linux-kernel - Re: perf report segfault

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Message-ID: <20181009222004.GA19295@krava>
Date:   Wed, 10 Oct 2018 00:20:04 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Anthony LaTorre <tlatorre9@...il.com>,
        andipan Das <sandipan@...ux.ibm.com>
Cc:     peterz@...radead.org, mingo@...hat.com, jolsa@...nel.org,
        acme@...nel.org, alexander.shishkin@...ux.intel.com,
        namhyung@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: perf report segfault

On Tue, Oct 09, 2018 at 04:47:31PM -0500, Anthony LaTorre wrote:
> I can try building perf from the latest sources. I've attached the
> perf.data and perf.data.tar.bz2 from the test program I sent earlier.

cool, reproduced.. it seems to get introduced by:
  2a9d5050dc84 perf script: Show correct offsets for DWARF-based unwinding

reverting that patch fixes the issue for me, but looks like
we could just make th attached check and prevent the crash

adding Sandipan Das to the loop, the author of that commit, any idea?

thanks,
jirka


---
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index c4acd2001db0..ea68c805c7ac 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -2312,7 +2312,6 @@ static int unwind_entry(struct unwind_entry *entry, void *arg)
 {
 	struct callchain_cursor *cursor = arg;
 	const char *srcline = NULL;
-	u64 addr;
 
 	if (symbol_conf.hide_unresolved && entry->sym == NULL)
 		return 0;
@@ -2320,13 +2319,15 @@ static int unwind_entry(struct unwind_entry *entry, void *arg)
 	if (append_inlines(cursor, entry->map, entry->sym, entry->ip) == 0)
 		return 0;
 
-	/*
-	 * Convert entry->ip from a virtual address to an offset in
-	 * its corresponding binary.
-	 */
-	addr = map__map_ip(entry->map, entry->ip);
+	if (entry->map) {
+		/*
+		 * Convert entry->ip from a virtual address to an offset in
+		 * its corresponding binary.
+		 */
+		u64 addr = map__map_ip(entry->map, entry->ip);
+		srcline = callchain_srcline(entry->map, entry->sym, addr);
+	}
 
-	srcline = callchain_srcline(entry->map, entry->sym, addr);
 	return callchain_cursor_append(cursor, entry->ip,
 				       entry->map, entry->sym,
 				       false, NULL, 0, 0, 0, srcline);