| // SPDX-License-Identifier: GPL-3.0 |
| // Copyright (c) 2022 Nicolas Sterchele |
| #include "vmlinux.h" |
| #include <bpf/bpf_helpers.h> |
| #include <bpf/bpf_core_read.h> |
| #include <bpf/bpf_tracing.h> |
| #include "wakeuptime.h" |
| #include "maps.bpf.h" |
| |
| #define PF_KTHREAD 0x00200000 /* kernel thread */ |
| |
| const volatile pid_t targ_pid = 0; |
| const volatile __u64 max_block_ns = -1; |
| const volatile __u64 min_block_ns = 1; |
| const volatile bool user_threads_only = false; |
| |
| struct { |
| __uint(type, BPF_MAP_TYPE_HASH); |
| __uint(max_entries, MAX_ENTRIES); |
| __type(key, struct key_t); |
| __type(value, u64); |
| } counts SEC(".maps"); |
| |
| struct { |
| __uint(type, BPF_MAP_TYPE_HASH); |
| __uint(max_entries, MAX_ENTRIES); |
| __type(key, u32); |
| __type(value, u64); |
| } start SEC(".maps"); |
| |
| struct { |
| __uint(type, BPF_MAP_TYPE_STACK_TRACE); |
| __uint(key_size, sizeof(u32)); |
| } stackmap SEC(".maps"); |
| |
| static int offcpu_sched_switch(struct task_struct *prev) |
| { |
| u64 pid_tgid = bpf_get_current_pid_tgid(); |
| u32 pid = pid_tgid >> 32; |
| u32 tid = (u32)pid_tgid; |
| u64 ts; |
| |
| if (targ_pid && targ_pid != pid) |
| return 0; |
| |
| if (user_threads_only && prev->flags & PF_KTHREAD) |
| return 0; |
| |
| ts = bpf_ktime_get_ns(); |
| bpf_map_update_elem(&start, &tid, &ts, BPF_ANY); |
| return 0; |
| } |
| |
| static int wakeup(void *ctx, struct task_struct *p) |
| { |
| u32 pid = p->tgid; |
| u32 tid = p->pid; |
| u64 delta, *count_key, *tsp; |
| static const u64 zero; |
| struct key_t key = {}; |
| |
| if (targ_pid && targ_pid != pid) |
| return 0; |
| tsp = bpf_map_lookup_elem(&start, &tid); |
| if (tsp == 0) |
| return 0; |
| bpf_map_delete_elem(&start, &tid); |
| |
| delta = bpf_ktime_get_ns() - *tsp; |
| if ((delta < min_block_ns) || (delta > max_block_ns)) |
| return 0; |
| |
| key.w_k_stack_id = bpf_get_stackid(ctx, &stackmap, 0); |
| bpf_probe_read_kernel(&key.target, sizeof(key.target), p->comm); |
| bpf_get_current_comm(&key.waker, sizeof(key.waker)); |
| |
| count_key = bpf_map_lookup_or_try_init(&counts, &key, &zero); |
| if (count_key) |
| __atomic_add_fetch(count_key, delta, __ATOMIC_RELAXED); |
| |
| return 0; |
| } |
| |
| |
| SEC("tp_btf/sched_switch") |
| int BPF_PROG(sched_switch, bool preempt, struct task_struct *prev, struct task_struct *next) |
| { |
| return offcpu_sched_switch(prev); |
| } |
| |
| SEC("tp_btf/sched_wakeup") |
| int BPF_PROG(sched_wakeup, struct task_struct *p) |
| { |
| return wakeup(ctx, p); |
| } |
| |
| char LICENSE[] SEC("license") = "GPL"; |