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 /* Branch trace information per thread.
 237
 238    This represents the branch trace configuration as well as the entry point
 239    into the branch trace data.  For the latter, it also contains the index into
 240    an array of branch trace blocks used for iterating though the branch trace
 241    blocks of a thread.  */
 242 struct btrace_thread_info
 243 {
 244   /* The target branch trace information for this thread.
 245
 246      This contains the branch trace configuration as well as any
 247      target-specific information necessary for implementing branch tracing on
 248      the underlying architecture.  */
 249   struct btrace_target_info *target;
 250
 251   /* The current branch trace for this thread (both inclusive).
 252
 253      The last instruction of END is the current instruction, which is not
 254      part of the execution history.
 255      Both will be NULL if there is no branch trace available.  If there is
 256      branch trace available, both will be non-NULL.  */
 257   struct btrace_function *begin;
 258   struct btrace_function *end;
 259
 260   /* The function level offset.  When added to each function's LEVEL,
 261      this normalizes the function levels such that the smallest level
 262      becomes zero.  */
 263   int level;
 264
 265   /* The number of gaps in the trace.  */
 266   unsigned int ngaps;
 267
 268   /* A bit-vector of btrace_thread_flag.  */
 269   enum btrace_thread_flag flags;
 270
 271   /* The instruction history iterator.  */
 272   struct btrace_insn_history *insn_history;
 273
 274   /* The function call history iterator.  */
 275   struct btrace_call_history *call_history;
 276
 277   /* The current replay position.  NULL if not replaying.
 278      Gaps are skipped during replay, so REPLAY always points to a valid
 279      instruction.  */
 280   struct btrace_insn_iterator *replay;
 281
 282   /* Why the thread stopped, if we need to track it.  */
 283   enum target_stop_reason stop_reason;
 284 };
 285
 286 /* Enable branch tracing for a thread.  */
 287 extern void btrace_enable (struct thread_info *tp,
 288                            const struct btrace_config *conf);
 289
 290 /* Get the branch trace configuration for a thread.
 291    Return NULL if branch tracing is not enabled for that thread.  */
 292 extern const struct btrace_config *
 293   btrace_conf (const struct btrace_thread_info *);
 294
 295 /* Disable branch tracing for a thread.
 296    This will also delete the current branch trace data.  */
 297 extern void btrace_disable (struct thread_info *);
 298
 299 /* Disable branch tracing for a thread during teardown.
 300    This is similar to btrace_disable, except that it will use
 301    target_teardown_btrace instead of target_disable_btrace.  */
 302 extern void btrace_teardown (struct thread_info *);
 303
 304 /* Fetch the branch trace for a single thread.  */
 305 extern void btrace_fetch (struct thread_info *);
 306
 307 /* Clear the branch trace for a single thread.  */
 308 extern void btrace_clear (struct thread_info *);
 309
 310 /* Clear the branch trace for all threads when an object file goes away.  */
 311 extern void btrace_free_objfile (struct objfile *);
 312
 313 /* Parse a branch trace xml document XML into DATA.  */
 314 extern void parse_xml_btrace (struct btrace_data *data, const char *xml);
 315
 316 /* Parse a branch trace configuration xml document XML into CONF.  */
 317 extern void parse_xml_btrace_conf (struct btrace_config *conf, const char *xml);
 318
 319 /* Dereference a branch trace instruction iterator.  Return a pointer to the
 320    instruction the iterator points to.
 321    May return NULL if the iterator points to a gap in the trace.  */
 322 extern const struct btrace_insn *
 323   btrace_insn_get (const struct btrace_insn_iterator *);
 324
 325 /* Return the instruction number for a branch trace iterator.
 326    Returns one past the maximum instruction number for the end iterator.
 327    Returns zero if the iterator does not point to a valid instruction.  */
 328 extern unsigned int btrace_insn_number (const struct btrace_insn_iterator *);
 329
 330 /* Initialize a branch trace instruction iterator to point to the begin/end of
 331    the branch trace.  Throws an error if there is no branch trace.  */
 332 extern void btrace_insn_begin (struct btrace_insn_iterator *,
 333                                const struct btrace_thread_info *);
 334 extern void btrace_insn_end (struct btrace_insn_iterator *,
 335                              const struct btrace_thread_info *);
 336
 337 /* Increment/decrement a branch trace instruction iterator by at most STRIDE
 338    instructions.  Return the number of instructions by which the instruction
 339    iterator has been advanced.
 340    Returns zero, if the operation failed or STRIDE had been zero.  */
 341 extern unsigned int btrace_insn_next (struct btrace_insn_iterator *,
 342                                       unsigned int stride);
 343 extern unsigned int btrace_insn_prev (struct btrace_insn_iterator *,
 344                                       unsigned int stride);
 345
 346 /* Compare two branch trace instruction iterators.
 347    Return a negative number if LHS < RHS.
 348    Return zero if LHS == RHS.
 349    Return a positive number if LHS > RHS.  */
 350 extern int btrace_insn_cmp (const struct btrace_insn_iterator *lhs,
 351                             const struct btrace_insn_iterator *rhs);
 352
 353 /* Find an instruction in the function branch trace by its number.
 354    If the instruction is found, initialize the branch trace instruction
 355    iterator to point to this instruction and return non-zero.
 356    Return zero otherwise.  */
 357 extern int btrace_find_insn_by_number (struct btrace_insn_iterator *,
 358                                        const struct btrace_thread_info *,
 359                                        unsigned int number);
 360
 361 /* Dereference a branch trace call iterator.  Return a pointer to the
 362    function the iterator points to or NULL if the interator points past
 363    the end of the branch trace.  */
 364 extern const struct btrace_function *
 365   btrace_call_get (const struct btrace_call_iterator *);
 366
 367 /* Return the function number for a branch trace call iterator.
 368    Returns one past the maximum function number for the end iterator.
 369    Returns zero if the iterator does not point to a valid function.  */
 370 extern unsigned int btrace_call_number (const struct btrace_call_iterator *);
 371
 372 /* Initialize a branch trace call iterator to point to the begin/end of
 373    the branch trace.  Throws an error if there is no branch trace.  */
 374 extern void btrace_call_begin (struct btrace_call_iterator *,
 375                                const struct btrace_thread_info *);
 376 extern void btrace_call_end (struct btrace_call_iterator *,
 377                              const struct btrace_thread_info *);
 378
 379 /* Increment/decrement a branch trace call iterator by at most STRIDE function
 380    segments.  Return the number of function segments by which the call
 381    iterator has been advanced.
 382    Returns zero, if the operation failed or STRIDE had been zero.  */
 383 extern unsigned int btrace_call_next (struct btrace_call_iterator *,
 384                                       unsigned int stride);
 385 extern unsigned int btrace_call_prev (struct btrace_call_iterator *,
 386                                       unsigned int stride);
 387
 388 /* Compare two branch trace call iterators.
 389    Return a negative number if LHS < RHS.
 390    Return zero if LHS == RHS.
 391    Return a positive number if LHS > RHS.  */
 392 extern int btrace_call_cmp (const struct btrace_call_iterator *lhs,
 393                             const struct btrace_call_iterator *rhs);
 394
 395 /* Find a function in the function branch trace by its NUMBER.
 396    If the function is found, initialize the branch trace call
 397    iterator to point to this function and return non-zero.
 398    Return zero otherwise.  */
 399 extern int btrace_find_call_by_number (struct btrace_call_iterator *,
 400                                        const struct btrace_thread_info *,
 401                                        unsigned int number);
 402
 403 /* Set the branch trace instruction history from BEGIN (inclusive) to
 404    END (exclusive).  */
 405 extern void btrace_set_insn_history (struct btrace_thread_info *,
 406                                      const struct btrace_insn_iterator *begin,
 407                                      const struct btrace_insn_iterator *end);
 408
 409 /* Set the branch trace function call history from BEGIN (inclusive) to
 410    END (exclusive).  */
 411 extern void btrace_set_call_history (struct btrace_thread_info *,
 412                                      const struct btrace_call_iterator *begin,
 413                                      const struct btrace_call_iterator *end);
 414
 415 /* Determine if branch tracing is currently replaying TP.  */
 416 extern int btrace_is_replaying (struct thread_info *tp);
 417
 418 /* Return non-zero if the branch trace for TP is empty; zero otherwise.  */
 419 extern int btrace_is_empty (struct thread_info *tp);
 420
 421 /* Create a cleanup for DATA.  */
 422 extern struct cleanup *make_cleanup_btrace_data (struct btrace_data *data);
 423
 424 #endif /* BTRACE_H */