[llvm-objdump]Correct .dynstr finding of getDynamicStrTab()

[cabbaken]

The dynamic string table used by the dynamic section is referenced by the sh_link field of that section, so we should use that directly, rather than going via the dynamic symbol table.
More info: #125679 (comment)

[llvmbot]

@llvm/pr-subscribers-llvm-binary-utilities

Author: Ruoyu Qiu (cabbaken)

Changes

More info: #125679 (comment)

---

Full diff: https://github.com/llvm/llvm-project/pull/127975.diff

2 Files Affected:

• (modified) llvm/test/tools/llvm-objdump/ELF/private-headers.test (+1)
• (modified) llvm/tools/llvm-objdump/ELFDump.cpp (+2-2)

diff --git a/llvm/test/tools/llvm-objdump/ELF/private-headers.test b/llvm/test/tools/llvm-objdump/ELF/private-headers.test
index eefdc8440385c..c90cf59f4ed7d 100644
--- a/llvm/test/tools/llvm-objdump/ELF/private-headers.test
+++ b/llvm/test/tools/llvm-objdump/ELF/private-headers.test
@@ -30,6 +30,7 @@ Sections:
   - Name:    .dynamic
     Type:    SHT_DYNAMIC
     Flags:   [ SHF_ALLOC ]
+    Link:    1
     Entries:
      - Tag:   DT_NEEDED
        Value: 0x1
diff --git a/llvm/tools/llvm-objdump/ELFDump.cpp b/llvm/tools/llvm-objdump/ELFDump.cpp
index e9e5b059f1786..bce308c870ddf 100644
--- a/llvm/tools/llvm-objdump/ELFDump.cpp
+++ b/llvm/tools/llvm-objdump/ELFDump.cpp
@@ -78,8 +78,8 @@ static Expected<StringRef> getDynamicStrTab(const ELFFile<ELFT> &Elf) {
     return SectionsOrError.takeError();
 
   for (const typename ELFT::Shdr &Sec : *SectionsOrError) {
-    if (Sec.sh_type == ELF::SHT_DYNSYM)
-      return Elf.getStringTableForSymtab(Sec);
+    if (Sec.sh_type == ELF::SHT_DYNAMIC)
+      return Elf.getLinkAsStrtab(Sec);
   }
 
   return createError("dynamic string table not found");

[jh7370]

LGTM too. Do you need assistance with merging it?

I'd be tempted to update the PR description to avoid people needing to click links to get the context. Something along the lines of "the dynamic string table used by the dynamic section is referenced by the sh_link field of that section, so we should use that directly, rather than going via the dynamic symbol table." Also, I'd add [llvm-objdump] to the PR title.

[cabbaken]

LGTM too. Do you need assistance with merging it?

I'd be tempted to update the PR description to avoid people needing to click links to get the context. Something along the lines of "the dynamic string table used by the dynamic section is referenced by the sh_link field of that section, so we should use that directly, rather than going via the dynamic symbol table." Also, I'd add [llvm-objdump] to the PR title.

Yes.
ok, I will modify PR title and description.

[jh7370]

Okay, merged. Please keep an eye out for any build bot failures (I wouldn't expect any related to the change, but that's not a guarantee).