1 : // Copyright 2012 Google Inc. All Rights Reserved.
2 : //
3 : // Licensed under the Apache License, Version 2.0 (the "License");
4 : // you may not use this file except in compliance with the License.
5 : // You may obtain a copy of the License at
6 : //
7 : // http://www.apache.org/licenses/LICENSE-2.0
8 : //
9 : // Unless required by applicable law or agreed to in writing, software
10 : // distributed under the License is distributed on an "AS IS" BASIS,
11 : // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 : // See the License for the specific language governing permissions and
13 : // limitations under the License.
14 :
15 : #include "syzygy/pe/decomposer.h"
16 :
17 : #include "pcrecpp.h" // NOLINT
18 : #include "base/bind.h"
19 : #include "base/strings/string_split.h"
20 : #include "base/strings/stringprintf.h"
21 : #include "base/strings/utf_string_conversions.h"
22 : #include "base/win/scoped_bstr.h"
23 : #include "base/win/scoped_comptr.h"
24 : #include "syzygy/core/zstream.h"
25 : #include "syzygy/pdb/omap.h"
26 : #include "syzygy/pdb/pdb_byte_stream.h"
27 : #include "syzygy/pdb/pdb_constants.h"
28 : #include "syzygy/pdb/pdb_dbi_stream.h"
29 : #include "syzygy/pdb/pdb_file.h"
30 : #include "syzygy/pdb/pdb_reader.h"
31 : #include "syzygy/pdb/pdb_symbol_record.h"
32 : #include "syzygy/pdb/pdb_util.h"
33 : #include "syzygy/pe/dia_util.h"
34 : #include "syzygy/pe/find.h"
35 : #include "syzygy/pe/pe_file_parser.h"
36 : #include "syzygy/pe/pe_utils.h"
37 : #include "syzygy/pe/serialization.h"
38 : #include "third_party/cci/Files/CvInfo.h"
39 :
40 : namespace cci = Microsoft_Cci_Pdb;
41 :
42 : namespace {
43 :
44 : using block_graph::BlockGraph;
45 : using block_graph::BlockInfo;
46 : using core::AbsoluteAddress;
47 : using core::FileOffsetAddress;
48 : using core::RelativeAddress;
49 :
50 : typedef BlockGraph::Block Block;
51 :
52 : } // namespace
53 :
54 : namespace pe {
55 :
56 : // An intermediate reference representation used while parsing PE blocks.
57 : // This is necessary because at that point we haven't yet chunked the whole
58 : // image into blocks thus some references cannot be resolved.
59 : struct Decomposer::IntermediateReference {
60 : RelativeAddress src_addr;
61 : BlockGraph::ReferenceType type;
62 : BlockGraph::Size size;
63 : RelativeAddress dst_addr;
64 : };
65 :
66 : namespace {
67 :
68 : using base::win::ScopedBstr;
69 : using base::win::ScopedComPtr;
70 : using builder::Callback;
71 : using builder::Opt;
72 : using builder::Or;
73 : using builder::Seq;
74 : using builder::Star;
75 :
76 : typedef BlockGraph::BlockType BlockType;
77 : typedef BlockGraph::Offset Offset;
78 : typedef BlockGraph::Reference Reference;
79 : typedef BlockGraph::ReferenceType ReferenceType;
80 : typedef core::AddressRange<RelativeAddress, size_t> RelativeRange;
81 : typedef Decomposer::IntermediateReference IntermediateReference;
82 : typedef Decomposer::IntermediateReferences IntermediateReferences;
83 : typedef pcrecpp::RE RE;
84 : typedef std::vector<OMAP> OMAPs;
85 : typedef std::vector<pdb::PdbFixup> PdbFixups;
86 :
87 : const char kJumpTable[] = "<jump-table>";
88 : const char kCaseTable[] = "<case-table>";
89 :
90 : // The MS linker pads between code blocks with int3s.
91 : static const uint8 kInt3 = 0xCC;
92 : static const size_t kPointerSize = BlockGraph::Reference::kMaximumSize;
93 :
94 : // Some helper functions for testing ranges.
95 : template<typename T1, typename T2, typename T3>
96 E : bool InRange(T1 value, T2 lower_bound_incl, T3 length_excl) {
97 E : T1 upper_bound_excl = static_cast<T1>(lower_bound_incl) + length_excl;
98 : return static_cast<T1>(lower_bound_incl) <= value &&
99 E : value < static_cast<T2>(upper_bound_excl);
100 E : }
101 : template<typename T1, typename T2, typename T3>
102 E : bool InRangeIncl(T1 value, T2 lower_bound_incl, T3 length_incl) {
103 E : T1 upper_bound_incl = static_cast<T1>(lower_bound_incl) + length_incl;
104 : return static_cast<T1>(lower_bound_incl) <= value &&
105 E : value <= upper_bound_incl;
106 E : }
107 :
108 : bool InitializeDia(const PEFile& image_file,
109 : const base::FilePath& pdb_path,
110 : IDiaDataSource** dia_source,
111 : IDiaSession** dia_session,
112 E : IDiaSymbol** global) {
113 E : DCHECK_EQ(reinterpret_cast<IDiaDataSource*>(NULL), *dia_source);
114 E : DCHECK_EQ(reinterpret_cast<IDiaSession*>(NULL), *dia_session);
115 E : DCHECK_EQ(reinterpret_cast<IDiaSymbol*>(NULL), *global);
116 :
117 E : if (!CreateDiaSource(dia_source))
118 i : return false;
119 E : DCHECK_NE(reinterpret_cast<IDiaDataSource*>(NULL), *dia_source);
120 :
121 : // We create the session using the PDB file directly, as we've already
122 : // validated that it matches the module.
123 E : if (!CreateDiaSession(pdb_path, *dia_source, dia_session))
124 i : return false;
125 E : DCHECK_NE(reinterpret_cast<IDiaSession*>(NULL), *dia_session);
126 :
127 E : HRESULT hr = (*dia_session)->get_globalScope(global);
128 E : if (hr != S_OK) {
129 i : LOG(ERROR) << "Failed to get the DIA global scope: "
130 : << common::LogHr(hr) << ".";
131 i : return false;
132 : }
133 :
134 E : return true;
135 E : }
136 :
137 : // Given a compiland, returns its compiland details.
138 : bool GetCompilandDetailsForCompiland(IDiaSymbol* compiland,
139 E : IDiaSymbol** compiland_details) {
140 E : DCHECK_NE(reinterpret_cast<IDiaSymbol*>(NULL), compiland);
141 E : DCHECK_NE(reinterpret_cast<IDiaSymbol**>(NULL), compiland_details);
142 E : DCHECK(IsSymTag(compiland, SymTagCompiland));
143 E : DCHECK_EQ(reinterpret_cast<IDiaSymbol*>(NULL), *compiland_details);
144 :
145 : // Get the enumeration of compiland details.
146 E : ScopedComPtr<IDiaEnumSymbols> enum_symbols;
147 : HRESULT hr = compiland->findChildren(SymTagCompilandDetails, NULL, 0,
148 E : enum_symbols.Receive());
149 E : DCHECK_EQ(S_OK, hr);
150 :
151 : // We expect there to be compiland details. For compilands built by
152 : // non-standard toolchains, there usually aren't any.
153 E : LONG count = 0;
154 E : hr = enum_symbols->get_Count(&count);
155 E : DCHECK_EQ(S_OK, hr);
156 E : if (count == 0) {
157 : // We don't log here because we see this quite often.
158 i : return false;
159 : }
160 :
161 : // We do sometimes encounter more than one compiland detail. In fact, for
162 : // import and export tables we get one compiland detail per table entry.
163 : // They are all marked as having been generated by the linker, so using the
164 : // first one is sufficient.
165 :
166 : // Get the compiland details.
167 E : ULONG fetched = 0;
168 E : hr = enum_symbols->Next(1, compiland_details, &fetched);
169 E : DCHECK_EQ(S_OK, hr);
170 E : DCHECK_EQ(1u, fetched);
171 :
172 E : return true;
173 E : }
174 :
175 : // Stores information regarding known compilers.
176 : struct KnownCompilerInfo {
177 : wchar_t* compiler_name;
178 : bool supported;
179 : };
180 :
181 : // A list of known compilers, and their status as being supported or not.
182 : KnownCompilerInfo kKnownCompilerInfos[] = {
183 : { L"Microsoft (R) Macro Assembler", false },
184 : { L"Microsoft (R) Optimizing Compiler", true },
185 : { L"Microsoft (R) LINK", false }
186 : };
187 :
188 : // Given a compiland, determines whether the compiler used is one of those that
189 : // we whitelist.
190 E : bool IsBuiltBySupportedCompiler(IDiaSymbol* compiland) {
191 E : DCHECK_NE(reinterpret_cast<IDiaSymbol*>(NULL), compiland);
192 E : DCHECK(IsSymTag(compiland, SymTagCompiland));
193 :
194 E : ScopedComPtr<IDiaSymbol> compiland_details;
195 : if (!GetCompilandDetailsForCompiland(compiland,
196 E : compiland_details.Receive())) {
197 : // If the compiland has no compiland details we assume the compiler is not
198 : // supported.
199 i : ScopedBstr compiland_name;
200 i : if (compiland->get_name(compiland_name.Receive()) == S_OK) {
201 i : VLOG(1) << "Compiland has no compiland details: "
202 : << common::ToString(compiland_name);
203 : }
204 i : return false;
205 : }
206 E : DCHECK_NE(reinterpret_cast<IDiaSymbol*>(NULL), compiland_details.get());
207 :
208 : // Get the compiler name.
209 E : ScopedBstr compiler_name;
210 E : HRESULT hr = compiland_details->get_compilerName(compiler_name.Receive());
211 E : DCHECK_EQ(S_OK, hr);
212 :
213 : // Check the compiler name against the list of known compilers.
214 E : for (size_t i = 0; i < arraysize(kKnownCompilerInfos); ++i) {
215 E : if (::wcscmp(kKnownCompilerInfos[i].compiler_name, compiler_name) == 0) {
216 E : return kKnownCompilerInfos[i].supported;
217 : }
218 E : }
219 :
220 : // Anything we don't explicitly know about is not supported.
221 E : VLOG(1) << "Encountered unknown compiler: " << compiler_name;
222 E : return false;
223 E : }
224 :
225 : // Adds an intermediate reference to the provided vector. The vector is
226 : // specified as the first parameter (in slight violation of our coding
227 : // standards) because this function is intended to be used by Bind.
228 : bool AddIntermediateReference(IntermediateReferences* references,
229 : RelativeAddress src_addr,
230 : ReferenceType type,
231 : BlockGraph::Size size,
232 E : RelativeAddress dst_addr) {
233 E : DCHECK_NE(reinterpret_cast<IntermediateReferences*>(NULL), references);
234 E : IntermediateReference ref = { src_addr, type, size, dst_addr };
235 E : references->push_back(ref);
236 E : return true;
237 E : }
238 :
239 : // Create a reference as specified. Ignores existing references if they are of
240 : // the exact same type.
241 : bool CreateReference(RelativeAddress src_addr,
242 : BlockGraph::Size ref_size,
243 : ReferenceType ref_type,
244 : RelativeAddress base_addr,
245 : RelativeAddress dst_addr,
246 E : BlockGraph::AddressSpace* image) {
247 E : DCHECK_NE(reinterpret_cast<BlockGraph::AddressSpace*>(NULL), image);
248 :
249 : // Get the source block and offset, and ensure that the reference fits
250 : // within it.
251 E : Block* src_block = image->GetBlockByAddress(src_addr);
252 E : if (src_block == NULL) {
253 i : LOG(ERROR) << "Unable to find block for reference originating at "
254 : << src_addr << ".";
255 i : return false;
256 : }
257 E : RelativeAddress src_block_addr;
258 E : CHECK(image->GetAddressOf(src_block, &src_block_addr));
259 E : Offset src_block_offset = src_addr - src_block_addr;
260 E : if (src_block_offset + ref_size > src_block->size()) {
261 i : LOG(ERROR) << "Reference originating at " << src_addr
262 : << " extends beyond block \"" << src_block->name() << "\".";
263 i : return false;
264 : }
265 :
266 : // Get the destination block and offset.
267 E : Block* dst_block = image->GetBlockByAddress(base_addr);
268 E : if (dst_block == NULL) {
269 i : LOG(ERROR) << "Unable to find block for reference pointing at "
270 : << base_addr << ".";
271 i : return false;
272 : }
273 E : RelativeAddress dst_block_addr;
274 E : CHECK(image->GetAddressOf(dst_block, &dst_block_addr));
275 E : Offset base = base_addr - dst_block_addr;
276 E : Offset offset = dst_addr - dst_block_addr;
277 :
278 E : Reference ref(ref_type, ref_size, dst_block, offset, base);
279 :
280 : // Check if a reference already exists at this offset.
281 : Block::ReferenceMap::const_iterator ref_it =
282 E : src_block->references().find(src_block_offset);
283 E : if (ref_it != src_block->references().end()) {
284 : // If an identical reference already exists then we're done.
285 E : if (ref == ref_it->second)
286 E : return true;
287 i : LOG(ERROR) << "Block \"" << src_block->name() << "\" has a conflicting "
288 : << "reference at offset " << src_block_offset << ".";
289 i : return false;
290 : }
291 :
292 E : CHECK(src_block->SetReference(src_block_offset, ref));
293 :
294 E : return true;
295 E : }
296 :
297 : // Loads FIXUP and OMAP_FROM debug streams.
298 : bool LoadDebugStreams(IDiaSession* dia_session,
299 : PdbFixups* pdb_fixups,
300 E : OMAPs* omap_from) {
301 E : DCHECK_NE(reinterpret_cast<IDiaSession*>(NULL), dia_session);
302 E : DCHECK_NE(reinterpret_cast<PdbFixups*>(NULL), pdb_fixups);
303 E : DCHECK_NE(reinterpret_cast<OMAPs*>(NULL), omap_from);
304 :
305 : // Load the fixups. These must exist.
306 : SearchResult search_result = FindAndLoadDiaDebugStreamByName(
307 E : kFixupDiaDebugStreamName, dia_session, pdb_fixups);
308 E : if (search_result != kSearchSucceeded) {
309 i : if (search_result == kSearchFailed) {
310 i : LOG(ERROR) << "PDB file does not contain a FIXUP stream. Module must be "
311 : "linked with '/PROFILE' or '/DEBUGINFO:FIXUP' flag.";
312 : }
313 i : return false;
314 : }
315 :
316 : // Load the omap_from table. It is not necessary that one exist.
317 : search_result = FindAndLoadDiaDebugStreamByName(
318 E : kOmapFromDiaDebugStreamName, dia_session, omap_from);
319 E : if (search_result == kSearchErrored) {
320 i : LOG(ERROR) << "Error trying to read " << kOmapFromDiaDebugStreamName
321 : << " stream.";
322 i : return false;
323 : }
324 :
325 E : return true;
326 E : }
327 :
328 : bool GetFixupDestinationAndType(const PEFile& image_file,
329 : const pdb::PdbFixup& fixup,
330 : RelativeAddress* dst_addr,
331 E : ReferenceType* ref_type) {
332 E : DCHECK_NE(reinterpret_cast<RelativeAddress*>(NULL), dst_addr);
333 E : DCHECK_NE(reinterpret_cast<ReferenceType*>(NULL), ref_type);
334 :
335 E : RelativeAddress src_addr(fixup.rva_location);
336 :
337 : // Get the destination displacement from the actual image itself. We only see
338 : // fixups for 32-bit references.
339 E : uint32 data = 0;
340 E : if (!image_file.ReadImage(src_addr, &data, sizeof(data))) {
341 i : LOG(ERROR) << "Unable to read image data for fixup with source address "
342 : << "at" << src_addr << ".";
343 i : return false;
344 : }
345 :
346 : // Translate this to a relative displacement value.
347 E : switch (fixup.type) {
348 : case pdb::PdbFixup::TYPE_ABSOLUTE: {
349 E : *ref_type = BlockGraph::ABSOLUTE_REF;
350 E : *dst_addr = RelativeAddress(image_file.AbsToRelDisplacement(data));
351 E : break;
352 : }
353 :
354 : case pdb::PdbFixup::TYPE_PC_RELATIVE: {
355 E : *ref_type = BlockGraph::PC_RELATIVE_REF;
356 E : *dst_addr = RelativeAddress(fixup.rva_location) + sizeof(data) + data;
357 E : break;
358 : }
359 :
360 : case pdb::PdbFixup::TYPE_RELATIVE: {
361 E : *ref_type = BlockGraph::RELATIVE_REF;
362 E : *dst_addr = RelativeAddress(data);
363 E : break;
364 : }
365 :
366 : default: {
367 i : LOG(ERROR) << "Unexpected fixup type (" << fixup.type << ").";
368 i : return false;
369 : }
370 : }
371 :
372 E : return true;
373 E : }
374 :
375 : // Creates references from the @p pdb_fixups (translating them via the
376 : // provided @p omap_from information if it is not empty), all while removing the
377 : // corresponding entries from @p reloc_set. If @p reloc_set is not empty after
378 : // this then the PDB fixups are out of sync with the image and we are unable to
379 : // safely decompose.
380 : //
381 : // @note This function deliberately ignores fixup information for the resource
382 : // section. This is because chrome.dll gets modified by a manifest tool
383 : // which doesn't update the FIXUPs in the corresponding PDB. They are thus
384 : // out of sync. Even if they were in sync this doesn't harm us as we have no
385 : // need to reach in and modify resource data.
386 : bool CreateReferencesFromFixupsImpl(
387 : const PEFile& image_file,
388 : const PdbFixups& pdb_fixups,
389 : const OMAPs& omap_from,
390 : PEFile::RelocSet* reloc_set,
391 E : BlockGraph::AddressSpace* image) {
392 E : DCHECK_NE(reinterpret_cast<PEFile::RelocSet*>(NULL), reloc_set);
393 E : DCHECK_NE(reinterpret_cast<BlockGraph::AddressSpace*>(NULL), image);
394 :
395 E : bool have_omap = !omap_from.empty();
396 E : size_t fixups_used = 0;
397 :
398 : // The resource section in Chrome is modified post-link by a tool that adds a
399 : // manifest to it. This causes all of the fixups in the resource section (and
400 : // anything beyond it) to be invalid. As long as the resource section is the
401 : // last section in the image, this is not a problem (we can safely ignore the
402 : // .rsrc fixups, which we know how to parse without them). However, if there
403 : // is a section after the resource section, things will have been shifted
404 : // and potentially crucial fixups will be invalid.
405 : const IMAGE_SECTION_HEADER* rsrc_header = image_file.GetSectionHeader(
406 E : kResourceSectionName);
407 E : RelativeAddress rsrc_start(0xffffffff);
408 E : RelativeAddress rsrc_end(0xffffffff);
409 E : if (rsrc_header != NULL) {
410 E : rsrc_start = RelativeAddress(rsrc_header->VirtualAddress);
411 E : rsrc_end = rsrc_start + rsrc_header->Misc.VirtualSize;
412 : }
413 :
414 : // Ensure the fixups are all valid.
415 E : for (size_t i = 0; i < pdb_fixups.size(); ++i) {
416 E : if (!pdb_fixups[i].ValidHeader()) {
417 i : LOG(ERROR) << "Unknown fixup header: "
418 : << base::StringPrintf("0x%08X.", pdb_fixups[i].header);
419 i : return false;
420 : }
421 :
422 : // For now, we skip any offset fixups. We've only seen this in the context
423 : // of TLS data access, and we don't mess with TLS structures.
424 E : if (pdb_fixups[i].is_offset())
425 E : continue;
426 :
427 : // All fixups we handle should be full size pointers.
428 E : DCHECK_EQ(Reference::kMaximumSize, pdb_fixups[i].size());
429 :
430 : // Get the original addresses, and map them through OMAP information.
431 : // Normally DIA takes care of this for us, but there is no API for
432 : // getting DIA to give us FIXUP information, so we have to do it manually.
433 E : RelativeAddress src_addr(pdb_fixups[i].rva_location);
434 E : RelativeAddress base_addr(pdb_fixups[i].rva_base);
435 E : if (have_omap) {
436 i : src_addr = pdb::TranslateAddressViaOmap(omap_from, src_addr);
437 i : base_addr = pdb::TranslateAddressViaOmap(omap_from, base_addr);
438 : }
439 :
440 : // If the reference originates beyond the .rsrc section then we can't
441 : // trust it.
442 E : if (src_addr >= rsrc_end) {
443 i : LOG(ERROR) << "Found fixup originating beyond .rsrc section.";
444 i : return false;
445 : }
446 :
447 : // If the reference originates from a part of the .rsrc section, ignore it.
448 E : if (src_addr >= rsrc_start)
449 E : continue;
450 :
451 : // Get the relative address/displacement of the fixup. This logs on failure.
452 E : RelativeAddress dst_addr;
453 E : ReferenceType type = BlockGraph::RELATIVE_REF;
454 : if (!GetFixupDestinationAndType(image_file, pdb_fixups[i], &dst_addr,
455 E : &type)) {
456 i : return false;
457 : }
458 :
459 : // Finally, create the reference. This logs verbosely for us on failure.
460 : if (!CreateReference(src_addr, Reference::kMaximumSize, type, base_addr,
461 E : dst_addr, image)) {
462 i : return false;
463 : }
464 :
465 : // Remove this reference from the relocs.
466 E : PEFile::RelocSet::iterator reloc_it = reloc_set->find(src_addr);
467 E : if (reloc_it != reloc_set->end()) {
468 : // We should only find a reloc if the fixup was of absolute type.
469 E : if (type != BlockGraph::ABSOLUTE_REF) {
470 i : LOG(ERROR) << "Found a reloc corresponding to a non-absolute fixup.";
471 i : return false;
472 : }
473 :
474 E : reloc_set->erase(reloc_it);
475 : }
476 :
477 E : ++fixups_used;
478 E : }
479 :
480 E : return true;
481 E : }
482 :
483 E : bool GetDataSymbolSize(IDiaSymbol* symbol, size_t* length) {
484 E : DCHECK_NE(reinterpret_cast<IDiaSymbol*>(NULL), symbol);
485 E : DCHECK_NE(reinterpret_cast<size_t*>(NULL), length);
486 :
487 E : *length = 0;
488 E : ScopedComPtr<IDiaSymbol> type;
489 E : HRESULT hr = symbol->get_type(type.Receive());
490 : // This happens if the symbol has no type information.
491 E : if (hr == S_FALSE)
492 E : return true;
493 E : if (hr != S_OK) {
494 i : LOG(ERROR) << "Failed to get type symbol: " << common::LogHr(hr) << ".";
495 i : return false;
496 : }
497 :
498 E : ULONGLONG ull_length = 0;
499 E : hr = type->get_length(&ull_length);
500 E : if (hr != S_OK) {
501 i : LOG(ERROR) << "Failed to retrieve type length properties: "
502 : << common::LogHr(hr) << ".";
503 i : return false;
504 : }
505 E : DCHECK_LE(ull_length, 0xFFFFFFFF);
506 E : *length = static_cast<size_t>(ull_length);
507 :
508 E : return true;
509 E : }
510 :
511 : bool ScopeSymTagToLabelProperties(enum SymTagEnum sym_tag,
512 : size_t scope_count,
513 : BlockGraph::LabelAttributes* attr,
514 E : std::string* name) {
515 E : DCHECK_NE(reinterpret_cast<BlockGraph::LabelAttributes*>(NULL), attr);
516 E : DCHECK_NE(reinterpret_cast<std::string*>(NULL), name);
517 :
518 E : switch (sym_tag) {
519 : case SymTagFuncDebugStart: {
520 E : *attr = BlockGraph::DEBUG_START_LABEL;
521 E : *name = "<debug-start>";
522 E : return true;
523 : }
524 : case SymTagFuncDebugEnd: {
525 E : *attr = BlockGraph::DEBUG_END_LABEL;
526 E : *name = "<debug-end>";
527 E : return true;
528 : }
529 : case SymTagBlock: {
530 E : *attr = BlockGraph::SCOPE_START_LABEL;
531 E : *name = base::StringPrintf("<scope-start-%d>", scope_count);
532 E : return true;
533 : }
534 : default:
535 i : return false;
536 : }
537 i : return false;
538 E : }
539 :
540 : // Reads the linker module symbol stream from the given PDB file. This should
541 : // always exist as the last module.
542 : scoped_refptr<pdb::PdbStream> GetLinkerSymbolStream(
543 E : const pdb::PdbFile& pdb_file) {
544 : static const char kLinkerModuleName[] = "* Linker *";
545 :
546 : // Get the DBI stream.
547 : scoped_refptr<pdb::PdbStream> stream =
548 E : pdb_file.GetStream(pdb::kDbiStream);
549 E : if (stream.get() == NULL) {
550 i : LOG(ERROR) << "PDB does not contain a DBI stream.";
551 i : return false;
552 : }
553 :
554 : // Read the entire thing into memory before parsing it. This makes parsing
555 : // much faster.
556 E : scoped_refptr<pdb::PdbByteStream> dbi_stream(new pdb::PdbByteStream());
557 E : if (!dbi_stream->Init(stream.get())) {
558 i : LOG(ERROR) << "Failed to read DBI stream.";
559 : }
560 :
561 : // Parse the DBI stream.
562 E : pdb::DbiStream dbi;
563 E : if (!dbi.Read(dbi_stream.get())) {
564 i : LOG(ERROR) << "Unable to parse DBI stream.";
565 i : return false;
566 : }
567 :
568 E : if (dbi.modules().empty()) {
569 i : LOG(ERROR) << "DBI stream contains no modules.";
570 i : return false;
571 : }
572 :
573 : // The last module has always been observed to be the linker module.
574 E : const pdb::DbiModuleInfo& linker = dbi.modules().back();
575 E : if (linker.module_name() != kLinkerModuleName) {
576 i : LOG(ERROR) << "Last module is not the linker module.";
577 i : return false;
578 : }
579 :
580 : // Get the symbol stream.
581 E : stream = pdb_file.GetStream(linker.module_info_base().stream);
582 E : if (stream.get() == NULL) {
583 i : LOG(ERROR) << "Unable to open linker symbol stream.";
584 i : return false;
585 : }
586 :
587 : // Also read it entirely into memory for faster parsing.
588 E : scoped_refptr<pdb::PdbByteStream> symbols(new pdb::PdbByteStream());
589 E : if (!symbols->Init(stream.get())) {
590 i : LOG(ERROR) << "Failed to read linker symbol stream.";
591 : }
592 :
593 E : return symbols;
594 E : }
595 :
596 : // Parses a symbol from a PDB symbol stream. The @p buffer is populated with the
597 : // data and upon success this returns the symbol directly cast onto the
598 : // @p buffer data. On failure this returns NULL.
599 : template<typename SymbolType>
600 : const SymbolType* ParseSymbol(uint16 symbol_length,
601 : pdb::PdbStream* stream,
602 E : std::vector<uint8>* buffer) {
603 E : DCHECK_NE(reinterpret_cast<pdb::PdbStream*>(NULL), stream);
604 E : DCHECK_NE(reinterpret_cast<std::vector<uint8>*>(NULL), buffer);
605 :
606 E : buffer->clear();
607 :
608 E : if (symbol_length < sizeof(SymbolType)) {
609 i : LOG(ERROR) << "Symbol too small for casting.";
610 i : return NULL;
611 : }
612 :
613 E : if (!stream->Read(buffer, symbol_length)) {
614 i : LOG(ERROR) << "Failed to read symbol.";
615 i : return NULL;
616 : }
617 :
618 E : return reinterpret_cast<const SymbolType*>(buffer->data());
619 E : }
620 :
621 : // If the given run of bytes consists of a single value repeated, returns that
622 : // value. Otherwise, returns -1.
623 E : int RepeatedValue(const uint8* data, size_t size) {
624 E : DCHECK_NE(reinterpret_cast<uint8*>(NULL), data);
625 E : const uint8* data_end = data + size;
626 E : uint8 value = *(data++);
627 E : for (; data < data_end; ++data) {
628 E : if (*data != value)
629 i : return -1;
630 E : }
631 E : return value;
632 E : }
633 :
634 : // Searches through the given image layout graph, and labels blocks that are
635 : // simply padding blocks.
636 E : bool FindPaddingBlocks(ImageLayout* image_layout) {
637 E : DCHECK_NE(reinterpret_cast<ImageLayout*>(NULL), image_layout);
638 :
639 E : BlockGraph* block_graph = image_layout->blocks.graph();
640 E : DCHECK_NE(reinterpret_cast<BlockGraph*>(NULL), block_graph);
641 :
642 : BlockGraph::BlockMap::iterator block_it =
643 E : block_graph->blocks_mutable().begin();
644 E : for (; block_it != block_graph->blocks_mutable().end(); ++block_it) {
645 E : Block& block = block_it->second;
646 :
647 : // Padding blocks must not have any symbol information: no labels,
648 : // no references, no referrers, and they must be a gap block.
649 : if (block.labels().size() != 0 ||
650 : block.references().size() != 0 ||
651 : block.referrers().size() != 0 ||
652 E : (block.attributes() & BlockGraph::GAP_BLOCK) == 0) {
653 E : continue;
654 : }
655 :
656 E : switch (block.type()) {
657 : // Code blocks should be fully defined and consist of only int3s.
658 : case BlockGraph::CODE_BLOCK: {
659 : if (block.data_size() != block.size() ||
660 E : RepeatedValue(block.data(), block.data_size()) != kInt3)
661 i : continue;
662 E : break;
663 : }
664 :
665 : // Data blocks should be uninitialized or have fully defined data
666 : // consisting only of zeros.
667 : default: {
668 E : DCHECK_EQ(BlockGraph::DATA_BLOCK, block.type());
669 E : if (block.data_size() == 0) // Uninitialized data blocks are padding.
670 E : break;
671 : if (block.data_size() != block.size() ||
672 E : RepeatedValue(block.data(), block.data_size()) != 0)
673 i : continue;
674 : }
675 : }
676 :
677 : // If we fall through to this point, then the block is a padding block.
678 E : block.set_attribute(BlockGraph::PADDING_BLOCK);
679 E : }
680 :
681 E : return true;
682 E : }
683 :
684 E : bool CodeBlockHasAlignedJumpTables(const Block* block) {
685 E : DCHECK_NE(reinterpret_cast<Block*>(NULL), block);
686 E : DCHECK_EQ(BlockGraph::CODE_BLOCK, block->type());
687 :
688 : // Iterate over the labels of this block looking for jump tables.
689 E : bool has_jump_tables = false;
690 : Block::LabelMap::const_iterator label_it =
691 E : block->labels().begin();
692 E : for (; label_it != block->labels().end(); ++label_it) {
693 E : if (!label_it->second.has_attributes(BlockGraph::JUMP_TABLE_LABEL))
694 E : continue;
695 :
696 E : has_jump_tables = true;
697 :
698 : // If the jump table is misaligned we can return false immediately.
699 E : if (label_it->first % kPointerSize != 0)
700 i : return false;
701 E : }
702 :
703 E : return has_jump_tables;
704 E : }
705 :
706 E : bool AlignCodeBlocks(ImageLayout* image_layout) {
707 E : DCHECK_NE(reinterpret_cast<ImageLayout*>(NULL), image_layout);
708 :
709 : BlockGraph::AddressSpace::RangeMapConstIter block_it =
710 E : image_layout->blocks.begin();
711 E : for (; block_it != image_layout->blocks.end(); ++block_it) {
712 E : Block* block = block_it->second;
713 E : if (block->type() != BlockGraph::CODE_BLOCK)
714 E : continue;
715 :
716 : // Preserve alignment for anything built by an unknown compiler. There may
717 : // be inline data that has alignment requirements we don't know about. SSE
718 : // and AVX instructions have 8 and 16 byte alignments, so we preserve
719 : // these. It is not possible for a function to contain both instructions
720 : // and data with an alignment constraint unless the size of the block is at
721 : // least twice the alignment; this is used as a simple filter to avoid
722 : // adding alignment where unnecessary.
723 E : if (block->attributes() & BlockGraph::BUILT_BY_UNSUPPORTED_COMPILER) {
724 E : uint32 align = std::min(16u, block_it->first.start().GetAlignment());
725 E : if (align >= 8 && block->size() >= 2 * align) {
726 E : VLOG(1) << "Preserving alignment of " << BlockInfo(block) << " as "
727 : << align << ".";
728 E : block->set_alignment(align);
729 E : continue;
730 : }
731 : }
732 :
733 : // We only care about code blocks that are already 4-byte aligned but
734 : // whose explicit alignment is currently less than that.
735 E : if (block->alignment() >= kPointerSize)
736 i : continue;
737 E : if (block_it->first.start().value() % kPointerSize != 0)
738 E : continue;
739 :
740 : // Inspect them to see if they have aligned jump tables. If they do,
741 : // set the alignment of the block itself.
742 E : if (CodeBlockHasAlignedJumpTables(block_it->second))
743 E : block->set_alignment(kPointerSize);
744 E : }
745 :
746 E : return true;
747 E : }
748 :
749 : void GuessDataBlockAlignment(uint32 max_alignment,
750 : RelativeAddress block_rva,
751 E : Block* block) {
752 E : DCHECK_NE(static_cast<Block*>(NULL), block);
753 E : DCHECK_EQ(BlockGraph::DATA_BLOCK, block->type());
754 E : uint32 alignment = block_rva.GetAlignment();
755 : // Cap the alignment.
756 E : if (alignment > max_alignment)
757 E : alignment = max_alignment;
758 E : block->set_alignment(alignment);
759 E : }
760 :
761 : void GuessDataBlockAlignments(const PEFile& pe_file,
762 E : ImageLayout* image_layout) {
763 E : DCHECK_NE(static_cast<ImageLayout*>(NULL), image_layout);
764 :
765 E : uint32 max_alignment = pe_file.nt_headers()->OptionalHeader.SectionAlignment;
766 :
767 E : BlockGraph::AddressSpace::RangeMapConstIter it = image_layout->blocks.begin();
768 E : for (; it != image_layout->blocks.end(); ++it) {
769 E : RelativeAddress block_rva = it->first.start();
770 E : BlockGraph::Block* block = it->second;
771 E : if (block->type() != BlockGraph::DATA_BLOCK)
772 E : continue;
773 E : GuessDataBlockAlignment(max_alignment, block_rva, block);
774 E : }
775 E : }
776 :
777 : } // namespace
778 :
779 : // We use ", " as a separator between symbol names. We sometimes see commas
780 : // in symbol names but do not see whitespace. Thus, this provides a useful
781 : // separator that is also human friendly to read.
782 : const char Decomposer::kLabelNameSep[] = ", ";
783 :
784 : // This is by CreateBlocksFromCoffGroups to communicate shared state to
785 : // VisitLinkerSymbol via the VisitSymbols helper function.
786 : struct Decomposer::VisitLinkerSymbolContext {
787 : int current_group_index;
788 : std::string current_group_prefix;
789 : RelativeAddress current_group_start;
790 :
791 : // These are the set of patterns that indicate bracketing groups. They
792 : // should match both the opening and the closing symbol, and have at least
793 : // one match group returning the common prefix.
794 : std::vector<RE> bracketing_groups;
795 :
796 E : VisitLinkerSymbolContext() : current_group_index(-1) {
797 : // Matches groups like: .CRT$XCA -> .CRT$XCZ
798 E : bracketing_groups.push_back(RE("(\\.CRT\\$X.)[AZ]"));
799 : // Matches groups like: .rtc$IAA -> .rtc$IZZ
800 E : bracketing_groups.push_back(RE("(\\.rtc\\$.*)(AA|ZZ)"));
801 : // Matches exactly: ATL$__a -> ATL$__z
802 E : bracketing_groups.push_back(RE("(ATL\\$__)[az]"));
803 : // Matches exactly: .tls -> .tls$ZZZ
804 E : bracketing_groups.push_back(RE("(\\.tls)(\\$ZZZ)?"));
805 E : }
806 :
807 : private:
808 : DISALLOW_COPY_AND_ASSIGN(VisitLinkerSymbolContext);
809 : };
810 :
811 : Decomposer::Decomposer(const PEFile& image_file)
812 : : image_file_(image_file), image_layout_(NULL), image_(NULL),
813 E : current_block_(NULL), current_scope_count_(0) {
814 E : }
815 :
816 E : bool Decomposer::Decompose(ImageLayout* image_layout) {
817 E : DCHECK_NE(reinterpret_cast<ImageLayout*>(NULL), image_layout);
818 :
819 : // The temporaries should be NULL.
820 E : DCHECK_EQ(reinterpret_cast<ImageLayout*>(NULL), image_layout_);
821 E : DCHECK_EQ(reinterpret_cast<BlockGraph::AddressSpace*>(NULL), image_);
822 :
823 : // Set the image format.
824 E : image_layout->blocks.graph()->set_image_format(BlockGraph::PE_IMAGE);
825 :
826 : // We start by finding the PDB path.
827 E : if (!FindAndValidatePdbPath())
828 E : return false;
829 E : DCHECK(!pdb_path_.empty());
830 :
831 : // Load the serialized block-graph from the PDB if it exists. This allows
832 : // round-trip decomposition.
833 E : bool stream_exists = false;
834 : if (LoadBlockGraphFromPdb(
835 E : pdb_path_, image_file_, image_layout, &stream_exists)) {
836 E : return true;
837 E : } else if (stream_exists) {
838 : // If the stream exists but hasn't been loaded we return an error. At this
839 : // point an error message has already been logged if there was one.
840 i : return false;
841 : }
842 :
843 : // At this point a full decomposition needs to be performed.
844 E : image_layout_ = image_layout;
845 E : image_ = &(image_layout->blocks);
846 E : bool success = DecomposeImpl();
847 E : image_layout_ = NULL;
848 E : image_ = NULL;
849 :
850 E : return success;
851 E : }
852 :
853 E : bool Decomposer::FindAndValidatePdbPath() {
854 : // Manually find the PDB path if it is not specified.
855 E : if (pdb_path_.empty()) {
856 : if (!FindPdbForModule(image_file_.path(), &pdb_path_) ||
857 E : pdb_path_.empty()) {
858 i : LOG(ERROR) << "Unable to find PDB file for module: "
859 : << image_file_.path().value();
860 i : return false;
861 : }
862 : }
863 E : DCHECK(!pdb_path_.empty());
864 :
865 E : if (!base::PathExists(pdb_path_)) {
866 E : LOG(ERROR) << "Path not found: " << pdb_path_.value();
867 E : return false;
868 : }
869 :
870 E : if (!pe::PeAndPdbAreMatched(image_file_.path(), pdb_path_)) {
871 i : LOG(ERROR) << "PDB file \"" << pdb_path_.value() << "\" does not match "
872 : << "module \"" << image_file_.path().value() << "\".";
873 i : return false;
874 : }
875 :
876 E : return true;
877 E : }
878 :
879 : bool Decomposer::LoadBlockGraphFromPdbStream(
880 : const PEFile& image_file,
881 : pdb::PdbStream* block_graph_stream,
882 E : ImageLayout* image_layout) {
883 E : DCHECK_NE(reinterpret_cast<pdb::PdbStream*>(NULL), block_graph_stream);
884 E : DCHECK_NE(reinterpret_cast<ImageLayout*>(NULL), image_layout);
885 E : LOG(INFO) << "Reading block-graph and image layout from the PDB.";
886 :
887 : // Initialize an input archive pointing to the stream.
888 E : scoped_refptr<pdb::PdbByteStream> byte_stream = new pdb::PdbByteStream();
889 E : if (!byte_stream->Init(block_graph_stream))
890 i : return false;
891 E : DCHECK_NE(reinterpret_cast<pdb::PdbByteStream*>(NULL), byte_stream.get());
892 :
893 E : core::ScopedInStreamPtr pdb_in_stream;
894 : pdb_in_stream.reset(core::CreateByteInStream(
895 E : byte_stream->data(), byte_stream->data() + byte_stream->length()));
896 :
897 : // Read the header.
898 E : uint32 stream_version = 0;
899 E : unsigned char compressed = 0;
900 : if (!pdb_in_stream->Read(sizeof(stream_version),
901 : reinterpret_cast<core::Byte*>(&stream_version)) ||
902 : !pdb_in_stream->Read(sizeof(compressed),
903 E : reinterpret_cast<core::Byte*>(&compressed))) {
904 i : LOG(ERROR) << "Failed to read existing Syzygy block-graph stream header.";
905 i : return false;
906 : }
907 :
908 : // Check the stream version.
909 E : if (stream_version != pdb::kSyzygyBlockGraphStreamVersion) {
910 E : LOG(ERROR) << "PDB contains an unsupported Syzygy block-graph stream"
911 : << " version (got " << stream_version << ", expected "
912 : << pdb::kSyzygyBlockGraphStreamVersion << ").";
913 E : return false;
914 : }
915 :
916 : // If the stream is compressed insert the decompression filter.
917 E : core::InStream* in_stream = pdb_in_stream.get();
918 E : scoped_ptr<core::ZInStream> zip_in_stream;
919 E : if (compressed != 0) {
920 E : zip_in_stream.reset(new core::ZInStream(in_stream));
921 E : if (!zip_in_stream->Init()) {
922 i : LOG(ERROR) << "Unable to initialize ZInStream.";
923 i : return false;
924 : }
925 E : in_stream = zip_in_stream.get();
926 : }
927 :
928 : // Deserialize the image-layout.
929 E : core::NativeBinaryInArchive in_archive(in_stream);
930 E : block_graph::BlockGraphSerializer::Attributes attributes = 0;
931 : if (!LoadBlockGraphAndImageLayout(
932 E : image_file, &attributes, image_layout, &in_archive)) {
933 i : LOG(ERROR) << "Failed to deserialize block-graph and image layout.";
934 i : return false;
935 : }
936 :
937 E : return true;
938 E : }
939 :
940 : bool Decomposer::LoadBlockGraphFromPdb(const base::FilePath& pdb_path,
941 : const PEFile& image_file,
942 : ImageLayout* image_layout,
943 E : bool* stream_exists) {
944 E : DCHECK_NE(reinterpret_cast<ImageLayout*>(NULL), image_layout);
945 E : DCHECK_NE(reinterpret_cast<bool*>(NULL), stream_exists);
946 :
947 E : pdb::PdbFile pdb_file;
948 E : pdb::PdbReader pdb_reader;
949 E : if (!pdb_reader.Read(pdb_path, &pdb_file)) {
950 i : LOG(ERROR) << "Unable to read the PDB named \"" << pdb_path.value()
951 : << "\".";
952 i : return NULL;
953 : }
954 :
955 : // Try to get the block-graph stream from the PDB.
956 E : scoped_refptr<pdb::PdbStream> block_graph_stream;
957 : if (!pdb::LoadNamedStreamFromPdbFile(pdb::kSyzygyBlockGraphStreamName,
958 : &pdb_file,
959 : &block_graph_stream) ||
960 E : block_graph_stream.get() == NULL) {
961 E : *stream_exists = false;
962 E : return false;
963 : }
964 E : if (block_graph_stream->length() == 0) {
965 i : *stream_exists = false;
966 i : LOG(WARNING) << "The block-graph stream is empty, ignoring it.";
967 i : return false;
968 : }
969 :
970 : // The PDB contains a block-graph stream, the block-graph and the image layout
971 : // will be read from this stream.
972 E : *stream_exists = true;
973 : if (!LoadBlockGraphFromPdbStream(image_file, block_graph_stream.get(),
974 E : image_layout)) {
975 i : return false;
976 : }
977 :
978 E : return true;
979 E : }
980 :
981 E : bool Decomposer::DecomposeImpl() {
982 : // Instantiate and initialize our Debug Interface Access session. This logs
983 : // verbosely for us.
984 E : ScopedComPtr<IDiaDataSource> dia_source;
985 E : ScopedComPtr<IDiaSession> dia_session;
986 E : ScopedComPtr<IDiaSymbol> global;
987 : if (!InitializeDia(image_file_, pdb_path_, dia_source.Receive(),
988 E : dia_session.Receive(), global.Receive())) {
989 i : return false;
990 : }
991 :
992 : // Copy the image headers to the layout.
993 : CopySectionHeadersToImageLayout(
994 : image_file_.nt_headers()->FileHeader.NumberOfSections,
995 : image_file_.section_headers(),
996 E : &(image_layout_->sections));
997 :
998 : // Create the sections in the underlying block-graph.
999 E : if (!CopySectionInfoToBlockGraph(image_file_, image_->graph()))
1000 i : return false;
1001 :
1002 : // We scope the first few operations so that we don't keep the intermediate
1003 : // references around any longer than we have to.
1004 : {
1005 E : IntermediateReferences references;
1006 :
1007 : // First we parse out the PE blocks.
1008 E : VLOG(1) << "Parsing PE blocks.";
1009 E : if (!CreatePEImageBlocksAndReferences(&references))
1010 i : return false;
1011 :
1012 : // Now we parse the COFF group symbols from the linker's symbol stream.
1013 : // These indicate things like static initializers, which must stay together
1014 : // in a single block.
1015 E : VLOG(1) << "Parsing COFF groups.";
1016 E : if (!CreateBlocksFromCoffGroups())
1017 i : return false;
1018 :
1019 : // Next we parse out section contributions. Some of these may coincide with
1020 : // existing PE parsed blocks, but when they do we expect them to be exact
1021 : // collisions.
1022 E : VLOG(1) << "Parsing section contributions.";
1023 E : if (!CreateBlocksFromSectionContribs(dia_session.get()))
1024 i : return false;
1025 :
1026 E : VLOG(1) << "Finding cold blocks.";
1027 E : if (!FindColdBlocksFromCompilands(dia_session.get()))
1028 i : return false;
1029 :
1030 : // Flesh out the rest of the image with gap blocks.
1031 E : VLOG(1) << "Creating gap blocks.";
1032 E : if (!CreateGapBlocks())
1033 i : return false;
1034 :
1035 : // Finalize the PE-parsed intermediate references.
1036 E : VLOG(1) << "Finalizing intermediate references.";
1037 E : if (!FinalizeIntermediateReferences(references))
1038 i : return false;
1039 E : }
1040 :
1041 : // Parse the fixups and use them to create references.
1042 E : VLOG(1) << "Parsing fixups.";
1043 E : if (!CreateReferencesFromFixups(dia_session.get()))
1044 i : return false;
1045 :
1046 : // Annotate the block-graph with symbol information.
1047 E : VLOG(1) << "Parsing symbols.";
1048 E : if (!ProcessSymbols(global.get()))
1049 i : return false;
1050 :
1051 : // Now, find and label any padding blocks.
1052 E : VLOG(1) << "Labeling padding blocks.";
1053 E : if (!FindPaddingBlocks(image_layout_))
1054 i : return false;
1055 :
1056 : // Set the alignment on code blocks with jump tables. This ensures that the
1057 : // jump tables remain aligned post-transform.
1058 E : VLOG(1) << "Calculating code block alignments.";
1059 E : if (!AlignCodeBlocks(image_layout_))
1060 i : return false;
1061 :
1062 : // Set the alignment of data blocks. This is not precise in that it simply
1063 : // guesses the alignment based on the address of the block. Some instructions
1064 : // have alignment requirements on their data but unfortunately the PDB does
1065 : // not contain explicit alignment information.
1066 E : VLOG(1) << "Guessing data block alignments.";
1067 E : GuessDataBlockAlignments(image_file_, image_layout_);
1068 :
1069 E : return true;
1070 E : }
1071 :
1072 : bool Decomposer::CreatePEImageBlocksAndReferences(
1073 E : IntermediateReferences* references) {
1074 E : DCHECK_NE(reinterpret_cast<IntermediateReferences*>(NULL), references);
1075 :
1076 : PEFileParser::AddReferenceCallback add_reference(
1077 E : base::Bind(&AddIntermediateReference, base::Unretained(references)));
1078 E : PEFileParser parser(image_file_, image_, add_reference);
1079 E : PEFileParser::PEHeader header;
1080 E : if (!parser.ParseImage(&header)) {
1081 i : LOG(ERROR) << "Unable to parse PE image.";
1082 i : return false;
1083 : }
1084 :
1085 E : return true;
1086 E : }
1087 :
1088 E : bool Decomposer::CreateBlocksFromCoffGroups() {
1089 E : pdb::PdbFile pdb_file;
1090 E : pdb::PdbReader pdb_reader;
1091 E : if (!pdb_reader.Read(pdb_path_, &pdb_file)) {
1092 i : LOG(ERROR) << "Failed to load PDB: " << pdb_path_.value();
1093 i : return false;
1094 : }
1095 :
1096 E : scoped_refptr<pdb::PdbStream> symbols = GetLinkerSymbolStream(pdb_file);
1097 :
1098 : // Process the symbols in the linker module symbol stream.
1099 E : VisitLinkerSymbolContext context;
1100 : pdb::VisitSymbolsCallback callback = base::Bind(
1101 : &Decomposer::VisitLinkerSymbol,
1102 : base::Unretained(this),
1103 E : base::Unretained(&context));
1104 E : if (!pdb::VisitSymbols(callback, symbols->length(), true, symbols.get()))
1105 i : return false;
1106 :
1107 : // Bail if we did not encounter a closing bracketing symbol where one was
1108 : // expected.
1109 E : if (context.current_group_index != -1) {
1110 i : LOG(ERROR) << "Unable to close bracketed COFF group \""
1111 : << context.current_group_prefix << "\".";
1112 i : return false;
1113 : }
1114 :
1115 E : return true;
1116 E : }
1117 :
1118 E : bool Decomposer::CreateBlocksFromSectionContribs(IDiaSession* session) {
1119 E : ScopedComPtr<IDiaEnumSectionContribs> section_contribs;
1120 : SearchResult search_result = FindDiaTable(session,
1121 E : section_contribs.Receive());
1122 E : if (search_result != kSearchSucceeded) {
1123 i : if (search_result == kSearchFailed)
1124 i : LOG(ERROR) << "No section contribution table found.";
1125 i : return false;
1126 : }
1127 :
1128 E : size_t rsrc_id = image_file_.GetSectionIndex(kResourceSectionName);
1129 :
1130 E : LONG count = 0;
1131 E : if (section_contribs->get_Count(&count) != S_OK) {
1132 i : LOG(ERROR) << "Failed to get section contributions enumeration length.";
1133 i : return false;
1134 : }
1135 :
1136 E : for (LONG visited = 0; visited < count; ++visited) {
1137 E : ScopedComPtr<IDiaSectionContrib> section_contrib;
1138 E : ULONG fetched = 0;
1139 E : HRESULT hr = section_contribs->Next(1, section_contrib.Receive(), &fetched);
1140 : // The standard way to end an enumeration (according to the docs) is by
1141 : // returning S_FALSE and setting fetched to 0. We don't actually see this,
1142 : // but it wouldn't be an error if we did.
1143 E : if (hr == S_FALSE && fetched == 0)
1144 i : break;
1145 E : if (hr != S_OK) {
1146 i : LOG(ERROR) << "Failed to get DIA section contribution: "
1147 : << common::LogHr(hr) << ".";
1148 i : return false;
1149 : }
1150 : // We actually end up seeing S_OK and fetched == 0 when the enumeration
1151 : // terminates, which goes against the publishes documentations.
1152 E : if (fetched == 0)
1153 i : break;
1154 :
1155 E : DWORD rva = 0;
1156 E : DWORD length = 0;
1157 E : DWORD section_id = 0;
1158 E : BOOL code = FALSE;
1159 E : ScopedComPtr<IDiaSymbol> compiland;
1160 E : ScopedBstr bstr_compiland_name;
1161 : if ((hr = section_contrib->get_relativeVirtualAddress(&rva)) != S_OK ||
1162 : (hr = section_contrib->get_length(&length)) != S_OK ||
1163 : (hr = section_contrib->get_addressSection(§ion_id)) != S_OK ||
1164 : (hr = section_contrib->get_code(&code)) != S_OK ||
1165 : (hr = section_contrib->get_compiland(compiland.Receive())) != S_OK ||
1166 E : (hr = compiland->get_name(bstr_compiland_name.Receive())) != S_OK) {
1167 i : LOG(ERROR) << "Failed to get section contribution properties: "
1168 : << common::LogHr(hr) << ".";
1169 i : return false;
1170 : }
1171 :
1172 : // Determine if this function was built by a supported compiler.
1173 : bool is_built_by_supported_compiler =
1174 E : IsBuiltBySupportedCompiler(compiland.get());
1175 :
1176 : // DIA numbers sections from 1 to n, while we do 0 to n - 1.
1177 E : DCHECK_LT(0u, section_id);
1178 E : --section_id;
1179 :
1180 : // We don't parse the resource section, as it is parsed by the PEFileParser.
1181 E : if (section_id == rsrc_id)
1182 E : continue;
1183 :
1184 E : std::string compiland_name;
1185 : if (!base::WideToUTF8(bstr_compiland_name, bstr_compiland_name.Length(),
1186 E : &compiland_name)) {
1187 i : LOG(ERROR) << "Failed to convert compiland name to UTF8.";
1188 i : return false;
1189 : }
1190 :
1191 : // Give a name to the block based on the basename of the object file. This
1192 : // will eventually be replaced by the full symbol name, if one exists for
1193 : // the block.
1194 E : size_t last_component = compiland_name.find_last_of('\\');
1195 E : size_t extension = compiland_name.find_last_of('.');
1196 E : if (last_component == std::string::npos) {
1197 E : last_component = 0;
1198 E : } else {
1199 : // We don't want to include the last slash.
1200 E : ++last_component;
1201 : }
1202 E : if (extension < last_component)
1203 i : extension = compiland_name.size();
1204 : std::string name = compiland_name.substr(last_component,
1205 E : extension - last_component);
1206 :
1207 : // TODO(chrisha): We see special section contributions with the name
1208 : // "* CIL *". These are concatenations of data symbols and can very
1209 : // likely be chunked using symbols directly. A cursory visual inspection
1210 : // of symbol names hints that these might be related to WPO.
1211 :
1212 : // Create the block.
1213 : BlockType block_type =
1214 E : code ? BlockGraph::CODE_BLOCK : BlockGraph::DATA_BLOCK;
1215 : Block* block = CreateBlockOrFindCoveringPeBlock(
1216 E : block_type, RelativeAddress(rva), length, name);
1217 E : if (block == NULL) {
1218 i : LOG(ERROR) << "Unable to create block for compiland \""
1219 : << compiland_name << "\".";
1220 i : return false;
1221 : }
1222 :
1223 : // Set the block compiland name.
1224 E : block->set_compiland_name(compiland_name);
1225 :
1226 : // Set the block attributes.
1227 E : block->set_attribute(BlockGraph::SECTION_CONTRIB);
1228 E : if (!is_built_by_supported_compiler)
1229 E : block->set_attribute(BlockGraph::BUILT_BY_UNSUPPORTED_COMPILER);
1230 E : }
1231 :
1232 E : return true;
1233 E : }
1234 :
1235 E : bool Decomposer::FindColdBlocksFromCompilands(IDiaSession* session) {
1236 : // Detect hot/cold code separation. Some blocks are outside the function
1237 : // address range and must be handled as separate blocks. When building
1238 : // with PGO, the compiler can split functions into "hot" and "cold" blocks,
1239 : // and move the "cold" blocks out to separate pages, so the function can be
1240 : // noncontiguous.
1241 E : ScopedComPtr<IDiaSymbol> global;
1242 E : if (session->get_globalScope(global.Receive()) != S_OK) {
1243 i : LOG(ERROR) << "Cannot get global symbol.";
1244 i : return false;
1245 : }
1246 :
1247 : // Find compilands within the global scope.
1248 E : ScopedComPtr<IDiaEnumSymbols> compilands;
1249 : HRESULT status =
1250 E : global->findChildren(SymTagCompiland, NULL, 0, compilands.Receive());
1251 E : if (status != S_OK) {
1252 i : LOG(ERROR) << "Finding compilands failed on the global symbol: "
1253 : << common::LogHr(status) << ".";
1254 i : return false;
1255 : }
1256 :
1257 : // For each compiland, process its lexical blocks.
1258 E : while (true) {
1259 E : ULONG count = 0;
1260 E : ScopedComPtr<IDiaSymbol> compiland;
1261 : if (compilands->Next(1, compiland.Receive(), &count) != S_OK ||
1262 E : count != 1) {
1263 E : break;
1264 : }
1265 :
1266 E : ScopedComPtr<IDiaEnumSymbols> compiland_blocks;
1267 : status = compiland->findChildren(SymTagBlock,
1268 : NULL,
1269 : 0,
1270 E : compiland_blocks.Receive());
1271 E : if (status != S_OK) {
1272 i : LOG(ERROR) << "Finding blocks failed on compiland: "
1273 : << common::LogHr(status) << ".";
1274 i : return false;
1275 : }
1276 :
1277 E : LONG blocks_count = 0;
1278 E : if (compiland_blocks->get_Count(&blocks_count) != S_OK) {
1279 i : LOG(ERROR) << "Failed to get compiland blocks enumeration length.";
1280 i : return false;
1281 : }
1282 :
1283 E : for (LONG block_index = 0; block_index < blocks_count; ++block_index) {
1284 E : ScopedComPtr<IDiaSymbol> compiland_block;
1285 E : ULONG fetched = 0;
1286 :
1287 E : status = compiland_blocks->Next(1, compiland_block.Receive(), &fetched);
1288 E : if (status == S_FALSE && fetched == 0)
1289 i : break;
1290 E : if (status != S_OK) {
1291 i : LOG(ERROR) << "Failed to get function block: "
1292 : << common::LogHr(status) << ".";
1293 i : return false;
1294 : }
1295 E : if (fetched == 0)
1296 i : break;
1297 :
1298 E : ScopedComPtr<IDiaSymbol> parent;
1299 E : DWORD parent_tag = 0;
1300 : if (compiland_block->get_lexicalParent(parent.Receive()) != S_OK ||
1301 E : parent->get_symTag(&parent_tag) != S_OK) {
1302 i : LOG(ERROR) << "Cannot retrieve block parent.";
1303 i : return false;
1304 : }
1305 :
1306 : // Only consider function block.
1307 E : if (parent_tag != SymTagFunction)
1308 i : continue;
1309 :
1310 : // Get relative adresses.
1311 : DWORD func_rva, block_rva;
1312 : ULONGLONG func_length;
1313 : if (compiland_block->get_relativeVirtualAddress(&block_rva) != S_OK ||
1314 : parent->get_relativeVirtualAddress(&func_rva) != S_OK ||
1315 E : parent->get_length(&func_length) != S_OK) {
1316 i : LOG(ERROR) << "Cannot retrieve parent address range.";
1317 i : return false;
1318 : }
1319 :
1320 : // Retrieve the function block.
1321 E : Block* func_block = image_->GetBlockByAddress(RelativeAddress(func_rva));
1322 E : if (func_block == NULL) {
1323 i : LOG(ERROR) << "Cannot retrieve parent block.";
1324 i : return false;
1325 : }
1326 :
1327 : // Skip blocks within the range of its parent.
1328 E : if (block_rva >= func_rva && block_rva <= func_rva + func_length)
1329 i : continue;
1330 :
1331 : // A cold block is detected and needs special handling.
1332 E : Block* cold_block = image_->GetBlockByAddress(RelativeAddress(block_rva));
1333 E : if (cold_block == NULL) {
1334 i : LOG(ERROR) << "Cannot retrieve parent block.";
1335 i : return false;
1336 : }
1337 :
1338 E : RelativeAddress cold_block_addr;
1339 E : if (!image_->GetAddressOf(cold_block, &cold_block_addr)) {
1340 i : LOG(ERROR) << "Cannot retrieve cold block address.";
1341 i : return false;
1342 : }
1343 :
1344 : // Add cold_block as a child of the function block.
1345 E : cold_blocks_[func_block][cold_block_addr] = cold_block;
1346 :
1347 : // Set the parent relation for blocks belonging to the function block.
1348 E : cold_blocks_parent_[func_block] = func_block;
1349 E : cold_blocks_parent_[cold_block] = func_block;
1350 E : }
1351 E : }
1352 :
1353 E : return true;
1354 E : }
1355 :
1356 E : bool Decomposer::CreateGapBlocks() {
1357 E : size_t num_sections = image_file_.nt_headers()->FileHeader.NumberOfSections;
1358 :
1359 : // Iterate through all the image sections.
1360 E : for (size_t i = 0; i < num_sections; ++i) {
1361 E : const IMAGE_SECTION_HEADER* header = image_file_.section_header(i);
1362 E : DCHECK_NE(reinterpret_cast<IMAGE_SECTION_HEADER*>(NULL), header);
1363 :
1364 E : BlockType type = BlockGraph::CODE_BLOCK;
1365 E : const char* section_type = NULL;
1366 E : switch (GetSectionType(*header)) {
1367 : case kSectionCode:
1368 E : type = BlockGraph::CODE_BLOCK;
1369 E : section_type = "code";
1370 E : break;
1371 :
1372 : case kSectionData:
1373 E : type = BlockGraph::DATA_BLOCK;
1374 E : section_type = "data";
1375 E : break;
1376 :
1377 : default:
1378 i : continue;
1379 : }
1380 :
1381 E : if (!CreateSectionGapBlocks(header, type)) {
1382 i : LOG(ERROR) << "Unable to create gap blocks for " << section_type
1383 : << " section \"" << header->Name << "\".";
1384 i : return false;
1385 : }
1386 E : }
1387 :
1388 E : return true;
1389 E : }
1390 :
1391 : bool Decomposer::FinalizeIntermediateReferences(
1392 E : const IntermediateReferences& references) {
1393 E : for (size_t i = 0; i < references.size(); ++i) {
1394 : // This logs verbosely for us.
1395 : if (!CreateReference(references[i].src_addr,
1396 : references[i].size,
1397 : references[i].type,
1398 : references[i].dst_addr,
1399 : references[i].dst_addr,
1400 E : image_)) {
1401 i : return false;
1402 : }
1403 E : }
1404 E : return true;
1405 E : }
1406 :
1407 E : bool Decomposer::CreateReferencesFromFixups(IDiaSession* session) {
1408 E : DCHECK_NE(reinterpret_cast<IDiaSession*>(NULL), session);
1409 :
1410 E : PEFile::RelocSet reloc_set;
1411 E : if (!image_file_.DecodeRelocs(&reloc_set))
1412 i : return false;
1413 :
1414 E : OMAPs omap_from;
1415 E : PdbFixups fixups;
1416 E : if (!LoadDebugStreams(session, &fixups, &omap_from))
1417 i : return false;
1418 :
1419 : // While creating references from the fixups this removes the
1420 : // corresponding reference data from the relocs. We use this as a kind of
1421 : // double-entry bookkeeping to ensure all is well and right in the world.
1422 : if (!CreateReferencesFromFixupsImpl(image_file_, fixups, omap_from,
1423 E : &reloc_set, image_)) {
1424 i : return false;
1425 : }
1426 :
1427 E : if (!reloc_set.empty()) {
1428 i : LOG(ERROR) << "Found reloc entries without matching FIXUP entries.";
1429 i : return false;
1430 : }
1431 :
1432 E : return true;
1433 E : }
1434 :
1435 E : bool Decomposer::ProcessSymbols(IDiaSymbol* root) {
1436 E : DCHECK_NE(reinterpret_cast<IDiaSymbol*>(NULL), root);
1437 :
1438 : DiaBrowser::MatchCallback on_push_function_or_thunk_symbol(
1439 : base::Bind(&Decomposer::OnPushFunctionOrThunkSymbol,
1440 E : base::Unretained(this)));
1441 : DiaBrowser::MatchCallback on_pop_function_or_thunk_symbol(
1442 : base::Bind(&Decomposer::OnPopFunctionOrThunkSymbol,
1443 E : base::Unretained(this)));
1444 : DiaBrowser::MatchCallback on_function_child_symbol(
1445 : base::Bind(&Decomposer::OnFunctionChildSymbol,
1446 E : base::Unretained(this)));
1447 : DiaBrowser::MatchCallback on_data_symbol(
1448 E : base::Bind(&Decomposer::OnDataSymbol, base::Unretained(this)));
1449 : DiaBrowser::MatchCallback on_public_symbol(
1450 E : base::Bind(&Decomposer::OnPublicSymbol, base::Unretained(this)));
1451 : DiaBrowser::MatchCallback on_label_symbol(
1452 E : base::Bind(&Decomposer::OnLabelSymbol, base::Unretained(this)));
1453 :
1454 E : DiaBrowser dia_browser;
1455 :
1456 : // Find thunks.
1457 : dia_browser.AddPattern(Seq(Opt(SymTagCompiland), SymTagThunk),
1458 : on_push_function_or_thunk_symbol,
1459 E : on_pop_function_or_thunk_symbol);
1460 :
1461 : // Find functions and all data, labels, callsites, debug start/end and block
1462 : // symbols below them. This is done in one single pattern so that the
1463 : // function pushes/pops happen in the right order.
1464 : dia_browser.AddPattern(
1465 : Seq(Opt(SymTagCompiland),
1466 : Callback(Or(SymTagFunction, SymTagThunk),
1467 : on_push_function_or_thunk_symbol,
1468 : on_pop_function_or_thunk_symbol),
1469 : Star(SymTagBlock),
1470 : Or(SymTagData,
1471 : SymTagLabel,
1472 : SymTagBlock,
1473 : SymTagFuncDebugStart,
1474 : SymTagFuncDebugEnd,
1475 : SymTagCallSite)),
1476 E : on_function_child_symbol);
1477 :
1478 : // Global data and code label symbols.
1479 : dia_browser.AddPattern(Seq(Opt(SymTagCompiland), SymTagLabel),
1480 E : on_label_symbol);
1481 : dia_browser.AddPattern(Seq(Opt(SymTagCompiland), SymTagData),
1482 E : on_data_symbol);
1483 :
1484 : // Public symbols. These provide decorated names without any type info, but
1485 : // are useful for debugging.
1486 E : dia_browser.AddPattern(SymTagPublicSymbol, on_public_symbol);
1487 :
1488 E : return dia_browser.Browse(root);
1489 E : }
1490 :
1491 : bool Decomposer::VisitLinkerSymbol(VisitLinkerSymbolContext* context,
1492 : uint16 symbol_length,
1493 : uint16 symbol_type,
1494 E : pdb::PdbStream* stream) {
1495 E : DCHECK_NE(reinterpret_cast<VisitLinkerSymbolContext*>(NULL), context);
1496 E : DCHECK_NE(reinterpret_cast<pdb::PdbStream*>(NULL), stream);
1497 :
1498 E : if (symbol_type != cci::S_COFFGROUP)
1499 E : return true;
1500 :
1501 E : std::vector<uint8> buffer;
1502 : const cci::CoffGroupSym* coffgroup =
1503 E : ParseSymbol<cci::CoffGroupSym>(symbol_length, stream, &buffer);
1504 E : if (coffgroup == NULL)
1505 i : return false;
1506 :
1507 : // The PDB numbers sections starting at index 1 but we use index 0.
1508 : RelativeAddress rva(image_layout_->sections[coffgroup->seg - 1].addr +
1509 E : coffgroup->off);
1510 :
1511 : // We are looking for an opening symbol.
1512 E : if (context->current_group_index == -1) {
1513 E : for (size_t i = 0; i < context->bracketing_groups.size(); ++i) {
1514 E : std::string prefix;
1515 E : if (context->bracketing_groups[i].FullMatch(coffgroup->name, &prefix)) {
1516 E : context->current_group_index = i;
1517 E : context->current_group_prefix = prefix;
1518 E : context->current_group_start = rva;
1519 E : return true;
1520 : }
1521 E : }
1522 :
1523 : // No opening symbol was encountered. We can safely ignore this
1524 : // COFF group symbol.
1525 E : return true;
1526 : }
1527 :
1528 : // If we get here we've found an opening symbol and we're looking for the
1529 : // matching closing symbol.
1530 E : std::string prefix;
1531 : if (!context->bracketing_groups[context->current_group_index].FullMatch(
1532 E : coffgroup->name, &prefix)) {
1533 E : return true;
1534 : }
1535 :
1536 E : if (prefix != context->current_group_prefix) {
1537 : // We see another symbol open/close while already in an opened symbol.
1538 : // This indicates nested bracketing information, which we've never seen
1539 : // before.
1540 i : LOG(ERROR) << "Encountered nested bracket symbol \"" << prefix
1541 : << "\" while in \"" << context->current_group_prefix << "\".";
1542 i : return false;
1543 : }
1544 :
1545 E : RelativeAddress end = rva + coffgroup->cb;
1546 E : DCHECK_LE(context->current_group_start, end);
1547 :
1548 : // If the COFF group is not empty, then create a block corresponding to it.
1549 E : if (context->current_group_start != end) {
1550 : // Create a block for this bracketed COFF group.
1551 : Block* block = CreateBlock(
1552 : BlockGraph::DATA_BLOCK,
1553 : context->current_group_start,
1554 : end - context->current_group_start,
1555 E : base::StringPrintf("Bracketed COFF group: %s", prefix.c_str()));
1556 E : if (block == NULL) {
1557 i : LOG(ERROR) << "Failed to create bracketed COFF group \""
1558 : << prefix << "\".";
1559 i : return false;
1560 : }
1561 E : block->set_attribute(BlockGraph::COFF_GROUP);
1562 : }
1563 :
1564 : // Indicate that this block is closed and we're looking for another opening
1565 : // bracket symbol.
1566 E : context->current_group_index = -1;
1567 E : context->current_group_prefix.clear();
1568 E : context->current_group_start = RelativeAddress(0);
1569 :
1570 E : return true;
1571 E : }
1572 :
1573 : DiaBrowser::BrowserDirective Decomposer::OnPushFunctionOrThunkSymbol(
1574 : const DiaBrowser& dia_browser,
1575 : const DiaBrowser::SymTagVector& sym_tags,
1576 E : const DiaBrowser::SymbolPtrVector& symbols) {
1577 E : DCHECK(!symbols.empty());
1578 E : DCHECK_EQ(sym_tags.size(), symbols.size());
1579 E : DiaBrowser::SymbolPtr symbol = symbols.back();
1580 :
1581 E : DCHECK_EQ(reinterpret_cast<Block*>(NULL), current_block_);
1582 E : DCHECK_EQ(current_address_, RelativeAddress(0));
1583 E : DCHECK_EQ(0u, current_scope_count_);
1584 :
1585 E : HRESULT hr = E_FAIL;
1586 E : DWORD location_type = LocIsNull;
1587 E : DWORD rva = 0;
1588 E : ULONGLONG length = 0;
1589 E : ScopedBstr name_bstr;
1590 : if (FAILED(hr = symbol->get_locationType(&location_type)) ||
1591 : FAILED(hr = symbol->get_relativeVirtualAddress(&rva)) ||
1592 : FAILED(hr = symbol->get_length(&length)) ||
1593 E : FAILED(hr = symbol->get_name(name_bstr.Receive()))) {
1594 i : LOG(ERROR) << "Failed to get function/thunk properties: "
1595 : << common::LogHr(hr) << ".";
1596 i : return DiaBrowser::kBrowserAbort;
1597 : }
1598 :
1599 : // We only care about functions with static storage. We can stop looking at
1600 : // things below this node, as we won't be able to resolve them either.
1601 E : if (location_type != LocIsStatic)
1602 i : return DiaBrowser::kBrowserTerminatePath;
1603 :
1604 E : RelativeAddress addr(rva);
1605 E : Block* block = image_->GetBlockByAddress(addr);
1606 E : CHECK(block != NULL);
1607 E : RelativeAddress block_addr;
1608 E : CHECK(image_->GetAddressOf(block, &block_addr));
1609 E : DCHECK(InRange(addr, block_addr, block->size()));
1610 :
1611 E : std::string name;
1612 E : if (!base::WideToUTF8(name_bstr, name_bstr.Length(), &name)) {
1613 i : LOG(ERROR) << "Failed to convert function/thunk name to UTF8.";
1614 i : return DiaBrowser::kBrowserAbort;
1615 : }
1616 :
1617 : // We know the function starts in this block but we need to make sure its
1618 : // end does not extend past the end of the block.
1619 E : if (addr + length > block_addr + block->size()) {
1620 i : LOG(ERROR) << "Got function/thunk \"" << name << "\" that is not contained "
1621 : << "by section contribution \"" << block->name() << "\".";
1622 i : return DiaBrowser::kBrowserAbort;
1623 : }
1624 :
1625 E : Offset offset = addr - block_addr;
1626 E : if (!AddLabelToBlock(offset, name, BlockGraph::CODE_LABEL, block))
1627 i : return DiaBrowser::kBrowserAbort;
1628 :
1629 : // Keep track of the generated block. We will use this when parsing symbols
1630 : // that belong to this function. This prevents us from having to do repeated
1631 : // lookups and also allows us to associate labels outside of the block to the
1632 : // correct block.
1633 E : current_block_ = block;
1634 E : current_address_ = block_addr;
1635 :
1636 : // Certain properties are not defined on all blocks, so the following calls
1637 : // may return S_FALSE.
1638 E : BOOL no_return = FALSE;
1639 E : if (symbol->get_noReturn(&no_return) != S_OK)
1640 E : no_return = FALSE;
1641 :
1642 E : BOOL has_inl_asm = FALSE;
1643 E : if (symbol->get_hasInlAsm(&has_inl_asm) != S_OK)
1644 E : has_inl_asm = FALSE;
1645 :
1646 E : BOOL has_eh = FALSE;
1647 E : if (symbol->get_hasEH(&has_eh) != S_OK)
1648 E : has_eh = FALSE;
1649 :
1650 E : BOOL has_seh = FALSE;
1651 E : if (symbol->get_hasSEH(&has_seh) != S_OK)
1652 E : has_seh = FALSE;
1653 :
1654 : // Set the block attributes.
1655 E : if (no_return == TRUE)
1656 E : block->set_attribute(BlockGraph::NON_RETURN_FUNCTION);
1657 E : if (has_inl_asm == TRUE)
1658 E : block->set_attribute(BlockGraph::HAS_INLINE_ASSEMBLY);
1659 E : if (has_eh || has_seh)
1660 E : block->set_attribute(BlockGraph::HAS_EXCEPTION_HANDLING);
1661 E : if (IsSymTag(symbol.get(), SymTagThunk))
1662 E : block->set_attribute(BlockGraph::THUNK);
1663 :
1664 E : return DiaBrowser::kBrowserContinue;
1665 E : }
1666 :
1667 : DiaBrowser::BrowserDirective Decomposer::OnPopFunctionOrThunkSymbol(
1668 : const DiaBrowser& dia_browser,
1669 : const DiaBrowser::SymTagVector& sym_tags,
1670 E : const DiaBrowser::SymbolPtrVector& symbols) {
1671 : // Simply clean up the current function block and address.
1672 E : current_block_ = NULL;
1673 E : current_address_ = RelativeAddress(0);
1674 E : current_scope_count_ = 0;
1675 E : return DiaBrowser::kBrowserContinue;
1676 E : }
1677 :
1678 : DiaBrowser::BrowserDirective Decomposer::OnFunctionChildSymbol(
1679 : const DiaBrowser& dia_browser,
1680 : const DiaBrowser::SymTagVector& sym_tags,
1681 E : const DiaBrowser::SymbolPtrVector& symbols) {
1682 E : DCHECK(!symbols.empty());
1683 E : DCHECK_EQ(sym_tags.size(), symbols.size());
1684 :
1685 : // This can only be called from the context of a function, so we expect the
1686 : // parent function block to be set and remembered.
1687 E : DCHECK_NE(reinterpret_cast<Block*>(NULL), current_block_);
1688 :
1689 : // The set of sym tags here should match the pattern used in the DiaBrowser
1690 : // instance set up in ProcessSymbols.
1691 E : switch (sym_tags.back()) {
1692 : case SymTagData:
1693 E : return OnDataSymbol(dia_browser, sym_tags, symbols);
1694 :
1695 : case SymTagLabel:
1696 E : return OnLabelSymbol(dia_browser, sym_tags, symbols);
1697 :
1698 : case SymTagBlock:
1699 : case SymTagFuncDebugStart:
1700 : case SymTagFuncDebugEnd:
1701 E : return OnScopeSymbol(sym_tags.back(), symbols.back());
1702 :
1703 : case SymTagCallSite:
1704 E : return OnCallSiteSymbol(symbols.back());
1705 :
1706 : default:
1707 : break;
1708 : }
1709 :
1710 i : LOG(ERROR) << "Unhandled function child symbol: " << sym_tags.back() << ".";
1711 i : return DiaBrowser::kBrowserAbort;
1712 E : }
1713 :
1714 : DiaBrowser::BrowserDirective Decomposer::OnDataSymbol(
1715 : const DiaBrowser& dia_browser,
1716 : const DiaBrowser::SymTagVector& sym_tags,
1717 E : const DiaBrowser::SymbolPtrVector& symbols) {
1718 E : DCHECK(!symbols.empty());
1719 E : DCHECK_EQ(sym_tags.size(), symbols.size());
1720 E : DiaBrowser::SymbolPtr symbol = symbols.back();
1721 :
1722 E : HRESULT hr = E_FAIL;
1723 E : DWORD location_type = LocIsNull;
1724 E : DWORD rva = 0;
1725 E : ScopedBstr name_bstr;
1726 : if (FAILED(hr = symbol->get_locationType(&location_type)) ||
1727 : FAILED(hr = symbol->get_relativeVirtualAddress(&rva)) ||
1728 E : FAILED(hr = symbol->get_name(name_bstr.Receive()))) {
1729 i : LOG(ERROR) << "Failed to get data properties: " << common::LogHr(hr) << ".";
1730 i : return DiaBrowser::kBrowserAbort;
1731 : }
1732 :
1733 : // Symbols with an address of zero are essentially invalid. They appear to
1734 : // have been optimized away by the compiler, but they are still reported.
1735 E : if (rva == 0)
1736 E : return DiaBrowser::kBrowserTerminatePath;
1737 :
1738 : // We only care about functions with static storage. We can stop looking at
1739 : // things below this node, as we won't be able to resolve them either.
1740 E : if (location_type != LocIsStatic)
1741 i : return DiaBrowser::kBrowserTerminatePath;
1742 :
1743 : // Get the size of this datum from its type info.
1744 E : size_t length = 0;
1745 E : if (!GetDataSymbolSize(symbol.get(), &length))
1746 i : return DiaBrowser::kBrowserAbort;
1747 :
1748 : // Reuse the parent function block if we can. This acts as small lookup
1749 : // cache.
1750 E : RelativeAddress addr(rva);
1751 E : Block* block = current_block_;
1752 E : RelativeAddress block_addr(current_address_);
1753 E : if (block == NULL || !InRange(addr, block_addr, block->size())) {
1754 E : block = image_->GetBlockByAddress(addr);
1755 E : CHECK(block != NULL);
1756 E : CHECK(image_->GetAddressOf(block, &block_addr));
1757 E : DCHECK(InRange(addr, block_addr, block->size()));
1758 : }
1759 :
1760 E : std::string name;
1761 E : if (!base::WideToUTF8(name_bstr, name_bstr.Length(), &name)) {
1762 i : LOG(ERROR) << "Failed to convert label name to UTF8.";
1763 i : return DiaBrowser::kBrowserAbort;
1764 : }
1765 :
1766 : // Zero-length data symbols mark case/jump tables, or are forward declares.
1767 E : BlockGraph::LabelAttributes attr = BlockGraph::DATA_LABEL;
1768 E : Offset offset = addr - block_addr;
1769 E : if (length == 0) {
1770 : // Jump and case tables come in as data symbols with no name. Jump tables
1771 : // are always an array of pointers, thus they coincide exactly with a
1772 : // reference. Case tables are simple arrays of integer values (themselves
1773 : // indices into a jump table), thus do not coincide with a reference.
1774 E : if (name.empty() && block->type() == BlockGraph::CODE_BLOCK) {
1775 E : if (block->references().find(offset) != block->references().end()) {
1776 E : name = kJumpTable;
1777 E : attr |= BlockGraph::JUMP_TABLE_LABEL;
1778 E : } else {
1779 E : name = kCaseTable;
1780 E : attr |= BlockGraph::CASE_TABLE_LABEL;
1781 : }
1782 E : } else {
1783 : // Zero-length data symbols act as 'forward declares' in some sense. They
1784 : // are always followed by a non-zero length data symbol with the same name
1785 : // and location.
1786 E : return DiaBrowser::kBrowserTerminatePath;
1787 : }
1788 : }
1789 :
1790 : // Verify that the data symbol does not exceed the size of the block.
1791 E : if (addr + length > block_addr + block->size()) {
1792 : // The data symbol can exceed the size of the block in the case of data
1793 : // imports. For some reason the toolchain emits a global data symbol with
1794 : // type information equal to the type of the data *pointed* to by the import
1795 : // entry rather than the type of the entry itself. Thus, if the data type
1796 : // is bigger than the entire IAT this symbol will exceed it. To complicate
1797 : // matters even more, a poorly written module can import its own export in
1798 : // which case a linker generated pseudo-import-entry block will be
1799 : // generated. This won't be part of the IAT, so we can't even filter based
1800 : // on that. Instead, we simply ignore global data symbols that exceed the
1801 : // block size.
1802 E : base::StringPiece spname(name);
1803 E : if (sym_tags.size() == 1 && spname.starts_with("_imp_")) {
1804 E : VLOG(1) << "Encountered an imported data symbol \"" << name << "\" that "
1805 : << "extends past its parent block \"" << block->name() << "\".";
1806 E : } else {
1807 i : LOG(ERROR) << "Received data symbol \"" << name << "\" that extends past "
1808 : << "its parent block \"" << block->name() << "\".";
1809 i : return DiaBrowser::kBrowserAbort;
1810 : }
1811 : }
1812 :
1813 E : if (!AddLabelToBlock(offset, name, attr, block))
1814 i : return DiaBrowser::kBrowserAbort;
1815 :
1816 E : return DiaBrowser::kBrowserContinue;
1817 E : }
1818 :
1819 : DiaBrowser::BrowserDirective Decomposer::OnPublicSymbol(
1820 : const DiaBrowser& dia_browser,
1821 : const DiaBrowser::SymTagVector& sym_tags,
1822 E : const DiaBrowser::SymbolPtrVector& symbols) {
1823 E : DCHECK(!symbols.empty());
1824 E : DCHECK_EQ(sym_tags.size(), symbols.size());
1825 E : DCHECK_EQ(reinterpret_cast<Block*>(NULL), current_block_);
1826 E : DiaBrowser::SymbolPtr symbol = symbols.back();
1827 :
1828 E : HRESULT hr = E_FAIL;
1829 E : DWORD rva = 0;
1830 E : ScopedBstr name_bstr;
1831 : if (FAILED(hr = symbol->get_relativeVirtualAddress(&rva)) ||
1832 E : FAILED(hr = symbol->get_name(name_bstr.Receive()))) {
1833 i : LOG(ERROR) << "Failed to get public symbol properties: "
1834 : << common::LogHr(hr) << ".";
1835 i : return DiaBrowser::kBrowserAbort;
1836 : }
1837 :
1838 E : RelativeAddress addr(rva);
1839 E : Block* block = image_->GetBlockByAddress(addr);
1840 E : CHECK(block != NULL);
1841 E : RelativeAddress block_addr;
1842 E : CHECK(image_->GetAddressOf(block, &block_addr));
1843 E : DCHECK(InRange(addr, block_addr, block->size()));
1844 :
1845 E : std::string name;
1846 E : base::WideToUTF8(name_bstr, name_bstr.Length(), &name);
1847 :
1848 : // Public symbol names are mangled. Remove leading '_' as per
1849 : // http://msdn.microsoft.com/en-us/library/00kh39zz(v=vs.80).aspx
1850 E : if (name[0] == '_')
1851 E : name = name.substr(1);
1852 :
1853 E : Offset offset = addr - block_addr;
1854 E : if (!AddLabelToBlock(offset, name, BlockGraph::PUBLIC_SYMBOL_LABEL, block))
1855 i : return DiaBrowser::kBrowserAbort;
1856 :
1857 E : return DiaBrowser::kBrowserContinue;
1858 E : }
1859 :
1860 : DiaBrowser::BrowserDirective Decomposer::OnLabelSymbol(
1861 : const DiaBrowser& dia_browser,
1862 : const DiaBrowser::SymTagVector& sym_tags,
1863 E : const DiaBrowser::SymbolPtrVector& symbols) {
1864 E : DCHECK(!symbols.empty());
1865 E : DCHECK_EQ(sym_tags.size(), symbols.size());
1866 E : DiaBrowser::SymbolPtr symbol = symbols.back();
1867 :
1868 E : HRESULT hr = E_FAIL;
1869 E : DWORD rva = 0;
1870 E : ScopedBstr name_bstr;
1871 : if (FAILED(hr = symbol->get_relativeVirtualAddress(&rva)) ||
1872 E : FAILED(hr = symbol->get_name(name_bstr.Receive()))) {
1873 i : LOG(ERROR) << "Failed to get label symbol properties: " << common::LogHr(hr)
1874 : << ".";
1875 i : return DiaBrowser::kBrowserAbort;
1876 : }
1877 :
1878 : // If we have a current_block_ the label should lie within its scope.
1879 E : RelativeAddress addr(rva);
1880 E : Block* block = current_block_;
1881 E : RelativeAddress block_addr(current_address_);
1882 E : if (block != NULL) {
1883 : // Try to find the block in the cold blocks. The cold blocks aren't in the
1884 : // same address space as the original function.
1885 E : if (!InRangeIncl(addr, block_addr, block->size())) {
1886 :
1887 : // Determine the function block containing this block.
1888 : ColdBlocksParent::iterator function_block =
1889 E : cold_blocks_parent_.find(block);
1890 E : if (function_block != cold_blocks_parent_.end())
1891 E : block = function_block->second;
1892 :
1893 : // Retrieve the first cold block related to that function before |addr|.
1894 E : ColdBlocksMap::iterator cold_blocks_it = cold_blocks_.find(block);
1895 E : if (cold_blocks_it != cold_blocks_.end()) {
1896 E : ColdBlocks& cold_blocks = cold_blocks_it->second;
1897 E : if (!cold_blocks.empty()) {
1898 : // Find the block containing the address |addr|. When |addr| is not
1899 : // the same as the block address, the iterator points to the next
1900 : // block.
1901 E : ColdBlocks::iterator cold_block_it = cold_blocks.lower_bound(addr);
1902 : if (cold_block_it == cold_blocks.end() ||
1903 E : cold_block_it->second->addr() != addr) {
1904 E : cold_block_it--;
1905 : }
1906 :
1907 : // Check whether the address falls into this cold block.
1908 E : DCHECK(cold_block_it != cold_blocks.end());
1909 E : Block* cold_block = cold_block_it->second;
1910 E : if (InRangeIncl(addr, cold_block->addr(), cold_block->size()))
1911 E : block = cold_block;
1912 : }
1913 : }
1914 :
1915 : // Update the block address according to the cold block found.
1916 E : if (!image_->GetAddressOf(block, &block_addr)) {
1917 i : LOG(ERROR) << "Cannot retrieve cold block address.";
1918 i : return DiaBrowser::kBrowserAbort;
1919 : }
1920 : }
1921 :
1922 E : if (!InRangeIncl(addr, block_addr, block->size())) {
1923 i : LOG(ERROR) << "Label falls outside of current block \""
1924 : << block->name() << "\".";
1925 i : return DiaBrowser::kBrowserAbort;
1926 : }
1927 E : } else {
1928 : // If there is no current block this is a compiland scope label.
1929 E : block = image_->GetBlockByAddress(addr);
1930 E : CHECK(block != NULL);
1931 E : CHECK(image_->GetAddressOf(block, &block_addr));
1932 E : DCHECK(InRange(addr, block_addr, block->size()));
1933 :
1934 : // TODO(chrisha): This label is in compiland scope, so we should be
1935 : // finding the block whose section contribution shares the same
1936 : // compiland.
1937 : }
1938 :
1939 E : std::string name;
1940 E : base::WideToUTF8(name_bstr, name_bstr.Length(), &name);
1941 :
1942 E : Offset offset = addr - block_addr;
1943 E : if (!AddLabelToBlock(offset, name, BlockGraph::CODE_LABEL, block))
1944 i : return DiaBrowser::kBrowserAbort;
1945 :
1946 E : return DiaBrowser::kBrowserContinue;
1947 E : }
1948 :
1949 : DiaBrowser::BrowserDirective Decomposer::OnScopeSymbol(
1950 E : enum SymTagEnum type, DiaBrowser::SymbolPtr symbol) {
1951 : // We should only get here via the successful exploration of a SymTagFunction,
1952 : // so current_block_ should be set.
1953 E : DCHECK_NE(reinterpret_cast<Block*>(NULL), current_block_);
1954 :
1955 E : HRESULT hr = E_FAIL;
1956 E : DWORD rva = 0;
1957 E : if (FAILED(hr = symbol->get_relativeVirtualAddress(&rva))) {
1958 i : LOG(ERROR) << "Failed to get scope symbol properties: " << common::LogHr(hr)
1959 : << ".";
1960 i : return DiaBrowser::kBrowserAbort;
1961 : }
1962 :
1963 : // The label may potentially lay at the first byte past the function.
1964 E : RelativeAddress addr(rva);
1965 E : DCHECK_LE(current_address_, addr);
1966 E : DCHECK_LE(addr, current_address_ + current_block_->size());
1967 :
1968 : // Get the attributes for this label.
1969 E : BlockGraph::LabelAttributes attr = 0;
1970 E : std::string name;
1971 E : CHECK(ScopeSymTagToLabelProperties(type, current_scope_count_, &attr, &name));
1972 :
1973 : // Add the label.
1974 E : Offset offset = addr - current_address_;
1975 E : if (!AddLabelToBlock(offset, name, attr, current_block_))
1976 i : return DiaBrowser::kBrowserAbort;
1977 :
1978 : // If this is a scope we extract the length and explicitly add a corresponding
1979 : // end label.
1980 E : if (type == SymTagBlock) {
1981 E : ULONGLONG length = 0;
1982 E : if (symbol->get_length(&length) != S_OK) {
1983 i : LOG(ERROR) << "Failed to extract code scope length for block \""
1984 : << current_block_->name() << "\".";
1985 i : return DiaBrowser::kBrowserAbort;
1986 : }
1987 E : DCHECK_LE(static_cast<size_t>(offset + length), current_block_->size());
1988 E : name = base::StringPrintf("<scope-end-%d>", current_scope_count_);
1989 E : ++current_scope_count_;
1990 : if (!AddLabelToBlock(offset + length, name,
1991 E : BlockGraph::SCOPE_END_LABEL, current_block_)) {
1992 i : return DiaBrowser::kBrowserAbort;
1993 : }
1994 : }
1995 :
1996 E : return DiaBrowser::kBrowserContinue;
1997 E : }
1998 :
1999 : DiaBrowser::BrowserDirective Decomposer::OnCallSiteSymbol(
2000 E : DiaBrowser::SymbolPtr symbol) {
2001 : // We should only get here via the successful exploration of a SymTagFunction,
2002 : // so current_block_ should be set.
2003 E : DCHECK_NE(reinterpret_cast<Block*>(NULL), current_block_);
2004 :
2005 E : HRESULT hr = E_FAIL;
2006 E : DWORD rva = 0;
2007 E : if (FAILED(hr = symbol->get_relativeVirtualAddress(&rva))) {
2008 i : LOG(ERROR) << "Failed to get call site symbol properties: "
2009 : << common::LogHr(hr) << ".";
2010 i : return DiaBrowser::kBrowserAbort;
2011 : }
2012 :
2013 E : RelativeAddress addr(rva);
2014 E : if (!InRange(addr, current_address_, current_block_->size())) {
2015 : // We see this happen under some build configurations (notably debug
2016 : // component builds of Chrome). As long as the label falls entirely
2017 : // outside of the block it is harmless and can be safely ignored.
2018 E : VLOG(1) << "Call site falls outside of current block \""
2019 : << current_block_->name() << "\".";
2020 E : return DiaBrowser::kBrowserContinue;
2021 : }
2022 :
2023 E : Offset offset = addr - current_address_;
2024 : if (!AddLabelToBlock(offset, "<call-site>", BlockGraph::CALL_SITE_LABEL,
2025 E : current_block_)) {
2026 i : return DiaBrowser::kBrowserAbort;
2027 : }
2028 :
2029 E : return DiaBrowser::kBrowserContinue;
2030 E : }
2031 :
2032 : Block* Decomposer::CreateBlock(BlockType type,
2033 : RelativeAddress address,
2034 : BlockGraph::Size size,
2035 E : const base::StringPiece& name) {
2036 E : Block* block = image_->AddBlock(type, address, size, name);
2037 E : if (block == NULL) {
2038 i : LOG(ERROR) << "Unable to add block \"" << name.as_string() << "\" at "
2039 : << address << " with size " << size << ".";
2040 i : return NULL;
2041 : }
2042 :
2043 : // Mark the source range from whence this block originates. This is assuming
2044 : // an untransformed image. To handle transformed images we'd have to use the
2045 : // OMAP information to do this properly.
2046 : bool pushed = block->source_ranges().Push(
2047 : Block::DataRange(0, size),
2048 E : Block::SourceRange(address, size));
2049 E : DCHECK(pushed);
2050 :
2051 E : BlockGraph::SectionId section = image_file_.GetSectionIndex(address, size);
2052 E : if (section == BlockGraph::kInvalidSectionId) {
2053 i : LOG(ERROR) << "Block \"" << name.as_string() << "\" at " << address
2054 : << " with size " << size << " lies outside of all sections.";
2055 i : return NULL;
2056 : }
2057 E : block->set_section(section);
2058 :
2059 E : const uint8* data = image_file_.GetImageData(address, size);
2060 E : if (data != NULL)
2061 E : block->SetData(data, size);
2062 :
2063 E : return block;
2064 E : }
2065 :
2066 : Block* Decomposer::CreateBlockOrFindCoveringPeBlock(
2067 : BlockType type,
2068 : RelativeAddress addr,
2069 : BlockGraph::Size size,
2070 E : const base::StringPiece& name) {
2071 E : Block* block = image_->GetBlockByAddress(addr);
2072 E : if (block != NULL) {
2073 E : RelativeAddress block_addr;
2074 E : CHECK(image_->GetAddressOf(block, &block_addr));
2075 :
2076 : // Allow PE-parsed blocks to be grown to reflect reality. For example,
2077 : // in VS2013 the linker makes space for 2 debug directories rather than
2078 : // just one, and the symbols reflect this. We parse the debug directory
2079 : // with the size indicated in the PE header, which conflicts with that
2080 : // indicated by the section contributions.
2081 E : if (name == "* Linker *" && block_addr == addr && size > block->size()) {
2082 E : if (!image_->ResizeBlock(block, size)) {
2083 i : LOG(ERROR) << "Failed to extend PE-parsed "
2084 : << BlockInfo(block, block_addr) << " with linker "
2085 : << "section contribution of size " << size << ".";
2086 :
2087 : // Get the conflicting block and output additional information about
2088 : // it.
2089 : Block* conflict = image_->GetFirstIntersectingBlock(
2090 i : block_addr + block->size(), size - block->size());
2091 i : if (conflict) {
2092 i : RelativeAddress conflict_addr;
2093 i : CHECK(image_->GetAddressOf(conflict, &conflict_addr));
2094 i : LOG(ERROR) << "Conflicts with existing "
2095 : << BlockInfo(conflict, conflict_addr) << ".";
2096 : }
2097 :
2098 i : return NULL;
2099 : }
2100 :
2101 : // Update the data in the extended block.
2102 E : const uint8* data = image_file_.GetImageData(addr, size);
2103 E : block->SetData(data, size);
2104 E : return block;
2105 : }
2106 :
2107 : // If this is not a PE parsed or COFF group block that covers us entirely,
2108 : // then this is an error.
2109 : static const BlockGraph::BlockAttributes kCoveringAttributes =
2110 : BlockGraph::PE_PARSED | BlockGraph::COFF_GROUP;
2111 E : RelativeRange existing_block(block_addr, block->size());
2112 : if ((block->attributes() & kCoveringAttributes) == 0 ||
2113 E : !existing_block.Contains(addr, size)) {
2114 i : LOG(ERROR) << "Trying to create block \"" << name.as_string() << "\" at "
2115 : << addr.value() << " with size " << size << " that conflicts "
2116 : << "with existing " << BlockInfo(block, block_addr) << ".";
2117 i : return NULL;
2118 : }
2119 :
2120 E : return block;
2121 : }
2122 E : DCHECK_EQ(reinterpret_cast<Block*>(NULL), block);
2123 :
2124 E : return CreateBlock(type, addr, size, name);
2125 E : }
2126 :
2127 : bool Decomposer::CreateGapBlock(BlockType block_type,
2128 : RelativeAddress address,
2129 E : BlockGraph::Size size) {
2130 : Block* block = CreateBlock(block_type, address, size,
2131 E : base::StringPrintf("Gap Block 0x%08X", address.value()).c_str());
2132 E : if (block == NULL) {
2133 i : LOG(ERROR) << "Unable to create gap block.";
2134 i : return false;
2135 : }
2136 E : block->set_attribute(BlockGraph::GAP_BLOCK);
2137 :
2138 E : return true;
2139 E : }
2140 :
2141 : bool Decomposer::CreateSectionGapBlocks(const IMAGE_SECTION_HEADER* header,
2142 E : BlockType block_type) {
2143 E : RelativeAddress section_begin(header->VirtualAddress);
2144 E : RelativeAddress section_end(section_begin + header->Misc.VirtualSize);
2145 : RelativeAddress image_end(
2146 E : image_file_.nt_headers()->OptionalHeader.SizeOfImage);
2147 :
2148 : // Search for the first and last blocks interesting from the start and end
2149 : // of the section to the end of the image.
2150 : BlockGraph::AddressSpace::RangeMap::const_iterator it(
2151 : image_->address_space_impl().FindFirstIntersection(
2152 : BlockGraph::AddressSpace::Range(section_begin,
2153 E : image_end - section_begin)));
2154 :
2155 : BlockGraph::AddressSpace::RangeMap::const_iterator end =
2156 E : image_->address_space_impl().end();
2157 E : if (section_end < image_end) {
2158 : end = image_->address_space_impl().FindFirstIntersection(
2159 : BlockGraph::AddressSpace::Range(section_end,
2160 E : image_end - section_end));
2161 : }
2162 :
2163 : // The whole section is missing. Cover it with one gap block.
2164 E : if (it == end)
2165 : return CreateGapBlock(
2166 i : block_type, section_begin, section_end - section_begin);
2167 :
2168 : // Create the head gap block if need be.
2169 E : if (section_begin < it->first.start()) {
2170 : if (!CreateGapBlock(
2171 i : block_type, section_begin, it->first.start() - section_begin)) {
2172 i : return false;
2173 : }
2174 : }
2175 :
2176 : // Now iterate the blocks and fill in gaps.
2177 E : for (; it != end; ++it) {
2178 E : const Block* block = it->second;
2179 E : DCHECK_NE(reinterpret_cast<Block*>(NULL), block);
2180 E : RelativeAddress block_end = it->first.start() + block->size();
2181 E : if (block_end >= section_end)
2182 E : break;
2183 :
2184 : // Walk to the next address in turn.
2185 E : BlockGraph::AddressSpace::RangeMap::const_iterator next = it;
2186 E : ++next;
2187 E : if (next == end) {
2188 : // We're at the end of the list. Create the tail gap block.
2189 E : DCHECK_GT(section_end, block_end);
2190 E : if (!CreateGapBlock(block_type, block_end, section_end - block_end))
2191 i : return false;
2192 E : break;
2193 : }
2194 :
2195 : // Create the interstitial gap block.
2196 E : if (block_end < next->first.start()) {
2197 : if (!CreateGapBlock(
2198 E : block_type, block_end, next->first.start() - block_end)) {
2199 i : return false;
2200 : }
2201 : }
2202 E : }
2203 :
2204 E : return true;
2205 E : }
2206 :
2207 : } // namespace pe
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