linux-kernel - [PATCH 4/9] perf/jit: make perf skip unknown records

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Date:   Thu, 13 Oct 2016 03:59:38 -0700
From:   Stephane Eranian <eranian@...gle.com>
To:     linux-kernel@...r.kernel.org
Cc:     acme@...nel.org, jolsa@...hat.com, peterz@...radead.org,
        mingo@...e.hu, anton@...abs.org, namhyung@...nel.org,
        Stefano Sanfilippo <ssanfilippo@...omium.org>,
        Ross McIlroy <rmcilroy@...omium.org>
Subject: [PATCH 4/9] perf/jit: make perf skip unknown records

From: Stefano Sanfilippo <ssanfilippo@...omium.org>

The behaviour before this commit was to skip the remaining
portion of the jitdump in case an unknown record was found,
including those records that perf could handle.

With this change, parsing a record with an unknown id will
cause a warning to be emitted, the record will be skipped
and parsing will resume from the next (valid) one.

The patch aims at making perf more future proof, by extracting
as much information as possible from jitdumps.

Signed-off-by: Stefano Sanfilippo <ssanfilippo@...omium.org>
Signed-off-by: Ross McIlroy <rmcilroy@...omium.org>
Reviewed-by: Stephane Eranian <eranian@...gle.com>
---
 tools/perf/util/jitdump.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/jitdump.c b/tools/perf/util/jitdump.c
index 95f0884aae02..5db2feb90060 100644
--- a/tools/perf/util/jitdump.c
+++ b/tools/perf/util/jitdump.c
@@ -263,8 +263,7 @@ jit_get_next_entry(struct jit_buf_desc *jd)
 		return NULL;
 
 	if (id >= JIT_CODE_MAX) {
-		pr_warning("next_entry: unknown prefix %d, skipping\n", id);
-		return NULL;
+		pr_warning("next_entry: unknown record type %d, skipping\n", id);
 	}
 	if (bs > jd->bufsize) {
 		void *n;
@@ -322,7 +321,8 @@ jit_get_next_entry(struct jit_buf_desc *jd)
 		break;
 	case JIT_CODE_MAX:
 	default:
-		return NULL;
+		/* skip unknown record (we have read them) */
+		break;
 	}
 	return jr;
 }
-- 
1.9.1