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, 73 insertions, 0 deletions

diff --git a/drivers/nfc/Kconfig b/drivers/nfc/Kconfig
new file mode 100644
index 000000000..288c6f1c6
--- /dev/null
+++ b/drivers/nfc/Kconfig
@@ -0,0 +1,73 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Near Field Communication (NFC) devices
+#
+
+menu "Near Field Communication (NFC) devices"
+	depends on NFC
+
+config NFC_TRF7970A
+	tristate "Texas Instruments TRF7970a NFC driver"
+	depends on SPI && NFC_DIGITAL && GPIOLIB
+	help
+	  This option enables the NFC driver for Texas Instruments' TRF7970a
+	  device. Such device supports 5 different protocols: ISO14443A,
+	  ISO14443B, FeLiCa, ISO15693 and ISO18000-3.
+
+	  Say Y here to compile support for TRF7970a into the kernel or
+	  say M  to compile it as a module. The module will be called
+	  trf7970a.ko.
+
+config NFC_MEI_PHY
+	tristate "MEI bus NFC device support"
+	depends on INTEL_MEI && NFC_HCI
+	help
+	  This adds support to use an mei bus nfc device. Select this if you
+	  will use an HCI NFC driver for an NFC chip connected behind an
+	  Intel's Management Engine chip.
+
+	  If unsure, say N.
+
+config NFC_SIM
+	tristate "NFC hardware simulator driver"
+	depends on NFC_DIGITAL
+	help
+	  This driver declares two virtual NFC devices supporting NFC-DEP
+	  protocol. An LLCP connection can be established between them and
+	  all packets sent from one device is sent back to the other, acting as
+	  loopback devices.
+
+	  If unsure, say N.
+
+config NFC_PORT100
+	tristate "Sony NFC Port-100 Series USB device support"
+	depends on USB
+	depends on NFC_DIGITAL
+	help
+	  This adds support for Sony Port-100 chip based USB devices such as the
+	  RC-S380 dongle.
+
+	  If unsure, say N.
+
+config NFC_VIRTUAL_NCI
+	tristate "NCI device simulator driver"
+	depends on NFC_NCI
+	help
+	  NCI virtual device simulates a NCI device to the user.
+	  It can be used to validate the NCI module and applications.
+	  This driver supports communication between the virtual NCI device and
+	  module.
+
+	  If unsure, say N.
+
+source "drivers/nfc/fdp/Kconfig"
+source "drivers/nfc/pn544/Kconfig"
+source "drivers/nfc/pn533/Kconfig"
+source "drivers/nfc/microread/Kconfig"
+source "drivers/nfc/nfcmrvl/Kconfig"
+source "drivers/nfc/st21nfca/Kconfig"
+source "drivers/nfc/st-nci/Kconfig"
+source "drivers/nfc/nxp-nci/Kconfig"
+source "drivers/nfc/s3fwrn5/Kconfig"
+source "drivers/nfc/st95hf/Kconfig"
+endmenu