diff --git a/.gitignore b/.gitignore
index fade14b3..f4d49d9e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -51,6 +51,16 @@ shellcode.static
 sample_m68k
 sample_m68k.exe
 sample_m68k.static
+mem_exec
+mem_exec.exe
+mem_exec.static
+mem_protect
+mem_protect.exe
+mem_protect.static
+mem_unmap
+mem_unmap.exe
+mem_unmap.static
+
 
 libunicorn*.dll
 libunicorn*.so
diff --git a/bindings/go/unicorn/hook.c b/bindings/go/unicorn/hook.c
index a06f9901..f24dd1f1 100644
--- a/bindings/go/unicorn/hook.c
+++ b/bindings/go/unicorn/hook.c
@@ -1,8 +1,12 @@
 #include <unicorn/unicorn.h>
 #include "_cgo_export.h"
 
-uc_err uc_hook_add2(uch handle, uch *h2, uc_hook_t type, void *callback, void *user_data, int extra) {
-    return uc_hook_add(handle, h2, type, callback, user_data, extra);
+uc_err uc_hook_add_i1(uch handle, uch *h2, uc_hook_t type, void *callback, void *user, int arg1) {
+    return uc_hook_add(handle, h2, type, callback, user, arg1);
+}
+
+uc_err uc_hook_add_u2(uch handle, uch *h2, uc_hook_t type, void *callback, void *user, uint64_t arg1, uint64_t arg2) {
+    return uc_hook_add(handle, h2, type, callback, user, arg1, arg2);
 }
 
 void hookCode_cgo(uch handle, uint64_t addr, uint32_t size, void *user) {
diff --git a/bindings/go/unicorn/hook.go b/bindings/go/unicorn/hook.go
index dcab893a..e6e01617 100644
--- a/bindings/go/unicorn/hook.go
+++ b/bindings/go/unicorn/hook.go
@@ -60,21 +60,26 @@ func hookX86Syscall(handle C.uch, user unsafe.Pointer) {
 
 var hookRetain = make(map[C.uch]*HookData)
 
-func (u *Uc) HookAdd(htype int, cb interface{}, insn ...int) (C.uch, error) {
+func (u *Uc) HookAdd(htype int, cb interface{}, extra ...uint64) (C.uch, error) {
 	var callback unsafe.Pointer
-	var extra C.int
+	var iarg1 C.int
+	var uarg1, uarg2 C.uint64_t
+	rangeMode := false
 	switch htype {
 	case UC_HOOK_BLOCK, UC_HOOK_CODE:
+		rangeMode = true
 		callback = C.hookCode_cgo
 	case UC_HOOK_MEM_INVALID:
+		rangeMode = true
 		callback = C.hookMemInvalid_cgo
 	case UC_HOOK_MEM_READ, UC_HOOK_MEM_WRITE, UC_HOOK_MEM_READ_WRITE:
+		rangeMode = true
 		callback = C.hookMemAccess_cgo
 	case UC_HOOK_INTR:
 		callback = C.hookInterrupt_cgo
 	case UC_HOOK_INSN:
-		extra = C.int(insn[0])
-		switch extra {
+		iarg1 = C.int(extra[0])
+		switch iarg1 {
 		case UC_X86_INS_IN:
 			callback = C.hookX86In_cgo
 		case UC_X86_INS_OUT:
@@ -89,7 +94,17 @@ func (u *Uc) HookAdd(htype int, cb interface{}, insn ...int) (C.uch, error) {
 	}
 	var h2 C.uch
 	data := &HookData{u, cb}
-	C.uc_hook_add2(u.Handle, &h2, C.uc_hook_t(htype), callback, unsafe.Pointer(data), extra)
+	if rangeMode {
+		if len(extra) == 2 {
+			uarg1 = C.uint64_t(extra[0])
+			uarg2 = C.uint64_t(extra[1])
+		} else {
+			uarg1, uarg2 = 1, 0
+		}
+		C.uc_hook_add_u2(u.Handle, &h2, C.uc_hook_t(htype), callback, unsafe.Pointer(data), uarg1, uarg2)
+	} else {
+		C.uc_hook_add_i1(u.Handle, &h2, C.uc_hook_t(htype), callback, unsafe.Pointer(data), iarg1)
+	}
 	hookRetain[h2] = data
 	return h2, nil
 }
diff --git a/bindings/go/unicorn/hook.h b/bindings/go/unicorn/hook.h
index c8c22267..b35fca27 100644
--- a/bindings/go/unicorn/hook.h
+++ b/bindings/go/unicorn/hook.h
@@ -1,4 +1,5 @@
-uc_err uc_hook_add2(uch handle, uch *h2, uc_hook_t type, void *callback, void *user_data, int extra);
+uc_err uc_hook_add_i1(uch handle, uch *h2, uc_hook_t type, void *callback, void *user_data, int arg1);
+uc_err uc_hook_add_u2(uch handle, uch *h2, uc_hook_t type, void *callback, void *user_data, uint64_t arg1, uint64_t arg2);
 void hookCode_cgo(uch handle, uint64_t addr, uint32_t size, void *user);
 bool hookMemInvalid_cgo(uch handle, uc_mem_type type, uint64_t addr, int size, int64_t value, void *user);
 void hookMemAccess_cgo(uch handle, uc_mem_type type, uint64_t addr, int size, int64_t value, void *user);
diff --git a/bindings/go/unicorn/unicorn_const.go b/bindings/go/unicorn/unicorn_const.go
index 427b34cd..e5ab6863 100644
--- a/bindings/go/unicorn/unicorn_const.go
+++ b/bindings/go/unicorn/unicorn_const.go
@@ -34,7 +34,7 @@ const (
 	UC_MODE_MIPS64 = 8
 
 	UC_ERR_OK = 0
-	UC_ERR_OOM = 1
+	UC_ERR_NOMEM = 1
 	UC_ERR_ARCH = 2
 	UC_ERR_HANDLE = 3
 	UC_ERR_UCH = 4
@@ -46,13 +46,16 @@ const (
 	UC_ERR_HOOK = 10
 	UC_ERR_INSN_INVALID = 11
 	UC_ERR_MAP = 12
-	UC_ERR_MEM_WRITE_NW = 13
-	UC_ERR_MEM_READ_NR = 14
+	UC_ERR_WRITE_PROT = 13
+	UC_ERR_READ_PROT = 14
+	UC_ERR_EXEC_PROT = 15
+	UC_ERR_INVAL = 16
 	UC_MEM_READ = 16
 	UC_MEM_WRITE = 17
 	UC_MEM_READ_WRITE = 18
-	UC_MEM_WRITE_NW = 19
-	UC_MEM_READ_NR = 20
+	UC_MEM_WRITE_PROT = 19
+	UC_MEM_READ_PROT = 20
+	UC_MEM_EXEC_PROT = 21
 	UC_HOOK_INTR = 32
 	UC_HOOK_INSN = 33
 	UC_HOOK_CODE = 34
@@ -65,5 +68,6 @@ const (
 	UC_PROT_NONE = 0
 	UC_PROT_READ = 1
 	UC_PROT_WRITE = 2
-	UC_PROT_ALL = 3
+	UC_PROT_EXEC = 4
+	UC_PROT_ALL = 7
 )
\ No newline at end of file
diff --git a/bindings/python/unicorn/unicorn_const.py b/bindings/python/unicorn/unicorn_const.py
index f2c8f0db..0f2bf718 100644
--- a/bindings/python/unicorn/unicorn_const.py
+++ b/bindings/python/unicorn/unicorn_const.py
@@ -32,7 +32,7 @@ UC_MODE_MIPS32 = 4
 UC_MODE_MIPS64 = 8
 
 UC_ERR_OK = 0
-UC_ERR_OOM = 1
+UC_ERR_NOMEM = 1
 UC_ERR_ARCH = 2
 UC_ERR_HANDLE = 3
 UC_ERR_UCH = 4
@@ -44,13 +44,16 @@ UC_ERR_CODE_INVALID = 9
 UC_ERR_HOOK = 10
 UC_ERR_INSN_INVALID = 11
 UC_ERR_MAP = 12
-UC_ERR_MEM_WRITE_NW = 13
-UC_ERR_MEM_READ_NR = 14
+UC_ERR_WRITE_PROT = 13
+UC_ERR_READ_PROT = 14
+UC_ERR_EXEC_PROT = 15
+UC_ERR_INVAL = 16
 UC_MEM_READ = 16
 UC_MEM_WRITE = 17
 UC_MEM_READ_WRITE = 18
-UC_MEM_WRITE_NW = 19
-UC_MEM_READ_NR = 20
+UC_MEM_WRITE_PROT = 19
+UC_MEM_READ_PROT = 20
+UC_MEM_EXEC_PROT = 21
 UC_HOOK_INTR = 32
 UC_HOOK_INSN = 33
 UC_HOOK_CODE = 34
@@ -63,4 +66,5 @@ UC_HOOK_MEM_READ_WRITE = 39
 UC_PROT_NONE = 0
 UC_PROT_READ = 1
 UC_PROT_WRITE = 2
-UC_PROT_ALL = 3
+UC_PROT_EXEC = 4
+UC_PROT_ALL = 7
diff --git a/include/uc_priv.h b/include/uc_priv.h
index 195d719c..dc4fcfd6 100644
--- a/include/uc_priv.h
+++ b/include/uc_priv.h
@@ -47,6 +47,8 @@ typedef void (*uc_args_uc_u64_t)(struct uc_struct *, uint64_t addr);
 
 typedef MemoryRegion* (*uc_args_uc_ram_size_t)(struct uc_struct*,  ram_addr_t begin, size_t size, uint32_t perms);
 
+typedef void (*uc_mem_unmap_t)(struct uc_struct*, MemoryRegion *mr);
+
 typedef void (*uc_readonly_mem_t)(MemoryRegion *mr, bool readonly);
 
 // which interrupt should make emulation stop?
@@ -90,6 +92,7 @@ struct uc_struct {
     uc_args_tcg_enable_t tcg_enabled;
     uc_args_uc_long_t tcg_exec_init;
     uc_args_uc_ram_size_t memory_map;
+    uc_mem_unmap_t memory_unmap;
     uc_readonly_mem_t readonly_mem;
     // list of cpu
     void* cpu;
@@ -172,8 +175,9 @@ struct uc_struct {
     bool block_full;
     MemoryRegion **mapped_blocks;
     uint32_t mapped_block_count;
-
     void *qemu_thread_data; // to support cross compile to Windows (qemu-thread-win32.c)
+    uint32_t target_page_size;
+    uint32_t target_page_align;
 };
 
 #include "qemu_macro.h"
diff --git a/include/unicorn/unicorn.h b/include/unicorn/unicorn.h
index 40a32e0e..ad373ab2 100644
--- a/include/unicorn/unicorn.h
+++ b/include/unicorn/unicorn.h
@@ -106,7 +106,7 @@ typedef enum uc_mode {
 // These are values returned by uc_errno()
 typedef enum uc_err {
     UC_ERR_OK = 0,   // No error: everything was fine
-    UC_ERR_OOM,      // Out-Of-Memory error: uc_open(), uc_emulate()
+    UC_ERR_NOMEM,      // Out-Of-Memory error: uc_open(), uc_emulate()
     UC_ERR_ARCH,     // Unsupported architecture: uc_open()
     UC_ERR_HANDLE,   // Invalid handle
     UC_ERR_MODE,     // Invalid/unsupported mode: uc_open()
@@ -117,8 +117,10 @@ typedef enum uc_err {
     UC_ERR_HOOK,    // Invalid hook type: uc_hook_add()
     UC_ERR_INSN_INVALID, // Quit emulation due to invalid instruction: uc_emu_start()
     UC_ERR_MAP, // Invalid memory mapping: uc_mem_map()
-    UC_ERR_MEM_WRITE_NW, // Quit emulation due to write to non-writable: uc_emu_start()
-    UC_ERR_MEM_READ_NR, // Quit emulation due to read from non-readable: uc_emu_start()
+    UC_ERR_WRITE_PROT, // Quit emulation due to UC_PROT_WRITE violation: uc_emu_start()
+    UC_ERR_READ_PROT, // Quit emulation due to UC_PROT_READ violation: uc_emu_start()
+    UC_ERR_EXEC_PROT, // Quit emulation due to UC_PROT_EXEC violation: uc_emu_start()
+    UC_ERR_INVAL,     // Inavalid argument provided to uc_xxx function (See specific function API)
 } uc_err;
 
 
@@ -150,8 +152,9 @@ typedef enum uc_mem_type {
     UC_MEM_READ = 16,   // Memory is read from
     UC_MEM_WRITE,       // Memory is written to
     UC_MEM_READ_WRITE,  // Memory is accessed (either READ or WRITE)
-    UC_MEM_WRITE_NW,    // write to non-writable
-    UC_MEM_READ_NR,     // read from non-readable
+    UC_MEM_WRITE_PROT,  // write to write protected memory
+    UC_MEM_READ_PROT,   // read from read protected memory
+    UC_MEM_EXEC_PROT,   // fetch from non-executable memory
 } uc_mem_type;
 
 // All type of hooks for uc_hook_add() API.
@@ -393,7 +396,8 @@ typedef enum uc_prot {
    UC_PROT_NONE = 0,
    UC_PROT_READ = 1,
    UC_PROT_WRITE = 2,
-   UC_PROT_ALL = 3,
+   UC_PROT_EXEC = 4,
+   UC_PROT_ALL = 7,
 } uc_prot;
 
 /*
@@ -402,12 +406,12 @@ typedef enum uc_prot {
 
  @uc: handle returned by uc_open()
  @address: starting address of the new memory region to be mapped in.
-    This address must be aligned to 4KB, or this will return with UC_ERR_MAP error.
+    This address must be aligned to 4KB, or this will return with UC_ERR_INVAL error.
  @size: size of the new memory region to be mapped in.
-    This size must be multiple of 4KB, or this will return with UC_ERR_MAP error.
+    This size must be multiple of 4KB, or this will return with UC_ERR_INVAL error.
  @perms: Permissions for the newly mapped region.
-    This must be some combination of UC_PROT_READ & UC_PROT_WRITE,
-    or this will return with UC_ERR_MAP error. See uc_prot type above.
+    This must be some combination of UC_PROT_READ | UC_PROT_WRITE | UC_PROT_EXEC,
+    or this will return with UC_ERR_INVAL error.
 
  @return UC_ERR_OK on success, or other value on failure (refer to uc_err enum
  for detailed error).
@@ -415,6 +419,41 @@ typedef enum uc_prot {
 UNICORN_EXPORT
 uc_err uc_mem_map(ucengine *uc, uint64_t address, size_t size, uint32_t perms);
 
+/*
+ Unmap a region of emulation memory.
+ This API deletes a memory mapping from the emulation memory space.
+
+ @handle: handle returned by uc_open()
+ @address: starting address of the memory region to be unmapped.
+    This address must be aligned to 4KB, or this will return with UC_ERR_INVAL error.
+ @size: size of the memory region to be modified.
+    This size must be multiple of 4KB, or this will return with UC_ERR_INVAL error.
+
+ @return UC_ERR_OK on success, or other value on failure (refer to uc_err enum
+ for detailed error).
+*/
+UNICORN_EXPORT
+uc_err uc_mem_unmap(uch handle, uint64_t address, size_t size);
+
+/*
+ Set memory permissions for emulation memory.
+ This API changes permissions on an existing memory region.
+
+ @handle: handle returned by uc_open()
+ @address: starting address of the memory region to be modified.
+    This address must be aligned to 4KB, or this will return with UC_ERR_INVAL error.
+ @size: size of the memory region to be modified.
+    This size must be multiple of 4KB, or this will return with UC_ERR_INVAL error.
+ @perms: New permissions for the mapped region.
+    This must be some combination of UC_PROT_READ | UC_PROT_WRITE | UC_PROT_EXEC,
+    or this will return with UC_ERR_INVAL error.
+
+ @return UC_ERR_OK on success, or other value on failure (refer to uc_err enum
+ for detailed error).
+*/
+UNICORN_EXPORT
+uc_err uc_mem_protect(uch handle, uint64_t address, size_t size, uint32_t perms);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/qemu/aarch64.h b/qemu/aarch64.h
index 9ab06273..77de1644 100644
--- a/qemu/aarch64.h
+++ b/qemu/aarch64.h
@@ -7,6 +7,7 @@
 #define phys_mem_clean phys_mem_clean_aarch64
 #define tb_cleanup tb_cleanup_aarch64
 #define memory_map memory_map_aarch64
+#define memory_unmap memory_unmap_aarch64
 #define memory_free memory_free_aarch64
 #define helper_raise_exception helper_raise_exception_aarch64
 #define tcg_enabled tcg_enabled_aarch64
diff --git a/qemu/arm.h b/qemu/arm.h
index c24329b3..3d405fac 100644
--- a/qemu/arm.h
+++ b/qemu/arm.h
@@ -7,6 +7,7 @@
 #define phys_mem_clean phys_mem_clean_arm
 #define tb_cleanup tb_cleanup_arm
 #define memory_map memory_map_arm
+#define memory_unmap memory_unmap_arm
 #define memory_free memory_free_arm
 #define helper_raise_exception helper_raise_exception_arm
 #define tcg_enabled tcg_enabled_arm
diff --git a/qemu/cputlb.c b/qemu/cputlb.c
index cde8e30e..ed120082 100644
--- a/qemu/cputlb.c
+++ b/qemu/cputlb.c
@@ -299,6 +299,11 @@ tb_page_addr_t get_page_addr_code(CPUArchState *env1, target_ulong addr)
     if (unlikely(env1->tlb_table[mmu_idx][page_index].addr_code !=
                  (addr & TARGET_PAGE_MASK))) {
         cpu_ldub_code(env1, addr);
+        //check for NX related error from softmmu
+        if (env1->invalid_error == UC_ERR_MEM_READ) {
+            env1->invalid_error = UC_ERR_CODE_INVALID;
+            return -1;
+        }
     }
     pd = env1->iotlb[mmu_idx][page_index] & ~TARGET_PAGE_MASK;
     mr = iotlb_to_region(cpu->as, pd);
diff --git a/qemu/header_gen.py b/qemu/header_gen.py
index ff8a1ca5..67982502 100644
--- a/qemu/header_gen.py
+++ b/qemu/header_gen.py
@@ -13,6 +13,7 @@ symbols = (
     'phys_mem_clean',
     'tb_cleanup',
     'memory_map',
+    'memory_unmap',
     'memory_free',
     'helper_raise_exception',
     'tcg_enabled',
diff --git a/qemu/include/exec/memory.h b/qemu/include/exec/memory.h
index 4df8bd85..45c51e4d 100644
--- a/qemu/include/exec/memory.h
+++ b/qemu/include/exec/memory.h
@@ -939,6 +939,7 @@ void address_space_unmap(AddressSpace *as, void *buffer, hwaddr len,
 void memory_register_types(struct uc_struct *uc);
 
 MemoryRegion *memory_map(struct uc_struct *uc, ram_addr_t begin, size_t size, uint32_t perms);
+void memory_unmap(struct uc_struct *uc, MemoryRegion *mr);
 int memory_free(struct uc_struct *uc);
 
 #endif
diff --git a/qemu/m68k.h b/qemu/m68k.h
index 5dbefab7..4be757ba 100644
--- a/qemu/m68k.h
+++ b/qemu/m68k.h
@@ -7,6 +7,7 @@
 #define phys_mem_clean phys_mem_clean_m68k
 #define tb_cleanup tb_cleanup_m68k
 #define memory_map memory_map_m68k
+#define memory_unmap memory_unmap_m68k
 #define memory_free memory_free_m68k
 #define helper_raise_exception helper_raise_exception_m68k
 #define tcg_enabled tcg_enabled_m68k
diff --git a/qemu/memory.c b/qemu/memory.c
index 60f86ae4..be7933d5 100644
--- a/qemu/memory.c
+++ b/qemu/memory.c
@@ -45,6 +45,29 @@ MemoryRegion *memory_map(struct uc_struct *uc, ram_addr_t begin, size_t size, ui
     return ram;
 }
 
+void memory_unmap(struct uc_struct *uc, MemoryRegion *mr)
+{
+    int i;
+    target_ulong addr;
+    //make sure all pages associated with the MemoryRegion are flushed
+    for (addr = mr->addr; addr < mr->end; addr += uc->target_page_size) {
+       tlb_flush_page(uc->current_cpu, addr);
+    }
+    mr->enabled = false;
+    memory_region_del_subregion(get_system_memory(uc), mr);
+
+    for (i = 0; i < uc->mapped_block_count; i++) {
+        if (uc->mapped_blocks[i] == mr) {
+            uc->mapped_block_count--;
+            //shift remainder of array down over deleted pointer
+            memcpy(&uc->mapped_blocks[i], &uc->mapped_blocks[i + 1], sizeof(MemoryRegion*) * (uc->mapped_block_count - i));
+            break;
+        }
+    }
+
+    g_free(mr);
+}
+
 int memory_free(struct uc_struct *uc)
 {
     int i;
diff --git a/qemu/mips.h b/qemu/mips.h
index 059995e5..7a3e308a 100644
--- a/qemu/mips.h
+++ b/qemu/mips.h
@@ -7,6 +7,7 @@
 #define phys_mem_clean phys_mem_clean_mips
 #define tb_cleanup tb_cleanup_mips
 #define memory_map memory_map_mips
+#define memory_unmap memory_unmap_mips
 #define memory_free memory_free_mips
 #define helper_raise_exception helper_raise_exception_mips
 #define tcg_enabled tcg_enabled_mips
diff --git a/qemu/mips64.h b/qemu/mips64.h
index 74daddbc..9870cb15 100644
--- a/qemu/mips64.h
+++ b/qemu/mips64.h
@@ -7,6 +7,7 @@
 #define phys_mem_clean phys_mem_clean_mips64
 #define tb_cleanup tb_cleanup_mips64
 #define memory_map memory_map_mips64
+#define memory_unmap memory_unmap_mips64
 #define memory_free memory_free_mips64
 #define helper_raise_exception helper_raise_exception_mips64
 #define tcg_enabled tcg_enabled_mips64
diff --git a/qemu/mips64el.h b/qemu/mips64el.h
index 6ffc2dbc..5fde9e53 100644
--- a/qemu/mips64el.h
+++ b/qemu/mips64el.h
@@ -7,6 +7,7 @@
 #define phys_mem_clean phys_mem_clean_mips64el
 #define tb_cleanup tb_cleanup_mips64el
 #define memory_map memory_map_mips64el
+#define memory_unmap memory_unmap_mips64el
 #define memory_free memory_free_mips64el
 #define helper_raise_exception helper_raise_exception_mips64el
 #define tcg_enabled tcg_enabled_mips64el
diff --git a/qemu/mipsel.h b/qemu/mipsel.h
index 94c4fdf7..caf1fe4d 100644
--- a/qemu/mipsel.h
+++ b/qemu/mipsel.h
@@ -7,6 +7,7 @@
 #define phys_mem_clean phys_mem_clean_mipsel
 #define tb_cleanup tb_cleanup_mipsel
 #define memory_map memory_map_mipsel
+#define memory_unmap memory_unmap_mipsel
 #define memory_free memory_free_mipsel
 #define helper_raise_exception helper_raise_exception_mipsel
 #define tcg_enabled tcg_enabled_mipsel
diff --git a/qemu/powerpc.h b/qemu/powerpc.h
index fd627665..92e614e1 100644
--- a/qemu/powerpc.h
+++ b/qemu/powerpc.h
@@ -7,6 +7,7 @@
 #define phys_mem_clean phys_mem_clean_powerpc
 #define tb_cleanup tb_cleanup_powerpc
 #define memory_map memory_map_powerpc
+#define memory_unmap memory_unmap_powerpc
 #define memory_free memory_free_powerpc
 #define helper_raise_exception helper_raise_exception_powerpc
 #define tcg_enabled tcg_enabled_powerpc
diff --git a/qemu/softmmu_template.h b/qemu/softmmu_template.h
index bda85dce..ade85c85 100644
--- a/qemu/softmmu_template.h
+++ b/qemu/softmmu_template.h
@@ -181,6 +181,23 @@ WORD_TYPE helper_le_ld_name(CPUArchState *env, target_ulong addr, int mmu_idx,
     struct uc_struct *uc = env->uc;
     MemoryRegion *mr = memory_mapping(uc, addr);
 
+#if defined(SOFTMMU_CODE_ACCESS)
+    // Unicorn: callback on fetch from NX
+    if (mr != NULL && !(mr->perms & UC_PROT_EXEC)) {  //non-executable
+        if (uc->hook_mem_idx != 0 && ((uc_cb_eventmem_t)uc->hook_callbacks[uc->hook_mem_idx].callback)(
+                                       (uch)uc, UC_MEM_EXEC_PROT, addr, DATA_SIZE, 0,
+                                       uc->hook_callbacks[uc->hook_mem_idx].user_data)) {
+            env->invalid_error = UC_ERR_OK;
+        } else {
+            env->invalid_addr = addr;
+            env->invalid_error = UC_ERR_EXEC_PROT;
+            // printf("***** Invalid fetch (non-executable) at " TARGET_FMT_lx "\n", addr);
+            cpu_exit(uc->current_cpu);
+            return 0;
+        }
+    }
+#endif
+
     // Unicorn: callback on memory read
     if (env->uc->hook_mem_read && READ_ACCESS_TYPE == MMU_DATA_LOAD) {
         struct hook_struct *trace = hook_find(env->uc, UC_HOOK_MEM_READ, addr);
@@ -206,20 +223,16 @@ WORD_TYPE helper_le_ld_name(CPUArchState *env, target_ulong addr, int mmu_idx,
         }
     }
 
-    // Unicorn: callback on read only memory
+    // Unicorn: callback on non-readable memory
     if (mr != NULL && !(mr->perms & UC_PROT_READ)) {  //non-readable
-        bool result = false;
-        if (uc->hook_mem_idx) {
-            result = ((uc_cb_eventmem_t)uc->hook_callbacks[uc->hook_mem_idx].callback)(
-                        uc, UC_MEM_READ_NR, addr, DATA_SIZE, 0,
-                        uc->hook_callbacks[uc->hook_mem_idx].user_data);
-        }
-        if (result) {
+        if (uc->hook_mem_idx != 0 && ((uc_cb_eventmem_t)uc->hook_callbacks[uc->hook_mem_idx].callback)(
+                                       uc, UC_MEM_READ_PROT, addr, DATA_SIZE, 0,
+                                       uc->hook_callbacks[uc->hook_mem_idx].user_data)) {
             env->invalid_error = UC_ERR_OK;
         }
         else {
             env->invalid_addr = addr;
-            env->invalid_error = UC_ERR_MEM_READ_NR;
+            env->invalid_error = UC_ERR_READ_PROT;
             // printf("***** Invalid memory read (non-readable) at " TARGET_FMT_lx "\n", addr);
             cpu_exit(uc->current_cpu);
             return 0;
@@ -326,6 +339,23 @@ WORD_TYPE helper_be_ld_name(CPUArchState *env, target_ulong addr, int mmu_idx,
     struct uc_struct *uc = env->uc;
     MemoryRegion *mr = memory_mapping(uc, addr);
 
+#if defined(SOFTMMU_CODE_ACCESS)
+    // Unicorn: callback on fetch from NX
+    if (mr != NULL && !(mr->perms & UC_PROT_EXEC)) {  //non-executable
+        if (uc->hook_mem_idx != 0 && ((uc_cb_eventmem_t)uc->hook_callbacks[uc->hook_mem_idx].callback)(
+                                       (uch)uc, UC_MEM_EXEC_PROT, addr, DATA_SIZE, 0,
+                                       uc->hook_callbacks[uc->hook_mem_idx].user_data)) {
+            env->invalid_error = UC_ERR_OK;
+        } else {
+            env->invalid_addr = addr;
+            env->invalid_error = UC_ERR_EXEC_PROT;
+            // printf("***** Invalid fetch (non-executable) at " TARGET_FMT_lx "\n", addr);
+            cpu_exit(uc->current_cpu);
+            return 0;
+        }
+    }
+#endif
+
     // Unicorn: callback on memory read
     if (env->uc->hook_mem_read && READ_ACCESS_TYPE == MMU_DATA_LOAD) {
         struct hook_struct *trace = hook_find(env->uc, UC_HOOK_MEM_READ, addr);
@@ -351,20 +381,15 @@ WORD_TYPE helper_be_ld_name(CPUArchState *env, target_ulong addr, int mmu_idx,
         }
     }
 
-    // Unicorn: callback on read only memory
+    // Unicorn: callback on non-readable memory
     if (mr != NULL && !(mr->perms & UC_PROT_READ)) {  //non-readable
-        bool result = false;
-        if (uc->hook_mem_idx) {
-            result = ((uc_cb_eventmem_t)uc->hook_callbacks[uc->hook_mem_idx].callback)(
-                        uc, UC_MEM_READ_NR, addr, DATA_SIZE, 0,
-                        uc->hook_callbacks[uc->hook_mem_idx].user_data);
-        }
-        if (result) {
+        if (uc->hook_mem_idx != 0 && ((uc_cb_eventmem_t)uc->hook_callbacks[uc->hook_mem_idx].callback)(
+                                       uc, UC_MEM_READ_PROT, addr, DATA_SIZE, 0,
+                                       uc->hook_callbacks[uc->hook_mem_idx].user_data)) {
             env->invalid_error = UC_ERR_OK;
-        }
-        else {
+        } else {
             env->invalid_addr = addr;
-            env->invalid_error = UC_ERR_MEM_READ_NR;
+            env->invalid_error = UC_ERR_READ_PROT;
             // printf("***** Invalid memory read (non-readable) at " TARGET_FMT_lx "\n", addr);
             cpu_exit(uc->current_cpu);
             return 0;
@@ -534,20 +559,16 @@ void helper_le_st_name(CPUArchState *env, target_ulong addr, DATA_TYPE val,
         }
     }
 
-    // Unicorn: callback on read only memory
-    if (mr != NULL && !(mr->perms & UC_PROT_WRITE)) {  //read only memory
-        bool result = false;
-        if (uc->hook_mem_idx) {
-            result = ((uc_cb_eventmem_t)uc->hook_callbacks[uc->hook_mem_idx].callback)(
-                        uc, UC_MEM_WRITE_NW, addr, DATA_SIZE, (int64_t)val,
-                        uc->hook_callbacks[uc->hook_mem_idx].user_data);
-        }
-        if (result) {
+    // Unicorn: callback on non-writable memory
+    if (mr != NULL && !(mr->perms & UC_PROT_WRITE)) {  //non-writable
+        if (uc->hook_mem_idx != 0 && ((uc_cb_eventmem_t)uc->hook_callbacks[uc->hook_mem_idx].callback)(
+                                       uc, UC_MEM_WRITE_PROT, addr, DATA_SIZE, (int64_t)val,
+                                       uc->hook_callbacks[uc->hook_mem_idx].user_data)) {
             env->invalid_error = UC_ERR_OK;
         }
         else {
             env->invalid_addr = addr;
-            env->invalid_error = UC_ERR_MEM_WRITE_NW;
+            env->invalid_error = UC_ERR_WRITE_PROT;
             // printf("***** Invalid memory write (ro) at " TARGET_FMT_lx "\n", addr);
             cpu_exit(uc->current_cpu);
             return;
@@ -672,20 +693,16 @@ void helper_be_st_name(CPUArchState *env, target_ulong addr, DATA_TYPE val,
         }
     }
 
-    // Unicorn: callback on read only memory
-    if (mr != NULL && !(mr->perms & UC_PROT_WRITE)) {  //read only memory
-        bool result = false;
-        if (uc->hook_mem_idx) {
-            result = ((uc_cb_eventmem_t)uc->hook_callbacks[uc->hook_mem_idx].callback)(
-                        uc, UC_MEM_WRITE_NW, addr, DATA_SIZE, (int64_t)val,
-                        uc->hook_callbacks[uc->hook_mem_idx].user_data);
-        }
-        if (result) {
+    // Unicorn: callback on non-writable memory
+    if (mr != NULL && !(mr->perms & UC_PROT_WRITE)) {  //non-writable
+        if (uc->hook_mem_idx != 0 && ((uc_cb_eventmem_t)uc->hook_callbacks[uc->hook_mem_idx].callback)(
+                                       uc, UC_MEM_WRITE_PROT, addr, DATA_SIZE, (int64_t)val,
+                                       uc->hook_callbacks[uc->hook_mem_idx].user_data)) {
             env->invalid_error = UC_ERR_OK;
         }
         else {
             env->invalid_addr = addr;
-            env->invalid_error = UC_ERR_MEM_WRITE_NW;
+            env->invalid_error = UC_ERR_WRITE_PROT;
             // printf("***** Invalid memory write (ro) at " TARGET_FMT_lx "\n", addr);
             cpu_exit(uc->current_cpu);
             return;
diff --git a/qemu/sparc.h b/qemu/sparc.h
index 64803c11..6aa47aa5 100644
--- a/qemu/sparc.h
+++ b/qemu/sparc.h
@@ -7,6 +7,7 @@
 #define phys_mem_clean phys_mem_clean_sparc
 #define tb_cleanup tb_cleanup_sparc
 #define memory_map memory_map_sparc
+#define memory_unmap memory_unmap_sparc
 #define memory_free memory_free_sparc
 #define helper_raise_exception helper_raise_exception_sparc
 #define tcg_enabled tcg_enabled_sparc
diff --git a/qemu/sparc64.h b/qemu/sparc64.h
index 5042c38d..6d3d2a1d 100644
--- a/qemu/sparc64.h
+++ b/qemu/sparc64.h
@@ -7,6 +7,7 @@
 #define phys_mem_clean phys_mem_clean_sparc64
 #define tb_cleanup tb_cleanup_sparc64
 #define memory_map memory_map_sparc64
+#define memory_unmap memory_unmap_sparc64
 #define memory_free memory_free_sparc64
 #define helper_raise_exception helper_raise_exception_sparc64
 #define tcg_enabled tcg_enabled_sparc64
diff --git a/qemu/unicorn_common.h b/qemu/unicorn_common.h
index 176900cb..adfb5f05 100644
--- a/qemu/unicorn_common.h
+++ b/qemu/unicorn_common.h
@@ -73,8 +73,12 @@ static inline void uc_common_init(struct uc_struct* uc)
     uc->pause_all_vcpus = pause_all_vcpus;
     uc->vm_start = vm_start;
     uc->memory_map = memory_map;
+    uc->memory_unmap = memory_unmap;
     uc->readonly_mem = memory_region_set_readonly;
 
+    uc->target_page_size = TARGET_PAGE_SIZE;
+    uc->target_page_align = TARGET_PAGE_SIZE - 1;
+
     if (!uc->release)
         uc->release = release_common;
 }
diff --git a/qemu/x86_64.h b/qemu/x86_64.h
index 9a148e95..ac9f34f0 100644
--- a/qemu/x86_64.h
+++ b/qemu/x86_64.h
@@ -7,6 +7,7 @@
 #define phys_mem_clean phys_mem_clean_x86_64
 #define tb_cleanup tb_cleanup_x86_64
 #define memory_map memory_map_x86_64
+#define memory_unmap memory_unmap_x86_64
 #define memory_free memory_free_x86_64
 #define helper_raise_exception helper_raise_exception_x86_64
 #define tcg_enabled tcg_enabled_x86_64
diff --git a/regress/reg_write_sign_extension.py b/regress/reg_write_sign_extension.py
new file mode 100755
index 00000000..69347c0f
--- /dev/null
+++ b/regress/reg_write_sign_extension.py
@@ -0,0 +1,23 @@
+#!/usr/bin/env python
+
+"""See https://github.com/unicorn-engine/unicorn/issues/98"""
+
+import unicorn
+ADDR = 0xffaabbcc
+
+def hook_mem_invalid(mu, access, address, size, value, user_data):
+    print ">>> Expected value: 0x%x, actual value: 0x%x" % (ADDR, address)
+    assert(address == ADDR)
+    mu.mem_map(address & 0xfffff000, 4 * 1024)
+    mu.mem_write(address, b'\xcc')
+    return True
+
+mu = unicorn.Uc(unicorn.UC_ARCH_X86, unicorn.UC_MODE_32)
+mu.reg_write(unicorn.x86_const.UC_X86_REG_EBX, ADDR)
+
+mu.mem_map(0x10000000, 1024 * 4)
+# jmp ebx
+mu.mem_write(0x10000000, b'\xff\xe3')
+
+mu.hook_add(unicorn.UC_HOOK_MEM_INVALID, hook_mem_invalid)
+mu.emu_start(0x10000000, 0x10000000 + 2, count=1)
diff --git a/regress/ro_mem_test.c b/regress/ro_mem_test.c
index 51b94b2f..0c0390ff 100644
--- a/regress/ro_mem_test.c
+++ b/regress/ro_mem_test.c
@@ -157,8 +157,11 @@ int main(int argc, char **argv, char **envp)
 
     // emulate machine code in infinite time
     printf("BEGIN execution - 2\n");
+    //update eax to point to aligned memory (same as add eax,7 above)
     uint32_t eax = 0x40002C;
     uc_reg_write(uc, UC_X86_REG_EAX, &eax); 
+    //resume execution at the mov dword [eax], 0x87654321
+    //to test an aligned write as well
     err = uc_emu_start(uc, 0x400015, 0x400000 + sizeof(PROGRAM), 0, 2);
     if (err) {
         printf("Expected failure on uc_emu_start() with error returned %u: %s\n",
diff --git a/samples/Makefile b/samples/Makefile
index 1ebb891f..f6345ae8 100644
--- a/samples/Makefile
+++ b/samples/Makefile
@@ -97,6 +97,9 @@ endif
 ifneq (,$(findstring x86,$(UNICORN_ARCHS)))
 SOURCES += sample_x86.c
 SOURCES += shellcode.c
+SOURCES += mem_unmap.c
+SOURCES += mem_protect.c
+SOURCES += mem_exec.c
 endif
 ifneq (,$(findstring m68k,$(UNICORN_ARCHS)))
 SOURCES += sample_m68k.c
@@ -111,7 +114,8 @@ all: $(BINARY)
 clean:
 	rm -rf *.o $(OBJS_ELF) $(BINARY) $(SAMPLEDIR)/*.exe $(SAMPLEDIR)/*.static $(OBJDIR)/lib$(LIBNAME)* $(OBJDIR)/$(LIBNAME)*
 	rm -rf libunicorn*.so libunicorn*.lib libunicorn*.dylib unicorn*.dll unicorn*.lib
-	rm -rf sample_x86 sample_arm sample_arm64 sample_mips sample_sparc sample_ppc sample_m68k shellcode
+	rm -rf sample_x86 sample_arm sample_arm64 sample_mips sample_sparc sample_ppc sample_m68k \
+		shellcode mem_unmap mem_protect mem_exec
 
 $(BINARY): $(OBJS)
 
diff --git a/samples/mem_exec.c b/samples/mem_exec.c
new file mode 100644
index 00000000..19153b46
--- /dev/null
+++ b/samples/mem_exec.c
@@ -0,0 +1,279 @@
+/*
+   Executable memory regions demo / unit test
+
+   Copyright(c) 2015 Chris Eagle
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License
+   version 2 as published by the Free Software Foundation.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+ */
+
+#define __STDC_FORMAT_MACROS
+#include <inttypes.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+#include <unicorn/unicorn.h>
+
+unsigned char PROGRAM[] =
+    "\xeb\x45\x5e\x81\xe6\x00\xf0\xff\xff\x40\x40\x40\x40\x40\x40\x40"
+    "\x40\x40\x40\x40\x40\x40\x40\x40\x40\x40\x40\x40\x40\x40\x40\x40"
+    "\x40\x40\x40\x40\x40\x40\x40\x89\xf7\x81\xc7\x00\x00\x10\x00\xb9"
+    "\x4c\x00\x00\x00\x81\xff\x00\x00\x40\x00\x75\x01\xf4\xf3\xa4\x81"
+    "\xe7\x00\xf0\xff\xff\xff\xe7\xe8\xb6\xff\xff\xff";
+    // total size: 76 bytes
+
+/*
+   bits 32
+
+   ; assumes r-x section at 0x100000
+   ; assumes rw- section at 0x200000
+   ; assumes r-- section at 0x300000
+   ; also needs an initialized stack
+
+start:
+jmp bottom
+top:
+pop esi
+and esi, ~0xfff
+times 30 inc eax
+mov edi, esi
+add edi, 0x100000
+mov ecx, end - start
+rep movsb
+and edi, ~0xfff
+cmp edi, 0x400000
+jnz next_block
+hlt
+next_block:
+jmp edi
+bottom:
+call top
+end:
+ */
+
+int test_num  = 0;
+uint32_t tests[] = {
+    0x41414141,
+    0x43434343,
+    0x45454545
+};
+
+static int log_num = 1;
+
+#define CODE_SECTION 0x100000
+#define CODE_SIZE 0x1000
+
+// callback for tracing instruction
+static void hook_code(uch handle, uint64_t addr, uint32_t size, void *user_data)
+{
+    uint8_t opcode;
+
+    if (uc_mem_read(handle, addr, &opcode, 1) != UC_ERR_OK) {
+        printf("not ok %d - uc_mem_read fail during hook_code callback, addr: 0x%" PRIx64 "\n", log_num++, addr);
+    }
+
+    //   printf("ok %d - uc_mem_read for opcode at address 0x%" PRIx64 "\n", log_num++, addr);
+    switch (opcode) {
+        case 0xf4:  //hlt
+            printf("# Handling HLT\n");
+            if (uc_emu_stop(handle) != UC_ERR_OK) {
+                printf("not ok %d - uc_emu_stop fail during hook_code callback, addr: 0x%" PRIx64 "\n", log_num++, addr);
+                _exit(-1);
+            } else {
+                printf("ok %d - hlt encountered, uc_emu_stop called\n", log_num++);
+            }
+            break;
+        default:  //all others
+            //         printf("# Handling OTHER\n");
+            break;
+    }
+}
+
+// callback for tracing memory access (READ or WRITE)
+static void hook_mem_write(uch handle, uc_mem_type type,
+        uint64_t addr, int size, int64_t value, void *user_data)
+{
+    printf("# write to memory at 0x%"PRIx64 ", data size = %u, data value = 0x%"PRIx64 "\n", addr, size, value);
+}
+
+// callback for tracing invalid memory access (READ or WRITE)
+static bool hook_mem_invalid(uch handle, uc_mem_type type,
+        uint64_t addr, int size, int64_t value, void *user_data)
+{
+    switch(type) {
+        default:
+            printf("not ok %d - UC_HOOK_MEM_INVALID type: %d at 0x%" PRIx64 "\n", log_num++, type, addr);
+            return false;
+        case UC_MEM_EXEC_PROT:
+            printf("# Fetch from non-executable memory at 0x%"PRIx64 "\n", addr);
+
+            //make page executable
+            if (uc_mem_protect(handle, addr & ~0xfffL, 0x1000, UC_PROT_READ | UC_PROT_EXEC) != UC_ERR_OK) {
+                printf("not ok %d - uc_mem_protect fail for address: 0x%" PRIx64 "\n", log_num++, addr);
+            } else {
+                printf("ok %d - uc_mem_protect success at 0x%" PRIx64 "\n", log_num++, addr);
+            }
+            return true;
+        case UC_MEM_WRITE_PROT:
+            printf("# write to non-writeable memory at 0x%"PRIx64 ", data size = %u, data value = 0x%"PRIx64 "\n", addr, size, value);
+
+            if (uc_mem_protect(handle, addr & ~0xfffL, 0x1000, UC_PROT_READ | UC_PROT_WRITE) != UC_ERR_OK) {
+                printf("not ok %d - uc_mem_protect fail during hook_mem_invalid callback, addr: 0x%" PRIx64 "\n", log_num++, addr);
+            } else {
+                printf("ok %d - uc_mem_protect success\n", log_num++);
+            }
+            return true;
+    }
+}
+
+int main(int argc, char **argv, char **envp)
+{
+    uch handle, trace1, trace2;
+    uc_err err;
+    uint32_t esp, eip;
+    int32_t buf1[1024], buf2[1024], readbuf[1024];
+    int i;
+
+    //don't really care about quality of randomness
+    srand(time(NULL));
+    for (i = 0; i < 1024; i++) {
+        buf1[i] = rand();
+        buf2[i] = rand();
+    }
+
+    printf("# Memory protect test\n");
+
+    // Initialize emulator in X86-32bit mode
+    err = uc_open(UC_ARCH_X86, UC_MODE_32, &handle);
+    if (err) {
+        printf("not ok %d - Failed on uc_open() with error returned: %u\n", log_num++, err);
+        return 1;
+    } else {
+        printf("ok %d - uc_open() success\n", log_num++);
+    }
+
+    uc_mem_map(handle, 0x100000, 0x1000, UC_PROT_READ | UC_PROT_EXEC);
+    uc_mem_map(handle, 0x1ff000, 0x2000, UC_PROT_READ | UC_PROT_WRITE);
+    uc_mem_map(handle, 0x300000, 0x2000, UC_PROT_READ);
+    uc_mem_map(handle, 0xf00000, 0x1000, UC_PROT_READ | UC_PROT_WRITE);
+
+    esp = 0xf00000 + 0x1000;
+
+    // Setup stack pointer
+    if (uc_reg_write(handle, UC_X86_REG_ESP, &esp)) {
+        printf("not ok %d - Failed to set esp. quit!\n", log_num++);
+        return 2;
+    } else {
+        printf("ok %d - ESP set\n", log_num++);
+    }
+
+    // fill in sections that shouldn't get touched
+    if (uc_mem_write(handle, 0x1ff000, (uint8_t*)buf1, 4096)) {
+        printf("not ok %d - Failed to write random buffer 1 to memory, quit!\n", log_num++);
+        return 3;
+    } else {
+        printf("ok %d - Random buffer 1 written to memory\n", log_num++);
+    }
+
+    if (uc_mem_write(handle, 0x301000, (uint8_t*)buf2, 4096)) {
+        printf("not ok %d - Failed to write random buffer 2 to memory, quit!\n", log_num++);
+        return 4;
+    } else {
+        printf("ok %d - Random buffer 2 written to memory\n", log_num++);
+    }
+
+    // write machine code to be emulated to memory
+    if (uc_mem_write(handle, 0x100000, PROGRAM, sizeof(PROGRAM))) {
+        printf("not ok %d - Failed to write emulation code to memory, quit!\n", log_num++);
+        return 5;
+    } else {
+        printf("ok %d - Program written to memory\n", log_num++);
+    }
+
+    if (uc_hook_add(handle, &trace2, UC_HOOK_CODE, hook_code, NULL, (uint64_t)1, (uint64_t)0) != UC_ERR_OK) {
+        printf("not ok %d - Failed to install UC_HOOK_CODE handler\n", log_num++);
+        return 6;
+    } else {
+        printf("ok %d - UC_HOOK_CODE installed\n", log_num++);
+    }
+
+    // intercept memory write events
+    if (uc_hook_add(handle, &trace1, UC_HOOK_MEM_WRITE, hook_mem_write, NULL, (uint64_t)1, (uint64_t)0) != UC_ERR_OK) {
+        printf("not ok %d - Failed to install UC_HOOK_MEM_WRITE handler\n", log_num++);
+        return 7;
+    } else {
+        printf("ok %d - UC_HOOK_MEM_WRITE installed\n", log_num++);
+    }
+
+    // intercept invalid memory events
+    if (uc_hook_add(handle, &trace1, UC_HOOK_MEM_INVALID, hook_mem_invalid, NULL) != UC_ERR_OK) {
+        printf("not ok %d - Failed to install UC_HOOK_MEM_INVALID handler\n", log_num++);
+        return 8;
+    } else {
+        printf("ok %d - UC_HOOK_MEM_INVALID installed\n", log_num++);
+    }
+
+    // emulate machine code until told to stop by hook_code
+    printf("# BEGIN execution\n");
+    err = uc_emu_start(handle, 0x100000, 0x400000, 0, 0);
+    if (err != UC_ERR_OK) {
+        printf("not ok %d - Failure on uc_emu_start() with error %u:%s\n", log_num++, err, uc_strerror(err));
+        return 9;
+    } else {
+        printf("ok %d - uc_emu_start complete\n", log_num++);
+    }
+    printf("# END execution\n");
+
+    // get ending EIP
+    if (uc_reg_read(handle, UC_X86_REG_EIP, &eip)) {
+        printf("not ok %d - Failed to read eip.\n", log_num++);
+    } else {
+        printf("ok %d - Ending EIP 0x%x\n", log_num++, eip);
+    }
+
+    //make sure that random blocks didn't get nuked
+    // fill in sections that shouldn't get touched
+    if (uc_mem_read(handle, 0x1ff000, (uint8_t*)readbuf, 4096)) {
+        printf("not ok %d - Failed to read random buffer 1 from memory\n", log_num++);
+    } else {
+        printf("ok %d - Random buffer 1 read from memory\n", log_num++);
+        if (memcmp(buf1, readbuf, 4096)) {
+            printf("not ok %d - Random buffer 1 contents are incorrect\n", log_num++);
+        } else {
+            printf("ok %d - Random buffer 1 contents are correct\n", log_num++);
+        }
+    }
+
+    if (uc_mem_read(handle, 0x301000, (uint8_t*)readbuf, 4096)) {
+        printf("not ok %d - Failed to read random buffer 2 from memory\n", log_num++);
+    } else {
+        printf("ok %d - Random buffer 2 read from memory\n", log_num++);
+        if (memcmp(buf2, readbuf, 4096)) {
+            printf("not ok %d - Random buffer 2 contents are incorrect\n", log_num++);
+        } else {
+            printf("ok %d - Random buffer 2 contents are correct\n", log_num++);
+        }
+    }
+
+    if (uc_close(&handle) == UC_ERR_OK) {
+        printf("ok %d - uc_close complete\n", log_num++);
+    } else {
+        printf("not ok %d - uc_close complete\n", log_num++);
+    }
+
+    return 0;
+}
diff --git a/samples/mem_protect.c b/samples/mem_protect.c
new file mode 100644
index 00000000..d9644d51
--- /dev/null
+++ b/samples/mem_protect.c
@@ -0,0 +1,301 @@
+/*
+   uc_mem_protect demo / unit test
+
+   Copyright(c) 2015 Chris Eagle
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License
+   version 2 as published by the Free Software Foundation.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+ */
+
+#define __STDC_FORMAT_MACROS
+#include <inttypes.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+#include <unicorn/unicorn.h>
+
+unsigned char PROGRAM[] =
+    "\xc7\x05\x00\x00\x20\x00\x41\x41\x41\x41\x90\xc7\x05\x00\x00\x20"
+    "\x00\x42\x42\x42\x42\xc7\x05\x00\x00\x30\x00\x43\x43\x43\x43\x90"
+    "\xc7\x05\x00\x00\x30\x00\x44\x44\x44\x44\xc7\x05\x00\x00\x40\x00"
+    "\x45\x45\x45\x45\x90\xc7\x05\x00\x00\x40\x00\x46\x46\x46\x46\xc7"
+    "\x05\x00\xf8\x3f\x00\x47\x47\x47\x47\xc7\x05\x00\x18\x40\x00\x48"
+    "\x48\x48\x48\xf4";
+    // total size: 84 bytes
+
+/*
+   bits 32
+
+   ; assumes code section at 0x100000
+   ; assumes data section at 0x200000, initially rw
+   ; assumes data section at 0x300000, initially rw
+   ; assumes data section at 0x400000, initially rw
+
+   ; with installed hooks unmaps or maps on each nop
+
+   mov dword [0x200000], 0x41414141 
+   nop                              ; mark it RO 
+   mov dword [0x200000], 0x42424242
+
+   mov dword [0x300000], 0x43434343
+   nop                              ; mark it RO 
+   mov dword [0x300000], 0x44444444
+
+   mov dword [0x400000], 0x45454545
+   nop                              ; mark it RO 
+   mov dword [0x400000], 0x46464646
+   mov dword [0x3ff800], 0x47474747 ; make sure surrounding areas remained RW
+   mov dword [0x401800], 0x48484848 ; make sure surrounding areas remained RW
+
+   hlt    ; tell hook function we are done
+ */
+
+int test_num  = 0;
+uint32_t tests[] = {
+    0x41414141,
+    0x43434343,
+    0x45454545
+};
+
+static int log_num = 1;
+
+#define CODE_SECTION 0x100000
+#define CODE_SIZE 0x1000
+
+// callback for tracing instruction
+static void hook_code(uch handle, uint64_t addr, uint32_t size, void *user_data)
+{
+    uint8_t opcode;
+    uint32_t testval;
+    if (uc_mem_read(handle, addr, &opcode, 1) != UC_ERR_OK) {
+        printf("not ok %d - uc_mem_read fail during hook_code callback, addr: 0x%" PRIx64 "\n", log_num++, addr);
+    }
+    printf("ok %d - uc_mem_read for opcode at address 0x%" PRIx64 "\n", log_num++, addr);
+    switch (opcode) {
+        case 0x90:  //nop
+            printf("# Handling NOP\n");
+            if (uc_mem_read(handle, 0x200000 + test_num * 0x100000, (uint8_t*)&testval, sizeof(testval)) != UC_ERR_OK) {
+                printf("not ok %d - uc_mem_read fail for address: 0x%x\n", log_num++, 0x200000 + test_num * 0x100000);
+            } else {
+                printf("ok %d - good uc_mem_read for address: 0x%x\n", log_num++, 0x200000 + test_num * 0x100000);
+                printf("# uc_mem_read for test %d\n", test_num);
+
+                if (testval == tests[test_num]) {
+                    printf("ok %d - passed test %d\n", log_num++, test_num);
+                } else {
+                    printf("not ok %d - failed test %d\n", log_num++, test_num);
+                    printf("# Expected: 0x%x\n",tests[test_num]);
+                    printf("# Received: 0x%x\n", testval);
+                }
+            }
+            if (uc_mem_protect(handle, 0x200000 + test_num * 0x100000, 0x1000, UC_PROT_READ) != UC_ERR_OK) {
+                printf("not ok %d - uc_mem_protect fail during hook_code callback, addr: 0x%x\n", log_num++, 0x200000 + test_num * 0x100000);
+            } else {
+                printf("ok %d - uc_mem_protect success\n", log_num++);
+            }
+            test_num++;
+            break;
+        case 0xf4:  //hlt
+            printf("# Handling HLT\n");
+            if (uc_emu_stop(handle) != UC_ERR_OK) {
+                printf("not ok %d - uc_emu_stop fail during hook_code callback, addr: 0x%" PRIx64 "\n", log_num++, addr);
+                _exit(-1);
+            } else {
+                printf("ok %d - hlt encountered, uc_emu_stop called\n", log_num++);
+            }
+            break;
+        default:  //all others
+            printf("# Handling OTHER\n");
+            break;
+    }
+}
+
+// callback for tracing memory access (READ or WRITE)
+static void hook_mem_write(uch handle, uc_mem_type type,
+        uint64_t addr, int size, int64_t value, void *user_data)
+{
+    printf("# write to memory at 0x%"PRIx64 ", data size = %u, data value = 0x%"PRIx64 "\n", addr, size, value);
+}
+
+// callback for tracing invalid memory access (READ or WRITE)
+static bool hook_mem_invalid(uch handle, uc_mem_type type,
+        uint64_t addr, int size, int64_t value, void *user_data)
+{
+    uint32_t testval;
+    switch(type) {
+        default:
+            printf("not ok %d - UC_HOOK_MEM_INVALID type: %d at 0x%" PRIx64 "\n", log_num++, type, addr);
+            return false;
+        case UC_MEM_WRITE_PROT:
+            printf("# write to non-writeable memory at 0x%"PRIx64 ", data size = %u, data value = 0x%"PRIx64 "\n", addr, size, value);
+
+            if (uc_mem_read(handle, addr, (uint8_t*)&testval, sizeof(testval)) != UC_ERR_OK) {
+                printf("not ok %d - uc_mem_read fail for address: 0x%" PRIx64 "\n", log_num++, addr);
+            } else {
+                printf("ok %d - uc_mem_read success after mem_protect at test %d\n", log_num++, test_num - 1);
+            }
+
+            if (uc_mem_protect(handle, addr & ~0xfffL, 0x1000, UC_PROT_READ | UC_PROT_WRITE) != UC_ERR_OK) {
+                printf("not ok %d - uc_mem_protect fail during hook_mem_invalid callback, addr: 0x%" PRIx64 "\n", log_num++, addr);
+            } else {
+                printf("ok %d - uc_mem_protect success\n", log_num++);
+            }
+            return true;
+    }
+}
+
+int main(int argc, char **argv, char **envp)
+{
+    uch handle, trace1, trace2;
+    uc_err err;
+    uint32_t addr, testval;
+    int32_t buf1[1024], buf2[1024], readbuf[1024];
+    int i;
+
+    //don't really care about quality of randomness
+    srand(time(NULL));
+    for (i = 0; i < 1024; i++) {
+        buf1[i] = rand();
+        buf2[i] = rand();
+    }
+
+    printf("# Memory protect test\n");
+
+    // Initialize emulator in X86-32bit mode
+    err = uc_open(UC_ARCH_X86, UC_MODE_32, &handle);
+    if (err) {
+        printf("not ok %d - Failed on uc_open() with error returned: %u\n", log_num++, err);
+        return 1;
+    } else {
+        printf("ok %d - uc_open() success\n", log_num++);
+    }
+
+    uc_mem_map(handle, CODE_SECTION, CODE_SIZE, UC_PROT_READ | UC_PROT_EXEC);
+    uc_mem_map(handle, 0x200000, 0x1000, UC_PROT_READ | UC_PROT_WRITE);
+    uc_mem_map(handle, 0x300000, 0x1000, UC_PROT_READ | UC_PROT_WRITE);
+    uc_mem_map(handle, 0x3ff000, 0x3000, UC_PROT_READ | UC_PROT_WRITE);
+
+    // fill in sections that shouldn't get touched
+    if (uc_mem_write(handle, 0x3ff000, (uint8_t*)buf1, 4096)) {
+        printf("not ok %d - Failed to write random buffer 1 to memory, quit!\n", log_num++);
+        return 2;
+    } else {
+        printf("ok %d - Random buffer 1 written to memory\n", log_num++);
+    }
+
+    if (uc_mem_write(handle, 0x401000, (uint8_t*)buf2, 4096)) {
+        printf("not ok %d - Failed to write random buffer 2 to memory, quit!\n", log_num++);
+        return 3;
+    } else {
+        printf("ok %d - Random buffer 2 written to memory\n", log_num++);
+    }
+
+    // write machine code to be emulated to memory
+    if (uc_mem_write(handle, CODE_SECTION, PROGRAM, sizeof(PROGRAM))) {
+        printf("not ok %d - Failed to write emulation code to memory, quit!\n", log_num++);
+        return 4;
+    } else {
+        printf("ok %d - Program written to memory\n", log_num++);
+    }
+
+    if (uc_hook_add(handle, &trace2, UC_HOOK_CODE, hook_code, NULL, (uint64_t)1, (uint64_t)0) != UC_ERR_OK) {
+        printf("not ok %d - Failed to install UC_HOOK_CODE handler\n", log_num++);
+        return 5;
+    } else {
+        printf("ok %d - UC_HOOK_CODE installed\n", log_num++);
+    }
+
+    // intercept memory write events
+    if (uc_hook_add(handle, &trace1, UC_HOOK_MEM_WRITE, hook_mem_write, NULL, (uint64_t)1, (uint64_t)0) != UC_ERR_OK) {
+        printf("not ok %d - Failed to install UC_HOOK_MEM_WRITE handler\n", log_num++);
+        return 6;
+    } else {
+        printf("ok %d - UC_HOOK_MEM_WRITE installed\n", log_num++);
+    }
+
+    // intercept invalid memory events
+    if (uc_hook_add(handle, &trace1, UC_HOOK_MEM_INVALID, hook_mem_invalid, NULL) != UC_ERR_OK) {
+        printf("not ok %d - Failed to install UC_HOOK_MEM_INVALID handler\n", log_num++);
+        return 7;
+    } else {
+        printf("ok %d - UC_HOOK_MEM_INVALID installed\n", log_num++);
+    }
+
+    // emulate machine code until told to stop by hook_code
+    printf("# BEGIN execution\n");
+    err = uc_emu_start(handle, CODE_SECTION, CODE_SECTION + CODE_SIZE, 0, 0);
+    if (err != UC_ERR_OK) {
+        printf("not ok %d - Failure on uc_emu_start() with error %u:%s\n", log_num++, err, uc_strerror(err));
+        return 8;
+    } else {
+        printf("ok %d - uc_emu_start complete\n", log_num++);
+    }
+    printf("# END execution\n");
+
+    //read from the remapped memory
+    testval = 0x42424242;
+    for (addr = 0x200000; addr <= 0x400000; addr += 0x100000) {
+        uint32_t val;
+        if (uc_mem_read(handle, addr, (uint8_t*)&val, sizeof(val)) != UC_ERR_OK) {
+            printf("not ok %d - Failed uc_mem_read for address 0x%x\n", log_num++, addr);
+        } else {
+            printf("ok %d - Good uc_mem_read from 0x%x\n", log_num++, addr);
+        }
+        if (val != testval) {
+            printf("not ok %d - Read 0x%x, expected 0x%x\n", log_num++, val, testval);
+        } else {
+            printf("ok %d - Correct value retrieved\n", log_num++);
+        }
+        testval += 0x02020202;
+    }
+
+    //account for the two mods made by the machine code
+    buf1[512] = 0x47474747;
+    buf2[512] = 0x48484848;
+
+    //make sure that random blocks didn't get nuked
+    // fill in sections that shouldn't get touched
+    if (uc_mem_read(handle, 0x3ff000, (uint8_t*)readbuf, 4096)) {
+        printf("not ok %d - Failed to read random buffer 1 from memory\n", log_num++);
+    } else {
+        printf("ok %d - Random buffer 1 read from memory\n", log_num++);
+        if (memcmp(buf1, readbuf, 4096)) {
+            printf("not ok %d - Random buffer 1 contents are incorrect\n", log_num++);
+        } else {
+            printf("ok %d - Random buffer 1 contents are correct\n", log_num++);
+        }
+    }
+
+    if (uc_mem_read(handle, 0x401000, (uint8_t*)readbuf, 4096)) {
+        printf("not ok %d - Failed to read random buffer 2 from memory\n", log_num++);
+    } else {
+        printf("ok %d - Random buffer 2 read from memory\n", log_num++);
+        if (memcmp(buf2, readbuf, 4096)) {
+            printf("not ok %d - Random buffer 2 contents are incorrect\n", log_num++);
+        } else {
+            printf("ok %d - Random buffer 2 contents are correct\n", log_num++);
+        }
+    }
+
+    if (uc_close(&handle) == UC_ERR_OK) {
+        printf("ok %d - uc_close complete\n", log_num++);
+    } else {
+        printf("not ok %d - uc_close complete\n", log_num++);
+    }
+
+    return 0;
+}
diff --git a/samples/mem_unmap.c b/samples/mem_unmap.c
new file mode 100644
index 00000000..e35b95ba
--- /dev/null
+++ b/samples/mem_unmap.c
@@ -0,0 +1,292 @@
+/*
+
+   uc_mem_unmap demo / unit test
+
+   Copyright(c) 2015 Chris Eagle
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License
+   version 2 as published by the Free Software Foundation.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+ */
+
+#define __STDC_FORMAT_MACROS
+#include <inttypes.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+#include <unicorn/unicorn.h>
+
+unsigned char PROGRAM[] =
+    "\xc7\x05\x00\x00\x20\x00\x41\x41\x41\x41\x90\xc7\x05\x00\x00\x20"
+    "\x00\x42\x42\x42\x42\xc7\x05\x00\x00\x30\x00\x43\x43\x43\x43\x90"
+    "\xc7\x05\x00\x00\x30\x00\x44\x44\x44\x44\xc7\x05\x00\x00\x40\x00"
+    "\x45\x45\x45\x45\x90\xc7\x05\x00\x00\x40\x00\x46\x46\x46\x46\xf4";
+    // total size: 64 bytes
+
+/*
+   ; assumes code section at 0x100000
+   ; assumes data section at 0x200000, initially rw
+   ; assumes data section at 0x300000, initially rw
+   ; assumes data section at 0x400000, initially rw
+
+   ; with installed hooks unmaps or maps on each nop
+
+   mov dword [0x200000], 0x41414141
+   nop                              ; unmap it
+   mov dword [0x200000], 0x42424242
+
+   mov dword [0x300000], 0x43434343
+   nop                              ; unmap it
+   mov dword [0x300000], 0x44444444
+
+   mov dword [0x400000], 0x45454545
+   nop                              ; unmap it
+   mov dword [0x400000], 0x46464646
+
+   hlt    ; tell hook function we are done
+ */
+
+int test_num  = 0;
+uint32_t tests[] = {
+    0x41414141,
+    0x43434343,
+    0x45454545
+};
+
+static int log_num = 1;
+
+#define CODE_SECTION 0x100000
+#define CODE_SIZE 0x1000
+
+// callback for tracing instruction
+static void hook_code(uch handle, uint64_t addr, uint32_t size, void *user_data)
+{
+    uint8_t opcode;
+    uint32_t testval;
+    if (uc_mem_read(handle, addr, &opcode, 1) != UC_ERR_OK) {
+        printf("not ok %d - uc_mem_read fail during hook_code callback, addr: 0x%" PRIx64 "\n", log_num++, addr);
+    }
+    printf("ok %d - uc_mem_read for opcode at address 0x%" PRIx64 "\n", log_num++, addr);
+    switch (opcode) {
+        case 0x90:  //nop
+            printf("# Handling NOP\n");
+            if (uc_mem_read(handle, 0x200000 + test_num * 0x100000, (uint8_t*)&testval, sizeof(testval)) != UC_ERR_OK) {
+                printf("not ok %d - uc_mem_read fail for address: 0x%x\n", log_num++, 0x200000 + test_num * 0x100000);
+            } else {
+                printf("ok %d - good uc_mem_read for address: 0x%x\n", log_num++, 0x200000 + test_num * 0x100000);
+                printf("# uc_mem_read for test %d\n", test_num);
+
+                if (testval == tests[test_num]) {
+                    printf("ok %d - passed test %d\n", log_num++, test_num);
+                } else {
+                    printf("not ok %d - failed test %d\n", log_num++, test_num);
+                    printf("# Expected: 0x%x\n",tests[test_num]);
+                    printf("# Received: 0x%x\n", testval);
+                }
+            }
+            if (uc_mem_unmap(handle, 0x200000 + test_num * 0x100000, 0x1000) != UC_ERR_OK) {
+                printf("not ok %d - uc_mem_unmap fail during hook_code callback, addr: 0x%x\n", log_num++, 0x200000 + test_num * 0x100000);
+            } else {
+                printf("ok %d - uc_mem_unmap success\n", log_num++);
+            }
+            test_num++;
+            break;
+        case 0xf4:  //hlt
+            printf("# Handling HLT\n");
+            if (uc_emu_stop(handle) != UC_ERR_OK) {
+                printf("not ok %d - uc_emu_stop fail during hook_code callback, addr: 0x%" PRIx64 "\n", log_num++, addr);
+                _exit(-1);
+            } else {
+                printf("ok %d - hlt encountered, uc_emu_stop called\n", log_num++);
+            }
+            break;
+        default:  //all others
+            printf("# Handling OTHER\n");
+            break;
+    }
+}
+
+// callback for tracing memory access (READ or WRITE)
+static void hook_mem_write(uch handle, uc_mem_type type,
+        uint64_t addr, int size, int64_t value, void *user_data)
+{
+    printf("# write to memory at 0x%"PRIx64 ", data size = %u, data value = 0x%"PRIx64 "\n", addr, size, value);
+}
+
+// callback for tracing invalid memory access (READ or WRITE)
+static bool hook_mem_invalid(uch handle, uc_mem_type type,
+        uint64_t addr, int size, int64_t value, void *user_data)
+{
+    uint32_t testval;
+    switch(type) {
+        default:
+            printf("not ok %d - UC_HOOK_MEM_INVALID type: %d at 0x%" PRIx64 "\n", log_num++, type, addr);
+            return false;
+        case UC_MEM_WRITE:
+            printf("# write to invalid memory at 0x%"PRIx64 ", data size = %u, data value = 0x%"PRIx64 "\n", addr, size, value);
+
+            if (uc_mem_read(handle, addr, (uint8_t*)&testval, sizeof(testval)) != UC_ERR_OK) {
+                printf("ok %d - uc_mem_read fail for address: 0x%" PRIx64 "\n", log_num++, addr);
+            } else {
+                printf("not ok %d - uc_mem_read success after unmap at test %d\n", log_num++, test_num - 1);
+            }
+
+            if (uc_mem_map(handle, addr & ~0xfffL, 0x1000, UC_PROT_READ | UC_PROT_WRITE) != UC_ERR_OK) {
+                printf("not ok %d - uc_mem_map fail during hook_mem_invalid callback, addr: 0x%" PRIx64 "\n", log_num++, addr);
+            } else {
+                printf("ok %d - uc_mem_map success\n", log_num++);
+            }
+            return true;
+    }
+}
+
+int main(int argc, char **argv, char **envp)
+{
+    uch handle, trace1, trace2;
+    uc_err err;
+    uint32_t addr, testval;
+    int32_t buf1[1024], buf2[1024], readbuf[1024];
+    int i;
+
+    //don't really care about quality of randomness
+    srand(time(NULL));
+    for (i = 0; i < 1024; i++) {
+        buf1[i] = rand();
+        buf2[i] = rand();
+    }
+
+    printf("# Memory unmapping test\n");
+
+    // Initialize emulator in X86-32bit mode
+    err = uc_open(UC_ARCH_X86, UC_MODE_32, &handle);
+    if (err) {
+        printf("not ok %d - Failed on uc_open() with error returned: %u\n", log_num++, err);
+        return 1;
+    } else {
+        printf("ok %d - uc_open() success\n", log_num++);
+    }
+
+    uc_mem_map(handle, CODE_SECTION, CODE_SIZE, UC_PROT_READ | UC_PROT_EXEC);
+    uc_mem_map(handle, 0x200000, 0x1000, UC_PROT_READ | UC_PROT_WRITE);
+    uc_mem_map(handle, 0x300000, 0x1000, UC_PROT_READ | UC_PROT_WRITE);
+    uc_mem_map(handle, 0x3ff000, 0x3000, UC_PROT_READ | UC_PROT_WRITE);
+
+    // fill in sections that shouldn't get touched
+    if (uc_mem_write(handle, 0x3ff000, (uint8_t*)buf1, 4096)) {
+        printf("not ok %d - Failed to write random buffer 1 to memory, quit!\n", log_num++);
+        return 2;
+    } else {
+        printf("ok %d - Random buffer 1 written to memory\n", log_num++);
+    }
+
+    if (uc_mem_write(handle, 0x401000, (uint8_t*)buf2, 4096)) {
+        printf("not ok %d - Failed to write random buffer 2 to memory, quit!\n", log_num++);
+        return 3;
+    } else {
+        printf("ok %d - Random buffer 2 written to memory\n", log_num++);
+    }
+
+    // write machine code to be emulated to memory
+    if (uc_mem_write(handle, CODE_SECTION, PROGRAM, sizeof(PROGRAM))) {
+        printf("not ok %d - Failed to write emulation code to memory, quit!\n", log_num++);
+        return 4;
+    } else {
+        printf("ok %d - Program written to memory\n", log_num++);
+    }
+
+    if (uc_hook_add(handle, &trace2, UC_HOOK_CODE, hook_code, NULL, (uint64_t)1, (uint64_t)0) != UC_ERR_OK) {
+        printf("not ok %d - Failed to install UC_HOOK_CODE handler\n", log_num++);
+        return 5;
+    } else {
+        printf("ok %d - UC_HOOK_CODE installed\n", log_num++);
+    }
+
+    // intercept memory write events
+    if (uc_hook_add(handle, &trace1, UC_HOOK_MEM_WRITE, hook_mem_write, NULL, (uint64_t)1, (uint64_t)0) != UC_ERR_OK) {
+        printf("not ok %d - Failed to install UC_HOOK_MEM_WRITE handler\n", log_num++);
+        return 6;
+    } else {
+        printf("ok %d - UC_HOOK_MEM_WRITE installed\n", log_num++);
+    }
+
+    // intercept invalid memory events
+    if (uc_hook_add(handle, &trace1, UC_HOOK_MEM_INVALID, hook_mem_invalid, NULL) != UC_ERR_OK) {
+        printf("not ok %d - Failed to install UC_HOOK_MEM_INVALID handler\n", log_num++);
+        return 7;
+    } else {
+        printf("ok %d - UC_HOOK_MEM_INVALID installed\n", log_num++);
+    }
+
+    // emulate machine code until told to stop by hook_code
+    printf("# BEGIN execution\n");
+    err = uc_emu_start(handle, CODE_SECTION, CODE_SECTION + CODE_SIZE, 0, 0);
+    if (err != UC_ERR_OK) {
+        printf("not ok %d - Failure on uc_emu_start() with error %u:%s\n", log_num++, err, uc_strerror(err));
+        return 8;
+    } else {
+        printf("ok %d - uc_emu_start complete\n", log_num++);
+    }
+    printf("# END execution\n");
+
+    //read from the remapped memory
+    testval = 0x42424242;
+    for (addr = 0x200000; addr <= 0x400000; addr += 0x100000) {
+        uint32_t val;
+        if (uc_mem_read(handle, addr, (uint8_t*)&val, sizeof(val)) != UC_ERR_OK) {
+            printf("not ok %d - Failed uc_mem_read for address 0x%x\n", log_num++, addr);
+        } else {
+            printf("ok %d - Good uc_mem_read from 0x%x\n", log_num++, addr);
+        }
+        if (val != testval) {
+            printf("not ok %d - Read 0x%x, expected 0x%x\n", log_num++, val, testval);
+        } else {
+            printf("ok %d - Correct value retrieved\n", log_num++);
+        }
+        testval += 0x02020202;
+    }
+
+    //make sure that random blocks didn't get nuked
+    // fill in sections that shouldn't get touched
+    if (uc_mem_read(handle, 0x3ff000, (uint8_t*)readbuf, 4096)) {
+        printf("not ok %d - Failed to read random buffer 1 from memory\n", log_num++);
+    } else {
+        printf("ok %d - Random buffer 1 read from memory\n", log_num++);
+        if (memcmp(buf1, readbuf, 4096)) {
+            printf("not ok %d - Random buffer 1 contents are incorrect\n", log_num++);
+        } else {
+            printf("ok %d - Random buffer 1 contents are correct\n", log_num++);
+        }
+    }
+
+    if (uc_mem_read(handle, 0x401000, (uint8_t*)readbuf, 4096)) {
+        printf("not ok %d - Failed to read random buffer 2 from memory\n", log_num++);
+    } else {
+        printf("ok %d - Random buffer 2 read from memory\n", log_num++);
+        if (memcmp(buf2, readbuf, 4096)) {
+            printf("not ok %d - Random buffer 2 contents are incorrect\n", log_num++);
+        } else {
+            printf("ok %d - Random buffer 2 contents are correct\n", log_num++);
+        }
+    }
+
+    if (uc_close(&handle) == UC_ERR_OK) {
+        printf("ok %d - uc_close complete\n", log_num++);
+    } else {
+        printf("not ok %d - uc_close complete\n", log_num++);
+    }
+
+    return 0;
+}
diff --git a/samples/sample_sparc.c b/samples/sample_sparc.c
index 36536680..ab9a9867 100644
--- a/samples/sample_sparc.c
+++ b/samples/sample_sparc.c
@@ -64,7 +64,7 @@ static void test_sparc(void)
 
     // emulate machine code in infinite time (last param = 0), or when
     // finishing all the code.
-    err = uc_emu_start(uc, ADDRESS, ADDRESS + sizeof(SPARC_CODE) -1, 0, 0);
+    err = uc_emu_start(uc, ADDRESS, ADDRESS + sizeof(SPARC_CODE) - 1, 0, 0);
     if (err) {
         printf("Failed on uc_emu_start() with error returned: %u (%s)\n",
                 err, uc_strerror(err));
diff --git a/uc.c b/uc.c
index cc25918a..49d29cfd 100644
--- a/uc.c
+++ b/uc.c
@@ -31,6 +31,9 @@
 
 #include "qemu/include/hw/boards.h"
 
+static uint8_t *copy_region(struct uc_struct *uc, MemoryRegion *mr);
+static bool split_region(struct uc_struct *uc, MemoryRegion *mr, uint64_t address, size_t size, bool do_delete);
+
 UNICORN_EXPORT
 unsigned int uc_version(unsigned int *major, unsigned int *minor)
 {
@@ -58,8 +61,8 @@ const char *uc_strerror(uc_err code)
             return "Unknown error code";
         case UC_ERR_OK:
             return "OK (UC_ERR_OK)";
-        case UC_ERR_OOM:
-            return "Out of memory (UC_ERR_OOM)";
+        case UC_ERR_NOMEM:
+            return "No memory available or memory not present (UC_ERR_NOMEM)";
         case UC_ERR_ARCH:
             return "Invalid/unsupported architecture(UC_ERR_ARCH)";
         case UC_ERR_HANDLE:
@@ -80,10 +83,14 @@ const char *uc_strerror(uc_err code)
             return "Invalid hook type (UC_ERR_HOOK)";
         case UC_ERR_MAP:
             return "Invalid memory mapping (UC_ERR_MAP)";
-        case UC_ERR_MEM_WRITE_NW:
-            return "Write to non-writable (UC_ERR_MEM_WRITE_NW)";
-        case UC_ERR_MEM_READ_NR:
-            return "Read from non-readable (UC_ERR_MEM_READ_NR)";
+        case UC_ERR_WRITE_PROT:
+            return "Write to write-protected memory (UC_ERR_WRITE_PROT)";
+        case UC_ERR_READ_PROT:
+            return "Read from non-readable memory (UC_ERR_READ_PROT)";
+        case UC_ERR_EXEC_PROT:
+            return "Fetch from non-executable memory (UC_ERR_EXEC_PROT)";
+        case UC_ERR_INVAL:
+            return "Invalid argumet (UC_ERR_INVAL)";
     }
 }
 
@@ -129,7 +136,7 @@ uc_err uc_open(uc_arch arch, uc_mode mode, ucengine **result)
         uc = calloc(1, sizeof(*uc));
         if (!uc) {
             // memory insufficient
-            return UC_ERR_OOM;
+            return UC_ERR_NOMEM;
         }
 
         uc->errnum = UC_ERR_OK;
@@ -522,7 +529,7 @@ static int _hook_code(ucengine *uc, int type, uint64_t begin, uint64_t end,
 
     i = hook_add(uc, type, begin, end, callback, user_data);
     if (i == 0)
-        return UC_ERR_OOM;  // FIXME
+        return UC_ERR_NOMEM;  // FIXME
 
     *hh = i;
 
@@ -538,7 +545,7 @@ static uc_err _hook_mem_access(ucengine *uc, uc_hook_t type,
 
     i = hook_add(uc, type, begin, end, callback, user_data);
     if (i == 0)
-        return UC_ERR_OOM;  // FIXME
+        return UC_ERR_NOMEM;  // FIXME
 
     *hh = i;
 
@@ -552,24 +559,25 @@ uc_err uc_mem_map(ucengine *uc, uint64_t address, size_t size, uint32_t perms)
 
     if (size == 0)
         // invalid memory mapping
-        return UC_ERR_MAP;
+        return UC_ERR_INVAL;
 
-    // address must be aligned to 4KB
-    if ((address & (4*1024 - 1)) != 0)
-        return UC_ERR_MAP;
+    // address must be aligned to uc->target_page_size
+    if ((address & uc->target_page_align) != 0)
+        return UC_ERR_INVAL;
 
-    // size must be multiple of 4KB
-    if ((size & (4*1024 - 1)) != 0)
-        return UC_ERR_MAP;
+    // size must be multiple of uc->target_page_size
+    if ((size & uc->target_page_align) != 0)
+        return UC_ERR_INVAL;
 
     // check for only valid permissions
-    if ((perms & ~(UC_PROT_READ | UC_PROT_WRITE)) != 0)
-        return UC_ERR_MAP;
+    if ((perms & ~UC_PROT_ALL) != 0)
+        return UC_ERR_INVAL;
 
     if ((uc->mapped_block_count & (MEM_BLOCK_INCR - 1)) == 0) {  //time to grow
-        regions = (MemoryRegion**)realloc(uc->mapped_blocks, sizeof(MemoryRegion*) * (uc->mapped_block_count + MEM_BLOCK_INCR));
+        regions = (MemoryRegion**)realloc(uc->mapped_blocks,
+                sizeof(MemoryRegion*) * (uc->mapped_block_count + MEM_BLOCK_INCR));
         if (regions == NULL) {
-            return UC_ERR_OOM;
+            return UC_ERR_NOMEM;
         }
         uc->mapped_blocks = regions;
     }
@@ -579,7 +587,224 @@ uc_err uc_mem_map(ucengine *uc, uint64_t address, size_t size, uint32_t perms)
     return UC_ERR_OK;
 }
 
-MemoryRegion *memory_mapping(ucengine* uc, uint64_t address)
+// Create a backup copy of the indicated MemoryRegion.
+// Generally used in prepartion for splitting a MemoryRegion.
+static uint8_t *copy_region(uch handle, MemoryRegion *mr)
+{
+    uint8_t *block = (uint8_t *)malloc(int128_get64(mr->size));
+    if (block != NULL) {
+        uc_err err = uc_mem_read(handle, mr->addr, block, int128_get64(mr->size));
+        if (err != UC_ERR_OK) {
+            free(block);
+            block = NULL;
+        }
+    }
+
+    return block;
+}
+
+/*
+   Split the given MemoryRegion at the indicated address for the indicated size
+   this may result in the create of up to 3 spanning sections. If the delete
+   parameter is true, the no new section will be created to replace the indicate
+   range. This functions exists to support uc_mem_protect and uc_mem_unmap.
+
+   This is a static function and callers have already done some preliminary 
+   parameter validation.
+   
+   The do_delete argument indicates that we are being called to support
+   uc_mem_unmap. In this case we save some time by choosing NOT to remap
+   the areas that are intended to get unmapped
+ */
+// TODO: investigate whether qemu region manipulation functions already offered
+// this capability
+static bool split_region(uch handle, MemoryRegion *mr, uint64_t address,
+        size_t size, bool do_delete)
+{
+    uint8_t *backup;
+    uint32_t perms;
+    uint64_t begin, end, chunk_end;
+    size_t l_size, m_size, r_size;
+
+    chunk_end = address + size;
+
+    // if this region belongs to area [address, address+size],
+    // then there is no work to do.
+    if (address <= mr->addr && chunk_end >= mr->end)
+        return true;
+
+    if (size == 0)
+        // trivial case
+        return true;
+
+    if (address >= mr->end || chunk_end <= mr->addr)
+        // impossible case
+        return false;
+
+    backup = copy_region(handle, mr);
+    if (backup == NULL)
+        return false;
+
+    // save the essential information required for the split before mr gets deleted
+    perms = mr->perms;
+    begin = mr->addr;
+    end = mr->end;
+
+    // unmap this region first, then do split it later
+    if (uc_mem_unmap(handle, mr->addr, int128_get64(mr->size)) != UC_ERR_OK)
+        goto error;
+
+    /* overlapping cases
+     *               |------mr------|
+     * case 1    |---size--|
+     * case 2           |--size--|
+     * case 3                  |---size--|
+     */
+
+    // adjust some things
+    if (address < begin)
+        address = begin;
+    if (chunk_end > end)
+        chunk_end = end;
+
+    // compute sub region sizes
+    l_size = (size_t)(address - begin);
+    r_size = (size_t)(end - chunk_end);
+    m_size = (size_t)(chunk_end - address);
+
+    // If there are error in any of the below operations, things are too far gone
+    // at that point to recover. Could try to remap orignal region, but these smaller
+    // allocation just failed so no guarantee that we can recover the original
+    // allocation at this point
+    if (l_size > 0) {
+        if (uc_mem_map(handle, begin, l_size, perms) != UC_ERR_OK)
+            goto error;
+        if (uc_mem_write(handle, begin, backup, l_size) != UC_ERR_OK)
+            goto error;
+    }
+
+    if (m_size > 0 && !do_delete) {
+        if (uc_mem_map(handle, address, m_size, perms) != UC_ERR_OK)
+            goto error;
+        if (uc_mem_write(handle, address, backup + l_size, m_size) != UC_ERR_OK)
+            goto error;
+    }
+
+    if (r_size > 0) {
+        if (uc_mem_map(handle, chunk_end, r_size, perms) != UC_ERR_OK)
+            goto error;
+        if (uc_mem_write(handle, chunk_end, backup + l_size + m_size, r_size) != UC_ERR_OK)
+            goto error;
+    }
+
+    return true;
+
+error:
+    free(backup);
+    return false;
+}
+
+UNICORN_EXPORT
+uc_err uc_mem_protect(uch handle, uint64_t address, size_t size, uint32_t perms)
+{
+    struct uc_struct* uc = (struct uc_struct *)handle;
+    MemoryRegion *mr;
+    uint64_t addr = address;
+    size_t count, len;
+
+    if (handle == 0)
+        // invalid handle
+        return UC_ERR_UCH;
+
+    if (size == 0)
+        // trivial case, no change
+        return UC_ERR_OK;
+
+    // address must be aligned to uc->target_page_size
+    if ((address & uc->target_page_align) != 0)
+        return UC_ERR_INVAL;
+
+    // size must be multiple of uc->target_page_size
+    if ((size & uc->target_page_align) != 0)
+        return UC_ERR_INVAL;
+
+    // check for only valid permissions
+    if ((perms & ~UC_PROT_ALL) != 0)
+        return UC_ERR_INVAL;
+
+    // check that user's entire requested block is mapped
+    if (!check_mem_area(uc, address, size))
+        return UC_ERR_NOMEM;
+
+    // Now we know entire region is mapped, so change permissions
+    // We may need to split regions if this area spans adjacent regions
+    addr = address;
+    count = 0;
+    while(count < size) {
+        mr = memory_mapping(uc, addr);
+        len = MIN(size - count, mr->end - addr);
+        if (!split_region(handle, mr, addr, len, false))
+            return UC_ERR_NOMEM;
+
+        mr = memory_mapping(uc, addr);
+        mr->perms = perms;
+        uc->readonly_mem(mr, (perms & UC_PROT_WRITE) == 0);
+
+        count += len;
+        addr += len;
+    }
+    return UC_ERR_OK;
+}
+
+UNICORN_EXPORT
+uc_err uc_mem_unmap(uch handle, uint64_t address, size_t size)
+{
+    MemoryRegion *mr;
+    struct uc_struct* uc = (struct uc_struct *)handle;
+    uint64_t addr;
+    size_t count, len;
+
+    if (handle == 0)
+        // invalid handle
+        return UC_ERR_UCH;
+
+    if (size == 0)
+        // nothing to unmap
+        return UC_ERR_OK;
+
+    // address must be aligned to uc->target_page_size
+    if ((address & uc->target_page_align) != 0)
+        return UC_ERR_INVAL;
+
+    // size must be multiple of uc->target_page_size
+    if ((size & uc->target_page_align) != 0)
+        return UC_ERR_MAP;
+
+    // check that user's entire requested block is mapped
+    if (!check_mem_area(uc, address, size))
+        return UC_ERR_NOMEM;
+
+    // Now we know entire region is mapped, so do the unmap
+    // We may need to split regions if this area spans adjacent regions
+    addr = address;
+    count = 0;
+    while(count < size) {
+        mr = memory_mapping(uc, addr);
+        len = MIN(size - count, mr->end - addr);
+        if (!split_region(handle, mr, addr, len, true))
+            return UC_ERR_NOMEM;
+        // if we can retrieve the mapping, then no splitting took place
+        // so unmap here
+        mr = memory_mapping(uc, addr);
+        if (mr != NULL)
+           uc->memory_unmap(uc, mr);
+        count += len;
+        addr += len;
+    }
+    return UC_ERR_OK;
+}
+
+MemoryRegion *memory_mapping(struct uc_struct* uc, uint64_t address)
 {
     unsigned int i;
 
@@ -607,7 +832,7 @@ static uc_err _hook_mem_invalid(struct uc_struct* uc, uc_cb_eventmem_t callback,
         uc->hook_mem_idx = i;
         return UC_ERR_OK;
     } else
-        return UC_ERR_OOM;
+        return UC_ERR_NOMEM;
 }
 
 
@@ -626,7 +851,7 @@ static uc_err _hook_intr(struct uc_struct* uc, void *callback,
         uc->hook_intr_idx = i;
         return UC_ERR_OK;
     } else
-        return UC_ERR_OOM;
+        return UC_ERR_NOMEM;
 }
 
 
@@ -650,7 +875,7 @@ static uc_err _hook_insn(struct uc_struct *uc, unsigned int insn_id, void *callb
                                   uc->hook_out_idx = i;
                                   return UC_ERR_OK;
                               } else
-                                  return UC_ERR_OOM;
+                                  return UC_ERR_NOMEM;
                      case UC_X86_INS_IN:
                               // FIXME: only one event handler at the same time
                               i = hook_find_new(uc);
@@ -661,7 +886,7 @@ static uc_err _hook_insn(struct uc_struct *uc, unsigned int insn_id, void *callb
                                   uc->hook_in_idx = i;
                                   return UC_ERR_OK;
                               } else
-                                  return UC_ERR_OOM;
+                                  return UC_ERR_NOMEM;
                      case UC_X86_INS_SYSCALL:
                      case UC_X86_INS_SYSENTER:
                               // FIXME: only one event handler at the same time
@@ -673,7 +898,7 @@ static uc_err _hook_insn(struct uc_struct *uc, unsigned int insn_id, void *callb
                                   uc->hook_syscall_idx = i;
                                   return UC_ERR_OK;
                               } else
-                                  return UC_ERR_OOM;
+                                  return UC_ERR_NOMEM;
                  }
                  break;
     }