void map_region_init(void)
{
int h;
assert(!avl_inited);
for(h = 0; h < YIELD_HASHSIZE; h++)
yielded_init(&vm_yielded_blocks[h]);
avl_inited = 1;
}
/*===========================================================================*
* 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 */
assert(vmc->vm_slot == childproc);
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;
yielded_init(&vmc->vm_yielded_blocks);
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
if(pt_new(&vmc->vm_pt) != OK) {
printf("VM: fork: pt_new failed\n");
return ENOMEM;
}
vmc->vm_flags |= VMF_HASPT;
if(fullvm) {
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);
assert(vmc->vm_heap);
}
SANITYCHECK(SCL_DETAIL);
} else {
vir_bytes sp;
struct vir_region *heap, *stack;
vir_bytes text_bytes, data_bytes, stack_bytes, parent_gap_bytes,
child_gap_bytes;
/* Get SP of new process (using parent). */
if(get_stack_ptr(vmp->vm_endpoint, &sp) != OK) {
printf("VM: fork: get_stack_ptr failed for %d\n",
vmp->vm_endpoint);
return ENOMEM;
}
/* Update size of stack segment using current SP. */
if(adjust(vmp, vmp->vm_arch.vm_seg[D].mem_len, sp) != OK) {
printf("VM: fork: adjust failed for %d\n",
vmp->vm_endpoint);
return ENOMEM;
}
/* Copy newly adjust()ed stack segment size to child. */
vmc->vm_arch.vm_seg[S] = vmp->vm_arch.vm_seg[S];
text_bytes = CLICK2ABS(vmc->vm_arch.vm_seg[T].mem_len);
data_bytes = CLICK2ABS(vmc->vm_arch.vm_seg[D].mem_len);
stack_bytes = CLICK2ABS(vmc->vm_arch.vm_seg[S].mem_len);
/* how much space after break and before lower end (which is the
* logical top) of stack for the parent
*/
parent_gap_bytes = CLICK2ABS(vmc->vm_arch.vm_seg[S].mem_vir -
vmc->vm_arch.vm_seg[D].mem_len);
/* how much space can the child stack grow downwards, below
* the current SP? The rest of the gap is available for the
* heap to grow upwards.
*/
child_gap_bytes = VM_PAGE_SIZE;
if((r=proc_new(vmc, VM_PROCSTART,
text_bytes, data_bytes, stack_bytes, child_gap_bytes, 0, 0,
CLICK2ABS(vmc->vm_arch.vm_seg[S].mem_vir +
vmc->vm_arch.vm_seg[S].mem_len), 1)) != OK) {
printf("VM: fork: proc_new failed\n");
return r;
}
if(!(heap = map_region_lookup_tag(vmc, VRT_HEAP)))
panic("couldn't lookup heap");
assert(heap->phys);
if(!(stack = map_region_lookup_tag(vmc, VRT_STACK)))
panic("couldn't lookup stack");
assert(stack->phys);
/* Now copy the memory regions. */
if(vmc->vm_arch.vm_seg[T].mem_len > 0) {
struct vir_region *text;
if(!(text = map_region_lookup_tag(vmc, VRT_TEXT)))
panic("couldn't lookup text");
assert(text->phys);
if(copy_abs2region(CLICK2ABS(vmp->vm_arch.vm_seg[T].mem_phys),
text, 0, text_bytes) != OK)
panic("couldn't copy text");
}
if(copy_abs2region(CLICK2ABS(vmp->vm_arch.vm_seg[D].mem_phys),
heap, 0, data_bytes) != OK)
panic("couldn't copy heap");
if(copy_abs2region(CLICK2ABS(vmp->vm_arch.vm_seg[D].mem_phys +
vmc->vm_arch.vm_seg[D].mem_len) + parent_gap_bytes,
stack, child_gap_bytes, stack_bytes) != OK)
panic("couldn't copy stack");
}
/* Only inherit these flags. */
vmc->vm_flags &= (VMF_INUSE|VMF_SEPARATE|VMF_HASPT);
/* inherit the priv call bitmaps */
memcpy(&vmc->vm_call_mask, &vmp->vm_call_mask, sizeof(vmc->vm_call_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) {
panic("do_fork can't sys_fork: %d", r);
}
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)
panic("fork can't pt_bind: %d", r);
/* Inform caller of new child endpoint. */
msg->VMF_CHILD_ENDPOINT = vmc->vm_endpoint;
SANITYCHECK(SCL_FUNCTIONS);
return OK;
}
