selftests/bpf: Test parameterized task BPF iterators.

Test iterators of vma, files and tasks.

Ensure the API works appropriately to visit all tasks,
tasks in a process, or a particular task.

Signed-off-by: Kui-Feng Lee <[e-mail]>
Signed-off-by: Andrii Nakryiko <[e-mail]>
Acked-by: Yonghong Song <[e-mail]>
Acked-by: Martin KaFai Lau <[e-mail]>
Link: https://lore.kernel.org/bpf/[e-mail]

tools/testing/selftests/bpf/prog_tests/bpf_iter.c

···
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright (c) 2020 Facebook */
 #include <test_progs.h>
+#include <unistd.h>
+#include <sys/syscall.h>
 #include "bpf_iter_ipv6_route.skel.h"
 #include "bpf_iter_netlink.skel.h"
 #include "bpf_iter_bpf_map.skel.h"
···
 #include "bpf_iter_udp4.skel.h"
 #include "bpf_iter_udp6.skel.h"
 #include "bpf_iter_unix.skel.h"
+#include "bpf_iter_vma_offset.skel.h"
 #include "bpf_iter_test_kern1.skel.h"
 #include "bpf_iter_test_kern2.skel.h"
 #include "bpf_iter_test_kern3.skel.h"
···
 	}
 }
 
-static void do_dummy_read(struct bpf_program *prog)
+static void do_dummy_read_opts(struct bpf_program *prog, struct bpf_iter_attach_opts *opts)
 {
 	struct bpf_link *link;
 	char buf[16] = {};
 	int iter_fd, len;
 
-	link = bpf_program__attach_iter(prog, NULL);
+	link = bpf_program__attach_iter(prog, opts);
 	if (!ASSERT_OK_PTR(link, "attach_iter"))
 		return;
 
···
 
 free_link:
 	bpf_link__destroy(link);
+}
+
+static void do_dummy_read(struct bpf_program *prog)
+{
+	do_dummy_read_opts(prog, NULL);
 }
 
 static void do_read_map_iter_fd(struct bpf_object_skeleton **skel, struct bpf_program *prog,
···
 	bpf_iter_bpf_map__destroy(skel);
 }
 
-static void test_task(void)
+static int pidfd_open(pid_t pid, unsigned int flags)
+{
+	return syscall(SYS_pidfd_open, pid, flags);
+}
+
+static void check_bpf_link_info(const struct bpf_program *prog)
+{
+	LIBBPF_OPTS(bpf_iter_attach_opts, opts);
+	union bpf_iter_link_info linfo;
+	struct bpf_link_info info = {};
+	struct bpf_link *link;
+	__u32 info_len;
+	int err;
+
+	memset(&linfo, 0, sizeof(linfo));
+	linfo.task.tid = getpid();
+	opts.link_info = &linfo;
+	opts.link_info_len = sizeof(linfo);
+
+	link = bpf_program__attach_iter(prog, &opts);
+	if (!ASSERT_OK_PTR(link, "attach_iter"))
+		return;
+
+	info_len = sizeof(info);
+	err = bpf_obj_get_info_by_fd(bpf_link__fd(link), &info, &info_len);
+	ASSERT_OK(err, "bpf_obj_get_info_by_fd");
+	ASSERT_EQ(info.iter.task.tid, getpid(), "check_task_tid");
+
+	bpf_link__destroy(link);
+}
+
+static pthread_mutex_t do_nothing_mutex;
+
+static void *do_nothing_wait(void *arg)
+{
+	pthread_mutex_lock(&do_nothing_mutex);
+	pthread_mutex_unlock(&do_nothing_mutex);
+
+	pthread_exit(arg);
+}
+
+static void test_task_common_nocheck(struct bpf_iter_attach_opts *opts,
+				     int *num_unknown, int *num_known)
 {
 	struct bpf_iter_task *skel;
+	pthread_t thread_id;
+	void *ret;
 
 	skel = bpf_iter_task__open_and_load();
 	if (!ASSERT_OK_PTR(skel, "bpf_iter_task__open_and_load"))
 		return;
 
-	do_dummy_read(skel->progs.dump_task);
+	ASSERT_OK(pthread_mutex_lock(&do_nothing_mutex), "pthread_mutex_lock");
+
+	ASSERT_OK(pthread_create(&thread_id, NULL, &do_nothing_wait, NULL),
+		  "pthread_create");
+
+	skel->bss->tid = getpid();
+
+	do_dummy_read_opts(skel->progs.dump_task, opts);
+
+	*num_unknown = skel->bss->num_unknown_tid;
+	*num_known = skel->bss->num_known_tid;
+
+	ASSERT_OK(pthread_mutex_unlock(&do_nothing_mutex), "pthread_mutex_unlock");
+	ASSERT_FALSE(pthread_join(thread_id, &ret) || ret != NULL,
+		     "pthread_join");
 
 	bpf_iter_task__destroy(skel);
+}
+
+static void test_task_common(struct bpf_iter_attach_opts *opts, int num_unknown, int num_known)
+{
+	int num_unknown_tid, num_known_tid;
+
+	test_task_common_nocheck(opts, &num_unknown_tid, &num_known_tid);
+	ASSERT_EQ(num_unknown_tid, num_unknown, "check_num_unknown_tid");
+	ASSERT_EQ(num_known_tid, num_known, "check_num_known_tid");
+}
+
+static void test_task_tid(void)
+{
+	LIBBPF_OPTS(bpf_iter_attach_opts, opts);
+	union bpf_iter_link_info linfo;
+	int num_unknown_tid, num_known_tid;
+
+	memset(&linfo, 0, sizeof(linfo));
+	linfo.task.tid = getpid();
+	opts.link_info = &linfo;
+	opts.link_info_len = sizeof(linfo);
+	test_task_common(&opts, 0, 1);
+
+	linfo.task.tid = 0;
+	linfo.task.pid = getpid();
+	test_task_common(&opts, 1, 1);
+
+	test_task_common_nocheck(NULL, &num_unknown_tid, &num_known_tid);
+	ASSERT_GT(num_unknown_tid, 1, "check_num_unknown_tid");
+	ASSERT_EQ(num_known_tid, 1, "check_num_known_tid");
+}
+
+static void test_task_pid(void)
+{
+	LIBBPF_OPTS(bpf_iter_attach_opts, opts);
+	union bpf_iter_link_info linfo;
+
+	memset(&linfo, 0, sizeof(linfo));
+	linfo.task.pid = getpid();
+	opts.link_info = &linfo;
+	opts.link_info_len = sizeof(linfo);
+
+	test_task_common(&opts, 1, 1);
+}
+
+static void test_task_pidfd(void)
+{
+	LIBBPF_OPTS(bpf_iter_attach_opts, opts);
+	union bpf_iter_link_info linfo;
+	int pidfd;
+
+	pidfd = pidfd_open(getpid(), 0);
+	if (!ASSERT_GT(pidfd, 0, "pidfd_open"))
+		return;
+
+	memset(&linfo, 0, sizeof(linfo));
+	linfo.task.pid_fd = pidfd;
+	opts.link_info = &linfo;
+	opts.link_info_len = sizeof(linfo);
+
+	test_task_common(&opts, 1, 1);
+
+	close(pidfd);
 }
 
 static void test_task_sleepable(void)
···
 	bpf_iter_task_stack__destroy(skel);
 }
 
-static void *do_nothing(void *arg)
-{
-	pthread_exit(arg);
-}
-
 static void test_task_file(void)
 {
+	LIBBPF_OPTS(bpf_iter_attach_opts, opts);
 	struct bpf_iter_task_file *skel;
+	union bpf_iter_link_info linfo;
 	pthread_t thread_id;
 	void *ret;
 
···
 
 	skel->bss->tgid = getpid();
 
-	if (!ASSERT_OK(pthread_create(&thread_id, NULL, &do_nothing, NULL),
-		  "pthread_create"))
-		goto done;
+	ASSERT_OK(pthread_mutex_lock(&do_nothing_mutex), "pthread_mutex_lock");
+
+	ASSERT_OK(pthread_create(&thread_id, NULL, &do_nothing_wait, NULL),
+		  "pthread_create");
+
+	memset(&linfo, 0, sizeof(linfo));
+	linfo.task.tid = getpid();
+	opts.link_info = &linfo;
+	opts.link_info_len = sizeof(linfo);
+
+	do_dummy_read_opts(skel->progs.dump_task_file, &opts);
+
+	ASSERT_EQ(skel->bss->count, 0, "check_count");
+	ASSERT_EQ(skel->bss->unique_tgid_count, 1, "check_unique_tgid_count");
+
+	skel->bss->last_tgid = 0;
+	skel->bss->count = 0;
+	skel->bss->unique_tgid_count = 0;
 
 	do_dummy_read(skel->progs.dump_task_file);
 
-	if (!ASSERT_FALSE(pthread_join(thread_id, &ret) || ret != NULL,
-		  "pthread_join"))
-		goto done;
-
 	ASSERT_EQ(skel->bss->count, 0, "check_count");
+	ASSERT_GT(skel->bss->unique_tgid_count, 1, "check_unique_tgid_count");
 
-done:
+	check_bpf_link_info(skel->progs.dump_task_file);
+
+	ASSERT_OK(pthread_mutex_unlock(&do_nothing_mutex), "pthread_mutex_unlock");
+	ASSERT_OK(pthread_join(thread_id, &ret), "pthread_join");
+	ASSERT_NULL(ret, "pthread_join");
+
 	bpf_iter_task_file__destroy(skel);
 }
 
···
 	*dst = '\0';
 }
 
-static void test_task_vma(void)
+static void test_task_vma_common(struct bpf_iter_attach_opts *opts)
 {
 	int err, iter_fd = -1, proc_maps_fd = -1;
 	struct bpf_iter_task_vma *skel;
···
 		return;
 
 	skel->bss->pid = getpid();
+	skel->bss->one_task = opts ? 1 : 0;
 
 	err = bpf_iter_task_vma__load(skel);
 	if (!ASSERT_OK(err, "bpf_iter_task_vma__load"))
 		goto out;
 
 	skel->links.proc_maps = bpf_program__attach_iter(
-		skel->progs.proc_maps, NULL);
+		skel->progs.proc_maps, opts);
 
 	if (!ASSERT_OK_PTR(skel->links.proc_maps, "bpf_program__attach_iter")) {
 		skel->links.proc_maps = NULL;
···
 			goto out;
 		len += err;
 	}
+	if (opts)
+		ASSERT_EQ(skel->bss->one_task_error, 0, "unexpected task");
 
 	/* read CMP_BUFFER_SIZE (1kB) from /proc/pid/maps */
 	snprintf(maps_path, 64, "/proc/%u/maps", skel->bss->pid);
···
 	str_strip_first_line(proc_maps_output);
 
 	ASSERT_STREQ(task_vma_output, proc_maps_output, "compare_output");
+
+	check_bpf_link_info(skel->progs.proc_maps);
+
 out:
 	close(proc_maps_fd);
 	close(iter_fd);
···
 	bpf_iter_sockmap__destroy(skel);
 }
 
+static void test_task_vma(void)
+{
+	LIBBPF_OPTS(bpf_iter_attach_opts, opts);
+	union bpf_iter_link_info linfo;
+
+	memset(&linfo, 0, sizeof(linfo));
+	linfo.task.tid = getpid();
+	opts.link_info = &linfo;
+	opts.link_info_len = sizeof(linfo);
+
+	test_task_vma_common(&opts);
+	test_task_vma_common(NULL);
+}
+
+/* uprobe attach point */
+static noinline int trigger_func(int arg)
+{
+	asm volatile ("");
+	return arg + 1;
+}
+
+static void test_task_vma_offset_common(struct bpf_iter_attach_opts *opts, bool one_proc)
+{
+	struct bpf_iter_vma_offset *skel;
+	struct bpf_link *link;
+	char buf[16] = {};
+	int iter_fd, len;
+	int pgsz, shift;
+
+	skel = bpf_iter_vma_offset__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "bpf_iter_vma_offset__open_and_load"))
+		return;
+
+	skel->bss->pid = getpid();
+	skel->bss->address = (uintptr_t)trigger_func;
+	for (pgsz = getpagesize(), shift = 0; pgsz > 1; pgsz >>= 1, shift++)
+		;
+	skel->bss->page_shift = shift;
+
+	link = bpf_program__attach_iter(skel->progs.get_vma_offset, opts);
+	if (!ASSERT_OK_PTR(link, "attach_iter"))
+		return;
+
+	iter_fd = bpf_iter_create(bpf_link__fd(link));
+	if (!ASSERT_GT(iter_fd, 0, "create_iter"))
+		goto exit;
+
+	while ((len = read(iter_fd, buf, sizeof(buf))) > 0)
+		;
+	buf[15] = 0;
+	ASSERT_EQ(strcmp(buf, "OK\n"), 0, "strcmp");
+
+	ASSERT_EQ(skel->bss->offset, get_uprobe_offset(trigger_func), "offset");
+	if (one_proc)
+		ASSERT_EQ(skel->bss->unique_tgid_cnt, 1, "unique_tgid_count");
+	else
+		ASSERT_GT(skel->bss->unique_tgid_cnt, 1, "unique_tgid_count");
+
+	close(iter_fd);
+
+exit:
+	bpf_link__destroy(link);
+}
+
+static void test_task_vma_offset(void)
+{
+	LIBBPF_OPTS(bpf_iter_attach_opts, opts);
+	union bpf_iter_link_info linfo;
+
+	memset(&linfo, 0, sizeof(linfo));
+	linfo.task.pid = getpid();
+	opts.link_info = &linfo;
+	opts.link_info_len = sizeof(linfo);
+
+	test_task_vma_offset_common(&opts, true);
+
+	linfo.task.pid = 0;
+	linfo.task.tid = getpid();
+	test_task_vma_offset_common(&opts, true);
+
+	test_task_vma_offset_common(NULL, false);
+}
+
 void test_bpf_iter(void)
 {
+	ASSERT_OK(pthread_mutex_init(&do_nothing_mutex, NULL), "pthread_mutex_init");
+
 	if (test__start_subtest("btf_id_or_null"))
 		test_btf_id_or_null();
 	if (test__start_subtest("ipv6_route"))
···
 		test_netlink();
 	if (test__start_subtest("bpf_map"))
 		test_bpf_map();
-	if (test__start_subtest("task"))
-		test_task();
+	if (test__start_subtest("task_tid"))
+		test_task_tid();
+	if (test__start_subtest("task_pid"))
+		test_task_pid();
+	if (test__start_subtest("task_pidfd"))
+		test_task_pidfd();
 	if (test__start_subtest("task_sleepable"))
 		test_task_sleepable();
 	if (test__start_subtest("task_stack"))
···
 		test_ksym_iter();
 	if (test__start_subtest("bpf_sockmap_map_iter_fd"))
 		test_bpf_sockmap_map_iter_fd();
+	if (test__start_subtest("vma_offset"))
+		test_task_vma_offset();
 }

tools/testing/selftests/bpf/prog_tests/btf_dump.c

···
 
 	/* union with nested struct */
 	TEST_BTF_DUMP_DATA(btf, d, "union", str, union bpf_iter_link_info, BTF_F_COMPACT,
-			   "(union bpf_iter_link_info){.map = (struct){.map_fd = (__u32)1,},.cgroup = (struct){.order = (enum bpf_cgroup_iter_order)BPF_CGROUP_ITER_SELF_ONLY,.cgroup_fd = (__u32)1,},}",
+			   "(union bpf_iter_link_info){.map = (struct){.map_fd = (__u32)1,},.cgroup = (struct){.order = (enum bpf_cgroup_iter_order)BPF_CGROUP_ITER_SELF_ONLY,.cgroup_fd = (__u32)1,},.task = (struct){.tid = (__u32)1,.pid = (__u32)1,},}",
 			   { .cgroup = { .order = 1, .cgroup_fd = 1, }});
 
 	/* struct skb with nested structs/unions; because type output is so

tools/testing/selftests/bpf/progs/bpf_iter_task.c

···
 
 char _license[] SEC("license") = "GPL";
 
+uint32_t tid = 0;
+int num_unknown_tid = 0;
+int num_known_tid = 0;
+
 SEC("iter/task")
 int dump_task(struct bpf_iter__task *ctx)
 {
···
 		BPF_SEQ_PRINTF(seq, "%s\n", info);
 		return 0;
 	}
+
+	if (task->pid != tid)
+		num_unknown_tid++;
+	else
+		num_known_tid++;
 
 	if (ctx->meta->seq_num == 0)
 		BPF_SEQ_PRINTF(seq, "    tgid      gid\n");

tools/testing/selftests/bpf/progs/bpf_iter_task_file.c

···
 
 int count = 0;
 int tgid = 0;
+int last_tgid = 0;
+int unique_tgid_count = 0;
 
 SEC("iter/task_file")
 int dump_task_file(struct bpf_iter__task_file *ctx)
 {
 	struct seq_file *seq = ctx->meta->seq;
 	struct task_struct *task = ctx->task;
-	__u32 fd = ctx->fd;
 	struct file *file = ctx->file;
+	__u32 fd = ctx->fd;
 
 	if (task == (void *)0 || file == (void *)0)
 		return 0;
···
 
 	if (tgid == task->tgid && task->tgid != task->pid)
 		count++;
+
+	if (last_tgid != task->tgid) {
+		last_tgid = task->tgid;
+		unique_tgid_count++;
+	}
 
 	BPF_SEQ_PRINTF(seq, "%8d %8d %8d %lx\n", task->tgid, task->pid, fd,
 		       (long)file->f_op);

tools/testing/selftests/bpf/progs/bpf_iter_task_vma.c

···
 #define D_PATH_BUF_SIZE 1024
 char d_path_buf[D_PATH_BUF_SIZE] = {};
 __u32 pid = 0;
+__u32 one_task = 0;
+__u32 one_task_error = 0;
 
 SEC("iter/task_vma") int proc_maps(struct bpf_iter__task_vma *ctx)
 {
···
 		return 0;
 
 	file = vma->vm_file;
-	if (task->tgid != pid)
+	if (task->tgid != pid) {
+		if (one_task)
+			one_task_error = 1;
 		return 0;
+	}
 	perm_str[0] = (vma->vm_flags & VM_READ) ? 'r' : '-';
 	perm_str[1] = (vma->vm_flags & VM_WRITE) ? 'w' : '-';
 	perm_str[2] = (vma->vm_flags & VM_EXEC) ? 'x' : '-';

tools/testing/selftests/bpf/progs/bpf_iter_vma_offset.c

···
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
+#include "bpf_iter.h"
+#include <bpf/bpf_helpers.h>
+
+char _license[] SEC("license") = "GPL";
+
+__u32 unique_tgid_cnt = 0;
+uintptr_t address = 0;
+uintptr_t offset = 0;
+__u32 last_tgid = 0;
+__u32 pid = 0;
+__u32 page_shift = 0;
+
+SEC("iter/task_vma")
+int get_vma_offset(struct bpf_iter__task_vma *ctx)
+{
+	struct vm_area_struct *vma = ctx->vma;
+	struct seq_file *seq = ctx->meta->seq;
+	struct task_struct *task = ctx->task;
+
+	if (task == NULL || vma == NULL)
+		return 0;
+
+	if (last_tgid != task->tgid)
+		unique_tgid_cnt++;
+	last_tgid = task->tgid;
+
+	if (task->tgid != pid)
+		return 0;
+
+	if (vma->vm_start <= address && vma->vm_end > address) {
+		offset = address - vma->vm_start + (vma->vm_pgoff << page_shift);
+		BPF_SEQ_PRINTF(seq, "OK\n");
+	}
+	return 0;
+}