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 index of the function segment in BTINFO->FUNCTIONS.  */
 199   unsigned int call_index;
 200
 201   /* The index into the function segment's instruction vector.  */
 202   unsigned int insn_index;
 203 };
 204
 205 /* A branch trace function call iterator.  */
 206 struct btrace_call_iterator
 207 {
 208   /* The branch trace information for this thread.  Will never be NULL.  */
 209   const struct btrace_thread_info *btinfo;
 210
 211   /* The index of the function segment in BTINFO->FUNCTIONS.  */
 212   unsigned int index;
 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   /* Vector of pointer to decoded function segments in execution flow order.
 335      Note that the numbering for btrace function segments starts with 1, so
 336      function segment i will be at index (i - 1).  */
 337   std::vector<btrace_function *> functions;
 338
 339   /* The function level offset.  When added to each function's LEVEL,
 340      this normalizes the function levels such that the smallest level
 341      becomes zero.  */
 342   int level;
 343
 344   /* The number of gaps in the trace.  */
 345   unsigned int ngaps;
 346
 347   /* A bit-vector of btrace_thread_flag.  */
 348   btrace_thread_flags flags;
 349
 350   /* The instruction history iterator.  */
 351   struct btrace_insn_history *insn_history;
 352
 353   /* The function call history iterator.  */
 354   struct btrace_call_history *call_history;
 355
 356   /* The current replay position.  NULL if not replaying.
 357      Gaps are skipped during replay, so REPLAY always points to a valid
 358      instruction.  */
 359   struct btrace_insn_iterator *replay;
 360
 361   /* Why the thread stopped, if we need to track it.  */
 362   enum target_stop_reason stop_reason;
 363
 364   /* Maintenance information.  */
 365   struct btrace_maint_info maint;
 366 };
 367
 368 /* Enable branch tracing for a thread.  */
 369 extern void btrace_enable (struct thread_info *tp,
 370                            const struct btrace_config *conf);
 371
 372 /* Get the branch trace configuration for a thread.
 373    Return NULL if branch tracing is not enabled for that thread.  */
 374 extern const struct btrace_config *
 375   btrace_conf (const struct btrace_thread_info *);
 376
 377 /* Disable branch tracing for a thread.
 378    This will also delete the current branch trace data.  */
 379 extern void btrace_disable (struct thread_info *);
 380
 381 /* Disable branch tracing for a thread during teardown.
 382    This is similar to btrace_disable, except that it will use
 383    target_teardown_btrace instead of target_disable_btrace.  */
 384 extern void btrace_teardown (struct thread_info *);
 385
 386 /* Return a human readable error string for the given ERRCODE in FORMAT.
 387    The pointer will never be NULL and must not be freed.  */
 388
 389 extern const char *btrace_decode_error (enum btrace_format format, int errcode);
 390
 391 /* Fetch the branch trace for a single thread.  */
 392 extern void btrace_fetch (struct thread_info *);
 393
 394 /* Clear the branch trace for a single thread.  */
 395 extern void btrace_clear (struct thread_info *);
 396
 397 /* Clear the branch trace for all threads when an object file goes away.  */
 398 extern void btrace_free_objfile (struct objfile *);
 399
 400 /* Parse a branch trace xml document XML into DATA.  */
 401 extern void parse_xml_btrace (struct btrace_data *data, const char *xml);
 402
 403 /* Parse a branch trace configuration xml document XML into CONF.  */
 404 extern void parse_xml_btrace_conf (struct btrace_config *conf, const char *xml);
 405
 406 /* Dereference a branch trace instruction iterator.  Return a pointer to the
 407    instruction the iterator points to.
 408    May return NULL if the iterator points to a gap in the trace.  */
 409 extern const struct btrace_insn *
 410   btrace_insn_get (const struct btrace_insn_iterator *);
 411
 412 /* Return the error code for a branch trace instruction iterator.  Returns zero
 413    if there is no error, i.e. the instruction is valid.  */
 414 extern int btrace_insn_get_error (const struct btrace_insn_iterator *);
 415
 416 /* Return the instruction number for a branch trace iterator.
 417    Returns one past the maximum instruction number for the end iterator.  */
 418 extern unsigned int btrace_insn_number (const struct btrace_insn_iterator *);
 419
 420 /* Initialize a branch trace instruction iterator to point to the begin/end of
 421    the branch trace.  Throws an error if there is no branch trace.  */
 422 extern void btrace_insn_begin (struct btrace_insn_iterator *,
 423                                const struct btrace_thread_info *);
 424 extern void btrace_insn_end (struct btrace_insn_iterator *,
 425                              const struct btrace_thread_info *);
 426
 427 /* Increment/decrement a branch trace instruction iterator by at most STRIDE
 428    instructions.  Return the number of instructions by which the instruction
 429    iterator has been advanced.
 430    Returns zero, if the operation failed or STRIDE had been zero.  */
 431 extern unsigned int btrace_insn_next (struct btrace_insn_iterator *,
 432                                       unsigned int stride);
 433 extern unsigned int btrace_insn_prev (struct btrace_insn_iterator *,
 434                                       unsigned int stride);
 435
 436 /* Compare two branch trace instruction iterators.
 437    Return a negative number if LHS < RHS.
 438    Return zero if LHS == RHS.
 439    Return a positive number if LHS > RHS.  */
 440 extern int btrace_insn_cmp (const struct btrace_insn_iterator *lhs,
 441                             const struct btrace_insn_iterator *rhs);
 442
 443 /* Find an instruction or gap in the function branch trace by its number.
 444    If the instruction is found, initialize the branch trace instruction
 445    iterator to point to this instruction and return non-zero.
 446    Return zero otherwise.  */
 447 extern int btrace_find_insn_by_number (struct btrace_insn_iterator *,
 448                                        const struct btrace_thread_info *,
 449                                        unsigned int number);
 450
 451 /* Dereference a branch trace call iterator.  Return a pointer to the
 452    function the iterator points to or NULL if the interator points past
 453    the end of the branch trace.  */
 454 extern const struct btrace_function *
 455   btrace_call_get (const struct btrace_call_iterator *);
 456
 457 /* Return the function number for a branch trace call iterator.
 458    Returns one past the maximum function number for the end iterator.
 459    Returns zero if the iterator does not point to a valid function.  */
 460 extern unsigned int btrace_call_number (const struct btrace_call_iterator *);
 461
 462 /* Initialize a branch trace call iterator to point to the begin/end of
 463    the branch trace.  Throws an error if there is no branch trace.  */
 464 extern void btrace_call_begin (struct btrace_call_iterator *,
 465                                const struct btrace_thread_info *);
 466 extern void btrace_call_end (struct btrace_call_iterator *,
 467                              const struct btrace_thread_info *);
 468
 469 /* Increment/decrement a branch trace call iterator by at most STRIDE function
 470    segments.  Return the number of function segments by which the call
 471    iterator has been advanced.
 472    Returns zero, if the operation failed or STRIDE had been zero.  */
 473 extern unsigned int btrace_call_next (struct btrace_call_iterator *,
 474                                       unsigned int stride);
 475 extern unsigned int btrace_call_prev (struct btrace_call_iterator *,
 476                                       unsigned int stride);
 477
 478 /* Compare two branch trace call iterators.
 479    Return a negative number if LHS < RHS.
 480    Return zero if LHS == RHS.
 481    Return a positive number if LHS > RHS.  */
 482 extern int btrace_call_cmp (const struct btrace_call_iterator *lhs,
 483                             const struct btrace_call_iterator *rhs);
 484
 485 /* Find a function in the function branch trace by its NUMBER.
 486    If the function is found, initialize the branch trace call
 487    iterator to point to this function and return non-zero.
 488    Return zero otherwise.  */
 489 extern int btrace_find_call_by_number (struct btrace_call_iterator *,
 490                                        const struct btrace_thread_info *,
 491                                        unsigned int number);
 492
 493 /* Set the branch trace instruction history from BEGIN (inclusive) to
 494    END (exclusive).  */
 495 extern void btrace_set_insn_history (struct btrace_thread_info *,
 496                                      const struct btrace_insn_iterator *begin,
 497                                      const struct btrace_insn_iterator *end);
 498
 499 /* Set the branch trace function call history from BEGIN (inclusive) to
 500    END (exclusive).  */
 501 extern void btrace_set_call_history (struct btrace_thread_info *,
 502                                      const struct btrace_call_iterator *begin,
 503                                      const struct btrace_call_iterator *end);
 504
 505 /* Determine if branch tracing is currently replaying TP.  */
 506 extern int btrace_is_replaying (struct thread_info *tp);
 507
 508 /* Return non-zero if the branch trace for TP is empty; zero otherwise.  */
 509 extern int btrace_is_empty (struct thread_info *tp);
 510
 511 /* Create a cleanup for DATA.  */
 512 extern struct cleanup *make_cleanup_btrace_data (struct btrace_data *data);
 513
 514 #endif /* BTRACE_H */