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