The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/i386/i386/vm_machdep.c

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    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 /*
  138  * Common code shared between cpu_fork() and cpu_copy_thread() for
  139  * initializing a thread.
  140  */
  141 static void
  142 copy_thread(struct thread *td1, struct thread *td2)
  143 {
  144         struct pcb *pcb2;
  145 
  146         pcb2 = td2->td_pcb;
  147 
  148         /* Ensure that td1's pcb is up to date for user threads. */
  149         if ((td2->td_pflags & TDP_KTHREAD) == 0) {
  150                 MPASS(td1 == curthread);
  151                 td1->td_pcb->pcb_gs = rgs();
  152                 critical_enter();
  153                 if (PCPU_GET(fpcurthread) == td1)
  154                         npxsave(td1->td_pcb->pcb_save);
  155                 critical_exit();
  156         }
  157 
  158         /* Copy td1's pcb */
  159         bcopy(td1->td_pcb, pcb2, sizeof(*pcb2));
  160 
  161         /* Properly initialize pcb_save */
  162         pcb2->pcb_save = get_pcb_user_save_pcb(pcb2);
  163 
  164         /* Kernel threads start with clean NPX and segment bases. */
  165         if ((td2->td_pflags & TDP_KTHREAD) != 0) {
  166                 pcb2->pcb_gs = _udatasel;
  167                 set_fsbase(td2, 0);
  168                 set_gsbase(td2, 0);
  169                 pcb2->pcb_flags &= ~(PCB_NPXINITDONE | PCB_NPXUSERINITDONE |
  170                     PCB_KERNNPX | PCB_KERNNPX_THR);
  171         } else {
  172                 MPASS((pcb2->pcb_flags & (PCB_KERNNPX | PCB_KERNNPX_THR)) == 0);
  173                 bcopy(get_pcb_user_save_td(td1), get_pcb_user_save_pcb(pcb2),
  174                     cpu_max_ext_state_size);
  175         }
  176 
  177         /*
  178          * Set registers for trampoline to user mode.  Leave space for the
  179          * return address on stack.  These are the kernel mode register values.
  180          */
  181         pcb2->pcb_edi = 0;
  182         pcb2->pcb_esi = (int)fork_return;                   /* trampoline arg */
  183         pcb2->pcb_ebp = 0;
  184         pcb2->pcb_esp = (int)td2->td_frame - sizeof(void *); /* trampoline arg */
  185         pcb2->pcb_ebx = (int)td2;                           /* trampoline arg */
  186         pcb2->pcb_eip = (int)fork_trampoline + setidt_disp;
  187         /*
  188          * If we didn't copy the pcb, we'd need to do the following registers:
  189          * pcb2->pcb_cr3:       cloned above.
  190          * pcb2->pcb_dr*:       cloned above.
  191          * pcb2->pcb_savefpu:   cloned above.
  192          * pcb2->pcb_flags:     cloned above.
  193          * pcb2->pcb_onfault:   cloned above (always NULL here?).
  194          * pcb2->pcb_gs:        cloned above.
  195          * pcb2->pcb_ext:       cleared below.
  196          */
  197         pcb2->pcb_ext = NULL;
  198 
  199         /* Setup to release spin count in fork_exit(). */
  200         td2->td_md.md_spinlock_count = 1;
  201         td2->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
  202 }
  203 
  204 /*
  205  * Finish a fork operation, with process p2 nearly set up.
  206  * Copy and update the pcb, set up the stack so that the child
  207  * ready to run and return to user mode.
  208  */
  209 void
  210 cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
  211 {
  212         struct proc *p1;
  213         struct pcb *pcb2;
  214         struct mdproc *mdp2;
  215 
  216         p1 = td1->td_proc;
  217         if ((flags & RFPROC) == 0) {
  218                 if ((flags & RFMEM) == 0) {
  219                         /* unshare user LDT */
  220                         struct mdproc *mdp1 = &p1->p_md;
  221                         struct proc_ldt *pldt, *pldt1;
  222 
  223                         mtx_lock_spin(&dt_lock);
  224                         if ((pldt1 = mdp1->md_ldt) != NULL &&
  225                             pldt1->ldt_refcnt > 1) {
  226                                 pldt = user_ldt_alloc(mdp1, pldt1->ldt_len);
  227                                 if (pldt == NULL)
  228                                         panic("could not copy LDT");
  229                                 mdp1->md_ldt = pldt;
  230                                 set_user_ldt(mdp1);
  231                                 user_ldt_deref(pldt1);
  232                         } else
  233                                 mtx_unlock_spin(&dt_lock);
  234                 }
  235                 return;
  236         }
  237 
  238         /* Point the pcb to the top of the stack */
  239         pcb2 = get_pcb_td(td2);
  240         td2->td_pcb = pcb2;
  241 
  242         copy_thread(td1, td2);
  243 
  244         /* Reset debug registers in the new process */
  245         x86_clear_dbregs(pcb2);
  246 
  247         /* Point mdproc and then copy over td1's contents */
  248         mdp2 = &p2->p_md;
  249         bcopy(&p1->p_md, mdp2, sizeof(*mdp2));
  250 
  251         /*
  252          * Copy the trap frame for the return to user mode as if from a
  253          * syscall.  This copies most of the user mode register values.
  254          * The -VM86_STACK_SPACE (-16) is so we can expand the trapframe
  255          * if we go to vm86.
  256          */
  257         td2->td_frame = (struct trapframe *)((caddr_t)td2->td_pcb -
  258             VM86_STACK_SPACE) - 1;
  259         bcopy(td1->td_frame, td2->td_frame, sizeof(struct trapframe));
  260 
  261         td2->td_frame->tf_eax = 0;              /* Child returns zero */
  262         td2->td_frame->tf_eflags &= ~PSL_C;     /* success */
  263         td2->td_frame->tf_edx = 1;
  264 
  265         /*
  266          * If the parent process has the trap bit set (i.e. a debugger
  267          * had single stepped the process to the system call), we need
  268          * to clear the trap flag from the new frame.
  269          */
  270         td2->td_frame->tf_eflags &= ~PSL_T;
  271 
  272         /* Set cr3 for the new process. */
  273         pcb2->pcb_cr3 = pmap_get_cr3(vmspace_pmap(p2->p_vmspace));
  274 
  275         /*
  276          * XXX don't copy the i/o pages.  this should probably be fixed.
  277          */
  278         pcb2->pcb_ext = NULL;
  279 
  280         /* Copy the LDT, if necessary. */
  281         mtx_lock_spin(&dt_lock);
  282         if (mdp2->md_ldt != NULL) {
  283                 if (flags & RFMEM) {
  284                         mdp2->md_ldt->ldt_refcnt++;
  285                 } else {
  286                         mdp2->md_ldt = user_ldt_alloc(mdp2,
  287                             mdp2->md_ldt->ldt_len);
  288                         if (mdp2->md_ldt == NULL)
  289                                 panic("could not copy LDT");
  290                 }
  291         }
  292         mtx_unlock_spin(&dt_lock);
  293 
  294         /*
  295          * Now, cpu_switch() can schedule the new process.
  296          * pcb_esp is loaded pointing to the cpu_switch() stack frame
  297          * containing the return address when exiting cpu_switch.
  298          * This will normally be to fork_trampoline(), which will have
  299          * %ebx loaded with the new proc's pointer.  fork_trampoline()
  300          * will set up a stack to call fork_return(p, frame); to complete
  301          * the return to user-mode.
  302          */
  303 }
  304 
  305 /*
  306  * Intercept the return address from a freshly forked process that has NOT
  307  * been scheduled yet.
  308  *
  309  * This is needed to make kernel threads stay in kernel mode.
  310  */
  311 void
  312 cpu_fork_kthread_handler(struct thread *td, void (*func)(void *), void *arg)
  313 {
  314         /*
  315          * Note that the trap frame follows the args, so the function
  316          * is really called like this:  func(arg, frame);
  317          */
  318         td->td_pcb->pcb_esi = (int) func;       /* function */
  319         td->td_pcb->pcb_ebx = (int) arg;        /* first arg */
  320 }
  321 
  322 void
  323 cpu_exit(struct thread *td)
  324 {
  325 
  326         /*
  327          * If this process has a custom LDT, release it.  Reset pc->pcb_gs
  328          * and %gs before we free it in case they refer to an LDT entry.
  329          */
  330         mtx_lock_spin(&dt_lock);
  331         if (td->td_proc->p_md.md_ldt) {
  332                 td->td_pcb->pcb_gs = _udatasel;
  333                 load_gs(_udatasel);
  334                 user_ldt_free(td);
  335         } else
  336                 mtx_unlock_spin(&dt_lock);
  337 }
  338 
  339 void
  340 cpu_thread_exit(struct thread *td)
  341 {
  342 
  343         critical_enter();
  344         if (td == PCPU_GET(fpcurthread))
  345                 npxdrop();
  346         critical_exit();
  347 
  348         /* Disable any hardware breakpoints. */
  349         if (td->td_pcb->pcb_flags & PCB_DBREGS) {
  350                 reset_dbregs();
  351                 td->td_pcb->pcb_flags &= ~PCB_DBREGS;
  352         }
  353 }
  354 
  355 void
  356 cpu_thread_clean(struct thread *td)
  357 {
  358         struct pcb *pcb;
  359 
  360         pcb = td->td_pcb; 
  361         if (pcb->pcb_ext != NULL) {
  362                 /* if (pcb->pcb_ext->ext_refcount-- == 1) ?? */
  363                 /*
  364                  * XXX do we need to move the TSS off the allocated pages
  365                  * before freeing them?  (not done here)
  366                  */
  367                 pmap_trm_free(pcb->pcb_ext, ctob(IOPAGES + 1));
  368                 pcb->pcb_ext = NULL;
  369         }
  370 }
  371 
  372 void
  373 cpu_thread_swapin(struct thread *td)
  374 {
  375 }
  376 
  377 void
  378 cpu_thread_swapout(struct thread *td)
  379 {
  380 }
  381 
  382 void
  383 cpu_thread_alloc(struct thread *td)
  384 {
  385         struct pcb *pcb;
  386         struct xstate_hdr *xhdr;
  387 
  388         td->td_pcb = pcb = get_pcb_td(td);
  389         td->td_frame = (struct trapframe *)((caddr_t)pcb -
  390             VM86_STACK_SPACE) - 1;
  391         pcb->pcb_ext = NULL; 
  392         pcb->pcb_save = get_pcb_user_save_pcb(pcb);
  393         if (use_xsave) {
  394                 xhdr = (struct xstate_hdr *)(pcb->pcb_save + 1);
  395                 bzero(xhdr, sizeof(*xhdr));
  396                 xhdr->xstate_bv = xsave_mask;
  397         }
  398 }
  399 
  400 void
  401 cpu_thread_free(struct thread *td)
  402 {
  403 
  404         cpu_thread_clean(td);
  405 }
  406 
  407 bool
  408 cpu_exec_vmspace_reuse(struct proc *p __unused, vm_map_t map __unused)
  409 {
  410 
  411         return (true);
  412 }
  413 
  414 int
  415 cpu_procctl(struct thread *td __unused, int idtype __unused, id_t id __unused,
  416     int com __unused, void *data __unused)
  417 {
  418 
  419         return (EINVAL);
  420 }
  421 
  422 void
  423 cpu_set_syscall_retval(struct thread *td, int error)
  424 {
  425 
  426         switch (error) {
  427         case 0:
  428                 td->td_frame->tf_eax = td->td_retval[0];
  429                 td->td_frame->tf_edx = td->td_retval[1];
  430                 td->td_frame->tf_eflags &= ~PSL_C;
  431                 break;
  432 
  433         case ERESTART:
  434                 /*
  435                  * Reconstruct pc, assuming lcall $X,y is 7 bytes, int
  436                  * 0x80 is 2 bytes. We saved this in tf_err.
  437                  */
  438                 td->td_frame->tf_eip -= td->td_frame->tf_err;
  439                 break;
  440 
  441         case EJUSTRETURN:
  442                 break;
  443 
  444         default:
  445                 td->td_frame->tf_eax = error;
  446                 td->td_frame->tf_eflags |= PSL_C;
  447                 break;
  448         }
  449 }
  450 
  451 /*
  452  * Initialize machine state, mostly pcb and trap frame for a new
  453  * thread, about to return to userspace.  Put enough state in the new
  454  * thread's PCB to get it to go back to the fork_return(), which
  455  * finalizes the thread state and handles peculiarities of the first
  456  * return to userspace for the new thread.
  457  */
  458 void
  459 cpu_copy_thread(struct thread *td, struct thread *td0)
  460 {
  461         copy_thread(td0, td);
  462 
  463         /*
  464          * Copy user general-purpose registers.
  465          *
  466          * Some of these registers are rewritten by cpu_set_upcall()
  467          * and linux_set_upcall().
  468          */
  469         bcopy(td0->td_frame, td->td_frame, sizeof(struct trapframe));
  470 
  471         /* If the current thread has the trap bit set (i.e. a debugger had
  472          * single stepped the process to the system call), we need to clear
  473          * the trap flag from the new frame. Otherwise, the new thread will
  474          * receive a (likely unexpected) SIGTRAP when it executes the first
  475          * instruction after returning to userland.
  476          */
  477         td->td_frame->tf_eflags &= ~PSL_T;
  478 }
  479 
  480 /*
  481  * Set that machine state for performing an upcall that starts
  482  * the entry function with the given argument.
  483  */
  484 void
  485 cpu_set_upcall(struct thread *td, void (*entry)(void *), void *arg,
  486     stack_t *stack)
  487 {
  488 
  489         /* 
  490          * Do any extra cleaning that needs to be done.
  491          * The thread may have optional components
  492          * that are not present in a fresh thread.
  493          * This may be a recycled thread so make it look
  494          * as though it's newly allocated.
  495          */
  496         cpu_thread_clean(td);
  497 
  498         /*
  499          * Set the trap frame to point at the beginning of the entry
  500          * function.
  501          */
  502         td->td_frame->tf_ebp = 0; 
  503         td->td_frame->tf_esp =
  504             (((int)stack->ss_sp + stack->ss_size - 4) & ~0x0f) - 4;
  505         td->td_frame->tf_eip = (int)entry;
  506 
  507         /* Return address sentinel value to stop stack unwinding. */
  508         suword((void *)td->td_frame->tf_esp, 0);
  509 
  510         /* Pass the argument to the entry point. */
  511         suword((void *)(td->td_frame->tf_esp + sizeof(void *)),
  512             (int)arg);
  513 }
  514 
  515 int
  516 cpu_set_user_tls(struct thread *td, void *tls_base)
  517 {
  518         struct segment_descriptor sd;
  519         uint32_t base;
  520 
  521         /*
  522          * Construct a descriptor and store it in the pcb for
  523          * the next context switch.  Also store it in the gdt
  524          * so that the load of tf_fs into %fs will activate it
  525          * at return to userland.
  526          */
  527         base = (uint32_t)tls_base;
  528         sd.sd_lobase = base & 0xffffff;
  529         sd.sd_hibase = (base >> 24) & 0xff;
  530         sd.sd_lolimit = 0xffff; /* 4GB limit, wraps around */
  531         sd.sd_hilimit = 0xf;
  532         sd.sd_type  = SDT_MEMRWA;
  533         sd.sd_dpl   = SEL_UPL;
  534         sd.sd_p     = 1;
  535         sd.sd_xx    = 0;
  536         sd.sd_def32 = 1;
  537         sd.sd_gran  = 1;
  538         critical_enter();
  539         /* set %gs */
  540         td->td_pcb->pcb_gsd = sd;
  541         if (td == curthread) {
  542                 PCPU_GET(fsgs_gdt)[1] = sd;
  543                 load_gs(GSEL(GUGS_SEL, SEL_UPL));
  544         }
  545         critical_exit();
  546         return (0);
  547 }
  548 
  549 /*
  550  * Convert kernel VA to physical address
  551  */
  552 vm_paddr_t
  553 kvtop(void *addr)
  554 {
  555         vm_paddr_t pa;
  556 
  557         pa = pmap_kextract((vm_offset_t)addr);
  558         if (pa == 0)
  559                 panic("kvtop: zero page frame");
  560         return (pa);
  561 }
  562 
  563 /*
  564  * Get an sf_buf from the freelist.  May block if none are available.
  565  */
  566 void
  567 sf_buf_map(struct sf_buf *sf, int flags)
  568 {
  569 
  570         pmap_sf_buf_map(sf);
  571 #ifdef SMP
  572         sf_buf_shootdown(sf, flags);
  573 #endif
  574 }
  575 
  576 #ifdef SMP
  577 static void
  578 sf_buf_shootdown_curcpu_cb(pmap_t pmap __unused,
  579     vm_offset_t addr1 __unused, vm_offset_t addr2 __unused)
  580 {
  581 }
  582 
  583 void
  584 sf_buf_shootdown(struct sf_buf *sf, int flags)
  585 {
  586         cpuset_t other_cpus;
  587         u_int cpuid;
  588 
  589         sched_pin();
  590         cpuid = PCPU_GET(cpuid);
  591         if (!CPU_ISSET(cpuid, &sf->cpumask)) {
  592                 CPU_SET(cpuid, &sf->cpumask);
  593                 invlpg(sf->kva);
  594         }
  595         if ((flags & SFB_CPUPRIVATE) == 0) {
  596                 other_cpus = all_cpus;
  597                 CPU_CLR(cpuid, &other_cpus);
  598                 CPU_ANDNOT(&other_cpus, &sf->cpumask);
  599                 if (!CPU_EMPTY(&other_cpus)) {
  600                         CPU_OR(&sf->cpumask, &other_cpus);
  601                         smp_masked_invlpg(other_cpus, sf->kva, kernel_pmap,
  602                             sf_buf_shootdown_curcpu_cb);
  603                 }
  604         }
  605         sched_unpin();
  606 }
  607 #endif
  608 
  609 /*
  610  * MD part of sf_buf_free().
  611  */
  612 int
  613 sf_buf_unmap(struct sf_buf *sf)
  614 {
  615 
  616         return (0);
  617 }
  618 
  619 static void
  620 sf_buf_invalidate(struct sf_buf *sf)
  621 {
  622         vm_page_t m = sf->m;
  623 
  624         /*
  625          * Use pmap_qenter to update the pte for
  626          * existing mapping, in particular, the PAT
  627          * settings are recalculated.
  628          */
  629         pmap_qenter(sf->kva, &m, 1);
  630         pmap_invalidate_cache_range(sf->kva, sf->kva + PAGE_SIZE);
  631 }
  632 
  633 /*
  634  * Invalidate the cache lines that may belong to the page, if
  635  * (possibly old) mapping of the page by sf buffer exists.  Returns
  636  * TRUE when mapping was found and cache invalidated.
  637  */
  638 boolean_t
  639 sf_buf_invalidate_cache(vm_page_t m)
  640 {
  641 
  642         return (sf_buf_process_page(m, sf_buf_invalidate));
  643 }
  644 
  645 /*
  646  * Software interrupt handler for queued VM system processing.
  647  */   
  648 void  
  649 swi_vm(void *dummy) 
  650 {     
  651         if (busdma_swi_pending != 0)
  652                 busdma_swi();
  653 }
  654 
  655 /*
  656  * Tell whether this address is in some physical memory region.
  657  * Currently used by the kernel coredump code in order to avoid
  658  * dumping the ``ISA memory hole'' which could cause indefinite hangs,
  659  * or other unpredictable behaviour.
  660  */
  661 
  662 int
  663 is_physical_memory(vm_paddr_t addr)
  664 {
  665 
  666 #ifdef DEV_ISA
  667         /* The ISA ``memory hole''. */
  668         if (addr >= 0xa0000 && addr < 0x100000)
  669                 return 0;
  670 #endif
  671 
  672         /*
  673          * stuff other tests for known memory-mapped devices (PCI?)
  674          * here
  675          */
  676 
  677         return 1;
  678 }

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