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, 36 insertions, 0 deletions

diff --git a/include/dt-bindings/clock/imx1-clock.h b/include/dt-bindings/clock/imx1-clock.h
new file mode 100644
index 000000000..3730a46e7
--- /dev/null
+++ b/include/dt-bindings/clock/imx1-clock.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2014 Alexander Shiyan <shc_work@mail.ru>
+ */
+
+#ifndef __DT_BINDINGS_CLOCK_IMX1_H
+#define __DT_BINDINGS_CLOCK_IMX1_H
+
+#define IMX1_CLK_DUMMY		0
+#define IMX1_CLK_CLK32		1
+#define IMX1_CLK_CLK16M_EXT	2
+#define IMX1_CLK_CLK16M		3
+#define IMX1_CLK_CLK32_PREMULT	4
+#define IMX1_CLK_PREM		5
+#define IMX1_CLK_MPLL		6
+#define IMX1_CLK_MPLL_GATE	7
+#define IMX1_CLK_SPLL		8
+#define IMX1_CLK_SPLL_GATE	9
+#define IMX1_CLK_MCU		10
+#define IMX1_CLK_FCLK		11
+#define IMX1_CLK_HCLK		12
+#define IMX1_CLK_CLK48M		13
+#define IMX1_CLK_PER1		14
+#define IMX1_CLK_PER2		15
+#define IMX1_CLK_PER3		16
+#define IMX1_CLK_CLKO		17
+#define IMX1_CLK_UART3_GATE	18
+#define IMX1_CLK_SSI2_GATE	19
+#define IMX1_CLK_BROM_GATE	20
+#define IMX1_CLK_DMA_GATE	21
+#define IMX1_CLK_CSI_GATE	22
+#define IMX1_CLK_MMA_GATE	23
+#define IMX1_CLK_USBD_GATE	24
+#define IMX1_CLK_MAX		25
+
+#endif