1 files changed, 97 insertions, 2 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 e1d8f7504cbe..0ac860c8dd2b 100644
--- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
+++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
@@ -137,6 +137,7 @@ struct intel_pt_decoder {
 	bool in_psb;
 	bool hop;
 	bool leap;
+	bool emulated_ptwrite;
 	bool vm_time_correlation;
 	bool vm_tm_corr_dry_run;
 	bool vm_tm_corr_reliable;
@@ -481,6 +482,8 @@ static int intel_pt_ext_err(int code)
 		return INTEL_PT_ERR_LOST;
 	case -ELOOP:
 		return INTEL_PT_ERR_NELOOP;
+	case -ECONNRESET:
+		return INTEL_PT_ERR_EPTW;
 	default:
 		return INTEL_PT_ERR_UNK;
 	}
@@ -497,6 +500,7 @@ static const char *intel_pt_err_msgs[] = {
 	[INTEL_PT_ERR_LOST]   = "Lost trace data",
 	[INTEL_PT_ERR_UNK]    = "Unknown error!",
 	[INTEL_PT_ERR_NELOOP] = "Never-ending loop (refer perf config intel-pt.max-loops)",
+	[INTEL_PT_ERR_EPTW]   = "Broken emulated ptwrite",
 };
 
 int intel_pt__strerror(int code, char *buf, size_t buflen)
@@ -1535,17 +1539,108 @@ static int intel_pt_walk_tip(struct intel_pt_decoder *decoder)
 	return intel_pt_bug(decoder);
 }
 
+struct eptw_data {
+	int bit_countdown;
+	uint64_t payload;
+};
+
+static int intel_pt_eptw_lookahead_cb(struct intel_pt_pkt_info *pkt_info)
+{
+	struct eptw_data *data = pkt_info->data;
+	int nr_bits;
+
+	switch (pkt_info->packet.type) {
+	case INTEL_PT_PAD:
+	case INTEL_PT_MNT:
+	case INTEL_PT_MODE_EXEC:
+	case INTEL_PT_MODE_TSX:
+	case INTEL_PT_MTC:
+	case INTEL_PT_FUP:
+	case INTEL_PT_CYC:
+	case INTEL_PT_CBR:
+	case INTEL_PT_TSC:
+	case INTEL_PT_TMA:
+	case INTEL_PT_PIP:
+	case INTEL_PT_VMCS:
+	case INTEL_PT_PSB:
+	case INTEL_PT_PSBEND:
+	case INTEL_PT_PTWRITE:
+	case INTEL_PT_PTWRITE_IP:
+	case INTEL_PT_EXSTOP:
+	case INTEL_PT_EXSTOP_IP:
+	case INTEL_PT_MWAIT:
+	case INTEL_PT_PWRE:
+	case INTEL_PT_PWRX:
+	case INTEL_PT_BBP:
+	case INTEL_PT_BIP:
+	case INTEL_PT_BEP:
+	case INTEL_PT_BEP_IP:
+	case INTEL_PT_CFE:
+	case INTEL_PT_CFE_IP:
+	case INTEL_PT_EVD:
+		break;
+
+	case INTEL_PT_TNT:
+		nr_bits = data->bit_countdown;
+		if (nr_bits > pkt_info->packet.count)
+			nr_bits = pkt_info->packet.count;
+		data->payload <<= nr_bits;
+		data->payload |= pkt_info->packet.payload >> (64 - nr_bits);
+		data->bit_countdown -= nr_bits;
+		return !data->bit_countdown;
+
+	case INTEL_PT_TIP_PGE:
+	case INTEL_PT_TIP_PGD:
+	case INTEL_PT_TIP:
+	case INTEL_PT_BAD:
+	case INTEL_PT_OVF:
+	case INTEL_PT_TRACESTOP:
+	default:
+		return 1;
+	}
+
+	return 0;
+}
+
+static int intel_pt_emulated_ptwrite(struct intel_pt_decoder *decoder)
+{
+	int n = 64 - decoder->tnt.count;
+	struct eptw_data data = {
+		.bit_countdown = n,
+		.payload = decoder->tnt.payload >> n,
+	};
+
+	decoder->emulated_ptwrite = false;
+	intel_pt_log("Emulated ptwrite detected\n");
+
+	intel_pt_pkt_lookahead(decoder, intel_pt_eptw_lookahead_cb, &data);
+	if (data.bit_countdown)
+		return -ECONNRESET;
+
+	decoder->state.type = INTEL_PT_PTW;
+	decoder->state.from_ip = decoder->ip;
+	decoder->state.to_ip = 0;
+	decoder->state.ptw_payload = data.payload;
+	return 0;
+}
+
 static int intel_pt_walk_tnt(struct intel_pt_decoder *decoder)
 {
 	struct intel_pt_insn intel_pt_insn;
 	int err;
 
 	while (1) {
+		if (decoder->emulated_ptwrite)
+			return intel_pt_emulated_ptwrite(decoder);
 		err = intel_pt_walk_insn(decoder, &intel_pt_insn, 0);
-		if (err == INTEL_PT_RETURN)
+		if (err == INTEL_PT_RETURN) {
+			decoder->emulated_ptwrite = intel_pt_insn.emulated_ptwrite;
 			return 0;
-		if (err)
+		}
+		if (err) {
+			decoder->emulated_ptwrite = false;
 			return err;
+		}
 
 		if (intel_pt_insn.op == INTEL_PT_OP_RET) {
 			if (!decoder->return_compression) {