gdb/btrace.h

   1 /* Branch trace support for GDB, the GNU debugger.
   2
   3    Copyright (C) 2013-2014 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 branch trace instruction.
  35
  36    This represents a single instruction in a branch trace.  */
  37 struct btrace_insn
  38 {
  39   /* The address of this instruction.  */
  40   CORE_ADDR pc;
  41 };
  42
  43 /* A vector of branch trace instructions.  */
  44 typedef struct btrace_insn btrace_insn_s;
  45 DEF_VEC_O (btrace_insn_s);
  46
  47 /* A doubly-linked list of branch trace function segments.  */
  48 struct btrace_func_link
  49 {
  50   struct btrace_function *prev;
  51   struct btrace_function *next;
  52 };
  53
  54 /* Flags for btrace function segments.  */
  55 enum btrace_function_flag
  56 {
  57   /* The 'up' link interpretation.
  58      If set, it points to the function segment we returned to.
  59      If clear, it points to the function segment we called from.  */
  60   BFUN_UP_LINKS_TO_RET = (1 << 0),
  61
  62   /* The 'up' link points to a tail call.  This obviously only makes sense
  63      if bfun_up_links_to_ret is clear.  */
  64   BFUN_UP_LINKS_TO_TAILCALL = (1 << 1)
  65 };
  66
  67 /* A branch trace function segment.
  68
  69    This represents a function segment in a branch trace, i.e. a consecutive
  70    number of instructions belonging to the same function.
  71
  72    We do not allow function segments without any instructions.  */
  73 struct btrace_function
  74 {
  75   /* The full and minimal symbol for the function.  Both may be NULL.  */
  76   struct minimal_symbol *msym;
  77   struct symbol *sym;
  78
  79   /* The previous and next segment belonging to the same function.
  80      If a function calls another function, the former will have at least
  81      two segments: one before the call and another after the return.  */
  82   struct btrace_func_link segment;
  83
  84   /* The previous and next function in control flow order.  */
  85   struct btrace_func_link flow;
  86
  87   /* The directly preceding function segment in a (fake) call stack.  */
  88   struct btrace_function *up;
  89
  90   /* The instructions in this function segment.
  91      The instruction vector will never be empty.  */
  92   VEC (btrace_insn_s) *insn;
  93
  94   /* The instruction number offset for the first instruction in this
  95      function segment.  */
  96   unsigned int insn_offset;
  97
  98   /* The function number in control-flow order.  */
  99   unsigned int number;
 100
 101   /* The function level in a back trace across the entire branch trace.
 102      A caller's level is one lower than the level of its callee.
 103
 104      Levels can be negative if we see returns for which we have not seen
 105      the corresponding calls.  The branch trace thread information provides
 106      a fixup to normalize function levels so the smallest level is zero.  */
 107   int level;
 108
 109   /* The source line range of this function segment (both inclusive).  */
 110   int lbegin, lend;
 111
 112   /* A bit-vector of btrace_function_flag.  */
 113   enum btrace_function_flag flags;
 114 };
 115
 116 /* A branch trace instruction iterator.  */
 117 struct btrace_insn_iterator
 118 {
 119   /* The branch trace function segment containing the instruction.
 120      Will never be NULL.  */
 121   const struct btrace_function *function;
 122
 123   /* The index into the function segment's instruction vector.  */
 124   unsigned int index;
 125 };
 126
 127 /* A branch trace function call iterator.  */
 128 struct btrace_call_iterator
 129 {
 130   /* The branch trace information for this thread.  Will never be NULL.  */
 131   const struct btrace_thread_info *btinfo;
 132
 133   /* The branch trace function segment.
 134      This will be NULL for the iterator pointing to the end of the trace.  */
 135   const struct btrace_function *function;
 136 };
 137
 138 /* Branch trace iteration state for "record instruction-history".  */
 139 struct btrace_insn_history
 140 {
 141   /* The branch trace instruction range from BEGIN (inclusive) to
 142      END (exclusive) that has been covered last time.  */
 143   struct btrace_insn_iterator begin;
 144   struct btrace_insn_iterator end;
 145 };
 146
 147 /* Branch trace iteration state for "record function-call-history".  */
 148 struct btrace_call_history
 149 {
 150   /* The branch trace function range from BEGIN (inclusive) to END (exclusive)
 151      that has been covered last time.  */
 152   struct btrace_call_iterator begin;
 153   struct btrace_call_iterator end;
 154 };
 155
 156 /* Branch trace thread flags.  */
 157 enum btrace_thread_flag
 158 {
 159   /* The thread is to be stepped forwards.  */
 160   BTHR_STEP = (1 << 0),
 161
 162   /* The thread is to be stepped backwards.  */
 163   BTHR_RSTEP = (1 << 1),
 164
 165   /* The thread is to be continued forwards.  */
 166   BTHR_CONT = (1 << 2),
 167
 168   /* The thread is to be continued backwards.  */
 169   BTHR_RCONT = (1 << 3),
 170
 171   /* The thread is to be moved.  */
 172   BTHR_MOVE = (BTHR_STEP | BTHR_RSTEP | BTHR_CONT | BTHR_RCONT)
 173 };
 174
 175 /* Branch trace information per thread.
 176
 177    This represents the branch trace configuration as well as the entry point
 178    into the branch trace data.  For the latter, it also contains the index into
 179    an array of branch trace blocks used for iterating though the branch trace
 180    blocks of a thread.  */
 181 struct btrace_thread_info
 182 {
 183   /* The target branch trace information for this thread.
 184
 185      This contains the branch trace configuration as well as any
 186      target-specific information necessary for implementing branch tracing on
 187      the underlying architecture.  */
 188   struct btrace_target_info *target;
 189
 190   /* The current branch trace for this thread (both inclusive).
 191
 192      The last instruction of END is the current instruction, which is not
 193      part of the execution history.
 194      Both will be NULL if there is no branch trace available.  If there is
 195      branch trace available, both will be non-NULL.  */
 196   struct btrace_function *begin;
 197   struct btrace_function *end;
 198
 199   /* The function level offset.  When added to each function's LEVEL,
 200      this normalizes the function levels such that the smallest level
 201      becomes zero.  */
 202   int level;
 203
 204   /* A bit-vector of btrace_thread_flag.  */
 205   enum btrace_thread_flag flags;
 206
 207   /* The instruction history iterator.  */
 208   struct btrace_insn_history *insn_history;
 209
 210   /* The function call history iterator.  */
 211   struct btrace_call_history *call_history;
 212
 213   /* The current replay position.  NULL if not replaying.  */
 214   struct btrace_insn_iterator *replay;
 215 };
 216
 217 /* Enable branch tracing for a thread.  */
 218 extern void btrace_enable (struct thread_info *tp);
 219
 220 /* Disable branch tracing for a thread.
 221    This will also delete the current branch trace data.  */
 222 extern void btrace_disable (struct thread_info *);
 223
 224 /* Disable branch tracing for a thread during teardown.
 225    This is similar to btrace_disable, except that it will use
 226    target_teardown_btrace instead of target_disable_btrace.  */
 227 extern void btrace_teardown (struct thread_info *);
 228
 229 /* Fetch the branch trace for a single thread.  */
 230 extern void btrace_fetch (struct thread_info *);
 231
 232 /* Clear the branch trace for a single thread.  */
 233 extern void btrace_clear (struct thread_info *);
 234
 235 /* Clear the branch trace for all threads when an object file goes away.  */
 236 extern void btrace_free_objfile (struct objfile *);
 237
 238 /* Parse a branch trace xml document into a block vector.  */
 239 extern VEC (btrace_block_s) *parse_xml_btrace (const char*);
 240
 241 /* Dereference a branch trace instruction iterator.  Return a pointer to the
 242    instruction the iterator points to.  */
 243 extern const struct btrace_insn *
 244   btrace_insn_get (const struct btrace_insn_iterator *);
 245
 246 /* Return the instruction number for a branch trace iterator.
 247    Returns one past the maximum instruction number for the end iterator.
 248    Returns zero if the iterator does not point to a valid instruction.  */
 249 extern unsigned int btrace_insn_number (const struct btrace_insn_iterator *);
 250
 251 /* Initialize a branch trace instruction iterator to point to the begin/end of
 252    the branch trace.  Throws an error if there is no branch trace.  */
 253 extern void btrace_insn_begin (struct btrace_insn_iterator *,
 254                                const struct btrace_thread_info *);
 255 extern void btrace_insn_end (struct btrace_insn_iterator *,
 256                              const struct btrace_thread_info *);
 257
 258 /* Increment/decrement a branch trace instruction iterator by at most STRIDE
 259    instructions.  Return the number of instructions by which the instruction
 260    iterator has been advanced.
 261    Returns zero, if the operation failed or STRIDE had been zero.  */
 262 extern unsigned int btrace_insn_next (struct btrace_insn_iterator *,
 263                                       unsigned int stride);
 264 extern unsigned int btrace_insn_prev (struct btrace_insn_iterator *,
 265                                       unsigned int stride);
 266
 267 /* Compare two branch trace instruction iterators.
 268    Return a negative number if LHS < RHS.
 269    Return zero if LHS == RHS.
 270    Return a positive number if LHS > RHS.  */
 271 extern int btrace_insn_cmp (const struct btrace_insn_iterator *lhs,
 272                             const struct btrace_insn_iterator *rhs);
 273
 274 /* Find an instruction in the function branch trace by its number.
 275    If the instruction is found, initialize the branch trace instruction
 276    iterator to point to this instruction and return non-zero.
 277    Return zero otherwise.  */
 278 extern int btrace_find_insn_by_number (struct btrace_insn_iterator *,
 279                                        const struct btrace_thread_info *,
 280                                        unsigned int number);
 281
 282 /* Dereference a branch trace call iterator.  Return a pointer to the
 283    function the iterator points to or NULL if the interator points past
 284    the end of the branch trace.  */
 285 extern const struct btrace_function *
 286   btrace_call_get (const struct btrace_call_iterator *);
 287
 288 /* Return the function number for a branch trace call iterator.
 289    Returns one past the maximum function number for the end iterator.
 290    Returns zero if the iterator does not point to a valid function.  */
 291 extern unsigned int btrace_call_number (const struct btrace_call_iterator *);
 292
 293 /* Initialize a branch trace call iterator to point to the begin/end of
 294    the branch trace.  Throws an error if there is no branch trace.  */
 295 extern void btrace_call_begin (struct btrace_call_iterator *,
 296                                const struct btrace_thread_info *);
 297 extern void btrace_call_end (struct btrace_call_iterator *,
 298                              const struct btrace_thread_info *);
 299
 300 /* Increment/decrement a branch trace call iterator by at most STRIDE function
 301    segments.  Return the number of function segments by which the call
 302    iterator has been advanced.
 303    Returns zero, if the operation failed or STRIDE had been zero.  */
 304 extern unsigned int btrace_call_next (struct btrace_call_iterator *,
 305                                       unsigned int stride);
 306 extern unsigned int btrace_call_prev (struct btrace_call_iterator *,
 307                                       unsigned int stride);
 308
 309 /* Compare two branch trace call iterators.
 310    Return a negative number if LHS < RHS.
 311    Return zero if LHS == RHS.
 312    Return a positive number if LHS > RHS.  */
 313 extern int btrace_call_cmp (const struct btrace_call_iterator *lhs,
 314                             const struct btrace_call_iterator *rhs);
 315
 316 /* Find a function in the function branch trace by its NUMBER.
 317    If the function is found, initialize the branch trace call
 318    iterator to point to this function and return non-zero.
 319    Return zero otherwise.  */
 320 extern int btrace_find_call_by_number (struct btrace_call_iterator *,
 321                                        const struct btrace_thread_info *,
 322                                        unsigned int number);
 323
 324 /* Set the branch trace instruction history from BEGIN (inclusive) to
 325    END (exclusive).  */
 326 extern void btrace_set_insn_history (struct btrace_thread_info *,
 327                                      const struct btrace_insn_iterator *begin,
 328                                      const struct btrace_insn_iterator *end);
 329
 330 /* Set the branch trace function call history from BEGIN (inclusive) to
 331    END (exclusive).  */
 332 extern void btrace_set_call_history (struct btrace_thread_info *,
 333                                      const struct btrace_call_iterator *begin,
 334                                      const struct btrace_call_iterator *end);
 335
 336 /* Determine if branch tracing is currently replaying TP.  */
 337 extern int btrace_is_replaying (struct thread_info *tp);
 338
 339 /* Return non-zero if the branch trace for TP is empty; zero otherwise.  */
 340 extern int btrace_is_empty (struct thread_info *tp);
 341
 342
 343 #endif /* BTRACE_H */