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.
- 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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
