diff --git a/arch/arm64/kernel/include/arch-memory.h b/arch/arm64/kernel/include/arch-memory.h
index c690106b..1ebf771a 100644
--- a/arch/arm64/kernel/include/arch-memory.h
+++ b/arch/arm64/kernel/include/arch-memory.h
@@ -57,6 +57,7 @@ extern char _end[];
 
 #if (VA_BITS == 39 && GRANULE_SIZE == _SZ4KB)
 #
+# define LD_TASK_UNMAPPED_BASE	UL(0x0000000400000000)
 # define TASK_UNMAPPED_BASE	UL(0x0000000800000000)
 # define USER_END		UL(0x0000002000000000)
 # define MAP_VMAP_START		UL(0xffffffbdc0000000)
@@ -67,6 +68,7 @@ extern char _end[];
 #
 #elif (VA_BITS == 42 && GRANULE_SIZE == _SZ64KB)
 #
+# define LD_TASK_UNMAPPED_BASE	UL(0x0000002000000000)
 # define TASK_UNMAPPED_BASE	UL(0x0000004000000000)
 # define USER_END		UL(0x0000010000000000)
 # define MAP_VMAP_START		UL(0xfffffdfee0000000)
@@ -77,6 +79,7 @@ extern char _end[];
 #
 #elif (VA_BITS == 48 && GRANULE_SIZE == _SZ4KB)
 #
+# define LD_TASK_UNMAPPED_BASE	UL(0x0000080000000000)
 # define TASK_UNMAPPED_BASE	UL(0x0000100000000000)
 # define USER_END		UL(0x0000400000000000)
 # define MAP_VMAP_START		UL(0xffff7bffc0000000)
@@ -87,6 +90,7 @@ extern char _end[];
 #
 #elif (VA_BITS == 48 && GRANULE_SIZE == _SZ64KB)
 #
+# define LD_TASK_UNMAPPED_BASE	UL(0x0000080000000000)
 # define TASK_UNMAPPED_BASE	UL(0x0000100000000000)
 # define USER_END		UL(0x0000400000000000)
 # define MAP_VMAP_START		UL(0xffff780000000000)
diff --git a/arch/x86_64/kernel/include/arch-memory.h b/arch/x86_64/kernel/include/arch-memory.h
index ed003ae9..443d6490 100644
--- a/arch/x86_64/kernel/include/arch-memory.h
+++ b/arch/x86_64/kernel/include/arch-memory.h
@@ -41,8 +41,9 @@
 #define LARGE_PAGE_MASK    (~((unsigned long)LARGE_PAGE_SIZE - 1))
 #define LARGE_PAGE_P2ALIGN (LARGE_PAGE_SHIFT - PAGE_SHIFT)
 
-#define USER_END           0x0000800000000000UL
-#define TASK_UNMAPPED_BASE 0x00002AAAAAA00000UL
+#define USER_END              0x0000800000000000UL
+#define LD_TASK_UNMAPPED_BASE 0x0000155555500000UL
+#define TASK_UNMAPPED_BASE    0x00002AAAAAA00000UL
 
 /*
  * Canonical negative addresses (i.e., the smallest kernel virtual address)
diff --git a/kernel/host.c b/kernel/host.c
index 53e1af6b..8ccac6ef 100644
--- a/kernel/host.c
+++ b/kernel/host.c
@@ -98,6 +98,7 @@ int prepare_process_ranges_args_envs(struct thread *thread,
 	
 	n = p->num_sections;
 
+	vm->region.data_start = ULONG_MAX;
 	aout_base = (pn->reloc)? vm->region.map_end: 0;
 	for (i = 0; i < n; i++) {
 		ap_flags = 0;
@@ -172,18 +173,13 @@ int prepare_process_ranges_args_envs(struct thread *thread,
 
 		p->sections[i].remote_pa = up;
 
-		/* TODO: Maybe we need flag */
 		if (pn->sections[i].interp) {
 			vm->region.map_end = e;
 		}
-		else if (i == 0) {
+		else if (pn->sections[i].prot & PROT_EXEC) {
 			vm->region.text_start = s;
 			vm->region.text_end = e;
 		} 
-		else if (i == 1) {
-			vm->region.data_start = s;
-			vm->region.data_end = e;
-		} 
 		else {
 			vm->region.data_start =
 				(s < vm->region.data_start ? 
@@ -212,9 +208,16 @@ int prepare_process_ranges_args_envs(struct thread *thread,
 		pn->at_entry += aout_base;
 	}
 
+	vm->region.map_start = vm->region.map_end = TASK_UNMAPPED_BASE;
+
 	vm->region.brk_start = vm->region.brk_end =
 		(vm->region.data_end + LARGE_PAGE_SIZE - 1) & LARGE_PAGE_MASK;
 
+	if (vm->region.brk_start >= vm->region.map_start) {
+		kprintf("%s: ERROR: data section is too large (end addr: %lx)\n",
+			__func__, vm->region.data_end);
+	}
+
 #if 0
 	{
 		void *heap;
@@ -528,17 +531,12 @@ static int process_msg_prepare_process(unsigned long rphys)
 	vm->region.user_end = pn->user_end;
 	if(vm->region.user_end > USER_END)
 		vm->region.user_end = USER_END;
-	if(vm->region.user_start != 0UL ||
-	   vm->region.user_end < TASK_UNMAPPED_BASE){
-		vm->region.map_start = 
-			(vm->region.user_start +
-			 (vm->region.user_end - vm->region.user_start) / 3) &
-			LARGE_PAGE_MASK;
-	}
-	else{
-		vm->region.map_start = TASK_UNMAPPED_BASE;
-	}
-	vm->region.map_end = vm->region.map_start;
+
+	/* map_start / map_end is used to track memory area
+	 * to which the program is loaded
+	 */
+	vm->region.map_start = vm->region.map_end = LD_TASK_UNMAPPED_BASE;
+
 	memcpy(proc->rlimit, pn->rlimit, sizeof(struct rlimit) * MCK_RLIM_MAX);
 	dkprintf("%s: rlim_cur: %ld, rlim_max: %ld, stack_premap: %ld\n",
 			__FUNCTION__,
diff --git a/kernel/syscall.c b/kernel/syscall.c
index d5c5b4ff..6602eb07 100644
--- a/kernel/syscall.c
+++ b/kernel/syscall.c
@@ -2598,6 +2598,11 @@ SYSCALL_DECLARE(execve)
 			((char *)thread) +
 			KERNEL_STACK_NR_PAGES * PAGE_SIZE, desc->entry, 0);
 
+	/* map_start / map_end is used to track memory area
+	 * to which the program is loaded
+	 */
+	vm->region.map_start = vm->region.map_end = LD_TASK_UNMAPPED_BASE;
+
 	/* Create virtual memory ranges and update args/envs */
 	if (prepare_process_ranges_args_envs(thread, desc, desc,
 				PTATTR_NO_EXECUTE | PTATTR_WRITABLE | PTATTR_FOR_USER,
diff --git a/lib/include/limits.h b/lib/include/limits.h
index ffab95b9..5223889e 100644
--- a/lib/include/limits.h
+++ b/lib/include/limits.h
@@ -15,6 +15,10 @@
 
 #define INT_MAX 0x7fffffff
 #define INT_MIN -0x80000000
+#define UINT_MAX 0xffffffff
+#define LONG_MAX 0x7fffffffffffffffL
+#define LONG_MIN -0x8000000000000000L
+#define ULONG_MAX 0xffffffffffffffffL
 #define IOV_MAX 1024
 
 #ifndef PATH_MAX