diff --git a/src/arch/x86_64/include/arch/mmu.h b/src/arch/x86_64/include/arch/mmu.h
index 0e0ba80d..a4d387a7 100644
--- a/src/arch/x86_64/include/arch/mmu.h
+++ b/src/arch/x86_64/include/arch/mmu.h
@@ -14,6 +14,11 @@
 #define ARCH_MMU_MAP_PAGESIZE     (uint64_t)(1 << 7)
 #define ARCH_MMU_MAP_ACCESSED	  (uint64_t)(1 << 5)
 
+#define ARCH_MMU_ERROR_WRITE 2
+#define ARCH_MMU_ERROR_PRESENT 1
+#define ARCH_MMU_ERROR_USER 4
+#define ARCH_MMU_ERROR_INSTFETCH 16
+
 typedef uint64_t* arch_mmu_tableptr;
 
 int arch_mmu_map(arch_mmu_tableptr, void*, void*, size_t);
diff --git a/src/arch/x86_64/isr.c b/src/arch/x86_64/isr.c
index db9cbe26..b5a8544d 100644
--- a/src/arch/x86_64/isr.c
+++ b/src/arch/x86_64/isr.c
@@ -16,7 +16,7 @@ void isr_except(arch_regs *reg){
 
 void isr_pagefault(arch_regs *reg){
 	
-	if(!vmm_dealwithrequest(reg->cr2))
+	if(!vmm_dealwithrequest(reg->cr2, reg->error, reg->cs == 0x3b))
 		_panic("Page fault!", reg);
 	
 }
diff --git a/src/arch/x86_64/syscall.asm b/src/arch/x86_64/syscall.asm
index 9d18b207..4eec5bfd 100644
--- a/src/arch/x86_64/syscall.asm
+++ b/src/arch/x86_64/syscall.asm
@@ -4,13 +4,15 @@ section .rodata
 extern syscall_libc_log
 extern syscall_mmap
 extern syscall_arch_ctl
-func_count equ 3
+extern syscall_gettid
+func_count equ 4
 
 
 func_table:
 	dq syscall_libc_log
 	dq syscall_mmap
 	dq syscall_arch_ctl
+	dq syscall_gettid
 section .text
 global asm_syscall_entry
 
diff --git a/src/include/kernel/syscalls.h b/src/include/kernel/syscalls.h
index b40b9841..6346d411 100644
--- a/src/include/kernel/syscalls.h
+++ b/src/include/kernel/syscalls.h
@@ -11,5 +11,6 @@ typedef struct {
 
 syscallret syscall_libc_log(char* str);
 syscallret syscall_mmap(void* hint, size_t len, int prot, int flags, int fd, off_t offset);
+syscallret syscall_gettid();
 
 #endif
diff --git a/src/include/kernel/vmm.h b/src/include/kernel/vmm.h
index 5426caa4..b2b9c3bb 100644
--- a/src/include/kernel/vmm.h
+++ b/src/include/kernel/vmm.h
@@ -55,7 +55,7 @@ typedef struct {
 
 void vmm_init();
 
-bool 		vmm_dealwithrequest(void* addr);
+bool 		vmm_dealwithrequest(void* addr, long error, bool user);
 bool 		vmm_setused(void* addr, size_t pagec, size_t mmuflags);
 bool		vmm_unmap(void* addr, size_t pagec);
 bool		vmm_map(void* paddr, void* vaddr, size_t pagec, size_t mmuflags);
diff --git a/src/sys/mm/vmm.c b/src/sys/mm/vmm.c
index 707e61ff..c84a1955 100644
--- a/src/sys/mm/vmm.c
+++ b/src/sys/mm/vmm.c
@@ -395,14 +395,16 @@ void* vmm_allocfrom(void* addr, size_t mmuflags, size_t pagec){
 
 	spinlock_acquire(lock);
 	
-	addr = findfirstfreearea(findmappingfromaddr(*start, addr), pagec);
+	vmm_mapping* map = findmappingfromaddr(*start, addr);
+
+	addr = findfirstfreearea(map, pagec);
 
 	if(!addr)
 		goto _done;
 	
 	if(!setmap(start, addr, pagec, mmuflags, VMM_TYPE_ANON, 0, 0))
 		addr = NULL;
-
+	
 	_done:
 	
 	spinlock_release(lock);
@@ -514,8 +516,11 @@ bool vmm_allocnowat(void* addr, size_t mmuflags, size_t size){
 
 // called by the page fault handler
 
-bool vmm_dealwithrequest(void* addr){
+bool vmm_dealwithrequest(void* addr, long error, bool user){
 	
+	if(user && addr > USER_SPACE_END)
+		return false;
+
 	int* lock;
 	vmm_mapping** start = NULL;
 	
@@ -533,10 +538,27 @@ bool vmm_dealwithrequest(void* addr){
 		status = false;
 		goto done;
 	}
-	
+
 	if(map->type == VMM_TYPE_FILE)
 		_panic("File mappings are not supported (yet)", 0);
 
+	size_t goodmmuflags = 1;
+
+	if(error & ARCH_MMU_ERROR_WRITE)
+		goodmmuflags |= ARCH_MMU_MAP_WRITE;
+	
+	if(error & ARCH_MMU_ERROR_USER)
+		goodmmuflags |= ARCH_MMU_MAP_USER;
+	
+	if(error & ARCH_MMU_ERROR_INSTFETCH == 0)
+		goodmmuflags |= ARCH_MMU_MAP_NOEXEC;
+
+
+	if(goodmmuflags != (map->mmuflags & goodmmuflags))
+		return false;
+	
+
+
 	// allocate a page
 
 	addr = (size_t)addr & ~(0xFFF);
diff --git a/src/sys/sched/elf.c b/src/sys/sched/elf.c
index 6b064506..a82b19a2 100644
--- a/src/sys/sched/elf.c
+++ b/src/sys/sched/elf.c
@@ -304,7 +304,7 @@ int elf_load(thread_t* thread, vnode_t* node, char** argv, char** env){
 	// also load the executable memory image if we're using an interpreter
 	
 	if(interp){
-		for(size_t currentph = 0; currentph < header.ph_count; ++currentph){
+		for(size_t currentph = 0; currentph < progheader.ph_count; ++currentph){
 
 			// read ph
 
diff --git a/src/sys/syscalls/gettid.c b/src/sys/syscalls/gettid.c
new file mode 100644
index 00000000..3d33f658
--- /dev/null
+++ b/src/sys/syscalls/gettid.c
@@ -0,0 +1,9 @@
+#include <kernel/syscalls.h>
+#include <arch/cls.h>
+
+syscallret syscall_gettid(){
+	syscallret retv;
+	retv.errno = 0;
+	retv.ret = arch_getcls()->thread->tid;
+	return retv;
+}
diff --git a/src/sys/syscalls/mmap.c b/src/sys/syscalls/mmap.c
index 34e1206b..510b3095 100644
--- a/src/sys/syscalls/mmap.c
+++ b/src/sys/syscalls/mmap.c
@@ -45,6 +45,7 @@
 #define MFD_ALLOW_SEALING 2U
 
 syscallret syscall_mmap(void* hint, size_t len, int prot, int flags, int fd, off_t offset){
+
 	syscallret retv;
 	
 	retv.ret = -1;
@@ -79,10 +80,10 @@ syscallret syscall_mmap(void* hint, size_t len, int prot, int flags, int fd, off
 	void* ret = NULL;
 
 	if(hint)
-		ret = vmm_allocnowat(hint, mmuflags, plen) ? hint : NULL; // TODO demand page
+		ret = vmm_allocnowat(hint, mmuflags, len) ? hint : NULL; // TODO demand page
 	
 	if(!ret && !(flags & MAP_FIXED))
-		ret = vmm_allocfrom(USER_ALLOC_START, mmuflags, len);
+		ret = vmm_allocfrom(USER_ALLOC_START, mmuflags, plen);
 
 	if(!ret){
 		retv.errno = ENOMEM;