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

source code of linux/tools/testing/selftests/bpf/progs/bpf_iter_tasks.c