1 // SPDX-License-Identifier: GPL-2.0 2 // Copyright (c) 2020 Facebook 3 4 #include <linux/bpf.h> 5 #include <bpf/bpf_helpers.h> 6 7 char _license[] SEC("license") = "GPL"; 8 9 struct sample { 10 int pid; 11 int seq; 12 long value; 13 char comm[16]; 14 }; 15 16 struct ringbuf_map { 17 __uint(type, BPF_MAP_TYPE_RINGBUF); 18 __uint(max_entries, 1 << 12); 19 } ringbuf1 SEC(".maps"), 20 ringbuf2 SEC(".maps"); 21 22 struct { 23 __uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS); 24 __uint(max_entries, 4); 25 __type(key, int); 26 __array(values, struct ringbuf_map); 27 } ringbuf_arr SEC(".maps") = { 28 .values = { 29 [0] = &ringbuf1, 30 [2] = &ringbuf2, 31 }, 32 }; 33 34 /* inputs */ 35 int pid = 0; 36 int target_ring = 0; 37 long value = 0; 38 39 /* outputs */ 40 long total = 0; 41 long dropped = 0; 42 long skipped = 0; 43 44 SEC("tp/syscalls/sys_enter_getpgid") 45 int test_ringbuf(void *ctx) 46 { 47 int cur_pid = bpf_get_current_pid_tgid() >> 32; 48 struct sample *sample; 49 void *rb; 50 int zero = 0; 51 52 if (cur_pid != pid) 53 return 0; 54 55 rb = bpf_map_lookup_elem(&ringbuf_arr, &target_ring); 56 if (!rb) { 57 skipped += 1; 58 return 1; 59 } 60 61 sample = bpf_ringbuf_reserve(rb, sizeof(*sample), 0); 62 if (!sample) { 63 dropped += 1; 64 return 1; 65 } 66 67 sample->pid = pid; 68 bpf_get_current_comm(sample->comm, sizeof(sample->comm)); 69 sample->value = value; 70 71 sample->seq = total; 72 total += 1; 73 74 bpf_ringbuf_submit(sample, 0); 75 76 return 0; 77 } 78