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, 38 insertions, 0 deletions

diff --git a/include/sound/sdca_jack.h b/include/sound/sdca_jack.h
new file mode 100644
index 000000000..871ba2d81
--- /dev/null
+++ b/include/sound/sdca_jack.h
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * The MIPI SDCA specification is available for public downloads at
+ * https://www.mipi.org/mipi-sdca-v1-0-download
+ *
+ * Copyright (C) 2025 Cirrus Logic, Inc. and
+ *                    Cirrus Logic International Semiconductor Ltd.
+ */
+
+#ifndef __SDCA_JACK_H__
+#define __SDCA_JACK_H__
+
+struct sdca_interrupt;
+struct snd_kcontrol;
+struct snd_soc_jack;
+
+/**
+ * struct jack_state - Jack state structure to keep data between interrupts
+ * @kctl: Pointer to the ALSA control attached to this jack
+ * @jack: Pointer to the ASoC jack struct for this jack
+ * @mask: Possible reported jack status bits for this jack
+ */
+struct jack_state {
+	struct snd_kcontrol *kctl;
+	struct snd_soc_jack *jack;
+
+	unsigned int mask;
+};
+
+int sdca_jack_alloc_state(struct sdca_interrupt *interrupt);
+int sdca_jack_init_state(struct sdca_interrupt *interrupt);
+void sdca_jack_free_state(struct sdca_interrupt *interrupt);
+
+int sdca_jack_process(struct sdca_interrupt *interrupt);
+int sdca_jack_set_jack(struct sdca_interrupt_info *info, struct snd_soc_jack *jack);
+int sdca_jack_report(struct sdca_interrupt *interrupt);
+
+#endif // __SDCA_JACK_H__