Stack recycling is added to the thread library.

Still, it does not support thread trees which have more than one level depth.

conts/libl4thread/include/l4thread/addr.h

@@ -21,7 +21,7 @@ int address_pool_init_with_idpool(struct address_pool *pool,
 int address_pool_init(struct address_pool *pool,
 			unsigned long start, unsigned long end,
 			int size);
-void *address_new(struct address_pool *pool, int npages);
-int address_del(struct address_pool *, void *addr, int npages);
+void *address_new(struct address_pool *pool, int nitems, int size);
+int address_del(struct address_pool *, void *addr, int nitems, int size);
 
 #endif /* __ADDR_H__ */

conts/libl4thread/include/l4thread/stack.h

@@ -0,0 +1,16 @@
+/*
+ * Stack region helper routines.
+ *
+ * Copyright (C) 2009 B Labs Ltd.
+ */
+#ifndef __LIB_STACK_H__
+#define __LIB_STACK_H__
+
+int stack_pool_init(unsigned long stack_start,
+			unsigned long stack_end,
+			unsigned long stack_size);
+
+void *stack_new_space(int nitems, int size);
+int stack_delete_space(void *stack_address, int nitems, int size);
+
+#endif /* __LIB_STACK_H__ */

conts/libl4thread/include/l4thread/tcb.h

@@ -19,6 +19,7 @@ struct l4t_tcb {
 	int tid;
 	struct utcb_head *utcb_head;
 	unsigned long utcb_addr;
+	unsigned long stack_addr;
 };
 
 /* This struct keeps track of all the threads handled by the thread lib. */

conts/libl4thread/include/l4thread/utcb-common.h

@@ -1,5 +1,5 @@
 /*
- * UTCB handling common helper routines
+ * UTCB handling common helper routines.
  *
  * Copyright (C) 2009 B Labs Ltd.
  */

conts/libl4thread/src/addr.c

@@ -33,21 +33,21 @@ int address_pool_init(struct address_pool *pool,
 	return 0;
 }
 
-void *address_new(struct address_pool *pool, int npages)
+void *address_new(struct address_pool *pool, int nitems, int size)
 {
-	unsigned int pfn;
+	unsigned int idx;
 
-	if ((int)(pfn = ids_new_contiguous(pool->idpool, npages)) < 0)
+	if ((int)(idx = ids_new_contiguous(pool->idpool, nitems)) < 0)
 		return 0;
 
-	return (void *)__pfn_to_addr(pfn) + pool->start;
+	return (void *)(idx * size) + pool->start;
 }
 
-int address_del(struct address_pool *pool, void *addr, int npages)
+int address_del(struct address_pool *pool, void *addr, int nitems, int size)
 {
-	unsigned long pfn = __pfn(page_align(addr) - pool->start);
+	unsigned long idx = (addr - (void *)pool->start) / size;
 
-	if (ids_del_contiguous(pool->idpool, pfn, npages) < 0) {
+	if (ids_del_contiguous(pool->idpool, idx, nitems) < 0) {
 		printf("%s: Invalid address range returned to "
 		       "virtual address pool.\n", __FUNCTION__);
 		return -1;

conts/libl4thread/src/stack.c

@@ -0,0 +1,37 @@
+/*
+ * Stack management in libl4thread.
+ *
+ * Copyright © 2009 B Labs Ltd.
+ */
+#include <stdio.h>
+#include <addr.h>
+
+/* Stack virtual region pool */
+static struct address_pool stack_region_pool;
+
+int stack_pool_init(unsigned long stack_start,
+			unsigned long stack_end,
+			unsigned long stack_size)
+{
+	int err;
+
+	/* Initialise the global stack virtual address pool. */
+	if ((err = address_pool_init(&stack_region_pool,
+					stack_start, stack_end,
+					stack_size) < 0)) {
+		printf("Stack address pool initialisation failed.\n");
+		return err;
+	}
+
+	return 0;
+}
+
+void *stack_new_space(int nitems, int size)
+{
+	return address_new(&stack_region_pool, nitems, size);
+}
+
+int stack_delete_space(void *stack_address, int nitems, int size)
+{
+	return address_del(&stack_region_pool, stack_address, nitems, size);
+}

conts/libl4thread/src/thread.c

@@ -10,6 +10,7 @@
 #include <l4/api/errno.h>
 #include <malloc/malloc.h>
 #include <utcb.h>
+#include <stack.h>
 
 /* Symbolic constants and macros */
 #define IS_STACK_SETUP()	(lib_stack_size)
@@ -18,8 +19,6 @@
 extern void setup_new_thread(void);
 
 /* Static variable definitions */
-static unsigned long lib_stack_top_addr;
-static unsigned long lib_stack_bot_addr;
 static unsigned long lib_stack_size;
 
 /* Function definitions */
@@ -60,11 +59,12 @@ int set_stack_params(unsigned long stack_top,
 	}
 	/* Arguments passed the validity tests. */
 
-	/* Initialize internal variables */
-	lib_stack_bot_addr = stack_bottom;
-	lib_stack_top_addr = stack_top;
+	/* Initialize internal variables. */
 	lib_stack_size = stack_size;
 
+	/* Init stack virtual address pool. */
+	stack_pool_init(stack_top, stack_bottom, stack_size);
+
 	return 0;
 }
 
@@ -75,6 +75,7 @@ int l4thread_create(struct task_ids *ids, unsigned int flags,
 	unsigned long utcb_addr;
 	struct l4t_tcb *parent, *child;
 	int err;
+	unsigned long stack_top_addr, stack_bot_addr;
 
 	/* A few controls before granting access to thread creation */
 	// FIXME: check if utcb region is setup
@@ -84,11 +85,7 @@ int l4thread_create(struct task_ids *ids, unsigned int flags,
 		return -EPERM;
 	}
 
-	/* Is there enough stack space for the new thread? */
-	if (lib_stack_top_addr >= lib_stack_bot_addr) {
-		printf("libl4thread: No stack space left.\n");
-		return -ENOMEM;
-	}
+	// FIXME: Check if there is enough stack space
 
 	// FIXME: Check if there is enough utcb space
 
@@ -110,7 +107,7 @@ int l4thread_create(struct task_ids *ids, unsigned int flags,
 		return -ENOMEM;
 	}
 
-	/* Get a utcb addr for this thread */
+	/* Get a utcb addr. */
 	if (!(utcb_addr = get_utcb_addr(child))) {
 		printf("libl4thread: No utcb address left.\n");
 		// FIXME: Check if there is any memory leak
@@ -128,9 +125,14 @@ int l4thread_create(struct task_ids *ids, unsigned int flags,
 		return err;
 	}
 
+	/* Get a stack space and calculate the bottom addr of the stack. */
+	stack_top_addr = (unsigned long)stack_new_space(1, lib_stack_size);
+	stack_bot_addr = stack_top_addr + lib_stack_size;
+	child->stack_addr = stack_top_addr;
+
 	/* Setup new thread pc, sp, utcb */
 	memset(&exregs, 0, sizeof(exregs));
-	exregs_set_stack(&exregs, align((lib_stack_bot_addr - 1), 8));
+	exregs_set_stack(&exregs, align((stack_bot_addr - 1), 8));
 	exregs_set_pc(&exregs, (unsigned long)setup_new_thread);
 	exregs_set_utcb(&exregs, (unsigned long)utcb_addr);
 
@@ -142,13 +144,11 @@ int l4thread_create(struct task_ids *ids, unsigned int flags,
 	}
 
 	/* First word of new stack is arg */
-	((unsigned long *)align((lib_stack_bot_addr - 1), 8))[0] =
-					(unsigned long)arg;
+	((unsigned long *)align((stack_bot_addr - 1), 8))[0] =
+						(unsigned long)arg;
 	/* Second word of new stack is function address */
-	((unsigned long *)align((lib_stack_bot_addr - 1), 8))[-1] =
-					(unsigned long)func;
-	/* Update the stack address */
-	lib_stack_bot_addr -= lib_stack_size;
+	((unsigned long *)align((stack_bot_addr - 1), 8))[-1] =
+						(unsigned long)func;
 
 	/* Add child to the global task list */
 	child->tid = ids->tid;
@@ -174,6 +174,9 @@ void l4thread_kill(struct task_ids *ids)
 	/* Delete the utcb address. */
 	delete_utcb_addr(task);
 
+	/* Delete the stack region. */
+	stack_delete_space((void *)task->stack_addr, 1, lib_stack_size);
+
 	/* Remove child from the global task list. */
 	l4t_global_remove_task(task);
 

conts/libl4thread/src/utcb-common.c

@@ -1,7 +1,7 @@
 /*
- * UTCB management in Codezero
+ * UTCB management in libl4thread.
  *
- * Copyright © 2009 B Labs Ltd
+ * Copyright © 2009 B Labs Ltd.
  */
 #include <stdio.h>
 #include <addr.h>
@@ -26,14 +26,14 @@ int utcb_pool_init(unsigned long utcb_start, unsigned long utcb_end)
 	return 0;
 }
 
-static inline void *utcb_new_address(int npages)
+static inline void *utcb_new_address(int nitems)
 {
-	return address_new(&utcb_region_pool, npages);
+	return address_new(&utcb_region_pool, nitems, PAGE_SIZE);
 }
 
-static inline int utcb_delete_address(void *utcb_address, int npages)
+static inline int utcb_delete_address(void *utcb_address, int nitems)
 {
-	return address_del(&utcb_region_pool, utcb_address, npages);
+	return address_del(&utcb_region_pool, utcb_address, nitems, PAGE_SIZE);
 }
 
 /* Return an empty utcb slot in this descriptor */

conts/libl4thread/src/utcb.c

@@ -128,7 +128,7 @@ int set_utcb_params(unsigned long utcb_start, unsigned long utcb_end)
 	/*
 	 * This check guarantees two things:
 	 *	1. The range must be multiple of UTCB_SIZE, at least one item.
-	 *	2. utcb_end is aligned on UTCB_SIZE
+	 *	2. utcb_end is aligned on UTCB_SIZE.
 	 */
 	if ((utcb_end - utcb_start) % UTCB_SIZE) {
 		printf("libl4thread: The given range size must be multiple "
@@ -137,7 +137,7 @@ int set_utcb_params(unsigned long utcb_start, unsigned long utcb_end)
 	}
 	/* Arguments passed the validity tests. */
 
-	/* Init utcb virtual address pool */
+	/* Init utcb virtual address pool. */
 	utcb_pool_init(utcb_start, utcb_end);
 
 	/* The very first thread's utcb address is assigned. */