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, 436 insertions, 0 deletions

diff --git a/drivers/hid/hid-winwing.c b/drivers/hid/hid-winwing.c
new file mode 100644
index 000000000..9cd25a779
--- /dev/null
+++ b/drivers/hid/hid-winwing.c
@@ -0,0 +1,436 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * HID driver for WinWing Orion 2 throttle
+ *
+ * Copyright (c) 2023 Ivan Gorinov
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/hidraw.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/workqueue.h>
+
+#define MAX_REPORT 16
+
+struct winwing_led {
+	struct led_classdev cdev;
+	struct hid_device *hdev;
+	int number;
+};
+
+struct winwing_led_info {
+	int number;
+	int max_brightness;
+	const char *led_name;
+};
+
+static const struct winwing_led_info led_info[3] = {
+	{ 0, 255, "backlight" },
+	{ 1, 1, "a-a" },
+	{ 2, 1, "a-g" },
+};
+
+struct winwing_drv_data {
+	struct hid_device *hdev;
+	struct mutex lights_lock;
+	__u8 *report_lights;
+	__u8 *report_rumble;
+	struct work_struct rumble_work;
+	struct ff_rumble_effect rumble;
+	int rumble_left;
+	int rumble_right;
+	int has_grip15;
+	struct winwing_led leds[];
+};
+
+static int winwing_led_write(struct led_classdev *cdev,
+		enum led_brightness br)
+{
+	struct winwing_led *led = (struct winwing_led *) cdev;
+	struct winwing_drv_data *data = hid_get_drvdata(led->hdev);
+	__u8 *buf = data->report_lights;
+	int ret;
+
+	mutex_lock(&data->lights_lock);
+
+	/*
+	 * Mimicking requests captured by usbmon when LEDs
+	 * are controlled by the vendor's app in a VM.
+	 */
+	buf[0] = 0x02;
+	buf[1] = 0x60;
+	buf[2] = 0xbe;
+	buf[3] = 0x00;
+	buf[4] = 0x00;
+	buf[5] = 0x03;
+	buf[6] = 0x49;
+	buf[7] = led->number;
+	buf[8] = br;
+	buf[9] = 0x00;
+	buf[10] = 0;
+	buf[11] = 0;
+	buf[12] = 0;
+	buf[13] = 0;
+
+	ret = hid_hw_output_report(led->hdev, buf, 14);
+
+	mutex_unlock(&data->lights_lock);
+
+	return ret;
+}
+
+static int winwing_init_led(struct hid_device *hdev,
+		struct input_dev *input)
+{
+	struct winwing_drv_data *data;
+	struct winwing_led *led;
+	int ret;
+	int i;
+
+	data = hid_get_drvdata(hdev);
+
+	if (!data)
+		return -EINVAL;
+
+	data->report_lights = devm_kzalloc(&hdev->dev, MAX_REPORT, GFP_KERNEL);
+
+	if (!data->report_lights)
+		return -ENOMEM;
+
+	for (i = 0; i < 3; i += 1) {
+		const struct winwing_led_info *info = &led_info[i];
+
+		led = &data->leds[i];
+		led->hdev = hdev;
+		led->number = info->number;
+		led->cdev.max_brightness = info->max_brightness;
+		led->cdev.brightness_set_blocking = winwing_led_write;
+		led->cdev.flags = LED_HW_PLUGGABLE;
+		led->cdev.name = devm_kasprintf(&hdev->dev, GFP_KERNEL,
+						"%s::%s",
+						dev_name(&input->dev),
+						info->led_name);
+
+		if (!led->cdev.name)
+			return -ENOMEM;
+
+		ret = devm_led_classdev_register(&hdev->dev, &led->cdev);
+		if (ret)
+			return ret;
+	}
+
+	return ret;
+}
+
+static int winwing_map_button(int button, int has_grip15)
+{
+	if (button < 1)
+		return KEY_RESERVED;
+
+	if (button > 112)
+		return KEY_RESERVED;
+
+	if (button <= 16) {
+		/*
+		 * Grip buttons [1 .. 16] are mapped to
+		 * key codes BTN_TRIGGER .. BTN_DEAD
+		 */
+		return (button - 1) + BTN_JOYSTICK;
+	}
+
+	if (button >= 65) {
+		/*
+		 * Base buttons [65 .. 112] are mapped to
+		 * key codes BTN_TRIGGER_HAPPY17 .. KEY_MAX
+		 */
+		return (button - 65) + BTN_TRIGGER_HAPPY17;
+	}
+
+	if (!has_grip15) {
+		/*
+		 * Not mapping numbers [33 .. 64] which
+		 * are not assigned to any real buttons
+		 */
+		if (button >= 33)
+			return KEY_RESERVED;
+		/*
+		 * Grip buttons [17 .. 32] are mapped to
+		 * BTN_TRIGGER_HAPPY1 .. BTN_TRIGGER_HAPPY16
+		 */
+		return (button - 17) + BTN_TRIGGER_HAPPY1;
+	}
+
+	if (button >= 49) {
+		/*
+		 * Grip buttons [49 .. 64] are mapped to
+		 * BTN_TRIGGER_HAPPY1 .. BTN_TRIGGER_HAPPY16
+		 */
+		return (button - 49) + BTN_TRIGGER_HAPPY1;
+	}
+
+	/*
+	 * Grip buttons [17 .. 44] are mapped to
+	 * key codes KEY_MACRO1 .. KEY_MACRO28;
+	 * also mapping numbers [45 .. 48] which
+	 * are not assigned to any real buttons.
+	 */
+	return (button - 17) + KEY_MACRO1;
+}
+
+static int winwing_input_mapping(struct hid_device *hdev,
+	struct hid_input *hi, struct hid_field *field, struct hid_usage *usage,
+	unsigned long **bit, int *max)
+{
+	struct winwing_drv_data *data;
+	int code = KEY_RESERVED;
+	int button = 0;
+
+	data = hid_get_drvdata(hdev);
+
+	if (!data)
+		return -EINVAL;
+
+	if ((usage->hid & HID_USAGE_PAGE) != HID_UP_BUTTON)
+		return 0;
+
+	if (field->application != HID_GD_JOYSTICK)
+		return 0;
+
+	/* Button numbers start with 1 */
+	button = usage->hid & HID_USAGE;
+
+	code = winwing_map_button(button, data->has_grip15);
+
+	hid_map_usage(hi, usage, bit, max, EV_KEY, code);
+
+	return 1;
+}
+
+/*
+ * If x ≤ 0, return 0;
+ * if x is in [1 .. 65535], return a value in [1 .. 255]
+ */
+static inline int convert_magnitude(int x)
+{
+	if (x < 1)
+		return 0;
+
+	return ((x * 255) >> 16) + 1;
+}
+
+static int winwing_haptic_rumble(struct winwing_drv_data *data)
+{
+	__u8 *buf;
+	__u8 m;
+
+	if (!data)
+		return -EINVAL;
+
+	if (!data->hdev)
+		return -EINVAL;
+
+	buf = data->report_rumble;
+
+	if (!buf)
+		return -EINVAL;
+
+	m = convert_magnitude(data->rumble.strong_magnitude);
+	if (m != data->rumble_left) {
+		int ret;
+
+		/*
+		 * Mimicking requests captured by usbmon when rumble
+		 * is activated by the vendor's app in a VM.
+		 */
+		buf[0] = 0x02;
+		buf[1] = 0x01;
+		buf[2] = 0xbf;
+		buf[3] = 0x00;
+		buf[4] = 0x00;
+		buf[5] = 0x03;
+		buf[6] = 0x49;
+		buf[7] = 0x00;
+		buf[8] = m;
+		buf[9] = 0x00;
+		buf[10] = 0;
+		buf[11] = 0;
+		buf[12] = 0;
+		buf[13] = 0;
+
+		ret = hid_hw_output_report(data->hdev, buf, 14);
+		if (ret < 0) {
+			hid_err(data->hdev, "error %d (%*ph)\n", ret, 14, buf);
+			return ret;
+		}
+		data->rumble_left = m;
+	}
+
+	m = convert_magnitude(data->rumble.weak_magnitude);
+	if (m != data->rumble_right) {
+		int ret;
+
+		/*
+		 * Mimicking requests captured by usbmon when rumble
+		 * is activated by the vendor's app in a VM.
+		 */
+		buf[0] = 0x02;
+		buf[1] = 0x03;
+		buf[2] = 0xbf;
+		buf[3] = 0x00;
+		buf[4] = 0x00;
+		buf[5] = 0x03;
+		buf[6] = 0x49;
+		buf[7] = 0x00;
+		buf[8] = m;
+		buf[9] = 0x00;
+		buf[10] = 0;
+		buf[11] = 0;
+		buf[12] = 0;
+		buf[13] = 0;
+
+		ret = hid_hw_output_report(data->hdev, buf, 14);
+		if (ret < 0) {
+			hid_err(data->hdev, "error %d (%*ph)\n", ret, 14, buf);
+			return ret;
+		}
+		data->rumble_right = m;
+	}
+
+	return 0;
+}
+
+
+static void winwing_haptic_rumble_cb(struct work_struct *work)
+{
+	struct winwing_drv_data *data;
+
+	data = container_of(work, struct winwing_drv_data, rumble_work);
+	winwing_haptic_rumble(data);
+}
+
+static int winwing_play_effect(struct input_dev *dev, void *context,
+		struct ff_effect *effect)
+{
+	struct winwing_drv_data *data = (struct winwing_drv_data *) context;
+
+	if (effect->type != FF_RUMBLE)
+		return 0;
+
+	if (!data)
+		return -EINVAL;
+
+	data->rumble = effect->u.rumble;
+
+	return schedule_work(&data->rumble_work);
+}
+
+static int winwing_init_ff(struct hid_device *hdev, struct hid_input *hidinput)
+{
+	struct winwing_drv_data *data;
+
+	data = (struct winwing_drv_data *) hid_get_drvdata(hdev);
+	if (!data)
+		return -EINVAL;
+
+	data->report_rumble = devm_kzalloc(&hdev->dev, MAX_REPORT, GFP_KERNEL);
+	data->rumble_left = -1;
+	data->rumble_right = -1;
+
+	input_set_capability(hidinput->input, EV_FF, FF_RUMBLE);
+
+	return input_ff_create_memless(hidinput->input, data,
+			winwing_play_effect);
+}
+
+static int winwing_probe(struct hid_device *hdev,
+		const struct hid_device_id *id)
+{
+	struct winwing_drv_data *data;
+	size_t data_size = struct_size(data, leds, 3);
+	int ret;
+
+	ret = hid_parse(hdev);
+	if (ret) {
+		hid_err(hdev, "parse failed\n");
+		return ret;
+	}
+
+	data = devm_kzalloc(&hdev->dev, data_size, GFP_KERNEL);
+
+	if (!data)
+		return -ENOMEM;
+
+	data->hdev = hdev;
+	data->has_grip15 = id->driver_data;
+	hid_set_drvdata(hdev, data);
+
+	INIT_WORK(&data->rumble_work, winwing_haptic_rumble_cb);
+
+	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+	if (ret) {
+		hid_err(hdev, "hw start failed\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static void winwing_remove(struct hid_device *hdev)
+{
+	struct winwing_drv_data *data;
+
+	data = (struct winwing_drv_data *) hid_get_drvdata(hdev);
+
+	if (data)
+		cancel_work_sync(&data->rumble_work);
+
+	hid_hw_close(hdev);
+	hid_hw_stop(hdev);
+}
+
+static int winwing_input_configured(struct hid_device *hdev,
+		struct hid_input *hidinput)
+{
+	struct winwing_drv_data *data;
+	int ret;
+
+	data = (struct winwing_drv_data *) hid_get_drvdata(hdev);
+
+	ret = winwing_init_led(hdev, hidinput->input);
+
+	if (ret)
+		hid_err(hdev, "led init failed\n");
+
+	if (data->has_grip15)
+		winwing_init_ff(hdev, hidinput);
+
+	return ret;
+}
+
+/* Set driver_data to 1 for grips with rumble motor and more than 32 buttons */
+static const struct hid_device_id winwing_devices[] = {
+	{ HID_USB_DEVICE(0x4098, 0xbd65), .driver_data = 1 },  /* TGRIP-15E  */
+	{ HID_USB_DEVICE(0x4098, 0xbd64), .driver_data = 1 },  /* TGRIP-15EX */
+	{ HID_USB_DEVICE(0x4098, 0xbe68), .driver_data = 0 },  /* TGRIP-16EX */
+	{ HID_USB_DEVICE(0x4098, 0xbe62), .driver_data = 0 },  /* TGRIP-18   */
+	{}
+};
+
+MODULE_DEVICE_TABLE(hid, winwing_devices);
+
+static struct hid_driver winwing_driver = {
+	.name = "winwing",
+	.id_table = winwing_devices,
+	.input_configured = winwing_input_configured,
+	.input_mapping = winwing_input_mapping,
+	.probe = winwing_probe,
+	.remove = winwing_remove,
+};
+module_hid_driver(winwing_driver);
+
+MODULE_DESCRIPTION("HID driver for WinWing Orion 2 throttle");
+MODULE_LICENSE("GPL");