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, 529 insertions, 0 deletions

diff --git a/drivers/regulator/max8660.c b/drivers/regulator/max8660.c
new file mode 100644
index 000000000..ede17099b
--- /dev/null
+++ b/drivers/regulator/max8660.c
@@ -0,0 +1,529 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * max8660.c  --  Voltage regulation for the Maxim 8660/8661
+ *
+ * based on max1586.c and wm8400-regulator.c
+ *
+ * Copyright (C) 2009 Wolfram Sang, Pengutronix e.K.
+ *
+ * Some info:
+ *
+ * Datasheet: http://datasheets.maxim-ic.com/en/ds/MAX8660-MAX8661.pdf
+ *
+ * This chip is a bit nasty because it is a write-only device. Thus, the driver
+ * uses shadow registers to keep track of its values. The main problem appears
+ * to be the initialization: When Linux boots up, we cannot know if the chip is
+ * in the default state or not, so we would have to pass such information in
+ * platform_data. As this adds a bit of complexity to the driver, this is left
+ * out for now until it is really needed.
+ *
+ * [A|S|M]DTV1 registers are currently not used, but [A|S|M]DTV2.
+ *
+ * If the driver is feature complete, it might be worth to check if one set of
+ * functions for V3-V7 is sufficient. For maximum flexibility during
+ * development, they are separated for now.
+ */
+
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/driver.h>
+#include <linux/slab.h>
+#include <linux/regulator/max8660.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/regulator/of_regulator.h>
+
+#define MAX8660_DCDC_MIN_UV	 725000
+#define MAX8660_DCDC_MAX_UV	1800000
+#define MAX8660_DCDC_STEP	  25000
+#define MAX8660_DCDC_MAX_SEL	0x2b
+
+#define MAX8660_LDO5_MIN_UV	1700000
+#define MAX8660_LDO5_MAX_UV	2000000
+#define MAX8660_LDO5_STEP	  25000
+#define MAX8660_LDO5_MAX_SEL	0x0c
+
+#define MAX8660_LDO67_MIN_UV	1800000
+#define MAX8660_LDO67_MAX_UV	3300000
+#define MAX8660_LDO67_STEP	 100000
+#define MAX8660_LDO67_MAX_SEL	0x0f
+
+enum {
+	MAX8660_OVER1,
+	MAX8660_OVER2,
+	MAX8660_VCC1,
+	MAX8660_ADTV1,
+	MAX8660_ADTV2,
+	MAX8660_SDTV1,
+	MAX8660_SDTV2,
+	MAX8660_MDTV1,
+	MAX8660_MDTV2,
+	MAX8660_L12VCR,
+	MAX8660_FPWM,
+	MAX8660_N_REGS,	/* not a real register */
+};
+
+struct max8660 {
+	struct i2c_client *client;
+	u8 shadow_regs[MAX8660_N_REGS];		/* as chip is write only */
+};
+
+static int max8660_write(struct max8660 *max8660, u8 reg, u8 mask, u8 val)
+{
+	static const u8 max8660_addresses[MAX8660_N_REGS] = {
+	 0x10, 0x12, 0x20, 0x23, 0x24, 0x29, 0x2a, 0x32, 0x33, 0x39, 0x80
+	};
+
+	int ret;
+	u8 reg_val = (max8660->shadow_regs[reg] & mask) | val;
+
+	dev_vdbg(&max8660->client->dev, "Writing reg %02x with %02x\n",
+			max8660_addresses[reg], reg_val);
+
+	ret = i2c_smbus_write_byte_data(max8660->client,
+			max8660_addresses[reg], reg_val);
+	if (ret == 0)
+		max8660->shadow_regs[reg] = reg_val;
+
+	return ret;
+}
+
+
+/*
+ * DCDC functions
+ */
+
+static int max8660_dcdc_is_enabled(struct regulator_dev *rdev)
+{
+	struct max8660 *max8660 = rdev_get_drvdata(rdev);
+	u8 val = max8660->shadow_regs[MAX8660_OVER1];
+	u8 mask = (rdev_get_id(rdev) == MAX8660_V3) ? 1 : 4;
+
+	return !!(val & mask);
+}
+
+static int max8660_dcdc_enable(struct regulator_dev *rdev)
+{
+	struct max8660 *max8660 = rdev_get_drvdata(rdev);
+	u8 bit = (rdev_get_id(rdev) == MAX8660_V3) ? 1 : 4;
+
+	return max8660_write(max8660, MAX8660_OVER1, 0xff, bit);
+}
+
+static int max8660_dcdc_disable(struct regulator_dev *rdev)
+{
+	struct max8660 *max8660 = rdev_get_drvdata(rdev);
+	u8 mask = (rdev_get_id(rdev) == MAX8660_V3) ? ~1 : ~4;
+
+	return max8660_write(max8660, MAX8660_OVER1, mask, 0);
+}
+
+static int max8660_dcdc_get_voltage_sel(struct regulator_dev *rdev)
+{
+	struct max8660 *max8660 = rdev_get_drvdata(rdev);
+	u8 reg = (rdev_get_id(rdev) == MAX8660_V3) ? MAX8660_ADTV2 : MAX8660_SDTV2;
+	u8 selector = max8660->shadow_regs[reg];
+
+	return selector;
+}
+
+static int max8660_dcdc_set_voltage_sel(struct regulator_dev *rdev,
+					unsigned int selector)
+{
+	struct max8660 *max8660 = rdev_get_drvdata(rdev);
+	u8 reg, bits;
+	int ret;
+
+	reg = (rdev_get_id(rdev) == MAX8660_V3) ? MAX8660_ADTV2 : MAX8660_SDTV2;
+	ret = max8660_write(max8660, reg, 0, selector);
+	if (ret)
+		return ret;
+
+	/* Select target voltage register and activate regulation */
+	bits = (rdev_get_id(rdev) == MAX8660_V3) ? 0x03 : 0x30;
+	return max8660_write(max8660, MAX8660_VCC1, 0xff, bits);
+}
+
+static struct regulator_ops max8660_dcdc_ops = {
+	.is_enabled = max8660_dcdc_is_enabled,
+	.list_voltage = regulator_list_voltage_linear,
+	.map_voltage = regulator_map_voltage_linear,
+	.set_voltage_sel = max8660_dcdc_set_voltage_sel,
+	.get_voltage_sel = max8660_dcdc_get_voltage_sel,
+};
+
+
+/*
+ * LDO5 functions
+ */
+
+static int max8660_ldo5_get_voltage_sel(struct regulator_dev *rdev)
+{
+	struct max8660 *max8660 = rdev_get_drvdata(rdev);
+
+	u8 selector = max8660->shadow_regs[MAX8660_MDTV2];
+	return selector;
+}
+
+static int max8660_ldo5_set_voltage_sel(struct regulator_dev *rdev,
+					unsigned int selector)
+{
+	struct max8660 *max8660 = rdev_get_drvdata(rdev);
+	int ret;
+
+	ret = max8660_write(max8660, MAX8660_MDTV2, 0, selector);
+	if (ret)
+		return ret;
+
+	/* Select target voltage register and activate regulation */
+	return max8660_write(max8660, MAX8660_VCC1, 0xff, 0xc0);
+}
+
+static const struct regulator_ops max8660_ldo5_ops = {
+	.list_voltage = regulator_list_voltage_linear,
+	.map_voltage = regulator_map_voltage_linear,
+	.set_voltage_sel = max8660_ldo5_set_voltage_sel,
+	.get_voltage_sel = max8660_ldo5_get_voltage_sel,
+};
+
+
+/*
+ * LDO67 functions
+ */
+
+static int max8660_ldo67_is_enabled(struct regulator_dev *rdev)
+{
+	struct max8660 *max8660 = rdev_get_drvdata(rdev);
+	u8 val = max8660->shadow_regs[MAX8660_OVER2];
+	u8 mask = (rdev_get_id(rdev) == MAX8660_V6) ? 2 : 4;
+
+	return !!(val & mask);
+}
+
+static int max8660_ldo67_enable(struct regulator_dev *rdev)
+{
+	struct max8660 *max8660 = rdev_get_drvdata(rdev);
+	u8 bit = (rdev_get_id(rdev) == MAX8660_V6) ? 2 : 4;
+
+	return max8660_write(max8660, MAX8660_OVER2, 0xff, bit);
+}
+
+static int max8660_ldo67_disable(struct regulator_dev *rdev)
+{
+	struct max8660 *max8660 = rdev_get_drvdata(rdev);
+	u8 mask = (rdev_get_id(rdev) == MAX8660_V6) ? ~2 : ~4;
+
+	return max8660_write(max8660, MAX8660_OVER2, mask, 0);
+}
+
+static int max8660_ldo67_get_voltage_sel(struct regulator_dev *rdev)
+{
+	struct max8660 *max8660 = rdev_get_drvdata(rdev);
+	u8 shift = (rdev_get_id(rdev) == MAX8660_V6) ? 0 : 4;
+	u8 selector = (max8660->shadow_regs[MAX8660_L12VCR] >> shift) & 0xf;
+
+	return selector;
+}
+
+static int max8660_ldo67_set_voltage_sel(struct regulator_dev *rdev,
+					 unsigned int selector)
+{
+	struct max8660 *max8660 = rdev_get_drvdata(rdev);
+
+	if (rdev_get_id(rdev) == MAX8660_V6)
+		return max8660_write(max8660, MAX8660_L12VCR, 0xf0, selector);
+	else
+		return max8660_write(max8660, MAX8660_L12VCR, 0x0f,
+				     selector << 4);
+}
+
+static const struct regulator_ops max8660_ldo67_ops = {
+	.is_enabled = max8660_ldo67_is_enabled,
+	.enable = max8660_ldo67_enable,
+	.disable = max8660_ldo67_disable,
+	.list_voltage = regulator_list_voltage_linear,
+	.map_voltage = regulator_map_voltage_linear,
+	.get_voltage_sel = max8660_ldo67_get_voltage_sel,
+	.set_voltage_sel = max8660_ldo67_set_voltage_sel,
+};
+
+static const struct regulator_desc max8660_reg[] = {
+	{
+		.name = "V3(DCDC)",
+		.id = MAX8660_V3,
+		.ops = &max8660_dcdc_ops,
+		.type = REGULATOR_VOLTAGE,
+		.n_voltages = MAX8660_DCDC_MAX_SEL + 1,
+		.owner = THIS_MODULE,
+		.min_uV = MAX8660_DCDC_MIN_UV,
+		.uV_step = MAX8660_DCDC_STEP,
+	},
+	{
+		.name = "V4(DCDC)",
+		.id = MAX8660_V4,
+		.ops = &max8660_dcdc_ops,
+		.type = REGULATOR_VOLTAGE,
+		.n_voltages = MAX8660_DCDC_MAX_SEL + 1,
+		.owner = THIS_MODULE,
+		.min_uV = MAX8660_DCDC_MIN_UV,
+		.uV_step = MAX8660_DCDC_STEP,
+	},
+	{
+		.name = "V5(LDO)",
+		.id = MAX8660_V5,
+		.ops = &max8660_ldo5_ops,
+		.type = REGULATOR_VOLTAGE,
+		.n_voltages = MAX8660_LDO5_MAX_SEL + 1,
+		.owner = THIS_MODULE,
+		.min_uV = MAX8660_LDO5_MIN_UV,
+		.uV_step = MAX8660_LDO5_STEP,
+	},
+	{
+		.name = "V6(LDO)",
+		.id = MAX8660_V6,
+		.ops = &max8660_ldo67_ops,
+		.type = REGULATOR_VOLTAGE,
+		.n_voltages = MAX8660_LDO67_MAX_SEL + 1,
+		.owner = THIS_MODULE,
+		.min_uV = MAX8660_LDO67_MIN_UV,
+		.uV_step = MAX8660_LDO67_STEP,
+	},
+	{
+		.name = "V7(LDO)",
+		.id = MAX8660_V7,
+		.ops = &max8660_ldo67_ops,
+		.type = REGULATOR_VOLTAGE,
+		.n_voltages = MAX8660_LDO67_MAX_SEL + 1,
+		.owner = THIS_MODULE,
+		.min_uV = MAX8660_LDO67_MIN_UV,
+		.uV_step = MAX8660_LDO67_STEP,
+	},
+};
+
+enum {
+	MAX8660 = 0,
+	MAX8661 = 1,
+};
+
+#ifdef CONFIG_OF
+static const struct of_device_id max8660_dt_ids[] = {
+	{ .compatible = "maxim,max8660", .data = (void *) MAX8660 },
+	{ .compatible = "maxim,max8661", .data = (void *) MAX8661 },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max8660_dt_ids);
+
+static int max8660_pdata_from_dt(struct device *dev,
+				 struct device_node **of_node,
+				 struct max8660_platform_data *pdata)
+{
+	int matched, i;
+	struct device_node *np;
+	struct max8660_subdev_data *sub;
+	struct of_regulator_match rmatch[ARRAY_SIZE(max8660_reg)] = { };
+
+	np = of_get_child_by_name(dev->of_node, "regulators");
+	if (!np) {
+		dev_err(dev, "missing 'regulators' subnode in DT\n");
+		return -EINVAL;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(rmatch); i++)
+		rmatch[i].name = max8660_reg[i].name;
+
+	matched = of_regulator_match(dev, np, rmatch, ARRAY_SIZE(rmatch));
+	of_node_put(np);
+	if (matched <= 0)
+		return matched;
+
+	pdata->subdevs = devm_kcalloc(dev,
+				      matched,
+				      sizeof(struct max8660_subdev_data),
+				      GFP_KERNEL);
+	if (!pdata->subdevs)
+		return -ENOMEM;
+
+	pdata->num_subdevs = matched;
+	sub = pdata->subdevs;
+
+	for (i = 0; i < matched; i++) {
+		sub->id = i;
+		sub->name = rmatch[i].name;
+		sub->platform_data = rmatch[i].init_data;
+		of_node[i] = rmatch[i].of_node;
+		sub++;
+	}
+
+	return 0;
+}
+#else
+static inline int max8660_pdata_from_dt(struct device *dev,
+					struct device_node **of_node,
+					struct max8660_platform_data *pdata)
+{
+	return 0;
+}
+#endif
+
+static int max8660_probe(struct i2c_client *client)
+{
+	const struct i2c_device_id *i2c_id = i2c_client_get_device_id(client);
+	struct device *dev = &client->dev;
+	struct max8660_platform_data pdata_of, *pdata = dev_get_platdata(dev);
+	struct regulator_config config = { };
+	struct max8660 *max8660;
+	int boot_on, i, id, ret = -EINVAL;
+	struct device_node *of_node[MAX8660_V_END];
+	unsigned long type;
+
+	if (dev->of_node && !pdata) {
+		const struct of_device_id *id;
+
+		id = of_match_device(of_match_ptr(max8660_dt_ids), dev);
+		if (!id)
+			return -ENODEV;
+
+		ret = max8660_pdata_from_dt(dev, of_node, &pdata_of);
+		if (ret < 0)
+			return ret;
+
+		pdata = &pdata_of;
+		type = (unsigned long) id->data;
+	} else {
+		type = i2c_id->driver_data;
+		memset(of_node, 0, sizeof(of_node));
+	}
+
+	if (pdata->num_subdevs > MAX8660_V_END) {
+		dev_err(dev, "Too many regulators found!\n");
+		return -EINVAL;
+	}
+
+	max8660 = devm_kzalloc(dev, sizeof(struct max8660), GFP_KERNEL);
+	if (!max8660)
+		return -ENOMEM;
+
+	max8660->client = client;
+
+	if (pdata->en34_is_high) {
+		/* Simulate always on */
+		max8660->shadow_regs[MAX8660_OVER1] = 5;
+	} else {
+		/* Otherwise devices can be toggled via software */
+		max8660_dcdc_ops.enable = max8660_dcdc_enable;
+		max8660_dcdc_ops.disable = max8660_dcdc_disable;
+	}
+
+	/*
+	 * First, set up shadow registers to prevent glitches. As some
+	 * registers are shared between regulators, everything must be properly
+	 * set up for all regulators in advance.
+	 */
+	max8660->shadow_regs[MAX8660_ADTV1] =
+		max8660->shadow_regs[MAX8660_ADTV2] =
+		max8660->shadow_regs[MAX8660_SDTV1] =
+		max8660->shadow_regs[MAX8660_SDTV2] = 0x1b;
+	max8660->shadow_regs[MAX8660_MDTV1] =
+		max8660->shadow_regs[MAX8660_MDTV2] = 0x04;
+
+	for (i = 0; i < pdata->num_subdevs; i++) {
+
+		if (!pdata->subdevs[i].platform_data)
+			boot_on = false;
+		else
+			boot_on = pdata->subdevs[i].platform_data->constraints.boot_on;
+
+		switch (pdata->subdevs[i].id) {
+		case MAX8660_V3:
+			if (boot_on)
+				max8660->shadow_regs[MAX8660_OVER1] |= 1;
+			break;
+
+		case MAX8660_V4:
+			if (boot_on)
+				max8660->shadow_regs[MAX8660_OVER1] |= 4;
+			break;
+
+		case MAX8660_V5:
+			break;
+
+		case MAX8660_V6:
+			if (boot_on)
+				max8660->shadow_regs[MAX8660_OVER2] |= 2;
+			break;
+
+		case MAX8660_V7:
+			if (type == MAX8661) {
+				dev_err(dev, "Regulator not on this chip!\n");
+				return -EINVAL;
+			}
+
+			if (boot_on)
+				max8660->shadow_regs[MAX8660_OVER2] |= 4;
+			break;
+
+		default:
+			dev_err(dev, "invalid regulator %s\n",
+				 pdata->subdevs[i].name);
+			return ret;
+		}
+	}
+
+	/* Finally register devices */
+	for (i = 0; i < pdata->num_subdevs; i++) {
+		struct regulator_dev *rdev;
+
+		id = pdata->subdevs[i].id;
+
+		config.dev = dev;
+		config.init_data = pdata->subdevs[i].platform_data;
+		config.of_node = of_node[i];
+		config.driver_data = max8660;
+
+		rdev = devm_regulator_register(&client->dev,
+						  &max8660_reg[id], &config);
+		if (IS_ERR(rdev)) {
+			dev_err(&client->dev, "failed to register %s\n",
+				max8660_reg[id].name);
+			return PTR_ERR(rdev);
+		}
+	}
+
+	i2c_set_clientdata(client, max8660);
+	return 0;
+}
+
+static const struct i2c_device_id max8660_id[] = {
+	{ .name = "max8660", .driver_data = MAX8660 },
+	{ .name = "max8661", .driver_data = MAX8661 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, max8660_id);
+
+static struct i2c_driver max8660_driver = {
+	.probe = max8660_probe,
+	.driver		= {
+		.name	= "max8660",
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+	.id_table	= max8660_id,
+};
+
+static int __init max8660_init(void)
+{
+	return i2c_add_driver(&max8660_driver);
+}
+subsys_initcall(max8660_init);
+
+static void __exit max8660_exit(void)
+{
+	i2c_del_driver(&max8660_driver);
+}
+module_exit(max8660_exit);
+
+/* Module information */
+MODULE_DESCRIPTION("MAXIM 8660/8661 voltage regulator driver");
+MODULE_AUTHOR("Wolfram Sang");
+MODULE_LICENSE("GPL v2");