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, 47 insertions, 0 deletions

diff --git a/include/sound/cs48l32.h b/include/sound/cs48l32.h
new file mode 100644
index 000000000..27b3e7cf9
--- /dev/null
+++ b/include/sound/cs48l32.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Register definitions for Cirrus Logic CS48L32
+ *
+ * Copyright (C) 2017-2018, 2020, 2022, 2025 Cirrus Logic, Inc. and
+ *               Cirrus Logic International Semiconductor Ltd.
+ */
+
+#ifndef CS48L32_H
+#define CS48L32_H
+
+/* pll_id for snd_soc_component_set_pll() */
+#define CS48L32_FLL1_REFCLK			1
+
+/* source for snd_soc_component_set_pll() */
+#define CS48L32_FLL_SRC_NONE			-1
+#define CS48L32_FLL_SRC_MCLK1			0
+#define CS48L32_FLL_SRC_PDMCLK			5
+#define CS48L32_FLL_SRC_ASP1_BCLK		8
+#define CS48L32_FLL_SRC_ASP2_BCLK		9
+#define CS48L32_FLL_SRC_ASP1_FSYNC		12
+#define CS48L32_FLL_SRC_ASP2_FSYNC		13
+
+/* clk_id for snd_soc_component_set_sysclk() and snd_soc_dai_set_sysclk() */
+#define CS48L32_CLK_SYSCLK_1			1
+#define CS48L32_CLK_SYSCLK_2			2
+#define CS48L32_CLK_SYSCLK_3			3
+#define CS48L32_CLK_SYSCLK_4			4
+#define CS48L32_CLK_DSPCLK			7
+#define CS48L32_CLK_PDM_FLLCLK			13
+
+/* source for snd_soc_component_set_sysclk() */
+#define CS48L32_CLK_SRC_MCLK1			0x0
+#define CS48L32_CLK_SRC_FLL1			0x4
+#define CS48L32_CLK_SRC_ASP1_BCLK		0x8
+#define CS48L32_CLK_SRC_ASP2_BCLK		0x9
+
+struct cs48l32 {
+	struct regmap *regmap;
+	struct device *dev;
+	struct gpio_desc *reset_gpio;
+	struct clk *mclk1;
+	struct regulator_bulk_data core_supplies[2];
+	struct regulator *vdd_d;
+	int irq;
+};
+#endif