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