LXR linux/tools/testing/selftests/bpf/progs/bpf_iter_task

   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}
  38