On Thu, 4 Nov 2021 10:04:27 -0700
Beau Belgrave <beaub@xxxxxxxxxxxxxxxxxxx> wrote:
> Ensures that when dynamic events requests a match with arguments that
> they match what is in the user_event.
>
> Signed-off-by: Beau Belgrave <beaub@xxxxxxxxxxxxxxxxxxx>
> ---
> kernel/trace/trace_events_user.c | 67 +++++++++++++++++++++++++++++++-
> 1 file changed, 66 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c
> index 479a9ced3281..cd78cc481557 100644
> --- a/kernel/trace/trace_events_user.c
> +++ b/kernel/trace/trace_events_user.c
> @@ -662,13 +662,78 @@ static int user_event_free(struct dyn_event *ev)
> return destroy_user_event(user);
> }
>
> +static int user_field_match(struct ftrace_event_field *field, int argc,
> + const char **argv, int *iout)
> +{
> + char field_name[256];
> + char arg_name[256];
I'm a bit nervous about allocating that much on the stack. This isn't a
critical function. I think it is best to just kmalloc it, and fail in the
unlikely event that the kmalloc fails. It should never fail unless there's
major memory issues with the system.
-- Steve
> + int len, pos, i = *iout;
> + bool colon = false;
> +
> + if (i >= argc)
> + return false;
> +
> + len = sizeof(arg_name);
> + pos = 0;
> +
> + for (; i < argc; ++i) {
> + if (i != *iout)
> + pos += snprintf(arg_name + pos, len - pos, " ");
> +
> + pos += snprintf(arg_name + pos, len - pos, argv[i]);
> +
> + if (strchr(argv[i], ';')) {
> + ++i;
> + colon = true;
> + break;
> + }
> + }
> +
> + len = sizeof(field_name);
> + pos = 0;
> +
> + pos += snprintf(field_name + pos, len - pos, field->type);
> + pos += snprintf(field_name + pos, len - pos, " ");
> + pos += snprintf(field_name + pos, len - pos, field->name);
> +
> + if (colon)
> + pos += snprintf(field_name + pos, len - pos, ";");
> +
> + *iout = i;
> +
> + return strcmp(arg_name, field_name) == 0;
> +}
> +
> +static bool user_fields_match(struct user_event *user, int argc,
> + const char **argv)
> +{
> + struct ftrace_event_field *field, *next;
> + struct list_head *head = &user->fields;
> + int i = 0;
> +
> + list_for_each_entry_safe_reverse(field, next, head, link)
> + if (!user_field_match(field, argc, argv, &i))
> + return false;
> +
> + if (i != argc)
> + return false;
> +
> + return true;
> +}
> +
> static bool user_event_match(const char *system, const char *event,
> int argc, const char **argv, struct dyn_event *ev)
> {
> struct user_event *user = container_of(ev, struct user_event, devent);
> + bool match;
>
> - return strcmp(EVENT_NAME(user), event) == 0 &&
> + match = strcmp(EVENT_NAME(user), event) == 0 &&
> (!system || strcmp(system, USER_EVENTS_SYSTEM) == 0);
> +
> + if (match && argc > 0)
> + match = user_fields_match(user, argc, argv);
> +
> + return match;
> }
>
> static struct dyn_event_operations user_event_dops = {
|