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