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  * 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/6.0/sys/i386/i386/vm_machdep.c 151490 2005-10-20 01:03:23Z ups $");
   45 
   46 #include "opt_isa.h"
   47 #include "opt_npx.h"
   48 #ifdef PC98
   49 #include "opt_pc98.h"
   50 #endif
   51 #include "opt_reset.h"
   52 #include "opt_cpu.h"
   53 
   54 #include <sys/param.h>
   55 #include <sys/systm.h>
   56 #include <sys/bio.h>
   57 #include <sys/buf.h>
   58 #include <sys/kse.h>
   59 #include <sys/kernel.h>
   60 #include <sys/ktr.h>
   61 #include <sys/lock.h>
   62 #include <sys/malloc.h>
   63 #include <sys/mbuf.h>
   64 #include <sys/mutex.h>
   65 #include <sys/pioctl.h>
   66 #include <sys/proc.h>
   67 #include <sys/sf_buf.h>
   68 #include <sys/smp.h>
   69 #include <sys/sched.h>
   70 #include <sys/sysctl.h>
   71 #include <sys/unistd.h>
   72 #include <sys/vnode.h>
   73 #include <sys/vmmeter.h>
   74 
   75 #include <machine/cpu.h>
   76 #include <machine/cputypes.h>
   77 #include <machine/md_var.h>
   78 #include <machine/pcb.h>
   79 #include <machine/pcb_ext.h>
   80 #include <machine/smp.h>
   81 #include <machine/vm86.h>
   82 
   83 #ifdef CPU_ELAN
   84 #include <machine/elan_mmcr.h>
   85 #endif
   86 
   87 #include <vm/vm.h>
   88 #include <vm/vm_extern.h>
   89 #include <vm/vm_kern.h>
   90 #include <vm/vm_page.h>
   91 #include <vm/vm_map.h>
   92 #include <vm/vm_param.h>
   93 
   94 #ifdef PC98
   95 #include <pc98/cbus/cbus.h>
   96 #else
   97 #include <i386/isa/isa.h>
   98 #endif
   99 
  100 #ifndef NSFBUFS
  101 #define NSFBUFS         (512 + maxusers * 16)
  102 #endif
  103 
  104 static void     cpu_reset_real(void);
  105 #ifdef SMP
  106 static void     cpu_reset_proxy(void);
  107 static u_int    cpu_reset_proxyid;
  108 static volatile u_int   cpu_reset_proxy_active;
  109 #endif
  110 static void     sf_buf_init(void *arg);
  111 SYSINIT(sock_sf, SI_SUB_MBUF, SI_ORDER_ANY, sf_buf_init, NULL)
  112 
  113 LIST_HEAD(sf_head, sf_buf);
  114 
  115 /*
  116  * A hash table of active sendfile(2) buffers
  117  */
  118 static struct sf_head *sf_buf_active;
  119 static u_long sf_buf_hashmask;
  120 
  121 #define SF_BUF_HASH(m)  (((m) - vm_page_array) & sf_buf_hashmask)
  122 
  123 static TAILQ_HEAD(, sf_buf) sf_buf_freelist;
  124 static u_int    sf_buf_alloc_want;
  125 
  126 /*
  127  * A lock used to synchronize access to the hash table and free list
  128  */
  129 static struct mtx sf_buf_lock;
  130 
  131 extern int      _ucodesel, _udatasel;
  132 
  133 /*
  134  * Finish a fork operation, with process p2 nearly set up.
  135  * Copy and update the pcb, set up the stack so that the child
  136  * ready to run and return to user mode.
  137  */
  138 void
  139 cpu_fork(td1, p2, td2, flags)
  140         register struct thread *td1;
  141         register struct proc *p2;
  142         struct thread *td2;
  143         int flags;
  144 {
  145         register struct proc *p1;
  146         struct pcb *pcb2;
  147         struct mdproc *mdp2;
  148 #ifdef DEV_NPX
  149         register_t savecrit;
  150 #endif
  151 
  152         p1 = td1->td_proc;
  153         if ((flags & RFPROC) == 0) {
  154                 if ((flags & RFMEM) == 0) {
  155                         /* unshare user LDT */
  156                         struct mdproc *mdp1 = &p1->p_md;
  157                         struct proc_ldt *pldt;
  158 
  159                         pldt = mdp1->md_ldt;
  160                         if (pldt && pldt->ldt_refcnt > 1) {
  161                                 pldt = user_ldt_alloc(mdp1, pldt->ldt_len);
  162                                 if (pldt == NULL)
  163                                         panic("could not copy LDT");
  164                                 mdp1->md_ldt = pldt;
  165                                 set_user_ldt(mdp1);
  166                                 user_ldt_free(td1);
  167                         }
  168                 }
  169                 return;
  170         }
  171 
  172         /* Ensure that p1's pcb is up to date. */
  173 #ifdef DEV_NPX
  174         if (td1 == curthread)
  175                 td1->td_pcb->pcb_gs = rgs();
  176         savecrit = intr_disable();
  177         if (PCPU_GET(fpcurthread) == td1)
  178                 npxsave(&td1->td_pcb->pcb_save);
  179         intr_restore(savecrit);
  180 #endif
  181 
  182         /* Point the pcb to the top of the stack */
  183         pcb2 = (struct pcb *)(td2->td_kstack +
  184             td2->td_kstack_pages * PAGE_SIZE) - 1;
  185         td2->td_pcb = pcb2;
  186 
  187         /* Copy p1's pcb */
  188         bcopy(td1->td_pcb, pcb2, sizeof(*pcb2));
  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 -16 is so we can expand the trapframe if we go to vm86.
  199          */
  200         td2->td_frame = (struct trapframe *)((caddr_t)td2->td_pcb - 16) - 1;
  201         bcopy(td1->td_frame, td2->td_frame, sizeof(struct trapframe));
  202 
  203         td2->td_frame->tf_eax = 0;              /* Child returns zero */
  204         td2->td_frame->tf_eflags &= ~PSL_C;     /* success */
  205         td2->td_frame->tf_edx = 1;
  206 
  207         /*
  208          * If the parent process has the trap bit set (i.e. a debugger had
  209          * single stepped the process to the system call), we need to clear
  210          * the trap flag from the new frame unless the debugger had set PF_FORK
  211          * on the parent.  Otherwise, the child will receive a (likely
  212          * unexpected) SIGTRAP when it executes the first instruction after
  213          * returning  to userland.
  214          */
  215         if ((p1->p_pfsflags & PF_FORK) == 0)
  216                 td2->td_frame->tf_eflags &= ~PSL_T;
  217 
  218         /*
  219          * Set registers for trampoline to user mode.  Leave space for the
  220          * return address on stack.  These are the kernel mode register values.
  221          */
  222 #ifdef PAE
  223         pcb2->pcb_cr3 = vtophys(vmspace_pmap(p2->p_vmspace)->pm_pdpt);
  224 #else
  225         pcb2->pcb_cr3 = vtophys(vmspace_pmap(p2->p_vmspace)->pm_pdir);
  226 #endif
  227         pcb2->pcb_edi = 0;
  228         pcb2->pcb_esi = (int)fork_return;       /* fork_trampoline argument */
  229         pcb2->pcb_ebp = 0;
  230         pcb2->pcb_esp = (int)td2->td_frame - sizeof(void *);
  231         pcb2->pcb_ebx = (int)td2;               /* fork_trampoline argument */
  232         pcb2->pcb_eip = (int)fork_trampoline;
  233         pcb2->pcb_psl = PSL_KERNEL;             /* ints disabled */
  234         pcb2->pcb_gs = rgs();
  235         /*-
  236          * pcb2->pcb_dr*:       cloned above.
  237          * pcb2->pcb_savefpu:   cloned above.
  238          * pcb2->pcb_flags:     cloned above.
  239          * pcb2->pcb_onfault:   cloned above (always NULL here?).
  240          * pcb2->pcb_gs:        cloned above.
  241          * pcb2->pcb_ext:       cleared below.
  242          */
  243 
  244         /*
  245          * XXX don't copy the i/o pages.  this should probably be fixed.
  246          */
  247         pcb2->pcb_ext = 0;
  248 
  249         /* Copy the LDT, if necessary. */
  250         mtx_lock_spin(&sched_lock);
  251         if (mdp2->md_ldt != NULL) {
  252                 if (flags & RFMEM) {
  253                         mdp2->md_ldt->ldt_refcnt++;
  254                 } else {
  255                         mdp2->md_ldt = user_ldt_alloc(mdp2,
  256                             mdp2->md_ldt->ldt_len);
  257                         if (mdp2->md_ldt == NULL)
  258                                 panic("could not copy LDT");
  259                 }
  260         }
  261         mtx_unlock_spin(&sched_lock);
  262 
  263         /* Setup to release sched_lock in fork_exit(). */
  264         td2->td_md.md_spinlock_count = 1;
  265         td2->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
  266 
  267         /*
  268          * Now, cpu_switch() can schedule the new process.
  269          * pcb_esp is loaded pointing to the cpu_switch() stack frame
  270          * containing the return address when exiting cpu_switch.
  271          * This will normally be to fork_trampoline(), which will have
  272          * %ebx loaded with the new proc's pointer.  fork_trampoline()
  273          * will set up a stack to call fork_return(p, frame); to complete
  274          * the return to user-mode.
  275          */
  276 }
  277 
  278 /*
  279  * Intercept the return address from a freshly forked process that has NOT
  280  * been scheduled yet.
  281  *
  282  * This is needed to make kernel threads stay in kernel mode.
  283  */
  284 void
  285 cpu_set_fork_handler(td, func, arg)
  286         struct thread *td;
  287         void (*func)(void *);
  288         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_esi = (int) func;       /* function */
  295         td->td_pcb->pcb_ebx = (int) 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.  Reset pc->pcb_gs
  304          * and %gs before we free it in case they refer to an LDT entry.
  305          */
  306         if (td->td_proc->p_md.md_ldt) {
  307                 td->td_pcb->pcb_gs = _udatasel;
  308                 load_gs(_udatasel);
  309                 user_ldt_free(td);
  310         }
  311 }
  312 
  313 void
  314 cpu_thread_exit(struct thread *td)
  315 {
  316 
  317 #ifdef DEV_NPX
  318         if (td == PCPU_GET(fpcurthread))
  319                 npxdrop();
  320 #endif
  321 
  322         /* Disable any hardware breakpoints. */
  323         if (td->td_pcb->pcb_flags & PCB_DBREGS) {
  324                 reset_dbregs();
  325                 td->td_pcb->pcb_flags &= ~PCB_DBREGS;
  326         }
  327 }
  328 
  329 void
  330 cpu_thread_clean(struct thread *td)
  331 {
  332         struct pcb *pcb;
  333 
  334         pcb = td->td_pcb; 
  335         if (pcb->pcb_ext != NULL) {
  336                 /* XXXKSE  XXXSMP  not SMP SAFE.. what locks do we have? */
  337                 /* if (pcb->pcb_ext->ext_refcount-- == 1) ?? */
  338                 /*
  339                  * XXX do we need to move the TSS off the allocated pages
  340                  * before freeing them?  (not done here)
  341                  */
  342                 kmem_free(kernel_map, (vm_offset_t)pcb->pcb_ext,
  343                     ctob(IOPAGES + 1));
  344                 pcb->pcb_ext = 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_setup(struct thread *td)
  360 {
  361 
  362         td->td_pcb = (struct pcb *)(td->td_kstack +
  363             td->td_kstack_pages * PAGE_SIZE) - 1;
  364         td->td_frame = (struct trapframe *)((caddr_t)td->td_pcb - 16) - 1;
  365         td->td_pcb->pcb_ext = NULL; 
  366 }
  367 
  368 /*
  369  * Initialize machine state (pcb and trap frame) for a new thread about to
  370  * upcall. Put enough state in the new thread's PCB to get it to go back 
  371  * userret(), where we can intercept it again to set the return (upcall)
  372  * Address and stack, along with those from upcals that are from other sources
  373  * such as those generated in thread_userret() itself.
  374  */
  375 void
  376 cpu_set_upcall(struct thread *td, struct thread *td0)
  377 {
  378         struct pcb *pcb2;
  379 
  380         /* Point the pcb to the top of the stack. */
  381         pcb2 = td->td_pcb;
  382 
  383         /*
  384          * Copy the upcall pcb.  This loads kernel regs.
  385          * Those not loaded individually below get their default
  386          * values here.
  387          *
  388          * XXXKSE It might be a good idea to simply skip this as
  389          * the values of the other registers may be unimportant.
  390          * This would remove any requirement for knowing the KSE
  391          * at this time (see the matching comment below for
  392          * more analysis) (need a good safe default).
  393          */
  394         bcopy(td0->td_pcb, pcb2, sizeof(*pcb2));
  395         pcb2->pcb_flags &= ~(PCB_NPXTRAP|PCB_NPXINITDONE);
  396 
  397         /*
  398          * Create a new fresh stack for the new thread.
  399          * The -16 is so we can expand the trapframe if we go to vm86.
  400          * Don't forget to set this stack value into whatever supplies
  401          * the address for the fault handlers.
  402          * The contexts are filled in at the time we actually DO the
  403          * upcall as only then do we know which KSE we got.
  404          */
  405         bcopy(td0->td_frame, td->td_frame, sizeof(struct trapframe));
  406 
  407         /*
  408          * Set registers for trampoline to user mode.  Leave space for the
  409          * return address on stack.  These are the kernel mode register values.
  410          */
  411 #ifdef PAE
  412         pcb2->pcb_cr3 = vtophys(vmspace_pmap(td->td_proc->p_vmspace)->pm_pdpt);
  413 #else
  414         pcb2->pcb_cr3 = vtophys(vmspace_pmap(td->td_proc->p_vmspace)->pm_pdir);
  415 #endif
  416         pcb2->pcb_edi = 0;
  417         pcb2->pcb_esi = (int)fork_return;                   /* trampoline arg */
  418         pcb2->pcb_ebp = 0;
  419         pcb2->pcb_esp = (int)td->td_frame - sizeof(void *); /* trampoline arg */
  420         pcb2->pcb_ebx = (int)td;                            /* trampoline arg */
  421         pcb2->pcb_eip = (int)fork_trampoline;
  422         pcb2->pcb_psl &= ~(PSL_I);      /* interrupts must be disabled */
  423         pcb2->pcb_gs = rgs();
  424         /*
  425          * If we didn't copy the pcb, we'd need to do the following registers:
  426          * pcb2->pcb_dr*:       cloned above.
  427          * pcb2->pcb_savefpu:   cloned above.
  428          * pcb2->pcb_flags:     cloned above.
  429          * pcb2->pcb_onfault:   cloned above (always NULL here?).
  430          * pcb2->pcb_gs:        cloned above.  XXXKSE ???
  431          * pcb2->pcb_ext:       cleared below.
  432          */
  433         pcb2->pcb_ext = NULL;
  434 
  435         /* Setup to release sched_lock in fork_exit(). */
  436         td->td_md.md_spinlock_count = 1;
  437         td->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
  438 }
  439 
  440 /*
  441  * Set that machine state for performing an upcall that has to
  442  * be done in thread_userret() so that those upcalls generated
  443  * in thread_userret() itself can be done as well.
  444  */
  445 void
  446 cpu_set_upcall_kse(struct thread *td, void (*entry)(void *), void *arg,
  447         stack_t *stack)
  448 {
  449 
  450         /* 
  451          * Do any extra cleaning that needs to be done.
  452          * The thread may have optional components
  453          * that are not present in a fresh thread.
  454          * This may be a recycled thread so make it look
  455          * as though it's newly allocated.
  456          */
  457         cpu_thread_clean(td);
  458 
  459         /*
  460          * Set the trap frame to point at the beginning of the uts
  461          * function.
  462          */
  463         td->td_frame->tf_ebp = 0; 
  464         td->td_frame->tf_esp =
  465             (int)stack->ss_sp + stack->ss_size - 16;
  466         td->td_frame->tf_eip = (int)entry;
  467 
  468         /*
  469          * Pass the address of the mailbox for this kse to the uts
  470          * function as a parameter on the stack.
  471          */
  472         suword((void *)(td->td_frame->tf_esp + sizeof(void *)),
  473             (int)arg);
  474 }
  475 
  476 int
  477 cpu_set_user_tls(struct thread *td, void *tls_base)
  478 {
  479         struct segment_descriptor sd;
  480         uint32_t base;
  481 
  482         /*
  483          * Construct a descriptor and store it in the pcb for
  484          * the next context switch.  Also store it in the gdt
  485          * so that the load of tf_fs into %fs will activate it
  486          * at return to userland.
  487          */
  488         base = (uint32_t)tls_base;
  489         sd.sd_lobase = base & 0xffffff;
  490         sd.sd_hibase = (base >> 24) & 0xff;
  491         sd.sd_lolimit = 0xffff; /* 4GB limit, wraps around */
  492         sd.sd_hilimit = 0xf;
  493         sd.sd_type  = SDT_MEMRWA;
  494         sd.sd_dpl   = SEL_UPL;
  495         sd.sd_p     = 1;
  496         sd.sd_xx    = 0;
  497         sd.sd_def32 = 1;
  498         sd.sd_gran  = 1;
  499         critical_enter();
  500         /* set %gs */
  501         td->td_pcb->pcb_gsd = sd;
  502         if (td == curthread) {
  503                 PCPU_GET(fsgs_gdt)[1] = sd;
  504                 load_gs(GSEL(GUGS_SEL, SEL_UPL));
  505         }
  506         critical_exit();
  507         return (0);
  508 }
  509 
  510 /*
  511  * Convert kernel VA to physical address
  512  */
  513 vm_paddr_t
  514 kvtop(void *addr)
  515 {
  516         vm_paddr_t pa;
  517 
  518         pa = pmap_kextract((vm_offset_t)addr);
  519         if (pa == 0)
  520                 panic("kvtop: zero page frame");
  521         return (pa);
  522 }
  523 
  524 #ifdef SMP
  525 static void
  526 cpu_reset_proxy()
  527 {
  528 
  529         cpu_reset_proxy_active = 1;
  530         while (cpu_reset_proxy_active == 1)
  531                 ;       /* Wait for other cpu to see that we've started */
  532         stop_cpus((1<<cpu_reset_proxyid));
  533         printf("cpu_reset_proxy: Stopped CPU %d\n", cpu_reset_proxyid);
  534         DELAY(1000000);
  535         cpu_reset_real();
  536 }
  537 #endif
  538 
  539 void
  540 cpu_reset()
  541 {
  542 #ifdef SMP
  543         u_int cnt, map;
  544 
  545         if (smp_active) {
  546                 map = PCPU_GET(other_cpus) & ~stopped_cpus;
  547                 if (map != 0) {
  548                         printf("cpu_reset: Stopping other CPUs\n");
  549                         stop_cpus(map);
  550                 }
  551 
  552                 if (PCPU_GET(cpuid) != 0) {
  553                         cpu_reset_proxyid = PCPU_GET(cpuid);
  554                         cpustop_restartfunc = cpu_reset_proxy;
  555                         cpu_reset_proxy_active = 0;
  556                         printf("cpu_reset: Restarting BSP\n");
  557                         started_cpus = (1<<0);          /* Restart CPU #0 */
  558 
  559                         cnt = 0;
  560                         while (cpu_reset_proxy_active == 0 && cnt < 10000000)
  561                                 cnt++;  /* Wait for BSP to announce restart */
  562                         if (cpu_reset_proxy_active == 0)
  563                                 printf("cpu_reset: Failed to restart BSP\n");
  564                         enable_intr();
  565                         cpu_reset_proxy_active = 2;
  566 
  567                         while (1);
  568                         /* NOTREACHED */
  569                 }
  570 
  571                 DELAY(1000000);
  572         }
  573 #endif
  574         cpu_reset_real();
  575         /* NOTREACHED */
  576 }
  577 
  578 static void
  579 cpu_reset_real()
  580 {
  581 
  582 #ifdef CPU_ELAN
  583         if (elan_mmcr != NULL)
  584                 elan_mmcr->RESCFG = 1;
  585 #endif
  586 
  587         if (cpu == CPU_GEODE1100) {
  588                 /* Attempt Geode's own reset */
  589                 outl(0xcf8, 0x80009044ul);
  590                 outl(0xcfc, 0xf);
  591         }
  592 
  593 #ifdef PC98
  594         /*
  595          * Attempt to do a CPU reset via CPU reset port.
  596          */
  597         disable_intr();
  598         if ((inb(0x35) & 0xa0) != 0xa0) {
  599                 outb(0x37, 0x0f);               /* SHUT0 = 0. */
  600                 outb(0x37, 0x0b);               /* SHUT1 = 0. */
  601         }
  602         outb(0xf0, 0x00);               /* Reset. */
  603 #else
  604 #if !defined(BROKEN_KEYBOARD_RESET)
  605         /*
  606          * Attempt to do a CPU reset via the keyboard controller,
  607          * do not turn off GateA20, as any machine that fails
  608          * to do the reset here would then end up in no man's land.
  609          */
  610         outb(IO_KBD + 4, 0xFE);
  611         DELAY(500000);  /* wait 0.5 sec to see if that did it */
  612         printf("Keyboard reset did not work, attempting CPU shutdown\n");
  613         DELAY(1000000); /* wait 1 sec for printf to complete */
  614 #endif
  615 #endif /* PC98 */
  616 
  617         /* Force a shutdown by unmapping entire address space. */
  618         bzero((caddr_t)PTD, NBPTD);
  619 
  620         /* "good night, sweet prince .... <THUNK!>" */
  621         invltlb();
  622         /* NOTREACHED */
  623         while(1);
  624 }
  625 
  626 /*
  627  * Allocate a pool of sf_bufs (sendfile(2) or "super-fast" if you prefer. :-))
  628  */
  629 static void
  630 sf_buf_init(void *arg)
  631 {
  632         struct sf_buf *sf_bufs;
  633         vm_offset_t sf_base;
  634         int i;
  635 
  636         nsfbufs = NSFBUFS;
  637         TUNABLE_INT_FETCH("kern.ipc.nsfbufs", &nsfbufs);
  638 
  639         sf_buf_active = hashinit(nsfbufs, M_TEMP, &sf_buf_hashmask);
  640         TAILQ_INIT(&sf_buf_freelist);
  641         sf_base = kmem_alloc_nofault(kernel_map, nsfbufs * PAGE_SIZE);
  642         sf_bufs = malloc(nsfbufs * sizeof(struct sf_buf), M_TEMP,
  643             M_NOWAIT | M_ZERO);
  644         for (i = 0; i < nsfbufs; i++) {
  645                 sf_bufs[i].kva = sf_base + i * PAGE_SIZE;
  646                 TAILQ_INSERT_TAIL(&sf_buf_freelist, &sf_bufs[i], free_entry);
  647         }
  648         sf_buf_alloc_want = 0;
  649         mtx_init(&sf_buf_lock, "sf_buf", NULL, MTX_DEF);
  650 }
  651 
  652 /*
  653  * Get an sf_buf from the freelist. Will block if none are available.
  654  */
  655 struct sf_buf *
  656 sf_buf_alloc(struct vm_page *m, int flags)
  657 {
  658         pt_entry_t opte, *ptep;
  659         struct sf_head *hash_list;
  660         struct sf_buf *sf;
  661 #ifdef SMP
  662         cpumask_t cpumask, other_cpus;
  663 #endif
  664         int error;
  665 
  666         KASSERT(curthread->td_pinned > 0 || (flags & SFB_CPUPRIVATE) == 0,
  667             ("sf_buf_alloc(SFB_CPUPRIVATE): curthread not pinned"));
  668         hash_list = &sf_buf_active[SF_BUF_HASH(m)];
  669         mtx_lock(&sf_buf_lock);
  670         LIST_FOREACH(sf, hash_list, list_entry) {
  671                 if (sf->m == m) {
  672                         sf->ref_count++;
  673                         if (sf->ref_count == 1) {
  674                                 TAILQ_REMOVE(&sf_buf_freelist, sf, free_entry);
  675                                 nsfbufsused++;
  676                                 nsfbufspeak = imax(nsfbufspeak, nsfbufsused);
  677                         }
  678 #ifdef SMP
  679                         goto shootdown; 
  680 #else
  681                         goto done;
  682 #endif
  683                 }
  684         }
  685         while ((sf = TAILQ_FIRST(&sf_buf_freelist)) == NULL) {
  686                 if (flags & SFB_NOWAIT)
  687                         goto done;
  688                 sf_buf_alloc_want++;
  689                 mbstat.sf_allocwait++;
  690                 error = msleep(&sf_buf_freelist, &sf_buf_lock,
  691                     (flags & SFB_CATCH) ? PCATCH | PVM : PVM, "sfbufa", 0);
  692                 sf_buf_alloc_want--;
  693 
  694                 /*
  695                  * If we got a signal, don't risk going back to sleep. 
  696                  */
  697                 if (error)
  698                         goto done;
  699         }
  700         TAILQ_REMOVE(&sf_buf_freelist, sf, free_entry);
  701         if (sf->m != NULL)
  702                 LIST_REMOVE(sf, list_entry);
  703         LIST_INSERT_HEAD(hash_list, sf, list_entry);
  704         sf->ref_count = 1;
  705         sf->m = m;
  706         nsfbufsused++;
  707         nsfbufspeak = imax(nsfbufspeak, nsfbufsused);
  708 
  709         /*
  710          * Update the sf_buf's virtual-to-physical mapping, flushing the
  711          * virtual address from the TLB.  Since the reference count for 
  712          * the sf_buf's old mapping was zero, that mapping is not 
  713          * currently in use.  Consequently, there is no need to exchange 
  714          * the old and new PTEs atomically, even under PAE.
  715          */
  716         ptep = vtopte(sf->kva);
  717         opte = *ptep;
  718         *ptep = VM_PAGE_TO_PHYS(m) | pgeflag | PG_RW | PG_V;
  719 
  720         /*
  721          * Avoid unnecessary TLB invalidations: If the sf_buf's old
  722          * virtual-to-physical mapping was not used, then any processor
  723          * that has invalidated the sf_buf's virtual address from its TLB
  724          * since the last used mapping need not invalidate again.
  725          */
  726 #ifdef SMP
  727         if ((opte & (PG_V | PG_A)) ==  (PG_V | PG_A))
  728                 sf->cpumask = 0;
  729 shootdown:
  730         sched_pin();
  731         cpumask = PCPU_GET(cpumask);
  732         if ((sf->cpumask & cpumask) == 0) {
  733                 sf->cpumask |= cpumask;
  734                 invlpg(sf->kva);
  735         }
  736         if ((flags & SFB_CPUPRIVATE) == 0) {
  737                 other_cpus = PCPU_GET(other_cpus) & ~sf->cpumask;
  738                 if (other_cpus != 0) {
  739                         sf->cpumask |= other_cpus;
  740                         mtx_lock_spin(&smp_ipi_mtx);
  741                         smp_masked_invlpg(other_cpus, sf->kva);
  742                         mtx_unlock_spin(&smp_ipi_mtx);
  743                 }
  744         }
  745         sched_unpin();  
  746 #else
  747         if ((opte & (PG_V | PG_A)) ==  (PG_V | PG_A))
  748                 pmap_invalidate_page(kernel_pmap, sf->kva);
  749 #endif
  750 done:
  751         mtx_unlock(&sf_buf_lock);
  752         return (sf);
  753 }
  754 
  755 /*
  756  * Remove a reference from the given sf_buf, adding it to the free
  757  * list when its reference count reaches zero.  A freed sf_buf still,
  758  * however, retains its virtual-to-physical mapping until it is
  759  * recycled or reactivated by sf_buf_alloc(9).
  760  */
  761 void
  762 sf_buf_free(struct sf_buf *sf)
  763 {
  764 
  765         mtx_lock(&sf_buf_lock);
  766         sf->ref_count--;
  767         if (sf->ref_count == 0) {
  768                 TAILQ_INSERT_TAIL(&sf_buf_freelist, sf, free_entry);
  769                 nsfbufsused--;
  770                 if (sf_buf_alloc_want > 0)
  771                         wakeup_one(&sf_buf_freelist);
  772         }
  773         mtx_unlock(&sf_buf_lock);
  774 }
  775 
  776 /*
  777  * Software interrupt handler for queued VM system processing.
  778  */   
  779 void  
  780 swi_vm(void *dummy) 
  781 {     
  782         if (busdma_swi_pending != 0)
  783                 busdma_swi();
  784 }
  785 
  786 /*
  787  * Tell whether this address is in some physical memory region.
  788  * Currently used by the kernel coredump code in order to avoid
  789  * dumping the ``ISA memory hole'' which could cause indefinite hangs,
  790  * or other unpredictable behaviour.
  791  */
  792 
  793 int
  794 is_physical_memory(vm_paddr_t addr)
  795 {
  796 
  797 #ifdef DEV_ISA
  798         /* The ISA ``memory hole''. */
  799         if (addr >= 0xa0000 && addr < 0x100000)
  800                 return 0;
  801 #endif
  802 
  803         /*
  804          * stuff other tests for known memory-mapped devices (PCI?)
  805          * here
  806          */
  807 
  808         return 1;
  809 }

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