X-Git-Url: http://git.efficios.com/?a=blobdiff_plain;f=gold%2Fresolve.cc;h=2dcf7b5b1e8c6431029fe3f53f4b43d41d841bc2;hb=cfe101c6a8227b6b97ed2da85895db7d6083bfa6;hp=408e83becab97842543533d4f0820ac6326093b5;hpb=7198066bc1e788f08e3a3fd1435ea50a610b8999;p=deliverable%2Fbinutils-gdb.git diff --git a/gold/resolve.cc b/gold/resolve.cc index 408e83beca..2dcf7b5b1e 100644 --- a/gold/resolve.cc +++ b/gold/resolve.cc @@ -1,6 +1,6 @@ // resolve.cc -- symbol resolution for gold -// Copyright 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc. +// Copyright (C) 2006-2015 Free Software Foundation, Inc. // Written by Ian Lance Taylor . // This file is part of gold. @@ -96,7 +96,9 @@ Symbol::override_base(const elfcpp::Sym& sym, this->override_version(version); this->u_.from_object.shndx = st_shndx; this->is_ordinary_shndx_ = is_ordinary; - this->type_ = sym.get_st_type(); + // Don't override st_type from plugin placeholder symbols. + if (object->pluginobj() == NULL) + this->type_ = sym.get_st_type(); this->binding_ = sym.get_st_bind(); this->override_visibility(sym.get_st_visibility()); this->nonvis_ = sym.get_st_nonvis(); @@ -171,7 +173,7 @@ static const unsigned int common_flag = 2 << def_undef_or_common_shift; static unsigned int symbol_to_bits(elfcpp::STB binding, bool is_dynamic, - unsigned int shndx, bool is_ordinary, elfcpp::STT type) + unsigned int shndx, bool is_ordinary) { unsigned int bits; @@ -195,7 +197,7 @@ symbol_to_bits(elfcpp::STB binding, bool is_dynamic, default: // Any target which wants to handle STB_LOOS, etc., needs to // define a resolve method. - gold_error(_("unsupported symbol binding")); + gold_error(_("unsupported symbol binding %d"), static_cast(binding)); bits = global_flag; } @@ -216,9 +218,7 @@ symbol_to_bits(elfcpp::STB binding, bool is_dynamic, break; default: - if (type == elfcpp::STT_COMMON) - bits |= common_flag; - else if (!is_ordinary && Symbol::is_common_shndx(shndx)) + if (!is_ordinary && Symbol::is_common_shndx(shndx)) bits |= common_flag; else bits |= def_flag; @@ -243,8 +243,24 @@ Symbol_table::resolve(Sized_symbol* to, const elfcpp::Sym& sym, unsigned int st_shndx, bool is_ordinary, unsigned int orig_st_shndx, - Object* object, const char* version) + Object* object, const char* version, + bool is_default_version) { + // It's possible for a symbol to be defined in an object file + // using .symver to give it a version, and for there to also be + // a linker script giving that symbol the same version. We + // don't want to give a multiple-definition error for this + // harmless redefinition. + bool to_is_ordinary; + if (to->source() == Symbol::FROM_OBJECT + && to->object() == object + && is_ordinary + && to->is_defined() + && to->shndx(&to_is_ordinary) == st_shndx + && to_is_ordinary + && to->value() == sym.get_st_value()) + return; + if (parameters->target().has_resolve()) { Sized_target* sized_target; @@ -255,6 +271,15 @@ Symbol_table::resolve(Sized_symbol* to, if (!object->is_dynamic()) { + if (sym.get_st_type() == elfcpp::STT_COMMON + && (is_ordinary || !Symbol::is_common_shndx(st_shndx))) + { + gold_warning(_("STT_COMMON symbol '%s' in %s " + "is not in a common section"), + to->demangled_name().c_str(), + to->object()->name().c_str()); + return; + } // Record that we've seen this symbol in a regular object. to->set_in_reg(); } @@ -262,15 +287,10 @@ Symbol_table::resolve(Sized_symbol* to, && (to->visibility() == elfcpp::STV_HIDDEN || to->visibility() == elfcpp::STV_INTERNAL)) { - // A dynamic object cannot reference a hidden or internal symbol - // defined in another object. - gold_warning(_("%s symbol '%s' in %s is referenced by DSO %s"), - (to->visibility() == elfcpp::STV_HIDDEN - ? "hidden" - : "internal"), - to->demangled_name().c_str(), - to->object()->name().c_str(), - object->name().c_str()); + // The symbol is hidden, so a reference from a shared object + // cannot bind to it. We tried issuing a warning in this case, + // but that produces false positives when the symbol is + // actually resolved in a different shared object (PR 15574). return; } else @@ -281,40 +301,120 @@ Symbol_table::resolve(Sized_symbol* to, // Record if we've seen this symbol in a real ELF object (i.e., the // symbol is referenced from outside the world known to the plugin). - if (object->pluginobj() == NULL) + if (object->pluginobj() == NULL && !object->is_dynamic()) to->set_in_real_elf(); // If we're processing replacement files, allow new symbols to override // the placeholders from the plugin objects. + // Treat common symbols specially since it is possible that an ELF + // file increased the size of the alignment. if (to->source() == Symbol::FROM_OBJECT) { Pluginobj* obj = to->object()->pluginobj(); if (obj != NULL && parameters->options().plugins()->in_replacement_phase()) { - this->override(to, sym, st_shndx, is_ordinary, object, version); - return; + bool adjust_common = false; + typename Sized_symbol::Size_type tosize = 0; + typename Sized_symbol::Value_type tovalue = 0; + if (to->is_common() + && !is_ordinary && Symbol::is_common_shndx(st_shndx)) + { + adjust_common = true; + tosize = to->symsize(); + tovalue = to->value(); + } + this->override(to, sym, st_shndx, is_ordinary, object, version); + if (adjust_common) + { + if (tosize > to->symsize()) + to->set_symsize(tosize); + if (tovalue > to->value()) + to->set_value(tovalue); + } + return; } } + // A new weak undefined reference, merging with an old weak + // reference, could be a One Definition Rule (ODR) violation -- + // especially if the types or sizes of the references differ. We'll + // store such pairs and look them up later to make sure they + // actually refer to the same lines of code. We also check + // combinations of weak and strong, which might occur if one case is + // inline and the other is not. (Note: not all ODR violations can + // be found this way, and not everything this finds is an ODR + // violation. But it's helpful to warn about.) + if (parameters->options().detect_odr_violations() + && (sym.get_st_bind() == elfcpp::STB_WEAK + || to->binding() == elfcpp::STB_WEAK) + && orig_st_shndx != elfcpp::SHN_UNDEF + && to->shndx(&to_is_ordinary) != elfcpp::SHN_UNDEF + && to_is_ordinary + && sym.get_st_size() != 0 // Ignore weird 0-sized symbols. + && to->symsize() != 0 + && (sym.get_st_type() != to->type() + || sym.get_st_size() != to->symsize()) + // C does not have a concept of ODR, so we only need to do this + // on C++ symbols. These have (mangled) names starting with _Z. + && to->name()[0] == '_' && to->name()[1] == 'Z') + { + Symbol_location fromloc + = { object, orig_st_shndx, static_cast(sym.get_st_value()) }; + Symbol_location toloc = { to->object(), to->shndx(&to_is_ordinary), + static_cast(to->value()) }; + this->candidate_odr_violations_[to->name()].insert(fromloc); + this->candidate_odr_violations_[to->name()].insert(toloc); + } + + // Plugins don't provide a symbol type, so adopt the existing type + // if the FROM symbol is from a plugin. + elfcpp::STT fromtype = (object->pluginobj() != NULL + ? to->type() + : sym.get_st_type()); unsigned int frombits = symbol_to_bits(sym.get_st_bind(), object->is_dynamic(), - st_shndx, is_ordinary, - sym.get_st_type()); + st_shndx, is_ordinary); bool adjust_common_sizes; + bool adjust_dyndef; typename Sized_symbol::Size_type tosize = to->symsize(); - if (Symbol_table::should_override(to, frombits, OBJECT, object, - &adjust_common_sizes)) + if (Symbol_table::should_override(to, frombits, fromtype, OBJECT, + object, &adjust_common_sizes, + &adjust_dyndef, is_default_version)) { + elfcpp::STB tobinding = to->binding(); + typename Sized_symbol::Value_type tovalue = to->value(); this->override(to, sym, st_shndx, is_ordinary, object, version); - if (adjust_common_sizes && tosize > to->symsize()) - to->set_symsize(tosize); + if (adjust_common_sizes) + { + if (tosize > to->symsize()) + to->set_symsize(tosize); + if (tovalue > to->value()) + to->set_value(tovalue); + } + if (adjust_dyndef) + { + // We are overriding an UNDEF or WEAK UNDEF with a DYN DEF. + // Remember which kind of UNDEF it was for future reference. + to->set_undef_binding(tobinding); + } } else { - if (adjust_common_sizes && sym.get_st_size() > tosize) - to->set_symsize(sym.get_st_size()); + if (adjust_common_sizes) + { + if (sym.get_st_size() > tosize) + to->set_symsize(sym.get_st_size()); + if (sym.get_st_value() > to->value()) + to->set_value(sym.get_st_value()); + } + if (adjust_dyndef) + { + // We are keeping a DYN DEF after seeing an UNDEF or WEAK UNDEF. + // Remember which kind of UNDEF it was. + to->set_undef_binding(sym.get_st_bind()); + } // The ELF ABI says that even for a reference to a symbol we // merge the visibility. to->override_visibility(sym.get_st_visibility()); @@ -337,38 +437,6 @@ Symbol_table::resolve(Sized_symbol* to, _("multiple common of '%s'"), to, OBJECT, object); } - - // A new weak undefined reference, merging with an old weak - // reference, could be a One Definition Rule (ODR) violation -- - // especially if the types or sizes of the references differ. We'll - // store such pairs and look them up later to make sure they - // actually refer to the same lines of code. We also check - // combinations of weak and strong, which might occur if one case is - // inline and the other is not. (Note: not all ODR violations can - // be found this way, and not everything this finds is an ODR - // violation. But it's helpful to warn about.) - bool to_is_ordinary; - if (parameters->options().detect_odr_violations() - && (sym.get_st_bind() == elfcpp::STB_WEAK - || to->binding() == elfcpp::STB_WEAK) - && orig_st_shndx != elfcpp::SHN_UNDEF - && to->shndx(&to_is_ordinary) != elfcpp::SHN_UNDEF - && to_is_ordinary - && sym.get_st_size() != 0 // Ignore weird 0-sized symbols. - && to->symsize() != 0 - && (sym.get_st_type() != to->type() - || sym.get_st_size() != to->symsize()) - // C does not have a concept of ODR, so we only need to do this - // on C++ symbols. These have (mangled) names starting with _Z. - && to->name()[0] == '_' && to->name()[1] == 'Z') - { - Symbol_location fromloc - = { object, orig_st_shndx, sym.get_st_value() }; - Symbol_location toloc = { to->object(), to->shndx(&to_is_ordinary), - to->value() }; - this->candidate_odr_violations_[to->name()].insert(fromloc); - this->candidate_odr_violations_[to->name()].insert(toloc); - } } // Handle the core of symbol resolution. This is called with the @@ -380,18 +448,18 @@ Symbol_table::resolve(Sized_symbol* to, bool Symbol_table::should_override(const Symbol* to, unsigned int frombits, - Defined defined, Object* object, - bool* adjust_common_sizes) + elfcpp::STT fromtype, Defined defined, + Object* object, bool* adjust_common_sizes, + bool* adjust_dyndef, bool is_default_version) { *adjust_common_sizes = false; + *adjust_dyndef = false; unsigned int tobits; if (to->source() == Symbol::IS_UNDEFINED) - tobits = symbol_to_bits(to->binding(), false, elfcpp::SHN_UNDEF, true, - to->type()); + tobits = symbol_to_bits(to->binding(), false, elfcpp::SHN_UNDEF, true); else if (to->source() != Symbol::FROM_OBJECT) - tobits = symbol_to_bits(to->binding(), false, elfcpp::SHN_ABS, false, - to->type()); + tobits = symbol_to_bits(to->binding(), false, elfcpp::SHN_ABS, false); else { bool is_ordinary; @@ -399,11 +467,15 @@ Symbol_table::should_override(const Symbol* to, unsigned int frombits, tobits = symbol_to_bits(to->binding(), to->object()->is_dynamic(), shndx, - is_ordinary, - to->type()); + is_ordinary); } - // FIXME: Warn if either but not both of TO and SYM are STT_TLS. + if ((to->type() == elfcpp::STT_TLS) ^ (fromtype == elfcpp::STT_TLS) + && !to->is_placeholder()) + Symbol_table::report_resolve_problem(true, + _("symbol '%s' used as both __thread " + "and non-__thread"), + to, defined, object); // We use a giant switch table for symbol resolution. This code is // unwieldy, but: 1) it is efficient; 2) we definitely handle all @@ -525,18 +597,33 @@ Symbol_table::should_override(const Symbol* to, unsigned int frombits, case DEF * 16 + DYN_DEF: case WEAK_DEF * 16 + DYN_DEF: + // Ignore a dynamic definition if we already have a definition. + return false; + case DYN_DEF * 16 + DYN_DEF: case DYN_WEAK_DEF * 16 + DYN_DEF: - // Ignore a dynamic definition if we already have a definition. + // Ignore a dynamic definition if we already have a definition, + // unless the existing definition is an unversioned definition + // in the same dynamic object, and the new definition is a + // default version. + if (to->object() == object + && to->version() == NULL + && is_default_version) + return true; return false; case UNDEF * 16 + DYN_DEF: - case WEAK_UNDEF * 16 + DYN_DEF: case DYN_UNDEF * 16 + DYN_DEF: case DYN_WEAK_UNDEF * 16 + DYN_DEF: // Use a dynamic definition if we have a reference. return true; + case WEAK_UNDEF * 16 + DYN_DEF: + // When overriding a weak undef by a dynamic definition, + // we need to remember that the original undef was weak. + *adjust_dyndef = true; + return true; + case COMMON * 16 + DYN_DEF: case WEAK_COMMON * 16 + DYN_DEF: case DYN_COMMON * 16 + DYN_DEF: @@ -554,12 +641,22 @@ Symbol_table::should_override(const Symbol* to, unsigned int frombits, return false; case UNDEF * 16 + DYN_WEAK_DEF: - case WEAK_UNDEF * 16 + DYN_WEAK_DEF: + // When overriding an undef by a dynamic weak definition, + // we need to remember that the original undef was not weak. + *adjust_dyndef = true; + return true; + case DYN_UNDEF * 16 + DYN_WEAK_DEF: case DYN_WEAK_UNDEF * 16 + DYN_WEAK_DEF: // Use a weak dynamic definition if we have a reference. return true; + case WEAK_UNDEF * 16 + DYN_WEAK_DEF: + // When overriding a weak undef by a dynamic definition, + // we need to remember that the original undef was weak. + *adjust_dyndef = true; + return true; + case COMMON * 16 + DYN_WEAK_DEF: case WEAK_COMMON * 16 + DYN_WEAK_DEF: case DYN_COMMON * 16 + DYN_WEAK_DEF: @@ -570,12 +667,16 @@ Symbol_table::should_override(const Symbol* to, unsigned int frombits, case DEF * 16 + UNDEF: case WEAK_DEF * 16 + UNDEF: - case DYN_DEF * 16 + UNDEF: - case DYN_WEAK_DEF * 16 + UNDEF: case UNDEF * 16 + UNDEF: // A new undefined reference tells us nothing. return false; + case DYN_DEF * 16 + UNDEF: + case DYN_WEAK_DEF * 16 + UNDEF: + // For a dynamic def, we need to remember which kind of undef we see. + *adjust_dyndef = true; + return false; + case WEAK_UNDEF * 16 + UNDEF: case DYN_UNDEF * 16 + UNDEF: case DYN_WEAK_UNDEF * 16 + UNDEF: @@ -591,17 +692,28 @@ Symbol_table::should_override(const Symbol* to, unsigned int frombits, case DEF * 16 + WEAK_UNDEF: case WEAK_DEF * 16 + WEAK_UNDEF: - case DYN_DEF * 16 + WEAK_UNDEF: - case DYN_WEAK_DEF * 16 + WEAK_UNDEF: case UNDEF * 16 + WEAK_UNDEF: case WEAK_UNDEF * 16 + WEAK_UNDEF: case DYN_UNDEF * 16 + WEAK_UNDEF: - case DYN_WEAK_UNDEF * 16 + WEAK_UNDEF: case COMMON * 16 + WEAK_UNDEF: case WEAK_COMMON * 16 + WEAK_UNDEF: case DYN_COMMON * 16 + WEAK_UNDEF: case DYN_WEAK_COMMON * 16 + WEAK_UNDEF: - // A new weak undefined reference tells us nothing. + // A new weak undefined reference tells us nothing unless the + // exisiting symbol is a dynamic weak reference. + return false; + + case DYN_WEAK_UNDEF * 16 + WEAK_UNDEF: + // A new weak reference overrides an existing dynamic weak reference. + // This is necessary because a dynamic weak reference remembers + // the old binding, which may not be weak. If we keeps the existing + // dynamic weak reference, the weakness may be dropped in the output. + return true; + + case DYN_DEF * 16 + WEAK_UNDEF: + case DYN_WEAK_DEF * 16 + WEAK_UNDEF: + // For a dynamic def, we need to remember which kind of undef we see. + *adjust_dyndef = true; return false; case DEF * 16 + DYN_UNDEF: @@ -783,6 +895,7 @@ Symbol_table::report_resolve_problem(bool is_error, const char* msg, objname = _("linker script"); break; case PREDEFINED: + case INCREMENTAL_BASE: objname = _("linker defined"); break; default: @@ -808,13 +921,17 @@ Symbol_table::report_resolve_problem(bool is_error, const char* msg, // defining special symbols. bool -Symbol_table::should_override_with_special(const Symbol* to, Defined defined) +Symbol_table::should_override_with_special(const Symbol* to, + elfcpp::STT fromtype, + Defined defined) { bool adjust_common_sizes; + bool adjust_dyn_def; unsigned int frombits = global_flag | regular_flag | def_flag; - bool ret = Symbol_table::should_override(to, frombits, defined, NULL, - &adjust_common_sizes); - gold_assert(!adjust_common_sizes); + bool ret = Symbol_table::should_override(to, frombits, fromtype, defined, + NULL, &adjust_common_sizes, + &adjust_dyn_def, false); + gold_assert(!adjust_common_sizes && !adjust_dyn_def); return ret; } @@ -823,7 +940,12 @@ Symbol_table::should_override_with_special(const Symbol* to, Defined defined) void Symbol::override_base_with_special(const Symbol* from) { - gold_assert(this->name_ == from->name_ || this->has_alias()); + bool same_name = this->name_ == from->name_; + gold_assert(same_name || this->has_alias()); + + // If we are overriding an undef, remember the original binding. + if (this->is_undefined()) + this->set_undef_binding(this->binding_); this->source_ = from->source_; switch (from->source_) @@ -845,7 +967,16 @@ Symbol::override_base_with_special(const Symbol* from) break; } - this->override_version(from->version_); + if (same_name) + { + // When overriding a versioned symbol with a special symbol, we + // may be changing the version. This will happen if we see a + // special symbol such as "_end" defined in a shared object with + // one version (from a version script), but we want to define it + // here with a different version (from a different version + // script). + this->version_ = from->version_; + } this->type_ = from->type_; this->binding_ = from->binding_; this->override_visibility(from->visibility_); @@ -859,6 +990,8 @@ Symbol::override_base_with_special(const Symbol* from) if (from->needs_dynsym_value_) this->needs_dynsym_value_ = true; + this->is_predefined_ = from->is_predefined_; + // We shouldn't see these flags. If we do, we need to handle them // somehow. gold_assert(!from->is_forwarder_); @@ -916,7 +1049,10 @@ Symbol_table::override_with_special(Sized_symbol* tosym, // script to restrict this to only the ones needed for implemented // targets. -#ifdef HAVE_TARGET_32_LITTLE +// We have to instantiate both big and little endian versions because +// these are used by other templates that depends on size only. + +#if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG) template void Symbol_table::resolve<32, false>( @@ -926,10 +1062,9 @@ Symbol_table::resolve<32, false>( bool is_ordinary, unsigned int orig_st_shndx, Object* object, - const char* version); -#endif + const char* version, + bool is_default_version); -#ifdef HAVE_TARGET_32_BIG template void Symbol_table::resolve<32, true>( @@ -939,10 +1074,11 @@ Symbol_table::resolve<32, true>( bool is_ordinary, unsigned int orig_st_shndx, Object* object, - const char* version); + const char* version, + bool is_default_version); #endif -#ifdef HAVE_TARGET_64_LITTLE +#if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG) template void Symbol_table::resolve<64, false>( @@ -952,10 +1088,9 @@ Symbol_table::resolve<64, false>( bool is_ordinary, unsigned int orig_st_shndx, Object* object, - const char* version); -#endif + const char* version, + bool is_default_version); -#ifdef HAVE_TARGET_64_BIG template void Symbol_table::resolve<64, true>( @@ -965,7 +1100,8 @@ Symbol_table::resolve<64, true>( bool is_ordinary, unsigned int orig_st_shndx, Object* object, - const char* version); + const char* version, + bool is_default_version); #endif #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)