gdb/btrace.h

   1 /* Branch trace support for GDB, the GNU debugger.
   2
   3    Copyright (C) 2013-2016 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(R) 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 /* A branch trace instruction iterator.  */
 191 struct btrace_insn_iterator
 192 {
 193   /* The branch trace function segment containing the instruction.
 194      Will never be NULL.  */
 195   const struct btrace_function *function;
 196
 197   /* The index into the function segment's instruction vector.  */
 198   unsigned int index;
 199 };
 200
 201 /* A branch trace function call iterator.  */
 202 struct btrace_call_iterator
 203 {
 204   /* The branch trace information for this thread.  Will never be NULL.  */
 205   const struct btrace_thread_info *btinfo;
 206
 207   /* The branch trace function segment.
 208      This will be NULL for the iterator pointing to the end of the trace.  */
 209   const struct btrace_function *function;
 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
 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 /* Define functions operating on a vector of packets.  */
 268 typedef struct btrace_pt_packet btrace_pt_packet_s;
 269 DEF_VEC_O (btrace_pt_packet_s);
 270 #endif /* defined (HAVE_LIBIPT)  */
 271
 272 /* Branch trace iteration state for "maintenance btrace packet-history".  */
 273 struct btrace_maint_packet_history
 274 {
 275   /* The branch trace packet range from BEGIN (inclusive) to
 276      END (exclusive) that has been covered last time.  */
 277   unsigned int begin;
 278   unsigned int end;
 279 };
 280
 281 /* Branch trace maintenance information per thread.
 282
 283    This information is used by "maintenance btrace" commands.  */
 284 struct btrace_maint_info
 285 {
 286   /* Most information is format-specific.
 287      The format can be found in the BTRACE.DATA.FORMAT field of each thread.  */
 288   union
 289   {
 290     /* BTRACE.DATA.FORMAT == BTRACE_FORMAT_BTS  */
 291     struct
 292     {
 293       /* The packet history iterator.
 294          We are iterating over BTRACE.DATA.FORMAT.VARIANT.BTS.BLOCKS.  */
 295       struct btrace_maint_packet_history packet_history;
 296     } bts;
 297
 298 #if defined (HAVE_LIBIPT)
 299     /* BTRACE.DATA.FORMAT == BTRACE_FORMAT_PT  */
 300     struct
 301     {
 302       /* A vector of decoded packets.  */
 303       VEC (btrace_pt_packet_s) *packets;
 304
 305       /* The packet history iterator.
 306          We are iterating over the above PACKETS vector.  */
 307       struct btrace_maint_packet_history packet_history;
 308     } pt;
 309 #endif /* defined (HAVE_LIBIPT)  */
 310   } variant;
 311 };
 312
 313 /* Branch trace information per thread.
 314
 315    This represents the branch trace configuration as well as the entry point
 316    into the branch trace data.  For the latter, it also contains the index into
 317    an array of branch trace blocks used for iterating though the branch trace
 318    blocks of a thread.  */
 319 struct btrace_thread_info
 320 {
 321   /* The target branch trace information for this thread.
 322
 323      This contains the branch trace configuration as well as any
 324      target-specific information necessary for implementing branch tracing on
 325      the underlying architecture.  */
 326   struct btrace_target_info *target;
 327
 328   /* The raw branch trace data for the below branch trace.  */
 329   struct btrace_data data;
 330
 331   /* The current branch trace for this thread (both inclusive).
 332
 333      The last instruction of END is the current instruction, which is not
 334      part of the execution history.
 335      Both will be NULL if there is no branch trace available.  If there is
 336      branch trace available, both will be non-NULL.  */
 337   struct btrace_function *begin;
 338   struct btrace_function *end;
 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 /* Fetch the branch trace for a single thread.  */
 388 extern void btrace_fetch (struct thread_info *);
 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 /* Parse a branch trace xml document XML into DATA.  */
 397 extern void parse_xml_btrace (struct btrace_data *data, const char *xml);
 398
 399 /* Parse a branch trace configuration xml document XML into CONF.  */
 400 extern void parse_xml_btrace_conf (struct btrace_config *conf, const char *xml);
 401
 402 /* Dereference a branch trace instruction iterator.  Return a pointer to the
 403    instruction the iterator points to.
 404    May return NULL if the iterator points to a gap in the trace.  */
 405 extern const struct btrace_insn *
 406   btrace_insn_get (const struct btrace_insn_iterator *);
 407
 408 /* Return the instruction number for a branch trace iterator.
 409    Returns one past the maximum instruction number for the end iterator.
 410    Returns zero if the iterator does not point to a valid instruction.  */
 411 extern unsigned int btrace_insn_number (const struct btrace_insn_iterator *);
 412
 413 /* Initialize a branch trace instruction iterator to point to the begin/end of
 414    the branch trace.  Throws an error if there is no branch trace.  */
 415 extern void btrace_insn_begin (struct btrace_insn_iterator *,
 416                                const struct btrace_thread_info *);
 417 extern void btrace_insn_end (struct btrace_insn_iterator *,
 418                              const struct btrace_thread_info *);
 419
 420 /* Increment/decrement a branch trace instruction iterator by at most STRIDE
 421    instructions.  Return the number of instructions by which the instruction
 422    iterator has been advanced.
 423    Returns zero, if the operation failed or STRIDE had been zero.  */
 424 extern unsigned int btrace_insn_next (struct btrace_insn_iterator *,
 425                                       unsigned int stride);
 426 extern unsigned int btrace_insn_prev (struct btrace_insn_iterator *,
 427                                       unsigned int stride);
 428
 429 /* Compare two branch trace instruction iterators.
 430    Return a negative number if LHS < RHS.
 431    Return zero if LHS == RHS.
 432    Return a positive number if LHS > RHS.  */
 433 extern int btrace_insn_cmp (const struct btrace_insn_iterator *lhs,
 434                             const struct btrace_insn_iterator *rhs);
 435
 436 /* Find an instruction in the function branch trace by its number.
 437    If the instruction is found, initialize the branch trace instruction
 438    iterator to point to this instruction and return non-zero.
 439    Return zero otherwise.  */
 440 extern int btrace_find_insn_by_number (struct btrace_insn_iterator *,
 441                                        const struct btrace_thread_info *,
 442                                        unsigned int number);
 443
 444 /* Dereference a branch trace call iterator.  Return a pointer to the
 445    function the iterator points to or NULL if the interator points past
 446    the end of the branch trace.  */
 447 extern const struct btrace_function *
 448   btrace_call_get (const struct btrace_call_iterator *);
 449
 450 /* Return the function number for a branch trace call iterator.
 451    Returns one past the maximum function number for the end iterator.
 452    Returns zero if the iterator does not point to a valid function.  */
 453 extern unsigned int btrace_call_number (const struct btrace_call_iterator *);
 454
 455 /* Initialize a branch trace call iterator to point to the begin/end of
 456    the branch trace.  Throws an error if there is no branch trace.  */
 457 extern void btrace_call_begin (struct btrace_call_iterator *,
 458                                const struct btrace_thread_info *);
 459 extern void btrace_call_end (struct btrace_call_iterator *,
 460                              const struct btrace_thread_info *);
 461
 462 /* Increment/decrement a branch trace call iterator by at most STRIDE function
 463    segments.  Return the number of function segments by which the call
 464    iterator has been advanced.
 465    Returns zero, if the operation failed or STRIDE had been zero.  */
 466 extern unsigned int btrace_call_next (struct btrace_call_iterator *,
 467                                       unsigned int stride);
 468 extern unsigned int btrace_call_prev (struct btrace_call_iterator *,
 469                                       unsigned int stride);
 470
 471 /* Compare two branch trace call iterators.
 472    Return a negative number if LHS < RHS.
 473    Return zero if LHS == RHS.
 474    Return a positive number if LHS > RHS.  */
 475 extern int btrace_call_cmp (const struct btrace_call_iterator *lhs,
 476                             const struct btrace_call_iterator *rhs);
 477
 478 /* Find a function in the function branch trace by its NUMBER.
 479    If the function is found, initialize the branch trace call
 480    iterator to point to this function and return non-zero.
 481    Return zero otherwise.  */
 482 extern int btrace_find_call_by_number (struct btrace_call_iterator *,
 483                                        const struct btrace_thread_info *,
 484                                        unsigned int number);
 485
 486 /* Set the branch trace instruction history from BEGIN (inclusive) to
 487    END (exclusive).  */
 488 extern void btrace_set_insn_history (struct btrace_thread_info *,
 489                                      const struct btrace_insn_iterator *begin,
 490                                      const struct btrace_insn_iterator *end);
 491
 492 /* Set the branch trace function call history from BEGIN (inclusive) to
 493    END (exclusive).  */
 494 extern void btrace_set_call_history (struct btrace_thread_info *,
 495                                      const struct btrace_call_iterator *begin,
 496                                      const struct btrace_call_iterator *end);
 497
 498 /* Determine if branch tracing is currently replaying TP.  */
 499 extern int btrace_is_replaying (struct thread_info *tp);
 500
 501 /* Return non-zero if the branch trace for TP is empty; zero otherwise.  */
 502 extern int btrace_is_empty (struct thread_info *tp);
 503
 504 /* Create a cleanup for DATA.  */
 505 extern struct cleanup *make_cleanup_btrace_data (struct btrace_data *data);
 506
 507 #endif /* BTRACE_H */