[PATCH bpf-next v3 2/2] selftests/bpf: Cover bpftool ring buffer event_pipe

[Tianyi Chen <diannaaav@gmail.com>]

From: Tianyi Chen <hi@tychen.cc>

Produce known ring buffer records and check complete plain, JSON and
pretty JSON output. Exercise ID and pinned map selection, SIGINT and
SIGTERM shutdown, empty streams and invalid map types or selectors.

Also produce a perf event sample and check its existing header and raw
payload output. Use a payload whose size plus the raw sample length
field is aligned to eight bytes so the expected bytes exclude implicit
perf padding.

Assisted-by: LLM
Signed-off-by: Tianyi Chen <hi@tychen.cc>
---
 .../bpf/prog_tests/bpftool_ringbuf.c          | 425 ++++++++++++++++++
 .../selftests/bpf/progs/bpftool_ringbuf.c     |  47 ++
 2 files changed, 472 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/bpftool_ringbuf.c
 create mode 100644 tools/testing/selftests/bpf/progs/bpftool_ringbuf.c

diff --git a/tools/testing/selftests/bpf/prog_tests/bpftool_ringbuf.c b/tools/testing/selftests/bpf/prog_tests/bpftool_ringbuf.c
new file mode 100644
index 000000000000..1a4ae88c05a0
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/bpftool_ringbuf.c
@@ -0,0 +1,425 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <ctype.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <signal.h>
+#include <sys/mman.h>
+#include <sys/wait.h>
+#include <test_progs.h>
+#include "bpftool_ringbuf.skel.h"
+
+#define WAIT_STEPS 500
+#define WAIT_US 10000
+
+struct consumer {
+	pid_t pid;
+	int fd;
+};
+
+static const char *bpftool_path(void)
+{
+	const char *path = getenv("BPFTOOL");
+
+	if (path)
+		return access(path, X_OK) ? NULL : path;
+	if (!access("./tools/sbin/bpftool", X_OK))
+		return "./tools/sbin/bpftool";
+	if (!access("../tools/sbin/bpftool", X_OK))
+		return "../tools/sbin/bpftool";
+	return NULL;
+}
+
+static void consumer_cleanup(struct consumer *child)
+{
+	if (child->pid > 0) {
+		kill(child->pid, SIGKILL);
+		while (waitpid(child->pid, NULL, 0) < 0 && errno == EINTR)
+			;
+		child->pid = -1;
+	}
+	if (child->fd >= 0) {
+		close(child->fd);
+		child->fd = -1;
+	}
+}
+
+static bool consumer_start(struct consumer *child, int map_fd, const char *format,
+			   const char *pin_path, const char *option,
+			   bool pair, bool capture_errors)
+{
+	struct bpf_map_info info = {};
+	__u32 len = sizeof(info);
+	const char *path = bpftool_path();
+	char *argv[12], id[16];
+	int out[2], ready[2], n = 0, err, err_fd;
+	struct pollfd pfd;
+
+	if (!ASSERT_OK_PTR(path, "bpftool path (set BPFTOOL to override)") ||
+	    !ASSERT_OK(bpf_map_get_info_by_fd(map_fd, &info, &len), "map info"))
+		return false;
+	snprintf(id, sizeof(id), "%u", info.id);
+	argv[n++] = (char *)path;
+	if (format)
+		argv[n++] = (char *)format;
+	argv[n++] = "map";
+	argv[n++] = "event_pipe";
+	argv[n++] = pin_path ? "pinned" : "id";
+	argv[n++] = pin_path ? (char *)pin_path : id;
+	if (option) {
+		argv[n++] = (char *)option;
+		argv[n++] = "0";
+		if (pair) {
+			argv[n++] = "index";
+			argv[n++] = "0";
+		}
+	}
+	argv[n] = NULL;
+	if (!ASSERT_OK(pipe2(out, O_CLOEXEC), "output pipe"))
+		return false;
+	if (!ASSERT_OK(pipe2(ready, O_CLOEXEC), "exec pipe")) {
+		close(out[0]);
+		close(out[1]);
+		return false;
+	}
+	child->pid = fork();
+	if (!child->pid) {
+		close(out[0]);
+		close(ready[0]);
+		err_fd = capture_errors ? out[1] : open("/dev/null", O_WRONLY);
+		if (dup2(out[1], STDOUT_FILENO) < 0 ||
+		    dup2(err_fd, STDERR_FILENO) < 0)
+			goto exec_fail;
+		if (!capture_errors)
+			close(err_fd);
+		close(out[1]);
+		execv(path, argv);
+exec_fail:
+		err = errno;
+		write(ready[1], &err, sizeof(err));
+		_exit(127);
+	}
+	close(out[1]);
+	close(ready[1]);
+	child->fd = out[0];
+	pfd = (struct pollfd) { .fd = ready[0], .events = POLLIN };
+	/* EOF on the close-on-exec pipe distinguishes exec from inherited handlers. */
+	err = child->pid > 0 ? poll(&pfd, 1, WAIT_STEPS * WAIT_US / 1000) : -1;
+	if (!ASSERT_GT(child->pid, 0, "fork") ||
+	    !ASSERT_GT(err, 0, "exec timeout") ||
+	    !ASSERT_EQ(read(ready[0], &err, sizeof(err)), 0, "exec")) {
+		close(ready[0]);
+		consumer_cleanup(child);
+		return false;
+	}
+	close(ready[0]);
+	return true;
+}
+
+static bool consumer_finish(struct consumer *child, int signo, bool success,
+			    char *output, size_t size)
+{
+	int status = 0, i;
+	pid_t ret = 0;
+	ssize_t n;
+	size_t used = 0;
+
+	if (!ASSERT_OK(fcntl(child->fd, F_SETFL, O_NONBLOCK), "nonblocking output"))
+		return false;
+	if (signo && !ASSERT_OK(kill(child->pid, signo), "signal consumer"))
+		return false;
+	for (i = 0; i < WAIT_STEPS; i++) {
+		while (used < size - 1 &&
+		       (n = read(child->fd, output + used, size - 1 - used)) > 0)
+			used += n;
+		ret = waitpid(child->pid, &status, WNOHANG);
+		if (ret == child->pid)
+			break;
+		if (ret < 0 && errno != EINTR)
+			break;
+		usleep(WAIT_US);
+	}
+	if (!ASSERT_EQ(ret, child->pid, "bounded consumer exit"))
+		return false;
+	child->pid = -1;
+	while (used < size - 1 && (n = read(child->fd, output + used, size - 1 - used)) > 0)
+		used += n;
+	output[used] = '\0';
+	return ASSERT_TRUE(WIFEXITED(status), "normal exit") &&
+	       ASSERT_EQ(WEXITSTATUS(status) == 0, success, "exit status");
+}
+
+static bool consumer_ready(struct consumer *child)
+{
+	unsigned long long caught;
+	char path[64], line[256];
+	int i;
+	FILE *f;
+
+	snprintf(path, sizeof(path), "/proc/%d/status", child->pid);
+	for (i = 0; i < WAIT_STEPS; i++) {
+		f = fopen(path, "r");
+		if (!f)
+			break;
+		while (fgets(line, sizeof(line), f)) {
+			if (sscanf(line, "SigCgt: %llx", &caught) == 1 &&
+			    (caught & (1ULL << (SIGINT - 1))) &&
+			    (caught & (1ULL << (SIGTERM - 1)))) {
+				fclose(f);
+				return true;
+			}
+		}
+		fclose(f);
+		usleep(WAIT_US);
+	}
+	return ASSERT_TRUE(false, "consumer signal handlers ready");
+}
+
+static bool emit_record(struct bpftool_ringbuf *skel, int record)
+{
+	char packet[64] = {};
+
+	LIBBPF_OPTS(bpf_test_run_opts, opts,
+		    .data_in = packet,
+		    .data_size_in = sizeof(packet),
+	);
+
+	skel->bss->record = record;
+	return ASSERT_OK(bpf_prog_test_run_opts(bpf_program__fd(skel->progs.produce),
+					      &opts), "produce record") &&
+	       ASSERT_OK(skel->bss->output_err, "ringbuf output");
+}
+
+static bool consumed(unsigned long *position, unsigned long expected)
+{
+	int i;
+
+	for (i = 0; i < WAIT_STEPS; i++) {
+		if (__atomic_load_n(position, __ATOMIC_ACQUIRE) == expected)
+			return true;
+		usleep(WAIT_US);
+	}
+	return ASSERT_EQ(*position, expected, "consumer position");
+}
+
+static void check_json(char *output, const char *expected)
+{
+	char *src = output, *dst = output;
+	bool quoted = false, escaped = false;
+
+	/* Ignore formatting whitespace while checking the entire JSON document. */
+	while (*src) {
+		if (quoted || !isspace((unsigned char)*src))
+			*dst++ = *src;
+		if (!escaped && *src == '"')
+			quoted = !quoted;
+		escaped = !escaped && quoted && *src == '\\';
+		src++;
+	}
+	*dst = '\0';
+	ASSERT_STREQ(output, expected, "JSON records");
+}
+
+static void test_consumer(const char *format, bool idle, int signo, bool pinned)
+{
+	struct consumer child = { .pid = -1, .fd = -1 };
+	struct bpftool_ringbuf *skel;
+	unsigned long *position = MAP_FAILED;
+	int page_size = getpagesize(), fd;
+	char pin_dir[] = "/sys/fs/bpf/bpftool_ringbuf_XXXXXX";
+	char pin_path[sizeof(pin_dir) + sizeof("/map")];
+	bool dir_created = false, map_pinned = false;
+	char output[4096];
+	struct pollfd pfd;
+
+	skel = bpftool_ringbuf__open();
+	if (!ASSERT_OK_PTR(skel, "open"))
+		return;
+	bpf_map__set_max_entries(skel->maps.ringbuf, page_size);
+	if (!ASSERT_OK(bpftool_ringbuf__load(skel), "load"))
+		goto out;
+	fd = bpf_map__fd(skel->maps.ringbuf);
+	if (pinned) {
+		if (!ASSERT_OK_PTR(mkdtemp(pin_dir), "create pin directory"))
+			goto out;
+		dir_created = true;
+		snprintf(pin_path, sizeof(pin_path), "%s/map", pin_dir);
+		if (!ASSERT_OK(bpf_obj_pin(fd, pin_path), "pin ringbuf"))
+			goto out;
+		map_pinned = true;
+	}
+	position = mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, 0);
+	if (!ASSERT_NEQ(position, MAP_FAILED, "consumer mmap"))
+		goto out;
+	if (!idle && (!emit_record(skel, 0) || !emit_record(skel, 1)))
+		goto out;
+	if (!consumer_start(&child, fd, format, pinned ? pin_path : NULL,
+			    NULL, false, false) ||
+	    !consumer_ready(&child))
+		goto out;
+	if (!idle) {
+		/* Both prefilled records occupy 16 bytes including their headers. */
+		if (!consumed(position, 32))
+			goto out;
+		pfd = (struct pollfd) { .fd = child.fd, .events = POLLIN };
+		if (!ASSERT_GT(poll(&pfd, 1, WAIT_STEPS * WAIT_US / 1000), 0,
+			       "records flushed before exit") ||
+		    !ASSERT_TRUE(pfd.revents & POLLIN, "record output readable") ||
+		    !emit_record(skel, 2) || !consumed(position, 64))
+			goto out;
+	}
+	if (!consumer_finish(&child, signo, true, output, sizeof(output)))
+		goto out;
+	if (format && !strcmp(format, "-p"))
+		ASSERT_STREQ(output, idle ? "[]\n" :
+			     "[{\n"
+			     "        \"size\": 2,\n"
+			     "        \"data\": [0,255\n"
+			     "        ]\n"
+			     "    },{\n"
+			     "        \"size\": 5,\n"
+			     "        \"data\": [1,2,3,4,5\n"
+			     "        ]\n"
+			     "    },{\n"
+			     "        \"size\": 17,\n"
+			     "        \"data\": [16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32\n"
+			     "        ]\n"
+			     "    }\n"
+			     "]\n", "pretty JSON records");
+	else if (format)
+		check_json(output, idle ? "[]" :
+			   "[{\"size\":2,\"data\":[0,255]},"
+			   "{\"size\":5,\"data\":[1,2,3,4,5]},"
+			   "{\"size\":17,\"data\":[16,17,18,19,20,21,22,23,"
+			   "24,25,26,27,28,29,30,31,32]}]");
+	else
+		ASSERT_STREQ(output, idle ? "" :
+			     "== size: 2 =====\n00 ff\n"
+			     "== size: 5 =====\n01 02 03 04 05\n"
+			     "== size: 17 =====\n10 11 12 13 14 15 16 17  "
+			     "18 19 1a 1b 1c 1d 1e 1f\n20\n", "plain records");
+out:
+	consumer_cleanup(&child);
+	if (position != MAP_FAILED)
+		munmap(position, page_size);
+	if (map_pinned)
+		ASSERT_OK(unlink(pin_path), "unpin ringbuf");
+	if (dir_created)
+		ASSERT_OK(rmdir(pin_dir), "remove pin directory");
+	bpftool_ringbuf__destroy(skel);
+}
+
+static void test_perf_consumer(void)
+{
+	struct consumer child = { .pid = -1, .fd = -1 };
+	unsigned long long seconds, nanoseconds;
+	struct bpftool_ringbuf *skel;
+	char output[16384], expected[16384];
+	int nr_cpus, cpu, index, offset = 0, i, used = 0, fields;
+	struct pollfd pfd;
+
+	nr_cpus = libbpf_num_possible_cpus();
+	if (!ASSERT_GT(nr_cpus, 0, "possible cpus"))
+		return;
+	skel = bpftool_ringbuf__open();
+	if (!ASSERT_OK_PTR(skel, "open"))
+		return;
+	bpf_map__set_max_entries(skel->maps.ringbuf, getpagesize());
+	bpf_map__set_max_entries(skel->maps.perfbuf, nr_cpus);
+	if (!ASSERT_OK(bpftool_ringbuf__load(skel), "load") ||
+	    !consumer_start(&child, bpf_map__fd(skel->maps.perfbuf), NULL,
+			    NULL, NULL, false, false) || !consumer_ready(&child) ||
+	    !emit_record(skel, 3))
+		goto out;
+	/* One large record flushes the existing buffered perf output callback. */
+	pfd = (struct pollfd) { .fd = child.fd, .events = POLLIN };
+	if (!ASSERT_GT(poll(&pfd, 1, WAIT_STEPS * WAIT_US / 1000), 0,
+		       "perf record output") ||
+	    !ASSERT_TRUE(pfd.revents & POLLIN, "perf output readable") ||
+	    !consumer_finish(&child, SIGINT, true, output, sizeof(output)))
+		goto out;
+	fields = sscanf(output, "== @%llu.%llu CPU: %d index: %d =====\n%n",
+			&seconds, &nanoseconds, &cpu, &index, &offset);
+	if (!ASSERT_EQ(fields, 4, "perf header") ||
+	    !ASSERT_GT(offset, 0, "perf payload offset"))
+		goto out;
+	ASSERT_GT(seconds * 1000000000ULL + nanoseconds, 0, "perf timestamp");
+	ASSERT_LT(nanoseconds, 1000000000ULL, "perf timestamp nanoseconds");
+	ASSERT_GE(cpu, 0, "perf cpu");
+	ASSERT_LT(cpu, nr_cpus, "perf cpu range");
+	ASSERT_EQ(index, cpu, "perf index");
+	for (i = 0; i < sizeof(skel->rodata->perf_payload); i++) {
+		const char *separator = !i ? "" : !(i % 16) ? "\n" :
+					!(i % 8) ? "  " : " ";
+
+		used += snprintf(expected + used, sizeof(expected) - used,
+				 "%s%02x", separator, i == 1 ? 0xff : 0);
+	}
+	snprintf(expected + used, sizeof(expected) - used, "\n");
+	ASSERT_STREQ(output + offset, expected, "perf payload");
+out:
+	consumer_cleanup(&child);
+	bpftool_ringbuf__destroy(skel);
+}
+
+static void test_reject(enum bpf_map_type type, const char *option, bool pair, bool json)
+{
+	struct consumer child = { .pid = -1, .fd = -1 };
+	bool ring = type == BPF_MAP_TYPE_RINGBUF || type == BPF_MAP_TYPE_USER_RINGBUF;
+	const char *expected = option ?
+		"{\"error\":\"ring buffer maps do not support cpu or index arguments\"}" :
+		"{\"error\":\"map is not a perf event array or ring buffer\"}";
+	char output[4096];
+	int fd;
+
+	fd = bpf_map_create(type, NULL, ring ? 0 : 4, ring ? 0 : 4,
+			    ring ? getpagesize() : 1, NULL);
+	if (!ASSERT_GE(fd, 0, "create map"))
+		return;
+	if (consumer_start(&child, fd, json ? "-j" : NULL, NULL, option, pair, true) &&
+	    consumer_finish(&child, 0, false, output, sizeof(output))) {
+		if (json)
+			check_json(output, expected);
+		else
+			ASSERT_GT(strlen(output), 0, "error diagnostic");
+	}
+	consumer_cleanup(&child);
+	close(fd);
+}
+
+void test_bpftool_ringbuf(void)
+{
+	if (test__start_subtest("perf_event_array"))
+		test_perf_consumer();
+	if (test__start_subtest("plain"))
+		test_consumer(NULL, false, SIGINT, false);
+	if (test__start_subtest("json"))
+		test_consumer("-j", false, SIGTERM, false);
+	if (test__start_subtest("pretty_json"))
+		test_consumer("-p", false, SIGINT, false);
+	if (test__start_subtest("pinned_plain"))
+		test_consumer(NULL, false, SIGTERM, true);
+	if (test__start_subtest("pinned_json"))
+		test_consumer("-j", false, SIGINT, true);
+	if (test__start_subtest("pinned_pretty_json"))
+		test_consumer("-p", false, SIGTERM, true);
+	if (test__start_subtest("idle_sigint"))
+		test_consumer(NULL, true, SIGINT, false);
+	if (test__start_subtest("idle_sigterm_json"))
+		test_consumer("-j", true, SIGTERM, false);
+	if (test__start_subtest("idle_sigint_pretty_json"))
+		test_consumer("-p", true, SIGINT, false);
+	if (test__start_subtest("reject_array"))
+		test_reject(BPF_MAP_TYPE_ARRAY, NULL, false, false);
+	if (test__start_subtest("reject_user_ringbuf"))
+		test_reject(BPF_MAP_TYPE_USER_RINGBUF, NULL, false, false);
+	if (test__start_subtest("reject_cpu"))
+		test_reject(BPF_MAP_TYPE_RINGBUF, "cpu", false, false);
+	if (test__start_subtest("reject_index"))
+		test_reject(BPF_MAP_TYPE_RINGBUF, "index", false, false);
+	if (test__start_subtest("reject_cpu_index"))
+		test_reject(BPF_MAP_TYPE_RINGBUF, "cpu", true, false);
+	if (test__start_subtest("reject_user_ringbuf_json"))
+		test_reject(BPF_MAP_TYPE_USER_RINGBUF, NULL, false, true);
+	if (test__start_subtest("reject_cpu_index_json"))
+		test_reject(BPF_MAP_TYPE_RINGBUF, "cpu", true, true);
+}
diff --git a/tools/testing/selftests/bpf/progs/bpftool_ringbuf.c b/tools/testing/selftests/bpf/progs/bpftool_ringbuf.c
new file mode 100644
index 000000000000..bbbc93c30a83
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bpftool_ringbuf.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+struct {
+	__uint(type, BPF_MAP_TYPE_RINGBUF);
+} ringbuf SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
+	__uint(key_size, sizeof(__u32));
+	__uint(value_size, sizeof(__u32));
+	__uint(max_entries, 1);
+} perfbuf SEC(".maps");
+
+/*
+ * Include the u32 raw size in perf's 8-byte alignment to avoid padding.
+ * Keep plain output large enough to flush stdio before the consumer exits.
+ */
+const unsigned char perf_payload[4092] = { 0x00, 0xff };
+
+int record;
+int output_err;
+
+SEC("socket")
+int produce(struct __sk_buff *skb)
+{
+	unsigned char first[] = { 0x00, 0xff };
+	unsigned char second[] = { 1, 2, 3, 4, 5 };
+	unsigned char third[] = {
+		0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+		0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20,
+	};
+
+	if (record == 0)
+		output_err = bpf_ringbuf_output(&ringbuf, first, sizeof(first), 0);
+	else if (record == 1)
+		output_err = bpf_ringbuf_output(&ringbuf, second, sizeof(second), 0);
+	else if (record == 2)
+		output_err = bpf_ringbuf_output(&ringbuf, third, sizeof(third), 0);
+	else
+		output_err = bpf_perf_event_output(skb, &perfbuf, BPF_F_CURRENT_CPU,
+						   (void *)perf_payload, sizeof(perf_payload));
+	return 0;
+}
+
+char LICENSE[] SEC("license") = "GPL";
-- 
2.55.0