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authorCary Coutant <ccoutant@google.com>2013-04-26 21:38:57 +0000
committerCary Coutant <ccoutant@google.com>2013-04-26 21:38:57 +0000
commite7c5ea405fd863a9fcf85d49694e0f69fd5511ec (patch)
treeb0f6073044c3fcf77b5cfba088ef59bc3ccf052c /gold/layout.cc
parentee441d9a9a2df27e795cfdbf80048f42bb1504cc (diff)
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2013-04-26 Geoff Pike <gpike@chromium.org>
gold/ * gold.cc (queue_final_tasks): invoke layout->queue_build_id_tasks(). * layout.cc (Hash_task): New class. (Layout::queue_build_id_tasks): New function. (Layout::write_build_id): Handle single-thread portion of build ID computation. (In some cases, all of it is single-threaded.) Replace {sha1,md5}_process_bytes with {sha1,md5}_buffer to get the same functionality in fewer lines of code. * layout.h (Layout::queue_build_id_tasks): New function declaration. * options.h (General_options): make "--build-id" default to tree rather than sha1. Add two new options related to --build-id=tree: --build-id-chunk-size-for-treehash and --build-id-min-file-size-for-treehash. * Makefile.am: add testing of --build-id=tree and related new options (these tests will be invoked by "make check"). * Makefile.in: Regenerate.
Diffstat (limited to 'gold/layout.cc')
-rw-r--r--gold/layout.cc150
1 files changed, 126 insertions, 24 deletions
diff --git a/gold/layout.cc b/gold/layout.cc
index 13f57cb..b593acd 100644
--- a/gold/layout.cc
+++ b/gold/layout.cc
@@ -236,6 +236,54 @@ Free_list::print_stats()
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.
@@ -398,6 +446,9 @@ Layout::Layout(int number_of_input_files, Script_options* script_options)
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_(),
@@ -2924,7 +2975,7 @@ Layout::create_build_id()
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)
{
@@ -5212,9 +5263,53 @@ Layout::write_sections_after_input_sections(Output_file* of)
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
@@ -5222,34 +5317,39 @@ 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());
+ 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
@@ -5439,12 +5539,14 @@ Write_after_input_sections_task::run(Workqueue*)
// 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.