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