int do_fork(unsigned flags)
{
assert(current_task && kernel_task);
assert(running_processes < (unsigned)MAX_TASKS || MAX_TASKS == -1);
addr_t eip;
task_t *task = task_create();
page_dir_t *newspace;
if(flags & FORK_SHAREDIR)
newspace = vm_copy(current_task->pd);
else
newspace = vm_clone(current_task->pd, 0);
if(!newspace)
{
kfree((void *)task);
return -ENOMEM;
}
/* set the address space's entry for the current task.
* this is a fast and easy way to store the "what task am I" data
* that gets automatically updated when the scheduler switches
* into a new address space */
arch_specific_set_current_task(newspace, (addr_t)task);
/* Create the new task structure */
task->pd = newspace;
copy_task_struct(task, current_task, flags & FORK_SHAREDAT);
add_atomic(&running_processes, 1);
/* Set the state as usleep temporarily, so that it doesn't accidentally run.
* And then add it to the queue */
task->state = TASK_USLEEP;
tqueue_insert(primary_queue, (void *)task, task->listnode);
cpu_t *cpu = (cpu_t *)current_task->cpu;
#if CONFIG_SMP
cpu = fork_choose_cpu(current_task);
#endif
/* Copy the stack */
set_int(0);
engage_new_stack(task, current_task);
/* Here we read the EIP of this exact location. The parent then sets the
* eip of the child to this. On the reschedule for the child, it will
* start here as well. */
volatile task_t *parent = current_task;
store_context_fork(task);
eip = read_eip();
if(current_task == parent)
{
/* These last things allow full execution of the task */
task->eip=eip;
task->state = TASK_RUNNING;
task->cpu = cpu;
add_atomic(&cpu->numtasks, 1);
tqueue_insert(cpu->active_queue, (void *)task, task->activenode);
__engage_idle();
return task->pid;
}
return 0;
}
static void betterCopy(void *source, unsigned bytes, void *dest, NXStream *s) {
if (bytes < vm_page_size ||
(((unsigned)source | (unsigned)dest) & (vm_page_size - 1))) {
bcopy(source, dest, bytes);
} else {
kern_return_t ret;
ret = vm_copy(mach_task_self(), (vm_address_t)source, round_page(bytes),
(vm_address_t)dest);
if (ret != KERN_SUCCESS)
NX_RAISE(NX_streamVMError, s, (void *)ret);
}
}
PassOwnPtr<PurgeableBuffer> PurgeableBuffer::create(const char* data, size_t size)
{
if (size < minPurgeableBufferSize)
return PassOwnPtr<PurgeableBuffer>();
vm_address_t buffer = 0;
kern_return_t ret = vm_allocate(mach_task_self(), &buffer, size, VM_FLAGS_PURGABLE | VM_FLAGS_ANYWHERE | VM_TAG_FOR_WEBCORE_PURGEABLE_MEMORY);
ASSERT(ret == KERN_SUCCESS);
if (ret != KERN_SUCCESS)
return PassOwnPtr<PurgeableBuffer>();
ret = vm_copy(mach_task_self(), reinterpret_cast<vm_address_t>(data), size, buffer);
ASSERT(ret == KERN_SUCCESS);
if (ret != KERN_SUCCESS) {
vm_deallocate(mach_task_self(), buffer, size);
return PassOwnPtr<PurgeableBuffer>();
}
return adoptPtr(new PurgeableBuffer(reinterpret_cast<char*>(buffer), size));
}
static void memory_extend(register NXStream *s, int size)
{
vm_size_t new_size;
vm_offset_t new_addr;
int cur_offset;
kern_return_t ret;
new_size = (size + CHUNK_SIZE) & (~(vm_page_size - 1));
ret = vm_allocate(mach_task_self(), &new_addr, new_size, TRUE);
if (ret != KERN_SUCCESS)
NX_RAISE(NX_streamVMError, s, (void *)ret);
cur_offset = 0;
if (s->buf_base) {
int copySize;
copySize = s->buf_size;
if (copySize % vm_page_size)
copySize += vm_page_size - (copySize % vm_page_size);
ret = vm_copy(mach_task_self(),
(vm_offset_t)s->buf_base,
(vm_size_t)copySize,
(vm_offset_t)new_addr);
if (ret != KERN_SUCCESS)
NX_RAISE(NX_streamVMError, s, (void *)ret);
ret = vm_deallocate(mach_task_self(),
(vm_offset_t)s->buf_base,
(vm_size_t)s->buf_size);
if (ret != KERN_SUCCESS)
NX_RAISE(NX_streamVMError, s, (void *)ret);
cur_offset = s->buf_ptr - s->buf_base;
}
s->buf_base = (unsigned char *)new_addr;
s->buf_size = new_size;
s->buf_ptr = s->buf_base + cur_offset;
s->buf_left = new_size - size;
s->flags &= ~NX_USER_OWNS_BUF;
}
/* The most common use of realloc is to manage a buffer of unlimited size
that is grown as it fills. So we try to optimise the case where you
are growing the last object allocated to avoid copies. */
void *
realloc(void *data, size_t size)
{
void *p;
union header *addr = ((union header *) data) - 1;
vm_address_t vmaddr = (vm_address_t) addr;
vm_address_t newaddr;
vm_size_t oldsize, allocsize;
size_t tocopy;
if (data == NULL)
return malloc(size);
oldsize = addr->size;
allocsize = get_allocsize(size + sizeof(union header), NULL);
if (allocsize == oldsize)
return data;
/* Deal with every case where we don't want to do a simple
malloc+memcpy+free. Otherwise it is a "simple case" in the
comments. */
if (allocsize < oldsize) {
/* Shrinking. We favour space over time here since if time is
really important you can just not do the realloc. */
if (oldsize >= kalloc_max) {
/* Shrinking a lot. */
if (allocsize >= kalloc_max) {
(void) vm_deallocate(mach_task_self(), vmaddr + allocsize,
oldsize - allocsize);
addr->size = allocsize;
return data;
}
/* Simple case: shrinking from a whole page or pages to less
than a page. */
} else {
if (vmaddr + oldsize == kalloc_next_space) {
/* Shrinking the last item in the current page. */
kalloc_next_space = vmaddr + allocsize;
addr->size = allocsize;
return data;
}
/* Simple case: shrinking enough to fit in a smaller power
of two. */
}
tocopy = size;
} else {
/* Growing. */
if (allocsize >= kalloc_max) {
/* Growing a lot. */
if (oldsize >= kalloc_max) {
/* We could try to vm_allocate extra pages after the old
data, but vm_allocate + vm_copy is not much more
expensive than that, even if it does fragment the
address space a bit more. */
newaddr = vmaddr;
if (vm_allocate(mach_task_self(), &newaddr, allocsize,
TRUE) != KERN_SUCCESS ||
vm_copy(mach_task_self(), vmaddr, oldsize, newaddr)
!= KERN_SUCCESS)
return NULL;
(void) vm_deallocate(mach_task_self(), vmaddr, oldsize);
addr = (union header *) newaddr;
addr->size = allocsize;
return (void *) (addr + 1);
}
/* Simple case: growing from less than a page to one or more
whole pages. */
} else {
/* Growing from a within-page size to a larger within-page
size. Frequently the item being grown is the last one
allocated so try to avoid copies in that case. */
if (vmaddr + oldsize == kalloc_next_space) {
if (vmaddr + allocsize <= kalloc_end_of_space) {
kalloc_next_space = vmaddr + allocsize;
addr->size = allocsize;
return data;
} else {
newaddr = round_page(vmaddr);
if (vm_allocate(mach_task_self(), &newaddr,
vm_page_size, FALSE)
== KERN_SUCCESS) {
kalloc_next_space = vmaddr + allocsize;
kalloc_end_of_space = newaddr + vm_page_size;
addr->size = allocsize;
return (void *) (addr + 1);
}
/* Simple case: growing the last object in the page
past the end of the page when the next page is
unavailable. */
}
}
/* Simple case: growing a within-page object that is not the
last object allocated. */
}
tocopy = oldsize - sizeof(union header);
}
/* So if we get here, we can't do any better than this: */
p = malloc(size);
if (p != NULL) {
memcpy(p, data, tocopy);
free(data);
}
return p;
}
