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binutils-gdb/gold/dynobj.cc
Ian Lance Taylor 008db82ec1 Don't emit symbols seen only in dynamic object, don't read duplicate 
dynamic object.
2006-12-06 06:28:56 +00:00

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// 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.
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