Change BKPT and UDF encodings on ARM.

src/trusted/validator_arm/actual_classes.cc

 /*
  * Copyright (c) 2012 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "native_client/src/trusted/validator_arm/actual_classes.h"
 
 #include <assert.h>
 #include <string.h>
@@ skipping 510 matching lines @@
 SafetyLevel EffectiveNoOp::safety(Instruction i) const {
   UNREFERENCED_PARAMETER(i);
   return MAY_BE_SAFE;
 }
 
 RegisterList EffectiveNoOp::defs(Instruction i) const {
   UNREFERENCED_PARAMETER(i);
   return RegisterList();
 }
 
-// Roadblock
-SafetyLevel Roadblock::safety(Instruction i) const {
-  UNREFERENCED_PARAMETER(i);
-  return MAY_BE_SAFE;
+// PermanentlyUndefined
+SafetyLevel PermanentlyUndefined::safety(Instruction i) const {
+  // Restrict UDF's encoding to values we've chosen as safe.
+  if ((i.Bits(31, 0) == kHaltFill) ||
+      (i.Bits(31, 0) == kAbortNow))
+    return MAY_BE_SAFE;
+  return FORBIDDEN_OPERANDS;
 }
 
-RegisterList Roadblock::defs(Instruction i) const {
+RegisterList PermanentlyUndefined::defs(Instruction i) const {
   UNREFERENCED_PARAMETER(i);
   return RegisterList();
 }
 
 // Breakpoint
 SafetyLevel Breakpoint::safety(Instruction i) const {
-  return i.GetCondition() == Instruction::AL
-      ? MAY_BE_SAFE
-      : UNPREDICTABLE;
+  if (i.GetCondition() != Instruction::AL)
+    return UNPREDICTABLE;
+  // Restrict BKPT's encoding to values we've chosen as safe.
+  if ((i.Bits(31, 0) == kLiteralPoolHeadInstruction) ||
+      (i.Bits(31, 0) == kBreakpoint))
+    return MAY_BE_SAFE;
+  return FORBIDDEN_OPERANDS;
+}
+
+RegisterList Breakpoint::defs(Instruction i) const {
+  UNREFERENCED_PARAMETER(i);
+  return RegisterList();
 }
 
 bool Breakpoint::is_literal_pool_head(const Instruction i) const {
   return i.Bits(31, 0) == kLiteralPoolHeadInstruction;
 }
 
 SafetyLevel PackSatRev::safety(const Instruction i) const {
   if (defs(i).Contains(Register::Pc())) {
     return FORBIDDEN_OPERANDS;
   }
@@ skipping 287 matching lines @@
   else if (width == 32) {
     // Clears everything.
     return true;
   } else {
     uint32_t bit_mask = (((1 << width) - 1) << lsbit);
     return (bit_mask & mask) == mask;
   }
 }
 
 }  // namespace nacl_arm_dec