From 7824c1d22fcab8a68162634d4293f4a6666ca43e Mon Sep 17 00:00:00 2001 From: Alan Modra Date: Mon, 1 Mar 2021 11:40:51 +1030 Subject: [PATCH] Weak references to __start_/__stop_ symbols If a weak reference to a __start_foo or __stop_foo symbol ends up having no definition due to all the foo sections being removed for some reason, undef_start_stop currently makes the symbol strong undefined. That risks a linker undefined symbol error. Fix that by making the symbol undefweak and also undo some dynamic symbol state. Note that saving the state of the symbol type at the time lang_init_start_stop runs is not sufficient. The linker may have merged in a shared library reference by that point and made what was an undefweak in regular objects, a strong undefined. So it is necessary to look at the ELF symbol flags to decide whether an undefweak is the proper resolution. Something probably should be done for COFF/PE too, but I'm unsure how to do go about that. * ldlang.c (undef_start_stop): For ELF make undefined start/stop symbols undefweak if that was how they were referenced. Undo dynamic state too. --- ld/ChangeLog | 6 ++++++ ld/ldlang.c | 13 +++++++++++++ 2 files changed, 19 insertions(+) diff --git a/ld/ChangeLog b/ld/ChangeLog index 873928608bd..2347f9ae19c 100644 --- a/ld/ChangeLog +++ b/ld/ChangeLog @@ -1,3 +1,9 @@ +2021-03-01 Alan Modra + + * ldlang.c (undef_start_stop): For ELF make undefined start/stop + symbols undefweak if that was how they were referenced. Undo + dynamic state too. + 2021-03-01 Alan Modra * testsuite/ld-elf/pr25708.d: Add --with-symbol-versions to nm. diff --git a/ld/ldlang.c b/ld/ldlang.c index 5ffc8444c77..a77e8fabeff 100644 --- a/ld/ldlang.c +++ b/ld/ldlang.c @@ -6808,6 +6808,19 @@ undef_start_stop (struct bfd_link_hash_entry *h) } h->type = bfd_link_hash_undefined; h->u.undef.abfd = NULL; + if (bfd_get_flavour (link_info.output_bfd) == bfd_target_elf_flavour) + { + const struct elf_backend_data *bed; + struct elf_link_hash_entry *eh = (struct elf_link_hash_entry *) h; + unsigned int was_forced = eh->forced_local; + + bed = get_elf_backend_data (link_info.output_bfd); + (*bed->elf_backend_hide_symbol) (&link_info, eh, TRUE); + if (!eh->ref_regular_nonweak) + h->type = bfd_link_hash_undefweak; + eh->def_regular = 0; + eh->forced_local = was_forced; + } } } -- 2.30.2