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, 145 insertions, 0 deletions

diff --git a/drivers/input/rmi4/Kconfig b/drivers/input/rmi4/Kconfig
new file mode 100644
index 000000000..5db58fc9e
--- /dev/null
+++ b/drivers/input/rmi4/Kconfig
@@ -0,0 +1,145 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# RMI4 configuration
+#
+config RMI4_CORE
+	tristate "Synaptics RMI4 bus support"
+	select IRQ_DOMAIN
+	help
+	  Say Y here if you want to support the Synaptics RMI4 bus.  This is
+	  required for all RMI4 device support.
+
+	  If unsure, say Y.
+
+if RMI4_CORE
+
+config RMI4_I2C
+	tristate "RMI4 I2C Support"
+	depends on I2C
+	help
+	  Say Y here if you want to support RMI4 devices connected to an I2C
+	  bus.
+
+	  If unsure, say Y.
+
+config RMI4_SPI
+	tristate "RMI4 SPI Support"
+	depends on SPI
+	help
+	  Say Y here if you want to support RMI4 devices connected to a SPI
+	  bus.
+
+	  If unsure, say N.
+
+config RMI4_SMB
+	tristate "RMI4 SMB Support"
+	depends on I2C
+	help
+	  Say Y here if you want to support RMI4 devices connected to an SMB
+	  bus.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called rmi_smbus.
+
+config RMI4_F03
+	bool "RMI4 Function 03 (PS2 Guest)"
+	depends on RMI4_CORE
+	help
+	  Say Y here if you want to add support for RMI4 function 03.
+
+	  Function 03 provides PS2 guest support for RMI4 devices. This
+	  includes support for TrackPoints on TouchPads.
+
+config RMI4_F03_SERIO
+	tristate
+	depends on RMI4_CORE
+	depends on RMI4_F03
+	default RMI4_CORE
+	select SERIO
+
+config RMI4_2D_SENSOR
+	bool
+
+config RMI4_F11
+	bool "RMI4 Function 11 (2D pointing)"
+	select RMI4_2D_SENSOR
+	help
+	  Say Y here if you want to add support for RMI4 function 11.
+
+	  Function 11 provides 2D multifinger pointing for touchscreens and
+	  touchpads. For sensors that support relative pointing, F11 also
+	  provides mouse input.
+
+config RMI4_F12
+	bool "RMI4 Function 12 (2D pointing)"
+	select RMI4_2D_SENSOR
+	help
+	  Say Y here if you want to add support for RMI4 function 12.
+
+	  Function 12 provides 2D multifinger pointing for touchscreens and
+	  touchpads. For sensors that support relative pointing, F12 also
+	  provides mouse input.
+
+config RMI4_F1A
+	bool "RMI4 Function 1A (0D pointing)"
+	help
+	  Say Y here if you want to add support for RMI4 function 1A.
+
+	  Function 1A provides capacitive keys support for RMI4 devices.
+
+config RMI4_F21
+	bool "RMI4 Function 21 (PRESSURE)"
+	help
+	  Say Y here if you want to add support for RMI4 function 21.
+
+	  Function 21 provides buttons/pressure handling for RMI4 devices.
+	  This includes support for buttons/pressure on PressurePad.
+
+config RMI4_F30
+	bool "RMI4 Function 30 (GPIO LED)"
+	help
+	  Say Y here if you want to add support for RMI4 function 30.
+
+	  Function 30 provides GPIO and LED support for RMI4 devices. This
+	  includes support for buttons on TouchPads and ClickPads.
+
+config RMI4_F34
+	bool "RMI4 Function 34 (Device reflash)"
+	select FW_LOADER
+	help
+	  Say Y here if you want to add support for RMI4 function 34.
+
+	  Function 34 provides support for upgrading the firmware on the RMI4
+	  device via the firmware loader interface. This is triggered using a
+	  sysfs attribute.
+
+config RMI4_F3A
+	bool "RMI4 Function 3A (GPIO)"
+	help
+	  Say Y here if you want to add support for RMI4 function 3A.
+
+	  Function 3A provides GPIO support for RMI4 devices. This includes
+	  support for buttons on TouchPads and ClickPads.
+
+config RMI4_F54
+	bool "RMI4 Function 54 (Analog diagnostics)"
+	depends on VIDEO_DEV=y || (RMI4_CORE=m && VIDEO_DEV=m)
+	select VIDEOBUF2_VMALLOC
+	select RMI4_F55
+	help
+	  Say Y here if you want to add support for RMI4 function 54
+
+	  Function 54 provides access to various diagnostic features in certain
+	  RMI4 touch sensors.
+
+config RMI4_F55
+	bool "RMI4 Function 55 (Sensor tuning)"
+	help
+	  Say Y here if you want to add support for RMI4 function 55
+
+	  Function 55 provides access to the RMI4 touch sensor tuning
+	  mechanism.
+
+endif # RMI_CORE