gdb/btrace.h

   1 /* Branch trace support for GDB, the GNU debugger.
   2
   3    Copyright (C) 2013-2017 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 #include "common/enum-flags.h"
  32
  33 #if defined (HAVE_LIBIPT)
  34 #  include <intel-pt.h>
  35 #endif
  36
  37 #include <vector>
  38
  39 struct thread_info;
  40 struct btrace_function;
  41
  42 /* A coarse instruction classification.  */
  43 enum btrace_insn_class
  44 {
  45   /* The instruction is something not listed below.  */
  46   BTRACE_INSN_OTHER,
  47
  48   /* The instruction is a function call.  */
  49   BTRACE_INSN_CALL,
  50
  51   /* The instruction is a function return.  */
  52   BTRACE_INSN_RETURN,
  53
  54   /* The instruction is an unconditional jump.  */
  55   BTRACE_INSN_JUMP
  56 };
  57
  58 /* Instruction flags.  */
  59 enum btrace_insn_flag
  60 {
  61   /* The instruction has been executed speculatively.  */
  62   BTRACE_INSN_FLAG_SPECULATIVE = (1 << 0)
  63 };
  64 DEF_ENUM_FLAGS_TYPE (enum btrace_insn_flag, btrace_insn_flags);
  65
  66 /* A branch trace instruction.
  67
  68    This represents a single instruction in a branch trace.  */
  69 struct btrace_insn
  70 {
  71   /* The address of this instruction.  */
  72   CORE_ADDR pc;
  73
  74   /* The size of this instruction in bytes.  */
  75   gdb_byte size;
  76
  77   /* The instruction class of this instruction.  */
  78   enum btrace_insn_class iclass;
  79
  80   /* A bit vector of BTRACE_INSN_FLAGS.  */
  81   btrace_insn_flags flags;
  82 };
  83
  84 /* A vector of branch trace instructions.  */
  85 typedef struct btrace_insn btrace_insn_s;
  86 DEF_VEC_O (btrace_insn_s);
  87
  88 /* Flags for btrace function segments.  */
  89 enum btrace_function_flag
  90 {
  91   /* The 'up' link interpretation.
  92      If set, it points to the function segment we returned to.
  93      If clear, it points to the function segment we called from.  */
  94   BFUN_UP_LINKS_TO_RET = (1 << 0),
  95
  96   /* The 'up' link points to a tail call.  This obviously only makes sense
  97      if bfun_up_links_to_ret is clear.  */
  98   BFUN_UP_LINKS_TO_TAILCALL = (1 << 1)
  99 };
 100 DEF_ENUM_FLAGS_TYPE (enum btrace_function_flag, btrace_function_flags);
 101
 102 /* Decode errors for the BTS recording format.  */
 103 enum btrace_bts_error
 104 {
 105   /* The instruction trace overflowed the end of the trace block.  */
 106   BDE_BTS_OVERFLOW = 1,
 107
 108   /* The instruction size could not be determined.  */
 109   BDE_BTS_INSN_SIZE
 110 };
 111
 112 /* Decode errors for the Intel Processor Trace recording format.  */
 113 enum btrace_pt_error
 114 {
 115   /* The user cancelled trace processing.  */
 116   BDE_PT_USER_QUIT = 1,
 117
 118   /* Tracing was temporarily disabled.  */
 119   BDE_PT_DISABLED,
 120
 121   /* Trace recording overflowed.  */
 122   BDE_PT_OVERFLOW
 123
 124   /* Negative numbers are used by the decoder library.  */
 125 };
 126
 127 /* A branch trace function segment.
 128
 129    This represents a function segment in a branch trace, i.e. a consecutive
 130    number of instructions belonging to the same function.
 131
 132    In case of decode errors, we add an empty function segment to indicate
 133    the gap in the trace.
 134
 135    We do not allow function segments without instructions otherwise.  */
 136 struct btrace_function
 137 {
 138   btrace_function (struct minimal_symbol *msym_, struct symbol *sym_,
 139                    unsigned int number_, unsigned int insn_offset_, int level_)
 140     : msym (msym_), sym (sym_), insn_offset (insn_offset_), number (number_),
 141       level (level_)
 142   {
 143   }
 144
 145   /* The full and minimal symbol for the function.  Both may be NULL.  */
 146   struct minimal_symbol *msym;
 147   struct symbol *sym;
 148
 149   /* The function segment numbers of the previous and next segment belonging to
 150      the same function.  If a function calls another function, the former will
 151      have at least two segments: one before the call and another after the
 152      return.  Will be zero if there is no such function segment.  */
 153   unsigned int prev = 0;
 154   unsigned int next = 0;
 155
 156   /* The function segment number of the directly preceding function segment in
 157      a (fake) call stack.  Will be zero if there is no such function segment in
 158      the record.  */
 159   unsigned int up = 0;
 160
 161   /* The instructions in this function segment.
 162      The instruction vector will be empty if the function segment
 163      represents a decode error.  */
 164   VEC (btrace_insn_s) *insn = NULL;
 165
 166   /* The error code of a decode error that led to a gap.
 167      Must be zero unless INSN is empty; non-zero otherwise.  */
 168   int errcode = 0;
 169
 170   /* The instruction number offset for the first instruction in this
 171      function segment.
 172      If INSN is empty this is the insn_offset of the succeding function
 173      segment in control-flow order.  */
 174   unsigned int insn_offset;
 175
 176   /* The 1-based function number in control-flow order.
 177      If INSN is empty indicating a gap in the trace due to a decode error,
 178      we still count the gap as a function.  */
 179   unsigned int number;
 180
 181   /* The function level in a back trace across the entire branch trace.
 182      A caller's level is one lower than the level of its callee.
 183
 184      Levels can be negative if we see returns for which we have not seen
 185      the corresponding calls.  The branch trace thread information provides
 186      a fixup to normalize function levels so the smallest level is zero.  */
 187   int level;
 188
 189   /* A bit-vector of btrace_function_flag.  */
 190   btrace_function_flags flags = 0;
 191 };
 192
 193 /* A branch trace instruction iterator.  */
 194 struct btrace_insn_iterator
 195 {
 196   /* The branch trace information for this thread.  Will never be NULL.  */
 197   const struct btrace_thread_info *btinfo;
 198
 199   /* The index of the function segment in BTINFO->FUNCTIONS.  */
 200   unsigned int call_index;
 201
 202   /* The index into the function segment's instruction vector.  */
 203   unsigned int insn_index;
 204 };
 205
 206 /* A branch trace function call iterator.  */
 207 struct btrace_call_iterator
 208 {
 209   /* The branch trace information for this thread.  Will never be NULL.  */
 210   const struct btrace_thread_info *btinfo;
 211
 212   /* The index of the function segment in BTINFO->FUNCTIONS.  */
 213   unsigned int index;
 214 };
 215
 216 /* Branch trace iteration state for "record instruction-history".  */
 217 struct btrace_insn_history
 218 {
 219   /* The branch trace instruction range from BEGIN (inclusive) to
 220      END (exclusive) that has been covered last time.  */
 221   struct btrace_insn_iterator begin;
 222   struct btrace_insn_iterator end;
 223 };
 224
 225 /* Branch trace iteration state for "record function-call-history".  */
 226 struct btrace_call_history
 227 {
 228   /* The branch trace function range from BEGIN (inclusive) to END (exclusive)
 229      that has been covered last time.  */
 230   struct btrace_call_iterator begin;
 231   struct btrace_call_iterator end;
 232 };
 233
 234 /* Branch trace thread flags.  */
 235 enum btrace_thread_flag
 236 {
 237   /* The thread is to be stepped forwards.  */
 238   BTHR_STEP = (1 << 0),
 239
 240   /* The thread is to be stepped backwards.  */
 241   BTHR_RSTEP = (1 << 1),
 242
 243   /* The thread is to be continued forwards.  */
 244   BTHR_CONT = (1 << 2),
 245
 246   /* The thread is to be continued backwards.  */
 247   BTHR_RCONT = (1 << 3),
 248
 249   /* The thread is to be moved.  */
 250   BTHR_MOVE = (BTHR_STEP | BTHR_RSTEP | BTHR_CONT | BTHR_RCONT),
 251
 252   /* The thread is to be stopped.  */
 253   BTHR_STOP = (1 << 4)
 254 };
 255 DEF_ENUM_FLAGS_TYPE (enum btrace_thread_flag, btrace_thread_flags);
 256
 257 #if defined (HAVE_LIBIPT)
 258 /* A packet.  */
 259 struct btrace_pt_packet
 260 {
 261   /* The offset in the trace stream.  */
 262   uint64_t offset;
 263
 264   /* The decode error code.  */
 265   enum pt_error_code errcode;
 266
 267   /* The decoded packet.  Only valid if ERRCODE == pte_ok.  */
 268   struct pt_packet packet;
 269 };
 270
 271 /* Define functions operating on a vector of packets.  */
 272 typedef struct btrace_pt_packet btrace_pt_packet_s;
 273 DEF_VEC_O (btrace_pt_packet_s);
 274 #endif /* defined (HAVE_LIBIPT)  */
 275
 276 /* Branch trace iteration state for "maintenance btrace packet-history".  */
 277 struct btrace_maint_packet_history
 278 {
 279   /* The branch trace packet range from BEGIN (inclusive) to
 280      END (exclusive) that has been covered last time.  */
 281   unsigned int begin;
 282   unsigned int end;
 283 };
 284
 285 /* Branch trace maintenance information per thread.
 286
 287    This information is used by "maintenance btrace" commands.  */
 288 struct btrace_maint_info
 289 {
 290   /* Most information is format-specific.
 291      The format can be found in the BTRACE.DATA.FORMAT field of each thread.  */
 292   union
 293   {
 294     /* BTRACE.DATA.FORMAT == BTRACE_FORMAT_BTS  */
 295     struct
 296     {
 297       /* The packet history iterator.
 298          We are iterating over BTRACE.DATA.FORMAT.VARIANT.BTS.BLOCKS.  */
 299       struct btrace_maint_packet_history packet_history;
 300     } bts;
 301
 302 #if defined (HAVE_LIBIPT)
 303     /* BTRACE.DATA.FORMAT == BTRACE_FORMAT_PT  */
 304     struct
 305     {
 306       /* A vector of decoded packets.  */
 307       VEC (btrace_pt_packet_s) *packets;
 308
 309       /* The packet history iterator.
 310          We are iterating over the above PACKETS vector.  */
 311       struct btrace_maint_packet_history packet_history;
 312     } pt;
 313 #endif /* defined (HAVE_LIBIPT)  */
 314   } variant;
 315 };
 316
 317 /* Branch trace information per thread.
 318
 319    This represents the branch trace configuration as well as the entry point
 320    into the branch trace data.  For the latter, it also contains the index into
 321    an array of branch trace blocks used for iterating though the branch trace
 322    blocks of a thread.  */
 323 struct btrace_thread_info
 324 {
 325   /* The target branch trace information for this thread.
 326
 327      This contains the branch trace configuration as well as any
 328      target-specific information necessary for implementing branch tracing on
 329      the underlying architecture.  */
 330   struct btrace_target_info *target;
 331
 332   /* The raw branch trace data for the below branch trace.  */
 333   struct btrace_data data;
 334
 335   /* Vector of decoded function segments in execution flow order.
 336      Note that the numbering for btrace function segments starts with 1, so
 337      function segment i will be at index (i - 1).  */
 338   std::vector<btrace_function> functions;
 339
 340   /* The function level offset.  When added to each function's LEVEL,
 341      this normalizes the function levels such that the smallest level
 342      becomes zero.  */
 343   int level;
 344
 345   /* The number of gaps in the trace.  */
 346   unsigned int ngaps;
 347
 348   /* A bit-vector of btrace_thread_flag.  */
 349   btrace_thread_flags flags;
 350
 351   /* The instruction history iterator.  */
 352   struct btrace_insn_history *insn_history;
 353
 354   /* The function call history iterator.  */
 355   struct btrace_call_history *call_history;
 356
 357   /* The current replay position.  NULL if not replaying.
 358      Gaps are skipped during replay, so REPLAY always points to a valid
 359      instruction.  */
 360   struct btrace_insn_iterator *replay;
 361
 362   /* Why the thread stopped, if we need to track it.  */
 363   enum target_stop_reason stop_reason;
 364
 365   /* Maintenance information.  */
 366   struct btrace_maint_info maint;
 367 };
 368
 369 /* Enable branch tracing for a thread.  */
 370 extern void btrace_enable (struct thread_info *tp,
 371                            const struct btrace_config *conf);
 372
 373 /* Get the branch trace configuration for a thread.
 374    Return NULL if branch tracing is not enabled for that thread.  */
 375 extern const struct btrace_config *
 376   btrace_conf (const struct btrace_thread_info *);
 377
 378 /* Disable branch tracing for a thread.
 379    This will also delete the current branch trace data.  */
 380 extern void btrace_disable (struct thread_info *);
 381
 382 /* Disable branch tracing for a thread during teardown.
 383    This is similar to btrace_disable, except that it will use
 384    target_teardown_btrace instead of target_disable_btrace.  */
 385 extern void btrace_teardown (struct thread_info *);
 386
 387 /* Return a human readable error string for the given ERRCODE in FORMAT.
 388    The pointer will never be NULL and must not be freed.  */
 389
 390 extern const char *btrace_decode_error (enum btrace_format format, int errcode);
 391
 392 /* Fetch the branch trace for a single thread.  */
 393 extern void btrace_fetch (struct thread_info *);
 394
 395 /* Clear the branch trace for a single thread.  */
 396 extern void btrace_clear (struct thread_info *);
 397
 398 /* Clear the branch trace for all threads when an object file goes away.  */
 399 extern void btrace_free_objfile (struct objfile *);
 400
 401 /* Parse a branch trace xml document XML into DATA.  */
 402 extern void parse_xml_btrace (struct btrace_data *data, const char *xml);
 403
 404 /* Parse a branch trace configuration xml document XML into CONF.  */
 405 extern void parse_xml_btrace_conf (struct btrace_config *conf, const char *xml);
 406
 407 /* Dereference a branch trace instruction iterator.  Return a pointer to the
 408    instruction the iterator points to.
 409    May return NULL if the iterator points to a gap in the trace.  */
 410 extern const struct btrace_insn *
 411   btrace_insn_get (const struct btrace_insn_iterator *);
 412
 413 /* Return the error code for a branch trace instruction iterator.  Returns zero
 414    if there is no error, i.e. the instruction is valid.  */
 415 extern int btrace_insn_get_error (const struct btrace_insn_iterator *);
 416
 417 /* Return the instruction number for a branch trace iterator.
 418    Returns one past the maximum instruction number for the end iterator.  */
 419 extern unsigned int btrace_insn_number (const struct btrace_insn_iterator *);
 420
 421 /* Initialize a branch trace instruction iterator to point to the begin/end of
 422    the branch trace.  Throws an error if there is no branch trace.  */
 423 extern void btrace_insn_begin (struct btrace_insn_iterator *,
 424                                const struct btrace_thread_info *);
 425 extern void btrace_insn_end (struct btrace_insn_iterator *,
 426                              const struct btrace_thread_info *);
 427
 428 /* Increment/decrement a branch trace instruction iterator by at most STRIDE
 429    instructions.  Return the number of instructions by which the instruction
 430    iterator has been advanced.
 431    Returns zero, if the operation failed or STRIDE had been zero.  */
 432 extern unsigned int btrace_insn_next (struct btrace_insn_iterator *,
 433                                       unsigned int stride);
 434 extern unsigned int btrace_insn_prev (struct btrace_insn_iterator *,
 435                                       unsigned int stride);
 436
 437 /* Compare two branch trace instruction iterators.
 438    Return a negative number if LHS < RHS.
 439    Return zero if LHS == RHS.
 440    Return a positive number if LHS > RHS.  */
 441 extern int btrace_insn_cmp (const struct btrace_insn_iterator *lhs,
 442                             const struct btrace_insn_iterator *rhs);
 443
 444 /* Find an instruction or gap in the function branch trace by its number.
 445    If the instruction is found, initialize the branch trace instruction
 446    iterator to point to this instruction and return non-zero.
 447    Return zero otherwise.  */
 448 extern int btrace_find_insn_by_number (struct btrace_insn_iterator *,
 449                                        const struct btrace_thread_info *,
 450                                        unsigned int number);
 451
 452 /* Dereference a branch trace call iterator.  Return a pointer to the
 453    function the iterator points to or NULL if the interator points past
 454    the end of the branch trace.  */
 455 extern const struct btrace_function *
 456   btrace_call_get (const struct btrace_call_iterator *);
 457
 458 /* Return the function number for a branch trace call iterator.
 459    Returns one past the maximum function number for the end iterator.
 460    Returns zero if the iterator does not point to a valid function.  */
 461 extern unsigned int btrace_call_number (const struct btrace_call_iterator *);
 462
 463 /* Initialize a branch trace call iterator to point to the begin/end of
 464    the branch trace.  Throws an error if there is no branch trace.  */
 465 extern void btrace_call_begin (struct btrace_call_iterator *,
 466                                const struct btrace_thread_info *);
 467 extern void btrace_call_end (struct btrace_call_iterator *,
 468                              const struct btrace_thread_info *);
 469
 470 /* Increment/decrement a branch trace call iterator by at most STRIDE function
 471    segments.  Return the number of function segments by which the call
 472    iterator has been advanced.
 473    Returns zero, if the operation failed or STRIDE had been zero.  */
 474 extern unsigned int btrace_call_next (struct btrace_call_iterator *,
 475                                       unsigned int stride);
 476 extern unsigned int btrace_call_prev (struct btrace_call_iterator *,
 477                                       unsigned int stride);
 478
 479 /* Compare two branch trace call iterators.
 480    Return a negative number if LHS < RHS.
 481    Return zero if LHS == RHS.
 482    Return a positive number if LHS > RHS.  */
 483 extern int btrace_call_cmp (const struct btrace_call_iterator *lhs,
 484                             const struct btrace_call_iterator *rhs);
 485
 486 /* Find a function in the function branch trace by its NUMBER.
 487    If the function is found, initialize the branch trace call
 488    iterator to point to this function and return non-zero.
 489    Return zero otherwise.  */
 490 extern int btrace_find_call_by_number (struct btrace_call_iterator *,
 491                                        const struct btrace_thread_info *,
 492                                        unsigned int number);
 493
 494 /* Set the branch trace instruction history from BEGIN (inclusive) to
 495    END (exclusive).  */
 496 extern void btrace_set_insn_history (struct btrace_thread_info *,
 497                                      const struct btrace_insn_iterator *begin,
 498                                      const struct btrace_insn_iterator *end);
 499
 500 /* Set the branch trace function call history from BEGIN (inclusive) to
 501    END (exclusive).  */
 502 extern void btrace_set_call_history (struct btrace_thread_info *,
 503                                      const struct btrace_call_iterator *begin,
 504                                      const struct btrace_call_iterator *end);
 505
 506 /* Determine if branch tracing is currently replaying TP.  */
 507 extern int btrace_is_replaying (struct thread_info *tp);
 508
 509 /* Return non-zero if the branch trace for TP is empty; zero otherwise.  */
 510 extern int btrace_is_empty (struct thread_info *tp);
 511
 512 /* Create a cleanup for DATA.  */
 513 extern struct cleanup *make_cleanup_btrace_data (struct btrace_data *data);
 514
 515 #endif /* BTRACE_H */