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Commit d73ef17

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author
George Rimar
committedSep 14, 2016
[ELF] - Implemented --section-start, -Ttext, -Tdata, -Tbss options.
--section-start=sectionname=org Locate a section in the output file at the absolute address given by org. You may use this option as many times as necessary to locate multiple sections in the command line. org must be a single hexadecimal integer; for compatibility with other linkers, you may omit the leading `0x' usually associated with hexadecimal values. Note: there should be no white space between sectionname, the equals sign (“<=>”), and org. -Tbss=org -Tdata=org -Ttext=org Same as --section-start, with .bss, .data or .text as the sectionname. Differential revision: https://reviews.llvm.org/D24294 llvm-svn: 281458
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llvmorg-21-initllvmorg-4.0.0-rc1
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‎lld/ELF/Config.h

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@@ -65,6 +65,7 @@ struct VersionDefinition {
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struct Configuration {
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Symbol *EntrySym = nullptr;
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InputFile *FirstElf = nullptr;
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llvm::StringMap<uint64_t> SectionStartMap;
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llvm::StringRef DynamicLinker;
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llvm::StringRef Entry;
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llvm::StringRef Emulation;

‎lld/ELF/Driver.cpp

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@@ -380,6 +380,33 @@ static StripPolicy getStripOption(opt::InputArgList &Args) {
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return StripPolicy::None;
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}
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static uint64_t parseSectionAddress(StringRef S, opt::Arg *Arg) {
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uint64_t VA = 0;
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if (S.startswith("0x"))
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S = S.drop_front(2);
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if (S.getAsInteger(16, VA))
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error("invalid argument: " + stringize(Arg));
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return VA;
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}
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static StringMap<uint64_t> getSectionStartMap(opt::InputArgList &Args) {
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StringMap<uint64_t> Ret;
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for (auto *Arg : Args.filtered(OPT_section_start)) {
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StringRef Name;
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StringRef Addr;
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std::tie(Name, Addr) = StringRef(Arg->getValue()).split('=');
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Ret[Name] = parseSectionAddress(Addr, Arg);
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}
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if (auto *Arg = Args.getLastArg(OPT_Ttext))
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Ret[".text"] = parseSectionAddress(Arg->getValue(), Arg);
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if (auto *Arg = Args.getLastArg(OPT_Tdata))
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Ret[".data"] = parseSectionAddress(Arg->getValue(), Arg);
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if (auto *Arg = Args.getLastArg(OPT_Tbss))
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Ret[".bss"] = parseSectionAddress(Arg->getValue(), Arg);
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return Ret;
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}
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// Initializes Config members by the command line options.
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void LinkerDriver::readConfigs(opt::InputArgList &Args) {
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for (auto *Arg : Args.filtered(OPT_L))
@@ -391,6 +418,8 @@ void LinkerDriver::readConfigs(opt::InputArgList &Args) {
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if (!RPaths.empty())
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Config->RPath = llvm::join(RPaths.begin(), RPaths.end(), ":");
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Config->SectionStartMap = getSectionStartMap(Args);
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if (auto *Arg = Args.getLastArg(OPT_m)) {
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// Parse ELF{32,64}{LE,BE} and CPU type.
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StringRef S = Arg->getValue();

‎lld/ELF/Options.td

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@@ -27,6 +27,12 @@ def L: JoinedOrSeparate<["-"], "L">, MetaVarName<"<dir>">,
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def O: Joined<["-"], "O">, HelpText<"Optimize output file size">;
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def Tbss: J<"Tbss=">, HelpText<"Same as --section-start with .bss as the sectionname">;
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def Tdata: J<"Tdata=">, HelpText<"Same as --section-start with .data as the sectionname">;
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def Ttext: J<"Ttext=">, HelpText<"Same as --section-start with .text as the sectionname">;
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def allow_multiple_definition: F<"allow-multiple-definition">,
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HelpText<"Allow multiple definitions">;
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@@ -147,6 +153,9 @@ def relocatable: F<"relocatable">, HelpText<"Create relocatable object file">;
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def script: S<"script">, HelpText<"Read linker script">;
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def section_start: S<"section-start">, MetaVarName<"<address>">,
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HelpText<"Set address of section">;
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def shared: F<"shared">, HelpText<"Build a shared object">;
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def soname: J<"soname=">, HelpText<"Set DT_SONAME">;

‎lld/ELF/Writer.cpp

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@@ -1080,6 +1080,10 @@ template <class ELFT> void Writer<ELFT>::assignAddresses() {
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if (Sec->PageAlign)
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Alignment = std::max<uintX_t>(Alignment, Target->PageSize);
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auto I = Config->SectionStartMap.find(Sec->getName());
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if (I != Config->SectionStartMap.end())
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VA = I->second;
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// We only assign VAs to allocated sections.
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if (needsPtLoad(Sec)) {
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VA = alignTo(VA, Alignment);

‎lld/test/ELF/sectionstart.s

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@@ -0,0 +1,57 @@
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# REQUIRES: x86
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# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
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# RUN: ld.lld %t.o --section-start .text=0x100000 \
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# RUN: --section-start .data=0x110000 --section-start .bss=0x200000 -o %t
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# RUN: llvm-objdump -section-headers %t | FileCheck %s
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# CHECK: Sections:
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# CHECK-NEXT: Idx Name Size Address Type
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# CHECK-NEXT: 0 00000000 0000000000000000
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# CHECK-NEXT: 1 .text 00000001 0000000000100000 TEXT DATA
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# CHECK-NEXT: 2 .data 00000004 0000000000110000 DATA
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# CHECK-NEXT: 3 .bss 00000004 0000000000200000 BSS
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## The same, but dropped "0x" prefix.
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# RUN: ld.lld %t.o --section-start .text=100000 \
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# RUN: --section-start .data=110000 --section-start .bss=0x200000 -o %t1
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# RUN: llvm-objdump -section-headers %t1 | FileCheck %s
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## Use -Ttext, -Tdata, -Tbss as replacement for --section-start:
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# RUN: ld.lld %t.o -Ttext=0x100000 -Tdata=0x110000 -Tbss=0x200000 -o %t4
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# RUN: llvm-objdump -section-headers %t4 | FileCheck %s
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## The same, but dropped "0x" prefix.
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# RUN: ld.lld %t.o -Ttext=100000 -Tdata=110000 -Tbss=200000 -o %t5
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# RUN: llvm-objdump -section-headers %t5 | FileCheck %s
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## Errors:
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# RUN: not ld.lld %t.o --section-start .text100000 -o %t2 2>&1 \
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# RUN: | FileCheck -check-prefix=ERR1 %s
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# ERR1: invalid argument: --section-start .text100000
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# RUN: not ld.lld %t.o --section-start .text=1Q0000 -o %t3 2>&1 \
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# RUN: | FileCheck -check-prefix=ERR2 %s
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# ERR2: invalid argument: --section-start .text=1Q0000
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# RUN: not ld.lld %t.o -Ttext=1w0000 -o %t6 2>&1 \
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# RUN: | FileCheck -check-prefix=ERR3 %s
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# ERR3: invalid argument: -Ttext=1w0000
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# RUN: not ld.lld %t.o -Tbss=1w0000 -o %t6 2>&1 \
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# RUN: | FileCheck -check-prefix=ERR4 %s
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# ERR4: invalid argument: -Tbss=1w0000
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# RUN: not ld.lld %t.o -Tdata=1w0000 -o %t6 2>&1 \
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# RUN: | FileCheck -check-prefix=ERR5 %s
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# ERR5: invalid argument: -Tdata=1w0000
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.text
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.globl _start
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_start:
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nop
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.data
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.long 0
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.bss
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.zero 4

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