gdb/btrace.h

   1 /* Branch trace support for GDB, the GNU debugger.
   2
   3    Copyright (C) 2013-2015 Free Software Foundation, Inc.
   4
   5    Contributed by Intel Corp. <markus.t.metzger@intel.com>.
   6
   7    This file is part of GDB.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  21
  22 #ifndef BTRACE_H
  23 #define BTRACE_H
  24
  25 /* Branch tracing (btrace) is a per-thread control-flow execution trace of the
  26    inferior.  For presentation purposes, the branch trace is represented as a
  27    list of sequential control-flow blocks, one such list per thread.  */
  28
  29 #include "btrace-common.h"
  30 #include "target/waitstatus.h" /* For enum target_stop_reason.  */
  31
  32 #if defined (HAVE_LIBIPT)
  33 #  include <intel-pt.h>
  34 #endif
  35
  36 struct thread_info;
  37 struct btrace_function;
  38
  39 /* A coarse instruction classification.  */
  40 enum btrace_insn_class
  41 {
  42   /* The instruction is something not listed below.  */
  43   BTRACE_INSN_OTHER,
  44
  45   /* The instruction is a function call.  */
  46   BTRACE_INSN_CALL,
  47
  48   /* The instruction is a function return.  */
  49   BTRACE_INSN_RETURN,
  50
  51   /* The instruction is an unconditional jump.  */
  52   BTRACE_INSN_JUMP
  53 };
  54
  55 /* Instruction flags.  */
  56 enum btrace_insn_flag
  57 {
  58   /* The instruction has been executed speculatively.  */
  59   BTRACE_INSN_FLAG_SPECULATIVE = (1 << 0)
  60 };
  61
  62 /* A branch trace instruction.
  63
  64    This represents a single instruction in a branch trace.  */
  65 struct btrace_insn
  66 {
  67   /* The address of this instruction.  */
  68   CORE_ADDR pc;
  69
  70   /* The size of this instruction in bytes.  */
  71   gdb_byte size;
  72
  73   /* The instruction class of this instruction.  */
  74   enum btrace_insn_class iclass;
  75
  76   /* A bit vector of BTRACE_INSN_FLAGS.  */
  77   enum btrace_insn_flag flags;
  78 };
  79
  80 /* A vector of branch trace instructions.  */
  81 typedef struct btrace_insn btrace_insn_s;
  82 DEF_VEC_O (btrace_insn_s);
  83
  84 /* A doubly-linked list of branch trace function segments.  */
  85 struct btrace_func_link
  86 {
  87   struct btrace_function *prev;
  88   struct btrace_function *next;
  89 };
  90
  91 /* Flags for btrace function segments.  */
  92 enum btrace_function_flag
  93 {
  94   /* The 'up' link interpretation.
  95      If set, it points to the function segment we returned to.
  96      If clear, it points to the function segment we called from.  */
  97   BFUN_UP_LINKS_TO_RET = (1 << 0),
  98
  99   /* The 'up' link points to a tail call.  This obviously only makes sense
 100      if bfun_up_links_to_ret is clear.  */
 101   BFUN_UP_LINKS_TO_TAILCALL = (1 << 1)
 102 };
 103
 104 /* Decode errors for the BTS recording format.  */
 105 enum btrace_bts_error
 106 {
 107   /* The instruction trace overflowed the end of the trace block.  */
 108   BDE_BTS_OVERFLOW = 1,
 109
 110   /* The instruction size could not be determined.  */
 111   BDE_BTS_INSN_SIZE
 112 };
 113
 114 /* Decode errors for the Intel(R) Processor Trace recording format.  */
 115 enum btrace_pt_error
 116 {
 117   /* The user cancelled trace processing.  */
 118   BDE_PT_USER_QUIT = 1,
 119
 120   /* Tracing was temporarily disabled.  */
 121   BDE_PT_DISABLED,
 122
 123   /* Trace recording overflowed.  */
 124   BDE_PT_OVERFLOW
 125
 126   /* Negative numbers are used by the decoder library.  */
 127 };
 128
 129 /* A branch trace function segment.
 130
 131    This represents a function segment in a branch trace, i.e. a consecutive
 132    number of instructions belonging to the same function.
 133
 134    In case of decode errors, we add an empty function segment to indicate
 135    the gap in the trace.
 136
 137    We do not allow function segments without instructions otherwise.  */
 138 struct btrace_function
 139 {
 140   /* The full and minimal symbol for the function.  Both may be NULL.  */
 141   struct minimal_symbol *msym;
 142   struct symbol *sym;
 143
 144   /* The previous and next segment belonging to the same function.
 145      If a function calls another function, the former will have at least
 146      two segments: one before the call and another after the return.  */
 147   struct btrace_func_link segment;
 148
 149   /* The previous and next function in control flow order.  */
 150   struct btrace_func_link flow;
 151
 152   /* The directly preceding function segment in a (fake) call stack.  */
 153   struct btrace_function *up;
 154
 155   /* The instructions in this function segment.
 156      The instruction vector will be empty if the function segment
 157      represents a decode error.  */
 158   VEC (btrace_insn_s) *insn;
 159
 160   /* The error code of a decode error that led to a gap.
 161      Must be zero unless INSN is empty; non-zero otherwise.  */
 162   int errcode;
 163
 164   /* The instruction number offset for the first instruction in this
 165      function segment.
 166      If INSN is empty this is the insn_offset of the succeding function
 167      segment in control-flow order.  */
 168   unsigned int insn_offset;
 169
 170   /* The function number in control-flow order.
 171      If INSN is empty indicating a gap in the trace due to a decode error,
 172      we still count the gap as a function.  */
 173   unsigned int number;
 174
 175   /* The function level in a back trace across the entire branch trace.
 176      A caller's level is one lower than the level of its callee.
 177
 178      Levels can be negative if we see returns for which we have not seen
 179      the corresponding calls.  The branch trace thread information provides
 180      a fixup to normalize function levels so the smallest level is zero.  */
 181   int level;
 182
 183   /* A bit-vector of btrace_function_flag.  */
 184   enum btrace_function_flag flags;
 185 };
 186
 187 /* A branch trace instruction iterator.  */
 188 struct btrace_insn_iterator
 189 {
 190   /* The branch trace function segment containing the instruction.
 191      Will never be NULL.  */
 192   const struct btrace_function *function;
 193
 194   /* The index into the function segment's instruction vector.  */
 195   unsigned int index;
 196 };
 197
 198 /* A branch trace function call iterator.  */
 199 struct btrace_call_iterator
 200 {
 201   /* The branch trace information for this thread.  Will never be NULL.  */
 202   const struct btrace_thread_info *btinfo;
 203
 204   /* The branch trace function segment.
 205      This will be NULL for the iterator pointing to the end of the trace.  */
 206   const struct btrace_function *function;
 207 };
 208
 209 /* Branch trace iteration state for "record instruction-history".  */
 210 struct btrace_insn_history
 211 {
 212   /* The branch trace instruction range from BEGIN (inclusive) to
 213      END (exclusive) that has been covered last time.  */
 214   struct btrace_insn_iterator begin;
 215   struct btrace_insn_iterator end;
 216 };
 217
 218 /* Branch trace iteration state for "record function-call-history".  */
 219 struct btrace_call_history
 220 {
 221   /* The branch trace function range from BEGIN (inclusive) to END (exclusive)
 222      that has been covered last time.  */
 223   struct btrace_call_iterator begin;
 224   struct btrace_call_iterator end;
 225 };
 226
 227 /* Branch trace thread flags.  */
 228 enum btrace_thread_flag
 229 {
 230   /* The thread is to be stepped forwards.  */
 231   BTHR_STEP = (1 << 0),
 232
 233   /* The thread is to be stepped backwards.  */
 234   BTHR_RSTEP = (1 << 1),
 235
 236   /* The thread is to be continued forwards.  */
 237   BTHR_CONT = (1 << 2),
 238
 239   /* The thread is to be continued backwards.  */
 240   BTHR_RCONT = (1 << 3),
 241
 242   /* The thread is to be moved.  */
 243   BTHR_MOVE = (BTHR_STEP | BTHR_RSTEP | BTHR_CONT | BTHR_RCONT),
 244
 245   /* The thread is to be stopped.  */
 246   BTHR_STOP = (1 << 4)
 247 };
 248
 249 #if defined (HAVE_LIBIPT)
 250 /* A packet.  */
 251 struct btrace_pt_packet
 252 {
 253   /* The offset in the trace stream.  */
 254   uint64_t offset;
 255
 256   /* The decode error code.  */
 257   enum pt_error_code errcode;
 258
 259   /* The decoded packet.  Only valid if ERRCODE == pte_ok.  */
 260   struct pt_packet packet;
 261 };
 262
 263 /* Define functions operating on a vector of packets.  */
 264 typedef struct btrace_pt_packet btrace_pt_packet_s;
 265 DEF_VEC_O (btrace_pt_packet_s);
 266 #endif /* defined (HAVE_LIBIPT)  */
 267
 268 /* Branch trace iteration state for "maintenance btrace packet-history".  */
 269 struct btrace_maint_packet_history
 270 {
 271   /* The branch trace packet range from BEGIN (inclusive) to
 272      END (exclusive) that has been covered last time.  */
 273   unsigned int begin;
 274   unsigned int end;
 275 };
 276
 277 /* Branch trace maintenance information per thread.
 278
 279    This information is used by "maintenance btrace" commands.  */
 280 struct btrace_maint_info
 281 {
 282   /* Most information is format-specific.
 283      The format can be found in the BTRACE.DATA.FORMAT field of each thread.  */
 284   union
 285   {
 286     /* BTRACE.DATA.FORMAT == BTRACE_FORMAT_BTS  */
 287     struct
 288     {
 289       /* The packet history iterator.
 290          We are iterating over BTRACE.DATA.FORMAT.VARIANT.BTS.BLOCKS.  */
 291       struct btrace_maint_packet_history packet_history;
 292     } bts;
 293
 294 #if defined (HAVE_LIBIPT)
 295     /* BTRACE.DATA.FORMAT == BTRACE_FORMAT_PT  */
 296     struct
 297     {
 298       /* A vector of decoded packets.  */
 299       VEC (btrace_pt_packet_s) *packets;
 300
 301       /* The packet history iterator.
 302          We are iterating over the above PACKETS vector.  */
 303       struct btrace_maint_packet_history packet_history;
 304     } pt;
 305 #endif /* defined (HAVE_LIBIPT)  */
 306   } variant;
 307 };
 308
 309 /* Branch trace information per thread.
 310
 311    This represents the branch trace configuration as well as the entry point
 312    into the branch trace data.  For the latter, it also contains the index into
 313    an array of branch trace blocks used for iterating though the branch trace
 314    blocks of a thread.  */
 315 struct btrace_thread_info
 316 {
 317   /* The target branch trace information for this thread.
 318
 319      This contains the branch trace configuration as well as any
 320      target-specific information necessary for implementing branch tracing on
 321      the underlying architecture.  */
 322   struct btrace_target_info *target;
 323
 324   /* The raw branch trace data for the below branch trace.  */
 325   struct btrace_data data;
 326
 327   /* The current branch trace for this thread (both inclusive).
 328
 329      The last instruction of END is the current instruction, which is not
 330      part of the execution history.
 331      Both will be NULL if there is no branch trace available.  If there is
 332      branch trace available, both will be non-NULL.  */
 333   struct btrace_function *begin;
 334   struct btrace_function *end;
 335
 336   /* The function level offset.  When added to each function's LEVEL,
 337      this normalizes the function levels such that the smallest level
 338      becomes zero.  */
 339   int level;
 340
 341   /* The number of gaps in the trace.  */
 342   unsigned int ngaps;
 343
 344   /* A bit-vector of btrace_thread_flag.  */
 345   enum btrace_thread_flag flags;
 346
 347   /* The instruction history iterator.  */
 348   struct btrace_insn_history *insn_history;
 349
 350   /* The function call history iterator.  */
 351   struct btrace_call_history *call_history;
 352
 353   /* The current replay position.  NULL if not replaying.
 354      Gaps are skipped during replay, so REPLAY always points to a valid
 355      instruction.  */
 356   struct btrace_insn_iterator *replay;
 357
 358   /* Why the thread stopped, if we need to track it.  */
 359   enum target_stop_reason stop_reason;
 360
 361   /* Maintenance information.  */
 362   struct btrace_maint_info maint;
 363 };
 364
 365 /* Enable branch tracing for a thread.  */
 366 extern void btrace_enable (struct thread_info *tp,
 367                            const struct btrace_config *conf);
 368
 369 /* Get the branch trace configuration for a thread.
 370    Return NULL if branch tracing is not enabled for that thread.  */
 371 extern const struct btrace_config *
 372   btrace_conf (const struct btrace_thread_info *);
 373
 374 /* Disable branch tracing for a thread.
 375    This will also delete the current branch trace data.  */
 376 extern void btrace_disable (struct thread_info *);
 377
 378 /* Disable branch tracing for a thread during teardown.
 379    This is similar to btrace_disable, except that it will use
 380    target_teardown_btrace instead of target_disable_btrace.  */
 381 extern void btrace_teardown (struct thread_info *);
 382
 383 /* Fetch the branch trace for a single thread.  */
 384 extern void btrace_fetch (struct thread_info *);
 385
 386 /* Clear the branch trace for a single thread.  */
 387 extern void btrace_clear (struct thread_info *);
 388
 389 /* Clear the branch trace for all threads when an object file goes away.  */
 390 extern void btrace_free_objfile (struct objfile *);
 391
 392 /* Parse a branch trace xml document XML into DATA.  */
 393 extern void parse_xml_btrace (struct btrace_data *data, const char *xml);
 394
 395 /* Parse a branch trace configuration xml document XML into CONF.  */
 396 extern void parse_xml_btrace_conf (struct btrace_config *conf, const char *xml);
 397
 398 /* Dereference a branch trace instruction iterator.  Return a pointer to the
 399    instruction the iterator points to.
 400    May return NULL if the iterator points to a gap in the trace.  */
 401 extern const struct btrace_insn *
 402   btrace_insn_get (const struct btrace_insn_iterator *);
 403
 404 /* Return the instruction number for a branch trace iterator.
 405    Returns one past the maximum instruction number for the end iterator.
 406    Returns zero if the iterator does not point to a valid instruction.  */
 407 extern unsigned int btrace_insn_number (const struct btrace_insn_iterator *);
 408
 409 /* Initialize a branch trace instruction iterator to point to the begin/end of
 410    the branch trace.  Throws an error if there is no branch trace.  */
 411 extern void btrace_insn_begin (struct btrace_insn_iterator *,
 412                                const struct btrace_thread_info *);
 413 extern void btrace_insn_end (struct btrace_insn_iterator *,
 414                              const struct btrace_thread_info *);
 415
 416 /* Increment/decrement a branch trace instruction iterator by at most STRIDE
 417    instructions.  Return the number of instructions by which the instruction
 418    iterator has been advanced.
 419    Returns zero, if the operation failed or STRIDE had been zero.  */
 420 extern unsigned int btrace_insn_next (struct btrace_insn_iterator *,
 421                                       unsigned int stride);
 422 extern unsigned int btrace_insn_prev (struct btrace_insn_iterator *,
 423                                       unsigned int stride);
 424
 425 /* Compare two branch trace instruction iterators.
 426    Return a negative number if LHS < RHS.
 427    Return zero if LHS == RHS.
 428    Return a positive number if LHS > RHS.  */
 429 extern int btrace_insn_cmp (const struct btrace_insn_iterator *lhs,
 430                             const struct btrace_insn_iterator *rhs);
 431
 432 /* Find an instruction in the function branch trace by its number.
 433    If the instruction is found, initialize the branch trace instruction
 434    iterator to point to this instruction and return non-zero.
 435    Return zero otherwise.  */
 436 extern int btrace_find_insn_by_number (struct btrace_insn_iterator *,
 437                                        const struct btrace_thread_info *,
 438                                        unsigned int number);
 439
 440 /* Dereference a branch trace call iterator.  Return a pointer to the
 441    function the iterator points to or NULL if the interator points past
 442    the end of the branch trace.  */
 443 extern const struct btrace_function *
 444   btrace_call_get (const struct btrace_call_iterator *);
 445
 446 /* Return the function number for a branch trace call iterator.
 447    Returns one past the maximum function number for the end iterator.
 448    Returns zero if the iterator does not point to a valid function.  */
 449 extern unsigned int btrace_call_number (const struct btrace_call_iterator *);
 450
 451 /* Initialize a branch trace call iterator to point to the begin/end of
 452    the branch trace.  Throws an error if there is no branch trace.  */
 453 extern void btrace_call_begin (struct btrace_call_iterator *,
 454                                const struct btrace_thread_info *);
 455 extern void btrace_call_end (struct btrace_call_iterator *,
 456                              const struct btrace_thread_info *);
 457
 458 /* Increment/decrement a branch trace call iterator by at most STRIDE function
 459    segments.  Return the number of function segments by which the call
 460    iterator has been advanced.
 461    Returns zero, if the operation failed or STRIDE had been zero.  */
 462 extern unsigned int btrace_call_next (struct btrace_call_iterator *,
 463                                       unsigned int stride);
 464 extern unsigned int btrace_call_prev (struct btrace_call_iterator *,
 465                                       unsigned int stride);
 466
 467 /* Compare two branch trace call iterators.
 468    Return a negative number if LHS < RHS.
 469    Return zero if LHS == RHS.
 470    Return a positive number if LHS > RHS.  */
 471 extern int btrace_call_cmp (const struct btrace_call_iterator *lhs,
 472                             const struct btrace_call_iterator *rhs);
 473
 474 /* Find a function in the function branch trace by its NUMBER.
 475    If the function is found, initialize the branch trace call
 476    iterator to point to this function and return non-zero.
 477    Return zero otherwise.  */
 478 extern int btrace_find_call_by_number (struct btrace_call_iterator *,
 479                                        const struct btrace_thread_info *,
 480                                        unsigned int number);
 481
 482 /* Set the branch trace instruction history from BEGIN (inclusive) to
 483    END (exclusive).  */
 484 extern void btrace_set_insn_history (struct btrace_thread_info *,
 485                                      const struct btrace_insn_iterator *begin,
 486                                      const struct btrace_insn_iterator *end);
 487
 488 /* Set the branch trace function call history from BEGIN (inclusive) to
 489    END (exclusive).  */
 490 extern void btrace_set_call_history (struct btrace_thread_info *,
 491                                      const struct btrace_call_iterator *begin,
 492                                      const struct btrace_call_iterator *end);
 493
 494 /* Determine if branch tracing is currently replaying TP.  */
 495 extern int btrace_is_replaying (struct thread_info *tp);
 496
 497 /* Return non-zero if the branch trace for TP is empty; zero otherwise.  */
 498 extern int btrace_is_empty (struct thread_info *tp);
 499
 500 /* Create a cleanup for DATA.  */
 501 extern struct cleanup *make_cleanup_btrace_data (struct btrace_data *data);
 502
 503 #endif /* BTRACE_H */