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 struct thread_info;
  38 struct btrace_function;
  39
  40 /* A coarse instruction classification.  */
  41 enum btrace_insn_class
  42 {
  43   /* The instruction is something not listed below.  */
  44   BTRACE_INSN_OTHER,
  45
  46   /* The instruction is a function call.  */
  47   BTRACE_INSN_CALL,
  48
  49   /* The instruction is a function return.  */
  50   BTRACE_INSN_RETURN,
  51
  52   /* The instruction is an unconditional jump.  */
  53   BTRACE_INSN_JUMP
  54 };
  55
  56 /* Instruction flags.  */
  57 enum btrace_insn_flag
  58 {
  59   /* The instruction has been executed speculatively.  */
  60   BTRACE_INSN_FLAG_SPECULATIVE = (1 << 0)
  61 };
  62 DEF_ENUM_FLAGS_TYPE (enum btrace_insn_flag, btrace_insn_flags);
  63
  64 /* A branch trace instruction.
  65
  66    This represents a single instruction in a branch trace.  */
  67 struct btrace_insn
  68 {
  69   /* The address of this instruction.  */
  70   CORE_ADDR pc;
  71
  72   /* The size of this instruction in bytes.  */
  73   gdb_byte size;
  74
  75   /* The instruction class of this instruction.  */
  76   enum btrace_insn_class iclass;
  77
  78   /* A bit vector of BTRACE_INSN_FLAGS.  */
  79   btrace_insn_flags flags;
  80 };
  81
  82 /* A vector of branch trace instructions.  */
  83 typedef struct btrace_insn btrace_insn_s;
  84 DEF_VEC_O (btrace_insn_s);
  85
  86 /* A doubly-linked list of branch trace function segments.  */
  87 struct btrace_func_link
  88 {
  89   struct btrace_function *prev;
  90   struct btrace_function *next;
  91 };
  92
  93 /* Flags for btrace function segments.  */
  94 enum btrace_function_flag
  95 {
  96   /* The 'up' link interpretation.
  97      If set, it points to the function segment we returned to.
  98      If clear, it points to the function segment we called from.  */
  99   BFUN_UP_LINKS_TO_RET = (1 << 0),
 100
 101   /* The 'up' link points to a tail call.  This obviously only makes sense
 102      if bfun_up_links_to_ret is clear.  */
 103   BFUN_UP_LINKS_TO_TAILCALL = (1 << 1)
 104 };
 105 DEF_ENUM_FLAGS_TYPE (enum btrace_function_flag, btrace_function_flags);
 106
 107 /* Decode errors for the BTS recording format.  */
 108 enum btrace_bts_error
 109 {
 110   /* The instruction trace overflowed the end of the trace block.  */
 111   BDE_BTS_OVERFLOW = 1,
 112
 113   /* The instruction size could not be determined.  */
 114   BDE_BTS_INSN_SIZE
 115 };
 116
 117 /* Decode errors for the Intel Processor Trace recording format.  */
 118 enum btrace_pt_error
 119 {
 120   /* The user cancelled trace processing.  */
 121   BDE_PT_USER_QUIT = 1,
 122
 123   /* Tracing was temporarily disabled.  */
 124   BDE_PT_DISABLED,
 125
 126   /* Trace recording overflowed.  */
 127   BDE_PT_OVERFLOW
 128
 129   /* Negative numbers are used by the decoder library.  */
 130 };
 131
 132 /* A branch trace function segment.
 133
 134    This represents a function segment in a branch trace, i.e. a consecutive
 135    number of instructions belonging to the same function.
 136
 137    In case of decode errors, we add an empty function segment to indicate
 138    the gap in the trace.
 139
 140    We do not allow function segments without instructions otherwise.  */
 141 struct btrace_function
 142 {
 143   /* The full and minimal symbol for the function.  Both may be NULL.  */
 144   struct minimal_symbol *msym;
 145   struct symbol *sym;
 146
 147   /* The previous and next segment belonging to the same function.
 148      If a function calls another function, the former will have at least
 149      two segments: one before the call and another after the return.  */
 150   struct btrace_func_link segment;
 151
 152   /* The previous and next function in control flow order.  */
 153   struct btrace_func_link flow;
 154
 155   /* The directly preceding function segment in a (fake) call stack.  */
 156   struct btrace_function *up;
 157
 158   /* The instructions in this function segment.
 159      The instruction vector will be empty if the function segment
 160      represents a decode error.  */
 161   VEC (btrace_insn_s) *insn;
 162
 163   /* The error code of a decode error that led to a gap.
 164      Must be zero unless INSN is empty; non-zero otherwise.  */
 165   int errcode;
 166
 167   /* The instruction number offset for the first instruction in this
 168      function segment.
 169      If INSN is empty this is the insn_offset of the succeding function
 170      segment in control-flow order.  */
 171   unsigned int insn_offset;
 172
 173   /* The function number in control-flow order.
 174      If INSN is empty indicating a gap in the trace due to a decode error,
 175      we still count the gap as a function.  */
 176   unsigned int number;
 177
 178   /* The function level in a back trace across the entire branch trace.
 179      A caller's level is one lower than the level of its callee.
 180
 181      Levels can be negative if we see returns for which we have not seen
 182      the corresponding calls.  The branch trace thread information provides
 183      a fixup to normalize function levels so the smallest level is zero.  */
 184   int level;
 185
 186   /* A bit-vector of btrace_function_flag.  */
 187   btrace_function_flags flags;
 188 };
 189
 190 typedef struct btrace_function *btrace_fun_p;
 191 DEF_VEC_P (btrace_fun_p);
 192
 193 /* A branch trace instruction iterator.  */
 194 struct btrace_insn_iterator
 195 {
 196   /* The branch trace function segment containing the instruction.
 197      Will never be NULL.  */
 198   const struct btrace_function *function;
 199
 200   /* The index into the function segment's instruction vector.  */
 201   unsigned int index;
 202 };
 203
 204 /* A branch trace function call iterator.  */
 205 struct btrace_call_iterator
 206 {
 207   /* The branch trace information for this thread.  Will never be NULL.  */
 208   const struct btrace_thread_info *btinfo;
 209
 210   /* The branch trace function segment.
 211      This will be NULL for the iterator pointing to the end of the trace.  */
 212   const struct btrace_function *function;
 213 };
 214
 215 /* Branch trace iteration state for "record instruction-history".  */
 216 struct btrace_insn_history
 217 {
 218   /* The branch trace instruction range from BEGIN (inclusive) to
 219      END (exclusive) that has been covered last time.  */
 220   struct btrace_insn_iterator begin;
 221   struct btrace_insn_iterator end;
 222 };
 223
 224 /* Branch trace iteration state for "record function-call-history".  */
 225 struct btrace_call_history
 226 {
 227   /* The branch trace function range from BEGIN (inclusive) to END (exclusive)
 228      that has been covered last time.  */
 229   struct btrace_call_iterator begin;
 230   struct btrace_call_iterator end;
 231 };
 232
 233 /* Branch trace thread flags.  */
 234 enum btrace_thread_flag
 235 {
 236   /* The thread is to be stepped forwards.  */
 237   BTHR_STEP = (1 << 0),
 238
 239   /* The thread is to be stepped backwards.  */
 240   BTHR_RSTEP = (1 << 1),
 241
 242   /* The thread is to be continued forwards.  */
 243   BTHR_CONT = (1 << 2),
 244
 245   /* The thread is to be continued backwards.  */
 246   BTHR_RCONT = (1 << 3),
 247
 248   /* The thread is to be moved.  */
 249   BTHR_MOVE = (BTHR_STEP | BTHR_RSTEP | BTHR_CONT | BTHR_RCONT),
 250
 251   /* The thread is to be stopped.  */
 252   BTHR_STOP = (1 << 4)
 253 };
 254 DEF_ENUM_FLAGS_TYPE (enum btrace_thread_flag, btrace_thread_flags);
 255
 256 #if defined (HAVE_LIBIPT)
 257 /* A packet.  */
 258 struct btrace_pt_packet
 259 {
 260   /* The offset in the trace stream.  */
 261   uint64_t offset;
 262
 263   /* The decode error code.  */
 264   enum pt_error_code errcode;
 265
 266   /* The decoded packet.  Only valid if ERRCODE == pte_ok.  */
 267   struct pt_packet packet;
 268 };
 269
 270 /* Define functions operating on a vector of packets.  */
 271 typedef struct btrace_pt_packet btrace_pt_packet_s;
 272 DEF_VEC_O (btrace_pt_packet_s);
 273 #endif /* defined (HAVE_LIBIPT)  */
 274
 275 /* Branch trace iteration state for "maintenance btrace packet-history".  */
 276 struct btrace_maint_packet_history
 277 {
 278   /* The branch trace packet range from BEGIN (inclusive) to
 279      END (exclusive) that has been covered last time.  */
 280   unsigned int begin;
 281   unsigned int end;
 282 };
 283
 284 /* Branch trace maintenance information per thread.
 285
 286    This information is used by "maintenance btrace" commands.  */
 287 struct btrace_maint_info
 288 {
 289   /* Most information is format-specific.
 290      The format can be found in the BTRACE.DATA.FORMAT field of each thread.  */
 291   union
 292   {
 293     /* BTRACE.DATA.FORMAT == BTRACE_FORMAT_BTS  */
 294     struct
 295     {
 296       /* The packet history iterator.
 297          We are iterating over BTRACE.DATA.FORMAT.VARIANT.BTS.BLOCKS.  */
 298       struct btrace_maint_packet_history packet_history;
 299     } bts;
 300
 301 #if defined (HAVE_LIBIPT)
 302     /* BTRACE.DATA.FORMAT == BTRACE_FORMAT_PT  */
 303     struct
 304     {
 305       /* A vector of decoded packets.  */
 306       VEC (btrace_pt_packet_s) *packets;
 307
 308       /* The packet history iterator.
 309          We are iterating over the above PACKETS vector.  */
 310       struct btrace_maint_packet_history packet_history;
 311     } pt;
 312 #endif /* defined (HAVE_LIBIPT)  */
 313   } variant;
 314 };
 315
 316 /* Branch trace information per thread.
 317
 318    This represents the branch trace configuration as well as the entry point
 319    into the branch trace data.  For the latter, it also contains the index into
 320    an array of branch trace blocks used for iterating though the branch trace
 321    blocks of a thread.  */
 322 struct btrace_thread_info
 323 {
 324   /* The target branch trace information for this thread.
 325
 326      This contains the branch trace configuration as well as any
 327      target-specific information necessary for implementing branch tracing on
 328      the underlying architecture.  */
 329   struct btrace_target_info *target;
 330
 331   /* The raw branch trace data for the below branch trace.  */
 332   struct btrace_data data;
 333
 334   /* The current branch trace for this thread (both inclusive).
 335
 336      The last instruction of END is the current instruction, which is not
 337      part of the execution history.
 338      Both will be NULL if there is no branch trace available.  If there is
 339      branch trace available, both will be non-NULL.  */
 340   struct btrace_function *begin;
 341   struct btrace_function *end;
 342
 343   /* Vector of pointer to decoded function segments.  These are in execution
 344      order with the first element == BEGIN and the last element == END.  */
 345   VEC (btrace_fun_p) *functions;
 346
 347   /* The function level offset.  When added to each function's LEVEL,
 348      this normalizes the function levels such that the smallest level
 349      becomes zero.  */
 350   int level;
 351
 352   /* The number of gaps in the trace.  */
 353   unsigned int ngaps;
 354
 355   /* A bit-vector of btrace_thread_flag.  */
 356   btrace_thread_flags flags;
 357
 358   /* The instruction history iterator.  */
 359   struct btrace_insn_history *insn_history;
 360
 361   /* The function call history iterator.  */
 362   struct btrace_call_history *call_history;
 363
 364   /* The current replay position.  NULL if not replaying.
 365      Gaps are skipped during replay, so REPLAY always points to a valid
 366      instruction.  */
 367   struct btrace_insn_iterator *replay;
 368
 369   /* Why the thread stopped, if we need to track it.  */
 370   enum target_stop_reason stop_reason;
 371
 372   /* Maintenance information.  */
 373   struct btrace_maint_info maint;
 374 };
 375
 376 /* Enable branch tracing for a thread.  */
 377 extern void btrace_enable (struct thread_info *tp,
 378                            const struct btrace_config *conf);
 379
 380 /* Get the branch trace configuration for a thread.
 381    Return NULL if branch tracing is not enabled for that thread.  */
 382 extern const struct btrace_config *
 383   btrace_conf (const struct btrace_thread_info *);
 384
 385 /* Disable branch tracing for a thread.
 386    This will also delete the current branch trace data.  */
 387 extern void btrace_disable (struct thread_info *);
 388
 389 /* Disable branch tracing for a thread during teardown.
 390    This is similar to btrace_disable, except that it will use
 391    target_teardown_btrace instead of target_disable_btrace.  */
 392 extern void btrace_teardown (struct thread_info *);
 393
 394 /* Return a human readable error string for the given ERRCODE in FORMAT.
 395    The pointer will never be NULL and must not be freed.  */
 396
 397 extern const char *btrace_decode_error (enum btrace_format format, int errcode);
 398
 399 /* Fetch the branch trace for a single thread.  */
 400 extern void btrace_fetch (struct thread_info *);
 401
 402 /* Clear the branch trace for a single thread.  */
 403 extern void btrace_clear (struct thread_info *);
 404
 405 /* Clear the branch trace for all threads when an object file goes away.  */
 406 extern void btrace_free_objfile (struct objfile *);
 407
 408 /* Parse a branch trace xml document XML into DATA.  */
 409 extern void parse_xml_btrace (struct btrace_data *data, const char *xml);
 410
 411 /* Parse a branch trace configuration xml document XML into CONF.  */
 412 extern void parse_xml_btrace_conf (struct btrace_config *conf, const char *xml);
 413
 414 /* Dereference a branch trace instruction iterator.  Return a pointer to the
 415    instruction the iterator points to.
 416    May return NULL if the iterator points to a gap in the trace.  */
 417 extern const struct btrace_insn *
 418   btrace_insn_get (const struct btrace_insn_iterator *);
 419
 420 /* Return the error code for a branch trace instruction iterator.  Returns zero
 421    if there is no error, i.e. the instruction is valid.  */
 422 extern int btrace_insn_get_error (const struct btrace_insn_iterator *);
 423
 424 /* Return the instruction number for a branch trace iterator.
 425    Returns one past the maximum instruction number for the end iterator.  */
 426 extern unsigned int btrace_insn_number (const struct btrace_insn_iterator *);
 427
 428 /* Initialize a branch trace instruction iterator to point to the begin/end of
 429    the branch trace.  Throws an error if there is no branch trace.  */
 430 extern void btrace_insn_begin (struct btrace_insn_iterator *,
 431                                const struct btrace_thread_info *);
 432 extern void btrace_insn_end (struct btrace_insn_iterator *,
 433                              const struct btrace_thread_info *);
 434
 435 /* Increment/decrement a branch trace instruction iterator by at most STRIDE
 436    instructions.  Return the number of instructions by which the instruction
 437    iterator has been advanced.
 438    Returns zero, if the operation failed or STRIDE had been zero.  */
 439 extern unsigned int btrace_insn_next (struct btrace_insn_iterator *,
 440                                       unsigned int stride);
 441 extern unsigned int btrace_insn_prev (struct btrace_insn_iterator *,
 442                                       unsigned int stride);
 443
 444 /* Compare two branch trace instruction iterators.
 445    Return a negative number if LHS < RHS.
 446    Return zero if LHS == RHS.
 447    Return a positive number if LHS > RHS.  */
 448 extern int btrace_insn_cmp (const struct btrace_insn_iterator *lhs,
 449                             const struct btrace_insn_iterator *rhs);
 450
 451 /* Find an instruction or gap in the function branch trace by its number.
 452    If the instruction is found, initialize the branch trace instruction
 453    iterator to point to this instruction and return non-zero.
 454    Return zero otherwise.  */
 455 extern int btrace_find_insn_by_number (struct btrace_insn_iterator *,
 456                                        const struct btrace_thread_info *,
 457                                        unsigned int number);
 458
 459 /* Dereference a branch trace call iterator.  Return a pointer to the
 460    function the iterator points to or NULL if the interator points past
 461    the end of the branch trace.  */
 462 extern const struct btrace_function *
 463   btrace_call_get (const struct btrace_call_iterator *);
 464
 465 /* Return the function number for a branch trace call iterator.
 466    Returns one past the maximum function number for the end iterator.
 467    Returns zero if the iterator does not point to a valid function.  */
 468 extern unsigned int btrace_call_number (const struct btrace_call_iterator *);
 469
 470 /* Initialize a branch trace call iterator to point to the begin/end of
 471    the branch trace.  Throws an error if there is no branch trace.  */
 472 extern void btrace_call_begin (struct btrace_call_iterator *,
 473                                const struct btrace_thread_info *);
 474 extern void btrace_call_end (struct btrace_call_iterator *,
 475                              const struct btrace_thread_info *);
 476
 477 /* Increment/decrement a branch trace call iterator by at most STRIDE function
 478    segments.  Return the number of function segments by which the call
 479    iterator has been advanced.
 480    Returns zero, if the operation failed or STRIDE had been zero.  */
 481 extern unsigned int btrace_call_next (struct btrace_call_iterator *,
 482                                       unsigned int stride);
 483 extern unsigned int btrace_call_prev (struct btrace_call_iterator *,
 484                                       unsigned int stride);
 485
 486 /* Compare two branch trace call iterators.
 487    Return a negative number if LHS < RHS.
 488    Return zero if LHS == RHS.
 489    Return a positive number if LHS > RHS.  */
 490 extern int btrace_call_cmp (const struct btrace_call_iterator *lhs,
 491                             const struct btrace_call_iterator *rhs);
 492
 493 /* Find a function in the function branch trace by its NUMBER.
 494    If the function is found, initialize the branch trace call
 495    iterator to point to this function and return non-zero.
 496    Return zero otherwise.  */
 497 extern int btrace_find_call_by_number (struct btrace_call_iterator *,
 498                                        const struct btrace_thread_info *,
 499                                        unsigned int number);
 500
 501 /* Set the branch trace instruction history from BEGIN (inclusive) to
 502    END (exclusive).  */
 503 extern void btrace_set_insn_history (struct btrace_thread_info *,
 504                                      const struct btrace_insn_iterator *begin,
 505                                      const struct btrace_insn_iterator *end);
 506
 507 /* Set the branch trace function call history from BEGIN (inclusive) to
 508    END (exclusive).  */
 509 extern void btrace_set_call_history (struct btrace_thread_info *,
 510                                      const struct btrace_call_iterator *begin,
 511                                      const struct btrace_call_iterator *end);
 512
 513 /* Determine if branch tracing is currently replaying TP.  */
 514 extern int btrace_is_replaying (struct thread_info *tp);
 515
 516 /* Return non-zero if the branch trace for TP is empty; zero otherwise.  */
 517 extern int btrace_is_empty (struct thread_info *tp);
 518
 519 /* Create a cleanup for DATA.  */
 520 extern struct cleanup *make_cleanup_btrace_data (struct btrace_data *data);
 521
 522 #endif /* BTRACE_H */