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, 56 insertions, 0 deletions

diff --git a/drivers/pinctrl/aspeed/Kconfig b/drivers/pinctrl/aspeed/Kconfig
new file mode 100644
index 000000000..8e1d4da08
--- /dev/null
+++ b/drivers/pinctrl/aspeed/Kconfig
@@ -0,0 +1,56 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config PINCTRL_ASPEED
+	bool
+	depends on (ARCH_ASPEED || COMPILE_TEST) && OF
+	select MFD_SYSCON
+	select PINMUX
+	select PINCONF
+	select GENERIC_PINCONF
+	select REGMAP_MMIO
+
+config PINCTRL_ASPEED_G4
+	bool "Aspeed G4 SoC pin control"
+	depends on (MACH_ASPEED_G4 || COMPILE_TEST) && OF
+	select PINCTRL_ASPEED
+	help
+	  Say Y here to enable pin controller support for Aspeed's 4th
+	  generation SoCs. GPIO is provided by a separate GPIO driver.
+
+config PINCTRL_ASPEED_G5
+	bool "Aspeed G5 SoC pin control"
+	depends on (MACH_ASPEED_G5 || COMPILE_TEST) && OF
+	select PINCTRL_ASPEED
+	help
+	  Say Y here to enable pin controller support for Aspeed's 5th
+	  generation SoCs. GPIO is provided by a separate GPIO driver.
+
+config PINCTRL_ASPEED_G6
+	bool "Aspeed G6 SoC pin control"
+	depends on (MACH_ASPEED_G6 || COMPILE_TEST) && OF
+	select PINCTRL_ASPEED
+	help
+	  Say Y here to enable pin controller support for Aspeed's 6th
+	  generation SoCs. GPIO is provided by a separate GPIO driver.
+
+config PINCTRL_ASPEED_G7_SOC0
+	bool "Aspeed G7 SoC pin control"
+	depends on (ARCH_ASPEED || COMPILE_TEST) && OF
+	select PINCTRL_ASPEED
+	help
+	  Say Y here to enable pin controller support for the SoC0 instance
+	  of Aspeed's 7th generation SoCs. GPIO is provided by a separate
+	  GPIO driver.
+
+config PINCTRL_ASPEED_G7_SOC1
+	bool "Aspeed G7 SoC1 pin control"
+	depends on (ARCH_ASPEED || COMPILE_TEST) && OF
+	select MFD_SYSCON
+	select PINMUX
+	select GENERIC_PINCTRL_GROUPS
+	select GENERIC_PINMUX_FUNCTIONS
+	select GENERIC_PINCONF
+	select REGMAP_MMIO
+	help
+	  Say Y here to enable pin controller support for the SoC1 instance
+	  of Aspeed's 7th generation SoCs. GPIO is provided by a separate
+	  GPIO driver.