The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/i386/i386/vm86.c

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    1 /*-
    2  * Copyright (c) 1997 Jonathan Lemon
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  */
   26 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD: releng/11.2/sys/i386/i386/vm86.c 332314 2018-04-09 01:06:09Z emaste $");
   29 
   30 #include <sys/param.h>
   31 #include <sys/systm.h>
   32 #include <sys/priv.h>
   33 #include <sys/proc.h>
   34 #include <sys/lock.h>
   35 #include <sys/malloc.h>
   36 #include <sys/mutex.h>
   37 
   38 #include <vm/vm.h>
   39 #include <vm/pmap.h>
   40 #include <vm/vm_map.h>
   41 #include <vm/vm_page.h>
   42 
   43 #include <machine/md_var.h>
   44 #include <machine/pcb.h>
   45 #include <machine/pcb_ext.h>
   46 #include <machine/psl.h>
   47 #include <machine/specialreg.h>
   48 #include <machine/sysarch.h>
   49 
   50 extern int vm86pa;
   51 extern struct pcb *vm86pcb;
   52 
   53 static struct mtx vm86_lock;
   54 
   55 extern int vm86_bioscall(struct vm86frame *);
   56 extern void vm86_biosret(struct vm86frame *);
   57 
   58 void vm86_prepcall(struct vm86frame *);
   59 
   60 struct system_map {
   61         int             type;
   62         vm_offset_t     start;
   63         vm_offset_t     end;
   64 };
   65 
   66 #define HLT     0xf4
   67 #define CLI     0xfa
   68 #define STI     0xfb
   69 #define PUSHF   0x9c
   70 #define POPF    0x9d
   71 #define INTn    0xcd
   72 #define IRET    0xcf
   73 #define CALLm   0xff
   74 #define OPERAND_SIZE_PREFIX     0x66
   75 #define ADDRESS_SIZE_PREFIX     0x67
   76 #define PUSH_MASK       ~(PSL_VM | PSL_RF | PSL_I)
   77 #define POP_MASK        ~(PSL_VIP | PSL_VIF | PSL_VM | PSL_RF | PSL_IOPL)
   78 
   79 static __inline caddr_t
   80 MAKE_ADDR(u_short sel, u_short off)
   81 {
   82         return ((caddr_t)((sel << 4) + off));
   83 }
   84 
   85 static __inline void
   86 GET_VEC(u_int vec, u_short *sel, u_short *off)
   87 {
   88         *sel = vec >> 16;
   89         *off = vec & 0xffff;
   90 }
   91 
   92 static __inline u_int
   93 MAKE_VEC(u_short sel, u_short off)
   94 {
   95         return ((sel << 16) | off);
   96 }
   97 
   98 static __inline void
   99 PUSH(u_short x, struct vm86frame *vmf)
  100 {
  101         vmf->vmf_sp -= 2;
  102         suword16(MAKE_ADDR(vmf->vmf_ss, vmf->vmf_sp), x);
  103 }
  104 
  105 static __inline void
  106 PUSHL(u_int x, struct vm86frame *vmf)
  107 {
  108         vmf->vmf_sp -= 4;
  109         suword(MAKE_ADDR(vmf->vmf_ss, vmf->vmf_sp), x);
  110 }
  111 
  112 static __inline u_short
  113 POP(struct vm86frame *vmf)
  114 {
  115         u_short x = fuword16(MAKE_ADDR(vmf->vmf_ss, vmf->vmf_sp));
  116 
  117         vmf->vmf_sp += 2;
  118         return (x);
  119 }
  120 
  121 static __inline u_int
  122 POPL(struct vm86frame *vmf)
  123 {
  124         u_int x = fuword(MAKE_ADDR(vmf->vmf_ss, vmf->vmf_sp));
  125 
  126         vmf->vmf_sp += 4;
  127         return (x);
  128 }
  129 
  130 int
  131 vm86_emulate(struct vm86frame *vmf)
  132 {
  133         struct vm86_kernel *vm86;
  134         caddr_t addr;
  135         u_char i_byte;
  136         u_int temp_flags;
  137         int inc_ip = 1;
  138         int retcode = 0;
  139 
  140         /*
  141          * pcb_ext contains the address of the extension area, or zero if
  142          * the extension is not present.  (This check should not be needed,
  143          * as we can't enter vm86 mode until we set up an extension area)
  144          */
  145         if (curpcb->pcb_ext == 0)
  146                 return (SIGBUS);
  147         vm86 = &curpcb->pcb_ext->ext_vm86;
  148 
  149         if (vmf->vmf_eflags & PSL_T)
  150                 retcode = SIGTRAP;
  151 
  152         addr = MAKE_ADDR(vmf->vmf_cs, vmf->vmf_ip);
  153         i_byte = fubyte(addr);
  154         if (i_byte == ADDRESS_SIZE_PREFIX) {
  155                 i_byte = fubyte(++addr);
  156                 inc_ip++;
  157         }
  158 
  159         if (vm86->vm86_has_vme) {
  160                 switch (i_byte) {
  161                 case OPERAND_SIZE_PREFIX:
  162                         i_byte = fubyte(++addr);
  163                         inc_ip++;
  164                         switch (i_byte) {
  165                         case PUSHF:
  166                                 if (vmf->vmf_eflags & PSL_VIF)
  167                                         PUSHL((vmf->vmf_eflags & PUSH_MASK)
  168                                             | PSL_IOPL | PSL_I, vmf);
  169                                 else
  170                                         PUSHL((vmf->vmf_eflags & PUSH_MASK)
  171                                             | PSL_IOPL, vmf);
  172                                 vmf->vmf_ip += inc_ip;
  173                                 return (retcode);
  174 
  175                         case POPF:
  176                                 temp_flags = POPL(vmf) & POP_MASK;
  177                                 vmf->vmf_eflags = (vmf->vmf_eflags & ~POP_MASK)
  178                                     | temp_flags | PSL_VM | PSL_I;
  179                                 vmf->vmf_ip += inc_ip;
  180                                 if (temp_flags & PSL_I) {
  181                                         vmf->vmf_eflags |= PSL_VIF;
  182                                         if (vmf->vmf_eflags & PSL_VIP)
  183                                                 break;
  184                                 } else {
  185                                         vmf->vmf_eflags &= ~PSL_VIF;
  186                                 }
  187                                 return (retcode);
  188                         }
  189                         break;
  190 
  191                 /* VME faults here if VIP is set, but does not set VIF. */
  192                 case STI:
  193                         vmf->vmf_eflags |= PSL_VIF;
  194                         vmf->vmf_ip += inc_ip;
  195                         if ((vmf->vmf_eflags & PSL_VIP) == 0) {
  196                                 uprintf("fatal sti\n");
  197                                 return (SIGKILL);
  198                         }
  199                         break;
  200 
  201                 /* VME if no redirection support */
  202                 case INTn:
  203                         break;
  204 
  205                 /* VME if trying to set PSL_T, or PSL_I when VIP is set */
  206                 case POPF:
  207                         temp_flags = POP(vmf) & POP_MASK;
  208                         vmf->vmf_flags = (vmf->vmf_flags & ~POP_MASK)
  209                             | temp_flags | PSL_VM | PSL_I;
  210                         vmf->vmf_ip += inc_ip;
  211                         if (temp_flags & PSL_I) {
  212                                 vmf->vmf_eflags |= PSL_VIF;
  213                                 if (vmf->vmf_eflags & PSL_VIP)
  214                                         break;
  215                         } else {
  216                                 vmf->vmf_eflags &= ~PSL_VIF;
  217                         }
  218                         return (retcode);
  219 
  220                 /* VME if trying to set PSL_T, or PSL_I when VIP is set */
  221                 case IRET:
  222                         vmf->vmf_ip = POP(vmf);
  223                         vmf->vmf_cs = POP(vmf);
  224                         temp_flags = POP(vmf) & POP_MASK;
  225                         vmf->vmf_flags = (vmf->vmf_flags & ~POP_MASK)
  226                             | temp_flags | PSL_VM | PSL_I;
  227                         if (temp_flags & PSL_I) {
  228                                 vmf->vmf_eflags |= PSL_VIF;
  229                                 if (vmf->vmf_eflags & PSL_VIP)
  230                                         break;
  231                         } else {
  232                                 vmf->vmf_eflags &= ~PSL_VIF;
  233                         }
  234                         return (retcode);
  235 
  236                 }
  237                 return (SIGBUS);
  238         }
  239 
  240         switch (i_byte) {
  241         case OPERAND_SIZE_PREFIX:
  242                 i_byte = fubyte(++addr);
  243                 inc_ip++;
  244                 switch (i_byte) {
  245                 case PUSHF:
  246                         if (vm86->vm86_eflags & PSL_VIF)
  247                                 PUSHL((vmf->vmf_flags & PUSH_MASK)
  248                                     | PSL_IOPL | PSL_I, vmf);
  249                         else
  250                                 PUSHL((vmf->vmf_flags & PUSH_MASK)
  251                                     | PSL_IOPL, vmf);
  252                         vmf->vmf_ip += inc_ip;
  253                         return (retcode);
  254 
  255                 case POPF:
  256                         temp_flags = POPL(vmf) & POP_MASK;
  257                         vmf->vmf_eflags = (vmf->vmf_eflags & ~POP_MASK)
  258                             | temp_flags | PSL_VM | PSL_I;
  259                         vmf->vmf_ip += inc_ip;
  260                         if (temp_flags & PSL_I) {
  261                                 vm86->vm86_eflags |= PSL_VIF;
  262                                 if (vm86->vm86_eflags & PSL_VIP)
  263                                         break;
  264                         } else {
  265                                 vm86->vm86_eflags &= ~PSL_VIF;
  266                         }
  267                         return (retcode);
  268                 }
  269                 return (SIGBUS);
  270 
  271         case CLI:
  272                 vm86->vm86_eflags &= ~PSL_VIF;
  273                 vmf->vmf_ip += inc_ip;
  274                 return (retcode);
  275 
  276         case STI:
  277                 /* if there is a pending interrupt, go to the emulator */
  278                 vm86->vm86_eflags |= PSL_VIF;
  279                 vmf->vmf_ip += inc_ip;
  280                 if (vm86->vm86_eflags & PSL_VIP)
  281                         break;
  282                 return (retcode);
  283 
  284         case PUSHF:
  285                 if (vm86->vm86_eflags & PSL_VIF)
  286                         PUSH((vmf->vmf_flags & PUSH_MASK)
  287                             | PSL_IOPL | PSL_I, vmf);
  288                 else
  289                         PUSH((vmf->vmf_flags & PUSH_MASK) | PSL_IOPL, vmf);
  290                 vmf->vmf_ip += inc_ip;
  291                 return (retcode);
  292 
  293         case INTn:
  294                 i_byte = fubyte(addr + 1);
  295                 if ((vm86->vm86_intmap[i_byte >> 3] & (1 << (i_byte & 7))) != 0)
  296                         break;
  297                 if (vm86->vm86_eflags & PSL_VIF)
  298                         PUSH((vmf->vmf_flags & PUSH_MASK)
  299                             | PSL_IOPL | PSL_I, vmf);
  300                 else
  301                         PUSH((vmf->vmf_flags & PUSH_MASK) | PSL_IOPL, vmf);
  302                 PUSH(vmf->vmf_cs, vmf);
  303                 PUSH(vmf->vmf_ip + inc_ip + 1, vmf);    /* increment IP */
  304                 GET_VEC(fuword((caddr_t)(i_byte * 4)),
  305                      &vmf->vmf_cs, &vmf->vmf_ip);
  306                 vmf->vmf_flags &= ~PSL_T;
  307                 vm86->vm86_eflags &= ~PSL_VIF;
  308                 return (retcode);
  309 
  310         case IRET:
  311                 vmf->vmf_ip = POP(vmf);
  312                 vmf->vmf_cs = POP(vmf);
  313                 temp_flags = POP(vmf) & POP_MASK;
  314                 vmf->vmf_flags = (vmf->vmf_flags & ~POP_MASK)
  315                     | temp_flags | PSL_VM | PSL_I;
  316                 if (temp_flags & PSL_I) {
  317                         vm86->vm86_eflags |= PSL_VIF;
  318                         if (vm86->vm86_eflags & PSL_VIP)
  319                                 break;
  320                 } else {
  321                         vm86->vm86_eflags &= ~PSL_VIF;
  322                 }
  323                 return (retcode);
  324 
  325         case POPF:
  326                 temp_flags = POP(vmf) & POP_MASK;
  327                 vmf->vmf_flags = (vmf->vmf_flags & ~POP_MASK)
  328                     | temp_flags | PSL_VM | PSL_I;
  329                 vmf->vmf_ip += inc_ip;
  330                 if (temp_flags & PSL_I) {
  331                         vm86->vm86_eflags |= PSL_VIF;
  332                         if (vm86->vm86_eflags & PSL_VIP)
  333                                 break;
  334                 } else {
  335                         vm86->vm86_eflags &= ~PSL_VIF;
  336                 }
  337                 return (retcode);
  338         }
  339         return (SIGBUS);
  340 }
  341 
  342 #define PGTABLE_SIZE    ((1024 + 64) * 1024 / PAGE_SIZE)
  343 #define INTMAP_SIZE     32
  344 #define IOMAP_SIZE      ctob(IOPAGES)
  345 #define TSS_SIZE \
  346         (sizeof(struct pcb_ext) - sizeof(struct segment_descriptor) + \
  347          INTMAP_SIZE + IOMAP_SIZE + 1)
  348 
  349 struct vm86_layout {
  350         pt_entry_t      vml_pgtbl[PGTABLE_SIZE];
  351         struct  pcb vml_pcb;
  352         struct  pcb_ext vml_ext;
  353         char    vml_intmap[INTMAP_SIZE];
  354         char    vml_iomap[IOMAP_SIZE];
  355         char    vml_iomap_trailer;
  356 };
  357 
  358 void
  359 vm86_initialize(void)
  360 {
  361         int i;
  362         u_int *addr;
  363         struct vm86_layout *vml = (struct vm86_layout *)vm86paddr;
  364         struct pcb *pcb;
  365         struct pcb_ext *ext;
  366         struct soft_segment_descriptor ssd = {
  367                 0,                      /* segment base address (overwritten) */
  368                 0,                      /* length (overwritten) */
  369                 SDT_SYS386TSS,          /* segment type */
  370                 0,                      /* priority level */
  371                 1,                      /* descriptor present */
  372                 0, 0,
  373                 0,                      /* default 16 size */
  374                 0                       /* granularity */
  375         };
  376 
  377         /*
  378          * this should be a compile time error, but cpp doesn't grok sizeof().
  379          */
  380         if (sizeof(struct vm86_layout) > ctob(3))
  381                 panic("struct vm86_layout exceeds space allocated in locore.s");
  382 
  383         /*
  384          * Below is the memory layout that we use for the vm86 region.
  385          *
  386          * +--------+
  387          * |        | 
  388          * |        |
  389          * | page 0 |       
  390          * |        | +--------+
  391          * |        | | stack  |
  392          * +--------+ +--------+ <--------- vm86paddr
  393          * |        | |Page Tbl| 1M + 64K = 272 entries = 1088 bytes
  394          * |        | +--------+
  395          * |        | |  PCB   | size: ~240 bytes
  396          * | page 1 | |PCB Ext | size: ~140 bytes (includes TSS)
  397          * |        | +--------+
  398          * |        | |int map |
  399          * |        | +--------+
  400          * +--------+ |        |
  401          * | page 2 | |  I/O   |
  402          * +--------+ | bitmap |
  403          * | page 3 | |        |
  404          * |        | +--------+
  405          * +--------+ 
  406          */
  407 
  408         /*
  409          * A rudimentary PCB must be installed, in order to get to the
  410          * PCB extension area.  We use the PCB area as a scratchpad for
  411          * data storage, the layout of which is shown below.
  412          *
  413          * pcb_esi      = new PTD entry 0
  414          * pcb_ebp      = pointer to frame on vm86 stack
  415          * pcb_esp      =    stack frame pointer at time of switch
  416          * pcb_ebx      = va of vm86 page table
  417          * pcb_eip      =    argument pointer to initial call
  418          * pcb_vm86[0]  =    saved TSS descriptor, word 0
  419          * pcb_vm86[1]  =    saved TSS descriptor, word 1
  420          */
  421 #define new_ptd         pcb_esi
  422 #define vm86_frame      pcb_ebp
  423 #define pgtable_va      pcb_ebx
  424 
  425         pcb = &vml->vml_pcb;
  426         ext = &vml->vml_ext;
  427 
  428         mtx_init(&vm86_lock, "vm86 lock", NULL, MTX_DEF);
  429 
  430         bzero(pcb, sizeof(struct pcb));
  431         pcb->new_ptd = vm86pa | PG_V | PG_RW | PG_U;
  432         pcb->vm86_frame = vm86paddr - sizeof(struct vm86frame);
  433         pcb->pgtable_va = vm86paddr;
  434         pcb->pcb_flags = PCB_VM86CALL; 
  435         pcb->pcb_ext = ext;
  436 
  437         bzero(ext, sizeof(struct pcb_ext)); 
  438         ext->ext_tss.tss_esp0 = vm86paddr;
  439         ext->ext_tss.tss_ss0 = GSEL(GDATA_SEL, SEL_KPL);
  440         ext->ext_tss.tss_ioopt = 
  441                 ((u_int)vml->vml_iomap - (u_int)&ext->ext_tss) << 16;
  442         ext->ext_iomap = vml->vml_iomap;
  443         ext->ext_vm86.vm86_intmap = vml->vml_intmap;
  444 
  445         if (cpu_feature & CPUID_VME)
  446                 ext->ext_vm86.vm86_has_vme = (rcr4() & CR4_VME ? 1 : 0);
  447 
  448         addr = (u_int *)ext->ext_vm86.vm86_intmap;
  449         for (i = 0; i < (INTMAP_SIZE + IOMAP_SIZE) / sizeof(u_int); i++)
  450                 *addr++ = 0;
  451         vml->vml_iomap_trailer = 0xff;
  452 
  453         ssd.ssd_base = (u_int)&ext->ext_tss;
  454         ssd.ssd_limit = TSS_SIZE - 1; 
  455         ssdtosd(&ssd, &ext->ext_tssd);
  456 
  457         vm86pcb = pcb;
  458 
  459 #if 0
  460         /*
  461          * use whatever is leftover of the vm86 page layout as a
  462          * message buffer so we can capture early output.
  463          */
  464         msgbufinit((vm_offset_t)vm86paddr + sizeof(struct vm86_layout),
  465             ctob(3) - sizeof(struct vm86_layout));
  466 #endif
  467 }
  468 
  469 vm_offset_t
  470 vm86_getpage(struct vm86context *vmc, int pagenum)
  471 {
  472         int i;
  473 
  474         for (i = 0; i < vmc->npages; i++)
  475                 if (vmc->pmap[i].pte_num == pagenum)
  476                         return (vmc->pmap[i].kva);
  477         return (0);
  478 }
  479 
  480 vm_offset_t
  481 vm86_addpage(struct vm86context *vmc, int pagenum, vm_offset_t kva)
  482 {
  483         int i, flags = 0;
  484 
  485         for (i = 0; i < vmc->npages; i++)
  486                 if (vmc->pmap[i].pte_num == pagenum)
  487                         goto overlap;
  488 
  489         if (vmc->npages == VM86_PMAPSIZE)
  490                 goto full;                      /* XXX grow map? */
  491 
  492         if (kva == 0) {
  493                 kva = (vm_offset_t)malloc(PAGE_SIZE, M_TEMP, M_WAITOK);
  494                 flags = VMAP_MALLOC;
  495         }
  496 
  497         i = vmc->npages++;
  498         vmc->pmap[i].flags = flags;
  499         vmc->pmap[i].kva = kva;
  500         vmc->pmap[i].pte_num = pagenum;
  501         return (kva);
  502 overlap:
  503         panic("vm86_addpage: overlap");
  504 full:
  505         panic("vm86_addpage: not enough room");
  506 }
  507 
  508 /*
  509  * called from vm86_bioscall, while in vm86 address space, to finalize setup.
  510  */
  511 void
  512 vm86_prepcall(struct vm86frame *vmf)
  513 {
  514         struct vm86_kernel *vm86;
  515         uint32_t *stack;
  516         uint8_t *code;
  517 
  518         code = (void *)0xa00;
  519         stack = (void *)(0x1000 - 2);   /* keep aligned */
  520         if ((vmf->vmf_trapno & PAGE_MASK) <= 0xff) {
  521                 /* interrupt call requested */
  522                 code[0] = INTn;
  523                 code[1] = vmf->vmf_trapno & 0xff;
  524                 code[2] = HLT;
  525                 vmf->vmf_ip = (uintptr_t)code;
  526                 vmf->vmf_cs = 0;
  527         } else {
  528                 code[0] = HLT;
  529                 stack--;
  530                 stack[0] = MAKE_VEC(0, (uintptr_t)code);
  531         }
  532         vmf->vmf_sp = (uintptr_t)stack;
  533         vmf->vmf_ss = 0;
  534         vmf->kernel_fs = vmf->kernel_es = vmf->kernel_ds = 0;
  535         vmf->vmf_eflags = PSL_VIF | PSL_VM | PSL_USER;
  536 
  537         vm86 = &curpcb->pcb_ext->ext_vm86;
  538         if (!vm86->vm86_has_vme) 
  539                 vm86->vm86_eflags = vmf->vmf_eflags;  /* save VIF, VIP */
  540 }
  541 
  542 /*
  543  * vm86 trap handler; determines whether routine succeeded or not.
  544  * Called while in vm86 space, returns to calling process.
  545  */
  546 void
  547 vm86_trap(struct vm86frame *vmf)
  548 {
  549         caddr_t addr;
  550 
  551         /* "should not happen" */
  552         if ((vmf->vmf_eflags & PSL_VM) == 0)
  553                 panic("vm86_trap called, but not in vm86 mode");
  554 
  555         addr = MAKE_ADDR(vmf->vmf_cs, vmf->vmf_ip);
  556         if (*(u_char *)addr == HLT)
  557                 vmf->vmf_trapno = vmf->vmf_eflags & PSL_C;
  558         else
  559                 vmf->vmf_trapno = vmf->vmf_trapno << 16;
  560 
  561         vm86_biosret(vmf);
  562 }
  563 
  564 int
  565 vm86_intcall(int intnum, struct vm86frame *vmf)
  566 {
  567         int retval;
  568 
  569         if (intnum < 0 || intnum > 0xff)
  570                 return (EINVAL);
  571 
  572         vmf->vmf_trapno = intnum;
  573         mtx_lock(&vm86_lock);
  574         critical_enter();
  575         retval = vm86_bioscall(vmf);
  576         critical_exit();
  577         mtx_unlock(&vm86_lock);
  578         return (retval);
  579 }
  580 
  581 /*
  582  * struct vm86context contains the page table to use when making
  583  * vm86 calls.  If intnum is a valid interrupt number (0-255), then
  584  * the "interrupt trampoline" will be used, otherwise we use the
  585  * caller's cs:ip routine.  
  586  */
  587 int
  588 vm86_datacall(int intnum, struct vm86frame *vmf, struct vm86context *vmc)
  589 {
  590         pt_entry_t *pte = (pt_entry_t *)vm86paddr;
  591         vm_paddr_t page;
  592         int i, entry, retval;
  593 
  594         mtx_lock(&vm86_lock);
  595         for (i = 0; i < vmc->npages; i++) {
  596                 page = vtophys(vmc->pmap[i].kva & PG_FRAME);
  597                 entry = vmc->pmap[i].pte_num; 
  598                 vmc->pmap[i].old_pte = pte[entry];
  599                 pte[entry] = page | PG_V | PG_RW | PG_U;
  600                 pmap_invalidate_page(kernel_pmap, vmc->pmap[i].kva);
  601         }
  602 
  603         vmf->vmf_trapno = intnum;
  604         critical_enter();
  605         retval = vm86_bioscall(vmf);
  606         critical_exit();
  607 
  608         for (i = 0; i < vmc->npages; i++) {
  609                 entry = vmc->pmap[i].pte_num;
  610                 pte[entry] = vmc->pmap[i].old_pte;
  611                 pmap_invalidate_page(kernel_pmap, vmc->pmap[i].kva);
  612         }
  613         mtx_unlock(&vm86_lock);
  614 
  615         return (retval);
  616 }
  617 
  618 vm_offset_t
  619 vm86_getaddr(struct vm86context *vmc, u_short sel, u_short off)
  620 {
  621         int i, page;
  622         vm_offset_t addr;
  623 
  624         addr = (vm_offset_t)MAKE_ADDR(sel, off);
  625         page = addr >> PAGE_SHIFT;
  626         for (i = 0; i < vmc->npages; i++)
  627                 if (page == vmc->pmap[i].pte_num)
  628                         return (vmc->pmap[i].kva + (addr & PAGE_MASK));
  629         return (0);
  630 }
  631 
  632 int
  633 vm86_getptr(struct vm86context *vmc, vm_offset_t kva, u_short *sel,
  634      u_short *off)
  635 {
  636         int i;
  637 
  638         for (i = 0; i < vmc->npages; i++)
  639                 if (kva >= vmc->pmap[i].kva &&
  640                     kva < vmc->pmap[i].kva + PAGE_SIZE) {
  641                         *off = kva - vmc->pmap[i].kva;
  642                         *sel = vmc->pmap[i].pte_num << 8;
  643                         return (1);
  644                 }
  645         return (0);
  646 }
  647         
  648 int
  649 vm86_sysarch(struct thread *td, char *args)
  650 {
  651         int error = 0;
  652         struct i386_vm86_args ua;
  653         struct vm86_kernel *vm86;
  654 
  655         if ((error = copyin(args, &ua, sizeof(struct i386_vm86_args))) != 0)
  656                 return (error);
  657 
  658         if (td->td_pcb->pcb_ext == 0)
  659                 if ((error = i386_extend_pcb(td)) != 0)
  660                         return (error);
  661         vm86 = &td->td_pcb->pcb_ext->ext_vm86;
  662 
  663         switch (ua.sub_op) {
  664         case VM86_INIT: {
  665                 struct vm86_init_args sa;
  666 
  667                 if ((error = copyin(ua.sub_args, &sa, sizeof(sa))) != 0)
  668                         return (error);
  669                 if (cpu_feature & CPUID_VME)
  670                         vm86->vm86_has_vme = (rcr4() & CR4_VME ? 1 : 0);
  671                 else
  672                         vm86->vm86_has_vme = 0;
  673                 vm86->vm86_inited = 1;
  674                 vm86->vm86_debug = sa.debug;
  675                 bcopy(&sa.int_map, vm86->vm86_intmap, 32);
  676                 }
  677                 break;
  678 
  679 #if 0
  680         case VM86_SET_VME: {
  681                 struct vm86_vme_args sa;
  682         
  683                 if ((cpu_feature & CPUID_VME) == 0)
  684                         return (ENODEV);
  685 
  686                 if (error = copyin(ua.sub_args, &sa, sizeof(sa)))
  687                         return (error);
  688                 if (sa.state)
  689                         load_cr4(rcr4() | CR4_VME);
  690                 else
  691                         load_cr4(rcr4() & ~CR4_VME);
  692                 }
  693                 break;
  694 #endif
  695 
  696         case VM86_GET_VME: {
  697                 struct vm86_vme_args sa;
  698 
  699                 sa.state = (rcr4() & CR4_VME ? 1 : 0);
  700                 error = copyout(&sa, ua.sub_args, sizeof(sa));
  701                 }
  702                 break;
  703 
  704         case VM86_INTCALL: {
  705                 struct vm86_intcall_args sa;
  706 
  707                 if ((error = priv_check(td, PRIV_VM86_INTCALL)))
  708                         return (error);
  709                 if ((error = copyin(ua.sub_args, &sa, sizeof(sa))))
  710                         return (error);
  711                 if ((error = vm86_intcall(sa.intnum, &sa.vmf)))
  712                         return (error);
  713                 error = copyout(&sa, ua.sub_args, sizeof(sa));
  714                 }
  715                 break;
  716 
  717         default:
  718                 error = EINVAL;
  719         }
  720         return (error);
  721 }

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