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, 114 insertions, 0 deletions

diff --git a/include/dt-bindings/leds/common.h b/include/dt-bindings/leds/common.h
new file mode 100644
index 000000000..b7bafbaf7
--- /dev/null
+++ b/include/dt-bindings/leds/common.h
@@ -0,0 +1,114 @@
+/* SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) */
+/*
+ * This header provides macros for the common LEDs device tree bindings.
+ *
+ * Copyright (C) 2015, Samsung Electronics Co., Ltd.
+ * Author: Jacek Anaszewski <j.anaszewski@samsung.com>
+ *
+ * Copyright (C) 2019 Jacek Anaszewski <jacek.anaszewski@gmail.com>
+ * Copyright (C) 2020 Pavel Machek <pavel@ucw.cz>
+ */
+
+#ifndef __DT_BINDINGS_LEDS_H
+#define __DT_BINDINGS_LEDS_H
+
+/* External trigger type */
+#define LEDS_TRIG_TYPE_EDGE	0
+#define LEDS_TRIG_TYPE_LEVEL	1
+
+/* Boost modes */
+#define LEDS_BOOST_OFF		0
+#define LEDS_BOOST_ADAPTIVE	1
+#define LEDS_BOOST_FIXED	2
+
+/* Standard LED colors */
+#define LED_COLOR_ID_WHITE	0
+#define LED_COLOR_ID_RED	1
+#define LED_COLOR_ID_GREEN	2
+#define LED_COLOR_ID_BLUE	3
+#define LED_COLOR_ID_AMBER	4
+#define LED_COLOR_ID_VIOLET	5
+#define LED_COLOR_ID_YELLOW	6
+#define LED_COLOR_ID_IR		7
+#define LED_COLOR_ID_MULTI	8	/* For multicolor LEDs */
+#define LED_COLOR_ID_RGB	9	/* For multicolor LEDs that can do arbitrary color,
+					   so this would include RGBW and similar */
+#define LED_COLOR_ID_PURPLE	10
+#define LED_COLOR_ID_ORANGE	11
+#define LED_COLOR_ID_PINK	12
+#define LED_COLOR_ID_CYAN	13
+#define LED_COLOR_ID_LIME	14
+#define LED_COLOR_ID_MAX	15
+
+/* Standard LED functions */
+/* Keyboard LEDs, usually it would be input4::capslock etc. */
+/*   Obsolete equivalent: "shift-key-light" */
+#define LED_FUNCTION_CAPSLOCK "capslock"
+#define LED_FUNCTION_SCROLLLOCK "scrolllock"
+#define LED_FUNCTION_NUMLOCK "numlock"
+#define LED_FUNCTION_FNLOCK "fnlock"
+/*   Obsolete equivalents: "tpacpi::thinklight" (IBM/Lenovo Thinkpads),
+     "lp5523:kb{1,2,3,4,5,6}" (Nokia N900) */
+#define LED_FUNCTION_KBD_BACKLIGHT "kbd_backlight"
+
+/* System LEDs, usually found on system body.
+   platform::mute (etc) is sometimes seen, :mute would be better */
+#define LED_FUNCTION_POWER "power"
+#define LED_FUNCTION_DISK "disk"
+
+/*   Obsolete: "platform:*:charging" (allwinner sun50i) */
+#define LED_FUNCTION_CHARGING "charging"
+/*   Used RGB notification LEDs common on phones.
+     Obsolete equivalents: "status-led:{red,green,blue}" (Motorola Droid 4),
+     "lp5523:{r,g,b}" (Nokia N900) */
+#define LED_FUNCTION_STATUS "status"
+
+#define LED_FUNCTION_MICMUTE "micmute"
+#define LED_FUNCTION_MUTE "mute"
+
+/* Used for player LEDs as found on game controllers from e.g. Nintendo, Sony. */
+#define LED_FUNCTION_PLAYER1 "player-1"
+#define LED_FUNCTION_PLAYER2 "player-2"
+#define LED_FUNCTION_PLAYER3 "player-3"
+#define LED_FUNCTION_PLAYER4 "player-4"
+#define LED_FUNCTION_PLAYER5 "player-5"
+
+/* Miscelleaus functions. Use functions above if you can. */
+#define LED_FUNCTION_ACTIVITY "activity"
+#define LED_FUNCTION_ALARM "alarm"
+#define LED_FUNCTION_BACKLIGHT "backlight"
+#define LED_FUNCTION_BLUETOOTH "bluetooth"
+#define LED_FUNCTION_BOOT "boot"
+#define LED_FUNCTION_CPU "cpu"
+#define LED_FUNCTION_DEBUG "debug"
+#define LED_FUNCTION_DISK_ACTIVITY "disk-activity"
+#define LED_FUNCTION_DISK_ERR "disk-err"
+#define LED_FUNCTION_DISK_READ "disk-read"
+#define LED_FUNCTION_DISK_WRITE "disk-write"
+#define LED_FUNCTION_FAULT "fault"
+#define LED_FUNCTION_FLASH "flash"
+#define LED_FUNCTION_HEARTBEAT "heartbeat"
+#define LED_FUNCTION_INDICATOR "indicator"
+#define LED_FUNCTION_LAN "lan"
+#define LED_FUNCTION_MAIL "mail"
+#define LED_FUNCTION_MOBILE "mobile"
+#define LED_FUNCTION_MTD "mtd"
+#define LED_FUNCTION_PANIC "panic"
+#define LED_FUNCTION_PROGRAMMING "programming"
+#define LED_FUNCTION_RX "rx"
+#define LED_FUNCTION_SD "sd"
+#define LED_FUNCTION_SPEED_LAN "speed-lan"
+#define LED_FUNCTION_SPEED_WAN "speed-wan"
+#define LED_FUNCTION_STANDBY "standby"
+#define LED_FUNCTION_TORCH "torch"
+#define LED_FUNCTION_TX "tx"
+#define LED_FUNCTION_USB "usb"
+#define LED_FUNCTION_WAN "wan"
+#define LED_FUNCTION_WAN_ONLINE "wan-online"
+#define LED_FUNCTION_WLAN "wlan"
+#define LED_FUNCTION_WLAN_2GHZ "wlan-2ghz"
+#define LED_FUNCTION_WLAN_5GHZ "wlan-5ghz"
+#define LED_FUNCTION_WLAN_6GHZ "wlan-6ghz"
+#define LED_FUNCTION_WPS "wps"
+
+#endif /* __DT_BINDINGS_LEDS_H */