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, 60 insertions, 0 deletions

diff --git a/include/dt-bindings/clock/r8a7779-clock.h b/include/dt-bindings/clock/r8a7779-clock.h
new file mode 100644
index 000000000..e39acdc64
--- /dev/null
+++ b/include/dt-bindings/clock/r8a7779-clock.h
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2013  Horms Solutions Ltd.
+ *
+ * Contact: Simon Horman <horms@verge.net.au>
+ */
+
+#ifndef __DT_BINDINGS_CLOCK_R8A7779_H__
+#define __DT_BINDINGS_CLOCK_R8A7779_H__
+
+/* CPG */
+#define R8A7779_CLK_PLLA	0
+#define R8A7779_CLK_Z		1
+#define R8A7779_CLK_ZS		2
+#define R8A7779_CLK_S		3
+#define R8A7779_CLK_S1		4
+#define R8A7779_CLK_P		5
+#define R8A7779_CLK_B		6
+#define R8A7779_CLK_OUT		7
+
+/* MSTP 0 */
+#define R8A7779_CLK_PWM		5
+#define R8A7779_CLK_HSPI	7
+#define R8A7779_CLK_TMU2	14
+#define R8A7779_CLK_TMU1	15
+#define R8A7779_CLK_TMU0	16
+#define R8A7779_CLK_HSCIF1	18
+#define R8A7779_CLK_HSCIF0	19
+#define R8A7779_CLK_SCIF5	21
+#define R8A7779_CLK_SCIF4	22
+#define R8A7779_CLK_SCIF3	23
+#define R8A7779_CLK_SCIF2	24
+#define R8A7779_CLK_SCIF1	25
+#define R8A7779_CLK_SCIF0	26
+#define R8A7779_CLK_I2C3	27
+#define R8A7779_CLK_I2C2	28
+#define R8A7779_CLK_I2C1	29
+#define R8A7779_CLK_I2C0	30
+
+/* MSTP 1 */
+#define R8A7779_CLK_USB01	0
+#define R8A7779_CLK_USB2	1
+#define R8A7779_CLK_DU		3
+#define R8A7779_CLK_VIN2	8
+#define R8A7779_CLK_VIN1	9
+#define R8A7779_CLK_VIN0	10
+#define R8A7779_CLK_ETHER	14
+#define R8A7779_CLK_SATA	15
+#define R8A7779_CLK_PCIE	16
+#define R8A7779_CLK_VIN3	20
+
+/* MSTP 3 */
+#define R8A7779_CLK_SDHI3	20
+#define R8A7779_CLK_SDHI2	21
+#define R8A7779_CLK_SDHI1	22
+#define R8A7779_CLK_SDHI0	23
+#define R8A7779_CLK_MMC1	30
+#define R8A7779_CLK_MMC0	31
+
+#endif /* __DT_BINDINGS_CLOCK_R8A7779_H__ */