The second step in creating a thread library.

Utcb support has beed added. It has the same drawback as in the stack support:
the area in questen has to be already mapped-in. There is some basic
infrastructure for utcb to support mapping but it is far from being complete.
MAPPING_ENABLE symbolic constant controls this behaviour.

There are also some minor fixes for the stack support and the utcb common helper
routines.

conts/libl4thread/include/l4thread/addr.h

@@ -18,8 +18,9 @@ struct address_pool {
 int address_pool_init_with_idpool(struct address_pool *pool,
 				  struct id_pool *idpool,
 				  unsigned long start, unsigned long end);
-int address_pool_init(struct address_pool *pool, unsigned long start,
-		      unsigned long end);
+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);
 

conts/libl4thread/include/l4thread/thread.h

@@ -6,6 +6,8 @@
 #ifndef __LIB_THREAD_H__
 #define __LIB_THREAD_H__
 
+#include "utcb.h"
+
 #define STACK_TOP_ADDR(stack)	((unsigned long)(stack))
 #define STACK_BOTTOM_ADDR(stack) \
 			((unsigned long)((stack) + (sizeof(stack))))

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

@@ -0,0 +1,25 @@
+/*
+ * UTCB handling common helper routines
+ *
+ * Copyright (C) 2009 B Labs Ltd.
+ */
+#ifndef __UTCB_COMMON_H__
+#define __UTCB_COMMON_H__
+
+#include <l4/lib/list.h>
+
+struct utcb_desc {
+	struct link list;
+	unsigned long utcb_base;
+	struct id_pool *slots;
+};
+
+int utcb_pool_init(unsigned long utcb_start, unsigned long utcb_end);
+
+unsigned long utcb_new_slot(struct utcb_desc *desc);
+int utcb_delete_slot(struct utcb_desc *desc, unsigned long address);
+
+struct utcb_desc *utcb_new_desc(void);
+int utcb_delete_desc(struct utcb_desc *desc);
+
+#endif /* __UTCB_COMMON_H__ */

conts/libl4thread/include/l4thread/utcb.h

@@ -3,23 +3,39 @@
  *
  * Copyright (C) 2009 B Labs Ltd.
  */
-#ifndef __UTCB_H__
-#define __UTCB_H__
+#ifndef __LIB_UTCB_H__
+#define __LIB_UTCB_H__
 
-#include <l4/lib/list.h>
+#include "utcb-common.h"
 
-struct utcb_desc {
-	struct link list;
-	unsigned long utcb_base;
-	struct id_pool *slots;
+#define UTCB_START_ADDR(utcb)	((unsigned long)(utcb))
+#define UTCB_END_ADDR(utcb) \
+			((unsigned long)((utcb) + (sizeof(utcb))))
+
+int set_utcb_params(unsigned long utcb_start_addr,
+			unsigned long utcb_end_addr);
+
+//#define MAPPING_ENABLE
+
+#if defined(MAPPING_ENABLE)
+
+#define IS_UTCB_SETUP()		(utcb_table_ptr)
+
+struct utcb_entry *utcb_table_ptr;
+
+struct utcb_entry {
+	struct utcb_desc *udesc;
+	unsigned long utcb_phys_base;
 };
 
-int utcb_pool_init(unsigned long utcb_start, unsigned long utcb_end);
+unsigned long get_utcb_addr(struct task_ids *parent_id, struct task_ids *child_id);
+#else /* !MAPPING_ENABLE */
 
-unsigned long utcb_new_slot(struct utcb_desc *desc);
-int utcb_delete_slot(struct utcb_desc *desc, unsigned long address);
+#define IS_UTCB_SETUP()		(udesc_ptr)
 
-struct utcb_desc *utcb_new_desc(void);
-int utcb_delete_desc(struct utcb_desc *desc);
+struct utcb_desc *udesc_ptr;
 
-#endif /* __UTCB_H__ */
+unsigned long get_utcb_addr(void);
+#endif /* MAPPING_ENABLE */
+
+#endif /* __LIB_UTCB_H__ */

conts/libl4thread/src/addr.c

@@ -22,9 +22,11 @@ int address_pool_init_with_idpool(struct address_pool *pool,
 	return 0;
 }
 
-int address_pool_init(struct address_pool *pool, unsigned long start, unsigned long end)
+int address_pool_init(struct address_pool *pool,
+			unsigned long start, unsigned long end,
+			int size)
 {
-	if ((pool->idpool = id_pool_new_init(__pfn(end - start))) < 0)
+	if ((pool->idpool = id_pool_new_init((end - start) / size)) < 0)
 		return (int)pool->idpool;
 	pool->start = start;
 	pool->end = end;

conts/libl4thread/src/thread.c

@@ -8,6 +8,7 @@
 #include <l4lib/exregs.h>
 #include <l4/api/thread.h>
 #include <l4/api/errno.h>
+#include <utcb.h>
 
 /* Symbolic constants and macros */
 #define STACK_PTR(addr)		align((addr - 1), 8)
@@ -26,11 +27,18 @@ int set_stack_params(unsigned long stack_top_addr,
 			unsigned long stack_bottom_addr,
 			unsigned long stack_size)
 {
+	/* Ensure that arguments are valid. */
 	if (IS_STACK_SETUP()) {
 		printf("libl4thread: You have already called: %s. Simply, "
 			"this will have no effect!\n", __FUNCTION__);
 		return -EPERM;
 	}
+	if (!stack_top_addr || !stack_bottom_addr) {
+		printf("libl4thread: stack address range cannot contain "
+			"0x00000000 as a start and/or end address(es)!\n");
+		return -EINVAL;
+	}
+	// FIXME: Aligning should be taken into account.
         /*
 	 * Stack grows downward so the top of the stack will have
 	 * the lowest numbered address.
@@ -44,12 +52,15 @@ int set_stack_params(unsigned long stack_top_addr,
 		printf("libl4thread: Stack size cannot be zero!\n");
 		return -EINVAL;
 	}
-	/* stack_size at least must be equal to the difference */
+	/* stack_size at least must be equal to the difference. */
 	if ((stack_bottom_addr - stack_top_addr) < stack_size) {
 		printf("libl4thread: the given range size is lesser than "
-			"the stack size!\n");
+			"the stack size(0x%x)!\n", stack_size);
 		return -EINVAL;
 	}
+	/* Arguments passed the validity tests. */
+
+	/* Initialize internal variables */
 	lib_stack_bot_addr = stack_bottom_addr;
 	lib_stack_top_addr = stack_top_addr;
 	lib_stack_size = stack_size;
@@ -61,13 +72,15 @@ int thread_create(struct task_ids *ids, unsigned int flags,
 			int (*func)(void *), void *arg)
 {
 	struct exregs_data exregs;
+	unsigned long utcb_addr;
 	int err;
 
 	/* A few controls before granting access to thread creation */
-	if (!IS_STACK_SETUP()) {
-		printf("libl4thread: Stack has not been set up. Before "
-			"calling thread_create, set_stack_params "
-			"has to be called!\n");
+	if (!IS_STACK_SETUP() || !IS_UTCB_SETUP()) {
+		printf("libl4thread: Stack and/or utcb have not been set up. "
+			"Before calling thread_create, set_stack_params "
+			"and/or set_utcb_params have to be called with valid "
+			"arguments!\n");
 		return -EPERM;
 	}
 
@@ -85,6 +98,12 @@ int thread_create(struct task_ids *ids, unsigned int flags,
 		return -EINVAL;
 	}
 
+	/* Get a utcb addr for this thread */
+	if (!(utcb_addr = get_utcb_addr())) {
+		printf("libl4thread: No utcb address left!\n");
+		return -ENOMEM;
+	}
+
 	/* Get parent's ids */
 	l4_getid(ids);
 
@@ -99,6 +118,7 @@ int thread_create(struct task_ids *ids, unsigned int flags,
 	memset(&exregs, 0, sizeof(exregs));
 	exregs_set_stack(&exregs, STACK_PTR(lib_stack_bot_addr));
 	exregs_set_pc(&exregs, (unsigned long)setup_new_thread);
+	exregs_set_utcb(&exregs, (unsigned long)utcb_addr);
 
 	if ((err = l4_exchange_registers(&exregs, ids->tid)) < 0) {
 		printf("libl4thread: l4_exchange_registers failed with "

conts/libl4thread/src/utcb-common.c

@@ -0,0 +1,89 @@
+/*
+ * UTCB management in Codezero
+ *
+ * Copyright © 2009 B Labs Ltd
+ */
+#include <stdio.h>
+#include <addr.h>
+#include <utcb-common.h>
+#include <malloc/malloc.h>
+
+/* Globally disjoint utcb virtual region pool */
+static struct address_pool utcb_region_pool;
+
+int utcb_pool_init(unsigned long utcb_start, unsigned long utcb_end)
+{
+	int err;
+
+	/* Initialise the global utcb virtual address pool */
+	if ((err = address_pool_init(&utcb_region_pool,
+					utcb_start, utcb_end,
+					UTCB_SIZE) < 0)) {
+		printf("UTCB address pool initialisation failed.\n");
+		return err;
+	}
+
+	return 0;
+}
+
+static inline void *utcb_new_address(int npages)
+{
+	return address_new(&utcb_region_pool, npages);
+}
+
+static inline int utcb_delete_address(void *utcb_address, int npages)
+{
+	return address_del(&utcb_region_pool, utcb_address, npages);
+}
+
+/* Return an empty utcb slot in this descriptor */
+unsigned long utcb_new_slot(struct utcb_desc *desc)
+{
+	int slot;
+
+	if ((slot = id_new(desc->slots)) < 0)
+		return 0;
+	else
+		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;
+}
+
+struct utcb_desc *utcb_new_desc(void)
+{
+	struct utcb_desc *d;
+
+	/* Allocate a new descriptor */
+	if (!(d	= kzalloc(sizeof(*d))))
+		return 0;
+
+	link_init(&d->list);
+
+	/* We currently assume UTCB is smaller than PAGE_SIZE */
+	BUG_ON(UTCB_SIZE > PAGE_SIZE);
+
+	/* Initialise utcb slots */
+	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);
+
+	return d;
+}
+
+int utcb_delete_desc(struct utcb_desc *desc)
+{
+	/* Return descriptor address */
+	utcb_delete_address((void *)desc->utcb_base, 1);
+
+	/* Free the descriptor */
+	kfree(desc);
+
+	return 0;
+}

conts/libl4thread/src/utcb.c

@@ -1,88 +1,168 @@
-/*
- * UTCB management in Codezero
- *
- * Copyright © 2009 B Labs Ltd
- */
 #include <stdio.h>
-#include <addr.h>
-#include <utcb.h>
+#include <l4lib/arch/syscalls.h>
+#include <l4lib/exregs.h>
+#include <errno.h>
 #include <malloc/malloc.h>
+#include <utcb.h>
 
-/* Globally disjoint utcb virtual region pool */
-static struct address_pool utcb_region_pool;
+static unsigned long utcb_end_max_addr;
 
-int utcb_pool_init(unsigned long utcb_start, unsigned long utcb_end)
+#if defined(MAPPING_ENABLE)
+static int setup_utcb_table(unsigned long utcb_start_addr,
+				unsigned long utcb_end_addr)
 {
+	unsigned long utcb_range_size;
+	unsigned long utcb_table_size;
+	int total_entry;
+
+	/*
+	 * Establish the utcb_table.
+	 *	1. Calculate the size of the table.
+	 *	2. Calculate the number of entries.
+	 *	3. Allocate it.
+	 */
+	utcb_range_size = utcb_end_addr - utcb_start_addr;
+	total_entry = utcb_range_size / UTCB_SIZE;
+	utcb_table_size = sizeof(struct utcb_entry) * total_entry;
+	if (!(utcb_table_ptr = kzalloc(utcb_table_size))) {
+		printf("libl4thread: There is not enough memory for the utcb "
+			"mapping table of size(%d)!\n", utcb_table_size);
+		return -ENOMEM;
+	}
+	return 0;
+}
+#endif
+
+static int set_utcb_addr(void)
+{
+	struct exregs_data exregs;
+	unsigned long utcb_addr;
+	struct task_ids ids;
 	int err;
 
-	/* Initialise the global utcb virtual address pool */
-	if ((err = address_pool_init(&utcb_region_pool,
-					utcb_start, utcb_end) < 0)) {
-		printf("UTCB address pool initialisation failed.\n");
+	l4_getid(&ids);
+	// FIXME: its tid must be 0.
+#if !defined(MAPPING_ENABLE)
+	udesc_ptr = utcb_new_desc();
+	utcb_addr = get_utcb_addr();
+#else
+	{
+		struct utcb_desc *udesc;
+		udesc = utcb_new_desc();
+		utcb_table_ptr[ids.tid].udesc = udesc;
+		utcb_addr = get_utcb_addr(&ids, &ids);
+	}
+#endif
+	memset(&exregs, 0, sizeof(exregs));
+	exregs_set_utcb(&exregs, (unsigned long)utcb_addr);
+
+	if ((err = l4_exchange_registers(&exregs, ids.tid)) < 0) {
+		printf("libl4thread: l4_exchange_registers failed with "
+				"(%d)!\n", err);
 		return err;
 	}
 
 	return 0;
 }
 
-static inline void *utcb_new_address(int npages)
+int set_utcb_params(unsigned long utcb_start_addr,
+			unsigned long utcb_end_addr)
 {
-	return address_new(&utcb_region_pool, npages);
-}
+	int err;
 
-static inline int utcb_delete_address(void *utcb_address, int npages)
-{
-	return address_del(&utcb_region_pool, utcb_address, npages);
-}
+	/* Ensure that arguments are valid. */
+	if (IS_UTCB_SETUP()) {
+		printf("libl4thread: You have already called: %s. Simply, "
+			"this will have no effect!\n", __FUNCTION__);
+		return -EPERM;
+	}
+	if (!utcb_start_addr || !utcb_end_addr) {
+		printf("libl4thread: utcb address range cannot contain "
+			"0x00000000 as a start and/or end address(es)!\n");
+		return -EINVAL;
+	}
+	/* Check if the start address is aligned on UTCB_SIZE. */
+	if (utcb_start_addr & !UTCB_SIZE) {
+		printf("libl4thread: utcb start address must be aligned "
+			"on UTCB_SIZE(0x%x)\n", UTCB_SIZE);
+		return -EINVAL;
+	}
+	/* The range must be a valid one. */
+	if (utcb_start_addr >= utcb_end_addr) {
+		printf("libl4thread: utcb end address must be bigger "
+			"than utcb start address!\n");
+		return -EINVAL;
+	}
+	/*
+	 * This check guarantees two things:
+	 *	1. The range must be multiple of UTCB_SIZE, at least one item.
+	 *	2. utcb_end_addr is aligned on UTCB_SIZE
+	*/
+	if ((utcb_end_addr - utcb_start_addr) % UTCB_SIZE) {
+		printf("libl4thread: the given range size must be multiple "
+			"of the utcb size(%d)!\n", UTCB_SIZE);
+		return -EINVAL;
+	}
+	/* Arguments passed the validity tests. */
 
-/* Return an empty utcb slot in this descriptor */
-unsigned long utcb_new_slot(struct utcb_desc *desc)
-{
-	int slot;
+	/* Init utcb virtual address pool */
+	utcb_pool_init(utcb_start_addr, utcb_end_addr);
 
-	if ((slot = id_new(desc->slots)) < 0)
-		return 0;
-	else
-		return desc->utcb_base + (unsigned long)slot * UTCB_SIZE;
-}
+#if defined(MAPPING_ENABLE)
+	setup_utcb_table(utcb_start_addr, utcb_end_addr);
+#endif
+	utcb_end_max_addr = utcb_end_addr;
+
+	/* The very first thread's utcb address is assigned. */
+	if ((err = set_utcb_addr()) < 0)
+		return err;
 
-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;
 }
 
-struct utcb_desc *utcb_new_desc(void)
+#if !defined(MAPPING_ENABLE)
+unsigned long get_utcb_addr(void)
 {
-	struct utcb_desc *d;
+	unsigned long utcb_addr;
 
-	/* Allocate a new descriptor */
-	if (!(d	= kzalloc(sizeof(*d))))
+	if (!(utcb_addr = utcb_new_slot(udesc_ptr))) {
+		udesc_ptr = utcb_new_desc();
+		utcb_addr = utcb_new_slot(udesc_ptr);
+	}
+
+	if (utcb_addr >= utcb_end_max_addr)
 		return 0;
 
-	link_init(&d->list);
-
-	/* We currently assume UTCB is smaller than PAGE_SIZE */
-	BUG_ON(UTCB_SIZE > PAGE_SIZE);
-
-	/* Initialise utcb slots */
-	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);
-
-	return d;
+	return utcb_addr;
 }
-
-int utcb_delete_desc(struct utcb_desc *desc)
+#else
+unsigned long get_utcb_addr(struct task_ids *parent_id,
+				struct task_ids *child_id)
 {
-	/* Return descriptor address */
-	utcb_delete_address((void *)desc->utcb_base, 1);
+	struct utcb_entry uentry;
+	unsigned long utcb_addr;
 
-	/* Free the descriptor */
-	kfree(desc);
+	/* Get the entry for this thread. */
+	uentry = utcb_table_ptr[parent_id->tid];
 
-	return 0;
+	/* Get a new utcb virtual address. */
+	if (!(utcb_addr = utcb_new_slot(uentry.udesc))) {
+		/* No slot for this desc, get a new desc. */
+		struct utcb_desc *udesc;
+		udesc = utcb_new_desc();
+		utcb_addr = utcb_new_slot(udesc);
+		uentry.udesc = udesc;
+	}
+	/* Place the entry into the utcb_table. */
+	utcb_table_ptr[child_id->tid].udesc = uentry.udesc;
+	utcb_table_ptr[parent_id->tid].udesc = uentry.udesc;
+
+	if (utcb_addr >= utcb_end_max_addr)
+		return 0;
+
+	return utcb_addr;
 }
+#endif
+
+/*void destroy_utcb(void) {}*/
+