gold regression vs BFD ld: __ehdr_start
Cary Coutant
ccoutant@google.com
Tue Apr 1 23:02:00 GMT 2014
Here's an updated patch that handles the weak reference properly and
handles __ehdr_start correctly (at least) when a SECTIONS clause is
present.
-cary
2014-04-01 Cary Coutant <ccoutant@google.com>
* gold/defstd.cc (in_segment): Define __ehdr_start here...
* gold/layout.cc (Layout::finalize): ...Instead of here. Set the
output segment when known.
* gold/resolve.cc (Symbol::override_base_with_special): Remember
the original binding.
* gold/symtab.cc (Symbol::set_output_segment): New function.
(Symbol::set_undefined): New function.
* gold/symtab.h (Symbol::is_weak_undefined): Check original undef
binding.
(Symbol::is_strong_undefined): New function.
(Symbol::set_output_segment): New function.
(Symbol::set_undefined): New function.
* gold/target-reloc.h (is_strong_undefined): Remove.
(issue_undefined_symbol_error): Call Symbol::is_weak_undefined.
Check for hidden undefs.
(relocate_section): Call Symbol::is_strong_undefined.
-------------- next part --------------
2014-04-01 Cary Coutant <ccoutant@google.com>
* gold/defstd.cc (in_segment): Define __ehdr_start here...
* gold/layout.cc (Layout::finalize): ...Instead of here. Set the
output segment when known.
* gold/resolve.cc (Symbol::override_base_with_special): Remember
the original binding.
* gold/symtab.cc (Symbol::set_output_segment): New function.
(Symbol::set_undefined): New function.
* gold/symtab.h (Symbol::is_weak_undefined): Check original undef
binding.
(Symbol::is_strong_undefined): New function.
(Symbol::set_output_segment): New function.
(Symbol::set_undefined): New function.
* gold/target-reloc.h (is_strong_undefined): Remove.
(issue_undefined_symbol_error): Call Symbol::is_weak_undefined.
Check for hidden undefs.
(relocate_section): Call Symbol::is_strong_undefined.
diff --git a/gold/defstd.cc b/gold/defstd.cc
index a50e75d..cee68a0 100644
--- a/gold/defstd.cc
+++ b/gold/defstd.cc
@@ -141,6 +141,20 @@ const Define_symbol_in_segment in_segment[] =
true // only_if_ref
},
{
+ "__ehdr_start", // name
+ elfcpp::PT_LOAD, // segment_type
+ elfcpp::PF(0), // segment_flags_set
+ elfcpp::PF(0), // segment_flags_clear
+ 0, // value
+ 0, // size
+ elfcpp::STT_NOTYPE, // type
+ elfcpp::STB_GLOBAL, // binding
+ elfcpp::STV_HIDDEN, // visibility
+ 0, // nonvis
+ Symbol::SEGMENT_START, // offset_from_base
+ true // only_if_ref
+ },
+ {
"etext", // name
elfcpp::PT_LOAD, // segment_type
elfcpp::PF_X, // segment_flags_set
diff --git a/gold/layout.cc b/gold/layout.cc
index c96516c..9bd19c5 100644
--- a/gold/layout.cc
+++ b/gold/layout.cc
@@ -2743,12 +2743,14 @@ Layout::finalize(const Input_objects* input_objects, Symbol_table* symtab,
// If there is a load segment that contains the file and program headers,
// provide a symbol __ehdr_start pointing there.
// A program can use this to examine itself robustly.
- if (load_seg != NULL)
- symtab->define_in_output_segment("__ehdr_start", NULL,
- Symbol_table::PREDEFINED, load_seg, 0, 0,
- elfcpp::STT_NOTYPE, elfcpp::STB_GLOBAL,
- elfcpp::STV_HIDDEN, 0,
- Symbol::SEGMENT_START, true);
+ Symbol *ehdr_start = symtab->lookup("__ehdr_start");
+ if (ehdr_start != NULL && ehdr_start->is_predefined())
+ {
+ if (load_seg != NULL)
+ ehdr_start->set_output_segment(load_seg, Symbol::SEGMENT_START);
+ else
+ ehdr_start->set_undefined();
+ }
// Set the file offsets of all the non-data sections we've seen so
// far which don't have to wait for the input sections. We need
diff --git a/gold/resolve.cc b/gold/resolve.cc
index 9b442e2..8cc637a 100644
--- a/gold/resolve.cc
+++ b/gold/resolve.cc
@@ -915,6 +915,10 @@ Symbol::override_base_with_special(const Symbol* from)
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_)
{
diff --git a/gold/symtab.cc b/gold/symtab.cc
index 1a69f5b..4e8afb1 100644
--- a/gold/symtab.cc
+++ b/gold/symtab.cc
@@ -527,6 +527,31 @@ Symbol::set_output_section(Output_section* os)
}
}
+// Set the symbol's output segment. This is used for pre-defined
+// symbols whose segments aren't known until after layout is done
+// (e.g., __ehdr_start).
+
+void
+Symbol::set_output_segment(Output_segment* os, Segment_offset_base base)
+{
+ gold_assert(this->is_predefined_);
+ this->source_ = IN_OUTPUT_SEGMENT;
+ this->u_.in_output_segment.output_segment = os;
+ this->u_.in_output_segment.offset_base = base;
+}
+
+// Set the symbol to undefined. This is used for pre-defined
+// symbols whose segments aren't known until after layout is done
+// (e.g., __ehdr_start).
+
+void
+Symbol::set_undefined()
+{
+ gold_assert(this->is_predefined_);
+ this->source_ = IS_UNDEFINED;
+ this->is_predefined_ = false;
+}
+
// Class Symbol_table.
Symbol_table::Symbol_table(unsigned int count,
diff --git a/gold/symtab.h b/gold/symtab.h
index b06c7b4..b6366d4 100644
--- a/gold/symtab.h
+++ b/gold/symtab.h
@@ -238,7 +238,7 @@ class Symbol
override_visibility(elfcpp::STV);
// Set whether the symbol was originally a weak undef or a regular undef
- // when resolved by a dynamic def.
+ // when resolved by a dynamic def or by a special symbol.
inline void
set_undef_binding(elfcpp::STB bind)
{
@@ -249,7 +249,8 @@ class Symbol
}
}
- // Return TRUE if a weak undef was resolved by a dynamic def.
+ // Return TRUE if a weak undef was resolved by a dynamic def or
+ // by a special symbol.
inline bool
is_undef_binding_weak() const
{ return this->undef_binding_weak_; }
@@ -517,7 +518,20 @@ class Symbol
// Return whether this is a weak undefined symbol.
bool
is_weak_undefined() const
- { return this->is_undefined() && this->binding() == elfcpp::STB_WEAK; }
+ {
+ return (this->is_undefined()
+ && (this->binding() == elfcpp::STB_WEAK
+ || this->is_undef_binding_weak()));
+ }
+
+ // Return whether this is a strong undefined symbol.
+ bool
+ is_strong_undefined() const
+ {
+ return (this->is_undefined()
+ && this->binding() != elfcpp::STB_WEAK
+ && !this->is_undef_binding_weak());
+ }
// Return whether this is an absolute symbol.
bool
@@ -782,6 +796,18 @@ class Symbol
void
set_output_section(Output_section*);
+ // Set the symbol's output segment. This is used for pre-defined
+ // symbols whose segments aren't known until after layout is done
+ // (e.g., __ehdr_start).
+ void
+ set_output_segment(Output_segment*, Segment_offset_base);
+
+ // Set the symbol to undefined. This is used for pre-defined
+ // symbols whose segments aren't known until after layout is done
+ // (e.g., __ehdr_start).
+ void
+ set_undefined();
+
// Return whether there should be a warning for references to this
// symbol.
bool
@@ -1030,7 +1056,7 @@ class Symbol
// True if UNDEF_BINDING_WEAK_ has been set (bit 32).
bool undef_binding_set_ : 1;
// True if this symbol was a weak undef resolved by a dynamic def
- // (bit 33).
+ // or by a special symbol (bit 33).
bool undef_binding_weak_ : 1;
// True if this symbol is a predefined linker symbol (bit 34).
bool is_predefined_ : 1;
diff --git a/gold/target-reloc.h b/gold/target-reloc.h
index f49020a..e44519b 100644
--- a/gold/target-reloc.h
+++ b/gold/target-reloc.h
@@ -143,12 +143,6 @@ class Default_comdat_behavior
}
};
-inline bool
-is_strong_undefined(const Symbol* sym)
-{
- return sym->is_undefined() && sym->binding() != elfcpp::STB_WEAK;
-}
-
// Give an error for a symbol with non-default visibility which is not
// defined locally.
@@ -190,7 +184,7 @@ issue_undefined_symbol_error(const Symbol* sym)
return false;
// We don't report weak symbols.
- if (sym->binding() == elfcpp::STB_WEAK)
+ if (sym->is_weak_undefined())
return false;
// We don't report symbols defined in discarded sections.
@@ -216,6 +210,10 @@ issue_undefined_symbol_error(const Symbol* sym)
return false;
}
+ // If the symbol is hidden, report it.
+ if (sym->visibility() == elfcpp::STV_HIDDEN)
+ return true;
+
// When creating a shared library, only report unresolved symbols if
// -z defs was used.
if (parameters->options().shared() && !parameters->options().defs())
@@ -419,7 +417,7 @@ relocate_section(
gold_undefined_symbol_at_location(sym, relinfo, i, offset);
else if (sym != NULL
&& sym->visibility() != elfcpp::STV_DEFAULT
- && (is_strong_undefined(sym) || sym->is_from_dynobj()))
+ && (sym->is_strong_undefined() || sym->is_from_dynobj()))
visibility_error(sym);
if (sym != NULL && sym->has_warning())
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