Added utcb create/destroy and better reorganized calls to them.

tasks/mm0/include/lib/idpool.h

@@ -14,6 +14,7 @@ struct id_pool *id_pool_new_init(int mapsize);
 int id_new(struct id_pool *pool);
 int id_del(struct id_pool *pool, int id);
 int id_get(struct id_pool *pool, int id);
+int id_is_empty(struct id_pool *pool);
 int ids_new_contiguous(struct id_pool *pool, int numids);
 int ids_del_contiguous(struct id_pool *pool, int first, int numids);
 

tasks/mm0/src/exit.c

@@ -8,6 +8,7 @@
 #include <file.h>
 #include <exit.h>
 #include <test.h>
+#include <utcb.h>
 #include <vm_area.h>
 #include <syscalls.h>
 #include <l4lib/arch/syslib.h>
@@ -92,10 +93,6 @@ int execve_recycle_task(struct tcb *new, struct tcb *orig)
 	/* Copy shared page */
 	new->shared_page = orig->shared_page;
 
-	/* Copy utcb descriptors and unique utcb */
-	new->utcb_head = orig->utcb_head;
-	new->utcb_address = orig->utcb_address;
-
 	/* Copy parent relationship */
 	BUG_ON(new->parent);
 	new->parent = orig->parent;
@@ -104,6 +101,9 @@ int execve_recycle_task(struct tcb *new, struct tcb *orig)
 	/* Flush all IO on task's files and close fds */
 	task_close_files(orig);
 
+	/* Destroy task's utcb slot */
+	task_destroy_utcb(orig);
+
 	/* Vfs still knows the thread */
 
 	/* Keep the shared page on vfs */
@@ -132,6 +132,9 @@ void do_exit(struct tcb *task, int status)
 	/* Flush all IO on task's files and close fds */
 	task_close_files(task);
 
+	/* Destroy task's utcb slot */
+	task_destroy_utcb(task);
+
 	/* Tell vfs that task is exiting */
 	vfs_notify_exit(task, status);
 

tasks/mm0/src/lib/idpool.c

@@ -78,3 +78,11 @@ int id_get(struct id_pool *pool, int id)
 		return id;
 }
 
+int id_is_empty(struct id_pool *pool)
+{
+	for (int i = 0; i < pool->nwords; i++)
+		if (pool->bitmap[i])
+			return 0;
+	return 1;
+}
+

tasks/mm0/src/task.c

@@ -7,29 +7,32 @@
 #include <l4/config.h>
 #include <l4/types.h>
 #include <l4/lib/list.h>
+#include <l4/lib/math.h>
 #include <l4/api/thread.h>
 #include <l4/api/kip.h>
 #include <l4/api/errno.h>
 #include INC_GLUE(memory.h)
+
 #include <l4lib/arch/syscalls.h>
 #include <l4lib/arch/syslib.h>
 #include <l4lib/arch/utcb.h>
 #include <l4lib/ipcdefs.h>
 #include <l4lib/exregs.h>
-#include <l4/lib/math.h>
+
 #include <lib/addr.h>
 #include <lib/malloc.h>
+
 #include <init.h>
 #include <string.h>
 #include <vm_area.h>
 #include <memory.h>
+#include <globals.h>
 #include <file.h>
 #include <task.h>
 #include <exec.h>
 #include <shm.h>
 #include <mmap.h>
 #include <boot.h>
-#include <globals.h>
 #include <test.h>
 #include <utcb.h>
 
@@ -150,6 +153,17 @@ int task_free_resources(struct tcb *task)
 		kfree(task->vm_area_head);
 	}
 
+	/*
+	 * Threads may share utcb chain
+	 */
+	if (!(--task->utcb_head->tcb_refs)) {
+		/* UTCBs must have been deleted explicitly */
+		BUG_ON(!list_empty(&task->utcb_head->list));
+
+		/* Free the head */
+		kfree(task->utcb_head);
+	}
+
 	return 0;
 }
 
@@ -269,9 +283,6 @@ int copy_tcb(struct tcb *to, struct tcb *from, unsigned int flags)
 		 */
 	}
 
-	/* Set up a new utcb for new thread */
-	task_setup_utcb(to);
-
 	/* Copy all file descriptors */
 	if (flags & TCB_SHARED_FILES) {
 		to->files = from->files;
@@ -336,6 +347,10 @@ struct tcb *task_create(struct tcb *parent, struct task_ids *ids,
 	if (parent) {
 		copy_tcb(task, parent, share_flags);
 
+		/* Set up a new utcb for new thread */
+		task_setup_utcb(task);
+
+
 		/* Set up parent-child relationship */
 		if ((share_flags & TCB_SHARED_PARENT) ||
 		    (share_flags & TCB_SHARED_TGROUP)) {
@@ -557,10 +572,12 @@ int task_mmap_segments(struct tcb *task, struct vm_file *file, struct exec_file_
 		return err;
 	}
 
+	/* Get a new utcb slot for new task */
+	task_setup_utcb(task);
+
 	/*
-	 * Task already has recycled task's shared page. It will attach to it
-	 * when it starts in userspace. Task also already utilizes recycled
-	 * task's utcb.
+	 * Recycled task's shared page shm still exists. Current task will
+	 * attach to it when it starts in userspace.
 	 */
 	//if (IS_ERR(shm = shm_new((key_t)task->utcb, __pfn(DEFAULT_UTCB_SIZE))))
 	//	return (int)shm;

tasks/mm0/src/utcb.c

@@ -42,7 +42,7 @@ int utcb_delete_address(void *utcb_address, int npages)
 }
 
 /* Return an empty utcb slot in this descriptor */
-unsigned long utcb_slot(struct utcb_desc *desc)
+unsigned long utcb_new_slot(struct utcb_desc *desc)
 {
 	int slot;
 
@@ -52,6 +52,13 @@ unsigned long utcb_slot(struct utcb_desc *desc)
 		return desc->utcb_base + (unsigned long)slot * UTCB_SIZE;
 }
 
+int utcb_delete_slot(struct utcb_desc *desc, unsigned long address)
+{
+	BUG_ON(id_del(desc->slots, (address - desc->utcb_base)
+		      / UTCB_SIZE) < 0);
+	return 0;
+}
+
 unsigned long task_new_utcb_desc(struct tcb *task)
 {
 	struct utcb_desc *d;
@@ -69,13 +76,31 @@ unsigned long task_new_utcb_desc(struct tcb *task)
        d->slots = id_pool_new_init(PAGE_SIZE / UTCB_SIZE);
 
        /* Obtain a new and unique utcb base */
+	/* FIXME: Use variable size than a page */
        d->utcb_base = (unsigned long)utcb_new_address(1);
 
        /* Add descriptor to tcb's chain */
        list_add(&d->list, &task->utcb_head->list);
 
        /* Obtain and return first slot */
-       return d->utcb_base + UTCB_SIZE * id_new(d->slots);
+       return utcb_new_slot(d);
+}
+
+int task_delete_utcb_desc(struct tcb *task, struct utcb_desc *d)
+{
+	/* Unlink desc from its list */
+	list_del_init(&d->list);
+
+	/* Unmap the descriptor region */
+	do_munmap(task, d->utcb_base, 1);
+
+	/* Return descriptor address */
+	utcb_delete_address((void *)d->utcb_base, 1);
+
+	/* Free the descriptor */
+	kfree(d);
+
+	return 0;
 }
 
 /*
@@ -102,7 +127,7 @@ int task_setup_utcb(struct tcb *task)
 
 	/* Search for an empty utcb slot already allocated to this space */
 	list_for_each_entry(udesc, &task->utcb_head->list, list)
-		if ((slot = utcb_slot(udesc)))
+		if ((slot = utcb_new_slot(udesc)))
 			goto out;
 
 	/* Allocate a new utcb memory region and return its base */
@@ -118,12 +143,42 @@ out:
 			printf("UTCB: mmapping failed with %d\n", err);
 			return (int)err;
 		}
-	} else
-		printf("UTCB at 0x%x already mapped.\n", slot);
+	}
 
 	/* Assign task's utcb address */
 	task->utcb_address = slot;
+	printf("UTCB at 0x%x.\n", slot);
 
 	return 0;
 }
 
+/*
+ * Deletes a utcb slot by first deleting the slot entry, the descriptor
+ * address if emptied, the mapping of the descriptor, and the descriptor itself
+ */
+int task_destroy_utcb(struct tcb *task)
+{
+	struct utcb_desc *udesc;
+
+	printf("UTCB: Destroying 0x%x\n", task->utcb_address);
+
+	/* Find the utcb descriptor slot first */
+	list_for_each_entry(udesc, &task->utcb_head->list, list) {
+		/* FIXME: Use variable alignment than a page */
+		/* Detect matching slot */
+		if (page_align(task->utcb_address) == udesc->utcb_base) {
+
+			/* Delete slot from the descriptor */
+			utcb_delete_slot(udesc, task->utcb_address);
+
+			/* Is the desc completely empty now? */
+			if (id_is_empty(udesc->slots))
+				/* Delete the descriptor */
+				task_delete_utcb_desc(task, udesc);
+			return 0; /* Finished */
+		}
+	}
+	BUG();
+}
+
+