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, 67 insertions, 0 deletions

diff --git a/drivers/pinctrl/tegra/Kconfig b/drivers/pinctrl/tegra/Kconfig
new file mode 100644
index 000000000..39a93733e
--- /dev/null
+++ b/drivers/pinctrl/tegra/Kconfig
@@ -0,0 +1,67 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config PINCTRL_TEGRA
+	bool "NVIDIA Tegra pin controllers common" if COMPILE_TEST && !ARCH_TEGRA
+	select PINMUX
+	select PINCONF
+
+config PINCTRL_TEGRA20
+	bool "NVIDIA Tegra20 pin controller" if COMPILE_TEST && !ARCH_TEGRA
+	select PINCTRL_TEGRA
+	depends on COMMON_CLK
+
+config PINCTRL_TEGRA30
+	bool "NVIDIA Tegra30 pin controller" if COMPILE_TEST && !ARCH_TEGRA
+	select PINCTRL_TEGRA
+
+config PINCTRL_TEGRA114
+	bool "NVIDIA Tegra114 pin controller" if COMPILE_TEST && !ARCH_TEGRA
+	select PINCTRL_TEGRA
+
+config PINCTRL_TEGRA124
+	bool "NVIDIA Tegra124 pin controller" if COMPILE_TEST && !ARCH_TEGRA
+	select PINCTRL_TEGRA
+
+config PINCTRL_TEGRA210
+	bool "NVIDIA Tegra210 pin controller" if COMPILE_TEST && !ARCH_TEGRA
+	select PINCTRL_TEGRA
+
+config PINCTRL_TEGRA186
+	bool "NVIDIA Tegra186 pin controller" if COMPILE_TEST && !ARCH_TEGRA
+	select PINCTRL_TEGRA
+
+config PINCTRL_TEGRA194
+	bool "NVIDIA Tegra194 pin controller" if COMPILE_TEST && !ARCH_TEGRA
+	select PINCTRL_TEGRA
+
+config PINCTRL_TEGRA234
+	bool "NVIDIA Tegra234 pin controller" if COMPILE_TEST && !ARCH_TEGRA
+	select PINCTRL_TEGRA
+
+config PINCTRL_TEGRA238
+	tristate "NVIDIA Tegra238 pinctrl driver"
+	depends on ARCH_TEGRA || COMPILE_TEST
+	default m if ARCH_TEGRA_238_SOC
+	select PINCTRL_TEGRA
+	help
+	  Say Y or M here to enable support for the pinctrl driver for
+	  NVIDIA Tegra238 SoC. This driver controls the pin multiplexing
+	  and configuration for the MAIN and AON pin controllers found
+	  on Tegra238.
+
+config PINCTRL_TEGRA264
+	tristate "NVIDIA Tegra264 pinctrl driver"
+	depends on ARCH_TEGRA || COMPILE_TEST
+	default m if ARCH_TEGRA_264_SOC
+	select PINCTRL_TEGRA
+	help
+	  Say Y or M here to enable support for the pinctrl driver for
+	  NVIDIA Tegra264 SoC. This driver controls the pin multiplexing
+	  and configuration for the MAIN, AON and UPHY pin controllers found
+	  on Tegra264.
+
+config PINCTRL_TEGRA_XUSB
+	bool "NVIDIA Tegra XUSB pin controller" if COMPILE_TEST && !ARCH_TEGRA
+	default y if ARCH_TEGRA
+	select GENERIC_PHY
+	select PINCONF
+	select PINMUX