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gold patch committed: Initialize first .got.plt entry
- From: Ian Lance Taylor <iant at google dot com>
- To: binutils at sourceware dot org
- Date: Fri, 15 Jul 2011 08:31:56 -0700
- Subject: gold patch committed: Initialize first .got.plt entry
I somehow managed to overlook the x86/x86_64 ELF ABI requirement that
the first entry in the .got.plt section hold the unrelocated address of
the .dynamic section. I got away with it because the only program which
cares is the dynamic linker itself. This patch fixes the problem.
Committed to mainline.
Ian
2011-07-15 Ian Lance Taylor <iant@google.com>
* i386.cc (class Output_data_plt_i386): Add layout_ field.
(Output_data_plt_i386::Output_data_plt_i386): Initialize layout_.
(Output_data_plt_i386::do_write): Write address of .dynamic
section to first entry in .got.plt section.
* x86_64.cc (class Output_data_plt_x86_64): Add layout_ field.
(Output_data_plt_x86_64::Output_data_plt_x86_64) [both versions]:
Initialize layout_.
(Output_data_plt_x86_64::do_write): Write address of .dynamic
section to first entry in .got.plt section.
* layout.h (Layout::dynamic_section): New function.
Index: i386.cc
===================================================================
RCS file: /cvs/src/src/gold/i386.cc,v
retrieving revision 1.140
diff -u -p -r1.140 i386.cc
--- i386.cc 13 Jul 2011 22:47:07 -0000 1.140
+++ i386.cc 15 Jul 2011 15:16:43 -0000
@@ -166,6 +166,9 @@ class Output_data_plt_i386 : public Outp
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
@@ -822,9 +825,9 @@ Target_i386::rel_irelative_section(Layou
Output_data_plt_i386::Output_data_plt_i386(Layout* layout,
Output_data_space* got_plt,
Output_data_space* got_irelative)
- : Output_section_data(16), tls_desc_rel_(NULL), irelative_rel_(NULL),
- got_plt_(got_plt), got_irelative_(got_irelative), count_(0),
- irelative_count_(0), global_ifuncs_(), local_ifuncs_()
+ : Output_section_data(16), 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_()
{
this->rel_ = new Reloc_section(false);
layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL,
@@ -1138,8 +1141,16 @@ Output_data_plt_i386::do_write(Output_fi
unsigned char* got_pov = got_view;
- memset(got_pov, 0, 12);
- got_pov += 12;
+ // 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;
const int rel_size = elfcpp::Elf_sizes<32>::rel_size;
Index: layout.h
===================================================================
RCS file: /cvs/src/src/gold/layout.h,v
retrieving revision 1.98
diff -u -p -r1.98 layout.h
--- layout.h 14 Jul 2011 00:55:17 -0000 1.98
+++ layout.h 15 Jul 2011 15:16:43 -0000
@@ -627,6 +627,12 @@ class Layout
dynpool() const
{ return &this->dynpool_; }
+ // Return the .dynamic output section. This is only valid after the
+ // layout has been finalized.
+ Output_section*
+ dynamic_section() const
+ { return this->dynamic_section_; }
+
// Return the symtab_xindex section used to hold large section
// indexes for the normal symbol table.
Output_symtab_xindex*
Index: x86_64.cc
===================================================================
RCS file: /cvs/src/src/gold/x86_64.cc,v
retrieving revision 1.138
diff -u -p -r1.138 x86_64.cc
--- x86_64.cc 13 Jul 2011 22:47:07 -0000 1.138
+++ x86_64.cc 15 Jul 2011 15:16:43 -0000
@@ -57,9 +57,10 @@ class Output_data_plt_x86_64 : public Ou
Output_data_plt_x86_64(Layout* layout, Output_data_got<64, false>* got,
Output_data_space* got_plt,
Output_data_space* got_irelative)
- : Output_section_data(16), 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_()
+ : Output_section_data(16), layout_(layout), 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_()
{ this->init(layout); }
Output_data_plt_x86_64(Layout* layout, Output_data_got<64, false>* got,
@@ -67,9 +68,9 @@ class Output_data_plt_x86_64 : public Ou
Output_data_space* got_irelative,
unsigned int plt_count)
: Output_section_data((plt_count + 1) * plt_entry_size, 16, false),
- 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_()
+ layout_(layout), 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_()
{
this->init(layout);
@@ -205,6 +206,9 @@ class Output_data_plt_x86_64 : public Ou
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
@@ -1306,8 +1310,16 @@ Output_data_plt_x86_64::do_write(Output_
unsigned char* got_pov = got_view;
- memset(got_pov, 0, 24);
- got_pov += 24;
+ // 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<64, false>::writeval(got_pov, dynamic_addr);
+ got_pov += 8;
+ memset(got_pov, 0, 16);
+ got_pov += 16;
unsigned int plt_offset = plt_entry_size;
unsigned int got_offset = 24;