Index: ELF/LinkerScript.h
===================================================================
--- ELF/LinkerScript.h
+++ ELF/LinkerScript.h
@@ -22,6 +22,7 @@
class ScriptParser;
template <class ELFT> class InputSectionBase;
template <class ELFT> class OutputSectionBase;
+template <class ELFT> class SymbolTable;
// This class represents each rule in SECTIONS command.
class SectionRule {
@@ -42,14 +43,18 @@
};
// This enum represents what we can observe in SECTIONS tag of script:
-// ExprKind is a location counter change, like ". = . + 0x1000"
-// SectionKind is a description of output section, like ".data :..."
-enum SectionsCommandKind { ExprKind, SectionKind };
+// * ExprKind is a location counter change, like ". = . + 0x1000"
+// * SectionKind is a description of output section, like ".data :..."
+// * ContentKind is a content of output section, it helps to distinguish PROVIDE
+// command before and after section content, first one should have address
+// equal to address of output section, second points to location after that.
+// * ProvideKind is PROVIDE command.
+enum SectionsCommandKind { ExprKind, SectionKind, ContentKind, ProvideKind };
struct SectionsCommand {
SectionsCommandKind Kind;
std::vector<StringRef> Expr;
- StringRef SectionName;
+ StringRef Name;
};
// This is a runner of the linker script.
@@ -68,6 +73,9 @@
template <class ELFT>
void assignAddresses(std::vector<OutputSectionBase<ELFT> *> &S);
int compareSections(StringRef A, StringRef B);
+ template <class ELFT>
+ void createSymbols(SymbolTable<ELFT> &Symtab,
+ ArrayRef<OutputSectionBase<ELFT> *> Sections);
bool DoLayout = false;
Index: ELF/LinkerScript.cpp
===================================================================
--- ELF/LinkerScript.cpp
+++ ELF/LinkerScript.cpp
@@ -172,7 +172,7 @@
template <class ELFT>
static OutputSectionBase<ELFT> *
-findSection(std::vector<OutputSectionBase<ELFT> *> &V, StringRef Name) {
+findSection(ArrayRef<OutputSectionBase<ELFT> *> V, StringRef Name) {
for (OutputSectionBase<ELFT> *Sec : V)
if (Sec->getName() == Name)
return Sec;
@@ -192,8 +192,10 @@
for (OutputSectionBase<ELFT> *Sec : Sections) {
StringRef Name = Sec->getName();
auto I = std::find(SectionOrder.begin(), SectionOrder.end(), Name);
- if (I == SectionOrder.end())
+ if (I == SectionOrder.end()) {
Commands.push_back({SectionKind, {}, Name});
+ Commands.push_back({ContentKind, {}, Name});
+ }
}
// Assign addresses as instructed by linker script SECTIONS sub-commands.
@@ -206,8 +208,10 @@
VA = evaluate(Cmd.Expr, VA);
continue;
}
+ if (Cmd.Kind != ContentKind)
+ continue;
- OutputSectionBase<ELFT> *Sec = findSection(Sections, Cmd.SectionName);
+ OutputSectionBase<ELFT> *Sec = findSection<ELFT>(Sections, Cmd.Name);
if (!Sec)
continue;
@@ -235,6 +239,40 @@
return I->second;
}
+template <class ELFT>
+void LinkerScript::createSymbols(SymbolTable<ELFT> &Symtab,
+ ArrayRef<OutputSectionBase<ELFT> *> Sections) {
+ typedef typename ELFT::uint uintX_t;
+ if (!Script->DoLayout)
+ return;
+
+ // Currently we support only PROVIDE keywords inside
+ // output sections descriptions that are used to mark
+ // begin and end of the section.
+ StringRef SecName;
+ uintX_t Val;
+ for (SectionsCommand &Cmd : Commands) {
+ if (Cmd.Kind == SectionKind) {
+ SecName = Cmd.Name;
+ Val = 0;
+ } else if (Cmd.Kind == ContentKind) {
+ Val = DefinedSynthetic<ELFT>::SectionEnd;
+ }
+
+ if (Cmd.Kind != ProvideKind)
+ continue;
+
+ OutputSectionBase<ELFT> *Sec = findSection(Sections, SecName);
+ if (!Sec)
+ continue;
+
+ StringRef SymName = Cmd.Name;
+ if (SymbolBody *S = Symtab.find(SymName))
+ if (S->isUndefined())
+ Symtab.addSynthetic(SymName, *Sec, Val);
+ }
+}
+
// A compartor to sort output sections. Returns -1 or 1 if both
// A and B are mentioned in linker scripts. Otherwise, returns 0
// to use the default rule which is implemented in Writer.cpp.
@@ -300,6 +338,7 @@
void readSections();
void readLocationCounterValue();
+ void readProvide();
void readOutputSectionDescription();
void readSectionPatterns(StringRef OutSec, bool Keep);
@@ -464,6 +503,9 @@
expect("{");
while (!Error && !skip("}")) {
StringRef Tok = peek();
+ if (Tok == "PROVIDE")
+ setError("PROVIDE outside section declaration not allowed");
+
if (Tok == ".")
readLocationCounterValue();
else
@@ -473,6 +515,7 @@
void ScriptParser::readSectionPatterns(StringRef OutSec, bool Keep) {
expect("(");
+ Script->Commands.push_back({ContentKind, {}, OutSec});
while (!Error && !skip(")"))
Script->Sections.emplace_back(OutSec, next(), Keep);
}
@@ -492,6 +535,27 @@
error("error in location counter expression");
}
+void ScriptParser::readProvide() {
+ expect("(");
+ Script->Commands.push_back({ProvideKind, {}, ""});
+ SectionsCommand &Cmd = Script->Commands.back();
+ Cmd.Name = next();
+
+ expect("=");
+ while (!Error) {
+ StringRef Tok = next();
+ if (Tok == ")")
+ break;
+ Cmd.Expr.push_back(Tok);
+ }
+ expect(";");
+
+ if (Cmd.Expr.empty())
+ error("empty provide expression");
+ else if (Cmd.Expr[0] != "." || Cmd.Expr.size() > 1)
+ error("PROVIDE does not support expressions");
+}
+
void ScriptParser::readOutputSectionDescription() {
StringRef OutSec = next();
Script->SectionOrder.push_back(OutSec);
@@ -500,7 +564,9 @@
expect("{");
while (!Error && !skip("}")) {
StringRef Tok = next();
- if (Tok == "*") {
+ if (Tok == "PROVIDE") {
+ readProvide();
+ } else if (Tok == "*") {
readSectionPatterns(OutSec, false);
} else if (Tok == "KEEP") {
expect("(");
@@ -561,3 +627,16 @@
LinkerScript::assignAddresses(std::vector<OutputSectionBase<ELF64LE> *> &);
template void
LinkerScript::assignAddresses(std::vector<OutputSectionBase<ELF64BE> *> &);
+
+template void
+LinkerScript::createSymbols(SymbolTable<ELF32LE> &,
+ ArrayRef<OutputSectionBase<ELF32LE> *> Sections);
+template void
+LinkerScript::createSymbols(SymbolTable<ELF32BE> &,
+ ArrayRef<OutputSectionBase<ELF32BE> *> Sections);
+template void
+LinkerScript::createSymbols(SymbolTable<ELF64LE> &,
+ ArrayRef<OutputSectionBase<ELF64LE> *> Sections);
+template void
+LinkerScript::createSymbols(SymbolTable<ELF64BE> &,
+ ArrayRef<OutputSectionBase<ELF64BE> *> Sections);
Index: ELF/Writer.cpp
===================================================================
--- ELF/Writer.cpp
+++ ELF/Writer.cpp
@@ -1215,6 +1215,8 @@
// Define __rel[a]_iplt_{start,end} symbols if needed.
addRelIpltSymbols();
+ Script->createSymbols<ELFT>(Symtab, OutputSections);
+
if (Out<ELFT>::EhFrameHdr->Sec)
Out<ELFT>::EhFrameHdr->Sec->finalize();
Index: test/ELF/linkerscript-provide.s
===================================================================
--- test/ELF/linkerscript-provide.s
+++ test/ELF/linkerscript-provide.s
@@ -0,0 +1,96 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
+
+## We do not support PROVIDE keyword outside
+## of output section declarations.
+# RUN: echo "SECTIONS \
+# RUN: { \
+# RUN: PROVIDE (beginText = .); \
+# RUN: .text : \
+# RUN: { \
+# RUN: *(.text) \
+# RUN: } \
+# RUN: }" > %t.script
+# RUN: not ld.lld -o %t2 --script %t.script %t 2>&1 | FileCheck -check-prefix=ERR1 %s
+# ERR1: PROVIDE outside section declaration not allowed
+
+## We do not support PROVIDE keyword that
+## contains anything except assign of location counter.
+# RUN: echo "SECTIONS \
+# RUN: { \
+# RUN: .text : \
+# RUN: { \
+# RUN: PROVIDE (beginText = . + 0x0); \
+# RUN: *(.text) \
+# RUN: } \
+# RUN: }" > %t.script
+# RUN: not ld.lld -o %t2 --script %t.script %t 2>&1 | FileCheck -check-prefix=ERR2 %s
+# ERR2: PROVIDE does not support expressions
+
+## Empty expression is a error.
+# RUN: echo "SECTIONS \
+# RUN: { \
+# RUN: .text : \
+# RUN: { \
+# RUN: PROVIDE (beginText = ); \
+# RUN: *(.text) \
+# RUN: } \
+# RUN: }" > %t.script
+# RUN: not ld.lld -o %t2 --script %t.script %t 2>&1 | FileCheck -check-prefix=ERR3 %s
+# ERR3: empty provide expression
+
+## Check case with PROVIDE inside section description.
+# RUN: echo "SECTIONS \
+# RUN: { \
+# RUN: .text : \
+# RUN: { \
+# RUN: PROVIDE (beginText = .); \
+# RUN: *(.text) \
+# RUN: PROVIDE (endText = .); \
+# RUN: } \
+# RUN: }" > %t.script
+# RUN: ld.lld -o %t2 --script %t.script %t
+# RUN: llvm-readobj -sections -symbols %t2 | FileCheck %s
+# CHECK: Sections [
+# CHECK: Section {
+# CHECK: Name: .text
+# CHECK-NEXT: Type: SHT_PROGBITS
+# CHECK-NEXT: Flags [
+# CHECK-NEXT: SHF_ALLOC
+# CHECK-NEXT: SHF_EXECINSTR
+# CHECK-NEXT: ]
+# CHECK-NEXT: Address: 0x[[ADDR:.*]]
+# CHECK-NEXT: Offset:
+# CHECK-NEXT: Size: 10
+# CHECK-NEXT: Link: 0
+# CHECK-NEXT: Info: 0
+# CHECK-NEXT: AddressAlignment: 4
+# CHECK-NEXT: EntrySize: 0
+# CHECK-NEXT: }
+# CHECK: Symbol {
+# CHECK: Name: beginText
+# CHECK-NEXT: Value: 0x[[ADDR]]
+# CHECK-NEXT: Size: 0
+# CHECK-NEXT: Binding: Local
+# CHECK-NEXT: Type: None
+# CHECK-NEXT: Other [
+# CHECK-NEXT: STV_HIDDEN
+# CHECK-NEXT: ]
+# CHECK-NEXT: Section: .text
+# CHECK-NEXT: }
+# CHECK-NEXT: Symbol {
+# CHECK-NEXT: Name: endText
+# CHECK-NEXT: Value: 0x12A
+# CHECK-NEXT: Size: 0
+# CHECK-NEXT: Binding: Local
+# CHECK-NEXT: Type: None
+# CHECK-NEXT: Other [
+# CHECK-NEXT: STV_HIDDEN
+# CHECK-NEXT: ]
+# CHECK-NEXT: Section: .text
+# CHECK-NEXT: }
+
+.globl _start
+_start:
+ call beginText
+ call endText