Commit c79ee2b2 authored by Adrian Hunter's avatar Adrian Hunter Committed by Arnaldo Carvalho de Melo
Browse files

perf intel-pt: Fix state setting when receiving overflow (OVF) packet 



An overflow (OVF packet) is treated as an error because it represents a
loss of trace data, but there is no loss of synchronization, so the packet
state should be INTEL_PT_STATE_IN_SYNC not INTEL_PT_STATE_ERR_RESYNC.

To support that, some additional variables must be reset, and the FUP
packet that may follow OVF is treated as an FUP event.

Fixes: f4aa0819 ("perf tools: Add Intel PT decoder")
Signed-off-by: default avatarAdrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: stable@vger.kernel.org # v5.15+
Link: https://lore.kernel.org/r/20211210162303.2288710-5-adrian.hunter@intel.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 4c761d80

tools/perf/util/intel-pt-decoder/intel-pt-decoder.c

+28 −4
Original line number Diff line number Diff line
@@ -1249,6 +1249,20 @@ static bool intel_pt_fup_event(struct intel_pt_decoder *decoder) 
		decoder->state.type |= INTEL_PT_BLK_ITEMS;

		ret = true;

	}

	if (decoder->overflow) {

		decoder->overflow = false;

		if (!ret && !decoder->pge) {

			if (decoder->hop) {

				decoder->state.type = 0;

				decoder->pkt_state = INTEL_PT_STATE_RESAMPLE;

			}

			decoder->pge = true;

			decoder->state.type |= INTEL_PT_BRANCH | INTEL_PT_TRACE_BEGIN;

			decoder->state.from_ip = 0;

			decoder->state.to_ip = decoder->ip;

			return true;

		}

	}

	if (ret) {

		decoder->state.from_ip = decoder->ip;

		decoder->state.to_ip = 0;
@@ -1602,7 +1616,16 @@ static int intel_pt_overflow(struct intel_pt_decoder *decoder) 
	intel_pt_clear_tx_flags(decoder);

	intel_pt_set_nr(decoder);

	decoder->timestamp_insn_cnt = 0;

	decoder->pkt_state = INTEL_PT_STATE_ERR_RESYNC;

	decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;

	decoder->state.from_ip = decoder->ip;

	decoder->ip = 0;

	decoder->pge = false;

	decoder->set_fup_tx_flags = false;

	decoder->set_fup_ptw = false;

	decoder->set_fup_mwait = false;

	decoder->set_fup_pwre = false;

	decoder->set_fup_exstop = false;

	decoder->set_fup_bep = false;

	decoder->overflow = true;

	return -EOVERFLOW;

}
@@ -2957,6 +2980,7 @@ static int intel_pt_walk_trace(struct intel_pt_decoder *decoder) 


		case INTEL_PT_TIP_PGE: {

			decoder->pge = true;

			decoder->overflow = false;

			intel_pt_mtc_cyc_cnt_pge(decoder);

			intel_pt_set_nr(decoder);

			if (decoder->packet.count == 0) {
@@ -3462,10 +3486,10 @@ static int intel_pt_sync_ip(struct intel_pt_decoder *decoder) 
	decoder->set_fup_pwre = false;

	decoder->set_fup_exstop = false;

	decoder->set_fup_bep = false;

	decoder->overflow = false;



	if (!decoder->branch_enable) {

		decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;

		decoder->overflow = false;

		decoder->state.type = 0; /* Do not have a sample */

		return 0;

	}
@@ -3480,7 +3504,6 @@ static int intel_pt_sync_ip(struct intel_pt_decoder *decoder) 
		decoder->pkt_state = INTEL_PT_STATE_RESAMPLE;

	else

		decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;

	decoder->overflow = false;



	decoder->state.from_ip = 0;

	decoder->state.to_ip = decoder->ip;
@@ -3699,6 +3722,7 @@ const struct intel_pt_state *intel_pt_decode(struct intel_pt_decoder *decoder) 


	if (err) {

		decoder->state.err = intel_pt_ext_err(err);

		if (err != -EOVERFLOW)

			decoder->state.from_ip = decoder->ip;

		intel_pt_update_sample_time(decoder);

		decoder->sample_tot_cyc_cnt = decoder->tot_cyc_cnt;