A mechanism to identify/forbid/"rewrite" non-temporal instructions (and other)

src/trusted/validator/driver/ncval.cc

Index: src/trusted/validator/driver/ncval.cc
diff --git a/src/trusted/validator/driver/ncval.cc b/src/trusted/validator/driver/ncval.cc
index c9736e6e33c8ad34911e75784135472c689325e0..906aef6d3b216a380d2b50cd48f4ffc0c7bd0f98 100644
--- a/src/trusted/validator/driver/ncval.cc
+++ b/src/trusted/validator/driver/ncval.cc
@@ -55,14 +55,17 @@ struct UserData {
   vector<Error> *errors;
   vector<Jump> *jumps;
   set<uint32_t> *bad_jump_targets;
+  bool pnacl_mode;
   UserData(Segment segment,
            vector<Error> *errors,
            vector<Jump> *jumps,
-           set<uint32_t> *bad_jump_targets)
+           set<uint32_t> *bad_jump_targets,
+           bool pnacl_mode)
       : segment(segment),
         errors(errors),
         jumps(jumps),
-        bad_jump_targets(bad_jump_targets) {
+        bad_jump_targets(bad_jump_targets),
+        pnacl_mode(pnacl_mode) {
   }
 };
 
@@ -94,6 +97,11 @@ Bool ProcessInstruction(
     }
   }
 
+  // For non-pnacl-mode, 'unsupported instruction' should pass validation,
+  // and we simply clear the flag.
+  if (!user_data.pnacl_mode)
+    validation_info &= ~UNSUPPORTED_INSTRUCTION;
+
   Bool result = (validation_info & (VALIDATION_ERRORS_MASK | BAD_JUMP_TARGET))
                 ? FALSE
                 : TRUE;
@@ -120,6 +128,11 @@ Bool ProcessInstruction(
     errors.push_back(Error(offset, "required CPU feature not found"));
   }
 
+  if (validation_info & UNSUPPORTED_INSTRUCTION) {
+    validation_info &= ~UNSUPPORTED_INSTRUCTION;
+    errors.push_back(Error(offset, "unsupported instruction"));
+  }
+
   if (validation_info & FORBIDDEN_BASE_REGISTER) {
     validation_info &= ~FORBIDDEN_BASE_REGISTER;
     errors.push_back(Error(offset, "improper memory address - bad base"));
@@ -192,9 +205,18 @@ Bool ProcessError(
     uint32_t validation_info, void *user_data_ptr) {
   UNREFERENCED_PARAMETER(begin);
   UNREFERENCED_PARAMETER(end);
-  UNREFERENCED_PARAMETER(validation_info);
-  UNREFERENCED_PARAMETER(user_data_ptr);
-  return FALSE;
+  UserData &user_data = *reinterpret_cast<UserData *>(user_data_ptr);
+
+  // We do the same thing as in ProcessInstruction(): for non-pnacl-mode,
+  // 'unsupported instruction' should pass validation, and we simply clear
+  // the flag.
+  if (!user_data.pnacl_mode)
+    validation_info &= ~UNSUPPORTED_INSTRUCTION;
+
+  Bool result = (validation_info & (VALIDATION_ERRORS_MASK | BAD_JUMP_TARGET))

[gdeepti, 2015/07/28 03:08:58]

Why BAD_JUMP_TARGET here? 

[ruiq, 2015/07/28 04:58:55]

This is to be consistent with the handling in ProcessInstruction(), line 105.

+                ? FALSE
+                : TRUE;
+  return result;
 }
 
 
@@ -209,7 +231,8 @@ typedef Bool ValidateChunkFunc(
 bool ValidateX86(
     const Segment &segment,
     ValidateChunkFunc validate_chunk,
-    vector<Error> *errors) {
+    vector<Error> *errors,
+    bool pnacl_mode) {
 
   errors->clear();
 
@@ -233,7 +256,7 @@ bool ValidateX86(
   vector<Jump> jumps;
   set<uint32_t> bad_jump_targets;
 
-  UserData user_data(segment, errors, &jumps, &bad_jump_targets);
+  UserData user_data(segment, errors, &jumps, &bad_jump_targets, pnacl_mode);
 
   // TODO(shcherbina): customize from command line
 
@@ -258,7 +281,7 @@ bool ValidateX86(
   CHECK(result == validate_chunk(
       segment.data, segment.size,
       0, &kFullCPUIDFeatures,
-      ProcessError, NULL));
+      ProcessError, &user_data));
 
   return static_cast<bool>(result);
 }
@@ -324,9 +347,10 @@ void Usage() {
 
 
 struct Options {
-  Options() : input_file(NULL), verbose(false) {}
+  Options() : input_file(NULL), verbose(false), pnacl_mode(false) {}
   const char *input_file;
   bool verbose;
+  bool pnacl_mode;

[Petr Hosek, 2015/07/28 19:05:46]

Rename to `flags`.

[ruiq, 2015/07/28 21:34:55]

Done.

 };
 
 
@@ -337,6 +361,9 @@ void ParseOptions(int argc, char **argv, Options *options) {
       case 'v':
         options->verbose = true;
         break;
+      case 'p':
+        options->pnacl_mode = true;

[Petr Hosek, 2015/07/28 19:05:46]

The 'p' option seems to be missing from the optstring.

[ruiq, 2015/07/28 21:34:55]

Done.

+        break;
       default:
         fprintf(stderr, "ERROR: unknown option: [%c]\n\n", opt);
         Usage();
@@ -368,10 +395,12 @@ int main(int argc, char **argv) {
   bool result = false;
   switch (architecture) {
     case elf_load::X86_32:
-      result = ValidateX86(segment, ValidateChunkIA32, &errors);
+      result = ValidateX86(segment, ValidateChunkIA32, &errors,
+                           options.pnacl_mode);
       break;
     case elf_load::X86_64:
-      result = ValidateX86(segment, ValidateChunkAMD64, &errors);
+      result = ValidateX86(segment, ValidateChunkAMD64, &errors,
+                           options.pnacl_mode);
       break;
     case elf_load::ARM:
       result = ValidateArm(segment, &errors);