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, 330 insertions, 0 deletions

diff --git a/drivers/regulator/mpq7920.c b/drivers/regulator/mpq7920.c
new file mode 100644
index 000000000..0cbc17deb
--- /dev/null
+++ b/drivers/regulator/mpq7920.c
@@ -0,0 +1,330 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// mpq7920.c  - regulator driver for mps mpq7920
+//
+// Copyright 2019 Monolithic Power Systems, Inc
+//
+// Author: Saravanan Sekar <sravanhome@gmail.com>
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/of_regulator.h>
+#include <linux/i2c.h>
+#include <linux/regmap.h>
+#include "mpq7920.h"
+
+#define MPQ7920_BUCK_VOLT_RANGE \
+	((MPQ7920_VOLT_MAX - MPQ7920_BUCK_VOLT_MIN)/MPQ7920_VOLT_STEP + 1)
+#define MPQ7920_LDO_VOLT_RANGE \
+	((MPQ7920_VOLT_MAX - MPQ7920_LDO_VOLT_MIN)/MPQ7920_VOLT_STEP + 1)
+
+#define MPQ7920BUCK(_name, _id, _ilim)					\
+	[MPQ7920_BUCK ## _id] = {					\
+		.id = MPQ7920_BUCK ## _id,				\
+		.name = _name,						\
+		.of_match = _name,					\
+		.regulators_node = "regulators",			\
+		.of_parse_cb = mpq7920_parse_cb,			\
+		.ops = &mpq7920_buck_ops,				\
+		.min_uV = MPQ7920_BUCK_VOLT_MIN,			\
+		.uV_step = MPQ7920_VOLT_STEP,				\
+		.n_voltages = MPQ7920_BUCK_VOLT_RANGE,			\
+		.curr_table = _ilim,					\
+		.n_current_limits = ARRAY_SIZE(_ilim),			\
+		.csel_reg = MPQ7920_BUCK ##_id## _REG_C,		\
+		.csel_mask = MPQ7920_MASK_BUCK_ILIM,			\
+		.enable_reg = MPQ7920_REG_REGULATOR_EN,			\
+		.enable_mask = BIT(MPQ7920_REGULATOR_EN_OFFSET -	\
+					 MPQ7920_BUCK ## _id),		\
+		.vsel_reg = MPQ7920_BUCK ##_id## _REG_A,		\
+		.vsel_mask = MPQ7920_MASK_VREF,				\
+		.active_discharge_on	= MPQ7920_DISCHARGE_ON,		\
+		.active_discharge_reg	= MPQ7920_BUCK ##_id## _REG_B,	\
+		.active_discharge_mask	= MPQ7920_MASK_DISCHARGE,	\
+		.soft_start_reg		= MPQ7920_BUCK ##_id## _REG_C,	\
+		.soft_start_mask	= MPQ7920_MASK_SOFTSTART,	\
+		.owner			= THIS_MODULE,			\
+	}
+
+#define MPQ7920LDO(_name, _id, _ops, _ilim, _ilim_sz, _creg, _cmask)	\
+	[MPQ7920_LDO ## _id] = {					\
+		.id = MPQ7920_LDO ## _id,				\
+		.name = _name,						\
+		.of_match = _name,					\
+		.regulators_node = "regulators",			\
+		.ops = _ops,						\
+		.min_uV = MPQ7920_LDO_VOLT_MIN,				\
+		.uV_step = MPQ7920_VOLT_STEP,				\
+		.n_voltages = MPQ7920_LDO_VOLT_RANGE,			\
+		.vsel_reg = MPQ7920_LDO ##_id## _REG_A,			\
+		.vsel_mask = MPQ7920_MASK_VREF,				\
+		.curr_table = _ilim,					\
+		.n_current_limits = _ilim_sz,				\
+		.csel_reg = _creg,					\
+		.csel_mask = _cmask,					\
+		.enable_reg = (_id == 1) ? 0 : MPQ7920_REG_REGULATOR_EN,\
+		.enable_mask = BIT(MPQ7920_REGULATOR_EN_OFFSET -	\
+					MPQ7920_LDO ##_id + 1),		\
+		.active_discharge_on	= MPQ7920_DISCHARGE_ON,		\
+		.active_discharge_mask	= MPQ7920_MASK_DISCHARGE,	\
+		.active_discharge_reg	= MPQ7920_LDO ##_id## _REG_B,	\
+		.type			= REGULATOR_VOLTAGE,		\
+		.owner			= THIS_MODULE,			\
+	}
+
+enum mpq7920_regulators {
+	MPQ7920_BUCK1,
+	MPQ7920_BUCK2,
+	MPQ7920_BUCK3,
+	MPQ7920_BUCK4,
+	MPQ7920_LDO1, /* LDORTC */
+	MPQ7920_LDO2,
+	MPQ7920_LDO3,
+	MPQ7920_LDO4,
+	MPQ7920_LDO5,
+	MPQ7920_MAX_REGULATORS,
+};
+
+struct mpq7920_regulator_info {
+	struct regmap *regmap;
+	struct regulator_desc *rdesc;
+};
+
+static const struct regmap_config mpq7920_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = 0x25,
+};
+
+/* Current limits array (in uA)
+ * ILIM1 & ILIM3
+ */
+static const unsigned int mpq7920_I_limits1[] = {
+	4600000, 6600000, 7600000, 9300000
+};
+
+/* ILIM2 & ILIM4 */
+static const unsigned int mpq7920_I_limits2[] = {
+	2700000, 3900000, 5100000, 6100000
+};
+
+/* LDO4 & LDO5 */
+static const unsigned int mpq7920_I_limits3[] = {
+	300000, 700000
+};
+
+static int mpq7920_set_ramp_delay(struct regulator_dev *rdev, int ramp_delay);
+static int mpq7920_parse_cb(struct device_node *np,
+				const struct regulator_desc *rdesc,
+				struct regulator_config *config);
+
+/* RTCLDO not controllable, always ON */
+static const struct regulator_ops mpq7920_ldortc_ops = {
+	.list_voltage		= regulator_list_voltage_linear,
+	.map_voltage		= regulator_map_voltage_linear,
+	.get_voltage_sel	= regulator_get_voltage_sel_regmap,
+	.set_voltage_sel	= regulator_set_voltage_sel_regmap,
+};
+
+static const struct regulator_ops mpq7920_ldo_wo_current_ops = {
+	.enable			= regulator_enable_regmap,
+	.disable		= regulator_disable_regmap,
+	.is_enabled		= regulator_is_enabled_regmap,
+	.list_voltage		= regulator_list_voltage_linear,
+	.map_voltage		= regulator_map_voltage_linear,
+	.get_voltage_sel	= regulator_get_voltage_sel_regmap,
+	.set_voltage_sel	= regulator_set_voltage_sel_regmap,
+	.set_active_discharge	= regulator_set_active_discharge_regmap,
+};
+
+static const struct regulator_ops mpq7920_ldo_ops = {
+	.enable			= regulator_enable_regmap,
+	.disable		= regulator_disable_regmap,
+	.is_enabled		= regulator_is_enabled_regmap,
+	.list_voltage		= regulator_list_voltage_linear,
+	.map_voltage		= regulator_map_voltage_linear,
+	.get_voltage_sel	= regulator_get_voltage_sel_regmap,
+	.set_voltage_sel	= regulator_set_voltage_sel_regmap,
+	.set_active_discharge	= regulator_set_active_discharge_regmap,
+	.get_current_limit	= regulator_get_current_limit_regmap,
+	.set_current_limit	= regulator_set_current_limit_regmap,
+};
+
+static const struct regulator_ops mpq7920_buck_ops = {
+	.enable			= regulator_enable_regmap,
+	.disable		= regulator_disable_regmap,
+	.is_enabled		= regulator_is_enabled_regmap,
+	.list_voltage		= regulator_list_voltage_linear,
+	.map_voltage		= regulator_map_voltage_linear,
+	.get_voltage_sel	= regulator_get_voltage_sel_regmap,
+	.set_voltage_sel	= regulator_set_voltage_sel_regmap,
+	.set_active_discharge	= regulator_set_active_discharge_regmap,
+	.set_soft_start		= regulator_set_soft_start_regmap,
+	.set_ramp_delay		= mpq7920_set_ramp_delay,
+};
+
+static struct regulator_desc mpq7920_regulators_desc[MPQ7920_MAX_REGULATORS] = {
+	MPQ7920BUCK("buck1", 1, mpq7920_I_limits1),
+	MPQ7920BUCK("buck2", 2, mpq7920_I_limits2),
+	MPQ7920BUCK("buck3", 3, mpq7920_I_limits1),
+	MPQ7920BUCK("buck4", 4, mpq7920_I_limits2),
+	MPQ7920LDO("ldortc", 1, &mpq7920_ldortc_ops, NULL, 0, 0, 0),
+	MPQ7920LDO("ldo2", 2, &mpq7920_ldo_wo_current_ops, NULL, 0, 0, 0),
+	MPQ7920LDO("ldo3", 3, &mpq7920_ldo_wo_current_ops, NULL, 0, 0, 0),
+	MPQ7920LDO("ldo4", 4, &mpq7920_ldo_ops, mpq7920_I_limits3,
+			ARRAY_SIZE(mpq7920_I_limits3), MPQ7920_LDO4_REG_B,
+			MPQ7920_MASK_LDO_ILIM),
+	MPQ7920LDO("ldo5", 5, &mpq7920_ldo_ops, mpq7920_I_limits3,
+			ARRAY_SIZE(mpq7920_I_limits3), MPQ7920_LDO5_REG_B,
+			MPQ7920_MASK_LDO_ILIM),
+};
+
+/*
+ * DVS ramp rate BUCK1 to BUCK4
+ * 00-01: Reserved
+ * 10: 8mV/us
+ * 11: 4mV/us
+ */
+static int mpq7920_set_ramp_delay(struct regulator_dev *rdev, int ramp_delay)
+{
+	unsigned int ramp_val;
+
+	if (ramp_delay > 8000 || ramp_delay < 0)
+		return -EINVAL;
+
+	if (ramp_delay <= 4000)
+		ramp_val = 3;
+	else
+		ramp_val = 2;
+
+	return regmap_update_bits(rdev->regmap, MPQ7920_REG_CTL0,
+				  MPQ7920_MASK_DVS_SLEWRATE, ramp_val << 6);
+}
+
+static int mpq7920_parse_cb(struct device_node *np,
+				const struct regulator_desc *desc,
+				struct regulator_config *config)
+{
+	uint8_t val;
+	int ret;
+	struct mpq7920_regulator_info *info = config->driver_data;
+	struct regulator_desc *rdesc = &info->rdesc[desc->id];
+
+	if (of_property_read_bool(np, "mps,buck-ovp-disable")) {
+		regmap_update_bits(config->regmap,
+				MPQ7920_BUCK1_REG_B + (rdesc->id * 4),
+				MPQ7920_MASK_OVP, MPQ7920_OVP_DISABLE);
+	}
+
+	ret = of_property_read_u8(np, "mps,buck-phase-delay", &val);
+	if (!ret) {
+		regmap_update_bits(config->regmap,
+				MPQ7920_BUCK1_REG_C + (rdesc->id * 4),
+				MPQ7920_MASK_BUCK_PHASE_DEALY,
+				(val & 3) << 4);
+	}
+
+	ret = of_property_read_u8(np, "mps,buck-softstart", &val);
+	if (!ret)
+		rdesc->soft_start_val_on = (val & 3) << 2;
+
+	return 0;
+}
+
+static void mpq7920_parse_dt(struct device *dev,
+		 struct mpq7920_regulator_info *info)
+{
+	int ret;
+	struct device_node *np = dev->of_node;
+	uint8_t freq;
+
+	np = of_get_child_by_name(np, "regulators");
+	if (!np) {
+		dev_err(dev, "missing 'regulators' subnode in DT\n");
+		return;
+	}
+
+	ret = of_property_read_u8(np, "mps,switch-freq", &freq);
+	if (!ret) {
+		regmap_update_bits(info->regmap, MPQ7920_REG_CTL0,
+					MPQ7920_MASK_SWITCH_FREQ,
+					(freq & 3) << 4);
+	}
+
+	of_node_put(np);
+}
+
+static int mpq7920_i2c_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct mpq7920_regulator_info *info;
+	struct regulator_config config = { NULL, };
+	struct regulator_dev *rdev;
+	struct regmap *regmap;
+	int i;
+
+	info = devm_kzalloc(dev, sizeof(struct mpq7920_regulator_info),
+				GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	info->rdesc = mpq7920_regulators_desc;
+	regmap = devm_regmap_init_i2c(client, &mpq7920_regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err(dev, "Failed to allocate regmap!\n");
+		return PTR_ERR(regmap);
+	}
+
+	i2c_set_clientdata(client, info);
+	info->regmap = regmap;
+	if (client->dev.of_node)
+		mpq7920_parse_dt(&client->dev, info);
+
+	config.dev = dev;
+	config.regmap = regmap;
+	config.driver_data = info;
+
+	for (i = 0; i < MPQ7920_MAX_REGULATORS; i++) {
+		rdev = devm_regulator_register(dev,
+					       &mpq7920_regulators_desc[i],
+					       &config);
+		if (IS_ERR(rdev)) {
+			dev_err(dev, "Failed to register regulator!\n");
+			return PTR_ERR(rdev);
+		}
+	}
+
+	return 0;
+}
+
+static const struct of_device_id mpq7920_of_match[] = {
+	{ .compatible = "mps,mpq7920"},
+	{},
+};
+MODULE_DEVICE_TABLE(of, mpq7920_of_match);
+
+static const struct i2c_device_id mpq7920_id[] = {
+	{ .name = "mpq7920" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, mpq7920_id);
+
+static struct i2c_driver mpq7920_regulator_driver = {
+	.driver = {
+		.name = "mpq7920",
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+		.of_match_table = mpq7920_of_match,
+	},
+	.probe = mpq7920_i2c_probe,
+	.id_table = mpq7920_id,
+};
+module_i2c_driver(mpq7920_regulator_driver);
+
+MODULE_AUTHOR("Saravanan Sekar <sravanhome@gmail.com>");
+MODULE_DESCRIPTION("MPQ7920 PMIC regulator driver");
+MODULE_LICENSE("GPL");