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, 29 insertions, 0 deletions

diff --git a/include/sound/da9055.h b/include/sound/da9055.h
new file mode 100644
index 000000000..5c9a3c23e
--- /dev/null
+++ b/include/sound/da9055.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * DA9055 ALSA Soc codec driver
+ *
+ * Copyright (c) 2012 Dialog Semiconductor
+ *
+ * Tested on (Samsung SMDK6410 board + DA9055 EVB) using I2S and I2C
+ * Written by David Chen <david.chen@diasemi.com> and
+ * Ashish Chavan <ashish.chavan@kpitcummins.com>
+ */
+
+#ifndef __SOUND_DA9055_H__
+#define __SOUND_DA9055_H__
+
+enum da9055_micbias_voltage {
+	DA9055_MICBIAS_1_6V = 0,
+	DA9055_MICBIAS_1_8V = 1,
+	DA9055_MICBIAS_2_1V = 2,
+	DA9055_MICBIAS_2_2V = 3,
+};
+
+struct da9055_platform_data {
+	/* Selects which of the two MicBias pins acts as the bias source */
+	bool micbias_source;
+	/* Selects the micbias voltage */
+	enum da9055_micbias_voltage micbias;
+};
+
+#endif