| // 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 handler(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; |
| } |
| |
| char _license[] SEC("license") = "GPL"; |
