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, 39 insertions, 0 deletions

diff --git a/include/sound/sta32x.h b/include/sound/sta32x.h
new file mode 100644
index 000000000..600494251
--- /dev/null
+++ b/include/sound/sta32x.h
@@ -0,0 +1,39 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Platform data for ST STA32x ASoC codec driver.
+ *
+ * Copyright: 2011 Raumfeld GmbH
+ * Author: Johannes Stezenbach <js@sig21.net>
+ */
+#ifndef __LINUX_SND__STA32X_H
+#define __LINUX_SND__STA32X_H
+
+#define STA32X_OCFG_2CH		0
+#define STA32X_OCFG_2_1CH	1
+#define STA32X_OCFG_1CH		3
+
+#define STA32X_OM_CH1		0
+#define STA32X_OM_CH2		1
+#define STA32X_OM_CH3		2
+
+#define STA32X_THERMAL_ADJUSTMENT_ENABLE	1
+#define STA32X_THERMAL_RECOVERY_ENABLE		2
+
+struct sta32x_platform_data {
+	u8 output_conf;
+	u8 ch1_output_mapping;
+	u8 ch2_output_mapping;
+	u8 ch3_output_mapping;
+	int needs_esd_watchdog;
+	u8 drop_compensation_ns;
+	unsigned int thermal_warning_recovery:1;
+	unsigned int thermal_warning_adjustment:1;
+	unsigned int fault_detect_recovery:1;
+	unsigned int max_power_use_mpcc:1;
+	unsigned int max_power_correction:1;
+	unsigned int am_reduction_mode:1;
+	unsigned int odd_pwm_speed_mode:1;
+	unsigned int invalid_input_detect_mute:1;
+};
+
+#endif /* __LINUX_SND__STA32X_H */