1 // SPDX-License-Identifier: GPL-2.0
2 // Copyright (c) 2019 Facebook
4 #include <linux/ptrace.h>
6 #include <bpf/bpf_helpers.h>
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
16 } rdonly_values = { .a = {2, 3, 4, 5} };
24 SEC("raw_tracepoint/sys_enter:skip_loop")
25 int skip_loop(struct pt_regs *ctx)
27 /* prevent compiler to optimize everything out */
28 unsigned * volatile p = (void *)&rdonly_values.a;
29 unsigned iters = 0, sum = 0;
31 /* we should never enter this loop */
43 SEC("raw_tracepoint/sys_enter:part_loop")
44 int part_loop(struct pt_regs *ctx)
46 /* prevent compiler to optimize everything out */
47 unsigned * volatile p = (void *)&rdonly_values.a;
48 unsigned iters = 0, sum = 0;
50 /* validate verifier can derive loop termination */
62 SEC("raw_tracepoint/sys_enter:full_loop")
63 int full_loop(struct pt_regs *ctx)
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;
70 /* validate verifier can allow full loop as well */
83 char _license[] SEC("license") = "GPL";