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 <kuifeng@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/bpf/20220926184957.208194-5-kuifeng@fb.com

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

@@ -764,7 +764,7 @@ static void test_btf_dump_struct_data(struct btf *btf, struct btf_dump *d,
 
 	/* 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

@@ -6,6 +6,10 @@
 
 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)
 {
@@ -18,6 +22,11 @@ int dump_task(struct bpf_iter__task *ctx)
 		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

@@ -7,14 +7,16 @@ char _license[] SEC("license") = "GPL";
 
 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;
@@ -27,6 +29,11 @@ int dump_task_file(struct bpf_iter__task_file *ctx)
 	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);
 	return 0;

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

@@ -20,6 +20,8 @@ char _license[] SEC("license") = "GPL";
 #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)
 {
@@ -33,8 +35,11 @@ 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;
+}