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- // Copyright 2017 The Chromium 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 "components/zucchini/zucchini_gen.h"
- #include <stddef.h>
- #include <stdint.h>
- #include <algorithm>
- #include <map>
- #include <memory>
- #include <string>
- #include <utility>
- #include "base/logging.h"
- #include "base/numerics/safe_conversions.h"
- #include "components/zucchini/disassembler.h"
- #include "components/zucchini/element_detection.h"
- #include "components/zucchini/encoded_view.h"
- #include "components/zucchini/ensemble_matcher.h"
- #include "components/zucchini/equivalence_map.h"
- #include "components/zucchini/heuristic_ensemble_matcher.h"
- #include "components/zucchini/image_index.h"
- #include "components/zucchini/imposed_ensemble_matcher.h"
- #include "components/zucchini/patch_writer.h"
- #include "components/zucchini/suffix_array.h"
- #include "components/zucchini/targets_affinity.h"
- namespace zucchini {
- namespace {
- // Parameters for patch generation.
- constexpr double kMinEquivalenceSimilarity = 12.0;
- constexpr double kMinLabelAffinity = 64.0;
- } // namespace
- std::vector<offset_t> FindExtraTargets(const TargetPool& projected_old_targets,
- const TargetPool& new_targets) {
- std::vector<offset_t> extra_targets;
- std::set_difference(
- new_targets.begin(), new_targets.end(), projected_old_targets.begin(),
- projected_old_targets.end(), std::back_inserter(extra_targets));
- return extra_targets;
- }
- // Label matching (between "old" and "new") can guide EquivalenceMap
- // construction; but EquivalenceMap induces Label matching. This apparent "chick
- // and egg" problem is solved by alternating 2 steps |num_iterations| times:
- // - Associate targets based on previous EquivalenceMap. Note on the first
- // iteration, EquivalenceMap is empty, resulting in a no-op.
- // - Construct refined EquivalenceMap based on new targets associations.
- EquivalenceMap CreateEquivalenceMap(const ImageIndex& old_image_index,
- const ImageIndex& new_image_index,
- int num_iterations) {
- size_t pool_count = old_image_index.PoolCount();
- // |target_affinities| is outside the loop to reduce allocation.
- std::vector<TargetsAffinity> target_affinities(pool_count);
- EquivalenceMap equivalence_map;
- for (int i = 0; i < num_iterations; ++i) {
- EncodedView old_view(old_image_index);
- EncodedView new_view(new_image_index);
- // Associate targets from "old" to "new" image based on |equivalence_map|
- // for each reference pool.
- for (const auto& old_pool_tag_and_targets :
- old_image_index.target_pools()) {
- PoolTag pool_tag = old_pool_tag_and_targets.first;
- target_affinities[pool_tag.value()].InferFromSimilarities(
- equivalence_map, old_pool_tag_and_targets.second.targets(),
- new_image_index.pool(pool_tag).targets());
- // Creates labels for strongly associated targets.
- std::vector<uint32_t> old_labels;
- std::vector<uint32_t> new_labels;
- size_t label_bound = target_affinities[pool_tag.value()].AssignLabels(
- kMinLabelAffinity, &old_labels, &new_labels);
- old_view.SetLabels(pool_tag, std::move(old_labels), label_bound);
- new_view.SetLabels(pool_tag, std::move(new_labels), label_bound);
- }
- // Build equivalence map, where references in "old" and "new" that share
- // common semantics (i.e., their respective targets were associated earlier
- // on) are considered equivalent.
- equivalence_map.Build(
- MakeSuffixArray<InducedSuffixSort>(old_view, old_view.Cardinality()),
- old_view, new_view, target_affinities, kMinEquivalenceSimilarity);
- }
- return equivalence_map;
- }
- bool GenerateEquivalencesAndExtraData(ConstBufferView new_image,
- const EquivalenceMap& equivalence_map,
- PatchElementWriter* patch_writer) {
- // Make 2 passes through |equivalence_map| to reduce write churn.
- // Pass 1: Write all equivalences.
- EquivalenceSink equivalences_sink;
- for (const EquivalenceCandidate& candidate : equivalence_map)
- equivalences_sink.PutNext(candidate.eq);
- patch_writer->SetEquivalenceSink(std::move(equivalences_sink));
- // Pass 2: Write data in gaps in |new_image| before / between after
- // |equivalence_map| as "extra data".
- ExtraDataSink extra_data_sink;
- offset_t dst_offset = 0;
- for (const EquivalenceCandidate& candidate : equivalence_map) {
- extra_data_sink.PutNext(
- new_image[{dst_offset, candidate.eq.dst_offset - dst_offset}]);
- dst_offset = candidate.eq.dst_end();
- DCHECK_LE(dst_offset, new_image.size());
- }
- extra_data_sink.PutNext(
- new_image[{dst_offset, new_image.size() - dst_offset}]);
- patch_writer->SetExtraDataSink(std::move(extra_data_sink));
- return true;
- }
- bool GenerateRawDelta(
- ConstBufferView old_image,
- ConstBufferView new_image,
- const EquivalenceMap& equivalence_map,
- const ImageIndex& new_image_index,
- const std::map<TypeTag, std::unique_ptr<ReferenceMixer>>& reference_mixers,
- PatchElementWriter* patch_writer) {
- RawDeltaSink raw_delta_sink;
- // Visit |equivalence_map| blocks in |new_image| order. Find and emit all
- // bytewise differences.
- offset_t base_copy_offset = 0;
- for (const EquivalenceCandidate& candidate : equivalence_map) {
- Equivalence equivalence = candidate.eq;
- // For each bytewise delta from |old_image| to |new_image|, compute "copy
- // offset" and pass it along with delta to the sink.
- for (offset_t i = 0; i < equivalence.length;) {
- if (new_image_index.IsReference(equivalence.dst_offset + i)) {
- DCHECK(new_image_index.IsToken(equivalence.dst_offset + i));
- TypeTag type_tag =
- new_image_index.LookupType(equivalence.dst_offset + i);
- ReferenceMixer* mixer = reference_mixers.at(type_tag).get();
- offset_t width = new_image_index.refs(type_tag).width();
- // Reference delta has its own flow. On some architectures (e.g., x86)
- // this does not involve raw delta, so we skip. On other architectures
- // (e.g., ARM) references are mixed with other bits that may change, so
- // we need to "mix" data and store some changed bits into raw delta.
- if (mixer) {
- ConstBufferView mixed_reference = mixer->Mix(
- equivalence.src_offset + i, equivalence.dst_offset + i);
- for (offset_t j = 0; j < width; ++j) {
- int8_t diff =
- mixed_reference[j] - old_image[equivalence.src_offset + i + j];
- if (diff != 0)
- raw_delta_sink.PutNext({base_copy_offset + i + j, diff});
- }
- }
- i += width;
- DCHECK_LE(i, equivalence.length);
- } else {
- int8_t diff = new_image[equivalence.dst_offset + i] -
- old_image[equivalence.src_offset + i];
- if (diff)
- raw_delta_sink.PutNext({base_copy_offset + i, diff});
- ++i;
- }
- }
- base_copy_offset += equivalence.length;
- }
- patch_writer->SetRawDeltaSink(std::move(raw_delta_sink));
- return true;
- }
- bool GenerateReferencesDelta(const ReferenceSet& src_refs,
- const ReferenceSet& dst_refs,
- const TargetPool& projected_target_pool,
- const OffsetMapper& offset_mapper,
- const EquivalenceMap& equivalence_map,
- ReferenceDeltaSink* reference_delta_sink) {
- size_t ref_width = src_refs.width();
- auto dst_ref = dst_refs.begin();
- // For each equivalence, for each covered |dst_ref| and the matching
- // |src_ref|, emit the delta between the respective target labels. Note: By
- // construction, each reference location (with |ref_width|) lies either
- // completely inside an equivalence or completely outside. We perform
- // "straddle checks" throughout to verify this assertion.
- for (const auto& candidate : equivalence_map) {
- const Equivalence equiv = candidate.eq;
- // Increment |dst_ref| until it catches up to |equiv|.
- while (dst_ref != dst_refs.end() && dst_ref->location < equiv.dst_offset)
- ++dst_ref;
- if (dst_ref == dst_refs.end())
- break;
- if (dst_ref->location >= equiv.dst_end())
- continue;
- // Straddle check.
- DCHECK_LE(dst_ref->location + ref_width, equiv.dst_end());
- offset_t src_loc =
- equiv.src_offset + (dst_ref->location - equiv.dst_offset);
- auto src_ref = std::lower_bound(
- src_refs.begin(), src_refs.end(), src_loc,
- [](const Reference& a, offset_t b) { return a.location < b; });
- for (; dst_ref != dst_refs.end() &&
- dst_ref->location + ref_width <= equiv.dst_end();
- ++dst_ref, ++src_ref) {
- // Local offset of |src_ref| should match that of |dst_ref|.
- DCHECK_EQ(src_ref->location - equiv.src_offset,
- dst_ref->location - equiv.dst_offset);
- offset_t old_offset = src_ref->target;
- offset_t new_estimated_offset =
- offset_mapper.ExtendedForwardProject(old_offset);
- offset_t new_estimated_key =
- projected_target_pool.KeyForNearestOffset(new_estimated_offset);
- offset_t new_offset = dst_ref->target;
- offset_t new_key = projected_target_pool.KeyForOffset(new_offset);
- reference_delta_sink->PutNext(
- static_cast<int32_t>(new_key - new_estimated_key));
- }
- if (dst_ref == dst_refs.end())
- break; // Done.
- // Straddle check.
- DCHECK_GE(dst_ref->location, equiv.dst_end());
- }
- return true;
- }
- bool GenerateExtraTargets(const std::vector<offset_t>& extra_targets,
- PoolTag pool_tag,
- PatchElementWriter* patch_writer) {
- TargetSink target_sink;
- for (offset_t target : extra_targets)
- target_sink.PutNext(target);
- patch_writer->SetTargetSink(pool_tag, std::move(target_sink));
- return true;
- }
- bool GenerateRawElement(const std::vector<offset_t>& old_sa,
- ConstBufferView old_image,
- ConstBufferView new_image,
- PatchElementWriter* patch_writer) {
- ImageIndex old_image_index(old_image);
- ImageIndex new_image_index(new_image);
- EquivalenceMap equivalences;
- equivalences.Build(old_sa, EncodedView(old_image_index),
- EncodedView(new_image_index), {},
- kMinEquivalenceSimilarity);
- patch_writer->SetReferenceDeltaSink({});
- std::map<TypeTag, std::unique_ptr<ReferenceMixer>> reference_mixers;
- return GenerateEquivalencesAndExtraData(new_image, equivalences,
- patch_writer) &&
- GenerateRawDelta(old_image, new_image, equivalences, new_image_index,
- reference_mixers, patch_writer);
- }
- bool GenerateExecutableElement(ExecutableType exe_type,
- ConstBufferView old_image,
- ConstBufferView new_image,
- PatchElementWriter* patch_writer) {
- // Initialize Disassemblers.
- std::unique_ptr<Disassembler> old_disasm =
- MakeDisassemblerOfType(old_image, exe_type);
- std::unique_ptr<Disassembler> new_disasm =
- MakeDisassemblerOfType(new_image, exe_type);
- if (!old_disasm || !new_disasm) {
- LOG(ERROR) << "Failed to create Disassembler.";
- return false;
- }
- DCHECK_EQ(old_disasm->GetExeType(), new_disasm->GetExeType());
- // Initialize ImageIndexes.
- ImageIndex old_image_index(old_image);
- ImageIndex new_image_index(new_image);
- if (!old_image_index.Initialize(old_disasm.get()) ||
- !new_image_index.Initialize(new_disasm.get())) {
- LOG(ERROR) << "Failed to create ImageIndex: Overlapping references found?";
- return false;
- }
- DCHECK_EQ(old_image_index.PoolCount(), new_image_index.PoolCount());
- EquivalenceMap equivalences =
- CreateEquivalenceMap(old_image_index, new_image_index,
- new_disasm->num_equivalence_iterations());
- OffsetMapper offset_mapper(equivalences,
- base::checked_cast<offset_t>(old_image.size()),
- base::checked_cast<offset_t>(new_image.size()));
- ReferenceDeltaSink reference_delta_sink;
- for (const auto& old_targets : old_image_index.target_pools()) {
- PoolTag pool_tag = old_targets.first;
- TargetPool projected_old_targets = old_targets.second;
- projected_old_targets.FilterAndProject(offset_mapper);
- std::vector<offset_t> extra_target =
- FindExtraTargets(projected_old_targets, new_image_index.pool(pool_tag));
- projected_old_targets.InsertTargets(extra_target);
- if (!GenerateExtraTargets(extra_target, pool_tag, patch_writer))
- return false;
- for (TypeTag type_tag : old_targets.second.types()) {
- if (!GenerateReferencesDelta(old_image_index.refs(type_tag),
- new_image_index.refs(type_tag),
- projected_old_targets, offset_mapper,
- equivalences, &reference_delta_sink)) {
- return false;
- }
- }
- }
- std::map<TypeTag, std::unique_ptr<ReferenceMixer>> reference_mixers;
- std::vector<ReferenceGroup> ref_groups = old_disasm->MakeReferenceGroups();
- for (const auto& group : ref_groups) {
- auto result = reference_mixers.emplace(
- group.type_tag(),
- group.GetMixer(old_image, new_image, old_disasm.get()));
- DCHECK(result.second);
- }
- patch_writer->SetReferenceDeltaSink(std::move(reference_delta_sink));
- return GenerateEquivalencesAndExtraData(new_image, equivalences,
- patch_writer) &&
- GenerateRawDelta(old_image, new_image, equivalences, new_image_index,
- reference_mixers, patch_writer);
- }
- status::Code GenerateBufferCommon(ConstBufferView old_image,
- ConstBufferView new_image,
- std::unique_ptr<EnsembleMatcher> matcher,
- EnsemblePatchWriter* patch_writer) {
- if (!matcher->RunMatch(old_image, new_image)) {
- LOG(INFO) << "RunMatch() failed, generating raw patch.";
- return GenerateBufferRaw(old_image, new_image, patch_writer);
- }
- const std::vector<ElementMatch>& matches = matcher->matches();
- LOG(INFO) << "Matching: Found " << matches.size()
- << " nontrivial matches and " << matcher->num_identical()
- << " identical matches.";
- size_t num_elements = matches.size();
- if (num_elements == 0) {
- LOG(INFO) << "No nontrival matches, generating raw patch.";
- return GenerateBufferRaw(old_image, new_image, patch_writer);
- }
- // "Gaps" are |new_image| bytes not covered by new_elements in |matches|.
- // These are treated as raw data, and patched against the entire |old_image|.
- // |patch_element_map| (keyed by "new" offsets) stores PatchElementWriter
- // results so elements and "gap" results can be computed separately (to reduce
- // peak memory usage), and later, properly serialized to |patch_writer|
- // ordered by "new" offset.
- std::map<offset_t, PatchElementWriter> patch_element_map;
- // Variables to track element patching successes.
- std::vector<BufferRegion> covered_new_regions;
- size_t covered_new_bytes = 0;
- // Process elements first, since non-fatal failures may turn some into gaps.
- for (const ElementMatch& match : matches) {
- BufferRegion new_region = match.new_element.region();
- LOG(INFO) << "--- Match [" << new_region.lo() << "," << new_region.hi()
- << ")";
- auto it_and_success = patch_element_map.emplace(
- base::checked_cast<offset_t>(new_region.lo()), match);
- DCHECK(it_and_success.second);
- PatchElementWriter& patch_element = it_and_success.first->second;
- ConstBufferView old_sub_image = old_image[match.old_element.region()];
- ConstBufferView new_sub_image = new_image[new_region];
- if (GenerateExecutableElement(match.exe_type(), old_sub_image,
- new_sub_image, &patch_element)) {
- covered_new_regions.push_back(new_region);
- covered_new_bytes += new_region.size;
- } else {
- LOG(INFO) << "Fall back to raw patching.";
- patch_element_map.erase(it_and_success.first);
- }
- }
- if (covered_new_bytes < new_image.size()) {
- // Process all "gaps", which are patched against the entire "old" image. To
- // compute equivalence maps, "gaps" share a common suffix array
- // |old_sa_raw|, whose lifetime is kept separated from elements' suffix
- // arrays to reduce peak memory.
- Element entire_old_element(old_image.local_region(), kExeTypeNoOp);
- ImageIndex old_image_index(old_image);
- EncodedView old_view_raw(old_image_index);
- std::vector<offset_t> old_sa_raw =
- MakeSuffixArray<InducedSuffixSort>(old_view_raw, size_t(256));
- offset_t gap_lo = 0;
- // Add sentinel that points to end of "new" file, to simplify gap iteration.
- covered_new_regions.emplace_back(BufferRegion{new_image.size(), 0});
- for (const BufferRegion& covered : covered_new_regions) {
- offset_t gap_hi = base::checked_cast<offset_t>(covered.lo());
- DCHECK_GE(gap_hi, gap_lo);
- offset_t gap_size = gap_hi - gap_lo;
- if (gap_size > 0) {
- LOG(INFO) << "--- Gap [" << gap_lo << "," << gap_hi << ")";
- ElementMatch gap_match{{entire_old_element, kExeTypeNoOp},
- {{gap_lo, gap_size}, kExeTypeNoOp}};
- auto it_and_success = patch_element_map.emplace(gap_lo, gap_match);
- DCHECK(it_and_success.second);
- PatchElementWriter& patch_element = it_and_success.first->second;
- ConstBufferView new_sub_image = new_image[{gap_lo, gap_size}];
- if (!GenerateRawElement(old_sa_raw, old_image, new_sub_image,
- &patch_element)) {
- return status::kStatusFatal;
- }
- }
- gap_lo = base::checked_cast<offset_t>(covered.hi());
- }
- }
- // Write all PatchElementWriter sorted by "new" offset.
- for (auto& new_lo_and_patch_element : patch_element_map)
- patch_writer->AddElement(std::move(new_lo_and_patch_element.second));
- return status::kStatusSuccess;
- }
- /******** Exported Functions ********/
- status::Code GenerateBuffer(ConstBufferView old_image,
- ConstBufferView new_image,
- EnsemblePatchWriter* patch_writer) {
- return GenerateBufferCommon(
- old_image, new_image, std::make_unique<HeuristicEnsembleMatcher>(nullptr),
- patch_writer);
- }
- status::Code GenerateBufferImposed(ConstBufferView old_image,
- ConstBufferView new_image,
- std::string imposed_matches,
- EnsemblePatchWriter* patch_writer) {
- if (imposed_matches.empty())
- return GenerateBuffer(old_image, new_image, patch_writer);
- return GenerateBufferCommon(
- old_image, new_image,
- std::make_unique<ImposedEnsembleMatcher>(imposed_matches), patch_writer);
- }
- status::Code GenerateBufferRaw(ConstBufferView old_image,
- ConstBufferView new_image,
- EnsemblePatchWriter* patch_writer) {
- ImageIndex old_image_index(old_image);
- EncodedView old_view(old_image_index);
- std::vector<offset_t> old_sa =
- MakeSuffixArray<InducedSuffixSort>(old_view, old_view.Cardinality());
- PatchElementWriter patch_element(
- {Element(old_image.local_region()), Element(new_image.local_region())});
- if (!GenerateRawElement(old_sa, old_image, new_image, &patch_element))
- return status::kStatusFatal;
- patch_writer->AddElement(std::move(patch_element));
- return status::kStatusSuccess;
- }
- } // namespace zucchini
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