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, 64 insertions, 0 deletions

diff --git a/drivers/usb/chipidea/Kconfig b/drivers/usb/chipidea/Kconfig
new file mode 100644
index 000000000..bab45bc62
--- /dev/null
+++ b/drivers/usb/chipidea/Kconfig
@@ -0,0 +1,64 @@
+# SPDX-License-Identifier: GPL-2.0
+
+config USB_CHIPIDEA
+	tristate "ChipIdea Highspeed Dual Role Controller"
+	depends on ((USB_EHCI_HCD && USB_GADGET) || (USB_EHCI_HCD && !USB_GADGET) || (!USB_EHCI_HCD && USB_GADGET)) && HAS_DMA
+	select EXTCON
+	select RESET_CONTROLLER
+	select USB_ULPI_BUS
+	select USB_ROLE_SWITCH
+	select USB_TEGRA_PHY if ARCH_TEGRA
+	help
+	  Say Y here if your system has a dual role high speed USB
+	  controller based on ChipIdea silicon IP. It supports:
+	  Dual-role switch (ID, OTG FSM, sysfs), Host-only, and
+	  Peripheral-only.
+
+	  When compiled dynamically, the module will be called ci_hdrc.ko.
+
+if USB_CHIPIDEA
+
+config USB_CHIPIDEA_UDC
+	bool "ChipIdea device controller"
+	depends on USB_GADGET
+	help
+	  Say Y here to enable device controller functionality of the
+	  ChipIdea driver.
+
+config USB_CHIPIDEA_HOST
+	bool "ChipIdea host controller"
+	depends on USB_EHCI_HCD
+	select USB_EHCI_ROOT_HUB_TT
+	help
+	  Say Y here to enable host controller functionality of the
+	  ChipIdea driver.
+
+config USB_CHIPIDEA_PCI
+	tristate "Enable PCI glue driver" if EXPERT
+	depends on USB_PCI
+	depends on NOP_USB_XCEIV
+	default USB_CHIPIDEA
+
+config USB_CHIPIDEA_MSM
+	tristate "Enable MSM hsusb glue driver" if EXPERT
+	default USB_CHIPIDEA
+
+config USB_CHIPIDEA_NPCM
+	tristate "Enable NPCM hsusb glue driver" if EXPERT
+	default USB_CHIPIDEA
+
+config USB_CHIPIDEA_IMX
+	tristate "Enable i.MX USB glue driver" if EXPERT
+	depends on OF
+	default USB_CHIPIDEA
+
+config USB_CHIPIDEA_GENERIC
+	tristate "Enable generic USB2 glue driver" if EXPERT
+	default USB_CHIPIDEA
+
+config USB_CHIPIDEA_TEGRA
+	tristate "Enable Tegra USB glue driver" if EXPERT
+	depends on OF
+	default USB_CHIPIDEA
+
+endif