From a896df97b952d4f3feed8068eaa70147d12e0e28 Mon Sep 17 00:00:00 2001 From: Alan Modra Date: Fri, 31 Jul 2020 16:37:17 +0930 Subject: [PATCH] PR26314, Linking LTO objects with symbols from static and shared libraries gcc -O2 -g -o ar -Wl,--as-needed arparse.o arlex.o ar.o not-ranlib.o arsup.o rename.o binemul.o emul_vanilla.o bucomm.o version.o filemode.o libbfd-2.35-3.fc33.so libiberty.a -Wl,-R,. All of the above .o files are lto, leading to libbfd-2.35-3.fc33.so not being found needed when loading the IR objects. That's problem number one: We exclude IR references when deciding a shared library is needed. See PR15146. Thus none of the libbfd.so symbols are loaded before libiberty.a is scanned, and libbfd.so contains copies of libiberty.a functions. We ought to be using the libbfd.so copies rather than extracting them from the archive (an object is extracted even to satisfy IR symbols). After lto recompilation, libbfd.so is of course found to be needed and loaded. But that causes more problems. The lto recompilation didn't see symbol references from libbfd.so and variables like _xexit_cleanup are made local in the recompiled objects. Oops, two copies of them. Finally, those silly undefined symbols in the lto output debug files, combined with definitions in both libbfd.so and IR objects result in IR symbols being made dynamic. The main fix here is to revert the PR15146 change to elf_link_add_object_symbols. PR 26314 * elflink.c (bfd_elf_link_record_dynamic_symbol): Don't allow IR symbols to become dynamic. (elf_link_add_object_symbols): Don't exclude IR symbols when deciding whether an as-needed shared library is needed. --- bfd/ChangeLog | 8 ++++++++ bfd/elflink.c | 16 +++++++++++----- 2 files changed, 19 insertions(+), 5 deletions(-) diff --git a/bfd/ChangeLog b/bfd/ChangeLog index e507a9d6c0..d0a5916d37 100644 --- a/bfd/ChangeLog +++ b/bfd/ChangeLog @@ -1,3 +1,11 @@ +2020-07-31 Alan Modra + + PR 26314 + * elflink.c (bfd_elf_link_record_dynamic_symbol): Don't allow + IR symbols to become dynamic. + (elf_link_add_object_symbols): Don't exclude IR symbols when + deciding whether an as-needed shared library is needed. + 2020-07-30 Szabolcs Nagy PR ld/26312 diff --git a/bfd/elflink.c b/bfd/elflink.c index ae5ff50ed6..0a7f5bb152 100644 --- a/bfd/elflink.c +++ b/bfd/elflink.c @@ -505,6 +505,16 @@ bfd_elf_link_record_dynamic_symbol (struct bfd_link_info *info, const char *name; size_t indx; + if (h->root.type == bfd_link_hash_defined + || h->root.type == bfd_link_hash_defweak) + { + /* An IR symbol should not be made dynamic. */ + if (h->root.u.def.section != NULL + && h->root.u.def.section->owner != NULL + && (h->root.u.def.section->owner->flags & BFD_PLUGIN) != 0) + return TRUE; + } + /* XXX: The ABI draft says the linker must turn hidden and internal symbols into STB_LOCAL symbols when producing the DSO. However, if ld.so honors st_other in the dynamic table, @@ -5199,15 +5209,11 @@ elf_link_add_object_symbols (bfd *abfd, struct bfd_link_info *info) break; } - /* Don't add DT_NEEDED for references from the dummy bfd nor - for unmatched symbol. */ if (!add_needed && matched && definition && ((dynsym - && h->ref_regular_nonweak - && (old_bfd == NULL - || (old_bfd->flags & BFD_PLUGIN) == 0)) + && h->ref_regular_nonweak) || (h->ref_dynamic_nonweak && (elf_dyn_lib_class (abfd) & DYN_AS_NEEDED) != 0 && !on_needed_list (elf_dt_name (abfd), -- 2.34.1