From: Ben Pfaff <blp@cs.stanford.edu>
Date: Thu, 18 Nov 2004 01:14:18 +0000 (+0000)
Subject: Some initial VM tests.
X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6399b258873072cdb546dff84c37e735cda25ac7;p=pintos-anon

Some initial VM tests.
---

diff --git a/grading/vm/arc4.c b/grading/vm/arc4.c
new file mode 100644
index 0000000..cd7fd6f
--- /dev/null
+++ b/grading/vm/arc4.c
@@ -0,0 +1,53 @@
+#include <stdint.h>
+#include "arc4.h"
+
+/* Swap bytes. */
+static inline void
+swap_byte (uint8_t *a, uint8_t *b)
+{
+  uint8_t t = *a;
+  *a = *b;
+  *b = t;
+}
+
+void
+arc4_init (struct arc4 *arc4, const void *key_, size_t size)
+{
+  const uint8_t *key = key_;
+  size_t key_idx;
+  uint8_t *s;
+  int i, j;
+
+  s = arc4->s;
+  arc4->i = arc4->j = 0;
+  for (i = 0; i < 256; i++)
+    s[i] = i;
+  for (key_idx = 0, i = j = 0; i < 256; i++)
+    {
+      j = (j + s[i] + key[key_idx]) & 255;
+      swap_byte (s + i, s + j);
+      if (++key_idx >= size)
+        key_idx = 0;
+    }
+}
+
+void
+arc4_crypt (struct arc4 *arc4, void *buf_, size_t size)
+{
+  uint8_t *buf = buf_;
+  uint8_t *s;
+  uint8_t i, j;
+
+  s = arc4->s;
+  i = arc4->i;
+  j = arc4->j;
+  while (size-- > 0)
+    {
+      i += 1;
+      j += s[i];
+      swap_byte (s + i, s + j);
+      *buf++ ^= s[(s[i] + s[j]) & 255];
+    }
+  arc4->i = i;
+  arc4->j = j;
+}
diff --git a/grading/vm/arc4.h b/grading/vm/arc4.h
new file mode 100644
index 0000000..ccb260c
--- /dev/null
+++ b/grading/vm/arc4.h
@@ -0,0 +1,18 @@
+#ifndef ARC4_H
+#define ARC4_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+/* Alleged RC4 algorithm encryption state. */
+struct arc4
+  {
+    uint8_t s[256];
+    uint8_t i, j;
+  };
+
+void arc4_init (struct arc4 *, const void *, size_t);
+void arc4_crypt (struct arc4 *, void *, size_t);
+
+
+#endif /* arc4.h */
diff --git a/grading/vm/child-linear.c b/grading/vm/child-linear.c
new file mode 100644
index 0000000..1b22b49
--- /dev/null
+++ b/grading/vm/child-linear.c
@@ -0,0 +1,32 @@
+#include <stdio.h>
+#include "arc4.h"
+
+#define SIZE (128 * 1024)
+
+static char buf[SIZE];
+
+int
+main (int argc, char *argv[]) 
+{
+  const char *key = argv[argc - 1];
+  struct arc4 arc4;
+  size_t i;
+
+  /* Encrypt zeros. */
+  arc4_init (&arc4, key, strlen (key));
+  arc4_crypt (&arc4, buf, SIZE);
+
+  /* Decrypt back to zeros. */
+  arc4_init (&arc4, key, strlen (key)));
+  arc4_crypt (&arc4, buf, SIZE);
+
+  /* Check that it's all zeros. */
+  for (i = 0; i < SIZE; i++)
+    if (buf[i] != '\0')
+      {
+        printf ("(child-linear) byte %zu != 0\n", i);
+        return 1;
+      }
+
+  return 0x42;
+}
diff --git a/grading/vm/child-sort.c b/grading/vm/child-sort.c
new file mode 100644
index 0000000..5ce8da4
--- /dev/null
+++ b/grading/vm/child-sort.c
@@ -0,0 +1,50 @@
+#include <stdio.h>
+#ifdef PINTOS
+#include <syscall.h>
+#else
+#include <unistd.h>
+#include <fcntl.h>
+#endif
+
+unsigned char buf[65536];
+size_t histogram[256];
+
+int
+main (void) 
+{
+  int fd;
+  unsigned char *p;
+  size_t size;
+  size_t i;
+  
+#ifdef PINTOS
+  fd = open ("buffer");
+#else
+  fd = open ("buffer", O_RDWR);
+#endif
+  if (fd < 0) 
+    {
+      printf ("(child-sort) open() failed\n");
+      return 1;
+    }
+
+  size = read (fd, buf, sizeof buf);
+  for (i = 0; i < size; i++)
+    histogram[buf[i]]++;
+  p = buf;
+  for (i = 0; i < sizeof histogram / sizeof *histogram; i++) 
+    {
+      size_t j = histogram[i];
+      while (j-- > 0)
+        *p++ = i;
+    }
+#ifdef PINTOS
+  seek (fd, 0);
+#else
+  lseek (fd, 0, SEEK_SET);
+#endif
+  write (fd, buf, size);
+  close (fd);
+  
+  return 0x123;
+}
diff --git a/grading/vm/cksum.c b/grading/vm/cksum.c
new file mode 100644
index 0000000..1a4219c
--- /dev/null
+++ b/grading/vm/cksum.c
@@ -0,0 +1,86 @@
+/* crctab[] and cksum() are from the `cksum' entry in SUSv3. */
+
+#include "cksum.h"
+
+static unsigned long crctab[] = {
+  0x00000000,
+  0x04c11db7, 0x09823b6e, 0x0d4326d9, 0x130476dc, 0x17c56b6b,
+  0x1a864db2, 0x1e475005, 0x2608edb8, 0x22c9f00f, 0x2f8ad6d6,
+  0x2b4bcb61, 0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,
+  0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9, 0x5f15adac,
+  0x5bd4b01b, 0x569796c2, 0x52568b75, 0x6a1936c8, 0x6ed82b7f,
+  0x639b0da6, 0x675a1011, 0x791d4014, 0x7ddc5da3, 0x709f7b7a,
+  0x745e66cd, 0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,
+  0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5, 0xbe2b5b58,
+  0xbaea46ef, 0xb7a96036, 0xb3687d81, 0xad2f2d84, 0xa9ee3033,
+  0xa4ad16ea, 0xa06c0b5d, 0xd4326d90, 0xd0f37027, 0xddb056fe,
+  0xd9714b49, 0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,
+  0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1, 0xe13ef6f4,
+  0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d, 0x34867077, 0x30476dc0,
+  0x3d044b19, 0x39c556ae, 0x278206ab, 0x23431b1c, 0x2e003dc5,
+  0x2ac12072, 0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16,
+  0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca, 0x7897ab07,
+  0x7c56b6b0, 0x71159069, 0x75d48dde, 0x6b93dddb, 0x6f52c06c,
+  0x6211e6b5, 0x66d0fb02, 0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1,
+  0x53dc6066, 0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
+  0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e, 0xbfa1b04b,
+  0xbb60adfc, 0xb6238b25, 0xb2e29692, 0x8aad2b2f, 0x8e6c3698,
+  0x832f1041, 0x87ee0df6, 0x99a95df3, 0x9d684044, 0x902b669d,
+  0x94ea7b2a, 0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e,
+  0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2, 0xc6bcf05f,
+  0xc27dede8, 0xcf3ecb31, 0xcbffd686, 0xd5b88683, 0xd1799b34,
+  0xdc3abded, 0xd8fba05a, 0x690ce0ee, 0x6dcdfd59, 0x608edb80,
+  0x644fc637, 0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,
+  0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f, 0x5c007b8a,
+  0x58c1663d, 0x558240e4, 0x51435d53, 0x251d3b9e, 0x21dc2629,
+  0x2c9f00f0, 0x285e1d47, 0x36194d42, 0x32d850f5, 0x3f9b762c,
+  0x3b5a6b9b, 0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,
+  0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623, 0xf12f560e,
+  0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7, 0xe22b20d2, 0xe6ea3d65,
+  0xeba91bbc, 0xef68060b, 0xd727bbb6, 0xd3e6a601, 0xdea580d8,
+  0xda649d6f, 0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,
+  0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7, 0xae3afba2,
+  0xaafbe615, 0xa7b8c0cc, 0xa379dd7b, 0x9b3660c6, 0x9ff77d71,
+  0x92b45ba8, 0x9675461f, 0x8832161a, 0x8cf30bad, 0x81b02d74,
+  0x857130c3, 0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640,
+  0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c, 0x7b827d21,
+  0x7f436096, 0x7200464f, 0x76c15bf8, 0x68860bfd, 0x6c47164a,
+  0x61043093, 0x65c52d24, 0x119b4be9, 0x155a565e, 0x18197087,
+  0x1cd86d30, 0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
+  0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088, 0x2497d08d,
+  0x2056cd3a, 0x2d15ebe3, 0x29d4f654, 0xc5a92679, 0xc1683bce,
+  0xcc2b1d17, 0xc8ea00a0, 0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb,
+  0xdbee767c, 0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18,
+  0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4, 0x89b8fd09,
+  0x8d79e0be, 0x803ac667, 0x84fbdbd0, 0x9abc8bd5, 0x9e7d9662,
+  0x933eb0bb, 0x97ffad0c, 0xafb010b1, 0xab710d06, 0xa6322bdf,
+  0xa2f33668, 0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4
+};
+
+/* This is the algorithm used by the Posix `cksum' utility. */
+unsigned long cksum(const unsigned char *b, size_t n)
+{
+  register unsigned   i, c, s = 0;
+  for (i = n; i > 0; --i) {
+    c = (unsigned)(*b++);
+    s = (s << 8) ^ crctab[(s >> 24) ^ c];
+  }
+  while (n != 0) {
+    c = n & 0377;
+    n >>= 8;
+    s = (s << 8) ^ crctab[(s >> 24) ^ c];
+  }
+  return ~s;
+}
+
+#ifdef STANDALONE_TEST
+#include <stdio.h>
+int
+main (void) 
+{
+  char buf[65536];
+  int n = fread (buf, 1, sizeof buf, stdin);
+  printf ("%lu\n", cksum (buf, n));
+  return 0;
+}
+#endif
diff --git a/grading/vm/cksum.h b/grading/vm/cksum.h
new file mode 100644
index 0000000..79b7c42
--- /dev/null
+++ b/grading/vm/cksum.h
@@ -0,0 +1,8 @@
+#ifndef CKSUM_H
+#define CKSUM_H
+
+#include <stddef.h>
+
+unsigned long cksum(const unsigned char *b, size_t n);
+
+#endif /* cksum.h */
diff --git a/grading/vm/page-linear.c b/grading/vm/page-linear.c
new file mode 100644
index 0000000..00ffb17
--- /dev/null
+++ b/grading/vm/page-linear.c
@@ -0,0 +1,39 @@
+#include <stdio.h>
+#include "arc4.h"
+
+#define SIZE (128 * 1024)
+
+static char buf[SIZE];
+
+int
+main (void) 
+{
+  struct arc4 arc4;
+  size_t i;
+
+  printf ("(page-linear) begin\n");
+
+  /* Encrypt zeros. */
+  printf ("(page-linear) read/modify/write pass one\n");
+  arc4_init (&arc4, "foobar", 6);
+  arc4_crypt (&arc4, buf, SIZE);
+
+  /* Decrypt back to zeros. */
+  printf ("(page-linear) read/modify/write pass two\n");
+  arc4_init (&arc4, "foobar", 6);
+  arc4_crypt (&arc4, buf, SIZE);
+
+  /* Check that it's all zeros. */
+  printf ("(page-linear) read pass\n");
+  for (i = 0; i < SIZE; i++)
+    if (buf[i] != '\0')
+      {
+        printf ("(page-linear) byte %zu != 0\n", i);
+        return 1;
+      }
+
+  /* Done. */
+  printf ("(page-linear) end\n");
+
+  return 0;
+}
diff --git a/grading/vm/page-linear.exp b/grading/vm/page-linear.exp
new file mode 100644
index 0000000..291183b
--- /dev/null
+++ b/grading/vm/page-linear.exp
@@ -0,0 +1,6 @@
+(page-linear) begin
+(page-linear) read/modify/write pass one
+(page-linear) read/modify/write pass two
+(page-linear) read pass
+(page-linear) end
+page-linear: exit(0)
diff --git a/grading/vm/page-merge-seq.c b/grading/vm/page-merge-seq.c
new file mode 100644
index 0000000..3abe9e2
--- /dev/null
+++ b/grading/vm/page-merge-seq.c
@@ -0,0 +1,169 @@
+#include <stdio.h>
+#include <stdlib.h>
+#ifdef PINTOS
+#include <syscall.h>
+#else
+#include <unistd.h>
+#include <fcntl.h>
+#endif
+#include "arc4.h"
+
+#define CHUNK_SIZE (63 * 1024)                  /* Max file size. */
+#define CHUNK_CNT 16                            /* Number of chunks. */
+#define DATA_SIZE (CHUNK_CNT * CHUNK_SIZE)      /* Buffer size. */
+
+unsigned char buf1[DATA_SIZE], buf2[DATA_SIZE];
+size_t histogram[256];
+
+/* Initialize buf1 with random data,
+   then count the number of instances of each value within it. */
+static void
+init (void) 
+{
+  struct arc4 arc4;
+  size_t i;
+
+  printf ("page-merge-seq) init\n");
+
+  arc4_init (&arc4, "foobar", 6);
+  arc4_crypt (&arc4, buf1, sizeof buf1);
+  for (i = 0; i < sizeof buf1; i++)
+    histogram[buf1[i]]++;
+}
+
+/* Sort each chunk of buf1 using a subprocess. */
+static void
+sort (void)
+{
+  size_t i;
+
+#ifdef PINTOS
+  create ("buffer", CHUNK_SIZE);
+#endif
+  for (i = 0; i < CHUNK_CNT; i++) 
+    {
+      int fd;
+
+      printf ("(page-merge-seq) sort chunk %zu\n", i);
+
+      /* Write this chunk to a file. */
+#ifdef PINTOS
+      fd = open ("buffer");
+#else
+      fd = open ("buffer", O_WRONLY | O_CREAT, 0660);
+#endif
+      if (fd < 0) 
+        {
+          printf ("(page-merge-seq) open() failed\n");
+          exit (1);
+        }
+      write (fd, buf1 + CHUNK_SIZE * i, CHUNK_SIZE);
+      close (fd);
+
+      /* Sort with subprocess. */
+#ifdef PINTOS
+      pid_t child = exec ("child-sort");
+      if (child == -1) 
+        {
+          printf ("(page-merge-seq) exec() failed\n");
+          exit (1);
+        }
+      if (join (child) != 0x123) 
+        {
+          printf ("(page-merge-seq) join(exec()) returned bad value\n");
+          exit (1);
+        }
+#else
+      system ("./child-sort");
+#endif
+
+      /* Read chunk back from file. */
+#ifdef PINTOS
+      fd = open ("buffer");
+#else
+      fd = open ("buffer", O_RDONLY);
+#endif
+      if (fd < 0) 
+        {
+          printf ("(page-merge-seq) open() failed\n");
+          exit (1);
+        }
+      read (fd, buf1 + CHUNK_SIZE * i, CHUNK_SIZE);
+      close (fd);
+    }
+}
+
+/* Merge the sorted chunks in buf1 into a fully sorted buf2. */
+static void
+merge (void) 
+{
+  unsigned char *mp[CHUNK_CNT];
+  size_t mp_left;
+  unsigned char *op;
+  size_t i;
+
+  printf ("(page-merge-seq) merge\n");
+
+  /* Initialize merge pointers. */
+  mp_left = CHUNK_CNT;
+  for (i = 0; i < CHUNK_CNT; i++)
+    mp[i] = buf1 + CHUNK_SIZE * i;
+
+  /* Merge. */
+  op = buf2;
+  while (mp_left > 0) 
+    {
+      /* Find smallest value. */
+      size_t min = 0;
+      for (i = 1; i < mp_left; i++)
+        if (*mp[i] < *mp[min])
+          min = i;
+
+      /* Append value to buf2. */
+      *op++ = *mp[min];
+
+      /* Advance merge pointer.
+         Delete this chunk from the set if it's emptied. */
+      if ((++mp[min] - buf1) % CHUNK_SIZE == 0) 
+        mp[min] = mp[--mp_left];
+    }
+}
+
+static void
+verify (void) 
+{
+  size_t buf_idx;
+  size_t hist_idx;
+
+  printf ("(page-merge-seq) verify\n");
+
+  buf_idx = 0;
+  for (hist_idx = 0; hist_idx < sizeof histogram / sizeof *histogram;
+       hist_idx++)
+    {
+      while (histogram[hist_idx]-- > 0) 
+        {
+          if (buf2[buf_idx] != hist_idx)
+            {
+              printf ("(page-merge-seq) bad value %d in byte %zu\n",
+                      buf2[buf_idx], buf_idx);
+              exit (1);
+            }
+          buf_idx++;
+        } 
+    }
+
+  printf ("(page-merge-seq) success, buf_idx=%zu\n", buf_idx);
+}
+
+int
+main (void) 
+{
+  printf ("(page-merge-seq) begin\n");
+  init ();
+  sort ();
+  merge ();
+  verify ();
+  printf ("(page-merge-seq) end\n");
+  return 0;
+}
diff --git a/grading/vm/page-parallel.c b/grading/vm/page-parallel.c
new file mode 100644
index 0000000..c2d8eb3
--- /dev/null
+++ b/grading/vm/page-parallel.c
@@ -0,0 +1,34 @@
+#include <syscall.h>
+
+#define CHILD_CNT 3
+
+int
+main (void) 
+{
+  pid_t children[CHILD_CNT];
+  int i;
+
+  printf ("(page-parallel) begin\n");
+  for (i = 0; i < CHILD_CNT; i++) 
+    {
+      printf ("(page-parallel) start child %d\n", i);
+      children[i] = exec ("child-linear");
+      if (children[i] == -1) 
+        {
+          printf ("(page-parallel) exec() returned pid -1\n", children[i]);
+          return 1;
+        }
+    }
+
+  for (i = 0; i < CHILD_CNT; i++) 
+    {
+      int code;
+      printf ("(page-parallel) join child %d\n", i);
+      code = join (children[i]);
+      if (code != 0x42)
+        printf ("(page-parallel) child %d returned bad exit code\n", i);
+    }
+  printf ("(page-parallel) end\n");
+
+  return 0;
+}
diff --git a/grading/vm/page-parallel.exp b/grading/vm/page-parallel.exp
new file mode 100644
index 0000000..bc914e6
--- /dev/null
+++ b/grading/vm/page-parallel.exp
@@ -0,0 +1,9 @@
+(page-parallel) begin
+(page-parallel) start child 0
+(page-parallel) start child 1
+(page-parallel) start child 2
+(page-parallel) join child 0
+(page-parallel) join child 1
+(page-parallel) join child 2
+(page-parallel) end
+page-parallel: exit(0)
diff --git a/grading/vm/pt-bad-addr.c b/grading/vm/pt-bad-addr.c
new file mode 100644
index 0000000..6d66587
--- /dev/null
+++ b/grading/vm/pt-bad-addr.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+
+int
+main (void) 
+{
+  printf ("(pt-bad-addr) begin\n");
+  printf ("(pt-bad-addr) addr=%d\n", *(int *) 0x04000000);
+  printf ("(pt-bad-addr) end\n");
+  return 0;
+}
diff --git a/grading/vm/pt-bad-addr.exp b/grading/vm/pt-bad-addr.exp
new file mode 100644
index 0000000..ac1492d
--- /dev/null
+++ b/grading/vm/pt-bad-addr.exp
@@ -0,0 +1,2 @@
+(pt-bad-addr) begin
+pt-bad-addr: exit(-1)
diff --git a/grading/vm/pt-big-stk-obj.c b/grading/vm/pt-big-stk-obj.c
new file mode 100644
index 0000000..70f5d79
--- /dev/null
+++ b/grading/vm/pt-big-stk-obj.c
@@ -0,0 +1,19 @@
+#include <stdio.h>
+#include <string.h>
+#include "arc4.h"
+#include "cksum.h"
+
+int
+main (void) 
+{
+  char stk_obj[65536];
+  struct arc4 arc4;
+
+  printf ("(pt-big-stk-obj) begin\n");
+  arc4_init (&arc4, "foobar", 6);
+  memset (stk_obj, 0, sizeof stk_obj);
+  arc4_crypt (&arc4, stk_obj, sizeof stk_obj);
+  printf ("(pt-big-stk-obj) cksum: %lu\n", cksum (stk_obj, sizeof stk_obj));
+  printf ("(pt-big-stk-obj) end\n");
+  return 0;
+}
diff --git a/grading/vm/pt-big-stk-obj.exp b/grading/vm/pt-big-stk-obj.exp
new file mode 100644
index 0000000..0919025
--- /dev/null
+++ b/grading/vm/pt-big-stk-obj.exp
@@ -0,0 +1,4 @@
+(pt-big-stk-obj) begin
+(pt-big-stk-obj) cksum: 3256410166
+(pt-big-stk-obj) end
+pt-big-stk-obj: exit(0)
diff --git a/grading/vm/pt-grow-stack.c b/grading/vm/pt-grow-stack.c
new file mode 100644
index 0000000..805db98
--- /dev/null
+++ b/grading/vm/pt-grow-stack.c
@@ -0,0 +1,19 @@
+#include <stdio.h>
+#include <string.h>
+#include "arc4.h"
+#include "cksum.h"
+
+int
+main (void) 
+{
+  char stack_obj[4096];
+  struct arc4 arc4;
+
+  printf ("(pt-grow-stack) begin\n");
+  arc4_init (&arc4, "foobar", 6);
+  memset (stack_obj, 0, sizeof stack_obj);
+  arc4_crypt (&arc4, stack_obj, sizeof stack_obj);
+  printf ("(pt-grow-stack) cksum: %lu\n", cksum (stack_obj, sizeof stack_obj));
+  printf ("(pt-grow-stack) end\n");
+  return 0;
+}
diff --git a/grading/vm/pt-grow-stack.exp b/grading/vm/pt-grow-stack.exp
new file mode 100644
index 0000000..2caafcf
--- /dev/null
+++ b/grading/vm/pt-grow-stack.exp
@@ -0,0 +1,4 @@
+(pt-grow-stack) begin
+(pt-grow-stack) cksum: 3424492700
+(pt-grow-stack) end
+pt-grow-stack: exit(0)
diff --git a/grading/vm/pt-write-code.c b/grading/vm/pt-write-code.c
new file mode 100644
index 0000000..6954ddf
--- /dev/null
+++ b/grading/vm/pt-write-code.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+
+int
+main (void) 
+{
+  printf ("(pt-write-code) begin\n");
+  *(int *) main = 0;
+  printf ("(pt-write-code) end\n");
+  return 0;
+}
diff --git a/grading/vm/pt-write-code.exp b/grading/vm/pt-write-code.exp
new file mode 100644
index 0000000..5844146
--- /dev/null
+++ b/grading/vm/pt-write-code.exp
@@ -0,0 +1,2 @@
+(pt-write-code) begin
+pt-write-code: exit(-1)
diff --git a/grading/vm/tests.txt b/grading/vm/tests.txt
new file mode 100644
index 0000000..8839084
--- /dev/null
+++ b/grading/vm/tests.txt
@@ -0,0 +1,29 @@
+CORRECTNESS [[total]]
+---------------------
+
+Page table management
+  -4 pt-grow-stack: stack should be able to grow beyond one page
+  -1 pt-big-stk-obj: stack should be able to handle large objects
+  -3 pt-bad-addr: accesses to invalid virtual memory should fault
+  -1 pt-write-code: should not be able to write to the code segment
+Score: /9
+
+Paging
+  -4 page-linear: sequentially read/modify/write memory twice then read it back
+  -2 page-parallel: write then read lots of memory--3 processes at once
+  -2 page-merge-seq: sequential merge sort of large data set
+  -1 page-merge-par: parallel merge sort of large data set
+  -3 page-shuffle: shuffle content of large static buffer
+Score: /12
+
+Memory mapping
+  -4 mmap-read: use mmap to read a file, munmap
+  -1 mmap-close: use mmap, close file, read from mapping, munmap
+  -1 mmap-unmap: after munmap virtual memory area should be invalid
+  -1 mmap-overlap: try to mmap files in overlapping virtual memory areas
+  -2 mmap-twice: mmap'ing same file twice should work
+  -4 mmap-write: after mmap-modify-munmap a read should reflect changes
+  -4 mmap-exit: after mmap-modify-exit a read should reflect changes
+  -2 mmap-shuffle: shuffle content of mapped file
+Score: /19
+