[llvm] 7b424b9 - [llvm-objcopy] Rename relocation sections together with their targets.
Igor Kudrin via llvm-commits
llvm-commits at lists.llvm.org
Wed Sep 29 02:36:49 PDT 2021
Author: Igor Kudrin
Date: 2021-09-29T16:36:37+07:00
New Revision: 7b424b933355c972da006e9afd560d4e534d08f8
URL: https://github.com/llvm/llvm-project/commit/7b424b933355c972da006e9afd560d4e534d08f8
DIFF: https://github.com/llvm/llvm-project/commit/7b424b933355c972da006e9afd560d4e534d08f8.diff
LOG: [llvm-objcopy] Rename relocation sections together with their targets.
As for now, llvm-objcopy renames only sections that are specified
explicitly in --rename-section, while GNU objcopy keeps names of
relocation sections in sync with their targets. For example:
> readelf -S test.o
...
[ 1] .foo PROGBITS
[ 2] .rela.foo RELA
> objcopy --rename-section .foo=.bar test.o gnu.o
> readelf -S gnu.o
...
[ 1] .bar PROGBITS
[ 2] .rela.bar RELA
> llvm-objcopy --rename-section .foo=.bar test.o llvm.o
> readelf -S llvm.o
...
[ 1] .bar PROGBITS
[ 2] .rela.foo RELA
This patch makes llvm-objcopy to match the behavior of GNU objcopy better.
Differential Revision: https://reviews.llvm.org/D110352
Added:
llvm/test/tools/llvm-objcopy/ELF/rename-section-relocsec.test
Modified:
llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp
Removed:
################################################################################
diff --git a/llvm/test/tools/llvm-objcopy/ELF/rename-section-relocsec.test b/llvm/test/tools/llvm-objcopy/ELF/rename-section-relocsec.test
new file mode 100644
index 0000000000000..d1f7ce556c14a
--- /dev/null
+++ b/llvm/test/tools/llvm-objcopy/ELF/rename-section-relocsec.test
@@ -0,0 +1,103 @@
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-objcopy %t %t1 \
+# RUN: --rename-section=.tst1.foo=.tst1.ren.foo \
+# RUN: --rename-section=.tst1.bar=.tst1.ren.bar \
+# RUN: --rename-section=.tst2.foo=.tst2.ren.foo \
+# RUN: --rename-section=.tst3.foo=.tst3.ren.foo \
+# RUN: --rename-section=.tst4.foo=.tst4.ren.foo \
+# RUN: --rename-section=.rel.tst4.foo=.tst4.ren.foo.rel \
+# RUN: --rename-section=.tst6.got.plt=.tst6.ren.got.plt \
+# RUN: --rename-section=.tst7.rela.plt=.tst7.ren.rela.plt
+# RUN: llvm-readobj --sections %t1 | FileCheck %s
+
+!ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_REL
+ Machine: EM_X86_64
+Sections:
+
+## Test 1. When a section is renamed, its relocation section should be renamed
+## similarly.
+# CHECK: Name: .tst1.ren.foo{{ }}
+# CHECK: Name: .rel.tst1.ren.foo{{ }}
+# CHECK: Name: .rela.tst1.ren.bar{{ }}
+# CHECK: Name: .tst1.ren.bar{{ }}
+ - Name: .tst1.foo
+ Type: SHT_PROGBITS
+ - Name: .rel.tst1.foo
+ Type: SHT_REL
+ Info: .tst1.foo
+ - Name: .rela.tst1.bar
+ Type: SHT_RELA
+ Info: .tst1.bar
+ - Name: .tst1.bar
+ Type: SHT_PROGBITS
+
+## Test 2. A relocation section should be renamed together with its target
+## section even if its name does not follow the typical pattern.
+# CHECK: Name: .tst2.ren.foo{{ }}
+# CHECK: Name: .rel.tst2.ren.foo{{ }}
+ - Name: .tst2.foo
+ Type: SHT_PROGBITS
+ - Name: .tst2.foo.rel
+ Type: SHT_REL
+ Info: .tst2.foo
+
+## Test 3. A relocation section should not be renamed if an unrelated section
+## with the same common name is renamed.
+## Note that '.rel.tst3.foo' targets '.tst3.bar', not '.tst3.foo'
+# CHECK: Name: .tst3.ren.foo{{ }}
+# CHECK: Name: .tst3.bar{{ }}
+# CHECK: Name: .rel.tst3.foo{{ }}
+ - Name: .tst3.foo
+ Type: SHT_PROGBITS
+ - Name: .tst3.bar
+ Type: SHT_PROGBITS
+ - Name: .rel.tst3.foo
+ Type: SHT_REL
+ Info: .tst3.bar
+
+## Test 4. A relocation section can be renamed with an explicit --rename-section
+## command. Explicit renaming overrides implicit one.
+# CHECK: Name: .tst4.ren.foo{{ }}
+# CHECK: Name: .tst4.ren.foo.rel{{ }}
+ - Name: .tst4.foo
+ Type: SHT_PROGBITS
+ - Name: .rel.tst4.foo
+ Type: SHT_REL
+ Info: .tst4.foo
+
+## Test 5. Should not rename a relocation section if it or its target are not
+## specified in --rename-section.
+## Note that this diverges from GNU objcopy.
+# CHECK: Name: .tst5.foo{{ }}
+# CHECK: Name: .tst5.foo.rel{{ }}
+ - Name: .tst5.foo
+ Type: SHT_PROGBITS
+ - Name: .tst5.foo.rel
+ Type: SHT_REL
+ Info: .tst5.foo
+
+## Test 6. A dynamic relocation section should not be renamed together with its
+## target section.
+# CHECK: Name: .tst6.rela.plt{{ }}
+# CHECK: Name: .tst6.ren.got.plt{{ }}
+ - Name: .tst6.rela.plt
+ Type: SHT_RELA
+ Flags: [ SHF_ALLOC ]
+ Info: .tst6.got.plt
+ - Name: .tst6.got.plt
+ Type: SHT_PROGBITS
+
+## Test 7. A dynamic relocation section can be renamed with an explicit
+## --rename-section command.
+# CHECK: Name: .tst7.ren.rela.plt{{ }}
+# CHECK: Name: .tst7.got.plt{{ }}
+ - Name: .tst7.rela.plt
+ Type: SHT_RELA
+ Flags: [ SHF_ALLOC ]
+ Info: .tst7.got.plt
+ - Name: .tst7.got.plt
+ Type: SHT_PROGBITS
diff --git a/llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp b/llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp
index ece1334d69636..8aa6d79145b08 100644
--- a/llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp
+++ b/llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp
@@ -588,14 +588,32 @@ static Error handleArgs(const CommonConfig &Config, const ELFConfig &ELFConfig,
return E;
if (!Config.SectionsToRename.empty()) {
+ std::vector<RelocationSectionBase *> RelocSections;
+ DenseSet<SectionBase *> RenamedSections;
for (SectionBase &Sec : Obj.sections()) {
+ auto *RelocSec = dyn_cast<RelocationSectionBase>(&Sec);
const auto Iter = Config.SectionsToRename.find(Sec.Name);
if (Iter != Config.SectionsToRename.end()) {
const SectionRename &SR = Iter->second;
Sec.Name = std::string(SR.NewName);
if (SR.NewFlags.hasValue())
setSectionFlagsAndType(Sec, SR.NewFlags.getValue());
- }
+ RenamedSections.insert(&Sec);
+ } else if (RelocSec && !(Sec.Flags & SHF_ALLOC))
+ // Postpone processing relocation sections which are not specified in
+ // their explicit '--rename-section' commands until after their target
+ // sections are renamed.
+ // Dynamic relocation sections (i.e. ones with SHF_ALLOC) should be
+ // renamed only explicitly. Otherwise, renaming, for example, '.got.plt'
+ // would affect '.rela.plt', which is not desirable.
+ RelocSections.push_back(RelocSec);
+ }
+
+ // Rename relocation sections according to their target sections.
+ for (RelocationSectionBase *RelocSec : RelocSections) {
+ auto Iter = RenamedSections.find(RelocSec->getSection());
+ if (Iter != RenamedSections.end())
+ RelocSec->Name = (RelocSec->getNamePrefix() + (*Iter)->Name).str();
}
}
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