On Tue, Nov 09, 2021 at 09:19:40PM -0800, Yonghong Song wrote:
> LLVM patches ([1] for clang, [2] and [3] for BPF backend)
> added support for btf_type_tag attributes. This patch
> added support for the kernel.
>
> The main motivation for btf_type_tag is to bring kernel
> annotations __user, __rcu etc. to btf. With such information
> available in btf, bpf verifier can detect mis-usages
> and reject the program. For example, for __user tagged pointer,
> developers can then use proper helper like bpf_probe_read_kernel()
> etc. to read the data.
+#define __tag1 __attribute__((btf_type_tag("tag1")))
+#define __tag2 __attribute__((btf_type_tag("tag2")))
+
+struct btf_type_tag_test {
+ int __tag1 * __tag1 __tag2 *p;
+} g;
Can we build the kernel with the latest clang and get __user in BTF ?
