bpf: Add namespace to BPF internal symbols

Add namespace to BPF internal symbols used by light skeleton
to prevent abuse and document with the code their allowed usage.

Fixes: b1d18a7574d0 ("bpf: Extend sys_bpf commands for bpf_syscall programs.")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/20250425014542.62385-1-alexei.starovoitov@gmail.com

1 files changed, 8 insertions, 0 deletions

diff --git a/Documentation/bpf/bpf_devel_QA.rst b/Documentation/bpf/bpf_devel_QA.rst
index de27e1620821..0acb4c9b8d90 100644
--- a/Documentation/bpf/bpf_devel_QA.rst
+++ b/Documentation/bpf/bpf_devel_QA.rst
@@ -382,6 +382,14 @@ In case of new BPF instructions, once the changes have been accepted
 into the Linux kernel, please implement support into LLVM's BPF back
 end. See LLVM_ section below for further information.
 
+Q: What "BPF_INTERNAL" symbol namespace is for?
+-----------------------------------------------
+A: Symbols exported as BPF_INTERNAL can only be used by BPF infrastructure
+like preload kernel modules with light skeleton. Most symbols outside
+of BPF_INTERNAL are not expected to be used by code outside of BPF either.
+Symbols may lack the designation because they predate the namespaces,
+or due to an oversight.
+
 Stable submission
 =================