perf/benchmark: add a new benchmark for seccom_unotify

The benchmark is similar to the pipe benchmark. It creates two processes,
one is calling syscalls, and another process is handling them via seccomp
user notifications. It measures the time required to run a specified number
of interations.

 $ ./perf bench sched  seccomp-notify --sync-mode --loop 1000000
 # Running 'sched/seccomp-notify' benchmark:
 # Executed 1000000 system calls

     Total time: 2.769 [sec]

       2.769629 usecs/op
         361059 ops/sec

 $ ./perf bench sched  seccomp-notify
 # Running 'sched/seccomp-notify' benchmark:
 # Executed 1000000 system calls

     Total time: 8.571 [sec]

       8.571119 usecs/op
         116670 ops/sec
Signed-off-by: Andrei Vagin <avagin@google.com>
Acked-by: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230308073201.3102738-7-avagin@google.com
Link: https://lore.kernel.org/r/20230630051953.454638-1-avagin@gmail.com
[kees: Added PRIu64 format string]
Signed-off-by: Kees Cook <keescook@chromium.org>

tools/arch/x86/include/uapi/asm/unistd_32.h

@@ -26,3 +26,6 @@
 #ifndef __NR_setns
 #define __NR_setns 346
 #endif
+#ifdef __NR_seccomp
+#define __NR_seccomp 354
+#endif

tools/arch/x86/include/uapi/asm/unistd_64.h

@@ -26,3 +26,6 @@
 #ifndef __NR_getcpu
 #define __NR_getcpu 309
 #endif
+#ifndef __NR_seccomp
+#define __NR_seccomp 317
+#endif

tools/perf/bench/Build

 perf-y += sched-messaging.o
 perf-y += sched-pipe.o
+perf-y += sched-seccomp-notify.o
 perf-y += syscall.o
 perf-y += mem-functions.o
 perf-y += futex-hash.o

tools/perf/bench/bench.h

@@ -21,6 +21,7 @@ extern struct timeval bench__start, bench__end, bench__runtime;
 int bench_numa(int argc, const char **argv);
 int bench_sched_messaging(int argc, const char **argv);
 int bench_sched_pipe(int argc, const char **argv);
+int bench_sched_seccomp_notify(int argc, const char **argv);
 int bench_syscall_basic(int argc, const char **argv);
 int bench_syscall_getpgid(int argc, const char **argv);
 int bench_syscall_fork(int argc, const char **argv);

tools/perf/bench/sched-seccomp-notify.c

+// SPDX-License-Identifier: GPL-2.0
+#include <subcmd/parse-options.h>
+#include "bench.h"
+
+#include <uapi/linux/filter.h>
+#include <sys/types.h>
+#include <sys/time.h>
+#include <linux/unistd.h>
+#include <sys/syscall.h>
+#include <sys/ioctl.h>
+#include <linux/time64.h>
+#include <linux/seccomp.h>
+#include <sys/prctl.h>
+
+#include <unistd.h>
+#include <limits.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <sys/wait.h>
+#include <string.h>
+#include <errno.h>
+#include <err.h>
+#include <inttypes.h>
+
+#define LOOPS_DEFAULT 1000000UL
+static uint64_t loops = LOOPS_DEFAULT;
+static bool sync_mode;
+
+static const struct option options[] = {
+	OPT_U64('l', "loop",	&loops,		"Specify number of loops"),
+	OPT_BOOLEAN('s', "sync-mode", &sync_mode,
+		    "Enable the synchronious mode for seccomp notifications"),
+	OPT_END()
+};
+
+static const char * const bench_seccomp_usage[] = {
+	"perf bench sched secccomp-notify <options>",
+	NULL
+};
+
+static int seccomp(unsigned int op, unsigned int flags, void *args)
+{
+	return syscall(__NR_seccomp, op, flags, args);
+}
+
+static int user_notif_syscall(int nr, unsigned int flags)
+{
+	struct sock_filter filter[] = {
+		BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
+			offsetof(struct seccomp_data, nr)),
+		BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, nr, 0, 1),
+		BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_USER_NOTIF),
+		BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW),
+	};
+
+	struct sock_fprog prog = {
+		.len = (unsigned short)ARRAY_SIZE(filter),
+		.filter = filter,
+	};
+
+	return seccomp(SECCOMP_SET_MODE_FILTER, flags, &prog);
+}
+
+#define USER_NOTIF_MAGIC INT_MAX
+static void user_notification_sync_loop(int listener)
+{
+	struct seccomp_notif_resp resp;
+	struct seccomp_notif req;
+	uint64_t nr;
+
+	for (nr = 0; nr < loops; nr++) {
+		memset(&req, 0, sizeof(req));
+		if (ioctl(listener, SECCOMP_IOCTL_NOTIF_RECV, &req))
+			err(EXIT_FAILURE, "SECCOMP_IOCTL_NOTIF_RECV failed");
+
+		if (req.data.nr != __NR_gettid)
+			errx(EXIT_FAILURE, "unexpected syscall: %d", req.data.nr);
+
+		resp.id = req.id;
+		resp.error = 0;
+		resp.val = USER_NOTIF_MAGIC;
+		resp.flags = 0;
+		if (ioctl(listener, SECCOMP_IOCTL_NOTIF_SEND, &resp))
+			err(EXIT_FAILURE, "SECCOMP_IOCTL_NOTIF_SEND failed");
+	}
+}
+
+#ifndef SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP
+#define SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP (1UL << 0)
+#define SECCOMP_IOCTL_NOTIF_SET_FLAGS  SECCOMP_IOW(4, __u64)
+#endif
+int bench_sched_seccomp_notify(int argc, const char **argv)
+{
+	struct timeval start, stop, diff;
+	unsigned long long result_usec = 0;
+	int status, listener;
+	pid_t pid;
+	long ret;
+
+	argc = parse_options(argc, argv, options, bench_seccomp_usage, 0);
+
+	gettimeofday(&start, NULL);
+
+	prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
+	listener = user_notif_syscall(__NR_gettid,
+				      SECCOMP_FILTER_FLAG_NEW_LISTENER);
+	if (listener < 0)
+		err(EXIT_FAILURE, "can't create a notification descriptor");
+
+	pid = fork();
+	if (pid < 0)
+		err(EXIT_FAILURE, "fork");
+	if (pid == 0) {
+		if (prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0))
+			err(EXIT_FAILURE, "can't set the parent death signal");
+		while (1) {
+			ret = syscall(__NR_gettid);
+			if (ret == USER_NOTIF_MAGIC)
+				continue;
+			break;
+		}
+		_exit(1);
+	}
+
+	if (sync_mode) {
+		if (ioctl(listener, SECCOMP_IOCTL_NOTIF_SET_FLAGS,
+			     SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP, 0))
+			err(EXIT_FAILURE,
+			    "can't set SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP");
+	}
+	user_notification_sync_loop(listener);
+
+	kill(pid, SIGKILL);
+	if (waitpid(pid, &status, 0) != pid)
+		err(EXIT_FAILURE, "waitpid(%d) failed", pid);
+	if (!WIFSIGNALED(status) || WTERMSIG(status) != SIGKILL)
+		errx(EXIT_FAILURE, "unexpected exit code: %d", status);
+
+	gettimeofday(&stop, NULL);
+	timersub(&stop, &start, &diff);
+
+	switch (bench_format) {
+	case BENCH_FORMAT_DEFAULT:
+		printf("# Executed %" PRIu64 " system calls\n\n",
+			loops);
+
+		result_usec = diff.tv_sec * USEC_PER_SEC;
+		result_usec += diff.tv_usec;
+
+		printf(" %14s: %lu.%03lu [sec]\n\n", "Total time",
+		       (unsigned long) diff.tv_sec,
+		       (unsigned long) (diff.tv_usec / USEC_PER_MSEC));
+
+		printf(" %14lf usecs/op\n",
+		       (double)result_usec / (double)loops);
+		printf(" %14d ops/sec\n",
+		       (int)((double)loops /
+			     ((double)result_usec / (double)USEC_PER_SEC)));
+		break;
+
+	case BENCH_FORMAT_SIMPLE:
+		printf("%lu.%03lu\n",
+		       (unsigned long) diff.tv_sec,
+		       (unsigned long) (diff.tv_usec / USEC_PER_MSEC));
+		break;
+
+	default:
+		/* reaching here is something disaster */
+		fprintf(stderr, "Unknown format:%d\n", bench_format);
+		exit(1);
+		break;
+	}
+
+	return 0;
+}

tools/perf/builtin-bench.c

@@ -47,6 +47,7 @@ static struct bench numa_benchmarks[] = {
 static struct bench sched_benchmarks[] = {
 	{ "messaging",	"Benchmark for scheduling and IPC",		bench_sched_messaging	},
 	{ "pipe",	"Benchmark for pipe() between two processes",	bench_sched_pipe	},
+	{ "seccomp-notify",	"Benchmark for seccomp user notify",	bench_sched_seccomp_notify},
 	{ "all",	"Run all scheduler benchmarks",		NULL			},
 	{ NULL,		NULL,						NULL			}
 };