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Fix incorrect handling of STT_COMMON symbols in shared libraries.

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The gABI allows STT_COMMON symbols to appear in executables and shared
objects, so that the dynamic loader can resolve commons across modules.
When reading a shared object, however, an STT_COMMON symbol should be
treated as a regular definition at link time.

In a relocatable object, the gABI requires that any STT_COMMON symbols
must also be defined in the special SHN_COMMON section (which we extend
to include target-specific small and large common sections). Thus,
there is no need for gold to treat STT_COMMON symbols as common unless
the st_shndx field is also set to a common section.

gold/
	PR gold/18288
	* resolve.cc (symbol_to_bits): Remove type parameter; adjust all
	callers. Don't use STT_COMMON to check for common symbols.
	(Symbol_table::resolve): Warn if relocatable object has STT_COMMON
	symbol that's not in a common section.
	* symtab.h (Symbol::is_common): Don't use STT_COMMON to check for
	common symbols.
This commit is contained in:
Cary Coutant 2015-06-07 14:03:09 -07:00
parent 66f38e2951
commit b8cf50755b
3 changed files with 27 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
gold/ChangeLog
View File

@ -1,3 +1,13 @@
2015-06-07 Cary Coutant <ccoutant@gmail.com>
PR gold/18288
* resolve.cc (symbol_to_bits): Remove type parameter; adjust all
callers. Don't use STT_COMMON to check for common symbols.
(Symbol_table::resolve): Warn if relocatable object has STT_COMMON
symbol that's not in a common section.
* symtab.h (Symbol::is_common): Don't use STT_COMMON to check for
common symbols.
2015-06-04 Cary Coutant <ccoutant@gmail.com>
PR gold/18200

30
gold/resolve.cc
View File

@ -173,7 +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;
@ -218,9 +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;
@ -272,6 +270,15 @@ Symbol_table::resolve(Sized_symbol<size>* 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();
}
@ -314,7 +321,8 @@ Symbol_table::resolve(Sized_symbol<size>* to,
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)
if (to->is_common()
&& !is_ordinary && Symbol::is_common_shndx(st_shndx))
{
adjust_common = true;
tosize = to->symsize();
@ -370,8 +378,7 @@ Symbol_table::resolve(Sized_symbol<size>* to,
: sym.get_st_type());
unsigned int frombits = symbol_to_bits(sym.get_st_bind(),
object->is_dynamic(),
st_shndx, is_ordinary,
fromtype);
st_shndx, is_ordinary);
bool adjust_common_sizes;
bool adjust_dyndef;
@ -454,11 +461,9 @@ Symbol_table::should_override(const Symbol* to, unsigned int frombits,
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;
@ -466,8 +471,7 @@ 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);
}
if ((to->type() == elfcpp::STT_TLS) ^ (fromtype == elfcpp::STT_TLS)

2
gold/symtab.h
View File

@ -557,8 +557,6 @@ class Symbol
{
if (this->source_ != FROM_OBJECT)
return false;
if (this->type_ == elfcpp::STT_COMMON)
return true;
bool is_ordinary;
unsigned int shndx = this->shndx(&is_ordinary);
return !is_ordinary && Symbol::is_common_shndx(shndx);