[PATCH v3 4/6] perf cs-etm: Support branch filter

Leo Yan
2019-10-05T09:18:25Z

If user specifies option '-F,+callindent' or call chain related options,
it means users only care about function calls and returns; for these
cases, it's pointless to generate samples for the branches within
function. But unlike other hardware trace handling (e.g. Intel's pt or
bts), Arm CoreSight doesn't filter branch types for these options and
generate samples for all branches, this causes Perf to output many
spurious blanks if the branch is not a function call or return.

To only output pairs of calls and returns, this patch introduces branch
filter and the filter is set according to synthetic options. Finally,
Perf can output only for calls and returns and avoid to output other
unnecessary blanks.

Before:

# perf script -F,+callindent
main 2808 1 branches: coresight_test1@plt aaaaba8d37d8 main+0x14 (/root/coresight_test/main)
main 2808 1 branches: coresight_test1@plt aaaaba8d367c coresight_test1@plt+0xc (/root/coresight_test/main)
main 2808 1 branches: _init aaaaba8d3650 _init+0x30 (/root/coresight_test/main)
main 2808 1 branches: _dl_fixup ffff86373b4c _dl_runtime_resolve+0x40 (/lib/aarch64-linux-gnu/ld-2.28.s
main 2808 1 branches: _dl_lookup_symbol_x ffff8636e078 _dl_fixup+0xb8 (/lib/aarch64-linux-gnu/ld-2.28.so)
main 2808 1 branches: ffff8636a3f4 _dl_lookup_symbol_x+0x5c (/lib/aarch64-linux-gnu/ld-2.28.s
main 2808 1 branches: ffff8636a3f4 _dl_lookup_symbol_x+0x5c (/lib/aarch64-linux-gnu/ld-2.28.s
main 2808 1 branches: ffff8636a3f4 _dl_lookup_symbol_x+0x5c (/lib/aarch64-linux-gnu/ld-2.28.s
main 2808 1 branches: ffff8636a3f4 _dl_lookup_symbol_x+0x5c (/lib/aarch64-linux-gnu/ld-2.28.s
main 2808 1 branches: ffff8636a3f4 _dl_lookup_symbol_x+0x5c (/lib/aarch64-linux-gnu/ld-2.28.s
[...]

After:

# perf script -F,+callindent
main 2808 1 branches: coresight_test1@plt aaaaba8d37d8 main+0x14 (/root/coresight_test/main)
main 2808 1 branches: _dl_fixup ffff86373b4c _dl_runtime_resolve+0x40 (/lib/aarch64-linux-gnu/ld-2.28.s
main 2808 1 branches: _dl_lookup_symbol_x ffff8636e078 _dl_fixup+0xb8 (/lib/aarch64-linux-gnu/ld-2.28.so)
main 2808 1 branches: do_lookup_x ffff8636a49c _dl_lookup_symbol_x+0x104 (/lib/aarch64-linux-gnu/ld-2.28.
main 2808 1 branches: check_match ffff86369bf0 do_lookup_x+0x238 (/lib/aarch64-linux-gnu/ld-2.28.so)
main 2808 1 branches: strcmp ffff86369888 check_match+0x70 (/lib/aarch64-linux-gnu/ld-2.28.so)
main 2808 1 branches: printf@plt aaaaba8d37ec main+0x28 (/root/coresight_test/main)
main 2808 1 branches: _dl_fixup ffff86373b4c _dl_runtime_resolve+0x40 (/lib/aarch64-linux-gnu/ld-2.28.s
main 2808 1 branches: _dl_lookup_symbol_x ffff8636e078 _dl_fixup+0xb8 (/lib/aarch64-linux-gnu/ld-2.28.so)
main 2808 1 branches: do_lookup_x ffff8636a49c _dl_lookup_symbol_x+0x104 (/lib/aarch64-linux-gnu/ld-2.28.
main 2808 1 branches: _dl_name_match_p ffff86369af0 do_lookup_x+0x138 (/lib/aarch64-linux-gnu/ld-2.28.so)
main 2808 1 branches: strcmp ffff8636f7f0 _dl_name_match_p+0x18 (/lib/aarch64-linux-gnu/ld-2.28.so)
[...]

Signed-off-by: Leo Yan <leo.yan@linaro.org>
---
tools/perf/util/cs-etm.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 780abbfd1833..4b42f9c9bd34 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -56,6 +56,7 @@ struct cs_etm_auxtrace {

int num_cpu;
u32 auxtrace_type;
+ u32 branches_filter;
u64 branches_sample_type;
u64 branches_id;
u64 instructions_sample_type;
@@ -1223,6 +1224,10 @@ static int cs_etm__synth_branch_sample(struct cs_etm_queue *etmq,
} dummy_bs;
u64 ip;

+ if (etm->branches_filter &&
+ !(etm->branches_filter & tidq->prev_packet->flags))
+ return 0;
+
ip = cs_etm__last_executed_instr(tidq->prev_packet);

event->sample.header.type = PERF_RECORD_SAMPLE;
@@ -2639,6 +2644,13 @@ int cs_etm__process_auxtrace_info(union perf_event *event,
session->itrace_synth_opts->thread_stack;
}

+ if (etm->synth_opts.calls)
+ etm->branches_filter |= PERF_IP_FLAG_CALL | PERF_IP_FLAG_ASYNC |
+ PERF_IP_FLAG_TRACE_END;
+ if (etm->synth_opts.returns)
+ etm->branches_filter |= PERF_IP_FLAG_RETURN |
+ PERF_IP_FLAG_TRACE_BEGIN;
+
err = cs_etm__synth_events(etm, session);
if (err)
goto err_delete_thread;
--
2.17.1