perf parse-events: Add parse_uid_filter helper

Add parse_uid_filter filter as a helper to parse_filter, that
constructs a uid filter string. As uid filters don't work with
tracepoint filters, add a is_possible_tp_filter function so the
tracepoint filter isn't attempted for tracepoint evsels.

Signed-off-by: Ian Rogers <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Namhyung Kim <[email protected]>

Author: captain5050

tools/perf/util/parse-events.c

@@ -25,6 +25,7 @@
 #include "pmu.h"
 #include "pmus.h"
 #include "asm/bug.h"
+#include "ui/ui.h"
 #include "util/parse-branch-options.h"
 #include "util/evsel_config.h"
 #include "util/event.h"
@@ -2561,6 +2562,12 @@ foreach_evsel_in_last_glob(struct evlist *evlist,
 	return 0;
 }
 
+/* Will a tracepoint filter work for str or should a BPF filter be used? */
+static bool is_possible_tp_filter(const char *str)
+{
+	return strstr(str, "uid") == NULL;
+}
+
 static int set_filter(struct evsel *evsel, const void *arg)
 {
 	const char *str = arg;
@@ -2573,7 +2580,7 @@ static int set_filter(struct evsel *evsel, const void *arg)
 		return -1;
 	}
 
-	if (evsel->core.attr.type == PERF_TYPE_TRACEPOINT) {
+	if (evsel->core.attr.type == PERF_TYPE_TRACEPOINT && is_possible_tp_filter(str)) {
 		if (evsel__append_tp_filter(evsel, str) < 0) {
 			fprintf(stderr,
 				"not enough memory to hold filter string\n");
@@ -2609,6 +2616,30 @@ int parse_filter(const struct option *opt, const char *str,
 					  (const void *)str);
 }
 
+int parse_uid_filter(struct evlist *evlist, uid_t uid)
+{
+	struct option opt = {
+		.value = &evlist,
+	};
+	char buf[128];
+	int ret;
+
+	snprintf(buf, sizeof(buf), "uid == %d", uid);
+	ret = parse_filter(&opt, buf, /*unset=*/0);
+	if (ret) {
+		if (use_browser >= 1) {
+			/*
+			 * Use ui__warning so a pop up appears above the
+			 * underlying BPF error message.
+			 */
+			ui__warning("Failed to add UID filtering that uses BPF filtering.\n");
+		} else {
+			fprintf(stderr, "Failed to add UID filtering that uses BPF filtering.\n");
+		}
+	}
+	return ret;
+}
+
 static int add_exclude_perf_filter(struct evsel *evsel,
 				   const void *arg __maybe_unused)
 {

tools/perf/util/parse-events.h

@@ -11,6 +11,7 @@
 #include <linux/perf_event.h>
 #include <stdio.h>
 #include <string.h>
+#include <sys/types.h>
 
 struct evsel;
 struct evlist;
@@ -45,6 +46,7 @@ static inline int parse_events(struct evlist *evlist, const char *str,
 int parse_event(struct evlist *evlist, const char *str);
 
 int parse_filter(const struct option *opt, const char *str, int unset);
+int parse_uid_filter(struct evlist *evlist, uid_t uid);
 int exclude_perf(const struct option *opt, const char *arg, int unset);
 
 enum parse_events__term_val_type {