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| author | Florian Weimer <fweimer@redhat.com> | 2021-03-25 11:05:37 +0100 |
|---|---|---|
| committer | Florian Weimer <fweimer@redhat.com> | 2021-03-25 12:33:02 +0100 |
| commit | 0923f74adaa2827264a0d7cbe51ba287fc0f0c16 (patch) | |
| tree | 06778dcf88a5b0ac149f3c23d5cb85de4a2f78b7 /configure.ac | |
| parent | 6d8fcee694b9581630a7f27fcbf0009fc44d7baa (diff) | |
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Support for multiple versions in versioned_symbol, compat_symbol
This essentially folds compat_symbol_unique functionality into
compat_symbol.
This change eliminates the need for intermediate aliases for defining
multiple symbol versions, for both compat_symbol and versioned_symbol.
Some binutils versions do not suport multiple versions per symbol on
some targets, so aliases are automatically introduced, similar to what
compat_symbol_unique did. To reduce symbol table sizes, a configure
check is added to avoid these aliases if they are not needed.
The new mechanism works with data symbols as well as function symbols,
due to the way an assembler-level redirect is used. It is not
compatible with weak symbols for old binutils versions, which is why
the definition of __malloc_initialize_hook had to be changed. This
is not a loss of functionality because weak symbols do not matter
to dynamic linking.
The placeholder symbol needs repeating in nptl/libpthread-compat.c
now that compat_symbol is used, but that seems more obvious than
introducing yet another macro.
A subtle difference was that compat_symbol_unique made the symbol
global automatically. compat_symbol does not do this, so static
had to be removed from the definition of
__libpthread_version_placeholder.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Diffstat (limited to 'configure.ac')
| -rw-r--r-- | configure.ac | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/configure.ac b/configure.ac index 6a3a9ab620..fce967f2c2 100644 --- a/configure.ac +++ b/configure.ac @@ -1673,6 +1673,29 @@ elif test "$libc_cv_ehdr_start" = broken; then AC_MSG_WARN([linker is broken -- you should upgrade]) fi +dnl Starting with binutils 2.35, GAS can attach multiple symbol versions +dnl to one symbol (PR 23840). +AC_CACHE_CHECK(whether the assembler requires one version per symbol, + libc_cv_symver_needs_alias, [dnl + cat > conftest.s <<EOF + .text +testfunc: + .globl testfunc + .symver testfunc, testfunc1@VERSION1 + .symver testfunc, testfunc1@VERSION2 +EOF + libc_cv_symver_needs_alias=no + if ${CC-cc} $ASFLAGS -c conftest.s 2>&AS_MESSAGE_LOG_FD; then + libc_cv_symver_needs_alias=no + else + libc_cv_symver_needs_alias=yes + fi + rm conftest.* +]) +if test "$libc_cv_symver_needs_alias" = yes; then + AC_DEFINE(SYMVER_NEEDS_ALIAS) +fi + AC_CACHE_CHECK(for __builtin_trap with no external dependencies, libc_cv_builtin_trap, [dnl libc_cv_builtin_trap=no |