1 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) 2 // Copyright (c) 2020 Facebook 3 #include <linux/bpf.h> 4 #include <bpf/bpf_helpers.h> 5 #include <bpf/bpf_tracing.h> 6 7 /* map of perf event fds, num_cpu * num_metric entries */ 8 struct { 9 __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY); 10 __uint(key_size, sizeof(__u32)); 11 __uint(value_size, sizeof(int)); 12 } events SEC(".maps"); 13 14 /* readings at fentry */ 15 struct { 16 __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); 17 __uint(key_size, sizeof(__u32)); 18 __uint(value_size, sizeof(struct bpf_perf_event_value)); 19 __uint(max_entries, 1); 20 } fentry_readings SEC(".maps"); 21 22 /* accumulated readings */ 23 struct { 24 __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); 25 __uint(key_size, sizeof(__u32)); 26 __uint(value_size, sizeof(struct bpf_perf_event_value)); 27 __uint(max_entries, 1); 28 } accum_readings SEC(".maps"); 29 30 const volatile __u32 num_cpu = 1; 31 32 SEC("fentry/XXX") 33 int BPF_PROG(fentry_XXX) 34 { 35 __u32 key = bpf_get_smp_processor_id(); 36 struct bpf_perf_event_value *ptr; 37 __u32 zero = 0; 38 long err; 39 40 /* look up before reading, to reduce error */ 41 ptr = bpf_map_lookup_elem(&fentry_readings, &zero); 42 if (!ptr) 43 return 0; 44 45 err = bpf_perf_event_read_value(&events, key, ptr, sizeof(*ptr)); 46 if (err) 47 return 0; 48 49 return 0; 50 } 51 52 static inline void 53 fexit_update_maps(struct bpf_perf_event_value *after) 54 { 55 struct bpf_perf_event_value *before, diff, *accum; 56 __u32 zero = 0; 57 58 before = bpf_map_lookup_elem(&fentry_readings, &zero); 59 /* only account samples with a valid fentry_reading */ 60 if (before && before->counter) { 61 struct bpf_perf_event_value *accum; 62 63 diff.counter = after->counter - before->counter; 64 diff.enabled = after->enabled - before->enabled; 65 diff.running = after->running - before->running; 66 67 accum = bpf_map_lookup_elem(&accum_readings, &zero); 68 if (accum) { 69 accum->counter += diff.counter; 70 accum->enabled += diff.enabled; 71 accum->running += diff.running; 72 } 73 } 74 } 75 76 SEC("fexit/XXX") 77 int BPF_PROG(fexit_XXX) 78 { 79 struct bpf_perf_event_value reading; 80 __u32 cpu = bpf_get_smp_processor_id(); 81 __u32 one = 1, zero = 0; 82 int err; 83 84 /* read all events before updating the maps, to reduce error */ 85 err = bpf_perf_event_read_value(&events, cpu, &reading, sizeof(reading)); 86 if (err) 87 return 0; 88 89 fexit_update_maps(&reading); 90 return 0; 91 } 92 93 char LICENSE[] SEC("license") = "Dual BSD/GPL"; 94