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, 36 insertions, 0 deletions

diff --git a/drivers/reset/spacemit/Kconfig b/drivers/reset/spacemit/Kconfig
new file mode 100644
index 000000000..545d6b41c
--- /dev/null
+++ b/drivers/reset/spacemit/Kconfig
@@ -0,0 +1,36 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+menu "Reset support for SpacemiT platforms"
+	depends on ARCH_SPACEMIT || COMPILE_TEST
+
+config RESET_SPACEMIT_COMMON
+	tristate
+	select AUXILIARY_BUS
+	help
+	  Common reset controller infrastructure for SpacemiT SoCs.
+	  This provides shared code and helper functions used by
+	  reset drivers for various SpacemiT SoC families.
+
+config RESET_SPACEMIT_K1
+	tristate "Support for SpacemiT K1 SoC"
+	depends on SPACEMIT_K1_CCU
+	select RESET_SPACEMIT_COMMON
+	default SPACEMIT_K1_CCU
+	help
+	  Support for reset controller in SpacemiT K1 SoC.
+	  This driver works with the SpacemiT K1 clock controller
+	  unit (CCU) driver to provide reset control functionality
+	  for various peripherals and subsystems in the SoC.
+
+config RESET_SPACEMIT_K3
+	tristate "Support for SpacemiT K3 SoC"
+	depends on SPACEMIT_K3_CCU
+	select RESET_SPACEMIT_COMMON
+	default SPACEMIT_K3_CCU
+	help
+	  Support for reset controller in SpacemiT K3 SoC.
+	  This driver works with the SpacemiT K3 clock controller
+	  unit (CCU) driver to provide reset control functionality
+	  for various peripherals and subsystems in the SoC.
+
+endmenu