minix/servers/vm/fork.c

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#define _SYSTEM 1
#include <minix/callnr.h>
#include <minix/com.h>
#include <minix/config.h>
#include <minix/const.h>
#include <minix/ds.h>
#include <minix/endpoint.h>
#include <minix/keymap.h>
#include <minix/minlib.h>
#include <minix/type.h>
#include <minix/ipc.h>
#include <minix/sysutil.h>
#include <minix/syslib.h>
#include <minix/debug.h>
#include <minix/bitmap.h>
#include <string.h>
#include <errno.h>
#include <env.h>
#include "glo.h"
#include "vm.h"
#include "proto.h"
#include "util.h"
#include "sanitycheck.h"
#include "region.h"
/*===========================================================================*
* do_fork *
*===========================================================================*/
PUBLIC int do_fork(message *msg)
{
int r, proc, s, childproc, fullvm;
struct vmproc *vmp, *vmc;
pt_t origpt;
vir_bytes msgaddr;
SANITYCHECK(SCL_FUNCTIONS);
if(vm_isokendpt(msg->VMF_ENDPOINT, &proc) != OK) {
printf("VM: bogus endpoint VM_FORK %d\n", msg->VMF_ENDPOINT);
SANITYCHECK(SCL_FUNCTIONS);
return EINVAL;
}
childproc = msg->VMF_SLOTNO;
if(childproc < 0 || childproc >= NR_PROCS) {
printf("VM: bogus slotno VM_FORK %d\n", msg->VMF_SLOTNO);
SANITYCHECK(SCL_FUNCTIONS);
return EINVAL;
}
vmp = &vmproc[proc]; /* parent */
vmc = &vmproc[childproc]; /* child */
vm_assert(vmc->vm_slot == childproc);
NOTRUNNABLE(vmp->vm_endpoint);
if(vmp->vm_flags & VMF_HAS_DMA) {
printf("VM: %d has DMA memory and may not fork\n", msg->VMF_ENDPOINT);
return EINVAL;
}
fullvm = vmp->vm_flags & VMF_HASPT;
/* The child is basically a copy of the parent. */
origpt = vmc->vm_pt;
*vmc = *vmp;
vmc->vm_slot = childproc;
vmc->vm_regions = NULL;
vmc->vm_endpoint = NONE; /* In case someone tries to use it. */
vmc->vm_pt = origpt;
vmc->vm_flags |= VMF_HASPT;
#if VMSTATS
vmc->vm_bytecopies = 0;
#endif
SANITYCHECK(SCL_DETAIL);
if(fullvm) {
SANITYCHECK(SCL_DETAIL);
if(pt_new(&vmc->vm_pt) != OK) {
printf("VM: fork: pt_new failed\n");
return ENOMEM;
}
SANITYCHECK(SCL_DETAIL);
if(map_proc_copy(vmc, vmp) != OK) {
printf("VM: fork: map_proc_copy failed\n");
pt_free(&vmc->vm_pt);
return(ENOMEM);
}
if(vmp->vm_heap) {
vmc->vm_heap = map_region_lookup_tag(vmc, VRT_HEAP);
vm_assert(vmc->vm_heap);
}
SANITYCHECK(SCL_DETAIL);
} else {
phys_bytes prog_bytes, parent_abs, child_abs; /* Intel only */
phys_clicks prog_clicks, child_base;
/* Determine how much memory to allocate. Only the data and stack
* need to be copied, because the text segment is either shared or
* of zero length.
*/
prog_clicks = (phys_clicks) vmp->vm_arch.vm_seg[S].mem_len;
prog_clicks += (vmp->vm_arch.vm_seg[S].mem_vir - vmp->vm_arch.vm_seg[D].mem_vir);
prog_bytes = (phys_bytes) prog_clicks << CLICK_SHIFT;
if ( (child_base = ALLOC_MEM(prog_clicks, 0)) == NO_MEM) {
SANITYCHECK(SCL_FUNCTIONS);
return(ENOMEM);
}
/* Create a copy of the parent's core image for the child. */
child_abs = (phys_bytes) child_base << CLICK_SHIFT;
parent_abs = (phys_bytes) vmp->vm_arch.vm_seg[D].mem_phys << CLICK_SHIFT;
s = sys_abscopy(parent_abs, child_abs, prog_bytes);
if (s < 0) vm_panic("do_fork can't copy", s);
/* A separate I&D child keeps the parents text segment. The data and stack
* segments must refer to the new copy.
*/
if (!(vmc->vm_flags & VMF_SEPARATE))
vmc->vm_arch.vm_seg[T].mem_phys = child_base;
vmc->vm_arch.vm_seg[D].mem_phys = child_base;
vmc->vm_arch.vm_seg[S].mem_phys = vmc->vm_arch.vm_seg[D].mem_phys +
(vmp->vm_arch.vm_seg[S].mem_vir - vmp->vm_arch.vm_seg[D].mem_vir);
if(pt_identity(&vmc->vm_pt) != OK) {
printf("VM: fork: pt_identity failed\n");
return ENOMEM;
}
}
/* Only inherit these flags. */
vmc->vm_flags &= (VMF_INUSE|VMF_SEPARATE|VMF_HASPT);
/* inherit the priv call bitmaps */
memcpy(&vmc->vm_call_priv_mask, &vmp->vm_call_priv_mask,
sizeof(vmc->vm_call_priv_mask));
/* Tell kernel about the (now successful) FORK. */
if((r=sys_fork(vmp->vm_endpoint, childproc,
&vmc->vm_endpoint, vmc->vm_arch.vm_seg,
PFF_VMINHIBIT, &msgaddr)) != OK) {
vm_panic("do_fork can't sys_fork", r);
}
NOTRUNNABLE(vmp->vm_endpoint);
NOTRUNNABLE(vmc->vm_endpoint);
if(fullvm) {
vir_bytes vir;
/* making these messages writable is an optimisation
* and its return value needn't be checked.
*/
vir = arch_vir2map(vmc, msgaddr);
handle_memory(vmc, vir, sizeof(message), 1);
vir = arch_vir2map(vmp, msgaddr);
handle_memory(vmp, vir, sizeof(message), 1);
}
if((r=pt_bind(&vmc->vm_pt, vmc)) != OK)
vm_panic("fork can't pt_bind", r);
/* Inform caller of new child endpoint. */
msg->VMF_CHILD_ENDPOINT = vmc->vm_endpoint;
SANITYCHECK(SCL_FUNCTIONS);
return OK;
}