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: stable/10/sys/i386/i386/vm_machdep.c 332759 2018-04-19 06:20:53Z avg $");
   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 #if !defined(CPU_DISABLE_SSE) && defined(I686_CPU)
  110 #define CPU_ENABLE_SSE
  111 #endif
  112 
  113 _Static_assert(OFFSETOF_CURTHREAD == offsetof(struct pcpu, pc_curthread),
  114     "OFFSETOF_CURTHREAD does not correspond with offset of pc_curthread.");
  115 _Static_assert(OFFSETOF_CURPCB == offsetof(struct pcpu, pc_curpcb),
  116     "OFFSETOF_CURPCB does not correspond with offset of pc_curpcb.");
  117 
  118 static void     cpu_reset_real(void);
  119 #ifdef SMP
  120 static void     cpu_reset_proxy(void);
  121 static u_int    cpu_reset_proxyid;
  122 static volatile u_int   cpu_reset_proxy_active;
  123 #endif
  124 
  125 static int nsfbufs;
  126 static int nsfbufspeak;
  127 static int nsfbufsused;
  128 
  129 SYSCTL_INT(_kern_ipc, OID_AUTO, nsfbufs, CTLFLAG_RDTUN, &nsfbufs, 0,
  130     "Maximum number of sendfile(2) sf_bufs available");
  131 SYSCTL_INT(_kern_ipc, OID_AUTO, nsfbufspeak, CTLFLAG_RD, &nsfbufspeak, 0,
  132     "Number of sendfile(2) sf_bufs at peak usage");
  133 SYSCTL_INT(_kern_ipc, OID_AUTO, nsfbufsused, CTLFLAG_RD, &nsfbufsused, 0,
  134     "Number of sendfile(2) sf_bufs in use");
  135 
  136 static void     sf_buf_init(void *arg);
  137 SYSINIT(sock_sf, SI_SUB_MBUF, SI_ORDER_ANY, sf_buf_init, NULL);
  138 
  139 LIST_HEAD(sf_head, sf_buf);
  140 
  141 /*
  142  * A hash table of active sendfile(2) buffers
  143  */
  144 static struct sf_head *sf_buf_active;
  145 static u_long sf_buf_hashmask;
  146 
  147 #define SF_BUF_HASH(m)  (((m) - vm_page_array) & sf_buf_hashmask)
  148 
  149 static TAILQ_HEAD(, sf_buf) sf_buf_freelist;
  150 static u_int    sf_buf_alloc_want;
  151 
  152 /*
  153  * A lock used to synchronize access to the hash table and free list
  154  */
  155 static struct mtx sf_buf_lock;
  156 
  157 union savefpu *
  158 get_pcb_user_save_td(struct thread *td)
  159 {
  160         vm_offset_t p;
  161         p = td->td_kstack + td->td_kstack_pages * PAGE_SIZE -
  162             roundup2(cpu_max_ext_state_size, XSAVE_AREA_ALIGN);
  163         KASSERT((p % XSAVE_AREA_ALIGN) == 0, ("Unaligned pcb_user_save area"));
  164         return ((union savefpu *)p);
  165 }
  166 
  167 union savefpu *
  168 get_pcb_user_save_pcb(struct pcb *pcb)
  169 {
  170         vm_offset_t p;
  171 
  172         p = (vm_offset_t)(pcb + 1);
  173         return ((union savefpu *)p);
  174 }
  175 
  176 struct pcb *
  177 get_pcb_td(struct thread *td)
  178 {
  179         vm_offset_t p;
  180 
  181         p = td->td_kstack + td->td_kstack_pages * PAGE_SIZE -
  182             roundup2(cpu_max_ext_state_size, XSAVE_AREA_ALIGN) -
  183             sizeof(struct pcb);
  184         return ((struct pcb *)p);
  185 }
  186 
  187 void *
  188 alloc_fpusave(int flags)
  189 {
  190         void *res;
  191 #ifdef CPU_ENABLE_SSE
  192         struct savefpu_ymm *sf;
  193 #endif
  194 
  195         res = malloc(cpu_max_ext_state_size, M_DEVBUF, flags);
  196 #ifdef CPU_ENABLE_SSE
  197         if (use_xsave) {
  198                 sf = (struct savefpu_ymm *)res;
  199                 bzero(&sf->sv_xstate.sx_hd, sizeof(sf->sv_xstate.sx_hd));
  200                 sf->sv_xstate.sx_hd.xstate_bv = xsave_mask;
  201         }
  202 #endif
  203         return (res);
  204 }
  205 
  206 /*
  207  * Finish a fork operation, with process p2 nearly set up.
  208  * Copy and update the pcb, set up the stack so that the child
  209  * ready to run and return to user mode.
  210  */
  211 void
  212 cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
  213 {
  214         register struct proc *p1;
  215         struct pcb *pcb2;
  216         struct mdproc *mdp2;
  217 
  218         p1 = td1->td_proc;
  219         if ((flags & RFPROC) == 0) {
  220                 if ((flags & RFMEM) == 0) {
  221                         /* unshare user LDT */
  222                         struct mdproc *mdp1 = &p1->p_md;
  223                         struct proc_ldt *pldt, *pldt1;
  224 
  225                         mtx_lock_spin(&dt_lock);
  226                         if ((pldt1 = mdp1->md_ldt) != NULL &&
  227                             pldt1->ldt_refcnt > 1) {
  228                                 pldt = user_ldt_alloc(mdp1, pldt1->ldt_len);
  229                                 if (pldt == NULL)
  230                                         panic("could not copy LDT");
  231                                 mdp1->md_ldt = pldt;
  232                                 set_user_ldt(mdp1);
  233                                 user_ldt_deref(pldt1);
  234                         } else
  235                                 mtx_unlock_spin(&dt_lock);
  236                 }
  237                 return;
  238         }
  239 
  240         /* Ensure that td1's pcb is up to date. */
  241         if (td1 == curthread)
  242                 td1->td_pcb->pcb_gs = rgs();
  243 #ifdef DEV_NPX
  244         critical_enter();
  245         if (PCPU_GET(fpcurthread) == td1)
  246                 npxsave(td1->td_pcb->pcb_save);
  247         critical_exit();
  248 #endif
  249 
  250         /* Point the pcb to the top of the stack */
  251         pcb2 = get_pcb_td(td2);
  252         td2->td_pcb = pcb2;
  253 
  254         /* Copy td1's pcb */
  255         bcopy(td1->td_pcb, pcb2, sizeof(*pcb2));
  256 
  257         /* Properly initialize pcb_save */
  258         pcb2->pcb_save = get_pcb_user_save_pcb(pcb2);
  259         bcopy(get_pcb_user_save_td(td1), get_pcb_user_save_pcb(pcb2),
  260             cpu_max_ext_state_size);
  261 
  262         /* Point mdproc and then copy over td1's contents */
  263         mdp2 = &p2->p_md;
  264         bcopy(&p1->p_md, mdp2, sizeof(*mdp2));
  265 
  266         /*
  267          * Create a new fresh stack for the new process.
  268          * Copy the trap frame for the return to user mode as if from a
  269          * syscall.  This copies most of the user mode register values.
  270          * The -16 is so we can expand the trapframe if we go to vm86.
  271          */
  272         td2->td_frame = (struct trapframe *)((caddr_t)td2->td_pcb - 16) - 1;
  273         bcopy(td1->td_frame, td2->td_frame, sizeof(struct trapframe));
  274 
  275         td2->td_frame->tf_eax = 0;              /* Child returns zero */
  276         td2->td_frame->tf_eflags &= ~PSL_C;     /* success */
  277         td2->td_frame->tf_edx = 1;
  278 
  279         /*
  280          * If the parent process has the trap bit set (i.e. a debugger had
  281          * single stepped the process to the system call), we need to clear
  282          * the trap flag from the new frame unless the debugger had set PF_FORK
  283          * on the parent.  Otherwise, the child will receive a (likely
  284          * unexpected) SIGTRAP when it executes the first instruction after
  285          * returning  to userland.
  286          */
  287         if ((p1->p_pfsflags & PF_FORK) == 0)
  288                 td2->td_frame->tf_eflags &= ~PSL_T;
  289 
  290         /*
  291          * Set registers for trampoline to user mode.  Leave space for the
  292          * return address on stack.  These are the kernel mode register values.
  293          */
  294 #if defined(PAE) || defined(PAE_TABLES)
  295         pcb2->pcb_cr3 = vtophys(vmspace_pmap(p2->p_vmspace)->pm_pdpt);
  296 #else
  297         pcb2->pcb_cr3 = vtophys(vmspace_pmap(p2->p_vmspace)->pm_pdir);
  298 #endif
  299         pcb2->pcb_edi = 0;
  300         pcb2->pcb_esi = (int)fork_return;       /* fork_trampoline argument */
  301         pcb2->pcb_ebp = 0;
  302         pcb2->pcb_esp = (int)td2->td_frame - sizeof(void *);
  303         pcb2->pcb_ebx = (int)td2;               /* fork_trampoline argument */
  304         pcb2->pcb_eip = (int)fork_trampoline;
  305         pcb2->pcb_psl = PSL_KERNEL;             /* ints disabled */
  306         /*-
  307          * pcb2->pcb_dr*:       cloned above.
  308          * pcb2->pcb_savefpu:   cloned above.
  309          * pcb2->pcb_flags:     cloned above.
  310          * pcb2->pcb_onfault:   cloned above (always NULL here?).
  311          * pcb2->pcb_gs:        cloned above.
  312          * pcb2->pcb_ext:       cleared below.
  313          */
  314 
  315         /*
  316          * XXX don't copy the i/o pages.  this should probably be fixed.
  317          */
  318         pcb2->pcb_ext = 0;
  319 
  320         /* Copy the LDT, if necessary. */
  321         mtx_lock_spin(&dt_lock);
  322         if (mdp2->md_ldt != NULL) {
  323                 if (flags & RFMEM) {
  324                         mdp2->md_ldt->ldt_refcnt++;
  325                 } else {
  326                         mdp2->md_ldt = user_ldt_alloc(mdp2,
  327                             mdp2->md_ldt->ldt_len);
  328                         if (mdp2->md_ldt == NULL)
  329                                 panic("could not copy LDT");
  330                 }
  331         }
  332         mtx_unlock_spin(&dt_lock);
  333 
  334         /* Setup to release spin count in fork_exit(). */
  335         td2->td_md.md_spinlock_count = 1;
  336         /*
  337          * XXX XEN need to check on PSL_USER is handled
  338          */
  339         td2->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
  340         /*
  341          * Now, cpu_switch() can schedule the new process.
  342          * pcb_esp is loaded pointing to the cpu_switch() stack frame
  343          * containing the return address when exiting cpu_switch.
  344          * This will normally be to fork_trampoline(), which will have
  345          * %ebx loaded with the new proc's pointer.  fork_trampoline()
  346          * will set up a stack to call fork_return(p, frame); to complete
  347          * the return to user-mode.
  348          */
  349 }
  350 
  351 /*
  352  * Intercept the return address from a freshly forked process that has NOT
  353  * been scheduled yet.
  354  *
  355  * This is needed to make kernel threads stay in kernel mode.
  356  */
  357 void
  358 cpu_set_fork_handler(td, func, arg)
  359         struct thread *td;
  360         void (*func)(void *);
  361         void *arg;
  362 {
  363         /*
  364          * Note that the trap frame follows the args, so the function
  365          * is really called like this:  func(arg, frame);
  366          */
  367         td->td_pcb->pcb_esi = (int) func;       /* function */
  368         td->td_pcb->pcb_ebx = (int) arg;        /* first arg */
  369 }
  370 
  371 void
  372 cpu_exit(struct thread *td)
  373 {
  374 
  375         /*
  376          * If this process has a custom LDT, release it.  Reset pc->pcb_gs
  377          * and %gs before we free it in case they refer to an LDT entry.
  378          */
  379         mtx_lock_spin(&dt_lock);
  380         if (td->td_proc->p_md.md_ldt) {
  381                 td->td_pcb->pcb_gs = _udatasel;
  382                 load_gs(_udatasel);
  383                 user_ldt_free(td);
  384         } else
  385                 mtx_unlock_spin(&dt_lock);
  386 }
  387 
  388 void
  389 cpu_thread_exit(struct thread *td)
  390 {
  391 
  392 #ifdef DEV_NPX
  393         critical_enter();
  394         if (td == PCPU_GET(fpcurthread))
  395                 npxdrop();
  396         critical_exit();
  397 #endif
  398 
  399         /* Disable any hardware breakpoints. */
  400         if (td->td_pcb->pcb_flags & PCB_DBREGS) {
  401                 reset_dbregs();
  402                 td->td_pcb->pcb_flags &= ~PCB_DBREGS;
  403         }
  404 }
  405 
  406 void
  407 cpu_thread_clean(struct thread *td)
  408 {
  409         struct pcb *pcb;
  410 
  411         pcb = td->td_pcb; 
  412         if (pcb->pcb_ext != NULL) {
  413                 /* if (pcb->pcb_ext->ext_refcount-- == 1) ?? */
  414                 /*
  415                  * XXX do we need to move the TSS off the allocated pages
  416                  * before freeing them?  (not done here)
  417                  */
  418                 kmem_free(kernel_arena, (vm_offset_t)pcb->pcb_ext,
  419                     ctob(IOPAGES + 1));
  420                 pcb->pcb_ext = NULL;
  421         }
  422 }
  423 
  424 void
  425 cpu_thread_swapin(struct thread *td)
  426 {
  427 }
  428 
  429 void
  430 cpu_thread_swapout(struct thread *td)
  431 {
  432 }
  433 
  434 void
  435 cpu_thread_alloc(struct thread *td)
  436 {
  437         struct pcb *pcb;
  438 #ifdef CPU_ENABLE_SSE
  439         struct xstate_hdr *xhdr;
  440 #endif
  441 
  442         td->td_pcb = pcb = get_pcb_td(td);
  443         td->td_frame = (struct trapframe *)((caddr_t)pcb - 16) - 1;
  444         pcb->pcb_ext = NULL; 
  445         pcb->pcb_save = get_pcb_user_save_pcb(pcb);
  446 #ifdef CPU_ENABLE_SSE
  447         if (use_xsave) {
  448                 xhdr = (struct xstate_hdr *)(pcb->pcb_save + 1);
  449                 bzero(xhdr, sizeof(*xhdr));
  450                 xhdr->xstate_bv = xsave_mask;
  451         }
  452 #endif
  453 }
  454 
  455 void
  456 cpu_thread_free(struct thread *td)
  457 {
  458 
  459         cpu_thread_clean(td);
  460 }
  461 
  462 void
  463 cpu_set_syscall_retval(struct thread *td, int error)
  464 {
  465 
  466         switch (error) {
  467         case 0:
  468                 td->td_frame->tf_eax = td->td_retval[0];
  469                 td->td_frame->tf_edx = td->td_retval[1];
  470                 td->td_frame->tf_eflags &= ~PSL_C;
  471                 break;
  472 
  473         case ERESTART:
  474                 /*
  475                  * Reconstruct pc, assuming lcall $X,y is 7 bytes, int
  476                  * 0x80 is 2 bytes. We saved this in tf_err.
  477                  */
  478                 td->td_frame->tf_eip -= td->td_frame->tf_err;
  479                 break;
  480 
  481         case EJUSTRETURN:
  482                 break;
  483 
  484         default:
  485                 td->td_frame->tf_eax = SV_ABI_ERRNO(td->td_proc, error);
  486                 td->td_frame->tf_eflags |= PSL_C;
  487                 break;
  488         }
  489 }
  490 
  491 /*
  492  * Initialize machine state (pcb and trap frame) for a new thread about to
  493  * upcall. Put enough state in the new thread's PCB to get it to go back 
  494  * userret(), where we can intercept it again to set the return (upcall)
  495  * Address and stack, along with those from upcals that are from other sources
  496  * such as those generated in thread_userret() itself.
  497  */
  498 void
  499 cpu_set_upcall(struct thread *td, struct thread *td0)
  500 {
  501         struct pcb *pcb2;
  502 
  503         /* Point the pcb to the top of the stack. */
  504         pcb2 = td->td_pcb;
  505 
  506         /*
  507          * Copy the upcall pcb.  This loads kernel regs.
  508          * Those not loaded individually below get their default
  509          * values here.
  510          */
  511         bcopy(td0->td_pcb, pcb2, sizeof(*pcb2));
  512         pcb2->pcb_flags &= ~(PCB_NPXINITDONE | PCB_NPXUSERINITDONE |
  513             PCB_KERNNPX);
  514         pcb2->pcb_save = get_pcb_user_save_pcb(pcb2);
  515         bcopy(get_pcb_user_save_td(td0), pcb2->pcb_save,
  516             cpu_max_ext_state_size);
  517 
  518         /*
  519          * Create a new fresh stack for the new thread.
  520          */
  521         bcopy(td0->td_frame, td->td_frame, sizeof(struct trapframe));
  522 
  523         /* If the current thread has the trap bit set (i.e. a debugger had
  524          * single stepped the process to the system call), we need to clear
  525          * the trap flag from the new frame. Otherwise, the new thread will
  526          * receive a (likely unexpected) SIGTRAP when it executes the first
  527          * instruction after returning to userland.
  528          */
  529         td->td_frame->tf_eflags &= ~PSL_T;
  530 
  531         /*
  532          * Set registers for trampoline to user mode.  Leave space for the
  533          * return address on stack.  These are the kernel mode register values.
  534          */
  535         pcb2->pcb_edi = 0;
  536         pcb2->pcb_esi = (int)fork_return;                   /* trampoline arg */
  537         pcb2->pcb_ebp = 0;
  538         pcb2->pcb_esp = (int)td->td_frame - sizeof(void *); /* trampoline arg */
  539         pcb2->pcb_ebx = (int)td;                            /* trampoline arg */
  540         pcb2->pcb_eip = (int)fork_trampoline;
  541         pcb2->pcb_psl &= ~(PSL_I);      /* interrupts must be disabled */
  542         pcb2->pcb_gs = rgs();
  543         /*
  544          * If we didn't copy the pcb, we'd need to do the following registers:
  545          * pcb2->pcb_cr3:       cloned above.
  546          * pcb2->pcb_dr*:       cloned above.
  547          * pcb2->pcb_savefpu:   cloned above.
  548          * pcb2->pcb_flags:     cloned above.
  549          * pcb2->pcb_onfault:   cloned above (always NULL here?).
  550          * pcb2->pcb_gs:        cloned above.
  551          * pcb2->pcb_ext:       cleared below.
  552          */
  553         pcb2->pcb_ext = NULL;
  554 
  555         /* Setup to release spin count in fork_exit(). */
  556         td->td_md.md_spinlock_count = 1;
  557         td->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
  558 }
  559 
  560 /*
  561  * Set that machine state for performing an upcall that has to
  562  * be done in thread_userret() so that those upcalls generated
  563  * in thread_userret() itself can be done as well.
  564  */
  565 void
  566 cpu_set_upcall_kse(struct thread *td, void (*entry)(void *), void *arg,
  567         stack_t *stack)
  568 {
  569 
  570         /* 
  571          * Do any extra cleaning that needs to be done.
  572          * The thread may have optional components
  573          * that are not present in a fresh thread.
  574          * This may be a recycled thread so make it look
  575          * as though it's newly allocated.
  576          */
  577         cpu_thread_clean(td);
  578 
  579         /*
  580          * Set the trap frame to point at the beginning of the uts
  581          * function.
  582          */
  583         td->td_frame->tf_ebp = 0; 
  584         td->td_frame->tf_esp =
  585             (((int)stack->ss_sp + stack->ss_size - 4) & ~0x0f) - 4;
  586         td->td_frame->tf_eip = (int)entry;
  587 
  588         /*
  589          * Pass the address of the mailbox for this kse to the uts
  590          * function as a parameter on the stack.
  591          */
  592         suword((void *)(td->td_frame->tf_esp + sizeof(void *)),
  593             (int)arg);
  594 }
  595 
  596 int
  597 cpu_set_user_tls(struct thread *td, void *tls_base)
  598 {
  599         struct segment_descriptor sd;
  600         uint32_t base;
  601 
  602         /*
  603          * Construct a descriptor and store it in the pcb for
  604          * the next context switch.  Also store it in the gdt
  605          * so that the load of tf_fs into %fs will activate it
  606          * at return to userland.
  607          */
  608         base = (uint32_t)tls_base;
  609         sd.sd_lobase = base & 0xffffff;
  610         sd.sd_hibase = (base >> 24) & 0xff;
  611         sd.sd_lolimit = 0xffff; /* 4GB limit, wraps around */
  612         sd.sd_hilimit = 0xf;
  613         sd.sd_type  = SDT_MEMRWA;
  614         sd.sd_dpl   = SEL_UPL;
  615         sd.sd_p     = 1;
  616         sd.sd_xx    = 0;
  617         sd.sd_def32 = 1;
  618         sd.sd_gran  = 1;
  619         critical_enter();
  620         /* set %gs */
  621         td->td_pcb->pcb_gsd = sd;
  622         if (td == curthread) {
  623                 PCPU_GET(fsgs_gdt)[1] = sd;
  624                 load_gs(GSEL(GUGS_SEL, SEL_UPL));
  625         }
  626         critical_exit();
  627         return (0);
  628 }
  629 
  630 /*
  631  * Convert kernel VA to physical address
  632  */
  633 vm_paddr_t
  634 kvtop(void *addr)
  635 {
  636         vm_paddr_t pa;
  637 
  638         pa = pmap_kextract((vm_offset_t)addr);
  639         if (pa == 0)
  640                 panic("kvtop: zero page frame");
  641         return (pa);
  642 }
  643 
  644 #ifdef SMP
  645 static void
  646 cpu_reset_proxy()
  647 {
  648 
  649         cpu_reset_proxy_active = 1;
  650         while (cpu_reset_proxy_active == 1)
  651                 ia32_pause(); /* Wait for other cpu to see that we've started */
  652 
  653         printf("cpu_reset_proxy: Stopped CPU %d\n", cpu_reset_proxyid);
  654         DELAY(1000000);
  655         cpu_reset_real();
  656 }
  657 #endif
  658 
  659 void
  660 cpu_reset()
  661 {
  662 #ifdef XBOX
  663         if (arch_i386_is_xbox) {
  664                 /* Kick the PIC16L, it can reboot the box */
  665                 pic16l_reboot();
  666                 for (;;);
  667         }
  668 #endif
  669 
  670 #ifdef SMP
  671         cpuset_t map;
  672         u_int cnt;
  673 
  674         if (smp_started) {
  675                 map = all_cpus;
  676                 CPU_CLR(PCPU_GET(cpuid), &map);
  677                 CPU_NAND(&map, &stopped_cpus);
  678                 if (!CPU_EMPTY(&map)) {
  679                         printf("cpu_reset: Stopping other CPUs\n");
  680                         stop_cpus(map);
  681                 }
  682 
  683                 if (PCPU_GET(cpuid) != 0) {
  684                         cpu_reset_proxyid = PCPU_GET(cpuid);
  685                         cpustop_restartfunc = cpu_reset_proxy;
  686                         cpu_reset_proxy_active = 0;
  687                         printf("cpu_reset: Restarting BSP\n");
  688 
  689                         /* Restart CPU #0. */
  690                         CPU_SETOF(0, &started_cpus);
  691                         wmb();
  692 
  693                         cnt = 0;
  694                         while (cpu_reset_proxy_active == 0 && cnt < 10000000) {
  695                                 ia32_pause();
  696                                 cnt++;  /* Wait for BSP to announce restart */
  697                         }
  698                         if (cpu_reset_proxy_active == 0) {
  699                                 printf("cpu_reset: Failed to restart BSP\n");
  700                         } else {
  701                                 cpu_reset_proxy_active = 2;
  702                                 while (1)
  703                                         ia32_pause();
  704                                 /* NOTREACHED */
  705                         }
  706                 }
  707 
  708                 DELAY(1000000);
  709         }
  710 #endif
  711         cpu_reset_real();
  712         /* NOTREACHED */
  713 }
  714 
  715 static void
  716 cpu_reset_real()
  717 {
  718         struct region_descriptor null_idt;
  719 #ifndef PC98
  720         int b;
  721 #endif
  722 
  723         disable_intr();
  724 #ifdef XEN
  725         if (smp_processor_id() == 0)
  726                 HYPERVISOR_shutdown(SHUTDOWN_reboot);
  727         else
  728                 HYPERVISOR_shutdown(SHUTDOWN_poweroff);
  729 #endif 
  730 #ifdef CPU_ELAN
  731         if (elan_mmcr != NULL)
  732                 elan_mmcr->RESCFG = 1;
  733 #endif
  734 
  735         if (cpu == CPU_GEODE1100) {
  736                 /* Attempt Geode's own reset */
  737                 outl(0xcf8, 0x80009044ul);
  738                 outl(0xcfc, 0xf);
  739         }
  740 
  741 #ifdef PC98
  742         /*
  743          * Attempt to do a CPU reset via CPU reset port.
  744          */
  745         if ((inb(0x35) & 0xa0) != 0xa0) {
  746                 outb(0x37, 0x0f);               /* SHUT0 = 0. */
  747                 outb(0x37, 0x0b);               /* SHUT1 = 0. */
  748         }
  749         outb(0xf0, 0x00);               /* Reset. */
  750 #else
  751 #if !defined(BROKEN_KEYBOARD_RESET)
  752         /*
  753          * Attempt to do a CPU reset via the keyboard controller,
  754          * do not turn off GateA20, as any machine that fails
  755          * to do the reset here would then end up in no man's land.
  756          */
  757         outb(IO_KBD + 4, 0xFE);
  758         DELAY(500000);  /* wait 0.5 sec to see if that did it */
  759 #endif
  760 
  761         /*
  762          * Attempt to force a reset via the Reset Control register at
  763          * I/O port 0xcf9.  Bit 2 forces a system reset when it
  764          * transitions from 0 to 1.  Bit 1 selects the type of reset
  765          * to attempt: 0 selects a "soft" reset, and 1 selects a
  766          * "hard" reset.  We try a "hard" reset.  The first write sets
  767          * bit 1 to select a "hard" reset and clears bit 2.  The
  768          * second write forces a 0 -> 1 transition in bit 2 to trigger
  769          * a reset.
  770          */
  771         outb(0xcf9, 0x2);
  772         outb(0xcf9, 0x6);
  773         DELAY(500000);  /* wait 0.5 sec to see if that did it */
  774 
  775         /*
  776          * Attempt to force a reset via the Fast A20 and Init register
  777          * at I/O port 0x92.  Bit 1 serves as an alternate A20 gate.
  778          * Bit 0 asserts INIT# when set to 1.  We are careful to only
  779          * preserve bit 1 while setting bit 0.  We also must clear bit
  780          * 0 before setting it if it isn't already clear.
  781          */
  782         b = inb(0x92);
  783         if (b != 0xff) {
  784                 if ((b & 0x1) != 0)
  785                         outb(0x92, b & 0xfe);
  786                 outb(0x92, b | 0x1);
  787                 DELAY(500000);  /* wait 0.5 sec to see if that did it */
  788         }
  789 #endif /* PC98 */
  790 
  791         printf("No known reset method worked, attempting CPU shutdown\n");
  792         DELAY(1000000); /* wait 1 sec for printf to complete */
  793 
  794         /* Wipe the IDT. */
  795         null_idt.rd_limit = 0;
  796         null_idt.rd_base = 0;
  797         lidt(&null_idt);
  798 
  799         /* "good night, sweet prince .... <THUNK!>" */
  800         breakpoint();
  801 
  802         /* NOTREACHED */
  803         while(1);
  804 }
  805 
  806 /*
  807  * Allocate a pool of sf_bufs (sendfile(2) or "super-fast" if you prefer. :-))
  808  */
  809 static void
  810 sf_buf_init(void *arg)
  811 {
  812         struct sf_buf *sf_bufs;
  813         vm_offset_t sf_base;
  814         int i;
  815 
  816         nsfbufs = NSFBUFS;
  817         TUNABLE_INT_FETCH("kern.ipc.nsfbufs", &nsfbufs);
  818 
  819         sf_buf_active = hashinit(nsfbufs, M_TEMP, &sf_buf_hashmask);
  820         TAILQ_INIT(&sf_buf_freelist);
  821         sf_base = kva_alloc(nsfbufs * PAGE_SIZE);
  822         sf_bufs = malloc(nsfbufs * sizeof(struct sf_buf), M_TEMP,
  823             M_NOWAIT | M_ZERO);
  824         for (i = 0; i < nsfbufs; i++) {
  825                 sf_bufs[i].kva = sf_base + i * PAGE_SIZE;
  826                 TAILQ_INSERT_TAIL(&sf_buf_freelist, &sf_bufs[i], free_entry);
  827         }
  828         sf_buf_alloc_want = 0;
  829         mtx_init(&sf_buf_lock, "sf_buf", NULL, MTX_DEF);
  830 }
  831 
  832 /*
  833  * Invalidate the cache lines that may belong to the page, if
  834  * (possibly old) mapping of the page by sf buffer exists.  Returns
  835  * TRUE when mapping was found and cache invalidated.
  836  */
  837 boolean_t
  838 sf_buf_invalidate_cache(vm_page_t m)
  839 {
  840         struct sf_head *hash_list;
  841         struct sf_buf *sf;
  842         boolean_t ret;
  843 
  844         hash_list = &sf_buf_active[SF_BUF_HASH(m)];
  845         ret = FALSE;
  846         mtx_lock(&sf_buf_lock);
  847         LIST_FOREACH(sf, hash_list, list_entry) {
  848                 if (sf->m == m) {
  849                         /*
  850                          * Use pmap_qenter to update the pte for
  851                          * existing mapping, in particular, the PAT
  852                          * settings are recalculated.
  853                          */
  854                         pmap_qenter(sf->kva, &m, 1);
  855                         pmap_invalidate_cache_range(sf->kva, sf->kva +
  856                             PAGE_SIZE, FALSE);
  857                         ret = TRUE;
  858                         break;
  859                 }
  860         }
  861         mtx_unlock(&sf_buf_lock);
  862         return (ret);
  863 }
  864 
  865 /*
  866  * Get an sf_buf from the freelist.  May block if none are available.
  867  */
  868 struct sf_buf *
  869 sf_buf_alloc(struct vm_page *m, int flags)
  870 {
  871         pt_entry_t opte, *ptep;
  872         struct sf_head *hash_list;
  873         struct sf_buf *sf;
  874 #ifdef SMP
  875         cpuset_t other_cpus;
  876         u_int cpuid;
  877 #endif
  878         int error;
  879 
  880         KASSERT(curthread->td_pinned > 0 || (flags & SFB_CPUPRIVATE) == 0,
  881             ("sf_buf_alloc(SFB_CPUPRIVATE): curthread not pinned"));
  882         hash_list = &sf_buf_active[SF_BUF_HASH(m)];
  883         mtx_lock(&sf_buf_lock);
  884         LIST_FOREACH(sf, hash_list, list_entry) {
  885                 if (sf->m == m) {
  886                         sf->ref_count++;
  887                         if (sf->ref_count == 1) {
  888                                 TAILQ_REMOVE(&sf_buf_freelist, sf, free_entry);
  889                                 nsfbufsused++;
  890                                 nsfbufspeak = imax(nsfbufspeak, nsfbufsused);
  891                         }
  892 #ifdef SMP
  893                         goto shootdown; 
  894 #else
  895                         goto done;
  896 #endif
  897                 }
  898         }
  899         while ((sf = TAILQ_FIRST(&sf_buf_freelist)) == NULL) {
  900                 if (flags & SFB_NOWAIT)
  901                         goto done;
  902                 sf_buf_alloc_want++;
  903                 SFSTAT_INC(sf_allocwait);
  904                 error = msleep(&sf_buf_freelist, &sf_buf_lock,
  905                     (flags & SFB_CATCH) ? PCATCH | PVM : PVM, "sfbufa", 0);
  906                 sf_buf_alloc_want--;
  907 
  908                 /*
  909                  * If we got a signal, don't risk going back to sleep. 
  910                  */
  911                 if (error)
  912                         goto done;
  913         }
  914         TAILQ_REMOVE(&sf_buf_freelist, sf, free_entry);
  915         if (sf->m != NULL)
  916                 LIST_REMOVE(sf, list_entry);
  917         LIST_INSERT_HEAD(hash_list, sf, list_entry);
  918         sf->ref_count = 1;
  919         sf->m = m;
  920         nsfbufsused++;
  921         nsfbufspeak = imax(nsfbufspeak, nsfbufsused);
  922 
  923         /*
  924          * Update the sf_buf's virtual-to-physical mapping, flushing the
  925          * virtual address from the TLB.  Since the reference count for 
  926          * the sf_buf's old mapping was zero, that mapping is not 
  927          * currently in use.  Consequently, there is no need to exchange 
  928          * the old and new PTEs atomically, even under PAE.
  929          */
  930         ptep = vtopte(sf->kva);
  931         opte = *ptep;
  932 #ifdef XEN
  933        PT_SET_MA(sf->kva, xpmap_ptom(VM_PAGE_TO_PHYS(m)) | pgeflag
  934            | PG_RW | PG_V | pmap_cache_bits(m->md.pat_mode, 0));
  935 #else
  936         *ptep = VM_PAGE_TO_PHYS(m) | pgeflag | PG_RW | PG_V |
  937             pmap_cache_bits(m->md.pat_mode, 0);
  938 #endif
  939 
  940         /*
  941          * Avoid unnecessary TLB invalidations: If the sf_buf's old
  942          * virtual-to-physical mapping was not used, then any processor
  943          * that has invalidated the sf_buf's virtual address from its TLB
  944          * since the last used mapping need not invalidate again.
  945          */
  946 #ifdef SMP
  947         if ((opte & (PG_V | PG_A)) ==  (PG_V | PG_A))
  948                 CPU_ZERO(&sf->cpumask);
  949 shootdown:
  950         sched_pin();
  951         cpuid = PCPU_GET(cpuid);
  952         if (!CPU_ISSET(cpuid, &sf->cpumask)) {
  953                 CPU_SET(cpuid, &sf->cpumask);
  954                 invlpg(sf->kva);
  955         }
  956         if ((flags & SFB_CPUPRIVATE) == 0) {
  957                 other_cpus = all_cpus;
  958                 CPU_CLR(cpuid, &other_cpus);
  959                 CPU_NAND(&other_cpus, &sf->cpumask);
  960                 if (!CPU_EMPTY(&other_cpus)) {
  961                         CPU_OR(&sf->cpumask, &other_cpus);
  962                         smp_masked_invlpg(other_cpus, sf->kva);
  963                 }
  964         }
  965         sched_unpin();
  966 #else
  967         if ((opte & (PG_V | PG_A)) ==  (PG_V | PG_A))
  968                 pmap_invalidate_page(kernel_pmap, sf->kva);
  969 #endif
  970 done:
  971         mtx_unlock(&sf_buf_lock);
  972         return (sf);
  973 }
  974 
  975 /*
  976  * Remove a reference from the given sf_buf, adding it to the free
  977  * list when its reference count reaches zero.  A freed sf_buf still,
  978  * however, retains its virtual-to-physical mapping until it is
  979  * recycled or reactivated by sf_buf_alloc(9).
  980  */
  981 void
  982 sf_buf_free(struct sf_buf *sf)
  983 {
  984 
  985         mtx_lock(&sf_buf_lock);
  986         sf->ref_count--;
  987         if (sf->ref_count == 0) {
  988                 TAILQ_INSERT_TAIL(&sf_buf_freelist, sf, free_entry);
  989                 nsfbufsused--;
  990 #ifdef XEN
  991 /*
  992  * Xen doesn't like having dangling R/W mappings
  993  */
  994                 pmap_qremove(sf->kva, 1);
  995                 sf->m = NULL;
  996                 LIST_REMOVE(sf, list_entry);
  997 #endif
  998                 if (sf_buf_alloc_want > 0)
  999                         wakeup(&sf_buf_freelist);
 1000         }
 1001         mtx_unlock(&sf_buf_lock);
 1002 }
 1003 
 1004 /*
 1005  * Software interrupt handler for queued VM system processing.
 1006  */   
 1007 void  
 1008 swi_vm(void *dummy) 
 1009 {     
 1010         if (busdma_swi_pending != 0)
 1011                 busdma_swi();
 1012 }
 1013 
 1014 /*
 1015  * Tell whether this address is in some physical memory region.
 1016  * Currently used by the kernel coredump code in order to avoid
 1017  * dumping the ``ISA memory hole'' which could cause indefinite hangs,
 1018  * or other unpredictable behaviour.
 1019  */
 1020 
 1021 int
 1022 is_physical_memory(vm_paddr_t addr)
 1023 {
 1024 
 1025 #ifdef DEV_ISA
 1026         /* The ISA ``memory hole''. */
 1027         if (addr >= 0xa0000 && addr < 0x100000)
 1028                 return 0;
 1029 #endif
 1030 
 1031         /*
 1032          * stuff other tests for known memory-mapped devices (PCI?)
 1033          * here
 1034          */
 1035 
 1036         return 1;
 1037 }

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