Lab pgtbl: ukvmcopy

kernel/defs.h

@@ -173,6 +173,7 @@ uint64          uvmdealloc(pagetable_t, uint64, uint64);
 #ifdef SOL_COW
 #else
 int             uvmcopy(pagetable_t, pagetable_t, uint64);
+int             ukvmcopy(pagetable_t, pagetable_t, uint64, uint64);
 #endif
 void            uvmfree(pagetable_t, uint64);
 void            uvmunmap(pagetable_t, uint64, uint64, int);
@@ -181,7 +182,9 @@ pte_t*          walk(pagetable_t, uint64, int);
 uint64          walkaddr(pagetable_t, uint64);
 int             copyout(pagetable_t, uint64, char *, uint64);
 int             copyin(pagetable_t, char *, uint64, uint64);
+int             copyin_new(pagetable_t, char *, uint64, uint64);
 int             copyinstr(pagetable_t, char *, uint64, uint64);
+int             copyinstr_new(pagetable_t, char *, uint64, uint64);
 void            vmprint(pagetable_t);
 
 // plic.c

kernel/exec.c

@@ -116,6 +116,8 @@ exec(char *path, char **argv)
   p->trapframe->sp = sp; // initial stack pointer
   proc_freepagetable(oldpagetable, oldsz);
 
+  ukvmcopy(p->pagetable, p->kpagetable, 0, p->sz);
+
   if (p->pid == 1) vmprint(p->pagetable);
 
   return argc; // this ends up in a0, the first argument to main(argc, argv)

kernel/proc.c

@@ -268,6 +268,8 @@ userinit(void)
   uvminit(p->pagetable, initcode, sizeof(initcode));
   p->sz = PGSIZE;
 
+  ukvmcopy(p->pagetable, p->kpagetable, 0, p->sz);
+
   // prepare for the very first "return" from kernel to user.
   p->trapframe->epc = 0;      // user program counter
   p->trapframe->sp = PGSIZE;  // user stack pointer
@@ -290,9 +292,13 @@ growproc(int n)
 
   sz = p->sz;
   if(n > 0){
+    // Prevent user process from growing larger than the PLIC address
+    if (PGROUNDUP(sz + n) > PLIC)
+      return -1;
     if((sz = uvmalloc(p->pagetable, sz, sz + n)) == 0) {
       return -1;
     }
+    ukvmcopy(p->pagetable, p->kpagetable, sz - n, sz);
   } else if(n < 0){
     sz = uvmdealloc(p->pagetable, sz, sz + n);
   }
@@ -322,6 +328,11 @@ fork(void)
   }
   np->sz = p->sz;
 
+  if (ukvmcopy(np->pagetable, np->kpagetable, 0, np->sz) < 0) {
+    release(&np->lock);
+    return -1;
+  }
+
   np->parent = p;
 
   // copy saved user registers.

kernel/vm.c

@@ -359,6 +359,29 @@ uvmcopy(pagetable_t old, pagetable_t new, uint64 sz)
   return -1;
 }
 
+// Copy the page table from old to new.
+int
+ukvmcopy(pagetable_t old, pagetable_t new, uint64 oldsz, uint64 newsz)
+{
+  pte_t *oldpte, *newpte;
+  uint64 pa, a;
+  uint flags;
+
+  oldsz = PGROUNDUP(oldsz);
+  for (a = oldsz; a < newsz; a += PGSIZE) {
+    if ((oldpte = walk(old, a, 0)) == 0)
+      panic("ukvmcopy: oldpte should exist");
+    if ((*oldpte & PTE_V) == 0)
+      panic("ukvmcopy: page not present");
+    if ((newpte = walk(new, a, 1)) == 0)
+      panic("ukvmcopy: newpte should exist");
+    pa = PTE2PA(*oldpte);
+    flags = PTE_FLAGS(*oldpte & ~PTE_U);
+    *newpte = PA2PTE(pa) | flags;
+  }
+  return 0;
+}
+
 // mark a PTE invalid for user access.
 // used by exec for the user stack guard page.
 void
@@ -403,23 +426,7 @@ copyout(pagetable_t pagetable, uint64 dstva, char *src, uint64 len)
 int
 copyin(pagetable_t pagetable, char *dst, uint64 srcva, uint64 len)
 {
-  uint64 n, va0, pa0;
-
-  while(len > 0){
-    va0 = PGROUNDDOWN(srcva);
-    pa0 = walkaddr(pagetable, va0);
-    if(pa0 == 0)
-      return -1;
-    n = PGSIZE - (srcva - va0);
-    if(n > len)
-      n = len;
-    memmove(dst, (void *)(pa0 + (srcva - va0)), n);
-
-    len -= n;
-    dst += n;
-    srcva = va0 + PGSIZE;
-  }
-  return 0;
+  return copyin_new(pagetable, dst, srcva, len);
 }
 
 // Copy a null-terminated string from user to kernel.
@@ -429,40 +436,7 @@ copyin(pagetable_t pagetable, char *dst, uint64 srcva, uint64 len)
 int
 copyinstr(pagetable_t pagetable, char *dst, uint64 srcva, uint64 max)
 {
-  uint64 n, va0, pa0;
-  int got_null = 0;
-
-  while(got_null == 0 && max > 0){
-    va0 = PGROUNDDOWN(srcva);
-    pa0 = walkaddr(pagetable, va0);
-    if(pa0 == 0)
-      return -1;
-    n = PGSIZE - (srcva - va0);
-    if(n > max)
-      n = max;
-
-    char *p = (char *) (pa0 + (srcva - va0));
-    while(n > 0){
-      if(*p == '\0'){
-        *dst = '\0';
-        got_null = 1;
-        break;
-      } else {
-        *dst = *p;
-      }
-      --n;
-      --max;
-      p++;
-      dst++;
-    }
-
-    srcva = va0 + PGSIZE;
-  }
-  if(got_null){
-    return 0;
-  } else {
-    return -1;
-  }
+  return copyinstr_new(pagetable, dst, srcva, max);
 }
 
 void