From bff3118d92bfd22952f81e9772e6472f8efcb6ed Mon Sep 17 00:00:00 2001
From: Leo Yan <leo.yan@linaro.org>
Date: Fri, 31 Dec 2021 13:32:02 +0800
Subject: [PATCH 06/21] perf arm-spe: Refactor printing string to buffer

mainline inclusion
from mainline-v5.11-rc1
commit 75eeaddd57f4a0ac89110547221df8f3757d5a6f
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4NGPV
CVE: NA

-------------------------------------------------

When outputs strings to the decoding buffer with function snprintf(),
SPE decoder needs to detects if any error returns from snprintf() and if
so needs to directly bail out.  If snprintf() returns success, it needs
to update buffer pointer and reduce the buffer length so can continue to
output the next string into the consequent memory space.

This complex logics are spreading in the function arm_spe_pkt_desc() so
there has many duplicate codes for handling error detecting, increment
buffer pointer and decrement buffer size.

To avoid the duplicate code, this patch introduces a new helper function
arm_spe_pkt_out_string() which is used to wrap up the complex logics,
and it's used by the caller arm_spe_pkt_desc().  This patch moves the
variable 'blen' as the function's local variable so allows to remove
the unnecessary braces and improve the readability.

This patch simplifies the return value for arm_spe_pkt_desc(): '0' means
success and other values mean an error has occurred.  To realize this,
it relies on arm_spe_pkt_out_string()'s parameter 'err', the 'err' is a
cumulative value, returns its final value if printing buffer is called
for one time or multiple times.  Finally, the error is handled in a
central place, rather than directly bailing out in switch-cases, it
returns error at the end of arm_spe_pkt_desc().

This patch changes the caller arm_spe_dump() to respect the updated
return value semantics of arm_spe_pkt_desc().

Suggested-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Will Deacon <will@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Al Grant <Al.Grant@arm.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wei Li <liwei391@huawei.com>
Link: https://lore.kernel.org/r/20201119152441.6972-2-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Wei Li <liwei391@huawei.com>
Reviewed-by: Yang Jihong <yangjihong1@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Signed-off-by: hongrongxuan <hongrongxuan@huawei.com>
---
 .../arm-spe-decoder/arm-spe-pkt-decoder.c     | 302 +++++++++---------
 tools/perf/util/arm-spe.c                     |   2 +-
 2 files changed, 151 insertions(+), 153 deletions(-)

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 1f97e432d125..81b3a12ed176 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c
@@ -161,7 +161,7 @@ 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");
-- 
2.27.0

