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, 59 insertions, 0 deletions

diff --git a/include/sound/madera-pdata.h b/include/sound/madera-pdata.h
new file mode 100644
index 000000000..58398d80c
--- /dev/null
+++ b/include/sound/madera-pdata.h
@@ -0,0 +1,59 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Platform data for Madera codec driver
+ *
+ * Copyright (C) 2016-2019 Cirrus Logic, Inc. and
+ *                         Cirrus Logic International Semiconductor Ltd.
+ */
+
+#ifndef MADERA_CODEC_PDATA_H
+#define MADERA_CODEC_PDATA_H
+
+#include <linux/types.h>
+
+#define MADERA_MAX_INPUT		6
+#define MADERA_MAX_MUXED_CHANNELS	4
+#define MADERA_MAX_OUTPUT		6
+#define MADERA_MAX_AIF			4
+#define MADERA_MAX_PDM_SPK		2
+#define MADERA_MAX_DSP			7
+
+/**
+ * struct madera_codec_pdata
+ *
+ * @max_channels_clocked: Maximum number of channels that I2S clocks will be
+ *			  generated for. Useful when clock master for systems
+ *			  where the I2S bus has multiple data lines.
+ * @dmic_ref:		  Indicates how the MICBIAS pins have been externally
+ *			  connected to DMICs on each input. A value of 0
+ *			  indicates MICVDD and is the default. Other values are:
+ *			  For CS47L35 one of the CS47L35_DMIC_REF_xxx values
+ *			  For all other codecs one of the MADERA_DMIC_REF_xxx
+ *			  Also see the datasheet for a description of the
+ *			  INn_DMIC_SUP field.
+ * @inmode:		  Mode for the ADC inputs. One of the MADERA_INMODE_xxx
+ *			  values. Two-dimensional array
+ *			  [input_number][channel number], with four slots per
+ *			  input in the order
+ *			  [n][0]=INnAL [n][1]=INnAR [n][2]=INnBL [n][3]=INnBR
+ * @out_mono:		  For each output set the value to TRUE to indicate that
+ *			  the output is mono. [0]=OUT1, [1]=OUT2, ...
+ * @pdm_fmt:		  PDM speaker data format. See the PDM_SPKn_FMT field in
+ *			  the datasheet for a description of this value.
+ * @pdm_mute:		  PDM mute format. See the PDM_SPKn_CTRL_1 register
+ *			  in the datasheet for a description of this value.
+ */
+struct madera_codec_pdata {
+	u32 max_channels_clocked[MADERA_MAX_AIF];
+
+	u32 dmic_ref[MADERA_MAX_INPUT];
+
+	u32 inmode[MADERA_MAX_INPUT][MADERA_MAX_MUXED_CHANNELS];
+
+	bool out_mono[MADERA_MAX_OUTPUT];
+
+	u32 pdm_fmt[MADERA_MAX_PDM_SPK];
+	u32 pdm_mute[MADERA_MAX_PDM_SPK];
+};
+
+#endif