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) 2024 Meta Platforms, Inc. and affiliates. */
3
4#include <vmlinux.h>
5#include <bpf/bpf_tracing.h>
6#include "bpf_misc.h"
7
8char _license[] SEC("license") = "GPL";
9
10int tid;
11int i;
12
13SEC("tp_btf/bpf_testmod_test_raw_tp_null_tp")
14int BPF_PROG(test_raw_tp_null, struct sk_buff *skb)
15{
16 struct task_struct *task = bpf_get_current_task_btf();
17
18 if (task->pid != tid)
19 return 0;
20
21 /* If dead code elimination kicks in, the increment +=2 will be
22 * removed. For raw_tp programs attaching to tracepoints in kernel
23 * modules, we mark input arguments as PTR_MAYBE_NULL, so branch
24 * prediction should never kick in.
25 */
26 asm volatile ("%[i] += 1; if %[ctx] != 0 goto +1; %[i] += 2;"
27 : [i]"+r"(i)
28 : [ctx]"r"(skb)
29 : "memory");
30 return 0;
31}