1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
|
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2021 Google */
#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
extern const int bpf_prog_active __ksym; /* int type global var. */
SEC("raw_tp/sys_enter")
int handler1(const void *ctx)
{
int *active;
__u32 cpu;
cpu = bpf_get_smp_processor_id();
active = (int *)bpf_per_cpu_ptr(&bpf_prog_active, cpu);
if (active) {
/* Kernel memory obtained from bpf_{per,this}_cpu_ptr
* is read-only, should _not_ pass verification.
*/
/* WRITE_ONCE */
*(volatile int *)active = -1;
}
return 0;
}
__noinline int write_active(int *p)
{
return p ? (*p = 42) : 0;
}
SEC("raw_tp/sys_enter")
int handler2(const void *ctx)
{
int *active;
__u32 cpu;
active = bpf_this_cpu_ptr(&bpf_prog_active);
write_active(active);
return 0;
}
char _license[] SEC("license") = "GPL";
|
