[PATCH V2 4/6] perf tools: Improve thread_stack__process() for trace begin / end

From: Adrian Hunter
Date: Thu Sep 20 2018 - 09:03:00 EST


thread_stack__process() is used to create call paths for database export.
Improve the handling of trace begin / end to allow for a trace that ends in
a call.

Previously, the Intel PT decoder would indicate begin / end by a branch
from / to zero. That hides useful information, in particular when a trace
ends with a call. Before remedying that, enhance the thread stack so that
it identifies the trace end by the flag instead of by ip == 0.

Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
---
tools/perf/util/thread-stack.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/tools/perf/util/thread-stack.c b/tools/perf/util/thread-stack.c
index cea28b9074c1..45a97d15c6c8 100644
--- a/tools/perf/util/thread-stack.c
+++ b/tools/perf/util/thread-stack.c
@@ -357,7 +357,7 @@ void call_return_processor__free(struct call_return_processor *crp)

static int thread_stack__push_cp(struct thread_stack *ts, u64 ret_addr,
u64 timestamp, u64 ref, struct call_path *cp,
- bool no_call)
+ bool no_call, bool trace_end)
{
struct thread_stack_entry *tse;
int err;
@@ -375,6 +375,7 @@ static int thread_stack__push_cp(struct thread_stack *ts, u64 ret_addr,
tse->branch_count = ts->branch_count;
tse->cp = cp;
tse->no_call = no_call;
+ tse->trace_end = trace_end;

return 0;
}
@@ -448,7 +449,7 @@ static int thread_stack__bottom(struct thread *thread, struct thread_stack *ts,
return -ENOMEM;

return thread_stack__push_cp(thread->ts, ip, sample->time, ref, cp,
- true);
+ true, false);
}

static int thread_stack__no_call_return(struct thread *thread,
@@ -480,7 +481,7 @@ static int thread_stack__no_call_return(struct thread *thread,
if (!cp)
return -ENOMEM;
return thread_stack__push_cp(ts, 0, sample->time, ref,
- cp, true);
+ cp, true, false);
}
} else if (thread_stack__in_kernel(ts) && sample->ip < ks) {
/* Return to userspace, so pop all kernel addresses */
@@ -505,7 +506,7 @@ static int thread_stack__no_call_return(struct thread *thread,
return -ENOMEM;

err = thread_stack__push_cp(ts, sample->addr, sample->time, ref, cp,
- true);
+ true, false);
if (err)
return err;

@@ -525,7 +526,7 @@ static int thread_stack__trace_begin(struct thread *thread,

/* Pop trace end */
tse = &ts->stack[ts->cnt - 1];
- if (tse->cp->sym == NULL && tse->cp->ip == 0) {
+ if (tse->trace_end) {
err = thread_stack__call_return(thread, ts, --ts->cnt,
timestamp, ref, false);
if (err)
@@ -554,7 +555,7 @@ static int thread_stack__trace_end(struct thread_stack *ts,
ret_addr = sample->ip + sample->insn_len;

return thread_stack__push_cp(ts, ret_addr, sample->time, ref, cp,
- false);
+ false, true);
}

int thread_stack__process(struct thread *thread, struct comm *comm,
@@ -604,6 +605,7 @@ int thread_stack__process(struct thread *thread, struct comm *comm,
ts->last_time = sample->time;

if (sample->flags & PERF_IP_FLAG_CALL) {
+ bool trace_end = sample->flags & PERF_IP_FLAG_TRACE_END;
struct call_path_root *cpr = ts->crp->cpr;
struct call_path *cp;
u64 ret_addr;
@@ -621,7 +623,7 @@ int thread_stack__process(struct thread *thread, struct comm *comm,
if (!cp)
return -ENOMEM;
err = thread_stack__push_cp(ts, ret_addr, sample->time, ref,
- cp, false);
+ cp, false, trace_end);
} else if (sample->flags & PERF_IP_FLAG_RETURN) {
if (!sample->ip || !sample->addr)
return 0;
--
2.17.1