Change BKPT and UDF encodings on ARM.

src/trusted/validator_arm/baseline_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/baseline_classes.h"
 
 #include <assert.h>
 #include <string.h>
@@ skipping 72 matching lines @@
   UNREFERENCED_PARAMETER(i);
   return true;
 }
 
 int32_t BranchImmediate24::branch_target_offset(Instruction i) const {
   return imm24.relative_address(i);
 }
 
 // BreakPointAndConstantPoolHead
 SafetyLevel BreakPointAndConstantPoolHead::safety(const 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) == kLiteralPoolHead) ||
+      (i.Bits(31, 0) == kBreakpoint))
+    return MAY_BE_SAFE;
+  return FORBIDDEN_OPERANDS;
 }
+
 bool BreakPointAndConstantPoolHead::
 is_literal_pool_head(const Instruction i) const {
-  return i.Bits(31, 0) == kLiteralPoolHeadInstruction;
+  return i.Bits(31, 0) == kLiteralPoolHead;
 }
 
 // BranchToRegister
 SafetyLevel BranchToRegister::safety(const Instruction i) const {
   // Extra NaCl constraint: can't branch to PC. This would branch to 8 bytes
   // after the current instruction. This instruction should be in an instruction
   // pair, the mask should therefore be to PC and fail checking, but there's
   // little harm in checking.
   if (m.reg(i).Equals(Register::Pc())) return FORBIDDEN_OPERANDS;
 
@@ skipping 1227 matching lines @@
 }
 
 // InstructionBarrier
 SafetyLevel InstructionBarrier::safety(Instruction i) const {
   if (option.value(i) != 0xF)
     return FORBIDDEN_OPERANDS;
   return UncondDecoder::safety(i);
 }
 
 }  // namespace nacl_arm_dec