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1// SPDX-License-Identifier: GPL-2.02// Copyright (c) 2018 Facebook3 4#include <vmlinux.h>5#include <bpf/bpf_helpers.h>6 7#ifndef PERF_MAX_STACK_DEPTH8#define PERF_MAX_STACK_DEPTH 1279#endif10 11struct {12 __uint(type, BPF_MAP_TYPE_ARRAY);13 __uint(max_entries, 1);14 __type(key, __u32);15 __type(value, __u32);16} control_map SEC(".maps");17 18struct {19 __uint(type, BPF_MAP_TYPE_HASH);20 __uint(max_entries, 16384);21 __type(key, __u32);22 __type(value, __u32);23} stackid_hmap SEC(".maps");24 25typedef __u64 stack_trace_t[PERF_MAX_STACK_DEPTH];26 27struct {28 __uint(type, BPF_MAP_TYPE_STACK_TRACE);29 __uint(max_entries, 16384);30 __type(key, __u32);31 __type(value, stack_trace_t);32} stackmap SEC(".maps");33 34struct {35 __uint(type, BPF_MAP_TYPE_ARRAY);36 __uint(max_entries, 16384);37 __type(key, __u32);38 __type(value, stack_trace_t);39} stack_amap SEC(".maps");40 41/* taken from /sys/kernel/tracing/events/sched/sched_switch/format */42struct sched_switch_args {43 unsigned long long pad;44 char prev_comm[TASK_COMM_LEN];45 int prev_pid;46 int prev_prio;47 long long prev_state;48 char next_comm[TASK_COMM_LEN];49 int next_pid;50 int next_prio;51};52 53SEC("tracepoint/sched/sched_switch")54int oncpu(struct sched_switch_args *ctx)55{56 __u32 max_len = PERF_MAX_STACK_DEPTH * sizeof(__u64);57 __u32 key = 0, val = 0, *value_p;58 void *stack_p;59 60 value_p = bpf_map_lookup_elem(&control_map, &key);61 if (value_p && *value_p)62 return 0; /* skip if non-zero *value_p */63 64 /* The size of stackmap and stackid_hmap should be the same */65 key = bpf_get_stackid(ctx, &stackmap, 0);66 if ((int)key >= 0) {67 bpf_map_update_elem(&stackid_hmap, &key, &val, 0);68 stack_p = bpf_map_lookup_elem(&stack_amap, &key);69 if (stack_p)70 bpf_get_stack(ctx, stack_p, max_len, 0);71 }72 73 return 0;74}75 76char _license[] SEC("license") = "GPL";77