linux-kernel - [PATCH 01/11] perf intel-pt: Fix FUP packet state

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Message-Id: <20200709173628.5613-2-adrian.hunter@intel.com>
Date:   Thu,  9 Jul 2020 20:36:18 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jiri Olsa <jolsa@...hat.com>, Andi Kleen <ak@...ux.intel.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 01/11] perf intel-pt: Fix FUP packet state

While walking code towards a FUP ip, the packet state is
INTEL_PT_STATE_FUP or INTEL_PT_STATE_FUP_NO_TIP. That was mishandled
resulting in the state becoming INTEL_PT_STATE_IN_SYNC prematurely.
The result was an occasional lost EXSTOP event.

Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
Cc: stable@...r.kernel.org
---
 .../util/intel-pt-decoder/intel-pt-decoder.c  | 21 +++++++------------
 1 file changed, 7 insertions(+), 14 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 f8ccfd6be0ee..75c4bd74d521 100644
--- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
@@ -1164,6 +1164,7 @@ static int intel_pt_walk_fup(struct intel_pt_decoder *decoder)
 			return 0;
 		if (err == -EAGAIN ||
 		    intel_pt_fup_with_nlip(decoder, &intel_pt_insn, ip, err)) {
+			decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
 			if (intel_pt_fup_event(decoder))
 				return 0;
 			return -EAGAIN;
@@ -1942,17 +1943,13 @@ static int intel_pt_walk_trace(struct intel_pt_decoder *decoder)
 			}
 			if (decoder->set_fup_mwait)
 				no_tip = true;
+			if (no_tip)
+				decoder->pkt_state = INTEL_PT_STATE_FUP_NO_TIP;
+			else
+				decoder->pkt_state = INTEL_PT_STATE_FUP;
 			err = intel_pt_walk_fup(decoder);
-			if (err != -EAGAIN) {
-				if (err)
-					return err;
-				if (no_tip)
-					decoder->pkt_state =
-						INTEL_PT_STATE_FUP_NO_TIP;
-				else
-					decoder->pkt_state = INTEL_PT_STATE_FUP;
-				return 0;
-			}
+			if (err != -EAGAIN)
+				return err;
 			if (no_tip) {
 				no_tip = false;
 				break;
@@ -2599,15 +2596,11 @@ const struct intel_pt_state *intel_pt_decode(struct intel_pt_decoder *decoder)
 			err = intel_pt_walk_tip(decoder);
 			break;
 		case INTEL_PT_STATE_FUP:
-			decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
 			err = intel_pt_walk_fup(decoder);
 			if (err == -EAGAIN)
 				err = intel_pt_walk_fup_tip(decoder);
-			else if (!err)
-				decoder->pkt_state = INTEL_PT_STATE_FUP;
 			break;
 		case INTEL_PT_STATE_FUP_NO_TIP:
-			decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
 			err = intel_pt_walk_fup(decoder);
 			if (err == -EAGAIN)
 				err = intel_pt_walk_trace(decoder);
-- 
2.25.1