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/keymap.h>
  11 #include <minix/minlib.h>
  12 #include <minix/type.h>
  13 #include <minix/ipc.h>
  14 #include <minix/sysutil.h>
  15 #include <minix/syslib.h>
  16 #include <minix/debug.h>
  17 #include <minix/bitmap.h>
  18
  19 #include <string.h>
  20 #include <errno.h>
  21 #include <env.h>
  22 #include <assert.h>
  23
  24 #include "glo.h"
  25 #include "vm.h"
  26 #include "proto.h"
  27 #include "util.h"
  28 #include "sanitycheck.h"
  29 #include "region.h"
  30 #include "memory.h"
  31
  32 /*===========================================================================*
  33  *                              do_fork                                      *
  34  *===========================================================================*/
  35 int do_fork(message *msg)
  36 {
  37   int r, proc, childproc;
  38   struct vmproc *vmp, *vmc;
  39   pt_t origpt;
  40   vir_bytes msgaddr;
  41
  42   SANITYCHECK(SCL_FUNCTIONS);
  43
  44   if(vm_isokendpt(msg->VMF_ENDPOINT, &proc) != OK) {
  45         printf("VM: bogus endpoint VM_FORK %d\n", msg->VMF_ENDPOINT);
  46   SANITYCHECK(SCL_FUNCTIONS);
  47         return EINVAL;
  48   }
  49
  50   childproc = msg->VMF_SLOTNO;
  51   if(childproc < 0 || childproc >= NR_PROCS) {
  52         printf("VM: bogus slotno VM_FORK %d\n", msg->VMF_SLOTNO);
  53   SANITYCHECK(SCL_FUNCTIONS);
  54         return EINVAL;
  55   }
  56
  57   vmp = &vmproc[proc];          /* parent */
  58   vmc = &vmproc[childproc];     /* child */
  59   assert(vmc->vm_slot == childproc);
  60
  61   /* The child is basically a copy of the parent. */
  62   origpt = vmc->vm_pt;
  63   *vmc = *vmp;
  64   vmc->vm_slot = childproc;
  65   region_init(&vmc->vm_regions_avl);
  66   vmc->vm_endpoint = NONE;      /* In case someone tries to use it. */
  67   vmc->vm_pt = origpt;
  68
  69 #if VMSTATS
  70   vmc->vm_bytecopies = 0;
  71 #endif
  72
  73   if(pt_new(&vmc->vm_pt) != OK) {
  74         printf("VM: fork: pt_new failed\n");
  75         return ENOMEM;
  76   }
  77
  78   SANITYCHECK(SCL_DETAIL);
  79
  80   if(map_proc_copy(vmc, vmp) != OK) {
  81         printf("VM: fork: map_proc_copy failed\n");
  82         pt_free(&vmc->vm_pt);
  83         return(ENOMEM);
  84   }
  85
  86   /* Only inherit these flags. */
  87   vmc->vm_flags &= VMF_INUSE;
  88
  89   /* inherit the priv call bitmaps */
  90   memcpy(&vmc->vm_call_mask, &vmp->vm_call_mask, sizeof(vmc->vm_call_mask));
  91
  92   /* Tell kernel about the (now successful) FORK. */
  93   if((r=sys_fork(vmp->vm_endpoint, childproc,
  94         &vmc->vm_endpoint, PFF_VMINHIBIT, &msgaddr)) != OK) {
  95         panic("do_fork can't sys_fork: %d", r);
  96   }
  97
  98   if((r=pt_bind(&vmc->vm_pt, vmc)) != OK)
  99         panic("fork can't pt_bind: %d", r);
 100
 101   {
 102         vir_bytes vir;
 103         /* making these messages writable is an optimisation
 104          * and its return value needn't be checked.
 105          */
 106         vir = msgaddr;
 107         if (handle_memory(vmc, vir, sizeof(message), 1) != OK)
 108             panic("do_fork: handle_memory for child failed\n");
 109         vir = msgaddr;
 110         if (handle_memory(vmp, vir, sizeof(message), 1) != OK)
 111             panic("do_fork: handle_memory for parent failed\n");
 112   }
 113
 114   /* Inform caller of new child endpoint. */
 115   msg->VMF_CHILD_ENDPOINT = vmc->vm_endpoint;
 116
 117   SANITYCHECK(SCL_FUNCTIONS);
 118   return OK;
 119 }
 120