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, 45 insertions, 0 deletions

diff --git a/include/sound/cs35l33.h b/include/sound/cs35l33.h
new file mode 100644
index 000000000..a25084c4f
--- /dev/null
+++ b/include/sound/cs35l33.h
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * linux/sound/cs35l33.h -- Platform data for CS35l33
+ *
+ * Copyright (c) 2016 Cirrus Logic Inc.
+ */
+
+#ifndef __CS35L33_H
+#define __CS35L33_H
+
+struct cs35l33_hg {
+	bool enable_hg_algo;
+	unsigned int mem_depth;
+	unsigned int release_rate;
+	unsigned int hd_rm;
+	unsigned int ldo_thld;
+	unsigned int ldo_path_disable;
+	unsigned int ldo_entry_delay;
+	bool vp_hg_auto;
+	unsigned int vp_hg;
+	unsigned int vp_hg_rate;
+	unsigned int vp_hg_va;
+};
+
+struct cs35l33_pdata {
+	/* Boost Controller Voltage Setting */
+	unsigned int boost_ctl;
+
+	/* Boost Controller Peak Current */
+	unsigned int boost_ipk;
+
+	/* Amplifier Drive Select */
+	unsigned int amp_drv_sel;
+
+	/* soft volume ramp */
+	unsigned int ramp_rate;
+
+	/* IMON adc scale */
+	unsigned int imon_adc_scale;
+
+	/* H/G algo configuration */
+	struct cs35l33_hg hg_config;
+};
+
+#endif /* __CS35L33_H */