servers/vm/fork.c

   1
   2 #define _SYSTEM 1
   3
   4 #include <minix/callnr.h>
   5 #include <minix/com.h>
   6 #include <minix/config.h>
   7 #include <minix/const.h>
   8 #include <minix/ds.h>
   9 #include <minix/endpoint.h>
  10 #include <minix/minlib.h>
  11 #include <minix/type.h>
  12 #include <minix/ipc.h>
  13 #include <minix/sysutil.h>
  14 #include <minix/syslib.h>
  15 #include <minix/debug.h>
  16 #include <minix/bitmap.h>
  17
  18 #include <string.h>
  19 #include <errno.h>
  20 #include <env.h>
  21 #include <assert.h>
  22
  23 #include "glo.h"
  24 #include "vm.h"
  25 #include "proto.h"
  26 #include "util.h"
  27 #include "sanitycheck.h"
  28 #include "region.h"
  29
  30 /*===========================================================================*
  31  *                              do_fork                                      *
  32  *===========================================================================*/
  33 int do_fork(message *msg)
  34 {
  35   int r, proc, childproc;
  36   struct vmproc *vmp, *vmc;
  37   pt_t origpt;
  38   vir_bytes msgaddr;
  39
  40   SANITYCHECK(SCL_FUNCTIONS);
  41
  42   if(vm_isokendpt(msg->VMF_ENDPOINT, &proc) != OK) {
  43         printf("VM: bogus endpoint VM_FORK %d\n", msg->VMF_ENDPOINT);
  44   SANITYCHECK(SCL_FUNCTIONS);
  45         return EINVAL;
  46   }
  47
  48   childproc = msg->VMF_SLOTNO;
  49   if(childproc < 0 || childproc >= NR_PROCS) {
  50         printf("VM: bogus slotno VM_FORK %d\n", msg->VMF_SLOTNO);
  51   SANITYCHECK(SCL_FUNCTIONS);
  52         return EINVAL;
  53   }
  54
  55   vmp = &vmproc[proc];          /* parent */
  56   vmc = &vmproc[childproc];     /* child */
  57   assert(vmc->vm_slot == childproc);
  58
  59   /* The child is basically a copy of the parent. */
  60   origpt = vmc->vm_pt;
  61   *vmc = *vmp;
  62   vmc->vm_slot = childproc;
  63   region_init(&vmc->vm_regions_avl);
  64   vmc->vm_endpoint = NONE;      /* In case someone tries to use it. */
  65   vmc->vm_pt = origpt;
  66
  67 #if VMSTATS
  68   vmc->vm_bytecopies = 0;
  69 #endif
  70
  71   if(pt_new(&vmc->vm_pt) != OK) {
  72         return ENOMEM;
  73   }
  74
  75   SANITYCHECK(SCL_DETAIL);
  76
  77   if(map_proc_copy(vmc, vmp) != OK) {
  78         printf("VM: fork: map_proc_copy failed\n");
  79         pt_free(&vmc->vm_pt);
  80         return(ENOMEM);
  81   }
  82
  83   /* Only inherit these flags. */
  84   vmc->vm_flags &= VMF_INUSE;
  85
  86   /* Deal with ACLs. */
  87   acl_fork(vmc);
  88
  89   /* Tell kernel about the (now successful) FORK. */
  90   if((r=sys_fork(vmp->vm_endpoint, childproc,
  91         &vmc->vm_endpoint, PFF_VMINHIBIT, &msgaddr)) != OK) {
  92         panic("do_fork can't sys_fork: %d", r);
  93   }
  94
  95   if((r=pt_bind(&vmc->vm_pt, vmc)) != OK)
  96         panic("fork can't pt_bind: %d", r);
  97
  98   {
  99         vir_bytes vir;
 100         /* making these messages writable is an optimisation
 101          * and its return value needn't be checked.
 102          */
 103         vir = msgaddr;
 104         if (handle_memory_once(vmc, vir, sizeof(message), 1) != OK)
 105             panic("do_fork: handle_memory for child failed\n");
 106         vir = msgaddr;
 107         if (handle_memory_once(vmp, vir, sizeof(message), 1) != OK)
 108             panic("do_fork: handle_memory for parent failed\n");
 109   }
 110
 111   /* Inform caller of new child endpoint. */
 112   msg->VMF_CHILD_ENDPOINT = vmc->vm_endpoint;
 113
 114   SANITYCHECK(SCL_FUNCTIONS);
 115   return OK;
 116 }
 117