From: Adrian Hunter <adrian.hunter@intel.com>

Date: Fri, 10 Dec 2021 18:23:00 +0200

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

Git-commit: c79ee2b2160909889df67c8801352d3e69d43a1a

Patch-mainline: v5.16-rc5

References: git-fixes

​

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: f4aa081949e7b6 ("perf tools: Add Intel PT decoder")

Signed-off-by: Adrian 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: Arnaldo Carvalho de Melo <acme@redhat.com>

Signed-off-by: Tony Jones <tonyj@suse.de>

---

 .../perf/util/intel-pt-decoder/intel-pt-decoder.c  | 32 +++++++++++++++++++---

 1 file changed, 28 insertions(+), 4 deletions(-)

​

diff --git a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c

index 16fbbf07e367..845b0ca866a4 100644

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

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

@@ -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;

@@ -3699,7 +3722,8 @@ const struct intel_pt_state *intel_pt_decode(struct intel_pt_decoder *decoder)

    if (err) {

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

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

+       if (err != -EOVERFLOW)

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

        intel_pt_update_sample_time(decoder);

        decoder->sample_tot_cyc_cnt = decoder->tot_cyc_cnt;

        intel_pt_set_nr(decoder);

​

​