bpf-developer-tutorial/12-profile/profile.bpf.c

// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
/* Copyright (c) 2022 Meta Platforms, Inc. */
#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
#include <bpf/bpf_core_read.h>

#include "profile.h"

char LICENSE[] SEC("license") = "Dual BSD/GPL";

struct {
	__uint(type, BPF_MAP_TYPE_RINGBUF);
	__uint(max_entries, 256 * 1024);
} events SEC(".maps");

SEC("perf_event")
int profile(void *ctx)
{
	int pid = bpf_get_current_pid_tgid() >> 32;
	int cpu_id = bpf_get_smp_processor_id();
	struct stacktrace_event *event;
	int cp;

	event = bpf_ringbuf_reserve(&events, sizeof(*event), 0);
	if (!event)
		return 1;

	event->pid = pid;
	event->cpu_id = cpu_id;

	if (bpf_get_current_comm(event->comm, sizeof(event->comm)))
		event->comm[0] = 0;

	event->kstack_sz = bpf_get_stack(ctx, event->kstack, sizeof(event->kstack), 0);

	event->ustack_sz = bpf_get_stack(ctx, event->ustack, sizeof(event->ustack), BPF_F_USER_STACK);

	bpf_ringbuf_submit(event, 0);

	return 0;
}