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 /* A doubly-linked list of branch trace function segments.  */
  89 struct btrace_func_link
  90 {
  91   struct btrace_function *prev;
  92   struct btrace_function *next;
  93 };
  94
  95 /* Flags for btrace function segments.  */
  96 enum btrace_function_flag
  97 {
  98   /* The 'up' link interpretation.
  99      If set, it points to the function segment we returned to.
 100      If clear, it points to the function segment we called from.  */
 101   BFUN_UP_LINKS_TO_RET = (1 << 0),
 102
 103   /* The 'up' link points to a tail call.  This obviously only makes sense
 104      if bfun_up_links_to_ret is clear.  */
 105   BFUN_UP_LINKS_TO_TAILCALL = (1 << 1)
 106 };
 107 DEF_ENUM_FLAGS_TYPE (enum btrace_function_flag, btrace_function_flags);
 108
 109 /* Decode errors for the BTS recording format.  */
 110 enum btrace_bts_error
 111 {
 112   /* The instruction trace overflowed the end of the trace block.  */
 113   BDE_BTS_OVERFLOW = 1,
 114
 115   /* The instruction size could not be determined.  */
 116   BDE_BTS_INSN_SIZE
 117 };
 118
 119 /* Decode errors for the Intel Processor Trace recording format.  */
 120 enum btrace_pt_error
 121 {
 122   /* The user cancelled trace processing.  */
 123   BDE_PT_USER_QUIT = 1,
 124
 125   /* Tracing was temporarily disabled.  */
 126   BDE_PT_DISABLED,
 127
 128   /* Trace recording overflowed.  */
 129   BDE_PT_OVERFLOW
 130
 131   /* Negative numbers are used by the decoder library.  */
 132 };
 133
 134 /* A branch trace function segment.
 135
 136    This represents a function segment in a branch trace, i.e. a consecutive
 137    number of instructions belonging to the same function.
 138
 139    In case of decode errors, we add an empty function segment to indicate
 140    the gap in the trace.
 141
 142    We do not allow function segments without instructions otherwise.  */
 143 struct btrace_function
 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 previous and next segment belonging to the same function.
 150      If a function calls another function, the former will have at least
 151      two segments: one before the call and another after the return.  */
 152   struct btrace_func_link segment;
 153
 154   /* The previous and next function in control flow order.  */
 155   struct btrace_func_link flow;
 156
 157   /* The directly preceding function segment in a (fake) call stack.  */
 158   struct btrace_function *up;
 159
 160   /* The instructions in this function segment.
 161      The instruction vector will be empty if the function segment
 162      represents a decode error.  */
 163   VEC (btrace_insn_s) *insn;
 164
 165   /* The error code of a decode error that led to a gap.
 166      Must be zero unless INSN is empty; non-zero otherwise.  */
 167   int errcode;
 168
 169   /* The instruction number offset for the first instruction in this
 170      function segment.
 171      If INSN is empty this is the insn_offset of the succeding function
 172      segment in control-flow order.  */
 173   unsigned int insn_offset;
 174
 175   /* The 1-based function number in control-flow order.
 176      If INSN is empty indicating a gap in the trace due to a decode error,
 177      we still count the gap as a function.  */
 178   unsigned int number;
 179
 180   /* The function level in a back trace across the entire branch trace.
 181      A caller's level is one lower than the level of its callee.
 182
 183      Levels can be negative if we see returns for which we have not seen
 184      the corresponding calls.  The branch trace thread information provides
 185      a fixup to normalize function levels so the smallest level is zero.  */
 186   int level;
 187
 188   /* A bit-vector of btrace_function_flag.  */
 189   btrace_function_flags flags;
 190 };
 191
 192 /* A branch trace instruction iterator.  */
 193 struct btrace_insn_iterator
 194 {
 195   /* The branch trace information for this thread.  Will never be NULL.  */
 196   const struct btrace_thread_info *btinfo;
 197
 198   /* The branch trace function segment containing the instruction.
 199      Will never be NULL.  */
 200   const struct btrace_function *function;
 201
 202   /* The index into the function segment's instruction vector.  */
 203   unsigned int 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   /* The current branch trace for this thread (both inclusive).
 336
 337      The last instruction of END is the current instruction, which is not
 338      part of the execution history.
 339      Both will be NULL if there is no branch trace available.  If there is
 340      branch trace available, both will be non-NULL.  */
 341   struct btrace_function *begin;
 342   struct btrace_function *end;
 343
 344   /* Vector of pointer to decoded function segments.  These are in execution
 345      order with the first element == BEGIN and the last element == END.  */
 346   std::vector<btrace_function *> functions;
 347
 348   /* The function level offset.  When added to each function's LEVEL,
 349      this normalizes the function levels such that the smallest level
 350      becomes zero.  */
 351   int level;
 352
 353   /* The number of gaps in the trace.  */
 354   unsigned int ngaps;
 355
 356   /* A bit-vector of btrace_thread_flag.  */
 357   btrace_thread_flags flags;
 358
 359   /* The instruction history iterator.  */
 360   struct btrace_insn_history *insn_history;
 361
 362   /* The function call history iterator.  */
 363   struct btrace_call_history *call_history;
 364
 365   /* The current replay position.  NULL if not replaying.
 366      Gaps are skipped during replay, so REPLAY always points to a valid
 367      instruction.  */
 368   struct btrace_insn_iterator *replay;
 369
 370   /* Why the thread stopped, if we need to track it.  */
 371   enum target_stop_reason stop_reason;
 372
 373   /* Maintenance information.  */
 374   struct btrace_maint_info maint;
 375 };
 376
 377 /* Enable branch tracing for a thread.  */
 378 extern void btrace_enable (struct thread_info *tp,
 379                            const struct btrace_config *conf);
 380
 381 /* Get the branch trace configuration for a thread.
 382    Return NULL if branch tracing is not enabled for that thread.  */
 383 extern const struct btrace_config *
 384   btrace_conf (const struct btrace_thread_info *);
 385
 386 /* Disable branch tracing for a thread.
 387    This will also delete the current branch trace data.  */
 388 extern void btrace_disable (struct thread_info *);
 389
 390 /* Disable branch tracing for a thread during teardown.
 391    This is similar to btrace_disable, except that it will use
 392    target_teardown_btrace instead of target_disable_btrace.  */
 393 extern void btrace_teardown (struct thread_info *);
 394
 395 /* Return a human readable error string for the given ERRCODE in FORMAT.
 396    The pointer will never be NULL and must not be freed.  */
 397
 398 extern const char *btrace_decode_error (enum btrace_format format, int errcode);
 399
 400 /* Fetch the branch trace for a single thread.  */
 401 extern void btrace_fetch (struct thread_info *);
 402
 403 /* Clear the branch trace for a single thread.  */
 404 extern void btrace_clear (struct thread_info *);
 405
 406 /* Clear the branch trace for all threads when an object file goes away.  */
 407 extern void btrace_free_objfile (struct objfile *);
 408
 409 /* Parse a branch trace xml document XML into DATA.  */
 410 extern void parse_xml_btrace (struct btrace_data *data, const char *xml);
 411
 412 /* Parse a branch trace configuration xml document XML into CONF.  */
 413 extern void parse_xml_btrace_conf (struct btrace_config *conf, const char *xml);
 414
 415 /* Dereference a branch trace instruction iterator.  Return a pointer to the
 416    instruction the iterator points to.
 417    May return NULL if the iterator points to a gap in the trace.  */
 418 extern const struct btrace_insn *
 419   btrace_insn_get (const struct btrace_insn_iterator *);
 420
 421 /* Return the error code for a branch trace instruction iterator.  Returns zero
 422    if there is no error, i.e. the instruction is valid.  */
 423 extern int btrace_insn_get_error (const struct btrace_insn_iterator *);
 424
 425 /* Return the instruction number for a branch trace iterator.
 426    Returns one past the maximum instruction number for the end iterator.  */
 427 extern unsigned int btrace_insn_number (const struct btrace_insn_iterator *);
 428
 429 /* Initialize a branch trace instruction iterator to point to the begin/end of
 430    the branch trace.  Throws an error if there is no branch trace.  */
 431 extern void btrace_insn_begin (struct btrace_insn_iterator *,
 432                                const struct btrace_thread_info *);
 433 extern void btrace_insn_end (struct btrace_insn_iterator *,
 434                              const struct btrace_thread_info *);
 435
 436 /* Increment/decrement a branch trace instruction iterator by at most STRIDE
 437    instructions.  Return the number of instructions by which the instruction
 438    iterator has been advanced.
 439    Returns zero, if the operation failed or STRIDE had been zero.  */
 440 extern unsigned int btrace_insn_next (struct btrace_insn_iterator *,
 441                                       unsigned int stride);
 442 extern unsigned int btrace_insn_prev (struct btrace_insn_iterator *,
 443                                       unsigned int stride);
 444
 445 /* Compare two branch trace instruction iterators.
 446    Return a negative number if LHS < RHS.
 447    Return zero if LHS == RHS.
 448    Return a positive number if LHS > RHS.  */
 449 extern int btrace_insn_cmp (const struct btrace_insn_iterator *lhs,
 450                             const struct btrace_insn_iterator *rhs);
 451
 452 /* Find an instruction or gap in the function branch trace by its number.
 453    If the instruction is found, initialize the branch trace instruction
 454    iterator to point to this instruction and return non-zero.
 455    Return zero otherwise.  */
 456 extern int btrace_find_insn_by_number (struct btrace_insn_iterator *,
 457                                        const struct btrace_thread_info *,
 458                                        unsigned int number);
 459
 460 /* Dereference a branch trace call iterator.  Return a pointer to the
 461    function the iterator points to or NULL if the interator points past
 462    the end of the branch trace.  */
 463 extern const struct btrace_function *
 464   btrace_call_get (const struct btrace_call_iterator *);
 465
 466 /* Return the function number for a branch trace call iterator.
 467    Returns one past the maximum function number for the end iterator.
 468    Returns zero if the iterator does not point to a valid function.  */
 469 extern unsigned int btrace_call_number (const struct btrace_call_iterator *);
 470
 471 /* Initialize a branch trace call iterator to point to the begin/end of
 472    the branch trace.  Throws an error if there is no branch trace.  */
 473 extern void btrace_call_begin (struct btrace_call_iterator *,
 474                                const struct btrace_thread_info *);
 475 extern void btrace_call_end (struct btrace_call_iterator *,
 476                              const struct btrace_thread_info *);
 477
 478 /* Increment/decrement a branch trace call iterator by at most STRIDE function
 479    segments.  Return the number of function segments by which the call
 480    iterator has been advanced.
 481    Returns zero, if the operation failed or STRIDE had been zero.  */
 482 extern unsigned int btrace_call_next (struct btrace_call_iterator *,
 483                                       unsigned int stride);
 484 extern unsigned int btrace_call_prev (struct btrace_call_iterator *,
 485                                       unsigned int stride);
 486
 487 /* Compare two branch trace call iterators.
 488    Return a negative number if LHS < RHS.
 489    Return zero if LHS == RHS.
 490    Return a positive number if LHS > RHS.  */
 491 extern int btrace_call_cmp (const struct btrace_call_iterator *lhs,
 492                             const struct btrace_call_iterator *rhs);
 493
 494 /* Find a function in the function branch trace by its NUMBER.
 495    If the function is found, initialize the branch trace call
 496    iterator to point to this function and return non-zero.
 497    Return zero otherwise.  */
 498 extern int btrace_find_call_by_number (struct btrace_call_iterator *,
 499                                        const struct btrace_thread_info *,
 500                                        unsigned int number);
 501
 502 /* Set the branch trace instruction history from BEGIN (inclusive) to
 503    END (exclusive).  */
 504 extern void btrace_set_insn_history (struct btrace_thread_info *,
 505                                      const struct btrace_insn_iterator *begin,
 506                                      const struct btrace_insn_iterator *end);
 507
 508 /* Set the branch trace function call history from BEGIN (inclusive) to
 509    END (exclusive).  */
 510 extern void btrace_set_call_history (struct btrace_thread_info *,
 511                                      const struct btrace_call_iterator *begin,
 512                                      const struct btrace_call_iterator *end);
 513
 514 /* Determine if branch tracing is currently replaying TP.  */
 515 extern int btrace_is_replaying (struct thread_info *tp);
 516
 517 /* Return non-zero if the branch trace for TP is empty; zero otherwise.  */
 518 extern int btrace_is_empty (struct thread_info *tp);
 519
 520 /* Create a cleanup for DATA.  */
 521 extern struct cleanup *make_cleanup_btrace_data (struct btrace_data *data);
 522
 523 #endif /* BTRACE_H */