bpf/progs/test_perf_buffer.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 // Copyright (c) 2019 Facebook
0003
0004 #include <linux/ptrace.h>
0005 #include <linux/bpf.h>
0006 #include <bpf/bpf_helpers.h>
0007 #include <bpf/bpf_tracing.h>
0008
0009 struct {
0010     __uint(type, BPF_MAP_TYPE_ARRAY);
0011     __type(key, int);
0012     __type(value, int);
0013     __uint(max_entries, 1);
0014 } my_pid_map SEC(".maps");
0015
0016 struct {
0017     __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
0018     __type(key, int);
0019     __type(value, int);
0020 } perf_buf_map SEC(".maps");
0021
0022 SEC("tp/raw_syscalls/sys_enter")
0023 int handle_sys_enter(void *ctx)
0024 {
0025     int zero = 0, *my_pid, cur_pid;
0026     int cpu = bpf_get_smp_processor_id();
0027
0028     my_pid = bpf_map_lookup_elem(&my_pid_map, &zero);
0029     if (!my_pid)
0030         return 1;
0031
0032     cur_pid = bpf_get_current_pid_tgid() >> 32;
0033     if (cur_pid != *my_pid)
0034         return 1;
0035
0036     bpf_perf_event_output(ctx, &perf_buf_map, BPF_F_CURRENT_CPU,
0037                   &cpu, sizeof(cpu));
0038     return 1;
0039 }
0040
0041 char _license[] SEC("license") = "GPL";