#include "gold.h"
+#include <cerrno>
#include <cstring>
#include <algorithm>
#include <iostream>
#include <utility>
+#include <fcntl.h>
+#include <unistd.h>
+#include "libiberty.h"
+#include "md5.h"
+#include "sha1.h"
#include "parameters.h"
#include "options.h"
: options_(options), script_options_(script_options), namepool_(),
sympool_(), dynpool_(), signatures_(),
section_name_map_(), segment_list_(), section_list_(),
- unattached_section_list_(), special_output_list_(),
- section_headers_(NULL), tls_segment_(NULL), symtab_section_(NULL),
- dynsym_section_(NULL), dynamic_section_(NULL), dynamic_data_(NULL),
- eh_frame_section_(NULL), group_signatures_(), output_file_size_(-1),
+ unattached_section_list_(), sections_are_attached_(false),
+ special_output_list_(), section_headers_(NULL), tls_segment_(NULL),
+ symtab_section_(NULL), dynsym_section_(NULL), dynamic_section_(NULL),
+ dynamic_data_(NULL), eh_frame_section_(NULL), eh_frame_data_(NULL),
+ added_eh_frame_data_(false), eh_frame_hdr_section_(NULL),
+ build_id_note_(NULL), group_signatures_(), output_file_size_(-1),
input_requires_executable_stack_(false),
input_with_gnu_stack_note_(false),
input_without_gnu_stack_note_(false),
Layout::get_output_section(const char* name, Stringpool::Key name_key,
elfcpp::Elf_Word type, elfcpp::Elf_Xword flags)
{
- const Key key(name_key, std::make_pair(type, flags));
+ elfcpp::Elf_Xword lookup_flags = flags;
+
+ // Ignoring SHF_WRITE and SHF_EXECINSTR here means that we combine
+ // read-write with read-only sections. Some other ELF linkers do
+ // not do this. FIXME: Perhaps there should be an option
+ // controlling this.
+ lookup_flags &= ~(elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR);
+
+ const Key key(name_key, std::make_pair(type, lookup_flags));
const std::pair<Key, Output_section*> v(key, NULL);
std::pair<Section_name_map::iterator, bool> ins(
this->section_name_map_.insert(v));
else
{
// This is the first time we've seen this name/type/flags
- // combination. If the section has contents but no flags, then
- // see whether we have an existing section with the same name.
- // This is a workaround for cases where assembler code forgets
- // to set section flags, and the GNU linker would simply pick an
- // existing section with the same name. FIXME: Perhaps there
- // should be an option to control this.
+ // combination. For compatibility with the GNU linker, we
+ // combine sections with contents and zero flags with sections
+ // with non-zero flags. This is a workaround for cases where
+ // assembler code forgets to set section flags. FIXME: Perhaps
+ // there should be an option to control this.
Output_section* os = NULL;
- if (type == elfcpp::SHT_PROGBITS && flags == 0)
+
+ if (type == elfcpp::SHT_PROGBITS)
{
- os = this->find_output_section(name);
- if (os != NULL && os->type() != elfcpp::SHT_PROGBITS)
- os = NULL;
+ if (flags == 0)
+ {
+ Output_section* same_name = this->find_output_section(name);
+ if (same_name != NULL
+ && same_name->type() == elfcpp::SHT_PROGBITS
+ && (same_name->flags() & elfcpp::SHF_TLS) == 0)
+ os = same_name;
+ }
+ else if ((flags & elfcpp::SHF_TLS) == 0)
+ {
+ elfcpp::Elf_Xword zero_flags = 0;
+ const Key zero_key(name_key, std::make_pair(type, zero_flags));
+ Section_name_map::iterator p =
+ this->section_name_map_.find(zero_key);
+ if (p != this->section_name_map_.end())
+ os = p->second;
+ }
}
+
if (os == NULL)
os = this->make_output_section(name, type, flags);
ins.first->second = os;
// Pick the output section to use for section NAME, in input file
// RELOBJ, with type TYPE and flags FLAGS. RELOBJ may be NULL for a
-// linker created section. ADJUST_NAME is true if we should apply the
-// standard name mappings in Layout::output_section_name. This will
-// return NULL if the input section should be discarded.
+// linker created section. IS_INPUT_SECTION is true if we are
+// choosing an output section for an input section found in a input
+// file. This will return NULL if the input section should be
+// discarded.
Output_section*
Layout::choose_output_section(const Relobj* relobj, const char* name,
elfcpp::Elf_Word type, elfcpp::Elf_Xword flags,
- bool adjust_name)
+ bool is_input_section)
{
- // We should ignore some flags. FIXME: This will need some
- // adjustment for ld -r.
+ // We should not see any input sections after we have attached
+ // sections to segments.
+ gold_assert(!is_input_section || !this->sections_are_attached_);
+
+ // Some flags in the input section should not be automatically
+ // copied to the output section.
flags &= ~ (elfcpp::SHF_INFO_LINK
| elfcpp::SHF_LINK_ORDER
| elfcpp::SHF_GROUP
// output section.
size_t len = strlen(name);
- if (adjust_name && !parameters->options().relocatable())
+ if (is_input_section && !parameters->options().relocatable())
name = Layout::output_section_name(name, &len);
Stringpool::Key name_key;
return NULL;
}
+ // By default the GNU linker sorts input sections whose names match
+ // .ctor.*, .dtor.*, .init_array.*, or .fini_array.*. The sections
+ // are sorted by name. This is used to implement constructor
+ // priority ordering. We are compatible.
+ if (!this->script_options_->saw_sections_clause()
+ && (is_prefix_of(".ctors.", name)
+ || is_prefix_of(".dtors.", name)
+ || is_prefix_of(".init_array.", name)
+ || is_prefix_of(".fini_array.", name)))
+ os->set_must_sort_attached_input_sections();
+
// FIXME: Handle SHF_LINK_ORDER somewhere.
*off = os->add_input_section(object, shndx, name, shdr, reloc_shndx,
off_t* off)
{
gold_assert(shdr.get_sh_type() == elfcpp::SHT_PROGBITS);
- gold_assert(shdr.get_sh_flags() == elfcpp::SHF_ALLOC);
+ gold_assert((shdr.get_sh_flags() & elfcpp::SHF_ALLOC) != 0);
const char* const name = ".eh_frame";
Output_section* os = this->choose_output_section(object,
{
this->eh_frame_section_ = os;
this->eh_frame_data_ = new Eh_frame();
- os->add_output_section_data(this->eh_frame_data_);
if (this->options_.eh_frame_hdr())
{
shndx,
reloc_shndx,
reloc_type))
- *off = -1;
+ {
+ os->update_flags_for_input_section(shdr.get_sh_flags());
+
+ // We found a .eh_frame section we are going to optimize, so now
+ // we can add the set of optimized sections to the output
+ // section. We need to postpone adding this until we've found a
+ // section we can optimize so that the .eh_frame section in
+ // crtbegin.o winds up at the start of the output section.
+ if (!this->added_eh_frame_data_)
+ {
+ os->add_output_section_data(this->eh_frame_data_);
+ this->added_eh_frame_data_ = true;
+ }
+ *off = -1;
+ }
else
{
// We couldn't handle this .eh_frame section for some reason.
this->section_list_.push_back(os);
- if ((flags & elfcpp::SHF_ALLOC) == 0)
+ // The GNU linker by default sorts some sections by priority, so we
+ // do the same. We need to know that this might happen before we
+ // attach any input sections.
+ if (!this->script_options_->saw_sections_clause()
+ && (strcmp(name, ".ctors") == 0
+ || strcmp(name, ".dtors") == 0
+ || strcmp(name, ".init_array") == 0
+ || strcmp(name, ".fini_array") == 0))
+ os->set_may_sort_attached_input_sections();
+
+ // If we have already attached the sections to segments, then we
+ // need to attach this one now. This happens for sections created
+ // directly by the linker.
+ if (this->sections_are_attached_)
+ this->attach_section_to_segment(os);
+
+ return os;
+}
+
+// Attach output sections to segments. This is called after we have
+// seen all the input sections.
+
+void
+Layout::attach_sections_to_segments()
+{
+ for (Section_list::iterator p = this->section_list_.begin();
+ p != this->section_list_.end();
+ ++p)
+ this->attach_section_to_segment(*p);
+
+ this->sections_are_attached_ = true;
+}
+
+// Attach an output section to a segment.
+
+void
+Layout::attach_section_to_segment(Output_section* os)
+{
+ if ((os->flags() & elfcpp::SHF_ALLOC) == 0)
this->unattached_section_list_.push_back(os);
else
- {
- if (parameters->options().relocatable())
- return os;
+ this->attach_allocated_section_to_segment(os);
+}
- // If we have a SECTIONS clause, we can't handle the attachment
- // to segments until after we've seen all the sections.
- if (this->script_options_->saw_sections_clause())
- return os;
+// Attach an allocated output section to a segment.
- gold_assert(!this->script_options_->saw_phdrs_clause());
+void
+Layout::attach_allocated_section_to_segment(Output_section* os)
+{
+ elfcpp::Elf_Xword flags = os->flags();
+ gold_assert((flags & elfcpp::SHF_ALLOC) != 0);
- // This output section goes into a PT_LOAD segment.
+ if (parameters->options().relocatable())
+ return;
- elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags);
+ // If we have a SECTIONS clause, we can't handle the attachment to
+ // segments until after we've seen all the sections.
+ if (this->script_options_->saw_sections_clause())
+ return;
- // In general the only thing we really care about for PT_LOAD
- // segments is whether or not they are writable, so that is how
- // we search for them. People who need segments sorted on some
- // other basis will have to use a linker script.
+ gold_assert(!this->script_options_->saw_phdrs_clause());
- Segment_list::const_iterator p;
- for (p = this->segment_list_.begin();
- p != this->segment_list_.end();
- ++p)
- {
- if ((*p)->type() == elfcpp::PT_LOAD
- && ((*p)->flags() & elfcpp::PF_W) == (seg_flags & elfcpp::PF_W))
- {
- // If -Tbss was specified, we need to separate the data
- // and BSS segments.
- if (this->options_.user_set_Tbss())
- {
- if ((type == elfcpp::SHT_NOBITS)
- == (*p)->has_any_data_sections())
- continue;
- }
+ // This output section goes into a PT_LOAD segment.
- (*p)->add_output_section(os, seg_flags);
- break;
- }
- }
+ elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags);
- if (p == this->segment_list_.end())
- {
- Output_segment* oseg = this->make_output_segment(elfcpp::PT_LOAD,
- seg_flags);
- oseg->add_output_section(os, seg_flags);
- }
+ // In general the only thing we really care about for PT_LOAD
+ // segments is whether or not they are writable, so that is how we
+ // search for them. People who need segments sorted on some other
+ // basis will have to use a linker script.
- // If we see a loadable SHT_NOTE section, we create a PT_NOTE
- // segment.
- if (type == elfcpp::SHT_NOTE)
- {
- // See if we already have an equivalent PT_NOTE segment.
- for (p = this->segment_list_.begin();
- p != segment_list_.end();
- ++p)
- {
- if ((*p)->type() == elfcpp::PT_NOTE
- && (((*p)->flags() & elfcpp::PF_W)
- == (seg_flags & elfcpp::PF_W)))
- {
- (*p)->add_output_section(os, seg_flags);
- break;
- }
- }
+ Segment_list::const_iterator p;
+ for (p = this->segment_list_.begin();
+ p != this->segment_list_.end();
+ ++p)
+ {
+ if ((*p)->type() == elfcpp::PT_LOAD
+ && ((*p)->flags() & elfcpp::PF_W) == (seg_flags & elfcpp::PF_W))
+ {
+ // If -Tbss was specified, we need to separate the data
+ // and BSS segments.
+ if (this->options_.user_set_Tbss())
+ {
+ if ((os->type() == elfcpp::SHT_NOBITS)
+ == (*p)->has_any_data_sections())
+ continue;
+ }
- if (p == this->segment_list_.end())
- {
- Output_segment* oseg = this->make_output_segment(elfcpp::PT_NOTE,
- seg_flags);
- oseg->add_output_section(os, seg_flags);
- }
- }
+ (*p)->add_output_section(os, seg_flags);
+ break;
+ }
+ }
- // If we see a loadable SHF_TLS section, we create a PT_TLS
- // segment. There can only be one such segment.
- if ((flags & elfcpp::SHF_TLS) != 0)
- {
- if (this->tls_segment_ == NULL)
- this->tls_segment_ = this->make_output_segment(elfcpp::PT_TLS,
- seg_flags);
- this->tls_segment_->add_output_section(os, seg_flags);
- }
+ if (p == this->segment_list_.end())
+ {
+ Output_segment* oseg = this->make_output_segment(elfcpp::PT_LOAD,
+ seg_flags);
+ oseg->add_output_section(os, seg_flags);
}
- return os;
+ // If we see a loadable SHT_NOTE section, we create a PT_NOTE
+ // segment.
+ if (os->type() == elfcpp::SHT_NOTE)
+ {
+ // See if we already have an equivalent PT_NOTE segment.
+ for (p = this->segment_list_.begin();
+ p != segment_list_.end();
+ ++p)
+ {
+ if ((*p)->type() == elfcpp::PT_NOTE
+ && (((*p)->flags() & elfcpp::PF_W)
+ == (seg_flags & elfcpp::PF_W)))
+ {
+ (*p)->add_output_section(os, seg_flags);
+ break;
+ }
+ }
+
+ if (p == this->segment_list_.end())
+ {
+ Output_segment* oseg = this->make_output_segment(elfcpp::PT_NOTE,
+ seg_flags);
+ oseg->add_output_section(os, seg_flags);
+ }
+ }
+
+ // If we see a loadable SHF_TLS section, we create a PT_TLS
+ // segment. There can only be one such segment.
+ if ((flags & elfcpp::SHF_TLS) != 0)
+ {
+ if (this->tls_segment_ == NULL)
+ this->tls_segment_ = this->make_output_segment(elfcpp::PT_TLS,
+ seg_flags);
+ this->tls_segment_->add_output_section(os, seg_flags);
+ }
}
// Make an output section for a script.
this->create_gold_note();
this->create_executable_stack_info(target);
+ this->create_build_id();
Output_segment* phdr_seg = NULL;
if (!parameters->options().relocatable() && !parameters->doing_static_link())
return off;
}
-// Create a .note section for an executable or shared library. This
-// records the version of gold used to create the binary.
+// Create a note header following the format defined in the ELF ABI.
+// NAME is the name, NOTE_TYPE is the type, DESCSZ is the size of the
+// descriptor. ALLOCATE is true if the section should be allocated in
+// memory. This returns the new note section. It sets
+// *TRAILING_PADDING to the number of trailing zero bytes required.
-void
-Layout::create_gold_note()
+Output_section*
+Layout::create_note(const char* name, int note_type, size_t descsz,
+ bool allocate, size_t* trailing_padding)
{
- if (parameters->options().relocatable())
- return;
-
// Authorities all agree that the values in a .note field should
// be aligned on 4-byte boundaries for 32-bit binaries. However,
// they differ on what the alignment is for 64-bit binaries.
#endif
// The contents of the .note section.
- const char* name = "GNU";
- std::string desc(std::string("gold ") + gold::get_version_string());
size_t namesz = strlen(name) + 1;
size_t aligned_namesz = align_address(namesz, size / 8);
- size_t descsz = desc.length() + 1;
size_t aligned_descsz = align_address(descsz, size / 8);
- const int note_type = 4;
- size_t notesz = 3 * (size / 8) + aligned_namesz + aligned_descsz;
+ size_t notehdrsz = 3 * (size / 8) + aligned_namesz;
- unsigned char buffer[128];
- gold_assert(sizeof buffer >= notesz);
- memset(buffer, 0, notesz);
+ unsigned char* buffer = new unsigned char[notehdrsz];
+ memset(buffer, 0, notehdrsz);
bool is_big_endian = parameters->target().is_big_endian();
gold_unreachable();
memcpy(buffer + 3 * (size / 8), name, namesz);
- memcpy(buffer + 3 * (size / 8) + aligned_namesz, desc.data(), descsz);
const char* note_name = this->namepool_.add(".note", false, NULL);
+ elfcpp::Elf_Xword flags = 0;
+ if (allocate)
+ flags = elfcpp::SHF_ALLOC;
Output_section* os = this->make_output_section(note_name,
elfcpp::SHT_NOTE,
- 0);
- Output_section_data* posd = new Output_data_const(buffer, notesz,
- size / 8);
+ flags);
+ Output_section_data* posd = new Output_data_const_buffer(buffer, notehdrsz,
+ size / 8);
os->add_output_section_data(posd);
+
+ *trailing_padding = aligned_descsz - descsz;
+
+ return os;
+}
+
+// For an executable or shared library, create a note to record the
+// version of gold used to create the binary.
+
+void
+Layout::create_gold_note()
+{
+ if (parameters->options().relocatable())
+ return;
+
+ std::string desc = std::string("gold ") + gold::get_version_string();
+
+ size_t trailing_padding;
+ Output_section *os = this->create_note("GNU", elfcpp::NT_GNU_GOLD_VERSION,
+ desc.size(), false, &trailing_padding);
+
+ Output_section_data* posd = new Output_data_const(desc, 4);
+ os->add_output_section_data(posd);
+
+ if (trailing_padding > 0)
+ {
+ posd = new Output_data_fixed_space(trailing_padding, 0);
+ os->add_output_section_data(posd);
+ }
}
// Record whether the stack should be executable. This can be set
}
}
+// If --build-id was used, set up the build ID note.
+
+void
+Layout::create_build_id()
+{
+ if (!parameters->options().user_set_build_id())
+ return;
+
+ const char* style = parameters->options().build_id();
+ if (strcmp(style, "none") == 0)
+ return;
+
+ // Set DESCSZ to the size of the note descriptor. When possible,
+ // set DESC to the note descriptor contents.
+ size_t descsz;
+ std::string desc;
+ if (strcmp(style, "md5") == 0)
+ descsz = 128 / 8;
+ else if (strcmp(style, "sha1") == 0)
+ descsz = 160 / 8;
+ else if (strcmp(style, "uuid") == 0)
+ {
+ const size_t uuidsz = 128 / 8;
+
+ char buffer[uuidsz];
+ memset(buffer, 0, uuidsz);
+
+ int descriptor = ::open("/dev/urandom", O_RDONLY);
+ if (descriptor < 0)
+ gold_error(_("--build-id=uuid failed: could not open /dev/urandom: %s"),
+ strerror(errno));
+ else
+ {
+ ssize_t got = ::read(descriptor, buffer, uuidsz);
+ ::close(descriptor);
+ if (got < 0)
+ gold_error(_("/dev/urandom: read failed: %s"), strerror(errno));
+ else if (static_cast<size_t>(got) != uuidsz)
+ gold_error(_("/dev/urandom: expected %zu bytes, got %zd bytes"),
+ uuidsz, got);
+ }
+
+ desc.assign(buffer, uuidsz);
+ descsz = uuidsz;
+ }
+ else if (strncmp(style, "0x", 2) == 0)
+ {
+ hex_init();
+ const char* p = style + 2;
+ while (*p != '\0')
+ {
+ if (hex_p(p[0]) && hex_p(p[1]))
+ {
+ char c = (hex_value(p[0]) << 4) | hex_value(p[1]);
+ desc += c;
+ p += 2;
+ }
+ else if (*p == '-' || *p == ':')
+ ++p;
+ else
+ gold_fatal(_("--build-id argument '%s' not a valid hex number"),
+ style);
+ }
+ descsz = desc.size();
+ }
+ else
+ gold_fatal(_("unrecognized --build-id argument '%s'"), style);
+
+ // Create the note.
+ size_t trailing_padding;
+ Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_BUILD_ID,
+ descsz, true, &trailing_padding);
+
+ if (!desc.empty())
+ {
+ // We know the value already, so we fill it in now.
+ gold_assert(desc.size() == descsz);
+
+ Output_section_data* posd = new Output_data_const(desc, 4);
+ os->add_output_section_data(posd);
+
+ if (trailing_padding != 0)
+ {
+ posd = new Output_data_fixed_space(trailing_padding, 0);
+ os->add_output_section_data(posd);
+ }
+ }
+ else
+ {
+ // We need to compute a checksum after we have completed the
+ // link.
+ gold_assert(trailing_padding == 0);
+ this->build_id_note_ = new Output_data_fixed_space(descsz, 4);
+ os->add_output_section_data(this->build_id_note_);
+ os->set_after_input_sections();
+ }
+}
+
// Return whether SEG1 should be before SEG2 in the output file. This
// is based entirely on the segment type and flags. When this is
// called the segment addresses has normally not yet been set.
}
unsigned int shndx_hold = *pshndx;
- uint64_t new_addr = (*p)->set_section_addresses(false, addr, &off,
- pshndx);
+ uint64_t new_addr = (*p)->set_section_addresses(this, false, addr,
+ &off, pshndx);
// Now that we know the size of this segment, we may be able
// to save a page in memory, at the cost of wasting some
addr = align_address(aligned_addr, common_pagesize);
addr = align_address(addr, (*p)->maximum_alignment());
off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1));
- new_addr = (*p)->set_section_addresses(true, addr, &off,
- pshndx);
+ new_addr = (*p)->set_section_addresses(this, true, addr,
+ &off, pshndx);
}
}
this->section_headers_->write(of);
}
+// If the build ID requires computing a checksum, do so here, and
+// write it out. We compute a checksum over the entire file because
+// that is simplest.
+
+void
+Layout::write_build_id(Output_file* of) const
+{
+ if (this->build_id_note_ == NULL)
+ return;
+
+ const unsigned char* iv = of->get_input_view(0, this->output_file_size_);
+
+ unsigned char* ov = of->get_output_view(this->build_id_note_->offset(),
+ this->build_id_note_->data_size());
+
+ const char* style = parameters->options().build_id();
+ if (strcmp(style, "sha1") == 0)
+ {
+ sha1_ctx ctx;
+ sha1_init_ctx(&ctx);
+ sha1_process_bytes(iv, this->output_file_size_, &ctx);
+ sha1_finish_ctx(&ctx, ov);
+ }
+ else if (strcmp(style, "md5") == 0)
+ {
+ md5_ctx ctx;
+ md5_init_ctx(&ctx);
+ md5_process_bytes(iv, this->output_file_size_, &ctx);
+ md5_finish_ctx(&ctx, ov);
+ }
+ else
+ gold_unreachable();
+
+ of->write_output_view(this->build_id_note_->offset(),
+ this->build_id_note_->data_size(),
+ ov);
+
+ of->free_input_view(0, this->output_file_size_, iv);
+}
+
// Write out a binary file. This is called after the link is
// complete. IN is the temporary output file we used to generate the
// ELF code. We simply walk through the segments, read them from
void
Close_task_runner::run(Workqueue*, const Task*)
{
+ // If we need to compute a checksum for the BUILD if, we do so here.
+ this->layout_->write_build_id(this->of_);
+
// If we've been asked to create a binary file, we do so here.
if (this->options_->oformat_enum() != General_options::OBJECT_FORMAT_ELF)
this->layout_->write_binary(this->of_);