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/soc/aspeed/Kconfig b/drivers/soc/aspeed/Kconfig
new file mode 100644
index 000000000..63a656449
--- /dev/null
+++ b/drivers/soc/aspeed/Kconfig
@@ -0,0 +1,56 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+if ARCH_ASPEED || COMPILE_TEST
+
+menu "ASPEED SoC drivers"
+
+config ASPEED_LPC_CTRL
+	tristate "ASPEED LPC firmware cycle control"
+	select REGMAP
+	select MFD_SYSCON
+	default ARCH_ASPEED
+	help
+	  Control LPC firmware cycle mappings through ioctl()s. The driver
+	  also provides a read/write interface to a BMC ram region where the
+	  host LPC read/write region can be buffered.
+
+config ASPEED_LPC_SNOOP
+	tristate "ASPEED LPC snoop support"
+	select REGMAP
+	select MFD_SYSCON
+	default ARCH_ASPEED
+	help
+	  Provides a driver to control the LPC snoop interface which
+	  allows the BMC to listen on and save the data written by
+	  the host to an arbitrary LPC I/O port.
+
+config ASPEED_UART_ROUTING
+	tristate "ASPEED uart routing control"
+	select REGMAP
+	select MFD_SYSCON
+	default ARCH_ASPEED
+	help
+	  Provides a driver to control the UART routing paths, allowing
+	  users to perform runtime configuration of the RX muxes among
+	  the UART controllers and I/O pins.
+
+config ASPEED_P2A_CTRL
+	tristate "ASPEED P2A (VGA MMIO to BMC) bridge control"
+	select REGMAP
+	select MFD_SYSCON
+	default ARCH_ASPEED
+	help
+	  Control ASPEED P2A VGA MMIO to BMC mappings through ioctl()s.  The
+	  driver also provides an interface for userspace mappings to a
+	  pre-defined region.
+
+config ASPEED_SOCINFO
+	bool "ASPEED SoC Information driver"
+	select SOC_BUS
+	default ARCH_ASPEED
+	help
+	  Say yes to support decoding of ASPEED BMC information.
+
+endmenu
+
+endif