linux-kernel - [PATCH 11/11] perf intel-pt: Add support for decoding PSB+ only

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Date:   Thu,  9 Jul 2020 20:36:28 +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 11/11] perf intel-pt: Add support for decoding PSB+ only

A single q option decodes ip from only FUP/TIP packets. Make it so that
repeating the q option (i.e. qq) decodes only PSB+, getting ip if there is
a FUP packet within PSB+ (i.e. between PSB and PSBEND).

Example:

 $ perf record -e intel_pt//u grep -rI pudding drivers
 [ perf record: Woken up 52 times to write data ]
 [ perf record: Captured and wrote 57.870 MB perf.data ]
 $ time perf script --itrace=bi | wc -l
 58948289

 real    1m23.863s
 user    1m23.251s
 sys     0m7.452s
 $ time perf script --itrace=biq | wc -l
 3385694

 real    0m4.453s
 user    0m4.455s
 sys     0m0.328s
 $ time perf script --itrace=biqq | wc -l
 1883

 real    0m0.047s
 user    0m0.043s
 sys     0m0.009s

Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
---
 tools/perf/Documentation/perf-intel-pt.txt     |  3 +++
 .../util/intel-pt-decoder/intel-pt-decoder.c   | 18 ++++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/tools/perf/Documentation/perf-intel-pt.txt b/tools/perf/Documentation/perf-intel-pt.txt
index 758295a7e3d6..849474629fe7 100644
--- a/tools/perf/Documentation/perf-intel-pt.txt
+++ b/tools/perf/Documentation/perf-intel-pt.txt
@@ -973,6 +973,9 @@ useful only if the control flow of interest is represented or indicated by FUP,
 TIP, TIP.PGE, or TIP.PGD packets.  However the q option could be used to find
 time ranges that could then be decoded fully using the --time option.
 
+Repeating the q option (i.e. qq) decodes only PSB+, getting ip if there is a
+FUP packet within PSB+ (i.e. between PSB and PSBEND).
+
 
 dump option
 ~~~~~~~~~~~
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 ccb204b1a050..697513f35154 100644
--- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
@@ -113,6 +113,7 @@ struct intel_pt_decoder {
 	bool in_psb;
 	bool hop;
 	bool hop_psb_fup;
+	bool leap;
 	enum intel_pt_param_flags flags;
 	uint64_t pos;
 	uint64_t last_ip;
@@ -240,6 +241,7 @@ struct intel_pt_decoder *intel_pt_decoder_new(struct intel_pt_params *params)
 	decoder->return_compression = params->return_compression;
 	decoder->branch_enable      = params->branch_enable;
 	decoder->hop                = params->quick >= 1;
+	decoder->leap               = params->quick >= 2;
 
 	decoder->flags              = params->flags;
 
@@ -1903,9 +1905,18 @@ static int intel_pt_resample(struct intel_pt_decoder *decoder)
 #define HOP_RETURN	2
 #define HOP_AGAIN	3
 
+static int intel_pt_scan_for_psb(struct intel_pt_decoder *decoder);
+
 /* Hop mode: Ignore TNT, do not walk code, but get ip from FUPs and TIPs */
 static int intel_pt_hop_trace(struct intel_pt_decoder *decoder, bool *no_tip, int *err)
 {
+	/* Leap from PSB to PSB, getting ip from FUP within PSB+ */
+	if (decoder->leap && !decoder->in_psb && decoder->packet.type != INTEL_PT_PSB) {
+		*err = intel_pt_scan_for_psb(decoder);
+		if (*err)
+			return HOP_RETURN;
+	}
+
 	switch (decoder->packet.type) {
 	case INTEL_PT_TNT:
 		return HOP_IGNORE;
@@ -2681,6 +2692,7 @@ static int intel_pt_sync(struct intel_pt_decoder *decoder)
 	decoder->ip = 0;
 	intel_pt_clear_stack(&decoder->stack);
 
+leap:
 	err = intel_pt_scan_for_psb(decoder);
 	if (err)
 		return err;
@@ -2702,6 +2714,12 @@ static int intel_pt_sync(struct intel_pt_decoder *decoder)
 			decoder->pkt_state = INTEL_PT_STATE_RESAMPLE;
 		else
 			decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
+	} else if (decoder->leap) {
+		/*
+		 * In leap mode, only PSB+ is decoded, so keeping leaping to the
+		 * next PSB until there is an ip.
+		 */
+		goto leap;
 	} else {
 		return intel_pt_sync_ip(decoder);
 	}
-- 
2.25.1