1// SPDX-License-Identifier: GPL-2.0
 2/* Copyright (c) 2020 Facebook */
 3#include "bpf_iter.h"
 4#include <bpf/bpf_helpers.h>
 5#include <bpf/bpf_tracing.h>
 6
 7char _license[] SEC("license") = "GPL";
 8
 9#define MAX_STACK_TRACE_DEPTH   64
10unsigned long entries[MAX_STACK_TRACE_DEPTH] = {};
11#define SIZE_OF_ULONG (sizeof(unsigned long))
12
13SEC("iter/task")
14int dump_task_stack(struct bpf_iter__task *ctx)
15{
16	struct seq_file *seq = ctx->meta->seq;
17	struct task_struct *task = ctx->task;
18	long i, retlen;
19
20	if (task == (void *)0)
21		return 0;
22
23	retlen = bpf_get_task_stack(task, entries,
24				    MAX_STACK_TRACE_DEPTH * SIZE_OF_ULONG, 0);
25	if (retlen < 0)
26		return 0;
27
28	BPF_SEQ_PRINTF(seq, "pid: %8u num_entries: %8u\n", task->pid,
29		       retlen / SIZE_OF_ULONG);
30	for (i = 0; i < MAX_STACK_TRACE_DEPTH; i++) {
31		if (retlen > i * SIZE_OF_ULONG)
32			BPF_SEQ_PRINTF(seq, "[<0>] %pB\n", (void *)entries[i]);
33	}
34	BPF_SEQ_PRINTF(seq, "\n");
35
36	return 0;
37}