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, 82 insertions, 0 deletions

diff --git a/include/dt-bindings/clock/bm1880-clock.h b/include/dt-bindings/clock/bm1880-clock.h
new file mode 100644
index 000000000..b46732361
--- /dev/null
+++ b/include/dt-bindings/clock/bm1880-clock.h
@@ -0,0 +1,82 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Device Tree binding constants for Bitmain BM1880 SoC
+ *
+ * Copyright (c) 2019 Linaro Ltd.
+ */
+
+#ifndef __DT_BINDINGS_CLOCK_BM1880_H
+#define __DT_BINDINGS_CLOCK_BM1880_H
+
+#define BM1880_CLK_OSC			0
+#define BM1880_CLK_MPLL			1
+#define BM1880_CLK_SPLL			2
+#define BM1880_CLK_FPLL			3
+#define BM1880_CLK_DDRPLL		4
+#define BM1880_CLK_A53			5
+#define BM1880_CLK_50M_A53		6
+#define BM1880_CLK_AHB_ROM		7
+#define BM1880_CLK_AXI_SRAM		8
+#define BM1880_CLK_DDR_AXI		9
+#define BM1880_CLK_EFUSE		10
+#define BM1880_CLK_APB_EFUSE		11
+#define BM1880_CLK_AXI5_EMMC		12
+#define BM1880_CLK_EMMC			13
+#define BM1880_CLK_100K_EMMC		14
+#define BM1880_CLK_AXI5_SD		15
+#define BM1880_CLK_SD			16
+#define BM1880_CLK_100K_SD		17
+#define BM1880_CLK_500M_ETH0		18
+#define BM1880_CLK_AXI4_ETH0		19
+#define BM1880_CLK_500M_ETH1		20
+#define BM1880_CLK_AXI4_ETH1		21
+#define BM1880_CLK_AXI1_GDMA		22
+#define BM1880_CLK_APB_GPIO		23
+#define BM1880_CLK_APB_GPIO_INTR	24
+#define BM1880_CLK_GPIO_DB		25
+#define BM1880_CLK_AXI1_MINER		26
+#define BM1880_CLK_AHB_SF		27
+#define BM1880_CLK_SDMA_AXI		28
+#define BM1880_CLK_SDMA_AUD		29
+#define BM1880_CLK_APB_I2C		30
+#define BM1880_CLK_APB_WDT		31
+#define BM1880_CLK_APB_JPEG		32
+#define BM1880_CLK_JPEG_AXI		33
+#define BM1880_CLK_AXI5_NF		34
+#define BM1880_CLK_APB_NF		35
+#define BM1880_CLK_NF			36
+#define BM1880_CLK_APB_PWM		37
+#define BM1880_CLK_DIV_0_RV		38
+#define BM1880_CLK_DIV_1_RV		39
+#define BM1880_CLK_MUX_RV		40
+#define BM1880_CLK_RV			41
+#define BM1880_CLK_APB_SPI		42
+#define BM1880_CLK_TPU_AXI		43
+#define BM1880_CLK_DIV_UART_500M	44
+#define BM1880_CLK_UART_500M		45
+#define BM1880_CLK_APB_UART		46
+#define BM1880_CLK_APB_I2S		47
+#define BM1880_CLK_AXI4_USB		48
+#define BM1880_CLK_APB_USB		49
+#define BM1880_CLK_125M_USB		50
+#define BM1880_CLK_33K_USB		51
+#define BM1880_CLK_DIV_12M_USB		52
+#define BM1880_CLK_12M_USB		53
+#define BM1880_CLK_APB_VIDEO		54
+#define BM1880_CLK_VIDEO_AXI		55
+#define BM1880_CLK_VPP_AXI		56
+#define BM1880_CLK_APB_VPP		57
+#define BM1880_CLK_DIV_0_AXI1		58
+#define BM1880_CLK_DIV_1_AXI1		59
+#define BM1880_CLK_AXI1			60
+#define BM1880_CLK_AXI2			61
+#define BM1880_CLK_AXI3			62
+#define BM1880_CLK_AXI4			63
+#define BM1880_CLK_AXI5			64
+#define BM1880_CLK_DIV_0_AXI6		65
+#define BM1880_CLK_DIV_1_AXI6		66
+#define BM1880_CLK_MUX_AXI6		67
+#define BM1880_CLK_AXI6			68
+#define BM1880_NR_CLKS			69
+
+#endif /* __DT_BINDINGS_CLOCK_BM1880_H */