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, 39 insertions, 0 deletions

diff --git a/drivers/interconnect/Kconfig b/drivers/interconnect/Kconfig
new file mode 100644
index 000000000..882dcb0b4
--- /dev/null
+++ b/drivers/interconnect/Kconfig
@@ -0,0 +1,39 @@
+# SPDX-License-Identifier: GPL-2.0-only
+menuconfig INTERCONNECT
+	bool "On-Chip Interconnect management support"
+	help
+	  Support for management of the on-chip interconnects.
+
+	  This framework is designed to provide a generic interface for
+	  managing the interconnects in a SoC.
+
+	  If unsure, say no.
+
+if INTERCONNECT
+
+source "drivers/interconnect/imx/Kconfig"
+source "drivers/interconnect/mediatek/Kconfig"
+source "drivers/interconnect/qcom/Kconfig"
+source "drivers/interconnect/samsung/Kconfig"
+
+config INTERCONNECT_CLK
+	tristate
+	depends on COMMON_CLK
+	help
+	  Support for wrapping clocks into the interconnect nodes.
+
+config INTERCONNECT_KUNIT_TEST
+	tristate "KUnit tests for Interconnect framework"
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  This builds the KUnit test suite for the generic system interconnect
+	  framework.
+
+	  The tests cover the core functionality of the interconnect subsystem,
+	  including provider/consumer APIs, topology management, and bandwidth
+	  aggregation logic.
+
+	  If unsure, say N.
+
+endif