The Design and Implementation of the FreeBSD Operating System, Second Edition
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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/9.1/sys/i386/i386/vm_machdep.c 223758 2011-07-04 12:04:52Z attilio $");
   45 
   46 #include "opt_isa.h"
   47 #include "opt_npx.h"
   48 #include "opt_reset.h"
   49 #include "opt_cpu.h"
   50 #include "opt_xbox.h"
   51 
   52 #include <sys/param.h>
   53 #include <sys/systm.h>
   54 #include <sys/bio.h>
   55 #include <sys/buf.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/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 #ifdef CPU_ELAN
   82 #include <machine/elan_mmcr.h>
   83 #endif
   84 
   85 #include <vm/vm.h>
   86 #include <vm/vm_extern.h>
   87 #include <vm/vm_kern.h>
   88 #include <vm/vm_page.h>
   89 #include <vm/vm_map.h>
   90 #include <vm/vm_param.h>
   91 
   92 #ifdef XEN
   93 #include <xen/hypervisor.h>
   94 #endif
   95 #ifdef PC98
   96 #include <pc98/cbus/cbus.h>
   97 #else
   98 #include <x86/isa/isa.h>
   99 #endif
  100 
  101 #ifdef XBOX
  102 #include <machine/xbox.h>
  103 #endif
  104 
  105 #ifndef NSFBUFS
  106 #define NSFBUFS         (512 + maxusers * 16)
  107 #endif
  108 
  109 static void     cpu_reset_real(void);
  110 #ifdef SMP
  111 static void     cpu_reset_proxy(void);
  112 static u_int    cpu_reset_proxyid;
  113 static volatile u_int   cpu_reset_proxy_active;
  114 #endif
  115 static void     sf_buf_init(void *arg);
  116 SYSINIT(sock_sf, SI_SUB_MBUF, SI_ORDER_ANY, sf_buf_init, NULL);
  117 
  118 LIST_HEAD(sf_head, sf_buf);
  119 
  120 /*
  121  * A hash table of active sendfile(2) buffers
  122  */
  123 static struct sf_head *sf_buf_active;
  124 static u_long sf_buf_hashmask;
  125 
  126 #define SF_BUF_HASH(m)  (((m) - vm_page_array) & sf_buf_hashmask)
  127 
  128 static TAILQ_HEAD(, sf_buf) sf_buf_freelist;
  129 static u_int    sf_buf_alloc_want;
  130 
  131 /*
  132  * A lock used to synchronize access to the hash table and free list
  133  */
  134 static struct mtx sf_buf_lock;
  135 
  136 extern int      _ucodesel, _udatasel;
  137 
  138 /*
  139  * Finish a fork operation, with process p2 nearly set up.
  140  * Copy and update the pcb, set up the stack so that the child
  141  * ready to run and return to user mode.
  142  */
  143 void
  144 cpu_fork(td1, p2, td2, flags)
  145         register struct thread *td1;
  146         register struct proc *p2;
  147         struct thread *td2;
  148         int flags;
  149 {
  150         register struct proc *p1;
  151         struct pcb *pcb2;
  152         struct mdproc *mdp2;
  153 
  154         p1 = td1->td_proc;
  155         if ((flags & RFPROC) == 0) {
  156                 if ((flags & RFMEM) == 0) {
  157                         /* unshare user LDT */
  158                         struct mdproc *mdp1 = &p1->p_md;
  159                         struct proc_ldt *pldt, *pldt1;
  160 
  161                         mtx_lock_spin(&dt_lock);
  162                         if ((pldt1 = mdp1->md_ldt) != NULL &&
  163                             pldt1->ldt_refcnt > 1) {
  164                                 pldt = user_ldt_alloc(mdp1, pldt1->ldt_len);
  165                                 if (pldt == NULL)
  166                                         panic("could not copy LDT");
  167                                 mdp1->md_ldt = pldt;
  168                                 set_user_ldt(mdp1);
  169                                 user_ldt_deref(pldt1);
  170                         } else
  171                                 mtx_unlock_spin(&dt_lock);
  172                 }
  173                 return;
  174         }
  175 
  176         /* Ensure that td1's pcb is up to date. */
  177         if (td1 == curthread)
  178                 td1->td_pcb->pcb_gs = rgs();
  179 #ifdef DEV_NPX
  180         critical_enter();
  181         if (PCPU_GET(fpcurthread) == td1)
  182                 npxsave(td1->td_pcb->pcb_save);
  183         critical_exit();
  184 #endif
  185 
  186         /* Point the pcb to the top of the stack */
  187         pcb2 = (struct pcb *)(td2->td_kstack +
  188             td2->td_kstack_pages * PAGE_SIZE) - 1;
  189         td2->td_pcb = pcb2;
  190 
  191         /* Copy td1's pcb */
  192         bcopy(td1->td_pcb, pcb2, sizeof(*pcb2));
  193 
  194         /* Properly initialize pcb_save */
  195         pcb2->pcb_save = &pcb2->pcb_user_save;
  196 
  197         /* Point mdproc and then copy over td1's contents */
  198         mdp2 = &p2->p_md;
  199         bcopy(&p1->p_md, mdp2, sizeof(*mdp2));
  200 
  201         /*
  202          * Create a new fresh stack for the new process.
  203          * Copy the trap frame for the return to user mode as if from a
  204          * syscall.  This copies most of the user mode register values.
  205          * The -16 is so we can expand the trapframe if we go to vm86.
  206          */
  207         td2->td_frame = (struct trapframe *)((caddr_t)td2->td_pcb - 16) - 1;
  208         bcopy(td1->td_frame, td2->td_frame, sizeof(struct trapframe));
  209 
  210         td2->td_frame->tf_eax = 0;              /* Child returns zero */
  211         td2->td_frame->tf_eflags &= ~PSL_C;     /* success */
  212         td2->td_frame->tf_edx = 1;
  213 
  214         /*
  215          * If the parent process has the trap bit set (i.e. a debugger had
  216          * single stepped the process to the system call), we need to clear
  217          * the trap flag from the new frame unless the debugger had set PF_FORK
  218          * on the parent.  Otherwise, the child will receive a (likely
  219          * unexpected) SIGTRAP when it executes the first instruction after
  220          * returning  to userland.
  221          */
  222         if ((p1->p_pfsflags & PF_FORK) == 0)
  223                 td2->td_frame->tf_eflags &= ~PSL_T;
  224 
  225         /*
  226          * Set registers for trampoline to user mode.  Leave space for the
  227          * return address on stack.  These are the kernel mode register values.
  228          */
  229 #ifdef PAE
  230         pcb2->pcb_cr3 = vtophys(vmspace_pmap(p2->p_vmspace)->pm_pdpt);
  231 #else
  232         pcb2->pcb_cr3 = vtophys(vmspace_pmap(p2->p_vmspace)->pm_pdir);
  233 #endif
  234         pcb2->pcb_edi = 0;
  235         pcb2->pcb_esi = (int)fork_return;       /* fork_trampoline argument */
  236         pcb2->pcb_ebp = 0;
  237         pcb2->pcb_esp = (int)td2->td_frame - sizeof(void *);
  238         pcb2->pcb_ebx = (int)td2;               /* fork_trampoline argument */
  239         pcb2->pcb_eip = (int)fork_trampoline;
  240         pcb2->pcb_psl = PSL_KERNEL;             /* ints disabled */
  241         /*-
  242          * pcb2->pcb_dr*:       cloned above.
  243          * pcb2->pcb_savefpu:   cloned above.
  244          * pcb2->pcb_flags:     cloned above.
  245          * pcb2->pcb_onfault:   cloned above (always NULL here?).
  246          * pcb2->pcb_gs:        cloned above.
  247          * pcb2->pcb_ext:       cleared below.
  248          */
  249 
  250         /*
  251          * XXX don't copy the i/o pages.  this should probably be fixed.
  252          */
  253         pcb2->pcb_ext = 0;
  254 
  255         /* Copy the LDT, if necessary. */
  256         mtx_lock_spin(&dt_lock);
  257         if (mdp2->md_ldt != NULL) {
  258                 if (flags & RFMEM) {
  259                         mdp2->md_ldt->ldt_refcnt++;
  260                 } else {
  261                         mdp2->md_ldt = user_ldt_alloc(mdp2,
  262                             mdp2->md_ldt->ldt_len);
  263                         if (mdp2->md_ldt == NULL)
  264                                 panic("could not copy LDT");
  265                 }
  266         }
  267         mtx_unlock_spin(&dt_lock);
  268 
  269         /* Setup to release spin count in fork_exit(). */
  270         td2->td_md.md_spinlock_count = 1;
  271         /*
  272          * XXX XEN need to check on PSL_USER is handled
  273          */
  274         td2->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
  275         /*
  276          * Now, cpu_switch() can schedule the new process.
  277          * pcb_esp is loaded pointing to the cpu_switch() stack frame
  278          * containing the return address when exiting cpu_switch.
  279          * This will normally be to fork_trampoline(), which will have
  280          * %ebx loaded with the new proc's pointer.  fork_trampoline()
  281          * will set up a stack to call fork_return(p, frame); to complete
  282          * the return to user-mode.
  283          */
  284 }
  285 
  286 /*
  287  * Intercept the return address from a freshly forked process that has NOT
  288  * been scheduled yet.
  289  *
  290  * This is needed to make kernel threads stay in kernel mode.
  291  */
  292 void
  293 cpu_set_fork_handler(td, func, arg)
  294         struct thread *td;
  295         void (*func)(void *);
  296         void *arg;
  297 {
  298         /*
  299          * Note that the trap frame follows the args, so the function
  300          * is really called like this:  func(arg, frame);
  301          */
  302         td->td_pcb->pcb_esi = (int) func;       /* function */
  303         td->td_pcb->pcb_ebx = (int) arg;        /* first arg */
  304 }
  305 
  306 void
  307 cpu_exit(struct thread *td)
  308 {
  309 
  310         /*
  311          * If this process has a custom LDT, release it.  Reset pc->pcb_gs
  312          * and %gs before we free it in case they refer to an LDT entry.
  313          */
  314         mtx_lock_spin(&dt_lock);
  315         if (td->td_proc->p_md.md_ldt) {
  316                 td->td_pcb->pcb_gs = _udatasel;
  317                 load_gs(_udatasel);
  318                 user_ldt_free(td);
  319         } else
  320                 mtx_unlock_spin(&dt_lock);
  321 }
  322 
  323 void
  324 cpu_thread_exit(struct thread *td)
  325 {
  326 
  327 #ifdef DEV_NPX
  328         critical_enter();
  329         if (td == PCPU_GET(fpcurthread))
  330                 npxdrop();
  331         critical_exit();
  332 #endif
  333 
  334         /* Disable any hardware breakpoints. */
  335         if (td->td_pcb->pcb_flags & PCB_DBREGS) {
  336                 reset_dbregs();
  337                 td->td_pcb->pcb_flags &= ~PCB_DBREGS;
  338         }
  339 }
  340 
  341 void
  342 cpu_thread_clean(struct thread *td)
  343 {
  344         struct pcb *pcb;
  345 
  346         pcb = td->td_pcb; 
  347         if (pcb->pcb_ext != NULL) {
  348                 /* if (pcb->pcb_ext->ext_refcount-- == 1) ?? */
  349                 /*
  350                  * XXX do we need to move the TSS off the allocated pages
  351                  * before freeing them?  (not done here)
  352                  */
  353                 kmem_free(kernel_map, (vm_offset_t)pcb->pcb_ext,
  354                     ctob(IOPAGES + 1));
  355                 pcb->pcb_ext = NULL;
  356         }
  357 }
  358 
  359 void
  360 cpu_thread_swapin(struct thread *td)
  361 {
  362 }
  363 
  364 void
  365 cpu_thread_swapout(struct thread *td)
  366 {
  367 }
  368 
  369 void
  370 cpu_thread_alloc(struct thread *td)
  371 {
  372 
  373         td->td_pcb = (struct pcb *)(td->td_kstack +
  374             td->td_kstack_pages * PAGE_SIZE) - 1;
  375         td->td_frame = (struct trapframe *)((caddr_t)td->td_pcb - 16) - 1;
  376         td->td_pcb->pcb_ext = NULL; 
  377         td->td_pcb->pcb_save = &td->td_pcb->pcb_user_save;
  378 }
  379 
  380 void
  381 cpu_thread_free(struct thread *td)
  382 {
  383 
  384         cpu_thread_clean(td);
  385 }
  386 
  387 void
  388 cpu_set_syscall_retval(struct thread *td, int error)
  389 {
  390 
  391         switch (error) {
  392         case 0:
  393                 td->td_frame->tf_eax = td->td_retval[0];
  394                 td->td_frame->tf_edx = td->td_retval[1];
  395                 td->td_frame->tf_eflags &= ~PSL_C;
  396                 break;
  397 
  398         case ERESTART:
  399                 /*
  400                  * Reconstruct pc, assuming lcall $X,y is 7 bytes, int
  401                  * 0x80 is 2 bytes. We saved this in tf_err.
  402                  */
  403                 td->td_frame->tf_eip -= td->td_frame->tf_err;
  404                 break;
  405 
  406         case EJUSTRETURN:
  407                 break;
  408 
  409         default:
  410                 if (td->td_proc->p_sysent->sv_errsize) {
  411                         if (error >= td->td_proc->p_sysent->sv_errsize)
  412                                 error = -1;     /* XXX */
  413                         else
  414                                 error = td->td_proc->p_sysent->sv_errtbl[error];
  415                 }
  416                 td->td_frame->tf_eax = error;
  417                 td->td_frame->tf_eflags |= PSL_C;
  418                 break;
  419         }
  420 }
  421 
  422 /*
  423  * Initialize machine state (pcb and trap frame) for a new thread about to
  424  * upcall. Put enough state in the new thread's PCB to get it to go back 
  425  * userret(), where we can intercept it again to set the return (upcall)
  426  * Address and stack, along with those from upcals that are from other sources
  427  * such as those generated in thread_userret() itself.
  428  */
  429 void
  430 cpu_set_upcall(struct thread *td, struct thread *td0)
  431 {
  432         struct pcb *pcb2;
  433 
  434         /* Point the pcb to the top of the stack. */
  435         pcb2 = td->td_pcb;
  436 
  437         /*
  438          * Copy the upcall pcb.  This loads kernel regs.
  439          * Those not loaded individually below get their default
  440          * values here.
  441          */
  442         bcopy(td0->td_pcb, pcb2, sizeof(*pcb2));
  443         pcb2->pcb_flags &= ~(PCB_NPXINITDONE | PCB_NPXUSERINITDONE);
  444         pcb2->pcb_save = &pcb2->pcb_user_save;
  445 
  446         /*
  447          * Create a new fresh stack for the new thread.
  448          */
  449         bcopy(td0->td_frame, td->td_frame, sizeof(struct trapframe));
  450 
  451         /* If the current thread has the trap bit set (i.e. a debugger had
  452          * single stepped the process to the system call), we need to clear
  453          * the trap flag from the new frame. Otherwise, the new thread will
  454          * receive a (likely unexpected) SIGTRAP when it executes the first
  455          * instruction after returning to userland.
  456          */
  457         td->td_frame->tf_eflags &= ~PSL_T;
  458 
  459         /*
  460          * Set registers for trampoline to user mode.  Leave space for the
  461          * return address on stack.  These are the kernel mode register values.
  462          */
  463         pcb2->pcb_edi = 0;
  464         pcb2->pcb_esi = (int)fork_return;                   /* trampoline arg */
  465         pcb2->pcb_ebp = 0;
  466         pcb2->pcb_esp = (int)td->td_frame - sizeof(void *); /* trampoline arg */
  467         pcb2->pcb_ebx = (int)td;                            /* trampoline arg */
  468         pcb2->pcb_eip = (int)fork_trampoline;
  469         pcb2->pcb_psl &= ~(PSL_I);      /* interrupts must be disabled */
  470         pcb2->pcb_gs = rgs();
  471         /*
  472          * If we didn't copy the pcb, we'd need to do the following registers:
  473          * pcb2->pcb_cr3:       cloned above.
  474          * pcb2->pcb_dr*:       cloned above.
  475          * pcb2->pcb_savefpu:   cloned above.
  476          * pcb2->pcb_flags:     cloned above.
  477          * pcb2->pcb_onfault:   cloned above (always NULL here?).
  478          * pcb2->pcb_gs:        cloned above.
  479          * pcb2->pcb_ext:       cleared below.
  480          */
  481         pcb2->pcb_ext = NULL;
  482 
  483         /* Setup to release spin count in fork_exit(). */
  484         td->td_md.md_spinlock_count = 1;
  485         td->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
  486 }
  487 
  488 /*
  489  * Set that machine state for performing an upcall that has to
  490  * be done in thread_userret() so that those upcalls generated
  491  * in thread_userret() itself can be done as well.
  492  */
  493 void
  494 cpu_set_upcall_kse(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 uts
  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         /*
  517          * Pass the address of the mailbox for this kse to the uts
  518          * function as a parameter on the stack.
  519          */
  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 #ifdef SMP
  573 static void
  574 cpu_reset_proxy()
  575 {
  576         cpuset_t tcrp;
  577 
  578         cpu_reset_proxy_active = 1;
  579         while (cpu_reset_proxy_active == 1)
  580                 ;       /* Wait for other cpu to see that we've started */
  581         CPU_SETOF(cpu_reset_proxyid, &tcrp);
  582         stop_cpus(tcrp);
  583         printf("cpu_reset_proxy: Stopped CPU %d\n", cpu_reset_proxyid);
  584         DELAY(1000000);
  585         cpu_reset_real();
  586 }
  587 #endif
  588 
  589 void
  590 cpu_reset()
  591 {
  592 #ifdef XBOX
  593         if (arch_i386_is_xbox) {
  594                 /* Kick the PIC16L, it can reboot the box */
  595                 pic16l_reboot();
  596                 for (;;);
  597         }
  598 #endif
  599 
  600 #ifdef SMP
  601         cpuset_t map;
  602         u_int cnt;
  603 
  604         if (smp_active) {
  605                 map = all_cpus;
  606                 CPU_CLR(PCPU_GET(cpuid), &map);
  607                 CPU_NAND(&map, &stopped_cpus);
  608                 if (!CPU_EMPTY(&map)) {
  609                         printf("cpu_reset: Stopping other CPUs\n");
  610                         stop_cpus(map);
  611                 }
  612 
  613                 if (PCPU_GET(cpuid) != 0) {
  614                         cpu_reset_proxyid = PCPU_GET(cpuid);
  615                         cpustop_restartfunc = cpu_reset_proxy;
  616                         cpu_reset_proxy_active = 0;
  617                         printf("cpu_reset: Restarting BSP\n");
  618 
  619                         /* Restart CPU #0. */
  620                         /* XXX: restart_cpus(1 << 0); */
  621                         CPU_SETOF(0, &started_cpus);
  622                         wmb();
  623 
  624                         cnt = 0;
  625                         while (cpu_reset_proxy_active == 0 && cnt < 10000000)
  626                                 cnt++;  /* Wait for BSP to announce restart */
  627                         if (cpu_reset_proxy_active == 0)
  628                                 printf("cpu_reset: Failed to restart BSP\n");
  629                         enable_intr();
  630                         cpu_reset_proxy_active = 2;
  631 
  632                         while (1);
  633                         /* NOTREACHED */
  634                 }
  635 
  636                 DELAY(1000000);
  637         }
  638 #endif
  639         cpu_reset_real();
  640         /* NOTREACHED */
  641 }
  642 
  643 static void
  644 cpu_reset_real()
  645 {
  646         struct region_descriptor null_idt;
  647 #ifndef PC98
  648         int b;
  649 #endif
  650 
  651         disable_intr();
  652 #ifdef XEN
  653         if (smp_processor_id() == 0)
  654                 HYPERVISOR_shutdown(SHUTDOWN_reboot);
  655         else
  656                 HYPERVISOR_shutdown(SHUTDOWN_poweroff);
  657 #endif 
  658 #ifdef CPU_ELAN
  659         if (elan_mmcr != NULL)
  660                 elan_mmcr->RESCFG = 1;
  661 #endif
  662 
  663         if (cpu == CPU_GEODE1100) {
  664                 /* Attempt Geode's own reset */
  665                 outl(0xcf8, 0x80009044ul);
  666                 outl(0xcfc, 0xf);
  667         }
  668 
  669 #ifdef PC98
  670         /*
  671          * Attempt to do a CPU reset via CPU reset port.
  672          */
  673         if ((inb(0x35) & 0xa0) != 0xa0) {
  674                 outb(0x37, 0x0f);               /* SHUT0 = 0. */
  675                 outb(0x37, 0x0b);               /* SHUT1 = 0. */
  676         }
  677         outb(0xf0, 0x00);               /* Reset. */
  678 #else
  679 #if !defined(BROKEN_KEYBOARD_RESET)
  680         /*
  681          * Attempt to do a CPU reset via the keyboard controller,
  682          * do not turn off GateA20, as any machine that fails
  683          * to do the reset here would then end up in no man's land.
  684          */
  685         outb(IO_KBD + 4, 0xFE);
  686         DELAY(500000);  /* wait 0.5 sec to see if that did it */
  687 #endif
  688 
  689         /*
  690          * Attempt to force a reset via the Reset Control register at
  691          * I/O port 0xcf9.  Bit 2 forces a system reset when it
  692          * transitions from 0 to 1.  Bit 1 selects the type of reset
  693          * to attempt: 0 selects a "soft" reset, and 1 selects a
  694          * "hard" reset.  We try a "hard" reset.  The first write sets
  695          * bit 1 to select a "hard" reset and clears bit 2.  The
  696          * second write forces a 0 -> 1 transition in bit 2 to trigger
  697          * a reset.
  698          */
  699         outb(0xcf9, 0x2);
  700         outb(0xcf9, 0x6);
  701         DELAY(500000);  /* wait 0.5 sec to see if that did it */
  702 
  703         /*
  704          * Attempt to force a reset via the Fast A20 and Init register
  705          * at I/O port 0x92.  Bit 1 serves as an alternate A20 gate.
  706          * Bit 0 asserts INIT# when set to 1.  We are careful to only
  707          * preserve bit 1 while setting bit 0.  We also must clear bit
  708          * 0 before setting it if it isn't already clear.
  709          */
  710         b = inb(0x92);
  711         if (b != 0xff) {
  712                 if ((b & 0x1) != 0)
  713                         outb(0x92, b & 0xfe);
  714                 outb(0x92, b | 0x1);
  715                 DELAY(500000);  /* wait 0.5 sec to see if that did it */
  716         }
  717 #endif /* PC98 */
  718 
  719         printf("No known reset method worked, attempting CPU shutdown\n");
  720         DELAY(1000000); /* wait 1 sec for printf to complete */
  721 
  722         /* Wipe the IDT. */
  723         null_idt.rd_limit = 0;
  724         null_idt.rd_base = 0;
  725         lidt(&null_idt);
  726 
  727         /* "good night, sweet prince .... <THUNK!>" */
  728         breakpoint();
  729 
  730         /* NOTREACHED */
  731         while(1);
  732 }
  733 
  734 /*
  735  * Allocate a pool of sf_bufs (sendfile(2) or "super-fast" if you prefer. :-))
  736  */
  737 static void
  738 sf_buf_init(void *arg)
  739 {
  740         struct sf_buf *sf_bufs;
  741         vm_offset_t sf_base;
  742         int i;
  743 
  744         nsfbufs = NSFBUFS;
  745         TUNABLE_INT_FETCH("kern.ipc.nsfbufs", &nsfbufs);
  746 
  747         sf_buf_active = hashinit(nsfbufs, M_TEMP, &sf_buf_hashmask);
  748         TAILQ_INIT(&sf_buf_freelist);
  749         sf_base = kmem_alloc_nofault(kernel_map, nsfbufs * PAGE_SIZE);
  750         sf_bufs = malloc(nsfbufs * sizeof(struct sf_buf), M_TEMP,
  751             M_NOWAIT | M_ZERO);
  752         for (i = 0; i < nsfbufs; i++) {
  753                 sf_bufs[i].kva = sf_base + i * PAGE_SIZE;
  754                 TAILQ_INSERT_TAIL(&sf_buf_freelist, &sf_bufs[i], free_entry);
  755         }
  756         sf_buf_alloc_want = 0;
  757         mtx_init(&sf_buf_lock, "sf_buf", NULL, MTX_DEF);
  758 }
  759 
  760 /*
  761  * Invalidate the cache lines that may belong to the page, if
  762  * (possibly old) mapping of the page by sf buffer exists.  Returns
  763  * TRUE when mapping was found and cache invalidated.
  764  */
  765 boolean_t
  766 sf_buf_invalidate_cache(vm_page_t m)
  767 {
  768         struct sf_head *hash_list;
  769         struct sf_buf *sf;
  770         boolean_t ret;
  771 
  772         hash_list = &sf_buf_active[SF_BUF_HASH(m)];
  773         ret = FALSE;
  774         mtx_lock(&sf_buf_lock);
  775         LIST_FOREACH(sf, hash_list, list_entry) {
  776                 if (sf->m == m) {
  777                         /*
  778                          * Use pmap_qenter to update the pte for
  779                          * existing mapping, in particular, the PAT
  780                          * settings are recalculated.
  781                          */
  782                         pmap_qenter(sf->kva, &m, 1);
  783                         pmap_invalidate_cache_range(sf->kva, sf->kva +
  784                             PAGE_SIZE);
  785                         ret = TRUE;
  786                         break;
  787                 }
  788         }
  789         mtx_unlock(&sf_buf_lock);
  790         return (ret);
  791 }
  792 
  793 /*
  794  * Get an sf_buf from the freelist.  May block if none are available.
  795  */
  796 struct sf_buf *
  797 sf_buf_alloc(struct vm_page *m, int flags)
  798 {
  799         pt_entry_t opte, *ptep;
  800         struct sf_head *hash_list;
  801         struct sf_buf *sf;
  802 #ifdef SMP
  803         cpuset_t other_cpus;
  804         u_int cpuid;
  805 #endif
  806         int error;
  807 
  808         KASSERT(curthread->td_pinned > 0 || (flags & SFB_CPUPRIVATE) == 0,
  809             ("sf_buf_alloc(SFB_CPUPRIVATE): curthread not pinned"));
  810         hash_list = &sf_buf_active[SF_BUF_HASH(m)];
  811         mtx_lock(&sf_buf_lock);
  812         LIST_FOREACH(sf, hash_list, list_entry) {
  813                 if (sf->m == m) {
  814                         sf->ref_count++;
  815                         if (sf->ref_count == 1) {
  816                                 TAILQ_REMOVE(&sf_buf_freelist, sf, free_entry);
  817                                 nsfbufsused++;
  818                                 nsfbufspeak = imax(nsfbufspeak, nsfbufsused);
  819                         }
  820 #ifdef SMP
  821                         goto shootdown; 
  822 #else
  823                         goto done;
  824 #endif
  825                 }
  826         }
  827         while ((sf = TAILQ_FIRST(&sf_buf_freelist)) == NULL) {
  828                 if (flags & SFB_NOWAIT)
  829                         goto done;
  830                 sf_buf_alloc_want++;
  831                 mbstat.sf_allocwait++;
  832                 error = msleep(&sf_buf_freelist, &sf_buf_lock,
  833                     (flags & SFB_CATCH) ? PCATCH | PVM : PVM, "sfbufa", 0);
  834                 sf_buf_alloc_want--;
  835 
  836                 /*
  837                  * If we got a signal, don't risk going back to sleep. 
  838                  */
  839                 if (error)
  840                         goto done;
  841         }
  842         TAILQ_REMOVE(&sf_buf_freelist, sf, free_entry);
  843         if (sf->m != NULL)
  844                 LIST_REMOVE(sf, list_entry);
  845         LIST_INSERT_HEAD(hash_list, sf, list_entry);
  846         sf->ref_count = 1;
  847         sf->m = m;
  848         nsfbufsused++;
  849         nsfbufspeak = imax(nsfbufspeak, nsfbufsused);
  850 
  851         /*
  852          * Update the sf_buf's virtual-to-physical mapping, flushing the
  853          * virtual address from the TLB.  Since the reference count for 
  854          * the sf_buf's old mapping was zero, that mapping is not 
  855          * currently in use.  Consequently, there is no need to exchange 
  856          * the old and new PTEs atomically, even under PAE.
  857          */
  858         ptep = vtopte(sf->kva);
  859         opte = *ptep;
  860 #ifdef XEN
  861        PT_SET_MA(sf->kva, xpmap_ptom(VM_PAGE_TO_PHYS(m)) | pgeflag
  862            | PG_RW | PG_V | pmap_cache_bits(m->md.pat_mode, 0));
  863 #else
  864         *ptep = VM_PAGE_TO_PHYS(m) | pgeflag | PG_RW | PG_V |
  865             pmap_cache_bits(m->md.pat_mode, 0);
  866 #endif
  867 
  868         /*
  869          * Avoid unnecessary TLB invalidations: If the sf_buf's old
  870          * virtual-to-physical mapping was not used, then any processor
  871          * that has invalidated the sf_buf's virtual address from its TLB
  872          * since the last used mapping need not invalidate again.
  873          */
  874 #ifdef SMP
  875         if ((opte & (PG_V | PG_A)) ==  (PG_V | PG_A))
  876                 CPU_ZERO(&sf->cpumask);
  877 shootdown:
  878         sched_pin();
  879         cpuid = PCPU_GET(cpuid);
  880         if (!CPU_ISSET(cpuid, &sf->cpumask)) {
  881                 CPU_SET(cpuid, &sf->cpumask);
  882                 invlpg(sf->kva);
  883         }
  884         if ((flags & SFB_CPUPRIVATE) == 0) {
  885                 other_cpus = all_cpus;
  886                 CPU_CLR(cpuid, &other_cpus);
  887                 CPU_NAND(&other_cpus, &sf->cpumask);
  888                 if (!CPU_EMPTY(&other_cpus)) {
  889                         CPU_OR(&sf->cpumask, &other_cpus);
  890                         smp_masked_invlpg(other_cpus, sf->kva);
  891                 }
  892         }
  893         sched_unpin();
  894 #else
  895         if ((opte & (PG_V | PG_A)) ==  (PG_V | PG_A))
  896                 pmap_invalidate_page(kernel_pmap, sf->kva);
  897 #endif
  898 done:
  899         mtx_unlock(&sf_buf_lock);
  900         return (sf);
  901 }
  902 
  903 /*
  904  * Remove a reference from the given sf_buf, adding it to the free
  905  * list when its reference count reaches zero.  A freed sf_buf still,
  906  * however, retains its virtual-to-physical mapping until it is
  907  * recycled or reactivated by sf_buf_alloc(9).
  908  */
  909 void
  910 sf_buf_free(struct sf_buf *sf)
  911 {
  912 
  913         mtx_lock(&sf_buf_lock);
  914         sf->ref_count--;
  915         if (sf->ref_count == 0) {
  916                 TAILQ_INSERT_TAIL(&sf_buf_freelist, sf, free_entry);
  917                 nsfbufsused--;
  918 #ifdef XEN
  919 /*
  920  * Xen doesn't like having dangling R/W mappings
  921  */
  922                 pmap_qremove(sf->kva, 1);
  923                 sf->m = NULL;
  924                 LIST_REMOVE(sf, list_entry);
  925 #endif
  926                 if (sf_buf_alloc_want > 0)
  927                         wakeup(&sf_buf_freelist);
  928         }
  929         mtx_unlock(&sf_buf_lock);
  930 }
  931 
  932 /*
  933  * Software interrupt handler for queued VM system processing.
  934  */   
  935 void  
  936 swi_vm(void *dummy) 
  937 {     
  938         if (busdma_swi_pending != 0)
  939                 busdma_swi();
  940 }
  941 
  942 /*
  943  * Tell whether this address is in some physical memory region.
  944  * Currently used by the kernel coredump code in order to avoid
  945  * dumping the ``ISA memory hole'' which could cause indefinite hangs,
  946  * or other unpredictable behaviour.
  947  */
  948 
  949 int
  950 is_physical_memory(vm_paddr_t addr)
  951 {
  952 
  953 #ifdef DEV_ISA
  954         /* The ISA ``memory hole''. */
  955         if (addr >= 0xa0000 && addr < 0x100000)
  956                 return 0;
  957 #endif
  958 
  959         /*
  960          * stuff other tests for known memory-mapped devices (PCI?)
  961          * here
  962          */
  963 
  964         return 1;
  965 }

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