gdb/btrace.h

   1 /* Branch trace support for GDB, the GNU debugger.
   2
   3    Copyright (C) 2013-2024 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 "gdbsupport/btrace-common.h"
  30 #include "target/waitstatus.h"
  31 #include "gdbsupport/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 /* Flags for btrace function segments.  */
  85 enum btrace_function_flag
  86 {
  87   /* The 'up' link interpretation.
  88      If set, it points to the function segment we returned to.
  89      If clear, it points to the function segment we called from.  */
  90   BFUN_UP_LINKS_TO_RET = (1 << 0),
  91
  92   /* The 'up' link points to a tail call.  This obviously only makes sense
  93      if bfun_up_links_to_ret is clear.  */
  94   BFUN_UP_LINKS_TO_TAILCALL = (1 << 1)
  95 };
  96 DEF_ENUM_FLAGS_TYPE (enum btrace_function_flag, btrace_function_flags);
  97
  98 /* Decode errors for the BTS recording format.  */
  99 enum btrace_bts_error
 100 {
 101   /* The instruction trace overflowed the end of the trace block.  */
 102   BDE_BTS_OVERFLOW = 1,
 103
 104   /* The instruction size could not be determined.  */
 105   BDE_BTS_INSN_SIZE
 106 };
 107
 108 /* Decode errors for the Intel Processor Trace recording format.  */
 109 enum btrace_pt_error
 110 {
 111   /* The user cancelled trace processing.  */
 112   BDE_PT_USER_QUIT = 1,
 113
 114   /* Tracing was temporarily disabled.  */
 115   BDE_PT_DISABLED,
 116
 117   /* Trace recording overflowed.  */
 118   BDE_PT_OVERFLOW
 119
 120   /* Negative numbers are used by the decoder library.  */
 121 };
 122
 123 /* A branch trace function segment.
 124
 125    This represents a function segment in a branch trace, i.e. a consecutive
 126    number of instructions belonging to the same function.
 127
 128    In case of decode errors, we add an empty function segment to indicate
 129    the gap in the trace.
 130
 131    We do not allow function segments without instructions otherwise.  */
 132 struct btrace_function
 133 {
 134   btrace_function (struct minimal_symbol *msym_, struct symbol *sym_,
 135                    unsigned int number_, unsigned int insn_offset_, int level_)
 136     : msym (msym_), sym (sym_), insn_offset (insn_offset_), number (number_),
 137       level (level_)
 138   {
 139   }
 140
 141   /* The full and minimal symbol for the function.  Both may be NULL.  */
 142   struct minimal_symbol *msym;
 143   struct symbol *sym;
 144
 145   /* The function segment numbers of the previous and next segment belonging to
 146      the same function.  If a function calls another function, the former will
 147      have at least two segments: one before the call and another after the
 148      return.  Will be zero if there is no such function segment.  */
 149   unsigned int prev = 0;
 150   unsigned int next = 0;
 151
 152   /* The function segment number of the directly preceding function segment in
 153      a (fake) call stack.  Will be zero if there is no such function segment in
 154      the record.  */
 155   unsigned int up = 0;
 156
 157   /* The instructions in this function segment.
 158      The instruction vector will be empty if the function segment
 159      represents a decode error.  */
 160   std::vector<btrace_insn> insn;
 161
 162   /* The error code of a decode error that led to a gap.
 163      Must be zero unless INSN is empty; non-zero otherwise.  */
 164   int errcode = 0;
 165
 166   /* The instruction number offset for the first instruction in this
 167      function segment.
 168      If INSN is empty this is the insn_offset of the succeding function
 169      segment in control-flow order.  */
 170   unsigned int insn_offset;
 171
 172   /* The 1-based function number in control-flow order.
 173      If INSN is empty indicating a gap in the trace due to a decode error,
 174      we still count the gap as a function.  */
 175   unsigned int number;
 176
 177   /* The function level in a back trace across the entire branch trace.
 178      A caller's level is one lower than the level of its callee.
 179
 180      Levels can be negative if we see returns for which we have not seen
 181      the corresponding calls.  The branch trace thread information provides
 182      a fixup to normalize function levels so the smallest level is zero.  */
 183   int level;
 184
 185   /* A bit-vector of btrace_function_flag.  */
 186   btrace_function_flags flags = 0;
 187 };
 188
 189 /* A branch trace instruction iterator.  */
 190 struct btrace_insn_iterator
 191 {
 192   /* The branch trace information for this thread.  Will never be NULL.  */
 193   const struct btrace_thread_info *btinfo;
 194
 195   /* The index of the function segment in BTINFO->FUNCTIONS.  */
 196   unsigned int call_index;
 197
 198   /* The index into the function segment's instruction vector.  */
 199   unsigned int insn_index;
 200 };
 201
 202 /* A branch trace function call iterator.  */
 203 struct btrace_call_iterator
 204 {
 205   /* The branch trace information for this thread.  Will never be NULL.  */
 206   const struct btrace_thread_info *btinfo;
 207
 208   /* The index of the function segment in BTINFO->FUNCTIONS.  */
 209   unsigned int index;
 210 };
 211
 212 /* Branch trace iteration state for "record instruction-history".  */
 213 struct btrace_insn_history
 214 {
 215   /* The branch trace instruction range from BEGIN (inclusive) to
 216      END (exclusive) that has been covered last time.  */
 217   struct btrace_insn_iterator begin;
 218   struct btrace_insn_iterator end;
 219 };
 220
 221 /* Branch trace iteration state for "record function-call-history".  */
 222 struct btrace_call_history
 223 {
 224   /* The branch trace function range from BEGIN (inclusive) to END (exclusive)
 225      that has been covered last time.  */
 226   struct btrace_call_iterator begin;
 227   struct btrace_call_iterator end;
 228 };
 229
 230 /* Branch trace thread flags.  */
 231 enum btrace_thread_flag : unsigned
 232 {
 233   /* The thread is to be stepped forwards.  */
 234   BTHR_STEP = (1 << 0),
 235
 236   /* The thread is to be stepped backwards.  */
 237   BTHR_RSTEP = (1 << 1),
 238
 239   /* The thread is to be continued forwards.  */
 240   BTHR_CONT = (1 << 2),
 241
 242   /* The thread is to be continued backwards.  */
 243   BTHR_RCONT = (1 << 3),
 244
 245   /* The thread is to be moved.  */
 246   BTHR_MOVE = (BTHR_STEP | BTHR_RSTEP | BTHR_CONT | BTHR_RCONT),
 247
 248   /* The thread is to be stopped.  */
 249   BTHR_STOP = (1 << 4)
 250 };
 251 DEF_ENUM_FLAGS_TYPE (enum btrace_thread_flag, btrace_thread_flags);
 252
 253 #if defined (HAVE_LIBIPT)
 254 /* A packet.  */
 255 struct btrace_pt_packet
 256 {
 257   /* The offset in the trace stream.  */
 258   uint64_t offset;
 259
 260   /* The decode error code.  */
 261   enum pt_error_code errcode;
 262
 263   /* The decoded packet.  Only valid if ERRCODE == pte_ok.  */
 264   struct pt_packet packet;
 265 };
 266
 267 #endif /* defined (HAVE_LIBIPT)  */
 268
 269 /* Branch trace iteration state for "maintenance btrace packet-history".  */
 270 struct btrace_maint_packet_history
 271 {
 272   /* The branch trace packet range from BEGIN (inclusive) to
 273      END (exclusive) that has been covered last time.  */
 274   unsigned int begin;
 275   unsigned int end;
 276 };
 277
 278 /* Branch trace maintenance information per thread.
 279
 280    This information is used by "maintenance btrace" commands.  */
 281 struct btrace_maint_info
 282 {
 283   /* Most information is format-specific.
 284      The format can be found in the BTRACE.DATA.FORMAT field of each thread.  */
 285   union
 286   {
 287     /* BTRACE.DATA.FORMAT == BTRACE_FORMAT_BTS  */
 288     struct
 289     {
 290       /* The packet history iterator.
 291          We are iterating over BTRACE.DATA.FORMAT.VARIANT.BTS.BLOCKS.  */
 292       struct btrace_maint_packet_history packet_history;
 293     } bts;
 294
 295 #if defined (HAVE_LIBIPT)
 296     /* BTRACE.DATA.FORMAT == BTRACE_FORMAT_PT  */
 297     struct
 298     {
 299       /* A vector of decoded packets.  */
 300       std::vector<btrace_pt_packet> *packets;
 301
 302       /* The packet history iterator.
 303          We are iterating over the above PACKETS vector.  */
 304       struct btrace_maint_packet_history packet_history;
 305     } pt;
 306 #endif /* defined (HAVE_LIBIPT)  */
 307   } variant;
 308 };
 309
 310 /* Branch trace information per thread.
 311
 312    This represents the branch trace configuration as well as the entry point
 313    into the branch trace data.  For the latter, it also contains the index into
 314    an array of branch trace blocks used for iterating though the branch trace
 315    blocks of a thread.  */
 316 struct btrace_thread_info
 317 {
 318   /* The target branch trace information for this thread.
 319
 320      This contains the branch trace configuration as well as any
 321      target-specific information necessary for implementing branch tracing on
 322      the underlying architecture.  */
 323   struct btrace_target_info *target;
 324
 325   /* The raw branch trace data for the below branch trace.  */
 326   struct btrace_data data;
 327
 328   /* Vector of decoded function segments in execution flow order.
 329      Note that the numbering for btrace function segments starts with 1, so
 330      function segment i will be at index (i - 1).  */
 331   std::vector<btrace_function> functions;
 332
 333   /* The function level offset.  When added to each function's LEVEL,
 334      this normalizes the function levels such that the smallest level
 335      becomes zero.  */
 336   int level;
 337
 338   /* The number of gaps in the trace.  */
 339   unsigned int ngaps;
 340
 341   /* A bit-vector of btrace_thread_flag.  */
 342   btrace_thread_flags flags;
 343
 344   /* The instruction history iterator.  */
 345   struct btrace_insn_history *insn_history;
 346
 347   /* The function call history iterator.  */
 348   struct btrace_call_history *call_history;
 349
 350   /* The current replay position.  NULL if not replaying.
 351      Gaps are skipped during replay, so REPLAY always points to a valid
 352      instruction.  */
 353   struct btrace_insn_iterator *replay;
 354
 355   /* Why the thread stopped, if we need to track it.  */
 356   enum target_stop_reason stop_reason;
 357
 358   /* Maintenance information.  */
 359   struct btrace_maint_info maint;
 360 };
 361
 362 /* Enable branch tracing for a thread.  */
 363 extern void btrace_enable (struct thread_info *tp,
 364                            const struct btrace_config *conf);
 365
 366 /* Get the branch trace configuration for a thread.
 367    Return NULL if branch tracing is not enabled for that thread.  */
 368 extern const struct btrace_config *
 369   btrace_conf (const struct btrace_thread_info *);
 370
 371 /* Disable branch tracing for a thread.
 372    This will also delete the current branch trace data.  */
 373 extern void btrace_disable (struct thread_info *);
 374
 375 /* Disable branch tracing for a thread during teardown.
 376    This is similar to btrace_disable, except that it will use
 377    target_teardown_btrace instead of target_disable_btrace.  */
 378 extern void btrace_teardown (struct thread_info *);
 379
 380 /* Return a human readable error string for the given ERRCODE in FORMAT.
 381    The pointer will never be NULL and must not be freed.  */
 382
 383 extern const char *btrace_decode_error (enum btrace_format format, int errcode);
 384
 385 /* Fetch the branch trace for a single thread.  If CPU is not NULL, assume
 386    CPU for trace decode.  */
 387 extern void btrace_fetch (struct thread_info *,
 388                           const struct btrace_cpu *cpu);
 389
 390 /* Clear the branch trace for a single thread.  */
 391 extern void btrace_clear (struct thread_info *);
 392
 393 /* Clear the branch trace for all threads when an object file goes away.  */
 394 extern void btrace_free_objfile (struct objfile *);
 395
 396 /* Dereference a branch trace instruction iterator.  Return a pointer to the
 397    instruction the iterator points to.
 398    May return NULL if the iterator points to a gap in the trace.  */
 399 extern const struct btrace_insn *
 400   btrace_insn_get (const struct btrace_insn_iterator *);
 401
 402 /* Return the error code for a branch trace instruction iterator.  Returns zero
 403    if there is no error, i.e. the instruction is valid.  */
 404 extern int btrace_insn_get_error (const struct btrace_insn_iterator *);
 405
 406 /* Return the instruction number for a branch trace iterator.
 407    Returns one past the maximum instruction number for the end iterator.  */
 408 extern unsigned int btrace_insn_number (const struct btrace_insn_iterator *);
 409
 410 /* Initialize a branch trace instruction iterator to point to the begin/end of
 411    the branch trace.  Throws an error if there is no branch trace.  */
 412 extern void btrace_insn_begin (struct btrace_insn_iterator *,
 413                                const struct btrace_thread_info *);
 414 extern void btrace_insn_end (struct btrace_insn_iterator *,
 415                              const struct btrace_thread_info *);
 416
 417 /* Increment/decrement a branch trace instruction iterator by at most STRIDE
 418    instructions.  Return the number of instructions by which the instruction
 419    iterator has been advanced.
 420    Returns zero, if the operation failed or STRIDE had been zero.  */
 421 extern unsigned int btrace_insn_next (struct btrace_insn_iterator *,
 422                                       unsigned int stride);
 423 extern unsigned int btrace_insn_prev (struct btrace_insn_iterator *,
 424                                       unsigned int stride);
 425
 426 /* Compare two branch trace instruction iterators.
 427    Return a negative number if LHS < RHS.
 428    Return zero if LHS == RHS.
 429    Return a positive number if LHS > RHS.  */
 430 extern int btrace_insn_cmp (const struct btrace_insn_iterator *lhs,
 431                             const struct btrace_insn_iterator *rhs);
 432
 433 /* Find an instruction or gap in the function branch trace by its number.
 434    If the instruction is found, initialize the branch trace instruction
 435    iterator to point to this instruction and return non-zero.
 436    Return zero otherwise.  */
 437 extern int btrace_find_insn_by_number (struct btrace_insn_iterator *,
 438                                        const struct btrace_thread_info *,
 439                                        unsigned int number);
 440
 441 /* Dereference a branch trace call iterator.  Return a pointer to the
 442    function the iterator points to or NULL if the iterator points past
 443    the end of the branch trace.  */
 444 extern const struct btrace_function *
 445   btrace_call_get (const struct btrace_call_iterator *);
 446
 447 /* Return the function number for a branch trace call iterator.
 448    Returns one past the maximum function number for the end iterator.
 449    Returns zero if the iterator does not point to a valid function.  */
 450 extern unsigned int btrace_call_number (const struct btrace_call_iterator *);
 451
 452 /* Initialize a branch trace call iterator to point to the begin/end of
 453    the branch trace.  Throws an error if there is no branch trace.  */
 454 extern void btrace_call_begin (struct btrace_call_iterator *,
 455                                const struct btrace_thread_info *);
 456 extern void btrace_call_end (struct btrace_call_iterator *,
 457                              const struct btrace_thread_info *);
 458
 459 /* Increment/decrement a branch trace call iterator by at most STRIDE function
 460    segments.  Return the number of function segments by which the call
 461    iterator has been advanced.
 462    Returns zero, if the operation failed or STRIDE had been zero.  */
 463 extern unsigned int btrace_call_next (struct btrace_call_iterator *,
 464                                       unsigned int stride);
 465 extern unsigned int btrace_call_prev (struct btrace_call_iterator *,
 466                                       unsigned int stride);
 467
 468 /* Compare two branch trace call iterators.
 469    Return a negative number if LHS < RHS.
 470    Return zero if LHS == RHS.
 471    Return a positive number if LHS > RHS.  */
 472 extern int btrace_call_cmp (const struct btrace_call_iterator *lhs,
 473                             const struct btrace_call_iterator *rhs);
 474
 475 /* Find a function in the function branch trace by its NUMBER.
 476    If the function is found, initialize the branch trace call
 477    iterator to point to this function and return non-zero.
 478    Return zero otherwise.  */
 479 extern int btrace_find_call_by_number (struct btrace_call_iterator *,
 480                                        const struct btrace_thread_info *,
 481                                        unsigned int number);
 482
 483 /* Set the branch trace instruction history from BEGIN (inclusive) to
 484    END (exclusive).  */
 485 extern void btrace_set_insn_history (struct btrace_thread_info *,
 486                                      const struct btrace_insn_iterator *begin,
 487                                      const struct btrace_insn_iterator *end);
 488
 489 /* Set the branch trace function call history from BEGIN (inclusive) to
 490    END (exclusive).  */
 491 extern void btrace_set_call_history (struct btrace_thread_info *,
 492                                      const struct btrace_call_iterator *begin,
 493                                      const struct btrace_call_iterator *end);
 494
 495 /* Determine if branch tracing is currently replaying TP.  */
 496 extern int btrace_is_replaying (struct thread_info *tp);
 497
 498 /* Return non-zero if the branch trace for TP is empty; zero otherwise.  */
 499 extern int btrace_is_empty (struct thread_info *tp);
 500
 501 #endif /* BTRACE_H */