[llvm] [llvm-objcopy] Add --change-section-address (PR #98664)
Eleanor Bonnici via llvm-commits
llvm-commits at lists.llvm.org
Fri Jul 12 10:20:06 PDT 2024
https://github.com/eleanor-arm created https://github.com/llvm/llvm-project/pull/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.
>From bee89de92bae8f1ea54512538d67e07d48a01d51 Mon Sep 17 00:00:00 2001
From: Eleanor Bonnici <eleanor.bonnici at arm.com>
Date: Wed, 19 Jun 2024 14:31:11 +0100
Subject: [PATCH] [llvm-objcopy] Add --change-section-address
--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.
---
llvm/docs/CommandGuide/llvm-objcopy.rst | 9 ++
llvm/include/llvm/ObjCopy/CommonConfig.h | 96 +++++++++++++---------
llvm/lib/ObjCopy/ConfigManager.cpp | 12 ++-
llvm/lib/ObjCopy/ELF/ELFObjcopy.cpp | 46 +++++++++++
llvm/tools/llvm-objcopy/ObjcopyOptions.cpp | 69 ++++++++++++++++
llvm/tools/llvm-objcopy/ObjcopyOpts.td | 8 ++
6 files changed, 197 insertions(+), 43 deletions(-)
diff --git a/llvm/docs/CommandGuide/llvm-objcopy.rst b/llvm/docs/CommandGuide/llvm-objcopy.rst
index 8ccb025a3f0f3..78663fb1cef23 100644
--- a/llvm/docs/CommandGuide/llvm-objcopy.rst
+++ b/llvm/docs/CommandGuide/llvm-objcopy.rst
@@ -303,6 +303,15 @@ them.
Shift LMA of non-zero-sized segments by ``<val>``.
+.. option:: --change-section-address <sectionpattern>{=+-}<val>, --adjust-section-vma
+
+ Change the address of ``<sectionpattern>`` to the specified value, or apply
+ offset to the current value. Can be specified multiple times to specify multiple
+ patterns. Each section is only modified by one --change-section-address
+ argument. Changes apply from the right of the command line. If a section name
+ matches multiple patterns, the rightmost change applies. Object file needs to be
+ relocatable.
+
.. option:: --change-start <incr>, --adjust-start
Add ``<incr>`` to the program's start address. Can be specified multiple
diff --git a/llvm/include/llvm/ObjCopy/CommonConfig.h b/llvm/include/llvm/ObjCopy/CommonConfig.h
index 7f9d90d528b3e..5e447670c4f99 100644
--- a/llvm/include/llvm/ObjCopy/CommonConfig.h
+++ b/llvm/include/llvm/ObjCopy/CommonConfig.h
@@ -44,45 +44,6 @@ struct MachineInfo {
bool IsLittleEndian;
};
-// Flags set by --set-section-flags or --rename-section. Interpretation of these
-// is format-specific and not all flags are meaningful for all object file
-// formats. This is a bitmask; many section flags may be set.
-enum SectionFlag {
- SecNone = 0,
- SecAlloc = 1 << 0,
- SecLoad = 1 << 1,
- SecNoload = 1 << 2,
- SecReadonly = 1 << 3,
- SecDebug = 1 << 4,
- SecCode = 1 << 5,
- SecData = 1 << 6,
- SecRom = 1 << 7,
- SecMerge = 1 << 8,
- SecStrings = 1 << 9,
- SecContents = 1 << 10,
- SecShare = 1 << 11,
- SecExclude = 1 << 12,
- SecLarge = 1 << 13,
- LLVM_MARK_AS_BITMASK_ENUM(/*LargestValue=*/SecLarge)
-};
-
-struct SectionRename {
- StringRef OriginalName;
- StringRef NewName;
- std::optional<SectionFlag> NewFlags;
-};
-
-struct SectionFlagsUpdate {
- StringRef Name;
- SectionFlag NewFlags;
-};
-
-enum class DiscardType {
- None, // Default
- All, // --discard-all (-x)
- Locals, // --discard-locals (-X)
-};
-
enum class MatchStyle {
Literal, // Default for symbols.
Wildcard, // Default for sections, or enabled with --wildcard (-w).
@@ -191,6 +152,61 @@ struct NewSectionInfo {
std::shared_ptr<MemoryBuffer> SectionData;
};
+// Flags set by --set-section-flags or --rename-section. Interpretation of these
+// is format-specific and not all flags are meaningful for all object file
+// formats. This is a bitmask; many section flags may be set.
+enum SectionFlag {
+ SecNone = 0,
+ SecAlloc = 1 << 0,
+ SecLoad = 1 << 1,
+ SecNoload = 1 << 2,
+ SecReadonly = 1 << 3,
+ SecDebug = 1 << 4,
+ SecCode = 1 << 5,
+ SecData = 1 << 6,
+ SecRom = 1 << 7,
+ SecMerge = 1 << 8,
+ SecStrings = 1 << 9,
+ SecContents = 1 << 10,
+ SecShare = 1 << 11,
+ SecExclude = 1 << 12,
+ SecLarge = 1 << 13,
+ LLVM_MARK_AS_BITMASK_ENUM(/*LargestValue=*/SecLarge)
+};
+
+struct SectionRename {
+ StringRef OriginalName;
+ StringRef NewName;
+ std::optional<SectionFlag> NewFlags;
+};
+
+struct SectionFlagsUpdate {
+ StringRef Name;
+ SectionFlag NewFlags;
+};
+
+struct AddressUpdate {
+ uint64_t Value = 0;
+ bool Absolute = false;
+ bool Negative = false;
+};
+
+struct SectionPatternAddressUpdate {
+ NameMatcher SectionPattern;
+ AddressUpdate Update;
+};
+
+struct SectionNameAddressUpdate {
+ StringRef Name;
+ AddressUpdate Update;
+};
+
+enum class DiscardType {
+ None, // Default
+ All, // --discard-all (-x)
+ Locals, // --discard-locals (-X)
+};
+
// Configuration for copying/stripping a single file.
struct CommonConfig {
// Main input/output options
@@ -219,6 +235,7 @@ struct CommonConfig {
SmallVector<NewSectionInfo, 0> AddSection;
SmallVector<StringRef, 0> DumpSection;
SmallVector<NewSectionInfo, 0> UpdateSection;
+ SmallVector<SectionPatternAddressUpdate, 0> ChangeSectionAddress;
// Section matchers
NameMatcher KeepSection;
@@ -241,6 +258,7 @@ struct CommonConfig {
StringMap<SectionFlagsUpdate> SetSectionFlags;
StringMap<uint64_t> SetSectionType;
StringMap<StringRef> SymbolsToRename;
+ StringMap<AddressUpdate> SectionsToUpdateAddress;
// Symbol info specified by --add-symbol option.
SmallVector<NewSymbolInfo, 0> SymbolsToAdd;
diff --git a/llvm/lib/ObjCopy/ConfigManager.cpp b/llvm/lib/ObjCopy/ConfigManager.cpp
index c542c4e5f0743..78fc0c451e1a3 100644
--- a/llvm/lib/ObjCopy/ConfigManager.cpp
+++ b/llvm/lib/ObjCopy/ConfigManager.cpp
@@ -26,7 +26,8 @@ Expected<const COFFConfig &> ConfigManager::getCOFFConfig() const {
Common.DecompressDebugSections ||
Common.DiscardMode == DiscardType::Locals ||
!Common.SymbolsToAdd.empty() || Common.GapFill != 0 ||
- Common.PadTo != 0 || Common.ChangeSectionLMAValAll != 0)
+ Common.PadTo != 0 || Common.ChangeSectionLMAValAll != 0 ||
+ !Common.ChangeSectionAddress.empty())
return createStringError(llvm::errc::invalid_argument,
"option is not supported for COFF");
@@ -48,7 +49,8 @@ Expected<const MachOConfig &> ConfigManager::getMachOConfig() const {
Common.DecompressDebugSections || Common.StripUnneeded ||
Common.DiscardMode == DiscardType::Locals ||
!Common.SymbolsToAdd.empty() || Common.GapFill != 0 ||
- Common.PadTo != 0 || Common.ChangeSectionLMAValAll != 0)
+ Common.PadTo != 0 || Common.ChangeSectionLMAValAll != 0 ||
+ !Common.ChangeSectionAddress.empty())
return createStringError(llvm::errc::invalid_argument,
"option is not supported for MachO");
@@ -68,7 +70,8 @@ Expected<const WasmConfig &> ConfigManager::getWasmConfig() const {
!Common.SectionsToRename.empty() || !Common.SetSectionAlignment.empty() ||
!Common.SetSectionFlags.empty() || !Common.SetSectionType.empty() ||
!Common.SymbolsToRename.empty() || Common.GapFill != 0 ||
- Common.PadTo != 0 || Common.ChangeSectionLMAValAll != 0)
+ Common.PadTo != 0 || Common.ChangeSectionLMAValAll != 0 ||
+ !Common.ChangeSectionAddress.empty())
return createStringError(llvm::errc::invalid_argument,
"only flags for section dumping, removal, and "
"addition are supported");
@@ -97,7 +100,8 @@ Expected<const XCOFFConfig &> ConfigManager::getXCOFFConfig() const {
Common.StripDebug || Common.StripNonAlloc || Common.StripSections ||
Common.Weaken || Common.StripUnneeded || Common.DecompressDebugSections ||
Common.GapFill != 0 || Common.PadTo != 0 ||
- Common.ChangeSectionLMAValAll != 0) {
+ Common.ChangeSectionLMAValAll != 0 ||
+ !Common.ChangeSectionAddress.empty()) {
return createStringError(
llvm::errc::invalid_argument,
"no flags are supported yet, only basic copying is allowed");
diff --git a/llvm/lib/ObjCopy/ELF/ELFObjcopy.cpp b/llvm/lib/ObjCopy/ELF/ELFObjcopy.cpp
index 075455c034154..718d6f2739382 100644
--- a/llvm/lib/ObjCopy/ELF/ELFObjcopy.cpp
+++ b/llvm/lib/ObjCopy/ELF/ELFObjcopy.cpp
@@ -745,6 +745,52 @@ static Error handleArgs(const CommonConfig &Config, const ELFConfig &ELFConfig,
}
}
+ if (!Config.ChangeSectionAddress.empty()) {
+ if (Obj.isRelocatable()) {
+ StringMap<AddressUpdate> SectionsToUpdateAddress;
+ for (const SectionPatternAddressUpdate &PatternUpdate :
+ make_range(Config.ChangeSectionAddress.rbegin(),
+ Config.ChangeSectionAddress.rend())) {
+ for (SectionBase &Sec : Obj.sections()) {
+ if (PatternUpdate.SectionPattern.matches(Sec.Name)) {
+ if (SectionsToUpdateAddress
+ .try_emplace(Sec.Name, PatternUpdate.Update)
+ .second) {
+ if (PatternUpdate.Update.Absolute) {
+ Sec.Addr = PatternUpdate.Update.Value;
+ } else if (PatternUpdate.Update.Negative &&
+ Sec.Addr < PatternUpdate.Update.Value) {
+ return createStringError(
+ errc::invalid_argument,
+ "address 0x" + Twine::utohexstr(Sec.Addr) +
+ " cannot be decreased by 0x" +
+ Twine::utohexstr(PatternUpdate.Update.Value) +
+ ". The result would underflow");
+ } else if (!PatternUpdate.Update.Negative &&
+ Sec.Addr > std::numeric_limits<uint64_t>::max() -
+ PatternUpdate.Update.Value) {
+ return createStringError(
+ errc::invalid_argument,
+ "address 0x" + Twine::utohexstr(Sec.Addr) +
+ " cannot be increased by 0x" +
+ Twine::utohexstr(PatternUpdate.Update.Value) +
+ ". The result would overflow");
+ } else if (PatternUpdate.Update.Negative) {
+ Sec.Addr -= PatternUpdate.Update.Value;
+ } else {
+ Sec.Addr += PatternUpdate.Update.Value;
+ }
+ }
+ }
+ }
+ }
+ } else {
+ return createStringError(
+ object_error::invalid_file_type,
+ "cannot change section address in a non-relocatable file");
+ }
+ }
+
if (Config.OnlyKeepDebug)
for (auto &Sec : Obj.sections())
if (Sec.Flags & SHF_ALLOC && Sec.Type != SHT_NOTE)
diff --git a/llvm/tools/llvm-objcopy/ObjcopyOptions.cpp b/llvm/tools/llvm-objcopy/ObjcopyOptions.cpp
index a54feb7644bda..be4511c1d7c00 100644
--- a/llvm/tools/llvm-objcopy/ObjcopyOptions.cpp
+++ b/llvm/tools/llvm-objcopy/ObjcopyOptions.cpp
@@ -584,6 +584,65 @@ static Expected<int64_t> parseChangeSectionLMA(StringRef ArgValue,
return *LMAValue;
}
+static Expected<SectionPatternAddressUpdate>
+parseChangeSectionAddr(StringRef ArgValue, StringRef OptionName,
+ MatchStyle SectionMatchStyle,
+ function_ref<Error(Error)> ErrorCallback) {
+
+ SectionPatternAddressUpdate PatternUpdate;
+ std::pair<StringRef, StringRef> UpdateParts;
+ std::string UpdateSymbol;
+
+ if (ArgValue.contains("+")) {
+ UpdateParts = ArgValue.split("+");
+ UpdateSymbol = '+';
+ } else if (ArgValue.contains("-")) {
+ UpdateParts = ArgValue.split("-");
+ UpdateSymbol = '-';
+ PatternUpdate.Update.Negative = true;
+ } else if (ArgValue.contains("=")) {
+ UpdateParts = ArgValue.split("=");
+ UpdateSymbol = '=';
+ PatternUpdate.Update.Absolute = true;
+ } else {
+ return createStringError(errc::invalid_argument,
+ "bad format for " + OptionName +
+ ": argument value " + ArgValue +
+ " is invalid. See help");
+ }
+
+ if (UpdateParts.second.empty()) {
+ if (UpdateSymbol == "+" || UpdateSymbol == "-")
+ return createStringError(errc::invalid_argument,
+ "bad format for " + OptionName +
+ ": missing value of offset after '" +
+ UpdateSymbol + "'");
+ else if (UpdateSymbol == "=")
+ return createStringError(errc::invalid_argument,
+ "bad format for " + OptionName +
+ ": missing address value after '='");
+ }
+ if (UpdateParts.first.empty())
+ return createStringError(
+ errc::invalid_argument,
+ "bad format for " + OptionName +
+ ": missing section pattern to apply address change to");
+
+ if (Error E = PatternUpdate.SectionPattern.addMatcher(NameOrPattern::create(
+ UpdateParts.first, SectionMatchStyle, ErrorCallback)))
+ return std::move(E);
+
+ auto AddrValue = getAsInteger<uint64_t>(UpdateParts.second);
+ if (!AddrValue)
+ return createStringError(AddrValue.getError(),
+ "bad format for " + OptionName + ": value after " +
+ UpdateSymbol + " is " + UpdateParts.second +
+ " when it should be an integer");
+
+ PatternUpdate.Update.Value = *AddrValue;
+ return PatternUpdate;
+}
+
// parseObjcopyOptions returns the config and sets the input arguments. If a
// help flag is set then parseObjcopyOptions will print the help messege and
// exit.
@@ -874,6 +933,16 @@ objcopy::parseObjcopyOptions(ArrayRef<const char *> RawArgsArr,
Config.ChangeSectionLMAValAll = *LMAValue;
}
+ for (auto *Arg : InputArgs.filtered(OBJCOPY_change_section_address)) {
+ Expected<SectionPatternAddressUpdate> AddressUpdate =
+ parseChangeSectionAddr(Arg->getValue(), Arg->getSpelling(),
+ SectionMatchStyle, ErrorCallback);
+ if (!AddressUpdate)
+ return AddressUpdate.takeError();
+ else
+ Config.ChangeSectionAddress.push_back(*AddressUpdate);
+ }
+
for (auto *Arg : InputArgs.filtered(OBJCOPY_redefine_symbol)) {
if (!StringRef(Arg->getValue()).contains('='))
return createStringError(errc::invalid_argument,
diff --git a/llvm/tools/llvm-objcopy/ObjcopyOpts.td b/llvm/tools/llvm-objcopy/ObjcopyOpts.td
index b26c497ca3997..15bfbd7ab7b23 100644
--- a/llvm/tools/llvm-objcopy/ObjcopyOpts.td
+++ b/llvm/tools/llvm-objcopy/ObjcopyOpts.td
@@ -267,6 +267,14 @@ defm change_section_lma
: Eq<"change-section-lma", "Shift LMA of non-zero-sized sections in the program header by <val>">,
MetaVarName<"*{+|-}val">;
+defm change_section_address
+ : Eq<"change-section-address", "Set, or adjust the address of sections in <sectionpattern> to, "
+ "or by <val> in a relocatable file">,
+ MetaVarName<"sectionpattern{=|+|-}val">;
+def adjust_section_vma : JoinedOrSeparate<["--"], "adjust-section-vma">,
+ Alias<change_section_address>,
+ HelpText<"Alias for --change-section-address">;
+
defm add_symbol
: Eq<"add-symbol", "Add new symbol <name> to .symtab. Accepted flags: "
"global, local, weak, default, hidden, protected, file, section, object, "
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