// resolve.cc -- symbol resolution for gold
-// Copyright 2006, 2007 Free Software Foundation, Inc.
+// Copyright 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.
// This file is part of gold.
#include "target.h"
#include "object.h"
#include "symtab.h"
+#include "plugin.h"
namespace gold
{
// Symbol methods used in this file.
+// This symbol is being overridden by another symbol whose version is
+// VERSION. Update the VERSION_ field accordingly.
+
+inline void
+Symbol::override_version(const char* version)
+{
+ if (version == NULL)
+ {
+ // This is the case where this symbol is NAME/VERSION, and the
+ // version was not marked as hidden. That makes it the default
+ // version, so we create NAME/NULL. Later we see another symbol
+ // NAME/NULL, and that symbol is overriding this one. In this
+ // case, since NAME/VERSION is the default, we make NAME/NULL
+ // override NAME/VERSION as well. They are already the same
+ // Symbol structure. Setting the VERSION_ field to NULL ensures
+ // that it will be output with the correct, empty, version.
+ this->version_ = version;
+ }
+ else
+ {
+ // This is the case where this symbol is NAME/VERSION_ONE, and
+ // now we see NAME/VERSION_TWO, and NAME/VERSION_TWO is
+ // overriding NAME. If VERSION_ONE and VERSION_TWO are
+ // different, then this can only happen when VERSION_ONE is NULL
+ // and VERSION_TWO is not hidden.
+ gold_assert(this->version_ == version || this->version_ == NULL);
+ this->version_ = version;
+ }
+}
+
+// This symbol is being overidden by another symbol whose visibility
+// is VISIBILITY. Updated the VISIBILITY_ field accordingly.
+
+inline void
+Symbol::override_visibility(elfcpp::STV visibility)
+{
+ // The rule for combining visibility is that we always choose the
+ // most constrained visibility. In order of increasing constraint,
+ // visibility goes PROTECTED, HIDDEN, INTERNAL. This is the reverse
+ // of the numeric values, so the effect is that we always want the
+ // smallest non-zero value.
+ if (visibility != elfcpp::STV_DEFAULT)
+ {
+ if (this->visibility_ == elfcpp::STV_DEFAULT)
+ this->visibility_ = visibility;
+ else if (this->visibility_ > visibility)
+ this->visibility_ = visibility;
+ }
+}
+
// Override the fields in Symbol.
template<int size, bool big_endian>
void
Symbol::override_base(const elfcpp::Sym<size, big_endian>& sym,
+ unsigned int st_shndx, bool is_ordinary,
Object* object, const char* version)
{
gold_assert(this->source_ == FROM_OBJECT);
this->u_.from_object.object = object;
- if (version != NULL && this->version() != version)
- {
- gold_assert(this->version() == NULL);
- this->version_ = version;
- }
- // FIXME: Handle SHN_XINDEX.
- this->u_.from_object.shndx = sym.get_st_shndx();
+ this->override_version(version);
+ this->u_.from_object.shndx = st_shndx;
+ this->is_ordinary_shndx_ = is_ordinary;
this->type_ = sym.get_st_type();
this->binding_ = sym.get_st_bind();
- this->visibility_ = sym.get_st_visibility();
+ this->override_visibility(sym.get_st_visibility());
this->nonvis_ = sym.get_st_nonvis();
if (object->is_dynamic())
this->in_dyn_ = true;
template<bool big_endian>
void
Sized_symbol<size>::override(const elfcpp::Sym<size, big_endian>& sym,
+ unsigned st_shndx, bool is_ordinary,
Object* object, const char* version)
{
- this->override_base(sym, object, version);
+ this->override_base(sym, st_shndx, is_ordinary, object, version);
this->value_ = sym.get_st_value();
this->symsize_ = sym.get_st_size();
}
+// Override TOSYM with symbol FROMSYM, defined in OBJECT, with version
+// VERSION. This handles all aliases of TOSYM.
+
+template<int size, bool big_endian>
+void
+Symbol_table::override(Sized_symbol<size>* tosym,
+ const elfcpp::Sym<size, big_endian>& fromsym,
+ unsigned int st_shndx, bool is_ordinary,
+ Object* object, const char* version)
+{
+ tosym->override(fromsym, st_shndx, is_ordinary, object, version);
+ if (tosym->has_alias())
+ {
+ Symbol* sym = this->weak_aliases_[tosym];
+ gold_assert(sym != NULL);
+ Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym);
+ do
+ {
+ ssym->override(fromsym, st_shndx, is_ordinary, object, version);
+ sym = this->weak_aliases_[ssym];
+ gold_assert(sym != NULL);
+ ssym = this->get_sized_symbol<size>(sym);
+ }
+ while (ssym != tosym);
+ }
+}
+
// The resolve functions build a little code for each symbol.
// Bit 0: 0 for global, 1 for weak.
// Bit 1: 0 for regular object, 1 for shared object
static const unsigned int undef_flag = 1 << def_undef_or_common_shift;
static const unsigned int common_flag = 2 << def_undef_or_common_shift;
-// Resolve a symbol. This is called the second and subsequent times
-// we see a symbol. TO is the pre-existing symbol. SYM is the new
-// symbol, seen in OBJECT. VERSION of the version of SYM.
+// This convenience function combines all the flags based on facts
+// about the symbol.
-template<int size, bool big_endian>
-void
-Symbol_table::resolve(Sized_symbol<size>* to,
- const elfcpp::Sym<size, big_endian>& sym,
- Object* object, const char* version)
+static unsigned int
+symbol_to_bits(elfcpp::STB binding, bool is_dynamic,
+ unsigned int shndx, bool is_ordinary, elfcpp::STT type)
{
- if (object->target()->has_resolve())
- {
- Sized_target<size, big_endian>* sized_target;
- sized_target = object->sized_target
- SELECT_SIZE_ENDIAN_NAME(size, big_endian) (
- SELECT_SIZE_ENDIAN_ONLY(size, big_endian));
- sized_target->resolve(to, sym, object, version);
- return;
- }
-
- if (!object->is_dynamic())
- {
- // Record that we've seen this symbol in a regular object.
- to->set_in_reg();
- }
- else
- {
- // Record that we've seen this symbol in a dynamic object.
- to->set_in_dyn();
- }
+ unsigned int bits;
- unsigned int frombits;
- switch (sym.get_st_bind())
+ switch (binding)
{
case elfcpp::STB_GLOBAL:
- frombits = global_flag;
+ case elfcpp::STB_GNU_UNIQUE:
+ bits = global_flag;
break;
case elfcpp::STB_WEAK:
- frombits = weak_flag;
+ bits = weak_flag;
break;
case elfcpp::STB_LOCAL:
- gold_error(_("%s: invalid STB_LOCAL symbol %s in external symbols"),
- object->name().c_str(), to->name());
- frombits = global_flag;
- break;
+ // We should only see externally visible symbols in the symbol
+ // table.
+ gold_error(_("invalid STB_LOCAL symbol in external symbols"));
+ bits = global_flag;
default:
- gold_error(_("%s: unsupported symbol binding %d for symbol %s"),
- object->name().c_str(),
- static_cast<int>(sym.get_st_bind()), to->name());
- frombits = global_flag;
- break;
+ // Any target which wants to handle STB_LOOS, etc., needs to
+ // define a resolve method.
+ gold_error(_("unsupported symbol binding"));
+ bits = global_flag;
}
- if (!object->is_dynamic())
- frombits |= regular_flag;
+ if (is_dynamic)
+ bits |= dynamic_flag;
else
- frombits |= dynamic_flag;
+ bits |= regular_flag;
- switch (sym.get_st_shndx())
+ switch (shndx)
{
case elfcpp::SHN_UNDEF:
- frombits |= undef_flag;
+ bits |= undef_flag;
break;
case elfcpp::SHN_COMMON:
- frombits |= common_flag;
+ if (!is_ordinary)
+ bits |= common_flag;
break;
default:
- if (sym.get_st_type() == elfcpp::STT_COMMON)
- frombits |= common_flag;
+ if (type == elfcpp::STT_COMMON)
+ bits |= common_flag;
+ else if (!is_ordinary && Symbol::is_common_shndx(shndx))
+ bits |= common_flag;
else
- frombits |= def_flag;
+ bits |= def_flag;
break;
}
- bool adjust_common_sizes;
- if (Symbol_table::should_override(to, frombits, &adjust_common_sizes))
+ return bits;
+}
+
+// Resolve a symbol. This is called the second and subsequent times
+// we see a symbol. TO is the pre-existing symbol. ST_SHNDX is the
+// section index for SYM, possibly adjusted for many sections.
+// IS_ORDINARY is whether ST_SHNDX is a normal section index rather
+// than a special code. ORIG_ST_SHNDX is the original section index,
+// before any munging because of discarded sections, except that all
+// non-ordinary section indexes are mapped to SHN_UNDEF. VERSION is
+// the version of SYM.
+
+template<int size, bool big_endian>
+void
+Symbol_table::resolve(Sized_symbol<size>* to,
+ const elfcpp::Sym<size, big_endian>& sym,
+ unsigned int st_shndx, bool is_ordinary,
+ unsigned int orig_st_shndx,
+ Object* object, const char* version)
+{
+ if (parameters->target().has_resolve())
{
- typename Sized_symbol<size>::Size_type tosize = to->symsize();
+ Sized_target<size, big_endian>* sized_target;
+ sized_target = parameters->sized_target<size, big_endian>();
+ sized_target->resolve(to, sym, object, version);
+ return;
+ }
- to->override(sym, object, version);
+ if (!object->is_dynamic())
+ {
+ // Record that we've seen this symbol in a regular object.
+ to->set_in_reg();
+ }
+ else if (st_shndx == elfcpp::SHN_UNDEF
+ && (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());
+ return;
+ }
+ else
+ {
+ // Record that we've seen this symbol in a dynamic object.
+ to->set_in_dyn();
+ }
+ // 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)
+ to->set_in_real_elf();
+
+ // If we're processing replacement files, allow new symbols to override
+ // the placeholders from the plugin objects.
+ 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;
+ }
+ }
+
+ unsigned int frombits = symbol_to_bits(sym.get_st_bind(),
+ object->is_dynamic(),
+ st_shndx, is_ordinary,
+ sym.get_st_type());
+
+ bool adjust_common_sizes;
+ typename Sized_symbol<size>::Size_type tosize = to->symsize();
+ if (Symbol_table::should_override(to, frombits, OBJECT, object,
+ &adjust_common_sizes))
+ {
+ this->override(to, sym, st_shndx, is_ordinary, object, version);
if (adjust_common_sizes && tosize > to->symsize())
to->set_symsize(tosize);
}
else
{
- if (adjust_common_sizes && sym.get_st_size() > to->symsize())
+ if (adjust_common_sizes && sym.get_st_size() > tosize)
to->set_symsize(sym.get_st_size());
+ // The ELF ABI says that even for a reference to a symbol we
+ // merge the visibility.
+ to->override_visibility(sym.get_st_visibility());
+ }
+
+ if (adjust_common_sizes && parameters->options().warn_common())
+ {
+ if (tosize > sym.get_st_size())
+ Symbol_table::report_resolve_problem(false,
+ _("common of '%s' overriding "
+ "smaller common"),
+ to, OBJECT, object);
+ else if (tosize < sym.get_st_size())
+ Symbol_table::report_resolve_problem(false,
+ _("common of '%s' overidden by "
+ "larger common"),
+ to, OBJECT, object);
+ else
+ Symbol_table::report_resolve_problem(false,
+ _("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. (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);
}
}
bool
Symbol_table::should_override(const Symbol* to, unsigned int frombits,
- bool* adjust_common_sizes)
+ Defined defined, Object* object,
+ bool* adjust_common_sizes)
{
*adjust_common_sizes = false;
unsigned int tobits;
- switch (to->binding())
- {
- case elfcpp::STB_GLOBAL:
- tobits = global_flag;
- break;
-
- case elfcpp::STB_WEAK:
- tobits = weak_flag;
- break;
-
- case elfcpp::STB_LOCAL:
- // We should only see externally visible symbols in the symbol
- // table.
- gold_unreachable();
-
- default:
- // Any target which wants to handle STB_LOOS, etc., needs to
- // define a resolve method.
- gold_unreachable();
- }
-
- if (to->source() == Symbol::FROM_OBJECT
- && to->object()->is_dynamic())
- tobits |= dynamic_flag;
+ if (to->source() == Symbol::IS_UNDEFINED)
+ tobits = symbol_to_bits(to->binding(), false, elfcpp::SHN_UNDEF, true,
+ to->type());
+ else if (to->source() != Symbol::FROM_OBJECT)
+ tobits = symbol_to_bits(to->binding(), false, elfcpp::SHN_ABS, false,
+ to->type());
else
- tobits |= regular_flag;
-
- switch (to->shndx())
{
- case elfcpp::SHN_UNDEF:
- tobits |= undef_flag;
- break;
-
- case elfcpp::SHN_COMMON:
- tobits |= common_flag;
- break;
-
- default:
- if (to->type() == elfcpp::STT_COMMON)
- tobits |= common_flag;
- else
- tobits |= def_flag;
- break;
+ bool is_ordinary;
+ unsigned int shndx = to->shndx(&is_ordinary);
+ tobits = symbol_to_bits(to->binding(),
+ to->object()->is_dynamic(),
+ shndx,
+ is_ordinary,
+ to->type());
}
// FIXME: Warn if either but not both of TO and SYM are STT_TLS.
{
case DEF * 16 + DEF:
// Two definitions of the same symbol.
- // FIXME: Report locations.
- gold_error(_("multiple definition of %s"), to->name());
+
+ // If either symbol is defined by an object included using
+ // --just-symbols, then don't warn. This is for compatibility
+ // with the GNU linker. FIXME: This is a hack.
+ if ((to->source() == Symbol::FROM_OBJECT && to->object()->just_symbols())
+ || (object != NULL && object->just_symbols()))
+ return false;
+
+ if (!parameters->options().muldefs())
+ Symbol_table::report_resolve_problem(true,
+ _("multiple definition of '%s'"),
+ to, defined, object);
return false;
case WEAK_DEF * 16 + DEF:
case DYN_COMMON * 16 + DEF:
case DYN_WEAK_COMMON * 16 + DEF:
// We've seen a common symbol and now we see a definition. The
- // definition overrides. FIXME: We should optionally issue, version a
- // warning.
+ // definition overrides.
+ if (parameters->options().warn_common())
+ Symbol_table::report_resolve_problem(false,
+ _("definition of '%s' overriding "
+ "common"),
+ to, defined, object);
return true;
case DEF * 16 + WEAK_DEF:
case DYN_COMMON * 16 + WEAK_DEF:
case DYN_WEAK_COMMON * 16 + WEAK_DEF:
// A weak definition does override a definition in a dynamic
- // object. FIXME: We should optionally issue a warning.
+ // object.
+ if (parameters->options().warn_common())
+ Symbol_table::report_resolve_problem(false,
+ _("definition of '%s' overriding "
+ "dynamic common definition"),
+ to, defined, object);
return true;
case DEF * 16 + DYN_DEF:
case DEF * 16 + COMMON:
// A common symbol does not override a definition.
+ if (parameters->options().warn_common())
+ Symbol_table::report_resolve_problem(false,
+ _("common '%s' overridden by "
+ "previous definition"),
+ to, defined, object);
return false;
case WEAK_DEF * 16 + COMMON:
}
}
+// Issue an error or warning due to symbol resolution. IS_ERROR
+// indicates an error rather than a warning. MSG is the error
+// message; it is expected to have a %s for the symbol name. TO is
+// the existing symbol. DEFINED/OBJECT is where the new symbol was
+// found.
+
+// FIXME: We should have better location information here. When the
+// symbol is defined, we should be able to pull the location from the
+// debug info if there is any.
+
+void
+Symbol_table::report_resolve_problem(bool is_error, const char* msg,
+ const Symbol* to, Defined defined,
+ Object* object)
+{
+ std::string demangled(to->demangled_name());
+ size_t len = strlen(msg) + demangled.length() + 10;
+ char* buf = new char[len];
+ snprintf(buf, len, msg, demangled.c_str());
+
+ const char* objname;
+ switch (defined)
+ {
+ case OBJECT:
+ objname = object->name().c_str();
+ break;
+ case COPY:
+ objname = _("COPY reloc");
+ break;
+ case DEFSYM:
+ case UNDEFINED:
+ objname = _("command line");
+ break;
+ case SCRIPT:
+ objname = _("linker script");
+ break;
+ case PREDEFINED:
+ objname = _("linker defined");
+ break;
+ default:
+ gold_unreachable();
+ }
+
+ if (is_error)
+ gold_error("%s: %s", objname, buf);
+ else
+ gold_warning("%s: %s", objname, buf);
+
+ delete[] buf;
+
+ if (to->source() == Symbol::FROM_OBJECT)
+ objname = to->object()->name().c_str();
+ else
+ objname = _("command line");
+ gold_info("%s: %s: previous definition here", program_name, objname);
+}
+
// A special case of should_override which is only called for a strong
// defined symbol from a regular object file. This is used when
// defining special symbols.
bool
-Symbol_table::should_override_with_special(const Symbol* to)
+Symbol_table::should_override_with_special(const Symbol* to, Defined defined)
{
bool adjust_common_sizes;
unsigned int frombits = global_flag | regular_flag | def_flag;
- bool ret = Symbol_table::should_override(to, frombits, &adjust_common_sizes);
+ bool ret = Symbol_table::should_override(to, frombits, defined, NULL,
+ &adjust_common_sizes);
gold_assert(!adjust_common_sizes);
return ret;
}
void
Symbol::override_base_with_special(const Symbol* from)
{
+ gold_assert(this->name_ == from->name_ || this->has_alias());
+
this->source_ = from->source_;
switch (from->source_)
{
case IN_OUTPUT_SEGMENT:
this->u_.in_output_segment = from->u_.in_output_segment;
break;
- case CONSTANT:
+ case IS_CONSTANT:
+ case IS_UNDEFINED:
break;
default:
gold_unreachable();
break;
}
- if (from->version_ != NULL && this->version_ != from->version_)
- {
- gold_assert(this->version_ == NULL);
- this->version_ = from->version_;
- }
-
+ this->override_version(from->version_);
this->type_ = from->type_;
this->binding_ = from->binding_;
- this->visibility_ = from->visibility_;
+ this->override_visibility(from->visibility_);
this->nonvis_ = from->nonvis_;
// Special symbols are always considered to be regular symbols.
this->in_reg_ = true;
+
+ if (from->needs_dynsym_entry_)
+ this->needs_dynsym_entry_ = true;
+ if (from->needs_dynsym_value_)
+ this->needs_dynsym_value_ = true;
+
+ // We shouldn't see these flags. If we do, we need to handle them
+ // somehow.
+ gold_assert(!from->is_forwarder_);
+ gold_assert(!from->has_plt_offset());
+ gold_assert(!from->has_warning_);
+ gold_assert(!from->is_copied_from_dynobj_);
+ gold_assert(!from->is_forced_local_);
}
// Override a symbol with a special symbol.
this->symsize_ = from->symsize_;
}
+// Override TOSYM with the special symbol FROMSYM. This handles all
+// aliases of TOSYM.
+
+template<int size>
+void
+Symbol_table::override_with_special(Sized_symbol<size>* tosym,
+ const Sized_symbol<size>* fromsym)
+{
+ tosym->override_with_special(fromsym);
+ if (tosym->has_alias())
+ {
+ Symbol* sym = this->weak_aliases_[tosym];
+ gold_assert(sym != NULL);
+ Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym);
+ do
+ {
+ ssym->override_with_special(fromsym);
+ sym = this->weak_aliases_[ssym];
+ gold_assert(sym != NULL);
+ ssym = this->get_sized_symbol<size>(sym);
+ }
+ while (ssym != tosym);
+ }
+ if (tosym->binding() == elfcpp::STB_LOCAL
+ || ((tosym->visibility() == elfcpp::STV_HIDDEN
+ || tosym->visibility() == elfcpp::STV_INTERNAL)
+ && (tosym->binding() == elfcpp::STB_GLOBAL
+ || tosym->binding() == elfcpp::STB_GNU_UNIQUE
+ || tosym->binding() == elfcpp::STB_WEAK)
+ && !parameters->options().relocatable()))
+ this->force_local(tosym);
+}
+
// Instantiate the templates we need. We could use the configure
// script to restrict this to only the ones needed for implemented
// targets.
Symbol_table::resolve<32, false>(
Sized_symbol<32>* to,
const elfcpp::Sym<32, false>& sym,
+ unsigned int st_shndx,
+ bool is_ordinary,
+ unsigned int orig_st_shndx,
Object* object,
const char* version);
#endif
Symbol_table::resolve<32, true>(
Sized_symbol<32>* to,
const elfcpp::Sym<32, true>& sym,
+ unsigned int st_shndx,
+ bool is_ordinary,
+ unsigned int orig_st_shndx,
Object* object,
const char* version);
#endif
Symbol_table::resolve<64, false>(
Sized_symbol<64>* to,
const elfcpp::Sym<64, false>& sym,
+ unsigned int st_shndx,
+ bool is_ordinary,
+ unsigned int orig_st_shndx,
Object* object,
const char* version);
#endif
Symbol_table::resolve<64, true>(
Sized_symbol<64>* to,
const elfcpp::Sym<64, true>& sym,
+ unsigned int st_shndx,
+ bool is_ordinary,
+ unsigned int orig_st_shndx,
Object* object,
const char* version);
#endif
#if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
template
void
-Sized_symbol<32>::override_with_special(const Sized_symbol<32>*);
+Symbol_table::override_with_special<32>(Sized_symbol<32>*,
+ const Sized_symbol<32>*);
#endif
#if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
template
void
-Sized_symbol<64>::override_with_special(const Sized_symbol<64>*);
+Symbol_table::override_with_special<64>(Sized_symbol<64>*,
+ const Sized_symbol<64>*);
#endif
} // End namespace gold.
projects / deliverable / binutils-gdb.git / blobdiff