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: src/sys/i386/i386/vm_machdep.c,v 1.241.2.4 2006/03/17 19:07:33 alc Exp $");
   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/pc98/pc98.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 = mdp1->md_ldt;
  158                         if (pldt && pldt->ldt_refcnt > 1) {
  159                                 pldt = user_ldt_alloc(mdp1, pldt->ldt_len);
  160                                 if (pldt == NULL)
  161                                         panic("could not copy LDT");
  162                                 mdp1->md_ldt = pldt;
  163                                 set_user_ldt(mdp1);
  164                                 user_ldt_free(td1);
  165                         }
  166                 }
  167                 return;
  168         }
  169 
  170         /* Ensure that p1's pcb is up to date. */
  171 #ifdef DEV_NPX
  172         if (td1 == curthread)
  173                 td1->td_pcb->pcb_gs = rgs();
  174         savecrit = intr_disable();
  175         if (PCPU_GET(fpcurthread) == td1)
  176                 npxsave(&td1->td_pcb->pcb_save);
  177         intr_restore(savecrit);
  178 #endif
  179 
  180         /* Point the pcb to the top of the stack */
  181         pcb2 = (struct pcb *)(td2->td_kstack +
  182             td2->td_kstack_pages * PAGE_SIZE) - 1;
  183         td2->td_pcb = pcb2;
  184 
  185         /* Copy p1's pcb */
  186         bcopy(td1->td_pcb, pcb2, sizeof(*pcb2));
  187 
  188         /* Point mdproc and then copy over td1's contents */
  189         mdp2 = &p2->p_md;
  190         bcopy(&p1->p_md, mdp2, sizeof(*mdp2));
  191 
  192         /*
  193          * Create a new fresh stack for the new process.
  194          * Copy the trap frame for the return to user mode as if from a
  195          * syscall.  This copies most of the user mode register values.
  196          * The -16 is so we can expand the trapframe if we go to vm86.
  197          */
  198         td2->td_frame = (struct trapframe *)((caddr_t)td2->td_pcb - 16) - 1;
  199         bcopy(td1->td_frame, td2->td_frame, sizeof(struct trapframe));
  200 
  201         td2->td_frame->tf_eax = 0;              /* Child returns zero */
  202         td2->td_frame->tf_eflags &= ~PSL_C;     /* success */
  203         td2->td_frame->tf_edx = 1;
  204 
  205         /*
  206          * If the parent process has the trap bit set (i.e. a debugger had
  207          * single stepped the process to the system call), we need to clear
  208          * the trap flag from the new frame unless the debugger had set PF_FORK
  209          * on the parent.  Otherwise, the child will receive a (likely
  210          * unexpected) SIGTRAP when it executes the first instruction after
  211          * returning to userland.
  212          */
  213         if ((p1->p_pfsflags & PF_FORK) == 0)
  214                 td2->td_frame->tf_eflags &= ~PSL_T;
  215 
  216         /*
  217          * Set registers for trampoline to user mode.  Leave space for the
  218          * return address on stack.  These are the kernel mode register values.
  219          */
  220 #ifdef PAE
  221         pcb2->pcb_cr3 = vtophys(vmspace_pmap(p2->p_vmspace)->pm_pdpt);
  222 #else
  223         pcb2->pcb_cr3 = vtophys(vmspace_pmap(p2->p_vmspace)->pm_pdir);
  224 #endif
  225         pcb2->pcb_edi = 0;
  226         pcb2->pcb_esi = (int)fork_return;       /* fork_trampoline argument */
  227         pcb2->pcb_ebp = 0;
  228         pcb2->pcb_esp = (int)td2->td_frame - sizeof(void *);
  229         pcb2->pcb_ebx = (int)td2;               /* fork_trampoline argument */
  230         pcb2->pcb_eip = (int)fork_trampoline;
  231         pcb2->pcb_psl = PSL_KERNEL;             /* ints disabled */
  232         pcb2->pcb_gs = rgs();
  233         /*-
  234          * pcb2->pcb_dr*:       cloned above.
  235          * pcb2->pcb_savefpu:   cloned above.
  236          * pcb2->pcb_flags:     cloned above.
  237          * pcb2->pcb_onfault:   cloned above (always NULL here?).
  238          * pcb2->pcb_gs:        cloned above.
  239          * pcb2->pcb_ext:       cleared below.
  240          */
  241 
  242         /*
  243          * XXX don't copy the i/o pages.  this should probably be fixed.
  244          */
  245         pcb2->pcb_ext = 0;
  246 
  247         /* Copy the LDT, if necessary. */
  248         mtx_lock_spin(&sched_lock);
  249         if (mdp2->md_ldt != 0) {
  250                 if (flags & RFMEM) {
  251                         mdp2->md_ldt->ldt_refcnt++;
  252                 } else {
  253                         mdp2->md_ldt = user_ldt_alloc(mdp2,
  254                             mdp2->md_ldt->ldt_len);
  255                         if (mdp2->md_ldt == NULL)
  256                                 panic("could not copy LDT");
  257                 }
  258         }
  259         mtx_unlock_spin(&sched_lock);
  260 
  261         /*
  262          * Now, cpu_switch() can schedule the new process.
  263          * pcb_esp is loaded pointing to the cpu_switch() stack frame
  264          * containing the return address when exiting cpu_switch.
  265          * This will normally be to fork_trampoline(), which will have
  266          * %ebx loaded with the new proc's pointer.  fork_trampoline()
  267          * will set up a stack to call fork_return(p, frame); to complete
  268          * the return to user-mode.
  269          */
  270 }
  271 
  272 /*
  273  * Intercept the return address from a freshly forked process that has NOT
  274  * been scheduled yet.
  275  *
  276  * This is needed to make kernel threads stay in kernel mode.
  277  */
  278 void
  279 cpu_set_fork_handler(td, func, arg)
  280         struct thread *td;
  281         void (*func)(void *);
  282         void *arg;
  283 {
  284         /*
  285          * Note that the trap frame follows the args, so the function
  286          * is really called like this:  func(arg, frame);
  287          */
  288         td->td_pcb->pcb_esi = (int) func;       /* function */
  289         td->td_pcb->pcb_ebx = (int) arg;        /* first arg */
  290 }
  291 
  292 void
  293 cpu_exit(struct thread *td)
  294 {
  295         struct mdproc *mdp;
  296         struct pcb *pcb = td->td_pcb; 
  297 
  298 
  299         /* Reset pc->pcb_gs and %gs before possibly invalidating it. */
  300         mdp = &td->td_proc->p_md;
  301         if (mdp->md_ldt) {
  302                 td->td_pcb->pcb_gs = _udatasel;
  303                 load_gs(_udatasel);
  304                 user_ldt_free(td);
  305         }
  306         if (pcb->pcb_flags & PCB_DBREGS) {
  307                 /* disable all hardware breakpoints */
  308                 reset_dbregs();
  309                 pcb->pcb_flags &= ~PCB_DBREGS;
  310         }
  311 }
  312 
  313 void
  314 cpu_thread_exit(struct thread *td)
  315 {
  316         struct pcb *pcb = td->td_pcb; 
  317 #ifdef DEV_NPX
  318         if (td == PCPU_GET(fpcurthread))
  319                 npxdrop();
  320 #endif
  321         if (pcb->pcb_flags & PCB_DBREGS) {
  322                 /* disable all hardware breakpoints */
  323                 reset_dbregs();
  324                 pcb->pcb_flags &= ~PCB_DBREGS;
  325         }
  326 }
  327 
  328 void
  329 cpu_thread_clean(struct thread *td)
  330 {
  331         struct pcb *pcb;
  332 
  333         pcb = td->td_pcb; 
  334         if (pcb->pcb_ext != 0) {
  335                 /* XXXKSE  XXXSMP  not SMP SAFE.. what locks do we have? */
  336                 /* if (pcb->pcb_ext->ext_refcount-- == 1) ?? */
  337                 /*
  338                  * XXX do we need to move the TSS off the allocated pages
  339                  * before freeing them?  (not done here)
  340                  */
  341                 kmem_free(kernel_map, (vm_offset_t)pcb->pcb_ext,
  342                     ctob(IOPAGES + 1));
  343                 pcb->pcb_ext = 0;
  344         }
  345 }
  346 
  347 void
  348 cpu_thread_swapin(struct thread *td)
  349 {
  350 }
  351 
  352 void
  353 cpu_thread_swapout(struct thread *td)
  354 {
  355 }
  356 
  357 void
  358 cpu_thread_setup(struct thread *td)
  359 {
  360 
  361         td->td_pcb = (struct pcb *)(td->td_kstack +
  362             td->td_kstack_pages * PAGE_SIZE) - 1;
  363         td->td_frame = (struct trapframe *)((caddr_t)td->td_pcb - 16) - 1;
  364         td->td_pcb->pcb_ext = NULL; 
  365 }
  366 
  367 /*
  368  * Initialize machine state (pcb and trap frame) for a new thread about to
  369  * upcall. Pu t enough state in the new thread's PCB to get it to go back 
  370  * userret(), where we can intercept it again to set the return (upcall)
  371  * Address and stack, along with those from upcals that are from other sources
  372  * such as those generated in thread_userret() itself.
  373  */
  374 void
  375 cpu_set_upcall(struct thread *td, struct thread *td0)
  376 {
  377         struct pcb *pcb2;
  378 
  379         /* Point the pcb to the top of the stack. */
  380         pcb2 = td->td_pcb;
  381 
  382         /*
  383          * Copy the upcall pcb.  This loads kernel regs.
  384          * Those not loaded individually below get their default
  385          * values here.
  386          *
  387          * XXXKSE It might be a good idea to simply skip this as
  388          * the values of the other registers may be unimportant.
  389          * This would remove any requirement for knowing the KSE
  390          * at this time (see the matching comment below for
  391          * more analysis) (need a good safe default).
  392          */
  393         bcopy(td0->td_pcb, pcb2, sizeof(*pcb2));
  394         pcb2->pcb_flags &= ~(PCB_NPXTRAP|PCB_NPXINITDONE);
  395 
  396         /*
  397          * Create a new fresh stack for the new thread.
  398          * The -16 is so we can expand the trapframe if we go to vm86.
  399          * Don't forget to set this stack value into whatever supplies
  400          * the address for the fault handlers.
  401          * The contexts are filled in at the time we actually DO the
  402          * upcall as only then do we know which KSE we got.
  403          */
  404         bcopy(td0->td_frame, td->td_frame, sizeof(struct trapframe));
  405 
  406         /*
  407          * Set registers for trampoline to user mode.  Leave space for the
  408          * return address on stack.  These are the kernel mode register values.
  409          */
  410 #ifdef PAE
  411         pcb2->pcb_cr3 = vtophys(vmspace_pmap(td->td_proc->p_vmspace)->pm_pdpt);
  412 #else
  413         pcb2->pcb_cr3 = vtophys(vmspace_pmap(td->td_proc->p_vmspace)->pm_pdir);
  414 #endif
  415         pcb2->pcb_edi = 0;
  416         pcb2->pcb_esi = (int)fork_return;                   /* trampoline arg */
  417         pcb2->pcb_ebp = 0;
  418         pcb2->pcb_esp = (int)td->td_frame - sizeof(void *); /* trampoline arg */
  419         pcb2->pcb_ebx = (int)td;                            /* trampoline arg */
  420         pcb2->pcb_eip = (int)fork_trampoline;
  421         pcb2->pcb_psl &= ~(PSL_I);      /* interrupts must be disabled */
  422         pcb2->pcb_gs = rgs();
  423         /*
  424          * If we didn't copy the pcb, we'd need to do the following registers:
  425          * pcb2->pcb_dr*:       cloned above.
  426          * pcb2->pcb_savefpu:   cloned above.
  427          * pcb2->pcb_flags:     cloned above.
  428          * pcb2->pcb_onfault:   cloned above (always NULL here?).
  429          * pcb2->pcb_gs:        cloned above.  XXXKSE ???
  430          * pcb2->pcb_ext:       cleared below.
  431          */
  432          pcb2->pcb_ext = NULL;
  433 }
  434 
  435 /*
  436  * Set that machine state for performing an upcall that has to
  437  * be done in thread_userret() so that those upcalls generated
  438  * in thread_userret() itself can be done as well.
  439  */
  440 void
  441 cpu_set_upcall_kse(struct thread *td, struct kse_upcall *ku)
  442 {
  443 
  444         /* 
  445          * Do any extra cleaning that needs to be done.
  446          * The thread may have optional components
  447          * that are not present in a fresh thread.
  448          * This may be a recycled thread so make it look
  449          * as though it's newly allocated.
  450          */
  451         cpu_thread_clean(td);
  452 
  453         /*
  454          * Set the trap frame to point at the beginning of the uts
  455          * function.
  456          */
  457         td->td_frame->tf_ebp = 0; 
  458         td->td_frame->tf_esp =
  459             (int)ku->ku_stack.ss_sp + ku->ku_stack.ss_size - 16;
  460         td->td_frame->tf_eip = (int)ku->ku_func;
  461 
  462         /*
  463          * Pass the address of the mailbox for this kse to the uts
  464          * function as a parameter on the stack.
  465          */
  466         suword((void *)(td->td_frame->tf_esp + sizeof(void *)),
  467             (int)ku->ku_mailbox);
  468 }
  469 
  470 /*
  471  * Convert kernel VA to physical address
  472  */
  473 vm_paddr_t
  474 kvtop(void *addr)
  475 {
  476         vm_paddr_t pa;
  477 
  478         pa = pmap_kextract((vm_offset_t)addr);
  479         if (pa == 0)
  480                 panic("kvtop: zero page frame");
  481         return (pa);
  482 }
  483 
  484 /*
  485  * Force reset the processor by invalidating the entire address space!
  486  */
  487 
  488 #ifdef SMP
  489 static void
  490 cpu_reset_proxy()
  491 {
  492 
  493         cpu_reset_proxy_active = 1;
  494         while (cpu_reset_proxy_active == 1)
  495                 ;        /* Wait for other cpu to see that we've started */
  496         stop_cpus((1<<cpu_reset_proxyid));
  497         printf("cpu_reset_proxy: Stopped CPU %d\n", cpu_reset_proxyid);
  498         DELAY(1000000);
  499         cpu_reset_real();
  500 }
  501 #endif
  502 
  503 void
  504 cpu_reset()
  505 {
  506 #ifdef SMP
  507         if (smp_active == 0) {
  508                 cpu_reset_real();
  509                 /* NOTREACHED */
  510         } else {
  511 
  512                 u_int map;
  513                 int cnt;
  514                 printf("cpu_reset called on cpu#%d\n", PCPU_GET(cpuid));
  515 
  516                 map = PCPU_GET(other_cpus) & ~ stopped_cpus;
  517 
  518                 if (map != 0) {
  519                         printf("cpu_reset: Stopping other CPUs\n");
  520                         stop_cpus(map);         /* Stop all other CPUs */
  521                 }
  522 
  523                 if (PCPU_GET(cpuid) == 0) {
  524                         DELAY(1000000);
  525                         cpu_reset_real();
  526                         /* NOTREACHED */
  527                 } else {
  528                         /* We are not BSP (CPU #0) */
  529 
  530                         cpu_reset_proxyid = PCPU_GET(cpuid);
  531                         cpustop_restartfunc = cpu_reset_proxy;
  532                         cpu_reset_proxy_active = 0;
  533                         printf("cpu_reset: Restarting BSP\n");
  534                         started_cpus = (1<<0);          /* Restart CPU #0 */
  535 
  536                         cnt = 0;
  537                         while (cpu_reset_proxy_active == 0 && cnt < 10000000)
  538                                 cnt++;  /* Wait for BSP to announce restart */
  539                         if (cpu_reset_proxy_active == 0)
  540                                 printf("cpu_reset: Failed to restart BSP\n");
  541                         enable_intr();
  542                         cpu_reset_proxy_active = 2;
  543 
  544                         while (1);
  545                         /* NOTREACHED */
  546                 }
  547         }
  548 #else
  549         cpu_reset_real();
  550 #endif
  551 }
  552 
  553 static void
  554 cpu_reset_real()
  555 {
  556 
  557 #ifdef CPU_ELAN
  558         if (elan_mmcr != NULL)
  559                 elan_mmcr->RESCFG = 1;
  560 #endif
  561 
  562         if (cpu == CPU_GEODE1100) {
  563                 /* Attempt Geode's own reset */
  564                 outl(0xcf8, 0x80009044ul);
  565                 outl(0xcfc, 0xf);
  566         }
  567 
  568 #ifdef PC98
  569         /*
  570          * Attempt to do a CPU reset via CPU reset port.
  571          */
  572         disable_intr();
  573         if ((inb(0x35) & 0xa0) != 0xa0) {
  574                 outb(0x37, 0x0f);               /* SHUT0 = 0. */
  575                 outb(0x37, 0x0b);               /* SHUT1 = 0. */
  576         }
  577         outb(0xf0, 0x00);               /* Reset. */
  578 #else
  579         /*
  580          * Attempt to do a CPU reset via the keyboard controller,
  581          * do not turn of the GateA20, as any machine that fails
  582          * to do the reset here would then end up in no man's land.
  583          */
  584 
  585 #if !defined(BROKEN_KEYBOARD_RESET)
  586         outb(IO_KBD + 4, 0xFE);
  587         DELAY(500000);  /* wait 0.5 sec to see if that did it */
  588         printf("Keyboard reset did not work, attempting CPU shutdown\n");
  589         DELAY(1000000); /* wait 1 sec for printf to complete */
  590 #endif
  591 #endif /* PC98 */
  592         /* force a shutdown by unmapping entire address space ! */
  593         bzero((caddr_t)PTD, NBPTD);
  594 
  595         /* "good night, sweet prince .... <THUNK!>" */
  596         invltlb();
  597         /* NOTREACHED */
  598         while(1);
  599 }
  600 
  601 /*
  602  * Allocate a pool of sf_bufs (sendfile(2) or "super-fast" if you prefer. :-))
  603  */
  604 static void
  605 sf_buf_init(void *arg)
  606 {
  607         struct sf_buf *sf_bufs;
  608         vm_offset_t sf_base;
  609         int i;
  610 
  611         nsfbufs = NSFBUFS;
  612         TUNABLE_INT_FETCH("kern.ipc.nsfbufs", &nsfbufs);
  613 
  614         sf_buf_active = hashinit(nsfbufs, M_TEMP, &sf_buf_hashmask);
  615         TAILQ_INIT(&sf_buf_freelist);
  616         sf_base = kmem_alloc_nofault(kernel_map, nsfbufs * PAGE_SIZE);
  617         sf_bufs = malloc(nsfbufs * sizeof(struct sf_buf), M_TEMP,
  618             M_NOWAIT | M_ZERO);
  619         for (i = 0; i < nsfbufs; i++) {
  620                 sf_bufs[i].kva = sf_base + i * PAGE_SIZE;
  621                 TAILQ_INSERT_TAIL(&sf_buf_freelist, &sf_bufs[i], free_entry);
  622         }
  623         sf_buf_alloc_want = 0;
  624         mtx_init(&sf_buf_lock, "sf_buf", NULL, MTX_DEF);
  625 }
  626 
  627 /*
  628  * Get an sf_buf from the freelist. Will block if none are available.
  629  */
  630 struct sf_buf *
  631 sf_buf_alloc(struct vm_page *m, int flags)
  632 {
  633         pt_entry_t opte, *ptep;
  634         struct sf_head *hash_list;
  635         struct sf_buf *sf;
  636 #ifdef SMP
  637         cpumask_t cpumask, other_cpus;
  638 #endif
  639         int error;
  640 
  641         KASSERT(curthread->td_pinned > 0 || (flags & SFB_CPUPRIVATE) == 0,
  642             ("sf_buf_alloc(SFB_CPUPRIVATE): curthread not pinned"));
  643         hash_list = &sf_buf_active[SF_BUF_HASH(m)];
  644         mtx_lock(&sf_buf_lock);
  645         LIST_FOREACH(sf, hash_list, list_entry) {
  646                 if (sf->m == m) {
  647                         sf->ref_count++;
  648                         if (sf->ref_count == 1) {
  649                                 TAILQ_REMOVE(&sf_buf_freelist, sf, free_entry);
  650                                 nsfbufsused++;
  651                                 nsfbufspeak = imax(nsfbufspeak, nsfbufsused);
  652                         }
  653 #ifdef SMP
  654                         goto shootdown; 
  655 #else
  656                         goto done;
  657 #endif
  658                 }
  659         }
  660         while ((sf = TAILQ_FIRST(&sf_buf_freelist)) == NULL) {
  661                 if (flags & SFB_NOWAIT)
  662                         goto done;
  663                 sf_buf_alloc_want++;
  664                 mbstat.sf_allocwait++;
  665                 error = msleep(&sf_buf_freelist, &sf_buf_lock,
  666                     (flags & SFB_CATCH) ? PCATCH | PVM : PVM, "sfbufa", 0);
  667                 sf_buf_alloc_want--;
  668 
  669                 /*
  670                  * If we got a signal, don't risk going back to sleep. 
  671                  */
  672                 if (error)
  673                         goto done;
  674         }
  675         TAILQ_REMOVE(&sf_buf_freelist, sf, free_entry);
  676         if (sf->m != NULL)
  677                 LIST_REMOVE(sf, list_entry);
  678         LIST_INSERT_HEAD(hash_list, sf, list_entry);
  679         sf->ref_count = 1;
  680         sf->m = m;
  681         nsfbufsused++;
  682         nsfbufspeak = imax(nsfbufspeak, nsfbufsused);
  683 
  684         /*
  685          * Update the sf_buf's virtual-to-physical mapping, flushing the
  686          * virtual address from the TLB.  Since the reference count for 
  687          * the sf_buf's old mapping was zero, that mapping is not 
  688          * currently in use.  Consequently, there is no need to exchange 
  689          * the old and new PTEs atomically, even under PAE.
  690          */
  691         ptep = vtopte(sf->kva);
  692         opte = *ptep;
  693         *ptep = VM_PAGE_TO_PHYS(m) | pgeflag | PG_RW | PG_V;
  694 
  695         /*
  696          * Avoid unnecessary TLB invalidations: If the sf_buf's old
  697          * virtual-to-physical mapping was not used, then any processor
  698          * that has invalidated the sf_buf's virtual address from its TLB
  699          * since the last used mapping need not invalidate again.
  700          */
  701 #ifdef SMP
  702         if ((opte & (PG_V | PG_A)) ==  (PG_V | PG_A))
  703                 sf->cpumask = 0;
  704 shootdown:
  705         sched_pin();
  706         cpumask = PCPU_GET(cpumask);
  707         if ((sf->cpumask & cpumask) == 0) {
  708                 sf->cpumask |= cpumask;
  709                 invlpg(sf->kva);
  710         }
  711         if ((flags & SFB_CPUPRIVATE) == 0) {
  712                 other_cpus = PCPU_GET(other_cpus) & ~sf->cpumask;
  713                 if (other_cpus != 0) {
  714                         sf->cpumask |= other_cpus;
  715                         mtx_lock_spin(&smp_ipi_mtx);
  716                         smp_masked_invlpg(other_cpus, sf->kva);
  717                         mtx_unlock_spin(&smp_ipi_mtx);
  718                 }
  719         }
  720         sched_unpin();  
  721 #else
  722         if ((opte & (PG_V | PG_A)) ==  (PG_V | PG_A))
  723                 pmap_invalidate_page(kernel_pmap, sf->kva);
  724 #endif
  725 done:
  726         mtx_unlock(&sf_buf_lock);
  727         return (sf);
  728 }
  729 
  730 /*
  731  * Remove a reference from the given sf_buf, adding it to the free
  732  * list when its reference count reaches zero.  A freed sf_buf still,
  733  * however, retains its virtual-to-physical mapping until it is
  734  * recycled or reactivated by sf_buf_alloc(9).
  735  */
  736 void
  737 sf_buf_free(struct sf_buf *sf)
  738 {
  739 
  740         mtx_lock(&sf_buf_lock);
  741         sf->ref_count--;
  742         if (sf->ref_count == 0) {
  743                 TAILQ_INSERT_TAIL(&sf_buf_freelist, sf, free_entry);
  744                 nsfbufsused--;
  745                 if (sf_buf_alloc_want > 0)
  746                         wakeup_one(&sf_buf_freelist);
  747         }
  748         mtx_unlock(&sf_buf_lock);
  749 }
  750 
  751 /*
  752  * Software interrupt handler for queued VM system processing.
  753  */   
  754 void  
  755 swi_vm(void *dummy) 
  756 {     
  757         if (busdma_swi_pending != 0)
  758                 busdma_swi();
  759 }
  760 
  761 /*
  762  * Tell whether this address is in some physical memory region.
  763  * Currently used by the kernel coredump code in order to avoid
  764  * dumping the ``ISA memory hole'' which could cause indefinite hangs,
  765  * or other unpredictable behaviour.
  766  */
  767 
  768 int
  769 is_physical_memory(vm_paddr_t addr)
  770 {
  771 
  772 #ifdef DEV_ISA
  773         /* The ISA ``memory hole''. */
  774         if (addr >= 0xa0000 && addr < 0x100000)
  775                 return 0;
  776 #endif
  777 
  778         /*
  779          * stuff other tests for known memory-mapped devices (PCI?)
  780          * here
  781          */
  782 
  783         return 1;
  784 }

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