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, 24 insertions, 0 deletions

diff --git a/fs/ntfs/reparse.h b/fs/ntfs/reparse.h
new file mode 100644
index 000000000..c11a5bb7e
--- /dev/null
+++ b/fs/ntfs/reparse.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (c) 2008-2021 Jean-Pierre Andre
+ * Copyright (c) 2025 LG Electronics Co., Ltd.
+ */
+
+#ifndef _LINUX_NTFS_REPARSE_H
+#define _LINUX_NTFS_REPARSE_H
+
+extern __le16 reparse_index_name[];
+
+unsigned int ntfs_make_symlink(struct ntfs_inode *ni);
+unsigned int ntfs_reparse_tag_dt_types(struct ntfs_volume *vol, unsigned long mref);
+int ntfs_translate_symlink_path(struct dentry *dentry, const char *target,
+				char **translated);
+int ntfs_reparse_set_wsl_symlink(struct ntfs_inode *ni,
+				 const char *target, int target_len);
+int ntfs_reparse_set_native_symlink(struct ntfs_inode *ni,
+				    const char *symname, int symlen);
+int ntfs_reparse_set_wsl_not_symlink(struct ntfs_inode *ni, mode_t mode);
+int ntfs_delete_reparse_index(struct ntfs_inode *ni);
+int ntfs_remove_ntfs_reparse_data(struct ntfs_inode *ni);
+
+#endif /* _LINUX_NTFS_REPARSE_H */