1 // SPDX-License-Identifier: GPL-2.0 2 /* Copyright (c) 2020 Facebook */ 3 4 #include "vmlinux.h" 5 6 #include <bpf/bpf_helpers.h> 7 8 extern const struct rq runqueues __ksym; /* struct type global var. */ 9 extern const int bpf_prog_active __ksym; /* int type global var. */ 10 11 SEC("raw_tp/sys_enter") handler(const void * ctx)12int handler(const void *ctx) 13 { 14 struct rq *rq; 15 int *active; 16 __u32 cpu; 17 18 cpu = bpf_get_smp_processor_id(); 19 rq = (struct rq *)bpf_per_cpu_ptr(&runqueues, cpu); 20 active = (int *)bpf_per_cpu_ptr(&bpf_prog_active, cpu); 21 if (active) { 22 /* READ_ONCE */ 23 *(volatile int *)active; 24 /* !rq has not been tested, so verifier should reject. */ 25 *(volatile int *)(&rq->cpu); 26 } 27 28 return 0; 29 } 30 31 char _license[] SEC("license") = "GPL"; 32