// layout.cc -- lay out output file sections for gold
-// Copyright 2006, 2007, 2008, 2009, 2010, 2011, 2012
+// Copyright 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013
// Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.
program_name, Free_list::num_allocate_visits);
}
+// A Hash_task computes the MD5 checksum of an array of char.
+// It has a blocker on either side (i.e., the task cannot run until
+// the first is unblocked, and it unblocks the second after running).
+
+class Hash_task : public Task
+{
+ public:
+ Hash_task(const unsigned char* src,
+ size_t size,
+ unsigned char* dst,
+ Task_token* build_id_blocker,
+ Task_token* final_blocker)
+ : src_(src), size_(size), dst_(dst), build_id_blocker_(build_id_blocker),
+ final_blocker_(final_blocker)
+ { }
+
+ void
+ run(Workqueue*)
+ { md5_buffer(reinterpret_cast<const char*>(src_), size_, dst_); }
+
+ Task_token*
+ is_runnable();
+
+ // Unblock FINAL_BLOCKER_ when done.
+ void
+ locks(Task_locker* tl)
+ { tl->add(this, this->final_blocker_); }
+
+ std::string
+ get_name() const
+ { return "Hash_task"; }
+
+ private:
+ const unsigned char* const src_;
+ const size_t size_;
+ unsigned char* const dst_;
+ Task_token* const build_id_blocker_;
+ Task_token* const final_blocker_;
+};
+
+Task_token*
+Hash_task::is_runnable()
+{
+ if (this->build_id_blocker_->is_blocked())
+ return this->build_id_blocker_;
+ return NULL;
+}
+
// Layout::Relaxation_debug_check methods.
// Check that sections and special data are in reset states.
void
Layout::Relaxation_debug_check::check_output_data_for_reset_values(
const Layout::Section_list& sections,
- const Layout::Data_list& special_outputs)
+ const Layout::Data_list& special_outputs,
+ const Layout::Data_list& relax_outputs)
{
for(Layout::Section_list::const_iterator p = sections.begin();
p != sections.end();
p != special_outputs.end();
++p)
gold_assert((*p)->address_and_file_offset_have_reset_values());
+
+ gold_assert(relax_outputs.empty());
}
// Save information of SECTIONS for checking later.
void
Layout_task_runner::run(Workqueue* workqueue, const Task* task)
{
+ // See if any of the input definitions violate the One Definition Rule.
+ // TODO: if this is too slow, do this as a task, rather than inline.
+ this->symtab_->detect_odr_violations(task, this->options_.output_file_name());
+
Layout* layout = this->layout_;
off_t file_size = layout->finalize(this->input_objects_,
this->symtab_,
section_list_(),
unattached_section_list_(),
special_output_list_(),
+ relax_output_list_(),
section_headers_(NULL),
tls_segment_(NULL),
relro_segment_(NULL),
eh_frame_hdr_section_(NULL),
gdb_index_data_(NULL),
build_id_note_(NULL),
+ array_of_hashes_(NULL),
+ size_of_array_of_hashes_(0),
+ input_view_(NULL),
debug_abbrev_(NULL),
debug_info_(NULL),
group_signatures_(),
return os;
}
+// Return the index by which an input section should be ordered. This
+// is used to sort some .text sections, for compatibility with GNU ld.
+
+int
+Layout::special_ordering_of_input_section(const char* name)
+{
+ // The GNU linker has some special handling for some sections that
+ // wind up in the .text section. Sections that start with these
+ // prefixes must appear first, and must appear in the order listed
+ // here.
+ static const char* const text_section_sort[] =
+ {
+ ".text.unlikely",
+ ".text.exit",
+ ".text.startup",
+ ".text.hot"
+ };
+
+ for (size_t i = 0;
+ i < sizeof(text_section_sort) / sizeof(text_section_sort[0]);
+ i++)
+ if (is_prefix_of(text_section_sort[i], name))
+ return i;
+
+ return -1;
+}
+
// Return the output section to use for input section SHNDX, with name
// NAME, with header HEADER, from object OBJECT. RELOC_SHNDX is the
// index of a relocation section which applies to this section, or 0
= this->section_segment_map_.find(Const_section_id(object, shndx));
if (it == this->section_segment_map_.end())
{
- os = this->choose_output_section(object, name, sh_type,
+ os = this->choose_output_section(object, name, sh_type,
shdr.get_sh_flags(), true,
ORDER_INVALID, false);
}
|| strcmp(name, ".dtors") == 0))))
os->set_must_sort_attached_input_sections();
+ // By default the GNU linker sorts some special text sections ahead
+ // of others. We are compatible.
+ if (parameters->options().text_reorder()
+ && !this->script_options_->saw_sections_clause()
+ && !this->is_section_ordering_specified()
+ && !parameters->options().relocatable()
+ && Layout::special_ordering_of_input_section(name) >= 0)
+ os->set_must_sort_attached_input_sections();
+
// If this is a .ctors or .ctors.* section being mapped to a
// .init_array section, or a .dtors or .dtors.* section being mapped
// to a .fini_array section, we will need to reverse the words if
Layout::insert_section_segment_map(Const_section_id secn,
Unique_segment_info *s)
{
- gold_assert(this->unique_segment_for_sections_specified_);
+ gold_assert(this->unique_segment_for_sections_specified_);
this->section_segment_map_[secn] = s;
}
|| strcmp(name, ".dtors") == 0))))
os->set_may_sort_attached_input_sections();
+ // The GNU linker by default sorts .text.{unlikely,exit,startup,hot}
+ // sections before other .text sections. We are compatible. We
+ // need to know that this might happen before we attach any input
+ // sections.
+ if (parameters->options().text_reorder()
+ && !this->script_options_->saw_sections_clause()
+ && !this->is_section_ordering_specified()
+ && !parameters->options().relocatable()
+ && strcmp(name, ".text") == 0)
+ os->set_may_sort_attached_input_sections();
+
+ // GNU linker sorts section by name with --sort-section=name.
+ if (strcmp(parameters->options().sort_section(), "name") == 0)
+ os->set_must_sort_attached_input_sections();
+
// Check for .stab*str sections, as .stab* sections need to link to
// them.
if (type == elfcpp::SHT_STRTAB
if (!os->is_unique_segment())
{
for (p = this->segment_list_.begin();
- p != this->segment_list_.end();
+ p != this->segment_list_.end();
++p)
{
- if ((*p)->type() != elfcpp::PT_LOAD)
- continue;
- if ((*p)->is_unique_segment())
- continue;
- if (!parameters->options().omagic()
- && ((*p)->flags() & elfcpp::PF_W) != (seg_flags & elfcpp::PF_W))
- continue;
- if ((target->isolate_execinstr() || parameters->options().rosegment())
- && ((*p)->flags() & elfcpp::PF_X) != (seg_flags & elfcpp::PF_X))
- continue;
- // If -Tbss was specified, we need to separate the data and BSS
- // segments.
- if (parameters->options().user_set_Tbss())
- {
- if ((os->type() == elfcpp::SHT_NOBITS)
- == (*p)->has_any_data_sections())
- continue;
- }
- if (os->is_large_data_section() && !(*p)->is_large_data_segment())
- continue;
-
- if (is_address_set)
- {
- if ((*p)->are_addresses_set())
- continue;
-
- (*p)->add_initial_output_data(os);
- (*p)->update_flags_for_output_section(seg_flags);
- (*p)->set_addresses(addr, addr);
- break;
- }
-
- (*p)->add_output_section_to_load(this, os, seg_flags);
- break;
- }
+ if ((*p)->type() != elfcpp::PT_LOAD)
+ continue;
+ if ((*p)->is_unique_segment())
+ continue;
+ if (!parameters->options().omagic()
+ && ((*p)->flags() & elfcpp::PF_W) != (seg_flags & elfcpp::PF_W))
+ continue;
+ if ((target->isolate_execinstr() || parameters->options().rosegment())
+ && ((*p)->flags() & elfcpp::PF_X) != (seg_flags & elfcpp::PF_X))
+ continue;
+ // If -Tbss was specified, we need to separate the data and BSS
+ // segments.
+ if (parameters->options().user_set_Tbss())
+ {
+ if ((os->type() == elfcpp::SHT_NOBITS)
+ == (*p)->has_any_data_sections())
+ continue;
+ }
+ if (os->is_large_data_section() && !(*p)->is_large_data_segment())
+ continue;
+
+ if (is_address_set)
+ {
+ if ((*p)->are_addresses_set())
+ continue;
+
+ (*p)->add_initial_output_data(os);
+ (*p)->update_flags_for_output_section(seg_flags);
+ (*p)->set_addresses(addr, addr);
+ break;
+ }
+
+ (*p)->add_output_section_to_load(this, os, seg_flags);
+ break;
+ }
}
if (p == this->segment_list_.end()
++p)
delete *p;
this->script_output_section_data_list_.clear();
+
+ // Special-case fill output objects are recreated each time through
+ // the relaxation loop.
+ this->reset_relax_output();
+}
+
+void
+Layout::reset_relax_output()
+{
+ for (Data_list::const_iterator p = this->relax_output_list_.begin();
+ p != this->relax_output_list_.end();
+ ++p)
+ delete *p;
+ this->relax_output_list_.clear();
}
// Prepare for relaxation.
if (is_debugging_enabled(DEBUG_RELAXATION))
this->relaxation_debug_check_->check_output_data_for_reset_values(
- this->section_list_, this->special_output_list_);
+ this->section_list_, this->special_output_list_,
+ this->relax_output_list_);
// Also enable recording of output section data from scripts.
this->record_output_section_data_from_script_ = true;
}
+// If the user set the address of the text segment, that may not be
+// compatible with putting the segment headers and file headers into
+// that segment. For isolate_execinstr() targets, it's the rodata
+// segment rather than text where we might put the headers.
+static inline bool
+load_seg_unusable_for_headers(const Target* target)
+{
+ const General_options& options = parameters->options();
+ if (target->isolate_execinstr())
+ return (options.user_set_Trodata_segment()
+ && options.Trodata_segment() % target->abi_pagesize() != 0);
+ else
+ return (options.user_set_Ttext()
+ && options.Ttext() % target->abi_pagesize() != 0);
+}
+
// Relaxation loop body: If target has no relaxation, this runs only once
// Otherwise, the target relaxation hook is called at the end of
// each iteration. If the hook returns true, it means re-layout of
!= General_options::OBJECT_FORMAT_ELF)
load_seg = NULL;
- // If the user set the address of the text segment, that may not be
- // compatible with putting the segment headers and file headers into
- // that segment.
- if (parameters->options().user_set_Ttext()
- && parameters->options().Ttext() % target->abi_pagesize() != 0)
+ if (load_seg_unusable_for_headers(target))
{
load_seg = NULL;
phdr_seg = NULL;
symtab->define_in_output_segment("__ehdr_start", NULL,
Symbol_table::PREDEFINED, load_seg, 0, 0,
elfcpp::STT_NOTYPE, elfcpp::STB_GLOBAL,
- elfcpp::STV_DEFAULT, 0,
+ elfcpp::STV_HIDDEN, 0,
Symbol::SEGMENT_START, true);
// Set the file offsets of all the non-data sections we've seen so
std::string desc;
if (strcmp(style, "md5") == 0)
descsz = 128 / 8;
- else if (strcmp(style, "sha1") == 0)
+ else if ((strcmp(style, "sha1") == 0) || (strcmp(style, "tree") == 0))
descsz = 160 / 8;
else if (strcmp(style, "uuid") == 0)
{
// The order of non-PT_LOAD segments is unimportant. We simply sort
// by the numeric segment type and flags values. There should not
- // be more than one segment with the same type and flags.
+ // be more than one segment with the same type and flags, except
+ // when a linker script specifies such.
if (type1 != elfcpp::PT_LOAD)
{
if (type1 != type2)
return type1 < type2;
- gold_assert(flags1 != flags2);
+ gold_assert(flags1 != flags2
+ || this->script_options_->saw_phdrs_clause());
return flags1 < flags2;
}
return aligned_off;
}
+// On targets where the text segment contains only executable code,
+// a non-executable segment is never the text segment.
+
+static inline bool
+is_text_segment(const Target* target, const Output_segment* seg)
+{
+ elfcpp::Elf_Xword flags = seg->flags();
+ if ((flags & elfcpp::PF_W) != 0)
+ return false;
+ if ((flags & elfcpp::PF_X) == 0)
+ return !target->isolate_execinstr();
+ return true;
+}
+
// Set the file offsets of all the segments, and all the sections they
// contain. They have all been created. LOAD_SEG must be be laid out
// first. Return the offset of the data to follow.
addr = (*p)->paddr();
}
else if (parameters->options().user_set_Ttext()
- && ((*p)->flags() & elfcpp::PF_W) == 0)
+ && (parameters->options().omagic()
+ || is_text_segment(target, *p)))
+ {
+ are_addresses_set = true;
+ }
+ else if (parameters->options().user_set_Trodata_segment()
+ && ((*p)->flags() & (elfcpp::PF_W | elfcpp::PF_X)) == 0)
{
+ addr = parameters->options().Trodata_segment();
are_addresses_set = true;
}
else if (parameters->options().user_set_Tdata()
// If the target wants a fixed minimum distance from the
// text segment to the read-only segment, move up now.
- uint64_t min_addr = start_addr + target->rosegment_gap();
+ uint64_t min_addr =
+ start_addr + (parameters->options().user_set_rosegment_gap()
+ ? parameters->options().rosegment_gap()
+ : target->rosegment_gap());
if (addr < min_addr)
addr = min_addr;
if (!parameters->options().nmagic()
&& !parameters->options().omagic())
- off = align_file_offset(off, addr, abi_pagesize);
+ {
+ // Here we are also taking care of the case when
+ // the maximum segment alignment is larger than the page size.
+ off = align_file_offset(off, addr,
+ std::max(abi_pagesize,
+ (*p)->maximum_alignment()));
+ }
else
{
// This is -N or -n with a section script which prevents
unsigned int shndx_hold = *pshndx;
bool has_relro = false;
- uint64_t new_addr = (*p)->set_section_addresses(this, false, addr,
+ uint64_t new_addr = (*p)->set_section_addresses(target, this,
+ false, addr,
&increase_relro,
&has_relro,
&off, pshndx);
increase_relro = 0;
has_relro = false;
- new_addr = (*p)->set_section_addresses(this, true, addr,
+ new_addr = (*p)->set_section_addresses(target, this,
+ true, addr,
&increase_relro,
&has_relro,
&off, pshndx);
// so they land after the segments starting at LOAD_SEG.
off = align_file_offset(off, 0, target->abi_pagesize());
+ this->reset_relax_output();
+
for (Segment_list::iterator p = this->segment_list_.begin();
*p != load_seg;
++p)
bool has_relro = false;
const uint64_t old_addr = (*p)->vaddr();
const uint64_t old_end = old_addr + (*p)->memsz();
- uint64_t new_addr = (*p)->set_section_addresses(this, true,
- old_addr,
+ uint64_t new_addr = (*p)->set_section_addresses(target, this,
+ true, old_addr,
&increase_relro,
&has_relro,
&off,
(*p)->set_address(0);
(*p)->set_file_offset(off);
(*p)->finalize_data_size();
- off += (*p)->data_size();
+ if ((*p)->type() != elfcpp::SHT_NOBITS)
+ off += (*p)->data_size();
(*p)->set_out_shndx(*pshndx);
++*pshndx;
false,
ORDER_DYNAMIC_LINKER,
false);
-
+ *pdynstr = dynstr;
if (dynstr != NULL)
{
Output_section_data* strdata = new Output_data_strtab(&this->dynpool_);
odyn->add_section_address(elfcpp::DT_STRTAB, dynstr);
odyn->add_section_size(elfcpp::DT_STRSZ, dynstr);
}
-
- *pdynstr = dynstr;
}
// Create the hash tables.
}
}
- odyn->add_string(elfcpp::DT_RPATH, rpath_val);
- if (parameters->options().enable_new_dtags())
+ if (!parameters->options().enable_new_dtags())
+ odyn->add_string(elfcpp::DT_RPATH, rpath_val);
+ else
odyn->add_string(elfcpp::DT_RUNPATH, rpath_val);
}
section_list->push_back(*p);
}
+// Store the executable sections into the section list.
+
+void
+Layout::get_executable_sections(Section_list* section_list) const
+{
+ for (Section_list::const_iterator p = this->section_list_.begin();
+ p != this->section_list_.end();
+ ++p)
+ if (((*p)->flags() & (elfcpp::SHF_ALLOC | elfcpp::SHF_EXECINSTR))
+ == (elfcpp::SHF_ALLOC | elfcpp::SHF_EXECINSTR))
+ section_list->push_back(*p);
+}
+
// Create an output segment.
Output_segment*
p != this->special_output_list_.end();
++p)
(*p)->write(of);
+
+ // Write out the Output_data which are not in an Output_section
+ // and are regenerated in each iteration of relaxation.
+ for (Data_list::const_iterator p = this->relax_output_list_.begin();
+ p != this->relax_output_list_.end();
+ ++p)
+ (*p)->write(of);
}
// Write out the Output_sections which can only be written after the
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.
+// Build IDs can be computed as a "flat" sha1 or md5 of a string of bytes,
+// or as a "tree" where each chunk of the string is hashed and then those
+// hashes are put into a (much smaller) string which is hashed with sha1.
+// We compute a checksum over the entire file because that is simplest.
+
+Task_token*
+Layout::queue_build_id_tasks(Workqueue* workqueue, Task_token* build_id_blocker,
+ Output_file* of)
+{
+ const size_t filesize = (this->output_file_size() <= 0 ? 0
+ : static_cast<size_t>(this->output_file_size()));
+ if (this->build_id_note_ != NULL
+ && strcmp(parameters->options().build_id(), "tree") == 0
+ && parameters->options().build_id_chunk_size_for_treehash() > 0
+ && filesize > 0
+ && (filesize >=
+ parameters->options().build_id_min_file_size_for_treehash()))
+ {
+ static const size_t MD5_OUTPUT_SIZE_IN_BYTES = 16;
+ const size_t chunk_size =
+ parameters->options().build_id_chunk_size_for_treehash();
+ const size_t num_hashes = ((filesize - 1) / chunk_size) + 1;
+ Task_token* post_hash_tasks_blocker = new Task_token(true);
+ post_hash_tasks_blocker->add_blockers(num_hashes);
+ this->size_of_array_of_hashes_ = num_hashes * MD5_OUTPUT_SIZE_IN_BYTES;
+ const unsigned char* src = of->get_input_view(0, filesize);
+ this->input_view_ = src;
+ unsigned char *dst = new unsigned char[this->size_of_array_of_hashes_];
+ this->array_of_hashes_ = dst;
+ for (size_t i = 0, src_offset = 0; i < num_hashes;
+ i++, dst += MD5_OUTPUT_SIZE_IN_BYTES, src_offset += chunk_size)
+ {
+ size_t size = std::min(chunk_size, filesize - src_offset);
+ workqueue->queue(new Hash_task(src + src_offset,
+ size,
+ dst,
+ build_id_blocker,
+ post_hash_tasks_blocker));
+ }
+ return post_hash_tasks_blocker;
+ }
+ return build_id_blocker;
+}
+
+// If a tree-style build ID was requested, the parallel part of that computation
+// is already done, and the final hash-of-hashes is computed here. For other
+// types of build IDs, all the work is done here.
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)
+ if (this->array_of_hashes_ == NULL)
{
- sha1_ctx ctx;
- sha1_init_ctx(&ctx);
- sha1_process_bytes(iv, this->output_file_size_, &ctx);
- sha1_finish_ctx(&ctx, ov);
+ const size_t output_file_size = this->output_file_size();
+ const unsigned char* iv = of->get_input_view(0, output_file_size);
+ const char* style = parameters->options().build_id();
+
+ // If we get here with style == "tree" then the output must be
+ // too small for chunking, and we use SHA-1 in that case.
+ if ((strcmp(style, "sha1") == 0) || (strcmp(style, "tree") == 0))
+ sha1_buffer(reinterpret_cast<const char*>(iv), output_file_size, ov);
+ else if (strcmp(style, "md5") == 0)
+ md5_buffer(reinterpret_cast<const char*>(iv), output_file_size, ov);
+ else
+ gold_unreachable();
+
+ of->free_input_view(0, output_file_size, iv);
}
- else if (strcmp(style, "md5") == 0)
+ else
{
- md5_ctx ctx;
- md5_init_ctx(&ctx);
- md5_process_bytes(iv, this->output_file_size_, &ctx);
- md5_finish_ctx(&ctx, ov);
+ // Non-overlapping substrings of the output file have been hashed.
+ // Compute SHA-1 hash of the hashes.
+ sha1_buffer(reinterpret_cast<const char*>(this->array_of_hashes_),
+ this->size_of_array_of_hashes_, ov);
+ delete[] this->array_of_hashes_;
+ of->free_input_view(0, this->output_file_size(), this->input_view_);
}
- 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
// Close_task_runner methods.
-// Run the task--close the file.
+// Finish up the build ID computation, if necessary, and write a binary file,
+// if necessary. Then close the output file.
void
Close_task_runner::run(Workqueue*, const Task*)
{
- // If we need to compute a checksum for the BUILD if, we do so here.
+ // At this point the multi-threaded part of the build ID computation,
+ // if any, is done. See queue_build_id_tasks().
this->layout_->write_build_id(this->of_);
// If we've been asked to create a binary file, we do so here.