diff options
Diffstat (limited to 'tools/perf/util/bpf_skel/bperf_follower.bpf.c')
| -rw-r--r-- | tools/perf/util/bpf_skel/bperf_follower.bpf.c | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/tools/perf/util/bpf_skel/bperf_follower.bpf.c b/tools/perf/util/bpf_skel/bperf_follower.bpf.c new file mode 100644 index 000000000000..0595063139a3 --- /dev/null +++ b/tools/perf/util/bpf_skel/bperf_follower.bpf.c @@ -0,0 +1,162 @@ +// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +// Copyright (c) 2021 Facebook +#include "vmlinux.h" +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h> +#include "bperf_u.h" + +#define MAX_ENTRIES 102400 + +struct { + __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); + __uint(key_size, sizeof(__u32)); + __uint(value_size, sizeof(struct bpf_perf_event_value)); + __uint(max_entries, 1); +} diff_readings SEC(".maps"); + +struct { + __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); + __uint(key_size, sizeof(__u32)); + __uint(value_size, sizeof(struct bpf_perf_event_value)); + __uint(max_entries, 1); +} accum_readings SEC(".maps"); + +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __uint(key_size, sizeof(__u32)); + __uint(value_size, sizeof(struct bperf_filter_value)); + __uint(max_entries, MAX_ENTRIES); + __uint(map_flags, BPF_F_NO_PREALLOC); +} filter SEC(".maps"); + +enum bperf_filter_type type = 0; +int enabled = 0; +int inherit; + +SEC("fexit/XXX") +int BPF_PROG(fexit_XXX) +{ + struct bpf_perf_event_value *diff_val, *accum_val; + __u32 filter_key, zero = 0; + __u32 accum_key; + struct bperf_filter_value *fval; + + if (!enabled) + return 0; + + switch (type) { + case BPERF_FILTER_GLOBAL: + accum_key = zero; + goto do_add; + case BPERF_FILTER_CPU: + filter_key = bpf_get_smp_processor_id(); + break; + case BPERF_FILTER_PID: + filter_key = bpf_get_current_pid_tgid() & 0xffffffff; + break; + case BPERF_FILTER_TGID: + /* Use pid as the filter_key to exclude new task counts + * when inherit is disabled. Don't worry about the existing + * children in TGID losing their counts, bpf_counter has + * already added them to the filter map via perf_thread_map + * before this bpf prog runs. + */ + filter_key = inherit ? + bpf_get_current_pid_tgid() >> 32 : + bpf_get_current_pid_tgid() & 0xffffffff; + break; + default: + return 0; + } + + fval = bpf_map_lookup_elem(&filter, &filter_key); + if (!fval) + return 0; + + accum_key = fval->accum_key; + if (fval->exited) + bpf_map_delete_elem(&filter, &filter_key); + +do_add: + diff_val = bpf_map_lookup_elem(&diff_readings, &zero); + if (!diff_val) + return 0; + + accum_val = bpf_map_lookup_elem(&accum_readings, &accum_key); + if (!accum_val) + return 0; + + accum_val->counter += diff_val->counter; + accum_val->enabled += diff_val->enabled; + accum_val->running += diff_val->running; + + return 0; +} + +/* The program is only used for PID or TGID filter types. */ +SEC("tp_btf/task_newtask") +int BPF_PROG(on_newtask, struct task_struct *task, __u64 clone_flags) +{ + __u32 parent_key, child_key; + struct bperf_filter_value *parent_fval; + struct bperf_filter_value child_fval = { 0 }; + + if (!enabled) + return 0; + + switch (type) { + case BPERF_FILTER_PID: + parent_key = bpf_get_current_pid_tgid() & 0xffffffff; + child_key = task->pid; + break; + case BPERF_FILTER_TGID: + parent_key = bpf_get_current_pid_tgid() >> 32; + child_key = task->tgid; + if (child_key == parent_key) + return 0; + break; + default: + return 0; + } + + /* Check if the current task is one of the target tasks to be counted */ + parent_fval = bpf_map_lookup_elem(&filter, &parent_key); + if (!parent_fval) + return 0; + + /* Start counting for the new task by adding it into filter map, + * inherit the accum key of its parent task so that they can be + * counted together. + */ + child_fval.accum_key = parent_fval->accum_key; + child_fval.exited = 0; + bpf_map_update_elem(&filter, &child_key, &child_fval, BPF_NOEXIST); + + return 0; +} + +/* The program is only used for PID or TGID filter types. */ +SEC("tp_btf/sched_process_exit") +int BPF_PROG(on_exittask, struct task_struct *task) +{ + __u32 pid; + struct bperf_filter_value *fval; + + if (!enabled) + return 0; + + /* Stop counting for this task by removing it from filter map. + * For TGID type, if the pid can be found in the map, it means that + * this pid belongs to the leader task. After the task exits, the + * tgid of its child tasks (if any) will be 1, so the pid can be + * safely removed. + */ + pid = task->pid; + fval = bpf_map_lookup_elem(&filter, &pid); + if (fval) + fval->exited = 1; + + return 0; +} + +char LICENSE[] SEC("license") = "Dual BSD/GPL"; |