1// SPDX-License-Identifier: GPL-2.0
2// Copyright (c) 2019 Facebook
3
4#include <linux/ptrace.h>
5#include <linux/bpf.h>
6#include <bpf/bpf_helpers.h>
7
8const struct {
9	unsigned a[4];
10	/*
11	 * if the struct's size is multiple of 16, compiler will put it into
12	 * .rodata.cst16 section, which is not recognized by libbpf; work
13	 * around this by ensuring we don't have 16-aligned struct
14	 */
15	char _y;
16} rdonly_values = { .a = {2, 3, 4, 5} };
17
18struct {
19	unsigned did_run;
20	unsigned iters;
21	unsigned sum;
22} res = {};
23
24SEC("raw_tracepoint/sys_enter:skip_loop")
25int skip_loop(struct pt_regs *ctx)
26{
27	/* prevent compiler to optimize everything out */
28	unsigned * volatile p = (void *)&rdonly_values.a;
29	unsigned iters = 0, sum = 0;
30
31	/* we should never enter this loop */
32	while (*p & 1) {
33		iters++;
34		sum += *p;
35		p++;
36	}
37	res.did_run = 1;
38	res.iters = iters;
39	res.sum = sum;
40	return 0;
41}
42
43SEC("raw_tracepoint/sys_enter:part_loop")
44int part_loop(struct pt_regs *ctx)
45{
46	/* prevent compiler to optimize everything out */
47	unsigned * volatile p = (void *)&rdonly_values.a;
48	unsigned iters = 0, sum = 0;
49
50	/* validate verifier can derive loop termination */
51	while (*p < 5) {
52		iters++;
53		sum += *p;
54		p++;
55	}
56	res.did_run = 1;
57	res.iters = iters;
58	res.sum = sum;
59	return 0;
60}
61
62SEC("raw_tracepoint/sys_enter:full_loop")
63int full_loop(struct pt_regs *ctx)
64{
65	/* prevent compiler to optimize everything out */
66	unsigned * volatile p = (void *)&rdonly_values.a;
67	int i = sizeof(rdonly_values.a) / sizeof(rdonly_values.a[0]);
68	unsigned iters = 0, sum = 0;
69
70	/* validate verifier can allow full loop as well */
71	while (i > 0 ) {
72		iters++;
73		sum += *p;
74		p++;
75		i--;
76	}
77	res.did_run = 1;
78	res.iters = iters;
79	res.sum = sum;
80	return 0;
81}
82
83char _license[] SEC("license") = "GPL";
84