diff --git a/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c b/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c
index 671a4763fb47..fbededc1bcd4 100644
--- a/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c
+++ b/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c
@@ -9,6 +9,7 @@
 #include <endian.h>
 #include <byteswap.h>
 #include <linux/bitops.h>
+#include <stdarg.h>
 
 #include "arm-spe-pkt-decoder.h"
 
@@ -258,192 +259,189 @@ int arm_spe_get_packet(const unsigned char *buf, size_t len,
 	return ret;
 }
 
+static int arm_spe_pkt_out_string(int *err, char **buf_p, size_t *blen,
+				  const char *fmt, ...)
+{
+	va_list ap;
+	int ret;
+
+	/* Bail out if any error occurred */
+	if (err && *err)
+		return *err;
+
+	va_start(ap, fmt);
+	ret = vsnprintf(*buf_p, *blen, fmt, ap);
+	va_end(ap);
+
+	if (ret < 0) {
+		if (err && !*err)
+			*err = ret;
+
+	/*
+	 * A return value of *blen or more means that the output was
+	 * truncated and the buffer is overrun.
+	 */
+	} else if ((size_t)ret >= *blen) {
+		(*buf_p)[*blen - 1] = '\0';
+
+		/*
+		 * Set *err to 'ret' to avoid overflow if tries to
+		 * fill this buffer sequentially.
+		 */
+		if (err && !*err)
+			*err = ret;
+	} else {
+		*buf_p += ret;
+		*blen -= ret;
+	}
+
+	return ret;
+}
+
 int arm_spe_pkt_desc(const struct arm_spe_pkt *packet, char *buf,
 		     size_t buf_len)
 {
-	int ret, ns, el, idx = packet->index;
+	int ns, el, idx = packet->index;
 	unsigned long long payload = packet->payload;
 	const char *name = arm_spe_pkt_name(packet->type);
+	char *buf_orig = buf;
+	size_t blen = buf_len;
+	int err = 0;
 
 	switch (packet->type) {
 	case ARM_SPE_BAD:
 	case ARM_SPE_PAD:
 	case ARM_SPE_END:
-		return snprintf(buf, buf_len, "%s", name);
-	case ARM_SPE_EVENTS: {
-		size_t blen = buf_len;
-
-		ret = 0;
-		ret = snprintf(buf, buf_len, "EV");
-		buf += ret;
-		blen -= ret;
-		if (payload & 0x1) {
-			ret = snprintf(buf, buf_len, " EXCEPTION-GEN");
-			buf += ret;
-			blen -= ret;
-		}
-		if (payload & 0x2) {
-			ret = snprintf(buf, buf_len, " RETIRED");
-			buf += ret;
-			blen -= ret;
-		}
-		if (payload & 0x4) {
-			ret = snprintf(buf, buf_len, " L1D-ACCESS");
-			buf += ret;
-			blen -= ret;
-		}
-		if (payload & 0x8) {
-			ret = snprintf(buf, buf_len, " L1D-REFILL");
-			buf += ret;
-			blen -= ret;
-		}
-		if (payload & 0x10) {
-			ret = snprintf(buf, buf_len, " TLB-ACCESS");
-			buf += ret;
-			blen -= ret;
-		}
-		if (payload & 0x20) {
-			ret = snprintf(buf, buf_len, " TLB-REFILL");
-			buf += ret;
-			blen -= ret;
-		}
-		if (payload & 0x40) {
-			ret = snprintf(buf, buf_len, " NOT-TAKEN");
-			buf += ret;
-			blen -= ret;
-		}
-		if (payload & 0x80) {
-			ret = snprintf(buf, buf_len, " MISPRED");
-			buf += ret;
-			blen -= ret;
-		}
+		arm_spe_pkt_out_string(&err, &buf, &blen, "%s", name);
+		break;
+	case ARM_SPE_EVENTS:
+		arm_spe_pkt_out_string(&err, &buf, &blen, "EV");
+
+		if (payload & 0x1)
+			arm_spe_pkt_out_string(&err, &buf, &blen, " EXCEPTION-GEN");
+		if (payload & 0x2)
+			arm_spe_pkt_out_string(&err, &buf, &blen, " RETIRED");
+		if (payload & 0x4)
+			arm_spe_pkt_out_string(&err, &buf, &blen, " L1D-ACCESS");
+		if (payload & 0x8)
+			arm_spe_pkt_out_string(&err, &buf, &blen, " L1D-REFILL");
+		if (payload & 0x10)
+			arm_spe_pkt_out_string(&err, &buf, &blen, " TLB-ACCESS");
+		if (payload & 0x20)
+			arm_spe_pkt_out_string(&err, &buf, &blen, " TLB-REFILL");
+		if (payload & 0x40)
+			arm_spe_pkt_out_string(&err, &buf, &blen, " NOT-TAKEN");
+		if (payload & 0x80)
+			arm_spe_pkt_out_string(&err, &buf, &blen, " MISPRED");
 		if (idx > 1) {
-			if (payload & 0x100) {
-				ret = snprintf(buf, buf_len, " LLC-ACCESS");
-				buf += ret;
-				blen -= ret;
-			}
-			if (payload & 0x200) {
-				ret = snprintf(buf, buf_len, " LLC-REFILL");
-				buf += ret;
-				blen -= ret;
-			}
-			if (payload & 0x400) {
-				ret = snprintf(buf, buf_len, " REMOTE-ACCESS");
-				buf += ret;
-				blen -= ret;
-			}
+			if (payload & 0x100)
+				arm_spe_pkt_out_string(&err, &buf, &blen, " LLC-ACCESS");
+			if (payload & 0x200)
+				arm_spe_pkt_out_string(&err, &buf, &blen, " LLC-REFILL");
+			if (payload & 0x400)
+				arm_spe_pkt_out_string(&err, &buf, &blen, " REMOTE-ACCESS");
 		}
-		if (ret < 0)
-			return ret;
-		blen -= ret;
-		return buf_len - blen;
-	}
+		break;
 	case ARM_SPE_OP_TYPE:
 		switch (idx) {
-		case 0:	return snprintf(buf, buf_len, "%s", payload & 0x1 ?
-					"COND-SELECT" : "INSN-OTHER");
-		case 1:	{
-			size_t blen = buf_len;
+		case 0:
+			arm_spe_pkt_out_string(&err, &buf, &blen,
+					payload & 0x1 ? "COND-SELECT" : "INSN-OTHER");
+			break;
+		case 1:
+			arm_spe_pkt_out_string(&err, &buf, &blen,
+					       payload & 0x1 ? "ST" : "LD");
 
-			if (payload & 0x1)
-				ret = snprintf(buf, buf_len, "ST");
-			else
-				ret = snprintf(buf, buf_len, "LD");
-			buf += ret;
-			blen -= ret;
 			if (payload & 0x2) {
-				if (payload & 0x4) {
-					ret = snprintf(buf, buf_len, " AT");
-					buf += ret;
-					blen -= ret;
-				}
-				if (payload & 0x8) {
-					ret = snprintf(buf, buf_len, " EXCL");
-					buf += ret;
-					blen -= ret;
-				}
-				if (payload & 0x10) {
-					ret = snprintf(buf, buf_len, " AR");
-					buf += ret;
-					blen -= ret;
-				}
+				if (payload & 0x4)
+					arm_spe_pkt_out_string(&err, &buf, &blen, " AT");
+				if (payload & 0x8)
+					arm_spe_pkt_out_string(&err, &buf, &blen, " EXCL");
+				if (payload & 0x10)
+					arm_spe_pkt_out_string(&err, &buf, &blen, " AR");
 			} else if (payload & 0x4) {
-				ret = snprintf(buf, buf_len, " SIMD-FP");
-				buf += ret;
-				blen -= ret;
-			}
-			if (ret < 0)
-				return ret;
-			blen -= ret;
-			return buf_len - blen;
-		}
-		case 2:	{
-			size_t blen = buf_len;
-
-			ret = snprintf(buf, buf_len, "B");
-			buf += ret;
-			blen -= ret;
-			if (payload & 0x1) {
-				ret = snprintf(buf, buf_len, " COND");
-				buf += ret;
-				blen -= ret;
-			}
-			if (payload & 0x2) {
-				ret = snprintf(buf, buf_len, " IND");
-				buf += ret;
-				blen -= ret;
-			}
-			if (ret < 0)
-				return ret;
-			blen -= ret;
-			return buf_len - blen;
+				arm_spe_pkt_out_string(&err, &buf, &blen, " SIMD-FP");
 			}
-		default: return 0;
+			break;
+		case 2:
+			arm_spe_pkt_out_string(&err, &buf, &blen, "B");
+
+			if (payload & 0x1)
+				arm_spe_pkt_out_string(&err, &buf, &blen, " COND");
+			if (payload & 0x2)
+				arm_spe_pkt_out_string(&err, &buf, &blen, " IND");
+
+			break;
+		default:
+			/* Unknown index */
+			err = -1;
+			break;
 		}
+		break;
 	case ARM_SPE_DATA_SOURCE:
 	case ARM_SPE_TIMESTAMP:
-		return snprintf(buf, buf_len, "%s %lld", name, payload);
+		arm_spe_pkt_out_string(&err, &buf, &blen, "%s %lld", name, payload);
+		break;
 	case ARM_SPE_ADDRESS:
 		switch (idx) {
 		case 0:
-		case 1: ns = !!(packet->payload & NS_FLAG);
+		case 1:
+			ns = !!(packet->payload & NS_FLAG);
 			el = (packet->payload & EL_FLAG) >> 61;
 			payload &= ~(0xffULL << 56);
-			return snprintf(buf, buf_len, "%s 0x%llx el%d ns=%d",
+			arm_spe_pkt_out_string(&err, &buf, &blen,
+					"%s 0x%llx el%d ns=%d",
 				        (idx == 1) ? "TGT" : "PC", payload, el, ns);
-		case 2:	return snprintf(buf, buf_len, "VA 0x%llx", payload);
-		case 3:	ns = !!(packet->payload & NS_FLAG);
+			break;
+		case 2:
+			arm_spe_pkt_out_string(&err, &buf, &blen,
+					       "VA 0x%llx", payload);
+			break;
+		case 3:
+			ns = !!(packet->payload & NS_FLAG);
 			payload &= ~(0xffULL << 56);
-			return snprintf(buf, buf_len, "PA 0x%llx ns=%d",
-					payload, ns);
-		default: return 0;
+			arm_spe_pkt_out_string(&err, &buf, &blen,
+					       "PA 0x%llx ns=%d", payload, ns);
+			break;
+		default:
+			/* Unknown index */
+			err = -1;
+			break;
 		}
+		break;
 	case ARM_SPE_CONTEXT:
-		return snprintf(buf, buf_len, "%s 0x%lx el%d", name,
-				(unsigned long)payload, idx + 1);
-	case ARM_SPE_COUNTER: {
-		size_t blen = buf_len;
-
-		ret = snprintf(buf, buf_len, "%s %d ", name,
-			       (unsigned short)payload);
-		buf += ret;
-		blen -= ret;
+		arm_spe_pkt_out_string(&err, &buf, &blen, "%s 0x%lx el%d",
+				       name, (unsigned long)payload, idx + 1);
+		break;
+	case ARM_SPE_COUNTER:
+		arm_spe_pkt_out_string(&err, &buf, &blen, "%s %d ", name,
+				       (unsigned short)payload);
 		switch (idx) {
-		case 0:	ret = snprintf(buf, buf_len, "TOT"); break;
-		case 1:	ret = snprintf(buf, buf_len, "ISSUE"); break;
-		case 2:	ret = snprintf(buf, buf_len, "XLAT"); break;
-		default: ret = 0;
+		case 0:
+			arm_spe_pkt_out_string(&err, &buf, &blen, "TOT");
+			break;
+		case 1:
+			arm_spe_pkt_out_string(&err, &buf, &blen, "ISSUE");
+			break;
+		case 2:
+			arm_spe_pkt_out_string(&err, &buf, &blen, "XLAT");
+			break;
+		default:
+			break;
 		}
-		if (ret < 0)
-			return ret;
-		blen -= ret;
-		return buf_len - blen;
-	}
+		break;
 	default:
+		/* Unknown packet type */
+		err = -1;
 		break;
 	}
 
-	return snprintf(buf, buf_len, "%s 0x%llx (%d)",
-			name, payload, packet->index);
+	/* Output raw data if detect any error */
+	if (err) {
+		err = 0;
+		arm_spe_pkt_out_string(&err, &buf_orig, &buf_len, "%s 0x%llx (%d)",
+				       name, payload, packet->index);
+	}
+
+	return err;
 }
diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
index 3882a5360ada..8901a1656a41 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c
@@ -113,7 +113,7 @@ static void arm_spe_dump(struct arm_spe *spe __maybe_unused,
 		if (ret > 0) {
 			ret = arm_spe_pkt_desc(&packet, desc,
 					       ARM_SPE_PKT_DESC_MAX);
-			if (ret > 0)
+			if (!ret)
 				color_fprintf(stdout, color, " %s\n", desc);
 		} else {
 			color_fprintf(stdout, color, " Bad packet!\n");
