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perf record: Switch user option to use BPF filter

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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. Ensure adding the BPF filter forces
system-wide.

Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250604174545.2853620-5-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
This commit is contained in:
Ian Rogers 2025-06-04 10:45:38 -07:00 committed by Namhyung Kim
parent 466db4275e
commit 1151208e70
1 changed files with 16 additions and 11 deletions
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27
tools/perf/builtin-record.c
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@ -175,6 +175,7 @@ struct record {
bool timestamp_boundary;
bool off_cpu;
const char *filter_action;
const char *uid_str;
struct switch_output switch_output;
unsigned long long samples;
unsigned long output_max_size; /* = 0: unlimited */
@ -3513,8 +3514,7 @@ static struct option __record_options[] = {
"or ranges of time to enable events e.g. '-D 10-20,30-40'",
record__parse_event_enable_time),
OPT_BOOLEAN(0, "kcore", &record.opts.kcore, "copy /proc/kcore"),
OPT_STRING('u', "uid", &record.opts.target.uid_str, "user",
"user to profile"),
OPT_STRING('u', "uid", &record.uid_str, "user", "user to profile"),
OPT_CALLBACK_NOOPT('b', "branch-any", &record.opts.branch_stack,
"branch any", "sample any taken branches",
@ -4256,19 +4256,24 @@ int cmd_record(int argc, const char **argv)
ui__warning("%s\n", errbuf);
}
err = target__parse_uid(&rec->opts.target);
if (err) {
int saved_errno = errno;
if (rec->uid_str) {
uid_t uid = parse_uid(rec->uid_str);
target__strerror(&rec->opts.target, err, errbuf, BUFSIZ);
ui__error("%s", errbuf);
if (uid == UINT_MAX) {
ui__error("Invalid User: %s", rec->uid_str);
err = -EINVAL;
goto out;
}
err = parse_uid_filter(rec->evlist, uid);
if (err)
goto out;
err = -saved_errno;
goto out;
/* User ID filtering implies system wide. */
rec->opts.target.system_wide = true;
}
/* Enable ignoring missing threads when -u/-p option is defined. */
rec->opts.ignore_missing_thread = rec->opts.target.uid != UINT_MAX || rec->opts.target.pid;
/* Enable ignoring missing threads when -p option is defined. */
rec->opts.ignore_missing_thread = rec->opts.target.pid;
evlist__warn_user_requested_cpus(rec->evlist, rec->opts.target.cpu_list);