[tip:perf/core] perf tools: /proc/ kcore requires CAP_SYS_RAWIO message too noisy

[tip-bot for Adrian Hunter <tipbot@zytor.com>]

Commit-ID:  133de940435493266acd4100b0dae8ba7eaa7c71
Gitweb:     http://git.kernel.org/tip/133de940435493266acd4100b0dae8ba7eaa7c71
Author:     Adrian Hunter <adrian.hunter@intel.com>
AuthorDate: Thu, 20 Aug 2015 13:07:40 +0300
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Fri, 21 Aug 2015 10:29:23 -0300

perf tools: /proc/kcore requires CAP_SYS_RAWIO message too noisy

The "/proc/kcore requires CAP_SYS_RAWIO" message comes up all the time
for 'perf script' if vmlinux is not found and the user isn't root, even
when the kernel is not being traced and even though the message is only
really relevant for annotation.

Change it to pr_debug and instead put a note in the message displayed if
annotation is not possible.

Also, the file being accessed might not be /proc/kcore.  Tools can be
directed to a different location using the --kallsyms option in which
case kcore is expected to be in the same directory.  Adjust the message
so it is not misleading in that case.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Li Zhang <zhlcindy@linux.vnet.ibm.com>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1440065260-8802-1-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/annotate.c | 1 +
 tools/perf/util/symbol.c   | 4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
index 8a18347..d1eece7 100644
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -1126,6 +1126,7 @@ fallback:
 		dso->annotate_warned = 1;
 		pr_err("Can't annotate %s:\n\n"
 		       "No vmlinux file%s\nwas found in the path.\n\n"
+		       "Note that annotation using /proc/kcore requires CAP_SYS_RAWIO capability.\n\n"
 		       "Please use:\n\n"
 		       "  perf buildid-cache -vu vmlinux\n\n"
 		       "or:\n\n"
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 725640f..42e98ab 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1138,8 +1138,8 @@ static int dso__load_kcore(struct dso *dso, struct map *map,
 
 	fd = open(kcore_filename, O_RDONLY);
 	if (fd < 0) {
-		pr_err("%s requires CAP_SYS_RAWIO capability to access.\n",
-			kcore_filename);
+		pr_debug("Failed to open %s. Note /proc/kcore requires CAP_SYS_RAWIO capability to access.\n",
+			 kcore_filename);
 		return -EINVAL;
 	}