gdb/tracefile.c

   1 /* Trace file support in GDB.
   2
   3    Copyright (C) 1997-2024 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "tracefile.h"
  21 #include "tracectf.h"
  22 #include "exec.h"
  23 #include "regcache.h"
  24 #include "gdbsupport/byte-vector.h"
  25 #include "gdbarch.h"
  26 #include "gdbsupport/buildargv.h"
  27 #include "inferior.h"
  28
  29 /* Helper macros.  */
  30
  31 #define TRACE_WRITE_R_BLOCK(writer, buf, size)  \
  32   writer->ops->frame_ops->write_r_block ((writer), (buf), (size))
  33 #define TRACE_WRITE_M_BLOCK_HEADER(writer, addr, size)            \
  34   writer->ops->frame_ops->write_m_block_header ((writer), (addr), \
  35                                                 (size))
  36 #define TRACE_WRITE_M_BLOCK_MEMORY(writer, buf, size)     \
  37   writer->ops->frame_ops->write_m_block_memory ((writer), (buf), \
  38                                                 (size))
  39 #define TRACE_WRITE_V_BLOCK(writer, num, val)   \
  40   writer->ops->frame_ops->write_v_block ((writer), (num), (val))
  41
  42 /* A unique pointer policy class for trace_file_writer.  */
  43
  44 struct trace_file_writer_deleter
  45 {
  46   void operator() (struct trace_file_writer *writer)
  47   {
  48     writer->ops->dtor (writer);
  49     xfree (writer);
  50   }
  51 };
  52
  53 /* A unique_ptr specialization for trace_file_writer.  */
  54
  55 typedef std::unique_ptr<trace_file_writer, trace_file_writer_deleter>
  56     trace_file_writer_up;
  57
  58 /* Save tracepoint data to file named FILENAME through WRITER.  WRITER
  59    determines the trace file format.  If TARGET_DOES_SAVE is non-zero,
  60    the save is performed on the target, otherwise GDB obtains all trace
  61    data and saves it locally.  */
  62
  63 static void
  64 trace_save (const char *filename, struct trace_file_writer *writer,
  65             int target_does_save)
  66 {
  67   struct trace_status *ts = current_trace_status ();
  68   struct uploaded_tp *uploaded_tps = NULL, *utp;
  69   struct uploaded_tsv *uploaded_tsvs = NULL, *utsv;
  70
  71   ULONGEST offset = 0;
  72 #define MAX_TRACE_UPLOAD 2000
  73   gdb::byte_vector buf (std::max (MAX_TRACE_UPLOAD, trace_regblock_size));
  74   bfd_endian byte_order = gdbarch_byte_order (current_inferior ()->arch ());
  75
  76   /* If the target is to save the data to a file on its own, then just
  77      send the command and be done with it.  */
  78   if (target_does_save)
  79     {
  80       if (!writer->ops->target_save (writer, filename))
  81         error (_("Target failed to save trace data to '%s'."),
  82                filename);
  83       return;
  84     }
  85
  86   /* Get the trace status first before opening the file, so if the
  87      target is losing, we can get out without touching files.  Since
  88      we're just calling this for side effects, we ignore the
  89      result.  */
  90   target_get_trace_status (ts);
  91
  92   writer->ops->start (writer, filename);
  93
  94   writer->ops->write_header (writer);
  95
  96   /* Write descriptive info.  */
  97
  98   /* Write out the size of a register block.  */
  99   writer->ops->write_regblock_type (writer, trace_regblock_size);
 100
 101   /* Write out the target description info.  */
 102   writer->ops->write_tdesc (writer);
 103
 104   /* Write out status of the tracing run (aka "tstatus" info).  */
 105   writer->ops->write_status (writer, ts);
 106
 107   /* Note that we want to upload tracepoints and save those, rather
 108      than simply writing out the local ones, because the user may have
 109      changed tracepoints in GDB in preparation for a future tracing
 110      run, or maybe just mass-deleted all types of breakpoints as part
 111      of cleaning up.  So as not to contaminate the session, leave the
 112      data in its uploaded form, don't make into real tracepoints.  */
 113
 114   /* Get trace state variables first, they may be checked when parsing
 115      uploaded commands.  */
 116
 117   target_upload_trace_state_variables (&uploaded_tsvs);
 118
 119   for (utsv = uploaded_tsvs; utsv; utsv = utsv->next)
 120     writer->ops->write_uploaded_tsv (writer, utsv);
 121
 122   free_uploaded_tsvs (&uploaded_tsvs);
 123
 124   target_upload_tracepoints (&uploaded_tps);
 125
 126   for (utp = uploaded_tps; utp; utp = utp->next)
 127     target_get_tracepoint_status (NULL, utp);
 128
 129   for (utp = uploaded_tps; utp; utp = utp->next)
 130     writer->ops->write_uploaded_tp (writer, utp);
 131
 132   free_uploaded_tps (&uploaded_tps);
 133
 134   /* Mark the end of the definition section.  */
 135   writer->ops->write_definition_end (writer);
 136
 137   /* Get and write the trace data proper.  */
 138   while (1)
 139     {
 140       LONGEST gotten = 0;
 141
 142       /* The writer supports writing the contents of trace buffer
 143           directly to trace file.  Don't parse the contents of trace
 144           buffer.  */
 145       if (writer->ops->write_trace_buffer != NULL)
 146         {
 147           /* We ask for big blocks, in the hopes of efficiency, but
 148              will take less if the target has packet size limitations
 149              or some such.  */
 150           gotten = target_get_raw_trace_data (buf.data (), offset,
 151                                               MAX_TRACE_UPLOAD);
 152           if (gotten < 0)
 153             error (_("Failure to get requested trace buffer data"));
 154           /* No more data is forthcoming, we're done.  */
 155           if (gotten == 0)
 156             break;
 157
 158           writer->ops->write_trace_buffer (writer, buf.data (), gotten);
 159
 160           offset += gotten;
 161         }
 162       else
 163         {
 164           uint16_t tp_num;
 165           uint32_t tf_size;
 166           /* Parse the trace buffers according to how data are stored
 167              in trace buffer in GDBserver.  */
 168
 169           gotten = target_get_raw_trace_data (buf.data (), offset, 6);
 170
 171           if (gotten == 0)
 172             break;
 173
 174           /* Read the first six bytes in, which is the tracepoint
 175              number and trace frame size.  */
 176           tp_num = (uint16_t)
 177             extract_unsigned_integer (&((buf.data ())[0]), 2, byte_order);
 178
 179           tf_size = (uint32_t)
 180             extract_unsigned_integer (&((buf.data ())[2]), 4, byte_order);
 181
 182           writer->ops->frame_ops->start (writer, tp_num);
 183           gotten = 6;
 184
 185           if (tf_size > 0)
 186             {
 187               unsigned int block;
 188
 189               offset += 6;
 190
 191               for (block = 0; block < tf_size; )
 192                 {
 193                   gdb_byte block_type;
 194
 195                   /* We'll fetch one block each time, in order to
 196                      handle the extremely large 'M' block.  We first
 197                      fetch one byte to get the type of the block.  */
 198                   gotten = target_get_raw_trace_data (buf.data (),
 199                                                       offset, 1);
 200                   if (gotten < 1)
 201                     error (_("Failure to get requested trace buffer data"));
 202
 203                   gotten = 1;
 204                   block += 1;
 205                   offset += 1;
 206
 207                   block_type = buf[0];
 208                   switch (block_type)
 209                     {
 210                     case 'R':
 211                       gotten
 212                         = target_get_raw_trace_data (buf.data (), offset,
 213                                                      trace_regblock_size);
 214                       if (gotten < trace_regblock_size)
 215                         error (_("Failure to get requested trace"
 216                                  " buffer data"));
 217
 218                       TRACE_WRITE_R_BLOCK (writer, buf.data (),
 219                                            trace_regblock_size);
 220                       break;
 221                     case 'M':
 222                       {
 223                         unsigned short mlen;
 224                         ULONGEST addr;
 225                         LONGEST t;
 226                         int j;
 227
 228                         t = target_get_raw_trace_data (buf.data (),
 229                                                        offset, 10);
 230                         if (t < 10)
 231                           error (_("Failure to get requested trace"
 232                                    " buffer data"));
 233
 234                         offset += 10;
 235                         block += 10;
 236
 237                         gotten = 0;
 238                         addr = (ULONGEST)
 239                           extract_unsigned_integer (buf.data (), 8,
 240                                                     byte_order);
 241                         mlen = (unsigned short)
 242                           extract_unsigned_integer (&((buf.data ())[8]), 2,
 243                                                     byte_order);
 244
 245                         TRACE_WRITE_M_BLOCK_HEADER (writer, addr,
 246                                                     mlen);
 247
 248                         /* The memory contents in 'M' block may be
 249                            very large.  Fetch the data from the target
 250                            and write them into file one by one.  */
 251                         for (j = 0; j < mlen; )
 252                           {
 253                             unsigned int read_length;
 254
 255                             if (mlen - j > MAX_TRACE_UPLOAD)
 256                               read_length = MAX_TRACE_UPLOAD;
 257                             else
 258                               read_length = mlen - j;
 259
 260                             t = target_get_raw_trace_data (buf.data (),
 261                                                            offset + j,
 262                                                            read_length);
 263                             if (t < read_length)
 264                               error (_("Failure to get requested"
 265                                        " trace buffer data"));
 266
 267                             TRACE_WRITE_M_BLOCK_MEMORY (writer,
 268                                                         buf.data (),
 269                                                         read_length);
 270
 271                             j += read_length;
 272                             gotten += read_length;
 273                           }
 274
 275                         break;
 276                       }
 277                     case 'V':
 278                       {
 279                         int vnum;
 280                         LONGEST val;
 281
 282                         gotten
 283                           = target_get_raw_trace_data (buf.data (),
 284                                                        offset, 12);
 285                         if (gotten < 12)
 286                           error (_("Failure to get requested"
 287                                    " trace buffer data"));
 288
 289                         vnum  = (int) extract_signed_integer (buf.data (),
 290                                                               4,
 291                                                               byte_order);
 292                         val
 293                           = extract_signed_integer (&((buf.data ())[4]),
 294                                                     8, byte_order);
 295
 296                         TRACE_WRITE_V_BLOCK (writer, vnum, val);
 297                       }
 298                       break;
 299                     default:
 300                       error (_("Unknown block type '%c' (0x%x) in"
 301                                " trace frame"),
 302                              block_type, block_type);
 303                     }
 304
 305                   block += gotten;
 306                   offset += gotten;
 307                 }
 308             }
 309           else
 310             offset += gotten;
 311
 312           writer->ops->frame_ops->end (writer);
 313         }
 314     }
 315
 316   writer->ops->end (writer);
 317 }
 318
 319 static void
 320 tsave_command (const char *args, int from_tty)
 321 {
 322   int target_does_save = 0;
 323   char **argv;
 324   char *filename = NULL;
 325   int generate_ctf = 0;
 326
 327   if (args == NULL)
 328     error_no_arg (_("file in which to save trace data"));
 329
 330   gdb_argv built_argv (args);
 331   argv = built_argv.get ();
 332
 333   for (; *argv; ++argv)
 334     {
 335       if (strcmp (*argv, "-r") == 0)
 336         target_does_save = 1;
 337       else if (strcmp (*argv, "-ctf") == 0)
 338         generate_ctf = 1;
 339       else if (**argv == '-')
 340         error (_("unknown option `%s'"), *argv);
 341       else
 342         filename = *argv;
 343     }
 344
 345   if (!filename)
 346     error_no_arg (_("file in which to save trace data"));
 347
 348   if (generate_ctf)
 349     trace_save_ctf (filename, target_does_save);
 350   else
 351     trace_save_tfile (filename, target_does_save);
 352
 353   if (from_tty)
 354     gdb_printf (_("Trace data saved to %s '%s'.\n"),
 355                 generate_ctf ? "directory" : "file", filename);
 356 }
 357
 358 /* Save the trace data to file FILENAME of tfile format.  */
 359
 360 void
 361 trace_save_tfile (const char *filename, int target_does_save)
 362 {
 363   trace_file_writer_up writer (tfile_trace_file_writer_new ());
 364   trace_save (filename, writer.get (), target_does_save);
 365 }
 366
 367 /* Save the trace data to dir DIRNAME of ctf format.  */
 368
 369 void
 370 trace_save_ctf (const char *dirname, int target_does_save)
 371 {
 372   trace_file_writer_up writer (ctf_trace_file_writer_new ());
 373   trace_save (dirname, writer.get (), target_does_save);
 374 }
 375
 376 /* Fetch register data from tracefile, shared for both tfile and
 377    ctf.  */
 378
 379 void
 380 tracefile_fetch_registers (struct regcache *regcache, int regno)
 381 {
 382   struct gdbarch *gdbarch = regcache->arch ();
 383   struct tracepoint *tp = get_tracepoint (get_tracepoint_number ());
 384   int regn;
 385
 386   /* We get here if no register data has been found.  Mark registers
 387      as unavailable.  */
 388   for (regn = 0; regn < gdbarch_num_regs (gdbarch); regn++)
 389     regcache->raw_supply (regn, NULL);
 390
 391   /* We can often usefully guess that the PC is going to be the same
 392      as the address of the tracepoint.  */
 393   if (tp == nullptr || !tp->has_locations ())
 394     return;
 395
 396   /* But don't try to guess if tracepoint is multi-location...  */
 397   if (tp->has_multiple_locations ())
 398     {
 399       warning (_("Tracepoint %d has multiple "
 400                  "locations, cannot infer $pc"),
 401                tp->number);
 402       return;
 403     }
 404   /* ... or does while-stepping.  */
 405   else if (tp->step_count > 0)
 406     {
 407       warning (_("Tracepoint %d does while-stepping, "
 408                  "cannot infer $pc"),
 409                tp->number);
 410       return;
 411     }
 412
 413   /* Guess what we can from the tracepoint location.  */
 414   gdbarch_guess_tracepoint_registers (gdbarch, regcache,
 415                                       tp->first_loc ().address);
 416 }
 417
 418 /* This is the implementation of target_ops method to_has_all_memory.  */
 419
 420 bool
 421 tracefile_target::has_all_memory ()
 422 {
 423   return true;
 424 }
 425
 426 /* This is the implementation of target_ops method to_has_memory.  */
 427
 428 bool
 429 tracefile_target::has_memory ()
 430 {
 431   return true;
 432 }
 433
 434 /* This is the implementation of target_ops method to_has_stack.
 435    The target has a stack when GDB has already selected one trace
 436    frame.  */
 437
 438 bool
 439 tracefile_target::has_stack ()
 440 {
 441   return get_traceframe_number () != -1;
 442 }
 443
 444 /* This is the implementation of target_ops method to_has_registers.
 445    The target has registers when GDB has already selected one trace
 446    frame.  */
 447
 448 bool
 449 tracefile_target::has_registers ()
 450 {
 451   return get_traceframe_number () != -1;
 452 }
 453
 454 /* This is the implementation of target_ops method to_thread_alive.
 455    tracefile has one thread faked by GDB.  */
 456
 457 bool
 458 tracefile_target::thread_alive (ptid_t ptid)
 459 {
 460   return true;
 461 }
 462
 463 /* This is the implementation of target_ops method to_get_trace_status.
 464    The trace status for a file is that tracing can never be run.  */
 465
 466 int
 467 tracefile_target::get_trace_status (struct trace_status *ts)
 468 {
 469   /* Other bits of trace status were collected as part of opening the
 470      trace files, so nothing to do here.  */
 471
 472   return -1;
 473 }
 474
 475 void _initialize_tracefile ();
 476 void
 477 _initialize_tracefile ()
 478 {
 479   add_com ("tsave", class_trace, tsave_command, _("\
 480 Save the trace data to a file.\n\
 481 Use the '-ctf' option to save the data to CTF format.\n\
 482 Use the '-r' option to direct the target to save directly to the file,\n\
 483 using its own filesystem."));
 484 }