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, 76 insertions, 0 deletions

diff --git a/include/dt-bindings/clock/r8a7740-clock.h b/include/dt-bindings/clock/r8a7740-clock.h
new file mode 100644
index 000000000..8a8816b2f
--- /dev/null
+++ b/include/dt-bindings/clock/r8a7740-clock.h
@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright 2014 Ulrich Hecht
+ */
+
+#ifndef __DT_BINDINGS_CLOCK_R8A7740_H__
+#define __DT_BINDINGS_CLOCK_R8A7740_H__
+
+/* CPG */
+#define R8A7740_CLK_SYSTEM	0
+#define R8A7740_CLK_PLLC0	1
+#define R8A7740_CLK_PLLC1	2
+#define R8A7740_CLK_PLLC2	3
+#define R8A7740_CLK_R		4
+#define R8A7740_CLK_USB24S	5
+#define R8A7740_CLK_I		6
+#define R8A7740_CLK_ZG		7
+#define R8A7740_CLK_B		8
+#define R8A7740_CLK_M1		9
+#define R8A7740_CLK_HP		10
+#define R8A7740_CLK_HPP		11
+#define R8A7740_CLK_USBP	12
+#define R8A7740_CLK_S		13
+#define R8A7740_CLK_ZB		14
+#define R8A7740_CLK_M3		15
+#define R8A7740_CLK_CP		16
+#define R8A7740_CLK_ZTR		17
+#define R8A7740_CLK_ZT		18
+
+/* MSTP1 */
+#define R8A7740_CLK_CEU21	28
+#define R8A7740_CLK_CEU20	27
+#define R8A7740_CLK_TMU0	25
+#define R8A7740_CLK_LCDC1	17
+#define R8A7740_CLK_IIC0	16
+#define R8A7740_CLK_TMU1	11
+#define R8A7740_CLK_LCDC0	0
+
+/* MSTP2 */
+#define R8A7740_CLK_SCIFA6	30
+#define R8A7740_CLK_INTCA	29
+#define R8A7740_CLK_SCIFA7	22
+#define R8A7740_CLK_DMAC1	18
+#define R8A7740_CLK_DMAC2	17
+#define R8A7740_CLK_DMAC3	16
+#define R8A7740_CLK_USBDMAC	14
+#define R8A7740_CLK_SCIFA5	7
+#define R8A7740_CLK_SCIFB	6
+#define R8A7740_CLK_SCIFA0	4
+#define R8A7740_CLK_SCIFA1	3
+#define R8A7740_CLK_SCIFA2	2
+#define R8A7740_CLK_SCIFA3	1
+#define R8A7740_CLK_SCIFA4	0
+
+/* MSTP3 */
+#define R8A7740_CLK_CMT1	29
+#define R8A7740_CLK_FSI		28
+#define R8A7740_CLK_IIC1	23
+#define R8A7740_CLK_USBF	20
+#define R8A7740_CLK_SDHI0	14
+#define R8A7740_CLK_SDHI1	13
+#define R8A7740_CLK_MMC		12
+#define R8A7740_CLK_GETHER	9
+#define R8A7740_CLK_TPU0	4
+
+/* MSTP4 */
+#define R8A7740_CLK_USBH	16
+#define R8A7740_CLK_SDHI2	15
+#define R8A7740_CLK_USBFUNC	7
+#define R8A7740_CLK_USBPHY	6
+
+/* SUBCK* */
+#define R8A7740_CLK_SUBCK	9
+#define R8A7740_CLK_SUBCK2	10
+
+#endif /* __DT_BINDINGS_CLOCK_R8A7740_H__ */