perf tools: Add Intel PT support for decoding MTC packets

MTC packets provide finer grain timestamp information than TSC packets.
MTC packets record time using the hardware crystal clock (CTC) which is
related to TSC packets using a TMA packet.

This patch just adds decoder support.

Support for a default value and validation of values is provided by a
later patch. Also documentation is updated in a separate patch.

For details refer to the June 2015 or later Intel 64 and IA-32
Architectures SDM Chapter 36 Intel Processor Trace.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1437150840-31811-21-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

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

@@ -85,7 +85,9 @@ struct intel_pt_decoder {
 	const unsigned char *buf;
 	size_t len;
 	bool return_compression;
+	bool mtc_insn;
 	bool pge;
+	bool have_tma;
 	uint64_t pos;
 	uint64_t last_ip;
 	uint64_t ip;
@@ -94,6 +96,15 @@ struct intel_pt_decoder {
 	uint64_t tsc_timestamp;
 	uint64_t ref_timestamp;
 	uint64_t ret_addr;
+	uint64_t ctc_timestamp;
+	uint64_t ctc_delta;
+	uint32_t last_mtc;
+	uint32_t tsc_ctc_ratio_n;
+	uint32_t tsc_ctc_ratio_d;
+	uint32_t tsc_ctc_mult;
+	uint32_t tsc_slip;
+	uint32_t ctc_rem_mask;
+	int mtc_shift;
 	struct intel_pt_stack stack;
 	enum intel_pt_pkt_state pkt_state;
 	struct intel_pt_pkt packet;
@@ -149,6 +160,13 @@ static void intel_pt_setup_period(struct intel_pt_decoder *decoder)
 	}
 }
 
+static uint64_t multdiv(uint64_t t, uint32_t n, uint32_t d)
+{
+	if (!d)
+		return 0;
+	return (t / d) * n + ((t % d) * n) / d;
+}
+
 struct intel_pt_decoder *intel_pt_decoder_new(struct intel_pt_params *params)
 {
 	struct intel_pt_decoder *decoder;
@@ -175,6 +193,39 @@ struct intel_pt_decoder *intel_pt_decoder_new(struct intel_pt_params *params)
 
 	intel_pt_setup_period(decoder);
 
+	decoder->mtc_shift = params->mtc_period;
+	decoder->ctc_rem_mask = (1 << decoder->mtc_shift) - 1;
+
+	decoder->tsc_ctc_ratio_n = params->tsc_ctc_ratio_n;
+	decoder->tsc_ctc_ratio_d = params->tsc_ctc_ratio_d;
+
+	if (!decoder->tsc_ctc_ratio_n)
+		decoder->tsc_ctc_ratio_d = 0;
+
+	if (decoder->tsc_ctc_ratio_d) {
+		if (!(decoder->tsc_ctc_ratio_n % decoder->tsc_ctc_ratio_d))
+			decoder->tsc_ctc_mult = decoder->tsc_ctc_ratio_n /
+						decoder->tsc_ctc_ratio_d;
+
+		/*
+		 * Allow for timestamps appearing to backwards because a TSC
+		 * packet has slipped past a MTC packet, so allow 2 MTC ticks
+		 * or ...
+		 */
+		decoder->tsc_slip = multdiv(2 << decoder->mtc_shift,
+					decoder->tsc_ctc_ratio_n,
+					decoder->tsc_ctc_ratio_d);
+	}
+	/* ... or 0x100 paranoia */
+	if (decoder->tsc_slip < 0x100)
+		decoder->tsc_slip = 0x100;
+
+	intel_pt_log("timestamp: mtc_shift %u\n", decoder->mtc_shift);
+	intel_pt_log("timestamp: tsc_ctc_ratio_n %u\n", decoder->tsc_ctc_ratio_n);
+	intel_pt_log("timestamp: tsc_ctc_ratio_d %u\n", decoder->tsc_ctc_ratio_d);
+	intel_pt_log("timestamp: tsc_ctc_mult %u\n", decoder->tsc_ctc_mult);
+	intel_pt_log("timestamp: tsc_slip %#x\n", decoder->tsc_slip);
+
 	return decoder;
 }
 
@@ -368,6 +419,7 @@ static inline void intel_pt_update_in_tx(struct intel_pt_decoder *decoder)
 static int intel_pt_bad_packet(struct intel_pt_decoder *decoder)
 {
 	intel_pt_clear_tx_flags(decoder);
+	decoder->have_tma = false;
 	decoder->pkt_len = 1;
 	decoder->pkt_step = 1;
 	intel_pt_decoder_log_packet(decoder);
@@ -400,6 +452,7 @@ static int intel_pt_get_data(struct intel_pt_decoder *decoder)
 		decoder->pkt_state = INTEL_PT_STATE_NO_PSB;
 		decoder->ref_timestamp = buffer.ref_timestamp;
 		decoder->timestamp = 0;
+		decoder->have_tma = false;
 		decoder->state.trace_nr = buffer.trace_nr;
 		intel_pt_log("Reference timestamp 0x%" PRIx64 "\n",
 			     decoder->ref_timestamp);
@@ -523,6 +576,7 @@ static uint64_t intel_pt_next_sample(struct intel_pt_decoder *decoder)
 	case INTEL_PT_PERIOD_TICKS:
 		return intel_pt_next_period(decoder);
 	case INTEL_PT_PERIOD_NONE:
+	case INTEL_PT_PERIOD_MTC:
 	default:
 		return 0;
 	}
@@ -542,6 +596,7 @@ static void intel_pt_sample_insn(struct intel_pt_decoder *decoder)
 		decoder->last_masked_timestamp = masked_timestamp;
 		break;
 	case INTEL_PT_PERIOD_NONE:
+	case INTEL_PT_PERIOD_MTC:
 	default:
 		break;
 	}
@@ -555,6 +610,9 @@ static int intel_pt_walk_insn(struct intel_pt_decoder *decoder,
 	uint64_t max_insn_cnt, insn_cnt = 0;
 	int err;
 
+	if (!decoder->mtc_insn)
+		decoder->mtc_insn = true;
+
 	max_insn_cnt = intel_pt_next_sample(decoder);
 
 	err = decoder->walk_insn(intel_pt_insn, &insn_cnt, &decoder->ip, ip,
@@ -861,6 +919,8 @@ static void intel_pt_calc_tsc_timestamp(struct intel_pt_decoder *decoder)
 {
 	uint64_t timestamp;
 
+	decoder->have_tma = false;
+
 	if (decoder->ref_timestamp) {
 		timestamp = decoder->packet.payload |
 			    (decoder->ref_timestamp & (0xffULL << 56));
@@ -878,17 +938,18 @@ static void intel_pt_calc_tsc_timestamp(struct intel_pt_decoder *decoder)
 	} else if (decoder->timestamp) {
 		timestamp = decoder->packet.payload |
 			    (decoder->timestamp & (0xffULL << 56));
+		decoder->tsc_timestamp = timestamp;
 		if (timestamp < decoder->timestamp &&
-		    decoder->timestamp - timestamp < 0x100) {
-			intel_pt_log_to("ERROR: Suppressing backwards timestamp",
+		    decoder->timestamp - timestamp < decoder->tsc_slip) {
+			intel_pt_log_to("Suppressing backwards timestamp",
 					timestamp);
 			timestamp = decoder->timestamp;
 		}
 		while (timestamp < decoder->timestamp) {
 			intel_pt_log_to("Wraparound timestamp", timestamp);
 			timestamp += (1ULL << 56);
+			decoder->tsc_timestamp = timestamp;
 		}
-		decoder->tsc_timestamp = timestamp;
 		decoder->timestamp = timestamp;
 		decoder->timestamp_insn_cnt = 0;
 	}
@@ -900,11 +961,73 @@ static int intel_pt_overflow(struct intel_pt_decoder *decoder)
 {
 	intel_pt_log("ERROR: Buffer overflow\n");
 	intel_pt_clear_tx_flags(decoder);
+	decoder->have_tma = false;
 	decoder->pkt_state = INTEL_PT_STATE_ERR_RESYNC;
 	decoder->overflow = true;
 	return -EOVERFLOW;
 }
 
+static void intel_pt_calc_tma(struct intel_pt_decoder *decoder)
+{
+	uint32_t ctc = decoder->packet.payload;
+	uint32_t fc = decoder->packet.count;
+	uint32_t ctc_rem = ctc & decoder->ctc_rem_mask;
+
+	if (!decoder->tsc_ctc_ratio_d)
+		return;
+
+	decoder->last_mtc = (ctc >> decoder->mtc_shift) & 0xff;
+	decoder->ctc_timestamp = decoder->tsc_timestamp - fc;
+	if (decoder->tsc_ctc_mult) {
+		decoder->ctc_timestamp -= ctc_rem * decoder->tsc_ctc_mult;
+	} else {
+		decoder->ctc_timestamp -= multdiv(ctc_rem,
+						  decoder->tsc_ctc_ratio_n,
+						  decoder->tsc_ctc_ratio_d);
+	}
+	decoder->ctc_delta = 0;
+	decoder->have_tma = true;
+	intel_pt_log("CTC timestamp " x64_fmt " last MTC %#x  CTC rem %#x\n",
+		     decoder->ctc_timestamp, decoder->last_mtc, ctc_rem);
+}
+
+static void intel_pt_calc_mtc_timestamp(struct intel_pt_decoder *decoder)
+{
+	uint64_t timestamp;
+	uint32_t mtc, mtc_delta;
+
+	if (!decoder->have_tma)
+		return;
+
+	mtc = decoder->packet.payload;
+
+	if (mtc > decoder->last_mtc)
+		mtc_delta = mtc - decoder->last_mtc;
+	else
+		mtc_delta = mtc + 256 - decoder->last_mtc;
+
+	decoder->ctc_delta += mtc_delta << decoder->mtc_shift;
+
+	if (decoder->tsc_ctc_mult) {
+		timestamp = decoder->ctc_timestamp +
+			    decoder->ctc_delta * decoder->tsc_ctc_mult;
+	} else {
+		timestamp = decoder->ctc_timestamp +
+			    multdiv(decoder->ctc_delta,
+				    decoder->tsc_ctc_ratio_n,
+				    decoder->tsc_ctc_ratio_d);
+	}
+
+	if (timestamp < decoder->timestamp)
+		intel_pt_log("Suppressing MTC timestamp " x64_fmt " less than current timestamp " x64_fmt "\n",
+			     timestamp, decoder->timestamp);
+	else
+		decoder->timestamp = timestamp;
+
+	decoder->timestamp_insn_cnt = 0;
+	decoder->last_mtc = mtc;
+}
+
 /* Walk PSB+ packets when already in sync. */
 static int intel_pt_walk_psbend(struct intel_pt_decoder *decoder)
 {
@@ -926,6 +1049,7 @@ static int intel_pt_walk_psbend(struct intel_pt_decoder *decoder)
 		case INTEL_PT_TRACESTOP:
 		case INTEL_PT_BAD:
 		case INTEL_PT_PSB:
+			decoder->have_tma = false;
 			intel_pt_log("ERROR: Unexpected packet\n");
 			return -EAGAIN;
 
@@ -937,6 +1061,7 @@ static int intel_pt_walk_psbend(struct intel_pt_decoder *decoder)
 			break;
 
 		case INTEL_PT_TMA:
+			intel_pt_calc_tma(decoder);
 			break;
 
 		case INTEL_PT_CBR:
@@ -961,6 +1086,9 @@ static int intel_pt_walk_psbend(struct intel_pt_decoder *decoder)
 			break;
 
 		case INTEL_PT_MTC:
+			intel_pt_calc_mtc_timestamp(decoder);
+			if (decoder->period_type == INTEL_PT_PERIOD_MTC)
+				decoder->state.type |= INTEL_PT_INSTRUCTION;
 			break;
 
 		case INTEL_PT_CYC:
@@ -1048,6 +1176,9 @@ static int intel_pt_walk_fup_tip(struct intel_pt_decoder *decoder)
 			break;
 
 		case INTEL_PT_MTC:
+			intel_pt_calc_mtc_timestamp(decoder);
+			if (decoder->period_type == INTEL_PT_PERIOD_MTC)
+				decoder->state.type |= INTEL_PT_INSTRUCTION;
 			break;
 
 		case INTEL_PT_CYC:
@@ -1159,13 +1290,31 @@ next:
 			break;
 
 		case INTEL_PT_MTC:
-			break;
+			intel_pt_calc_mtc_timestamp(decoder);
+			if (decoder->period_type != INTEL_PT_PERIOD_MTC)
+				break;
+			/*
+			 * Ensure that there has been an instruction since the
+			 * last MTC.
+			 */
+			if (!decoder->mtc_insn)
+				break;
+			decoder->mtc_insn = false;
+			/* Ensure that there is a timestamp */
+			if (!decoder->timestamp)
+				break;
+			decoder->state.type = INTEL_PT_INSTRUCTION;
+			decoder->state.from_ip = decoder->ip;
+			decoder->state.to_ip = 0;
+			decoder->mtc_insn = false;
+			return 0;
 
 		case INTEL_PT_TSC:
 			intel_pt_calc_tsc_timestamp(decoder);
 			break;
 
 		case INTEL_PT_TMA:
+			intel_pt_calc_tma(decoder);
 			break;
 
 		case INTEL_PT_CYC:
@@ -1237,6 +1386,7 @@ static int intel_pt_walk_psb(struct intel_pt_decoder *decoder)
 			break;
 
 		case INTEL_PT_MTC:
+			intel_pt_calc_mtc_timestamp(decoder);
 			break;
 
 		case INTEL_PT_TSC:
@@ -1244,6 +1394,7 @@ static int intel_pt_walk_psb(struct intel_pt_decoder *decoder)
 			break;
 
 		case INTEL_PT_TMA:
+			intel_pt_calc_tma(decoder);
 			break;
 
 		case INTEL_PT_CYC:
@@ -1267,6 +1418,7 @@ static int intel_pt_walk_psb(struct intel_pt_decoder *decoder)
 
 		case INTEL_PT_TRACESTOP:
 		case INTEL_PT_TNT:
+			decoder->have_tma = false;
 			intel_pt_log("ERROR: Unexpected packet\n");
 			if (decoder->ip)
 				decoder->pkt_state = INTEL_PT_STATE_ERR4;
@@ -1329,6 +1481,7 @@ static int intel_pt_walk_to_ip(struct intel_pt_decoder *decoder)
 			break;
 
 		case INTEL_PT_MTC:
+			intel_pt_calc_mtc_timestamp(decoder);
 			break;
 
 		case INTEL_PT_TSC:
@@ -1336,6 +1489,7 @@ static int intel_pt_walk_to_ip(struct intel_pt_decoder *decoder)
 			break;
 
 		case INTEL_PT_TMA:
+			intel_pt_calc_tma(decoder);
 			break;
 
 		case INTEL_PT_CYC:

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

@@ -36,6 +36,7 @@ enum intel_pt_period_type {
 	INTEL_PT_PERIOD_NONE,
 	INTEL_PT_PERIOD_INSTRUCTIONS,
 	INTEL_PT_PERIOD_TICKS,
+	INTEL_PT_PERIOD_MTC,
 };
 
 enum {