//拷贝父进程本身所占资源给子进程
static int32_t copy_process(struct task_struct* child_thread,struct task_struct* parent_thread){
//内核缓冲区，作为父进程用户空间的数据复制到子进程用户空间的中转
void* buf_page = get_kernel_pages(1);
if(buf_page == NULL){
return -1;
}
//a 复制父进程的pcb、虚拟地址位图、内核栈到子进程
if(copy_pcb_vaddrbitmap_stack0(child_thread,parent_thread) == -1){
return -1;
}
//b 为子进程创建页表，此页表仅包括内核空间
child_thread->pgdir = create_page_dir();
if(child_thread->pgdir == NULL){
return -1;
}
//c 复制父进程进程体及用户栈给子进程
copy_body_stack3(child_thread,parent_thread,buf_page);
//d 构建子进程thread_stack和修改返回值pid
build_child_stack(child_thread);
//e 更新文件inode的打开数
update_inode_open_cnts(child_thread);
mfree_page(PF_KERNEL,buf_page,1);
return 0;
}
void do_fork_vm (process_t *parent,
process_t *child)
{
//printf ("FORK_VM: forking memory tables\n");
// Create a page directory
if (create_page_dir (child))
{
panic ("Cant setup page dir for new child!\n");
}
//printf ("FORK_VM: preparing copy on write\n");
//Setup pagetables
prepare_copy_on_write (parent, child);
//printf ("FORK_VM: setting mem-blocks\n");
//Set the vm_blocks in proc table
child->vm_code.vm_start = parent->vm_code.vm_start;
child->vm_code.vm_end = parent->vm_code.vm_end;
child->vm_code.vm_flags = parent->vm_code.vm_flags;
child->vm_data.vm_start = parent->vm_data.vm_start;
child->vm_data.vm_end = parent->vm_data.vm_end;
child->vm_data.vm_flags = parent->vm_data.vm_flags;
child->vm_stack.vm_start = parent->vm_stack.vm_start;
child->vm_stack.vm_end = parent->vm_stack.vm_end;
child->vm_stack.vm_flags = parent->vm_stack.vm_flags;
child->vm_kernel_stack.vm_start = parent->vm_kernel_stack.vm_start;
child->vm_kernel_stack.vm_end = parent->vm_kernel_stack.vm_end;
child->vm_kernel_stack.vm_flags = parent->vm_kernel_stack.vm_flags;
//printf ("FORK_VM: done\n");
}
void vm_setup_init_process (process_t *init_proc,
Elf32_Phdr *pht,
int pht_entries,
loaded_module_t *init_mod)
{
page_frame_t *stack_page;
page_frame_t *kernel_stack_page;
int i;
unsigned int data_min = 0xffffffff;
unsigned int data_max = 0;
unsigned int code_min = 0xffffffff;
unsigned int code_max = 0;
//
// Create a page directory
//
if (create_page_dir (init_proc))
{
panic ("Cant setup page dir for init task!\n");
}
//
// HAS TO CHECK PHT AND MAP ACCORDINGLY!!
//
//Get page table and insert loaded pages into it
for (i = 0; i < pht_entries; i++)
{
if (pht[i].p_flags & PF_X)
{
//It's a code entry
if (pht[i].p_memsz > PAGE_SIZE)
panic ("INIT bigger tham one page, not implemented yet!");
if (pht[i].p_memsz > 0)
{
code_max = MAX(code_max,(pht[i].p_vaddr + pht[i].p_memsz));
code_min = MIN(code_min,pht[i].p_vaddr);
map_page (init_proc,
init_mod->page_frames->page_frame_nr * PAGE_SIZE,
pht[i].p_vaddr,
PAGE_PRESENT | PAGE_USER);
}
} else
{
//It's a data entry
if (pht[i].p_memsz > PAGE_SIZE)
panic ("INIT bigger tham one page, not implemented yet!");
if (pht[i].p_memsz > 0)
{
data_max = MAX(data_max,(pht[i].p_vaddr + pht[i].p_memsz));
data_min = MIN(data_min,pht[i].p_vaddr);
map_page (init_proc,
init_mod->page_frames->page_frame_nr * PAGE_SIZE,
pht[i].p_vaddr,
PAGE_PRESENT | PAGE_WRITEABLE | PAGE_USER);
}
}
}
//Set the areas in proc table
init_proc->vm_code.vm_start = code_min;
init_proc->vm_code.vm_end = code_max;
init_proc->vm_code.vm_flags = VM_READONLY | VM_CODE;
init_proc->vm_data.vm_start = data_min;
init_proc->vm_data.vm_end = data_max;
init_proc->vm_data.vm_flags = VM_READWRITE;
//Setup a new stack page
stack_page = get_free_page ();
kernel_stack_page = get_free_page ();
init_proc->tss.ss0 = DS_SELECTOR;
init_proc->tss.esp0 = PROC_KERNEL_STACK_TOP;
init_proc->tss.ss = USER_DS_SELECTOR;
init_proc->tss.esp = USER_STACK_TOP;
map_page (init_proc,
kernel_stack_page->page_frame_nr * PAGE_SIZE,
PROC_KERNEL_STACK_TOP,
PAGE_PRESENT | PAGE_WRITEABLE | PAGE_USER);
map_page (init_proc,
stack_page->page_frame_nr * PAGE_SIZE,
USER_STACK_TOP,
PAGE_PRESENT | PAGE_WRITEABLE | PAGE_USER);
//vm addresses are linear
init_proc->vm_kernel_stack.vm_start = PROC_KERNEL_STACK_TOP & PHYS_PAGE_MASK;
init_proc->vm_kernel_stack.vm_end = (PROC_KERNEL_STACK_TOP & PHYS_PAGE_MASK) + PAGE_SIZE;
init_proc->vm_kernel_stack.vm_flags = VM_READWRITE;
init_proc->vm_stack.vm_start = USER_STACK_TOP & PHYS_PAGE_MASK;
init_proc->vm_stack.vm_end = (USER_STACK_TOP & PHYS_PAGE_MASK) + PAGE_SIZE;
init_proc->vm_stack.vm_flags = VM_READWRITE;
map_standard_pages (init_proc);
}