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}

 1// SPDX-License-Identifier: GPL-2.0
 2/* Copyright (c) 2020 Facebook */
 3#include "bpf_iter.h"
 4#include <bpf/bpf_helpers.h>
 
 5
 6char _license[] SEC("license") = "GPL";
 7
 8#define MAX_STACK_TRACE_DEPTH   64
 9unsigned long entries[MAX_STACK_TRACE_DEPTH] = {};
10#define SIZE_OF_ULONG (sizeof(unsigned long))
11
12SEC("iter/task")
13int dump_task_stack(struct bpf_iter__task *ctx)
14{
15	struct seq_file *seq = ctx->meta->seq;
16	struct task_struct *task = ctx->task;
17	long i, retlen;
18
19	if (task == (void *)0)
20		return 0;
21
22	retlen = bpf_get_task_stack(task, entries,
23				    MAX_STACK_TRACE_DEPTH * SIZE_OF_ULONG, 0);
24	if (retlen < 0)
25		return 0;
26
27	BPF_SEQ_PRINTF(seq, "pid: %8u num_entries: %8u\n", task->pid,
28		       retlen / SIZE_OF_ULONG);
29	for (i = 0; i < MAX_STACK_TRACE_DEPTH; i++) {
30		if (retlen > i * SIZE_OF_ULONG)
31			BPF_SEQ_PRINTF(seq, "[<0>] %pB\n", (void *)entries[i]);
32	}
33	BPF_SEQ_PRINTF(seq, "\n");
34
35	return 0;
36}
37
38SEC("iter/task")
39int get_task_user_stacks(struct bpf_iter__task *ctx)
40{
41	struct seq_file *seq = ctx->meta->seq;
42	struct task_struct *task = ctx->task;
43	uint64_t buf_sz = 0;
44	int64_t res;
45
46	if (task == (void *)0)
47		return 0;
48
49	res = bpf_get_task_stack(task, entries,
50			MAX_STACK_TRACE_DEPTH * SIZE_OF_ULONG, BPF_F_USER_STACK);
51	if (res <= 0)
52		return 0;
53
54	buf_sz += res;
55
56	/* If the verifier doesn't refine bpf_get_task_stack res, and instead
57	 * assumes res is entirely unknown, this program will fail to load as
58	 * the verifier will believe that max buf_sz value allows reading
59	 * past the end of entries in bpf_seq_write call
60	 */
61	bpf_seq_write(seq, &entries, buf_sz);
62	return 0;
63}