| // SPDX-License-Identifier: GPL-2.0 |
| // Copyright (c) 2018 Facebook |
| |
| #include <linux/bpf.h> |
| #include <bpf/bpf_helpers.h> |
| |
| #ifndef PERF_MAX_STACK_DEPTH |
| #define PERF_MAX_STACK_DEPTH 127 |
| #endif |
| |
| struct { |
| __uint(type, BPF_MAP_TYPE_ARRAY); |
| __uint(max_entries, 1); |
| __type(key, __u32); |
| __type(value, __u32); |
| } control_map SEC(".maps"); |
| |
| struct { |
| __uint(type, BPF_MAP_TYPE_HASH); |
| __uint(max_entries, 16384); |
| __type(key, __u32); |
| __type(value, __u32); |
| } stackid_hmap SEC(".maps"); |
| |
| typedef __u64 stack_trace_t[PERF_MAX_STACK_DEPTH]; |
| |
| struct { |
| __uint(type, BPF_MAP_TYPE_STACK_TRACE); |
| __uint(max_entries, 16384); |
| __type(key, __u32); |
| __type(value, stack_trace_t); |
| } stackmap SEC(".maps"); |
| |
| struct { |
| __uint(type, BPF_MAP_TYPE_ARRAY); |
| __uint(max_entries, 16384); |
| __type(key, __u32); |
| __type(value, stack_trace_t); |
| } stack_amap SEC(".maps"); |
| |
| /* taken from /sys/kernel/debug/tracing/events/sched/sched_switch/format */ |
| struct sched_switch_args { |
| unsigned long long pad; |
| char prev_comm[16]; |
| int prev_pid; |
| int prev_prio; |
| long long prev_state; |
| char next_comm[16]; |
| int next_pid; |
| int next_prio; |
| }; |
| |
| SEC("tracepoint/sched/sched_switch") |
| int oncpu(struct sched_switch_args *ctx) |
| { |
| __u32 max_len = PERF_MAX_STACK_DEPTH * sizeof(__u64); |
| __u32 key = 0, val = 0, *value_p; |
| void *stack_p; |
| |
| value_p = bpf_map_lookup_elem(&control_map, &key); |
| if (value_p && *value_p) |
| return 0; /* skip if non-zero *value_p */ |
| |
| /* The size of stackmap and stackid_hmap should be the same */ |
| key = bpf_get_stackid(ctx, &stackmap, 0); |
| if ((int)key >= 0) { |
| bpf_map_update_elem(&stackid_hmap, &key, &val, 0); |
| stack_p = bpf_map_lookup_elem(&stack_amap, &key); |
| if (stack_p) |
| bpf_get_stack(ctx, stack_p, max_len, 0); |
| } |
| |
| return 0; |
| } |
| |
| char _license[] SEC("license") = "GPL"; |