[MIPS] Forbid $sp update at the end of the last bundle.

src/trusted/validator_mips/validator.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 <assert.h>
 #include "native_client/src/trusted/service_runtime/nacl_config.h"
 #include "native_client/src/trusted/validator_mips/validator.h"
 #include "native_client/src/include/nacl_macros.h"
@@ skipping 337 matching lines @@
     complete_success &= ApplyPatterns(prev, inst, critical, out);
     if (!out->ShouldContinue()) return false;
 
     if (inst.IsDirectJump()) {
       branches->Add(inst.addr());
       branch_targets->Add(inst.DestAddr());
     }
 
     prev = inst;
   }
+
+  // Validate the last instruction, paired with a nop.
+  const Instruction nop(nacl_mips_dec::kNop);
+  DecodedInstruction one_past_end(segment.EndAddr(), nop, initial_decoder);

[JF, 2012/11/16 21:03:27]

Why initial_decoder here?

The ARM change does:
decode_state_.decode(nop)

[petarj, 2012/11/19 18:46:10]

Changed to nacl_mips_dec::decode(nop, decode_state_).

+  complete_success &= ApplyPatterns(prev, one_past_end, critical, out);
+
   return complete_success;
 }
 
 bool SfiValidator::ValidatePseudos(const SfiValidator &sfi,
                                    const std::vector<CodeSegment> &segments,
                                    const AddressSet &branches,
                                    const AddressSet &branch_targets,
                                    const AddressSet &critical,
                                    ProblemSink* out) {
   bool complete_success = true;
@@ skipping 133 matching lines @@
 DecodedInstruction::DecodedInstruction(uint32_t vaddr,
                                        Instruction inst,
                                        const ClassDecoder &decoder)
     : vaddr_(vaddr),
       inst_(inst),
       decoder_(&decoder),
       safety_(decoder.safety(inst_))
 {}
 
 }  // namespace