On 2015年06月10日 22:44, Arnaldo Carvalho de Melo wrote:
Em Wed, Jun 10, 2015 at 11:01:33AM +0800, Li Zhang escreveu:
When using command perf report --kallsyms=/proc/kallsyms with a non-root
user, symbols are resolved. Then select one symbol and annotate it, it
reports the error as the following:
Can't annotate __clear_user: No vmlinux file with build id xxx was found.
The problem is caused by reading /proc/kcore without access permission.
It needs to change access permission to allow a specific user to read
/proc/kcore or use root to execute the perf command.
But then only if the user tries it again, using -v to enable verbose
mode is that the message will be presented, how about instead return
-EPERM, or -errno, so that this error is propagated back and we
eventually emit a more meaningful message to the user, such as:
"Insufficient permission to access %s.", kcore_filename
Trying to check if that is possible by going to the dso__load_kcore()
callers and on back to the tools.
This sounds much better. I will check whether it can deliver this
message to user.
Thanks Li
- Arnaldo
This patch is to check access permission when reading kcore file.
Signed-off-by: Li Zhang <zhlci...@linux.vnet.ibm.com>
---
tools/perf/util/symbol.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 201f6c4c..8255556 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1125,6 +1125,11 @@ static int dso__load_kcore(struct dso *dso, struct map
*map,
md.type = map->type;
INIT_LIST_HEAD(&md.maps);
+ if (access(kcore_filename, R_OK)) {
+ pr_debug("Can't access file %s.\n", kcore_filename);
+ return -EINVAL;
+ }
+
fd = open(kcore_filename, O_RDONLY);
if (fd < 0)
return -EINVAL;
--
2.1.0
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--
Li Zhang
IBM China Linux Technology Centre
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