Support ABSOLUTE on the right hand side in linker scripts

This also requires postponing the assignment the assignment of
symbols defined in input linker scripts since those can refer to
output sections and in case we don't have a SECTIONS command, we
need to wait until all output sections have been created and
assigned addresses.

Differential Revision: https://reviews.llvm.org/D30851

llvm-svn: 297802
This commit is contained in:
Petr Hosek 2017-03-15 03:33:23 +00:00
parent c6ee33852b
commit 02ad516b2e
4 changed files with 34 additions and 21 deletions

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@ -153,11 +153,6 @@ void LinkerScript<ELFT>::addSymbol(SymbolAssignment *Cmd) {
return; return;
Cmd->Sym = addRegular<ELFT>(Cmd); Cmd->Sym = addRegular<ELFT>(Cmd);
// If there are sections, then let the value be assigned later in
// `assignAddresses`.
if (!ScriptConfig->HasSections)
assignSymbol(Cmd);
} }
bool SymbolAssignment::classof(const BaseCommand *C) { bool SymbolAssignment::classof(const BaseCommand *C) {
@ -344,15 +339,6 @@ void LinkerScript<ELFT>::processCommands(OutputSectionFactory &Factory) {
continue; continue;
} }
if (auto *Cmd = dyn_cast<AssertCommand>(Base1.get())) {
// If we don't have SECTIONS then output sections have already been
// created by Writer<ELFT>. The LinkerScript<ELFT>::assignAddresses
// will not be called, so ASSERT should be evaluated now.
if (!Opt.HasSections)
Cmd->Expression();
continue;
}
if (auto *Cmd = dyn_cast<OutputSectionCommand>(Base1.get())) { if (auto *Cmd = dyn_cast<OutputSectionCommand>(Base1.get())) {
std::vector<InputSectionBase *> V = createInputSectionList(*Cmd); std::vector<InputSectionBase *> V = createInputSectionList(*Cmd);
@ -779,6 +765,15 @@ void LinkerScriptBase::placeOrphanSections() {
} }
} }
void LinkerScriptBase::processNonSectionCommands() {
for (const std::unique_ptr<BaseCommand> &Base : Opt.Commands) {
if (auto *Cmd = dyn_cast<SymbolAssignment>(Base.get()))
assignSymbol(Cmd);
else if (auto *Cmd = dyn_cast<AssertCommand>(Base.get()))
Cmd->Expression();
}
}
void LinkerScriptBase::assignAddresses(std::vector<PhdrEntry> &Phdrs) { void LinkerScriptBase::assignAddresses(std::vector<PhdrEntry> &Phdrs) {
// Assign addresses as instructed by linker script SECTIONS sub-commands. // Assign addresses as instructed by linker script SECTIONS sub-commands.
Dot = 0; Dot = 0;
@ -1556,14 +1551,8 @@ SymbolAssignment *ScriptParser::readProvideOrAssignment(StringRef Tok) {
SymbolAssignment *ScriptParser::readAssignment(StringRef Name) { SymbolAssignment *ScriptParser::readAssignment(StringRef Name) {
StringRef Op = next(); StringRef Op = next();
Expr E;
assert(Op == "=" || Op == "+="); assert(Op == "=" || Op == "+=");
if (consume("ABSOLUTE")) { Expr E = readExpr();
E = readExpr();
E.IsAbsolute = [] { return true; };
} else {
E = readExpr();
}
if (Op == "+=") { if (Op == "+=") {
std::string Loc = getCurrentLocation(); std::string Loc = getCurrentLocation();
E = [=] { return ScriptBase->getSymbolValue(Loc, Name) + E(); }; E = [=] { return ScriptBase->getSymbolValue(Loc, Name) + E(); };
@ -1739,6 +1728,11 @@ Expr ScriptParser::readPrimary() {
// Built-in functions are parsed here. // Built-in functions are parsed here.
// https://sourceware.org/binutils/docs/ld/Builtin-Functions.html. // https://sourceware.org/binutils/docs/ld/Builtin-Functions.html.
if (Tok == "ABSOLUTE") {
Expr E = readParenExpr();
E.IsAbsolute = [] { return true; };
return E;
}
if (Tok == "ADDR") { if (Tok == "ADDR") {
StringRef Name = readParenLiteral(); StringRef Name = readParenLiteral();
return {[=] { return ScriptBase->getOutputSection(Location, Name)->Addr; }, return {[=] { return ScriptBase->getOutputSection(Location, Name)->Addr; },

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@ -287,6 +287,7 @@ public:
bool shouldKeep(InputSectionBase *S); bool shouldKeep(InputSectionBase *S);
void assignOffsets(OutputSectionCommand *Cmd); void assignOffsets(OutputSectionCommand *Cmd);
void placeOrphanSections(); void placeOrphanSections();
void processNonSectionCommands();
void assignAddresses(std::vector<PhdrEntry> &Phdrs); void assignAddresses(std::vector<PhdrEntry> &Phdrs);
int getSectionIndex(StringRef Name); int getSectionIndex(StringRef Name);
}; };

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@ -270,6 +270,7 @@ template <class ELFT> void Writer<ELFT>::run() {
} else { } else {
fixSectionAlignments(); fixSectionAlignments();
assignAddresses(); assignAddresses();
Script<ELFT>::X->processNonSectionCommands();
} }
// Remove empty PT_LOAD to avoid causing the dynamic linker to try to mmap a // Remove empty PT_LOAD to avoid causing the dynamic linker to try to mmap a

View File

@ -4,6 +4,11 @@
# RUN: ld.lld -o %t --script %t.script %t.o # RUN: ld.lld -o %t --script %t.script %t.o
# RUN: llvm-readobj --symbols %t | FileCheck %s # RUN: llvm-readobj --symbols %t | FileCheck %s
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
# RUN: echo "PROVIDE(foo = 1 + ABSOLUTE(ADDR(.text)));" > %t.script
# RUN: ld.lld -o %t --script %t.script %t.o
# RUN: llvm-readobj --symbols %t | FileCheck --check-prefix=CHECK-RHS %s
# CHECK: Name: foo # CHECK: Name: foo
# CHECK-NEXT: Value: # CHECK-NEXT: Value:
# CHECK-NEXT: Size: # CHECK-NEXT: Size:
@ -13,6 +18,18 @@
# CHECK-NEXT: Section: Absolute # CHECK-NEXT: Section: Absolute
# CHECK-NEXT: } # CHECK-NEXT: }
# CHECK-RHS: Name: foo
# CHECK-RHS-NEXT: Value: 0x201001
# CHECK-RHS-NEXT: Size:
# CHECK-RHS-NEXT: Binding:
# CHECK-RHS-NEXT: Type:
# CHECK-RHS-NEXT: Other:
# CHECK-RHS-NEXT: Section: Absolute
# CHECK-RHS-NEXT: }
.text .text
.globl _start .globl _start
_start: _start:
nop
.global foo