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, 88 insertions, 0 deletions

diff --git a/drivers/i3c/master/Kconfig b/drivers/i3c/master/Kconfig
new file mode 100644
index 000000000..2609f2b18
--- /dev/null
+++ b/drivers/i3c/master/Kconfig
@@ -0,0 +1,88 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config ADI_I3C_MASTER
+	tristate "Analog Devices I3C master driver"
+	depends on HAS_IOMEM
+	help
+	  Support for Analog Devices I3C Controller IP, an AXI-interfaced IP
+	  core that supports I3C and I2C devices, multiple speed-grades and I3C
+	  IBIs.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called adi-i3c-master.
+
+config CDNS_I3C_MASTER
+	tristate "Cadence I3C master driver"
+	depends on HAS_IOMEM
+	depends on !(ALPHA || PARISC)
+	help
+	  Enable this driver if you want to support Cadence I3C master block.
+
+config DW_I3C_MASTER
+	tristate "Synospsys DesignWare I3C master driver"
+	depends on HAS_IOMEM
+	depends on !(ALPHA || PARISC)
+	# ALPHA and PARISC needs {read,write}sl()
+	help
+	  Support for Synopsys DesignWare MIPI I3C Controller.
+
+	  For details please see
+	  https://www.synopsys.com/dw/ipdir.php?ds=mipi_i3c
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called dw-i3c-master.
+
+config AST2600_I3C_MASTER
+	tristate "ASPEED AST2600 I3C master driver"
+	depends on DW_I3C_MASTER
+	depends on ARCH_ASPEED || COMPILE_TEST
+	select MFD_SYSCON
+	help
+	  Support for ASPEED AST2600 I3C Controller.
+
+	  This hardware is an instance of the DW I3C controller; this
+	  driver adds platform- specific support for AST2600 hardware.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called ast2600-i3c-master.
+
+config SVC_I3C_MASTER
+	tristate "Silvaco I3C Dual-Role Master driver"
+	depends on HAS_IOMEM
+	depends on !(ALPHA || PARISC)
+	help
+	  Support for Silvaco I3C Dual-Role Master Controller.
+
+config MIPI_I3C_HCI
+	tristate "MIPI I3C Host Controller Interface driver (EXPERIMENTAL)"
+	depends on HAS_IOMEM
+	help
+	  Support for hardware following the MIPI Aliance's I3C Host Controller
+	  Interface specification.
+
+	  For details please see:
+	  https://www.mipi.org/specifications/i3c-hci
+
+	  This driver can also be built as a module.  If so, the module will be
+	  called mipi-i3c-hci.
+
+config MIPI_I3C_HCI_PCI
+	tristate "MIPI I3C Host Controller Interface PCI support"
+	depends on MIPI_I3C_HCI
+	depends on PCI
+	select MFD_CORE
+	help
+	  Support for MIPI I3C Host Controller Interface compatible hardware
+	  on the PCI bus.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called mipi-i3c-hci-pci.
+
+config RENESAS_I3C
+	tristate "Renesas I3C controller driver"
+	depends on HAS_IOMEM
+	depends on ARCH_RENESAS || COMPILE_TEST
+	help
+	  Support the Renesas I3C controller as found in some RZ variants.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called renesas-i3c.