gdb/btrace.h

   1 /* Branch trace support for GDB, the GNU debugger.
   2
   3    Copyright (C) 2013-2015 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
  32 #if defined (HAVE_LIBIPT)
  33 #  include <intel-pt.h>
  34 #endif
  35
  36 struct thread_info;
  37 struct btrace_function;
  38
  39 /* A coarse instruction classification.  */
  40 enum btrace_insn_class
  41 {
  42   /* The instruction is something not listed below.  */
  43   BTRACE_INSN_OTHER,
  44
  45   /* The instruction is a function call.  */
  46   BTRACE_INSN_CALL,
  47
  48   /* The instruction is a function return.  */
  49   BTRACE_INSN_RETURN,
  50
  51   /* The instruction is an unconditional jump.  */
  52   BTRACE_INSN_JUMP
  53 };
  54
  55 /* Instruction flags.  */
  56 enum btrace_insn_flag
  57 {
  58   /* The instruction has been executed speculatively.  */
  59   BTRACE_INSN_FLAG_SPECULATIVE = (1 << 0)
  60 };
  61
  62 /* A branch trace instruction.
  63
  64    This represents a single instruction in a branch trace.  */
  65 struct btrace_insn
  66 {
  67   /* The address of this instruction.  */
  68   CORE_ADDR pc;
  69
  70   /* The size of this instruction in bytes.  */
  71   gdb_byte size;
  72
  73   /* The instruction class of this instruction.  */
  74   enum btrace_insn_class iclass;
  75
  76   /* A bit vector of BTRACE_INSN_FLAGS.  */
  77   enum btrace_insn_flag flags;
  78 };
  79
  80 /* A vector of branch trace instructions.  */
  81 typedef struct btrace_insn btrace_insn_s;
  82 DEF_VEC_O (btrace_insn_s);
  83
  84 /* A doubly-linked list of branch trace function segments.  */
  85 struct btrace_func_link
  86 {
  87   struct btrace_function *prev;
  88   struct btrace_function *next;
  89 };
  90
  91 /* Flags for btrace function segments.  */
  92 enum btrace_function_flag
  93 {
  94   /* The 'up' link interpretation.
  95      If set, it points to the function segment we returned to.
  96      If clear, it points to the function segment we called from.  */
  97   BFUN_UP_LINKS_TO_RET = (1 << 0),
  98
  99   /* The 'up' link points to a tail call.  This obviously only makes sense
 100      if bfun_up_links_to_ret is clear.  */
 101   BFUN_UP_LINKS_TO_TAILCALL = (1 << 1)
 102 };
 103
 104 /* Decode errors for the BTS recording format.  */
 105 enum btrace_bts_error
 106 {
 107   /* The instruction trace overflowed the end of the trace block.  */
 108   BDE_BTS_OVERFLOW = 1,
 109
 110   /* The instruction size could not be determined.  */
 111   BDE_BTS_INSN_SIZE
 112 };
 113
 114 /* Decode errors for the Intel(R) Processor Trace recording format.  */
 115 enum btrace_pt_error
 116 {
 117   /* The user cancelled trace processing.  */
 118   BDE_PT_USER_QUIT = 1,
 119
 120   /* Tracing was temporarily disabled.  */
 121   BDE_PT_DISABLED,
 122
 123   /* Trace recording overflowed.  */
 124   BDE_PT_OVERFLOW
 125
 126   /* Negative numbers are used by the decoder library.  */
 127 };
 128
 129 /* A branch trace function segment.
 130
 131    This represents a function segment in a branch trace, i.e. a consecutive
 132    number of instructions belonging to the same function.
 133
 134    In case of decode errors, we add an empty function segment to indicate
 135    the gap in the trace.
 136
 137    We do not allow function segments without instructions otherwise.  */
 138 struct btrace_function
 139 {
 140   /* The full and minimal symbol for the function.  Both may be NULL.  */
 141   struct minimal_symbol *msym;
 142   struct symbol *sym;
 143
 144   /* The previous and next segment belonging to the same function.
 145      If a function calls another function, the former will have at least
 146      two segments: one before the call and another after the return.  */
 147   struct btrace_func_link segment;
 148
 149   /* The previous and next function in control flow order.  */
 150   struct btrace_func_link flow;
 151
 152   /* The directly preceding function segment in a (fake) call stack.  */
 153   struct btrace_function *up;
 154
 155   /* The instructions in this function segment.
 156      The instruction vector will be empty if the function segment
 157      represents a decode error.  */
 158   VEC (btrace_insn_s) *insn;
 159
 160   /* The error code of a decode error that led to a gap.
 161      Must be zero unless INSN is empty; non-zero otherwise.  */
 162   int errcode;
 163
 164   /* The instruction number offset for the first instruction in this
 165      function segment.
 166      If INSN is empty this is the insn_offset of the succeding function
 167      segment in control-flow order.  */
 168   unsigned int insn_offset;
 169
 170   /* The function number in control-flow order.
 171      If INSN is empty indicating a gap in the trace due to a decode error,
 172      we still count the gap as a function.  */
 173   unsigned int number;
 174
 175   /* The function level in a back trace across the entire branch trace.
 176      A caller's level is one lower than the level of its callee.
 177
 178      Levels can be negative if we see returns for which we have not seen
 179      the corresponding calls.  The branch trace thread information provides
 180      a fixup to normalize function levels so the smallest level is zero.  */
 181   int level;
 182
 183   /* A bit-vector of btrace_function_flag.  */
 184   enum btrace_function_flag flags;
 185 };
 186
 187 /* A branch trace instruction iterator.  */
 188 struct btrace_insn_iterator
 189 {
 190   /* The branch trace function segment containing the instruction.
 191      Will never be NULL.  */
 192   const struct btrace_function *function;
 193
 194   /* The index into the function segment's instruction vector.  */
 195   unsigned int index;
 196 };
 197
 198 /* A branch trace function call iterator.  */
 199 struct btrace_call_iterator
 200 {
 201   /* The branch trace information for this thread.  Will never be NULL.  */
 202   const struct btrace_thread_info *btinfo;
 203
 204   /* The branch trace function segment.
 205      This will be NULL for the iterator pointing to the end of the trace.  */
 206   const struct btrace_function *function;
 207 };
 208
 209 /* Branch trace iteration state for "record instruction-history".  */
 210 struct btrace_insn_history
 211 {
 212   /* The branch trace instruction range from BEGIN (inclusive) to
 213      END (exclusive) that has been covered last time.  */
 214   struct btrace_insn_iterator begin;
 215   struct btrace_insn_iterator end;
 216 };
 217
 218 /* Branch trace iteration state for "record function-call-history".  */
 219 struct btrace_call_history
 220 {
 221   /* The branch trace function range from BEGIN (inclusive) to END (exclusive)
 222      that has been covered last time.  */
 223   struct btrace_call_iterator begin;
 224   struct btrace_call_iterator end;
 225 };
 226
 227 /* Branch trace thread flags.  */
 228 enum btrace_thread_flag
 229 {
 230   /* The thread is to be stepped forwards.  */
 231   BTHR_STEP = (1 << 0),
 232
 233   /* The thread is to be stepped backwards.  */
 234   BTHR_RSTEP = (1 << 1),
 235
 236   /* The thread is to be continued forwards.  */
 237   BTHR_CONT = (1 << 2),
 238
 239   /* The thread is to be continued backwards.  */
 240   BTHR_RCONT = (1 << 3),
 241
 242   /* The thread is to be moved.  */
 243   BTHR_MOVE = (BTHR_STEP | BTHR_RSTEP | BTHR_CONT | BTHR_RCONT)
 244 };
 245
 246 #if defined (HAVE_LIBIPT)
 247 /* A packet.  */
 248 struct btrace_pt_packet
 249 {
 250   /* The offset in the trace stream.  */
 251   uint64_t offset;
 252
 253   /* The decode error code.  */
 254   enum pt_error_code errcode;
 255
 256   /* The decoded packet.  Only valid if ERRCODE == pte_ok.  */
 257   struct pt_packet packet;
 258 };
 259
 260 /* Define functions operating on a vector of packets.  */
 261 typedef struct btrace_pt_packet btrace_pt_packet_s;
 262 DEF_VEC_O (btrace_pt_packet_s);
 263 #endif /* defined (HAVE_LIBIPT)  */
 264
 265 /* Branch trace iteration state for "maintenance btrace packet-history".  */
 266 struct btrace_maint_packet_history
 267 {
 268   /* The branch trace packet range from BEGIN (inclusive) to
 269      END (exclusive) that has been covered last time.  */
 270   unsigned int begin;
 271   unsigned int end;
 272 };
 273
 274 /* Branch trace maintenance information per thread.
 275
 276    This information is used by "maintenance btrace" commands.  */
 277 struct btrace_maint_info
 278 {
 279   /* Most information is format-specific.
 280      The format can be found in the BTRACE.DATA.FORMAT field of each thread.  */
 281   union
 282   {
 283     /* BTRACE.DATA.FORMAT == BTRACE_FORMAT_BTS  */
 284     struct
 285     {
 286       /* The packet history iterator.
 287          We are iterating over BTRACE.DATA.FORMAT.VARIANT.BTS.BLOCKS.  */
 288       struct btrace_maint_packet_history packet_history;
 289     } bts;
 290
 291 #if defined (HAVE_LIBIPT)
 292     /* BTRACE.DATA.FORMAT == BTRACE_FORMAT_PT  */
 293     struct
 294     {
 295       /* A vector of decoded packets.  */
 296       VEC (btrace_pt_packet_s) *packets;
 297
 298       /* The packet history iterator.
 299          We are iterating over the above PACKETS vector.  */
 300       struct btrace_maint_packet_history packet_history;
 301     } pt;
 302 #endif /* defined (HAVE_LIBIPT)  */
 303   } variant;
 304 };
 305
 306 /* Branch trace information per thread.
 307
 308    This represents the branch trace configuration as well as the entry point
 309    into the branch trace data.  For the latter, it also contains the index into
 310    an array of branch trace blocks used for iterating though the branch trace
 311    blocks of a thread.  */
 312 struct btrace_thread_info
 313 {
 314   /* The target branch trace information for this thread.
 315
 316      This contains the branch trace configuration as well as any
 317      target-specific information necessary for implementing branch tracing on
 318      the underlying architecture.  */
 319   struct btrace_target_info *target;
 320
 321   /* The raw branch trace data for the below branch trace.  */
 322   struct btrace_data data;
 323
 324   /* The current branch trace for this thread (both inclusive).
 325
 326      The last instruction of END is the current instruction, which is not
 327      part of the execution history.
 328      Both will be NULL if there is no branch trace available.  If there is
 329      branch trace available, both will be non-NULL.  */
 330   struct btrace_function *begin;
 331   struct btrace_function *end;
 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   enum btrace_thread_flag 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 /* Fetch the branch trace for a single thread.  */
 381 extern void btrace_fetch (struct thread_info *);
 382
 383 /* Clear the branch trace for a single thread.  */
 384 extern void btrace_clear (struct thread_info *);
 385
 386 /* Clear the branch trace for all threads when an object file goes away.  */
 387 extern void btrace_free_objfile (struct objfile *);
 388
 389 /* Parse a branch trace xml document XML into DATA.  */
 390 extern void parse_xml_btrace (struct btrace_data *data, const char *xml);
 391
 392 /* Parse a branch trace configuration xml document XML into CONF.  */
 393 extern void parse_xml_btrace_conf (struct btrace_config *conf, const char *xml);
 394
 395 /* Dereference a branch trace instruction iterator.  Return a pointer to the
 396    instruction the iterator points to.
 397    May return NULL if the iterator points to a gap in the trace.  */
 398 extern const struct btrace_insn *
 399   btrace_insn_get (const struct btrace_insn_iterator *);
 400
 401 /* Return the instruction number for a branch trace iterator.
 402    Returns one past the maximum instruction number for the end iterator.
 403    Returns zero if the iterator does not point to a valid instruction.  */
 404 extern unsigned int btrace_insn_number (const struct btrace_insn_iterator *);
 405
 406 /* Initialize a branch trace instruction iterator to point to the begin/end of
 407    the branch trace.  Throws an error if there is no branch trace.  */
 408 extern void btrace_insn_begin (struct btrace_insn_iterator *,
 409                                const struct btrace_thread_info *);
 410 extern void btrace_insn_end (struct btrace_insn_iterator *,
 411                              const struct btrace_thread_info *);
 412
 413 /* Increment/decrement a branch trace instruction iterator by at most STRIDE
 414    instructions.  Return the number of instructions by which the instruction
 415    iterator has been advanced.
 416    Returns zero, if the operation failed or STRIDE had been zero.  */
 417 extern unsigned int btrace_insn_next (struct btrace_insn_iterator *,
 418                                       unsigned int stride);
 419 extern unsigned int btrace_insn_prev (struct btrace_insn_iterator *,
 420                                       unsigned int stride);
 421
 422 /* Compare two branch trace instruction iterators.
 423    Return a negative number if LHS < RHS.
 424    Return zero if LHS == RHS.
 425    Return a positive number if LHS > RHS.  */
 426 extern int btrace_insn_cmp (const struct btrace_insn_iterator *lhs,
 427                             const struct btrace_insn_iterator *rhs);
 428
 429 /* Find an instruction in the function branch trace by its number.
 430    If the instruction is found, initialize the branch trace instruction
 431    iterator to point to this instruction and return non-zero.
 432    Return zero otherwise.  */
 433 extern int btrace_find_insn_by_number (struct btrace_insn_iterator *,
 434                                        const struct btrace_thread_info *,
 435                                        unsigned int number);
 436
 437 /* Dereference a branch trace call iterator.  Return a pointer to the
 438    function the iterator points to or NULL if the interator points past
 439    the end of the branch trace.  */
 440 extern const struct btrace_function *
 441   btrace_call_get (const struct btrace_call_iterator *);
 442
 443 /* Return the function number for a branch trace call iterator.
 444    Returns one past the maximum function number for the end iterator.
 445    Returns zero if the iterator does not point to a valid function.  */
 446 extern unsigned int btrace_call_number (const struct btrace_call_iterator *);
 447
 448 /* Initialize a branch trace call iterator to point to the begin/end of
 449    the branch trace.  Throws an error if there is no branch trace.  */
 450 extern void btrace_call_begin (struct btrace_call_iterator *,
 451                                const struct btrace_thread_info *);
 452 extern void btrace_call_end (struct btrace_call_iterator *,
 453                              const struct btrace_thread_info *);
 454
 455 /* Increment/decrement a branch trace call iterator by at most STRIDE function
 456    segments.  Return the number of function segments by which the call
 457    iterator has been advanced.
 458    Returns zero, if the operation failed or STRIDE had been zero.  */
 459 extern unsigned int btrace_call_next (struct btrace_call_iterator *,
 460                                       unsigned int stride);
 461 extern unsigned int btrace_call_prev (struct btrace_call_iterator *,
 462                                       unsigned int stride);
 463
 464 /* Compare two branch trace call iterators.
 465    Return a negative number if LHS < RHS.
 466    Return zero if LHS == RHS.
 467    Return a positive number if LHS > RHS.  */
 468 extern int btrace_call_cmp (const struct btrace_call_iterator *lhs,
 469                             const struct btrace_call_iterator *rhs);
 470
 471 /* Find a function in the function branch trace by its NUMBER.
 472    If the function is found, initialize the branch trace call
 473    iterator to point to this function and return non-zero.
 474    Return zero otherwise.  */
 475 extern int btrace_find_call_by_number (struct btrace_call_iterator *,
 476                                        const struct btrace_thread_info *,
 477                                        unsigned int number);
 478
 479 /* Set the branch trace instruction history from BEGIN (inclusive) to
 480    END (exclusive).  */
 481 extern void btrace_set_insn_history (struct btrace_thread_info *,
 482                                      const struct btrace_insn_iterator *begin,
 483                                      const struct btrace_insn_iterator *end);
 484
 485 /* Set the branch trace function call history from BEGIN (inclusive) to
 486    END (exclusive).  */
 487 extern void btrace_set_call_history (struct btrace_thread_info *,
 488                                      const struct btrace_call_iterator *begin,
 489                                      const struct btrace_call_iterator *end);
 490
 491 /* Determine if branch tracing is currently replaying TP.  */
 492 extern int btrace_is_replaying (struct thread_info *tp);
 493
 494 /* Return non-zero if the branch trace for TP is empty; zero otherwise.  */
 495 extern int btrace_is_empty (struct thread_info *tp);
 496
 497 /* Create a cleanup for DATA.  */
 498 extern struct cleanup *make_cleanup_btrace_data (struct btrace_data *data);
 499
 500 #endif /* BTRACE_H */