1 //===- GsymCreator.h --------------------------------------------*- 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 #ifndef LLVM_DEBUGINFO_GSYM_GSYMCREATOR_H 10 #define LLVM_DEBUGINFO_GSYM_GSYMCREATOR_H 11 12 #include <functional> 13 #include <memory> 14 #include <mutex> 15 #include <thread> 16 17 #include "llvm/ADT/AddressRanges.h" 18 #include "llvm/ADT/ArrayRef.h" 19 #include "llvm/ADT/StringSet.h" 20 #include "llvm/DebugInfo/GSYM/FileEntry.h" 21 #include "llvm/DebugInfo/GSYM/FunctionInfo.h" 22 #include "llvm/MC/StringTableBuilder.h" 23 #include "llvm/Support/Endian.h" 24 #include "llvm/Support/Error.h" 25 #include "llvm/Support/Path.h" 26 27 namespace llvm { 28 29 namespace gsym { 30 class FileWriter; 31 32 /// GsymCreator is used to emit GSYM data to a stand alone file or section 33 /// within a file. 34 /// 35 /// The GsymCreator is designed to be used in 3 stages: 36 /// - Create FunctionInfo objects and add them 37 /// - Finalize the GsymCreator object 38 /// - Save to file or section 39 /// 40 /// The first stage involves creating FunctionInfo objects from another source 41 /// of information like compiler debug info metadata, DWARF or Breakpad files. 42 /// Any strings in the FunctionInfo or contained information, like InlineInfo 43 /// or LineTable objects, should get the string table offsets by calling 44 /// GsymCreator::insertString(...). Any file indexes that are needed should be 45 /// obtained by calling GsymCreator::insertFile(...). All of the function calls 46 /// in GsymCreator are thread safe. This allows multiple threads to create and 47 /// add FunctionInfo objects while parsing debug information. 48 /// 49 /// Once all of the FunctionInfo objects have been added, the 50 /// GsymCreator::finalize(...) must be called prior to saving. This function 51 /// will sort the FunctionInfo objects, finalize the string table, and do any 52 /// other passes on the information needed to prepare the information to be 53 /// saved. 54 /// 55 /// Once the object has been finalized, it can be saved to a file or section. 56 /// 57 /// ENCODING 58 /// 59 /// GSYM files are designed to be memory mapped into a process as shared, read 60 /// only data, and used as is. 61 /// 62 /// The GSYM file format when in a stand alone file consists of: 63 /// - Header 64 /// - Address Table 65 /// - Function Info Offsets 66 /// - File Table 67 /// - String Table 68 /// - Function Info Data 69 /// 70 /// HEADER 71 /// 72 /// The header is fully described in "llvm/DebugInfo/GSYM/Header.h". 73 /// 74 /// ADDRESS TABLE 75 /// 76 /// The address table immediately follows the header in the file and consists 77 /// of Header.NumAddresses address offsets. These offsets are sorted and can be 78 /// binary searched for efficient lookups. Addresses in the address table are 79 /// stored as offsets from a 64 bit base address found in Header.BaseAddress. 80 /// This allows the address table to contain 8, 16, or 32 offsets. This allows 81 /// the address table to not require full 64 bit addresses for each address. 82 /// The resulting GSYM size is smaller and causes fewer pages to be touched 83 /// during address lookups when the address table is smaller. The size of the 84 /// address offsets in the address table is specified in the header in 85 /// Header.AddrOffSize. The first offset in the address table is aligned to 86 /// Header.AddrOffSize alignment to ensure efficient access when loaded into 87 /// memory. 88 /// 89 /// FUNCTION INFO OFFSETS TABLE 90 /// 91 /// The function info offsets table immediately follows the address table and 92 /// consists of Header.NumAddresses 32 bit file offsets: one for each address 93 /// in the address table. This data is aligned to a 4 byte boundary. The 94 /// offsets in this table are the relative offsets from the start offset of the 95 /// GSYM header and point to the function info data for each address in the 96 /// address table. Keeping this data separate from the address table helps to 97 /// reduce the number of pages that are touched when address lookups occur on a 98 /// GSYM file. 99 /// 100 /// FILE TABLE 101 /// 102 /// The file table immediately follows the function info offsets table. The 103 /// encoding of the FileTable is: 104 /// 105 /// struct FileTable { 106 /// uint32_t Count; 107 /// FileEntry Files[]; 108 /// }; 109 /// 110 /// The file table starts with a 32 bit count of the number of files that are 111 /// used in all of the function info, followed by that number of FileEntry 112 /// structures. The file table is aligned to a 4 byte boundary, Each file in 113 /// the file table is represented with a FileEntry structure. 114 /// See "llvm/DebugInfo/GSYM/FileEntry.h" for details. 115 /// 116 /// STRING TABLE 117 /// 118 /// The string table follows the file table in stand alone GSYM files and 119 /// contains all strings for everything contained in the GSYM file. Any string 120 /// data should be added to the string table and any references to strings 121 /// inside GSYM information must be stored as 32 bit string table offsets into 122 /// this string table. The string table always starts with an empty string at 123 /// offset zero and is followed by any strings needed by the GSYM information. 124 /// The start of the string table is not aligned to any boundary. 125 /// 126 /// FUNCTION INFO DATA 127 /// 128 /// The function info data is the payload that contains information about the 129 /// address that is being looked up. It contains all of the encoded 130 /// FunctionInfo objects. Each encoded FunctionInfo's data is pointed to by an 131 /// entry in the Function Info Offsets Table. For details on the exact encoding 132 /// of FunctionInfo objects, see "llvm/DebugInfo/GSYM/FunctionInfo.h". 133 class GsymCreator { 134 // Private member variables require Mutex protections 135 mutable std::mutex Mutex; 136 std::vector<FunctionInfo> Funcs; 137 StringTableBuilder StrTab; 138 StringSet<> StringStorage; 139 DenseMap<llvm::gsym::FileEntry, uint32_t> FileEntryToIndex; 140 // Needed for mapping string offsets back to the string stored in \a StrTab. 141 DenseMap<uint64_t, CachedHashStringRef> StringOffsetMap; 142 std::vector<llvm::gsym::FileEntry> Files; 143 std::vector<uint8_t> UUID; 144 std::optional<AddressRanges> ValidTextRanges; 145 std::optional<uint64_t> BaseAddress; 146 bool IsSegment = false; 147 bool Finalized = false; 148 bool Quiet; 149 150 151 /// Get the first function start address. 152 /// 153 /// \returns The start address of the first FunctionInfo or std::nullopt if 154 /// there are no function infos. 155 std::optional<uint64_t> getFirstFunctionAddress() const; 156 157 /// Get the last function address. 158 /// 159 /// \returns The start address of the last FunctionInfo or std::nullopt if 160 /// there are no function infos. 161 std::optional<uint64_t> getLastFunctionAddress() const; 162 163 /// Get the base address to use for this GSYM file. 164 /// 165 /// \returns The base address to put into the header and to use when creating 166 /// the address offset table or std::nullpt if there are no valid 167 /// function infos or if the base address wasn't specified. 168 std::optional<uint64_t> getBaseAddress() const; 169 170 /// Get the size of an address offset in the address offset table. 171 /// 172 /// GSYM files store offsets from the base address in the address offset table 173 /// and we store the size of the address offsets in the GSYM header. This 174 /// function will calculate the size in bytes of these address offsets based 175 /// on the current contents of the GSYM file. 176 /// 177 /// \returns The size in byets of the address offsets. 178 uint8_t getAddressOffsetSize() const; 179 180 /// Get the maximum address offset for the current address offset size. 181 /// 182 /// This is used when creating the address offset table to ensure we have 183 /// values that are in range so we don't end up truncating address offsets 184 /// when creating GSYM files as the code evolves. 185 /// 186 /// \returns The maximum address offset value that will be encoded into a GSYM 187 /// file. 188 uint64_t getMaxAddressOffset() const; 189 190 /// Calculate the byte size of the GSYM header and tables sizes. 191 /// 192 /// This function will calculate the exact size in bytes of the encocded GSYM 193 /// for the following items: 194 /// - The GSYM header 195 /// - The Address offset table 196 /// - The Address info offset table 197 /// - The file table 198 /// - The string table 199 /// 200 /// This is used to help split GSYM files into segments. 201 /// 202 /// \returns Size in bytes the GSYM header and tables. 203 uint64_t calculateHeaderAndTableSize() const; 204 205 /// Copy a FunctionInfo from the \a SrcGC GSYM creator into this creator. 206 /// 207 /// Copy the function info and only the needed files and strings and add a 208 /// converted FunctionInfo into this object. This is used to segment GSYM 209 /// files into separate files while only transferring the files and strings 210 /// that are needed from \a SrcGC. 211 /// 212 /// \param SrcGC The source gsym creator to copy from. 213 /// \param FuncInfoIdx The function info index within \a SrcGC to copy. 214 /// \returns The number of bytes it will take to encode the function info in 215 /// this GsymCreator. This helps calculate the size of the current GSYM 216 /// segment file. 217 uint64_t copyFunctionInfo(const GsymCreator &SrcGC, size_t FuncInfoIdx); 218 219 /// Copy a string from \a SrcGC into this object. 220 /// 221 /// Copy a string from \a SrcGC by string table offset into this GSYM creator. 222 /// If a string has already been copied, the uniqued string table offset will 223 /// be returned, otherwise the string will be copied and a unique offset will 224 /// be returned. 225 /// 226 /// \param SrcGC The source gsym creator to copy from. 227 /// \param StrOff The string table offset from \a SrcGC to copy. 228 /// \returns The new string table offset of the string within this object. 229 uint32_t copyString(const GsymCreator &SrcGC, uint32_t StrOff); 230 231 /// Copy a file from \a SrcGC into this object. 232 /// 233 /// Copy a file from \a SrcGC by file index into this GSYM creator. Files 234 /// consist of two string table entries, one for the directory and one for the 235 /// filename, this function will copy any needed strings ensure the file is 236 /// uniqued within this object. If a file already exists in this GSYM creator 237 /// the uniqued index will be returned, else the stirngs will be copied and 238 /// the new file index will be returned. 239 /// 240 /// \param SrcGC The source gsym creator to copy from. 241 /// \param FileIdx The 1 based file table index within \a SrcGC to copy. A 242 /// file index of zero will always return zero as the zero is a reserved file 243 /// index that means no file. 244 /// \returns The new file index of the file within this object. 245 uint32_t copyFile(const GsymCreator &SrcGC, uint32_t FileIdx); 246 247 /// Inserts a FileEntry into the file table. 248 /// 249 /// This is used to insert a file entry in a thread safe way into this object. 250 /// 251 /// \param FE A file entry object that contains valid string table offsets 252 /// from this object already. 253 uint32_t insertFileEntry(FileEntry FE); 254 255 /// Fixup any string and file references by updating any file indexes and 256 /// strings offsets in the InlineInfo parameter. 257 /// 258 /// When copying InlineInfo entries, we can simply make a copy of the object 259 /// and then fixup the files and strings for efficiency. 260 /// 261 /// \param SrcGC The source gsym creator to copy from. 262 /// \param II The inline info that contains file indexes and string offsets 263 /// that come from \a SrcGC. The entries will be updated by coping any files 264 /// and strings over into this object. 265 void fixupInlineInfo(const GsymCreator &SrcGC, InlineInfo &II); 266 267 /// Save this GSYM file into segments that are roughly \a SegmentSize in size. 268 /// 269 /// When segemented GSYM files are saved to disk, they will use \a Path as a 270 /// prefix and then have the first function info address appended to the path 271 /// when each segment is saved. Each segmented GSYM file has a only the 272 /// strings and files that are needed to save the function infos that are in 273 /// each segment. These smaller files are easy to compress and download 274 /// separately and allow for efficient lookups with very large GSYM files and 275 /// segmenting them allows servers to download only the segments that are 276 /// needed. 277 /// 278 /// \param Path The path prefix to use when saving the GSYM files. 279 /// \param ByteOrder The endianness to use when saving the file. 280 /// \param SegmentSize The size in bytes to segment the GSYM file into. 281 llvm::Error saveSegments(StringRef Path, llvm::endianness ByteOrder, 282 uint64_t SegmentSize) const; 283 284 /// Let this creator know that this is a segment of another GsymCreator. 285 /// 286 /// When we have a segment, we know that function infos will be added in 287 /// ascending address range order without having to be finalized. We also 288 /// don't need to sort and unique entries during the finalize function call. 289 void setIsSegment() { 290 IsSegment = true; 291 } 292 293 public: 294 GsymCreator(bool Quiet = false); 295 296 /// Save a GSYM file to a stand alone file. 297 /// 298 /// \param Path The file path to save the GSYM file to. 299 /// \param ByteOrder The endianness to use when saving the file. 300 /// \param SegmentSize The size in bytes to segment the GSYM file into. If 301 /// this option is set this function will create N segments 302 /// that are all around \a SegmentSize bytes in size. This 303 /// allows a very large GSYM file to be broken up into 304 /// shards. Each GSYM file will have its own file table, 305 /// and string table that only have the files and strings 306 /// needed for the shared. If this argument has no value, 307 /// a single GSYM file that contains all function 308 /// information will be created. 309 /// \returns An error object that indicates success or failure of the save. 310 llvm::Error save(StringRef Path, llvm::endianness ByteOrder, 311 std::optional<uint64_t> SegmentSize = std::nullopt) const; 312 313 /// Encode a GSYM into the file writer stream at the current position. 314 /// 315 /// \param O The stream to save the binary data to 316 /// \returns An error object that indicates success or failure of the save. 317 llvm::Error encode(FileWriter &O) const; 318 319 /// Insert a string into the GSYM string table. 320 /// 321 /// All strings used by GSYM files must be uniqued by adding them to this 322 /// string pool and using the returned offset for any string values. 323 /// 324 /// \param S The string to insert into the string table. 325 /// \param Copy If true, then make a backing copy of the string. If false, 326 /// the string is owned by another object that will stay around 327 /// long enough for the GsymCreator to save the GSYM file. 328 /// \returns The unique 32 bit offset into the string table. 329 uint32_t insertString(StringRef S, bool Copy = true); 330 331 /// Insert a file into this GSYM creator. 332 /// 333 /// Inserts a file by adding a FileEntry into the "Files" member variable if 334 /// the file has not already been added. The file path is split into 335 /// directory and filename which are both added to the string table. This 336 /// allows paths to be stored efficiently by reusing the directories that are 337 /// common between multiple files. 338 /// 339 /// \param Path The path to the file to insert. 340 /// \param Style The path style for the "Path" parameter. 341 /// \returns The unique file index for the inserted file. 342 uint32_t insertFile(StringRef Path, 343 sys::path::Style Style = sys::path::Style::native); 344 345 /// Add a function info to this GSYM creator. 346 /// 347 /// All information in the FunctionInfo object must use the 348 /// GsymCreator::insertString(...) function when creating string table 349 /// offsets for names and other strings. 350 /// 351 /// \param FI The function info object to emplace into our functions list. 352 void addFunctionInfo(FunctionInfo &&FI); 353 354 /// Finalize the data in the GSYM creator prior to saving the data out. 355 /// 356 /// Finalize must be called after all FunctionInfo objects have been added 357 /// and before GsymCreator::save() is called. 358 /// 359 /// \param OS Output stream to report duplicate function infos, overlapping 360 /// function infos, and function infos that were merged or removed. 361 /// \returns An error object that indicates success or failure of the 362 /// finalize. 363 llvm::Error finalize(llvm::raw_ostream &OS); 364 365 /// Set the UUID value. 366 /// 367 /// \param UUIDBytes The new UUID bytes. 368 void setUUID(llvm::ArrayRef<uint8_t> UUIDBytes) { 369 UUID.assign(UUIDBytes.begin(), UUIDBytes.end()); 370 } 371 372 /// Thread safe iteration over all function infos. 373 /// 374 /// \param Callback A callback function that will get called with each 375 /// FunctionInfo. If the callback returns false, stop iterating. 376 void forEachFunctionInfo( 377 std::function<bool(FunctionInfo &)> const &Callback); 378 379 /// Thread safe const iteration over all function infos. 380 /// 381 /// \param Callback A callback function that will get called with each 382 /// FunctionInfo. If the callback returns false, stop iterating. 383 void forEachFunctionInfo( 384 std::function<bool(const FunctionInfo &)> const &Callback) const; 385 386 /// Get the current number of FunctionInfo objects contained in this 387 /// object. 388 size_t getNumFunctionInfos() const; 389 390 /// Set valid .text address ranges that all functions must be contained in. 391 void SetValidTextRanges(AddressRanges &TextRanges) { 392 ValidTextRanges = TextRanges; 393 } 394 395 /// Get the valid text ranges. 396 const std::optional<AddressRanges> GetValidTextRanges() const { 397 return ValidTextRanges; 398 } 399 400 /// Check if an address is a valid code address. 401 /// 402 /// Any functions whose addresses do not exist within these function bounds 403 /// will not be converted into the final GSYM. This allows the object file 404 /// to figure out the valid file address ranges of all the code sections 405 /// and ensure we don't add invalid functions to the final output. Many 406 /// linkers have issues when dead stripping functions from DWARF debug info 407 /// where they set the DW_AT_low_pc to zero, but newer DWARF has the 408 /// DW_AT_high_pc as an offset from the DW_AT_low_pc and these size 409 /// attributes have no relocations that can be applied. This results in DWARF 410 /// where many functions have an DW_AT_low_pc of zero and a valid offset size 411 /// for DW_AT_high_pc. If we extract all valid ranges from an object file 412 /// that are marked with executable permissions, we can properly ensure that 413 /// these functions are removed. 414 /// 415 /// \param Addr An address to check. 416 /// 417 /// \returns True if the address is in the valid text ranges or if no valid 418 /// text ranges have been set, false otherwise. 419 bool IsValidTextAddress(uint64_t Addr) const; 420 421 /// Set the base address to use for the GSYM file. 422 /// 423 /// Setting the base address to use for the GSYM file. Object files typically 424 /// get loaded from a base address when the OS loads them into memory. Using 425 /// GSYM files for symbolication becomes easier if the base address in the 426 /// GSYM header is the same address as it allows addresses to be easily slid 427 /// and allows symbolication without needing to find the original base 428 /// address in the original object file. 429 /// 430 /// \param Addr The address to use as the base address of the GSYM file 431 /// when it is saved to disk. 432 void setBaseAddress(uint64_t Addr) { 433 BaseAddress = Addr; 434 } 435 436 /// Whether the transformation should be quiet, i.e. not output warnings. 437 bool isQuiet() const { return Quiet; } 438 439 440 /// Create a segmented GSYM creator starting with function info index 441 /// \a FuncIdx. 442 /// 443 /// This function will create a GsymCreator object that will encode into 444 /// roughly \a SegmentSize bytes and return it. It is used by the private 445 /// saveSegments(...) function and also is used by the GSYM unit tests to test 446 /// segmenting of GSYM files. The returned GsymCreator can be finalized and 447 /// encoded. 448 /// 449 /// \param [in] SegmentSize The size in bytes to roughly segment the GSYM file 450 /// into. 451 /// \param [in,out] FuncIdx The index of the first function info to encode 452 /// into the returned GsymCreator. This index will be updated so it can be 453 /// used in subsequent calls to this function to allow more segments to be 454 /// created. 455 /// \returns An expected unique pointer to a GsymCreator or an error. The 456 /// returned unique pointer can be NULL if there are no more functions to 457 /// encode. 458 llvm::Expected<std::unique_ptr<GsymCreator>> 459 createSegment(uint64_t SegmentSize, size_t &FuncIdx) const; 460 }; 461 462 } // namespace gsym 463 } // namespace llvm 464 465 #endif // LLVM_DEBUGINFO_GSYM_GSYMCREATOR_H 466