[Syzygy Instrumenter] Add FillerTransform.

syzygy/instrument/transforms/filler_transform.cc

+// Copyright 2015 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "syzygy/instrument/transforms/filler_transform.h"
+
+#include "base/logging.h"
+#include "syzygy/assm/assembler_base.h"
+#include "syzygy/block_graph/basic_block_assembler.h"
+#include "syzygy/block_graph/basic_block_subgraph.h"
+#include "syzygy/block_graph/block_util.h"
+#include "syzygy/block_graph/transform_policy.h"
+
+namespace instrument {
+namespace transforms {
+
+const char FillerBasicBlockTransform::kTransformName[] =
+    "FillerBasicBlockTransform";
+
+const char FillerTransform::kTransformName[] = "FillerTransform";
+
+// static
+void FillerBasicBlockTransform::InjectNop(
+    const NopSpec& nop_spec,
+    bool debug_friendly,
+    BasicBlock::Instructions* instructions) {
+  BasicBlock::Instructions::iterator inst_it = instructions->begin();
+  NopSpec::const_iterator nop_it = nop_spec.begin();
+  size_t write_index = 0LL;
+  while (inst_it != instructions->end() && nop_it != nop_spec.end()) {
+    if (nop_it->first == write_index) {
+      block_graph::BasicBlockAssembler assm(inst_it, instructions);
+      // If specified, set source range for successive NOPs to to be that of the
+      // current instruction (which follows the NOPs). Caveat: This breaks the
+      // 1:1 OMAP mapping and may confuse some debuggers.
+      if (debug_friendly) {
+        assm.set_source_range(inst_it->source_range());
+        auto source_range = inst_it->source_range();

[chrisha, 2015/06/10 18:07:27]

What is this needed for?

[huangs, 2015/06/11 14:54:15]

Removed.

+      }
+      // Add all NOPs with consecutive instruction indexes.
+      while (nop_it != nop_spec.end() && nop_it->first == write_index) {
+        assm.nop(nop_it->second);
+        ++nop_it;
+        ++write_index;
+      }
+    }
+    ++inst_it;
+    ++write_index;
+  }
+}
+
+bool FillerBasicBlockTransform::TransformBasicBlockSubGraph(
+      const TransformPolicyInterface* policy,
+      BlockGraph* block_graph,
+      BasicBlockSubGraph* basic_block_subgraph) {
+  DCHECK(nullptr != policy);
+  DCHECK(nullptr != block_graph);
+  DCHECK(nullptr != basic_block_subgraph);
+
+  // Locations for code injection.
+  NopSpec nop_spec = {{1, NOP1}};

[chrisha, 2015/06/10 18:07:27]

Is this going to be sufficient? Do we maybe want to randomly generate a NopSpec
based on some input conditions? (ie: maximum number of consecutive original
instructions)

[huangs, 2015/06/11 14:54:15]

We want to start small; will do randomness later.  Also, this is injected to
every basic code block.

+
+  fprintf(stderr, "TransformBasicBlockSubGraph: %s\n",
+      debug_friendly_ ? "true" : "false");

[chrisha, 2015/06/10 18:07:27]

Debugging code?

[huangs, 2015/06/11 14:54:15]

Removed.

+
+  // Visit each basic code block and inject NOPs.
+  BasicBlockSubGraph::BBCollection& basic_blocks =
+      basic_block_subgraph->basic_blocks();
+  for (auto bb = basic_blocks.begin(); bb != basic_blocks.end(); ++bb) {
+    BasicCodeBlock* bc_block = BasicCodeBlock::Cast(*bb);
+    if (bc_block != nullptr)
+      InjectNop(nop_spec, debug_friendly_, &bc_block->instructions());
+  }
+  return true;
+}
+
+FillerTransform::FillerTransform(const std::vector<std::string>& target_list)
+    : debug_friendly_(false),
+      num_blocks_(0),
+      num_code_blocks_(0),
+      num_targets_updated_(0) {
+  // Targets are not found yet, so initialize value to false.
+  for (const std::string& target : target_list)
+    target_names_[target] = false;
+}
+
+bool FillerTransform::ShouldProcessBlock(Block* block) const {
+  return target_names_.find(block->name()) != target_names_.end();
+}
+
+void FillerTransform::CheckAllTargetFound() const {
+  bool has_missing = false;
+  for (auto it = target_names_.begin(); it != target_names_.end(); ++it) {
+    if (it->second)
+      continue;
+    if (!has_missing) {
+      LOG(WARNING) << "There are missing target(s):";
+      has_missing = true;
+    }
+    LOG(WARNING) << "  " << it->first;
+  }
+}
+
+bool FillerTransform::PreBlockGraphIteration(
+    const TransformPolicyInterface* policy,
+    BlockGraph* block_graph,
+    Block* header_block) {
+  return true;
+}
+
+bool FillerTransform::OnBlock(const TransformPolicyInterface* policy,
+                              BlockGraph* block_graph,
+                              Block* block) {
+  DCHECK(nullptr != policy);
+  DCHECK(nullptr != block_graph);
+  DCHECK(nullptr != block);
+
+  ++num_blocks_;
+  if (block->type() != BlockGraph::CODE_BLOCK)
+    return true;
+
+  ++num_code_blocks_;
+  if (!ShouldProcessBlock(block))
+    return true;
+
+  // Mark target as found.
+  std::string name(block->name());
+  auto target_it = target_names_.find(block->name());
+  if (target_it != target_names_.end())
+    target_it->second = true;
+
+  // Skip blocks that aren't eligible for basic-block decomposition.
+  if (!policy->BlockIsSafeToBasicBlockDecompose(block))
+    return true;
+
+  ++num_targets_updated_;
+  // Apply the basic block transform.
+  FillerBasicBlockTransform basic_block_transform;
+  basic_block_transform.set_debug_friendly(debug_friendly());
+  return ApplyBasicBlockSubGraphTransform(
+      &basic_block_transform, policy, block_graph, block, NULL);
+}
+
+bool FillerTransform::PostBlockGraphIteration(
+    const TransformPolicyInterface* policy,
+    BlockGraph* block_graph,
+    Block* header_block) {
+  LOG(INFO) << "Found " << num_blocks_ << " block(s).";
+  LOG(INFO) << "Found " << num_code_blocks_ << " code block(s).";
+  LOG(INFO) << "Updated " << num_targets_updated_ << " blocks(s).";
+  CheckAllTargetFound();
+  return true;
+}
+
+}  // namespace transforms
+}  // namespace instrument