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 struct thread_info;
  33 struct btrace_function;
  34
  35 /* A coarse instruction classification.  */
  36 enum btrace_insn_class
  37 {
  38   /* The instruction is something not listed below.  */
  39   BTRACE_INSN_OTHER,
  40
  41   /* The instruction is a function call.  */
  42   BTRACE_INSN_CALL,
  43
  44   /* The instruction is a function return.  */
  45   BTRACE_INSN_RETURN,
  46
  47   /* The instruction is an unconditional jump.  */
  48   BTRACE_INSN_JUMP
  49 };
  50
  51 /* A branch trace instruction.
  52
  53    This represents a single instruction in a branch trace.  */
  54 struct btrace_insn
  55 {
  56   /* The address of this instruction.  */
  57   CORE_ADDR pc;
  58
  59   /* The size of this instruction in bytes.  */
  60   gdb_byte size;
  61
  62   /* The instruction class of this instruction.  */
  63   enum btrace_insn_class iclass;
  64 };
  65
  66 /* A vector of branch trace instructions.  */
  67 typedef struct btrace_insn btrace_insn_s;
  68 DEF_VEC_O (btrace_insn_s);
  69
  70 /* A doubly-linked list of branch trace function segments.  */
  71 struct btrace_func_link
  72 {
  73   struct btrace_function *prev;
  74   struct btrace_function *next;
  75 };
  76
  77 /* Flags for btrace function segments.  */
  78 enum btrace_function_flag
  79 {
  80   /* The 'up' link interpretation.
  81      If set, it points to the function segment we returned to.
  82      If clear, it points to the function segment we called from.  */
  83   BFUN_UP_LINKS_TO_RET = (1 << 0),
  84
  85   /* The 'up' link points to a tail call.  This obviously only makes sense
  86      if bfun_up_links_to_ret is clear.  */
  87   BFUN_UP_LINKS_TO_TAILCALL = (1 << 1)
  88 };
  89
  90 /* Decode errors for the BTS recording format.  */
  91 enum btrace_bts_error
  92 {
  93   /* The instruction trace overflowed the end of the trace block.  */
  94   BDE_BTS_OVERFLOW = 1,
  95
  96   /* The instruction size could not be determined.  */
  97   BDE_BTS_INSN_SIZE
  98 };
  99
 100 /* A branch trace function segment.
 101
 102    This represents a function segment in a branch trace, i.e. a consecutive
 103    number of instructions belonging to the same function.
 104
 105    In case of decode errors, we add an empty function segment to indicate
 106    the gap in the trace.
 107
 108    We do not allow function segments without instructions otherwise.  */
 109 struct btrace_function
 110 {
 111   /* The full and minimal symbol for the function.  Both may be NULL.  */
 112   struct minimal_symbol *msym;
 113   struct symbol *sym;
 114
 115   /* The previous and next segment belonging to the same function.
 116      If a function calls another function, the former will have at least
 117      two segments: one before the call and another after the return.  */
 118   struct btrace_func_link segment;
 119
 120   /* The previous and next function in control flow order.  */
 121   struct btrace_func_link flow;
 122
 123   /* The directly preceding function segment in a (fake) call stack.  */
 124   struct btrace_function *up;
 125
 126   /* The instructions in this function segment.
 127      The instruction vector will be empty if the function segment
 128      represents a decode error.  */
 129   VEC (btrace_insn_s) *insn;
 130
 131   /* The error code of a decode error that led to a gap.
 132      Must be zero unless INSN is empty; non-zero otherwise.  */
 133   int errcode;
 134
 135   /* The instruction number offset for the first instruction in this
 136      function segment.
 137      If INSN is empty this is the insn_offset of the succeding function
 138      segment in control-flow order.  */
 139   unsigned int insn_offset;
 140
 141   /* The function number in control-flow order.
 142      If INSN is empty indicating a gap in the trace due to a decode error,
 143      we still count the gap as a function.  */
 144   unsigned int number;
 145
 146   /* The function level in a back trace across the entire branch trace.
 147      A caller's level is one lower than the level of its callee.
 148
 149      Levels can be negative if we see returns for which we have not seen
 150      the corresponding calls.  The branch trace thread information provides
 151      a fixup to normalize function levels so the smallest level is zero.  */
 152   int level;
 153
 154   /* A bit-vector of btrace_function_flag.  */
 155   enum btrace_function_flag flags;
 156 };
 157
 158 /* A branch trace instruction iterator.  */
 159 struct btrace_insn_iterator
 160 {
 161   /* The branch trace function segment containing the instruction.
 162      Will never be NULL.  */
 163   const struct btrace_function *function;
 164
 165   /* The index into the function segment's instruction vector.  */
 166   unsigned int index;
 167 };
 168
 169 /* A branch trace function call iterator.  */
 170 struct btrace_call_iterator
 171 {
 172   /* The branch trace information for this thread.  Will never be NULL.  */
 173   const struct btrace_thread_info *btinfo;
 174
 175   /* The branch trace function segment.
 176      This will be NULL for the iterator pointing to the end of the trace.  */
 177   const struct btrace_function *function;
 178 };
 179
 180 /* Branch trace iteration state for "record instruction-history".  */
 181 struct btrace_insn_history
 182 {
 183   /* The branch trace instruction range from BEGIN (inclusive) to
 184      END (exclusive) that has been covered last time.  */
 185   struct btrace_insn_iterator begin;
 186   struct btrace_insn_iterator end;
 187 };
 188
 189 /* Branch trace iteration state for "record function-call-history".  */
 190 struct btrace_call_history
 191 {
 192   /* The branch trace function range from BEGIN (inclusive) to END (exclusive)
 193      that has been covered last time.  */
 194   struct btrace_call_iterator begin;
 195   struct btrace_call_iterator end;
 196 };
 197
 198 /* Branch trace thread flags.  */
 199 enum btrace_thread_flag
 200 {
 201   /* The thread is to be stepped forwards.  */
 202   BTHR_STEP = (1 << 0),
 203
 204   /* The thread is to be stepped backwards.  */
 205   BTHR_RSTEP = (1 << 1),
 206
 207   /* The thread is to be continued forwards.  */
 208   BTHR_CONT = (1 << 2),
 209
 210   /* The thread is to be continued backwards.  */
 211   BTHR_RCONT = (1 << 3),
 212
 213   /* The thread is to be moved.  */
 214   BTHR_MOVE = (BTHR_STEP | BTHR_RSTEP | BTHR_CONT | BTHR_RCONT)
 215 };
 216
 217 /* Branch trace information per thread.
 218
 219    This represents the branch trace configuration as well as the entry point
 220    into the branch trace data.  For the latter, it also contains the index into
 221    an array of branch trace blocks used for iterating though the branch trace
 222    blocks of a thread.  */
 223 struct btrace_thread_info
 224 {
 225   /* The target branch trace information for this thread.
 226
 227      This contains the branch trace configuration as well as any
 228      target-specific information necessary for implementing branch tracing on
 229      the underlying architecture.  */
 230   struct btrace_target_info *target;
 231
 232   /* The current branch trace for this thread (both inclusive).
 233
 234      The last instruction of END is the current instruction, which is not
 235      part of the execution history.
 236      Both will be NULL if there is no branch trace available.  If there is
 237      branch trace available, both will be non-NULL.  */
 238   struct btrace_function *begin;
 239   struct btrace_function *end;
 240
 241   /* The function level offset.  When added to each function's LEVEL,
 242      this normalizes the function levels such that the smallest level
 243      becomes zero.  */
 244   int level;
 245
 246   /* The number of gaps in the trace.  */
 247   unsigned int ngaps;
 248
 249   /* A bit-vector of btrace_thread_flag.  */
 250   enum btrace_thread_flag flags;
 251
 252   /* The instruction history iterator.  */
 253   struct btrace_insn_history *insn_history;
 254
 255   /* The function call history iterator.  */
 256   struct btrace_call_history *call_history;
 257
 258   /* The current replay position.  NULL if not replaying.
 259      Gaps are skipped during replay, so REPLAY always points to a valid
 260      instruction.  */
 261   struct btrace_insn_iterator *replay;
 262
 263   /* Why the thread stopped, if we need to track it.  */
 264   enum target_stop_reason stop_reason;
 265 };
 266
 267 /* Enable branch tracing for a thread.  */
 268 extern void btrace_enable (struct thread_info *tp,
 269                            const struct btrace_config *conf);
 270
 271 /* Get the branch trace configuration for a thread.
 272    Return NULL if branch tracing is not enabled for that thread.  */
 273 extern const struct btrace_config *
 274   btrace_conf (const struct btrace_thread_info *);
 275
 276 /* Disable branch tracing for a thread.
 277    This will also delete the current branch trace data.  */
 278 extern void btrace_disable (struct thread_info *);
 279
 280 /* Disable branch tracing for a thread during teardown.
 281    This is similar to btrace_disable, except that it will use
 282    target_teardown_btrace instead of target_disable_btrace.  */
 283 extern void btrace_teardown (struct thread_info *);
 284
 285 /* Fetch the branch trace for a single thread.  */
 286 extern void btrace_fetch (struct thread_info *);
 287
 288 /* Clear the branch trace for a single thread.  */
 289 extern void btrace_clear (struct thread_info *);
 290
 291 /* Clear the branch trace for all threads when an object file goes away.  */
 292 extern void btrace_free_objfile (struct objfile *);
 293
 294 /* Parse a branch trace xml document XML into DATA.  */
 295 extern void parse_xml_btrace (struct btrace_data *data, const char *xml);
 296
 297 /* Parse a branch trace configuration xml document XML into CONF.  */
 298 extern void parse_xml_btrace_conf (struct btrace_config *conf, const char *xml);
 299
 300 /* Dereference a branch trace instruction iterator.  Return a pointer to the
 301    instruction the iterator points to.
 302    May return NULL if the iterator points to a gap in the trace.  */
 303 extern const struct btrace_insn *
 304   btrace_insn_get (const struct btrace_insn_iterator *);
 305
 306 /* Return the instruction number for a branch trace iterator.
 307    Returns one past the maximum instruction number for the end iterator.
 308    Returns zero if the iterator does not point to a valid instruction.  */
 309 extern unsigned int btrace_insn_number (const struct btrace_insn_iterator *);
 310
 311 /* Initialize a branch trace instruction iterator to point to the begin/end of
 312    the branch trace.  Throws an error if there is no branch trace.  */
 313 extern void btrace_insn_begin (struct btrace_insn_iterator *,
 314                                const struct btrace_thread_info *);
 315 extern void btrace_insn_end (struct btrace_insn_iterator *,
 316                              const struct btrace_thread_info *);
 317
 318 /* Increment/decrement a branch trace instruction iterator by at most STRIDE
 319    instructions.  Return the number of instructions by which the instruction
 320    iterator has been advanced.
 321    Returns zero, if the operation failed or STRIDE had been zero.  */
 322 extern unsigned int btrace_insn_next (struct btrace_insn_iterator *,
 323                                       unsigned int stride);
 324 extern unsigned int btrace_insn_prev (struct btrace_insn_iterator *,
 325                                       unsigned int stride);
 326
 327 /* Compare two branch trace instruction iterators.
 328    Return a negative number if LHS < RHS.
 329    Return zero if LHS == RHS.
 330    Return a positive number if LHS > RHS.  */
 331 extern int btrace_insn_cmp (const struct btrace_insn_iterator *lhs,
 332                             const struct btrace_insn_iterator *rhs);
 333
 334 /* Find an instruction in the function branch trace by its number.
 335    If the instruction is found, initialize the branch trace instruction
 336    iterator to point to this instruction and return non-zero.
 337    Return zero otherwise.  */
 338 extern int btrace_find_insn_by_number (struct btrace_insn_iterator *,
 339                                        const struct btrace_thread_info *,
 340                                        unsigned int number);
 341
 342 /* Dereference a branch trace call iterator.  Return a pointer to the
 343    function the iterator points to or NULL if the interator points past
 344    the end of the branch trace.  */
 345 extern const struct btrace_function *
 346   btrace_call_get (const struct btrace_call_iterator *);
 347
 348 /* Return the function number for a branch trace call iterator.
 349    Returns one past the maximum function number for the end iterator.
 350    Returns zero if the iterator does not point to a valid function.  */
 351 extern unsigned int btrace_call_number (const struct btrace_call_iterator *);
 352
 353 /* Initialize a branch trace call iterator to point to the begin/end of
 354    the branch trace.  Throws an error if there is no branch trace.  */
 355 extern void btrace_call_begin (struct btrace_call_iterator *,
 356                                const struct btrace_thread_info *);
 357 extern void btrace_call_end (struct btrace_call_iterator *,
 358                              const struct btrace_thread_info *);
 359
 360 /* Increment/decrement a branch trace call iterator by at most STRIDE function
 361    segments.  Return the number of function segments by which the call
 362    iterator has been advanced.
 363    Returns zero, if the operation failed or STRIDE had been zero.  */
 364 extern unsigned int btrace_call_next (struct btrace_call_iterator *,
 365                                       unsigned int stride);
 366 extern unsigned int btrace_call_prev (struct btrace_call_iterator *,
 367                                       unsigned int stride);
 368
 369 /* Compare two branch trace call iterators.
 370    Return a negative number if LHS < RHS.
 371    Return zero if LHS == RHS.
 372    Return a positive number if LHS > RHS.  */
 373 extern int btrace_call_cmp (const struct btrace_call_iterator *lhs,
 374                             const struct btrace_call_iterator *rhs);
 375
 376 /* Find a function in the function branch trace by its NUMBER.
 377    If the function is found, initialize the branch trace call
 378    iterator to point to this function and return non-zero.
 379    Return zero otherwise.  */
 380 extern int btrace_find_call_by_number (struct btrace_call_iterator *,
 381                                        const struct btrace_thread_info *,
 382                                        unsigned int number);
 383
 384 /* Set the branch trace instruction history from BEGIN (inclusive) to
 385    END (exclusive).  */
 386 extern void btrace_set_insn_history (struct btrace_thread_info *,
 387                                      const struct btrace_insn_iterator *begin,
 388                                      const struct btrace_insn_iterator *end);
 389
 390 /* Set the branch trace function call history from BEGIN (inclusive) to
 391    END (exclusive).  */
 392 extern void btrace_set_call_history (struct btrace_thread_info *,
 393                                      const struct btrace_call_iterator *begin,
 394                                      const struct btrace_call_iterator *end);
 395
 396 /* Determine if branch tracing is currently replaying TP.  */
 397 extern int btrace_is_replaying (struct thread_info *tp);
 398
 399 /* Return non-zero if the branch trace for TP is empty; zero otherwise.  */
 400 extern int btrace_is_empty (struct thread_info *tp);
 401
 402 /* Create a cleanup for DATA.  */
 403 extern struct cleanup *make_cleanup_btrace_data (struct btrace_data *data);
 404
 405 #endif /* BTRACE_H */