x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.

The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:

<__hrtimer_run_queues+249>:  nopl   0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>:  mov    %r14,%rdi
<__hrtimer_run_queues+257>:  cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>:  mov    %eax,%r12d
<__hrtimer_run_queues+266>:  xchg   %ax,%ax
<__hrtimer_run_queues+268>:  mov    %r13,%rdi

Which triggers this crash:

  BUG: unable to handle page fault for address: 00000000000f41c9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
  RIP: 0010:__hrtimer_run_queues+0x106/0x230

Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.

The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.

During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.

Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.

[ mingo: Refined the changelog ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

1 files changed, 561 insertions, 0 deletions

diff --git a/drivers/mfd/stmfx.c b/drivers/mfd/stmfx.c
new file mode 100644
index 000000000..f683fdb6e
--- /dev/null
+++ b/drivers/mfd/stmfx.c
@@ -0,0 +1,561 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for STMicroelectronics Multi-Function eXpander (STMFX) core
+ *
+ * Copyright (C) 2019 STMicroelectronics
+ * Author(s): Amelie Delaunay <amelie.delaunay@st.com>.
+ */
+#include <linux/bitfield.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/stmfx.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+
+static bool stmfx_reg_volatile(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case STMFX_REG_SYS_CTRL:
+	case STMFX_REG_IRQ_SRC_EN:
+	case STMFX_REG_IRQ_PENDING:
+	case STMFX_REG_IRQ_GPI_PENDING1:
+	case STMFX_REG_IRQ_GPI_PENDING2:
+	case STMFX_REG_IRQ_GPI_PENDING3:
+	case STMFX_REG_GPIO_STATE1:
+	case STMFX_REG_GPIO_STATE2:
+	case STMFX_REG_GPIO_STATE3:
+	case STMFX_REG_IRQ_GPI_SRC1:
+	case STMFX_REG_IRQ_GPI_SRC2:
+	case STMFX_REG_IRQ_GPI_SRC3:
+	case STMFX_REG_GPO_SET1:
+	case STMFX_REG_GPO_SET2:
+	case STMFX_REG_GPO_SET3:
+	case STMFX_REG_GPO_CLR1:
+	case STMFX_REG_GPO_CLR2:
+	case STMFX_REG_GPO_CLR3:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool stmfx_reg_writeable(struct device *dev, unsigned int reg)
+{
+	return (reg >= STMFX_REG_SYS_CTRL);
+}
+
+static const struct regmap_config stmfx_regmap_config = {
+	.reg_bits	= 8,
+	.reg_stride	= 1,
+	.val_bits	= 8,
+	.max_register	= STMFX_REG_MAX,
+	.volatile_reg	= stmfx_reg_volatile,
+	.writeable_reg	= stmfx_reg_writeable,
+	.cache_type	= REGCACHE_MAPLE,
+};
+
+static const struct resource stmfx_pinctrl_resources[] = {
+	DEFINE_RES_IRQ(STMFX_REG_IRQ_SRC_EN_GPIO),
+};
+
+static const struct resource stmfx_idd_resources[] = {
+	DEFINE_RES_IRQ(STMFX_REG_IRQ_SRC_EN_IDD),
+	DEFINE_RES_IRQ(STMFX_REG_IRQ_SRC_EN_ERROR),
+};
+
+static const struct resource stmfx_ts_resources[] = {
+	DEFINE_RES_IRQ(STMFX_REG_IRQ_SRC_EN_TS_DET),
+	DEFINE_RES_IRQ(STMFX_REG_IRQ_SRC_EN_TS_NE),
+	DEFINE_RES_IRQ(STMFX_REG_IRQ_SRC_EN_TS_TH),
+	DEFINE_RES_IRQ(STMFX_REG_IRQ_SRC_EN_TS_FULL),
+	DEFINE_RES_IRQ(STMFX_REG_IRQ_SRC_EN_TS_OVF),
+};
+
+static struct mfd_cell stmfx_cells[] = {
+	{
+		.of_compatible = "st,stmfx-0300-pinctrl",
+		.name = "stmfx-pinctrl",
+		.resources = stmfx_pinctrl_resources,
+		.num_resources = ARRAY_SIZE(stmfx_pinctrl_resources),
+	},
+	{
+		.of_compatible = "st,stmfx-0300-idd",
+		.name = "stmfx-idd",
+		.resources = stmfx_idd_resources,
+		.num_resources = ARRAY_SIZE(stmfx_idd_resources),
+	},
+	{
+		.of_compatible = "st,stmfx-0300-ts",
+		.name = "stmfx-ts",
+		.resources = stmfx_ts_resources,
+		.num_resources = ARRAY_SIZE(stmfx_ts_resources),
+	},
+};
+
+static u8 stmfx_func_to_mask(u32 func)
+{
+	u8 mask = 0;
+
+	if (func & STMFX_FUNC_GPIO)
+		mask |= STMFX_REG_SYS_CTRL_GPIO_EN;
+
+	if ((func & STMFX_FUNC_ALTGPIO_LOW) || (func & STMFX_FUNC_ALTGPIO_HIGH))
+		mask |= STMFX_REG_SYS_CTRL_ALTGPIO_EN;
+
+	if (func & STMFX_FUNC_TS)
+		mask |= STMFX_REG_SYS_CTRL_TS_EN;
+
+	if (func & STMFX_FUNC_IDD)
+		mask |= STMFX_REG_SYS_CTRL_IDD_EN;
+
+	return mask;
+}
+
+int stmfx_function_enable(struct stmfx *stmfx, u32 func)
+{
+	u32 sys_ctrl;
+	u8 mask;
+	int ret;
+
+	ret = regmap_read(stmfx->map, STMFX_REG_SYS_CTRL, &sys_ctrl);
+	if (ret)
+		return ret;
+
+	/*
+	 * IDD and TS have priority in STMFX FW, so if IDD and TS are enabled,
+	 * ALTGPIO function is disabled by STMFX FW. If IDD or TS is enabled,
+	 * the number of aGPIO available decreases. To avoid GPIO management
+	 * disturbance, abort IDD or TS function enable in this case.
+	 */
+	if (((func & STMFX_FUNC_IDD) || (func & STMFX_FUNC_TS)) &&
+	    (sys_ctrl & STMFX_REG_SYS_CTRL_ALTGPIO_EN)) {
+		dev_err(stmfx->dev, "ALTGPIO function already enabled\n");
+		return -EBUSY;
+	}
+
+	/* If TS is enabled, aGPIO[3:0] cannot be used */
+	if ((func & STMFX_FUNC_ALTGPIO_LOW) &&
+	    (sys_ctrl & STMFX_REG_SYS_CTRL_TS_EN)) {
+		dev_err(stmfx->dev, "TS in use, aGPIO[3:0] unavailable\n");
+		return -EBUSY;
+	}
+
+	/* If IDD is enabled, aGPIO[7:4] cannot be used */
+	if ((func & STMFX_FUNC_ALTGPIO_HIGH) &&
+	    (sys_ctrl & STMFX_REG_SYS_CTRL_IDD_EN)) {
+		dev_err(stmfx->dev, "IDD in use, aGPIO[7:4] unavailable\n");
+		return -EBUSY;
+	}
+
+	mask = stmfx_func_to_mask(func);
+
+	return regmap_update_bits(stmfx->map, STMFX_REG_SYS_CTRL, mask, mask);
+}
+EXPORT_SYMBOL_GPL(stmfx_function_enable);
+
+int stmfx_function_disable(struct stmfx *stmfx, u32 func)
+{
+	u8 mask = stmfx_func_to_mask(func);
+
+	return regmap_update_bits(stmfx->map, STMFX_REG_SYS_CTRL, mask, 0);
+}
+EXPORT_SYMBOL_GPL(stmfx_function_disable);
+
+static void stmfx_irq_bus_lock(struct irq_data *data)
+{
+	struct stmfx *stmfx = irq_data_get_irq_chip_data(data);
+
+	mutex_lock(&stmfx->lock);
+}
+
+static void stmfx_irq_bus_sync_unlock(struct irq_data *data)
+{
+	struct stmfx *stmfx = irq_data_get_irq_chip_data(data);
+
+	regmap_write(stmfx->map, STMFX_REG_IRQ_SRC_EN, stmfx->irq_src);
+
+	mutex_unlock(&stmfx->lock);
+}
+
+static void stmfx_irq_mask(struct irq_data *data)
+{
+	struct stmfx *stmfx = irq_data_get_irq_chip_data(data);
+
+	stmfx->irq_src &= ~BIT(data->hwirq % 8);
+}
+
+static void stmfx_irq_unmask(struct irq_data *data)
+{
+	struct stmfx *stmfx = irq_data_get_irq_chip_data(data);
+
+	stmfx->irq_src |= BIT(data->hwirq % 8);
+}
+
+static struct irq_chip stmfx_irq_chip = {
+	.name			= "stmfx-core",
+	.irq_bus_lock		= stmfx_irq_bus_lock,
+	.irq_bus_sync_unlock	= stmfx_irq_bus_sync_unlock,
+	.irq_mask		= stmfx_irq_mask,
+	.irq_unmask		= stmfx_irq_unmask,
+};
+
+static irqreturn_t stmfx_irq_handler(int irq, void *data)
+{
+	struct stmfx *stmfx = data;
+	unsigned long bits;
+	u32 pending, ack;
+	int n, ret;
+
+	ret = regmap_read(stmfx->map, STMFX_REG_IRQ_PENDING, &pending);
+	if (ret)
+		return IRQ_NONE;
+
+	/*
+	 * There is no ACK for GPIO, MFX_REG_IRQ_PENDING_GPIO is a logical OR
+	 * of MFX_REG_IRQ_GPI _PENDING1/_PENDING2/_PENDING3
+	 */
+	ack = pending & ~BIT(STMFX_REG_IRQ_SRC_EN_GPIO);
+	if (ack) {
+		ret = regmap_write(stmfx->map, STMFX_REG_IRQ_ACK, ack);
+		if (ret)
+			return IRQ_NONE;
+	}
+
+	bits = pending;
+	for_each_set_bit(n, &bits, STMFX_REG_IRQ_SRC_MAX)
+		handle_nested_irq(irq_find_mapping(stmfx->irq_domain, n));
+
+	return IRQ_HANDLED;
+}
+
+static int stmfx_irq_map(struct irq_domain *d, unsigned int virq,
+			 irq_hw_number_t hwirq)
+{
+	irq_set_chip_data(virq, d->host_data);
+	irq_set_chip_and_handler(virq, &stmfx_irq_chip, handle_simple_irq);
+	irq_set_nested_thread(virq, 1);
+	irq_set_noprobe(virq);
+
+	return 0;
+}
+
+static void stmfx_irq_unmap(struct irq_domain *d, unsigned int virq)
+{
+	irq_set_chip_and_handler(virq, NULL, NULL);
+	irq_set_chip_data(virq, NULL);
+}
+
+static const struct irq_domain_ops stmfx_irq_ops = {
+	.map	= stmfx_irq_map,
+	.unmap	= stmfx_irq_unmap,
+};
+
+static void stmfx_irq_exit(struct i2c_client *client)
+{
+	struct stmfx *stmfx = i2c_get_clientdata(client);
+	int hwirq;
+
+	for (hwirq = 0; hwirq < STMFX_REG_IRQ_SRC_MAX; hwirq++)
+		irq_dispose_mapping(irq_find_mapping(stmfx->irq_domain, hwirq));
+
+	irq_domain_remove(stmfx->irq_domain);
+}
+
+static int stmfx_irq_init(struct i2c_client *client)
+{
+	struct stmfx *stmfx = i2c_get_clientdata(client);
+	u32 irqoutpin = 0, irqtrigger;
+	int ret;
+
+	stmfx->irq_domain = irq_domain_create_simple(dev_fwnode(stmfx->dev), STMFX_REG_IRQ_SRC_MAX,
+						     0, &stmfx_irq_ops, stmfx);
+	if (!stmfx->irq_domain) {
+		dev_err(stmfx->dev, "Failed to create IRQ domain\n");
+		return -EINVAL;
+	}
+
+	if (!of_property_read_bool(stmfx->dev->of_node, "drive-open-drain"))
+		irqoutpin |= STMFX_REG_IRQ_OUT_PIN_TYPE;
+
+	irqtrigger = irq_get_trigger_type(client->irq);
+	if ((irqtrigger & IRQ_TYPE_EDGE_RISING) ||
+	    (irqtrigger & IRQ_TYPE_LEVEL_HIGH))
+		irqoutpin |= STMFX_REG_IRQ_OUT_PIN_POL;
+
+	ret = regmap_write(stmfx->map, STMFX_REG_IRQ_OUT_PIN, irqoutpin);
+	if (ret)
+		goto irq_exit;
+
+	ret = devm_request_threaded_irq(stmfx->dev, client->irq,
+					NULL, stmfx_irq_handler,
+					irqtrigger | IRQF_ONESHOT,
+					"stmfx", stmfx);
+	if (ret)
+		goto irq_exit;
+
+	stmfx->irq = client->irq;
+
+	return 0;
+
+irq_exit:
+	stmfx_irq_exit(client);
+
+	return ret;
+}
+
+static int stmfx_chip_reset(struct stmfx *stmfx)
+{
+	int ret;
+
+	ret = regmap_write(stmfx->map, STMFX_REG_SYS_CTRL,
+			   STMFX_REG_SYS_CTRL_SWRST);
+	if (ret)
+		return ret;
+
+	msleep(STMFX_BOOT_TIME_MS);
+
+	return ret;
+}
+
+static int stmfx_chip_init(struct i2c_client *client)
+{
+	struct stmfx *stmfx = i2c_get_clientdata(client);
+	u32 id;
+	u8 version[2];
+	int ret;
+
+	stmfx->vdd = devm_regulator_get_optional(&client->dev, "vdd");
+	ret = PTR_ERR_OR_ZERO(stmfx->vdd);
+	if (ret) {
+		stmfx->vdd = NULL;
+		if (ret != -ENODEV)
+			return dev_err_probe(&client->dev, ret, "Failed to get VDD regulator\n");
+	}
+
+	if (stmfx->vdd) {
+		ret = regulator_enable(stmfx->vdd);
+		if (ret) {
+			dev_err(&client->dev, "VDD enable failed: %d\n", ret);
+			return ret;
+		}
+	}
+
+	ret = regmap_read(stmfx->map, STMFX_REG_CHIP_ID, &id);
+	if (ret) {
+		dev_err(&client->dev, "Error reading chip ID: %d\n", ret);
+		goto err;
+	}
+
+	/*
+	 * Check that ID is the complement of the I2C address:
+	 * STMFX I2C address follows the 7-bit format (MSB), that's why
+	 * client->addr is shifted.
+	 *
+	 * STMFX_I2C_ADDR|       STMFX         |        Linux
+	 *   input pin   | I2C device address  | I2C device address
+	 *---------------------------------------------------------
+	 *       0       | b: 1000 010x h:0x84 |       0x42
+	 *       1       | b: 1000 011x h:0x86 |       0x43
+	 */
+	if (FIELD_GET(STMFX_REG_CHIP_ID_MASK, ~id) != (client->addr << 1)) {
+		dev_err(&client->dev, "Unknown chip ID: %#x\n", id);
+		ret = -EINVAL;
+		goto err;
+	}
+
+	ret = regmap_bulk_read(stmfx->map, STMFX_REG_FW_VERSION_MSB,
+			       version, ARRAY_SIZE(version));
+	if (ret) {
+		dev_err(&client->dev, "Error reading FW version: %d\n", ret);
+		goto err;
+	}
+
+	dev_info(&client->dev, "STMFX id: %#x, fw version: %x.%02x\n",
+		 id, version[0], version[1]);
+
+	ret = stmfx_chip_reset(stmfx);
+	if (ret) {
+		dev_err(&client->dev, "Failed to reset chip: %d\n", ret);
+		goto err;
+	}
+
+	return 0;
+
+err:
+	if (stmfx->vdd)
+		regulator_disable(stmfx->vdd);
+
+	return ret;
+}
+
+static void stmfx_chip_exit(struct i2c_client *client)
+{
+	struct stmfx *stmfx = i2c_get_clientdata(client);
+
+	regmap_write(stmfx->map, STMFX_REG_IRQ_SRC_EN, 0);
+	regmap_write(stmfx->map, STMFX_REG_SYS_CTRL, 0);
+
+	if (stmfx->vdd) {
+		int ret;
+
+		ret = regulator_disable(stmfx->vdd);
+		if (ret)
+			dev_err(&client->dev,
+				"Failed to disable vdd regulator: %pe\n",
+				ERR_PTR(ret));
+	}
+}
+
+static int stmfx_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct stmfx *stmfx;
+	int ret;
+
+	stmfx = devm_kzalloc(dev, sizeof(*stmfx), GFP_KERNEL);
+	if (!stmfx)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, stmfx);
+
+	stmfx->dev = dev;
+
+	stmfx->map = devm_regmap_init_i2c(client, &stmfx_regmap_config);
+	if (IS_ERR(stmfx->map)) {
+		ret = PTR_ERR(stmfx->map);
+		dev_err(dev, "Failed to allocate register map: %d\n", ret);
+		return ret;
+	}
+
+	mutex_init(&stmfx->lock);
+
+	ret = stmfx_chip_init(client);
+	if (ret) {
+		if (ret == -ETIMEDOUT)
+			return -EPROBE_DEFER;
+		return ret;
+	}
+
+	if (client->irq < 0) {
+		dev_err(dev, "Failed to get IRQ: %d\n", client->irq);
+		ret = client->irq;
+		goto err_chip_exit;
+	}
+
+	ret = stmfx_irq_init(client);
+	if (ret)
+		goto err_chip_exit;
+
+	ret = devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE,
+				   stmfx_cells, ARRAY_SIZE(stmfx_cells), NULL,
+				   0, stmfx->irq_domain);
+	if (ret)
+		goto err_irq_exit;
+
+	return 0;
+
+err_irq_exit:
+	stmfx_irq_exit(client);
+err_chip_exit:
+	stmfx_chip_exit(client);
+
+	return ret;
+}
+
+static void stmfx_remove(struct i2c_client *client)
+{
+	stmfx_irq_exit(client);
+
+	stmfx_chip_exit(client);
+}
+
+static int stmfx_suspend(struct device *dev)
+{
+	struct stmfx *stmfx = dev_get_drvdata(dev);
+	int ret;
+
+	ret = regmap_raw_read(stmfx->map, STMFX_REG_SYS_CTRL,
+			      &stmfx->bkp_sysctrl, sizeof(stmfx->bkp_sysctrl));
+	if (ret)
+		return ret;
+
+	ret = regmap_raw_read(stmfx->map, STMFX_REG_IRQ_OUT_PIN,
+			      &stmfx->bkp_irqoutpin,
+			      sizeof(stmfx->bkp_irqoutpin));
+	if (ret)
+		return ret;
+
+	disable_irq(stmfx->irq);
+
+	if (stmfx->vdd)
+		return regulator_disable(stmfx->vdd);
+
+	return 0;
+}
+
+static int stmfx_resume(struct device *dev)
+{
+	struct stmfx *stmfx = dev_get_drvdata(dev);
+	int ret;
+
+	if (stmfx->vdd) {
+		ret = regulator_enable(stmfx->vdd);
+		if (ret) {
+			dev_err(stmfx->dev,
+				"VDD enable failed: %d\n", ret);
+			return ret;
+		}
+	}
+
+	/* Reset STMFX - supply has been stopped during suspend */
+	ret = stmfx_chip_reset(stmfx);
+	if (ret) {
+		dev_err(stmfx->dev, "Failed to reset chip: %d\n", ret);
+		return ret;
+	}
+
+	ret = regmap_raw_write(stmfx->map, STMFX_REG_SYS_CTRL,
+			       &stmfx->bkp_sysctrl, sizeof(stmfx->bkp_sysctrl));
+	if (ret)
+		return ret;
+
+	ret = regmap_raw_write(stmfx->map, STMFX_REG_IRQ_OUT_PIN,
+			       &stmfx->bkp_irqoutpin,
+			       sizeof(stmfx->bkp_irqoutpin));
+	if (ret)
+		return ret;
+
+	ret = regmap_raw_write(stmfx->map, STMFX_REG_IRQ_SRC_EN,
+			       &stmfx->irq_src, sizeof(stmfx->irq_src));
+	if (ret)
+		return ret;
+
+	enable_irq(stmfx->irq);
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(stmfx_dev_pm_ops, stmfx_suspend, stmfx_resume);
+
+static const struct of_device_id stmfx_of_match[] = {
+	{ .compatible = "st,stmfx-0300", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, stmfx_of_match);
+
+static struct i2c_driver stmfx_driver = {
+	.driver = {
+		.name = "stmfx-core",
+		.of_match_table = stmfx_of_match,
+		.pm = pm_sleep_ptr(&stmfx_dev_pm_ops),
+	},
+	.probe = stmfx_probe,
+	.remove = stmfx_remove,
+};
+module_i2c_driver(stmfx_driver);
+
+MODULE_DESCRIPTION("STMFX core driver");
+MODULE_AUTHOR("Amelie Delaunay <amelie.delaunay@st.com>");
+MODULE_LICENSE("GPL v2");