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/max98088.h b/include/sound/max98088.h
new file mode 100644
index 000000000..76b376919
--- /dev/null
+++ b/include/sound/max98088.h
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Platform data for MAX98088
+ *
+ * Copyright 2010 Maxim Integrated Products
+ */
+
+#ifndef __SOUND_MAX98088_PDATA_H__
+#define __SOUND_MAX98088_PDATA_H__
+
+/* Equalizer filter response configuration */
+struct max98088_eq_cfg {
+       const char *name;
+       unsigned int rate;
+       u16 band1[5];
+       u16 band2[5];
+       u16 band3[5];
+       u16 band4[5];
+       u16 band5[5];
+};
+
+/* codec platform data */
+struct max98088_pdata {
+
+       /* Equalizers for DAI1 and DAI2 */
+       struct max98088_eq_cfg *eq_cfg;
+       unsigned int eq_cfgcnt;
+
+       /* Receiver output can be configured as power amplifier or LINE out */
+       /* Set receiver_mode to:
+        * 0 = amplifier output, or
+        * 1 = LINE level output
+        */
+       unsigned int receiver_mode:1;
+
+       /* Analog/digital microphone configuration:
+        * 0 = analog microphone input (normal setting)
+        * 1 = digital microphone input
+        */
+       unsigned int digmic_left_mode:1;
+       unsigned int digmic_right_mode:1;
+
+};
+
+#endif