1 // SPDX-License-Identifier: GPL-2.0 2 // Copyright (c) 2018 Facebook 3 4 #include <linux/bpf.h> 5 #include "bpf_helpers.h" 6 7 #ifndef PERF_MAX_STACK_DEPTH 8 #define PERF_MAX_STACK_DEPTH 127 9 #endif 10 11 struct bpf_map_def SEC("maps") control_map = { 12 .type = BPF_MAP_TYPE_ARRAY, 13 .key_size = sizeof(__u32), 14 .value_size = sizeof(__u32), 15 .max_entries = 1, 16 }; 17 18 struct bpf_map_def SEC("maps") stackid_hmap = { 19 .type = BPF_MAP_TYPE_HASH, 20 .key_size = sizeof(__u32), 21 .value_size = sizeof(__u32), 22 .max_entries = 16384, 23 }; 24 25 struct bpf_map_def SEC("maps") stackmap = { 26 .type = BPF_MAP_TYPE_STACK_TRACE, 27 .key_size = sizeof(__u32), 28 .value_size = sizeof(__u64) * PERF_MAX_STACK_DEPTH, 29 .max_entries = 16384, 30 }; 31 32 struct bpf_map_def SEC("maps") stack_amap = { 33 .type = BPF_MAP_TYPE_ARRAY, 34 .key_size = sizeof(__u32), 35 .value_size = sizeof(__u64) * PERF_MAX_STACK_DEPTH, 36 .max_entries = 16384, 37 }; 38 39 /* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */ 40 struct sched_switch_args { 41 unsigned long long pad; 42 char prev_comm[16]; 43 int prev_pid; 44 int prev_prio; 45 long long prev_state; 46 char next_comm[16]; 47 int next_pid; 48 int next_prio; 49 }; 50 51 SEC("tracepoint/sched/sched_switch") 52 int oncpu(struct sched_switch_args *ctx) 53 { 54 __u32 max_len = PERF_MAX_STACK_DEPTH * sizeof(__u64); 55 __u32 key = 0, val = 0, *value_p; 56 void *stack_p; 57 58 value_p = bpf_map_lookup_elem(&control_map, &key); 59 if (value_p && *value_p) 60 return 0; /* skip if non-zero *value_p */ 61 62 /* The size of stackmap and stackid_hmap should be the same */ 63 key = bpf_get_stackid(ctx, &stackmap, 0); 64 if ((int)key >= 0) { 65 bpf_map_update_elem(&stackid_hmap, &key, &val, 0); 66 stack_p = bpf_map_lookup_elem(&stack_amap, &key); 67 if (stack_p) 68 bpf_get_stack(ctx, stack_p, max_len, 0); 69 } 70 71 return 0; 72 } 73 74 char _license[] SEC("license") = "GPL"; 75 __u32 _version SEC("version") = 1; /* ignored by tracepoints, required by libbpf.a */ 76