Merge branch 'paging-fork' of https://github.com/stv0g/eduOS into stage6

arch/x86/mm/page.c

@@ -58,6 +58,12 @@ static size_t* self[PAGE_LEVELS] = {
 	(size_t *) 0xFFFFF000
 };
 
+/** An other self-reference for page_map_copy() */
+static size_t * other[PAGE_LEVELS] = {
+	(size_t *) 0xFF800000,
+	(size_t *) 0xFFFFE000
+};
+
 /* Addresses of child/parent tables */
 #define  CHILD(map, lvl, vpn)	&map[lvl-1][vpn<<PAGE_MAP_BITS]
 #define PARENT(map, lvl, vpn)	&map[lvl+1][vpn>>PAGE_MAP_BITS]
@@ -142,6 +148,77 @@ int page_unmap(size_t viraddr, size_t npages)
 	return 0;
 }
 
+int page_map_drop()
+{
+	void traverse(int lvl, long vpn) {
+		kprintf("traverse(lvl=%d, vpn=%#lx)\n", lvl, vpn);
+
+		long stop;
+		for (stop=vpn+PAGE_MAP_ENTRIES; vpn<stop; vpn++) {
+			if (self[lvl][vpn] & PG_PRESENT) {
+				if (self[lvl][vpn] & PG_BOOT)
+					continue;
+
+				// ost-order traversal
+				if (lvl > 1)
+					traverse(lvl-1, vpn<<PAGE_MAP_BITS);
+
+				kprintf("%#lx, ", self[lvl][vpn] & PAGE_MASK);
+				//put_page(self[lvl][vpn] & PAGE_MASK);
+
+				atomic_int32_dec(&current_task->user_usage);
+			}
+		}
+	}
+
+	spinlock_irqsave_lock(&current_task->page_lock);
+
+	traverse(PAGE_LEVELS-1, 0);
+
+	spinlock_irqsave_unlock(&current_task->page_lock);
+
+	return 0;
+}
+
+int page_map_copy(size_t dest)
+{
+	int traverse(int lvl, long vpn) {
+		long stop;
+		for (stop=vpn+PAGE_MAP_ENTRIES; vpn<stop; vpn++) {
+			if (self[lvl][vpn] & PG_PRESENT) {
+				size_t phyaddr = get_pages(1);
+				if (BUILTIN_EXPECT(phyaddr, 0))
+					return -ENOMEM;
+
+		                other[lvl][vpn]  = phyaddr;
+				other[lvl][vpn] |= self[lvl][vpn] & ~PAGE_MASK;
+
+				memcpy(CHILD(other, lvl, vpn), CHILD(self, lvl, vpn), PAGE_SIZE);
+
+				// pre-order traversal
+				if (lvl)
+					traverse(lvl-1, vpn<<PAGE_MAP_BITS);
+			}
+		}
+
+		return 0;
+	}
+
+	spinlock_lock(&kslock);
+
+	// create another temporary self-reference
+	self[PAGE_LEVELS-1][PAGE_MAP_ENTRIES-2] = dest | PG_PRESENT | PG_RW;
+
+	traverse(PAGE_LEVELS-1, 0);
+
+	// remove temporary self-reference
+	self[PAGE_LEVELS-1][PAGE_MAP_ENTRIES-2] = 0;
+
+	spinlock_unlock(&kslock);
+
+	return 0;
+}
+
 void page_fault_handler(struct state *s)
 {
 	size_t viraddr = read_cr2();

include/eduos/tasks_types.h

@@ -39,7 +39,9 @@
 
 #include <eduos/stddef.h>
 #include <eduos/spinlock_types.h>
+
 #include <asm/tasks_types.h>
+#include <asm/atomic.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -73,6 +75,12 @@ typedef struct task {
 	void*			stack;
 	/// Task priority
 	uint8_t			prio;
+	/// Physical address of root page table
+	size_t				page_map;
+	/// Lock for page tables
+	spinlock_irqsave_t	page_lock;
+	/// usage in number of pages (including page map tables)
+	atomic_int32_t		user_usage;
 	/// next task in the queue
 	struct task*		next;
 	/// previous task in the queue

kernel/tasks.c

@@ -34,14 +34,17 @@
 #include <eduos/spinlock.h>
 #include <eduos/errno.h>
 #include <eduos/syscall.h>
+#include <eduos/memory.h>
+
+#include <asm/page.h>
 
 /** @brief Array of task structures (aka PCB)
  *
  * A task's id will be its position in this array.
  */
 static task_t task_table[MAX_TASKS] = { \
-		[0]                 = {0, TASK_IDLE, NULL, NULL, 0, NULL, NULL}, \
-		[1 ... MAX_TASKS-1] = {0, TASK_INVALID, NULL, NULL, 0, NULL, NULL}};
+		[0]                 = {0, TASK_IDLE, NULL, NULL, 0, 0, SPINLOCK_IRQSAVE_INIT, ATOMIC_INIT(0), NULL, NULL}, \
+		[1 ... MAX_TASKS-1] = {0, TASK_INVALID, NULL, NULL, 0, 0, SPINLOCK_IRQSAVE_INIT, ATOMIC_INIT(0), NULL, NULL}};
 
 static spinlock_irqsave_t table_lock = SPINLOCK_IRQSAVE_INIT;
 
@@ -53,7 +56,7 @@ extern const void boot_stack;
 /** @brief helper function for the assembly code to determine the current task
  * @return Pointer to the task_t structure of current task
  */
-task_t* get_current_task(void) 
+task_t* get_current_task(void)
 {
 	return current_task;
 }
@@ -118,6 +121,8 @@ static void NORETURN do_exit(int arg)
 
 	kprintf("Terminate task: %u, return value %d\n", curr_task->id, arg);
 
+        page_map_drop();
+
 	curr_task->status = TASK_FINISHED;
 	reschedule();
 
@@ -160,6 +165,8 @@ void NORETURN abort(void) {
 }
 
 /** @brief Create a task with a specific entry point
+ *
+ * @todo Dont aquire table_lock for the whole task creation.
  *
  * @param id Pointer to a tid_t struct were the id shall be set
  * @param ep Pointer to the function the task shall start with
@@ -193,6 +200,17 @@ static int create_task(tid_t* id, entry_point_t ep, void* arg, uint8_t prio)
 			task_table[i].stack = create_stack(i);
 			task_table[i].prio = prio;
 
+			spinlock_irqsave_init(&task_table[i].page_lock);
+			atomic_int32_set(&task_table[i].user_usage, 0);
+
+                        /* Allocated new PGD or PML4 and copy page table */
+                        size_t map = get_pages(1);
+			if (BUILTIN_EXPECT(map, 0))
+			        goto out;
+
+			page_map_copy(map);
+                        task_table[i].page_map = map;
+
 			if (id)
 				*id = i;
 
@@ -217,6 +235,7 @@ static int create_task(tid_t* id, entry_point_t ep, void* arg, uint8_t prio)
 		}
 	}
 
+out:
 	spinlock_irqsave_unlock(&table_lock);
 
 	return ret;