diff.txt

diff --git a/Makefile b/Makefile
index 2d2b9e4..d47164b 100644
--- a/Makefile
+++ b/Makefile
@@ -29,6 +29,7 @@ OBJS = \
 	vm.o\
 	shm.o\
 
+
 # Cross-compiling (e.g., on Mac OS X)
 # TOOLPREFIX = i386-jos-elf
 
@@ -177,6 +178,8 @@ UPROGS=\
 	_zombie\
 	_shm_cnt\
 	_null\
+	_lab3_test1\
+	_lab3_test2\
 
 fs.img: mkfs README $(UPROGS)
 	./mkfs fs.img README $(UPROGS)
diff --git a/exec.c b/exec.c
index b40134f..edf97f3 100644
--- a/exec.c
+++ b/exec.c
@@ -63,10 +63,12 @@ exec(char *path, char **argv)
   // Allocate two pages at the next page boundary.
   // Make the first inaccessible.  Use the second as the user stack.
   sz = PGROUNDUP(sz);
-  if((sz = allocuvm(pgdir, sz, sz + 2*PGSIZE)) == 0)
+    sp = KERNBASE-1; // put sp at 0x8
+  if((allocuvm(pgdir, sp - PGSIZE, sp )) == 0) // userstack + page guard
     goto bad;
-  clearpteu(pgdir, (char*)(sz - 2*PGSIZE));
-  sp = sz;
+  clearpteu(pgdir, (char*)(KERNBASE - 2*PGSIZE)); // create page guard starting from 2 page sizes below kernbase
+  sp = KERNBASE-4;
+  //curproc->topOfStack = sp - PGSIZE; // where user stack starts
 
   // Push argument strings, prepare rest of stack in ustack.
   for(argc = 0; argv[argc]; argc++) {
@@ -99,6 +101,7 @@ exec(char *path, char **argv)
   curproc->sz = sz;
   curproc->tf->eip = elf.entry;  // main
   curproc->tf->esp = sp;
+  curproc->stackNum = 1; // initialize stacknum
   switchuvm(curproc);
   freevm(oldpgdir);
   return 0;
diff --git a/proc.h b/proc.h
index 1647114..c89bd38 100644
--- a/proc.h
+++ b/proc.h
@@ -49,6 +49,7 @@ struct proc {
   struct file *ofile[NOFILE];  // Open files
   struct inode *cwd;           // Current directory
   char name[16];               // Process name (debugging)
+  uint stackNum;
 };
 
 // Process memory is laid out contiguously, low addresses first:
diff --git a/syscall.c b/syscall.c
index 94ef3c9..c888335 100644
--- a/syscall.c
+++ b/syscall.c
@@ -17,9 +17,9 @@
 int
 fetchint(uint addr, int *ip)
 {
-  struct proc *curproc = myproc();
+//  struct proc *curproc = myproc();
 
-  if(addr >= curproc->sz || addr+4 > curproc->sz)
+  if(addr >= KERNBASE-1 || addr+4 > KERNBASE-1) // these changes to access whole changes we made
     return -1;
   *ip = *(int*)(addr);
   return 0;
@@ -32,12 +32,12 @@ int
 fetchstr(uint addr, char **pp)
 {
   char *s, *ep;
-  struct proc *curproc = myproc();
+//  struct proc *curproc = myproc();
 
-  if(addr >= curproc->sz)
+  if(addr >= KERNBASE-1)
     return -1;
   *pp = (char*)addr;
-  ep = (char*)curproc->sz;
+  ep = (char*)KERNBASE-1;
   for(s = *pp; s < ep; s++){
     if(*s == 0)
       return s - *pp;
@@ -59,11 +59,11 @@ int
 argptr(int n, char **pp, int size)
 {
   int i;
-  struct proc *curproc = myproc();
+//  struct proc *curproc = myproc();
  
   if(argint(n, &i) < 0)
     return -1;
-  if(size < 0 || (uint)i >= curproc->sz || (uint)i+size > curproc->sz)
+  if(size < 0 || (uint)i >= KERNBASE-1 || (uint)i+size > KERNBASE-1)
     return -1;
   *pp = (char*)i;
   return 0;
diff --git a/trap.c b/trap.c
index 41c66eb..2474cdf 100644
--- a/trap.c
+++ b/trap.c
@@ -78,6 +78,25 @@ trap(struct trapframe *tf)
     lapiceoi();
     break;
 
+  case T_PGFLT:
+      if (KERNBASE > rcr2()) { //rcr2 address causing pagefault, checking if from userspace
+        if (tf->esp >= rcr2()) {
+            uint topOfStack = KERNBASE - myproc()->stackNum * PGSIZE; // right above page guard, where to start allocating
+            if (allocuvm(myproc()->pgdir, PGROUNDDOWN(topOfStack - 1), topOfStack - 1) == 0) { // check if we can allocate
+                cprintf("No new page can be allocated. \n");
+                exit();
+            }
+            myproc()->stackNum++;
+            cprintf("%d pages currently allocated. \n", myproc()->stackNum);
+        }
+      }
+      else {
+          cprintf("Address is out of bounds. \n");
+          exit();
+      }
+      break;
+
+
   //PAGEBREAK: 13
   default:
     if(myproc() == 0 || (tf->cs&3) == 0){
diff --git a/vm.c b/vm.c
index f623aa3..05c7b1a 100644
--- a/vm.c
+++ b/vm.c
@@ -224,7 +224,7 @@ allocuvm(pde_t *pgdir, uint oldsz, uint newsz)
   char *mem;
   uint a;
 
-  if(newsz >= KERNBASE)
+  if(newsz > KERNBASE)
     return 0;
   if(newsz < oldsz)
     return oldsz;
@@ -320,9 +320,11 @@ copyuvm(pde_t *pgdir, uint sz)
   uint pa, i, flags;
   char *mem;
 
+  struct proc *curproc = myproc();
+
   if((d = setupkvm()) == 0)
     return 0;
-  for(i = 0; i < sz; i += PGSIZE){
+  for(i = 0; i < curproc->sz ; i += PGSIZE){
     if((pte = walkpgdir(pgdir, (void *) i, 0)) == 0)
       panic("copyuvm: pte should exist");
     if(!(*pte & PTE_P))
@@ -335,6 +337,19 @@ copyuvm(pde_t *pgdir, uint sz)
     if(mappages(d, (void*)i, PGSIZE, V2P(mem), flags) < 0)
       goto bad;
   }
+    for(i = PGROUNDUP(KERNBASE - 1 - myproc()->stackNum * PGSIZE); i < KERNBASE ; i += PGSIZE){ // basically  go through userstack
+        if((pte = walkpgdir(pgdir, (void *) i, 0)) == 0)
+            panic("copyuvm: pte should exist");
+        if(!(*pte & PTE_P))
+            panic("copyuvm: page not present");
+        pa = PTE_ADDR(*pte);
+        flags = PTE_FLAGS(*pte);
+        if((mem = kalloc()) == 0)
+            goto bad;
+        memmove(mem, (char*)P2V(pa), PGSIZE);
+        if(mappages(d, (void*)i, PGSIZE, V2P(mem), flags) < 0)
+            goto bad;
+    }
   return d;
 
 bad: