The Tor Browser: tools/reorder/grope.cpp@97036ab72558 (annotated)

tools/reorder/grope.cpp@97036ab72558 (annotated)

tools/reorder/grope.cpp

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 /*
   A program that computes a function ordering for an executable based
   on runtime profile information.
   This program is directly based on work done by Roger Chickering
   <rogc@netscape.com> in
     <http://bugzilla.mozilla.org/show_bug.cgi?id=65845>
   to implement Nat Friedman's <nat@nat.org> `grope',
     _GNU Rope - A Subroutine Position Optimizer_
     <http://www.hungry.com/~shaver/grope/grope.ps>
   Specifically, it implements the procedure re-ordering algorithm
   described in:
     K. Pettis and R. Hansen. ``Profile-Guided Core Position.'' In
     _Proceedings of the Int. Conference on Programming Language Design
     and Implementation_, pages 16-27, June 1990.
  */
 #include <assert.h>
 #include <fstream>
 #include <hash_set>
 #include <map>
 #include <set>
 #include <list>
 #include <vector>
 #include <limits.h>
 #include <unistd.h>
 #include <stdio.h>
 #include <fcntl.h>
 #include "elf_symbol_table.h"
 #define _GNU_SOURCE
 #include <getopt.h>
 elf_symbol_table symtab;
 // Straight outta plhash.c!
 #define GOLDEN_RATIO 0x9E3779B9U
 struct hash<const Elf32_Sym *>
 {
     size_t operator()(const Elf32_Sym *sym) const {
         return (reinterpret_cast<size_t>(sym) >> 4) * GOLDEN_RATIO; }
 };
 typedef unsigned int call_count_t;
 struct call_graph_arc
 {
     const Elf32_Sym *m_from;
     const Elf32_Sym *m_to;
     call_count_t     m_count;
     call_graph_arc(const Elf32_Sym *left, const Elf32_Sym *right, call_count_t count = 0)
         : m_count(count)
     {
         assert(left != right);
         if (left > right) {
             m_from = left;
             m_to   = right;
         }
         else {
             m_from = right;
             m_to   = left;
         }
     }
     friend bool
     operator==(const call_graph_arc &lhs, const call_graph_arc &rhs)
     {
         return (lhs.m_from == rhs.m_from) && (lhs.m_to == rhs.m_to);
     }
     friend ostream &
     operator<<(ostream &out, const call_graph_arc &arc)
     {
         out << &arc << ": ";
         out.form("<(%s %s) %d>",
                  symtab.get_symbol_name(arc.m_from),
                  symtab.get_symbol_name(arc.m_to),
                  arc.m_count);
         return out;
     }
 };
 struct hash<call_graph_arc *>
 {
     size_t
     operator()(const call_graph_arc* arc) const
     {
         size_t result;
         result = reinterpret_cast<unsigned long>(arc->m_from);
         result ^= reinterpret_cast<unsigned long>(arc->m_to) >> 16;
         result ^= reinterpret_cast<unsigned long>(arc->m_to) << 16;
         result *= GOLDEN_RATIO;
         return result;
     }
 };
 struct equal_to<call_graph_arc *>
 {
     bool
     operator()(const call_graph_arc* lhs, const call_graph_arc *rhs) const
     {
         return *lhs == *rhs;
     }
 };
 typedef hash_set<call_graph_arc *> arc_container_t;
 arc_container_t arcs;
 typedef multimap<const Elf32_Sym *, call_graph_arc *> arc_map_t;
 arc_map_t from_map;
 arc_map_t to_map;
 struct less_call_graph_arc_count
 {
     bool
     operator()(const call_graph_arc *lhs, const call_graph_arc *rhs) const
     {
         if (lhs->m_count == rhs->m_count) {
             if (lhs->m_from == rhs->m_from)
                 return lhs->m_to > rhs->m_to;
             return lhs->m_from > rhs->m_from;
         }
         return lhs->m_count > rhs->m_count;
     }
 };
 typedef set<call_graph_arc *, less_call_graph_arc_count> arc_count_index_t;
 bool opt_debug = false;
 const char *opt_out = "order.out";
 int opt_tick = 0;
 bool opt_verbose = false;
 int opt_window = 16;
 static struct option long_options[] = {
     { "debug",       no_argument,       0, 'd' },
     { "exe",         required_argument, 0, 'e' },
     { "help",        no_argument,       0, '?' },
     { "out",         required_argument, 0, 'o' },
     { "tick",        optional_argument, 0, 't' },
     { "verbose",     no_argument,       0, 'v' },
     { "window",      required_argument, 0, 'w' },
     { 0,             0,                 0, 0   }
 };
 //----------------------------------------------------------------------
 static void
 usage(const char *name)
 {
     cerr << "usage: " << name << " [options] [<file> ...]" << endl;
     cerr << "  Options:" << endl;
     cerr << "  --debug, -d" << endl;
     cerr << "      Print lots of verbose debugging cruft." << endl;
     cerr << "  --exe=<image>, -e <image> (required)" << endl;
     cerr << "      Specify the executable image from which to read symbol information." << endl;
     cerr << "  --help, -?" << endl;
     cerr << "      Print this message and exit." << endl;
     cerr << "  --out=<file>, -o <file>" << endl;
     cerr << "      Specify the output file to which to dump the symbol ordering of the" << endl;
     cerr << "      best individual (default is `order.out')." << endl;
     cerr << "  --tick[=<num>], -t [<num>]" << endl;
     cerr << "      When reading address data, print a dot to stderr every <num>th" << endl;
     cerr << "      address processed from the call trace. If specified with no argument," << endl;
     cerr << "      a dot will be printed for every million addresses processed." << endl;
     cerr << "  --verbose, -v" << endl;
     cerr << "      Issue progress messages to stderr." << endl;
     cerr << "  --window=<num>, -w <num>" << endl;
     cerr << "      Use a sliding window instead of pagination to score orderings." << endl;
 }
 /**
  * Using the symbol table, map a stream of address references into a
  * callgraph.
  */
 static void
 map_addrs(int fd)
 {
     long long total_calls = 0;
     typedef list<const Elf32_Sym *> window_t;
     window_t window;
     int window_size = 0;
     unsigned int buf[128];
     ssize_t cb;
     while ((cb = read(fd, buf, sizeof buf)) > 0) {
         if (cb % sizeof buf[0])
             fprintf(stderr, "unaligned read\n");
         unsigned int *addr = buf;
         unsigned int *limit = buf + (cb / 4);
         for (; addr < limit; ++addr) {
             const Elf32_Sym *sym = symtab.lookup(*addr);
             if (! sym)
                 continue;
             ++total_calls;
             window.push_front(sym);
             if (window_size >= opt_window)
                 window.pop_back();
             else
                 ++window_size;
             window_t::const_iterator i = window.begin();
             window_t::const_iterator end = window.end();
             for (; i != end; ++i) {
                 if (sym != *i) {
                     call_graph_arc *arc;
                     call_graph_arc key(sym, *i);
                     arc_container_t::iterator iter = arcs.find(&key);
                     if (iter == arcs.end()) {
                         arc = new call_graph_arc(sym, *i);
                         arcs.insert(arc);
                         from_map.insert(arc_map_t::value_type(arc->m_from, arc));
                         to_map.insert(arc_map_t::value_type(arc->m_to, arc));
                     }
                     else
                         arc = const_cast<call_graph_arc *>(*iter);
                     ++(arc->m_count);
                 }
             }
             if (opt_verbose && opt_tick && (total_calls % opt_tick == 0)) {
                 cerr << ".";
                 flush(cerr);
             }
         }
     }
     if (opt_verbose) {
         if (opt_tick)
             cerr << endl;
         cerr << "Total calls: " << total_calls << endl;
     }
 }
 static void
 remove_from(arc_map_t& map, const Elf32_Sym *sym, const call_graph_arc *arc)
 {
     pair<arc_map_t::iterator, arc_map_t::iterator> p
         = map.equal_range(sym);
     for (arc_map_t::iterator i = p.first; i != p.second; ++i) {
         if (i->second == arc) {
             map.erase(i);
             break;
         }
     }
 }
 /**
  * The main program
  */
 int
 main(int argc, char *argv[])
 {
     const char *opt_exe = 0;
     int c;
     while (1) {
         int option_index = 0;
         c = getopt_long(argc, argv, "?de:o:t:vw:", long_options, &option_index);
         if (c < 0)
             break;
         switch (c) {
         case '?':
             usage(argv[0]);
             return 0;
         case 'd':
             opt_debug = true;
             break;
         case 'e':
             opt_exe = optarg;
             break;
         case 'o':
             opt_out = optarg;
             break;
         case 't':
             opt_tick = optarg ? atoi(optarg) : 1000000;
             break;
         case 'v':
             opt_verbose = true;
             break;
         case 'w':
             opt_window = atoi(optarg);
             if (opt_window <= 0) {
                 cerr << "invalid window size: " << opt_window << endl;
                 return 1;
             }
             break;
         default:
             usage(argv[0]);
             return 1;
         }
     }
     // Make sure an image was specified
     if (! opt_exe) {
         usage(argv[0]);
         return 1;
     }
     // Read the sym table.
     symtab.init(opt_exe);
     // Process addresses to construct the weighted call graph.
     if (optind >= argc) {
         map_addrs(STDIN_FILENO);
     }
     else {
         do {
             int fd = open(argv[optind], O_RDONLY);
             if (fd < 0) {
                 perror(argv[optind]);
                 return 1;
             }
             map_addrs(fd);
             close(fd);
         } while (++optind < argc);
     }
     // Emit the ordering.
     ofstream out(opt_out);
     // Collect all of the arcs into a sorted container, with arcs
     // having the largest weight at the front.
     arc_count_index_t sorted_arcs(arcs.begin(), arcs.end());
     while (sorted_arcs.size()) {
         if (opt_debug) {
             cerr << "==========================================" << endl << endl;
             cerr << "Sorted Arcs:" << endl;
             for (arc_count_index_t::const_iterator iter = sorted_arcs.begin();
                  iter != sorted_arcs.end();
                  ++iter) {
                 cerr << **iter << endl;
             }
             cerr << endl << "Arc Container:" << endl;
             for (arc_container_t::const_iterator iter = arcs.begin();
                  iter != arcs.end();
                  ++iter) {
                 cerr << **iter << endl;
             }
             cerr << endl << "From Map:" << endl;
             for (arc_map_t::const_iterator iter = from_map.begin();
                  iter != from_map.end();
                  ++iter) {
                 cerr << symtab.get_symbol_name(iter->first) << ": " << *(iter->second) << endl;
             }
             cerr << endl << "To Map:" << endl;
             for (arc_map_t::const_iterator iter = to_map.begin();
                  iter != to_map.end();
                  ++iter) {
                 cerr << symtab.get_symbol_name(iter->first) << ": " << *(iter->second) << endl;
             }
             cerr << endl;
         }
         // The first arc in the sorted set will have the largest
         // weight. Pull it out, and emit its sink.
         arc_count_index_t::iterator max = sorted_arcs.begin();
         call_graph_arc *arc = const_cast<call_graph_arc *>(*max);
         sorted_arcs.erase(max);
         if (opt_debug)
             cerr << "pulling " << *arc << endl;
         arcs.erase(arc);
         remove_from(from_map, arc->m_from, arc);
         remove_from(to_map, arc->m_to, arc);
         out << symtab.get_symbol_name(arc->m_to) << endl;
         // Merge arc->m_to into arc->m_from. First, modify anything
         // that used to point to arc->m_to to point to arc->m_from.
         typedef list<call_graph_arc *> arc_list_t;
         arc_list_t map_add_queue;
         pair<arc_map_t::iterator, arc_map_t::iterator> p;
         // Find all the arcs that point to arc->m_to.
         p = to_map.equal_range(arc->m_to);
         for (arc_map_t::iterator i = p.first; i != p.second; ++i) {
             // Remove the arc that points to arc->m_to (`doomed') from
             // all of our indicies.
             call_graph_arc *doomed = i->second;
             const Elf32_Sym *source = doomed->m_from;
             sorted_arcs.erase(doomed);
             arcs.erase(doomed);
             remove_from(from_map, source, doomed);
             // N.B. that `doomed' will be removed from the `to_map'
             // after the loop completes.
             // Create a new (or locate an existing) arc whose source
             // was the doomed arc's source, and whose sink is
             // arc->m_from (i.e., the node that subsumed arc->m_to).
             call_graph_arc *merge;
             call_graph_arc key = call_graph_arc(source, arc->m_from);
             arc_container_t::iterator iter = arcs.find(&key);
             if (iter == arcs.end()) {
                 merge = new call_graph_arc(source, arc->m_from);
                 arcs.insert(merge);
                 from_map.insert(arc_map_t::value_type(merge->m_from, merge));
                 map_add_queue.push_back(merge);
             }
             else {
                 // We found an existing arc: temporarily remove it
                 // from the sorted index.
                 merge = const_cast<call_graph_arc *>(*iter);
                 sorted_arcs.erase(merge);
             }
             // Include the doomed arc's weight in the merged arc, and
             // (re-)insert it into the sorted index.
             merge->m_count += doomed->m_count;
             sorted_arcs.insert(merge);
             delete doomed;
         }
         to_map.erase(p.first, p.second);
         for (arc_list_t::iterator merge = map_add_queue.begin();
              merge != map_add_queue.end();
              map_add_queue.erase(merge++)) {
             to_map.insert(arc_map_t::value_type((*merge)->m_to, *merge));
         }
         // Now, roll anything that arc->m_to used to point at into
         // what arc->m_from now points at.
         // Collect all of the arcs that originate at arc->m_to.
         p = from_map.equal_range(arc->m_to);
         for (arc_map_t::iterator i = p.first; i != p.second; ++i) {
             // Remove the arc originating from arc->m_to (`doomed')
             // from all of our indicies.
             call_graph_arc *doomed = i->second;
             const Elf32_Sym *sink = doomed->m_to;
             // There shouldn't be any self-referential arcs.
             assert(sink != arc->m_to);
             sorted_arcs.erase(doomed);
             arcs.erase(doomed);
             remove_from(to_map, sink, doomed);
             // N.B. that `doomed' will be removed from the `from_map'
             // once the loop completes.
             // Create a new (or locate an existing) arc whose source
             // is arc->m_from and whose sink was the removed arc's
             // sink.
             call_graph_arc *merge;
             call_graph_arc key = call_graph_arc(arc->m_from, sink);
             arc_container_t::iterator iter = arcs.find(&key);
             if (iter == arcs.end()) {
                 merge = new call_graph_arc(arc->m_from, sink);
                 arcs.insert(merge);
                 map_add_queue.push_back(merge);
                 to_map.insert(arc_map_t::value_type(merge->m_to, merge));
             }
             else {
                 // We found an existing arc: temporarily remove it
                 // from the sorted index.
                 merge = const_cast<call_graph_arc *>(*iter);
                 sorted_arcs.erase(merge);
             }
             // Include the doomed arc's weight in the merged arc, and
             // (re-)insert it into the sorted index.
             merge->m_count += doomed->m_count;
             sorted_arcs.insert(merge);
             delete doomed;
         }
         from_map.erase(p.first, p.second);
         for (arc_list_t::iterator merge = map_add_queue.begin();
              merge != map_add_queue.end();
              map_add_queue.erase(merge++)) {
             from_map.insert(arc_map_t::value_type((*merge)->m_from, *merge));
         }
     }
     out.close();
     return 0;
 }

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tools/reorder/grope.cpp@97036ab72558 (annotated)

tools/reorder/grope.cpp