linux-kernel - [PATCH 1/9] perf top: Exit if specified --vmlinux can't be used

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Date:	Wed, 27 Jan 2010 21:05:49 -0200
From:	Arnaldo Carvalho de Melo <acme@...radead.org>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	linux-kernel@...r.kernel.org,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Frédéric Weisbecker <fweisbec@...il.com>,
	Mike Galbraith <efault@....de>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>
Subject: [PATCH 1/9] perf top: Exit if specified --vmlinux can't be used

From: Arnaldo Carvalho de Melo <acme@...hat.com>

As we do lazy loading of symtabs we only will know if the specified
vmlinux file is invalid when we actually have a hit in kernel space and
then try to load it. So if we get kernel hits and there are _no_ symbols
in the DSO backing the kernel map, bail out.

Reported-by: Mike Galbraith <efault@....de>
Cc: Frédéric Weisbecker <fweisbec@...il.com>
Cc: Mike Galbraith <efault@....de>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Paul Mackerras <paulus@...ba.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/builtin-top.c |   24 +++++++++++++++++++++++-
 1 files changed, 23 insertions(+), 1 deletions(-)

diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 2227b84..78f9c45 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -951,9 +951,31 @@ static void event__process_sample(const event_t *self,
 	}
 
 	if (event__preprocess_sample(self, session, &al, symbol_filter) < 0 ||
-	    al.sym == NULL || al.filtered)
+	    al.filtered)
 		return;
 
+	if (al.sym == NULL) {
+		/*
+		 * As we do lazy loading of symtabs we only will know if the
+		 * specified vmlinux file is invalid when we actually have a
+		 * hit in kernel space and then try to load it. So if we get
+		 * here and there are _no_ symbols in the DSO backing the
+		 * kernel map, bail out.
+		 *
+		 * We may never get here, for instance, if we use -K/
+		 * --hide-kernel-symbols, even if the user specifies an
+		 * invalid --vmlinux ;-)
+		 */
+		if (al.map == session->vmlinux_maps[MAP__FUNCTION] &&
+		    RB_EMPTY_ROOT(&al.map->dso->symbols[MAP__FUNCTION])) {
+			pr_err("The %s file can't be used\n",
+			       symbol_conf.vmlinux_name);
+			exit(1);
+		}
+
+		return;
+	}
+
 	syme = symbol__priv(al.sym);
 	if (!syme->skip) {
 		syme->count[counter]++;
-- 
1.6.2.5

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