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https://github.com/drasko/codezero.git
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Revised task initialisation, revising mmap yet.
This commit is contained in:
Bahadir Balban
185
tasks/mm0/src/pagers.c
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185
tasks/mm0/src/pagers.c
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@@ -0,0 +1,185 @@
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/*
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* Copyright (C) 2008 Bahadir Balban
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*/
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#include <vm_area.h>
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struct page *file_page_in(struct vm_object *vm_obj, unsigned long page_offset)
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{
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struct vm_file *f = vm_object_to_file(vm_obj);
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struct page *page;
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/* The page is not resident in page cache. */
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if (!(page = find_page(vm_obj, page_offset)))
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/* Allocate a new page */
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void *paddr = alloc_page(1);
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void *vaddr = phys_to_virt(paddr);
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page = phys_to_page(paddr);
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/* Map the page to vfs task */
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l4_map(paddr, vaddr, 1, MAP_USR_RW_FLAGS, VFS_TID);
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/* Syscall to vfs to read into the page. */
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if ((err = vfs_read(f->vnum, page_offset, 1, vaddr)) < 0)
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goto out_err;
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/* Unmap it from vfs */
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l4_unmap(vaddr, 1, VFS_TID);
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/* Update vm object details */
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vm_obj->npages++;
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/* Update page details */
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spin_lock(&page->lock);
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page->count++;
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page->owner = vm_obj;
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page->offset = page_offset;
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page->virtual = 0;
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/* Add the page to owner's list of in-memory pages */
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BUG_ON(!list_empty(&page->list));
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insert_page_olist(page, vm_obj);
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spin_unlock(&page->lock);
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}
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return page;
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out_err:
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l4_unmap(vaddr, 1, VFS_TID);
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free_page(paddr);
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return PTR_ERR(err);
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}
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/*
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* This reads-in a range of pages from a file and populates the page cache
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* just like a page fault, but its not in the page fault path.
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*/
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int read_file_pages(struct vm_file *vmfile, unsigned long pfn_start,
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unsigned long pfn_end)
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{
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struct page *page;
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for (int f_offset = pfn_start; f_offset < pfn_end; f_offset++)
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vmfile->vm_obj->pager.ops->page_in(vmfile->vm_obj, f_offset);
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return 0;
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}
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/*
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* All non-mmapable char devices are handled by this.
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* VFS calls those devices to read their pages
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*/
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struct vm_pager file_pager {
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.page_in = file_page_in,
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};
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/* Returns the page with given offset in this vm_object */
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struct page *bootfile_page_in(struct vm_object *vm_obj,
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unsigned long pfn_offset)
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{
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struct vm_file *boot_file = vm_obj_to_file(vm_obj);
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struct svc_image *img = boot_file->priv_data;
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struct page *page = phys_to_page(img->phys_start +
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__pfn_to_addr(pfn_offset));
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spin_lock(&page->lock);
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page->count++;
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spin_unlock(&page->lock);
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return page;
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}
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struct vm_pager bootfile_pager {
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.page_in = bootfile_page_in,
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};
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LIST_HEAD(&boot_file_list);
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/* From bare boot images, create mappable device files */
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int init_boot_files(struct initdata *initdata)
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{
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struct svc_image *img;
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unsigned int sp, pc;
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struct tcb *task;
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struct task_ids ids;
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struct bootdesc *bd;
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struct vm_file *boot_file;
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int err;
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bd = initdata->bootdesc;
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INIT_LIST_HEAD(&initdata->boot_file_list);
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for (int i = 0; i < bd->total_images; i++) {
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img = &bd->images[i];
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boot_file = vm_file_alloc_init();
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boot_file->priv_data = img;
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boot_file->length = img->phys_end - img->phys_start;
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boot_file->pager = &bootfile_pager;
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boot_file->type = VM_FILE_BOOTFILE;
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/* Initialise the vm object */
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boot_file->vm_obj.type = VM_OBJ_FILE;
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/* Add the object to global vm_object list */
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list_add(&boot_file->vm_obj.list, &vm_object_list);
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/* Add the file to initdata's bootfile list */
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list_add(&boot_file->list, &initdata->boot_file_list);
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}
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}
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/* Returns the page with given offset in this vm_object */
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struct page *devzero_page_in(struct vm_object *vm_obj,
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unsigned long page_offset)
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{
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struct vm_file *devzero = vm_obj_to_file(vm_obj);
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struct page *zpage = devzero->priv_data;
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/* Update zero page struct. */
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spin_lock(&page->lock);
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zpage->count++;
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spin_unlock(&page->lock);
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return zpage;
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}
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struct vm_pager devzero_pager {
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.page_in = devzero_page_in,
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};
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struct vm_file *get_devzero(void)
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{
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struct vm_file *f;
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list_for_each_entry(f, &vm_file_list, list)
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if (f->type & VM_FILE_DEVZERO)
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return f;
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return 0;
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}
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int init_devzero(void)
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{
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void *zphys, *zvirt;
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struct page *zpage;
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struct vm_file *devzero;
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/* Allocate and initialise the zero page */
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zphys = alloc_page(1);
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zpage = phys_to_page(zphys);
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zvirt = l4_map_helper(zphys, 1);
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memset(zvirt, 0, PAGE_SIZE);
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l4_unmap_helper(zvirt, 1);
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zpage->count++;
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/* Allocate and initialise devzero file */
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devzero = vmfile_alloc_init();
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devzero->vm_obj.npages = ~0;
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devzero->vm_obj.pager = devzero_pager;
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devzero->vm_obj.type = VM_OBJ_FILE;
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devzero->type = VM_FILE_DEVZERO;
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devzero->priv_data = zpage;
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list_add(&devzero->vm_obj.list, &vm_object_list);
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list_add(&devzero->list, &vm_file_list);
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return 0;
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}
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