tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c

   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
   7 char _license[] SEC("license") = "GPL";
   8
   9 #define MAX_STACK_TRACE_DEPTH   64
  10 unsigned long entries[MAX_STACK_TRACE_DEPTH] = {};
  11 #define SIZE_OF_ULONG (sizeof(unsigned long))
  12
  13 SEC("iter/task")
  14 int 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 }