Index: ELF/LinkerScript.h =================================================================== --- ELF/LinkerScript.h +++ ELF/LinkerScript.h @@ -21,6 +21,7 @@ class ScriptParser; template class InputSectionBase; +template class OutputSectionBase; // This class represents each rule in SECTIONS command. class SectionRule { @@ -40,6 +41,17 @@ StringRef SectionPattern; }; +// This enum represents what we can observe in SECTIONS tag of script: +// Expr is a location counter change, like ". = . + 0x1000" +// Section is a description of output section, like ".data :..." +enum class Command { Expr, Section }; + +struct LocationNode { + Command Type; + std::vector Expr; + StringRef SectionName; +}; + // This is a runner of the linker script. class LinkerScript { friend class ScriptParser; @@ -53,9 +65,16 @@ ArrayRef getFiller(StringRef Name); template bool isDiscarded(InputSectionBase *S); template bool shouldKeep(InputSectionBase *S); + template + void fixupLocations(std::vector *> &); + template + void assignAddresses(std::vector *> &S); int compareSections(StringRef A, StringRef B); + bool Exists = false; + private: + uint64_t evaluate(std::vector &Tokens, uint64_t LocCounter); template SectionRule *find(InputSectionBase *S); // SECTIONS commands. @@ -67,6 +86,9 @@ // Section fill attribute for each section. llvm::StringMap> Filler; + // Used to assign addresses to sections. + std::vector Locations; + llvm::BumpPtrAllocator Alloc; }; Index: ELF/LinkerScript.cpp =================================================================== --- ELF/LinkerScript.cpp +++ ELF/LinkerScript.cpp @@ -17,20 +17,55 @@ #include "Config.h" #include "Driver.h" #include "InputSection.h" +#include "OutputSections.h" #include "ScriptParser.h" #include "SymbolTable.h" +#include "llvm/Support/ELF.h" #include "llvm/Support/FileSystem.h" #include "llvm/Support/MemoryBuffer.h" #include "llvm/Support/Path.h" #include "llvm/Support/StringSaver.h" using namespace llvm; +using namespace llvm::ELF; using namespace llvm::object; using namespace lld; using namespace lld::elf; LinkerScript *elf::Script; +static uint64_t getInteger(StringRef S) { + uint64_t V; + if (S.getAsInteger(0, V)) { + error("malformed number: " + V); + return 0; + } + return V; +} + +// Evaluates the expression given by list of tokens. +uint64_t LinkerScript::evaluate(std::vector &Tokens, + uint64_t LocCounter) { + uint64_t Result = 0; + for (size_t I = 0, E = Tokens.size(); I < E; ++I) { + // Each second token should be '+' as this is the + // only operator we support now. + if (I % 2 == 1) { + if (Tokens[I] == "+") + continue; + error("error in location counter expression"); + return 0; + } + + StringRef Tok = Tokens[I]; + if (Tok == ".") + Result += LocCounter; + else + Result += getInteger(Tok); + } + return Result; +} + template SectionRule *LinkerScript::find(InputSectionBase *S) { for (SectionRule &R : Sections) @@ -55,6 +90,64 @@ return R && R->Keep; } +// This method finalizes the Locations list. Adds neccesary locations for +// orphan sections, what prepares it for futher use without +// changes in LinkerScript::assignAddresses(). +template +void LinkerScript::fixupLocations(std::vector *> &S) { + // Orphan sections are sections present in the input files which + // are not explicitly placed into the output file by the linker + // script. We place orphan sections at end of file. Other linkers places + // them using some heuristics as described in + // https://sourceware.org/binutils/docs/ld/Orphan-Sections.html#Orphan-Sections. + for (OutputSectionBase *Sec : S) { + StringRef Name = Sec->getName(); + auto I = std::find(SectionOrder.begin(), SectionOrder.end(), Name); + if (I == SectionOrder.end()) + Locations.push_back({Command::Section, {}, {Name}}); + } +} + +template +void LinkerScript::assignAddresses(std::vector *> &S) { + typedef typename ELFT::uint uintX_t; + + uintX_t ThreadBssOffset = 0; + uintX_t VA = + Out::ElfHeader->getSize() + Out::ProgramHeaders->getSize(); + + for (LocationNode &Node : Locations) { + if (Node.Type == Command::Expr) { + VA = evaluate(Node.Expr, VA); + continue; + } + + auto I = + std::find_if(S.begin(), S.end(), [&](OutputSectionBase *Sec) { + return Sec->getName() == Node.SectionName; + }); + if (I == S.end()) + continue; + + OutputSectionBase *Sec = *I; + uintX_t Align = Sec->getAlign(); + if ((Sec->getFlags() & SHF_TLS) && Sec->getType() == SHT_NOBITS) { + uintX_t TVA = VA + ThreadBssOffset; + TVA = alignTo(TVA, Align); + Sec->setVA(TVA); + ThreadBssOffset = TVA - VA + Sec->getSize(); + continue; + } + + if (Sec->getFlags() & SHF_ALLOC) { + VA = alignTo(VA, Align); + Sec->setVA(VA); + VA += Sec->getSize(); + continue; + } + } +} + ArrayRef LinkerScript::getFiller(StringRef Name) { auto I = Filler.find(Name); if (I == Filler.end()) @@ -126,6 +219,7 @@ void readSearchDir(); void readSections(); + void readLocationCounterValue(); void readOutputSectionDescription(); void readSectionPatterns(StringRef OutSec, bool Keep); @@ -287,8 +381,13 @@ void ScriptParser::readSections() { expect("{"); - while (!Error && !skip("}")) - readOutputSectionDescription(); + while (!Error && !skip("}")) { + StringRef Tok = peek(); + if (Tok == ".") + readLocationCounterValue(); + else + readOutputSectionDescription(); + } } void ScriptParser::readSectionPatterns(StringRef OutSec, bool Keep) { @@ -297,9 +396,25 @@ Script->Sections.emplace_back(OutSec, next(), Keep); } +void ScriptParser::readLocationCounterValue() { + expect("."); + expect("="); + Script->Locations.push_back({Command::Expr}); + LocationNode &Node = Script->Locations.back(); + while (!Error) { + StringRef Tok = next(); + if (Tok == ";") + break; + Node.Expr.push_back(Tok); + } + if (Node.Expr.empty()) + error("error in location counter expression"); +} + void ScriptParser::readOutputSectionDescription() { StringRef OutSec = next(); Script->SectionOrder.push_back(OutSec); + Script->Locations.push_back({Command::Section, {}, {OutSec}}); expect(":"); expect("{"); while (!Error && !skip("}")) { @@ -340,6 +455,7 @@ void LinkerScript::read(MemoryBufferRef MB) { StringRef Path = MB.getBufferIdentifier(); ScriptParser(&Alloc, MB.getBuffer(), isUnderSysroot(Path)).run(); + Exists = true; } template StringRef LinkerScript::getOutputSection(InputSectionBase *); @@ -356,3 +472,21 @@ template bool LinkerScript::shouldKeep(InputSectionBase *); template bool LinkerScript::shouldKeep(InputSectionBase *); template bool LinkerScript::shouldKeep(InputSectionBase *); + +template void +LinkerScript::assignAddresses(std::vector *> &); +template void +LinkerScript::assignAddresses(std::vector *> &); +template void +LinkerScript::assignAddresses(std::vector *> &); +template void +LinkerScript::assignAddresses(std::vector *> &); + +template void +LinkerScript::fixupLocations(std::vector *> &); +template void +LinkerScript::fixupLocations(std::vector *> &); +template void +LinkerScript::fixupLocations(std::vector *> &); +template void +LinkerScript::fixupLocations(std::vector *> &); Index: ELF/Writer.cpp =================================================================== --- ELF/Writer.cpp +++ ELF/Writer.cpp @@ -220,8 +220,12 @@ } else { createPhdrs(); fixHeaders(); - fixSectionAlignments(); - assignAddresses(); + if (Script->Exists) { + Script->assignAddresses(OutputSections); + } else { + fixSectionAlignments(); + assignAddresses(); + } assignFileOffsets(); setPhdrs(); fixAbsoluteSymbols(); @@ -1280,6 +1284,9 @@ std::stable_sort(OutputSections.begin(), OutputSections.end(), compareSections); + if (Script->Exists) + Script->fixupLocations(OutputSections); + unsigned I = 1; for (OutputSectionBase *Sec : OutputSections) { Sec->SectionIndex = I++; @@ -1542,10 +1549,11 @@ // sections. These are special, we do not include them into output sections // list, but have them to simplify the code. template void Writer::fixHeaders() { - Out::ElfHeader->setVA(Target->getVAStart()); + uintX_t BaseVA = Script->Exists ? 0 : Target->getVAStart(); + Out::ElfHeader->setVA(BaseVA); Out::ElfHeader->setFileOffset(0); uintX_t Off = Out::ElfHeader->getSize(); - Out::ProgramHeaders->setVA(Off + Target->getVAStart()); + Out::ProgramHeaders->setVA(Off + BaseVA); Out::ProgramHeaders->setFileOffset(Off); } Index: test/ELF/end.s =================================================================== --- test/ELF/end.s +++ test/ELF/end.s @@ -36,13 +36,13 @@ // NOBSS-NEXT: SHF_ALLOC // NOBSS-NEXT: SHF_WRITE // NOBSS-NEXT: ] -// NOBSS-NEXT: Address: 0x12000 +// NOBSS-NEXT: Address: 0x159 // NOBSS-NEXT: Offset: // NOBSS-NEXT: Size: 2 // NOBSS: ] // NOBSS: Symbols [ // NOBSS: Name: _end -// NOBSS-NEXT: Value: 0x12002 +// NOBSS-NEXT: Value: 0x15B // NOBSS: ] // If the layout of the sections is changed, "_end" should point to the end of allocated address space. @@ -60,13 +60,13 @@ // TEXTATEND-NEXT: SHF_ALLOC // TEXTATEND-NEXT: SHF_EXECINSTR // TEXTATEND-NEXT: ] -// TEXTATEND-NEXT: Address: 0x12000 +// TEXTATEND-NEXT: Address: 0x160 // TEXTATEND-NEXT: Offset: // TEXTATEND-NEXT: Size: 1 // TEXTATEND: ] // TEXTATEND: Symbols [ // TEXTATEND: Name: _end -// TEXTATEND-NEXT: Value: 0x12001 +// TEXTATEND-NEXT: Value: 0x161 // TEXTATEND: ] .global _start,_end Index: test/ELF/linkerscript-locationcounter.s =================================================================== --- test/ELF/linkerscript-locationcounter.s +++ test/ELF/linkerscript-locationcounter.s @@ -0,0 +1,67 @@ +# REQUIRES: x86 +# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t +# RUN: echo "SECTIONS { \ +# RUN: . = 0x12341; \ +# RUN: .data : { *(.data) } \ +# RUN: . = . + 0x10000; \ +# RUN: .text : { *(.text) } \ +# RUN: }" > %t.script + +# RUN: ld.lld %t --script %t.script -o %t2 +# RUN: llvm-readobj -s %t2 | FileCheck %s + +# CHECK: Sections [ +# CHECK-NEXT: Section { +# CHECK-NEXT: Index: 0 +# CHECK-NEXT: Name: (0) +# CHECK-NEXT: Type: SHT_NULL +# CHECK-NEXT: Flags [ +# CHECK-NEXT: ] +# CHECK-NEXT: Address: 0x0 +# CHECK-NEXT: Offset: 0x0 +# CHECK-NEXT: Size: 0 +# CHECK-NEXT: Link: 0 +# CHECK-NEXT: Info: 0 +# CHECK-NEXT: AddressAlignment: 0 +# CHECK-NEXT: EntrySize: 0 +# CHECK-NEXT: } +# CHECK-NEXT: Section { +# CHECK-NEXT: Index: 1 +# CHECK-NEXT: Name: .data +# CHECK-NEXT: Type: SHT_PROGBITS +# CHECK-NEXT: Flags [ +# CHECK-NEXT: SHF_ALLOC +# CHECK-NEXT: SHF_WRITE +# CHECK-NEXT: ] +# CHECK-NEXT: Address: 0x12341 +# CHECK-NEXT: Offset: 0x158 +# CHECK-NEXT: Size: 8 +# CHECK-NEXT: Link: 0 +# CHECK-NEXT: Info: 0 +# CHECK-NEXT: AddressAlignment: 1 +# CHECK-NEXT: EntrySize: 0 +# CHECK-NEXT: } +# CHECK-NEXT: Section { +# CHECK-NEXT: Index: 2 +# CHECK-NEXT: Name: .text +# CHECK-NEXT: Type: SHT_PROGBITS +# CHECK-NEXT: Flags [ +# CHECK-NEXT: SHF_ALLOC +# CHECK-NEXT: SHF_EXECINSTR +# CHECK-NEXT: ] +# CHECK-NEXT: Address: 0x2234C +# CHECK-NEXT: Offset: 0x160 +# CHECK-NEXT: Size: 1 +# CHECK-NEXT: Link: 0 +# CHECK-NEXT: Info: 0 +# CHECK-NEXT: AddressAlignment: 4 +# CHECK-NEXT: EntrySize: 0 +# CHECK-NEXT: } + +.globl _start; +_start: +nop + +.section .data +.quad 0 + Index: test/ELF/linkerscript-sections-keep.s =================================================================== --- test/ELF/linkerscript-sections-keep.s +++ test/ELF/linkerscript-sections-keep.s @@ -12,8 +12,8 @@ # SECGC: Sections: # SECGC-NEXT: Idx Name Size Address Type # SECGC-NEXT: 0 00000000 0000000000000000 -# SECGC-NEXT: 1 .text 00000007 0000000000011000 TEXT DATA -# SECGC-NEXT: 2 .temp 00000004 0000000000012000 DATA +# SECGC-NEXT: 1 .text 00000007 0000000000000158 TEXT DATA +# SECGC-NEXT: 2 .temp 00000004 000000000000015f DATA ## Now apply KEEP command to preserve the section. # RUN: echo "SECTIONS { \ @@ -26,9 +26,9 @@ # SECNOGC: Sections: # SECNOGC-NEXT: Idx Name Size Address Type # SECNOGC-NEXT: 0 00000000 0000000000000000 -# SECNOGC-NEXT: 1 .text 00000007 0000000000011000 TEXT DATA -# SECNOGC-NEXT: 2 .keep 00000004 0000000000012000 DATA -# SECNOGC-NEXT: 3 .temp 00000004 0000000000012004 DATA +# SECNOGC-NEXT: 1 .text 00000007 0000000000000158 TEXT DATA +# SECNOGC-NEXT: 2 .keep 00000004 000000000000015f DATA +# SECNOGC-NEXT: 3 .temp 00000004 0000000000000163 DATA ## A section name matches two entries in the SECTIONS directive. The ## first one doesn't have KEEP, the second one does. If section that have @@ -42,9 +42,9 @@ # KEEP-AT-FIRST: Sections: # KEEP-AT-FIRST-NEXT: Idx Name Size Address Type # KEEP-AT-FIRST-NEXT: 0 00000000 0000000000000000 -# KEEP-AT-FIRST-NEXT: 1 .keep 00000004 0000000000010120 DATA -# KEEP-AT-FIRST-NEXT: 2 .temp 00000004 0000000000010124 DATA -# KEEP-AT-FIRST-NEXT: 3 .text 00000007 0000000000011000 TEXT DATA +# KEEP-AT-FIRST-NEXT: 1 .keep 00000004 0000000000000120 DATA +# KEEP-AT-FIRST-NEXT: 2 .temp 00000004 0000000000000124 DATA +# KEEP-AT-FIRST-NEXT: 3 .text 00000007 0000000000000128 TEXT DATA # KEEP-AT-FIRST-NEXT: 4 .symtab 00000060 0000000000000000 # KEEP-AT-FIRST-NEXT: 5 .shstrtab 0000002d 0000000000000000 # KEEP-AT-FIRST-NEXT: 6 .strtab 00000012 0000000000000000 @@ -63,8 +63,8 @@ # KEEP-AT-SECOND: Sections: # KEEP-AT-SECOND-NEXT: Idx Name Size Address Type # KEEP-AT-SECOND-NEXT: 0 00000000 0000000000000000 -# KEEP-AT-SECOND-NEXT: 1 .temp 00000004 0000000000010120 DATA -# KEEP-AT-SECOND-NEXT: 2 .text 00000007 0000000000011000 TEXT DATA +# KEEP-AT-SECOND-NEXT: 1 .temp 00000004 0000000000000120 DATA +# KEEP-AT-SECOND-NEXT: 2 .text 00000007 0000000000000124 TEXT DATA # KEEP-AT-SECOND-NEXT: 3 .symtab 00000048 0000000000000000 # KEEP-AT-SECOND-NEXT: 4 .shstrtab 00000027 0000000000000000 # KEEP-AT-SECOND-NEXT: 5 .strtab 0000000d 0000000000000000 Index: test/ELF/linkerscript-va.s =================================================================== --- test/ELF/linkerscript-va.s +++ test/ELF/linkerscript-va.s @@ -0,0 +1,24 @@ +# REQUIRES: x86 +# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t + +# RUN: echo "" > %t.script +# RUN: ld.lld -o %t1 --script %t.script %t +# RUN: llvm-objdump -section-headers %t1 | FileCheck %s +# CHECK: Sections: +# CHECK-NEXT: Idx Name Size Address Type +# CHECK-NEXT: 0 00000000 0000000000000000 +# CHECK-NEXT: 1 .foo 00000004 0000000000000120 DATA +# CHECK-NEXT: 2 .boo 00000004 0000000000000124 DATA +# CHECK-NEXT: 3 .text 00000001 0000000000000128 TEXT DATA + +.global _start +_start: + nop + +.section .foo, "a" +foo: + .long 0 + +.section .boo, "a" +boo: + .long 0 Index: test/ELF/wildcards.s =================================================================== --- test/ELF/wildcards.s +++ test/ELF/wildcards.s @@ -10,10 +10,10 @@ # SEC-DEFAULT: Sections: # SEC-DEFAULT-NEXT: Idx Name Size Address Type # SEC-DEFAULT-NEXT: 0 00000000 0000000000000000 -# SEC-DEFAULT-NEXT: 1 .text 00000008 0000000000011000 TEXT DATA -# SEC-DEFAULT-NEXT: 2 .abcd 00000004 0000000000011008 TEXT DATA -# SEC-DEFAULT-NEXT: 3 .ad 00000004 000000000001100c TEXT DATA -# SEC-DEFAULT-NEXT: 4 .ag 00000004 0000000000011010 TEXT DATA +# SEC-DEFAULT-NEXT: 1 .text 00000008 0000000000000120 TEXT DATA +# SEC-DEFAULT-NEXT: 2 .abcd 00000004 0000000000000128 TEXT DATA +# SEC-DEFAULT-NEXT: 3 .ad 00000004 000000000000012c TEXT DATA +# SEC-DEFAULT-NEXT: 4 .ag 00000004 0000000000000130 TEXT DATA # SEC-DEFAULT-NEXT: 5 .symtab 00000030 0000000000000000 # SEC-DEFAULT-NEXT: 6 .shstrtab 0000002f 0000000000000000 # SEC-DEFAULT-NEXT: 7 .strtab 00000008 0000000000000000 @@ -34,9 +34,9 @@ # SEC-ALL: Sections: # SEC-ALL-NEXT: Idx Name Size Address Type # SEC-ALL-NEXT: 0 00000000 0000000000000000 -# SEC-ALL-NEXT: 1 .text 0000000c 0000000000011000 TEXT DATA -# SEC-ALL-NEXT: 2 .ad 00000004 000000000001100c TEXT DATA -# SEC-ALL-NEXT: 3 .ag 00000004 0000000000011010 TEXT DATA +# SEC-ALL-NEXT: 1 .text 0000000c 0000000000000120 TEXT DATA +# SEC-ALL-NEXT: 2 .ad 00000004 000000000000012c TEXT DATA +# SEC-ALL-NEXT: 3 .ag 00000004 0000000000000130 TEXT DATA # SEC-ALL-NEXT: 4 .symtab 00000030 0000000000000000 # SEC-ALL-NEXT: 5 .shstrtab 00000029 0000000000000000 # SEC-ALL-NEXT: 6 .strtab 00000008 0000000000000000 @@ -50,7 +50,7 @@ # SEC-NO: Sections: # SEC-NO-NEXT: Idx Name Size Address Type # SEC-NO-NEXT: 0 00000000 0000000000000000 -# SEC-NO-NEXT: 1 .text 00000014 0000000000011000 TEXT DATA +# SEC-NO-NEXT: 1 .text 00000014 0000000000000120 TEXT DATA # SEC-NO-NEXT: 2 .symtab 00000030 0000000000000000 # SEC-NO-NEXT: 3 .shstrtab 00000021 0000000000000000 # SEC-NO-NEXT: 4 .strtab 00000008 0000000000000000