1 //===- ScriptParser.cpp ---------------------------------------------------===//
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains a recursive-descendent parser for linker scripts.
11 // Parsed results are stored to Config and Script global objects.
13 //===----------------------------------------------------------------------===//
15 #include "ScriptParser.h"
18 #include "InputSection.h"
19 #include "LinkerScript.h"
20 #include "OutputSections.h"
21 #include "ScriptLexer.h"
24 #include "lld/Common/Memory.h"
25 #include "llvm/ADT/SmallString.h"
26 #include "llvm/ADT/StringRef.h"
27 #include "llvm/ADT/StringSet.h"
28 #include "llvm/ADT/StringSwitch.h"
29 #include "llvm/BinaryFormat/ELF.h"
30 #include "llvm/Support/Casting.h"
31 #include "llvm/Support/ErrorHandling.h"
32 #include "llvm/Support/FileSystem.h"
33 #include "llvm/Support/Path.h"
39 using namespace llvm::ELF;
40 using namespace llvm::support::endian;
42 using namespace lld::elf;
44 static bool isUnderSysroot(StringRef Path);
47 class ScriptParser final : ScriptLexer {
49 ScriptParser(MemoryBufferRef MB)
51 IsUnderSysroot(isUnderSysroot(MB.getBufferIdentifier())) {}
53 void readLinkerScript();
54 void readVersionScript();
55 void readDynamicList();
56 void readDefsym(StringRef Name);
59 void addFile(StringRef Path);
69 void readOutputArch();
70 void readOutputFormat();
72 void readRegionAlias();
76 void readVersionScriptCommand();
78 SymbolAssignment *readSymbolAssignment(StringRef Name);
79 ByteCommand *readByteCommand(StringRef Tok);
81 uint32_t parseFill(StringRef Tok);
82 void readSectionAddressType(OutputSection *Cmd);
83 OutputSection *readOverlaySectionDescription();
84 OutputSection *readOutputSectionDescription(StringRef OutSec);
85 std::vector<BaseCommand *> readOverlay();
86 std::vector<StringRef> readOutputSectionPhdrs();
87 InputSectionDescription *readInputSectionDescription(StringRef Tok);
88 StringMatcher readFilePatterns();
89 std::vector<SectionPattern> readInputSectionsList();
90 InputSectionDescription *readInputSectionRules(StringRef FilePattern);
91 unsigned readPhdrType();
92 SortSectionPolicy readSortKind();
93 SymbolAssignment *readProvideHidden(bool Provide, bool Hidden);
94 SymbolAssignment *readAssignment(StringRef Tok);
100 uint64_t readMemoryAssignment(StringRef, StringRef, StringRef);
101 std::pair<uint32_t, uint32_t> readMemoryAttributes();
103 Expr combine(StringRef Op, Expr L, Expr R);
105 Expr readExpr1(Expr Lhs, int MinPrec);
106 StringRef readParenLiteral();
108 Expr readTernary(Expr Cond);
109 Expr readParenExpr();
111 // For parsing version script.
112 std::vector<SymbolVersion> readVersionExtern();
113 void readAnonymousDeclaration();
114 void readVersionDeclaration(StringRef VerStr);
116 std::pair<std::vector<SymbolVersion>, std::vector<SymbolVersion>>
119 // True if a script being read is in a subdirectory specified by -sysroot.
122 // A set to detect an INCLUDE() cycle.
127 static StringRef unquote(StringRef S) {
128 if (S.startswith("\""))
129 return S.substr(1, S.size() - 2);
133 static bool isUnderSysroot(StringRef Path) {
134 if (Config->Sysroot == "")
136 for (; !Path.empty(); Path = sys::path::parent_path(Path))
137 if (sys::fs::equivalent(Config->Sysroot, Path))
142 // Some operations only support one non absolute value. Move the
143 // absolute one to the right hand side for convenience.
144 static void moveAbsRight(ExprValue &A, ExprValue &B) {
145 if (A.Sec == nullptr || (A.ForceAbsolute && !B.isAbsolute()))
148 error(A.Loc + ": at least one side of the expression must be absolute");
151 static ExprValue add(ExprValue A, ExprValue B) {
153 return {A.Sec, A.ForceAbsolute, A.getSectionOffset() + B.getValue(), A.Loc};
156 static ExprValue sub(ExprValue A, ExprValue B) {
157 // The distance between two symbols in sections is absolute.
158 if (!A.isAbsolute() && !B.isAbsolute())
159 return A.getValue() - B.getValue();
160 return {A.Sec, false, A.getSectionOffset() - B.getValue(), A.Loc};
163 static ExprValue bitAnd(ExprValue A, ExprValue B) {
165 return {A.Sec, A.ForceAbsolute,
166 (A.getValue() & B.getValue()) - A.getSecAddr(), A.Loc};
169 static ExprValue bitOr(ExprValue A, ExprValue B) {
171 return {A.Sec, A.ForceAbsolute,
172 (A.getValue() | B.getValue()) - A.getSecAddr(), A.Loc};
175 void ScriptParser::readDynamicList() {
176 Config->HasDynamicList = true;
178 std::vector<SymbolVersion> Locals;
179 std::vector<SymbolVersion> Globals;
180 std::tie(Locals, Globals) = readSymbols();
184 setError("EOF expected, but got " + next());
187 if (!Locals.empty()) {
188 setError("\"local:\" scope not supported in --dynamic-list");
192 for (SymbolVersion V : Globals)
193 Config->DynamicList.push_back(V);
196 void ScriptParser::readVersionScript() {
197 readVersionScriptCommand();
199 setError("EOF expected, but got " + next());
202 void ScriptParser::readVersionScriptCommand() {
204 readAnonymousDeclaration();
208 while (!atEOF() && !errorCount() && peek() != "}") {
209 StringRef VerStr = next();
211 setError("anonymous version definition is used in "
212 "combination with other version definitions");
216 readVersionDeclaration(VerStr);
220 void ScriptParser::readVersion() {
222 readVersionScriptCommand();
226 void ScriptParser::readLinkerScript() {
228 StringRef Tok = next();
232 if (Tok == "ENTRY") {
234 } else if (Tok == "EXTERN") {
236 } else if (Tok == "GROUP") {
238 } else if (Tok == "INCLUDE") {
240 } else if (Tok == "INPUT") {
242 } else if (Tok == "MEMORY") {
244 } else if (Tok == "OUTPUT") {
246 } else if (Tok == "OUTPUT_ARCH") {
248 } else if (Tok == "OUTPUT_FORMAT") {
250 } else if (Tok == "PHDRS") {
252 } else if (Tok == "REGION_ALIAS") {
254 } else if (Tok == "SEARCH_DIR") {
256 } else if (Tok == "SECTIONS") {
258 } else if (Tok == "VERSION") {
260 } else if (SymbolAssignment *Cmd = readAssignment(Tok)) {
261 Script->SectionCommands.push_back(Cmd);
263 setError("unknown directive: " + Tok);
268 void ScriptParser::readDefsym(StringRef Name) {
271 setError("EOF expected, but got " + next());
272 SymbolAssignment *Cmd = make<SymbolAssignment>(Name, E, getCurrentLocation());
273 Script->SectionCommands.push_back(Cmd);
276 void ScriptParser::addFile(StringRef S) {
277 if (IsUnderSysroot && S.startswith("/")) {
278 SmallString<128> PathData;
279 StringRef Path = (Config->Sysroot + S).toStringRef(PathData);
280 if (sys::fs::exists(Path)) {
281 Driver->addFile(Saver.save(Path), /*WithLOption=*/false);
286 if (S.startswith("/")) {
287 Driver->addFile(S, /*WithLOption=*/false);
288 } else if (S.startswith("=")) {
289 if (Config->Sysroot.empty())
290 Driver->addFile(S.substr(1), /*WithLOption=*/false);
292 Driver->addFile(Saver.save(Config->Sysroot + "/" + S.substr(1)),
293 /*WithLOption=*/false);
294 } else if (S.startswith("-l")) {
295 Driver->addLibrary(S.substr(2));
296 } else if (sys::fs::exists(S)) {
297 Driver->addFile(S, /*WithLOption=*/false);
299 if (Optional<std::string> Path = findFromSearchPaths(S))
300 Driver->addFile(Saver.save(*Path), /*WithLOption=*/true);
302 setError("unable to find " + S);
306 void ScriptParser::readAsNeeded() {
308 bool Orig = Config->AsNeeded;
309 Config->AsNeeded = true;
310 while (!errorCount() && !consume(")"))
311 addFile(unquote(next()));
312 Config->AsNeeded = Orig;
315 void ScriptParser::readEntry() {
316 // -e <symbol> takes predecence over ENTRY(<symbol>).
318 StringRef Tok = next();
319 if (Config->Entry.empty())
324 void ScriptParser::readExtern() {
326 while (!errorCount() && !consume(")"))
327 Config->Undefined.push_back(next());
330 void ScriptParser::readGroup() {
331 bool Orig = InputFile::IsInGroup;
332 InputFile::IsInGroup = true;
334 InputFile::IsInGroup = Orig;
336 ++InputFile::NextGroupId;
339 void ScriptParser::readInclude() {
340 StringRef Tok = unquote(next());
342 if (!Seen.insert(Tok).second) {
343 setError("there is a cycle in linker script INCLUDEs");
347 if (Optional<std::string> Path = searchScript(Tok)) {
348 if (Optional<MemoryBufferRef> MB = readFile(*Path))
352 setError("cannot find linker script " + Tok);
355 void ScriptParser::readInput() {
357 while (!errorCount() && !consume(")")) {
358 if (consume("AS_NEEDED"))
361 addFile(unquote(next()));
365 void ScriptParser::readOutput() {
366 // -o <file> takes predecence over OUTPUT(<file>).
368 StringRef Tok = next();
369 if (Config->OutputFile.empty())
370 Config->OutputFile = unquote(Tok);
374 void ScriptParser::readOutputArch() {
375 // OUTPUT_ARCH is ignored for now.
377 while (!errorCount() && !consume(")"))
381 void ScriptParser::readOutputFormat() {
382 // Error checking only for now.
394 void ScriptParser::readPhdrs() {
397 while (!errorCount() && !consume("}")) {
400 Cmd.Type = readPhdrType();
402 while (!errorCount() && !consume(";")) {
403 if (consume("FILEHDR"))
404 Cmd.HasFilehdr = true;
405 else if (consume("PHDRS"))
407 else if (consume("AT"))
408 Cmd.LMAExpr = readParenExpr();
409 else if (consume("FLAGS"))
410 Cmd.Flags = readParenExpr()().getValue();
412 setError("unexpected header attribute: " + next());
415 Script->PhdrsCommands.push_back(Cmd);
419 void ScriptParser::readRegionAlias() {
421 StringRef Alias = unquote(next());
423 StringRef Name = next();
426 if (Script->MemoryRegions.count(Alias))
427 setError("redefinition of memory region '" + Alias + "'");
428 if (!Script->MemoryRegions.count(Name))
429 setError("memory region '" + Name + "' is not defined");
430 Script->MemoryRegions.insert({Alias, Script->MemoryRegions[Name]});
433 void ScriptParser::readSearchDir() {
435 StringRef Tok = next();
436 if (!Config->Nostdlib)
437 Config->SearchPaths.push_back(unquote(Tok));
441 // This reads an overlay description. Overlays are used to describe output
442 // sections that use the same virtual memory range and normally would trigger
443 // linker's sections sanity check failures.
444 // https://sourceware.org/binutils/docs/ld/Overlay-Description.html#Overlay-Description
445 std::vector<BaseCommand *> ScriptParser::readOverlay() {
446 // VA and LMA expressions are optional, though for simplicity of
447 // implementation we assume they are not. That is what OVERLAY was designed
448 // for first of all: to allow sections with overlapping VAs at different LMAs.
449 Expr AddrExpr = readExpr();
452 Expr LMAExpr = readParenExpr();
455 std::vector<BaseCommand *> V;
456 OutputSection *Prev = nullptr;
457 while (!errorCount() && !consume("}")) {
458 // VA is the same for all sections. The LMAs are consecutive in memory
459 // starting from the base load address specified.
460 OutputSection *OS = readOverlaySectionDescription();
461 OS->AddrExpr = AddrExpr;
463 OS->LMAExpr = [=] { return Prev->getLMA() + Prev->Size; };
465 OS->LMAExpr = LMAExpr;
470 // According to the specification, at the end of the overlay, the location
471 // counter should be equal to the overlay base address plus size of the
472 // largest section seen in the overlay.
473 // Here we want to create the Dot assignment command to achieve that.
476 for (BaseCommand *Cmd : V)
477 Max = std::max(Max, cast<OutputSection>(Cmd)->Size);
478 return AddrExpr().getValue() + Max;
480 V.push_back(make<SymbolAssignment>(".", MoveDot, getCurrentLocation()));
484 void ScriptParser::readSections() {
485 Script->HasSectionsCommand = true;
487 // -no-rosegment is used to avoid placing read only non-executable sections in
488 // their own segment. We do the same if SECTIONS command is present in linker
489 // script. See comment for computeFlags().
490 Config->SingleRoRx = true;
493 std::vector<BaseCommand *> V;
494 while (!errorCount() && !consume("}")) {
495 StringRef Tok = next();
496 if (Tok == "OVERLAY") {
497 for (BaseCommand *Cmd : readOverlay())
502 if (BaseCommand *Cmd = readAssignment(Tok))
505 V.push_back(readOutputSectionDescription(Tok));
508 if (!atEOF() && consume("INSERT")) {
509 std::vector<BaseCommand *> *Dest = nullptr;
510 if (consume("AFTER"))
511 Dest = &Script->InsertAfterCommands[next()];
512 else if (consume("BEFORE"))
513 Dest = &Script->InsertBeforeCommands[next()];
515 setError("expected AFTER/BEFORE, but got '" + next() + "'");
517 Dest->insert(Dest->end(), V.begin(), V.end());
521 Script->SectionCommands.insert(Script->SectionCommands.end(), V.begin(),
525 static int precedence(StringRef Op) {
526 return StringSwitch<int>(Op)
527 .Cases("*", "/", "%", 8)
529 .Cases("<<", ">>", 6)
530 .Cases("<", "<=", ">", ">=", "==", "!=", 5)
538 StringMatcher ScriptParser::readFilePatterns() {
539 std::vector<StringRef> V;
540 while (!errorCount() && !consume(")"))
542 return StringMatcher(V);
545 SortSectionPolicy ScriptParser::readSortKind() {
546 if (consume("SORT") || consume("SORT_BY_NAME"))
547 return SortSectionPolicy::Name;
548 if (consume("SORT_BY_ALIGNMENT"))
549 return SortSectionPolicy::Alignment;
550 if (consume("SORT_BY_INIT_PRIORITY"))
551 return SortSectionPolicy::Priority;
552 if (consume("SORT_NONE"))
553 return SortSectionPolicy::None;
554 return SortSectionPolicy::Default;
557 // Reads SECTIONS command contents in the following form:
559 // <contents> ::= <elem>*
560 // <elem> ::= <exclude>? <glob-pattern>
561 // <exclude> ::= "EXCLUDE_FILE" "(" <glob-pattern>+ ")"
565 // *(.foo EXCLUDE_FILE (a.o) .bar EXCLUDE_FILE (b.o) .baz)
567 // is parsed as ".foo", ".bar" with "a.o", and ".baz" with "b.o".
568 // The semantics of that is section .foo in any file, section .bar in
569 // any file but a.o, and section .baz in any file but b.o.
570 std::vector<SectionPattern> ScriptParser::readInputSectionsList() {
571 std::vector<SectionPattern> Ret;
572 while (!errorCount() && peek() != ")") {
573 StringMatcher ExcludeFilePat;
574 if (consume("EXCLUDE_FILE")) {
576 ExcludeFilePat = readFilePatterns();
579 std::vector<StringRef> V;
580 while (!errorCount() && peek() != ")" && peek() != "EXCLUDE_FILE")
584 Ret.push_back({std::move(ExcludeFilePat), StringMatcher(V)});
586 setError("section pattern is expected");
591 // Reads contents of "SECTIONS" directive. That directive contains a
592 // list of glob patterns for input sections. The grammar is as follows.
594 // <patterns> ::= <section-list>
595 // | <sort> "(" <section-list> ")"
596 // | <sort> "(" <sort> "(" <section-list> ")" ")"
598 // <sort> ::= "SORT" | "SORT_BY_NAME" | "SORT_BY_ALIGNMENT"
599 // | "SORT_BY_INIT_PRIORITY" | "SORT_NONE"
601 // <section-list> is parsed by readInputSectionsList().
602 InputSectionDescription *
603 ScriptParser::readInputSectionRules(StringRef FilePattern) {
604 auto *Cmd = make<InputSectionDescription>(FilePattern);
607 while (!errorCount() && !consume(")")) {
608 SortSectionPolicy Outer = readSortKind();
609 SortSectionPolicy Inner = SortSectionPolicy::Default;
610 std::vector<SectionPattern> V;
611 if (Outer != SortSectionPolicy::Default) {
613 Inner = readSortKind();
614 if (Inner != SortSectionPolicy::Default) {
616 V = readInputSectionsList();
619 V = readInputSectionsList();
623 V = readInputSectionsList();
626 for (SectionPattern &Pat : V) {
627 Pat.SortInner = Inner;
628 Pat.SortOuter = Outer;
631 std::move(V.begin(), V.end(), std::back_inserter(Cmd->SectionPatterns));
636 InputSectionDescription *
637 ScriptParser::readInputSectionDescription(StringRef Tok) {
638 // Input section wildcard can be surrounded by KEEP.
639 // https://sourceware.org/binutils/docs/ld/Input-Section-Keep.html#Input-Section-Keep
642 StringRef FilePattern = next();
643 InputSectionDescription *Cmd = readInputSectionRules(FilePattern);
645 Script->KeptSections.push_back(Cmd);
648 return readInputSectionRules(Tok);
651 void ScriptParser::readSort() {
653 expect("CONSTRUCTORS");
657 Expr ScriptParser::readAssert() {
661 StringRef Msg = unquote(next());
667 return Script->getDot();
671 // Reads a FILL(expr) command. We handle the FILL command as an
672 // alias for =fillexp section attribute, which is different from
673 // what GNU linkers do.
674 // https://sourceware.org/binutils/docs/ld/Output-Section-Data.html
675 uint32_t ScriptParser::readFill() {
677 uint32_t V = parseFill(next());
682 // Reads an expression and/or the special directive for an output
683 // section definition. Directive is one of following: "(NOLOAD)",
684 // "(COPY)", "(INFO)" or "(OVERLAY)".
686 // An output section name can be followed by an address expression
687 // and/or directive. This grammar is not LL(1) because "(" can be
688 // interpreted as either the beginning of some expression or beginning
691 // https://sourceware.org/binutils/docs/ld/Output-Section-Address.html
692 // https://sourceware.org/binutils/docs/ld/Output-Section-Type.html
693 void ScriptParser::readSectionAddressType(OutputSection *Cmd) {
695 if (consume("NOLOAD")) {
700 if (consume("COPY") || consume("INFO") || consume("OVERLAY")) {
702 Cmd->NonAlloc = true;
705 Cmd->AddrExpr = readExpr();
708 Cmd->AddrExpr = readExpr();
718 static Expr checkAlignment(Expr E, std::string &Loc) {
720 uint64_t Alignment = std::max((uint64_t)1, E().getValue());
721 if (!isPowerOf2_64(Alignment)) {
722 error(Loc + ": alignment must be power of 2");
723 return (uint64_t)1; // Return a dummy value.
729 OutputSection *ScriptParser::readOverlaySectionDescription() {
731 Script->createOutputSection(next(), getCurrentLocation());
732 Cmd->InOverlay = true;
734 while (!errorCount() && !consume("}"))
735 Cmd->SectionCommands.push_back(readInputSectionRules(next()));
736 Cmd->Phdrs = readOutputSectionPhdrs();
740 OutputSection *ScriptParser::readOutputSectionDescription(StringRef OutSec) {
742 Script->createOutputSection(OutSec, getCurrentLocation());
744 size_t SymbolsReferenced = Script->ReferencedSymbols.size();
747 readSectionAddressType(Cmd);
750 std::string Location = getCurrentLocation();
752 Cmd->LMAExpr = readParenExpr();
753 if (consume("ALIGN"))
754 Cmd->AlignExpr = checkAlignment(readParenExpr(), Location);
755 if (consume("SUBALIGN"))
756 Cmd->SubalignExpr = checkAlignment(readParenExpr(), Location);
758 // Parse constraints.
759 if (consume("ONLY_IF_RO"))
760 Cmd->Constraint = ConstraintKind::ReadOnly;
761 if (consume("ONLY_IF_RW"))
762 Cmd->Constraint = ConstraintKind::ReadWrite;
765 while (!errorCount() && !consume("}")) {
766 StringRef Tok = next();
768 // Empty commands are allowed. Do nothing here.
769 } else if (SymbolAssignment *Assign = readAssignment(Tok)) {
770 Cmd->SectionCommands.push_back(Assign);
771 } else if (ByteCommand *Data = readByteCommand(Tok)) {
772 Cmd->SectionCommands.push_back(Data);
773 } else if (Tok == "CONSTRUCTORS") {
774 // CONSTRUCTORS is a keyword to make the linker recognize C++ ctors/dtors
775 // by name. This is for very old file formats such as ECOFF/XCOFF.
776 // For ELF, we should ignore.
777 } else if (Tok == "FILL") {
778 Cmd->Filler = readFill();
779 } else if (Tok == "SORT") {
781 } else if (peek() == "(") {
782 Cmd->SectionCommands.push_back(readInputSectionDescription(Tok));
784 setError("unknown command " + Tok);
789 Cmd->MemoryRegionName = next();
793 Cmd->LMARegionName = next();
796 if (Cmd->LMAExpr && !Cmd->LMARegionName.empty())
797 error("section can't have both LMA and a load region");
799 Cmd->Phdrs = readOutputSectionPhdrs();
802 Cmd->Filler = parseFill(next());
803 else if (peek().startswith("="))
804 Cmd->Filler = parseFill(next().drop_front());
806 // Consume optional comma following output section command.
809 if (Script->ReferencedSymbols.size() > SymbolsReferenced)
810 Cmd->ExpressionsUseSymbols = true;
814 // Parses a given string as a octal/decimal/hexadecimal number and
815 // returns it as a big-endian number. Used for `=<fillexp>`.
816 // https://sourceware.org/binutils/docs/ld/Output-Section-Fill.html
818 // When reading a hexstring, ld.bfd handles it as a blob of arbitrary
819 // size, while ld.gold always handles it as a 32-bit big-endian number.
820 // We are compatible with ld.gold because it's easier to implement.
821 uint32_t ScriptParser::parseFill(StringRef Tok) {
823 if (!to_integer(Tok, V))
824 setError("invalid filler expression: " + Tok);
831 SymbolAssignment *ScriptParser::readProvideHidden(bool Provide, bool Hidden) {
833 SymbolAssignment *Cmd = readSymbolAssignment(next());
834 Cmd->Provide = Provide;
835 Cmd->Hidden = Hidden;
840 SymbolAssignment *ScriptParser::readAssignment(StringRef Tok) {
841 // Assert expression returns Dot, so this is equal to ".=."
843 return make<SymbolAssignment>(".", readAssert(), getCurrentLocation());
846 SymbolAssignment *Cmd = nullptr;
847 if (peek() == "=" || peek() == "+=")
848 Cmd = readSymbolAssignment(Tok);
849 else if (Tok == "PROVIDE")
850 Cmd = readProvideHidden(true, false);
851 else if (Tok == "HIDDEN")
852 Cmd = readProvideHidden(false, true);
853 else if (Tok == "PROVIDE_HIDDEN")
854 Cmd = readProvideHidden(true, true);
859 llvm::join(Tokens.begin() + OldPos, Tokens.begin() + Pos, " ");
865 SymbolAssignment *ScriptParser::readSymbolAssignment(StringRef Name) {
866 StringRef Op = next();
867 assert(Op == "=" || Op == "+=");
870 std::string Loc = getCurrentLocation();
871 E = [=] { return add(Script->getSymbolValue(Name, Loc), E()); };
873 return make<SymbolAssignment>(Name, E, getCurrentLocation());
876 // This is an operator-precedence parser to parse a linker
877 // script expression.
878 Expr ScriptParser::readExpr() {
879 // Our lexer is context-aware. Set the in-expression bit so that
880 // they apply different tokenization rules.
883 Expr E = readExpr1(readPrimary(), 0);
888 Expr ScriptParser::combine(StringRef Op, Expr L, Expr R) {
890 return [=] { return add(L(), R()); };
892 return [=] { return sub(L(), R()); };
894 return [=] { return L().getValue() * R().getValue(); };
896 std::string Loc = getCurrentLocation();
897 return [=]() -> uint64_t {
898 if (uint64_t RV = R().getValue())
899 return L().getValue() / RV;
900 error(Loc + ": division by zero");
905 std::string Loc = getCurrentLocation();
906 return [=]() -> uint64_t {
907 if (uint64_t RV = R().getValue())
908 return L().getValue() % RV;
909 error(Loc + ": modulo by zero");
914 return [=] { return L().getValue() << R().getValue(); };
916 return [=] { return L().getValue() >> R().getValue(); };
918 return [=] { return L().getValue() < R().getValue(); };
920 return [=] { return L().getValue() > R().getValue(); };
922 return [=] { return L().getValue() >= R().getValue(); };
924 return [=] { return L().getValue() <= R().getValue(); };
926 return [=] { return L().getValue() == R().getValue(); };
928 return [=] { return L().getValue() != R().getValue(); };
930 return [=] { return L().getValue() || R().getValue(); };
932 return [=] { return L().getValue() && R().getValue(); };
934 return [=] { return bitAnd(L(), R()); };
936 return [=] { return bitOr(L(), R()); };
937 llvm_unreachable("invalid operator");
940 // This is a part of the operator-precedence parser. This function
941 // assumes that the remaining token stream starts with an operator.
942 Expr ScriptParser::readExpr1(Expr Lhs, int MinPrec) {
943 while (!atEOF() && !errorCount()) {
944 // Read an operator and an expression.
946 return readTernary(Lhs);
947 StringRef Op1 = peek();
948 if (precedence(Op1) < MinPrec)
951 Expr Rhs = readPrimary();
953 // Evaluate the remaining part of the expression first if the
954 // next operator has greater precedence than the previous one.
955 // For example, if we have read "+" and "3", and if the next
956 // operator is "*", then we'll evaluate 3 * ... part first.
958 StringRef Op2 = peek();
959 if (precedence(Op2) <= precedence(Op1))
961 Rhs = readExpr1(Rhs, precedence(Op2));
964 Lhs = combine(Op1, Lhs, Rhs);
969 Expr ScriptParser::getPageSize() {
970 std::string Location = getCurrentLocation();
971 return [=]() -> uint64_t {
973 return Target->PageSize;
974 error(Location + ": unable to calculate page size");
975 return 4096; // Return a dummy value.
979 Expr ScriptParser::readConstant() {
980 StringRef S = readParenLiteral();
981 if (S == "COMMONPAGESIZE")
982 return getPageSize();
983 if (S == "MAXPAGESIZE")
984 return [] { return Config->MaxPageSize; };
985 setError("unknown constant: " + S);
986 return [] { return 0; };
989 // Parses Tok as an integer. It recognizes hexadecimal (prefixed with
990 // "0x" or suffixed with "H") and decimal numbers. Decimal numbers may
991 // have "K" (Ki) or "M" (Mi) suffixes.
992 static Optional<uint64_t> parseInt(StringRef Tok) {
995 if (Tok.startswith_lower("0x")) {
996 if (!to_integer(Tok.substr(2), Val, 16))
1000 if (Tok.endswith_lower("H")) {
1001 if (!to_integer(Tok.drop_back(), Val, 16))
1007 if (Tok.endswith_lower("K")) {
1008 if (!to_integer(Tok.drop_back(), Val, 10))
1012 if (Tok.endswith_lower("M")) {
1013 if (!to_integer(Tok.drop_back(), Val, 10))
1015 return Val * 1024 * 1024;
1017 if (!to_integer(Tok, Val, 10))
1022 ByteCommand *ScriptParser::readByteCommand(StringRef Tok) {
1023 int Size = StringSwitch<int>(Tok)
1032 size_t OldPos = Pos;
1033 Expr E = readParenExpr();
1034 std::string CommandString =
1036 llvm::join(Tokens.begin() + OldPos, Tokens.begin() + Pos, " ");
1037 return make<ByteCommand>(E, Size, CommandString);
1040 StringRef ScriptParser::readParenLiteral() {
1044 StringRef Tok = next();
1050 static void checkIfExists(OutputSection *Cmd, StringRef Location) {
1051 if (Cmd->Location.empty() && Script->ErrorOnMissingSection)
1052 error(Location + ": undefined section " + Cmd->Name);
1055 Expr ScriptParser::readPrimary() {
1057 return readParenExpr();
1060 Expr E = readPrimary();
1061 return [=] { return ~E().getValue(); };
1064 Expr E = readPrimary();
1065 return [=] { return !E().getValue(); };
1068 Expr E = readPrimary();
1069 return [=] { return -E().getValue(); };
1072 StringRef Tok = next();
1073 std::string Location = getCurrentLocation();
1075 // Built-in functions are parsed here.
1076 // https://sourceware.org/binutils/docs/ld/Builtin-Functions.html.
1077 if (Tok == "ABSOLUTE") {
1078 Expr Inner = readParenExpr();
1080 ExprValue I = Inner();
1081 I.ForceAbsolute = true;
1085 if (Tok == "ADDR") {
1086 StringRef Name = readParenLiteral();
1087 OutputSection *Sec = Script->getOrCreateOutputSection(Name);
1088 return [=]() -> ExprValue {
1089 checkIfExists(Sec, Location);
1090 return {Sec, false, 0, Location};
1093 if (Tok == "ALIGN") {
1095 Expr E = readExpr();
1097 E = checkAlignment(E, Location);
1098 return [=] { return alignTo(Script->getDot(), E().getValue()); };
1101 Expr E2 = checkAlignment(readExpr(), Location);
1105 V.Alignment = E2().getValue();
1109 if (Tok == "ALIGNOF") {
1110 StringRef Name = readParenLiteral();
1111 OutputSection *Cmd = Script->getOrCreateOutputSection(Name);
1113 checkIfExists(Cmd, Location);
1114 return Cmd->Alignment;
1117 if (Tok == "ASSERT")
1118 return readAssert();
1119 if (Tok == "CONSTANT")
1120 return readConstant();
1121 if (Tok == "DATA_SEGMENT_ALIGN") {
1123 Expr E = readExpr();
1128 return alignTo(Script->getDot(), std::max((uint64_t)1, E().getValue()));
1131 if (Tok == "DATA_SEGMENT_END") {
1135 return [] { return Script->getDot(); };
1137 if (Tok == "DATA_SEGMENT_RELRO_END") {
1138 // GNU linkers implements more complicated logic to handle
1139 // DATA_SEGMENT_RELRO_END. We instead ignore the arguments and
1140 // just align to the next page boundary for simplicity.
1146 Expr E = getPageSize();
1147 return [=] { return alignTo(Script->getDot(), E().getValue()); };
1149 if (Tok == "DEFINED") {
1150 StringRef Name = readParenLiteral();
1151 return [=] { return Symtab->find(Name) ? 1 : 0; };
1153 if (Tok == "LENGTH") {
1154 StringRef Name = readParenLiteral();
1155 if (Script->MemoryRegions.count(Name) == 0) {
1156 setError("memory region not defined: " + Name);
1157 return [] { return 0; };
1159 return [=] { return Script->MemoryRegions[Name]->Length; };
1161 if (Tok == "LOADADDR") {
1162 StringRef Name = readParenLiteral();
1163 OutputSection *Cmd = Script->getOrCreateOutputSection(Name);
1165 checkIfExists(Cmd, Location);
1166 return Cmd->getLMA();
1169 if (Tok == "MAX" || Tok == "MIN") {
1171 Expr A = readExpr();
1173 Expr B = readExpr();
1176 return [=] { return std::min(A().getValue(), B().getValue()); };
1177 return [=] { return std::max(A().getValue(), B().getValue()); };
1179 if (Tok == "ORIGIN") {
1180 StringRef Name = readParenLiteral();
1181 if (Script->MemoryRegions.count(Name) == 0) {
1182 setError("memory region not defined: " + Name);
1183 return [] { return 0; };
1185 return [=] { return Script->MemoryRegions[Name]->Origin; };
1187 if (Tok == "SEGMENT_START") {
1191 Expr E = readExpr();
1193 return [=] { return E(); };
1195 if (Tok == "SIZEOF") {
1196 StringRef Name = readParenLiteral();
1197 OutputSection *Cmd = Script->getOrCreateOutputSection(Name);
1198 // Linker script does not create an output section if its content is empty.
1199 // We want to allow SIZEOF(.foo) where .foo is a section which happened to
1201 return [=] { return Cmd->Size; };
1203 if (Tok == "SIZEOF_HEADERS")
1204 return [=] { return elf::getHeaderSize(); };
1208 return [=] { return Script->getSymbolValue(Tok, Location); };
1210 // Tok is a literal number.
1211 if (Optional<uint64_t> Val = parseInt(Tok))
1212 return [=] { return *Val; };
1214 // Tok is a symbol name.
1215 if (!isValidCIdentifier(Tok))
1216 setError("malformed number: " + Tok);
1217 Script->ReferencedSymbols.push_back(Tok);
1218 return [=] { return Script->getSymbolValue(Tok, Location); };
1221 Expr ScriptParser::readTernary(Expr Cond) {
1222 Expr L = readExpr();
1224 Expr R = readExpr();
1225 return [=] { return Cond().getValue() ? L() : R(); };
1228 Expr ScriptParser::readParenExpr() {
1230 Expr E = readExpr();
1235 std::vector<StringRef> ScriptParser::readOutputSectionPhdrs() {
1236 std::vector<StringRef> Phdrs;
1237 while (!errorCount() && peek().startswith(":")) {
1238 StringRef Tok = next();
1239 Phdrs.push_back((Tok.size() == 1) ? next() : Tok.substr(1));
1244 // Read a program header type name. The next token must be a
1245 // name of a program header type or a constant (e.g. "0x3").
1246 unsigned ScriptParser::readPhdrType() {
1247 StringRef Tok = next();
1248 if (Optional<uint64_t> Val = parseInt(Tok))
1251 unsigned Ret = StringSwitch<unsigned>(Tok)
1252 .Case("PT_NULL", PT_NULL)
1253 .Case("PT_LOAD", PT_LOAD)
1254 .Case("PT_DYNAMIC", PT_DYNAMIC)
1255 .Case("PT_INTERP", PT_INTERP)
1256 .Case("PT_NOTE", PT_NOTE)
1257 .Case("PT_SHLIB", PT_SHLIB)
1258 .Case("PT_PHDR", PT_PHDR)
1259 .Case("PT_TLS", PT_TLS)
1260 .Case("PT_GNU_EH_FRAME", PT_GNU_EH_FRAME)
1261 .Case("PT_GNU_STACK", PT_GNU_STACK)
1262 .Case("PT_GNU_RELRO", PT_GNU_RELRO)
1263 .Case("PT_OPENBSD_RANDOMIZE", PT_OPENBSD_RANDOMIZE)
1264 .Case("PT_OPENBSD_WXNEEDED", PT_OPENBSD_WXNEEDED)
1265 .Case("PT_OPENBSD_BOOTDATA", PT_OPENBSD_BOOTDATA)
1268 if (Ret == (unsigned)-1) {
1269 setError("invalid program header type: " + Tok);
1275 // Reads an anonymous version declaration.
1276 void ScriptParser::readAnonymousDeclaration() {
1277 std::vector<SymbolVersion> Locals;
1278 std::vector<SymbolVersion> Globals;
1279 std::tie(Locals, Globals) = readSymbols();
1281 for (SymbolVersion V : Locals) {
1283 Config->DefaultSymbolVersion = VER_NDX_LOCAL;
1285 Config->VersionScriptLocals.push_back(V);
1288 for (SymbolVersion V : Globals)
1289 Config->VersionScriptGlobals.push_back(V);
1294 // Reads a non-anonymous version definition,
1295 // e.g. "VerStr { global: foo; bar; local: *; };".
1296 void ScriptParser::readVersionDeclaration(StringRef VerStr) {
1297 // Read a symbol list.
1298 std::vector<SymbolVersion> Locals;
1299 std::vector<SymbolVersion> Globals;
1300 std::tie(Locals, Globals) = readSymbols();
1302 for (SymbolVersion V : Locals) {
1304 Config->DefaultSymbolVersion = VER_NDX_LOCAL;
1306 Config->VersionScriptLocals.push_back(V);
1309 // Create a new version definition and add that to the global symbols.
1310 VersionDefinition Ver;
1312 Ver.Globals = Globals;
1314 // User-defined version number starts from 2 because 0 and 1 are
1315 // reserved for VER_NDX_LOCAL and VER_NDX_GLOBAL, respectively.
1316 Ver.Id = Config->VersionDefinitions.size() + 2;
1317 Config->VersionDefinitions.push_back(Ver);
1319 // Each version may have a parent version. For example, "Ver2"
1320 // defined as "Ver2 { global: foo; local: *; } Ver1;" has "Ver1"
1321 // as a parent. This version hierarchy is, probably against your
1322 // instinct, purely for hint; the runtime doesn't care about it
1323 // at all. In LLD, we simply ignore it.
1329 static bool hasWildcard(StringRef S) {
1330 return S.find_first_of("?*[") != StringRef::npos;
1333 // Reads a list of symbols, e.g. "{ global: foo; bar; local: *; };".
1334 std::pair<std::vector<SymbolVersion>, std::vector<SymbolVersion>>
1335 ScriptParser::readSymbols() {
1336 std::vector<SymbolVersion> Locals;
1337 std::vector<SymbolVersion> Globals;
1338 std::vector<SymbolVersion> *V = &Globals;
1340 while (!errorCount()) {
1343 if (consumeLabel("local")) {
1347 if (consumeLabel("global")) {
1352 if (consume("extern")) {
1353 std::vector<SymbolVersion> Ext = readVersionExtern();
1354 V->insert(V->end(), Ext.begin(), Ext.end());
1356 StringRef Tok = next();
1357 V->push_back({unquote(Tok), false, hasWildcard(Tok)});
1361 return {Locals, Globals};
1364 // Reads an "extern C++" directive, e.g.,
1365 // "extern "C++" { ns::*; "f(int, double)"; };"
1367 // The last semicolon is optional. E.g. this is OK:
1368 // "extern "C++" { ns::*; "f(int, double)" };"
1369 std::vector<SymbolVersion> ScriptParser::readVersionExtern() {
1370 StringRef Tok = next();
1371 bool IsCXX = Tok == "\"C++\"";
1372 if (!IsCXX && Tok != "\"C\"")
1373 setError("Unknown language");
1376 std::vector<SymbolVersion> Ret;
1377 while (!errorCount() && peek() != "}") {
1378 StringRef Tok = next();
1379 bool HasWildcard = !Tok.startswith("\"") && hasWildcard(Tok);
1380 Ret.push_back({unquote(Tok), IsCXX, HasWildcard});
1390 uint64_t ScriptParser::readMemoryAssignment(StringRef S1, StringRef S2,
1392 if (!consume(S1) && !consume(S2) && !consume(S3)) {
1393 setError("expected one of: " + S1 + ", " + S2 + ", or " + S3);
1397 return readExpr()().getValue();
1400 // Parse the MEMORY command as specified in:
1401 // https://sourceware.org/binutils/docs/ld/MEMORY.html
1403 // MEMORY { name [(attr)] : ORIGIN = origin, LENGTH = len ... }
1404 void ScriptParser::readMemory() {
1406 while (!errorCount() && !consume("}")) {
1407 StringRef Name = next();
1410 uint32_t NegFlags = 0;
1412 std::tie(Flags, NegFlags) = readMemoryAttributes();
1417 uint64_t Origin = readMemoryAssignment("ORIGIN", "org", "o");
1419 uint64_t Length = readMemoryAssignment("LENGTH", "len", "l");
1421 // Add the memory region to the region map.
1423 make<MemoryRegion>(Name, Origin, Length, Flags, NegFlags);
1424 if (!Script->MemoryRegions.insert({Name, MR}).second)
1425 setError("region '" + Name + "' already defined");
1429 // This function parses the attributes used to match against section
1430 // flags when placing output sections in a memory region. These flags
1431 // are only used when an explicit memory region name is not used.
1432 std::pair<uint32_t, uint32_t> ScriptParser::readMemoryAttributes() {
1434 uint32_t NegFlags = 0;
1435 bool Invert = false;
1437 for (char C : next().lower()) {
1444 Flag = SHF_EXECINSTR;
1448 setError("invalid memory region attribute");
1455 return {Flags, NegFlags};
1458 void elf::readLinkerScript(MemoryBufferRef MB) {
1459 ScriptParser(MB).readLinkerScript();
1462 void elf::readVersionScript(MemoryBufferRef MB) {
1463 ScriptParser(MB).readVersionScript();
1466 void elf::readDynamicList(MemoryBufferRef MB) {
1467 ScriptParser(MB).readDynamicList();
1470 void elf::readDefsym(StringRef Name, MemoryBufferRef MB) {
1471 ScriptParser(MB).readDefsym(Name);