diff options
Diffstat (limited to 'gold/i386.cc')
| -rw-r--r-- | gold/i386.cc | 1517 |
1 files changed, 1517 insertions, 0 deletions
diff --git a/gold/i386.cc b/gold/i386.cc new file mode 100644 index 000000000000..448453aa3495 --- /dev/null +++ b/gold/i386.cc @@ -0,0 +1,1517 @@ +// i386.cc -- i386 target support for gold. + +#include "gold.h" + +#include <cstring> + +#include "elfcpp.h" +#include "reloc.h" +#include "i386.h" +#include "object.h" +#include "symtab.h" +#include "layout.h" +#include "output.h" +#include "target.h" +#include "target-reloc.h" +#include "target-select.h" + +namespace +{ + +using namespace gold; + +class Output_data_plt_i386; + +// The i386 target class. + +class Target_i386 : public Sized_target<32, false> +{ + public: + typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section; + + Target_i386() + : Sized_target<32, false>(&i386_info), + got_(NULL), plt_(NULL), got_plt_(NULL), rel_dyn_(NULL), + copy_relocs_(NULL), dynbss_(NULL) + { } + + // Scan the relocations to look for symbol adjustments. + void + scan_relocs(const General_options& options, + Symbol_table* symtab, + Layout* layout, + Sized_relobj<32, false>* object, + unsigned int data_shndx, + unsigned int sh_type, + const unsigned char* prelocs, + size_t reloc_count, + size_t local_symbol_count, + const unsigned char* plocal_symbols, + Symbol** global_symbols); + + // Finalize the sections. + void + do_finalize_sections(const General_options*, Layout*); + + // Relocate a section. + void + relocate_section(const Relocate_info<32, false>*, + unsigned int sh_type, + const unsigned char* prelocs, + size_t reloc_count, + unsigned char* view, + elfcpp::Elf_types<32>::Elf_Addr view_address, + off_t view_size); + + private: + // The class which scans relocations. + struct Scan + { + inline void + local(const General_options& options, Symbol_table* symtab, + Layout* layout, Target_i386* target, + Sized_relobj<32, false>* object, + unsigned int data_shndx, + const elfcpp::Rel<32, false>& reloc, unsigned int r_type, + const elfcpp::Sym<32, false>& lsym); + + inline void + global(const General_options& options, Symbol_table* symtab, + Layout* layout, Target_i386* target, + Sized_relobj<32, false>* object, + unsigned int data_shndx, + const elfcpp::Rel<32, false>& reloc, unsigned int r_type, + Symbol* gsym); + }; + + // The class which implements relocation. + class Relocate + { + public: + Relocate() + : skip_call_tls_get_addr_(false) + { } + + ~Relocate() + { + if (this->skip_call_tls_get_addr_) + { + // FIXME: This needs to specify the location somehow. + fprintf(stderr, _("%s: missing expected TLS relocation\n"), + program_name); + gold_exit(false); + } + } + + // Do a relocation. Return false if the caller should not issue + // any warnings about this relocation. + inline bool + relocate(const Relocate_info<32, false>*, Target_i386*, size_t relnum, + const elfcpp::Rel<32, false>&, + unsigned int r_type, const Sized_symbol<32>*, + const Symbol_value<32>*, + unsigned char*, elfcpp::Elf_types<32>::Elf_Addr, + off_t); + + private: + // Do a TLS relocation. + inline void + relocate_tls(const Relocate_info<32, false>*, size_t relnum, + const elfcpp::Rel<32, false>&, + unsigned int r_type, const Sized_symbol<32>*, + const Symbol_value<32>*, + unsigned char*, elfcpp::Elf_types<32>::Elf_Addr, off_t); + + // Do a TLS Initial-Exec to Local-Exec transition. + static inline void + tls_ie_to_le(const Relocate_info<32, false>*, size_t relnum, + Output_segment* tls_segment, + const elfcpp::Rel<32, false>&, unsigned int r_type, + elfcpp::Elf_types<32>::Elf_Addr value, + unsigned char* view, + off_t view_size); + + // Do a TLS Global-Dynamic to Local-Exec transition. + inline void + tls_gd_to_le(const Relocate_info<32, false>*, size_t relnum, + Output_segment* tls_segment, + const elfcpp::Rel<32, false>&, unsigned int r_type, + elfcpp::Elf_types<32>::Elf_Addr value, + unsigned char* view, + off_t view_size); + + // Check the range for a TLS relocation. + static inline void + check_range(const Relocate_info<32, false>*, size_t relnum, + const elfcpp::Rel<32, false>&, off_t, off_t); + + // Check the validity of a TLS relocation. This is like assert. + static inline void + check_tls(const Relocate_info<32, false>*, size_t relnum, + const elfcpp::Rel<32, false>&, bool); + + // This is set if we should skip the next reloc, which should be a + // PLT32 reloc against ___tls_get_addr. + bool skip_call_tls_get_addr_; + }; + + // Adjust TLS relocation type based on the options and whether this + // is a local symbol. + static unsigned int + optimize_tls_reloc(const General_options*, bool is_final, int r_type); + + // Get the GOT section, creating it if necessary. + Output_data_got<32, false>* + got_section(const General_options*, Symbol_table*, Layout*); + + // Create a PLT entry for a global symbol. + void + make_plt_entry(const General_options* options, Symbol_table*, + Layout*, Symbol*); + + // Get the PLT section. + Output_data_plt_i386* + plt_section() const + { + gold_assert(this->plt_ != NULL); + return this->plt_; + } + + // Get the dynamic reloc section, creating it if necessary. + Reloc_section* + rel_dyn_section(Layout*); + + // Copy a relocation against a global symbol. + void + copy_reloc(const General_options*, Symbol_table*, Layout*, + Sized_relobj<32, false>*, unsigned int, + Symbol*, const elfcpp::Rel<32, false>&); + + // Information about this specific target which we pass to the + // general Target structure. + static const Target::Target_info i386_info; + + // The GOT section. + Output_data_got<32, false>* got_; + // The PLT section. + Output_data_plt_i386* plt_; + // The GOT PLT section. + Output_data_space* got_plt_; + // The dynamic reloc section. + Reloc_section* rel_dyn_; + // Relocs saved to avoid a COPY reloc. + Copy_relocs<32, false>* copy_relocs_; + // Space for variables copied with a COPY reloc. + Output_data_space* dynbss_; +}; + +const Target::Target_info Target_i386::i386_info = +{ + 32, // size + false, // is_big_endian + elfcpp::EM_386, // machine_code + false, // has_make_symbol + false, // has_resolve + "/usr/lib/libc.so.1", // dynamic_linker + 0x08048000, // text_segment_address + 0x1000, // abi_pagesize + 0x1000 // common_pagesize +}; + +// Get the GOT section, creating it if necessary. + +Output_data_got<32, false>* +Target_i386::got_section(const General_options* options, Symbol_table* symtab, + Layout* layout) +{ + if (this->got_ == NULL) + { + gold_assert(options != NULL && symtab != NULL && layout != NULL); + + this->got_ = new Output_data_got<32, false>(options); + + layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS, + elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE, + this->got_); + + // The old GNU linker creates a .got.plt section. We just + // create another set of data in the .got section. Note that we + // always create a PLT if we create a GOT, although the PLT + // might be empty. + this->got_plt_ = new Output_data_space(4); + layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS, + elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE, + this->got_plt_); + + // The first three entries are reserved. + this->got_plt_->set_space_size(3 * 4); + + // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT. + symtab->define_in_output_data(this, "_GLOBAL_OFFSET_TABLE_", NULL, + this->got_plt_, + 0, 0, elfcpp::STT_OBJECT, + elfcpp::STB_LOCAL, + elfcpp::STV_HIDDEN, 0, + false, false); + } + + return this->got_; +} + +// Get the dynamic reloc section, creating it if necessary. + +Target_i386::Reloc_section* +Target_i386::rel_dyn_section(Layout* layout) +{ + if (this->rel_dyn_ == NULL) + { + gold_assert(layout != NULL); + this->rel_dyn_ = new Reloc_section(); + layout->add_output_section_data(".rel.dyn", elfcpp::SHT_REL, + elfcpp::SHF_ALLOC, this->rel_dyn_); + } + return this->rel_dyn_; +} + +// A class to handle the PLT data. + +class Output_data_plt_i386 : public Output_section_data +{ + public: + typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section; + + Output_data_plt_i386(Layout*, Output_data_space*, bool is_shared); + + // Add an entry to the PLT. + void + add_entry(Symbol* gsym); + + // Return the .rel.plt section data. + const Reloc_section* + rel_plt() const + { return this->rel_; } + + protected: + void + do_adjust_output_section(Output_section* os); + + private: + // The size of an entry in the PLT. + static const int plt_entry_size = 16; + + // The first entry in the PLT for an executable. + static unsigned char exec_first_plt_entry[plt_entry_size]; + + // The first entry in the PLT for a shared object. + static unsigned char dyn_first_plt_entry[plt_entry_size]; + + // Other entries in the PLT for an executable. + static unsigned char exec_plt_entry[plt_entry_size]; + + // Other entries in the PLT for a shared object. + static unsigned char dyn_plt_entry[plt_entry_size]; + + // Set the final size. + void + do_set_address(uint64_t, off_t) + { this->set_data_size((this->count_ + 1) * plt_entry_size); } + + // Write out the PLT data. + void + do_write(Output_file*); + + // The reloc section. + Reloc_section* rel_; + // The .got.plt section. + Output_data_space* got_plt_; + // The number of PLT entries. + unsigned int count_; + // Whether we are generated a shared object. + bool is_shared_; +}; + +// 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, + Output_data_space* got_plt, + bool is_shared) + : Output_section_data(4), got_plt_(got_plt), is_shared_(is_shared) +{ + this->rel_ = new Reloc_section(); + layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL, + elfcpp::SHF_ALLOC, this->rel_); +} + +// For some reason + +void +Output_data_plt_i386::do_adjust_output_section(Output_section* os) +{ + // UnixWare sets the entsize of .plt to 4, and so does the old GNU + // linker, and so do we. + os->set_entsize(4); +} + +// Add an entry to the PLT. + +void +Output_data_plt_i386::add_entry(Symbol* gsym) +{ + gold_assert(!gsym->has_plt_offset()); + + // Note that when setting the PLT offset we skip the initial + // reserved PLT entry. + gsym->set_plt_offset((this->count_ + 1) * plt_entry_size); + + ++this->count_; + + off_t got_offset = this->got_plt_->data_size(); + + // Every PLT entry needs a GOT entry which points back to the PLT + // entry (this will be changed by the dynamic linker, normally + // lazily when the function is called). + this->got_plt_->set_space_size(got_offset + 4); + + // Every PLT entry needs a reloc. + gsym->set_needs_dynsym_entry(); + this->rel_->add_global(gsym, elfcpp::R_386_JUMP_SLOT, this->got_plt_, + got_offset); + + // Note that we don't need to save the symbol. The contents of the + // PLT are independent of which symbols are used. The symbols only + // appear in the relocations. +} + +// The first entry in the PLT for an executable. + +unsigned char Output_data_plt_i386::exec_first_plt_entry[plt_entry_size] = +{ + 0xff, 0x35, // pushl contents of memory address + 0, 0, 0, 0, // replaced with address of .got + 4 + 0xff, 0x25, // jmp indirect + 0, 0, 0, 0, // replaced with address of .got + 8 + 0, 0, 0, 0 // unused +}; + +// The first entry in the PLT for a shared object. + +unsigned char Output_data_plt_i386::dyn_first_plt_entry[plt_entry_size] = +{ + 0xff, 0xb3, 4, 0, 0, 0, // pushl 4(%ebx) + 0xff, 0xa3, 8, 0, 0, 0, // jmp *8(%ebx) + 0, 0, 0, 0 // unused +}; + +// Subsequent entries in the PLT for an executable. + +unsigned char Output_data_plt_i386::exec_plt_entry[plt_entry_size] = +{ + 0xff, 0x25, // jmp indirect + 0, 0, 0, 0, // replaced with address of symbol in .got + 0x68, // pushl immediate + 0, 0, 0, 0, // replaced with offset into relocation table + 0xe9, // jmp relative + 0, 0, 0, 0 // replaced with offset to start of .plt +}; + +// Subsequent entries in the PLT for a shared object. + +unsigned char Output_data_plt_i386::dyn_plt_entry[plt_entry_size] = +{ + 0xff, 0xa3, // jmp *offset(%ebx) + 0, 0, 0, 0, // replaced with offset of symbol in .got + 0x68, // pushl immediate + 0, 0, 0, 0, // replaced with offset into relocation table + 0xe9, // jmp relative + 0, 0, 0, 0 // replaced with offset to start of .plt +}; + +// Write out the PLT. This uses the hand-coded instructions above, +// and adjusts them as needed. This is all specified by the i386 ELF +// Processor Supplement. + +void +Output_data_plt_i386::do_write(Output_file* of) +{ + const off_t offset = this->offset(); + const off_t oview_size = this->data_size(); + unsigned char* const oview = of->get_output_view(offset, oview_size); + + const off_t got_file_offset = this->got_plt_->offset(); + const off_t got_size = this->got_plt_->data_size(); + unsigned char* const got_view = of->get_output_view(got_file_offset, + got_size); + + unsigned char* pov = oview; + + elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address(); + elfcpp::Elf_types<32>::Elf_Addr got_address = this->got_plt_->address(); + + if (this->is_shared_) + memcpy(pov, dyn_first_plt_entry, plt_entry_size); + else + { + memcpy(pov, exec_first_plt_entry, plt_entry_size); + elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 4); + elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 8); + } + pov += plt_entry_size; + + unsigned char* got_pov = got_view; + + memset(got_pov, 0, 12); + got_pov += 12; + + const int rel_size = elfcpp::Elf_sizes<32>::rel_size; + + unsigned int plt_offset = plt_entry_size; + unsigned int plt_rel_offset = 0; + unsigned int got_offset = 12; + const unsigned int count = this->count_; + for (unsigned int i = 0; + i < count; + ++i, + pov += plt_entry_size, + got_pov += 4, + plt_offset += plt_entry_size, + plt_rel_offset += rel_size, + got_offset += 4) + { + // Set and adjust the PLT entry itself. + + if (this->is_shared_) + { + memcpy(pov, dyn_plt_entry, plt_entry_size); + elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset); + } + else + { + memcpy(pov, exec_plt_entry, plt_entry_size); + elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, + (got_address + + got_offset)); + } + + elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_rel_offset); + elfcpp::Swap<32, false>::writeval(pov + 12, + - (plt_offset + plt_entry_size)); + + // Set the entry in the GOT. + elfcpp::Swap<32, false>::writeval(got_pov, plt_address + plt_offset + 6); + } + + gold_assert(pov - oview == oview_size); + gold_assert(got_pov - got_view == got_size); + + of->write_output_view(offset, oview_size, oview); + of->write_output_view(got_file_offset, got_size, got_view); +} + +// Create a PLT entry for a global symbol. + +void +Target_i386::make_plt_entry(const General_options* options, + Symbol_table* symtab, Layout* layout, Symbol* gsym) +{ + if (gsym->has_plt_offset()) + return; + + if (this->plt_ == NULL) + { + // Create the GOT sections first. + this->got_section(options, symtab, layout); + + this->plt_ = new Output_data_plt_i386(layout, this->got_plt_, + options->is_shared()); + layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS, + (elfcpp::SHF_ALLOC + | elfcpp::SHF_EXECINSTR), + this->plt_); + } + + this->plt_->add_entry(gsym); +} + +// Handle a relocation against a non-function symbol defined in a +// dynamic object. The traditional way to handle this is to generate +// a COPY relocation to copy the variable at runtime from the shared +// object into the executable's data segment. However, this is +// undesirable in general, as if the size of the object changes in the +// dynamic object, the executable will no longer work correctly. If +// this relocation is in a writable section, then we can create a +// dynamic reloc and the dynamic linker will resolve it to the correct +// address at runtime. However, we do not want do that if the +// relocation is in a read-only section, as it would prevent the +// readonly segment from being shared. And if we have to eventually +// generate a COPY reloc, then any dynamic relocations will be +// useless. So this means that if this is a writable section, we need +// to save the relocation until we see whether we have to create a +// COPY relocation for this symbol for any other relocation. + +void +Target_i386::copy_reloc(const General_options* options, + Symbol_table* symtab, + Layout* layout, + Sized_relobj<32, false>* object, + unsigned int data_shndx, Symbol* gsym, + const elfcpp::Rel<32, false>& rel) +{ + Sized_symbol<32>* ssym; + ssym = symtab->get_sized_symbol SELECT_SIZE_NAME(32) (gsym + SELECT_SIZE(32)); + + if (!Copy_relocs<32, false>::need_copy_reloc(options, object, + data_shndx, ssym)) + { + // So far we do not need a COPY reloc. Save this relocation. + // If it turns out that we never need a COPY reloc for this + // symbol, then we will emit the relocation. + if (this->copy_relocs_ == NULL) + this->copy_relocs_ = new Copy_relocs<32, false>(); + this->copy_relocs_->save(ssym, object, data_shndx, rel); + } + else + { + // Allocate space for this symbol in the .bss section. + + elfcpp::Elf_types<32>::Elf_WXword symsize = ssym->symsize(); + + // There is no defined way to determine the required alignment + // of the symbol. We pick the alignment based on the size. We + // set an arbitrary maximum of 256. + unsigned int align; + for (align = 1; align < 512; align <<= 1) + if ((symsize & align) != 0) + break; + + if (this->dynbss_ == NULL) + { + this->dynbss_ = new Output_data_space(align); + layout->add_output_section_data(".bss", + elfcpp::SHT_NOBITS, + (elfcpp::SHF_ALLOC + | elfcpp::SHF_WRITE), + this->dynbss_); + } + + Output_data_space* dynbss = this->dynbss_; + + if (align > dynbss->addralign()) + dynbss->set_space_alignment(align); + + off_t dynbss_size = dynbss->data_size(); + dynbss_size = align_address(dynbss_size, align); + off_t offset = dynbss_size; + dynbss->set_space_size(dynbss_size + symsize); + + // Define the symbol in the .dynbss section. + symtab->define_in_output_data(this, ssym->name(), ssym->version(), + dynbss, offset, symsize, ssym->type(), + ssym->binding(), ssym->visibility(), + ssym->nonvis(), false, false); + + // Add the COPY reloc. + ssym->set_needs_dynsym_entry(); + Reloc_section* rel_dyn = this->rel_dyn_section(layout); + rel_dyn->add_global(ssym, elfcpp::R_386_COPY, dynbss, offset); + } +} + +// Optimize the TLS relocation type based on what we know about the +// symbol. IS_FINAL is true if the final address of this symbol is +// known at link time. + +unsigned int +Target_i386::optimize_tls_reloc(const General_options* options, + bool is_final, + int r_type) +{ + // If we are generating a shared library, then we can't do anything + // in the linker. + if (options->is_shared()) + return r_type; + + switch (r_type) + { + case elfcpp::R_386_TLS_GD: + case elfcpp::R_386_TLS_GOTDESC: + case elfcpp::R_386_TLS_DESC_CALL: + // These are Global-Dynamic which permits fully general TLS + // access. Since we know that we are generating an executable, + // we can convert this to Initial-Exec. If we also know that + // this is a local symbol, we can further switch to Local-Exec. + if (is_final) + return elfcpp::R_386_TLS_LE_32; + return elfcpp::R_386_TLS_IE_32; + + case elfcpp::R_386_TLS_LDM: + // This is Local-Dynamic, which refers to a local symbol in the + // dynamic TLS block. Since we know that we generating an + // executable, we can switch to Local-Exec. + return elfcpp::R_386_TLS_LE_32; + + case elfcpp::R_386_TLS_LDO_32: + // Another type of Local-Dynamic relocation. + return elfcpp::R_386_TLS_LE; + + case elfcpp::R_386_TLS_IE: + case elfcpp::R_386_TLS_GOTIE: + case elfcpp::R_386_TLS_IE_32: + // These are Initial-Exec relocs which get the thread offset + // from the GOT. If we know that we are linking against the + // local symbol, we can switch to Local-Exec, which links the + // thread offset into the instruction. + if (is_final) + return elfcpp::R_386_TLS_LE_32; + return r_type; + + case elfcpp::R_386_TLS_LE: + case elfcpp::R_386_TLS_LE_32: + // When we already have Local-Exec, there is nothing further we + // can do. + return r_type; + + default: + gold_unreachable(); + } +} + +// Scan a relocation for a local symbol. + +inline void +Target_i386::Scan::local(const General_options& options, + Symbol_table* symtab, + Layout* layout, + Target_i386* target, + Sized_relobj<32, false>* object, + unsigned int, + const elfcpp::Rel<32, false>&, + unsigned int r_type, + const elfcpp::Sym<32, false>&) +{ + switch (r_type) + { + case elfcpp::R_386_NONE: + case elfcpp::R_386_GNU_VTINHERIT: + case elfcpp::R_386_GNU_VTENTRY: + break; + + case elfcpp::R_386_32: + case elfcpp::R_386_16: + case elfcpp::R_386_8: + // FIXME: If we are generating a shared object we need to copy + // this relocation into the object. + gold_assert(!options.is_shared()); + break; + + case elfcpp::R_386_PC32: + case elfcpp::R_386_PC16: + case elfcpp::R_386_PC8: + break; + + case elfcpp::R_386_GOTOFF: + case elfcpp::R_386_GOTPC: + // We need a GOT section. + target->got_section(&options, symtab, layout); + break; + + case elfcpp::R_386_COPY: + case elfcpp::R_386_GLOB_DAT: + case elfcpp::R_386_JUMP_SLOT: + case elfcpp::R_386_RELATIVE: + case elfcpp::R_386_TLS_TPOFF: + case elfcpp::R_386_TLS_DTPMOD32: + case elfcpp::R_386_TLS_DTPOFF32: + case elfcpp::R_386_TLS_TPOFF32: + case elfcpp::R_386_TLS_DESC: + fprintf(stderr, _("%s: %s: unexpected reloc %u in object file\n"), + program_name, object->name().c_str(), r_type); + gold_exit(false); + break; + + case elfcpp::R_386_TLS_IE: + case elfcpp::R_386_TLS_GOTIE: + case elfcpp::R_386_TLS_LE: + case elfcpp::R_386_TLS_GD: + case elfcpp::R_386_TLS_LDM: + case elfcpp::R_386_TLS_LDO_32: + case elfcpp::R_386_TLS_IE_32: + case elfcpp::R_386_TLS_LE_32: + case elfcpp::R_386_TLS_GOTDESC: + case elfcpp::R_386_TLS_DESC_CALL: + r_type = Target_i386::optimize_tls_reloc(&options, + !options.is_shared(), + r_type); + switch (r_type) + { + case elfcpp::R_386_TLS_LE: + case elfcpp::R_386_TLS_LE_32: + // FIXME: If generating a shared object, we need to copy + // this relocation into the object. + gold_assert(!options.is_shared()); + break; + + case elfcpp::R_386_TLS_IE: + case elfcpp::R_386_TLS_GOTIE: + case elfcpp::R_386_TLS_GD: + case elfcpp::R_386_TLS_LDM: + case elfcpp::R_386_TLS_LDO_32: + case elfcpp::R_386_TLS_IE_32: + case elfcpp::R_386_TLS_GOTDESC: + case elfcpp::R_386_TLS_DESC_CALL: + fprintf(stderr, + _("%s: %s: unsupported reloc %u against local symbol\n"), + program_name, object->name().c_str(), r_type); + break; + } + break; + + case elfcpp::R_386_GOT32: + case elfcpp::R_386_PLT32: + case elfcpp::R_386_32PLT: + case elfcpp::R_386_TLS_GD_32: + case elfcpp::R_386_TLS_GD_PUSH: + case elfcpp::R_386_TLS_GD_CALL: + case elfcpp::R_386_TLS_GD_POP: + case elfcpp::R_386_TLS_LDM_32: + case elfcpp::R_386_TLS_LDM_PUSH: + case elfcpp::R_386_TLS_LDM_CALL: + case elfcpp::R_386_TLS_LDM_POP: + case elfcpp::R_386_USED_BY_INTEL_200: + default: + fprintf(stderr, _("%s: %s: unsupported reloc %u against local symbol\n"), + program_name, object->name().c_str(), r_type); + break; + } +} + +// Scan a relocation for a global symbol. + +inline void +Target_i386::Scan::global(const General_options& options, + Symbol_table* symtab, + Layout* layout, + Target_i386* target, + Sized_relobj<32, false>* object, + unsigned int data_shndx, + const elfcpp::Rel<32, false>& reloc, + unsigned int r_type, + Symbol* gsym) +{ + switch (r_type) + { + case elfcpp::R_386_NONE: + case elfcpp::R_386_GNU_VTINHERIT: + case elfcpp::R_386_GNU_VTENTRY: + break; + + case elfcpp::R_386_32: + case elfcpp::R_386_PC32: + case elfcpp::R_386_16: + case elfcpp::R_386_PC16: + case elfcpp::R_386_8: + case elfcpp::R_386_PC8: + // FIXME: If we are generating a shared object we may need to + // copy this relocation into the object. If this symbol is + // defined in a shared object, we may need to copy this + // relocation in order to avoid a COPY relocation. + gold_assert(!options.is_shared()); + + if (gsym->is_from_dynobj()) + { + // This symbol is defined in a dynamic object. If it is a + // function, we make a PLT entry. Otherwise we need to + // either generate a COPY reloc or copy this reloc. + if (gsym->type() == elfcpp::STT_FUNC) + target->make_plt_entry(&options, symtab, layout, gsym); + else + target->copy_reloc(&options, symtab, layout, object, data_shndx, + gsym, reloc); + } + + break; + + case elfcpp::R_386_GOT32: + // The symbol requires a GOT entry. + if (target->got_section(&options, symtab, layout)->add_global(gsym)) + { + // If this symbol is not fully resolved, we need to add a + // dynamic relocation for it. + if (!gsym->final_value_is_known(&options)) + gold_unreachable(); + } + break; + + case elfcpp::R_386_PLT32: + // If the symbol is fully resolved, this is just a PC32 reloc. + // Otherwise we need a PLT entry. + if (gsym->final_value_is_known(&options)) + break; + target->make_plt_entry(&options, symtab, layout, gsym); + break; + + case elfcpp::R_386_GOTOFF: + case elfcpp::R_386_GOTPC: + // We need a GOT section. + target->got_section(&options, symtab, layout); + break; + + case elfcpp::R_386_COPY: + case elfcpp::R_386_GLOB_DAT: + case elfcpp::R_386_JUMP_SLOT: + case elfcpp::R_386_RELATIVE: + case elfcpp::R_386_TLS_TPOFF: + case elfcpp::R_386_TLS_DTPMOD32: + case elfcpp::R_386_TLS_DTPOFF32: + case elfcpp::R_386_TLS_TPOFF32: + case elfcpp::R_386_TLS_DESC: + fprintf(stderr, _("%s: %s: unexpected reloc %u in object file\n"), + program_name, object->name().c_str(), r_type); + gold_exit(false); + break; + + case elfcpp::R_386_TLS_IE: + case elfcpp::R_386_TLS_GOTIE: + case elfcpp::R_386_TLS_LE: + case elfcpp::R_386_TLS_GD: + case elfcpp::R_386_TLS_LDM: + case elfcpp::R_386_TLS_LDO_32: + case elfcpp::R_386_TLS_IE_32: + case elfcpp::R_386_TLS_LE_32: + case elfcpp::R_386_TLS_GOTDESC: + case elfcpp::R_386_TLS_DESC_CALL: + { + const bool is_final = gsym->final_value_is_known(&options); + r_type = Target_i386::optimize_tls_reloc(&options, is_final, r_type); + switch (r_type) + { + case elfcpp::R_386_TLS_LE: + case elfcpp::R_386_TLS_LE_32: + // FIXME: If generating a shared object, we need to copy + // this relocation into the object. + gold_assert(!options.is_shared()); + break; + + case elfcpp::R_386_TLS_IE: + case elfcpp::R_386_TLS_GOTIE: + case elfcpp::R_386_TLS_GD: + case elfcpp::R_386_TLS_LDM: + case elfcpp::R_386_TLS_LDO_32: + case elfcpp::R_386_TLS_IE_32: + case elfcpp::R_386_TLS_GOTDESC: + case elfcpp::R_386_TLS_DESC_CALL: + fprintf(stderr, + _("%s: %s: unsupported reloc %u " + "against global symbol %s\n"), + program_name, object->name().c_str(), r_type, + gsym->name()); + break; + } + } + break; + + case elfcpp::R_386_32PLT: + case elfcpp::R_386_TLS_GD_32: + case elfcpp::R_386_TLS_GD_PUSH: + case elfcpp::R_386_TLS_GD_CALL: + case elfcpp::R_386_TLS_GD_POP: + case elfcpp::R_386_TLS_LDM_32: + case elfcpp::R_386_TLS_LDM_PUSH: + case elfcpp::R_386_TLS_LDM_CALL: + case elfcpp::R_386_TLS_LDM_POP: + case elfcpp::R_386_USED_BY_INTEL_200: + default: + fprintf(stderr, + _("%s: %s: unsupported reloc %u against global symbol %s\n"), + program_name, object->name().c_str(), r_type, gsym->name()); + break; + } +} + +// Scan relocations for a section. + +void +Target_i386::scan_relocs(const General_options& options, + Symbol_table* symtab, + Layout* layout, + Sized_relobj<32, false>* object, + unsigned int data_shndx, + unsigned int sh_type, + const unsigned char* prelocs, + size_t reloc_count, + size_t local_symbol_count, + const unsigned char* plocal_symbols, + Symbol** global_symbols) +{ + if (sh_type == elfcpp::SHT_RELA) + { + fprintf(stderr, _("%s: %s: unsupported RELA reloc section\n"), + program_name, object->name().c_str()); + gold_exit(false); + } + + gold::scan_relocs<32, false, Target_i386, elfcpp::SHT_REL, + Target_i386::Scan>( + options, + symtab, + layout, + this, + object, + data_shndx, + prelocs, + reloc_count, + local_symbol_count, + plocal_symbols, + global_symbols); +} + +// Finalize the sections. + +void +Target_i386::do_finalize_sections(const General_options* options, + Layout* layout) +{ + // Fill in some more dynamic tags. + Output_data_dynamic* const odyn = layout->dynamic_data(); + if (odyn != NULL) + { + if (this->got_plt_ != NULL) + odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_); + + if (this->plt_ != NULL) + { + const Output_data* od = this->plt_->rel_plt(); + odyn->add_section_size(elfcpp::DT_PLTRELSZ, od); + odyn->add_section_address(elfcpp::DT_JMPREL, od); + odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_REL); + } + + if (this->rel_dyn_ != NULL) + { + const Output_data* od = this->rel_dyn_; + odyn->add_section_address(elfcpp::DT_REL, od); + odyn->add_section_size(elfcpp::DT_RELSZ, od); + odyn->add_constant(elfcpp::DT_RELENT, + elfcpp::Elf_sizes<32>::rel_size); + } + + if (!options->is_shared()) + { + // The value of the DT_DEBUG tag is filled in by the dynamic + // linker at run time, and used by the debugger. + odyn->add_constant(elfcpp::DT_DEBUG, 0); + } + } + + // Emit any relocs we saved in an attempt to avoid generating COPY + // relocs. + if (this->copy_relocs_ == NULL) + return; + if (this->copy_relocs_->any_to_emit()) + { + Reloc_section* rel_dyn = this->rel_dyn_section(layout); + this->copy_relocs_->emit(rel_dyn); + } + delete this->copy_relocs_; + this->copy_relocs_ = NULL; +} + +// Perform a relocation. + +inline bool +Target_i386::Relocate::relocate(const Relocate_info<32, false>* relinfo, + Target_i386* target, + size_t relnum, + const elfcpp::Rel<32, false>& rel, + unsigned int r_type, + const Sized_symbol<32>* gsym, + const Symbol_value<32>* psymval, + unsigned char* view, + elfcpp::Elf_types<32>::Elf_Addr address, + off_t view_size) +{ + if (this->skip_call_tls_get_addr_) + { + if (r_type != elfcpp::R_386_PLT32 + || gsym == NULL + || strcmp(gsym->name(), "___tls_get_addr") != 0) + { + fprintf(stderr, _("%s: %s: missing expected TLS relocation\n"), + program_name, + relinfo->location(relnum, rel.get_r_offset()).c_str()); + gold_exit(false); + } + + this->skip_call_tls_get_addr_ = false; + + return false; + } + + // Pick the value to use for symbols defined in shared objects. + Symbol_value<32> symval; + if (gsym != NULL && gsym->is_from_dynobj()) + { + if (!gsym->has_plt_offset()) + gold_unreachable(); + + symval.set_output_value(target->plt_section()->address() + + gsym->plt_offset()); + psymval = &symval; + } + + const Sized_relobj<32, false>* object = relinfo->object; + + switch (r_type) + { + case elfcpp::R_386_NONE: + case elfcpp::R_386_GNU_VTINHERIT: + case elfcpp::R_386_GNU_VTENTRY: + break; + + case elfcpp::R_386_32: + Relocate_functions<32, false>::rel32(view, object, psymval); + break; + + case elfcpp::R_386_PC32: + Relocate_functions<32, false>::pcrel32(view, object, psymval, address); + break; + + case elfcpp::R_386_16: + Relocate_functions<32, false>::rel16(view, object, psymval); + break; + + case elfcpp::R_386_PC16: + Relocate_functions<32, false>::pcrel16(view, object, psymval, address); + break; + + case elfcpp::R_386_8: + Relocate_functions<32, false>::rel8(view, object, psymval); + break; + + case elfcpp::R_386_PC8: + Relocate_functions<32, false>::pcrel8(view, object, psymval, address); + break; + + case elfcpp::R_386_PLT32: + gold_assert(gsym->has_plt_offset() + || gsym->final_value_is_known(relinfo->options)); + Relocate_functions<32, false>::pcrel32(view, object, psymval, address); + break; + + case elfcpp::R_386_GOT32: + // Local GOT offsets not yet supported. + gold_assert(gsym); + gold_assert(gsym->has_got_offset()); + Relocate_functions<32, false>::rel32(view, gsym->got_offset()); + break; + + case elfcpp::R_386_GOTOFF: + { + elfcpp::Elf_types<32>::Elf_Addr value; + value = (psymval->value(object, 0) + - target->got_section(NULL, NULL, NULL)->address()); + Relocate_functions<32, false>::rel32(view, value); + } + break; + + case elfcpp::R_386_GOTPC: + { + elfcpp::Elf_types<32>::Elf_Addr value; + value = target->got_section(NULL, NULL, NULL)->address(); + Relocate_functions<32, false>::pcrel32(view, value, address); + } + break; + + case elfcpp::R_386_COPY: + case elfcpp::R_386_GLOB_DAT: + case elfcpp::R_386_JUMP_SLOT: + case elfcpp::R_386_RELATIVE: + case elfcpp::R_386_TLS_TPOFF: + case elfcpp::R_386_TLS_DTPMOD32: + case elfcpp::R_386_TLS_DTPOFF32: + case elfcpp::R_386_TLS_TPOFF32: + case elfcpp::R_386_TLS_DESC: + fprintf(stderr, _("%s: %s: unexpected reloc %u in object file\n"), + program_name, + relinfo->location(relnum, rel.get_r_offset()).c_str(), + r_type); + gold_exit(false); + break; + + case elfcpp::R_386_TLS_IE: + case elfcpp::R_386_TLS_GOTIE: + case elfcpp::R_386_TLS_LE: + case elfcpp::R_386_TLS_GD: + case elfcpp::R_386_TLS_LDM: + case elfcpp::R_386_TLS_LDO_32: + case elfcpp::R_386_TLS_IE_32: + case elfcpp::R_386_TLS_LE_32: + case elfcpp::R_386_TLS_GOTDESC: + case elfcpp::R_386_TLS_DESC_CALL: + this->relocate_tls(relinfo, relnum, rel, r_type, gsym, psymval, view, + address, view_size); + break; + + case elfcpp::R_386_32PLT: + case elfcpp::R_386_TLS_GD_32: + case elfcpp::R_386_TLS_GD_PUSH: + case elfcpp::R_386_TLS_GD_CALL: + case elfcpp::R_386_TLS_GD_POP: + case elfcpp::R_386_TLS_LDM_32: + case elfcpp::R_386_TLS_LDM_PUSH: + case elfcpp::R_386_TLS_LDM_CALL: + case elfcpp::R_386_TLS_LDM_POP: + case elfcpp::R_386_USED_BY_INTEL_200: + default: + fprintf(stderr, _("%s: %s: unsupported reloc %u\n"), + program_name, + relinfo->location(relnum, rel.get_r_offset()).c_str(), + r_type); + // gold_exit(false); + break; + } + + return true; +} + +// Perform a TLS relocation. + +inline void +Target_i386::Relocate::relocate_tls(const Relocate_info<32, false>* relinfo, + size_t relnum, + const elfcpp::Rel<32, false>& rel, + unsigned int r_type, + const Sized_symbol<32>* gsym, + const Symbol_value<32>* psymval, + unsigned char* view, + elfcpp::Elf_types<32>::Elf_Addr, + off_t view_size) +{ + Output_segment* tls_segment = relinfo->layout->tls_segment(); + if (tls_segment == NULL) + { + fprintf(stderr, _("%s: %s: TLS reloc but no TLS segment\n"), + program_name, + relinfo->location(relnum, rel.get_r_offset()).c_str()); + gold_exit(false); + } + + elfcpp::Elf_types<32>::Elf_Addr value = psymval->value(relinfo->object, 0); + + const bool is_final = (gsym == NULL + ? !relinfo->options->is_shared() + : gsym->final_value_is_known(relinfo->options)); + const unsigned int opt_r_type = + Target_i386::optimize_tls_reloc(relinfo->options, is_final, r_type); + switch (r_type) + { + case elfcpp::R_386_TLS_LE_32: + value = tls_segment->vaddr() + tls_segment->memsz() - value; + Relocate_functions<32, false>::rel32(view, value); + break; + + case elfcpp::R_386_TLS_LE: + value = value - (tls_segment->vaddr() + tls_segment->memsz()); + Relocate_functions<32, false>::rel32(view, value); + break; + + case elfcpp::R_386_TLS_IE: + case elfcpp::R_386_TLS_GOTIE: + case elfcpp::R_386_TLS_IE_32: + if (opt_r_type == elfcpp::R_386_TLS_LE_32) + { + Target_i386::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment, + rel, r_type, value, view, + view_size); + break; + } + fprintf(stderr, _("%s: %s: unsupported reloc type %u\n"), + program_name, + relinfo->location(relnum, rel.get_r_offset()).c_str(), + r_type); + // gold_exit(false); + break; + + case elfcpp::R_386_TLS_GD: + if (opt_r_type == elfcpp::R_386_TLS_LE_32) + { + this->tls_gd_to_le(relinfo, relnum, tls_segment, + rel, r_type, value, view, + view_size); + break; + } + fprintf(stderr, _("%s: %s: unsupported reloc %u\n"), + program_name, + relinfo->location(relnum, rel.get_r_offset()).c_str(), + r_type); + // gold_exit(false); + break; + + case elfcpp::R_386_TLS_LDM: + case elfcpp::R_386_TLS_LDO_32: + case elfcpp::R_386_TLS_GOTDESC: + case elfcpp::R_386_TLS_DESC_CALL: + fprintf(stderr, _("%s: %s: unsupported reloc %u\n"), + program_name, + relinfo->location(relnum, rel.get_r_offset()).c_str(), + r_type); + // gold_exit(false); + break; + } +} + +// Do a relocation in which we convert a TLS Initial-Exec to a +// Local-Exec. + +inline void +Target_i386::Relocate::tls_ie_to_le(const Relocate_info<32, false>* relinfo, + size_t relnum, + Output_segment* tls_segment, + const elfcpp::Rel<32, false>& rel, + unsigned int r_type, + elfcpp::Elf_types<32>::Elf_Addr value, + unsigned char* view, + off_t view_size) +{ + // We have to actually change the instructions, which means that we + // need to examine the opcodes to figure out which instruction we + // are looking at. + if (r_type == elfcpp::R_386_TLS_IE) + { + // movl %gs:XX,%eax ==> movl $YY,%eax + // movl %gs:XX,%reg ==> movl $YY,%reg + // addl %gs:XX,%reg ==> addl $YY,%reg + Target_i386::Relocate::check_range(relinfo, relnum, rel, view_size, -1); + Target_i386::Relocate::check_range(relinfo, relnum, rel, view_size, 4); + + unsigned char op1 = view[-1]; + if (op1 == 0xa1) + { + // movl XX,%eax ==> movl $YY,%eax + view[-1] = 0xb8; + } + else + { + Target_i386::Relocate::check_range(relinfo, relnum, rel, + view_size, -2); + + unsigned char op2 = view[-2]; + if (op2 == 0x8b) + { + // movl XX,%reg ==> movl $YY,%reg + Target_i386::Relocate::check_tls(relinfo, relnum, rel, + (op1 & 0xc7) == 0x05); + view[-2] = 0xc7; + view[-1] = 0xc0 | ((op1 >> 3) & 7); + } + else if (op2 == 0x03) + { + // addl XX,%reg ==> addl $YY,%reg + Target_i386::Relocate::check_tls(relinfo, relnum, rel, + (op1 & 0xc7) == 0x05); + view[-2] = 0x81; + view[-1] = 0xc0 | ((op1 >> 3) & 7); + } + else + Target_i386::Relocate::check_tls(relinfo, relnum, rel, 0); + } + } + else + { + // subl %gs:XX(%reg1),%reg2 ==> subl $YY,%reg2 + // movl %gs:XX(%reg1),%reg2 ==> movl $YY,%reg2 + // addl %gs:XX(%reg1),%reg2 ==> addl $YY,$reg2 + Target_i386::Relocate::check_range(relinfo, relnum, rel, view_size, -2); + Target_i386::Relocate::check_range(relinfo, relnum, rel, view_size, 4); + + unsigned char op1 = view[-1]; + unsigned char op2 = view[-2]; + Target_i386::Relocate::check_tls(relinfo, relnum, rel, + (op1 & 0xc0) == 0x80 && (op1 & 7) != 4); + if (op2 == 0x8b) + { + // movl %gs:XX(%reg1),%reg2 ==> movl $YY,%reg2 + view[-2] = 0xc7; + view[-1] = 0xc0 | ((op1 >> 3) & 7); + } + else if (op2 == 0x2b) + { + // subl %gs:XX(%reg1),%reg2 ==> subl $YY,%reg2 + view[-2] = 0x81; + view[-1] = 0xe8 | ((op1 >> 3) & 7); + } + else if (op2 == 0x03) + { + // addl %gs:XX(%reg1),%reg2 ==> addl $YY,$reg2 + view[-2] = 0x81; + view[-1] = 0xc0 | ((op1 >> 3) & 7); + } + else + Target_i386::Relocate::check_tls(relinfo, relnum, rel, 0); + } + + value = tls_segment->vaddr() + tls_segment->memsz() - value; + if (r_type == elfcpp::R_386_TLS_IE || r_type == elfcpp::R_386_TLS_GOTIE) + value = - value; + + Relocate_functions<32, false>::rel32(view, value); +} + +// Do a relocation in which we convert a TLS Global-Dynamic to a +// Local-Exec. + +inline void +Target_i386::Relocate::tls_gd_to_le(const Relocate_info<32, false>* relinfo, + size_t relnum, + Output_segment* tls_segment, + const elfcpp::Rel<32, false>& rel, + unsigned int, + elfcpp::Elf_types<32>::Elf_Addr value, + unsigned char* view, + off_t view_size) +{ + // leal foo(,%reg,1),%eax; call ___tls_get_addr + // ==> movl %gs,0,%eax; subl $foo@tpoff,%eax + // leal foo(%reg),%eax; call ___tls_get_addr + // ==> movl %gs:0,%eax; subl $foo@tpoff,%eax + + Target_i386::Relocate::check_range(relinfo, relnum, rel, view_size, -2); + Target_i386::Relocate::check_range(relinfo, relnum, rel, view_size, 9); + + unsigned char op1 = view[-1]; + unsigned char op2 = view[-2]; + + Target_i386::Relocate::check_tls(relinfo, relnum, rel, + op2 == 0x8d || op2 == 0x04); + Target_i386::Relocate::check_tls(relinfo, relnum, rel, + view[4] == 0xe8); + + int roff = 5; + + if (op2 == 0x04) + { + Target_i386::Relocate::check_range(relinfo, relnum, rel, view_size, -3); + Target_i386::Relocate::check_tls(relinfo, relnum, rel, + view[-3] == 0x8d); + Target_i386::Relocate::check_tls(relinfo, relnum, rel, + ((op1 & 0xc7) == 0x05 + && op1 != (4 << 3))); + memcpy(view - 3, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12); + } + else + { + Target_i386::Relocate::check_tls(relinfo, relnum, rel, + (op1 & 0xf8) == 0x80 && (op1 & 7) != 4); + if (rel.get_r_offset() + 9 < view_size && view[9] == 0x90) + { + // There is a trailing nop. Use the size byte subl. + memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12); + roff = 6; + } + else + { + // Use the five byte subl. + memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11); + } + } + + value = tls_segment->vaddr() + tls_segment->memsz() - value; + Relocate_functions<32, false>::rel32(view + roff, value); + + // The next reloc should be a PLT32 reloc against __tls_get_addr. + // We can skip it. + this->skip_call_tls_get_addr_ = true; +} + +// Check the range for a TLS relocation. + +inline void +Target_i386::Relocate::check_range(const Relocate_info<32, false>* relinfo, + size_t relnum, + const elfcpp::Rel<32, false>& rel, + off_t view_size, off_t off) +{ + off_t offset = rel.get_r_offset() + off; + if (offset < 0 || offset > view_size) + { + fprintf(stderr, _("%s: %s: TLS relocation out of range\n"), + program_name, + relinfo->location(relnum, rel.get_r_offset()).c_str()); + gold_exit(false); + } +} + +// Check the validity of a TLS relocation. This is like assert. + +inline void +Target_i386::Relocate::check_tls(const Relocate_info<32, false>* relinfo, + size_t relnum, + const elfcpp::Rel<32, false>& rel, + bool valid) +{ + if (!valid) + { + fprintf(stderr, + _("%s: %s: TLS relocation against invalid instruction\n"), + program_name, + relinfo->location(relnum, rel.get_r_offset()).c_str()); + gold_exit(false); + } +} + +// Relocate section data. + +void +Target_i386::relocate_section(const Relocate_info<32, false>* relinfo, + unsigned int sh_type, + const unsigned char* prelocs, + size_t reloc_count, + unsigned char* view, + elfcpp::Elf_types<32>::Elf_Addr address, + off_t view_size) +{ + gold_assert(sh_type == elfcpp::SHT_REL); + + gold::relocate_section<32, false, Target_i386, elfcpp::SHT_REL, + Target_i386::Relocate>( + relinfo, + this, + prelocs, + reloc_count, + view, + address, + view_size); +} + +// The selector for i386 object files. + +class Target_selector_i386 : public Target_selector +{ +public: + Target_selector_i386() + : Target_selector(elfcpp::EM_386, 32, false) + { } + + Target* + recognize(int machine, int osabi, int abiversion); + + private: + Target_i386* target_; +}; + +// Recognize an i386 object file when we already know that the machine +// number is EM_386. + +Target* +Target_selector_i386::recognize(int, int, int) +{ + if (this->target_ == NULL) + this->target_ = new Target_i386(); + return this->target_; +} + +Target_selector_i386 target_selector_i386; + +} // End anonymous namespace. |