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