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petrhosekpetrhosek
committedJul 12, 2016
[ELF] Support for setting the base address
The -image-base option allows for overriding the base address. Differential Revision: http://reviews.llvm.org/D22116 llvm-svn: 275206
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5 files changed

+75
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‎lld/ELF/Config.h

+1
Original file line numberDiff line numberDiff line change
@@ -117,6 +117,7 @@ struct Configuration {
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ELFKind EKind = ELFNoneKind;
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uint16_t EMachine = llvm::ELF::EM_NONE;
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uint64_t EntryAddr = -1;
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uint64_t VAStart;
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unsigned LtoJobs;
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unsigned LtoO;
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unsigned Optimize;

‎lld/ELF/Driver.cpp

+10
Original file line numberDiff line numberDiff line change
@@ -532,6 +532,16 @@ template <class ELFT> void LinkerDriver::link(opt::InputArgList &Args) {
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Config->EntrySym = Symtab.addUndefined(S);
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}
534534

535+
if (auto *Arg = Args.getLastArg(OPT_image_base)) {
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StringRef S = Arg->getValue();
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if (S.getAsInteger(0, Config->VAStart))
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error(Arg->getSpelling() + ": number expected, but got " + S);
539+
else if ((Config->VAStart % Target->PageSize) != 0)
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warning(Arg->getSpelling() + ": address isn't multiple of page size");
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} else {
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Config->VAStart = Target->getVAStart();
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}
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for (std::unique_ptr<InputFile> &F : Files)
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Symtab.addFile(std::move(F));
537547
if (HasError)

‎lld/ELF/Options.td

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Original file line numberDiff line numberDiff line change
@@ -79,6 +79,8 @@ def help: F<"help">, HelpText<"Print option help">;
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def icf: F<"icf=all">, HelpText<"Enable identical code folding">;
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def image_base : J<"image-base=">, HelpText<"Set the base address">;
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def gc_sections: F<"gc-sections">,
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HelpText<"Enable garbage collection of unused sections">;
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‎lld/ELF/Writer.cpp

+2-2
Original file line numberDiff line numberDiff line change
@@ -1022,15 +1022,15 @@ template <class ELFT> void Writer<ELFT>::fixSectionAlignments() {
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// sections. These are special, we do not include them into output sections
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// list, but have them to simplify the code.
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template <class ELFT> void Writer<ELFT>::fixHeaders() {
1025-
uintX_t BaseVA = ScriptConfig->DoLayout ? 0 : Target->getVAStart();
1025+
uintX_t BaseVA = ScriptConfig->DoLayout ? 0 : Config->VAStart;
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Out<ELFT>::ElfHeader->setVA(BaseVA);
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uintX_t Off = Out<ELFT>::ElfHeader->getSize();
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Out<ELFT>::ProgramHeaders->setVA(Off + BaseVA);
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}
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// Assign VAs (addresses at run-time) to output sections.
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template <class ELFT> void Writer<ELFT>::assignAddresses() {
1033-
uintX_t VA = Target->getVAStart() + Out<ELFT>::ElfHeader->getSize() +
1033+
uintX_t VA = Config->VAStart + Out<ELFT>::ElfHeader->getSize() +
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Out<ELFT>::ProgramHeaders->getSize();
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uintX_t ThreadBssOffset = 0;

‎lld/test/ELF/ttext-segment.s

+60
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,60 @@
1+
# REQUIRES: x86
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# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
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# RUN: ld.lld -image-base=0x1000000 %t -o %t1
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# RUN: llvm-readobj -program-headers %t1 | FileCheck %s
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.global _start
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_start:
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nop
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# CHECK: ProgramHeaders [
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# CHECK-NEXT: ProgramHeader {
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# CHECK-NEXT: Type: PT_PHDR (0x6)
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# CHECK-NEXT: Offset: 0x40
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# CHECK-NEXT: VirtualAddress: 0x1000040
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# CHECK-NEXT: PhysicalAddress: 0x1000040
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# CHECK-NEXT: FileSize: 224
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# CHECK-NEXT: MemSize: 224
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# CHECK-NEXT: Flags [ (0x4)
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# CHECK-NEXT: PF_R (0x4)
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# CHECK-NEXT: ]
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# CHECK-NEXT: Alignment: 8
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# CHECK-NEXT: }
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# CHECK-NEXT: ProgramHeader {
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# CHECK-NEXT: Type: PT_LOAD (0x1)
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# CHECK-NEXT: Offset: 0x0
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# CHECK-NEXT: VirtualAddress: 0x1000000
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# CHECK-NEXT: PhysicalAddress: 0x1000000
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# CHECK-NEXT: FileSize: 288
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# CHECK-NEXT: MemSize: 288
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# CHECK-NEXT: Flags [ (0x4)
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# CHECK-NEXT: PF_R (0x4)
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# CHECK-NEXT: ]
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# CHECK-NEXT: Alignment: 4096
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# CHECK-NEXT: }
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# CHECK-NEXT: ProgramHeader {
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# CHECK-NEXT: Type: PT_LOAD (0x1)
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# CHECK-NEXT: Offset: 0x1000
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# CHECK-NEXT: VirtualAddress: 0x1001000
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# CHECK-NEXT: PhysicalAddress: 0x1001000
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# CHECK-NEXT: FileSize: 1
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# CHECK-NEXT: MemSize: 1
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# CHECK-NEXT: Flags [ (0x5)
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# CHECK-NEXT: PF_R (0x4)
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# CHECK-NEXT: PF_X (0x1)
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# CHECK-NEXT: ]
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# CHECK-NEXT: Alignment: 4096
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# CHECK-NEXT: }
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# CHECK-NEXT: ProgramHeader {
49+
# CHECK-NEXT: Type: PT_GNU_STACK (0x6474E551)
50+
# CHECK-NEXT: Offset: 0x0
51+
# CHECK-NEXT: VirtualAddress: 0x0
52+
# CHECK-NEXT: PhysicalAddress: 0x0
53+
# CHECK-NEXT: FileSize: 0
54+
# CHECK-NEXT: MemSize: 0
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# CHECK-NEXT: Flags [ (0x6)
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# CHECK-NEXT: PF_R (0x4)
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# CHECK-NEXT: PF_W (0x2)
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# CHECK-NEXT: ]
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# CHECK-NEXT: Alignment: 0
60+
# CHECK-NEXT: }

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