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[llvm-objcopy] Add change-section-lma *+/-offset
llvm-objcopy did not support change-section-lma argument. This patch adds support for a use case of change-section-lma, that is shifting load address of all sections by the same offset. This seems to be the only practical use case of change-section-lma, found in other software.
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‎llvm/docs/CommandGuide/llvm-objcopy.rst

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@@ -528,6 +528,10 @@ them.
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Mark all defined global symbols as weak in the output.
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.. option:: --change-section-lma \*{+-}<offset>
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Currently only supports changing LMA for all sections by the same offset.
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MACH-O-SPECIFIC OPTIONS
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-----------------------
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‎llvm/include/llvm/ObjCopy/CommonConfig.h

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@@ -245,6 +245,9 @@ struct CommonConfig {
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// Symbol info specified by --add-symbol option.
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SmallVector<NewSymbolInfo, 0> SymbolsToAdd;
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// Integer options
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int64_t ChangeSectionLMAValAll = 0;
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// Boolean options
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bool DeterministicArchives = true;
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bool ExtractDWO = false;

‎llvm/lib/ObjCopy/ELF/ELFObjcopy.cpp

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@@ -670,6 +670,13 @@ static Error handleArgs(const CommonConfig &Config, const ELFConfig &ELFConfig,
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}
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}
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if (Config.ChangeSectionLMAValAll != 0) {
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for (auto &Seg : Obj.segments()) {
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if (Seg.FileSize > 0)
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Seg.PAddr += Config.ChangeSectionLMAValAll;
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}
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}
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if (Config.OnlyKeepDebug)
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for (auto &Sec : Obj.sections())
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if (Sec.Flags & SHF_ALLOC && Sec.Type != SHT_NOTE)

‎llvm/test/tools/llvm-objcopy/ELF/change-section-lma-multiple-load.test

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# RUN: yaml2obj %s -o %t
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# RUN: llvm-objcopy --change-section-lma *+0x20 %t %t2
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# RUN: llvm-readelf -l %t2 | FileCheck %s --check-prefix=CHECK-PLUS
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# RUN: llvm-objcopy --change-section-lma *-0x10 %t2 %t3
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# RUN: llvm-readelf -l %t3 | FileCheck %s --check-prefix=CHECK-MINUS
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# RUN: not llvm-objcopy --change-section-lma .text3=0x5000 %t 2>&1 | FileCheck %s --check-prefix=ERR
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!ELF
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FileHeader:
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Class: ELFCLASS64
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Data: ELFDATA2LSB
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Type: ET_EXEC
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Machine: EM_AARCH64
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Sections:
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- Name: .text1
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Type: SHT_PROGBITS
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Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
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Address: 0x1000
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AddressAlign: 0x1000
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Content: "DEADBEEF"
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Size: 0x1000
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- Name: .text2
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Type: SHT_PROGBITS
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Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
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Address: 0x2000
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AddressAlign: 0x1000
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Content: "32323232"
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Size: 0x1000
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- Name: .text3
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Type: SHT_PROGBITS
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Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
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Address: 0x3000
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AddressAlign: 0x1000
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Content: "c3c3c3c3"
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Size: 0x1000
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ProgramHeaders:
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- Type: PT_LOAD
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Flags: [ PF_R ]
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VAddr: 0x1000
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FirstSec: .text1
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LastSec: .text2
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# CHECK-PLUS: Type Offset VirtAddr PhysAddr FileSiz MemSiz
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# CHECK-PLUS: LOAD 0x001000 0x0000000000001000 0x0000000000001020 0x002000 0x002000
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# CHECK-MINUS: LOAD 0x001000 0x0000000000001000 0x0000000000001010 0x002000 0x002000
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- Type: PT_LOAD
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Flags: [ PF_R ]
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VAddr: 0x7000
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FirstSec: .text3
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LastSec: .text3
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# CHECK-PLUS: LOAD 0x003000 0x0000000000007000 0x0000000000007020 0x001000 0x001000
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# CHECK-MINUS: LOAD 0x003000 0x0000000000007000 0x0000000000007010 0x001000 0x001000
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# ERR: error: bad format for --change-section-lma: it is required that all sections are either incremented, or decremented at the same time; use *+val, or *-val

‎llvm/test/tools/llvm-objcopy/ELF/change-section-lma-single-load.test

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# RUN: yaml2obj %s -o %t
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# RUN: llvm-objcopy --change-section-lma *+0x20 %t %t2
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# RUN: llvm-readelf -l %t2 | FileCheck %s --check-prefix=CHECK-PLUS
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# RUN: llvm-objcopy --change-section-lma *-0x10 %t2 %t3
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# RUN: llvm-readelf -l %t3 | FileCheck %s --check-prefix=CHECK-MINUS
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# RUN: not llvm-objcopy --change-section-lma .text3=0x5000 %t 2>&1 | FileCheck %s --check-prefix=ERR
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!ELF
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FileHeader:
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Class: ELFCLASS64
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Data: ELFDATA2LSB
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Type: ET_EXEC
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Machine: EM_AARCH64
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Sections:
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- Name: .text1
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Type: SHT_PROGBITS
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Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
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Address: 0x1000
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AddressAlign: 0x1000
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Content: "DEADBEEF"
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Size: 0x1000
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- Name: .text2
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Type: SHT_PROGBITS
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Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
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Address: 0x2000
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AddressAlign: 0x1000
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Content: "32323232"
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Size: 0x1000
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- Name: .text3
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Type: SHT_PROGBITS
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Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
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Address: 0x3000
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AddressAlign: 0x1000
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Content: "c3c3c3c3"
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Size: 0x1000
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ProgramHeaders:
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- Type: PT_LOAD
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Flags: [ PF_R ]
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VAddr: 0x1000
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FirstSec: .text1
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LastSec: .text3
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# CHECK-PLUS: Type Offset VirtAddr PhysAddr FileSiz MemSiz
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# CHECK-PLUS: LOAD 0x001000 0x0000000000001000 0x0000000000001020 0x003000 0x003000
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# CHECK-MINUS: LOAD 0x001000 0x0000000000001000 0x0000000000001010 0x003000 0x003000
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# ERR: error: bad format for --change-section-lma: it is required that all sections are either incremented, or decremented at the same time; use *+val, or *-val

‎llvm/tools/llvm-objcopy/ObjcopyOptions.cpp

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@@ -552,6 +552,33 @@ static Error loadNewSectionData(StringRef ArgValue, StringRef OptionName,
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return Error::success();
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}
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static Expected<int64_t> parseAdjustSectionLMA(StringRef ArgValue,
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StringRef OptionName) {
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StringRef StringValue;
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if (ArgValue.starts_with("*+")) {
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StringValue = ArgValue.slice(2, StringRef::npos);
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} else if (ArgValue.starts_with("*-")) {
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StringValue = ArgValue.slice(1, StringRef::npos);
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} else {
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return createStringError(errc::invalid_argument,
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"bad format for " + OptionName +
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": it is required that all sections "
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"are either incremented, or decremented at "
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"the same time; use *+val, "
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"or *-val");
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}
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if (StringValue.empty())
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return createStringError(errc::invalid_argument,
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"bad format for " + OptionName +
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": missing offset of LMA");
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auto SLMAV = getAsInteger<int64_t>(StringValue);
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if (!SLMAV)
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return createStringError(SLMAV.getError(),
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"Unable to parse adjustment value");
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return *SLMAV;
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}
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// parseObjcopyOptions returns the config and sets the input arguments. If a
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// help flag is set then parseObjcopyOptions will print the help messege and
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// exit.
@@ -833,6 +860,14 @@ objcopy::parseObjcopyOptions(ArrayRef<const char *> RawArgsArr,
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Config.PadTo = *Addr;
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}
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if (const auto *Arg = InputArgs.getLastArg(OBJCOPY_adjust_section_lma)) {
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Expected<int64_t> SLMAV =
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parseAdjustSectionLMA(Arg->getValue(), Arg->getSpelling());
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if (!SLMAV)
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return SLMAV.takeError();
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Config.ChangeSectionLMAValAll = *SLMAV;
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}
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for (auto *Arg : InputArgs.filtered(OBJCOPY_redefine_symbol)) {
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if (!StringRef(Arg->getValue()).contains('='))
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return createStringError(errc::invalid_argument,

‎llvm/tools/llvm-objcopy/ObjcopyOpts.td

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@@ -254,6 +254,14 @@ def adjust_start : JoinedOrSeparate<["--"], "adjust-start">,
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Alias<change_start>,
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HelpText<"Alias for --change-start">;
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defm adjust_section_lma
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: Eq<"change-section-lma",
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"Change LMA of all sections by <val>. LMA is the physical address where the section is "
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"loaded in the memory; as opoosed to VMA, which is the virtual address at which the "
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"section resides during program execution. Ussually LMA and VMA are the same, but some "
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"platforms support these to be different resulting in runtime copying">,
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MetaVarName<"*{+|-}val">;
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defm add_symbol
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: Eq<"add-symbol", "Add new symbol <name> to .symtab. Accepted flags: "
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"global, local, weak, default, hidden, protected, file, section, object, "

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