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, 36 insertions, 0 deletions

diff --git a/include/sound/sof/dai-amd.h b/include/sound/sof/dai-amd.h
new file mode 100644
index 000000000..59cd01439
--- /dev/null
+++ b/include/sound/sof/dai-amd.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause) */
+/*
+ * This file is provided under a dual BSD/GPLv2 license. When using or
+ * redistributing this file, you may do so under either license.
+ *
+ * Copyright(c) 2021 Advanced Micro Devices, Inc.. All rights reserved.
+ */
+
+#ifndef __INCLUDE_SOUND_SOF_DAI_AMD_H__
+#define __INCLUDE_SOUND_SOF_DAI_AMD_H__
+
+#include <sound/sof/header.h>
+
+/* ACP Configuration Request - SOF_IPC_DAI_AMD_CONFIG */
+struct sof_ipc_dai_acp_params {
+	struct sof_ipc_hdr hdr;
+
+	uint32_t fsync_rate;    /* FSYNC frequency in Hz */
+	uint32_t tdm_slots;
+	uint32_t tdm_mode;
+} __packed;
+
+/* ACPDMIC Configuration Request - SOF_IPC_DAI_AMD_CONFIG */
+struct sof_ipc_dai_acpdmic_params {
+	uint32_t pdm_rate;
+	uint32_t pdm_ch;
+} __packed;
+
+/* ACP_SDW Configuration Request - SOF_IPC_DAI_AMD_SDW_CONFIG */
+struct sof_ipc_dai_acp_sdw_params {
+	struct sof_ipc_hdr hdr;
+	u32 rate;
+	u32 channels;
+} __packed;
+
+#endif