Added kernel + libl4 changes for full and extended ipc.

- Short ipc working as normal. Full/extended ipc haven't been tested.
- Added automated compilation and inclusion of test executable in test0.

include/l4/api/ipc.h

@@ -13,8 +13,8 @@
 #if defined (__KERNEL__)
 
 /* These are for internally created ipc paths. */
-int ipc_send(l4id_t to);
-int ipc_sendrecv(l4id_t to, l4id_t from);
+int ipc_send(l4id_t to, int full);
+int ipc_sendrecv(l4id_t to, l4id_t from, int full);
 
 #endif
 

include/l4/generic/space.h

@@ -42,7 +42,8 @@ void address_space_remove(struct address_space *space);
 void address_space_reference_lock();
 void address_space_reference_unlock();
 void init_address_space_list(void);
-int check_access(unsigned long vaddr, unsigned long size, unsigned int flags);
+int check_access(unsigned long vaddr, unsigned long size,
+		 unsigned int flags, int page_in);
 #endif
 
 #endif /* __SPACE_H__ */

include/l4/generic/tcb.h

@@ -26,6 +26,9 @@
 #define TASK_SUSPENDING			(1 << 1)
 #define TASK_RESUMING			(1 << 2)
 
+/* IPC resulted in a fault error (For ipcs that cannot page fault) */
+#define IPC_EFAULT			(1 << 3)
+
 /* Task states */
 enum task_state {
 	TASK_INACTIVE	= 0,

include/l4/glue/arm/message.h

@@ -83,4 +83,13 @@
 
 #include INC_GLUE(memlayout.h)
 
+#if defined (__KERNEL__)
+struct utcb {
+	u32 mr[MR_TOTAL];	/* MRs that are mapped to real registers */
+	u32 saved_tag;		/* Saved tag field for stacked ipcs */
+	u32 saved_sender;	/* Saved sender field for stacked ipcs */
+	u32 mr_rest[MR_REST];	/* Complete the utcb for up to 64 words */
+};
+#endif
+
 #endif /* __GLUE_ARM_MESSAGE_H__ */

src/api/ipc.c

@@ -1,7 +1,7 @@
 /*
  * Inter-process communication
  *
- * Copyright (C) 2007 Bahadir Balban
+ * Copyright (C) 2007-2009 Bahadir Bilgehan Balban
  */
 #include <l4/generic/tcb.h>
 #include <l4/lib/mutex.h>
@@ -14,13 +14,46 @@
 #include INC_API(syscall.h)
 #include INC_GLUE(message.h)
 
+/*
+ * ipc syscall uses an ipc_type variable and flags and send/recv
+ * details are embedded in this variable.
+ */
+#define IPC_TYPE_FLAGS_SHIFT		2
 enum IPC_TYPE {
 	IPC_INVALID = 0,
 	IPC_SEND = 1,
 	IPC_RECV = 2,
-	IPC_SENDRECV = 3
+	IPC_SENDRECV = 3,
+	IPC_SEND_FULL = 5,
+	IPC_RECV_FULL = 6,
+	IPC_SENDRECV_FULL = 7,
+	IPC_SEND_EXTENDED = 9,
+	IPC_RECV_EXTENDED = 10,
+	IPC_SENDRECV_EXTENDED = 11,
 };
 
+/* Copy full utcb region from one task to another. */
+int ipc_full_copy(struct ktcb *to, struct ktcb *from)
+{
+	struct utcb *from_utcb = (struct utcb *)from->utcb_address;
+	struct utcb *to_utcb = (struct utcb *)to->utcb_address;
+	int ret;
+
+	/* Check that utcb memory accesses won't fault us */
+	if ((ret = check_access(to->utcb_address, UTCB_SIZE,
+				MAP_SVC_RW_FLAGS, 0)) < 0)
+		return ret;
+	if ((ret = check_access(to->utcb_address, UTCB_SIZE,
+				MAP_SVC_RW_FLAGS, 0)) < 0)
+		return ret;
+
+	/* Directly copy from one utcb to another */
+	memcpy(to_utcb->mr_rest, from_utcb->mr_rest,
+	       MR_REST * sizeof(unsigned int));
+
+	return 0;
+}
+
 /*
  * Copies message registers from one ktcb stack to another. During the return
  * from system call, the registers are popped from the stack. In the future
@@ -30,10 +63,11 @@ enum IPC_TYPE {
  * L4_ANYTHREAD. This is done for security since the receiver cannot trust
  * the sender info provided by the sender task.
  */
-int ipc_msg_copy(struct ktcb *to, struct ktcb *from)
+int ipc_msg_copy(struct ktcb *to, struct ktcb *from, int full)
 {
 	unsigned int *mr0_src = KTCB_REF_MR0(from);
 	unsigned int *mr0_dst = KTCB_REF_MR0(to);
+	int ret = 0;
 
 	/* NOTE:
 	 * Make sure MR_TOTAL matches the number of registers saved on stack.
@@ -44,7 +78,11 @@ int ipc_msg_copy(struct ktcb *to, struct ktcb *from)
 	if (to->expected_sender == L4_ANYTHREAD)
 		mr0_dst[MR_SENDER] = from->tid;
 
-	return 0;
+	/* Check if full utcb copying is requested and do it */
+	if (full)
+		ret = ipc_full_copy(to, from);
+
+	return ret;
 }
 
 int sys_ipc_control(syscall_context_t *regs)
@@ -61,10 +99,11 @@ int sys_ipc_control(syscall_context_t *regs)
  */
 
 /* Interruptible ipc */
-int ipc_send(l4id_t recv_tid)
+int ipc_send(l4id_t recv_tid, int full)
 {
 	struct ktcb *receiver = tcb_find(recv_tid);
 	struct waitqueue_head *wqhs, *wqhr;
+	int ret = 0;
 
 	wqhs = &receiver->wqh_send;
 	wqhr = &receiver->wqh_recv;
@@ -89,14 +128,18 @@ int ipc_send(l4id_t recv_tid)
 		spin_unlock(&wqhs->slock);
 
 		/* Copy message registers */
-		ipc_msg_copy(receiver, current);
+		if ((ret = ipc_msg_copy(receiver, current, full)) < 0) {
+			/* Set ipc error flag in receiver */
+			BUG_ON(ret != -EFAULT);
+			receiver->flags |= IPC_EFAULT;
+		}
 
 		// printk("%s: (%d) Waking up (%d)\n", __FUNCTION__,
 		//       current->tid, receiver->tid);
 
 		/* Wake it up, we can yield here. */
 		sched_resume_sync(receiver);
-		return 0;
+		return ret;
 	}
 
 	/* The receiver is not ready and/or not expecting us */
@@ -116,12 +159,19 @@ int ipc_send(l4id_t recv_tid)
 		current->flags &= ~TASK_INTERRUPTED;
 		return -EINTR;
 	}
+
+	/* Did ipc fail with a fault error? */
+	if (current->flags & IPC_EFAULT) {
+		current->flags &= ~IPC_EFAULT;
+		return -EFAULT;
+	}
 	return 0;
 }
 
-int ipc_recv(l4id_t senderid)
+int ipc_recv(l4id_t senderid, int full)
 {
 	struct waitqueue_head *wqhs, *wqhr;
+	int ret = 0;
 
 	wqhs = &current->wqh_send;
 	wqhr = &current->wqh_recv;
@@ -154,12 +204,20 @@ int ipc_recv(l4id_t senderid)
 				task_unset_wqh(sleeper);
 				spin_unlock(&wqhr->slock);
 				spin_unlock(&wqhs->slock);
-				ipc_msg_copy(current, sleeper);
+
+				/* Copy message registers */
+				if ((ret = ipc_msg_copy(current, sleeper,
+							full)) < 0) {
+
+					/* Set ipc fault flag on sleeper */
+					BUG_ON(ret != -EFAULT);
+					sleeper->flags |= IPC_EFAULT;
+				}
 
 				// printk("%s: (%d) Waking up (%d)\n", __FUNCTION__,
 				//       current->tid, sleeper->tid);
 				sched_resume_sync(sleeper);
-				return 0;
+				return ret;
 			}
 		}
 	}
@@ -181,6 +239,13 @@ int ipc_recv(l4id_t senderid)
 		current->flags &= ~TASK_INTERRUPTED;
 		return -EINTR;
 	}
+
+	/* Did ipc fail with a fault error? */
+	if (current->flags & IPC_EFAULT) {
+		current->flags &= ~IPC_EFAULT;
+		return -EFAULT;
+	}
+
 	return 0;
 }
 
@@ -198,20 +263,22 @@ int ipc_recv(l4id_t senderid)
  * (6) System task calls ipc_send() sending the return result.
  * (7) Rendezvous occurs. Both tasks exchange mrs and leave rendezvous.
  */
-int ipc_sendrecv(l4id_t to, l4id_t from)
+int ipc_sendrecv(l4id_t to, l4id_t from, int full)
 {
 	int ret = 0;
 
 	if (to == from) {
 		/* Send ipc request */
-		ipc_send(to);
+		if ((ret = ipc_send(to, full)) < 0)
+			return ret;
 
 		/*
 		 * Get reply.
 		 * A client would block its server only very briefly
 		 * between these calls.
 		 */
-		ipc_recv(from);
+		if ((ret = ipc_recv(from, full)) < 0)
+			return ret;
 	} else {
 		printk("%s: Unsupported ipc operation.\n", __FUNCTION__);
 		ret = -ENOSYS;
@@ -225,13 +292,28 @@ static inline int __sys_ipc(l4id_t to, l4id_t from, unsigned int ipc_type)
 
 	switch (ipc_type) {
 	case IPC_SEND:
-		ret = ipc_send(to);
+		ret = ipc_send(to, 0);
 		break;
 	case IPC_RECV:
-		ret = ipc_recv(from);
+		ret = ipc_recv(from, 0);
 		break;
 	case IPC_SENDRECV:
-		ret = ipc_sendrecv(to, from);
+		ret = ipc_sendrecv(to, from, 0);
+		break;
+	case IPC_SEND_FULL:
+		ret = ipc_send(to, 1);
+		break;
+	case IPC_RECV_FULL:
+		ret = ipc_recv(from, 1);
+		break;
+	case IPC_SENDRECV_FULL:
+		ret = ipc_sendrecv(to, from, 1);
+		break;
+	case IPC_SEND_EXTENDED:
+		break;
+	case IPC_RECV_EXTENDED:
+		break;
+	case IPC_SENDRECV_EXTENDED:
 		break;
 	case IPC_INVALID:
 	default:
@@ -267,6 +349,7 @@ int sys_ipc(syscall_context_t *regs)
 {
 	l4id_t to = (l4id_t)regs->r0;
 	l4id_t from = (l4id_t)regs->r1;
+	unsigned int flags = (unsigned int)regs->r2;
 	unsigned int ipc_type = 0;
 	int ret = 0;
 
@@ -292,6 +375,9 @@ int sys_ipc(syscall_context_t *regs)
 	/* [1] for Receive, [1:0] for both */
 	ipc_type |= ((from != L4_NILTHREAD) << 1);
 
+	/* Short, full or extended ipc set here. Bits [3:2] */
+	ipc_type |= (flags & L4_IPC_FLAGS_MASK) << IPC_TYPE_FLAGS_SHIFT;
+
 	if (ipc_type == IPC_INVALID) {
 		ret = -EINVAL;
 		goto error;
@@ -302,7 +388,7 @@ int sys_ipc(syscall_context_t *regs)
 	return ret;
 
 error:
-	printk("Erroneous ipc by: %d. Err: %d\n", current->tid, ret);
+	// printk("Erroneous ipc by: %d. Err: %d\n", current->tid, ret);
 	ipc_type = IPC_INVALID;
 	return ret;
 }

src/api/kip.c

@@ -23,19 +23,19 @@ int __sys_kread(int rd, void *dest)
 	switch(rd) {
 	case KDATA_PAGE_MAP:
 		// printk("Handling KDATA_PAGE_MAP request.\n");
-		if (check_access(vaddr, sizeof(page_map), MAP_USR_RW_FLAGS) < 0)
+		if (check_access(vaddr, sizeof(page_map), MAP_USR_RW_FLAGS, 1) < 0)
 			return -EINVAL;
 		memcpy(dest, &page_map, sizeof(page_map));
 		break;
 	case KDATA_BOOTDESC:
 		// printk("Handling KDATA_BOOTDESC request.\n");
-		if (check_access(vaddr, bootdesc->desc_size, MAP_USR_RW_FLAGS) < 0)
+		if (check_access(vaddr, bootdesc->desc_size, MAP_USR_RW_FLAGS, 1) < 0)
 			return -EINVAL;
 		memcpy(dest, bootdesc, bootdesc->desc_size);
 		break;
 	case KDATA_BOOTDESC_SIZE:
 		// printk("Handling KDATA_BOOTDESC_SIZE request.\n");
-		if (check_access(vaddr, sizeof(unsigned int), MAP_USR_RW_FLAGS) < 0)
+		if (check_access(vaddr, sizeof(unsigned int), MAP_USR_RW_FLAGS, 1) < 0)
 			return -EINVAL;
 		*(unsigned int *)dest = bootdesc->desc_size;
 		break;

src/arch/arm/exception.c

@@ -58,7 +58,7 @@ void fault_ipc_to_pager(u32 faulty_pc, u32 fsr, u32 far)
 				 offsetof(syscall_context_t, r3));
 
 	/* Send ipc to the task's pager */
-	ipc_sendrecv(current->pagerid, current->pagerid);
+	ipc_sendrecv(current->pagerid, current->pagerid, 0);
 
 	/*
 	 * FIXME: CHECK TASK KILL REPLY !!!

src/generic/space.c

@@ -151,7 +151,7 @@ struct address_space *address_space_create(struct address_space *orig)
  * If its not mapped-in, it generates a page-in request to the thread's
  * pager. If fault hasn't cleared, aborts.
  */
-int check_access(unsigned long vaddr, unsigned long size, unsigned int flags)
+int check_access(unsigned long vaddr, unsigned long size, unsigned int flags, int page_in)
 {
 	int err;
 
@@ -159,20 +159,17 @@ int check_access(unsigned long vaddr, unsigned long size, unsigned int flags)
 	if (size >= USER_AREA_SIZE)
 		return -EINVAL;
 
-	/* Check if in user range, but this is more up to the pager to decide */
-	if (current->tid == PAGER_TID) {
-		if (!(vaddr >= INITTASK_AREA_START && vaddr < INITTASK_AREA_END))
-			return -EINVAL;
-	} else {
-		if (!(vaddr >= USER_AREA_START && vaddr < USER_AREA_END))
-			return -EINVAL;
+	/* Check if the address is mapped with given flags */
+	if (!check_mapping(vaddr, size, flags)) {
+		/* Is a page in requested? */
+		if (page_in) {
+			/* Ask pager if paging in is possible */
+			if((err = pager_pagein_request(vaddr, size, flags)) < 0)
+				return err;
+		} else
+			return -EFAULT;
 	}
 
-	/* If not mapped, ask pager whether this is possible */
-	if (!check_mapping(vaddr, size, flags))
-		if((err = pager_pagein_request(vaddr, size, flags)) < 0)
-			return err;
-
 	return 0;
 }
 

src/generic/time.c

@@ -77,7 +77,7 @@ int sys_time(syscall_context_t *args)
 	int set = (int)args->r1;
 	int retries = 20;
 
-	if (check_access((unsigned long)tv, sizeof(*tv), MAP_USR_RW_FLAGS) < 0)
+	if (check_access((unsigned long)tv, sizeof(*tv), MAP_USR_RW_FLAGS, 1) < 0)
 		return -EINVAL;
 
 	/* Get time */

tasks/libl4/src/arm/syscalls.S

@@ -53,7 +53,7 @@ END_PROC(l4_kread)
 
 /*
  * For clone() we need special assembler handling
- * Same signature as ipc(): @r0 = to, @r1 = from
+ * Same signature as ipc(): @r0 = to, @r1 = from @r2 = flags
  *
  * NOTE: Note that this breaks l4 system call interface,
  * this should be moved elsewhere and modified using existing l4 mechanisms.
@@ -62,6 +62,11 @@ BEGIN_PROC(arch_clone)
 	stmfd	sp!, {r4-r8,lr}		@ Save context.
 	utcb_address r12		@ Get utcb address.
 	ldmia	r12!, {r3-r8}		@ Load 6 Message registers from utcb. MR0-MR5
+
+	cmp	r2, #0
+1:
+	bne	1b
+
 	ldr	r12, =__l4_ipc
 	mov	lr, pc
 	ldr	pc, [r12]		@ Perform the ipc()
@@ -101,6 +106,11 @@ BEGIN_PROC(l4_ipc)
 	stmfd	sp!, {r4-r8,lr}		@ Save context.
 	utcb_address r12		@ Get utcb address.
 	ldmia	r12!, {r3-r8}		@ Load 6 Message registers from utcb. MR0-MR5
+
+	cmp	r2, #0
+1:
+	bne	1b
+
 	ldr	r12, =__l4_ipc
 	mov	lr, pc
 	ldr	pc, [r12]

tasks/libposix/fork.c

@@ -52,7 +52,7 @@ int fork(void)
 	return ret;
 }
 
-extern int arch_clone(l4id_t to, l4id_t from);
+extern int arch_clone(l4id_t to, l4id_t from, unsigned int flags);
 
 int clone(int (*fn)(void *), void *child_stack, int flags, void *arg, ...)
 {
@@ -74,7 +74,7 @@ int clone(int (*fn)(void *), void *child_stack, int flags, void *arg, ...)
 	write_mr(L4SYS_ARG1, flags);
 
 	/* Perform an ipc but with different return logic. See implementation. */
-	if ((ret = arch_clone(PAGER_TID, PAGER_TID)) < 0) {
+	if ((ret = arch_clone(PAGER_TID, PAGER_TID, 0)) < 0) {
 		print_err("%s: L4 IPC Error: %d.\n", __FUNCTION__, ret);
 		return ret;
 	}

tasks/test0/SConstruct

@@ -68,11 +68,42 @@ env = Environment(CC = 'arm-none-linux-gnueabi-gcc',
 		  CPPFLAGS = "-D__USERSPACE__",
 		  CPPPATH = ['#include', libl4_incpath, libposix_incpath, kernel_incpath])
 
+
+test_exec_ld_script = "include/test_exec_linker.lds"
+# The kernel build environment:
+test_exec_env = Environment(CC = 'arm-none-linux-gnueabi-gcc',
+		  # We don't use -nostdinc because sometimes we need standard headers,
+		  # such as stdarg.h e.g. for variable args, as in printk().
+		  CCFLAGS = ['-O3', '-nostdlib', '-ffreestanding', '-std=gnu99', '-Wall', '-Werror'],
+		  LINKFLAGS = ['-nostdlib', '-T' + test_exec_ld_script, "-L" + libc_libpath, "-L" + libl4_path, \
+				  '-L' + libposix_libpath],
+		  ASFLAGS = ['-D__ASSEMBLY__'],
+		  PROGSUFFIX = '.axf',			# The suffix to use for final executable
+		  ENV = {'PATH' : os.environ['PATH']},	# Inherit shell path
+		  LIBS = [libc_name, 'gcc', libc_name, 'libl4', 'libposix', libc_name],
+		  CPPFLAGS = "-D__USERSPACE__",
+		  CPPPATH = ['#include', libl4_incpath, libposix_incpath, kernel_incpath])
+
 src = [glob("src/*.c"), glob("*.c"), glob("*.S"), glob("src/arch/arm/*.c"), glob("../libcont/*.c")]
 objs = env.Object(src)
 physical_base = env.Command(physical_base_ld_script, prev_image, get_physical_base)
 crt0_copied = env.Command("crt0.o", libc_crt0, copy_crt0)
 
+test_exec_src = [glob("src/test_exec/*.c")]
+test_exec_objs = test_exec_env.Object(test_exec_src)
+test_exec_name = "test_exec"
+test_exec = test_exec_env.Program(test_exec_name, test_exec_objs + [crt0_copied])
+test_exec_env.Alias(test_exec_name, test_exec)
+
+env.Depends(objs, test_exec)
 task = env.Program(task_name, objs + [crt0_copied])
 env.Alias(task_name, task)
+
+# I find this to be a BUG related to SCons. SCons is still good compared to
+# notoriously horrible makefiles, but it could have been better.
+# if test_exec doesn't depend on physical_base, test_exec is compiled but
+# task complains that physical_base is not there. However we already declared
+# its dependency below.
+
+env.Depends(test_exec, physical_base)
 env.Depends(task, physical_base)

tasks/test0/include/linker.lds

@@ -33,9 +33,9 @@ SECTIONS
 	.data : AT (ADDR(.data) - offset)
 	{
 		. = ALIGN(4K);
-		_start_test1 = .;
-		*(.test1)
-		_end_test1 = .;
+		_start_test_exec = .;
+		*(.testexec)
+		_end_test_exec = .;
 		*(.data)
 	}
 	.bss : AT (ADDR(.bss) - offset) { *(.bss) }

tasks/test0/include/test_exec_linker.lds

@@ -0,0 +1,37 @@
+/*
+ * Simple linker script for userspace or svc tasks.
+ *
+ * Copyright (C) 2007 Bahadir Balban
+ */
+
+/*
+ * The only catch with this linker script is that everything
+ * is linked starting at virtual_base, and loaded starting
+ * at physical_base. virtual_base is the predefined region
+ * of virtual memory for userland applications. physical_base
+ * is determined at build-time, it is one of the subsequent pages
+ * that come after the kernel image's load area.
+ */
+/* USER_AREA_START, see memlayout.h */
+virtual_base = 0x10000000;
+__stack = (0x20000000 - 0x1000 - 8); /* First page before the env/args */
+INCLUDE "include/physical_base.lds"
+
+/* physical_base = 0x228000; */
+offset = virtual_base - physical_base;
+
+ENTRY(_start)
+
+SECTIONS
+{
+	. = virtual_base;
+	_start_text = .;
+	.text : AT (ADDR(.text) - offset) { crt0.o(.text) *(.text) }
+	/* rodata is needed else your strings will link at physical! */
+	.rodata : AT (ADDR(.rodata) - offset) { *(.rodata) }
+	.rodata1 : AT (ADDR(.rodata1) - offset) { *(.rodata1) }
+	. = ALIGN(4K);
+	.data : AT (ADDR(.data) - offset) { *(.data) }
+	.bss : AT (ADDR(.bss) - offset) { *(.bss) }
+	_end = .;
+}

tasks/test0/main.c

@@ -19,7 +19,7 @@ void wait_pager(l4id_t partner)
 	for (int i = 0; i < 6; i++)
 		write_mr(i, i);
 	l4_send(partner, L4_IPC_TAG_SYNC);
-	// printf("Pager synced with us.\n");
+	printf("Pager synced with us.\n");
 }
 
 pid_t parent_of_all;

tasks/test0/src/exectest.c

@@ -11,14 +11,14 @@
 #include <string.h>
 #include <errno.h>
 
-extern char _start_test1[];
-extern char _end_test1[];
+extern char _start_test_exec[];
+extern char _end_test_exec[];
 
 int exectest(void)
 {
 	int fd;
-	void *exec_start = (void *)_start_test1;
-	unsigned long size = _end_test1 - _start_test1;
+	void *exec_start = (void *)_start_test_exec;
+	unsigned long size = _end_test_exec - _start_test_exec;
 	int left, cnt;
 	char *argv[5];
 	char filename[128];

tasks/test0/src/test_exec/container.c

@@ -0,0 +1,25 @@
+/*
+ * Container entry point for this task.
+ *
+ * Copyright (C) 2007-2009 Bahadir Bilgehan Balban
+ */
+
+#include <l4lib/types.h>
+#include <l4lib/init.h>
+#include <l4lib/utcb.h>
+#include <posix_init.h>		/* Initialisers for posix library */
+
+void main(void);
+
+void __container_init(void)
+{
+	/* Generic L4 thread initialisation */
+	__l4_init();
+
+	/* Initialise posix library for application */
+	libposix_init();
+
+	/* Entry to main */
+	main();
+}
+

tasks/test0/src/test_exec/test_exec.c

@@ -0,0 +1,36 @@
+/*
+ * Some tests for posix syscalls.
+ *
+ * Copyright (C) 2007 Bahadir Balban
+ */
+#include <stdio.h>
+#include <string.h>
+#include <l4lib/arch/syslib.h>
+#include <l4lib/kip.h>
+#include <l4lib/utcb.h>
+#include <l4lib/ipcdefs.h>
+#include <tests.h>
+#include <unistd.h>
+#include <sys/types.h>
+
+void wait_pager(l4id_t partner)
+{
+	// printf("%s: Syncing with pager.\n", __TASKNAME__);
+	for (int i = 0; i < 6; i++)
+		write_mr(i, i);
+	l4_send(partner, L4_IPC_TAG_SYNC);
+	// printf("Pager synced with us.\n");
+}
+
+void main(void)
+{
+	wait_pager(0);
+	if (getpid() == 2) {
+		printf("EXECVE TEST    -- PASSED --\n", getpid());
+		printf("\n(Thread %d): Continues to sync with the pager...\n", getpid());
+		while (1)
+			wait_pager(0);
+	}
+	_exit(0);
+}
+

tasks/test0/test_exec.S

@@ -0,0 +1,5 @@
+.section .testexec
+
+.align 4
+.incbin "test_exec.axf"
+.align 4