1// SPDX-License-Identifier: GPL-2.0
2/* Copyright (c) 2020 Facebook */
3#include "bpf_iter.h"
4#include <bpf/bpf_helpers.h>
5#include <bpf/bpf_tracing.h>
6
7char _license[] SEC("license") = "GPL";
8
9uint32_t tid = 0;
10int num_unknown_tid = 0;
11int num_known_tid = 0;
12
13SEC("iter/task")
14int dump_task(struct bpf_iter__task *ctx)
15{
16	struct seq_file *seq = ctx->meta->seq;
17	struct task_struct *task = ctx->task;
18	static char info[] = "    === END ===";
19
20	if (task == (void *)0) {
21		BPF_SEQ_PRINTF(seq, "%s\n", info);
22		return 0;
23	}
24
25	if (task->pid != (pid_t)tid)
26		num_unknown_tid++;
27	else
28		num_known_tid++;
29
30	if (ctx->meta->seq_num == 0)
31		BPF_SEQ_PRINTF(seq, "    tgid      gid\n");
32
33	BPF_SEQ_PRINTF(seq, "%8d %8d\n", task->tgid, task->pid);
34	return 0;
35}
36
37int num_expected_failure_copy_from_user_task = 0;
38int num_success_copy_from_user_task = 0;
39
40SEC("iter.s/task")
41int dump_task_sleepable(struct bpf_iter__task *ctx)
42{
43	struct seq_file *seq = ctx->meta->seq;
44	struct task_struct *task = ctx->task;
45	static const char info[] = "    === END ===";
46	struct pt_regs *regs;
47	void *ptr;
48	uint32_t user_data = 0;
49	int ret;
50
51	if (task == (void *)0) {
52		BPF_SEQ_PRINTF(seq, "%s\n", info);
53		return 0;
54	}
55
56	/* Read an invalid pointer and ensure we get an error */
57	ptr = NULL;
58	ret = bpf_copy_from_user_task(&user_data, sizeof(uint32_t), ptr, task, 0);
59	if (ret) {
60		++num_expected_failure_copy_from_user_task;
61	} else {
62		BPF_SEQ_PRINTF(seq, "%s\n", info);
63		return 0;
64	}
65
66	/* Try to read the contents of the task's instruction pointer from the
67	 * remote task's address space.
68	 */
69	regs = (struct pt_regs *)bpf_task_pt_regs(task);
70	if (regs == (void *)0) {
71		BPF_SEQ_PRINTF(seq, "%s\n", info);
72		return 0;
73	}
74	ptr = (void *)PT_REGS_IP(regs);
75
76	ret = bpf_copy_from_user_task(&user_data, sizeof(uint32_t), ptr, task, 0);
77	if (ret) {
78		BPF_SEQ_PRINTF(seq, "%s\n", info);
79		return 0;
80	}
81	++num_success_copy_from_user_task;
82
83	if (ctx->meta->seq_num == 0)
84		BPF_SEQ_PRINTF(seq, "    tgid      gid     data\n");
85
86	BPF_SEQ_PRINTF(seq, "%8d %8d %8d\n", task->tgid, task->pid, user_data);
87	return 0;
88}
89