1 //===- Wasm.h - Wasm object file implementation -----------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file declares the WasmObjectFile class, which implements the ObjectFile
10 // interface for Wasm files.
11 //
12 // See: https://github.com/WebAssembly/design/blob/master/BinaryEncoding.md
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #ifndef LLVM_OBJECT_WASM_H
17 #define LLVM_OBJECT_WASM_H
18 
19 #include "llvm/ADT/ArrayRef.h"
20 #include "llvm/ADT/StringMap.h"
21 #include "llvm/ADT/StringRef.h"
22 #include "llvm/BinaryFormat/Wasm.h"
23 #include "llvm/Config/llvm-config.h"
24 #include "llvm/MC/MCSymbolWasm.h"
25 #include "llvm/Object/Binary.h"
26 #include "llvm/Object/ObjectFile.h"
27 #include "llvm/Support/Error.h"
28 #include "llvm/Support/MemoryBuffer.h"
29 #include <cstddef>
30 #include <cstdint>
31 #include <vector>
32 
33 namespace llvm {
34 namespace object {
35 
36 class WasmSymbol {
37 public:
WasmSymbol(const wasm::WasmSymbolInfo & Info,const wasm::WasmGlobalType * GlobalType,const wasm::WasmEventType * EventType,const wasm::WasmSignature * Signature)38   WasmSymbol(const wasm::WasmSymbolInfo &Info,
39              const wasm::WasmGlobalType *GlobalType,
40              const wasm::WasmEventType *EventType,
41              const wasm::WasmSignature *Signature)
42       : Info(Info), GlobalType(GlobalType), EventType(EventType),
43         Signature(Signature) {}
44 
45   const wasm::WasmSymbolInfo &Info;
46   const wasm::WasmGlobalType *GlobalType;
47   const wasm::WasmEventType *EventType;
48   const wasm::WasmSignature *Signature;
49 
isTypeFunction()50   bool isTypeFunction() const {
51     return Info.Kind == wasm::WASM_SYMBOL_TYPE_FUNCTION;
52   }
53 
isTypeData()54   bool isTypeData() const { return Info.Kind == wasm::WASM_SYMBOL_TYPE_DATA; }
55 
isTypeGlobal()56   bool isTypeGlobal() const {
57     return Info.Kind == wasm::WASM_SYMBOL_TYPE_GLOBAL;
58   }
59 
isTypeSection()60   bool isTypeSection() const {
61     return Info.Kind == wasm::WASM_SYMBOL_TYPE_SECTION;
62   }
63 
isTypeEvent()64   bool isTypeEvent() const { return Info.Kind == wasm::WASM_SYMBOL_TYPE_EVENT; }
65 
isDefined()66   bool isDefined() const { return !isUndefined(); }
67 
isUndefined()68   bool isUndefined() const {
69     return (Info.Flags & wasm::WASM_SYMBOL_UNDEFINED) != 0;
70   }
71 
isBindingWeak()72   bool isBindingWeak() const {
73     return getBinding() == wasm::WASM_SYMBOL_BINDING_WEAK;
74   }
75 
isBindingGlobal()76   bool isBindingGlobal() const {
77     return getBinding() == wasm::WASM_SYMBOL_BINDING_GLOBAL;
78   }
79 
isBindingLocal()80   bool isBindingLocal() const {
81     return getBinding() == wasm::WASM_SYMBOL_BINDING_LOCAL;
82   }
83 
getBinding()84   unsigned getBinding() const {
85     return Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK;
86   }
87 
isHidden()88   bool isHidden() const {
89     return getVisibility() == wasm::WASM_SYMBOL_VISIBILITY_HIDDEN;
90   }
91 
getVisibility()92   unsigned getVisibility() const {
93     return Info.Flags & wasm::WASM_SYMBOL_VISIBILITY_MASK;
94   }
95 
96   void print(raw_ostream &Out) const;
97 
98 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
99   LLVM_DUMP_METHOD void dump() const;
100 #endif
101 };
102 
103 struct WasmSection {
104   WasmSection() = default;
105 
106   uint32_t Type = 0;         // Section type (See below)
107   uint32_t Offset = 0;       // Offset with in the file
108   StringRef Name;            // Section name (User-defined sections only)
109   ArrayRef<uint8_t> Content; // Section content
110   std::vector<wasm::WasmRelocation> Relocations; // Relocations for this section
111 };
112 
113 struct WasmSegment {
114   uint32_t SectionOffset;
115   wasm::WasmDataSegment Data;
116 };
117 
118 class WasmObjectFile : public ObjectFile {
119 
120 public:
121   WasmObjectFile(MemoryBufferRef Object, Error &Err);
122 
123   const wasm::WasmObjectHeader &getHeader() const;
124   const WasmSymbol &getWasmSymbol(const DataRefImpl &Symb) const;
125   const WasmSymbol &getWasmSymbol(const SymbolRef &Symbol) const;
126   const WasmSection &getWasmSection(const SectionRef &Section) const;
127   const wasm::WasmRelocation &getWasmRelocation(const RelocationRef &Ref) const;
128 
classof(const Binary * v)129   static bool classof(const Binary *v) { return v->isWasm(); }
130 
dylinkInfo()131   const wasm::WasmDylinkInfo &dylinkInfo() const { return DylinkInfo; }
getProducerInfo()132   const wasm::WasmProducerInfo &getProducerInfo() const { return ProducerInfo; }
getTargetFeatures()133   ArrayRef<wasm::WasmFeatureEntry> getTargetFeatures() const {
134     return TargetFeatures;
135   }
types()136   ArrayRef<wasm::WasmSignature> types() const { return Signatures; }
functionTypes()137   ArrayRef<uint32_t> functionTypes() const { return FunctionTypes; }
imports()138   ArrayRef<wasm::WasmImport> imports() const { return Imports; }
tables()139   ArrayRef<wasm::WasmTable> tables() const { return Tables; }
memories()140   ArrayRef<wasm::WasmLimits> memories() const { return Memories; }
globals()141   ArrayRef<wasm::WasmGlobal> globals() const { return Globals; }
events()142   ArrayRef<wasm::WasmEvent> events() const { return Events; }
exports()143   ArrayRef<wasm::WasmExport> exports() const { return Exports; }
syms()144   ArrayRef<WasmSymbol> syms() const { return Symbols; }
linkingData()145   const wasm::WasmLinkingData &linkingData() const { return LinkingData; }
getNumberOfSymbols()146   uint32_t getNumberOfSymbols() const { return Symbols.size(); }
elements()147   ArrayRef<wasm::WasmElemSegment> elements() const { return ElemSegments; }
dataSegments()148   ArrayRef<WasmSegment> dataSegments() const { return DataSegments; }
functions()149   ArrayRef<wasm::WasmFunction> functions() const { return Functions; }
debugNames()150   ArrayRef<wasm::WasmFunctionName> debugNames() const { return DebugNames; }
startFunction()151   uint32_t startFunction() const { return StartFunction; }
getNumImportedGlobals()152   uint32_t getNumImportedGlobals() const { return NumImportedGlobals; }
getNumImportedFunctions()153   uint32_t getNumImportedFunctions() const { return NumImportedFunctions; }
getNumImportedEvents()154   uint32_t getNumImportedEvents() const { return NumImportedEvents; }
155   void moveSymbolNext(DataRefImpl &Symb) const override;
156 
157   uint32_t getSymbolFlags(DataRefImpl Symb) const override;
158 
159   basic_symbol_iterator symbol_begin() const override;
160 
161   basic_symbol_iterator symbol_end() const override;
162   Expected<StringRef> getSymbolName(DataRefImpl Symb) const override;
163 
164   Expected<uint64_t> getSymbolAddress(DataRefImpl Symb) const override;
165   uint64_t getWasmSymbolValue(const WasmSymbol &Sym) const;
166   uint64_t getSymbolValueImpl(DataRefImpl Symb) const override;
167   uint32_t getSymbolAlignment(DataRefImpl Symb) const override;
168   uint64_t getCommonSymbolSizeImpl(DataRefImpl Symb) const override;
169   Expected<SymbolRef::Type> getSymbolType(DataRefImpl Symb) const override;
170   Expected<section_iterator> getSymbolSection(DataRefImpl Symb) const override;
171 
172   // Overrides from SectionRef.
173   void moveSectionNext(DataRefImpl &Sec) const override;
174   Expected<StringRef> getSectionName(DataRefImpl Sec) const override;
175   uint64_t getSectionAddress(DataRefImpl Sec) const override;
176   uint64_t getSectionIndex(DataRefImpl Sec) const override;
177   uint64_t getSectionSize(DataRefImpl Sec) const override;
178   Expected<ArrayRef<uint8_t>>
179   getSectionContents(DataRefImpl Sec) const override;
180   uint64_t getSectionAlignment(DataRefImpl Sec) const override;
181   bool isSectionCompressed(DataRefImpl Sec) const override;
182   bool isSectionText(DataRefImpl Sec) const override;
183   bool isSectionData(DataRefImpl Sec) const override;
184   bool isSectionBSS(DataRefImpl Sec) const override;
185   bool isSectionVirtual(DataRefImpl Sec) const override;
186   bool isSectionBitcode(DataRefImpl Sec) const override;
187   relocation_iterator section_rel_begin(DataRefImpl Sec) const override;
188   relocation_iterator section_rel_end(DataRefImpl Sec) const override;
189 
190   // Overrides from RelocationRef.
191   void moveRelocationNext(DataRefImpl &Rel) const override;
192   uint64_t getRelocationOffset(DataRefImpl Rel) const override;
193   symbol_iterator getRelocationSymbol(DataRefImpl Rel) const override;
194   uint64_t getRelocationType(DataRefImpl Rel) const override;
195   void getRelocationTypeName(DataRefImpl Rel,
196                              SmallVectorImpl<char> &Result) const override;
197 
198   section_iterator section_begin() const override;
199   section_iterator section_end() const override;
200   uint8_t getBytesInAddress() const override;
201   StringRef getFileFormatName() const override;
202   Triple::ArchType getArch() const override;
203   SubtargetFeatures getFeatures() const override;
204   bool isRelocatableObject() const override;
205   bool isSharedObject() const;
206 
207   struct ReadContext {
208     const uint8_t *Start;
209     const uint8_t *Ptr;
210     const uint8_t *End;
211   };
212 
213 private:
214   bool isValidFunctionIndex(uint32_t Index) const;
215   bool isDefinedFunctionIndex(uint32_t Index) const;
216   bool isValidGlobalIndex(uint32_t Index) const;
217   bool isDefinedGlobalIndex(uint32_t Index) const;
218   bool isValidEventIndex(uint32_t Index) const;
219   bool isDefinedEventIndex(uint32_t Index) const;
220   bool isValidFunctionSymbol(uint32_t Index) const;
221   bool isValidGlobalSymbol(uint32_t Index) const;
222   bool isValidEventSymbol(uint32_t Index) const;
223   bool isValidDataSymbol(uint32_t Index) const;
224   bool isValidSectionSymbol(uint32_t Index) const;
225   wasm::WasmFunction &getDefinedFunction(uint32_t Index);
226   const wasm::WasmFunction &getDefinedFunction(uint32_t Index) const;
227   wasm::WasmGlobal &getDefinedGlobal(uint32_t Index);
228   wasm::WasmEvent &getDefinedEvent(uint32_t Index);
229 
230   const WasmSection &getWasmSection(DataRefImpl Ref) const;
231   const wasm::WasmRelocation &getWasmRelocation(DataRefImpl Ref) const;
232 
233   Error parseSection(WasmSection &Sec);
234   Error parseCustomSection(WasmSection &Sec, ReadContext &Ctx);
235 
236   // Standard section types
237   Error parseTypeSection(ReadContext &Ctx);
238   Error parseImportSection(ReadContext &Ctx);
239   Error parseFunctionSection(ReadContext &Ctx);
240   Error parseTableSection(ReadContext &Ctx);
241   Error parseMemorySection(ReadContext &Ctx);
242   Error parseGlobalSection(ReadContext &Ctx);
243   Error parseEventSection(ReadContext &Ctx);
244   Error parseExportSection(ReadContext &Ctx);
245   Error parseStartSection(ReadContext &Ctx);
246   Error parseElemSection(ReadContext &Ctx);
247   Error parseCodeSection(ReadContext &Ctx);
248   Error parseDataSection(ReadContext &Ctx);
249   Error parseDataCountSection(ReadContext &Ctx);
250 
251   // Custom section types
252   Error parseDylinkSection(ReadContext &Ctx);
253   Error parseNameSection(ReadContext &Ctx);
254   Error parseLinkingSection(ReadContext &Ctx);
255   Error parseLinkingSectionSymtab(ReadContext &Ctx);
256   Error parseLinkingSectionComdat(ReadContext &Ctx);
257   Error parseProducersSection(ReadContext &Ctx);
258   Error parseTargetFeaturesSection(ReadContext &Ctx);
259   Error parseRelocSection(StringRef Name, ReadContext &Ctx);
260 
261   wasm::WasmObjectHeader Header;
262   std::vector<WasmSection> Sections;
263   wasm::WasmDylinkInfo DylinkInfo;
264   wasm::WasmProducerInfo ProducerInfo;
265   std::vector<wasm::WasmFeatureEntry> TargetFeatures;
266   std::vector<wasm::WasmSignature> Signatures;
267   std::vector<uint32_t> FunctionTypes;
268   std::vector<wasm::WasmTable> Tables;
269   std::vector<wasm::WasmLimits> Memories;
270   std::vector<wasm::WasmGlobal> Globals;
271   std::vector<wasm::WasmEvent> Events;
272   std::vector<wasm::WasmImport> Imports;
273   std::vector<wasm::WasmExport> Exports;
274   std::vector<wasm::WasmElemSegment> ElemSegments;
275   std::vector<WasmSegment> DataSegments;
276   llvm::Optional<size_t> DataCount;
277   std::vector<wasm::WasmFunction> Functions;
278   std::vector<WasmSymbol> Symbols;
279   std::vector<wasm::WasmFunctionName> DebugNames;
280   uint32_t StartFunction = -1;
281   bool HasLinkingSection = false;
282   bool HasDylinkSection = false;
283   wasm::WasmLinkingData LinkingData;
284   uint32_t NumImportedGlobals = 0;
285   uint32_t NumImportedFunctions = 0;
286   uint32_t NumImportedEvents = 0;
287   uint32_t CodeSection = 0;
288   uint32_t DataSection = 0;
289   uint32_t GlobalSection = 0;
290   uint32_t EventSection = 0;
291 };
292 
293 class WasmSectionOrderChecker {
294 public:
295   // We define orders for all core wasm sections and known custom sections.
296   enum : int {
297     // Sentinel, must be zero
298     WASM_SEC_ORDER_NONE = 0,
299 
300     // Core sections
301     WASM_SEC_ORDER_TYPE,
302     WASM_SEC_ORDER_IMPORT,
303     WASM_SEC_ORDER_FUNCTION,
304     WASM_SEC_ORDER_TABLE,
305     WASM_SEC_ORDER_MEMORY,
306     WASM_SEC_ORDER_GLOBAL,
307     WASM_SEC_ORDER_EVENT,
308     WASM_SEC_ORDER_EXPORT,
309     WASM_SEC_ORDER_START,
310     WASM_SEC_ORDER_ELEM,
311     WASM_SEC_ORDER_DATACOUNT,
312     WASM_SEC_ORDER_CODE,
313     WASM_SEC_ORDER_DATA,
314 
315     // Custom sections
316     // "dylink" should be the very first section in the module
317     WASM_SEC_ORDER_DYLINK,
318     // "linking" section requires DATA section in order to validate data symbols
319     WASM_SEC_ORDER_LINKING,
320     // Must come after "linking" section in order to validate reloc indexes.
321     WASM_SEC_ORDER_RELOC,
322     // "name" section must appear after DATA. Comes after "linking" to allow
323     // symbol table to set default function name.
324     WASM_SEC_ORDER_NAME,
325     // "producers" section must appear after "name" section.
326     WASM_SEC_ORDER_PRODUCERS,
327     // "target_features" section must appear after producers section
328     WASM_SEC_ORDER_TARGET_FEATURES,
329 
330     // Must be last
331     WASM_NUM_SEC_ORDERS
332 
333   };
334 
335   // Sections that may or may not be present, but cannot be predecessors
336   static int DisallowedPredecessors[WASM_NUM_SEC_ORDERS][WASM_NUM_SEC_ORDERS];
337 
338   bool isValidSectionOrder(unsigned ID, StringRef CustomSectionName = "");
339 
340 private:
341   bool Seen[WASM_NUM_SEC_ORDERS] = {}; // Sections that have been seen already
342 
343   // Returns -1 for unknown sections.
344   int getSectionOrder(unsigned ID, StringRef CustomSectionName = "");
345 };
346 
347 } // end namespace object
348 
349 inline raw_ostream &operator<<(raw_ostream &OS, const object::WasmSymbol &Sym) {
350   Sym.print(OS);
351   return OS;
352 }
353 
354 } // end namespace llvm
355 
356 #endif // LLVM_OBJECT_WASM_H
357