perf symbols: Check access permission when reading symbol files
There 2 problems when reading symbols files:
* It doesn't report any errors even if when users specify symbol
files which don't exist with --kallsyms or --vmlinux. The result
just shows the address without symbols, which is not what is expected.
So it's better to report errors and exit the program.
* 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.
/proc/kcore requires CAP_SYS_RAWIO capability to access, so it needs to
change access permission to allow a specific user to read /proc/kcore or
use root to execute the perf command.
This patch is to report errors when symbol files specified by users
don't exist. And check access permission of /proc/kcore when reading it.
Signed-off-by: Li Zhang <zhlcindy@linux.vnet.ibm.com>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1434704253-2632-1-git-send-email-zhlcindy@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 32626ea..348bed4 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -742,6 +742,17 @@
argc = parse_options(argc, argv, options, report_usage, 0);
+ if (symbol_conf.vmlinux_name &&
+ access(symbol_conf.vmlinux_name, R_OK)) {
+ pr_err("Invalid file: %s\n", symbol_conf.vmlinux_name);
+ return -EINVAL;
+ }
+ if (symbol_conf.kallsyms_name &&
+ access(symbol_conf.kallsyms_name, R_OK)) {
+ pr_err("Invalid file: %s\n", symbol_conf.kallsyms_name);
+ return -EINVAL;
+ }
+
if (report.use_stdio)
use_browser = 0;
else if (report.use_tui)
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 504f2d7..48b588c 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1132,8 +1132,11 @@
INIT_LIST_HEAD(&md.maps);
fd = open(kcore_filename, O_RDONLY);
- if (fd < 0)
+ if (fd < 0) {
+ pr_err("%s requires CAP_SYS_RAWIO capability to access.\n",
+ kcore_filename);
return -EINVAL;
+ }
/* Read new maps into temporary lists */
err = file__read_maps(fd, md.type == MAP__FUNCTION, kcore_mapfn, &md,