diff options
Diffstat (limited to 'gold/dynobj.cc')
| -rw-r--r-- | gold/dynobj.cc | 1647 |
1 files changed, 1647 insertions, 0 deletions
diff --git a/gold/dynobj.cc b/gold/dynobj.cc new file mode 100644 index 000000000000..1bd5a85e4392 --- /dev/null +++ b/gold/dynobj.cc @@ -0,0 +1,1647 @@ +// dynobj.cc -- dynamic object support for gold + +#include "gold.h" + +#include <vector> +#include <cstring> + +#include "elfcpp.h" +#include "symtab.h" +#include "dynobj.h" + +namespace gold +{ + +// Class Dynobj. + +// Return the string to use in a DT_NEEDED entry. + +const char* +Dynobj::soname() const +{ + if (!this->soname_.empty()) + return this->soname_.c_str(); + return this->name().c_str(); +} + +// Class Sized_dynobj. + +template<int size, bool big_endian> +Sized_dynobj<size, big_endian>::Sized_dynobj( + const std::string& name, + Input_file* input_file, + off_t offset, + const elfcpp::Ehdr<size, big_endian>& ehdr) + : Dynobj(name, input_file, offset), + elf_file_(this, ehdr) +{ +} + +// Set up the object. + +template<int size, bool big_endian> +void +Sized_dynobj<size, big_endian>::setup( + const elfcpp::Ehdr<size, big_endian>& ehdr) +{ + this->set_target(ehdr.get_e_machine(), size, big_endian, + ehdr.get_e_ident()[elfcpp::EI_OSABI], + ehdr.get_e_ident()[elfcpp::EI_ABIVERSION]); + + const unsigned int shnum = this->elf_file_.shnum(); + this->set_shnum(shnum); +} + +// Find the SHT_DYNSYM section and the various version sections, and +// the dynamic section, given the section headers. + +template<int size, bool big_endian> +void +Sized_dynobj<size, big_endian>::find_dynsym_sections( + const unsigned char* pshdrs, + unsigned int* pdynsym_shndx, + unsigned int* pversym_shndx, + unsigned int* pverdef_shndx, + unsigned int* pverneed_shndx, + unsigned int* pdynamic_shndx) +{ + *pdynsym_shndx = -1U; + *pversym_shndx = -1U; + *pverdef_shndx = -1U; + *pverneed_shndx = -1U; + *pdynamic_shndx = -1U; + + const unsigned int shnum = this->shnum(); + const unsigned char* p = pshdrs; + for (unsigned int i = 0; i < shnum; ++i, p += This::shdr_size) + { + typename This::Shdr shdr(p); + + unsigned int* pi; + switch (shdr.get_sh_type()) + { + case elfcpp::SHT_DYNSYM: + pi = pdynsym_shndx; + break; + case elfcpp::SHT_GNU_versym: + pi = pversym_shndx; + break; + case elfcpp::SHT_GNU_verdef: + pi = pverdef_shndx; + break; + case elfcpp::SHT_GNU_verneed: + pi = pverneed_shndx; + break; + case elfcpp::SHT_DYNAMIC: + pi = pdynamic_shndx; + break; + default: + pi = NULL; + break; + } + + if (pi == NULL) + continue; + + if (*pi != -1U) + { + fprintf(stderr, + _("%s: %s: unexpected duplicate type %u section: %u, %u\n"), + program_name, this->name().c_str(), shdr.get_sh_type(), + *pi, i); + gold_exit(false); + } + + *pi = i; + } +} + +// Read the contents of section SHNDX. PSHDRS points to the section +// headers. TYPE is the expected section type. LINK is the expected +// section link. Store the data in *VIEW and *VIEW_SIZE. The +// section's sh_info field is stored in *VIEW_INFO. + +template<int size, bool big_endian> +void +Sized_dynobj<size, big_endian>::read_dynsym_section( + const unsigned char* pshdrs, + unsigned int shndx, + elfcpp::SHT type, + unsigned int link, + File_view** view, + off_t* view_size, + unsigned int* view_info) +{ + if (shndx == -1U) + { + *view = NULL; + *view_size = 0; + *view_info = 0; + return; + } + + typename This::Shdr shdr(pshdrs + shndx * This::shdr_size); + + gold_assert(shdr.get_sh_type() == type); + + if (shdr.get_sh_link() != link) + { + fprintf(stderr, + _("%s: %s: unexpected link in section %u header: %u != %u\n"), + program_name, this->name().c_str(), shndx, + shdr.get_sh_link(), link); + gold_exit(false); + } + + *view = this->get_lasting_view(shdr.get_sh_offset(), shdr.get_sh_size()); + *view_size = shdr.get_sh_size(); + *view_info = shdr.get_sh_info(); +} + +// Set the soname field if this shared object has a DT_SONAME tag. +// PSHDRS points to the section headers. DYNAMIC_SHNDX is the section +// index of the SHT_DYNAMIC section. STRTAB_SHNDX, STRTAB, and +// STRTAB_SIZE are the section index and contents of a string table +// which may be the one associated with the SHT_DYNAMIC section. + +template<int size, bool big_endian> +void +Sized_dynobj<size, big_endian>::set_soname(const unsigned char* pshdrs, + unsigned int dynamic_shndx, + unsigned int strtab_shndx, + const unsigned char* strtabu, + off_t strtab_size) +{ + typename This::Shdr dynamicshdr(pshdrs + dynamic_shndx * This::shdr_size); + gold_assert(dynamicshdr.get_sh_type() == elfcpp::SHT_DYNAMIC); + + const off_t dynamic_size = dynamicshdr.get_sh_size(); + const unsigned char* pdynamic = this->get_view(dynamicshdr.get_sh_offset(), + dynamic_size); + + const unsigned int link = dynamicshdr.get_sh_link(); + if (link != strtab_shndx) + { + if (link >= this->shnum()) + { + fprintf(stderr, + _("%s: %s: DYNAMIC section %u link out of range: %u\n"), + program_name, this->name().c_str(), + dynamic_shndx, link); + gold_exit(false); + } + + typename This::Shdr strtabshdr(pshdrs + link * This::shdr_size); + if (strtabshdr.get_sh_type() != elfcpp::SHT_STRTAB) + { + fprintf(stderr, + _("%s: %s: DYNAMIC section %u link %u is not a strtab\n"), + program_name, this->name().c_str(), + dynamic_shndx, link); + gold_exit(false); + } + + strtab_size = strtabshdr.get_sh_size(); + strtabu = this->get_view(strtabshdr.get_sh_offset(), strtab_size); + } + + for (const unsigned char* p = pdynamic; + p < pdynamic + dynamic_size; + p += This::dyn_size) + { + typename This::Dyn dyn(p); + + if (dyn.get_d_tag() == elfcpp::DT_SONAME) + { + off_t val = dyn.get_d_val(); + if (val >= strtab_size) + { + fprintf(stderr, + _("%s: %s: DT_SONAME value out of range: " + "%lld >= %lld\n"), + program_name, this->name().c_str(), + static_cast<long long>(val), + static_cast<long long>(strtab_size)); + gold_exit(false); + } + + const char* strtab = reinterpret_cast<const char*>(strtabu); + this->set_soname_string(strtab + val); + return; + } + + if (dyn.get_d_tag() == elfcpp::DT_NULL) + return; + } + + fprintf(stderr, _("%s: %s: missing DT_NULL in dynamic segment\n"), + program_name, this->name().c_str()); + gold_exit(false); +} + +// Read the symbols and sections from a dynamic object. We read the +// dynamic symbols, not the normal symbols. + +template<int size, bool big_endian> +void +Sized_dynobj<size, big_endian>::do_read_symbols(Read_symbols_data* sd) +{ + this->read_section_data(&this->elf_file_, sd); + + const unsigned char* const pshdrs = sd->section_headers->data(); + + unsigned int dynsym_shndx; + unsigned int versym_shndx; + unsigned int verdef_shndx; + unsigned int verneed_shndx; + unsigned int dynamic_shndx; + this->find_dynsym_sections(pshdrs, &dynsym_shndx, &versym_shndx, + &verdef_shndx, &verneed_shndx, &dynamic_shndx); + + unsigned int strtab_shndx = -1U; + + if (dynsym_shndx == -1U) + { + sd->symbols = NULL; + sd->symbols_size = 0; + sd->symbol_names = NULL; + sd->symbol_names_size = 0; + } + else + { + // Get the dynamic symbols. + typename This::Shdr dynsymshdr(pshdrs + dynsym_shndx * This::shdr_size); + gold_assert(dynsymshdr.get_sh_type() == elfcpp::SHT_DYNSYM); + + sd->symbols = this->get_lasting_view(dynsymshdr.get_sh_offset(), + dynsymshdr.get_sh_size()); + sd->symbols_size = dynsymshdr.get_sh_size(); + + // Get the symbol names. + strtab_shndx = dynsymshdr.get_sh_link(); + if (strtab_shndx >= this->shnum()) + { + fprintf(stderr, + _("%s: %s: invalid dynamic symbol table name index: %u\n"), + program_name, this->name().c_str(), strtab_shndx); + gold_exit(false); + } + typename This::Shdr strtabshdr(pshdrs + strtab_shndx * This::shdr_size); + if (strtabshdr.get_sh_type() != elfcpp::SHT_STRTAB) + { + fprintf(stderr, + _("%s: %s: dynamic symbol table name section " + "has wrong type: %u\n"), + program_name, this->name().c_str(), + static_cast<unsigned int>(strtabshdr.get_sh_type())); + gold_exit(false); + } + + sd->symbol_names = this->get_lasting_view(strtabshdr.get_sh_offset(), + strtabshdr.get_sh_size()); + sd->symbol_names_size = strtabshdr.get_sh_size(); + + // Get the version information. + + unsigned int dummy; + this->read_dynsym_section(pshdrs, versym_shndx, elfcpp::SHT_GNU_versym, + dynsym_shndx, &sd->versym, &sd->versym_size, + &dummy); + + // We require that the version definition and need section link + // to the same string table as the dynamic symbol table. This + // is not a technical requirement, but it always happens in + // practice. We could change this if necessary. + + this->read_dynsym_section(pshdrs, verdef_shndx, elfcpp::SHT_GNU_verdef, + strtab_shndx, &sd->verdef, &sd->verdef_size, + &sd->verdef_info); + + this->read_dynsym_section(pshdrs, verneed_shndx, elfcpp::SHT_GNU_verneed, + strtab_shndx, &sd->verneed, &sd->verneed_size, + &sd->verneed_info); + } + + // Read the SHT_DYNAMIC section to find whether this shared object + // has a DT_SONAME tag. This doesn't really have anything to do + // with reading the symbols, but this is a convenient place to do + // it. + if (dynamic_shndx != -1U) + this->set_soname(pshdrs, dynamic_shndx, strtab_shndx, + (sd->symbol_names == NULL + ? NULL + : sd->symbol_names->data()), + sd->symbol_names_size); +} + +// Lay out the input sections for a dynamic object. We don't want to +// include sections from a dynamic object, so all that we actually do +// here is check for .gnu.warning sections. + +template<int size, bool big_endian> +void +Sized_dynobj<size, big_endian>::do_layout(const General_options&, + Symbol_table* symtab, + Layout*, + Read_symbols_data* sd) +{ + const unsigned int shnum = this->shnum(); + if (shnum == 0) + return; + + // Get the section headers. + const unsigned char* pshdrs = sd->section_headers->data(); + + // Get the section names. + const unsigned char* pnamesu = sd->section_names->data(); + const char* pnames = reinterpret_cast<const char*>(pnamesu); + + // Skip the first, dummy, section. + pshdrs += This::shdr_size; + for (unsigned int i = 1; i < shnum; ++i, pshdrs += This::shdr_size) + { + typename This::Shdr shdr(pshdrs); + + if (shdr.get_sh_name() >= sd->section_names_size) + { + fprintf(stderr, + _("%s: %s: bad section name offset for section %u: %lu\n"), + program_name, this->name().c_str(), i, + static_cast<unsigned long>(shdr.get_sh_name())); + gold_exit(false); + } + + const char* name = pnames + shdr.get_sh_name(); + + this->handle_gnu_warning_section(name, i, symtab); + } + + delete sd->section_headers; + sd->section_headers = NULL; + delete sd->section_names; + sd->section_names = NULL; +} + +// Add an entry to the vector mapping version numbers to version +// strings. + +template<int size, bool big_endian> +void +Sized_dynobj<size, big_endian>::set_version_map( + Version_map* version_map, + unsigned int ndx, + const char* name) const +{ + if (ndx >= version_map->size()) + version_map->resize(ndx + 1); + if ((*version_map)[ndx] != NULL) + { + fprintf(stderr, _("%s: %s: duplicate definition for version %u\n"), + program_name, this->name().c_str(), ndx); + gold_exit(false); + } + (*version_map)[ndx] = name; +} + +// Add mappings for the version definitions to VERSION_MAP. + +template<int size, bool big_endian> +void +Sized_dynobj<size, big_endian>::make_verdef_map( + Read_symbols_data* sd, + Version_map* version_map) const +{ + if (sd->verdef == NULL) + return; + + const char* names = reinterpret_cast<const char*>(sd->symbol_names->data()); + off_t names_size = sd->symbol_names_size; + + const unsigned char* pverdef = sd->verdef->data(); + off_t verdef_size = sd->verdef_size; + const unsigned int count = sd->verdef_info; + + const unsigned char* p = pverdef; + for (unsigned int i = 0; i < count; ++i) + { + elfcpp::Verdef<size, big_endian> verdef(p); + + if (verdef.get_vd_version() != elfcpp::VER_DEF_CURRENT) + { + fprintf(stderr, _("%s: %s: unexpected verdef version %u\n"), + program_name, this->name().c_str(), verdef.get_vd_version()); + gold_exit(false); + } + + const unsigned int vd_ndx = verdef.get_vd_ndx(); + + // The GNU linker clears the VERSYM_HIDDEN bit. I'm not + // sure why. + + // The first Verdaux holds the name of this version. Subsequent + // ones are versions that this one depends upon, which we don't + // care about here. + const unsigned int vd_cnt = verdef.get_vd_cnt(); + if (vd_cnt < 1) + { + fprintf(stderr, _("%s: %s: verdef vd_cnt field too small: %u\n"), + program_name, this->name().c_str(), vd_cnt); + gold_exit(false); + } + + const unsigned int vd_aux = verdef.get_vd_aux(); + if ((p - pverdef) + vd_aux >= verdef_size) + { + fprintf(stderr, + _("%s: %s: verdef vd_aux field out of range: %u\n"), + program_name, this->name().c_str(), vd_aux); + gold_exit(false); + } + + const unsigned char* pvda = p + vd_aux; + elfcpp::Verdaux<size, big_endian> verdaux(pvda); + + const unsigned int vda_name = verdaux.get_vda_name(); + if (vda_name >= names_size) + { + fprintf(stderr, + _("%s: %s: verdaux vda_name field out of range: %u\n"), + program_name, this->name().c_str(), vda_name); + gold_exit(false); + } + + this->set_version_map(version_map, vd_ndx, names + vda_name); + + const unsigned int vd_next = verdef.get_vd_next(); + if ((p - pverdef) + vd_next >= verdef_size) + { + fprintf(stderr, + _("%s: %s: verdef vd_next field out of range: %u\n"), + program_name, this->name().c_str(), vd_next); + gold_exit(false); + } + + p += vd_next; + } +} + +// Add mappings for the required versions to VERSION_MAP. + +template<int size, bool big_endian> +void +Sized_dynobj<size, big_endian>::make_verneed_map( + Read_symbols_data* sd, + Version_map* version_map) const +{ + if (sd->verneed == NULL) + return; + + const char* names = reinterpret_cast<const char*>(sd->symbol_names->data()); + off_t names_size = sd->symbol_names_size; + + const unsigned char* pverneed = sd->verneed->data(); + const off_t verneed_size = sd->verneed_size; + const unsigned int count = sd->verneed_info; + + const unsigned char* p = pverneed; + for (unsigned int i = 0; i < count; ++i) + { + elfcpp::Verneed<size, big_endian> verneed(p); + + if (verneed.get_vn_version() != elfcpp::VER_NEED_CURRENT) + { + fprintf(stderr, _("%s: %s: unexpected verneed version %u\n"), + program_name, this->name().c_str(), + verneed.get_vn_version()); + gold_exit(false); + } + + const unsigned int vn_aux = verneed.get_vn_aux(); + + if ((p - pverneed) + vn_aux >= verneed_size) + { + fprintf(stderr, + _("%s: %s: verneed vn_aux field out of range: %u\n"), + program_name, this->name().c_str(), vn_aux); + gold_exit(false); + } + + const unsigned int vn_cnt = verneed.get_vn_cnt(); + const unsigned char* pvna = p + vn_aux; + for (unsigned int j = 0; j < vn_cnt; ++j) + { + elfcpp::Vernaux<size, big_endian> vernaux(pvna); + + const unsigned int vna_name = vernaux.get_vna_name(); + if (vna_name >= names_size) + { + fprintf(stderr, + _("%s: %s: vernaux vna_name field " + "out of range: %u\n"), + program_name, this->name().c_str(), vna_name); + gold_exit(false); + } + + this->set_version_map(version_map, vernaux.get_vna_other(), + names + vna_name); + + const unsigned int vna_next = vernaux.get_vna_next(); + if ((pvna - pverneed) + vna_next >= verneed_size) + { + fprintf(stderr, + _("%s: %s: verneed vna_next field " + "out of range: %u\n"), + program_name, this->name().c_str(), vna_next); + gold_exit(false); + } + + pvna += vna_next; + } + + const unsigned int vn_next = verneed.get_vn_next(); + if ((p - pverneed) + vn_next >= verneed_size) + { + fprintf(stderr, + _("%s: %s: verneed vn_next field out of range: %u\n"), + program_name, this->name().c_str(), vn_next); + gold_exit(false); + } + + p += vn_next; + } +} + +// Create a vector mapping version numbers to version strings. + +template<int size, bool big_endian> +void +Sized_dynobj<size, big_endian>::make_version_map( + Read_symbols_data* sd, + Version_map* version_map) const +{ + if (sd->verdef == NULL && sd->verneed == NULL) + return; + + // A guess at the maximum version number we will see. If this is + // wrong we will be less efficient but still correct. + version_map->reserve(sd->verdef_info + sd->verneed_info * 10); + + this->make_verdef_map(sd, version_map); + this->make_verneed_map(sd, version_map); +} + +// Add the dynamic symbols to the symbol table. + +template<int size, bool big_endian> +void +Sized_dynobj<size, big_endian>::do_add_symbols(Symbol_table* symtab, + Read_symbols_data* sd) +{ + if (sd->symbols == NULL) + { + gold_assert(sd->symbol_names == NULL); + gold_assert(sd->versym == NULL && sd->verdef == NULL + && sd->verneed == NULL); + return; + } + + const int sym_size = This::sym_size; + const size_t symcount = sd->symbols_size / sym_size; + if (symcount * sym_size != sd->symbols_size) + { + fprintf(stderr, + _("%s: %s: size of dynamic symbols is not " + "multiple of symbol size\n"), + program_name, this->name().c_str()); + gold_exit(false); + } + + Version_map version_map; + this->make_version_map(sd, &version_map); + + const char* sym_names = + reinterpret_cast<const char*>(sd->symbol_names->data()); + symtab->add_from_dynobj(this, sd->symbols->data(), symcount, + sym_names, sd->symbol_names_size, + (sd->versym == NULL + ? NULL + : sd->versym->data()), + sd->versym_size, + &version_map); + + delete sd->symbols; + sd->symbols = NULL; + delete sd->symbol_names; + sd->symbol_names = NULL; + if (sd->versym != NULL) + { + delete sd->versym; + sd->versym = NULL; + } + if (sd->verdef != NULL) + { + delete sd->verdef; + sd->verdef = NULL; + } + if (sd->verneed != NULL) + { + delete sd->verneed; + sd->verneed = NULL; + } +} + +// Given a vector of hash codes, compute the number of hash buckets to +// use. + +unsigned int +Dynobj::compute_bucket_count(const std::vector<uint32_t>& hashcodes, + bool for_gnu_hash_table) +{ + // FIXME: Implement optional hash table optimization. + + // Array used to determine the number of hash table buckets to use + // based on the number of symbols there are. If there are fewer + // than 3 symbols we use 1 bucket, fewer than 17 symbols we use 3 + // buckets, fewer than 37 we use 17 buckets, and so forth. We never + // use more than 32771 buckets. This is straight from the old GNU + // linker. + static const unsigned int buckets[] = + { + 1, 3, 17, 37, 67, 97, 131, 197, 263, 521, 1031, 2053, 4099, 8209, + 16411, 32771 + }; + const int buckets_count = sizeof buckets / sizeof buckets[0]; + + unsigned int symcount = hashcodes.size(); + unsigned int ret = 1; + for (int i = 0; i < buckets_count; ++i) + { + if (symcount < buckets[i]) + break; + ret = buckets[i]; + } + + if (for_gnu_hash_table && ret < 2) + ret = 2; + + return ret; +} + +// The standard ELF hash function. This hash function must not +// change, as the dynamic linker uses it also. + +uint32_t +Dynobj::elf_hash(const char* name) +{ + const unsigned char* nameu = reinterpret_cast<const unsigned char*>(name); + uint32_t h = 0; + unsigned char c; + while ((c = *nameu++) != '\0') + { + h = (h << 4) + c; + uint32_t g = h & 0xf0000000; + if (g != 0) + { + h ^= g >> 24; + // The ELF ABI says h &= ~g, but using xor is equivalent in + // this case (since g was set from h) and may save one + // instruction. + h ^= g; + } + } + return h; +} + +// Create a standard ELF hash table, setting *PPHASH and *PHASHLEN. +// DYNSYMS is a vector with all the global dynamic symbols. +// LOCAL_DYNSYM_COUNT is the number of local symbols in the dynamic +// symbol table. + +void +Dynobj::create_elf_hash_table(const Target* target, + const std::vector<Symbol*>& dynsyms, + unsigned int local_dynsym_count, + unsigned char** pphash, + unsigned int* phashlen) +{ + unsigned int dynsym_count = dynsyms.size(); + + // Get the hash values for all the symbols. + std::vector<uint32_t> dynsym_hashvals(dynsym_count); + for (unsigned int i = 0; i < dynsym_count; ++i) + dynsym_hashvals[i] = Dynobj::elf_hash(dynsyms[i]->name()); + + const unsigned int bucketcount = + Dynobj::compute_bucket_count(dynsym_hashvals, false); + + std::vector<uint32_t> bucket(bucketcount); + std::vector<uint32_t> chain(local_dynsym_count + dynsym_count); + + for (unsigned int i = 0; i < dynsym_count; ++i) + { + unsigned int dynsym_index = dynsyms[i]->dynsym_index(); + unsigned int bucketpos = dynsym_hashvals[i] % bucketcount; + chain[dynsym_index] = bucket[bucketpos]; + bucket[bucketpos] = dynsym_index; + } + + unsigned int hashlen = ((2 + + bucketcount + + local_dynsym_count + + dynsym_count) + * 4); + unsigned char* phash = new unsigned char[hashlen]; + + if (target->is_big_endian()) + Dynobj::sized_create_elf_hash_table<true>(bucket, chain, phash, hashlen); + else + Dynobj::sized_create_elf_hash_table<false>(bucket, chain, phash, hashlen); + + *pphash = phash; + *phashlen = hashlen; +} + +// Fill in an ELF hash table. + +template<bool big_endian> +void +Dynobj::sized_create_elf_hash_table(const std::vector<uint32_t>& bucket, + const std::vector<uint32_t>& chain, + unsigned char* phash, + unsigned int hashlen) +{ + unsigned char* p = phash; + + const unsigned int bucketcount = bucket.size(); + const unsigned int chaincount = chain.size(); + + elfcpp::Swap<32, big_endian>::writeval(p, bucketcount); + p += 4; + elfcpp::Swap<32, big_endian>::writeval(p, chaincount); + p += 4; + + for (unsigned int i = 0; i < bucketcount; ++i) + { + elfcpp::Swap<32, big_endian>::writeval(p, bucket[i]); + p += 4; + } + + for (unsigned int i = 0; i < chaincount; ++i) + { + elfcpp::Swap<32, big_endian>::writeval(p, chain[i]); + p += 4; + } + + gold_assert(static_cast<unsigned int>(p - phash) == hashlen); +} + +// The hash function used for the GNU hash table. This hash function +// must not change, as the dynamic linker uses it also. + +uint32_t +Dynobj::gnu_hash(const char* name) +{ + const unsigned char* nameu = reinterpret_cast<const unsigned char*>(name); + uint32_t h = 5381; + unsigned char c; + while ((c = *nameu++) != '\0') + h = (h << 5) + h + c; + return h; +} + +// Create a GNU hash table, setting *PPHASH and *PHASHLEN. GNU hash +// tables are an extension to ELF which are recognized by the GNU +// dynamic linker. They are referenced using dynamic tag DT_GNU_HASH. +// TARGET is the target. DYNSYMS is a vector with all the global +// symbols which will be going into the dynamic symbol table. +// LOCAL_DYNSYM_COUNT is the number of local symbols in the dynamic +// symbol table. + +void +Dynobj::create_gnu_hash_table(const Target* target, + const std::vector<Symbol*>& dynsyms, + unsigned int local_dynsym_count, + unsigned char** pphash, + unsigned int* phashlen) +{ + const unsigned int count = dynsyms.size(); + + // Sort the dynamic symbols into two vectors. Symbols which we do + // not want to put into the hash table we store into + // UNHASHED_DYNSYMS. Symbols which we do want to store we put into + // HASHED_DYNSYMS. DYNSYM_HASHVALS is parallel to HASHED_DYNSYMS, + // and records the hash codes. + + std::vector<Symbol*> unhashed_dynsyms; + unhashed_dynsyms.reserve(count); + + std::vector<Symbol*> hashed_dynsyms; + hashed_dynsyms.reserve(count); + + std::vector<uint32_t> dynsym_hashvals; + dynsym_hashvals.reserve(count); + + for (unsigned int i = 0; i < count; ++i) + { + Symbol* sym = dynsyms[i]; + + // FIXME: Should put on unhashed_dynsyms if the symbol is + // hidden. + if (sym->is_undefined()) + unhashed_dynsyms.push_back(sym); + else + { + hashed_dynsyms.push_back(sym); + dynsym_hashvals.push_back(Dynobj::gnu_hash(sym->name())); + } + } + + // Put the unhashed symbols at the start of the global portion of + // the dynamic symbol table. + const unsigned int unhashed_count = unhashed_dynsyms.size(); + unsigned int unhashed_dynsym_index = local_dynsym_count; + for (unsigned int i = 0; i < unhashed_count; ++i) + { + unhashed_dynsyms[i]->set_dynsym_index(unhashed_dynsym_index); + ++unhashed_dynsym_index; + } + + // For the actual data generation we call out to a templatized + // function. + int size = target->get_size(); + bool big_endian = target->is_big_endian(); + if (size == 32) + { + if (big_endian) + Dynobj::sized_create_gnu_hash_table<32, true>(hashed_dynsyms, + dynsym_hashvals, + unhashed_dynsym_index, + pphash, + phashlen); + else + Dynobj::sized_create_gnu_hash_table<32, false>(hashed_dynsyms, + dynsym_hashvals, + unhashed_dynsym_index, + pphash, + phashlen); + } + else if (size == 64) + { + if (big_endian) + Dynobj::sized_create_gnu_hash_table<64, true>(hashed_dynsyms, + dynsym_hashvals, + unhashed_dynsym_index, + pphash, + phashlen); + else + Dynobj::sized_create_gnu_hash_table<64, false>(hashed_dynsyms, + dynsym_hashvals, + unhashed_dynsym_index, + pphash, + phashlen); + } + else + gold_unreachable(); +} + +// Create the actual data for a GNU hash table. This is just a copy +// of the code from the old GNU linker. + +template<int size, bool big_endian> +void +Dynobj::sized_create_gnu_hash_table( + const std::vector<Symbol*>& hashed_dynsyms, + const std::vector<uint32_t>& dynsym_hashvals, + unsigned int unhashed_dynsym_count, + unsigned char** pphash, + unsigned int* phashlen) +{ + if (hashed_dynsyms.empty()) + { + // Special case for the empty hash table. + unsigned int hashlen = 5 * 4 + size / 8; + unsigned char* phash = new unsigned char[hashlen]; + // One empty bucket. + elfcpp::Swap<32, big_endian>::writeval(phash, 1); + // Symbol index above unhashed symbols. + elfcpp::Swap<32, big_endian>::writeval(phash + 4, unhashed_dynsym_count); + // One word for bitmask. + elfcpp::Swap<32, big_endian>::writeval(phash + 8, 1); + // Only bloom filter. + elfcpp::Swap<32, big_endian>::writeval(phash + 12, 0); + // No valid hashes. + elfcpp::Swap<size, big_endian>::writeval(phash + 16, 0); + // No hashes in only bucket. + elfcpp::Swap<32, big_endian>::writeval(phash + 16 + size / 8, 0); + + *phashlen = hashlen; + *pphash = phash; + + return; + } + + const unsigned int bucketcount = + Dynobj::compute_bucket_count(dynsym_hashvals, true); + + const unsigned int nsyms = hashed_dynsyms.size(); + + uint32_t maskbitslog2 = 1; + uint32_t x = nsyms >> 1; + while (x != 0) + { + ++maskbitslog2; + x >>= 1; + } + if (maskbitslog2 < 3) + maskbitslog2 = 5; + else if (((1U << (maskbitslog2 - 2)) & nsyms) != 0) + maskbitslog2 += 3; + else + maskbitslog2 += 2; + + uint32_t shift1; + if (size == 32) + shift1 = 5; + else + { + if (maskbitslog2 == 5) + maskbitslog2 = 6; + shift1 = 6; + } + uint32_t mask = (1U << shift1) - 1U; + uint32_t shift2 = maskbitslog2; + uint32_t maskbits = 1U << maskbitslog2; + uint32_t maskwords = 1U << (maskbitslog2 - shift1); + + typedef typename elfcpp::Elf_types<size>::Elf_WXword Word; + std::vector<Word> bitmask(maskwords); + std::vector<uint32_t> counts(bucketcount); + std::vector<uint32_t> indx(bucketcount); + uint32_t symindx = unhashed_dynsym_count; + + // Count the number of times each hash bucket is used. + for (unsigned int i = 0; i < nsyms; ++i) + ++counts[dynsym_hashvals[i] % bucketcount]; + + unsigned int cnt = symindx; + for (unsigned int i = 0; i < bucketcount; ++i) + { + indx[i] = cnt; + cnt += counts[i]; + } + + unsigned int hashlen = (4 + bucketcount + nsyms) * 4; + hashlen += maskbits / 8; + unsigned char* phash = new unsigned char[hashlen]; + + elfcpp::Swap<32, big_endian>::writeval(phash, bucketcount); + elfcpp::Swap<32, big_endian>::writeval(phash + 4, symindx); + elfcpp::Swap<32, big_endian>::writeval(phash + 8, maskwords); + elfcpp::Swap<32, big_endian>::writeval(phash + 12, shift2); + + unsigned char* p = phash + 16 + maskbits / 8; + for (unsigned int i = 0; i < bucketcount; ++i) + { + if (counts[i] == 0) + elfcpp::Swap<32, big_endian>::writeval(p, 0); + else + elfcpp::Swap<32, big_endian>::writeval(p, indx[i]); + p += 4; + } + + for (unsigned int i = 0; i < nsyms; ++i) + { + Symbol* sym = hashed_dynsyms[i]; + uint32_t hashval = dynsym_hashvals[i]; + + unsigned int bucket = hashval % bucketcount; + unsigned int val = ((hashval >> shift1) + & ((maskbits >> shift1) - 1)); + bitmask[val] |= (static_cast<Word>(1U)) << (hashval & mask); + bitmask[val] |= (static_cast<Word>(1U)) << ((hashval >> shift2) & mask); + val = hashval & ~ 1U; + if (counts[bucket] == 1) + { + // Last element terminates the chain. + val |= 1; + } + elfcpp::Swap<32, big_endian>::writeval(p + (indx[bucket] - symindx) * 4, + val); + --counts[bucket]; + + sym->set_dynsym_index(indx[bucket]); + ++indx[bucket]; + } + + p = phash + 16; + for (unsigned int i = 0; i < maskwords; ++i) + { + elfcpp::Swap<size, big_endian>::writeval(p, bitmask[i]); + p += size / 8; + } + + *phashlen = hashlen; + *pphash = phash; +} + +// Verdef methods. + +// Write this definition to a buffer for the output section. + +template<int size, bool big_endian> +unsigned char* +Verdef::write(const Stringpool* dynpool, bool is_last, unsigned char* pb + ACCEPT_SIZE_ENDIAN) const +{ + const int verdef_size = elfcpp::Elf_sizes<size>::verdef_size; + const int verdaux_size = elfcpp::Elf_sizes<size>::verdaux_size; + + elfcpp::Verdef_write<size, big_endian> vd(pb); + vd.set_vd_version(elfcpp::VER_DEF_CURRENT); + vd.set_vd_flags((this->is_base_ ? elfcpp::VER_FLG_BASE : 0) + | (this->is_weak_ ? elfcpp::VER_FLG_WEAK : 0)); + vd.set_vd_ndx(this->index()); + vd.set_vd_cnt(1 + this->deps_.size()); + vd.set_vd_hash(Dynobj::elf_hash(this->name())); + vd.set_vd_aux(verdef_size); + vd.set_vd_next(is_last + ? 0 + : verdef_size + (1 + this->deps_.size()) * verdaux_size); + pb += verdef_size; + + elfcpp::Verdaux_write<size, big_endian> vda(pb); + vda.set_vda_name(dynpool->get_offset(this->name())); + vda.set_vda_next(this->deps_.empty() ? 0 : verdaux_size); + pb += verdaux_size; + + Deps::const_iterator p; + unsigned int i; + for (p = this->deps_.begin(), i = 0; + p != this->deps_.end(); + ++p, ++i) + { + elfcpp::Verdaux_write<size, big_endian> vda(pb); + vda.set_vda_name(dynpool->get_offset(*p)); + vda.set_vda_next(i + 1 >= this->deps_.size() ? 0 : verdaux_size); + pb += verdaux_size; + } + + return pb; +} + +// Verneed methods. + +Verneed::~Verneed() +{ + for (Need_versions::iterator p = this->need_versions_.begin(); + p != this->need_versions_.end(); + ++p) + delete *p; +} + +// Add a new version to this file reference. + +Verneed_version* +Verneed::add_name(const char* name) +{ + Verneed_version* vv = new Verneed_version(name); + this->need_versions_.push_back(vv); + return vv; +} + +// Set the version indexes starting at INDEX. + +unsigned int +Verneed::finalize(unsigned int index) +{ + for (Need_versions::iterator p = this->need_versions_.begin(); + p != this->need_versions_.end(); + ++p) + { + (*p)->set_index(index); + ++index; + } + return index; +} + +// Write this list of referenced versions to a buffer for the output +// section. + +template<int size, bool big_endian> +unsigned char* +Verneed::write(const Stringpool* dynpool, bool is_last, + unsigned char* pb ACCEPT_SIZE_ENDIAN) const +{ + const int verneed_size = elfcpp::Elf_sizes<size>::verneed_size; + const int vernaux_size = elfcpp::Elf_sizes<size>::vernaux_size; + + elfcpp::Verneed_write<size, big_endian> vn(pb); + vn.set_vn_version(elfcpp::VER_NEED_CURRENT); + vn.set_vn_cnt(this->need_versions_.size()); + vn.set_vn_file(dynpool->get_offset(this->filename())); + vn.set_vn_aux(verneed_size); + vn.set_vn_next(is_last + ? 0 + : verneed_size + this->need_versions_.size() * vernaux_size); + pb += verneed_size; + + Need_versions::const_iterator p; + unsigned int i; + for (p = this->need_versions_.begin(), i = 0; + p != this->need_versions_.end(); + ++p, ++i) + { + elfcpp::Vernaux_write<size, big_endian> vna(pb); + vna.set_vna_hash(Dynobj::elf_hash((*p)->version())); + // FIXME: We need to sometimes set VER_FLG_WEAK here. + vna.set_vna_flags(0); + vna.set_vna_other((*p)->index()); + vna.set_vna_name(dynpool->get_offset((*p)->version())); + vna.set_vna_next(i + 1 >= this->need_versions_.size() + ? 0 + : vernaux_size); + pb += vernaux_size; + } + + return pb; +} + +// Versions methods. + +Versions::~Versions() +{ + for (Defs::iterator p = this->defs_.begin(); + p != this->defs_.end(); + ++p) + delete *p; + + for (Needs::iterator p = this->needs_.begin(); + p != this->needs_.end(); + ++p) + delete *p; +} + +// Record version information for a symbol going into the dynamic +// symbol table. + +void +Versions::record_version(const General_options* options, + Stringpool* dynpool, const Symbol* sym) +{ + gold_assert(!this->is_finalized_); + gold_assert(sym->version() != NULL); + + Stringpool::Key version_key; + const char* version = dynpool->add(sym->version(), &version_key); + + if (!sym->is_from_dynobj()) + this->add_def(options, sym, version, version_key); + else + { + // This is a version reference. + + Object* object = sym->object(); + gold_assert(object->is_dynamic()); + Dynobj* dynobj = static_cast<Dynobj*>(object); + + this->add_need(dynpool, dynobj->soname(), version, version_key); + } +} + +// We've found a symbol SYM defined in version VERSION. + +void +Versions::add_def(const General_options* options, const Symbol* sym, + const char* version, Stringpool::Key version_key) +{ + Key k(version_key, 0); + Version_base* const vbnull = NULL; + std::pair<Version_table::iterator, bool> ins = + this->version_table_.insert(std::make_pair(k, vbnull)); + + if (!ins.second) + { + // We already have an entry for this version. + Version_base* vb = ins.first->second; + + // We have now seen a symbol in this version, so it is not + // weak. + vb->clear_weak(); + + // FIXME: When we support version scripts, we will need to + // check whether this symbol should be forced local. + } + else + { + // If we are creating a shared object, it is an error to + // find a definition of a symbol with a version which is not + // in the version script. + if (options->is_shared()) + { + fprintf(stderr, _("%s: symbol %s has undefined version %s\n"), + program_name, sym->name(), version); + gold_exit(false); + } + + // If this is the first version we are defining, first define + // the base version. FIXME: Should use soname here when + // creating a shared object. + Verdef* vdbase = new Verdef(options->output_file_name(), true, false, + true); + this->defs_.push_back(vdbase); + + // When creating a regular executable, automatically define + // a new version. + Verdef* vd = new Verdef(version, false, false, false); + this->defs_.push_back(vd); + ins.first->second = vd; + } +} + +// Add a reference to version NAME in file FILENAME. + +void +Versions::add_need(Stringpool* dynpool, const char* filename, const char* name, + Stringpool::Key name_key) +{ + Stringpool::Key filename_key; + filename = dynpool->add(filename, &filename_key); + + Key k(name_key, filename_key); + Version_base* const vbnull = NULL; + std::pair<Version_table::iterator, bool> ins = + this->version_table_.insert(std::make_pair(k, vbnull)); + + if (!ins.second) + { + // We already have an entry for this filename/version. + return; + } + + // See whether we already have this filename. We don't expect many + // version references, so we just do a linear search. This could be + // replaced by a hash table. + Verneed* vn = NULL; + for (Needs::iterator p = this->needs_.begin(); + p != this->needs_.end(); + ++p) + { + if ((*p)->filename() == filename) + { + vn = *p; + break; + } + } + + if (vn == NULL) + { + // We have a new filename. + vn = new Verneed(filename); + this->needs_.push_back(vn); + } + + ins.first->second = vn->add_name(name); +} + +// Set the version indexes. Create a new dynamic version symbol for +// each new version definition. + +unsigned int +Versions::finalize(const Target* target, Symbol_table* symtab, + unsigned int dynsym_index, std::vector<Symbol*>* syms) +{ + gold_assert(!this->is_finalized_); + + unsigned int vi = 1; + + for (Defs::iterator p = this->defs_.begin(); + p != this->defs_.end(); + ++p) + { + (*p)->set_index(vi); + ++vi; + + // Create a version symbol if necessary. + if (!(*p)->is_symbol_created()) + { + Symbol* vsym = symtab->define_as_constant(target, (*p)->name(), + (*p)->name(), 0, 0, + elfcpp::STT_OBJECT, + elfcpp::STB_GLOBAL, + elfcpp::STV_DEFAULT, 0, + false); + vsym->set_needs_dynsym_entry(); + ++dynsym_index; + syms->push_back(vsym); + // The name is already in the dynamic pool. + } + } + + // Index 1 is used for global symbols. + if (vi == 1) + { + gold_assert(this->defs_.empty()); + vi = 2; + } + + for (Needs::iterator p = this->needs_.begin(); + p != this->needs_.end(); + ++p) + vi = (*p)->finalize(vi); + + this->is_finalized_ = true; + + return dynsym_index; +} + +// Return the version index to use for a symbol. This does two hash +// table lookups: one in DYNPOOL and one in this->version_table_. +// Another approach alternative would be store a pointer in SYM, which +// would increase the size of the symbol table. Or perhaps we could +// use a hash table from dynamic symbol pointer values to Version_base +// pointers. + +unsigned int +Versions::version_index(const Stringpool* dynpool, const Symbol* sym) const +{ + Stringpool::Key version_key; + const char* version = dynpool->find(sym->version(), &version_key); + gold_assert(version != NULL); + + Key k; + if (!sym->is_from_dynobj()) + k = Key(version_key, 0); + else + { + Object* object = sym->object(); + gold_assert(object->is_dynamic()); + Dynobj* dynobj = static_cast<Dynobj*>(object); + + Stringpool::Key filename_key; + const char* filename = dynpool->find(dynobj->soname(), &filename_key); + gold_assert(filename != NULL); + + k = Key(version_key, filename_key); + } + + Version_table::const_iterator p = this->version_table_.find(k); + gold_assert(p != this->version_table_.end()); + + return p->second->index(); +} + +// Return an allocated buffer holding the contents of the symbol +// version section. + +template<int size, bool big_endian> +void +Versions::symbol_section_contents(const Stringpool* dynpool, + unsigned int local_symcount, + const std::vector<Symbol*>& syms, + unsigned char** pp, + unsigned int* psize + ACCEPT_SIZE_ENDIAN) const +{ + gold_assert(this->is_finalized_); + + unsigned int sz = (local_symcount + syms.size()) * 2; + unsigned char* pbuf = new unsigned char[sz]; + + for (unsigned int i = 0; i < local_symcount; ++i) + elfcpp::Swap<16, big_endian>::writeval(pbuf + i * 2, + elfcpp::VER_NDX_LOCAL); + + for (std::vector<Symbol*>::const_iterator p = syms.begin(); + p != syms.end(); + ++p) + { + unsigned int version_index; + const char* version = (*p)->version(); + if (version == NULL) + version_index = elfcpp::VER_NDX_GLOBAL; + else + version_index = this->version_index(dynpool, *p); + elfcpp::Swap<16, big_endian>::writeval(pbuf + (*p)->dynsym_index() * 2, + version_index); + } + + *pp = pbuf; + *psize = sz; +} + +// Return an allocated buffer holding the contents of the version +// definition section. + +template<int size, bool big_endian> +void +Versions::def_section_contents(const Stringpool* dynpool, + unsigned char** pp, unsigned int* psize, + unsigned int* pentries + ACCEPT_SIZE_ENDIAN) const +{ + gold_assert(this->is_finalized_); + gold_assert(!this->defs_.empty()); + + const int verdef_size = elfcpp::Elf_sizes<size>::verdef_size; + const int verdaux_size = elfcpp::Elf_sizes<size>::verdaux_size; + + unsigned int sz = 0; + for (Defs::const_iterator p = this->defs_.begin(); + p != this->defs_.end(); + ++p) + { + sz += verdef_size + verdaux_size; + sz += (*p)->count_dependencies() * verdaux_size; + } + + unsigned char* pbuf = new unsigned char[sz]; + + unsigned char* pb = pbuf; + Defs::const_iterator p; + unsigned int i; + for (p = this->defs_.begin(), i = 0; + p != this->defs_.end(); + ++p, ++i) + pb = (*p)->write SELECT_SIZE_ENDIAN_NAME(size, big_endian)( + dynpool, i + 1 >= this->defs_.size(), pb + SELECT_SIZE_ENDIAN(size, big_endian)); + + gold_assert(static_cast<unsigned int>(pb - pbuf) == sz); + + *pp = pbuf; + *psize = sz; + *pentries = this->defs_.size(); +} + +// Return an allocated buffer holding the contents of the version +// reference section. + +template<int size, bool big_endian> +void +Versions::need_section_contents(const Stringpool* dynpool, + unsigned char** pp, unsigned int *psize, + unsigned int *pentries + ACCEPT_SIZE_ENDIAN) const +{ + gold_assert(this->is_finalized_); + gold_assert(!this->needs_.empty()); + + const int verneed_size = elfcpp::Elf_sizes<size>::verneed_size; + const int vernaux_size = elfcpp::Elf_sizes<size>::vernaux_size; + + unsigned int sz = 0; + for (Needs::const_iterator p = this->needs_.begin(); + p != this->needs_.end(); + ++p) + { + sz += verneed_size; + sz += (*p)->count_versions() * vernaux_size; + } + + unsigned char* pbuf = new unsigned char[sz]; + + unsigned char* pb = pbuf; + Needs::const_iterator p; + unsigned int i; + for (p = this->needs_.begin(), i = 0; + p != this->needs_.end(); + ++p, ++i) + pb = (*p)->write SELECT_SIZE_ENDIAN_NAME(size, big_endian)( + dynpool, i + 1 >= this->needs_.size(), pb + SELECT_SIZE_ENDIAN(size, big_endian)); + + gold_assert(static_cast<unsigned int>(pb - pbuf) == sz); + + *pp = pbuf; + *psize = sz; + *pentries = this->needs_.size(); +} + +// Instantiate the templates we need. We could use the configure +// script to restrict this to only the ones for implemented targets. + +template +class Sized_dynobj<32, false>; + +template +class Sized_dynobj<32, true>; + +template +class Sized_dynobj<64, false>; + +template +class Sized_dynobj<64, true>; + +template +void +Versions::symbol_section_contents<32, false>( + const Stringpool*, + unsigned int, + const std::vector<Symbol*>&, + unsigned char**, + unsigned int* + ACCEPT_SIZE_ENDIAN_EXPLICIT(32, false)) const; + +template +void +Versions::symbol_section_contents<32, true>( + const Stringpool*, + unsigned int, + const std::vector<Symbol*>&, + unsigned char**, + unsigned int* + ACCEPT_SIZE_ENDIAN_EXPLICIT(32, true)) const; + +template +void +Versions::symbol_section_contents<64, false>( + const Stringpool*, + unsigned int, + const std::vector<Symbol*>&, + unsigned char**, + unsigned int* + ACCEPT_SIZE_ENDIAN_EXPLICIT(64, false)) const; + +template +void +Versions::symbol_section_contents<64, true>( + const Stringpool*, + unsigned int, + const std::vector<Symbol*>&, + unsigned char**, + unsigned int* + ACCEPT_SIZE_ENDIAN_EXPLICIT(64, true)) const; + +template +void +Versions::def_section_contents<32, false>( + const Stringpool*, + unsigned char**, + unsigned int*, + unsigned int* + ACCEPT_SIZE_ENDIAN_EXPLICIT(32, false)) const; + +template +void +Versions::def_section_contents<32, true>( + const Stringpool*, + unsigned char**, + unsigned int*, + unsigned int* + ACCEPT_SIZE_ENDIAN_EXPLICIT(32, true)) const; + +template +void +Versions::def_section_contents<64, false>( + const Stringpool*, + unsigned char**, + unsigned int*, + unsigned int* + ACCEPT_SIZE_ENDIAN_EXPLICIT(64, false)) const; + +template +void +Versions::def_section_contents<64, true>( + const Stringpool*, + unsigned char**, + unsigned int*, + unsigned int* + ACCEPT_SIZE_ENDIAN_EXPLICIT(64, true)) const; + +template +void +Versions::need_section_contents<32, false>( + const Stringpool*, + unsigned char**, + unsigned int*, + unsigned int* + ACCEPT_SIZE_ENDIAN_EXPLICIT(32, false)) const; + +template +void +Versions::need_section_contents<32, true>( + const Stringpool*, + unsigned char**, + unsigned int*, + unsigned int* + ACCEPT_SIZE_ENDIAN_EXPLICIT(32, true)) const; + +template +void +Versions::need_section_contents<64, false>( + const Stringpool*, + unsigned char**, + unsigned int*, + unsigned int* + ACCEPT_SIZE_ENDIAN_EXPLICIT(64, false)) const; + +template +void +Versions::need_section_contents<64, true>( + const Stringpool*, + unsigned char**, + unsigned int*, + unsigned int* + ACCEPT_SIZE_ENDIAN_EXPLICIT(64, true)) const; + +} // End namespace gold. |