diff options
| author | Fangrui Song <i@maskray.me> | 2025-11-22 12:54:50 -0800 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2025-11-22 20:54:50 +0000 |
| commit | d96a93ff00ac02bc523d36dd2e687d597a068ae1 (patch) | |
| tree | 6f8061f964b40218b645f2c70479c357693557c0 /lld/ELF/InputFiles.cpp | |
| parent | 080ca902c6aaf1a1bf48df04a65ed163825b2006 (diff) | |
ELF: Use index 0 for unversioned undefined symbols (#168189)
The GNU documentation is ambiguous about the version index for
unversioned undefined symbols. The current specification at
https://sourceware.org/gnu-gabi/program-loading-and-dynamic-linking.txt
defines VER_NDX_LOCAL (0) as "The symbol is private, and is not
available outside this object."
However, this naming is misleading for undefined symbols. As suggested
in
discussions, VER_NDX_LOCAL should conceptually be VER_NDX_NONE and apply
to unversioned undefined symbols as well.
GNU ld has used index 0 for unversioned undefined symbols both before
version 2.35 (see https://sourceware.org/PR26002) and in the upcoming
2.46 release (see https://sourceware.org/PR33577). This change aligns
with GNU ld's behavior by switching from index 1 to index 0.
While here, add a test to dso-undef-extract-lazy.s that undefined
symbols of index 0 in DSO are treated as unversioned symbols.
Diffstat (limited to 'lld/ELF/InputFiles.cpp')
| -rw-r--r-- | lld/ELF/InputFiles.cpp | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/lld/ELF/InputFiles.cpp b/lld/ELF/InputFiles.cpp index a5921feb1829..240a6d0cd4b2 100644 --- a/lld/ELF/InputFiles.cpp +++ b/lld/ELF/InputFiles.cpp @@ -1676,8 +1676,9 @@ template <class ELFT> void SharedFile::parse() { const uint16_t ver = versyms[i], idx = ver & ~VERSYM_HIDDEN; if (sym.isUndefined()) { - // For unversioned undefined symbols, VER_NDX_GLOBAL makes more sense but - // as of binutils 2.34, GNU ld produces VER_NDX_LOCAL. + // Index 0 (VER_NDX_LOCAL) is used for unversioned undefined symbols. + // GNU ld versions between 2.35 and 2.45 also generate VER_NDX_GLOBAL + // for this case (https://sourceware.org/PR33577). if (ver != VER_NDX_LOCAL && ver != VER_NDX_GLOBAL) { if (idx >= verneeds.size()) { ErrAlways(ctx) << "corrupt input file: version need index " << idx |