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[llvm-objcopy] Add --change-section-address (llvm#98664)
--change-section address and its alias --adjust-section-vma allows modification of section addresses in a relocatable file. This used to be used, for example, in Fiasco microkernel. On a relocatable file this option behaves the same as GNU objcopy, apart from the fact that it does not issue any warnings, for example, when an argument is not used. GNU objcopy does not produce an error when passed an executable file but the usecase for this is not clear, and the behaviour is inconsistent. The idea of GNU objcopy --change-section-address is that the option should change both LMA and VMA in an executable file. Since this patch does not implement executable file support, only VMA is changed.
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‎llvm/docs/CommandGuide/llvm-objcopy.rst

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@@ -303,6 +303,15 @@ them.
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Shift LMA of non-zero-sized segments by ``<val>``.
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.. option:: --change-section-address <section>{=+-}<val>, --adjust-section-vma
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Change the address of sections that match ``<section>`` pattern to the
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specified value, or apply ``+<val>``/``-<val>`` to the current value. Can be
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specified multiple times to specify multiple patterns. Each section is only
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modified by one ``--change-section-address`` argument. If a section name
312+
matches multiple patterns, the rightmost change applies. The object file needs
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to be of ET_REL type.
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306315
.. option:: --change-start <incr>, --adjust-start
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Add ``<incr>`` to the program's start address. Can be specified multiple

‎llvm/include/llvm/ObjCopy/CommonConfig.h

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Original file line numberDiff line numberDiff line change
@@ -151,6 +151,18 @@ class NameMatcher {
151151
}
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};
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154+
enum class AdjustKind { Set, Add, Subtract };
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struct AddressUpdate {
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uint64_t Value = 0;
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AdjustKind Kind = AdjustKind::Add;
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};
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struct SectionPatternAddressUpdate {
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NameMatcher SectionPattern;
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AddressUpdate Update;
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};
165+
154166
enum class SymbolFlag {
155167
Global,
156168
Local,
@@ -219,6 +231,7 @@ struct CommonConfig {
219231
SmallVector<NewSectionInfo, 0> AddSection;
220232
SmallVector<StringRef, 0> DumpSection;
221233
SmallVector<NewSectionInfo, 0> UpdateSection;
234+
SmallVector<SectionPatternAddressUpdate, 0> ChangeSectionAddress;
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// Section matchers
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NameMatcher KeepSection;

‎llvm/lib/ObjCopy/ConfigManager.cpp

Lines changed: 8 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -26,7 +26,8 @@ Expected<const COFFConfig &> ConfigManager::getCOFFConfig() const {
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Common.DecompressDebugSections ||
2727
Common.DiscardMode == DiscardType::Locals ||
2828
!Common.SymbolsToAdd.empty() || Common.GapFill != 0 ||
29-
Common.PadTo != 0 || Common.ChangeSectionLMAValAll != 0)
29+
Common.PadTo != 0 || Common.ChangeSectionLMAValAll != 0 ||
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!Common.ChangeSectionAddress.empty())
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return createStringError(llvm::errc::invalid_argument,
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"option is not supported for COFF");
3233

@@ -48,7 +49,8 @@ Expected<const MachOConfig &> ConfigManager::getMachOConfig() const {
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Common.DecompressDebugSections || Common.StripUnneeded ||
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Common.DiscardMode == DiscardType::Locals ||
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!Common.SymbolsToAdd.empty() || Common.GapFill != 0 ||
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Common.PadTo != 0 || Common.ChangeSectionLMAValAll != 0)
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Common.PadTo != 0 || Common.ChangeSectionLMAValAll != 0 ||
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!Common.ChangeSectionAddress.empty())
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return createStringError(llvm::errc::invalid_argument,
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"option is not supported for MachO");
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@@ -68,7 +70,8 @@ Expected<const WasmConfig &> ConfigManager::getWasmConfig() const {
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!Common.SectionsToRename.empty() || !Common.SetSectionAlignment.empty() ||
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!Common.SetSectionFlags.empty() || !Common.SetSectionType.empty() ||
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!Common.SymbolsToRename.empty() || Common.GapFill != 0 ||
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Common.PadTo != 0 || Common.ChangeSectionLMAValAll != 0)
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Common.PadTo != 0 || Common.ChangeSectionLMAValAll != 0 ||
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!Common.ChangeSectionAddress.empty())
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return createStringError(llvm::errc::invalid_argument,
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"only flags for section dumping, removal, and "
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"addition are supported");
@@ -97,7 +100,8 @@ Expected<const XCOFFConfig &> ConfigManager::getXCOFFConfig() const {
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Common.StripDebug || Common.StripNonAlloc || Common.StripSections ||
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Common.Weaken || Common.StripUnneeded || Common.DecompressDebugSections ||
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Common.GapFill != 0 || Common.PadTo != 0 ||
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Common.ChangeSectionLMAValAll != 0) {
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Common.ChangeSectionLMAValAll != 0 ||
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!Common.ChangeSectionAddress.empty()) {
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return createStringError(
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llvm::errc::invalid_argument,
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"no flags are supported yet, only basic copying is allowed");

‎llvm/lib/ObjCopy/ELF/ELFObjcopy.cpp

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@@ -745,6 +745,56 @@ static Error handleArgs(const CommonConfig &Config, const ELFConfig &ELFConfig,
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}
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}
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if (!Config.ChangeSectionAddress.empty()) {
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if (Obj.Type != ELF::ET_REL)
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return createStringError(
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object_error::invalid_file_type,
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"cannot change section address in a non-relocatable file");
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StringMap<AddressUpdate> SectionsToUpdateAddress;
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for (const SectionPatternAddressUpdate &PatternUpdate :
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make_range(Config.ChangeSectionAddress.rbegin(),
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Config.ChangeSectionAddress.rend())) {
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for (SectionBase &Sec : Obj.sections()) {
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if (PatternUpdate.SectionPattern.matches(Sec.Name) &&
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SectionsToUpdateAddress.try_emplace(Sec.Name, PatternUpdate.Update)
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.second) {
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if (PatternUpdate.Update.Kind == AdjustKind::Subtract &&
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Sec.Addr < PatternUpdate.Update.Value) {
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return createStringError(
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errc::invalid_argument,
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"address 0x" + Twine::utohexstr(Sec.Addr) +
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" cannot be decreased by 0x" +
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Twine::utohexstr(PatternUpdate.Update.Value) +
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". The result would underflow");
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}
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if (PatternUpdate.Update.Kind == AdjustKind::Add &&
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Sec.Addr > std::numeric_limits<uint64_t>::max() -
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PatternUpdate.Update.Value) {
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return createStringError(
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errc::invalid_argument,
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"address 0x" + Twine::utohexstr(Sec.Addr) +
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" cannot be increased by 0x" +
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Twine::utohexstr(PatternUpdate.Update.Value) +
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". The result would overflow");
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}
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switch (PatternUpdate.Update.Kind) {
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case (AdjustKind::Set):
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Sec.Addr = PatternUpdate.Update.Value;
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break;
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case (AdjustKind::Subtract):
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Sec.Addr -= PatternUpdate.Update.Value;
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break;
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case (AdjustKind::Add):
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Sec.Addr += PatternUpdate.Update.Value;
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break;
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}
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}
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}
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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-address.test

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## This test tests the behavior of --change-section-address option.
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# RUN: yaml2obj -DTYPE=REL %s -o %ti1
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## Basic check that the option processes wildcards and changes the address as expected.
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# RUN: llvm-objcopy --change-section-address *+0x20 %ti1 %to1
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# RUN: llvm-readelf --section-headers %to1 | FileCheck %s --check-prefix=CHECK-ADD-ALL
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## Check that --change-section-address alias --adjust-section-vma produces the same output as the test above.
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# RUN: llvm-objcopy --adjust-section-vma *+0x20 %ti1 %to2
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# RUN: cmp %to1 %to2
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## Check that negative adjustment reduces the address by the specified value.
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# RUN: llvm-objcopy --change-section-address .anotherone-0x30 %ti1 %to3
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# RUN: llvm-readelf --section-headers %to3 | FileCheck %s --check-prefix=CHECK-SUB-SECTION
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## Check that a wildcard pattern works and only the specified sections are updated.
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# RUN: llvm-objcopy --change-section-address .text*+0x20 %ti1 %to4
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# RUN: llvm-readelf --section-headers %to4 | FileCheck %s --check-prefix=CHECK-ADD-PATTERN
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## Check that regex pattern can be used with --change-section-address.
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# RUN: llvm-objcopy --regex --change-section-address .text.+0x20 %ti1 %to5
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# RUN: llvm-readelf --section-headers %to5 | FileCheck %s --check-prefix=CHECK-ADD-PATTERN
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## Check that a section address can be set to a specific value.
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# RUN: llvm-objcopy --change-section-address .text*=0x10 %ti1 %to6
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# RUN: llvm-readelf --section-headers %to6 | FileCheck %s --check-prefix=CHECK-SET-PATTERN
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## Check setting that a section address can be set to the maximum possible value (UINT64_MAX).
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# RUN: llvm-objcopy --change-section-address .text2=0xffffffffffffffff %ti1 %to7
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# RUN: llvm-readelf --section-headers %to7 | FileCheck %s --check-prefix=CHECK-MAX
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## Check that a section address can be adjusted to the maximum possible value (UINT64_MAX).
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# RUN: llvm-objcopy --change-section-address .text2+0xfffffffffffffdff %ti1 %to8
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# RUN: llvm-readelf --section-headers %to8 | FileCheck %s --check-prefix=CHECK-MAX
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## Check that the section address can be adjusted to the minimum possible value (0).
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# RUN: llvm-objcopy --change-section-address .text2-0x200 %ti1 %to9
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# RUN: llvm-readelf --section-headers %to9 | FileCheck %s --check-prefix=CHECK-ZERO
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## Check that a section address can be adjusted by a maximum possible positive offset (UINT64_MAX).
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# RUN: llvm-objcopy --change-section-address .text2=0 %ti1 %to10
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# RUN: llvm-objcopy --change-section-address .text2+0xffffffffffffffff %to10 %to11
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# RUN: llvm-readelf --section-headers %to11 | FileCheck %s --check-prefix=CHECK-MAX
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## Check that a section address can be adjusted by a maximum possible negative offset (UINT64_MIN).
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# RUN: llvm-objcopy --change-section-address .text2=0xffffffffffffffff %ti1 %to12
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# RUN: llvm-objcopy --change-section-address .text2-0xffffffffffffffff %to12 %to13
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# RUN: llvm-readelf --section-headers %to13 | FileCheck %s --check-prefix=CHECK-ZERO
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## Check two independent changes.
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# RUN: llvm-objcopy --change-section-address .text1=0x110 --change-section-address .text2=0x210 %ti1 %to14
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# RUN: llvm-readelf --section-headers %to14 | FileCheck %s --check-prefix=CHECK-INDEPENDENT
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## Check two overlapping changes.
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# RUN: llvm-objcopy --change-section-address .anotherone-0x30 --change-section-address .anotherone+0x20 %ti1 %to15
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# RUN: llvm-readelf --section-headers %to15 | FileCheck %s --check-prefix=CHECK-USE-LAST
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## Check unused option.
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# RUN: llvm-objcopy --change-section-address .anotherone=0x455 --change-section-address *+0x20 %ti1 %to16
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# RUN: llvm-readelf --section-headers %to16 | FileCheck %s --check-prefix=CHECK-NOTSUPERSET-SET
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## Check partial overlap (.anotherone overlaps).
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# RUN: llvm-objcopy --change-section-address *+0x20 --change-section-address .anotherone=0x455 %ti1 %to17
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# RUN: llvm-readelf --section-headers %to17 | FileCheck %s --check-prefix=CHECK-SUPERSET-SET
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## Check more complex partial overlap (P1: .anotherone, .text2, P2: .text1, text2) (.text2 overlaps).
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# RUN: llvm-objcopy --regex --change-section-address ".(text2|anotherone)+0x20" --change-section-address .text.*+0x30 %ti1 %to18
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# RUN: llvm-readelf --section-headers %to18 | FileCheck %s --check-prefix=CHECK-PARTIAL-OVERLAP
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# CHECK-ADD-ALL: [Nr] Name Type Address
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# CHECK-ADD-ALL: .text1
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# CHECK-ADD-ALL-SAME: 0000000000000120
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# CHECK-ADD-ALL: .text2
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# CHECK-ADD-ALL-SAME: 0000000000000220
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# CHECK-ADD-ALL: .anotherone
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# CHECK-ADD-ALL-SAME: 0000000000000320
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# CHECK-ADD-ALL: =a-b+c++d
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# CHECK-ADD-ALL-SAME: 0000000000000420
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# CHECK-ADD-ALL: .strtab
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# CHECK-ADD_ALL-SAME: 0000000000000020
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# CHECK-ADD-ALL: .shstrtab
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# CHECK-ADD-ALL-SAME: 0000000000000020
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# CHECK-SUB-SECTION: .text1
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# CHECK-SUB-SECTION-SAME: 0000000000000100
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# CHECK-SUB-SECTION: .text2
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# CHECK-SUB-SECTION-SAME: 0000000000000200
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# CHECK-SUB-SECTION: .anotherone
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# CHECK-SUB-SECTION-SAME: 00000000000002d0
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# CHECK-ADD-PATTERN: .text1
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# CHECK-ADD-PATTERN-SAME: 0000000000000120
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# CHECK-ADD-PATTERN: .text2
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# CHECK-ADD-PATTERN-SAME: 0000000000000220
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# CHECK-ADD-PATTERN: .anotherone
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# CHECK-ADD-PATTERN-SAME: 0000000000000300
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# CHECK-SET-PATTERN: .text1
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# CHECK-SET-PATTERN-SAME: 0000000000000010
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# CHECK-SET-PATTERN: .text2
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# CHECK-SET-PATTERN-SAME: 0000000000000010
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# CHECK-SET-PATTERN: .anotherone
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# CHECK-SET-PATTERN-SAME: 0000000000000300
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# CHECK-MAX: .text2
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# CHECK-MAX-SAME: ffffffffffffffff
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# CHECK-ZERO: .text2
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# CHECK-ZERO-SAME: 0000000000000000
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# CHECK-INDEPENDENT: .text1
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# CHECK-INDEPENDENT-SAME: 0000000000000110
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# CHECK-INDEPENDENT: .text2
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# CHECK-INDEPENDENT-SAME: 0000000000000210
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# CHECK-USE-LAST: .anotherone
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# CHECK-USE-LAST-SAME: 0000000000000320
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# CHECK-NOTSUPERSET-SET: .text1
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# CHECK-NOTSUPERSET-SET-SAME: 0000000000000120
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# CHECK-NOTSUPERSET-SET: .text2
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# CHECK-NOTSUPERSET-SET-SAME: 0000000000000220
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# CHECK-NOTSUPERSET-SET: .anotherone
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# CHECK-NOTSUPERSET-SET-SAME: 0000000000000320
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# CHECK-SUPERSET-SET: .text1
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# CHECK-SUPERSET-SET-SAME: 0000000000000120
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# CHECK-SUPERSET-SET: .text2
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# CHECK-SUPERSET-SET-SAME: 0000000000000220
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# CHECK-SUPERSET-SET: .anotherone
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# CHECK-SUPERSET-SET-SAME: 0000000000000455
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# CHECK-PARTIAL-OVERLAP: .text1
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# CHECK-PARTIAL-OVERLAP-SAME: 0000000000000130
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# CHECK-PARTIAL-OVERLAP: .text2
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# CHECK-PARTIAL-OVERLAP-SAME: 0000000000000230
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# CHECK-PARTIAL-OVERLAP: .anotherone
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# CHECK-PARTIAL-OVERLAP-SAME: 0000000000000320
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## Check overflow by 1.
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# RUN: not llvm-objcopy --change-section-address .anotherone+0xfffffffffffffd00 %ti1 2>&1 | FileCheck %s --check-prefix=ERR-OVERFLOW
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## Check underflow by 1.
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# RUN: not llvm-objcopy --change-section-address .text2-0x201 %ti1 2>&1 | FileCheck %s --check-prefix=ERR-UNDERFLOW
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## Check error when argument value is invalid as a whole.
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# RUN: not llvm-objcopy --change-section-address 0 %ti1 2>&1 | FileCheck %s --check-prefix=ERR-IVALID-VAL
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## Check error when the value is invalid in the argument value.
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# RUN: not llvm-objcopy --change-section-address .anotherone+0c50 %ti1 2>&1 | FileCheck %s --check-prefix=ERR-NOT-INTEGER
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## Check error when the value does not fit in uint64_t.
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# RUN not llvm-objcopy --change-section-address .text1=0x10000000000000000 %ti1 %to 2>&1 | FileCheck %s --chack-prefix=ERR-NOT-INTEGER
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## Check error when the section pattern is missing.
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# RUN: not llvm-objcopy --change-section-address =0x10 %ti1 2>&1 | FileCheck %s --check-prefix=ERR-MISSING-SECTION
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## Check error when the negative adjustment value is missing.
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# RUN: not llvm-objcopy --change-section-address .text1- %ti1 2>&1 | FileCheck %s --check-prefix=ERR-MISSING-VALUE-MINUS
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## Check error when the positive adjustment value is missing.
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# RUN: not llvm-objcopy --change-section-address .text1+ %ti1 2>&1 | FileCheck %s --check-prefix=ERR-MISSING-VALUE-PLUS
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## Check error when the value to set the address to is missing.
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# RUN: not llvm-objcopy --change-section-address .text1= %ti1 2>&1 | FileCheck %s --check-prefix=ERR-MISSING-VALUE-EQUAL
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## Check error when the provided regex is invalid.
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# RUN: not llvm-objcopy --regex --change-section-address "ab**-0x20" %ti1 2>&1 | FileCheck %s --check-prefix=ERR-MATCHER-FAILURE
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# ERR-OVERFLOW: address 0x300 cannot be increased by 0xfffffffffffffd00. The result would overflow
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# ERR-UNDERFLOW: address 0x200 cannot be decreased by 0x201. The result would underflow
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# ERR-IVALID-VAL: error: bad format for --change-section-address: argument value 0 is invalid. See --help
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# ERR-NOT-INTEGER: error: bad format for --change-section-address: value after + is 0c50 when it should be a 64-bit integer
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# ERR-MISSING-SECTION: error: bad format for --change-section-address: missing section pattern to apply address change to
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# ERR-MISSING-VALUE-MINUS: error: bad format for --change-section-address: missing value of offset after '-'
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# ERR-MISSING-VALUE-PLUS: error: bad format for --change-section-address: missing value of offset after '+'
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# ERR-MISSING-VALUE-EQUAL: error: bad format for --change-section-address: missing address value after '='
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# ERR-MATCHER-FAILURE: error: cannot compile regular expression 'ab**': repetition-operator operand invalid
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--- !ELF
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FileHeader:
173+
Class: ELFCLASS64
174+
Data: ELFDATA2LSB
175+
Type: ET_[[TYPE]]
176+
Sections:
177+
- Name: .text1
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Type: SHT_PROGBITS
179+
Size: 0x100
180+
Address: 0x100
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- Name: .text2
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Type: SHT_PROGBITS
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Size: 0x100
184+
Address: 0x200
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- Name: .anotherone
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Type: SHT_PROGBITS
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Size: 0x100
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Address: 0x300
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- Name: =a-b+c++d
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Type: SHT_PROGBITS
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Size: 0x100
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Address: 0x400
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194+
# RUN: yaml2obj -DTYPE=EXEC %s -o %ti2
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196+
## Input file is not ET_REL
197+
# RUN: not llvm-objcopy --change-section-address *+0x20 %ti2 2>&1 | FileCheck %s --check-prefix=ERR-FILE-TYPE
198+
199+
# ERR-FILE-TYPE: cannot change section address in a non-relocatable file

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