X-Git-Url: http://git.efficios.com/?a=blobdiff_plain;f=gold%2Fdynobj.cc;h=ac5a74b1c6899aea6fd2b4bb8fd99da58a83dd85;hb=a3ad94edd406b9abc26493761764d4034dda69fa;hp=ba1fb151a3870fdf5429312dc4305d827688735a;hpb=e1da3f5b9645750e966e471ff0db480d6450dcb7;p=deliverable%2Fbinutils-gdb.git diff --git a/gold/dynobj.cc b/gold/dynobj.cc index ba1fb151a3..ac5a74b1c6 100644 --- a/gold/dynobj.cc +++ b/gold/dynobj.cc @@ -5,12 +5,25 @@ #include #include +#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 @@ -20,8 +33,7 @@ Sized_dynobj::Sized_dynobj( off_t offset, const elfcpp::Ehdr& ehdr) : Dynobj(name, input_file, offset), - elf_file_(this, ehdr), - soname_() + elf_file_(this, ehdr) { } @@ -130,7 +142,7 @@ Sized_dynobj::read_dynsym_section( typename This::Shdr shdr(pshdrs + shndx * This::shdr_size); - assert(shdr.get_sh_type() == type); + gold_assert(shdr.get_sh_type() == type); if (shdr.get_sh_link() != link) { @@ -146,11 +158,11 @@ Sized_dynobj::read_dynsym_section( *view_info = shdr.get_sh_info(); } -// Set soname_ 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. +// 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 void @@ -161,7 +173,7 @@ Sized_dynobj::set_soname(const unsigned char* pshdrs, off_t strtab_size) { typename This::Shdr dynamicshdr(pshdrs + dynamic_shndx * This::shdr_size); - assert(dynamicshdr.get_sh_type() == elfcpp::SHT_DYNAMIC); + 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(), @@ -214,7 +226,7 @@ Sized_dynobj::set_soname(const unsigned char* pshdrs, } const char* strtab = reinterpret_cast(strtabu); - this->soname_ = std::string(strtab + val); + this->set_soname_string(strtab + val); return; } @@ -259,7 +271,7 @@ Sized_dynobj::do_read_symbols(Read_symbols_data* sd) { // Get the dynamic symbols. typename This::Shdr dynsymshdr(pshdrs + dynsym_shndx * This::shdr_size); - assert(dynsymshdr.get_sh_type() == elfcpp::SHT_DYNSYM); + gold_assert(dynsymshdr.get_sh_type() == elfcpp::SHT_DYNSYM); sd->symbols = this->get_lasting_view(dynsymshdr.get_sh_offset(), dynsymshdr.get_sh_size()); @@ -380,7 +392,7 @@ Sized_dynobj::set_version_map( unsigned int ndx, const char* name) const { - assert(ndx < version_map->size()); + gold_assert(ndx < version_map->size()); if ((*version_map)[ndx] != NULL) { fprintf(stderr, _("%s: %s: duplicate definition for version %u\n"), @@ -602,8 +614,9 @@ Sized_dynobj::do_add_symbols(Symbol_table* symtab, { if (sd->symbols == NULL) { - assert(sd->symbol_names == NULL); - assert(sd->versym == NULL && sd->verdef == NULL && sd->verneed == NULL); + gold_assert(sd->symbol_names == NULL); + gold_assert(sd->versym == NULL && sd->verdef == NULL + && sd->verneed == NULL); return; } @@ -652,6 +665,400 @@ Sized_dynobj::do_add_symbols(Symbol_table* symtab, } } +// Given a vector of hash codes, compute the number of hash buckets to +// use. + +unsigned int +Dynobj::compute_bucket_count(const std::vector& 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(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& 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 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 bucket(bucketcount); + std::vector 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(bucket, chain, phash, hashlen); + else + Dynobj::sized_create_elf_hash_table(bucket, chain, phash, hashlen); + + *pphash = phash; + *phashlen = hashlen; +} + +// Fill in an ELF hash table. + +template +void +Dynobj::sized_create_elf_hash_table(const std::vector& bucket, + const std::vector& 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(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(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& 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 unhashed_dynsyms; + unhashed_dynsyms.reserve(count); + + std::vector hashed_dynsyms; + hashed_dynsyms.reserve(count); + + std::vector 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 +void +Dynobj::sized_create_gnu_hash_table( + const std::vector& hashed_dynsyms, + const std::vector& 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::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::Elf_WXword Word; + std::vector bitmask(maskwords); + std::vector counts(bucketcount); + std::vector 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(1U)) << (hashval & mask); + bitmask[val] |= (static_cast(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::writeval(p, bitmask[i]); + p += size / 8; + } + + *phashlen = hashlen; + *pphash = phash; +} + // Instantiate the templates we need. We could use the configure // script to restrict this to only the ones for implemented targets.