kbuild: rust: keep Rust objects out of Clang LTO with inline helpersgrafted

Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit
`objtool` errors such as:

    vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a:
    can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd

The reason is that in such builds, the Clang invocation that compiles
the combined Rust plus helpers bitcode emits LLVM bitcode (again) --
the final code generation happens in the linker's LTO step, which the
`-mllvm` trap options passed to Clang do not reach.

This, in turn, means that unreachable traps are missing, and the
impossible paths do not merely fallthrough to the next symbol, but past
the end of their own section, since LTO builds place each function in
its own section.

Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always
emits machine code directly, with the traps in place.

Assisted-by: LLM
Cc: Gary Guo <gary@garyguo.net>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust")
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 70 insertions, 0 deletions

diff --git a/fs/smb/server/auth.h b/fs/smb/server/auth.h
new file mode 100644
index 000000000..f14b7c033
--- /dev/null
+++ b/fs/smb/server/auth.h
@@ -0,0 +1,70 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *   Copyright (C) 2018 Samsung Electronics Co., Ltd.
+ */
+
+#ifndef __AUTH_H__
+#define __AUTH_H__
+
+#include "ntlmssp.h"
+
+#ifdef CONFIG_SMB_SERVER_KERBEROS5
+#define AUTH_GSS_LENGTH		96
+#define AUTH_GSS_PADDING	0
+#else
+#define AUTH_GSS_LENGTH		74
+#define AUTH_GSS_PADDING	6
+#endif
+
+#define CIFS_HMAC_MD5_HASH_SIZE	(16)
+#define CIFS_NTHASH_SIZE	(16)
+
+/*
+ * Size of the ntlm client response
+ */
+#define CIFS_AUTH_RESP_SIZE		24
+#define CIFS_SMB1_SIGNATURE_SIZE	8
+#define CIFS_SMB1_SESSKEY_SIZE		16
+
+#define KSMBD_AUTH_NTLMSSP	0x0001
+#define KSMBD_AUTH_KRB5		0x0002
+#define KSMBD_AUTH_MSKRB5	0x0004
+#define KSMBD_AUTH_KRB5U2U	0x0008
+
+struct ksmbd_session;
+struct ksmbd_conn;
+struct ksmbd_work;
+struct kvec;
+
+int ksmbd_crypt_message(struct ksmbd_work *work, struct kvec *iov,
+			unsigned int nvec, int enc);
+void ksmbd_copy_gss_neg_header(void *buf);
+int ksmbd_auth_ntlmv2(struct ksmbd_conn *conn, struct ksmbd_session *sess,
+		      struct ntlmv2_resp *ntlmv2, int blen, char *domain_name,
+		      char *cryptkey, char *sess_key);
+int ksmbd_decode_ntlmssp_auth_blob(struct authenticate_message *authblob,
+				   int blob_len, struct ksmbd_conn *conn,
+				   struct ksmbd_session *sess, char *sess_key);
+int ksmbd_decode_ntlmssp_neg_blob(struct negotiate_message *negblob,
+				  int blob_len, struct ksmbd_conn *conn);
+unsigned int
+ksmbd_build_ntlmssp_challenge_blob(struct challenge_message *chgblob,
+				   struct ksmbd_conn *conn);
+int ksmbd_krb5_authenticate(struct ksmbd_session *sess, char *in_blob,
+			    int in_len, char *out_blob, int *out_len,
+			    char *sess_key);
+void ksmbd_sign_smb2_pdu(struct ksmbd_conn *conn, char *key, struct kvec *iov,
+			 int n_vec, char *sig);
+void ksmbd_sign_smb3_pdu(struct ksmbd_conn *conn, char *key, struct kvec *iov,
+			 int n_vec, char *sig);
+int ksmbd_gen_smb30_signingkey(struct ksmbd_session *sess,
+			       struct ksmbd_conn *conn);
+int ksmbd_gen_smb311_signingkey(struct ksmbd_session *sess,
+				struct ksmbd_conn *conn);
+void ksmbd_gen_smb30_encryptionkey(struct ksmbd_conn *conn,
+				   struct ksmbd_session *sess);
+void ksmbd_gen_smb311_encryptionkey(struct ksmbd_conn *conn,
+				    struct ksmbd_session *sess);
+int ksmbd_gen_preauth_integrity_hash(struct ksmbd_conn *conn, char *buf,
+				     __u8 *pi_hash);
+#endif