Re: [PATCH] tools lib traceevent: add checks for returned EVENT_ERROR type

Jiri Olsa
2015-08-07T10:59:15Z

On Mon, Aug 03, 2015 at 01:08:05PM -0400, Dean Nelson wrote:
> Running the following perf-stat command on an arm64 system produces the
> following result...
>
> [root@aarch64 ~]# perf stat -e kmem:mm_page_alloc -a sleep 1
> Warning: [kmem:mm_page_alloc] function sizeof not defined
> Warning: Error: expected type 4 but read 0
> Segmentation fault
> [root@aarch64 ~]#

hum, what kernel are you running on? I dont see that warning
on my system:

[jolsa@krava perf]$ sudo ./perf stat -e kmem:mm_page_alloc -a sleep 1

Performance counter stats for 'system wide':

227 kmem:mm_page_alloc

1.000762466 seconds time elapsed

Cc-ing Namhyung

jirka

>
> The second warning message and SIGSEGV stem from the issue expressed in the
> first warning message, and are the result of ignoring the EVENT_ERROR type
> returned back through the call chain.
>
> Dealing with the first warning message is beyond the scope of this patch. But
> the second warning is addressed by this patch's first hunk. And the SIGSEGV is
> eliminated by its second hunk.
>
> Signed-off-by: Dean Nelson <dnelson@redhat.com>
> ---
> tools/lib/traceevent/event-parse.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
> index cc25f05..72e2933 100644
> --- a/tools/lib/traceevent/event-parse.c
> +++ b/tools/lib/traceevent/event-parse.c
> @@ -1680,6 +1680,9 @@ process_cond(struct event_format *event, struct print_arg *top, char **tok)
> type = process_arg(event, left, &token);
>
> again:
> + if (type == EVENT_ERROR)
> + goto out_free;
> +
> /* Handle other operations in the arguments */
> if (type == EVENT_OP && strcmp(token, ":") != 0) {
> type = process_op(event, left, &token);
> @@ -1940,7 +1943,7 @@ process_op(struct event_format *event, struct print_arg *arg, char **tok)
>
> type = process_arg_token(event, right, tok, type);
>
> - if (right->type == PRINT_OP &&
> + if (type != EVENT_ERROR && right->type == PRINT_OP &&
> get_op_prio(arg->op.op) < get_op_prio(right->op.op)) {
> struct print_arg tmp;
>