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         /* Set child return values. */
  262         p2->p_sysent->sv_set_fork_retval(td2);
  263 
  264         /*
  265          * If the parent process has the trap bit set (i.e. a debugger
  266          * had single stepped the process to the system call), we need
  267          * to clear the trap flag from the new frame.
  268          */
  269         td2->td_frame->tf_eflags &= ~PSL_T;
  270 
  271         /* Set cr3 for the new process. */
  272         pcb2->pcb_cr3 = pmap_get_cr3(vmspace_pmap(p2->p_vmspace));
  273 
  274         /*
  275          * XXX don't copy the i/o pages.  this should probably be fixed.
  276          */
  277         pcb2->pcb_ext = NULL;
  278 
  279         /* Copy the LDT, if necessary. */
  280         mtx_lock_spin(&dt_lock);
  281         if (mdp2->md_ldt != NULL) {
  282                 if (flags & RFMEM) {
  283                         mdp2->md_ldt->ldt_refcnt++;
  284                 } else {
  285                         mdp2->md_ldt = user_ldt_alloc(mdp2,
  286                             mdp2->md_ldt->ldt_len);
  287                         if (mdp2->md_ldt == NULL)
  288                                 panic("could not copy LDT");
  289                 }
  290         }
  291         mtx_unlock_spin(&dt_lock);
  292 
  293         /*
  294          * Now, cpu_switch() can schedule the new process.
  295          * pcb_esp is loaded pointing to the cpu_switch() stack frame
  296          * containing the return address when exiting cpu_switch.
  297          * This will normally be to fork_trampoline(), which will have
  298          * %ebx loaded with the new proc's pointer.  fork_trampoline()
  299          * will set up a stack to call fork_return(p, frame); to complete
  300          * the return to user-mode.
  301          */
  302 }
  303 
  304 void
  305 x86_set_fork_retval(struct thread *td)
  306 {
  307         struct trapframe * frame = td->td_frame;
  308 
  309         frame->tf_eax = 0;              /* Child returns zero */
  310         frame->tf_eflags &= ~PSL_C;     /* success */
  311         frame->tf_edx = 1;              /* System V emulation */
  312 }
  313 
  314 /*
  315  * Intercept the return address from a freshly forked process that has NOT
  316  * been scheduled yet.
  317  *
  318  * This is needed to make kernel threads stay in kernel mode.
  319  */
  320 void
  321 cpu_fork_kthread_handler(struct thread *td, void (*func)(void *), void *arg)
  322 {
  323         /*
  324          * Note that the trap frame follows the args, so the function
  325          * is really called like this:  func(arg, frame);
  326          */
  327         td->td_pcb->pcb_esi = (int) func;       /* function */
  328         td->td_pcb->pcb_ebx = (int) arg;        /* first arg */
  329 }
  330 
  331 void
  332 cpu_exit(struct thread *td)
  333 {
  334 
  335         /*
  336          * If this process has a custom LDT, release it.  Reset pc->pcb_gs
  337          * and %gs before we free it in case they refer to an LDT entry.
  338          */
  339         mtx_lock_spin(&dt_lock);
  340         if (td->td_proc->p_md.md_ldt) {
  341                 td->td_pcb->pcb_gs = _udatasel;
  342                 load_gs(_udatasel);
  343                 user_ldt_free(td);
  344         } else
  345                 mtx_unlock_spin(&dt_lock);
  346 }
  347 
  348 void
  349 cpu_thread_exit(struct thread *td)
  350 {
  351 
  352         critical_enter();
  353         if (td == PCPU_GET(fpcurthread))
  354                 npxdrop();
  355         critical_exit();
  356 
  357         /* Disable any hardware breakpoints. */
  358         if (td->td_pcb->pcb_flags & PCB_DBREGS) {
  359                 reset_dbregs();
  360                 td->td_pcb->pcb_flags &= ~PCB_DBREGS;
  361         }
  362 }
  363 
  364 void
  365 cpu_thread_clean(struct thread *td)
  366 {
  367         struct pcb *pcb;
  368 
  369         pcb = td->td_pcb; 
  370         if (pcb->pcb_ext != NULL) {
  371                 /* if (pcb->pcb_ext->ext_refcount-- == 1) ?? */
  372                 /*
  373                  * XXX do we need to move the TSS off the allocated pages
  374                  * before freeing them?  (not done here)
  375                  */
  376                 pmap_trm_free(pcb->pcb_ext, ctob(IOPAGES + 1));
  377                 pcb->pcb_ext = NULL;
  378         }
  379 }
  380 
  381 void
  382 cpu_thread_swapin(struct thread *td)
  383 {
  384 }
  385 
  386 void
  387 cpu_thread_swapout(struct thread *td)
  388 {
  389 }
  390 
  391 void
  392 cpu_thread_alloc(struct thread *td)
  393 {
  394         struct pcb *pcb;
  395         struct xstate_hdr *xhdr;
  396 
  397         td->td_pcb = pcb = get_pcb_td(td);
  398         td->td_frame = (struct trapframe *)((caddr_t)pcb -
  399             VM86_STACK_SPACE) - 1;
  400         pcb->pcb_ext = NULL; 
  401         pcb->pcb_save = get_pcb_user_save_pcb(pcb);
  402         if (use_xsave) {
  403                 xhdr = (struct xstate_hdr *)(pcb->pcb_save + 1);
  404                 bzero(xhdr, sizeof(*xhdr));
  405                 xhdr->xstate_bv = xsave_mask;
  406         }
  407 }
  408 
  409 void
  410 cpu_thread_free(struct thread *td)
  411 {
  412 
  413         cpu_thread_clean(td);
  414 }
  415 
  416 bool
  417 cpu_exec_vmspace_reuse(struct proc *p __unused, vm_map_t map __unused)
  418 {
  419 
  420         return (true);
  421 }
  422 
  423 int
  424 cpu_procctl(struct thread *td __unused, int idtype __unused, id_t id __unused,
  425     int com __unused, void *data __unused)
  426 {
  427 
  428         return (EINVAL);
  429 }
  430 
  431 void
  432 cpu_set_syscall_retval(struct thread *td, int error)
  433 {
  434 
  435         switch (error) {
  436         case 0:
  437                 td->td_frame->tf_eax = td->td_retval[0];
  438                 td->td_frame->tf_edx = td->td_retval[1];
  439                 td->td_frame->tf_eflags &= ~PSL_C;
  440                 break;
  441 
  442         case ERESTART:
  443                 /*
  444                  * Reconstruct pc, assuming lcall $X,y is 7 bytes, int
  445                  * 0x80 is 2 bytes. We saved this in tf_err.
  446                  */
  447                 td->td_frame->tf_eip -= td->td_frame->tf_err;
  448                 break;
  449 
  450         case EJUSTRETURN:
  451                 break;
  452 
  453         default:
  454                 td->td_frame->tf_eax = error;
  455                 td->td_frame->tf_eflags |= PSL_C;
  456                 break;
  457         }
  458 }
  459 
  460 /*
  461  * Initialize machine state, mostly pcb and trap frame for a new
  462  * thread, about to return to userspace.  Put enough state in the new
  463  * thread's PCB to get it to go back to the fork_return(), which
  464  * finalizes the thread state and handles peculiarities of the first
  465  * return to userspace for the new thread.
  466  */
  467 void
  468 cpu_copy_thread(struct thread *td, struct thread *td0)
  469 {
  470         copy_thread(td0, td);
  471 
  472         /*
  473          * Copy user general-purpose registers.
  474          *
  475          * Some of these registers are rewritten by cpu_set_upcall()
  476          * and linux_set_upcall().
  477          */
  478         bcopy(td0->td_frame, td->td_frame, sizeof(struct trapframe));
  479 
  480         /* If the current thread has the trap bit set (i.e. a debugger had
  481          * single stepped the process to the system call), we need to clear
  482          * the trap flag from the new frame. Otherwise, the new thread will
  483          * receive a (likely unexpected) SIGTRAP when it executes the first
  484          * instruction after returning to userland.
  485          */
  486         td->td_frame->tf_eflags &= ~PSL_T;
  487 }
  488 
  489 /*
  490  * Set that machine state for performing an upcall that starts
  491  * the entry function with the given argument.
  492  */
  493 void
  494 cpu_set_upcall(struct thread *td, void (*entry)(void *), void *arg,
  495     stack_t *stack)
  496 {
  497 
  498         /* 
  499          * Do any extra cleaning that needs to be done.
  500          * The thread may have optional components
  501          * that are not present in a fresh thread.
  502          * This may be a recycled thread so make it look
  503          * as though it's newly allocated.
  504          */
  505         cpu_thread_clean(td);
  506 
  507         /*
  508          * Set the trap frame to point at the beginning of the entry
  509          * function.
  510          */
  511         td->td_frame->tf_ebp = 0; 
  512         td->td_frame->tf_esp =
  513             (((int)stack->ss_sp + stack->ss_size - 4) & ~0x0f) - 4;
  514         td->td_frame->tf_eip = (int)entry;
  515 
  516         /* Return address sentinel value to stop stack unwinding. */
  517         suword((void *)td->td_frame->tf_esp, 0);
  518 
  519         /* Pass the argument to the entry point. */
  520         suword((void *)(td->td_frame->tf_esp + sizeof(void *)),
  521             (int)arg);
  522 }
  523 
  524 int
  525 cpu_set_user_tls(struct thread *td, void *tls_base)
  526 {
  527         struct segment_descriptor sd;
  528         uint32_t base;
  529 
  530         /*
  531          * Construct a descriptor and store it in the pcb for
  532          * the next context switch.  Also store it in the gdt
  533          * so that the load of tf_fs into %fs will activate it
  534          * at return to userland.
  535          */
  536         base = (uint32_t)tls_base;
  537         sd.sd_lobase = base & 0xffffff;
  538         sd.sd_hibase = (base >> 24) & 0xff;
  539         sd.sd_lolimit = 0xffff; /* 4GB limit, wraps around */
  540         sd.sd_hilimit = 0xf;
  541         sd.sd_type  = SDT_MEMRWA;
  542         sd.sd_dpl   = SEL_UPL;
  543         sd.sd_p     = 1;
  544         sd.sd_xx    = 0;
  545         sd.sd_def32 = 1;
  546         sd.sd_gran  = 1;
  547         critical_enter();
  548         /* set %gs */
  549         td->td_pcb->pcb_gsd = sd;
  550         if (td == curthread) {
  551                 PCPU_GET(fsgs_gdt)[1] = sd;
  552                 load_gs(GSEL(GUGS_SEL, SEL_UPL));
  553         }
  554         critical_exit();
  555         return (0);
  556 }
  557 
  558 /*
  559  * Convert kernel VA to physical address
  560  */
  561 vm_paddr_t
  562 kvtop(void *addr)
  563 {
  564         vm_paddr_t pa;
  565 
  566         pa = pmap_kextract((vm_offset_t)addr);
  567         if (pa == 0)
  568                 panic("kvtop: zero page frame");
  569         return (pa);
  570 }
  571 
  572 /*
  573  * Get an sf_buf from the freelist.  May block if none are available.
  574  */
  575 void
  576 sf_buf_map(struct sf_buf *sf, int flags)
  577 {
  578 
  579         pmap_sf_buf_map(sf);
  580 #ifdef SMP
  581         sf_buf_shootdown(sf, flags);
  582 #endif
  583 }
  584 
  585 #ifdef SMP
  586 static void
  587 sf_buf_shootdown_curcpu_cb(pmap_t pmap __unused,
  588     vm_offset_t addr1 __unused, vm_offset_t addr2 __unused)
  589 {
  590 }
  591 
  592 void
  593 sf_buf_shootdown(struct sf_buf *sf, int flags)
  594 {
  595         cpuset_t other_cpus;
  596         u_int cpuid;
  597 
  598         sched_pin();
  599         cpuid = PCPU_GET(cpuid);
  600         if (!CPU_ISSET(cpuid, &sf->cpumask)) {
  601                 CPU_SET(cpuid, &sf->cpumask);
  602                 invlpg(sf->kva);
  603         }
  604         if ((flags & SFB_CPUPRIVATE) == 0) {
  605                 other_cpus = all_cpus;
  606                 CPU_CLR(cpuid, &other_cpus);
  607                 CPU_ANDNOT(&other_cpus, &other_cpus, &sf->cpumask);
  608                 if (!CPU_EMPTY(&other_cpus)) {
  609                         CPU_OR(&sf->cpumask, &sf->cpumask, &other_cpus);
  610                         smp_masked_invlpg(other_cpus, sf->kva, kernel_pmap,
  611                             sf_buf_shootdown_curcpu_cb);
  612                 }
  613         }
  614         sched_unpin();
  615 }
  616 #endif
  617 
  618 /*
  619  * MD part of sf_buf_free().
  620  */
  621 int
  622 sf_buf_unmap(struct sf_buf *sf)
  623 {
  624 
  625         return (0);
  626 }
  627 
  628 static void
  629 sf_buf_invalidate(struct sf_buf *sf)
  630 {
  631         vm_page_t m = sf->m;
  632 
  633         /*
  634          * Use pmap_qenter to update the pte for
  635          * existing mapping, in particular, the PAT
  636          * settings are recalculated.
  637          */
  638         pmap_qenter(sf->kva, &m, 1);
  639         pmap_invalidate_cache_range(sf->kva, sf->kva + PAGE_SIZE);
  640 }
  641 
  642 /*
  643  * Invalidate the cache lines that may belong to the page, if
  644  * (possibly old) mapping of the page by sf buffer exists.  Returns
  645  * TRUE when mapping was found and cache invalidated.
  646  */
  647 boolean_t
  648 sf_buf_invalidate_cache(vm_page_t m)
  649 {
  650 
  651         return (sf_buf_process_page(m, sf_buf_invalidate));
  652 }

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