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, 49 insertions, 0 deletions

diff --git a/drivers/pinctrl/starfive/Kconfig b/drivers/pinctrl/starfive/Kconfig
new file mode 100644
index 000000000..a9a7cb101
--- /dev/null
+++ b/drivers/pinctrl/starfive/Kconfig
@@ -0,0 +1,49 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+config PINCTRL_STARFIVE_JH7100
+	tristate "Pinctrl and GPIO driver for the StarFive JH7100 SoC"
+	depends on SOC_STARFIVE || COMPILE_TEST
+	depends on OF
+	select GENERIC_PINCTRL_GROUPS
+	select GENERIC_PINMUX_FUNCTIONS
+	select GENERIC_PINCONF
+	select GPIOLIB
+	select GPIOLIB_IRQCHIP
+	default SOC_STARFIVE
+	help
+	  Say yes here to support pin control on the StarFive JH7100 SoC.
+	  This also provides an interface to the GPIO pins not used by other
+	  peripherals supporting inputs, outputs, configuring pull-up/pull-down
+	  and interrupts on input changes.
+
+config PINCTRL_STARFIVE_JH7110
+	bool
+	select GENERIC_PINCTRL_GROUPS
+	select GENERIC_PINMUX_FUNCTIONS
+	select GENERIC_PINCONF
+	select GPIOLIB
+	select GPIOLIB_IRQCHIP
+
+config PINCTRL_STARFIVE_JH7110_SYS
+	tristate "System pinctrl and GPIO driver for the StarFive JH7110 SoC"
+	depends on SOC_STARFIVE  || COMPILE_TEST
+	depends on OF
+	select PINCTRL_STARFIVE_JH7110
+	default SOC_STARFIVE
+	help
+	  Say yes here to support system pin control on the StarFive JH7110 SoC.
+	  This also provides an interface to the GPIO pins not used by other
+	  peripherals supporting inputs, outputs, configuring pull-up/pull-down
+	  and interrupts on input changes.
+
+config PINCTRL_STARFIVE_JH7110_AON
+	tristate "Always-on pinctrl and GPIO driver for the StarFive JH7110 SoC"
+	depends on SOC_STARFIVE  || COMPILE_TEST
+	depends on OF
+	select PINCTRL_STARFIVE_JH7110
+	default SOC_STARFIVE
+	help
+	  Say yes here to support always-on pin control on the StarFive JH7110 SoC.
+	  This also provides an interface to the GPIO pins not used by other
+	  peripherals supporting inputs, outputs, configuring pull-up/pull-down
+	  and interrupts on input changes.