1 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) 2 // Copyright (c) 2021 Google 3 #include "vmlinux.h" 4 #include <bpf/bpf_helpers.h> 5 #include <bpf/bpf_tracing.h> 6 7 // This should be in sync with "util/ftrace.h" 8 #define NUM_BUCKET 22 9 10 struct { 11 __uint(type, BPF_MAP_TYPE_HASH); 12 __uint(key_size, sizeof(__u64)); 13 __uint(value_size, sizeof(__u64)); 14 __uint(max_entries, 10000); 15 } functime SEC(".maps"); 16 17 struct { 18 __uint(type, BPF_MAP_TYPE_HASH); 19 __uint(key_size, sizeof(__u32)); 20 __uint(value_size, sizeof(__u8)); 21 __uint(max_entries, 1); 22 } cpu_filter SEC(".maps"); 23 24 struct { 25 __uint(type, BPF_MAP_TYPE_HASH); 26 __uint(key_size, sizeof(__u32)); 27 __uint(value_size, sizeof(__u8)); 28 __uint(max_entries, 1); 29 } task_filter SEC(".maps"); 30 31 struct { 32 __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); 33 __uint(key_size, sizeof(__u32)); 34 __uint(value_size, sizeof(__u64)); 35 __uint(max_entries, NUM_BUCKET); 36 } latency SEC(".maps"); 37 38 39 int enabled = 0; 40 int has_cpu = 0; 41 int has_task = 0; 42 int use_nsec = 0; 43 44 SEC("kprobe/func") 45 int BPF_PROG(func_begin) 46 { 47 __u64 key, now; 48 49 if (!enabled) 50 return 0; 51 52 key = bpf_get_current_pid_tgid(); 53 54 if (has_cpu) { 55 __u32 cpu = bpf_get_smp_processor_id(); 56 __u8 *ok; 57 58 ok = bpf_map_lookup_elem(&cpu_filter, &cpu); 59 if (!ok) 60 return 0; 61 } 62 63 if (has_task) { 64 __u32 pid = key & 0xffffffff; 65 __u8 *ok; 66 67 ok = bpf_map_lookup_elem(&task_filter, &pid); 68 if (!ok) 69 return 0; 70 } 71 72 now = bpf_ktime_get_ns(); 73 74 // overwrite timestamp for nested functions 75 bpf_map_update_elem(&functime, &key, &now, BPF_ANY); 76 return 0; 77 } 78 79 SEC("kretprobe/func") 80 int BPF_PROG(func_end) 81 { 82 __u64 tid; 83 __u64 *start; 84 __u64 cmp_base = use_nsec ? 1 : 1000; 85 86 if (!enabled) 87 return 0; 88 89 tid = bpf_get_current_pid_tgid(); 90 91 start = bpf_map_lookup_elem(&functime, &tid); 92 if (start) { 93 __s64 delta = bpf_ktime_get_ns() - *start; 94 __u32 key; 95 __u64 *hist; 96 97 bpf_map_delete_elem(&functime, &tid); 98 99 if (delta < 0) 100 return 0; 101 102 // calculate index using delta 103 for (key = 0; key < (NUM_BUCKET - 1); key++) { 104 if (delta < (cmp_base << key)) 105 break; 106 } 107 108 hist = bpf_map_lookup_elem(&latency, &key); 109 if (!hist) 110 return 0; 111 112 *hist += 1; 113 } 114 115 return 0; 116 } 117