[llvm] c781e73 - [yaml2obj] - Add a way to exclude specified sections from the section header.
Georgii Rymar via llvm-commits
llvm-commits at lists.llvm.org
Thu Jun 4 03:51:06 PDT 2020
Author: Georgii Rymar
Date: 2020-06-04T13:50:35+03:00
New Revision: c781e7370e9b408f27996175fcf07b02905e6db4
URL: https://github.com/llvm/llvm-project/commit/c781e7370e9b408f27996175fcf07b02905e6db4
DIFF: https://github.com/llvm/llvm-project/commit/c781e7370e9b408f27996175fcf07b02905e6db4.diff
LOG: [yaml2obj] - Add a way to exclude specified sections from the section header.
This implements a new "Excluded" key that can be used
to exclude entries from section header:
```
SectionHeaderTable:
Sections:
...
Excluded:
- Name: .foo
```
Differential revision: https://reviews.llvm.org/D81005
Added:
llvm/test/tools/yaml2obj/ELF/section-headers-exclude.yaml
Modified:
llvm/include/llvm/ObjectYAML/ELFYAML.h
llvm/lib/ObjectYAML/ELFEmitter.cpp
llvm/lib/ObjectYAML/ELFYAML.cpp
llvm/test/tools/yaml2obj/ELF/section-headers.yaml
Removed:
################################################################################
diff --git a/llvm/include/llvm/ObjectYAML/ELFYAML.h b/llvm/include/llvm/ObjectYAML/ELFYAML.h
index 5b96283b786e..b88a10eecad7 100644
--- a/llvm/include/llvm/ObjectYAML/ELFYAML.h
+++ b/llvm/include/llvm/ObjectYAML/ELFYAML.h
@@ -93,6 +93,7 @@ struct SectionHeader {
struct SectionHeaderTable {
std::vector<SectionHeader> Sections;
+ Optional<std::vector<SectionHeader>> Excluded;
};
struct SectionName {
diff --git a/llvm/lib/ObjectYAML/ELFEmitter.cpp b/llvm/lib/ObjectYAML/ELFEmitter.cpp
index 8cc322f8275a..02b2c94516fb 100644
--- a/llvm/lib/ObjectYAML/ELFEmitter.cpp
+++ b/llvm/lib/ObjectYAML/ELFEmitter.cpp
@@ -128,6 +128,8 @@ template <class ELFT> class ELFState {
NameToIdxMap DynSymN2I;
ELFYAML::Object &Doc;
+ StringSet<> ExcludedSectionHeaders;
+
uint64_t LocationCounter = 0;
bool HasError = false;
yaml::ErrorHandler ErrHandler;
@@ -230,6 +232,8 @@ template <class ELFT> class ELFState {
uint64_t alignToOffset(ContiguousBlobAccumulator &CBA, uint64_t Align,
llvm::Optional<llvm::yaml::Hex64> Offset);
+ uint64_t getSectionNameOffset(StringRef Name);
+
public:
static bool writeELF(raw_ostream &OS, ELFYAML::Object &Doc,
yaml::ErrorHandler EH);
@@ -350,7 +354,8 @@ void ELFState<ELFT>::writeELFHeader(ContiguousBlobAccumulator &CBA, raw_ostream
if (Doc.Header.SHStrNdx)
Header.e_shstrndx = *Doc.Header.SHStrNdx;
- else if (!Doc.SectionHeaders || !Doc.SectionHeaders->Sections.empty())
+ else if ((!Doc.SectionHeaders || !Doc.SectionHeaders->Sections.empty()) &&
+ !ExcludedSectionHeaders.count(".shstrtab"))
Header.e_shstrndx = SN2I.get(".shstrtab");
else
Header.e_shstrndx = 0;
@@ -397,18 +402,32 @@ void ELFState<ELFT>::initProgramHeaders(std::vector<Elf_Phdr> &PHeaders) {
template <class ELFT>
unsigned ELFState<ELFT>::toSectionIndex(StringRef S, StringRef LocSec,
StringRef LocSym) {
+ assert(LocSec.empty() || LocSym.empty());
+
unsigned Index;
- if (SN2I.lookup(S, Index) || to_integer(S, Index))
+ if (!SN2I.lookup(S, Index) && !to_integer(S, Index)) {
+ if (!LocSym.empty())
+ reportError("unknown section referenced: '" + S + "' by YAML symbol '" +
+ LocSym + "'");
+ else
+ reportError("unknown section referenced: '" + S + "' by YAML section '" +
+ LocSec + "'");
+ return 0;
+ }
+
+ if (!Doc.SectionHeaders || !Doc.SectionHeaders->Excluded)
return Index;
- assert(LocSec.empty() || LocSym.empty());
- if (!LocSym.empty())
- reportError("unknown section referenced: '" + S + "' by YAML symbol '" +
- LocSym + "'");
- else
- reportError("unknown section referenced: '" + S + "' by YAML section '" +
- LocSec + "'");
- return 0;
+ assert(!Doc.SectionHeaders->Sections.empty());
+ if (Index >= Doc.SectionHeaders->Sections.size()) {
+ if (LocSym.empty())
+ reportError("unable to link '" + LocSec + "' to excluded section '" + S +
+ "'");
+ else
+ reportError("excluded section referenced: '" + S + "' by symbol '" +
+ LocSym + "'");
+ }
+ return Index;
}
template <class ELFT>
@@ -498,6 +517,15 @@ StringRef llvm::ELFYAML::dropUniqueSuffix(StringRef S) {
return S.substr(0, SuffixPos - 1);
}
+template <class ELFT>
+uint64_t ELFState<ELFT>::getSectionNameOffset(StringRef Name) {
+ // If a section is excluded from section headers, we do not save its name in
+ // the string table.
+ if (ExcludedSectionHeaders.count(Name))
+ return 0;
+ return DotShStrtab.getOffset(Name);
+}
+
template <class ELFT>
void ELFState<ELFT>::initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
ContiguousBlobAccumulator &CBA) {
@@ -531,7 +559,7 @@ void ELFState<ELFT>::initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
"implicit sections should already have been handled above.");
SHeader.sh_name =
- DotShStrtab.getOffset(ELFYAML::dropUniqueSuffix(Sec->Name));
+ getSectionNameOffset(ELFYAML::dropUniqueSuffix(Sec->Name));
SHeader.sh_type = Sec->Type;
if (Sec->Flags)
SHeader.sh_flags = *Sec->Flags;
@@ -716,7 +744,7 @@ void ELFState<ELFT>::initSymtabSectionHeader(Elf_Shdr &SHeader,
}
zero(SHeader);
- SHeader.sh_name = DotShStrtab.getOffset(IsStatic ? ".symtab" : ".dynsym");
+ SHeader.sh_name = getSectionNameOffset(IsStatic ? ".symtab" : ".dynsym");
if (YAMLSec)
SHeader.sh_type = YAMLSec->Type;
@@ -733,10 +761,13 @@ void ELFState<ELFT>::initSymtabSectionHeader(Elf_Shdr &SHeader,
// added implicitly and we should be able to leave the Link zeroed if
// .dynstr is not defined.
unsigned Link = 0;
- if (IsStatic)
- Link = SN2I.get(".strtab");
- else
- SN2I.lookup(".dynstr", Link);
+ if (IsStatic) {
+ if (!ExcludedSectionHeaders.count(".strtab"))
+ Link = SN2I.get(".strtab");
+ } else {
+ if (!ExcludedSectionHeaders.count(".dynstr"))
+ SN2I.lookup(".dynstr", Link);
+ }
SHeader.sh_link = Link;
}
@@ -777,7 +808,7 @@ void ELFState<ELFT>::initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
ContiguousBlobAccumulator &CBA,
ELFYAML::Section *YAMLSec) {
zero(SHeader);
- SHeader.sh_name = DotShStrtab.getOffset(Name);
+ SHeader.sh_name = getSectionNameOffset(Name);
SHeader.sh_type = YAMLSec ? YAMLSec->Type : ELF::SHT_STRTAB;
SHeader.sh_addralign = YAMLSec ? (uint64_t)YAMLSec->AddressAlign : 1;
@@ -832,7 +863,7 @@ void ELFState<ELFT>::initDWARFSectionHeader(Elf_Shdr &SHeader, StringRef Name,
ContiguousBlobAccumulator &CBA,
ELFYAML::Section *YAMLSec) {
zero(SHeader);
- SHeader.sh_name = DotShStrtab.getOffset(ELFYAML::dropUniqueSuffix(Name));
+ SHeader.sh_name = getSectionNameOffset(ELFYAML::dropUniqueSuffix(Name));
SHeader.sh_type = YAMLSec ? YAMLSec->Type : ELF::SHT_PROGBITS;
SHeader.sh_addralign = YAMLSec ? (uint64_t)YAMLSec->AddressAlign : 1;
SHeader.sh_offset = alignToOffset(CBA, SHeader.sh_addralign,
@@ -866,9 +897,8 @@ void ELFState<ELFT>::initDWARFSectionHeader(Elf_Shdr &SHeader, StringRef Name,
else if (Name == ".debug_str")
SHeader.sh_flags = ELF::SHF_MERGE | ELF::SHF_STRINGS;
- unsigned Link = 0;
- if (YAMLSec && !YAMLSec->Link.empty() && SN2I.lookup(YAMLSec->Link, Link))
- SHeader.sh_link = Link;
+ if (YAMLSec && !YAMLSec->Link.empty())
+ SHeader.sh_link = toSectionIndex(YAMLSec->Link, Name);
assignSectionAddress(SHeader, YAMLSec);
}
@@ -992,7 +1022,8 @@ void ELFState<ELFT>::writeSectionContent(
// For relocation section set link to .symtab by default.
unsigned Link = 0;
- if (Section.Link.empty() && SN2I.lookup(".symtab", Link))
+ if (Section.Link.empty() && !ExcludedSectionHeaders.count(".symtab") &&
+ SN2I.lookup(".symtab", Link))
SHeader.sh_link = Link;
if (!Section.RelocatableSec.empty())
@@ -1065,7 +1096,8 @@ void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
"Section type is not SHT_GROUP");
unsigned Link = 0;
- if (Section.Link.empty() && SN2I.lookup(".symtab", Link))
+ if (Section.Link.empty() && !ExcludedSectionHeaders.count(".symtab") &&
+ SN2I.lookup(".symtab", Link))
SHeader.sh_link = Link;
SHeader.sh_entsize = 4;
@@ -1190,7 +1222,8 @@ void ELFState<ELFT>::writeSectionContent(
SHeader.sh_entsize = 16;
unsigned Link = 0;
- if (Section.Link.empty() && SN2I.lookup(".symtab", Link))
+ if (Section.Link.empty() && !ExcludedSectionHeaders.count(".symtab") &&
+ SN2I.lookup(".symtab", Link))
SHeader.sh_link = Link;
raw_ostream &OS = CBA.getOS();
@@ -1218,7 +1251,8 @@ void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::HashSection &Section,
ContiguousBlobAccumulator &CBA) {
unsigned Link = 0;
- if (Section.Link.empty() && SN2I.lookup(".dynsym", Link))
+ if (Section.Link.empty() && !ExcludedSectionHeaders.count(".dynsym") &&
+ SN2I.lookup(".dynsym", Link))
SHeader.sh_link = Link;
raw_ostream &OS = CBA.getOS();
@@ -1408,7 +1442,8 @@ void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::AddrsigSection &Section,
ContiguousBlobAccumulator &CBA) {
unsigned Link = 0;
- if (Section.Link.empty() && SN2I.lookup(".symtab", Link))
+ if (Section.Link.empty() && !ExcludedSectionHeaders.count(".symtab") &&
+ SN2I.lookup(".symtab", Link))
SHeader.sh_link = Link;
raw_ostream &OS = CBA.getOS();
@@ -1474,7 +1509,8 @@ void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::GnuHashSection &Section,
ContiguousBlobAccumulator &CBA) {
unsigned Link = 0;
- if (Section.Link.empty() && SN2I.lookup(".dynsym", Link))
+ if (Section.Link.empty() && !ExcludedSectionHeaders.count(".dynsym") &&
+ SN2I.lookup(".dynsym", Link))
SHeader.sh_link = Link;
raw_ostream &OS = CBA.getOS();
@@ -1556,12 +1592,20 @@ DenseMap<StringRef, size_t> ELFState<ELFT>::buildSectionHeaderReorderMap() {
DenseMap<StringRef, size_t> Ret;
size_t SecNdx = 0;
StringSet<> Seen;
- for (const ELFYAML::SectionHeader &Hdr : Doc.SectionHeaders->Sections) {
+
+ auto AddSection = [&](const ELFYAML::SectionHeader &Hdr) {
if (!Ret.try_emplace(Hdr.Name, ++SecNdx).second)
reportError("repeated section name: '" + Hdr.Name +
"' in the section header description");
Seen.insert(Hdr.Name);
- }
+ };
+
+ for (const ELFYAML::SectionHeader &Hdr : Doc.SectionHeaders->Sections)
+ AddSection(Hdr);
+
+ if (Doc.SectionHeaders->Excluded)
+ for (const ELFYAML::SectionHeader &Hdr : *Doc.SectionHeaders->Excluded)
+ AddSection(Hdr);
for (const ELFYAML::Section *S : Doc.getSections()) {
// Ignore special first SHT_NULL section.
@@ -1569,7 +1613,7 @@ DenseMap<StringRef, size_t> ELFState<ELFT>::buildSectionHeaderReorderMap() {
continue;
if (!Seen.count(S->Name))
reportError("section '" + S->Name +
- "' should be present in the 'Sections' list");
+ "' should be present in the 'Sections' or 'Excluded' lists");
Seen.erase(S->Name);
}
@@ -1579,21 +1623,36 @@ DenseMap<StringRef, size_t> ELFState<ELFT>::buildSectionHeaderReorderMap() {
return Ret;
}
+static bool hasSectionHeader(const ELFYAML::Object &Doc, size_t SecNdx) {
+ if (!Doc.SectionHeaders)
+ return true;
+ return SecNdx < Doc.SectionHeaders->Sections.size();
+}
+
template <class ELFT> void ELFState<ELFT>::buildSectionIndex() {
- // A YAML description can have an explicit section header declaration that allows
- // to change the order of section headers.
+ // A YAML description can have an explicit section header declaration that
+ // allows to change the order of section headers.
DenseMap<StringRef, size_t> ReorderMap = buildSectionHeaderReorderMap();
+ if (HasError)
+ return;
+
+ // Build excluded section headers map.
+ if (Doc.SectionHeaders && Doc.SectionHeaders->Excluded)
+ for (const ELFYAML::SectionHeader &Hdr : *Doc.SectionHeaders->Excluded)
+ if (!ExcludedSectionHeaders.insert(Hdr.Name).second)
+ llvm_unreachable("buildSectionIndex() failed");
+
size_t SecNdx = -1;
- for (const std::unique_ptr<ELFYAML::Chunk> &C : Doc.Chunks) {
- if (!isa<ELFYAML::Section>(C.get()))
- continue;
+ for (const ELFYAML::Section *S : Doc.getSections()) {
++SecNdx;
- size_t Index = ReorderMap.empty() ? SecNdx : ReorderMap.lookup(C->Name);
- if (!SN2I.addName(C->Name, Index))
+ size_t Index = ReorderMap.empty() ? SecNdx : ReorderMap.lookup(S->Name);
+ if (!SN2I.addName(S->Name, Index))
llvm_unreachable("buildSectionIndex() failed");
- DotShStrtab.add(ELFYAML::dropUniqueSuffix(C->Name));
+
+ if (!ExcludedSectionHeaders.count(S->Name))
+ DotShStrtab.add(ELFYAML::dropUniqueSuffix(S->Name));
}
DotShStrtab.finalize();
@@ -1663,6 +1722,9 @@ bool ELFState<ELFT>::writeELF(raw_ostream &OS, ELFYAML::Object &Doc,
State.buildSectionIndex();
State.buildSymbolIndexes();
+ if (State.HasError)
+ return false;
+
std::vector<Elf_Phdr> PHeaders;
State.initProgramHeaders(PHeaders);
diff --git a/llvm/lib/ObjectYAML/ELFYAML.cpp b/llvm/lib/ObjectYAML/ELFYAML.cpp
index 98a40c906bee..87f4eea126ae 100644
--- a/llvm/lib/ObjectYAML/ELFYAML.cpp
+++ b/llvm/lib/ObjectYAML/ELFYAML.cpp
@@ -840,6 +840,7 @@ void MappingTraits<ELFYAML::SectionHeader>::mapping(
void MappingTraits<ELFYAML::SectionHeaderTable>::mapping(
IO &IO, ELFYAML::SectionHeaderTable &SectionHeader) {
IO.mapRequired("Sections", SectionHeader.Sections);
+ IO.mapOptional("Excluded", SectionHeader.Excluded);
}
void MappingTraits<ELFYAML::FileHeader>::mapping(IO &IO,
diff --git a/llvm/test/tools/yaml2obj/ELF/section-headers-exclude.yaml b/llvm/test/tools/yaml2obj/ELF/section-headers-exclude.yaml
new file mode 100644
index 000000000000..a244643f93e3
--- /dev/null
+++ b/llvm/test/tools/yaml2obj/ELF/section-headers-exclude.yaml
@@ -0,0 +1,478 @@
+## Check how we can use the "Excluded" key of the "SectionHeaderTable" tag to exclude
+## entries from the section header table.
+
+## Check we can use the "Excluded" key to omit a section from the section header table.
+## Check we do not include the name of the excluded section in the string table.
+# RUN: yaml2obj %s -DINCLUDED=.foo -DEXCLUDED=.bar --docnum=1 -o %t1
+# RUN: llvm-readelf --section-headers -p .shstrtab %t1 | \
+# RUN: FileCheck %s -DSEC=.foo --check-prefixes=INCLUDE-SEC,INCLUDE-FOO
+# RUN: yaml2obj %s -DINCLUDED=.bar -DEXCLUDED=.foo --docnum=1 -o %t2
+# RUN: llvm-readelf --section-headers -p .shstrtab %t2 | \
+# RUN: FileCheck %s -DSEC=.bar --check-prefixes=INCLUDE-SEC,INCLUDE-BAR
+
+# INCLUDE-SEC: [Nr] Name
+# INCLUDE-SEC: [ 1] [[SEC]]
+# INCLUDE-SEC-NEXT: [ 2] .strtab
+# INCLUDE-SEC-NEXT: [ 3] .shstrtab
+
+# INCLUDE-SEC: String dump of section '.shstrtab':
+# INCLUDE-FOO-NEXT: [ 1] .foo
+# INCLUDE-BAR-NEXT: [ 1] .bar
+# INCLUDE-SEC-NEXT: [ 6] .shstrtab
+# INCLUDE-SEC-NEXT: [ 10] .strtab
+# INCLUDE-SEC-NOT: {{.}}
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_REL
+ Machine: EM_X86_64
+Sections:
+ - Name: .foo
+ Type: SHT_PROGBITS
+ - Name: .bar
+ Type: SHT_PROGBITS
+SectionHeaderTable:
+ Sections:
+ - Name: [[INCLUDED]]
+ - Name: .strtab
+ - Name: .shstrtab
+ Excluded:
+ - Name: [[EXCLUDED]]
+
+## Check we report an error when a section is in both the "Sections" and "Excluded" lists at the same time.
+## Also check that we report an error if a section is missing from the lists.
+# RUN: not yaml2obj %s -DINCLUDED=.bar -DEXCLUDED=.strtab --docnum=1 -o /dev/null 2>&1 | \
+# RUN: FileCheck %s --check-prefix=EXCLUDE-INCLUDED
+
+# EXCLUDE-INCLUDED: error: repeated section name: '.strtab' in the section header description
+# EXCLUDE-INCLUDED: error: section '.foo' should be present in the 'Sections' or 'Excluded' lists
+
+## Check we report an error when the `Excluded` key mentions an unknown section.
+# RUN: not yaml2obj %s -DINCLUDED=.bar -DEXCLUDED=.unknown --docnum=1 -o /dev/null 2>&1 | \
+# RUN: FileCheck %s --check-prefix=EXCLUDE-UNKNOWN
+
+# EXCLUDE-UNKNOWN: error: section '.foo' should be present in the 'Sections' or 'Excluded' lists
+# EXCLUDE-UNKNOWN: error: section header contains undefined section '.unknown'
+
+## Check we report an error when the `Excluded` key mentions a section more than once.
+# RUN: not yaml2obj %s --docnum=2 -o /dev/null 2>&1 | FileCheck %s --check-prefix=EXCLUDE-TWICE
+
+# EXCLUDE-TWICE: error: repeated section name: '.strtab' in the section header description
+# EXCLUDE-TWICE: error: repeated section name: '.strtab' in the section header description
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_REL
+ Machine: EM_X86_64
+SectionHeaderTable:
+ Sections:
+ - Name: .strtab
+ - Name: .shstrtab
+ Excluded:
+ - Name: .strtab
+ - Name: .strtab
+
+## Check we are able to exclude all sections.
+# RUN: yaml2obj %s --docnum=3 -o %t3
+# RUN: llvm-readelf --section-headers %t3 | FileCheck %s --check-prefix=NO-SECTIONS
+
+# NO-SECTIONS: There are 0 section headers, starting at offset 0x0:
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_REL
+ Machine: EM_X86_64
+SectionHeaderTable:
+ Sections: []
+ Excluded:
+ - Name: .strtab
+
+## Check how we handle cases when a section is excluded, but its section index is needed.
+## The general rule is: when a section is explicitly linked with another section, which is
+## excluded, then we report an error. In the case when it is linked implicitly with an excluded
+## section, we use 0 as index value.
+
+## Case A: check we report an error when a regular section has a Link field which
+## points to an excluded section.
+# RUN: not yaml2obj %s --docnum=4 -o /dev/null 2>&1 | \
+# RUN: FileCheck %s --check-prefix=LINK -DSEC=.foo -DTARGET=.bar
+
+# LINK: error: unable to link '[[SEC]]' to excluded section '[[TARGET]]'
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_REL
+ Machine: EM_X86_64
+Sections:
+ - Name: .foo
+ Type: SHT_PROGBITS
+ Link: .bar
+ - Name: .bar
+ Type: SHT_PROGBITS
+SectionHeaderTable:
+ Sections:
+ - Name: .foo
+ - Name: .strtab
+ - Name: .shstrtab
+ Excluded:
+ - Name: .bar
+
+## Case B.1: check we report an error when a symbol table section has a Link field which
+## points to an excluded section.
+# RUN: not yaml2obj %s --docnum=5 -DNAME=.symtab -DTYPE=SHT_SYMTAB -o /dev/null 2>&1 | \
+# RUN: FileCheck %s --check-prefix=LINK -DSEC=.symtab -DTARGET=.foo
+# RUN: not yaml2obj %s --docnum=5 -DNAME=.dynsym -DTYPE=SHT_DYNSYM -o /dev/null 2>&1 | \
+# RUN: FileCheck %s --check-prefix=LINK -DSEC=.dynsym -DTARGET=.foo
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_DYN
+ Machine: EM_X86_64
+Sections:
+ - Name: [[NAME]]
+ Type: [[TYPE]]
+ Link: .foo
+ - Name: .foo
+ Type: SHT_PROGBITS
+SectionHeaderTable:
+ Sections:
+ - Name: [[NAME]]
+ - Name: .strtab
+ - Name: .shstrtab
+ Excluded:
+ - Name: .foo
+
+## Case B.2: check we do not link .dynsym with .dynstr implicitly when the latter is excluded.
+# RUN: yaml2obj %s --docnum=6 -o %t4
+# RUN: llvm-readelf %t4 --section-headers | FileCheck %s --check-prefix=LINK-DYNSYM
+
+# LINK-DYNSYM: [Nr] Name Type Address Off Size ES Flg Lk
+# LINK-DYNSYM: [ 1] .dynsym DYNSYM 0000000000000000 000040 000018 18 A 0
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_DYN
+ Machine: EM_X86_64
+Sections:
+ - Name: .dynsym
+ Type: SHT_DYNSYM
+ - Name: .dynstr
+ Type: SHT_PROGBITS
+SectionHeaderTable:
+ Sections:
+ - Name: .dynsym
+ - Name: .strtab
+ - Name: .shstrtab
+ Excluded:
+ - Name: .dynstr
+
+## Case B.3: check we do not link .symtab with .strtab implicitly when the latter is excluded.
+# RUN: yaml2obj %s --docnum=7 -o %t5
+# RUN: llvm-readelf %t5 --section-headers | FileCheck %s --check-prefix=LINK-SYMTAB
+
+# LINK-SYMTAB: [Nr] Name Type Address Off Size ES Flg Lk Inf Al
+# LINK-SYMTAB: [ 1] .symtab SYMTAB 0000000000000000 000040 000018 18 0 1 0
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_DYN
+ Machine: EM_X86_64
+Sections:
+ - Name: .symtab
+ Type: SHT_SYMTAB
+ - Name: .strtab
+ Type: SHT_PROGBITS
+SectionHeaderTable:
+ Sections:
+ - Name: .symtab
+ - Name: .shstrtab
+ Excluded:
+ - Name: .strtab
+
+## Case C: check we report an error when a debug section has a Link field which
+## points to an excluded section.
+# RUN: not yaml2obj %s --docnum=8 -o /dev/null 2>&1 | \
+# RUN: FileCheck %s --check-prefix=LINK -DSEC=.debug_unknown -DTARGET=.strtab
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_EXEC
+ Machine: EM_X86_64
+Sections:
+ - Name: .debug_unknown
+ Type: SHT_PROGBITS
+ Link: .strtab
+SectionHeaderTable:
+ Sections:
+ - Name: .debug_unknown
+ - Name: .shstrtab
+ Excluded:
+ - Name: .strtab
+
+## Case D.1: check we report an error when a relocatable section has an Info field which
+## points to an excluded section.
+# RUN: not yaml2obj %s --docnum=9 -o /dev/null 2>&1 | \
+# RUN: FileCheck %s --check-prefix=LINK -DSEC=.rela -DTARGET=.strtab
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_DYN
+ Machine: EM_X86_64
+Sections:
+ - Name: .rela
+ Type: SHT_RELA
+ Info: .strtab
+ Relocations: []
+SectionHeaderTable:
+ Sections:
+ - Name: .rela
+ - Name: .shstrtab
+ Excluded:
+ - Name: .strtab
+
+## Case D.2: check we report an error when the SHT_REL[A] section is linked
+## with an excluded section explicitly.
+# RUN: not yaml2obj %s --docnum=10 -o /dev/null 2>&1 | \
+# RUN: FileCheck %s --check-prefix=LINK -DSEC=.rela -DTARGET=.symtab
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_DYN
+ Machine: EM_X86_64
+Sections:
+ - Name: .rela
+ Type: SHT_RELA
+ Link: .symtab
+ Relocations: []
+ - Name: .symtab
+ Type: SHT_PROGBITS
+SectionHeaderTable:
+ Sections:
+ - Name: .rela
+ - Name: .strtab
+ - Name: .shstrtab
+ Excluded:
+ - Name: .symtab
+
+## Case E: check we report an error when a symbol references an excluded section.
+# RUN: not yaml2obj %s --docnum=11 -o /dev/null 2>&1 | \
+# RUN: FileCheck %s --check-prefix=SYMBOL-SECTION
+
+# SYMBOL-SECTION: error: excluded section referenced: '.foo' by symbol 'foo'
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_DYN
+ Machine: EM_X86_64
+Sections:
+ - Name: .foo
+ Type: SHT_PROGBITS
+Symbols:
+ - Name: foo
+ Type: STT_OBJECT
+ Section: .foo
+SectionHeaderTable:
+ Sections:
+ - Name: .symtab
+ - Name: .strtab
+ - Name: .shstrtab
+ Excluded:
+ - Name: .foo
+
+## Case F.1: check we report an error when a group section
+## contains an excluded section member.
+# RUN: not yaml2obj %s --docnum=12 -o /dev/null 2>&1 | \
+# RUN: FileCheck %s --check-prefix=LINK -DSEC=.group -DTARGET=.strtab
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_REL
+ Machine: EM_X86_64
+Sections:
+ - Name: .group
+ Type: SHT_GROUP
+ Members:
+ - SectionOrType: .strtab
+SectionHeaderTable:
+ Sections:
+ - Name: .group
+ - Name: .shstrtab
+ Excluded:
+ - Name: .strtab
+
+## Case F.2: check we report an error when the group section is linked
+## to an excluded section explicitly.
+# RUN: not yaml2obj %s --docnum=13 -o /dev/null 2>&1 | \
+# RUN: FileCheck %s --check-prefix=LINK -DSEC=.group -DTARGET=.symtab
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_REL
+ Machine: EM_X86_64
+Sections:
+ - Name: .group
+ Type: SHT_GROUP
+ Link: .symtab
+ Members: []
+ - Name: .symtab
+ Type: SHT_SYMTAB
+SectionHeaderTable:
+ Sections:
+ - Name: .group
+ - Name: .strtab
+ - Name: .shstrtab
+ Excluded:
+ - Name: .symtab
+
+## Case G: check we do not link SHT_LLVM_CALL_GRAPH_PROFILE/SHT_LLVM_ADDRSIG/SHT_GROUP/SHT_REL[A] sections
+## with .symtab implicitly when the latter is excluded.
+# RUN: yaml2obj %s --docnum=14 -o %t6
+# RUN: llvm-readelf %t6 --section-headers | FileCheck %s --check-prefix=LINK-IMPLICIT
+
+# LINK-IMPLICIT: [Nr] Name Type Address Off Size ES Flg Lk Inf Al
+# LINK-IMPLICIT: [ 1] .cgp LLVM_CALL_GRAPH_PROFILE 0000000000000000 000040 000000 10 0 0 0
+# LINK-IMPLICIT-NEXT: [ 2] .llvm_addrsig LLVM_ADDRSIG 0000000000000000 000040 000000 00 0 0 0
+# LINK-IMPLICIT-NEXT: [ 3] .group GROUP 0000000000000000 000040 000000 04 0 0 0
+# LINK-IMPLICIT-NEXT: [ 4] .rela RELA 0000000000000000 000040 000000 18 0 0 0
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_DYN
+ Machine: EM_X86_64
+Sections:
+ - Name: .cgp
+ Type: SHT_LLVM_CALL_GRAPH_PROFILE
+ Content: ""
+ - Name: .llvm_addrsig
+ Type: SHT_LLVM_ADDRSIG
+ Content: ""
+ - Name: .group
+ Type: SHT_GROUP
+ Members: []
+ - Name: .rela
+ Type: SHT_RELA
+ Relocations: []
+ - Name: .symtab
+ Type: SHT_SYMTAB
+SectionHeaderTable:
+ Sections:
+ - Name: .cgp
+ - Name: .llvm_addrsig
+ - Name: .group
+ - Name: .rela
+ - Name: .strtab
+ - Name: .shstrtab
+ Excluded:
+ - Name: .symtab
+
+## Case H: check we do not link SHT_HASH/SHT_GNU_HASH sections with .dynsym
+## implicitly when the latter is excluded.
+# RUN: yaml2obj %s --docnum=15 -o %t7
+# RUN: llvm-readelf %t7 --section-headers | FileCheck %s --check-prefix=LINK-HASH
+
+# LINK-HASH: [Nr] Name Type Address Off Size ES Flg Lk Inf Al
+# LINK-HASH: [ 1] .hash HASH 0000000000000000 000040 000000 00 0 0 0
+# LINK-HASH-NEXT: [ 2] .gnu_hash GNU_HASH 0000000000000000 000040 000000 00 0 0 0
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_DYN
+ Machine: EM_X86_64
+Sections:
+ - Name: .hash
+ Type: SHT_HASH
+ Content: ""
+ - Name: .gnu_hash
+ Type: SHT_GNU_HASH
+ Content: ""
+ - Name: .dynsym
+ Type: SHT_DYNSYM
+SectionHeaderTable:
+ Sections:
+ - Name: .hash
+ - Name: .gnu_hash
+ - Name: .strtab
+ - Name: .shstrtab
+ Excluded:
+ - Name: .dynsym
+
+## Case I: document the case when an excluded section is explicitly linked to another excluded section.
+## We report an error in this case, because:
+## 1) It is a reasonable behavior, as it is perhaps usually a result of a mistake
+## in a YAML description.
+## 2) Helps to keep the code simpler.
+# RUN: not yaml2obj %s --docnum=16 -o /dev/null 2>&1 | FileCheck %s --check-prefix=CROSS-LINK
+
+# CROSS-LINK: error: unable to link '.foo' to excluded section '.bar'
+# CROSS-LINK-NEXT: error: unable to link '.bar' to excluded section '.foo'
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_REL
+ Machine: EM_X86_64
+Sections:
+ - Name: .foo
+ Type: SHT_PROGBITS
+ Link: .bar
+ - Name: .bar
+ Type: SHT_PROGBITS
+ Link: .foo
+SectionHeaderTable:
+ Sections:
+ - Name: .strtab
+ - Name: .shstrtab
+ Excluded:
+ - Name: .foo
+ - Name: .bar
+
+## Check we set e_shstrndx field to 0 when the section header string table is excluded.
+## Check that the e_shnum field is adjusted properly when a section is removed.
+# RUN: yaml2obj --docnum=17 %s -o %t9
+# RUN: llvm-readelf --file-headers %t9 | FileCheck %s --check-prefix=SHSTRTAB
+
+# SHSTRTAB: Number of section headers: 2
+# SHSTRTAB: Section header string table index: 0
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_REL
+ Machine: EM_X86_64
+SectionHeaderTable:
+ Sections:
+ - Name: .strtab
+ Excluded:
+ - Name: .shstrtab
diff --git a/llvm/test/tools/yaml2obj/ELF/section-headers.yaml b/llvm/test/tools/yaml2obj/ELF/section-headers.yaml
index ee0049d4d31d..8e2f6f5a3091 100644
--- a/llvm/test/tools/yaml2obj/ELF/section-headers.yaml
+++ b/llvm/test/tools/yaml2obj/ELF/section-headers.yaml
@@ -68,15 +68,15 @@ SectionHeaderTable:
# RUN: FileCheck %s --check-prefix=ERR2
# ERR1: error: repeated section name: '.section.foo' in the section header description
-# ERR1-NEXT: error: section '.section (1)' should be present in the 'Sections' list
-# ERR1-NEXT: error: section '.section (2)' should be present in the 'Sections' list
+# ERR1-NEXT: error: section '.section (1)' should be present in the 'Sections' or 'Excluded' lists
+# ERR1-NEXT: error: section '.section (2)' should be present in the 'Sections' or 'Excluded' lists
# ERR1-NEXT: error: section header contains undefined section 'unknown'
# ERR2: error: repeated section name: '.strtab' in the section header description
# ERR2-NEXT: error: repeated section name: '.shstrtab' in the section header description
-# ERR2-NEXT: error: section '.section (1)' should be present in the 'Sections' list
-# ERR2-NEXT: error: section '.section (2)' should be present in the 'Sections' list
-# ERR2-NEXT: error: section '.section.foo' should be present in the 'Sections' list
+# ERR2-NEXT: error: section '.section (1)' should be present in the 'Sections' or 'Excluded' lists
+# ERR2-NEXT: error: section '.section (2)' should be present in the 'Sections' or 'Excluded' lists
+# ERR2-NEXT: error: section '.section.foo' should be present in the 'Sections' or 'Excluded' lists
# ERR2-NEXT: error: section header contains undefined section '.filler'
## Test that we are able to specify an empty sections list for
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