// resolve.cc -- symbol resolution for gold
-// Copyright 2006, 2007, 2008 Free Software Foundation, Inc.
+// Copyright (C) 2006-2014 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
{
}
}
+// 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>
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->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;
switch (binding)
{
case elfcpp::STB_GLOBAL:
+ case elfcpp::STB_GNU_UNIQUE:
bits = global_flag;
break;
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<int>(binding));
bits = global_flag;
}
default:
if (type == elfcpp::STT_COMMON)
bits |= common_flag;
+ else if (!is_ordinary && Symbol::is_common_shndx(shndx))
+ bits |= common_flag;
else
bits |= def_flag;
break;
unsigned int orig_st_shndx,
Object* object, const char* version)
{
- if (object->target()->has_resolve())
+ // 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<size, big_endian>* sized_target;
- sized_target = object->sized_target<size, big_endian>();
+ sized_target = parameters->sized_target<size, big_endian>();
sized_target->resolve(to, sym, object, version);
return;
}
// 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();
}
- unsigned int frombits = symbol_to_bits(sym.get_st_bind(),
- object->is_dynamic(),
- st_shndx, is_ordinary,
- sym.get_st_type());
+ // 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 && !object->is_dynamic())
+ to->set_in_real_elf();
- bool adjust_common_sizes;
- if (Symbol_table::should_override(to, frombits, object,
- &adjust_common_sizes))
+ // 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)
{
- typename Sized_symbol<size>::Size_type tosize = to->symsize();
-
- 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())
- to->set_symsize(sym.get_st_size());
+ Pluginobj* obj = to->object()->pluginobj();
+ if (obj != NULL
+ && parameters->options().plugins()->in_replacement_phase())
+ {
+ bool adjust_common = false;
+ typename Sized_symbol<size>::Size_type tosize = 0;
+ typename Sized_symbol<size>::Value_type tovalue = 0;
+ if (to->is_common() && !is_ordinary && st_shndx == elfcpp::SHN_COMMON)
+ {
+ 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. (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;
+ // 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
+ && (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
&& to->name()[0] == '_' && to->name()[1] == 'Z')
{
Symbol_location fromloc
- = { object, orig_st_shndx, sym.get_st_value() };
+ = { object, orig_st_shndx, static_cast<off_t>(sym.get_st_value()) };
Symbol_location toloc = { to->object(), to->shndx(&to_is_ordinary),
- to->value() };
+ static_cast<off_t>(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,
+ fromtype);
+
+ bool adjust_common_sizes;
+ bool adjust_dyndef;
+ typename Sized_symbol<size>::Size_type tosize = to->symsize();
+ if (Symbol_table::should_override(to, frombits, fromtype, OBJECT,
+ object, &adjust_common_sizes,
+ &adjust_dyndef))
+ {
+ elfcpp::STB tobinding = to->binding();
+ typename Sized_symbol<size>::Value_type tovalue = to->value();
+ this->override(to, sym, st_shndx, is_ordinary, object, version);
+ 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)
+ {
+ 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());
+ }
+
+ 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);
+ }
}
// Handle the core of symbol resolution. This is called with the
bool
Symbol_table::should_override(const Symbol* to, unsigned int frombits,
- Object* object, bool* adjust_common_sizes)
+ elfcpp::STT fromtype, Defined defined,
+ Object* object, bool* adjust_common_sizes,
+ bool* adjust_dyndef)
{
*adjust_common_sizes = false;
+ *adjust_dyndef = false;
unsigned int tobits;
if (to->source() == Symbol::IS_UNDEFINED)
to->type());
}
- // 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
// --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->just_symbols())
+ || (object != NULL && object->just_symbols()))
return false;
- // FIXME: Do a better job of reporting locations.
- gold_error(_("%s: multiple definition of %s"),
- object != NULL ? object->name().c_str() : _("command line"),
- to->demangled_name().c_str());
- gold_error(_("%s: previous definition here"),
- (to->source() == Symbol::FROM_OBJECT
- ? to->object()->name().c_str()
- : _("command line")));
+ 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:
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:
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:
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:
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:
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:
+ case INCREMENTAL_BASE:
+ 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,
+ 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, 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);
+ gold_assert(!adjust_common_sizes && !adjust_dyn_def);
return ret;
}
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_)
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->visibility_ = from->visibility_;
+ this->override_visibility(from->visibility_);
this->nonvis_ = from->nonvis_;
// Special symbols are always considered to be regular symbols.
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_target_special_ || this->is_target_special_);
gold_assert(!from->is_forwarder_);
- gold_assert(!from->has_plt_offset_);
+ gold_assert(!from->has_plt_offset());
gold_assert(!from->has_warning_);
gold_assert(!from->is_copied_from_dynobj_);
gold_assert(!from->is_forced_local_);
}
while (ssym != tosym);
}
- if (tosym->binding() == elfcpp::STB_LOCAL)
+ 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);
}
// 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>(
unsigned int orig_st_shndx,
Object* object,
const char* version);
-#endif
-#ifdef HAVE_TARGET_32_BIG
template
void
Symbol_table::resolve<32, true>(
const char* 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>(
unsigned int orig_st_shndx,
Object* object,
const char* version);
-#endif
-#ifdef HAVE_TARGET_64_BIG
template
void
Symbol_table::resolve<64, true>(
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