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, 42 insertions, 0 deletions

diff --git a/include/dt-bindings/clock/bcm6318-clock.h b/include/dt-bindings/clock/bcm6318-clock.h
new file mode 100644
index 000000000..c4417f898
--- /dev/null
+++ b/include/dt-bindings/clock/bcm6318-clock.h
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+#ifndef __DT_BINDINGS_CLOCK_BCM6318_H
+#define __DT_BINDINGS_CLOCK_BCM6318_H
+
+#define BCM6318_CLK_ADSL_ASB	0
+#define BCM6318_CLK_USB_ASB	1
+#define BCM6318_CLK_MIPS_ASB	2
+#define BCM6318_CLK_PCIE_ASB	3
+#define BCM6318_CLK_PHYMIPS_ASB	4
+#define BCM6318_CLK_ROBOSW_ASB	5
+#define BCM6318_CLK_SAR_ASB	6
+#define BCM6318_CLK_SDR_ASB	7
+#define BCM6318_CLK_SWREG_ASB	8
+#define BCM6318_CLK_PERIPH_ASB	9
+#define BCM6318_CLK_CPUBUS160	10
+#define BCM6318_CLK_ADSL	11
+#define BCM6318_CLK_SAR125	12
+#define BCM6318_CLK_MIPS	13
+#define BCM6318_CLK_PCIE	14
+#define BCM6318_CLK_ROBOSW250	16
+#define BCM6318_CLK_ROBOSW025	17
+#define BCM6318_CLK_SDR		19
+#define BCM6318_CLK_USBD	20
+#define BCM6318_CLK_HSSPI	25
+#define BCM6318_CLK_PCIE25	27
+#define BCM6318_CLK_PHYMIPS	28
+#define BCM6318_CLK_AFE		29
+#define BCM6318_CLK_QPROC	30
+
+#define BCM6318_UCLK_ADSL	0
+#define BCM6318_UCLK_ARB	1
+#define BCM6318_UCLK_MIPS	2
+#define BCM6318_UCLK_PCIE	3
+#define BCM6318_UCLK_PERIPH	4
+#define BCM6318_UCLK_PHYMIPS	5
+#define BCM6318_UCLK_ROBOSW	6
+#define BCM6318_UCLK_SAR	7
+#define BCM6318_UCLK_SDR	8
+#define BCM6318_UCLK_USB	9
+
+#endif /* __DT_BINDINGS_CLOCK_BCM6318_H */