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, 57 insertions, 0 deletions

diff --git a/drivers/spmi/Kconfig b/drivers/spmi/Kconfig
new file mode 100644
index 000000000..a80cf4047
--- /dev/null
+++ b/drivers/spmi/Kconfig
@@ -0,0 +1,57 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# SPMI driver configuration
+#
+menuconfig SPMI
+	tristate "SPMI support"
+	help
+	  SPMI (System Power Management Interface) is a two-wire
+	  serial interface between baseband and application processors
+	  and Power Management Integrated Circuits (PMIC).
+
+if SPMI
+
+config SPMI_APPLE
+	tristate "Apple SoC SPMI Controller platform driver"
+	depends on ARCH_APPLE || COMPILE_TEST
+	help
+	  If you say yes to this option, support will be included for the
+	  SPMI controller present on many Apple SoCs, including the
+	  t8103 (M1) and t600x (M1 Pro/Max).
+
+config SPMI_HISI3670
+	tristate "Hisilicon 3670 SPMI Controller"
+	select IRQ_DOMAIN_HIERARCHY
+	depends on ARM64 || COMPILE_TEST
+	depends on HAS_IOMEM
+	help
+	  If you say yes to this option, support will be included for the
+	  built-in SPMI PMIC Arbiter interface on Hisilicon 3670
+	  processors.
+
+config SPMI_MSM_PMIC_ARB
+	tristate "Qualcomm MSM SPMI Controller (PMIC Arbiter)"
+	select IRQ_DOMAIN_HIERARCHY
+	depends on ARCH_QCOM || COMPILE_TEST
+	depends on HAS_IOMEM
+	default ARCH_QCOM
+	help
+	  If you say yes to this option, support will be included for the
+	  built-in SPMI PMIC Arbiter interface on Qualcomm MSM family
+	  processors.
+
+	  This is required for communicating with Qualcomm PMICs and
+	  other devices that have the SPMI interface.
+
+config SPMI_MTK_PMIF
+	tristate "Mediatek SPMI Controller (PMIC Arbiter)"
+	depends on ARCH_MEDIATEK || COMPILE_TEST
+	help
+	  If you say yes to this option, support will be included for the
+	  built-in SPMI PMIC Arbiter interface on Mediatek family
+	  processors.
+
+	  This is required for communicating with Mediatek PMICs and
+	  other devices that have the SPMI interface.
+
+endif