1 /* Branch trace support for GDB, the GNU debugger.
3 Copyright (C) 2013-2017 Free Software Foundation, Inc.
5 Contributed by Intel Corp. <markus.t.metzger@intel.com>.
7 This file is part of GDB.
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.
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.
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/>. */
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. */
29 #include "btrace-common.h"
30 #include "target/waitstatus.h" /* For enum target_stop_reason. */
31 #include "common/enum-flags.h"
33 #if defined (HAVE_LIBIPT)
34 # include <intel-pt.h>
40 struct btrace_function;
42 /* A coarse instruction classification. */
43 enum btrace_insn_class
45 /* The instruction is something not listed below. */
48 /* The instruction is a function call. */
51 /* The instruction is a function return. */
54 /* The instruction is an unconditional jump. */
58 /* Instruction flags. */
61 /* The instruction has been executed speculatively. */
62 BTRACE_INSN_FLAG_SPECULATIVE = (1 << 0)
64 DEF_ENUM_FLAGS_TYPE (enum btrace_insn_flag, btrace_insn_flags);
66 /* A branch trace instruction.
68 This represents a single instruction in a branch trace. */
71 /* The address of this instruction. */
74 /* The size of this instruction in bytes. */
77 /* The instruction class of this instruction. */
78 enum btrace_insn_class iclass;
80 /* A bit vector of BTRACE_INSN_FLAGS. */
81 btrace_insn_flags flags;
84 /* A vector of branch trace instructions. */
85 typedef struct btrace_insn btrace_insn_s;
86 DEF_VEC_O (btrace_insn_s);
88 /* A doubly-linked list of branch trace function segments. */
89 struct btrace_func_link
91 struct btrace_function *prev;
92 struct btrace_function *next;
95 /* Flags for btrace function segments. */
96 enum btrace_function_flag
98 /* The 'up' link interpretation.
99 If set, it points to the function segment we returned to.
100 If clear, it points to the function segment we called from. */
101 BFUN_UP_LINKS_TO_RET = (1 << 0),
103 /* The 'up' link points to a tail call. This obviously only makes sense
104 if bfun_up_links_to_ret is clear. */
105 BFUN_UP_LINKS_TO_TAILCALL = (1 << 1)
107 DEF_ENUM_FLAGS_TYPE (enum btrace_function_flag, btrace_function_flags);
109 /* Decode errors for the BTS recording format. */
110 enum btrace_bts_error
112 /* The instruction trace overflowed the end of the trace block. */
113 BDE_BTS_OVERFLOW = 1,
115 /* The instruction size could not be determined. */
119 /* Decode errors for the Intel Processor Trace recording format. */
122 /* The user cancelled trace processing. */
123 BDE_PT_USER_QUIT = 1,
125 /* Tracing was temporarily disabled. */
128 /* Trace recording overflowed. */
131 /* Negative numbers are used by the decoder library. */
134 /* A branch trace function segment.
136 This represents a function segment in a branch trace, i.e. a consecutive
137 number of instructions belonging to the same function.
139 In case of decode errors, we add an empty function segment to indicate
140 the gap in the trace.
142 We do not allow function segments without instructions otherwise. */
143 struct btrace_function
145 /* The full and minimal symbol for the function. Both may be NULL. */
146 struct minimal_symbol *msym;
149 /* The previous and next segment belonging to the same function.
150 If a function calls another function, the former will have at least
151 two segments: one before the call and another after the return. */
152 struct btrace_func_link segment;
154 /* The previous and next function in control flow order. */
155 struct btrace_func_link flow;
157 /* The function segment number of the directly preceding function segment in
158 a (fake) call stack. Will be zero if there is no such function segment in
162 /* The instructions in this function segment.
163 The instruction vector will be empty if the function segment
164 represents a decode error. */
165 VEC (btrace_insn_s) *insn;
167 /* The error code of a decode error that led to a gap.
168 Must be zero unless INSN is empty; non-zero otherwise. */
171 /* The instruction number offset for the first instruction in this
173 If INSN is empty this is the insn_offset of the succeding function
174 segment in control-flow order. */
175 unsigned int insn_offset;
177 /* The 1-based function number in control-flow order.
178 If INSN is empty indicating a gap in the trace due to a decode error,
179 we still count the gap as a function. */
182 /* The function level in a back trace across the entire branch trace.
183 A caller's level is one lower than the level of its callee.
185 Levels can be negative if we see returns for which we have not seen
186 the corresponding calls. The branch trace thread information provides
187 a fixup to normalize function levels so the smallest level is zero. */
190 /* A bit-vector of btrace_function_flag. */
191 btrace_function_flags flags;
194 /* A branch trace instruction iterator. */
195 struct btrace_insn_iterator
197 /* The branch trace information for this thread. Will never be NULL. */
198 const struct btrace_thread_info *btinfo;
200 /* The index of the function segment in BTINFO->FUNCTIONS. */
201 unsigned int call_index;
203 /* The index into the function segment's instruction vector. */
204 unsigned int insn_index;
207 /* A branch trace function call iterator. */
208 struct btrace_call_iterator
210 /* The branch trace information for this thread. Will never be NULL. */
211 const struct btrace_thread_info *btinfo;
213 /* The index of the function segment in BTINFO->FUNCTIONS. */
217 /* Branch trace iteration state for "record instruction-history". */
218 struct btrace_insn_history
220 /* The branch trace instruction range from BEGIN (inclusive) to
221 END (exclusive) that has been covered last time. */
222 struct btrace_insn_iterator begin;
223 struct btrace_insn_iterator end;
226 /* Branch trace iteration state for "record function-call-history". */
227 struct btrace_call_history
229 /* The branch trace function range from BEGIN (inclusive) to END (exclusive)
230 that has been covered last time. */
231 struct btrace_call_iterator begin;
232 struct btrace_call_iterator end;
235 /* Branch trace thread flags. */
236 enum btrace_thread_flag
238 /* The thread is to be stepped forwards. */
239 BTHR_STEP = (1 << 0),
241 /* The thread is to be stepped backwards. */
242 BTHR_RSTEP = (1 << 1),
244 /* The thread is to be continued forwards. */
245 BTHR_CONT = (1 << 2),
247 /* The thread is to be continued backwards. */
248 BTHR_RCONT = (1 << 3),
250 /* The thread is to be moved. */
251 BTHR_MOVE = (BTHR_STEP | BTHR_RSTEP | BTHR_CONT | BTHR_RCONT),
253 /* The thread is to be stopped. */
256 DEF_ENUM_FLAGS_TYPE (enum btrace_thread_flag, btrace_thread_flags);
258 #if defined (HAVE_LIBIPT)
260 struct btrace_pt_packet
262 /* The offset in the trace stream. */
265 /* The decode error code. */
266 enum pt_error_code errcode;
268 /* The decoded packet. Only valid if ERRCODE == pte_ok. */
269 struct pt_packet packet;
272 /* Define functions operating on a vector of packets. */
273 typedef struct btrace_pt_packet btrace_pt_packet_s;
274 DEF_VEC_O (btrace_pt_packet_s);
275 #endif /* defined (HAVE_LIBIPT) */
277 /* Branch trace iteration state for "maintenance btrace packet-history". */
278 struct btrace_maint_packet_history
280 /* The branch trace packet range from BEGIN (inclusive) to
281 END (exclusive) that has been covered last time. */
286 /* Branch trace maintenance information per thread.
288 This information is used by "maintenance btrace" commands. */
289 struct btrace_maint_info
291 /* Most information is format-specific.
292 The format can be found in the BTRACE.DATA.FORMAT field of each thread. */
295 /* BTRACE.DATA.FORMAT == BTRACE_FORMAT_BTS */
298 /* The packet history iterator.
299 We are iterating over BTRACE.DATA.FORMAT.VARIANT.BTS.BLOCKS. */
300 struct btrace_maint_packet_history packet_history;
303 #if defined (HAVE_LIBIPT)
304 /* BTRACE.DATA.FORMAT == BTRACE_FORMAT_PT */
307 /* A vector of decoded packets. */
308 VEC (btrace_pt_packet_s) *packets;
310 /* The packet history iterator.
311 We are iterating over the above PACKETS vector. */
312 struct btrace_maint_packet_history packet_history;
314 #endif /* defined (HAVE_LIBIPT) */
318 /* Branch trace information per thread.
320 This represents the branch trace configuration as well as the entry point
321 into the branch trace data. For the latter, it also contains the index into
322 an array of branch trace blocks used for iterating though the branch trace
323 blocks of a thread. */
324 struct btrace_thread_info
326 /* The target branch trace information for this thread.
328 This contains the branch trace configuration as well as any
329 target-specific information necessary for implementing branch tracing on
330 the underlying architecture. */
331 struct btrace_target_info *target;
333 /* The raw branch trace data for the below branch trace. */
334 struct btrace_data data;
336 /* Vector of pointer to decoded function segments in execution flow order.
337 Note that the numbering for btrace function segments starts with 1, so
338 function segment i will be at index (i - 1). */
339 std::vector<btrace_function *> functions;
341 /* The function level offset. When added to each function's LEVEL,
342 this normalizes the function levels such that the smallest level
346 /* The number of gaps in the trace. */
349 /* A bit-vector of btrace_thread_flag. */
350 btrace_thread_flags flags;
352 /* The instruction history iterator. */
353 struct btrace_insn_history *insn_history;
355 /* The function call history iterator. */
356 struct btrace_call_history *call_history;
358 /* The current replay position. NULL if not replaying.
359 Gaps are skipped during replay, so REPLAY always points to a valid
361 struct btrace_insn_iterator *replay;
363 /* Why the thread stopped, if we need to track it. */
364 enum target_stop_reason stop_reason;
366 /* Maintenance information. */
367 struct btrace_maint_info maint;
370 /* Enable branch tracing for a thread. */
371 extern void btrace_enable (struct thread_info *tp,
372 const struct btrace_config *conf);
374 /* Get the branch trace configuration for a thread.
375 Return NULL if branch tracing is not enabled for that thread. */
376 extern const struct btrace_config *
377 btrace_conf (const struct btrace_thread_info *);
379 /* Disable branch tracing for a thread.
380 This will also delete the current branch trace data. */
381 extern void btrace_disable (struct thread_info *);
383 /* Disable branch tracing for a thread during teardown.
384 This is similar to btrace_disable, except that it will use
385 target_teardown_btrace instead of target_disable_btrace. */
386 extern void btrace_teardown (struct thread_info *);
388 /* Return a human readable error string for the given ERRCODE in FORMAT.
389 The pointer will never be NULL and must not be freed. */
391 extern const char *btrace_decode_error (enum btrace_format format, int errcode);
393 /* Fetch the branch trace for a single thread. */
394 extern void btrace_fetch (struct thread_info *);
396 /* Clear the branch trace for a single thread. */
397 extern void btrace_clear (struct thread_info *);
399 /* Clear the branch trace for all threads when an object file goes away. */
400 extern void btrace_free_objfile (struct objfile *);
402 /* Parse a branch trace xml document XML into DATA. */
403 extern void parse_xml_btrace (struct btrace_data *data, const char *xml);
405 /* Parse a branch trace configuration xml document XML into CONF. */
406 extern void parse_xml_btrace_conf (struct btrace_config *conf, const char *xml);
408 /* Dereference a branch trace instruction iterator. Return a pointer to the
409 instruction the iterator points to.
410 May return NULL if the iterator points to a gap in the trace. */
411 extern const struct btrace_insn *
412 btrace_insn_get (const struct btrace_insn_iterator *);
414 /* Return the error code for a branch trace instruction iterator. Returns zero
415 if there is no error, i.e. the instruction is valid. */
416 extern int btrace_insn_get_error (const struct btrace_insn_iterator *);
418 /* Return the instruction number for a branch trace iterator.
419 Returns one past the maximum instruction number for the end iterator. */
420 extern unsigned int btrace_insn_number (const struct btrace_insn_iterator *);
422 /* Initialize a branch trace instruction iterator to point to the begin/end of
423 the branch trace. Throws an error if there is no branch trace. */
424 extern void btrace_insn_begin (struct btrace_insn_iterator *,
425 const struct btrace_thread_info *);
426 extern void btrace_insn_end (struct btrace_insn_iterator *,
427 const struct btrace_thread_info *);
429 /* Increment/decrement a branch trace instruction iterator by at most STRIDE
430 instructions. Return the number of instructions by which the instruction
431 iterator has been advanced.
432 Returns zero, if the operation failed or STRIDE had been zero. */
433 extern unsigned int btrace_insn_next (struct btrace_insn_iterator *,
434 unsigned int stride);
435 extern unsigned int btrace_insn_prev (struct btrace_insn_iterator *,
436 unsigned int stride);
438 /* Compare two branch trace instruction iterators.
439 Return a negative number if LHS < RHS.
440 Return zero if LHS == RHS.
441 Return a positive number if LHS > RHS. */
442 extern int btrace_insn_cmp (const struct btrace_insn_iterator *lhs,
443 const struct btrace_insn_iterator *rhs);
445 /* Find an instruction or gap in the function branch trace by its number.
446 If the instruction is found, initialize the branch trace instruction
447 iterator to point to this instruction and return non-zero.
448 Return zero otherwise. */
449 extern int btrace_find_insn_by_number (struct btrace_insn_iterator *,
450 const struct btrace_thread_info *,
451 unsigned int number);
453 /* Dereference a branch trace call iterator. Return a pointer to the
454 function the iterator points to or NULL if the interator points past
455 the end of the branch trace. */
456 extern const struct btrace_function *
457 btrace_call_get (const struct btrace_call_iterator *);
459 /* Return the function number for a branch trace call iterator.
460 Returns one past the maximum function number for the end iterator.
461 Returns zero if the iterator does not point to a valid function. */
462 extern unsigned int btrace_call_number (const struct btrace_call_iterator *);
464 /* Initialize a branch trace call iterator to point to the begin/end of
465 the branch trace. Throws an error if there is no branch trace. */
466 extern void btrace_call_begin (struct btrace_call_iterator *,
467 const struct btrace_thread_info *);
468 extern void btrace_call_end (struct btrace_call_iterator *,
469 const struct btrace_thread_info *);
471 /* Increment/decrement a branch trace call iterator by at most STRIDE function
472 segments. Return the number of function segments by which the call
473 iterator has been advanced.
474 Returns zero, if the operation failed or STRIDE had been zero. */
475 extern unsigned int btrace_call_next (struct btrace_call_iterator *,
476 unsigned int stride);
477 extern unsigned int btrace_call_prev (struct btrace_call_iterator *,
478 unsigned int stride);
480 /* Compare two branch trace call iterators.
481 Return a negative number if LHS < RHS.
482 Return zero if LHS == RHS.
483 Return a positive number if LHS > RHS. */
484 extern int btrace_call_cmp (const struct btrace_call_iterator *lhs,
485 const struct btrace_call_iterator *rhs);
487 /* Find a function in the function branch trace by its NUMBER.
488 If the function is found, initialize the branch trace call
489 iterator to point to this function and return non-zero.
490 Return zero otherwise. */
491 extern int btrace_find_call_by_number (struct btrace_call_iterator *,
492 const struct btrace_thread_info *,
493 unsigned int number);
495 /* Set the branch trace instruction history from BEGIN (inclusive) to
497 extern void btrace_set_insn_history (struct btrace_thread_info *,
498 const struct btrace_insn_iterator *begin,
499 const struct btrace_insn_iterator *end);
501 /* Set the branch trace function call history from BEGIN (inclusive) to
503 extern void btrace_set_call_history (struct btrace_thread_info *,
504 const struct btrace_call_iterator *begin,
505 const struct btrace_call_iterator *end);
507 /* Determine if branch tracing is currently replaying TP. */
508 extern int btrace_is_replaying (struct thread_info *tp);
510 /* Return non-zero if the branch trace for TP is empty; zero otherwise. */
511 extern int btrace_is_empty (struct thread_info *tp);
513 /* Create a cleanup for DATA. */
514 extern struct cleanup *make_cleanup_btrace_data (struct btrace_data *data);
516 #endif /* BTRACE_H */