linux-kernel - [PATCH 5/5] perf: warn that perf_event_paranoid can restrict kernel symbols

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Message-ID: <1566869956-7154-6-git-send-email-ilubashe@akamai.com>
Date:   Mon, 26 Aug 2019 21:39:16 -0400
From:   Igor Lubashev <ilubashe@...mai.com>
To:     Jiri Olsa <jolsa@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>
CC:     Igor Lubashev <ilubashe@...mai.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Alexey Budankov <alexey.budankov@...ux.intel.com>,
        James Morris <jmorris@...ei.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Suzuki Poulouse <suzuki.poulose@....com>,
        <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH 5/5] perf: warn that perf_event_paranoid can restrict kernel symbols

Warn that /proc/sys/kernel/perf_event_paranoid can also restrict kernel
symbols.

Signed-off-by: Igor Lubashev <ilubashe@...mai.com>
---
 tools/perf/builtin-record.c | 2 +-
 tools/perf/builtin-top.c    | 2 +-
 tools/perf/builtin-trace.c  | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index f71631f2bcb5..18505d92ff69 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -2372,7 +2372,7 @@ int cmd_record(int argc, const char **argv)
 	if (symbol_conf.kptr_restrict && !perf_evlist__exclude_kernel(rec->evlist))
 		pr_warning(
 "WARNING: Kernel address maps (/proc/{kallsyms,modules}) are restricted,\n"
-"check /proc/sys/kernel/kptr_restrict.\n\n"
+"check /proc/sys/kernel/kptr_restrict and /proc/sys/kernel/perf_event_paranoid.\n\n"
 "Samples in kernel functions may not be resolved if a suitable vmlinux\n"
 "file is not found in the buildid cache or in the vmlinux path.\n\n"
 "Samples in kernel modules won't be resolved at all.\n\n"
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 5970723cd55a..29e910fb2d9a 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -770,7 +770,7 @@ static void perf_event__process_sample(struct perf_tool *tool,
 		if (!perf_evlist__exclude_kernel(top->session->evlist)) {
 			ui__warning(
 "Kernel address maps (/proc/{kallsyms,modules}) are restricted.\n\n"
-"Check /proc/sys/kernel/kptr_restrict.\n\n"
+"Check /proc/sys/kernel/kptr_restrict and /proc/sys/kernel/perf_event_paranoid.\n\n"
 "Kernel%s samples will not be resolved.\n",
 			  al.map && map__has_symbols(al.map) ?
 			  " modules" : "");
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index bc44ed29e05a..9443b8e05810 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -1381,7 +1381,7 @@ static char *trace__machine__resolve_kernel_addr(void *vmachine, unsigned long l
 
 	if (symbol_conf.kptr_restrict) {
 		pr_warning("Kernel address maps (/proc/{kallsyms,modules}) are restricted.\n\n"
-			   "Check /proc/sys/kernel/kptr_restrict.\n\n"
+			   "Check /proc/sys/kernel/kptr_restrict and /proc/sys/kernel/perf_event_paranoid.\n\n"
 			   "Kernel samples will not be resolved.\n");
 		machine->kptr_restrict_warned = true;
 		return NULL;
-- 
2.7.4