Simplified/Cleaned up pager initialization in the kernel

src/generic/container.c

@@ -47,70 +47,6 @@ void kres_insert_container(struct container *c,
 	kres->containers.ncont++;
 }
 
-/*
- * FIXME: Remove completely. Need to be done in userspace.
- * This searches pager capabilities and if it has a virtual memory area
- * defined as a UTCB, uses the first entry as its utcb. If not, it is
- * not an error, perhaps another pager will map its utcb.
- */
-void pager_init_utcb(struct ktcb *task, struct pager *pager)
-{
-	struct capability *cap;
-
-	/* Find a virtual memory capability with UTCB map permissions */
-	list_foreach_struct(cap, &pager->cap_list.caps, list) {
-		if (cap_rtype(cap) == CAP_RTYPE_VIRTMEM &&
-		    cap->access & CAP_MAP_UTCB) {
- 			/* Use first address slot as pager's utcb */
- 			task->utcb_address = __pfn_to_addr(cap->start);
-			break;
- 		}
-	}
-}
-
-#if 0
-
-/*
- * NOTE: This is not useful because FP stores references to
- * old stack so even if stacks are copied, unwinding is not
- * possible, which makes copying pointless. If there was no
- * FP, it may make sense, but this is not tested.
- *
- * Copy current stack contents to new one,
- * and jump to that stack by modifying sp and frame pointer.
- */
-int switch_stacks(struct ktcb *task)
-{
-	volatile register unsigned int stack asm("sp");
-	volatile register unsigned int frameptr asm("fp");
-	volatile register unsigned int newstack;
-	unsigned int stack_size = (unsigned int)_bootstack - stack;
-
-	newstack = align((unsigned long)task + PAGE_SIZE - 1,
-			 STACK_ALIGNMENT);
-
-	/* Copy stack contents to new stack */
-	memcpy((void *)(newstack - stack_size),
-	       (void *)stack, stack_size);
-
-	/*
-	 * Switch to new stack, as new stack
-	 * minus currently used stack size
-	 */
-	stack = newstack - stack_size;
-
-	/*
-	 * Frame ptr is new stack minus the original
-	 * difference from start of boot stack to current fptr
-	 */
-	frameptr = newstack -
-		   ((unsigned int)_bootstack - frameptr);
-
-	/* We should be able to return safely */
-	return 0;
-}
-#endif
-
 /*
  * TODO:
  *
@@ -120,48 +56,57 @@ int switch_stacks(struct ktcb *task)
  */
 
 /*
+ * Inspects pager parameters defined in the container,
+ * and sets up an execution environment for the pager.
+ *
+ * This involves setting up pager's ktcb, space, utcb,
+ * all ids, registers, and mapping its (perhaps) first
+ * few pages in order to make it runnable.
+ *
  * The first pager initialization is a special-case
  * since it uses the current kernel pgd.
  */
-int init_first_pager(struct pager *pager,
+int init_pager(struct pager *pager,
 		     struct container *cont,
 		     pgd_table_t *current_pgd)
 {
 	struct ktcb *task;
 	struct address_space *space;
+	int first = !!current_pgd;
 
 	/*
 	 * Initialize dummy current capability list pointer
 	 * so that capability accounting can be done as normal
+	 *
+	 * FYI: We're still on bootstack instead of current's
+	 * real stack. Hence this is a dummy.
 	 */
 	current->cap_list_ptr = &pager->cap_list;
 
-	/*
+	/* New ktcb allocation is needed */
-	 * Find capability from pager's list, since
-	 * there is no ktcb, no standard path to check
-	 * per-task capability list yet.
-	 */
-	/* Use it to allocate ktcb */
 	task = tcb_alloc_init();
 
+	/* If first, manually allocate/initalize space */
+	if (first) {
+		if (!(space = alloc_space())) {
+			return -ENOMEM;
+		}
+		/* Set up space id */
+		space->spid = id_new(&kernel_resources.space_ids);
+
+		/* Initialize space structure */
+		link_init(&space->list);
+		mutex_init(&space->lock);
+		space->pgd = current_pgd;
+		address_space_attach(task, space);
+	} else {
+		/* Otherwise allocate conventionally */
+		task->space = address_space_create(0);
+	}
+
 	/* Initialize ktcb */
 	task_init_registers(task, pager->start_vma);
 
-	pager_init_utcb(task, pager);
-
-	/* Allocate space structure */
-	if (!(space = alloc_space()))
-		return -ENOMEM;
-
-	/* Set up space id */
-	space->spid = id_new(&kernel_resources.space_ids);
-
-	/* Initialize space structure */
-	link_init(&space->list);
-	mutex_init(&space->lock);
-	space->pgd = current_pgd;
-	address_space_attach(task, space);
-
 	/* Initialize container/pager relationships */
 	pager->tcb = task;
 	task->pager = pager;
@@ -192,64 +137,6 @@ int init_first_pager(struct pager *pager,
 	return 0;
 }
 
-/*
- * Inspects pager parameters defined in the container,
- * and sets up an execution environment for the pager.
- *
- * This involves setting up pager's ktcb, space, utcb,
- * all ids, registers, and mapping its (perhaps) first
- * few pages in order to make it runnable.
- */
-int init_pager(struct pager *pager, struct container *cont)
-{
-	struct ktcb *task;
-
-	/*
-	 * Initialize dummy current capability list pointer
-	 * so that capability accounting can be done as normal
-	 * FYI: We're still on bootstack instead of current's
-	 * real stack. Hence this is a dummy.
-	 */
-	current->cap_list_ptr = &pager->cap_list;
-
-	/* Use it to allocate ktcb */
-	task = tcb_alloc_init();
-
-	task_init_registers(task, pager->start_vma);
-
-	pager_init_utcb(task, pager);
-
-	task->space = address_space_create(0);
-
-	/* Initialize container/pager relationships */
-	pager->tcb = task;
-	task->pager = pager;
-	task->container = cont;
-	task->pagerid = task->tid;
-
-	task->cap_list_ptr = &pager->cap_list;
-
-	printk("%s: Mapping %lu pages from 0x%lx to 0x%lx for %s\n",
-	       __KERNELNAME__, __pfn(page_align_up(pager->memsize)),
-	       pager->start_lma, pager->start_vma, cont->name);
-
-	add_mapping_pgd(pager->start_lma, pager->start_vma,
-			page_align_up(pager->memsize),
-			MAP_USR_DEFAULT_FLAGS, TASK_PGD(task));
-
-	/* Initialize task scheduler parameters */
-	sched_init_task(task, TASK_PRIO_PAGER);
-
-	/* Give it a kick-start tick and make runnable */
-	task->ticks_left = 1;
-	sched_resume_async(task);
-
-	/* Container list that keeps all tasks */
-	tcb_add(task);
-
-	return 0;
-}
-
 /*
  * Initialize all containers with their initial set of tasks,
  * spaces, scheduler parameters such that they can be started.
@@ -259,19 +146,16 @@ int container_init_pagers(struct kernel_resources *kres,
 {
 	struct container *cont;
 	struct pager *pager;
- 	int pgidx = 0;
 
 	list_foreach_struct(cont, &kres->containers.list, list) {
 		for (int i = 0; i < cont->npagers; i++) {
 			pager = &cont->pager[i];
 
 			/* First pager initializes specially */
-			if (pgidx == 0)
+			if (i == 0)
-				init_first_pager(pager, cont,
+				init_pager(pager, cont, current_pgd);
-						 current_pgd);
 			else
-				init_pager(pager, cont);
+				init_pager(pager, cont, 0);
-			pgidx++;
 		}
 	}
 

src/generic/resource.c

@@ -477,17 +477,6 @@ int copy_container_info(struct container *c, struct container_info *cinfo)
 	return 0;
 }
 
-/*
- * TODO:
- *
- * Rearrange as follows:
- * 1.) Move realloc_page_tables to before container_init_pagers()
- * 2.) Set up dummy current cap_list_ptr right after real capability list
- * has been created. -> Think! since there are many containers!!!!!!!
- * 3.) At this point, no need to do alloc_boot_pmd(), and current->cap_list_ptr
- * is valid, so no custom alloc functions.
- */
-
 /*
  * Create real containers from compile-time created cinfo structures
  */

src/glue/arm/init.c

@@ -45,26 +45,6 @@ void init_kernel_mappings(void)
 	add_section_mapping_init(align(virt_to_phys(_start_text),SZ_1MB),
 				 align(virt_to_phys(_start_text),SZ_1MB),
 				 1, 0);
-
-#if 0
-	/* Map page table to its virtual region */
-	add_section_mapping_init(virt_to_phys(_start_kspace),
-				 (unsigned int)_start_kspace,
-				 1, 0);
-
-	/* Clean current before first time access. */
-	memset(current, 0, sizeof(struct ktcb));
-
-	/*
-	 * We are currently on the bootstack. End of bootstack would
-	 * eventually become the ktcb of the first pager. We use a
-	 * statically allocated address_space structure for the pager.
-	 */
-	current->space = &pager_space;
-
-	/* Access physical address of pager_space to assign with initial pgd */
-	((struct address_space *)virt_to_phys(current->space))->pgd = &init_pgd;
-#endif
 }
 
 void print_sections(void)
@@ -171,6 +151,9 @@ void kip_init()
 {
 	struct utcb **utcb_ref;
 
+	/*
+	 * TODO: Adding utcb size might be useful
+	 */
 	memset(&kip, 0, PAGE_SIZE);
 	memcpy(&kip, "L4\230K", 4); /* Name field = l4uK */
 	kip.api_version 	= 0xBB;
@@ -179,7 +162,6 @@ void kip_init()
 	kip.kdesc.magic		= 0xBBB;
 	kip.kdesc.version	= CODEZERO_VERSION;
 	kip.kdesc.subversion	= CODEZERO_SUBVERSION;
-	// kip.kdesc.gendate 	= (__YEAR__ << 9)|(__MONTH__ << 5)|(__DAY__);
 	strncpy(kip.kdesc.date, __DATE__, KDESC_DATE_SIZE);
 	strncpy(kip.kdesc.time, __TIME__, KDESC_TIME_SIZE);
 
@@ -254,111 +236,11 @@ void switch_to_user(struct ktcb *task)
 	jump(task);
 }
 
-#if 0
-/*
- * Initialize the pager in the system.
- *
- * The pager uses the bootstack as its ktcb, the initial kspace as its pgd,
- * (kernel pmds are shared among all tasks) and a statically allocated
- * pager_space struct for its space structure.
- */
-void init_pager(char *name, struct task_ids *ids)
-{
-	struct svc_image *taskimg = 0;
-	struct ktcb *task;
-	int task_pages;
-
-	BUG_ON(strcmp(name, __PAGERNAME__));
-	task = current;
-
-	tcb_init(task);
-
-	/*
-	 * Search the compile-time generated boot descriptor for
-	 * information on available task images.
-	 */
-	for (int i = 0; i < bootdesc->total_images; i++) {
-		if (!strcmp(name, bootdesc->images[i].name)) {
-			taskimg = &bootdesc->images[i];
-			break;
-		}
-	}
-	BUG_ON(!taskimg);
-
-	if (taskimg->phys_start & PAGE_MASK)
-		printk("Warning, image start address not page aligned.\n");
-
-	/* Calculate the number of pages the task sections occupy. */
-	task_pages = __pfn((page_align_up(taskimg->phys_end) -
-			    page_align(taskimg->phys_start)));
-	task->context.pc = INITTASK_AREA_START;
-
-	/* Stack starts one page above the end of image. */
-	task->context.sp = INITTASK_AREA_END - 8;
-	task->context.spsr = ARM_MODE_USR;
-
-	set_task_ids(task, ids);
-
-	/* Pager gets first UTCB area available by default */
-	task->utcb_address = UTCB_AREA_START;
-
-	BUG_ON(!TASK_PGD(task));
-
-	/*
-	 * This task's userspace mapping. This should allocate a new pmd, if not
-	 * existing, and a new page entry on its private pgd.
-	 */
-	add_mapping_pgd(taskimg->phys_start, INITTASK_AREA_START,
-			task_pages * PAGE_SIZE, MAP_USR_DEFAULT_FLAGS,
-			TASK_PGD(task));
-	//printk("Mapping %d pages from 0x%x to 0x%x for %s\n", task_pages,
-	//       taskimg->phys_start, INITTASK_AREA_START, name);
-
-	/* Add the physical pages used by the task to the page map */
-	set_page_map(taskimg->phys_start, task_pages, 1);
-
-	/* Task's rendezvous point */
-	waitqueue_head_init(&task->wqh_send);
-	waitqueue_head_init(&task->wqh_recv);
-	waitqueue_head_init(&task->wqh_pager);
-
-	/* Global hashlist that keeps all existing tasks */
-	tcb_add(task);
-
-	/* Scheduler initialises the very first task itself */
-}
-
-void init_tasks()
-{
-	struct task_ids ids;
-
-	/* Initialise thread and space id pools */
-	thread_id_pool = id_pool_new_init(THREAD_IDS_MAX);
-	space_id_pool = id_pool_new_init(SPACE_IDS_MAX);
-	ids.tid = id_new(thread_id_pool);
-	ids.spid = id_new(space_id_pool);
-	ids.tgid = ids.tid;
-
-	/* Initialise the global task and address space lists */
-	//init_ktcb_list();
-	//init_address_space_list();
-	//init_mutex_queue_head();
-
-	printk("%s: Initialized. Starting %s as pager.\n",
-	       __KERNELNAME__, __PAGERNAME__);
-	/*
-	 * This must come last so that other tasks can copy its pgd before it
-	 * modifies it for its own specifics.
-	 */
-	// init_pager(__PAGERNAME__, &ids);
-}
-#endif
-
 void setup_dummy_current()
 {
 	/*
-	 * Initialize the beginning of last page of
+	 * Temporarily iInitialize the beginning of
-	 * stack as the current ktcb
+	 * last page of stack as the current ktcb
 	 */
 	memset(current, 0, sizeof(struct ktcb));
 
@@ -388,7 +270,7 @@ void init_finalize(struct kernel_resources *kres)
 	/* Switch to new stack */
 	stack = newstack;
 
-	/* -- Point of no stack unwinding/referencing -- */
+	/* -- Point of no stack unwinding -- */
 
 	/*
 	 * Unmap boot memory, and add it as
@@ -411,39 +293,54 @@ void init_finalize(struct kernel_resources *kres)
 	 * Start the scheduler, jumping to task
 	 */
 	scheduler_start();
-
-	/* FIXME: Make sure SP_SVC is reset in jump() */
 }
 
 void start_kernel(void)
 {
 	printascii("\n"__KERNELNAME__": start kernel...\n");
 
-	/* Print section boundaries for kernel image */
+	/*
-	// print_sections();
+	 * Initialise section mappings
-
+	 * for the kernel area
-	/* Initialise section mappings for the kernel area */
+	 */
 	init_kernel_mappings();
 
-	/* Enable virtual memory and jump to virtual addresses */
+	/*
+	 * Enable virtual memory
+	 * and jump to virtual addresses
+	 */
 	start_vm();
 
-	/* Set up a dummy current ktcb on boot stack with initial pgd */
+	/*
+	 * Set up a dummy current ktcb on
+	 * boot stack with initial pgd
+	 */
 	setup_dummy_current();
 
-	/* Initialise platform-specific page mappings, and peripherals */
+	/*
+	 * Initialise platform-specific
+	 * page mappings, and peripherals
+	 */
 	platform_init();
 
-	printk("%s: Virtual memory enabled.\n", __KERNELNAME__);
+	/* Can only print when uart is mapped */
+	printk("%s: Virtual memory enabled.\n",
+	       __KERNELNAME__);
 
-	/* Map and enable high vector page. Faults can be handled after here. */
+	/*
+	 * Map and enable high vector page.
+	 * Faults can be handled after here.
+	 */
 	vectors_init();
 
 	/* Remap 1MB kernel sections as 4Kb pages. */
 	remap_as_pages((void *)page_align(_start_kernel),
 		       (void *)page_align_up(_end_kernel));
 
-	/* Initialise kip and map for userspace access */
+	/*
+	 * Initialise kip and map
+	 * for userspace access
+	 */
 	kip_init();
 
 	/* Initialise system call page */
@@ -452,10 +349,16 @@ void start_kernel(void)
 	/* Init scheduler */
 	sched_init(&scheduler);
 
-	/* Evaluate system resources and set up resource pools */
+	/*
+	 * Evaluate system resources
+	 * and set up resource pools
+	 */
 	init_system_resources(&kernel_resources);
 
-	/* Free boot memory, jump to first task's stack and start scheduler */
+	/*
+	 * Free boot memory, switch to first
+	 * task's stack and start scheduler
+	 */
 	init_finalize(&kernel_resources);
 
 	BUG();