[yaml2elf] - Support describing .stack_sizes sections using unique suffixes.

[grimar]

Summary

Currently we can't use unique suffixes in section names to describe
stack sizes sections. E.g. '.stack_sizes [1]' will be treated as a regular section.
This happens because we recognize stack sizes section by name and
do not yet drop the suffix before the check.

The patch fixes it.

[jhenderson]

LGTM, with two suggestions.

test/tools/yaml2obj/elf-stack-sizes.yaml

231

Maybe worth saying "describe multiple .stack_sizes sections..."

234

I think "UNIQUE" might be a better prefix here.

include/llvm/ObjectYAML/ELFYAML.h

 #include "llvm/Support/YAMLTraits.h"
 #include <cstdint>
 #include <memory>
 #include <vector>
 
 namespace llvm {
 namespace ELFYAML {
 
+StringRef dropUniqueSuffix(StringRef S);
+
 // These types are invariant across 32/64-bit ELF, so for simplicity just
 // directly give them their exact sizes. We don't need to worry about
 // endianness because these are just the types in the YAMLIO structures,
 // and are appropriately converted to the necessary endianness when
 // reading/generating binary object files.
 // The naming of these types is intended to be ELF_PREFIX, where PREFIX is
 // the common prefix of the respective constants. E.g. ELF_EM corresponds
 // to the `e_machine` constants, like `EM_X86_64`.

lib/ObjectYAML/ELFEmitter.cpp

if (YAMLSec->ShOffset)
       Header.sh_offset = *YAMLSec->ShOffset;
     if (YAMLSec->ShSize)
       Header.sh_size = *YAMLSec->ShSize;
   }
 
   return true;
 }
 
-static StringRef dropUniqueSuffix(StringRef S) {
+StringRef llvm::ELFYAML::dropUniqueSuffix(StringRef S) {
   size_t SuffixPos = S.rfind(" [");
   if (SuffixPos == StringRef::npos)
     return S;
   return S.substr(0, SuffixPos);
 }
 
 template <class ELFT>
 void ELFState<ELFT>::initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
for (size_t I = 0; I < Doc.Sections.size(); ++I) {
     Elf_Shdr &SHeader = SHeaders[I];
     if (initImplicitHeader(CBA, SHeader, Sec->Name,
                            Sec->IsImplicit ? nullptr : Sec))
       continue;
 
     assert(Sec && "It can't be null unless it is an implicit section. But all "
                   "implicit sections should already have been handled above.");
 
-    SHeader.sh_name = DotShStrtab.getOffset(dropUniqueSuffix(Sec->Name));
+    SHeader.sh_name =
+        DotShStrtab.getOffset(ELFYAML::dropUniqueSuffix(Sec->Name));
     SHeader.sh_type = Sec->Type;
     if (Sec->Flags)
       SHeader.sh_flags = *Sec->Flags;
     SHeader.sh_addr = Sec->Address;
     SHeader.sh_addralign = Sec->AddressAlign;
 
     if (!Sec->Link.empty())
       SHeader.sh_link = toSectionIndex(Sec->Link, Sec->Name);
for (const auto &Sym : Symbols) {
     Elf_Sym &Symbol = Ret[++I];
 
     // If NameIndex, which contains the name offset, is explicitly specified, we
     // use it. This is useful for preparing broken objects. Otherwise, we add
     // the specified Name to the string table builder to get its offset.
     if (Sym.NameIndex)
       Symbol.st_name = *Sym.NameIndex;
     else if (!Sym.Name.empty())
-      Symbol.st_name = Strtab.getOffset(dropUniqueSuffix(Sym.Name));
+      Symbol.st_name = Strtab.getOffset(ELFYAML::dropUniqueSuffix(Sym.Name));
 
     Symbol.setBindingAndType(Sym.Binding, Sym.Type);
     if (!Sym.Section.empty())
       Symbol.st_shndx = toSectionIndex(Sym.Section, "", Sym.Name);
     else if (Sym.Index)
       Symbol.st_shndx = *Sym.Index;
 
     Symbol.st_value = Sym.Value;

 }
 
 template <class ELFT> void ELFState<ELFT>::buildSectionIndex() {
   for (unsigned I = 0, E = Doc.Sections.size(); I != E; ++I) {
     StringRef Name = Doc.Sections[I]->Name;
     if (Name.empty())
       continue;
 
-    DotShStrtab.add(dropUniqueSuffix(Name));
+    DotShStrtab.add(ELFYAML::dropUniqueSuffix(Name));
     if (!SN2I.addName(Name, I))
       reportError("repeated section name: '" + Name +
                   "' at YAML section number " + Twine(I));
   }
 
   DotShStrtab.finalize();
 }
 
 template <class ELFT> void ELFState<ELFT>::buildSymbolIndexes() {
   auto Build = [this](ArrayRef<ELFYAML::Symbol> V, NameToIdxMap &Map) {
     for (size_t I = 0, S = V.size(); I < S; ++I) {
       const ELFYAML::Symbol &Sym = V[I];
       if (!Sym.Name.empty() && !Map.addName(Sym.Name, I + 1))
         reportError("repeated symbol name: '" + Sym.Name + "'");
     }
   };
 
   Build(Doc.Symbols, SymN2I);
   Build(Doc.DynamicSymbols, DynSymN2I);
 }
 
 template <class ELFT> void ELFState<ELFT>::finalizeStrings() {
   // Add the regular symbol names to .strtab section.
   for (const ELFYAML::Symbol &Sym : Doc.Symbols)
-    DotStrtab.add(dropUniqueSuffix(Sym.Name));
+    DotStrtab.add(ELFYAML::dropUniqueSuffix(Sym.Name));
   DotStrtab.finalize();
 
   // Add the dynamic symbol names to .dynstr section.
   for (const ELFYAML::Symbol &Sym : Doc.DynamicSymbols)
-    DotDynstr.add(dropUniqueSuffix(Sym.Name));
+    DotDynstr.add(ELFYAML::dropUniqueSuffix(Sym.Name));
 
   // SHT_GNU_verdef and SHT_GNU_verneed sections might also
   // add strings to .dynstr section.
   for (const std::unique_ptr<ELFYAML::Section> &Sec : Doc.Sections) {
     if (auto VerNeed = dyn_cast<ELFYAML::VerneedSection>(Sec.get())) {
       for (const ELFYAML::VerneedEntry &VE : VerNeed->VerneedV) {
         DotDynstr.add(VE.File);
         for (const ELFYAML::VernauxEntry &Aux : VE.AuxV)

lib/ObjectYAML/ELFYAML.cpp

case ELF::SHT_SYMTAB_SHNDX:
     if (!IO.outputting())
       Section.reset(new ELFYAML::SymtabShndxSection());
     sectionMapping(IO, *cast<ELFYAML::SymtabShndxSection>(Section.get()));
     break;
   default:
     if (!IO.outputting()) {
       StringRef Name;
       IO.mapOptional("Name", Name, StringRef());
+      Name = ELFYAML::dropUniqueSuffix(Name);
 
       if (ELFYAML::StackSizesSection::nameMatches(Name))
         Section = std::make_unique<ELFYAML::StackSizesSection>();
       else
         Section = std::make_unique<ELFYAML::RawContentSection>();
     }
 
     if (auto S = dyn_cast<ELFYAML::RawContentSection>(Section.get()))

test/tools/yaml2obj/elf-stack-sizes.yaml

 FileHeader:
   Class:   ELFCLASS64
   Data:    ELFDATA2LSB
   Type:    ET_EXEC
   Machine: EM_X86_64
 Sections:
   - Name: .stack_sizes
     Type: SHT_PROGBITS
+
+## Check we can describe .stack_sizes sections using unique suffixes.
+
+# RUN: yaml2obj --docnum=10 %s -o %t10
+# RUN: llvm-readobj --sections --section-data %t10 | FileCheck %s --check-prefix=SUFFIX
+
+# SUFFIX:      Name: .stack_sizes
+# SUFFIX:      SectionData (
+# SUFFIX-NEXT:   0000: 10000000 00000000 20 |
+
+# SUFFIX:      Name: .stack_sizes
+# SUFFIX:      SectionData (
+# SUFFIX-NEXT:   0000: 30000000 00000000 40 |
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_EXEC
+  Machine: EM_X86_64
+Sections:
+  - Name:    '.stack_sizes [1]'
+    Type:    SHT_PROGBITS
+    Entries:
+      - Address: 0x10
+        Size:    0x20
+  - Name:    '.stack_sizes [2]'
+    Type:    SHT_PROGBITS
+    Entries:
+      - Address: 0x30
+        Size:    0x40