perf top: Switch user option to use BPF filter

Finding user processes by scanning /proc is inherently racy and
results in perf_event_open failures. Use a BPF filter to drop samples
where the uid doesn't match.

Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250604174545.2853620-7-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 7b6cde87d2afd13f21744ecb632cb63afe97a657..051ded5ba9baaac601cc033b6d363c857953441c 100644 (file)
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -643,7 +643,7 @@ repeat:
         */
        evlist__for_each_entry(top->evlist, pos) {
                struct hists *hists = evsel__hists(pos);
-               hists->uid_filter_str = top->record_opts.target.uid_str;
+               hists->uid_filter_str = top->uid_str;
        }
 
        ret = evlist__tui_browse_hists(top->evlist, help, &hbt, top->min_percent,
@@ -1571,7 +1571,7 @@ int cmd_top(int argc, const char **argv)
                    "Add prefix to source file path names in programs (with --prefix-strip)"),
        OPT_STRING(0, "prefix-strip", &annotate_opts.prefix_strip, "N",
                    "Strip first N entries of source file path name in programs (with --prefix)"),
-       OPT_STRING('u', "uid", &target->uid_str, "user", "user to profile"),
+       OPT_STRING('u', "uid", &top.uid_str, "user", "user to profile"),
        OPT_CALLBACK(0, "percent-limit", &top, "percent",
                     "Don't show entries under that percent", parse_percent_limit),
        OPT_CALLBACK(0, "percentage", NULL, "relative|absolute",
@@ -1762,15 +1762,17 @@ int cmd_top(int argc, const char **argv)
                ui__warning("%s\n", errbuf);
        }
 
-       status = target__parse_uid(target);
-       if (status) {
-               int saved_errno = errno;
-
-               target__strerror(target, status, errbuf, BUFSIZ);
-               ui__error("%s\n", errbuf);
+       if (top.uid_str) {
+               uid_t uid = parse_uid(top.uid_str);
 
-               status = -saved_errno;
-               goto out_delete_evlist;
+               if (uid == UINT_MAX) {
+                       ui__error("Invalid User: %s", top.uid_str);
+                       status = -EINVAL;
+                       goto out_delete_evlist;
+               }
+               status = parse_uid_filter(top.evlist, uid);
+               if (status)
+                       goto out_delete_evlist;
        }
 
        if (target__none(target))

diff --git a/tools/perf/util/top.c b/tools/perf/util/top.c
index 4db3d1bd686cf399757edb25ebf671958ba25f63..b06e10a116bb326d0fcc7d7abc71b97973461016 100644 (file)
--- a/tools/perf/util/top.c
+++ b/tools/perf/util/top.c
@@ -88,9 +88,9 @@ size_t perf_top__header_snprintf(struct perf_top *top, char *bf, size_t size)
        else if (target->tid)
                ret += SNPRINTF(bf + ret, size - ret, " (target_tid: %s",
                                target->tid);
-       else if (target->uid_str != NULL)
+       else if (top->uid_str != NULL)
                ret += SNPRINTF(bf + ret, size - ret, " (uid: %s",
-                               target->uid_str);
+                               top->uid_str);
        else
                ret += SNPRINTF(bf + ret, size - ret, " (all");
 

diff --git a/tools/perf/util/top.h b/tools/perf/util/top.h
index 4c5588dbb1317d38fcbddb21d241becd61771706..04ff926846be0f70a4a081e9421c9db1e8ff56f7 100644 (file)
--- a/tools/perf/util/top.h
+++ b/tools/perf/util/top.h
@@ -48,6 +48,7 @@ struct perf_top {
        const char         *sym_filter;
        float              min_percent;
        unsigned int       nr_threads_synthesize;
+       const char         *uid_str;
 
        struct {
                struct ordered_events   *in;