tapset-mark.cxx

   1 // tapset for kernel static markers
   2 // Copyright (C) 2005-2010 Red Hat Inc.
   3 // Copyright (C) 2005-2007 Intel Corporation.
   4 // Copyright (C) 2008 James.Bottomley@HansenPartnership.com
   5 //
   6 // This file is part of systemtap, and is free software.  You can
   7 // redistribute it and/or modify it under the terms of the GNU General
   8 // Public License (GPL); either version 2, or (at your option) any
   9 // later version.
  10
  11 #include "session.h"
  12 #include "tapsets.h"
  13 #include "translate.h"
  14 #include "util.h"
  15
  16 #include <cerrno>
  17 #include <cstdlib>
  18 #include <cstring>
  19 #include <string>
  20
  21 extern "C" {
  22 #include <fnmatch.h>
  23 }
  24
  25
  26 using namespace std;
  27 using namespace __gnu_cxx;
  28
  29
  30 static const string TOK_KERNEL("kernel");
  31 static const string TOK_MARK("mark");
  32 static const string TOK_FORMAT("format");
  33
  34
  35 // ------------------------------------------------------------------------
  36 // statically inserted macro-based derived probes
  37 // ------------------------------------------------------------------------
  38
  39 struct mark_arg
  40 {
  41   bool str;
  42   bool isptr;
  43   string c_type;
  44   exp_type stp_type;
  45 };
  46
  47 struct mark_derived_probe: public derived_probe
  48 {
  49   mark_derived_probe (systemtap_session &s,
  50                       const string& probe_name, const string& probe_format,
  51                       probe* base_probe, probe_point* location);
  52
  53   systemtap_session& sess;
  54   string probe_name, probe_format;
  55   vector <struct mark_arg *> mark_args;
  56   bool target_symbol_seen;
  57
  58   void join_group (systemtap_session& s);
  59   void print_dupe_stamp (ostream& o);
  60   void emit_probe_context_vars (translator_output* o);
  61   void initialize_probe_context_vars (translator_output* o);
  62   void getargs (std::list<std::string> &arg_set) const;
  63
  64   void parse_probe_format ();
  65 };
  66
  67
  68 struct mark_derived_probe_group: public generic_dpg<mark_derived_probe>
  69 {
  70 public:
  71   void emit_module_decls (systemtap_session& s);
  72   void emit_module_init (systemtap_session& s);
  73   void emit_module_exit (systemtap_session& s);
  74 };
  75
  76
  77 struct mark_var_expanding_visitor: public var_expanding_visitor
  78 {
  79   mark_var_expanding_visitor(systemtap_session& s, const string& pn,
  80                              vector <struct mark_arg *> &mark_args):
  81     sess (s), probe_name (pn), mark_args (mark_args),
  82     target_symbol_seen (false) {}
  83   systemtap_session& sess;
  84   string probe_name;
  85   vector <struct mark_arg *> &mark_args;
  86   bool target_symbol_seen;
  87
  88   void visit_target_symbol (target_symbol* e);
  89   void visit_target_symbol_arg (target_symbol* e);
  90   void visit_target_symbol_context (target_symbol* e);
  91 };
  92
  93
  94 void
  95 mark_var_expanding_visitor::visit_target_symbol_arg (target_symbol* e)
  96 {
  97   string argnum_s = e->base_name.substr(4,e->base_name.length()-4);
  98   int argnum = atoi (argnum_s.c_str());
  99
 100   if (argnum < 1 || argnum > (int)mark_args.size())
 101     throw semantic_error ("invalid marker argument number", e->tok);
 102
 103   if (is_active_lvalue (e))
 104     throw semantic_error("write to marker parameter not permitted", e->tok);
 105
 106   e->assert_no_components("marker");
 107
 108   // Remember that we've seen a target variable.
 109   target_symbol_seen = true;
 110
 111   e->probe_context_var = "__mark_arg" + lex_cast(argnum);
 112   e->type = mark_args[argnum-1]->stp_type;
 113   provide (e);
 114 }
 115
 116
 117 void
 118 mark_var_expanding_visitor::visit_target_symbol_context (target_symbol* e)
 119 {
 120   string sname = e->base_name;
 121
 122   if (is_active_lvalue (e))
 123     throw semantic_error("write to marker '" + sname + "' not permitted", e->tok);
 124
 125   e->assert_no_components("marker");
 126
 127   if (e->base_name == "$format" || e->base_name == "$name") {
 128      string fname;
 129      if (e->base_name == "$format") {
 130         fname = string("_mark_format_get");
 131      } else {
 132         fname = string("_mark_name_get");
 133      }
 134
 135      // Synthesize a functioncall.
 136      functioncall* n = new functioncall;
 137      n->tok = e->tok;
 138      n->function = fname;
 139      n->referent = 0; // NB: must not resolve yet, to ensure inclusion in session
 140      provide (n);
 141   }
 142  else if (e->base_name == "$$vars" || e->base_name == "$$parms")
 143   {
 144      //copy from tracepoint
 145      token* pf_tok = new token(*e->tok);
 146      pf_tok->content = "sprintf";
 147      print_format* pf = print_format::create(pf_tok);
 148
 149      for (unsigned i = 0; i < mark_args.size(); ++i)
 150         {
 151           if (i > 0)
 152             pf->raw_components += " ";
 153           pf->raw_components += "$arg" + lex_cast(i+1);
 154           target_symbol *tsym = new target_symbol;
 155           tsym->tok = e->tok;
 156           tsym->base_name = "$arg" + lex_cast(i+1);
 157
 158           tsym->saved_conversion_error = 0;
 159           expression *texp = require (tsym); //same treatment as tracepoint
 160           assert (!tsym->saved_conversion_error);
 161           switch (mark_args[i]->stp_type)
 162            {
 163              case pe_long:
 164                pf->raw_components += mark_args[i]->isptr ? "=%p" : "=%#x";
 165                break;
 166              case pe_string:
 167                pf->raw_components += "=%s";
 168                break;
 169              default:
 170                pf->raw_components += "=%#x";
 171                break;
 172             }
 173           pf->args.push_back(texp);
 174         }
 175      pf->components = print_format::string_to_components(pf->raw_components);
 176      provide (pf);
 177   }
 178 }
 179
 180 void
 181 mark_var_expanding_visitor::visit_target_symbol (target_symbol* e)
 182 {
 183   assert(e->base_name.size() > 0 && e->base_name[0] == '$');
 184
 185   try
 186     {
 187       if (e->addressof)
 188         throw semantic_error("cannot take address of marker variable", e->tok);
 189
 190       if (startswith(e->base_name, "$arg"))
 191         visit_target_symbol_arg (e);
 192       else if (e->base_name == "$format" || e->base_name == "$name"
 193                || e->base_name == "$$parms" || e->base_name == "$$vars")
 194         visit_target_symbol_context (e);
 195       else
 196         throw semantic_error ("invalid target symbol for marker, $argN, $name, $format, $$parms or $$vars expected",
 197                               e->tok);
 198     }
 199   catch (const semantic_error &er)
 200     {
 201       e->chain (er);
 202       provide (e);
 203     }
 204 }
 205
 206
 207 mark_derived_probe::mark_derived_probe (systemtap_session &s,
 208                                         const string& p_n,
 209                                         const string& p_f,
 210                                         probe* base, probe_point* loc):
 211   derived_probe (base, new probe_point(*loc) /* .components soon rewritten */),
 212   sess (s), probe_name (p_n), probe_format (p_f),
 213   target_symbol_seen (false)
 214 {
 215   // create synthetic probe point name; preserve condition
 216   vector<probe_point::component*> comps;
 217   comps.push_back (new probe_point::component (TOK_KERNEL));
 218   comps.push_back (new probe_point::component (TOK_MARK, new literal_string (probe_name)));
 219   comps.push_back (new probe_point::component (TOK_FORMAT, new literal_string (probe_format)));
 220   this->sole_location()->components = comps;
 221
 222   // expand the marker format
 223   parse_probe_format();
 224
 225   // Now expand the local variables in the probe body
 226   mark_var_expanding_visitor v (sess, name, mark_args);
 227   v.replace (this->body);
 228   target_symbol_seen = v.target_symbol_seen;
 229
 230   if (sess.verbose > 2)
 231     clog << "marker-based " << name << " mark=" << probe_name
 232          << " fmt='" << probe_format << "'" << endl;
 233 }
 234
 235
 236 static int
 237 skip_atoi(const char **s)
 238 {
 239   int i = 0;
 240   while (isdigit(**s))
 241     i = i * 10 + *((*s)++) - '0';
 242   return i;
 243 }
 244
 245
 246 void
 247 mark_derived_probe::parse_probe_format()
 248 {
 249   const char *fmt = probe_format.c_str();
 250   int qualifier;                // 'h', 'l', or 'L' for integer fields
 251   mark_arg *arg;
 252
 253   for (; *fmt ; ++fmt)
 254     {
 255       if (*fmt != '%')
 256         {
 257           /* Skip text */
 258           continue;
 259         }
 260
 261 repeat:
 262       ++fmt;
 263
 264       // skip conversion flags (if present)
 265       switch (*fmt)
 266         {
 267         case '-':
 268         case '+':
 269         case ' ':
 270         case '#':
 271         case '0':
 272           goto repeat;
 273         }
 274
 275       // skip minimum field witdh (if present)
 276       if (isdigit(*fmt))
 277         skip_atoi(&fmt);
 278
 279       // skip precision (if present)
 280       if (*fmt == '.')
 281         {
 282           ++fmt;
 283           if (isdigit(*fmt))
 284             skip_atoi(&fmt);
 285         }
 286
 287       // get the conversion qualifier (if present)
 288       qualifier = -1;
 289       if (*fmt == 'h' || *fmt == 'l' || *fmt == 'L')
 290         {
 291           qualifier = *fmt;
 292           ++fmt;
 293           if (qualifier == 'l' && *fmt == 'l')
 294             {
 295               qualifier = 'L';
 296               ++fmt;
 297             }
 298         }
 299
 300       // get the conversion type
 301       switch (*fmt)
 302         {
 303         case 'c':
 304           arg = new mark_arg;
 305           arg->str = false;
 306           arg->isptr = false;
 307           arg->c_type = "int";
 308           arg->stp_type = pe_long;
 309           mark_args.push_back(arg);
 310           continue;
 311
 312         case 's':
 313           arg = new mark_arg;
 314           arg->str = true;
 315           arg->isptr = false;
 316           arg->c_type = "char *";
 317           arg->stp_type = pe_string;
 318           mark_args.push_back(arg);
 319           continue;
 320
 321         case 'p':
 322           arg = new mark_arg;
 323           arg->str = false;
 324           arg->isptr = true;
 325           // This should really be 'void *'.  But, then we'll get a
 326           // compile error when we assign the void pointer to an
 327           // integer without a cast.  So, we use 'long' instead, since
 328           // it should have the same size as 'void *'.
 329           arg->c_type = "long";
 330           arg->stp_type = pe_long;
 331           mark_args.push_back(arg);
 332           continue;
 333
 334         case '%':
 335           continue;
 336
 337         case 'o':
 338         case 'X':
 339         case 'x':
 340         case 'd':
 341         case 'i':
 342         case 'u':
 343           // fall through...
 344           break;
 345
 346         default:
 347           if (!*fmt)
 348             --fmt;
 349           continue;
 350         }
 351
 352       arg = new mark_arg;
 353       arg->str = false;
 354       arg->isptr = false;
 355       arg->stp_type = pe_long;
 356       switch (qualifier)
 357         {
 358         case 'L':
 359           arg->c_type = "long long";
 360           break;
 361
 362         case 'l':
 363           arg->c_type = "long";
 364           break;
 365
 366         case 'h':
 367           arg->c_type = "short";
 368           break;
 369
 370         default:
 371           arg->c_type = "int";
 372           break;
 373         }
 374       mark_args.push_back(arg);
 375     }
 376 }
 377
 378
 379 void
 380 mark_derived_probe::join_group (systemtap_session& s)
 381 {
 382   if (! s.mark_derived_probes)
 383     {
 384       s.mark_derived_probes = new mark_derived_probe_group ();
 385
 386       // Make sure <linux/marker.h> is included early.
 387       embeddedcode *ec = new embeddedcode;
 388       ec->tok = NULL;
 389       ec->code = string("#if ! defined(CONFIG_MARKERS)\n")
 390         + string("#error \"Need CONFIG_MARKERS!\"\n")
 391         + string("#endif\n")
 392         + string("#include <linux/marker.h>\n");
 393
 394       s.embeds.push_back(ec);
 395     }
 396   s.mark_derived_probes->enroll (this);
 397 }
 398
 399
 400 void
 401 mark_derived_probe::print_dupe_stamp (ostream& o)
 402 {
 403   if (target_symbol_seen)
 404     for (unsigned i = 0; i < mark_args.size(); i++)
 405       o << mark_args[i]->c_type << " __mark_arg" << (i+1) << endl;
 406 }
 407
 408
 409 void
 410 mark_derived_probe::emit_probe_context_vars (translator_output* o)
 411 {
 412   // If we haven't seen a target symbol for this probe, quit.
 413   if (! target_symbol_seen)
 414     return;
 415
 416   for (unsigned i = 0; i < mark_args.size(); i++)
 417     {
 418       string localname = "__mark_arg" + lex_cast(i+1);
 419       switch (mark_args[i]->stp_type)
 420         {
 421         case pe_long:
 422           o->newline() << "int64_t " << localname << ";";
 423           break;
 424         case pe_string:
 425           o->newline() << "string_t " << localname << ";";
 426           break;
 427         default:
 428           throw semantic_error ("cannot expand unknown type");
 429           break;
 430         }
 431     }
 432 }
 433
 434
 435 void
 436 mark_derived_probe::initialize_probe_context_vars (translator_output* o)
 437 {
 438   // If we haven't seen a target symbol for this probe, quit.
 439   if (! target_symbol_seen)
 440     return;
 441
 442   bool deref_fault_needed = false;
 443   for (unsigned i = 0; i < mark_args.size(); i++)
 444     {
 445       string localname = "l->__mark_arg" + lex_cast(i+1);
 446       switch (mark_args[i]->stp_type)
 447         {
 448         case pe_long:
 449           o->newline() << localname << " = va_arg(*c->mark_va_list, "
 450                        << mark_args[i]->c_type << ");";
 451           break;
 452
 453         case pe_string:
 454           // We're assuming that this is a kernel string (this code is
 455           // basically the guts of kernel_string), not a user string.
 456           o->newline() << "{ " << mark_args[i]->c_type
 457                        << " tmp_str = va_arg(*c->mark_va_list, "
 458                        << mark_args[i]->c_type << ");";
 459           o->newline() << "deref_string (" << localname
 460                        << ", tmp_str, MAXSTRINGLEN); }";
 461           deref_fault_needed = true;
 462           break;
 463
 464         default:
 465           throw semantic_error ("cannot expand unknown type");
 466           break;
 467         }
 468     }
 469   if (deref_fault_needed)
 470     // Need to report errors?
 471     o->newline() << "deref_fault: ;";
 472 }
 473
 474 void
 475 mark_derived_probe::getargs(std::list<std::string> &arg_set) const
 476 {
 477   for (unsigned i = 0; i < mark_args.size(); i++)
 478     {
 479       string localname = "$arg" + lex_cast(i+1);
 480       switch (mark_args[i]->stp_type)
 481         {
 482         case pe_long:
 483           arg_set.push_back(localname+":long");
 484           break;
 485         case pe_string:
 486           arg_set.push_back(localname+":string");
 487           break;
 488         default:
 489           arg_set.push_back(localname+":unknown");
 490           break;
 491         }
 492     }
 493 }
 494
 495
 496 void
 497 mark_derived_probe_group::emit_module_decls (systemtap_session& s)
 498 {
 499   if (probes.empty())
 500     return;
 501
 502   s.op->newline() << "/* ---- marker probes ---- */";
 503
 504   s.op->newline() << "static struct stap_marker_probe {";
 505   s.op->newline(1) << "const char * const name;";
 506   s.op->newline() << "const char * const format;";
 507   s.op->newline() << "const char * const pp;";
 508   s.op->newline() << "void (* const ph) (struct context *);";
 509
 510   s.op->newline(-1) << "} stap_marker_probes [" << probes.size() << "] = {";
 511   s.op->indent(1);
 512   for (unsigned i=0; i < probes.size(); i++)
 513     {
 514       s.op->newline () << "{";
 515       s.op->line() << " .name=" << lex_cast_qstring(probes[i]->probe_name)
 516                    << ",";
 517       s.op->line() << " .format=" << lex_cast_qstring(probes[i]->probe_format)
 518                    << ",";
 519       s.op->line() << " .pp=" << lex_cast_qstring (*probes[i]->sole_location())
 520                    << ",";
 521       s.op->line() << " .ph=&" << probes[i]->name;
 522       s.op->line() << " },";
 523     }
 524   s.op->newline(-1) << "};";
 525   s.op->newline();
 526
 527
 528   // Emit the marker callback function
 529   s.op->newline();
 530   s.op->newline() << "static void enter_marker_probe (void *probe_data, void *call_data, const char *fmt, va_list *args) {";
 531   s.op->newline(1) << "struct stap_marker_probe *smp = (struct stap_marker_probe *)probe_data;";
 532   common_probe_entryfn_prologue (s.op, "STAP_SESSION_RUNNING", "smp->pp");
 533   s.op->newline() << "c->marker_name = smp->name;";
 534   s.op->newline() << "c->marker_format = smp->format;";
 535   s.op->newline() << "c->mark_va_list = args;";
 536   s.op->newline() << "(*smp->ph) (c);";
 537   s.op->newline() << "c->mark_va_list = NULL;";
 538   s.op->newline() << "c->data = NULL;";
 539
 540   common_probe_entryfn_epilogue (s.op);
 541   s.op->newline(-1) << "}";
 542
 543   return;
 544 }
 545
 546
 547 void
 548 mark_derived_probe_group::emit_module_init (systemtap_session &s)
 549 {
 550   if (probes.size () == 0)
 551     return;
 552
 553   s.op->newline() << "/* init marker probes */";
 554   s.op->newline() << "for (i=0; i<" << probes.size() << "; i++) {";
 555   s.op->newline(1) << "struct stap_marker_probe *smp = &stap_marker_probes[i];";
 556   s.op->newline() << "probe_point = smp->pp;";
 557   s.op->newline() << "rc = marker_probe_register(smp->name, smp->format, enter_marker_probe, smp);";
 558   s.op->newline() << "if (rc) {";
 559   s.op->newline(1) << "for (j=i-1; j>=0; j--) {"; // partial rollback
 560   s.op->newline(1) << "struct stap_marker_probe *smp2 = &stap_marker_probes[j];";
 561   s.op->newline() << "marker_probe_unregister(smp2->name, enter_marker_probe, smp2);";
 562   s.op->newline(-1) << "}";
 563   s.op->newline() << "break;"; // don't attempt to register any more probes
 564   s.op->newline(-1) << "}";
 565   s.op->newline(-1) << "}"; // for loop
 566 }
 567
 568
 569 void
 570 mark_derived_probe_group::emit_module_exit (systemtap_session& s)
 571 {
 572   if (probes.empty())
 573     return;
 574
 575   s.op->newline() << "/* deregister marker probes */";
 576   s.op->newline() << "for (i=0; i<" << probes.size() << "; i++) {";
 577   s.op->newline(1) << "struct stap_marker_probe *smp = &stap_marker_probes[i];";
 578   s.op->newline() << "marker_probe_unregister(smp->name, enter_marker_probe, smp);";
 579   s.op->newline(-1) << "}"; // for loop
 580 }
 581
 582
 583 struct mark_builder: public derived_probe_builder
 584 {
 585 private:
 586   bool cache_initialized;
 587   typedef multimap<string, string> mark_cache_t;
 588   typedef multimap<string, string>::const_iterator mark_cache_const_iterator_t;
 589   typedef pair<mark_cache_const_iterator_t, mark_cache_const_iterator_t>
 590     mark_cache_const_iterator_pair_t;
 591   mark_cache_t mark_cache;
 592
 593 public:
 594   mark_builder(): cache_initialized(false) {}
 595
 596   void build_no_more (systemtap_session &s)
 597   {
 598     if (! mark_cache.empty())
 599       {
 600         if (s.verbose > 3)
 601           clog << "mark_builder releasing cache" << endl;
 602         mark_cache.clear();
 603       }
 604   }
 605
 606   void build(systemtap_session & sess,
 607              probe * base,
 608              probe_point * location,
 609              literal_map_t const & parameters,
 610              vector<derived_probe *> & finished_results);
 611 };
 612
 613
 614 void
 615 mark_builder::build(systemtap_session & sess,
 616                     probe * base,
 617                     probe_point *loc,
 618                     literal_map_t const & parameters,
 619                     vector<derived_probe *> & finished_results)
 620 {
 621   string mark_str_val;
 622   bool has_mark_str = get_param (parameters, TOK_MARK, mark_str_val);
 623   string mark_format_val;
 624   bool has_mark_format = get_param (parameters, TOK_FORMAT, mark_format_val);
 625   assert (has_mark_str);
 626   (void) has_mark_str;
 627
 628   if (! cache_initialized)
 629     {
 630       cache_initialized = true;
 631       string module_markers_path = sess.kernel_build_tree + "/Module.markers";
 632
 633       ifstream module_markers;
 634       module_markers.open(module_markers_path.c_str(), ifstream::in);
 635       if (! module_markers)
 636         {
 637           if (sess.verbose>3)
 638             clog << module_markers_path << " cannot be opened: "
 639                  << strerror(errno) << endl;
 640           return;
 641         }
 642
 643       string name, module, format;
 644       do
 645         {
 646           module_markers >> name >> module;
 647           getline(module_markers, format);
 648
 649           // trim leading whitespace
 650           string::size_type notwhite = format.find_first_not_of(" \t");
 651           format.erase(0, notwhite);
 652
 653           // If the format is empty, make sure we add back a space
 654           // character, which is what MARK_NOARGS expands to.
 655           if (format.length() == 0)
 656             format = " ";
 657
 658           if (sess.verbose>3)
 659             clog << "'" << name << "' '" << module << "' '" << format
 660                  << "'" << endl;
 661
 662           if (mark_cache.count(name) > 0)
 663             {
 664               // If we have 2 markers with the same we've got 2 cases:
 665               // different format strings or duplicate format strings.
 666               // If an existing marker in the cache doesn't have the
 667               // same format string, add this marker.
 668               mark_cache_const_iterator_pair_t ret;
 669               mark_cache_const_iterator_t it;
 670               bool matching_format_string = false;
 671
 672               ret = mark_cache.equal_range(name);
 673               for (it = ret.first; it != ret.second; ++it)
 674                 {
 675                   if (format == it->second)
 676                     {
 677                       matching_format_string = true;
 678                       break;
 679                     }
 680                 }
 681
 682               if (! matching_format_string)
 683                 mark_cache.insert(pair<string,string>(name, format));
 684           }
 685           else
 686             mark_cache.insert(pair<string,string>(name, format));
 687         }
 688       while (! module_markers.eof());
 689       module_markers.close();
 690     }
 691
 692   // Search marker list for matching markers
 693   for (mark_cache_const_iterator_t it = mark_cache.begin();
 694        it != mark_cache.end(); it++)
 695     {
 696       // Below, "rc" has negative polarity: zero iff matching.
 697       int rc = fnmatch(mark_str_val.c_str(), it->first.c_str(), 0);
 698       if (! rc)
 699         {
 700           bool add_result = true;
 701
 702           // Match format strings (if the user specified one)
 703           if (has_mark_format && fnmatch(mark_format_val.c_str(),
 704                                          it->second.c_str(), 0))
 705             add_result = false;
 706
 707           if (add_result)
 708             {
 709               derived_probe *dp
 710                 = new mark_derived_probe (sess,
 711                                           it->first, it->second,
 712                                           base, loc);
 713               finished_results.push_back (dp);
 714             }
 715         }
 716     }
 717 }
 718
 719
 720
 721 void
 722 register_tapset_mark(systemtap_session& s)
 723 {
 724   match_node* root = s.pattern_root;
 725   derived_probe_builder *builder = new mark_builder();
 726
 727   root = root->bind(TOK_KERNEL);
 728   root = root->bind_str(TOK_MARK);
 729
 730   root->bind(builder);
 731   root->bind_str(TOK_FORMAT)->bind(builder);
 732 }
 733
 734 /* vim: set sw=2 ts=8 cino=>4,n-2,{2,^-2,t0,(0,u0,w1,M1 : */