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/6.1/sys/i386/i386/vm_machdep.c 158179 2006-04-30 16:44:43Z cvs2svn $");
   45 
   46 #include "opt_isa.h"
   47 #include "opt_npx.h"
   48 #include "opt_reset.h"
   49 #include "opt_cpu.h"
   50 
   51 #include <sys/param.h>
   52 #include <sys/systm.h>
   53 #include <sys/bio.h>
   54 #include <sys/buf.h>
   55 #include <sys/kse.h>
   56 #include <sys/kernel.h>
   57 #include <sys/ktr.h>
   58 #include <sys/lock.h>
   59 #include <sys/malloc.h>
   60 #include <sys/mbuf.h>
   61 #include <sys/mutex.h>
   62 #include <sys/pioctl.h>
   63 #include <sys/proc.h>
   64 #include <sys/sf_buf.h>
   65 #include <sys/smp.h>
   66 #include <sys/sched.h>
   67 #include <sys/sysctl.h>
   68 #include <sys/unistd.h>
   69 #include <sys/vnode.h>
   70 #include <sys/vmmeter.h>
   71 
   72 #include <machine/cpu.h>
   73 #include <machine/cputypes.h>
   74 #include <machine/md_var.h>
   75 #include <machine/pcb.h>
   76 #include <machine/pcb_ext.h>
   77 #include <machine/smp.h>
   78 #include <machine/vm86.h>
   79 
   80 #ifdef CPU_ELAN
   81 #include <machine/elan_mmcr.h>
   82 #endif
   83 
   84 #include <vm/vm.h>
   85 #include <vm/vm_extern.h>
   86 #include <vm/vm_kern.h>
   87 #include <vm/vm_page.h>
   88 #include <vm/vm_map.h>
   89 #include <vm/vm_param.h>
   90 
   91 #ifdef PC98
   92 #include <pc98/cbus/cbus.h>
   93 #else
   94 #include <i386/isa/isa.h>
   95 #endif
   96 
   97 #ifndef NSFBUFS
   98 #define NSFBUFS         (512 + maxusers * 16)
   99 #endif
  100 
  101 static void     cpu_reset_real(void);
  102 #ifdef SMP
  103 static void     cpu_reset_proxy(void);
  104 static u_int    cpu_reset_proxyid;
  105 static volatile u_int   cpu_reset_proxy_active;
  106 #endif
  107 static void     sf_buf_init(void *arg);
  108 SYSINIT(sock_sf, SI_SUB_MBUF, SI_ORDER_ANY, sf_buf_init, NULL)
  109 
  110 LIST_HEAD(sf_head, sf_buf);
  111 
  112 /*
  113  * A hash table of active sendfile(2) buffers
  114  */
  115 static struct sf_head *sf_buf_active;
  116 static u_long sf_buf_hashmask;
  117 
  118 #define SF_BUF_HASH(m)  (((m) - vm_page_array) & sf_buf_hashmask)
  119 
  120 static TAILQ_HEAD(, sf_buf) sf_buf_freelist;
  121 static u_int    sf_buf_alloc_want;
  122 
  123 /*
  124  * A lock used to synchronize access to the hash table and free list
  125  */
  126 static struct mtx sf_buf_lock;
  127 
  128 extern int      _ucodesel, _udatasel;
  129 
  130 /*
  131  * Finish a fork operation, with process p2 nearly set up.
  132  * Copy and update the pcb, set up the stack so that the child
  133  * ready to run and return to user mode.
  134  */
  135 void
  136 cpu_fork(td1, p2, td2, flags)
  137         register struct thread *td1;
  138         register struct proc *p2;
  139         struct thread *td2;
  140         int flags;
  141 {
  142         register struct proc *p1;
  143         struct pcb *pcb2;
  144         struct mdproc *mdp2;
  145 #ifdef DEV_NPX
  146         register_t savecrit;
  147 #endif
  148 
  149         p1 = td1->td_proc;
  150         if ((flags & RFPROC) == 0) {
  151                 if ((flags & RFMEM) == 0) {
  152                         /* unshare user LDT */
  153                         struct mdproc *mdp1 = &p1->p_md;
  154                         struct proc_ldt *pldt;
  155 
  156                         pldt = mdp1->md_ldt;
  157                         if (pldt && pldt->ldt_refcnt > 1) {
  158                                 pldt = user_ldt_alloc(mdp1, pldt->ldt_len);
  159                                 if (pldt == NULL)
  160                                         panic("could not copy LDT");
  161                                 mdp1->md_ldt = pldt;
  162                                 set_user_ldt(mdp1);
  163                                 user_ldt_free(td1);
  164                         }
  165                 }
  166                 return;
  167         }
  168 
  169         /* Ensure that p1's pcb is up to date. */
  170 #ifdef DEV_NPX
  171         if (td1 == curthread)
  172                 td1->td_pcb->pcb_gs = rgs();
  173         savecrit = intr_disable();
  174         if (PCPU_GET(fpcurthread) == td1)
  175                 npxsave(&td1->td_pcb->pcb_save);
  176         intr_restore(savecrit);
  177 #endif
  178 
  179         /* Point the pcb to the top of the stack */
  180         pcb2 = (struct pcb *)(td2->td_kstack +
  181             td2->td_kstack_pages * PAGE_SIZE) - 1;
  182         td2->td_pcb = pcb2;
  183 
  184         /* Copy p1's pcb */
  185         bcopy(td1->td_pcb, pcb2, sizeof(*pcb2));
  186 
  187         /* Point mdproc and then copy over td1's contents */
  188         mdp2 = &p2->p_md;
  189         bcopy(&p1->p_md, mdp2, sizeof(*mdp2));
  190 
  191         /*
  192          * Create a new fresh stack for the new process.
  193          * Copy the trap frame for the return to user mode as if from a
  194          * syscall.  This copies most of the user mode register values.
  195          * The -16 is so we can expand the trapframe if we go to vm86.
  196          */
  197         td2->td_frame = (struct trapframe *)((caddr_t)td2->td_pcb - 16) - 1;
  198         bcopy(td1->td_frame, td2->td_frame, sizeof(struct trapframe));
  199 
  200         td2->td_frame->tf_eax = 0;              /* Child returns zero */
  201         td2->td_frame->tf_eflags &= ~PSL_C;     /* success */
  202         td2->td_frame->tf_edx = 1;
  203 
  204         /*
  205          * If the parent process has the trap bit set (i.e. a debugger had
  206          * single stepped the process to the system call), we need to clear
  207          * the trap flag from the new frame unless the debugger had set PF_FORK
  208          * on the parent.  Otherwise, the child will receive a (likely
  209          * unexpected) SIGTRAP when it executes the first instruction after
  210          * returning  to userland.
  211          */
  212         if ((p1->p_pfsflags & PF_FORK) == 0)
  213                 td2->td_frame->tf_eflags &= ~PSL_T;
  214 
  215         /*
  216          * Set registers for trampoline to user mode.  Leave space for the
  217          * return address on stack.  These are the kernel mode register values.
  218          */
  219 #ifdef PAE
  220         pcb2->pcb_cr3 = vtophys(vmspace_pmap(p2->p_vmspace)->pm_pdpt);
  221 #else
  222         pcb2->pcb_cr3 = vtophys(vmspace_pmap(p2->p_vmspace)->pm_pdir);
  223 #endif
  224         pcb2->pcb_edi = 0;
  225         pcb2->pcb_esi = (int)fork_return;       /* fork_trampoline argument */
  226         pcb2->pcb_ebp = 0;
  227         pcb2->pcb_esp = (int)td2->td_frame - sizeof(void *);
  228         pcb2->pcb_ebx = (int)td2;               /* fork_trampoline argument */
  229         pcb2->pcb_eip = (int)fork_trampoline;
  230         pcb2->pcb_psl = PSL_KERNEL;             /* ints disabled */
  231         pcb2->pcb_gs = rgs();
  232         /*-
  233          * pcb2->pcb_dr*:       cloned above.
  234          * pcb2->pcb_savefpu:   cloned above.
  235          * pcb2->pcb_flags:     cloned above.
  236          * pcb2->pcb_onfault:   cloned above (always NULL here?).
  237          * pcb2->pcb_gs:        cloned above.
  238          * pcb2->pcb_ext:       cleared below.
  239          */
  240 
  241         /*
  242          * XXX don't copy the i/o pages.  this should probably be fixed.
  243          */
  244         pcb2->pcb_ext = 0;
  245 
  246         /* Copy the LDT, if necessary. */
  247         mtx_lock_spin(&sched_lock);
  248         if (mdp2->md_ldt != NULL) {
  249                 if (flags & RFMEM) {
  250                         mdp2->md_ldt->ldt_refcnt++;
  251                 } else {
  252                         mdp2->md_ldt = user_ldt_alloc(mdp2,
  253                             mdp2->md_ldt->ldt_len);
  254                         if (mdp2->md_ldt == NULL)
  255                                 panic("could not copy LDT");
  256                 }
  257         }
  258         mtx_unlock_spin(&sched_lock);
  259 
  260         /* Setup to release sched_lock in fork_exit(). */
  261         td2->td_md.md_spinlock_count = 1;
  262         td2->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
  263 
  264         /*
  265          * Now, cpu_switch() can schedule the new process.
  266          * pcb_esp is loaded pointing to the cpu_switch() stack frame
  267          * containing the return address when exiting cpu_switch.
  268          * This will normally be to fork_trampoline(), which will have
  269          * %ebx loaded with the new proc's pointer.  fork_trampoline()
  270          * will set up a stack to call fork_return(p, frame); to complete
  271          * the return to user-mode.
  272          */
  273 }
  274 
  275 /*
  276  * Intercept the return address from a freshly forked process that has NOT
  277  * been scheduled yet.
  278  *
  279  * This is needed to make kernel threads stay in kernel mode.
  280  */
  281 void
  282 cpu_set_fork_handler(td, func, arg)
  283         struct thread *td;
  284         void (*func)(void *);
  285         void *arg;
  286 {
  287         /*
  288          * Note that the trap frame follows the args, so the function
  289          * is really called like this:  func(arg, frame);
  290          */
  291         td->td_pcb->pcb_esi = (int) func;       /* function */
  292         td->td_pcb->pcb_ebx = (int) arg;        /* first arg */
  293 }
  294 
  295 void
  296 cpu_exit(struct thread *td)
  297 {
  298 
  299         /*
  300          * If this process has a custom LDT, release it.  Reset pc->pcb_gs
  301          * and %gs before we free it in case they refer to an LDT entry.
  302          */
  303         if (td->td_proc->p_md.md_ldt) {
  304                 td->td_pcb->pcb_gs = _udatasel;
  305                 load_gs(_udatasel);
  306                 user_ldt_free(td);
  307         }
  308 }
  309 
  310 void
  311 cpu_thread_exit(struct thread *td)
  312 {
  313 
  314 #ifdef DEV_NPX
  315         if (td == PCPU_GET(fpcurthread))
  316                 npxdrop();
  317 #endif
  318 
  319         /* Disable any hardware breakpoints. */
  320         if (td->td_pcb->pcb_flags & PCB_DBREGS) {
  321                 reset_dbregs();
  322                 td->td_pcb->pcb_flags &= ~PCB_DBREGS;
  323         }
  324 }
  325 
  326 void
  327 cpu_thread_clean(struct thread *td)
  328 {
  329         struct pcb *pcb;
  330 
  331         pcb = td->td_pcb; 
  332         if (pcb->pcb_ext != NULL) {
  333                 /* XXXKSE  XXXSMP  not SMP SAFE.. what locks do we have? */
  334                 /* if (pcb->pcb_ext->ext_refcount-- == 1) ?? */
  335                 /*
  336                  * XXX do we need to move the TSS off the allocated pages
  337                  * before freeing them?  (not done here)
  338                  */
  339                 kmem_free(kernel_map, (vm_offset_t)pcb->pcb_ext,
  340                     ctob(IOPAGES + 1));
  341                 pcb->pcb_ext = NULL;
  342         }
  343 }
  344 
  345 void
  346 cpu_thread_swapin(struct thread *td)
  347 {
  348 }
  349 
  350 void
  351 cpu_thread_swapout(struct thread *td)
  352 {
  353 }
  354 
  355 void
  356 cpu_thread_setup(struct thread *td)
  357 {
  358 
  359         td->td_pcb = (struct pcb *)(td->td_kstack +
  360             td->td_kstack_pages * PAGE_SIZE) - 1;
  361         td->td_frame = (struct trapframe *)((caddr_t)td->td_pcb - 16) - 1;
  362         td->td_pcb->pcb_ext = NULL; 
  363 }
  364 
  365 /*
  366  * Initialize machine state (pcb and trap frame) for a new thread about to
  367  * upcall. Put enough state in the new thread's PCB to get it to go back 
  368  * userret(), where we can intercept it again to set the return (upcall)
  369  * Address and stack, along with those from upcals that are from other sources
  370  * such as those generated in thread_userret() itself.
  371  */
  372 void
  373 cpu_set_upcall(struct thread *td, struct thread *td0)
  374 {
  375         struct pcb *pcb2;
  376 
  377         /* Point the pcb to the top of the stack. */
  378         pcb2 = td->td_pcb;
  379 
  380         /*
  381          * Copy the upcall pcb.  This loads kernel regs.
  382          * Those not loaded individually below get their default
  383          * values here.
  384          *
  385          * XXXKSE It might be a good idea to simply skip this as
  386          * the values of the other registers may be unimportant.
  387          * This would remove any requirement for knowing the KSE
  388          * at this time (see the matching comment below for
  389          * more analysis) (need a good safe default).
  390          */
  391         bcopy(td0->td_pcb, pcb2, sizeof(*pcb2));
  392         pcb2->pcb_flags &= ~(PCB_NPXTRAP|PCB_NPXINITDONE);
  393 
  394         /*
  395          * Create a new fresh stack for the new thread.
  396          * The -16 is so we can expand the trapframe if we go to vm86.
  397          * Don't forget to set this stack value into whatever supplies
  398          * the address for the fault handlers.
  399          * The contexts are filled in at the time we actually DO the
  400          * upcall as only then do we know which KSE we got.
  401          */
  402         bcopy(td0->td_frame, td->td_frame, sizeof(struct trapframe));
  403 
  404         /*
  405          * Set registers for trampoline to user mode.  Leave space for the
  406          * return address on stack.  These are the kernel mode register values.
  407          */
  408 #ifdef PAE
  409         pcb2->pcb_cr3 = vtophys(vmspace_pmap(td->td_proc->p_vmspace)->pm_pdpt);
  410 #else
  411         pcb2->pcb_cr3 = vtophys(vmspace_pmap(td->td_proc->p_vmspace)->pm_pdir);
  412 #endif
  413         pcb2->pcb_edi = 0;
  414         pcb2->pcb_esi = (int)fork_return;                   /* trampoline arg */
  415         pcb2->pcb_ebp = 0;
  416         pcb2->pcb_esp = (int)td->td_frame - sizeof(void *); /* trampoline arg */
  417         pcb2->pcb_ebx = (int)td;                            /* trampoline arg */
  418         pcb2->pcb_eip = (int)fork_trampoline;
  419         pcb2->pcb_psl &= ~(PSL_I);      /* interrupts must be disabled */
  420         pcb2->pcb_gs = rgs();
  421         /*
  422          * If we didn't copy the pcb, we'd need to do the following registers:
  423          * pcb2->pcb_dr*:       cloned above.
  424          * pcb2->pcb_savefpu:   cloned above.
  425          * pcb2->pcb_flags:     cloned above.
  426          * pcb2->pcb_onfault:   cloned above (always NULL here?).
  427          * pcb2->pcb_gs:        cloned above.  XXXKSE ???
  428          * pcb2->pcb_ext:       cleared below.
  429          */
  430         pcb2->pcb_ext = NULL;
  431 
  432         /* Setup to release sched_lock in fork_exit(). */
  433         td->td_md.md_spinlock_count = 1;
  434         td->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
  435 }
  436 
  437 /*
  438  * Set that machine state for performing an upcall that has to
  439  * be done in thread_userret() so that those upcalls generated
  440  * in thread_userret() itself can be done as well.
  441  */
  442 void
  443 cpu_set_upcall_kse(struct thread *td, void (*entry)(void *), void *arg,
  444         stack_t *stack)
  445 {
  446 
  447         /* 
  448          * Do any extra cleaning that needs to be done.
  449          * The thread may have optional components
  450          * that are not present in a fresh thread.
  451          * This may be a recycled thread so make it look
  452          * as though it's newly allocated.
  453          */
  454         cpu_thread_clean(td);
  455 
  456         /*
  457          * Set the trap frame to point at the beginning of the uts
  458          * function.
  459          */
  460         td->td_frame->tf_ebp = 0; 
  461         td->td_frame->tf_esp =
  462             (((int)stack->ss_sp + stack->ss_size - 4) & ~0x0f) - 4;
  463         td->td_frame->tf_eip = (int)entry;
  464 
  465         /*
  466          * Pass the address of the mailbox for this kse to the uts
  467          * function as a parameter on the stack.
  468          */
  469         suword((void *)(td->td_frame->tf_esp + sizeof(void *)),
  470             (int)arg);
  471 }
  472 
  473 int
  474 cpu_set_user_tls(struct thread *td, void *tls_base)
  475 {
  476         struct segment_descriptor sd;
  477         uint32_t base;
  478 
  479         /*
  480          * Construct a descriptor and store it in the pcb for
  481          * the next context switch.  Also store it in the gdt
  482          * so that the load of tf_fs into %fs will activate it
  483          * at return to userland.
  484          */
  485         base = (uint32_t)tls_base;
  486         sd.sd_lobase = base & 0xffffff;
  487         sd.sd_hibase = (base >> 24) & 0xff;
  488         sd.sd_lolimit = 0xffff; /* 4GB limit, wraps around */
  489         sd.sd_hilimit = 0xf;
  490         sd.sd_type  = SDT_MEMRWA;
  491         sd.sd_dpl   = SEL_UPL;
  492         sd.sd_p     = 1;
  493         sd.sd_xx    = 0;
  494         sd.sd_def32 = 1;
  495         sd.sd_gran  = 1;
  496         critical_enter();
  497         /* set %gs */
  498         td->td_pcb->pcb_gsd = sd;
  499         if (td == curthread) {
  500                 PCPU_GET(fsgs_gdt)[1] = sd;
  501                 load_gs(GSEL(GUGS_SEL, SEL_UPL));
  502         }
  503         critical_exit();
  504         return (0);
  505 }
  506 
  507 /*
  508  * Convert kernel VA to physical address
  509  */
  510 vm_paddr_t
  511 kvtop(void *addr)
  512 {
  513         vm_paddr_t pa;
  514 
  515         pa = pmap_kextract((vm_offset_t)addr);
  516         if (pa == 0)
  517                 panic("kvtop: zero page frame");
  518         return (pa);
  519 }
  520 
  521 #ifdef SMP
  522 static void
  523 cpu_reset_proxy()
  524 {
  525 
  526         cpu_reset_proxy_active = 1;
  527         while (cpu_reset_proxy_active == 1)
  528                 ;       /* Wait for other cpu to see that we've started */
  529         stop_cpus((1<<cpu_reset_proxyid));
  530         printf("cpu_reset_proxy: Stopped CPU %d\n", cpu_reset_proxyid);
  531         DELAY(1000000);
  532         cpu_reset_real();
  533 }
  534 #endif
  535 
  536 void
  537 cpu_reset()
  538 {
  539 #ifdef SMP
  540         u_int cnt, map;
  541 
  542         if (smp_active) {
  543                 map = PCPU_GET(other_cpus) & ~stopped_cpus;
  544                 if (map != 0) {
  545                         printf("cpu_reset: Stopping other CPUs\n");
  546                         stop_cpus(map);
  547                 }
  548 
  549                 if (PCPU_GET(cpuid) != 0) {
  550                         cpu_reset_proxyid = PCPU_GET(cpuid);
  551                         cpustop_restartfunc = cpu_reset_proxy;
  552                         cpu_reset_proxy_active = 0;
  553                         printf("cpu_reset: Restarting BSP\n");
  554                         started_cpus = (1<<0);          /* Restart CPU #0 */
  555 
  556                         cnt = 0;
  557                         while (cpu_reset_proxy_active == 0 && cnt < 10000000)
  558                                 cnt++;  /* Wait for BSP to announce restart */
  559                         if (cpu_reset_proxy_active == 0)
  560                                 printf("cpu_reset: Failed to restart BSP\n");
  561                         enable_intr();
  562                         cpu_reset_proxy_active = 2;
  563 
  564                         while (1);
  565                         /* NOTREACHED */
  566                 }
  567 
  568                 DELAY(1000000);
  569         }
  570 #endif
  571         cpu_reset_real();
  572         /* NOTREACHED */
  573 }
  574 
  575 static void
  576 cpu_reset_real()
  577 {
  578 
  579 #ifdef CPU_ELAN
  580         if (elan_mmcr != NULL)
  581                 elan_mmcr->RESCFG = 1;
  582 #endif
  583 
  584         if (cpu == CPU_GEODE1100) {
  585                 /* Attempt Geode's own reset */
  586                 outl(0xcf8, 0x80009044ul);
  587                 outl(0xcfc, 0xf);
  588         }
  589 
  590 #ifdef PC98
  591         /*
  592          * Attempt to do a CPU reset via CPU reset port.
  593          */
  594         disable_intr();
  595         if ((inb(0x35) & 0xa0) != 0xa0) {
  596                 outb(0x37, 0x0f);               /* SHUT0 = 0. */
  597                 outb(0x37, 0x0b);               /* SHUT1 = 0. */
  598         }
  599         outb(0xf0, 0x00);               /* Reset. */
  600 #else
  601 #if !defined(BROKEN_KEYBOARD_RESET)
  602         /*
  603          * Attempt to do a CPU reset via the keyboard controller,
  604          * do not turn off GateA20, as any machine that fails
  605          * to do the reset here would then end up in no man's land.
  606          */
  607         outb(IO_KBD + 4, 0xFE);
  608         DELAY(500000);  /* wait 0.5 sec to see if that did it */
  609         printf("Keyboard reset did not work, attempting CPU shutdown\n");
  610         DELAY(1000000); /* wait 1 sec for printf to complete */
  611 #endif
  612 #endif /* PC98 */
  613 
  614         /* Force a shutdown by unmapping entire address space. */
  615         bzero((caddr_t)PTD, NBPTD);
  616 
  617         /* "good night, sweet prince .... <THUNK!>" */
  618         invltlb();
  619         /* NOTREACHED */
  620         while(1);
  621 }
  622 
  623 /*
  624  * Allocate a pool of sf_bufs (sendfile(2) or "super-fast" if you prefer. :-))
  625  */
  626 static void
  627 sf_buf_init(void *arg)
  628 {
  629         struct sf_buf *sf_bufs;
  630         vm_offset_t sf_base;
  631         int i;
  632 
  633         nsfbufs = NSFBUFS;
  634         TUNABLE_INT_FETCH("kern.ipc.nsfbufs", &nsfbufs);
  635 
  636         sf_buf_active = hashinit(nsfbufs, M_TEMP, &sf_buf_hashmask);
  637         TAILQ_INIT(&sf_buf_freelist);
  638         sf_base = kmem_alloc_nofault(kernel_map, nsfbufs * PAGE_SIZE);
  639         sf_bufs = malloc(nsfbufs * sizeof(struct sf_buf), M_TEMP,
  640             M_NOWAIT | M_ZERO);
  641         for (i = 0; i < nsfbufs; i++) {
  642                 sf_bufs[i].kva = sf_base + i * PAGE_SIZE;
  643                 TAILQ_INSERT_TAIL(&sf_buf_freelist, &sf_bufs[i], free_entry);
  644         }
  645         sf_buf_alloc_want = 0;
  646         mtx_init(&sf_buf_lock, "sf_buf", NULL, MTX_DEF);
  647 }
  648 
  649 /*
  650  * Get an sf_buf from the freelist. Will block if none are available.
  651  */
  652 struct sf_buf *
  653 sf_buf_alloc(struct vm_page *m, int flags)
  654 {
  655         pt_entry_t opte, *ptep;
  656         struct sf_head *hash_list;
  657         struct sf_buf *sf;
  658 #ifdef SMP
  659         cpumask_t cpumask, other_cpus;
  660 #endif
  661         int error;
  662 
  663         KASSERT(curthread->td_pinned > 0 || (flags & SFB_CPUPRIVATE) == 0,
  664             ("sf_buf_alloc(SFB_CPUPRIVATE): curthread not pinned"));
  665         hash_list = &sf_buf_active[SF_BUF_HASH(m)];
  666         mtx_lock(&sf_buf_lock);
  667         LIST_FOREACH(sf, hash_list, list_entry) {
  668                 if (sf->m == m) {
  669                         sf->ref_count++;
  670                         if (sf->ref_count == 1) {
  671                                 TAILQ_REMOVE(&sf_buf_freelist, sf, free_entry);
  672                                 nsfbufsused++;
  673                                 nsfbufspeak = imax(nsfbufspeak, nsfbufsused);
  674                         }
  675 #ifdef SMP
  676                         goto shootdown; 
  677 #else
  678                         goto done;
  679 #endif
  680                 }
  681         }
  682         while ((sf = TAILQ_FIRST(&sf_buf_freelist)) == NULL) {
  683                 if (flags & SFB_NOWAIT)
  684                         goto done;
  685                 sf_buf_alloc_want++;
  686                 mbstat.sf_allocwait++;
  687                 error = msleep(&sf_buf_freelist, &sf_buf_lock,
  688                     (flags & SFB_CATCH) ? PCATCH | PVM : PVM, "sfbufa", 0);
  689                 sf_buf_alloc_want--;
  690 
  691                 /*
  692                  * If we got a signal, don't risk going back to sleep. 
  693                  */
  694                 if (error)
  695                         goto done;
  696         }
  697         TAILQ_REMOVE(&sf_buf_freelist, sf, free_entry);
  698         if (sf->m != NULL)
  699                 LIST_REMOVE(sf, list_entry);
  700         LIST_INSERT_HEAD(hash_list, sf, list_entry);
  701         sf->ref_count = 1;
  702         sf->m = m;
  703         nsfbufsused++;
  704         nsfbufspeak = imax(nsfbufspeak, nsfbufsused);
  705 
  706         /*
  707          * Update the sf_buf's virtual-to-physical mapping, flushing the
  708          * virtual address from the TLB.  Since the reference count for 
  709          * the sf_buf's old mapping was zero, that mapping is not 
  710          * currently in use.  Consequently, there is no need to exchange 
  711          * the old and new PTEs atomically, even under PAE.
  712          */
  713         ptep = vtopte(sf->kva);
  714         opte = *ptep;
  715         *ptep = VM_PAGE_TO_PHYS(m) | pgeflag | PG_RW | PG_V;
  716 
  717         /*
  718          * Avoid unnecessary TLB invalidations: If the sf_buf's old
  719          * virtual-to-physical mapping was not used, then any processor
  720          * that has invalidated the sf_buf's virtual address from its TLB
  721          * since the last used mapping need not invalidate again.
  722          */
  723 #ifdef SMP
  724         if ((opte & (PG_V | PG_A)) ==  (PG_V | PG_A))
  725                 sf->cpumask = 0;
  726 shootdown:
  727         sched_pin();
  728         cpumask = PCPU_GET(cpumask);
  729         if ((sf->cpumask & cpumask) == 0) {
  730                 sf->cpumask |= cpumask;
  731                 invlpg(sf->kva);
  732         }
  733         if ((flags & SFB_CPUPRIVATE) == 0) {
  734                 other_cpus = PCPU_GET(other_cpus) & ~sf->cpumask;
  735                 if (other_cpus != 0) {
  736                         sf->cpumask |= other_cpus;
  737                         mtx_lock_spin(&smp_ipi_mtx);
  738                         smp_masked_invlpg(other_cpus, sf->kva);
  739                         mtx_unlock_spin(&smp_ipi_mtx);
  740                 }
  741         }
  742         sched_unpin();  
  743 #else
  744         if ((opte & (PG_V | PG_A)) ==  (PG_V | PG_A))
  745                 pmap_invalidate_page(kernel_pmap, sf->kva);
  746 #endif
  747 done:
  748         mtx_unlock(&sf_buf_lock);
  749         return (sf);
  750 }
  751 
  752 /*
  753  * Remove a reference from the given sf_buf, adding it to the free
  754  * list when its reference count reaches zero.  A freed sf_buf still,
  755  * however, retains its virtual-to-physical mapping until it is
  756  * recycled or reactivated by sf_buf_alloc(9).
  757  */
  758 void
  759 sf_buf_free(struct sf_buf *sf)
  760 {
  761 
  762         mtx_lock(&sf_buf_lock);
  763         sf->ref_count--;
  764         if (sf->ref_count == 0) {
  765                 TAILQ_INSERT_TAIL(&sf_buf_freelist, sf, free_entry);
  766                 nsfbufsused--;
  767                 if (sf_buf_alloc_want > 0)
  768                         wakeup_one(&sf_buf_freelist);
  769         }
  770         mtx_unlock(&sf_buf_lock);
  771 }
  772 
  773 /*
  774  * Software interrupt handler for queued VM system processing.
  775  */   
  776 void  
  777 swi_vm(void *dummy) 
  778 {     
  779         if (busdma_swi_pending != 0)
  780                 busdma_swi();
  781 }
  782 
  783 /*
  784  * Tell whether this address is in some physical memory region.
  785  * Currently used by the kernel coredump code in order to avoid
  786  * dumping the ``ISA memory hole'' which could cause indefinite hangs,
  787  * or other unpredictable behaviour.
  788  */
  789 
  790 int
  791 is_physical_memory(vm_paddr_t addr)
  792 {
  793 
  794 #ifdef DEV_ISA
  795         /* The ISA ``memory hole''. */
  796         if (addr >= 0xa0000 && addr < 0x100000)
  797                 return 0;
  798 #endif
  799 
  800         /*
  801          * stuff other tests for known memory-mapped devices (PCI?)
  802          * here
  803          */
  804 
  805         return 1;
  806 }

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