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, 562 insertions, 0 deletions

diff --git a/drivers/input/misc/bma150.c b/drivers/input/misc/bma150.c
new file mode 100644
index 000000000..0ef282932
--- /dev/null
+++ b/drivers/input/misc/bma150.c
@@ -0,0 +1,562 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2011 Bosch Sensortec GmbH
+ * Copyright (c) 2011 Unixphere
+ *
+ * This driver adds support for Bosch Sensortec's digital acceleration
+ * sensors BMA150 and SMB380.
+ * The SMB380 is fully compatible with BMA150 and only differs in packaging.
+ *
+ * The datasheet for the BMA150 chip can be found here:
+ * http://www.bosch-sensortec.com/content/language1/downloads/BST-BMA150-DS000-07.pdf
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/pm.h>
+#include <linux/pm_runtime.h>
+#include <linux/bma150.h>
+
+#define ABSMAX_ACC_VAL		0x01FF
+#define ABSMIN_ACC_VAL		-(ABSMAX_ACC_VAL)
+
+/* Each axis is represented by a 2-byte data word */
+#define BMA150_XYZ_DATA_SIZE	6
+
+/* Input poll interval in milliseconds */
+#define BMA150_POLL_INTERVAL	10
+#define BMA150_POLL_MAX		200
+#define BMA150_POLL_MIN		0
+
+#define BMA150_MODE_NORMAL	0
+#define BMA150_MODE_SLEEP	2
+#define BMA150_MODE_WAKE_UP	3
+
+/* Data register addresses */
+#define BMA150_DATA_0_REG	0x00
+#define BMA150_DATA_1_REG	0x01
+#define BMA150_DATA_2_REG	0x02
+
+/* Control register addresses */
+#define BMA150_CTRL_0_REG	0x0A
+#define BMA150_CTRL_1_REG	0x0B
+#define BMA150_CTRL_2_REG	0x14
+#define BMA150_CTRL_3_REG	0x15
+
+/* Configuration/Setting register addresses */
+#define BMA150_CFG_0_REG	0x0C
+#define BMA150_CFG_1_REG	0x0D
+#define BMA150_CFG_2_REG	0x0E
+#define BMA150_CFG_3_REG	0x0F
+#define BMA150_CFG_4_REG	0x10
+#define BMA150_CFG_5_REG	0x11
+
+#define BMA150_CHIP_ID		2
+#define BMA150_CHIP_ID_REG	BMA150_DATA_0_REG
+
+#define BMA150_ACC_X_LSB_REG	BMA150_DATA_2_REG
+
+#define BMA150_SLEEP_POS	0
+#define BMA150_SLEEP_MSK	0x01
+#define BMA150_SLEEP_REG	BMA150_CTRL_0_REG
+
+#define BMA150_BANDWIDTH_POS	0
+#define BMA150_BANDWIDTH_MSK	0x07
+#define BMA150_BANDWIDTH_REG	BMA150_CTRL_2_REG
+
+#define BMA150_RANGE_POS	3
+#define BMA150_RANGE_MSK	0x18
+#define BMA150_RANGE_REG	BMA150_CTRL_2_REG
+
+#define BMA150_WAKE_UP_POS	0
+#define BMA150_WAKE_UP_MSK	0x01
+#define BMA150_WAKE_UP_REG	BMA150_CTRL_3_REG
+
+#define BMA150_SW_RES_POS	1
+#define BMA150_SW_RES_MSK	0x02
+#define BMA150_SW_RES_REG	BMA150_CTRL_0_REG
+
+/* Any-motion interrupt register fields */
+#define BMA150_ANY_MOTION_EN_POS	6
+#define BMA150_ANY_MOTION_EN_MSK	0x40
+#define BMA150_ANY_MOTION_EN_REG	BMA150_CTRL_1_REG
+
+#define BMA150_ANY_MOTION_DUR_POS	6
+#define BMA150_ANY_MOTION_DUR_MSK	0xC0
+#define BMA150_ANY_MOTION_DUR_REG	BMA150_CFG_5_REG
+
+#define BMA150_ANY_MOTION_THRES_REG	BMA150_CFG_4_REG
+
+/* Advanced interrupt register fields */
+#define BMA150_ADV_INT_EN_POS		6
+#define BMA150_ADV_INT_EN_MSK		0x40
+#define BMA150_ADV_INT_EN_REG		BMA150_CTRL_3_REG
+
+/* High-G interrupt register fields */
+#define BMA150_HIGH_G_EN_POS		1
+#define BMA150_HIGH_G_EN_MSK		0x02
+#define BMA150_HIGH_G_EN_REG		BMA150_CTRL_1_REG
+
+#define BMA150_HIGH_G_HYST_POS		3
+#define BMA150_HIGH_G_HYST_MSK		0x38
+#define BMA150_HIGH_G_HYST_REG		BMA150_CFG_5_REG
+
+#define BMA150_HIGH_G_DUR_REG		BMA150_CFG_3_REG
+#define BMA150_HIGH_G_THRES_REG		BMA150_CFG_2_REG
+
+/* Low-G interrupt register fields */
+#define BMA150_LOW_G_EN_POS		0
+#define BMA150_LOW_G_EN_MSK		0x01
+#define BMA150_LOW_G_EN_REG		BMA150_CTRL_1_REG
+
+#define BMA150_LOW_G_HYST_POS		0
+#define BMA150_LOW_G_HYST_MSK		0x07
+#define BMA150_LOW_G_HYST_REG		BMA150_CFG_5_REG
+
+#define BMA150_LOW_G_DUR_REG		BMA150_CFG_1_REG
+#define BMA150_LOW_G_THRES_REG		BMA150_CFG_0_REG
+
+struct bma150_data {
+	struct i2c_client *client;
+	struct input_dev *input;
+	u8 mode;
+};
+
+/*
+ * The settings for the given range, bandwidth and interrupt features
+ * are stated and verified by Bosch Sensortec where they are configured
+ * to provide a generic sensitivity performance.
+ */
+static const struct bma150_cfg default_cfg = {
+	.any_motion_int = 1,
+	.hg_int = 1,
+	.lg_int = 1,
+	.any_motion_dur = 0,
+	.any_motion_thres = 0,
+	.hg_hyst = 0,
+	.hg_dur = 150,
+	.hg_thres = 160,
+	.lg_hyst = 0,
+	.lg_dur = 150,
+	.lg_thres = 20,
+	.range = BMA150_RANGE_2G,
+	.bandwidth = BMA150_BW_50HZ
+};
+
+static int bma150_write_byte(struct i2c_client *client, u8 reg, u8 val)
+{
+	s32 ret;
+
+	/* As per specification, disable irq in between register writes */
+	if (client->irq)
+		disable_irq_nosync(client->irq);
+
+	ret = i2c_smbus_write_byte_data(client, reg, val);
+
+	if (client->irq)
+		enable_irq(client->irq);
+
+	return ret;
+}
+
+static int bma150_set_reg_bits(struct i2c_client *client,
+					int val, int shift, u8 mask, u8 reg)
+{
+	int data;
+
+	data = i2c_smbus_read_byte_data(client, reg);
+	if (data < 0)
+		return data;
+
+	data = (data & ~mask) | ((val << shift) & mask);
+	return bma150_write_byte(client, reg, data);
+}
+
+static int bma150_set_mode(struct bma150_data *bma150, u8 mode)
+{
+	int error;
+
+	error = bma150_set_reg_bits(bma150->client, mode, BMA150_WAKE_UP_POS,
+				BMA150_WAKE_UP_MSK, BMA150_WAKE_UP_REG);
+	if (error)
+		return error;
+
+	error = bma150_set_reg_bits(bma150->client, mode, BMA150_SLEEP_POS,
+				BMA150_SLEEP_MSK, BMA150_SLEEP_REG);
+	if (error)
+		return error;
+
+	if (mode == BMA150_MODE_NORMAL)
+		usleep_range(2000, 2100);
+
+	bma150->mode = mode;
+	return 0;
+}
+
+static int bma150_soft_reset(struct bma150_data *bma150)
+{
+	int error;
+
+	error = bma150_set_reg_bits(bma150->client, 1, BMA150_SW_RES_POS,
+				BMA150_SW_RES_MSK, BMA150_SW_RES_REG);
+	if (error)
+		return error;
+
+	usleep_range(2000, 2100);
+	return 0;
+}
+
+static int bma150_set_range(struct bma150_data *bma150, u8 range)
+{
+	return bma150_set_reg_bits(bma150->client, range, BMA150_RANGE_POS,
+				BMA150_RANGE_MSK, BMA150_RANGE_REG);
+}
+
+static int bma150_set_bandwidth(struct bma150_data *bma150, u8 bw)
+{
+	return bma150_set_reg_bits(bma150->client, bw, BMA150_BANDWIDTH_POS,
+				BMA150_BANDWIDTH_MSK, BMA150_BANDWIDTH_REG);
+}
+
+static int bma150_set_low_g_interrupt(struct bma150_data *bma150,
+					u8 enable, u8 hyst, u8 dur, u8 thres)
+{
+	int error;
+
+	error = bma150_set_reg_bits(bma150->client, hyst,
+				BMA150_LOW_G_HYST_POS, BMA150_LOW_G_HYST_MSK,
+				BMA150_LOW_G_HYST_REG);
+	if (error)
+		return error;
+
+	error = bma150_write_byte(bma150->client, BMA150_LOW_G_DUR_REG, dur);
+	if (error)
+		return error;
+
+	error = bma150_write_byte(bma150->client, BMA150_LOW_G_THRES_REG, thres);
+	if (error)
+		return error;
+
+	return bma150_set_reg_bits(bma150->client, !!enable,
+				BMA150_LOW_G_EN_POS, BMA150_LOW_G_EN_MSK,
+				BMA150_LOW_G_EN_REG);
+}
+
+static int bma150_set_high_g_interrupt(struct bma150_data *bma150,
+					u8 enable, u8 hyst, u8 dur, u8 thres)
+{
+	int error;
+
+	error = bma150_set_reg_bits(bma150->client, hyst,
+				BMA150_HIGH_G_HYST_POS, BMA150_HIGH_G_HYST_MSK,
+				BMA150_HIGH_G_HYST_REG);
+	if (error)
+		return error;
+
+	error = bma150_write_byte(bma150->client,
+				BMA150_HIGH_G_DUR_REG, dur);
+	if (error)
+		return error;
+
+	error = bma150_write_byte(bma150->client,
+				BMA150_HIGH_G_THRES_REG, thres);
+	if (error)
+		return error;
+
+	return bma150_set_reg_bits(bma150->client, !!enable,
+				BMA150_HIGH_G_EN_POS, BMA150_HIGH_G_EN_MSK,
+				BMA150_HIGH_G_EN_REG);
+}
+
+
+static int bma150_set_any_motion_interrupt(struct bma150_data *bma150,
+						u8 enable, u8 dur, u8 thres)
+{
+	int error;
+
+	error = bma150_set_reg_bits(bma150->client, dur,
+				BMA150_ANY_MOTION_DUR_POS,
+				BMA150_ANY_MOTION_DUR_MSK,
+				BMA150_ANY_MOTION_DUR_REG);
+	if (error)
+		return error;
+
+	error = bma150_write_byte(bma150->client,
+				BMA150_ANY_MOTION_THRES_REG, thres);
+	if (error)
+		return error;
+
+	error = bma150_set_reg_bits(bma150->client, !!enable,
+				BMA150_ADV_INT_EN_POS, BMA150_ADV_INT_EN_MSK,
+				BMA150_ADV_INT_EN_REG);
+	if (error)
+		return error;
+
+	return bma150_set_reg_bits(bma150->client, !!enable,
+				BMA150_ANY_MOTION_EN_POS,
+				BMA150_ANY_MOTION_EN_MSK,
+				BMA150_ANY_MOTION_EN_REG);
+}
+
+static void bma150_report_xyz(struct bma150_data *bma150)
+{
+	u8 data[BMA150_XYZ_DATA_SIZE];
+	s16 x, y, z;
+	s32 ret;
+
+	ret = i2c_smbus_read_i2c_block_data(bma150->client,
+			BMA150_ACC_X_LSB_REG, BMA150_XYZ_DATA_SIZE, data);
+	if (ret != BMA150_XYZ_DATA_SIZE)
+		return;
+
+	x = ((0xc0 & data[0]) >> 6) | (data[1] << 2);
+	y = ((0xc0 & data[2]) >> 6) | (data[3] << 2);
+	z = ((0xc0 & data[4]) >> 6) | (data[5] << 2);
+
+	x = sign_extend32(x, 9);
+	y = sign_extend32(y, 9);
+	z = sign_extend32(z, 9);
+
+	input_report_abs(bma150->input, ABS_X, x);
+	input_report_abs(bma150->input, ABS_Y, y);
+	input_report_abs(bma150->input, ABS_Z, z);
+	input_sync(bma150->input);
+}
+
+static irqreturn_t bma150_irq_thread(int irq, void *dev)
+{
+	bma150_report_xyz(dev);
+
+	return IRQ_HANDLED;
+}
+
+static void bma150_poll(struct input_dev *input)
+{
+	struct bma150_data *bma150 = input_get_drvdata(input);
+
+	bma150_report_xyz(bma150);
+}
+
+static int bma150_open(struct input_dev *input)
+{
+	struct bma150_data *bma150 = input_get_drvdata(input);
+	int error;
+
+	error = pm_runtime_get_sync(&bma150->client->dev);
+	if (error < 0 && error != -ENOSYS)
+		return error;
+
+	/*
+	 * See if runtime PM woke up the device. If runtime PM
+	 * is disabled we need to do it ourselves.
+	 */
+	if (bma150->mode != BMA150_MODE_NORMAL) {
+		error = bma150_set_mode(bma150, BMA150_MODE_NORMAL);
+		if (error)
+			return error;
+	}
+
+	return 0;
+}
+
+static void bma150_close(struct input_dev *input)
+{
+	struct bma150_data *bma150 = input_get_drvdata(input);
+
+	pm_runtime_put_sync(&bma150->client->dev);
+
+	if (bma150->mode != BMA150_MODE_SLEEP)
+		bma150_set_mode(bma150, BMA150_MODE_SLEEP);
+}
+
+static int bma150_initialize(struct bma150_data *bma150,
+			     const struct bma150_cfg *cfg)
+{
+	int error;
+
+	error = bma150_soft_reset(bma150);
+	if (error)
+		return error;
+
+	error = bma150_set_bandwidth(bma150, cfg->bandwidth);
+	if (error)
+		return error;
+
+	error = bma150_set_range(bma150, cfg->range);
+	if (error)
+		return error;
+
+	if (bma150->client->irq) {
+		error = bma150_set_any_motion_interrupt(bma150,
+					cfg->any_motion_int,
+					cfg->any_motion_dur,
+					cfg->any_motion_thres);
+		if (error)
+			return error;
+
+		error = bma150_set_high_g_interrupt(bma150,
+					cfg->hg_int, cfg->hg_hyst,
+					cfg->hg_dur, cfg->hg_thres);
+		if (error)
+			return error;
+
+		error = bma150_set_low_g_interrupt(bma150,
+					cfg->lg_int, cfg->lg_hyst,
+					cfg->lg_dur, cfg->lg_thres);
+		if (error)
+			return error;
+	}
+
+	return bma150_set_mode(bma150, BMA150_MODE_SLEEP);
+}
+
+static int bma150_probe(struct i2c_client *client)
+{
+	const struct bma150_platform_data *pdata =
+			dev_get_platdata(&client->dev);
+	const struct bma150_cfg *cfg;
+	struct bma150_data *bma150;
+	struct input_dev *idev;
+	int chip_id;
+	int error;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
+		dev_err(&client->dev, "i2c_check_functionality error\n");
+		return -EIO;
+	}
+
+	chip_id = i2c_smbus_read_byte_data(client, BMA150_CHIP_ID_REG);
+	if (chip_id != BMA150_CHIP_ID) {
+		dev_err(&client->dev, "BMA150 chip id error: %d\n", chip_id);
+		return -EINVAL;
+	}
+
+	bma150 = devm_kzalloc(&client->dev, sizeof(*bma150), GFP_KERNEL);
+	if (!bma150)
+		return -ENOMEM;
+
+	bma150->client = client;
+
+	if (pdata) {
+		if (pdata->irq_gpio_cfg) {
+			error = pdata->irq_gpio_cfg();
+			if (error) {
+				dev_err(&client->dev,
+					"IRQ GPIO conf. error %d, error %d\n",
+					client->irq, error);
+				return error;
+			}
+		}
+		cfg = &pdata->cfg;
+	} else {
+		cfg = &default_cfg;
+	}
+
+	error = bma150_initialize(bma150, cfg);
+	if (error)
+		return error;
+
+	idev = devm_input_allocate_device(&bma150->client->dev);
+	if (!idev)
+		return -ENOMEM;
+
+	input_set_drvdata(idev, bma150);
+	bma150->input = idev;
+
+	idev->name = BMA150_DRIVER;
+	idev->phys = BMA150_DRIVER "/input0";
+	idev->id.bustype = BUS_I2C;
+
+	idev->open = bma150_open;
+	idev->close = bma150_close;
+
+	input_set_abs_params(idev, ABS_X, ABSMIN_ACC_VAL, ABSMAX_ACC_VAL, 0, 0);
+	input_set_abs_params(idev, ABS_Y, ABSMIN_ACC_VAL, ABSMAX_ACC_VAL, 0, 0);
+	input_set_abs_params(idev, ABS_Z, ABSMIN_ACC_VAL, ABSMAX_ACC_VAL, 0, 0);
+
+	if (client->irq <= 0) {
+		error = input_setup_polling(idev, bma150_poll);
+		if (error)
+			return error;
+
+		input_set_poll_interval(idev, BMA150_POLL_INTERVAL);
+		input_set_min_poll_interval(idev, BMA150_POLL_MIN);
+		input_set_max_poll_interval(idev, BMA150_POLL_MAX);
+	}
+
+	error = input_register_device(idev);
+	if (error)
+		return error;
+
+	if (client->irq > 0) {
+		error = devm_request_threaded_irq(&client->dev, client->irq,
+					NULL, bma150_irq_thread,
+					IRQF_TRIGGER_RISING | IRQF_ONESHOT,
+					BMA150_DRIVER, bma150);
+		if (error) {
+			dev_err(&client->dev,
+				"irq request failed %d, error %d\n",
+				client->irq, error);
+			return error;
+		}
+	}
+
+	i2c_set_clientdata(client, bma150);
+
+	pm_runtime_enable(&client->dev);
+
+	return 0;
+}
+
+static void bma150_remove(struct i2c_client *client)
+{
+	pm_runtime_disable(&client->dev);
+}
+
+static int __maybe_unused bma150_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct bma150_data *bma150 = i2c_get_clientdata(client);
+
+	return bma150_set_mode(bma150, BMA150_MODE_SLEEP);
+}
+
+static int __maybe_unused bma150_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct bma150_data *bma150 = i2c_get_clientdata(client);
+
+	return bma150_set_mode(bma150, BMA150_MODE_NORMAL);
+}
+
+static UNIVERSAL_DEV_PM_OPS(bma150_pm, bma150_suspend, bma150_resume, NULL);
+
+static const struct i2c_device_id bma150_id[] = {
+	{ .name = "bma150" },
+	{ .name = "smb380" },
+	{ .name = "bma023" },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(i2c, bma150_id);
+
+static struct i2c_driver bma150_driver = {
+	.driver = {
+		.name	= BMA150_DRIVER,
+		.pm	= &bma150_pm,
+	},
+	.class		= I2C_CLASS_HWMON,
+	.id_table	= bma150_id,
+	.probe		= bma150_probe,
+	.remove		= bma150_remove,
+};
+
+module_i2c_driver(bma150_driver);
+
+MODULE_AUTHOR("Albert Zhang <xu.zhang@bosch-sensortec.com>");
+MODULE_DESCRIPTION("BMA150 driver");
+MODULE_LICENSE("GPL");