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+//===- ScriptParser.cpp ---------------------------------------------------===//
+//
+// The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains a recursive-descendent parser for linker scripts.
+// Parsed results are stored to Config and Script global objects.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ScriptParser.h"
+#include "Config.h"
+#include "Driver.h"
+#include "InputSection.h"
+#include "LinkerScript.h"
+#include "Memory.h"
+#include "OutputSections.h"
+#include "ScriptLexer.h"
+#include "Symbols.h"
+#include "Target.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/StringSwitch.h"
+#include "llvm/BinaryFormat/ELF.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/Path.h"
+#include <cassert>
+#include <limits>
+#include <vector>
+
+using namespace llvm;
+using namespace llvm::ELF;
+using namespace llvm::support::endian;
+using namespace lld;
+using namespace lld::elf;
+
+static bool isUnderSysroot(StringRef Path);
+
+namespace {
+class ScriptParser final : ScriptLexer {
+public:
+ ScriptParser(MemoryBufferRef MB)
+ : ScriptLexer(MB),
+ IsUnderSysroot(isUnderSysroot(MB.getBufferIdentifier())) {}
+
+ void readLinkerScript();
+ void readVersionScript();
+ void readDynamicList();
+
+private:
+ void addFile(StringRef Path);
+ OutputSection *checkSection(OutputSectionCommand *Cmd, StringRef Loccation);
+
+ void readAsNeeded();
+ void readEntry();
+ void readExtern();
+ void readGroup();
+ void readInclude();
+ void readMemory();
+ void readOutput();
+ void readOutputArch();
+ void readOutputFormat();
+ void readPhdrs();
+ void readSearchDir();
+ void readSections();
+ void readVersion();
+ void readVersionScriptCommand();
+
+ SymbolAssignment *readAssignment(StringRef Name);
+ BytesDataCommand *readBytesDataCommand(StringRef Tok);
+ uint32_t readFill();
+ uint32_t parseFill(StringRef Tok);
+ void readSectionAddressType(OutputSectionCommand *Cmd);
+ OutputSectionCommand *readOutputSectionDescription(StringRef OutSec);
+ std::vector<StringRef> readOutputSectionPhdrs();
+ InputSectionDescription *readInputSectionDescription(StringRef Tok);
+ StringMatcher readFilePatterns();
+ std::vector<SectionPattern> readInputSectionsList();
+ InputSectionDescription *readInputSectionRules(StringRef FilePattern);
+ unsigned readPhdrType();
+ SortSectionPolicy readSortKind();
+ SymbolAssignment *readProvideHidden(bool Provide, bool Hidden);
+ SymbolAssignment *readProvideOrAssignment(StringRef Tok);
+ void readSort();
+ AssertCommand *readAssert();
+ Expr readAssertExpr();
+
+ uint64_t readMemoryAssignment(StringRef, StringRef, StringRef);
+ std::pair<uint32_t, uint32_t> readMemoryAttributes();
+
+ Expr readExpr();
+ Expr readExpr1(Expr Lhs, int MinPrec);
+ StringRef readParenLiteral();
+ Expr readPrimary();
+ Expr readTernary(Expr Cond);
+ Expr readParenExpr();
+
+ // For parsing version script.
+ std::vector<SymbolVersion> readVersionExtern();
+ void readAnonymousDeclaration();
+ void readVersionDeclaration(StringRef VerStr);
+
+ std::pair<std::vector<SymbolVersion>, std::vector<SymbolVersion>>
+ readSymbols();
+
+ bool IsUnderSysroot;
+};
+} // namespace
+
+static StringRef unquote(StringRef S) {
+ if (S.startswith("\""))
+ return S.substr(1, S.size() - 2);
+ return S;
+}
+
+static bool isUnderSysroot(StringRef Path) {
+ if (Config->Sysroot == "")
+ return false;
+ for (; !Path.empty(); Path = sys::path::parent_path(Path))
+ if (sys::fs::equivalent(Config->Sysroot, Path))
+ return true;
+ return false;
+}
+
+// Some operations only support one non absolute value. Move the
+// absolute one to the right hand side for convenience.
+static void moveAbsRight(ExprValue &A, ExprValue &B) {
+ if (A.isAbsolute())
+ std::swap(A, B);
+ if (!B.isAbsolute())
+ error(A.Loc + ": at least one side of the expression must be absolute");
+}
+
+static ExprValue add(ExprValue A, ExprValue B) {
+ moveAbsRight(A, B);
+ return {A.Sec, A.ForceAbsolute, A.Val + B.getValue(), A.Loc};
+}
+
+static ExprValue sub(ExprValue A, ExprValue B) {
+ return {A.Sec, A.Val - B.getValue(), A.Loc};
+}
+
+static ExprValue mul(ExprValue A, ExprValue B) {
+ return A.getValue() * B.getValue();
+}
+
+static ExprValue div(ExprValue A, ExprValue B) {
+ if (uint64_t BV = B.getValue())
+ return A.getValue() / BV;
+ error("division by zero");
+ return 0;
+}
+
+static ExprValue bitAnd(ExprValue A, ExprValue B) {
+ moveAbsRight(A, B);
+ return {A.Sec, A.ForceAbsolute,
+ (A.getValue() & B.getValue()) - A.getSecAddr(), A.Loc};
+}
+
+static ExprValue bitOr(ExprValue A, ExprValue B) {
+ moveAbsRight(A, B);
+ return {A.Sec, A.ForceAbsolute,
+ (A.getValue() | B.getValue()) - A.getSecAddr(), A.Loc};
+}
+
+void ScriptParser::readDynamicList() {
+ expect("{");
+ readAnonymousDeclaration();
+ if (!atEOF())
+ setError("EOF expected, but got " + next());
+}
+
+void ScriptParser::readVersionScript() {
+ readVersionScriptCommand();
+ if (!atEOF())
+ setError("EOF expected, but got " + next());
+}
+
+void ScriptParser::readVersionScriptCommand() {
+ if (consume("{")) {
+ readAnonymousDeclaration();
+ return;
+ }
+
+ while (!atEOF() && !Error && peek() != "}") {
+ StringRef VerStr = next();
+ if (VerStr == "{") {
+ setError("anonymous version definition is used in "
+ "combination with other version definitions");
+ return;
+ }
+ expect("{");
+ readVersionDeclaration(VerStr);
+ }
+}
+
+void ScriptParser::readVersion() {
+ expect("{");
+ readVersionScriptCommand();
+ expect("}");
+}
+
+void ScriptParser::readLinkerScript() {
+ while (!atEOF()) {
+ StringRef Tok = next();
+ if (Tok == ";")
+ continue;
+
+ if (Tok == "ASSERT") {
+ Script->Opt.Commands.push_back(readAssert());
+ } else if (Tok == "ENTRY") {
+ readEntry();
+ } else if (Tok == "EXTERN") {
+ readExtern();
+ } else if (Tok == "GROUP" || Tok == "INPUT") {
+ readGroup();
+ } else if (Tok == "INCLUDE") {
+ readInclude();
+ } else if (Tok == "MEMORY") {
+ readMemory();
+ } else if (Tok == "OUTPUT") {
+ readOutput();
+ } else if (Tok == "OUTPUT_ARCH") {
+ readOutputArch();
+ } else if (Tok == "OUTPUT_FORMAT") {
+ readOutputFormat();
+ } else if (Tok == "PHDRS") {
+ readPhdrs();
+ } else if (Tok == "SEARCH_DIR") {
+ readSearchDir();
+ } else if (Tok == "SECTIONS") {
+ readSections();
+ } else if (Tok == "VERSION") {
+ readVersion();
+ } else if (SymbolAssignment *Cmd = readProvideOrAssignment(Tok)) {
+ Script->Opt.Commands.push_back(Cmd);
+ } else {
+ setError("unknown directive: " + Tok);
+ }
+ }
+}
+
+void ScriptParser::addFile(StringRef S) {
+ if (IsUnderSysroot && S.startswith("/")) {
+ SmallString<128> PathData;
+ StringRef Path = (Config->Sysroot + S).toStringRef(PathData);
+ if (sys::fs::exists(Path)) {
+ Driver->addFile(Saver.save(Path), /*WithLOption=*/false);
+ return;
+ }
+ }
+
+ if (sys::path::is_absolute(S)) {
+ Driver->addFile(S, /*WithLOption=*/false);
+ } else if (S.startswith("=")) {
+ if (Config->Sysroot.empty())
+ Driver->addFile(S.substr(1), /*WithLOption=*/false);
+ else
+ Driver->addFile(Saver.save(Config->Sysroot + "/" + S.substr(1)),
+ /*WithLOption=*/false);
+ } else if (S.startswith("-l")) {
+ Driver->addLibrary(S.substr(2));
+ } else if (sys::fs::exists(S)) {
+ Driver->addFile(S, /*WithLOption=*/false);
+ } else {
+ if (Optional<std::string> Path = findFromSearchPaths(S))
+ Driver->addFile(Saver.save(*Path), /*WithLOption=*/true);
+ else
+ setError("unable to find " + S);
+ }
+}
+
+void ScriptParser::readAsNeeded() {
+ expect("(");
+ bool Orig = Config->AsNeeded;
+ Config->AsNeeded = true;
+ while (!Error && !consume(")"))
+ addFile(unquote(next()));
+ Config->AsNeeded = Orig;
+}
+
+void ScriptParser::readEntry() {
+ // -e <symbol> takes predecence over ENTRY(<symbol>).
+ expect("(");
+ StringRef Tok = next();
+ if (Config->Entry.empty())
+ Config->Entry = Tok;
+ expect(")");
+}
+
+void ScriptParser::readExtern() {
+ expect("(");
+ while (!Error && !consume(")"))
+ Config->Undefined.push_back(next());
+}
+
+void ScriptParser::readGroup() {
+ expect("(");
+ while (!Error && !consume(")")) {
+ if (consume("AS_NEEDED"))
+ readAsNeeded();
+ else
+ addFile(unquote(next()));
+ }
+}
+
+void ScriptParser::readInclude() {
+ StringRef Tok = unquote(next());
+
+ // https://sourceware.org/binutils/docs/ld/File-Commands.html:
+ // The file will be searched for in the current directory, and in any
+ // directory specified with the -L option.
+ if (sys::fs::exists(Tok)) {
+ if (Optional<MemoryBufferRef> MB = readFile(Tok))
+ tokenize(*MB);
+ return;
+ }
+ if (Optional<std::string> Path = findFromSearchPaths(Tok)) {
+ if (Optional<MemoryBufferRef> MB = readFile(*Path))
+ tokenize(*MB);
+ return;
+ }
+ setError("cannot open " + Tok);
+}
+
+void ScriptParser::readOutput() {
+ // -o <file> takes predecence over OUTPUT(<file>).
+ expect("(");
+ StringRef Tok = next();
+ if (Config->OutputFile.empty())
+ Config->OutputFile = unquote(Tok);
+ expect(")");
+}
+
+void ScriptParser::readOutputArch() {
+ // OUTPUT_ARCH is ignored for now.
+ expect("(");
+ while (!Error && !consume(")"))
+ skip();
+}
+
+void ScriptParser::readOutputFormat() {
+ // Error checking only for now.
+ expect("(");
+ skip();
+ if (consume(")"))
+ return;
+ expect(",");
+ skip();
+ expect(",");
+ skip();
+ expect(")");
+}
+
+void ScriptParser::readPhdrs() {
+ expect("{");
+ while (!Error && !consume("}")) {
+ Script->Opt.PhdrsCommands.push_back(
+ {next(), PT_NULL, false, false, UINT_MAX, nullptr});
+
+ PhdrsCommand &PhdrCmd = Script->Opt.PhdrsCommands.back();
+ PhdrCmd.Type = readPhdrType();
+
+ while (!Error && !consume(";")) {
+ if (consume("FILEHDR"))
+ PhdrCmd.HasFilehdr = true;
+ else if (consume("PHDRS"))
+ PhdrCmd.HasPhdrs = true;
+ else if (consume("AT"))
+ PhdrCmd.LMAExpr = readParenExpr();
+ else if (consume("FLAGS"))
+ PhdrCmd.Flags = readParenExpr()().getValue();
+ else
+ setError("unexpected header attribute: " + next());
+ }
+ }
+}
+
+void ScriptParser::readSearchDir() {
+ expect("(");
+ StringRef Tok = next();
+ if (!Config->Nostdlib)
+ Config->SearchPaths.push_back(unquote(Tok));
+ expect(")");
+}
+
+void ScriptParser::readSections() {
+ Script->Opt.HasSections = true;
+
+ // -no-rosegment is used to avoid placing read only non-executable sections in
+ // their own segment. We do the same if SECTIONS command is present in linker
+ // script. See comment for computeFlags().
+ Config->SingleRoRx = true;
+
+ expect("{");
+ while (!Error && !consume("}")) {
+ StringRef Tok = next();
+ BaseCommand *Cmd = readProvideOrAssignment(Tok);
+ if (!Cmd) {
+ if (Tok == "ASSERT")
+ Cmd = readAssert();
+ else
+ Cmd = readOutputSectionDescription(Tok);
+ }
+ Script->Opt.Commands.push_back(Cmd);
+ }
+}
+
+static int precedence(StringRef Op) {
+ return StringSwitch<int>(Op)
+ .Cases("*", "/", 5)
+ .Cases("+", "-", 4)
+ .Cases("<<", ">>", 3)
+ .Cases("<", "<=", ">", ">=", "==", "!=", 2)
+ .Cases("&", "|", 1)
+ .Default(-1);
+}
+
+StringMatcher ScriptParser::readFilePatterns() {
+ std::vector<StringRef> V;
+ while (!Error && !consume(")"))
+ V.push_back(next());
+ return StringMatcher(V);
+}
+
+SortSectionPolicy ScriptParser::readSortKind() {
+ if (consume("SORT") || consume("SORT_BY_NAME"))
+ return SortSectionPolicy::Name;
+ if (consume("SORT_BY_ALIGNMENT"))
+ return SortSectionPolicy::Alignment;
+ if (consume("SORT_BY_INIT_PRIORITY"))
+ return SortSectionPolicy::Priority;
+ if (consume("SORT_NONE"))
+ return SortSectionPolicy::None;
+ return SortSectionPolicy::Default;
+}
+
+// Reads SECTIONS command contents in the following form:
+//
+// <contents> ::= <elem>*
+// <elem> ::= <exclude>? <glob-pattern>
+// <exclude> ::= "EXCLUDE_FILE" "(" <glob-pattern>+ ")"
+//
+// For example,
+//
+// *(.foo EXCLUDE_FILE (a.o) .bar EXCLUDE_FILE (b.o) .baz)
+//
+// is parsed as ".foo", ".bar" with "a.o", and ".baz" with "b.o".
+// The semantics of that is section .foo in any file, section .bar in
+// any file but a.o, and section .baz in any file but b.o.
+std::vector<SectionPattern> ScriptParser::readInputSectionsList() {
+ std::vector<SectionPattern> Ret;
+ while (!Error && peek() != ")") {
+ StringMatcher ExcludeFilePat;
+ if (consume("EXCLUDE_FILE")) {
+ expect("(");
+ ExcludeFilePat = readFilePatterns();
+ }
+
+ std::vector<StringRef> V;
+ while (!Error && peek() != ")" && peek() != "EXCLUDE_FILE")
+ V.push_back(next());
+
+ if (!V.empty())
+ Ret.push_back({std::move(ExcludeFilePat), StringMatcher(V)});
+ else
+ setError("section pattern is expected");
+ }
+ return Ret;
+}
+
+// Reads contents of "SECTIONS" directive. That directive contains a
+// list of glob patterns for input sections. The grammar is as follows.
+//
+// <patterns> ::= <section-list>
+// | <sort> "(" <section-list> ")"
+// | <sort> "(" <sort> "(" <section-list> ")" ")"
+//
+// <sort> ::= "SORT" | "SORT_BY_NAME" | "SORT_BY_ALIGNMENT"
+// | "SORT_BY_INIT_PRIORITY" | "SORT_NONE"
+//
+// <section-list> is parsed by readInputSectionsList().
+InputSectionDescription *
+ScriptParser::readInputSectionRules(StringRef FilePattern) {
+ auto *Cmd = make<InputSectionDescription>(FilePattern);
+ expect("(");
+
+ while (!Error && !consume(")")) {
+ SortSectionPolicy Outer = readSortKind();
+ SortSectionPolicy Inner = SortSectionPolicy::Default;
+ std::vector<SectionPattern> V;
+ if (Outer != SortSectionPolicy::Default) {
+ expect("(");
+ Inner = readSortKind();
+ if (Inner != SortSectionPolicy::Default) {
+ expect("(");
+ V = readInputSectionsList();
+ expect(")");
+ } else {
+ V = readInputSectionsList();
+ }
+ expect(")");
+ } else {
+ V = readInputSectionsList();
+ }
+
+ for (SectionPattern &Pat : V) {
+ Pat.SortInner = Inner;
+ Pat.SortOuter = Outer;
+ }
+
+ std::move(V.begin(), V.end(), std::back_inserter(Cmd->SectionPatterns));
+ }
+ return Cmd;
+}
+
+InputSectionDescription *
+ScriptParser::readInputSectionDescription(StringRef Tok) {
+ // Input section wildcard can be surrounded by KEEP.
+ // https://sourceware.org/binutils/docs/ld/Input-Section-Keep.html#Input-Section-Keep
+ if (Tok == "KEEP") {
+ expect("(");
+ StringRef FilePattern = next();
+ InputSectionDescription *Cmd = readInputSectionRules(FilePattern);
+ expect(")");
+ Script->Opt.KeptSections.push_back(Cmd);
+ return Cmd;
+ }
+ return readInputSectionRules(Tok);
+}
+
+void ScriptParser::readSort() {
+ expect("(");
+ expect("CONSTRUCTORS");
+ expect(")");
+}
+
+AssertCommand *ScriptParser::readAssert() {
+ return make<AssertCommand>(readAssertExpr());
+}
+
+Expr ScriptParser::readAssertExpr() {
+ expect("(");
+ Expr E = readExpr();
+ expect(",");
+ StringRef Msg = unquote(next());
+ expect(")");
+
+ return [=] {
+ if (!E().getValue())
+ error(Msg);
+ return Script->getDot();
+ };
+}
+
+// Reads a FILL(expr) command. We handle the FILL command as an
+// alias for =fillexp section attribute, which is different from
+// what GNU linkers do.
+// https://sourceware.org/binutils/docs/ld/Output-Section-Data.html
+uint32_t ScriptParser::readFill() {
+ expect("(");
+ uint32_t V = parseFill(next());
+ expect(")");
+ return V;
+}
+
+// Reads an expression and/or the special directive "(NOLOAD)" for an
+// output section definition.
+//
+// An output section name can be followed by an address expression
+// and/or by "(NOLOAD)". This grammar is not LL(1) because "(" can be
+// interpreted as either the beginning of some expression or "(NOLOAD)".
+//
+// https://sourceware.org/binutils/docs/ld/Output-Section-Address.html
+// https://sourceware.org/binutils/docs/ld/Output-Section-Type.html
+void ScriptParser::readSectionAddressType(OutputSectionCommand *Cmd) {
+ if (consume("(")) {
+ if (consume("NOLOAD")) {
+ expect(")");
+ Cmd->Noload = true;
+ return;
+ }
+ Cmd->AddrExpr = readExpr();
+ expect(")");
+ } else {
+ Cmd->AddrExpr = readExpr();
+ }
+
+ if (consume("(")) {
+ expect("NOLOAD");
+ expect(")");
+ Cmd->Noload = true;
+ }
+}
+
+OutputSectionCommand *
+ScriptParser::readOutputSectionDescription(StringRef OutSec) {
+ OutputSectionCommand *Cmd =
+ Script->createOutputSectionCommand(OutSec, getCurrentLocation());
+
+ if (peek() != ":")
+ readSectionAddressType(Cmd);
+ expect(":");
+
+ if (consume("AT"))
+ Cmd->LMAExpr = readParenExpr();
+ if (consume("ALIGN"))
+ Cmd->AlignExpr = readParenExpr();
+ if (consume("SUBALIGN"))
+ Cmd->SubalignExpr = readParenExpr();
+
+ // Parse constraints.
+ if (consume("ONLY_IF_RO"))
+ Cmd->Constraint = ConstraintKind::ReadOnly;
+ if (consume("ONLY_IF_RW"))
+ Cmd->Constraint = ConstraintKind::ReadWrite;
+ expect("{");
+
+ while (!Error && !consume("}")) {
+ StringRef Tok = next();
+ if (Tok == ";") {
+ // Empty commands are allowed. Do nothing here.
+ } else if (SymbolAssignment *Assign = readProvideOrAssignment(Tok)) {
+ Cmd->Commands.push_back(Assign);
+ } else if (BytesDataCommand *Data = readBytesDataCommand(Tok)) {
+ Cmd->Commands.push_back(Data);
+ } else if (Tok == "ASSERT") {
+ Cmd->Commands.push_back(readAssert());
+ expect(";");
+ } else if (Tok == "CONSTRUCTORS") {
+ // CONSTRUCTORS is a keyword to make the linker recognize C++ ctors/dtors
+ // by name. This is for very old file formats such as ECOFF/XCOFF.
+ // For ELF, we should ignore.
+ } else if (Tok == "FILL") {
+ Cmd->Filler = readFill();
+ } else if (Tok == "SORT") {
+ readSort();
+ } else if (peek() == "(") {
+ Cmd->Commands.push_back(readInputSectionDescription(Tok));
+ } else {
+ setError("unknown command " + Tok);
+ }
+ }
+
+ if (consume(">"))
+ Cmd->MemoryRegionName = next();
+
+ Cmd->Phdrs = readOutputSectionPhdrs();
+
+ if (consume("="))
+ Cmd->Filler = parseFill(next());
+ else if (peek().startswith("="))
+ Cmd->Filler = parseFill(next().drop_front());
+
+ // Consume optional comma following output section command.
+ consume(",");
+
+ return Cmd;
+}
+
+// Parses a given string as a octal/decimal/hexadecimal number and
+// returns it as a big-endian number. Used for `=<fillexp>`.
+// https://sourceware.org/binutils/docs/ld/Output-Section-Fill.html
+//
+// When reading a hexstring, ld.bfd handles it as a blob of arbitrary
+// size, while ld.gold always handles it as a 32-bit big-endian number.
+// We are compatible with ld.gold because it's easier to implement.
+uint32_t ScriptParser::parseFill(StringRef Tok) {
+ uint32_t V = 0;
+ if (!to_integer(Tok, V))
+ setError("invalid filler expression: " + Tok);
+
+ uint32_t Buf;
+ write32be(&Buf, V);
+ return Buf;
+}
+
+SymbolAssignment *ScriptParser::readProvideHidden(bool Provide, bool Hidden) {
+ expect("(");
+ SymbolAssignment *Cmd = readAssignment(next());
+ Cmd->Provide = Provide;
+ Cmd->Hidden = Hidden;
+ expect(")");
+ expect(";");
+ return Cmd;
+}
+
+SymbolAssignment *ScriptParser::readProvideOrAssignment(StringRef Tok) {
+ SymbolAssignment *Cmd = nullptr;
+ if (peek() == "=" || peek() == "+=") {
+ Cmd = readAssignment(Tok);
+ expect(";");
+ } else if (Tok == "PROVIDE") {
+ Cmd = readProvideHidden(true, false);
+ } else if (Tok == "HIDDEN") {
+ Cmd = readProvideHidden(false, true);
+ } else if (Tok == "PROVIDE_HIDDEN") {
+ Cmd = readProvideHidden(true, true);
+ }
+ return Cmd;
+}
+
+SymbolAssignment *ScriptParser::readAssignment(StringRef Name) {
+ StringRef Op = next();
+ assert(Op == "=" || Op == "+=");
+ Expr E = readExpr();
+ if (Op == "+=") {
+ std::string Loc = getCurrentLocation();
+ E = [=] { return add(Script->getSymbolValue(Loc, Name), E()); };
+ }
+ return make<SymbolAssignment>(Name, E, getCurrentLocation());
+}
+
+// This is an operator-precedence parser to parse a linker
+// script expression.
+Expr ScriptParser::readExpr() {
+ // Our lexer is context-aware. Set the in-expression bit so that
+ // they apply different tokenization rules.
+ bool Orig = InExpr;
+ InExpr = true;
+ Expr E = readExpr1(readPrimary(), 0);
+ InExpr = Orig;
+ return E;
+}
+
+static Expr combine(StringRef Op, Expr L, Expr R) {
+ if (Op == "+")
+ return [=] { return add(L(), R()); };
+ if (Op == "-")
+ return [=] { return sub(L(), R()); };
+ if (Op == "*")
+ return [=] { return mul(L(), R()); };
+ if (Op == "/")
+ return [=] { return div(L(), R()); };
+ if (Op == "<<")
+ return [=] { return L().getValue() << R().getValue(); };
+ if (Op == ">>")
+ return [=] { return L().getValue() >> R().getValue(); };
+ if (Op == "<")
+ return [=] { return L().getValue() < R().getValue(); };
+ if (Op == ">")
+ return [=] { return L().getValue() > R().getValue(); };
+ if (Op == ">=")
+ return [=] { return L().getValue() >= R().getValue(); };
+ if (Op == "<=")
+ return [=] { return L().getValue() <= R().getValue(); };
+ if (Op == "==")
+ return [=] { return L().getValue() == R().getValue(); };
+ if (Op == "!=")
+ return [=] { return L().getValue() != R().getValue(); };
+ if (Op == "&")
+ return [=] { return bitAnd(L(), R()); };
+ if (Op == "|")
+ return [=] { return bitOr(L(), R()); };
+ llvm_unreachable("invalid operator");
+}
+
+// This is a part of the operator-precedence parser. This function
+// assumes that the remaining token stream starts with an operator.
+Expr ScriptParser::readExpr1(Expr Lhs, int MinPrec) {
+ while (!atEOF() && !Error) {
+ // Read an operator and an expression.
+ if (consume("?"))
+ return readTernary(Lhs);
+ StringRef Op1 = peek();
+ if (precedence(Op1) < MinPrec)
+ break;
+ skip();
+ Expr Rhs = readPrimary();
+
+ // Evaluate the remaining part of the expression first if the
+ // next operator has greater precedence than the previous one.
+ // For example, if we have read "+" and "3", and if the next
+ // operator is "*", then we'll evaluate 3 * ... part first.
+ while (!atEOF()) {
+ StringRef Op2 = peek();
+ if (precedence(Op2) <= precedence(Op1))
+ break;
+ Rhs = readExpr1(Rhs, precedence(Op2));
+ }
+
+ Lhs = combine(Op1, Lhs, Rhs);
+ }
+ return Lhs;
+}
+
+uint64_t static getConstant(StringRef S) {
+ if (S == "COMMONPAGESIZE")
+ return Target->PageSize;
+ if (S == "MAXPAGESIZE")
+ return Config->MaxPageSize;
+ error("unknown constant: " + S);
+ return 0;
+}
+
+// Parses Tok as an integer. It recognizes hexadecimal (prefixed with
+// "0x" or suffixed with "H") and decimal numbers. Decimal numbers may
+// have "K" (Ki) or "M" (Mi) suffixes.
+static Optional<uint64_t> parseInt(StringRef Tok) {
+ // Negative number
+ if (Tok.startswith("-")) {
+ if (Optional<uint64_t> Val = parseInt(Tok.substr(1)))
+ return -*Val;
+ return None;
+ }
+
+ // Hexadecimal
+ uint64_t Val;
+ if (Tok.startswith_lower("0x") && to_integer(Tok.substr(2), Val, 16))
+ return Val;
+ if (Tok.endswith_lower("H") && to_integer(Tok.drop_back(), Val, 16))
+ return Val;
+
+ // Decimal
+ if (Tok.endswith_lower("K")) {
+ if (!to_integer(Tok.drop_back(), Val, 10))
+ return None;
+ return Val * 1024;
+ }
+ if (Tok.endswith_lower("M")) {
+ if (!to_integer(Tok.drop_back(), Val, 10))
+ return None;
+ return Val * 1024 * 1024;
+ }
+ if (!to_integer(Tok, Val, 10))
+ return None;
+ return Val;
+}
+
+BytesDataCommand *ScriptParser::readBytesDataCommand(StringRef Tok) {
+ int Size = StringSwitch<int>(Tok)
+ .Case("BYTE", 1)
+ .Case("SHORT", 2)
+ .Case("LONG", 4)
+ .Case("QUAD", 8)
+ .Default(-1);
+ if (Size == -1)
+ return nullptr;
+
+ return make<BytesDataCommand>(readParenExpr(), Size);
+}
+
+StringRef ScriptParser::readParenLiteral() {
+ expect("(");
+ StringRef Tok = next();
+ expect(")");
+ return Tok;
+}
+
+OutputSection *ScriptParser::checkSection(OutputSectionCommand *Cmd,
+ StringRef Location) {
+ if (Cmd->Location.empty() && Script->ErrorOnMissingSection)
+ error(Location + ": undefined section " + Cmd->Name);
+ if (Cmd->Sec)
+ return Cmd->Sec;
+ static OutputSection Dummy("", 0, 0);
+ return &Dummy;
+}
+
+Expr ScriptParser::readPrimary() {
+ if (peek() == "(")
+ return readParenExpr();
+
+ if (consume("~")) {
+ Expr E = readPrimary();
+ return [=] { return ~E().getValue(); };
+ }
+ if (consume("-")) {
+ Expr E = readPrimary();
+ return [=] { return -E().getValue(); };
+ }
+
+ StringRef Tok = next();
+ std::string Location = getCurrentLocation();
+
+ // Built-in functions are parsed here.
+ // https://sourceware.org/binutils/docs/ld/Builtin-Functions.html.
+ if (Tok == "ABSOLUTE") {
+ Expr Inner = readParenExpr();
+ return [=] {
+ ExprValue I = Inner();
+ I.ForceAbsolute = true;
+ return I;
+ };
+ }
+ if (Tok == "ADDR") {
+ StringRef Name = readParenLiteral();
+ OutputSectionCommand *Cmd = Script->getOrCreateOutputSectionCommand(Name);
+ return [=]() -> ExprValue {
+ return {checkSection(Cmd, Location), 0, Location};
+ };
+ }
+ if (Tok == "ALIGN") {
+ expect("(");
+ Expr E = readExpr();
+ if (consume(")"))
+ return [=] { return alignTo(Script->getDot(), E().getValue()); };
+ expect(",");
+ Expr E2 = readExpr();
+ expect(")");
+ return [=] {
+ ExprValue V = E();
+ V.Alignment = E2().getValue();
+ return V;
+ };
+ }
+ if (Tok == "ALIGNOF") {
+ StringRef Name = readParenLiteral();
+ OutputSectionCommand *Cmd = Script->getOrCreateOutputSectionCommand(Name);
+ return [=] { return checkSection(Cmd, Location)->Alignment; };
+ }
+ if (Tok == "ASSERT")
+ return readAssertExpr();
+ if (Tok == "CONSTANT") {
+ StringRef Name = readParenLiteral();
+ return [=] { return getConstant(Name); };
+ }
+ if (Tok == "DATA_SEGMENT_ALIGN") {
+ expect("(");
+ Expr E = readExpr();
+ expect(",");
+ readExpr();
+ expect(")");
+ return [=] { return alignTo(Script->getDot(), E().getValue()); };
+ }
+ if (Tok == "DATA_SEGMENT_END") {
+ expect("(");
+ expect(".");
+ expect(")");
+ return [] { return Script->getDot(); };
+ }
+ if (Tok == "DATA_SEGMENT_RELRO_END") {
+ // GNU linkers implements more complicated logic to handle
+ // DATA_SEGMENT_RELRO_END. We instead ignore the arguments and
+ // just align to the next page boundary for simplicity.
+ expect("(");
+ readExpr();
+ expect(",");
+ readExpr();
+ expect(")");
+ return [] { return alignTo(Script->getDot(), Target->PageSize); };
+ }
+ if (Tok == "DEFINED") {
+ StringRef Name = readParenLiteral();
+ return [=] { return Script->isDefined(Name) ? 1 : 0; };
+ }
+ if (Tok == "LENGTH") {
+ StringRef Name = readParenLiteral();
+ if (Script->Opt.MemoryRegions.count(Name) == 0)
+ setError("memory region not defined: " + Name);
+ return [=] { return Script->Opt.MemoryRegions[Name].Length; };
+ }
+ if (Tok == "LOADADDR") {
+ StringRef Name = readParenLiteral();
+ OutputSectionCommand *Cmd = Script->getOrCreateOutputSectionCommand(Name);
+ return [=] { return checkSection(Cmd, Location)->getLMA(); };
+ }
+ if (Tok == "ORIGIN") {
+ StringRef Name = readParenLiteral();
+ if (Script->Opt.MemoryRegions.count(Name) == 0)
+ setError("memory region not defined: " + Name);
+ return [=] { return Script->Opt.MemoryRegions[Name].Origin; };
+ }
+ if (Tok == "SEGMENT_START") {
+ expect("(");
+ skip();
+ expect(",");
+ Expr E = readExpr();
+ expect(")");
+ return [=] { return E(); };
+ }
+ if (Tok == "SIZEOF") {
+ StringRef Name = readParenLiteral();
+ OutputSectionCommand *Cmd = Script->getOrCreateOutputSectionCommand(Name);
+ // Linker script does not create an output section if its content is empty.
+ // We want to allow SIZEOF(.foo) where .foo is a section which happened to
+ // be empty.
+ return [=] { return Cmd->Sec ? Cmd->Sec->Size : 0; };
+ }
+ if (Tok == "SIZEOF_HEADERS")
+ return [=] { return elf::getHeaderSize(); };
+
+ // Tok is the dot.
+ if (Tok == ".")
+ return [=] { return Script->getSymbolValue(Location, Tok); };
+
+ // Tok is a literal number.
+ if (Optional<uint64_t> Val = parseInt(Tok))
+ return [=] { return *Val; };
+
+ // Tok is a symbol name.
+ if (!isValidCIdentifier(Tok))
+ setError("malformed number: " + Tok);
+ Script->Opt.ReferencedSymbols.push_back(Tok);
+ return [=] { return Script->getSymbolValue(Location, Tok); };
+}
+
+Expr ScriptParser::readTernary(Expr Cond) {
+ Expr L = readExpr();
+ expect(":");
+ Expr R = readExpr();
+ return [=] { return Cond().getValue() ? L() : R(); };
+}
+
+Expr ScriptParser::readParenExpr() {
+ expect("(");
+ Expr E = readExpr();
+ expect(")");
+ return E;
+}
+
+std::vector<StringRef> ScriptParser::readOutputSectionPhdrs() {
+ std::vector<StringRef> Phdrs;
+ while (!Error && peek().startswith(":")) {
+ StringRef Tok = next();
+ Phdrs.push_back((Tok.size() == 1) ? next() : Tok.substr(1));
+ }
+ return Phdrs;
+}
+
+// Read a program header type name. The next token must be a
+// name of a program header type or a constant (e.g. "0x3").
+unsigned ScriptParser::readPhdrType() {
+ StringRef Tok = next();
+ if (Optional<uint64_t> Val = parseInt(Tok))
+ return *Val;
+
+ unsigned Ret = StringSwitch<unsigned>(Tok)
+ .Case("PT_NULL", PT_NULL)
+ .Case("PT_LOAD", PT_LOAD)
+ .Case("PT_DYNAMIC", PT_DYNAMIC)
+ .Case("PT_INTERP", PT_INTERP)
+ .Case("PT_NOTE", PT_NOTE)
+ .Case("PT_SHLIB", PT_SHLIB)
+ .Case("PT_PHDR", PT_PHDR)
+ .Case("PT_TLS", PT_TLS)
+ .Case("PT_GNU_EH_FRAME", PT_GNU_EH_FRAME)
+ .Case("PT_GNU_STACK", PT_GNU_STACK)
+ .Case("PT_GNU_RELRO", PT_GNU_RELRO)
+ .Case("PT_OPENBSD_RANDOMIZE", PT_OPENBSD_RANDOMIZE)
+ .Case("PT_OPENBSD_WXNEEDED", PT_OPENBSD_WXNEEDED)
+ .Case("PT_OPENBSD_BOOTDATA", PT_OPENBSD_BOOTDATA)
+ .Default(-1);
+
+ if (Ret == (unsigned)-1) {
+ setError("invalid program header type: " + Tok);
+ return PT_NULL;
+ }
+ return Ret;
+}
+
+// Reads an anonymous version declaration.
+void ScriptParser::readAnonymousDeclaration() {
+ std::vector<SymbolVersion> Locals;
+ std::vector<SymbolVersion> Globals;
+ std::tie(Locals, Globals) = readSymbols();
+
+ for (SymbolVersion V : Locals) {
+ if (V.Name == "*")
+ Config->DefaultSymbolVersion = VER_NDX_LOCAL;
+ else
+ Config->VersionScriptLocals.push_back(V);
+ }
+
+ for (SymbolVersion V : Globals)
+ Config->VersionScriptGlobals.push_back(V);
+
+ expect(";");
+}
+
+// Reads a non-anonymous version definition,
+// e.g. "VerStr { global: foo; bar; local: *; };".
+void ScriptParser::readVersionDeclaration(StringRef VerStr) {
+ // Read a symbol list.
+ std::vector<SymbolVersion> Locals;
+ std::vector<SymbolVersion> Globals;
+ std::tie(Locals, Globals) = readSymbols();
+
+ for (SymbolVersion V : Locals) {
+ if (V.Name == "*")
+ Config->DefaultSymbolVersion = VER_NDX_LOCAL;
+ else
+ Config->VersionScriptLocals.push_back(V);
+ }
+
+ // Create a new version definition and add that to the global symbols.
+ VersionDefinition Ver;
+ Ver.Name = VerStr;
+ Ver.Globals = Globals;
+
+ // User-defined version number starts from 2 because 0 and 1 are
+ // reserved for VER_NDX_LOCAL and VER_NDX_GLOBAL, respectively.
+ Ver.Id = Config->VersionDefinitions.size() + 2;
+ Config->VersionDefinitions.push_back(Ver);
+
+ // Each version may have a parent version. For example, "Ver2"
+ // defined as "Ver2 { global: foo; local: *; } Ver1;" has "Ver1"
+ // as a parent. This version hierarchy is, probably against your
+ // instinct, purely for hint; the runtime doesn't care about it
+ // at all. In LLD, we simply ignore it.
+ if (peek() != ";")
+ skip();
+ expect(";");
+}
+
+static bool hasWildcard(StringRef S) {
+ return S.find_first_of("?*[") != StringRef::npos;
+}
+
+// Reads a list of symbols, e.g. "{ global: foo; bar; local: *; };".
+std::pair<std::vector<SymbolVersion>, std::vector<SymbolVersion>>
+ScriptParser::readSymbols() {
+ std::vector<SymbolVersion> Locals;
+ std::vector<SymbolVersion> Globals;
+ std::vector<SymbolVersion> *V = &Globals;
+
+ while (!Error) {
+ if (consume("}"))
+ break;
+ if (consumeLabel("local")) {
+ V = &Locals;
+ continue;
+ }
+ if (consumeLabel("global")) {
+ V = &Globals;
+ continue;
+ }
+
+ if (consume("extern")) {
+ std::vector<SymbolVersion> Ext = readVersionExtern();
+ V->insert(V->end(), Ext.begin(), Ext.end());
+ } else {
+ StringRef Tok = next();
+ V->push_back({unquote(Tok), false, hasWildcard(Tok)});
+ }
+ expect(";");
+ }
+ return {Locals, Globals};
+}
+
+// Reads an "extern C++" directive, e.g.,
+// "extern "C++" { ns::*; "f(int, double)"; };"
+std::vector<SymbolVersion> ScriptParser::readVersionExtern() {
+ StringRef Tok = next();
+ bool IsCXX = Tok == "\"C++\"";
+ if (!IsCXX && Tok != "\"C\"")
+ setError("Unknown language");
+ expect("{");
+
+ std::vector<SymbolVersion> Ret;
+ while (!Error && peek() != "}") {
+ StringRef Tok = next();
+ bool HasWildcard = !Tok.startswith("\"") && hasWildcard(Tok);
+ Ret.push_back({unquote(Tok), IsCXX, HasWildcard});
+ expect(";");
+ }
+
+ expect("}");
+ return Ret;
+}
+
+uint64_t ScriptParser::readMemoryAssignment(StringRef S1, StringRef S2,
+ StringRef S3) {
+ if (!consume(S1) && !consume(S2) && !consume(S3)) {
+ setError("expected one of: " + S1 + ", " + S2 + ", or " + S3);
+ return 0;
+ }
+ expect("=");
+ return readExpr()().getValue();
+}
+
+// Parse the MEMORY command as specified in:
+// https://sourceware.org/binutils/docs/ld/MEMORY.html
+//
+// MEMORY { name [(attr)] : ORIGIN = origin, LENGTH = len ... }
+void ScriptParser::readMemory() {
+ expect("{");
+ while (!Error && !consume("}")) {
+ StringRef Name = next();
+
+ uint32_t Flags = 0;
+ uint32_t NegFlags = 0;
+ if (consume("(")) {
+ std::tie(Flags, NegFlags) = readMemoryAttributes();
+ expect(")");
+ }
+ expect(":");
+
+ uint64_t Origin = readMemoryAssignment("ORIGIN", "org", "o");
+ expect(",");
+ uint64_t Length = readMemoryAssignment("LENGTH", "len", "l");
+
+ // Add the memory region to the region map (if it doesn't already exist).
+ auto It = Script->Opt.MemoryRegions.find(Name);
+ if (It != Script->Opt.MemoryRegions.end())
+ setError("region '" + Name + "' already defined");
+ else
+ Script->Opt.MemoryRegions[Name] = {Name, Origin, Length, Flags, NegFlags};
+ }
+}
+
+// This function parses the attributes used to match against section
+// flags when placing output sections in a memory region. These flags
+// are only used when an explicit memory region name is not used.
+std::pair<uint32_t, uint32_t> ScriptParser::readMemoryAttributes() {
+ uint32_t Flags = 0;
+ uint32_t NegFlags = 0;
+ bool Invert = false;
+
+ for (char C : next().lower()) {
+ uint32_t Flag = 0;
+ if (C == '!')
+ Invert = !Invert;
+ else if (C == 'w')
+ Flag = SHF_WRITE;
+ else if (C == 'x')
+ Flag = SHF_EXECINSTR;
+ else if (C == 'a')
+ Flag = SHF_ALLOC;
+ else if (C != 'r')
+ setError("invalid memory region attribute");
+
+ if (Invert)
+ NegFlags |= Flag;
+ else
+ Flags |= Flag;
+ }
+ return {Flags, NegFlags};
+}
+
+void elf::readLinkerScript(MemoryBufferRef MB) {
+ ScriptParser(MB).readLinkerScript();
+}
+
+void elf::readVersionScript(MemoryBufferRef MB) {
+ ScriptParser(MB).readVersionScript();
+}
+
+void elf::readDynamicList(MemoryBufferRef MB) {
+ ScriptParser(MB).readDynamicList();
+}
generated by cgit v1.2.3 (git 2.39.1) at 2025-12-28 17:43:57 +0000