tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0
2/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
3
4#include "vmlinux.h"
5#include <bpf/bpf_helpers.h>
6#include <bpf/bpf_tracing.h>
7
8char _license[] SEC("license") = "GPL";
9
10struct {
11 __uint(type, BPF_MAP_TYPE_CGRP_STORAGE);
12 __uint(map_flags, BPF_F_NO_PREALLOC);
13 __type(key, int);
14 __type(value, long);
15} map_a SEC(".maps");
16
17struct {
18 __uint(type, BPF_MAP_TYPE_CGRP_STORAGE);
19 __uint(map_flags, BPF_F_NO_PREALLOC);
20 __type(key, int);
21 __type(value, long);
22} map_b SEC(".maps");
23
24#define MAGIC_VALUE 0xabcd1234
25
26pid_t target_pid = 0;
27int mismatch_cnt = 0;
28int enter_cnt = 0;
29int exit_cnt = 0;
30
31SEC("tp_btf/sys_enter")
32int BPF_PROG(on_enter, struct pt_regs *regs, long id)
33{
34 struct task_struct *task;
35 long *ptr;
36 int err;
37
38 task = bpf_get_current_task_btf();
39 if (task->pid != target_pid)
40 return 0;
41
42 /* populate value 0 */
43 ptr = bpf_cgrp_storage_get(&map_a, task->cgroups->dfl_cgrp, 0,
44 BPF_LOCAL_STORAGE_GET_F_CREATE);
45 if (!ptr)
46 return 0;
47
48 /* delete value 0 */
49 err = bpf_cgrp_storage_delete(&map_a, task->cgroups->dfl_cgrp);
50 if (err)
51 return 0;
52
53 /* value is not available */
54 ptr = bpf_cgrp_storage_get(&map_a, task->cgroups->dfl_cgrp, 0, 0);
55 if (ptr)
56 return 0;
57
58 /* re-populate the value */
59 ptr = bpf_cgrp_storage_get(&map_a, task->cgroups->dfl_cgrp, 0,
60 BPF_LOCAL_STORAGE_GET_F_CREATE);
61 if (!ptr)
62 return 0;
63 __sync_fetch_and_add(&enter_cnt, 1);
64 *ptr = MAGIC_VALUE + enter_cnt;
65
66 return 0;
67}
68
69SEC("tp_btf/sys_exit")
70int BPF_PROG(on_exit, struct pt_regs *regs, long id)
71{
72 struct task_struct *task;
73 long *ptr;
74
75 task = bpf_get_current_task_btf();
76 if (task->pid != target_pid)
77 return 0;
78
79 ptr = bpf_cgrp_storage_get(&map_a, task->cgroups->dfl_cgrp, 0,
80 BPF_LOCAL_STORAGE_GET_F_CREATE);
81 if (!ptr)
82 return 0;
83
84 __sync_fetch_and_add(&exit_cnt, 1);
85 if (*ptr != MAGIC_VALUE + exit_cnt)
86 __sync_fetch_and_add(&mismatch_cnt, 1);
87 return 0;
88}