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[gold commit] Fix issue where first reserved word of GOT is not initialized if there is no PLT
- From: ccoutant at google dot com (Cary Coutant)
- To: binutils at sourceware dot org
- Date: Tue, 6 May 2014 14:22:57 -0700 (PDT)
- Subject: [gold commit] Fix issue where first reserved word of GOT is not initialized if there is no PLT
- Authentication-results: sourceware.org; auth=none
This patch fixes an issue where reserved words of GOT are not initialized
if there is no PLT. The reserved words were only initialized when writing
the PLT, so if there is no PLT, they were never initialized. The fix is
to create a new Output_data class for the .got.plt section, and have its
do_write() method initialize those three words. The remainder of .got.plt
can continue to be written when the PLT is written.
Tested on i386 and x86_64.
-cary
2014-05-06 Cary Coutant <ccoutant@google.com>
gold/
PR gold/16900
* i386.cc (Output_data_got_plt_i386): New class.
(Output_data_plt_i386::Output_data_plt_i386): Change type of got_plt
parameter. Change all callers.
(Output_data_plt_i386::layout_): Remove.
(Output_data_plt_i386::got_plt_): Change type.
(Target_i386::got_plt_): Change type. Change all references.
(Target_i386::got_section): Create instance of new class.
(Output_data_got_plt_i386::do_write): New function.
* x86_64.cc (Output_data_got_plt_x86_64): New class.
(Output_data_plt_x86_64::Output_data_plt_x86_64): Change type of got_plt
parameter. Change all callers.
(Output_data_plt_x86_64::layout_): Remove.
(Output_data_plt_x86_64::got_plt_): Change type.
(Target_x86_64::got_plt_): Change type. Change all references.
(Target_x86_64::got_section): Create instance of new class.
(Output_data_got_plt_x86_64::do_write): New function.
(Output_data_plt_x86_64::do_write): Don't write reserved words in GOT.
(Target_x86_64<size>::init_got_plt_for_update): Create instance of new
class.
diff --git a/gold/i386.cc b/gold/i386.cc
index a2f7522..ed7f3f9 100644
--- a/gold/i386.cc
+++ b/gold/i386.cc
@@ -47,6 +47,32 @@ namespace
using namespace gold;
+// A class to handle the .got.plt section.
+
+class Output_data_got_plt_i386 : public Output_section_data_build
+{
+ public:
+ Output_data_got_plt_i386(Layout* layout)
+ : Output_section_data_build(4),
+ layout_(layout)
+ { }
+
+ protected:
+ // Write out the PLT data.
+ void
+ do_write(Output_file*);
+
+ // Write to a map file.
+ void
+ do_print_to_mapfile(Mapfile* mapfile) const
+ { mapfile->print_output_data(this, "** GOT PLT"); }
+
+ private:
+ // A pointer to the Layout class, so that we can find the .dynamic
+ // section when we write out the GOT PLT section.
+ Layout* layout_;
+};
+
// A class to handle the PLT data.
// This is an abstract base class that handles most of the linker details
// but does not know the actual contents of PLT entries. The derived
@@ -58,7 +84,7 @@ class Output_data_plt_i386 : public Output_section_data
typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;
Output_data_plt_i386(Layout*, uint64_t addralign,
- Output_data_space*, Output_data_space*);
+ Output_data_got_plt_i386*, Output_data_space*);
// Add an entry to the PLT.
void
@@ -201,9 +227,6 @@ class Output_data_plt_i386 : public Output_section_data
unsigned int got_offset;
};
- // A pointer to the Layout class, so that we can find the .dynamic
- // section when we write out the GOT PLT section.
- Layout* layout_;
// The reloc section.
Reloc_section* rel_;
// The TLS_DESC relocations, if necessary. These must follow the
@@ -213,7 +236,7 @@ class Output_data_plt_i386 : public Output_section_data
// regular relocatoins and the TLS_DESC relocations.
Reloc_section* irelative_rel_;
// The .got.plt section.
- Output_data_space* got_plt_;
+ Output_data_got_plt_i386* got_plt_;
// The part of the .got.plt section used for IRELATIVE relocs.
Output_data_space* got_irelative_;
// The number of PLT entries.
@@ -236,7 +259,7 @@ class Output_data_plt_i386_standard : public Output_data_plt_i386
{
public:
Output_data_plt_i386_standard(Layout* layout,
- Output_data_space* got_plt,
+ Output_data_got_plt_i386* got_plt,
Output_data_space* got_irelative)
: Output_data_plt_i386(layout, plt_entry_size, got_plt, got_irelative)
{ }
@@ -267,7 +290,7 @@ class Output_data_plt_i386_exec : public Output_data_plt_i386_standard
{
public:
Output_data_plt_i386_exec(Layout* layout,
- Output_data_space* got_plt,
+ Output_data_got_plt_i386* got_plt,
Output_data_space* got_irelative)
: Output_data_plt_i386_standard(layout, got_plt, got_irelative)
{ }
@@ -298,7 +321,7 @@ class Output_data_plt_i386_dyn : public Output_data_plt_i386_standard
{
public:
Output_data_plt_i386_dyn(Layout* layout,
- Output_data_space* got_plt,
+ Output_data_got_plt_i386* got_plt,
Output_data_space* got_irelative)
: Output_data_plt_i386_standard(layout, got_plt, got_irelative)
{ }
@@ -506,14 +529,14 @@ class Target_i386 : public Sized_target<32, false>
// This chooses the right PLT flavor for an executable or a shared object.
Output_data_plt_i386*
make_data_plt(Layout* layout,
- Output_data_space* got_plt,
+ Output_data_got_plt_i386* got_plt,
Output_data_space* got_irelative,
bool dyn)
{ return this->do_make_data_plt(layout, got_plt, got_irelative, dyn); }
virtual Output_data_plt_i386*
do_make_data_plt(Layout* layout,
- Output_data_space* got_plt,
+ Output_data_got_plt_i386* got_plt,
Output_data_space* got_irelative,
bool dyn)
{
@@ -720,7 +743,7 @@ class Target_i386 : public Sized_target<32, false>
got_section(Symbol_table*, Layout*);
// Get the GOT PLT section.
- Output_data_space*
+ Output_data_got_plt_i386*
got_plt_section() const
{
gold_assert(this->got_plt_ != NULL);
@@ -813,7 +836,7 @@ class Target_i386 : public Sized_target<32, false>
// The PLT section.
Output_data_plt_i386* plt_;
// The GOT PLT section.
- Output_data_space* got_plt_;
+ Output_data_got_plt_i386* got_plt_;
// The GOT section for IRELATIVE relocations.
Output_data_space* got_irelative_;
// The GOT section for TLSDESC relocations.
@@ -885,7 +908,7 @@ Target_i386::got_section(Symbol_table* symtab, Layout* layout)
| elfcpp::SHF_WRITE),
this->got_, got_order, true);
- this->got_plt_ = new Output_data_space(4, "** GOT PLT");
+ this->got_plt_ = new Output_data_got_plt_i386(layout);
layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS,
(elfcpp::SHF_ALLOC
| elfcpp::SHF_WRITE),
@@ -972,18 +995,39 @@ Target_i386::rel_irelative_section(Layout* layout)
return this->rel_irelative_;
}
+// Write the first three reserved words of the .got.plt section.
+// The remainder of the section is written while writing the PLT
+// in Output_data_plt_i386::do_write.
+
+void
+Output_data_got_plt_i386::do_write(Output_file* of)
+{
+ // The first entry in the GOT is the address of the .dynamic section
+ // aka the PT_DYNAMIC segment. The next two entries are reserved.
+ // We saved space for them when we created the section in
+ // Target_i386::got_section.
+ const off_t got_file_offset = this->offset();
+ gold_assert(this->data_size() >= 12);
+ unsigned char* const got_view = of->get_output_view(got_file_offset, 12);
+ Output_section* dynamic = this->layout_->dynamic_section();
+ uint32_t dynamic_addr = dynamic == NULL ? 0 : dynamic->address();
+ elfcpp::Swap<32, false>::writeval(got_view, dynamic_addr);
+ memset(got_view + 4, 0, 8);
+ of->write_output_view(got_file_offset, 12, got_view);
+}
+
// Create the PLT section. The ordinary .got section is an argument,
// since we need to refer to the start. We also create our own .got
// section just for PLT entries.
Output_data_plt_i386::Output_data_plt_i386(Layout* layout,
uint64_t addralign,
- Output_data_space* got_plt,
+ Output_data_got_plt_i386* got_plt,
Output_data_space* got_irelative)
: Output_section_data(addralign),
- layout_(layout), tls_desc_rel_(NULL),
- irelative_rel_(NULL), got_plt_(got_plt), got_irelative_(got_irelative),
- count_(0), irelative_count_(0), global_ifuncs_(), local_ifuncs_()
+ tls_desc_rel_(NULL), irelative_rel_(NULL), got_plt_(got_plt),
+ got_irelative_(got_irelative), count_(0), irelative_count_(0),
+ global_ifuncs_(), local_ifuncs_()
{
this->rel_ = new Reloc_section(false);
layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL,
@@ -1323,6 +1367,7 @@ Output_data_plt_i386::do_write(Output_file* of)
const section_size_type got_size =
convert_to_section_size_type(this->got_plt_->data_size()
+ this->got_irelative_->data_size());
+
unsigned char* const got_view = of->get_output_view(got_file_offset,
got_size);
@@ -1334,18 +1379,9 @@ Output_data_plt_i386::do_write(Output_file* of)
this->fill_first_plt_entry(pov, got_address);
pov += this->get_plt_entry_size();
- unsigned char* got_pov = got_view;
-
- // The first entry in the GOT is the address of the .dynamic section
- // aka the PT_DYNAMIC segment. The next two entries are reserved.
- // We saved space for them when we created the section in
- // Target_i386::got_section.
- Output_section* dynamic = this->layout_->dynamic_section();
- uint32_t dynamic_addr = dynamic == NULL ? 0 : dynamic->address();
- elfcpp::Swap<32, false>::writeval(got_pov, dynamic_addr);
- got_pov += 4;
- memset(got_pov, 0, 8);
- got_pov += 8;
+ // The first three entries in the GOT are reserved, and are written
+ // by Output_data_got_plt_i386::do_write.
+ unsigned char* got_pov = got_view + 12;
const int rel_size = elfcpp::Elf_sizes<32>::rel_size;
@@ -3834,7 +3870,7 @@ class Output_data_plt_i386_nacl : public Output_data_plt_i386
{
public:
Output_data_plt_i386_nacl(Layout* layout,
- Output_data_space* got_plt,
+ Output_data_got_plt_i386* got_plt,
Output_data_space* got_irelative)
: Output_data_plt_i386(layout, plt_entry_size, got_plt, got_irelative)
{ }
@@ -3863,7 +3899,7 @@ class Output_data_plt_i386_nacl_exec : public Output_data_plt_i386_nacl
{
public:
Output_data_plt_i386_nacl_exec(Layout* layout,
- Output_data_space* got_plt,
+ Output_data_got_plt_i386* got_plt,
Output_data_space* got_irelative)
: Output_data_plt_i386_nacl(layout, got_plt, got_irelative)
{ }
@@ -3892,7 +3928,7 @@ class Output_data_plt_i386_nacl_dyn : public Output_data_plt_i386_nacl
{
public:
Output_data_plt_i386_nacl_dyn(Layout* layout,
- Output_data_space* got_plt,
+ Output_data_got_plt_i386* got_plt,
Output_data_space* got_irelative)
: Output_data_plt_i386_nacl(layout, got_plt, got_irelative)
{ }
@@ -3926,7 +3962,7 @@ class Target_i386_nacl : public Target_i386
protected:
virtual Output_data_plt_i386*
do_make_data_plt(Layout* layout,
- Output_data_space* got_plt,
+ Output_data_got_plt_i386* got_plt,
Output_data_space* got_irelative,
bool dyn)
{
diff --git a/gold/x86_64.cc b/gold/x86_64.cc
index aa9e5b4..255ebb9 100644
--- a/gold/x86_64.cc
+++ b/gold/x86_64.cc
@@ -48,6 +48,37 @@ namespace
using namespace gold;
+// A class to handle the .got.plt section.
+
+class Output_data_got_plt_x86_64 : public Output_section_data_build
+{
+ public:
+ Output_data_got_plt_x86_64(Layout* layout)
+ : Output_section_data_build(8),
+ layout_(layout)
+ { }
+
+ Output_data_got_plt_x86_64(Layout* layout, off_t data_size)
+ : Output_section_data_build(data_size, 8),
+ layout_(layout)
+ { }
+
+ protected:
+ // Write out the PLT data.
+ void
+ do_write(Output_file*);
+
+ // Write to a map file.
+ void
+ do_print_to_mapfile(Mapfile* mapfile) const
+ { mapfile->print_output_data(this, "** GOT PLT"); }
+
+ private:
+ // A pointer to the Layout class, so that we can find the .dynamic
+ // section when we write out the GOT PLT section.
+ Layout* layout_;
+};
+
// A class to handle the PLT data.
// This is an abstract base class that handles most of the linker details
// but does not know the actual contents of PLT entries. The derived
@@ -61,9 +92,9 @@ class Output_data_plt_x86_64 : public Output_section_data
Output_data_plt_x86_64(Layout* layout, uint64_t addralign,
Output_data_got<64, false>* got,
- Output_data_space* got_plt,
+ Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative)
- : Output_section_data(addralign), layout_(layout), tlsdesc_rel_(NULL),
+ : Output_section_data(addralign), tlsdesc_rel_(NULL),
irelative_rel_(NULL), got_(got), got_plt_(got_plt),
got_irelative_(got_irelative), count_(0), irelative_count_(0),
tlsdesc_got_offset_(-1U), free_list_()
@@ -71,12 +102,12 @@ class Output_data_plt_x86_64 : public Output_section_data
Output_data_plt_x86_64(Layout* layout, uint64_t plt_entry_size,
Output_data_got<64, false>* got,
- Output_data_space* got_plt,
+ Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative,
unsigned int plt_count)
: Output_section_data((plt_count + 1) * plt_entry_size,
plt_entry_size, false),
- layout_(layout), tlsdesc_rel_(NULL), irelative_rel_(NULL), got_(got),
+ tlsdesc_rel_(NULL), irelative_rel_(NULL), got_(got),
got_plt_(got_plt), got_irelative_(got_irelative), count_(plt_count),
irelative_count_(0), tlsdesc_got_offset_(-1U), free_list_()
{
@@ -268,9 +299,6 @@ class Output_data_plt_x86_64 : public Output_section_data
void
do_write(Output_file*);
- // A pointer to the Layout class, so that we can find the .dynamic
- // section when we write out the GOT PLT section.
- Layout* layout_;
// The reloc section.
Reloc_section* rel_;
// The TLSDESC relocs, if necessary. These must follow the regular
@@ -282,7 +310,7 @@ class Output_data_plt_x86_64 : public Output_section_data
// The .got section.
Output_data_got<64, false>* got_;
// The .got.plt section.
- Output_data_space* got_plt_;
+ Output_data_got_plt_x86_64* got_plt_;
// The part of the .got.plt section used for IRELATIVE relocs.
Output_data_space* got_irelative_;
// The number of PLT entries.
@@ -303,7 +331,7 @@ class Output_data_plt_x86_64_standard : public Output_data_plt_x86_64<size>
public:
Output_data_plt_x86_64_standard(Layout* layout,
Output_data_got<64, false>* got,
- Output_data_space* got_plt,
+ Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative)
: Output_data_plt_x86_64<size>(layout, plt_entry_size,
got, got_plt, got_irelative)
@@ -311,7 +339,7 @@ class Output_data_plt_x86_64_standard : public Output_data_plt_x86_64<size>
Output_data_plt_x86_64_standard(Layout* layout,
Output_data_got<64, false>* got,
- Output_data_space* got_plt,
+ Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative,
unsigned int plt_count)
: Output_data_plt_x86_64<size>(layout, plt_entry_size,
@@ -618,7 +646,7 @@ class Target_x86_64 : public Sized_target<size, false>
Output_data_plt_x86_64<size>*
make_data_plt(Layout* layout,
Output_data_got<64, false>* got,
- Output_data_space* got_plt,
+ Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative)
{
return this->do_make_data_plt(layout, got, got_plt, got_irelative);
@@ -627,7 +655,7 @@ class Target_x86_64 : public Sized_target<size, false>
Output_data_plt_x86_64<size>*
make_data_plt(Layout* layout,
Output_data_got<64, false>* got,
- Output_data_space* got_plt,
+ Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative,
unsigned int plt_count)
{
@@ -638,7 +666,7 @@ class Target_x86_64 : public Sized_target<size, false>
virtual Output_data_plt_x86_64<size>*
do_make_data_plt(Layout* layout,
Output_data_got<64, false>* got,
- Output_data_space* got_plt,
+ Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative)
{
return new Output_data_plt_x86_64_standard<size>(layout, got, got_plt,
@@ -648,7 +676,7 @@ class Target_x86_64 : public Sized_target<size, false>
virtual Output_data_plt_x86_64<size>*
do_make_data_plt(Layout* layout,
Output_data_got<64, false>* got,
- Output_data_space* got_plt,
+ Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative,
unsigned int plt_count)
{
@@ -847,7 +875,7 @@ class Target_x86_64 : public Sized_target<size, false>
got_section(Symbol_table*, Layout*);
// Get the GOT PLT section.
- Output_data_space*
+ Output_data_got_plt_x86_64*
got_plt_section() const
{
gold_assert(this->got_plt_ != NULL);
@@ -958,7 +986,7 @@ class Target_x86_64 : public Sized_target<size, false>
// The PLT section.
Output_data_plt_x86_64<size>* plt_;
// The GOT PLT section.
- Output_data_space* got_plt_;
+ Output_data_got_plt_x86_64* got_plt_;
// The GOT section for IRELATIVE relocations.
Output_data_space* got_irelative_;
// The GOT section for TLSDESC relocations.
@@ -1074,7 +1102,7 @@ Target_x86_64<size>::got_section(Symbol_table* symtab, Layout* layout)
| elfcpp::SHF_WRITE),
this->got_, got_order, true);
- this->got_plt_ = new Output_data_space(8, "** GOT PLT");
+ this->got_plt_ = new Output_data_got_plt_x86_64(layout);
layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS,
(elfcpp::SHF_ALLOC
| elfcpp::SHF_WRITE),
@@ -1163,6 +1191,27 @@ Target_x86_64<size>::rela_irelative_section(Layout* layout)
return this->rela_irelative_;
}
+// Write the first three reserved words of the .got.plt section.
+// The remainder of the section is written while writing the PLT
+// in Output_data_plt_i386::do_write.
+
+void
+Output_data_got_plt_x86_64::do_write(Output_file* of)
+{
+ // The first entry in the GOT is the address of the .dynamic section
+ // aka the PT_DYNAMIC segment. The next two entries are reserved.
+ // We saved space for them when we created the section in
+ // Target_x86_64::got_section.
+ const off_t got_file_offset = this->offset();
+ gold_assert(this->data_size() >= 24);
+ unsigned char* const got_view = of->get_output_view(got_file_offset, 24);
+ Output_section* dynamic = this->layout_->dynamic_section();
+ uint64_t dynamic_addr = dynamic == NULL ? 0 : dynamic->address();
+ elfcpp::Swap<64, false>::writeval(got_view, dynamic_addr);
+ memset(got_view + 8, 0, 16);
+ of->write_output_view(got_file_offset, 24, got_view);
+}
+
// Initialize the PLT section.
template<int size>
@@ -1198,7 +1247,7 @@ Output_data_plt_x86_64<size>::add_entry(Symbol_table* symtab, Layout* layout,
unsigned int* pcount;
unsigned int offset;
unsigned int reserved;
- Output_data_space* got;
+ Output_section_data_build* got;
if (gsym->type() == elfcpp::STT_GNU_IFUNC
&& gsym->can_use_relative_reloc(false))
{
@@ -1605,18 +1654,9 @@ Output_data_plt_x86_64<size>::do_write(Output_file* of)
this->fill_first_plt_entry(pov, got_address, plt_address);
pov += this->get_plt_entry_size();
- unsigned char* got_pov = got_view;
-
- // The first entry in the GOT is the address of the .dynamic section
- // aka the PT_DYNAMIC segment. The next two entries are reserved.
- // We saved space for them when we created the section in
- // Target_x86_64::got_section.
- Output_section* dynamic = this->layout_->dynamic_section();
- uint32_t dynamic_addr = dynamic == NULL ? 0 : dynamic->address();
- elfcpp::Swap<64, false>::writeval(got_pov, dynamic_addr);
- got_pov += 8;
- memset(got_pov, 0, 16);
- got_pov += 16;
+ // The first three entries in the GOT are reserved, and are written
+ // by Output_data_got_plt_x86_64::do_write.
+ unsigned char* got_pov = got_view + 24;
unsigned int plt_offset = this->get_plt_entry_size();
unsigned int got_offset = 24;
@@ -1777,7 +1817,7 @@ Target_x86_64<size>::init_got_plt_for_update(Symbol_table* symtab,
true);
// Add the three reserved entries.
- this->got_plt_ = new Output_data_space((plt_count + 3) * 8, 8, "** GOT PLT");
+ this->got_plt_ = new Output_data_got_plt_x86_64(layout, (plt_count + 3) * 8);
layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS,
(elfcpp::SHF_ALLOC
| elfcpp::SHF_WRITE),
@@ -4500,7 +4540,7 @@ class Output_data_plt_x86_64_nacl : public Output_data_plt_x86_64<size>
public:
Output_data_plt_x86_64_nacl(Layout* layout,
Output_data_got<64, false>* got,
- Output_data_space* got_plt,
+ Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative)
: Output_data_plt_x86_64<size>(layout, plt_entry_size,
got, got_plt, got_irelative)
@@ -4508,7 +4548,7 @@ class Output_data_plt_x86_64_nacl : public Output_data_plt_x86_64<size>
Output_data_plt_x86_64_nacl(Layout* layout,
Output_data_got<64, false>* got,
- Output_data_space* got_plt,
+ Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative,
unsigned int plt_count)
: Output_data_plt_x86_64<size>(layout, plt_entry_size,
@@ -4581,7 +4621,7 @@ class Target_x86_64_nacl : public Target_x86_64<size>
virtual Output_data_plt_x86_64<size>*
do_make_data_plt(Layout* layout,
Output_data_got<64, false>* got,
- Output_data_space* got_plt,
+ Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative)
{
return new Output_data_plt_x86_64_nacl<size>(layout, got, got_plt,
@@ -4591,7 +4631,7 @@ class Target_x86_64_nacl : public Target_x86_64<size>
virtual Output_data_plt_x86_64<size>*
do_make_data_plt(Layout* layout,
Output_data_got<64, false>* got,
- Output_data_space* got_plt,
+ Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative,
unsigned int plt_count)
{