/* Control whether to skip PAD packets when computing the packet history. */
static int maint_btrace_pt_skip_pad = 1;
+/* A vector of function segments. */
+typedef struct btrace_function * bfun_s;
+DEF_VEC_P (bfun_s);
+
static void btrace_add_pc (struct thread_info *tp);
/* Print a record debug message. Use do ... while (0) to avoid ambiguities
bfun->flags = flags;
ftrace_debug (bfun, "set caller");
+ ftrace_debug (caller, "..to");
}
/* Fix up the caller for all segments of a function. */
return bfun;
}
+/* Return the caller of BFUN or NULL if there is none. This function skips
+ tail calls in the call chain. */
+static struct btrace_function *
+ftrace_get_caller (struct btrace_function *bfun)
+{
+ for (; bfun != NULL; bfun = bfun->up)
+ if ((bfun->flags & BFUN_UP_LINKS_TO_TAILCALL) == 0)
+ return bfun->up;
+
+ return NULL;
+}
+
/* Find the innermost caller in the back trace of BFUN with MFUN/FUN
symbol information. */
return iclass;
}
+/* Try to match the back trace at LHS to the back trace at RHS. Returns the
+ number of matching function segments or zero if the back traces do not
+ match. */
+
+static int
+ftrace_match_backtrace (struct btrace_function *lhs,
+ struct btrace_function *rhs)
+{
+ int matches;
+
+ for (matches = 0; lhs != NULL && rhs != NULL; ++matches)
+ {
+ if (ftrace_function_switched (lhs, rhs->msym, rhs->sym))
+ return 0;
+
+ lhs = ftrace_get_caller (lhs);
+ rhs = ftrace_get_caller (rhs);
+ }
+
+ return matches;
+}
+
+/* Add ADJUSTMENT to the level of BFUN and succeeding function segments. */
+
+static void
+ftrace_fixup_level (struct btrace_function *bfun, int adjustment)
+{
+ if (adjustment == 0)
+ return;
+
+ DEBUG_FTRACE ("fixup level (%+d)", adjustment);
+ ftrace_debug (bfun, "..bfun");
+
+ for (; bfun != NULL; bfun = bfun->flow.next)
+ bfun->level += adjustment;
+}
+
+/* Recompute the global level offset. Traverse the function trace and compute
+ the global level offset as the negative of the minimal function level. */
+
+static void
+ftrace_compute_global_level_offset (struct btrace_thread_info *btinfo)
+{
+ struct btrace_function *bfun, *end;
+ int level;
+
+ if (btinfo == NULL)
+ return;
+
+ bfun = btinfo->begin;
+ if (bfun == NULL)
+ return;
+
+ /* The last function segment contains the current instruction, which is not
+ really part of the trace. If it contains just this one instruction, we
+ stop when we reach it; otherwise, we let the below loop run to the end. */
+ end = btinfo->end;
+ if (VEC_length (btrace_insn_s, end->insn) > 1)
+ end = NULL;
+
+ level = INT_MAX;
+ for (; bfun != end; bfun = bfun->flow.next)
+ level = std::min (level, bfun->level);
+
+ DEBUG_FTRACE ("setting global level offset: %d", -level);
+ btinfo->level = -level;
+}
+
+/* Connect the function segments PREV and NEXT in a bottom-to-top walk as in
+ ftrace_connect_backtrace. */
+
+static void
+ftrace_connect_bfun (struct btrace_function *prev,
+ struct btrace_function *next)
+{
+ DEBUG_FTRACE ("connecting...");
+ ftrace_debug (prev, "..prev");
+ ftrace_debug (next, "..next");
+
+ /* The function segments are not yet connected. */
+ gdb_assert (prev->segment.next == NULL);
+ gdb_assert (next->segment.prev == NULL);
+
+ prev->segment.next = next;
+ next->segment.prev = prev;
+
+ /* We may have moved NEXT to a different function level. */
+ ftrace_fixup_level (next, prev->level - next->level);
+
+ /* If we run out of back trace for one, let's use the other's. */
+ if (prev->up == NULL)
+ {
+ if (next->up != NULL)
+ {
+ DEBUG_FTRACE ("using next's callers");
+ ftrace_fixup_caller (prev, next->up, next->flags);
+ }
+ }
+ else if (next->up == NULL)
+ {
+ if (prev->up != NULL)
+ {
+ DEBUG_FTRACE ("using prev's callers");
+ ftrace_fixup_caller (next, prev->up, prev->flags);
+ }
+ }
+ else
+ {
+ /* PREV may have a tailcall caller, NEXT can't. If it does, fixup the up
+ link to add the tail callers to NEXT's back trace.
+
+ This removes NEXT->UP from NEXT's back trace. It will be added back
+ when connecting NEXT and PREV's callers - provided they exist.
+
+ If PREV's back trace consists of a series of tail calls without an
+ actual call, there will be no further connection and NEXT's caller will
+ be removed for good. To catch this case, we handle it here and connect
+ the top of PREV's back trace to NEXT's caller. */
+ if ((prev->flags & BFUN_UP_LINKS_TO_TAILCALL) != 0)
+ {
+ struct btrace_function *caller;
+ btrace_function_flags flags;
+
+ /* We checked NEXT->UP above so CALLER can't be NULL. */
+ caller = next->up;
+ flags = next->flags;
+
+ DEBUG_FTRACE ("adding prev's tail calls to next");
+
+ ftrace_fixup_caller (next, prev->up, prev->flags);
+
+ for (prev = prev->up; prev != NULL; prev = prev->up)
+ {
+ /* At the end of PREV's back trace, continue with CALLER. */
+ if (prev->up == NULL)
+ {
+ DEBUG_FTRACE ("fixing up link for tailcall chain");
+ ftrace_debug (prev, "..top");
+ ftrace_debug (caller, "..up");
+
+ ftrace_fixup_caller (prev, caller, flags);
+
+ /* If we skipped any tail calls, this may move CALLER to a
+ different function level.
+
+ Note that changing CALLER's level is only OK because we
+ know that this is the last iteration of the bottom-to-top
+ walk in ftrace_connect_backtrace.
+
+ Otherwise we will fix up CALLER's level when we connect it
+ to PREV's caller in the next iteration. */
+ ftrace_fixup_level (caller, prev->level - caller->level - 1);
+ break;
+ }
+
+ /* There's nothing to do if we find a real call. */
+ if ((prev->flags & BFUN_UP_LINKS_TO_TAILCALL) == 0)
+ {
+ DEBUG_FTRACE ("will fix up link in next iteration");
+ break;
+ }
+ }
+ }
+ }
+}
+
+/* Connect function segments on the same level in the back trace at LHS and RHS.
+ The back traces at LHS and RHS are expected to match according to
+ ftrace_match_backtrace. */
+
+static void
+ftrace_connect_backtrace (struct btrace_function *lhs,
+ struct btrace_function *rhs)
+{
+ while (lhs != NULL && rhs != NULL)
+ {
+ struct btrace_function *prev, *next;
+
+ gdb_assert (!ftrace_function_switched (lhs, rhs->msym, rhs->sym));
+
+ /* Connecting LHS and RHS may change the up link. */
+ prev = lhs;
+ next = rhs;
+
+ lhs = ftrace_get_caller (lhs);
+ rhs = ftrace_get_caller (rhs);
+
+ ftrace_connect_bfun (prev, next);
+ }
+}
+
+/* Bridge the gap between two function segments left and right of a gap if their
+ respective back traces match in at least MIN_MATCHES functions.
+
+ Returns non-zero if the gap could be bridged, zero otherwise. */
+
+static int
+ftrace_bridge_gap (struct btrace_function *lhs, struct btrace_function *rhs,
+ int min_matches)
+{
+ struct btrace_function *best_l, *best_r, *cand_l, *cand_r;
+ int best_matches;
+
+ DEBUG_FTRACE ("checking gap at insn %u (req matches: %d)",
+ rhs->insn_offset - 1, min_matches);
+
+ best_matches = 0;
+ best_l = NULL;
+ best_r = NULL;
+
+ /* We search the back traces of LHS and RHS for valid connections and connect
+ the two functon segments that give the longest combined back trace. */
+
+ for (cand_l = lhs; cand_l != NULL; cand_l = ftrace_get_caller (cand_l))
+ for (cand_r = rhs; cand_r != NULL; cand_r = ftrace_get_caller (cand_r))
+ {
+ int matches;
+
+ matches = ftrace_match_backtrace (cand_l, cand_r);
+ if (best_matches < matches)
+ {
+ best_matches = matches;
+ best_l = cand_l;
+ best_r = cand_r;
+ }
+ }
+
+ /* We need at least MIN_MATCHES matches. */
+ gdb_assert (min_matches > 0);
+ if (best_matches < min_matches)
+ return 0;
+
+ DEBUG_FTRACE ("..matches: %d", best_matches);
+
+ /* We will fix up the level of BEST_R and succeeding function segments such
+ that BEST_R's level matches BEST_L's when we connect BEST_L to BEST_R.
+
+ This will ignore the level of RHS and following if BEST_R != RHS. I.e. if
+ BEST_R is a successor of RHS in the back trace of RHS (phases 1 and 3).
+
+ To catch this, we already fix up the level here where we can start at RHS
+ instead of at BEST_R. We will ignore the level fixup when connecting
+ BEST_L to BEST_R as they will already be on the same level. */
+ ftrace_fixup_level (rhs, best_l->level - best_r->level);
+
+ ftrace_connect_backtrace (best_l, best_r);
+
+ return best_matches;
+}
+
+/* Try to bridge gaps due to overflow or decode errors by connecting the
+ function segments that are separated by the gap. */
+
+static void
+btrace_bridge_gaps (struct thread_info *tp, VEC (bfun_s) **gaps)
+{
+ VEC (bfun_s) *remaining;
+ struct cleanup *old_chain;
+ int min_matches;
+
+ DEBUG ("bridge gaps");
+
+ remaining = NULL;
+ old_chain = make_cleanup (VEC_cleanup (bfun_s), &remaining);
+
+ /* We require a minimum amount of matches for bridging a gap. The number of
+ required matches will be lowered with each iteration.
+
+ The more matches the higher our confidence that the bridging is correct.
+ For big gaps or small traces, however, it may not be feasible to require a
+ high number of matches. */
+ for (min_matches = 5; min_matches > 0; --min_matches)
+ {
+ /* Let's try to bridge as many gaps as we can. In some cases, we need to
+ skip a gap and revisit it again after we closed later gaps. */
+ while (!VEC_empty (bfun_s, *gaps))
+ {
+ struct btrace_function *gap;
+ unsigned int idx;
+
+ for (idx = 0; VEC_iterate (bfun_s, *gaps, idx, gap); ++idx)
+ {
+ struct btrace_function *lhs, *rhs;
+ int bridged;
+
+ /* We may have a sequence of gaps if we run from one error into
+ the next as we try to re-sync onto the trace stream. Ignore
+ all but the leftmost gap in such a sequence.
+
+ Also ignore gaps at the beginning of the trace. */
+ lhs = gap->flow.prev;
+ if (lhs == NULL || lhs->errcode != 0)
+ continue;
+
+ /* Skip gaps to the right. */
+ for (rhs = gap->flow.next; rhs != NULL; rhs = rhs->flow.next)
+ if (rhs->errcode == 0)
+ break;
+
+ /* Ignore gaps at the end of the trace. */
+ if (rhs == NULL)
+ continue;
+
+ bridged = ftrace_bridge_gap (lhs, rhs, min_matches);
+
+ /* Keep track of gaps we were not able to bridge and try again.
+ If we just pushed them to the end of GAPS we would risk an
+ infinite loop in case we simply cannot bridge a gap. */
+ if (bridged == 0)
+ VEC_safe_push (bfun_s, remaining, gap);
+ }
+
+ /* Let's see if we made any progress. */
+ if (VEC_length (bfun_s, remaining) == VEC_length (bfun_s, *gaps))
+ break;
+
+ VEC_free (bfun_s, *gaps);
+
+ *gaps = remaining;
+ remaining = NULL;
+ }
+
+ /* We get here if either GAPS is empty or if GAPS equals REMAINING. */
+ if (VEC_empty (bfun_s, *gaps))
+ break;
+
+ VEC_free (bfun_s, remaining);
+ }
+
+ do_cleanups (old_chain);
+
+ /* We may omit this in some cases. Not sure it is worth the extra
+ complication, though. */
+ ftrace_compute_global_level_offset (&tp->btrace);
+}
+
/* Compute the function branch trace from BTS trace. */
static void
btrace_compute_ftrace_bts (struct thread_info *tp,
- const struct btrace_data_bts *btrace)
+ const struct btrace_data_bts *btrace,
+ VEC (bfun_s) **gaps)
{
struct btrace_thread_info *btinfo;
struct btrace_function *begin, *end;
struct gdbarch *gdbarch;
- unsigned int blk, ngaps;
+ unsigned int blk;
int level;
gdbarch = target_gdbarch ();
btinfo = &tp->btrace;
begin = btinfo->begin;
end = btinfo->end;
- ngaps = btinfo->ngaps;
level = begin != NULL ? -btinfo->level : INT_MAX;
blk = VEC_length (btrace_block_s, btrace->blocks);
if (begin == NULL)
begin = end;
- ngaps += 1;
+ VEC_safe_push (bfun_s, *gaps, end);
warning (_("Recorded trace may be corrupted at instruction "
"%u (pc = %s)."), end->insn_offset - 1,
/* Indicate the gap in the trace. We just added INSN so we're
not at the beginning. */
end = ftrace_new_gap (end, BDE_BTS_INSN_SIZE);
- ngaps += 1;
+
+ VEC_safe_push (bfun_s, *gaps, end);
warning (_("Recorded trace may be incomplete at instruction %u "
"(pc = %s)."), end->insn_offset - 1,
btinfo->begin = begin;
btinfo->end = end;
- btinfo->ngaps = ngaps;
/* LEVEL is the minimal function level of all btrace function segments.
Define the global level offset to -LEVEL so all function levels are
ftrace_add_pt (struct pt_insn_decoder *decoder,
struct btrace_function **pbegin,
struct btrace_function **pend, int *plevel,
- unsigned int *ngaps)
+ VEC (bfun_s) **gaps)
{
struct btrace_function *begin, *end, *upd;
uint64_t offset;
if (insn.enabled)
{
*pend = end = ftrace_new_gap (end, BDE_PT_DISABLED);
- *ngaps += 1;
+
+ VEC_safe_push (bfun_s, *gaps, end);
pt_insn_get_offset (decoder, &offset);
if (begin == NULL)
*pbegin = begin = end;
- *ngaps += 1;
+ VEC_safe_push (bfun_s, *gaps, end);
pt_insn_get_offset (decoder, &offset);
*pend = end = ftrace_new_gap (end, errcode);
if (begin == NULL)
*pbegin = begin = end;
- *ngaps += 1;
+
+ VEC_safe_push (bfun_s, *gaps, end);
pt_insn_get_offset (decoder, &offset);
static void
btrace_compute_ftrace_pt (struct thread_info *tp,
- const struct btrace_data_pt *btrace)
+ const struct btrace_data_pt *btrace,
+ VEC (bfun_s) **gaps)
{
struct btrace_thread_info *btinfo;
struct pt_insn_decoder *decoder;
error (_("Failed to configure the Intel Processor Trace decoder: "
"%s."), pt_errstr (pt_errcode (errcode)));
- ftrace_add_pt (decoder, &btinfo->begin, &btinfo->end, &level,
- &btinfo->ngaps);
+ ftrace_add_pt (decoder, &btinfo->begin, &btinfo->end, &level, gaps);
}
CATCH (error, RETURN_MASK_ALL)
{
if (error.reason == RETURN_QUIT && btinfo->end != NULL)
{
btinfo->end = ftrace_new_gap (btinfo->end, BDE_PT_USER_QUIT);
- btinfo->ngaps++;
+
+ VEC_safe_push (bfun_s, *gaps, btinfo->end);
}
btrace_finalize_ftrace_pt (decoder, tp, level);
static void
btrace_compute_ftrace_pt (struct thread_info *tp,
- const struct btrace_data_pt *btrace)
+ const struct btrace_data_pt *btrace,
+ VEC (bfun_s) **gaps)
{
internal_error (__FILE__, __LINE__, _("Unexpected branch trace format."));
}
a thread given by BTINFO. */
static void
-btrace_compute_ftrace (struct thread_info *tp, struct btrace_data *btrace)
+btrace_compute_ftrace_1 (struct thread_info *tp, struct btrace_data *btrace,
+ VEC (bfun_s) **gaps)
{
DEBUG ("compute ftrace");
return;
case BTRACE_FORMAT_BTS:
- btrace_compute_ftrace_bts (tp, &btrace->variant.bts);
+ btrace_compute_ftrace_bts (tp, &btrace->variant.bts, gaps);
return;
case BTRACE_FORMAT_PT:
- btrace_compute_ftrace_pt (tp, &btrace->variant.pt);
+ btrace_compute_ftrace_pt (tp, &btrace->variant.pt, gaps);
return;
}
internal_error (__FILE__, __LINE__, _("Unkown branch trace format."));
}
+static void
+btrace_finalize_ftrace (struct thread_info *tp, VEC (bfun_s) **gaps)
+{
+ if (!VEC_empty (bfun_s, *gaps))
+ {
+ tp->btrace.ngaps += VEC_length (bfun_s, *gaps);
+ btrace_bridge_gaps (tp, gaps);
+ }
+}
+
+static void
+btrace_compute_ftrace (struct thread_info *tp, struct btrace_data *btrace)
+{
+ VEC (bfun_s) *gaps;
+ struct cleanup *old_chain;
+
+ gaps = NULL;
+ old_chain = make_cleanup (VEC_cleanup (bfun_s), &gaps);
+
+ TRY
+ {
+ btrace_compute_ftrace_1 (tp, btrace, &gaps);
+ }
+ CATCH (error, RETURN_MASK_ALL)
+ {
+ btrace_finalize_ftrace (tp, &gaps);
+
+ throw_exception (error);
+ }
+ END_CATCH
+
+ btrace_finalize_ftrace (tp, &gaps);
+
+ do_cleanups (old_chain);
+}
+
/* Add an entry for the current PC. */
static void
projects / binutils-gdb.git / commitdiff