PR26978, Inconsistency for strong foo@v1 and weak foo@@v1
Prior to this patch ld -shared --version-script=pr26979.ver pr26978a.o pr26978b.o results in ld: pr26978b.o: in function `foo_v1': (.text+0x0): multiple definition of `foo@v1' ld: pr26978b.o:(*IND*+0x0): multiple definition of `foo' while ld -shared --version-script=pr26979.ver pr26978b.o pr26978a.o results in no error, but some odd dynamic symbols. ... 0 NOTYPE GLOBAL DEFAULT 7 foo@v1 ... 0 NOTYPE WEAK DEFAULT 7 foo@@v1 When linking an undecorated reference to foo against such a shared library, ld complains about multiple definitions of foo@v1 while gold creates a dynamic reference to foo@v1. That results in foo@v1 being used at runtime. While we could error in both cases, it is reasonable to say foo@v1 and foo@@v1 are in fact the same symbol. (Same name, same version. The only real difference is that foo@@v1 satisfies a reference to plain foo, while foo@v1 does not.) Just as merging a weak undecorated sym with a strong sym results in the strong sym prevailing, so should the strong foo@v1 prevail. And since there is a definition that satisfies plain foo, the foo@@v1 variety of dynamic symbol should be emitted at the foo@v1 value. That makes the testcase that currently links continue to produce a shared library, and that shared library can now be used by both ld and gold with the same runtime behaviour as when using gold with the odd dynamic symbol library. bfd/ PR 26978 * elflink.c (_bfd_elf_add_default_symbol): Handle the case where a new weak sym@@ver should be overridden by an existing sym@ver. (elf_link_add_object_symbols): Don't _bfd_elf_add_default_symbol for a new weak sym@ver when sym@@ver already exists. * linker.c (link_action): Choose MIND for previous indirect, current def, rather than MDEF. (_bfd_generic_link_add_one_symbol <MIND>): Handle redefinition of weak indirect symbol. ld/ * testsuite/ld-elf/pr26978a.d, * testsuite/ld-elf/pr26978a.s, * testsuite/ld-elf/pr26978b.d, * testsuite/ld-elf/pr26978b.s: New tests.
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Alan Modra
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099ee20ac3
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726d7d1ecf
@ -1,3 +1,15 @@
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2020-12-04 Alan Modra <amodra@gmail.com>
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PR 26978
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* elflink.c (_bfd_elf_add_default_symbol): Handle the case where
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a new weak sym@@ver should be overridden by an existing sym@ver.
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(elf_link_add_object_symbols): Don't _bfd_elf_add_default_symbol
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for a new weak sym@ver when sym@@ver already exists.
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* linker.c (link_action): Choose MIND for previous indirect,
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current def, rather than MDEF.
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(_bfd_generic_link_add_one_symbol <MIND>): Handle redefinition of
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weak indirect symbol.
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2020-12-01 Nelson Chu <nelson.chu@sifive.com>
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* elfxx-riscv.c (riscv_parse_prefixed_ext): Use riscv_compare_subsets
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@ -2078,9 +2078,26 @@ _bfd_elf_add_default_symbol (bfd *abfd,
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return FALSE;
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if (skip)
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return TRUE;
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if (override)
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{
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if (!dynamic
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&& h->root.type == bfd_link_hash_defweak
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&& hi->root.type == bfd_link_hash_defined)
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{
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/* We are handling a weak sym@@ver and attempting to define
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a weak sym@ver, but _bfd_elf_merge_symbol said to skip the
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new weak sym@ver because there is already a strong sym@ver.
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However, sym@ver and sym@@ver are really the same symbol.
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The existing strong sym@ver ought to override sym@@ver. */
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h->root.type = bfd_link_hash_defined;
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h->root.u.def.section = hi->root.u.def.section;
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h->root.u.def.value = hi->root.u.def.value;
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hi->root.type = bfd_link_hash_indirect;
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hi->root.u.i.link = &h->root;
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}
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else
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return TRUE;
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}
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else if (override)
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{
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/* Here SHORTNAME is a versioned name, so we don't expect to see
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the type of override we do in the case above unless it is
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@ -2091,6 +2108,7 @@ _bfd_elf_add_default_symbol (bfd *abfd,
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/* xgettext:c-format */
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(_("%pB: unexpected redefinition of indirect versioned symbol `%s'"),
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abfd, shortname);
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return TRUE;
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}
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else
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{
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@ -2100,37 +2118,36 @@ _bfd_elf_add_default_symbol (bfd *abfd,
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bfd_ind_section_ptr, 0, name, FALSE, collect, &bh)))
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return FALSE;
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hi = (struct elf_link_hash_entry *) bh;
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}
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/* If there is a duplicate definition somewhere, then HI may not
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point to an indirect symbol. We will have reported an error
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to the user in that case. */
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/* If there is a duplicate definition somewhere, then HI may not
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point to an indirect symbol. We will have reported an error
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to the user in that case. */
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if (hi->root.type == bfd_link_hash_indirect)
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{
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(*bed->elf_backend_copy_indirect_symbol) (info, h, hi);
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h->ref_dynamic_nonweak |= hi->ref_dynamic_nonweak;
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hi->dynamic_def |= h->dynamic_def;
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if (hi->root.type == bfd_link_hash_indirect)
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/* If we first saw a reference to @VER symbol with
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non-default visibility, merge that visibility to the
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@@VER symbol. */
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elf_merge_st_other (abfd, h, hi->other, sec, TRUE, dynamic);
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/* See if the new flags lead us to realize that the symbol
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must be dynamic. */
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if (! *dynsym)
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{
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(*bed->elf_backend_copy_indirect_symbol) (info, h, hi);
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h->ref_dynamic_nonweak |= hi->ref_dynamic_nonweak;
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hi->dynamic_def |= h->dynamic_def;
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/* If we first saw a reference to @VER symbol with
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non-default visibility, merge that visibility to the
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@@VER symbol. */
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elf_merge_st_other (abfd, h, hi->other, sec, TRUE, dynamic);
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/* See if the new flags lead us to realize that the symbol
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must be dynamic. */
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if (! *dynsym)
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if (! dynamic)
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{
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if (! dynamic)
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{
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if (! bfd_link_executable (info)
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|| hi->ref_dynamic)
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*dynsym = TRUE;
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}
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else
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{
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if (hi->ref_regular)
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*dynsym = TRUE;
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}
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if (! bfd_link_executable (info)
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|| hi->ref_dynamic)
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*dynsym = TRUE;
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}
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else
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{
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if (hi->ref_regular)
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*dynsym = TRUE;
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}
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}
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}
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@ -5060,8 +5077,10 @@ elf_link_add_object_symbols (bfd *abfd, struct bfd_link_info *info)
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/* Check to see if we need to add an indirect symbol for
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the default name. */
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if (definition
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|| (!override && h->root.type == bfd_link_hash_common))
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if ((definition
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|| (!override && h->root.type == bfd_link_hash_common))
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&& !(hi != h
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&& hi->versioned == versioned_hidden))
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if (!_bfd_elf_add_default_symbol (abfd, info, h, name, isym,
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sec, value, &old_bfd, &dynsym))
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goto error_free_vers;
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13
bfd/linker.c
13
bfd/linker.c
@ -1301,7 +1301,7 @@ static const enum link_action link_action[8][8] =
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/* current\prev new undef undefw def defw com indr warn */
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/* UNDEF_ROW */ {UND, NOACT, UND, REF, REF, NOACT, REFC, WARNC },
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/* UNDEFW_ROW */ {WEAK, NOACT, NOACT, REF, REF, NOACT, REFC, WARNC },
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/* DEF_ROW */ {DEF, DEF, DEF, MDEF, DEF, CDEF, MDEF, CYCLE },
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/* DEF_ROW */ {DEF, DEF, DEF, MDEF, DEF, CDEF, MIND, CYCLE },
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/* DEFW_ROW */ {DEFW, DEFW, DEFW, NOACT, NOACT, NOACT, NOACT, CYCLE },
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/* COMMON_ROW */ {COM, COM, COM, CREF, COM, BIG, REFC, WARNC },
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/* INDR_ROW */ {IND, IND, IND, MDEF, IND, CIND, MIND, CYCLE },
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@ -1672,6 +1672,17 @@ _bfd_generic_link_add_one_symbol (struct bfd_link_info *info,
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case MIND:
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/* Multiple indirect symbols. This is OK if they both point
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to the same symbol. */
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if (h->u.i.link->type == bfd_link_hash_defweak)
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{
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/* It is also OK to redefine a symbol that indirects to
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a weak definition. So for sym@ver -> sym@@ver where
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sym@@ver is weak and we have a new strong sym@ver,
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redefine sym@@ver. Of course if there exists
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sym -> sym@@ver then this also redefines sym. */
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h = h->u.i.link;
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cycle = TRUE;
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break;
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}
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if (strcmp (h->u.i.link->root.string, string) == 0)
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break;
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/* Fall through. */
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@ -1,3 +1,10 @@
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2020-12-04 Alan Modra <amodra@gmail.com>
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* testsuite/ld-elf/pr26978a.d,
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* testsuite/ld-elf/pr26978a.s,
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* testsuite/ld-elf/pr26978b.d,
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* testsuite/ld-elf/pr26978b.s: New tests.
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2020-12-03 Andreas Krebbel <krebbel@linux.ibm.com>
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* testsuite/ld-s390/tlsbin_64.dd: The newly added jgnop mnemonic
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11
ld/testsuite/ld-elf/pr26978a.d
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11
ld/testsuite/ld-elf/pr26978a.d
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@ -0,0 +1,11 @@
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#source: pr26978a.s
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#source: pr26978b.s
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#target: [check_shared_lib_support]
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#as:
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#ld: -shared --version-script=pr26979.ver
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#readelf: -sW
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#failif
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#...
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.*foo@v1
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#pass
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4
ld/testsuite/ld-elf/pr26978a.s
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4
ld/testsuite/ld-elf/pr26978a.s
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@ -0,0 +1,4 @@
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.weak foo
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.symver foo, foo@@@v1
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foo:
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.octa 0
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11
ld/testsuite/ld-elf/pr26978b.d
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11
ld/testsuite/ld-elf/pr26978b.d
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@ -0,0 +1,11 @@
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#source: pr26978b.s
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#source: pr26978a.s
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#target: [check_shared_lib_support]
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#as:
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#ld: -shared --version-script=pr26979.ver
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#readelf: -sW
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#failif
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#...
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.*foo@v1
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#pass
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4
ld/testsuite/ld-elf/pr26978b.s
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4
ld/testsuite/ld-elf/pr26978b.s
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.globl foo_v1
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.symver foo_v1, foo@v1
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foo_v1:
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.octa 0
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