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 /* libbpf will adjust to valid page size */ 19 __uint(max_entries, 1000); 20 } ringbuf1 SEC(".maps"), 21 ringbuf2 SEC(".maps"); 22 23 struct { 24 __uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS); 25 __uint(max_entries, 4); 26 __type(key, int); 27 __array(values, struct ringbuf_map); 28 } ringbuf_arr SEC(".maps") = { 29 .values = { 30 [0] = &ringbuf1, 31 [2] = &ringbuf2, 32 }, 33 }; 34 35 struct { 36 __uint(type, BPF_MAP_TYPE_HASH_OF_MAPS); 37 __uint(max_entries, 1); 38 __type(key, int); 39 __array(values, struct ringbuf_map); 40 } ringbuf_hash SEC(".maps") = { 41 .values = { 42 [0] = &ringbuf1, 43 }, 44 }; 45 46 /* inputs */ 47 int pid = 0; 48 int target_ring = 0; 49 long value = 0; 50 51 /* outputs */ 52 long total = 0; 53 long dropped = 0; 54 long skipped = 0; 55 56 SEC("tp/syscalls/sys_enter_getpgid") 57 int test_ringbuf(void *ctx) 58 { 59 int cur_pid = bpf_get_current_pid_tgid() >> 32; 60 struct sample *sample; 61 void *rb; 62 63 if (cur_pid != pid) 64 return 0; 65 66 rb = bpf_map_lookup_elem(&ringbuf_arr, &target_ring); 67 if (!rb) { 68 skipped += 1; 69 return 1; 70 } 71 72 sample = bpf_ringbuf_reserve(rb, sizeof(*sample), 0); 73 if (!sample) { 74 dropped += 1; 75 return 1; 76 } 77 78 sample->pid = pid; 79 bpf_get_current_comm(sample->comm, sizeof(sample->comm)); 80 sample->value = value; 81 82 sample->seq = total; 83 total += 1; 84 85 bpf_ringbuf_submit(sample, 0); 86 87 return 0; 88 } 89