lazy.patch

diff --git a/Makefile b/Makefile
index 09d790c..a1694cd 100644
--- a/Makefile
+++ b/Makefile
@@ -181,6 +181,8 @@ UPROGS=\
 	_usertests\
 	_wc\
 	_zombie\
+	_testprog\
+	_testprog2\
 
 fs.img: mkfs README $(UPROGS)
 	./mkfs fs.img README $(UPROGS)
@@ -248,9 +250,10 @@ qemu-nox-gdb: fs.img xv6.img .gdbinit
 # check in that version.
 
 EXTRA=\
-	mkfs.c ulib.c user.h cat.c echo.c forktest.c grep.c kill.c\
+	mkfs.c ulib.c user.h cat.c echo.c forktest.c grep.c kill.c testprog.c\
 	ln.c ls.c mkdir.c rm.c stressfs.c usertests.c wc.c zombie.c\
 	printf.c umalloc.c\
+	testprog.c\
 	README dot-bochsrc *.pl toc.* runoff runoff1 runoff.list\
 	.gdbinit.tmpl gdbutil\
 
diff --git a/defs.h b/defs.h
index 82fb982..9b850a3 100644
--- a/defs.h
+++ b/defs.h
@@ -172,6 +172,7 @@ void            uartputc(int);
 
 // vm.c
 void            seginit(void);
+int 			mappages(pde_t*,void*,uint,uint,int);
 void            kvmalloc(void);
 pde_t*          setupkvm(void);
 char*           uva2ka(pde_t*, char*);
diff --git a/kernel.ld b/kernel.ld
index 4e12e14..e24c860 100644
--- a/kernel.ld
+++ b/kernel.ld
@@ -26,12 +26,16 @@ SECTIONS
 		PROVIDE(__STAB_BEGIN__ = .);
 		*(.stab);
 		PROVIDE(__STAB_END__ = .);
+		BYTE(0)		/* Force the linker to allocate space
+				   for this section */
 	}
 
 	.stabstr : {
 		PROVIDE(__STABSTR_BEGIN__ = .);
 		*(.stabstr);
 		PROVIDE(__STABSTR_END__ = .);
+		BYTE(0)		/* Force the linker to allocate space
+				   for this section */
 	}
 
 	/* Adjust the address for the data segment to the next page */
diff --git a/syscall.c b/syscall.c
index ee85261..13db545 100644
--- a/syscall.c
+++ b/syscall.c
@@ -103,6 +103,8 @@ extern int sys_unlink(void);
 extern int sys_wait(void);
 extern int sys_write(void);
 extern int sys_uptime(void);
+extern int sys_count_virtual_pages(void);
+extern int sys_count_physical_pages(void);
 
 static int (*syscalls[])(void) = {
 [SYS_fork]    sys_fork,
@@ -126,6 +128,8 @@ static int (*syscalls[])(void) = {
 [SYS_link]    sys_link,
 [SYS_mkdir]   sys_mkdir,
 [SYS_close]   sys_close,
+[SYS_count_virtual_pages]   sys_count_virtual_pages,
+[SYS_count_physical_pages]  sys_count_physical_pages,
 };
 
 void
@@ -143,3 +147,4 @@ syscall(void)
     curproc->tf->eax = -1;
   }
 }
+
diff --git a/syscall.h b/syscall.h
index bc5f356..5bee4bc 100644
--- a/syscall.h
+++ b/syscall.h
@@ -20,3 +20,5 @@
 #define SYS_link   19
 #define SYS_mkdir  20
 #define SYS_close  21
+#define SYS_count_virtual_pages 22
+#define SYS_count_physical_pages 23
diff --git a/sysproc.c b/sysproc.c
index 0686d29..82fa341 100644
--- a/sysproc.c
+++ b/sysproc.c
@@ -47,12 +47,15 @@ sys_sbrk(void)
 {
   int addr;
   int n;
-
+  //Have to increase proc size by n bytes
   if(argint(0, &n) < 0)
     return -1;
   addr = myproc()->sz;
-  if(growproc(n) < 0)
-    return -1;
+  myproc()->sz = addr + n;
+  //cprintf("Proc size was %d and now is %d\n",addr-n,myproc()->sz);
+  //if n<0 then simply deallocate 
+  //if(growproc(n) < 0)
+  //  return -1;
   return addr;
 }
 
@@ -89,3 +92,34 @@ sys_uptime(void)
   release(&tickslock);
   return xticks;
 }
+
+int
+sys_count_virtual_pages(void)
+{
+  uint vsize;
+  vsize = myproc()->sz;
+  vsize = vsize/PGSIZE;
+  return vsize;
+}
+
+int sys_count_physical_pages(void)
+{
+  struct proc *curproc = myproc();
+  pde_t *pgdir = curproc->pgdir;
+  pde_t *pde;
+  pte_t *pgtab;
+  int i;int j;int cnt;cnt=0;
+  for(i=0;i<NPDENTRIES;++i){
+    pde = &pgdir[i];
+    if(*pde & PTE_P){
+      //cprintf("Directory %d is present :contents are  = %p\n ",i,*pde);
+      pgtab = (pte_t*)P2V(PTE_ADDR(*pde));
+      for(j=0;j<NPTENTRIES;++j){
+        if(pgtab[j] & PTE_P){
+          cnt++;
+        }
+      }
+    }
+  }
+  return cnt;
+}
diff --git a/trap.c b/trap.c
index 41c66eb..b4a2f08 100644
--- a/trap.c
+++ b/trap.c
@@ -36,6 +36,8 @@ idtinit(void)
 void
 trap(struct trapframe *tf)
 {
+  int va;
+  char* mem;
   if(tf->trapno == T_SYSCALL){
     if(myproc()->killed)
       exit();
@@ -77,7 +79,40 @@ trap(struct trapframe *tf)
             cpuid(), tf->cs, tf->eip);
     lapiceoi();
     break;
-
+  
+  case T_PGFLT:
+    //PAGEFAULT: 14 - allocate a new page
+    va = rcr2();
+    struct proc *curproc = myproc();
+    va = PGROUNDDOWN(va);
+    if(va <= curproc->sz){
+      //allocate page corresponding to va
+      //cprintf("Page not allocated at virtual address %d\n",va);
+      mem = kalloc();
+      if(mem == 0){
+        cprintf("allocuvm out of memory\n");
+        //deallocuvm(pgdir, newsz, oldsz);
+        //return 0;
+        myproc()->killed = 1;
+      }else{
+        memset(mem, 0, PGSIZE);
+        if(mappages(curproc->pgdir, (char*)va, PGSIZE, V2P(mem), PTE_W|PTE_U) < 0){
+          cprintf("allocuvm out of memory (2)\n");
+          //deallocuvm(pgdir, newsz, oldsz);
+          //kfree(mem);
+          myproc()->killed = 1;
+        }
+      }
+    }else{
+      //cprintf("Process size is %d\n",myproc()->sz);
+      //cprintf("Page fault at virtual address %d\n",va);
+      cprintf("pid %d %s: trap %d err %d on cpu %d "
+            "eip 0x%x addr 0x%x--kill proc\n",
+            myproc()->pid, myproc()->name, tf->trapno,
+            tf->err, cpuid(), tf->eip, rcr2());
+      myproc()->killed = 1;
+    }
+    break;
   //PAGEBREAK: 13
   default:
     if(myproc() == 0 || (tf->cs&3) == 0){
diff --git a/user.h b/user.h
index 4f99c52..ccc3c34 100644
--- a/user.h
+++ b/user.h
@@ -23,6 +23,8 @@ int getpid(void);
 char* sbrk(int);
 int sleep(int);
 int uptime(void);
+int count_virtual_pages(void);
+int count_physical_pages(void);
 
 // ulib.c
 int stat(const char*, struct stat*);
diff --git a/usys.S b/usys.S
index 8bfd8a1..24c9b81 100644
--- a/usys.S
+++ b/usys.S
@@ -29,3 +29,5 @@ SYSCALL(getpid)
 SYSCALL(sbrk)
 SYSCALL(sleep)
 SYSCALL(uptime)
+SYSCALL(count_virtual_pages)
+SYSCALL(count_physical_pages)
diff --git a/vm.c b/vm.c
index 7134cff..b6c31e0 100644
--- a/vm.c
+++ b/vm.c
@@ -57,7 +57,7 @@ walkpgdir(pde_t *pgdir, const void *va, int alloc)
 // Create PTEs for virtual addresses starting at va that refer to
 // physical addresses starting at pa. va and size might not
 // be page-aligned.
-static int
+int
 mappages(pde_t *pgdir, void *va, uint size, uint pa, int perm)
 {
   char *a, *last;
@@ -325,8 +325,8 @@ copyuvm(pde_t *pgdir, uint sz)
   for(i = 0; i < sz; i += PGSIZE){
     if((pte = walkpgdir(pgdir, (void *) i, 0)) == 0)
       panic("copyuvm: pte should exist");
-    if(!(*pte & PTE_P))
-      panic("copyuvm: page not present");
+    //if(!(*pte & PTE_P))
+    //  panic("copyuvm: page not present");
     pa = PTE_ADDR(*pte);
     flags = PTE_FLAGS(*pte);
     if((mem = kalloc()) == 0)