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, 206 insertions, 0 deletions

diff --git a/drivers/accessibility/speakup/Kconfig b/drivers/accessibility/speakup/Kconfig
new file mode 100644
index 000000000..e84fb617a
--- /dev/null
+++ b/drivers/accessibility/speakup/Kconfig
@@ -0,0 +1,206 @@
+# SPDX-License-Identifier: GPL-2.0
+menu "Speakup console speech"
+
+config SPEAKUP
+	depends on VT
+	tristate "Speakup core"
+	help
+		This is the Speakup screen reader.  Think of it as a
+		video console for blind people.  If built in to the
+		kernel, it can speak everything on the text console from
+		boot up to shutdown.  For more information on Speakup,
+		point your browser at <http://www.linux-speakup.org/>.
+		There is also a mailing list at the above url that you
+		can subscribe to.
+
+		Supported synthesizers are accent sa, accent pc,
+		appollo II., Auddapter, Braille 'n Speak, Dectalk
+		external (old), Dectalk PC (full length isa board),
+		Dectalk express, Doubletalk, Doubletalk LT or
+		Litetalk, Keynote Gold internal PC, software
+		synthesizers, Speakout, transport, and a dummy module
+		that can be used with a plain text terminal.
+
+		Speakup can either be built in or compiled as a module
+		by answering y or m.  If you answer y here, then you
+		must answer either y or m to at least one of the
+		synthesizer drivers below.  If you answer m here, then
+		the synthesizer drivers below can only be built as
+		modules.
+
+		These drivers are not standalone drivers, but must be
+		used in conjunction with Speakup.  Think of them as
+		video cards for blind people.
+
+
+		The Dectalk pc driver can only be built as a module, and
+		requires software to be pre-loaded on to the card before
+		the module can be loaded.  See the decpc choice below
+		for more details.
+
+		If you are not a blind person, or don't have access to
+		one of the listed synthesizers, you should say n.
+
+if SPEAKUP
+
+config SPEAKUP_SERIALIO
+	def_bool y
+	depends on ISA || COMPILE_TEST
+	depends on HAS_IOPORT
+
+config SPEAKUP_SYNTH_ACNTSA
+	tristate "Accent SA synthesizer support"
+	help
+		This is the Speakup driver for the Accent SA
+		synthesizer.  You can say y to build it into the kernel,
+		or m to build it as a module.  See the configuration
+		help on the Speakup choice above for more info.
+
+config SPEAKUP_SYNTH_ACNTPC
+	tristate "Accent PC synthesizer support"
+	depends on SPEAKUP_SERIALIO
+	help
+		This is the Speakup driver for the accent pc
+		synthesizer.  You can say y to build it into the kernel,
+		or m to build it as a module.  See the configuration
+		help on the Speakup choice above for more info.
+
+config SPEAKUP_SYNTH_APOLLO
+	tristate "Apollo II synthesizer support"
+	help
+		This is the Speakup driver for the Apollo II
+		synthesizer.  You can say y to build it into the kernel,
+		or m to build it as a module.  See the configuration
+		help on the Speakup choice above for more info.
+
+config SPEAKUP_SYNTH_AUDPTR
+	tristate "Audapter synthesizer support"
+	help
+		This is the Speakup driver for the Audapter synthesizer.
+		 You can say y to build it into the kernel, or m to
+		build it as a module.  See the configuration help on the
+		Speakup choice above for more info.
+
+config SPEAKUP_SYNTH_BNS
+	tristate "Braille 'n' Speak synthesizer support"
+	help
+		This is the Speakup driver for the Braille 'n' Speak
+		synthesizer.  You can say y to build it into the kernel,
+		or m to build it as a module.  See the configuration
+		help on the Speakup choice above for more info.
+
+config SPEAKUP_SYNTH_DECTLK
+	tristate "DECtalk Express synthesizer support"
+	help
+
+		This is the Speakup driver for the DecTalk Express
+		synthesizer.  You can say y to build it into the kernel,
+		or m to build it as a module.  See the configuration
+		help on the Speakup choice above for more info.
+
+config SPEAKUP_SYNTH_DECEXT
+	tristate "DECtalk External (old) synthesizer support"
+	help
+
+		This is the Speakup driver for the DecTalk External
+		(old) synthesizer.  You can say y to build it into the
+		kernel, or m to build it as a module.  See the
+		configuration help on the Speakup choice above for more
+		info.
+
+config SPEAKUP_SYNTH_DECPC
+	depends on m
+	depends on SPEAKUP_SERIALIO
+	tristate "DECtalk PC (big ISA card) synthesizer support"
+	help
+
+		This is the Speakup driver for the DecTalk PC (full
+		length ISA) synthesizer.  You can say m to build it as
+		a module.  See the configuration help on the Speakup
+		choice above for more info.
+
+		In order to use the DecTalk PC driver, you must download
+		the dec_pc.tgz file from linux-speakup.org.  It is in
+		the pub/linux/goodies directory.  The dec_pc.tgz file
+		contains the software which must be pre-loaded on to the
+		DecTalk PC board in order to use it with this driver.
+		This driver must be built as a module, and can not be
+		loaded until the file system is mounted and the DecTalk
+		PC software has been pre-loaded on to the board.
+
+		See the README file in the dec_pc.tgz file for more
+		details.
+
+config SPEAKUP_SYNTH_DTLK
+	tristate "DoubleTalk PC synthesizer support"
+	depends on SPEAKUP_SERIALIO
+	help
+
+		This is the Speakup driver for the internal DoubleTalk
+		PC synthesizer.  You can say y to build it into the
+		kernel, or m to build it as a module.  See the
+		configuration help on the Speakup choice above for more
+		info.
+
+config SPEAKUP_SYNTH_KEYPC
+	tristate "Keynote Gold PC synthesizer support"
+	depends on SPEAKUP_SERIALIO
+	help
+
+		This is the Speakup driver for the Keynote Gold
+		PC synthesizer.  You can say y to build it into the
+		kernel, or m to build it as a module.  See the
+		configuration help on the Speakup choice above for more
+		info.
+
+config SPEAKUP_SYNTH_LTLK
+	tristate "DoubleTalk LT/LiteTalk synthesizer support"
+help
+
+		This is the Speakup driver for the LiteTalk/DoubleTalk
+		LT synthesizer.  You can say y to build it into the
+		kernel, or m to build it as a module.  See the
+		configuration help on the Speakup choice above for more
+		info.
+
+config SPEAKUP_SYNTH_SOFT
+	tristate "Userspace software synthesizer support"
+	help
+
+		This is the software synthesizer device node.  It will
+		register a device /dev/softsynth which midware programs
+		and speech daemons may open and read to provide kernel
+		output to software synths such as espeak, festival,
+		flite and so forth.  You can select 'y' or 'm' to have
+		it built-in to the kernel or loaded as a module.
+
+config SPEAKUP_SYNTH_SPKOUT
+	tristate "Speak Out synthesizer support"
+	help
+
+		This is the Speakup driver for the Speakout synthesizer.
+		 You can say y to build it into the kernel, or m to
+		build it as a module.  See the configuration help on the
+		Speakup choice above for more info.
+
+config SPEAKUP_SYNTH_TXPRT
+	tristate "Transport synthesizer support"
+	help
+
+		This is the Speakup driver for the Transport
+		synthesizer.  You can say y to build it into the kernel,
+		or m to build it as a module.  See the configuration
+		help on the Speakup choice above for more info.
+
+config SPEAKUP_SYNTH_DUMMY
+	tristate "Dummy synthesizer driver (for testing)"
+	help
+
+		This is a dummy Speakup driver for plugging a mere serial
+		terminal.  This is handy if you want to test speakup but
+		don't have the hardware.  You can say y to build it into
+		the kernel, or m to build it as a module.  See the
+		configuration help on the Speakup choice above for more info.
+
+endif	# SPEAKUP
+endmenu