Mutex test progress

- Mutex test added. Forked tasks demonstrate produce/consumer using a
  shared mmap'ed page.
- Added l4lib assembler syscall
- Added forgotten SWI to mutex control offset in syscall page.
- Added mutex head initialization
- Contended child successfully sleeps in a waitqueue.

Issues:
- Somehow the child's produced page buffer is altered at about [4020] offset.
  Parent fails to validate buffer therefore.
- Need to add syncing to test so that parent does not unlock and lock again
  before child has a chance to lock buffer and produce.

include/l4/api/mutex.h

@@ -6,6 +6,8 @@
 #if defined (__KERNEL__)
 #define MUTEX_CONTROL_LOCK		L4_MUTEX_LOCK
 #define MUTEX_CONTROL_UNLOCK		L4_MUTEX_UNLOCK
+
+void init_mutex_queue_head(void);
 #endif
 
 #define L4_MUTEX_LOCK		0

src/api/mutex.c

@@ -24,23 +24,29 @@ struct mutex_queue {
 
 struct mutex_queue_head {
 	struct list_head list;
+
+	/*
+	 * Lock for mutex_queue create/deletion and also list add/removal.
+	 * Both operations are done jointly so a single lock is enough.
+	 */
+	struct mutex mutex_control_mutex;
 	int count;
 } mutex_queue_head;
 
-/*
+void init_mutex_queue_head(void)
- * Lock for mutex_queue create/deletion and also list add/removal.
+{
- * Both operations are done jointly so a single lock is enough.
+	memset(&mutex_queue_head, 0, sizeof (mutex_queue_head));
- */
+	INIT_LIST_HEAD(&mutex_queue_head.list);
-struct mutex mutex_control_mutex;
+	mutex_init(&mutex_queue_head.mutex_control_mutex);
-
+}
 void mutex_queue_head_lock()
 {
-	mutex_lock(&mutex_control_mutex);
+	mutex_lock(&mutex_queue_head.mutex_control_mutex);
 }
 
 void mutex_queue_head_unlock()
 {
-	mutex_unlock(&mutex_control_mutex);
+	mutex_unlock(&mutex_queue_head.mutex_control_mutex);
 }
 
 

src/arch/arm/syscall.S

@@ -30,5 +30,6 @@ BEGIN_PROC(arm_system_calls)
 	swi	0x14		@ kread			/* 0x28 */
 	swi	0x14		@ kmem_control		/* 0x2C */
 	swi	0x14		@ time			/* 0x30 */
+	swi	0x14		@ mutex_control		/* 0x34 */
 END_PROC(arm_system_calls)
 

src/glue/arm/init.c

@@ -26,6 +26,7 @@
 #include INC_PLAT(printascii.h)
 #include INC_API(syscall.h)
 #include INC_API(kip.h)
+#include INC_API(mutex.h)
 
 unsigned int kernel_mapping_end;
 
@@ -344,6 +345,7 @@ void init_tasks()
 	/* 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__);

src/glue/arm/systable.c

@@ -54,7 +54,7 @@ void syscall_init()
 	syscall_table[sys_kread_offset >> 2]		 	= (syscall_fn_t)sys_kread;
 	syscall_table[sys_kmem_control_offset >> 2]		= (syscall_fn_t)sys_kmem_control;
 	syscall_table[sys_time_offset >> 2]			= (syscall_fn_t)sys_time;
-	syscall_table[sys_mutex_control_offset >> 2]			= (syscall_fn_t)sys_mutex_control;
+	syscall_table[sys_mutex_control_offset >> 2]		= (syscall_fn_t)sys_mutex_control;
 
 	add_mapping(virt_to_phys(&__syscall_page_start),
 		    ARM_SYSCALL_PAGE, PAGE_SIZE, MAP_USR_RO_FLAGS);

tasks/libl4/src/arm/syscalls.S

@@ -197,6 +197,18 @@ BEGIN_PROC(l4_space_control)
 	ldmfd	sp!, {pc}	@ Restore original lr and return.
 END_PROC(l4_space_control)
 
+/*
+ * Locks/unlocks a userspace mutex.
+ * @r0 = mutex virtual address, @r1 = mutex operation code
+ */
+BEGIN_PROC(l4_mutex_control)
+	stmfd	sp!, {lr}
+	ldr	r12, =__l4_mutex_control
+	mov	lr, pc
+	ldr	pc, [r12]
+	ldmfd	sp!, {pc}	@ Restore original lr and return.
+END_PROC(l4_mutex_control)
+
 /*
  * Sets registers of a thread and its pager.
  * @r0 = ptr to exregs_data structure, @r1 = tid of thread.

tasks/libl4/src/init.c

@@ -55,6 +55,6 @@ void __l4_init(void)
 			(__l4_exchange_registers_t)kip->exchange_registers;
 	__l4_kmem_control =	(__l4_kmem_control_t)kip->kmem_control;
 	__l4_time =		(__l4_time_t)kip->time;
-	__l4_mutex_control=	(__l4_mutex_control_t)kip->mutex_control;
+	__l4_mutex_control =	(__l4_mutex_control_t)kip->mutex_control;
 }
 

tasks/libl4/src/mutex.c

@@ -6,6 +6,7 @@
 #include <l4lib/mutex.h>
 #include <l4lib/types.h>
 #include <l4lib/arch/syscalls.h>
+#include <l4lib/arch/syslib.h>
 
 /*
  * NOTES:

tasks/test0/include/tests.h

@@ -23,5 +23,6 @@ int dirtest(void);
 int fileio(void);
 int clonetest(void);
 int exectest(void);
+int user_mutex_test(void);
 
 #endif /* __TEST0_TESTS_H__ */

tasks/test0/main.c

@@ -52,6 +52,9 @@ void main(void)
 		ipc_full_test();
 		ipc_extended_test();
 	}
+	if (parent_of_all == getpid()) {
+		user_mutex_test();
+	}
 	exectest();
 
 	while (1)

tasks/test0/src/mutextest.c

@@ -0,0 +1,161 @@
+/*
+ * Tests for userspace mutexes
+ *
+ * Copyright (C) 2007-2009 Bahadir Bilgehan Balban
+ */
+#include <l4lib/arch/syslib.h>
+#include <l4lib/ipcdefs.h>
+#include <l4lib/mutex.h>
+#include <errno.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <tests.h>
+
+/*
+ * This structure is placed at the head of shared memory.
+ * Tasks lock and write to rest of the page. Indicate that
+ * they have run, and the later running task tests that both
+ * processes has run and no data corruption occured on page_rest.
+ */
+struct shared_page {
+	struct l4_mutex mutex;
+	int child_has_run;
+	int parent_has_run;
+	char page_rest[];
+};
+
+static struct shared_page *shared_page;
+
+/*
+ * This test forks a parent task, creates a shared memory mapping, and makes two tasks
+ * lock and write to almost the whole page 10 times with different values, and makes
+ * the tasks test that the writes are all there without any wrong values. The amount of
+ * time spent should justify a context switch and demonstrate that lock protects the
+ * region.
+ */
+int user_mutex_test(void)
+{
+	pid_t child, parent;
+	int map_size = PAGE_SIZE;
+	int buf_size;
+	void *base;
+
+	/* Get parent pid */
+	parent = getpid();
+
+
+	/*
+	 * Create a shared anonymous memory region. This can be
+	 * accessed by both parent and child after a fork.
+	 */
+	if ((int)(base = mmap(0, map_size, PROT_READ | PROT_WRITE,
+			      MAP_SHARED | MAP_ANONYMOUS, 0, 0)) < 0) {
+		printf("%s: mmap for extended ipc buffer failed: %d\n",
+			    __FUNCTION__, (int)base);
+		goto out_err;
+	} else
+		printf("mmap: Anonymous shared buffer at %p\n", base);
+
+	shared_page = base;
+
+	/* Find the buffer size */
+	buf_size = map_size - sizeof(*shared_page);
+	printf("Total buffer size: %d\n", buf_size);
+
+	/* Initialize the mutex */
+	l4_mutex_init(&shared_page->mutex);
+
+	/* Initialize buffer with unique child value */
+	printf("Child writing:\n");
+	for (int i = 0; i < buf_size; i++) {
+		shared_page->page_rest[i] = 'c';
+		printf("%c", shared_page->page_rest[i]);
+	}
+	printf("\n\n");
+
+	/* Fork the current task */
+	if ((child = fork()) < 0) {
+		printf("%s: Fork failed with %d\n", __FUNCTION__, errno);
+		goto out_err;
+	}
+
+	if (child)
+		printf("%d: Created child with pid %d\n", getpid(), child);
+	else
+		printf("Child %d running.\n", getpid());
+
+	/* Child locks and produces */
+	if (child == 0) {
+
+		for (int i = 0; i < 5; i++) {
+			/* Lock */
+			printf("Child locking page.\n");
+			l4_mutex_lock(&shared_page->mutex);
+
+			printf("Child locked page.\n");
+			/* Get sample value */
+			char val = shared_page->page_rest[0];
+
+			/* Write a unique child value to whole buffer */
+			for (int i = 0; i < buf_size; i++) {
+				/* Check sample is same in all */
+				if (shared_page->page_rest[i] != val) {
+					printf("Sample values dont match. "
+					       "page_rest[%d] = %c, "
+					       "val = %c\n", i,
+					       shared_page->page_rest[i], val);
+					goto out_err;
+				}
+				shared_page->page_rest[i] = 'c';
+			}
+			printf("Child produced.\n");
+			/* Unlock */
+			l4_mutex_unlock(&shared_page->mutex);
+			printf("Child unlocked page.\n");
+		}
+
+	/* Parent locks and consumes */
+	} else {
+		for (int i = 0; i < 5; i++) {
+			printf("Parent locking page.\n");
+
+			/* Lock the page */
+			l4_mutex_lock(&shared_page->mutex);
+			printf("Parent locked page.\n");
+
+			printf("Parent reading:\n");
+
+			/* Test and consume the page */
+			for (int i = 0; i < buf_size; i++) {
+				printf("%c", shared_page->page_rest[i]);
+				/* Test that child has produced */
+				if (shared_page->page_rest[i] != 'c') {
+					printf("Child not produced. "
+					       "page_rest[%d] = %c, "
+					       "expected = 'c'\n",
+					       i, shared_page->page_rest[i]);
+					goto out_err;
+				}
+				/* Consume the page */
+				shared_page->page_rest[i] = 'P';
+			}
+			printf("\n\n");
+			printf("Parent consumed.\n");
+			l4_mutex_unlock(&shared_page->mutex);
+			printf("Parent unlocked page.\n");
+		}
+
+		printf("USER MUTEX TEST:    -- PASSED --\n");
+	}
+	return 0;
+
+out_err:
+	printf("USER MUTEX TEST:    -- FAILED --\n");
+	return -1;
+}
+
+
+
+
+