// i386.cc -- i386 target support for gold.
-// Copyright 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
+// Copyright 2006, 2007, 2008, 2009, 2010, 2011, 2012
+// Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.
// This file is part of gold.
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
this->got_ = new Output_data_got<32, false>();
+ // When using -z now, we can treat .got.plt as a relro section.
+ // Without -z now, it is modified after program startup by lazy
+ // PLT relocations.
+ bool is_got_plt_relro = parameters->options().now();
+ Output_section_order got_order = (is_got_plt_relro
+ ? ORDER_RELRO
+ : ORDER_RELRO_LAST);
+ Output_section_order got_plt_order = (is_got_plt_relro
+ ? ORDER_RELRO
+ : ORDER_NON_RELRO_FIRST);
+
layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
(elfcpp::SHF_ALLOC
| elfcpp::SHF_WRITE),
- this->got_, ORDER_RELRO_LAST, true);
+ this->got_, got_order, true);
this->got_plt_ = new Output_data_space(4, "** GOT PLT");
layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS,
(elfcpp::SHF_ALLOC
| elfcpp::SHF_WRITE),
- this->got_plt_, ORDER_NON_RELRO_FIRST,
- false);
+ this->got_plt_, got_plt_order,
+ is_got_plt_relro);
// The first three entries are reserved.
this->got_plt_->set_current_data_size(3 * 4);
- // Those bytes can go into the relro segment.
- layout->increase_relro(3 * 4);
+ if (!is_got_plt_relro)
+ {
+ // Those bytes can go into the relro segment.
+ layout->increase_relro(3 * 4);
+ }
// Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT.
this->global_offset_table_ =
(elfcpp::SHF_ALLOC
| elfcpp::SHF_WRITE),
this->got_irelative_,
- ORDER_NON_RELRO_FIRST, false);
+ got_plt_order, is_got_plt_relro);
// If there are any TLSDESC relocations, they get GOT entries in
// .got.plt after the jump slot entries.
(elfcpp::SHF_ALLOC
| elfcpp::SHF_WRITE),
this->got_tlsdesc_,
- ORDER_NON_RELRO_FIRST, false);
+ got_plt_order, is_got_plt_relro);
}
return this->got_;
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,
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;
// If this symbol is not fully resolved, we need to add a
// GOT entry with a dynamic relocation.
Reloc_section* rel_dyn = target->rel_dyn_section(layout);
+
+ // Use a GLOB_DAT rather than a RELATIVE reloc if:
+ //
+ // 1) The symbol may be defined in some other module.
+ //
+ // 2) We are building a shared library and this is a
+ // protected symbol; using GLOB_DAT means that the dynamic
+ // linker can use the address of the PLT in the main
+ // executable when appropriate so that function address
+ // comparisons work.
+ //
+ // 3) This is a STT_GNU_IFUNC symbol in position dependent
+ // code, again so that function address comparisons work.
if (gsym->is_from_dynobj()
|| gsym->is_undefined()
|| gsym->is_preemptible()
+ || (gsym->visibility() == elfcpp::STV_PROTECTED
+ && parameters->options().shared())
|| (gsym->type() == elfcpp::STT_GNU_IFUNC
&& parameters->options().output_is_position_independent()))
got->add_global_with_rel(gsym, GOT_TYPE_STANDARD,
}
if (optimized_type == tls::TLSOPT_TO_IE)
{
- if (tls_segment == NULL)
- {
- gold_assert(parameters->errors()->error_count() > 0
- || issue_undefined_symbol_error(gsym));
- return;
- }
this->tls_gd_to_ie(relinfo, relnum, tls_segment, rel, r_type,
got_offset, view, view_size);
break;
jmp[0] = 0xe9;
elfcpp::Swap_unaligned<32, false>::writeval(jmp + 1, length - 5);
return (std::string(reinterpret_cast<char*>(&jmp[0]), 5)
- + std::string(length - 5, '\0'));
+ + std::string(length - 5, static_cast<char>(0x90)));
}
// Nop sequences of various lengths.
- const char nop1[1] = { 0x90 }; // nop
- const char nop2[2] = { 0x66, 0x90 }; // xchg %ax %ax
- const char nop3[3] = { 0x8d, 0x76, 0x00 }; // leal 0(%esi),%esi
- const char nop4[4] = { 0x8d, 0x74, 0x26, 0x00}; // leal 0(%esi,1),%esi
- const char nop5[5] = { 0x90, 0x8d, 0x74, 0x26, // nop
- 0x00 }; // leal 0(%esi,1),%esi
- const char nop6[6] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
- 0x00, 0x00 };
- const char nop7[7] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
- 0x00, 0x00, 0x00 };
- const char nop8[8] = { 0x90, 0x8d, 0xb4, 0x26, // nop
- 0x00, 0x00, 0x00, 0x00 }; // leal 0L(%esi,1),%esi
- const char nop9[9] = { 0x89, 0xf6, 0x8d, 0xbc, // movl %esi,%esi
- 0x27, 0x00, 0x00, 0x00, // leal 0L(%edi,1),%edi
- 0x00 };
- const char nop10[10] = { 0x8d, 0x76, 0x00, 0x8d, // leal 0(%esi),%esi
- 0xbc, 0x27, 0x00, 0x00, // leal 0L(%edi,1),%edi
- 0x00, 0x00 };
- const char nop11[11] = { 0x8d, 0x74, 0x26, 0x00, // leal 0(%esi,1),%esi
- 0x8d, 0xbc, 0x27, 0x00, // leal 0L(%edi,1),%edi
- 0x00, 0x00, 0x00 };
- const char nop12[12] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
- 0x00, 0x00, 0x8d, 0xbf, // leal 0L(%edi),%edi
- 0x00, 0x00, 0x00, 0x00 };
- const char nop13[13] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
- 0x00, 0x00, 0x8d, 0xbc, // leal 0L(%edi,1),%edi
- 0x27, 0x00, 0x00, 0x00,
- 0x00 };
- const char nop14[14] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
- 0x00, 0x00, 0x00, 0x8d, // leal 0L(%edi,1),%edi
- 0xbc, 0x27, 0x00, 0x00,
- 0x00, 0x00 };
- const char nop15[15] = { 0xeb, 0x0d, 0x90, 0x90, // jmp .+15
- 0x90, 0x90, 0x90, 0x90, // nop,nop,nop,...
- 0x90, 0x90, 0x90, 0x90,
- 0x90, 0x90, 0x90 };
+ const char nop1[1] = { '\x90' }; // nop
+ const char nop2[2] = { '\x66', '\x90' }; // xchg %ax %ax
+ const char nop3[3] = { '\x8d', '\x76', '\x00' }; // leal 0(%esi),%esi
+ const char nop4[4] = { '\x8d', '\x74', '\x26', // leal 0(%esi,1),%esi
+ '\x00'};
+ const char nop5[5] = { '\x90', '\x8d', '\x74', // nop
+ '\x26', '\x00' }; // leal 0(%esi,1),%esi
+ const char nop6[6] = { '\x8d', '\xb6', '\x00', // leal 0L(%esi),%esi
+ '\x00', '\x00', '\x00' };
+ const char nop7[7] = { '\x8d', '\xb4', '\x26', // leal 0L(%esi,1),%esi
+ '\x00', '\x00', '\x00',
+ '\x00' };
+ const char nop8[8] = { '\x90', '\x8d', '\xb4', // nop
+ '\x26', '\x00', '\x00', // leal 0L(%esi,1),%esi
+ '\x00', '\x00' };
+ const char nop9[9] = { '\x89', '\xf6', '\x8d', // movl %esi,%esi
+ '\xbc', '\x27', '\x00', // leal 0L(%edi,1),%edi
+ '\x00', '\x00', '\x00' };
+ const char nop10[10] = { '\x8d', '\x76', '\x00', // leal 0(%esi),%esi
+ '\x8d', '\xbc', '\x27', // leal 0L(%edi,1),%edi
+ '\x00', '\x00', '\x00',
+ '\x00' };
+ const char nop11[11] = { '\x8d', '\x74', '\x26', // leal 0(%esi,1),%esi
+ '\x00', '\x8d', '\xbc', // leal 0L(%edi,1),%edi
+ '\x27', '\x00', '\x00',
+ '\x00', '\x00' };
+ const char nop12[12] = { '\x8d', '\xb6', '\x00', // leal 0L(%esi),%esi
+ '\x00', '\x00', '\x00', // leal 0L(%edi),%edi
+ '\x8d', '\xbf', '\x00',
+ '\x00', '\x00', '\x00' };
+ const char nop13[13] = { '\x8d', '\xb6', '\x00', // leal 0L(%esi),%esi
+ '\x00', '\x00', '\x00', // leal 0L(%edi,1),%edi
+ '\x8d', '\xbc', '\x27',
+ '\x00', '\x00', '\x00',
+ '\x00' };
+ const char nop14[14] = { '\x8d', '\xb4', '\x26', // leal 0L(%esi,1),%esi
+ '\x00', '\x00', '\x00', // leal 0L(%edi,1),%edi
+ '\x00', '\x8d', '\xbc',
+ '\x27', '\x00', '\x00',
+ '\x00', '\x00' };
+ const char nop15[15] = { '\xeb', '\x0d', '\x90', // jmp .+15
+ '\x90', '\x90', '\x90', // nop,nop,nop,...
+ '\x90', '\x90', '\x90',
+ '\x90', '\x90', '\x90',
+ '\x90', '\x90', '\x90' };
const char* nops[16] = {
NULL,
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