i.e. a debugger
262 * had single stepped the process to the system call), we need
263 * to clear the trap flag from the new frame.
264 */
265 td2->td_frame->tf_eflags &= ~PSL_T;
266
267 /* Set cr3 for the new process. */
268 pcb2->pcb_cr3 = pmap_get_cr3(vmspace_pmap(p2->p_vmspace));
269
270 /*
271 * XXX don't copy the i/o pages. this should probably be fixed.
272 */
273 pcb2->pcb_ext = NULL;
274
275 /* Copy the LDT, if necessary. */
276 mtx_lock_spin(&dt_lock);
277 if (mdp2->md_ldt != NULL) {
278 if (flags & RFMEM) {
279 mdp2->md_ldt->ldt_refcnt++;
280 } else {
281 mdp2->md_ldt = user_ldt_alloc(mdp2,
282 mdp2->md_ldt->ldt_len);
283 if (mdp2->md_ldt == NULL)
284 panic("could not copy LDT");
285 }
286 }
287 mtx_unlock_spin(&dt_lock);
288
289 /*
290 * Now, cpu_switch() can schedule the new process.
291 * pcb_esp is loaded pointing to the cpu_switch() stack frame
292 * containing the return address when exiting cpu_switch.
293 * This will normally be to fork_trampoline(), which will have
294 * %ebx loaded with the new proc's pointer. fork_trampoline()
295 * will set up a stack to call fork_return(p, frame); to complete
296 * the return to user-mode.
297 */
298 }
299
300 void
x86_set_fork_retval(struct thread * td)301 x86_set_fork_retval(struct thread *td)
302 {
303 struct trapframe * frame = td->td_frame;
304
305 frame->tf_eax = 0; /* Child returns zero */
306 frame->tf_eflags &= ~PSL_C; /* success */
307 frame->tf_edx = 1; /* System V emulation */
308 }
309
310 /*
311 * Intercept the return address from a freshly forked process that has NOT
312 * been scheduled yet.
313 *
314 * This is needed to make kernel threads stay in kernel mode.
315 */
316 void
cpu_fork_kthread_handler(struct thread * td,void (* func)(void *),void * arg)317 cpu_fork_kthread_handler(struct thread *td, void (*func)(void *), void *arg)
318 {
319 /*
320 * Note that the trap frame follows the args, so the function
321 * is really called like this: func(arg, frame);
322 */
323 td->td_pcb->pcb_esi = (int) func; /* function */
324 td->td_pcb->pcb_ebx = (int) arg; /* first arg */
325 }
326
327 void
cpu_exit(struct thread * td)328 cpu_exit(struct thread *td)
329 {
330
331 /*
332 * If this process has a custom LDT, release it. Reset pc->pcb_gs
333 * and %gs before we free it in case they refer to an LDT entry.
334 */
335 mtx_lock_spin(&dt_lock);
336 if (td->td_proc->p_md.md_ldt) {
337 td->td_pcb->pcb_gs = _udatasel;
338 load_gs(_udatasel);
339 user_ldt_free(td);
340 } else
341 mtx_unlock_spin(&dt_lock);
342 }
343
344 void
cpu_thread_exit(struct thread * td)345 cpu_thread_exit(struct thread *td)
346 {
347
348 critical_enter();
349 if (td == PCPU_GET(fpcurthread))
350 npxdrop();
351 critical_exit();
352
353 /* Disable any hardware breakpoints. */
354 if (td->td_pcb->pcb_flags & PCB_DBREGS) {
355 reset_dbregs();
356 td->td_pcb->pcb_flags &= ~PCB_DBREGS;
357 }
358 }
359
360 void
cpu_thread_clean(struct thread * td)361 cpu_thread_clean(struct thread *td)
362 {
363 struct pcb *pcb;
364
365 pcb = td->td_pcb;
366 if (pcb->pcb_ext != NULL) {
367 /* if (pcb->pcb_ext->ext_refcount-- == 1) ?? */
368 /*
369 * XXX do we need to move the TSS off the allocated pages
370 * before freeing them? (not done here)
371 */
372 pmap_trm_free(pcb->pcb_ext, ctob(IOPAGES + 1));
373 pcb->pcb_ext = NULL;
374 }
375 }
376
377 void
cpu_thread_swapin(struct thread * td)378 cpu_thread_swapin(struct thread *td)
379 {
380 }
381
382 void
cpu_thread_swapout(struct thread * td)383 cpu_thread_swapout(struct thread *td)
384 {
385 }
386
387 void
cpu_thread_alloc(struct thread * td)388 cpu_thread_alloc(struct thread *td)
389 {
390 struct pcb *pcb;
391 struct xstate_hdr *xhdr;
392
393 td->td_pcb = pcb = get_pcb_td(td);
394 td->td_frame = (struct trapframe *)((caddr_t)pcb -
395 VM86_STACK_SPACE) - 1;
396 pcb->pcb_ext = NULL;
397 pcb->pcb_save = get_pcb_user_save_pcb(pcb);
398 if (use_xsave) {
399 xhdr = (struct xstate_hdr *)(pcb->pcb_save + 1);
400 bzero(xhdr, sizeof(*xhdr));
401 xhdr->xstate_bv = xsave_mask;
402 }
403 }
404
405 void
cpu_thread_free(struct thread * td)406 cpu_thread_free(struct thread *td)
407 {
408
409 cpu_thread_clean(td);
410 }
411
412 bool
cpu_exec_vmspace_reuse(struct proc * p __unused,vm_map_t map __unused)413 cpu_exec_vmspace_reuse(struct proc *p __unused, vm_map_t map __unused)
414 {
415
416 return (true);
417 }
418
419 int
cpu_procctl(struct thread * td __unused,int idtype __unused,id_t id __unused,int com __unused,void * data __unused)420 cpu_procctl(struct thread *td __unused, int idtype __unused, id_t id __unused,
421 int com __unused, void *data __unused)
422 {
423
424 return (EINVAL);
425 }
426
427 void
cpu_set_syscall_retval(struct thread * td,int error)428 cpu_set_syscall_retval(struct thread *td, int error)
429 {
430
431 switch (error) {
432 case 0:
433 td->td_frame->tf_eax = td->td_retval[0];
434 td->td_frame->tf_edx = td->td_retval[1];
435 td->td_frame->tf_eflags &= ~PSL_C;
436 break;
437
438 case ERESTART:
439 /*
440 * Reconstruct pc, assuming lcall $X,y is 7 bytes, int
441 * 0x80 is 2 bytes. We saved this in tf_err.
442 */
443 td->td_frame->tf_eip -= td->td_frame->tf_err;
444 break;
445
446 case EJUSTRETURN:
447 break;
448
449 default:
450 td->td_frame->tf_eax = error;
451 td->td_frame->tf_eflags |= PSL_C;
452 break;
453 }
454 }
455
456 /*
457 * Initialize machine state, mostly pcb and trap frame for a new
458 * thread, about to return to userspace. Put enough state in the new
459 * thread's PCB to get it to go back to the fork_return(), which
460 * finalizes the thread state and handles peculiarities of the first
461 * return to userspace for the new thread.
462 */
463 void
cpu_copy_thread(struct thread * td,struct thread * td0)464 cpu_copy_thread(struct thread *td, struct thread *td0)
465 {
466 copy_thread(td0, td);
467
468 /*
469 * Copy user general-purpose registers.
470 *
471 * Some of these registers are rewritten by cpu_set_upcall()
472 * and linux_set_upcall().
473 */
474 bcopy(td0->td_frame, td->td_frame, sizeof(struct trapframe));
475
476 /* If the current thread has the trap bit set (i.e. a debugger had
477 * single stepped the process to the system call), we need to clear
478 * the trap flag from the new frame. Otherwise, the new thread will
479 * receive a (likely unexpected) SIGTRAP when it executes the first
480 * instruction after returning to userland.
481 */
482 td->td_frame->tf_eflags &= ~PSL_T;
483 }
484
485 /*
486 * Set that machine state for performing an upcall that starts
487 * the entry function with the given argument.
488 */
489 int
cpu_set_upcall(struct thread * td,void (* entry)(void *),void * arg,stack_t * stack)490 cpu_set_upcall(struct thread *td, void (*entry)(void *), void *arg,
491 stack_t *stack)
492 {
493
494 /*
495 * Do any extra cleaning that needs to be done.
496 * The thread may have optional components
497 * that are not present in a fresh thread.
498 * This may be a recycled thread so make it look
499 * as though it's newly allocated.
500 */
501 cpu_thread_clean(td);
502
503 /*
504 * Set the trap frame to point at the beginning of the entry
505 * function.
506 */
507 td->td_frame->tf_ebp = 0;
508 td->td_frame->tf_esp =
509 (((int)stack->ss_sp + stack->ss_size - 4) & ~0x0f) - 4;
510 td->td_frame->tf_eip = (int)entry;
511
512 /* Return address sentinel value to stop stack unwinding. */
513 if (suword((void *)td->td_frame->tf_esp, 0) != 0)
514 return (EFAULT);
515
516 /* Pass the argument to the entry point. */
517 if (suword((void *)(td->td_frame->tf_esp + sizeof(void *)),
518 (int)arg) != 0)
519 return (EFAULT);
520 return (0);
521 }
522
523 int
cpu_set_user_tls(struct thread * td,void * tls_base)524 cpu_set_user_tls(struct thread *td, void *tls_base)
525 {
526 struct segment_descriptor sd;
527 uint32_t base;
528
529 /*
530 * Construct a descriptor and store it in the pcb for
531 * the next context switch. Also store it in the gdt
532 * so that the load of tf_fs into %fs will activate it
533 * at return to userland.
534 */
535 base = (uint32_t)tls_base;
536 sd.sd_lobase = base & 0xffffff;
537 sd.sd_hibase = (base >> 24) & 0xff;
538 sd.sd_lolimit = 0xffff; /* 4GB limit, wraps around */
539 sd.sd_hilimit = 0xf;
540 sd.sd_type = SDT_MEMRWA;
541 sd.sd_dpl = SEL_UPL;
542 sd.sd_p = 1;
543 sd.sd_xx = 0;
544 sd.sd_def32 = 1;
545 sd.sd_gran = 1;
546 critical_enter();
547 /* set %gs */
548 td->td_pcb->pcb_gsd = sd;
549 if (td == curthread) {
550 PCPU_GET(fsgs_gdt)[1] = sd;
551 load_gs(GSEL(GUGS_SEL, SEL_UPL));
552 }
553 critical_exit();
554 return (0);
555 }
556
557 /*
558 * Convert kernel VA to physical address
559 */
560 vm_paddr_t
kvtop(void * addr)561 kvtop(void *addr)
562 {
563 vm_paddr_t pa;
564
565 pa = pmap_kextract((vm_offset_t)addr);
566 if (pa == 0)
567 panic("kvtop: zero page frame");
568 return (pa);
569 }
570
571 /*
572 * Get an sf_buf from the freelist. May block if none are available.
573 */
574 void
sf_buf_map(struct sf_buf * sf,int flags)575 sf_buf_map(struct sf_buf *sf, int flags)
576 {
577
578 pmap_sf_buf_map(sf);
579 #ifdef SMP
580 sf_buf_shootdown(sf, flags);
581 #endif
582 }
583
584 #ifdef SMP
585 static void
sf_buf_shootdown_curcpu_cb(pmap_t pmap __unused,vm_offset_t addr1 __unused,vm_offset_t addr2 __unused)586 sf_buf_shootdown_curcpu_cb(pmap_t pmap __unused,
587 vm_offset_t addr1 __unused, vm_offset_t addr2 __unused)
588 {
589 }
590
591 void
sf_buf_shootdown(struct sf_buf * sf,int flags)592 sf_buf_shootdown(struct sf_buf *sf, int flags)
593 {
594 cpuset_t other_cpus;
595 u_int cpuid;
596
597 sched_pin();
598 cpuid = PCPU_GET(cpuid);
599 if (!CPU_ISSET(cpuid, &sf->cpumask)) {
600 CPU_SET(cpuid, &sf->cpumask);
601 invlpg(sf->kva);
602 }
603 if ((flags & SFB_CPUPRIVATE) == 0) {
604 other_cpus = all_cpus;
605 CPU_CLR(cpuid, &other_cpus);
606 CPU_ANDNOT(&other_cpus, &other_cpus, &sf->cpumask);
607 if (!CPU_EMPTY(&other_cpus)) {
608 CPU_OR(&sf->cpumask, &sf->cpumask, &other_cpus);
609 smp_masked_invlpg(other_cpus, sf->kva, kernel_pmap,
610 sf_buf_shootdown_curcpu_cb);
611 }
612 }
613 sched_unpin();
614 }
615 #endif
616
617 /*
618 * MD part of sf_buf_free().
619 */
620 int
sf_buf_unmap(struct sf_buf * sf)621 sf_buf_unmap(struct sf_buf *sf)
622 {
623
624 return (0);
625 }
626
627 static void
sf_buf_invalidate(struct sf_buf * sf)628 sf_buf_invalidate(struct sf_buf *sf)
629 {
630 vm_page_t m = sf->m;
631
632 /*
633 * Use pmap_qenter to update the pte for
634 * existing mapping, in particular, the PAT
635 * settings are recalculated.
636 */
637 pmap_qenter(sf->kva, &m, 1);
638 pmap_invalidate_cache_range(sf->kva, sf->kva + PAGE_SIZE);
639 }
640
641 /*
642 * Invalidate the cache lines that may belong to the page, if
643 * (possibly old) mapping of the page by sf buffer exists. Returns
644 * TRUE when mapping was found and cache invalidated.
645 */
646 boolean_t
sf_buf_invalidate_cache(vm_page_t m)647 sf_buf_invalidate_cache(vm_page_t m)
648 {
649
650 return (sf_buf_process_page(m, sf_buf_invalidate));
651 }
652