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, 250 insertions, 0 deletions

diff --git a/drivers/regulator/mp5416.c b/drivers/regulator/mp5416.c
new file mode 100644
index 000000000..2948635b1
--- /dev/null
+++ b/drivers/regulator/mp5416.c
@@ -0,0 +1,250 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// mp5416.c  - regulator driver for mps mp5416
+//
+// Copyright 2020 Monolithic Power Systems, Inc
+//
+// Author: Saravanan Sekar <sravanhome@gmail.com>
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/regulator/driver.h>
+
+#define MP5416_REG_CTL0			0x00
+#define MP5416_REG_CTL1			0x01
+#define MP5416_REG_CTL2			0x02
+#define MP5416_REG_ILIM			0x03
+#define MP5416_REG_BUCK1		0x04
+#define MP5416_REG_BUCK2		0x05
+#define MP5416_REG_BUCK3		0x06
+#define MP5416_REG_BUCK4		0x07
+#define MP5416_REG_LDO1			0x08
+#define MP5416_REG_LDO2			0x09
+#define MP5416_REG_LDO3			0x0a
+#define MP5416_REG_LDO4			0x0b
+
+#define MP5416_REGULATOR_EN		BIT(7)
+#define MP5416_MASK_VSET		0x7f
+#define MP5416_MASK_BUCK1_ILIM		0xc0
+#define MP5416_MASK_BUCK2_ILIM		0x0c
+#define MP5416_MASK_BUCK3_ILIM		0x30
+#define MP5416_MASK_BUCK4_ILIM		0x03
+#define MP5416_MASK_DVS_SLEWRATE	0xc0
+
+/* values in uV */
+#define MP5416_VOLT1_MIN		600000
+#define MP5416_VOLT1_MAX		2187500
+#define MP5416_VOLT1_STEP		12500
+#define MP5416_VOLT2_MIN		800000
+#define MP5416_VOLT2_MAX		3975000
+#define MP5416_VOLT2_STEP		25000
+
+#define MP5416_VOLT1_RANGE \
+	((MP5416_VOLT1_MAX - MP5416_VOLT1_MIN)/MP5416_VOLT1_STEP + 1)
+#define MP5416_VOLT2_RANGE \
+	((MP5416_VOLT2_MAX - MP5416_VOLT2_MIN)/MP5416_VOLT2_STEP + 1)
+
+#define MP5416BUCK(_name, _id, _ilim, _dreg, _dval, _vsel)		\
+	[MP5416_BUCK ## _id] = {					\
+		.id = MP5416_BUCK ## _id,				\
+		.name = _name,						\
+		.of_match = _name,					\
+		.regulators_node = "regulators",			\
+		.ops = &mp5416_buck_ops,				\
+		.min_uV = MP5416_VOLT ##_vsel## _MIN,			\
+		.uV_step = MP5416_VOLT ##_vsel## _STEP,			\
+		.n_voltages = MP5416_VOLT ##_vsel## _RANGE,		\
+		.curr_table = _ilim,					\
+		.n_current_limits = ARRAY_SIZE(_ilim),			\
+		.csel_reg = MP5416_REG_ILIM,				\
+		.csel_mask = MP5416_MASK_BUCK ## _id ##_ILIM,		\
+		.vsel_reg = MP5416_REG_BUCK ## _id,			\
+		.vsel_mask = MP5416_MASK_VSET,				\
+		.enable_reg = MP5416_REG_BUCK ## _id,			\
+		.enable_mask = MP5416_REGULATOR_EN,			\
+		.ramp_reg = MP5416_REG_CTL2,				\
+		.ramp_mask = MP5416_MASK_DVS_SLEWRATE,			\
+		.ramp_delay_table = mp5416_buck_ramp_table,		\
+		.n_ramp_values = ARRAY_SIZE(mp5416_buck_ramp_table),	\
+		.active_discharge_on	= _dval,			\
+		.active_discharge_reg	= _dreg,			\
+		.active_discharge_mask	= _dval,			\
+		.owner			= THIS_MODULE,			\
+	}
+
+#define MP5416LDO(_name, _id, _dval)					\
+	[MP5416_LDO ## _id] = {						\
+		.id = MP5416_LDO ## _id,				\
+		.name = _name,						\
+		.of_match = _name,					\
+		.regulators_node = "regulators",			\
+		.ops = &mp5416_ldo_ops,					\
+		.min_uV = MP5416_VOLT2_MIN,				\
+		.uV_step = MP5416_VOLT2_STEP,				\
+		.n_voltages = MP5416_VOLT2_RANGE,			\
+		.vsel_reg = MP5416_REG_LDO ##_id,			\
+		.vsel_mask = MP5416_MASK_VSET,				\
+		.enable_reg = MP5416_REG_LDO ##_id,			\
+		.enable_mask = MP5416_REGULATOR_EN,			\
+		.active_discharge_on	= _dval,			\
+		.active_discharge_reg	= MP5416_REG_CTL2,		\
+		.active_discharge_mask	= _dval,			\
+		.owner			= THIS_MODULE,			\
+	}
+
+enum mp5416_regulators {
+	MP5416_BUCK1,
+	MP5416_BUCK2,
+	MP5416_BUCK3,
+	MP5416_BUCK4,
+	MP5416_LDO1,
+	MP5416_LDO2,
+	MP5416_LDO3,
+	MP5416_LDO4,
+	MP5416_MAX_REGULATORS,
+};
+
+static const struct regmap_config mp5416_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = 0x0d,
+};
+
+/* Current limits array (in uA)
+ * ILIM1 & ILIM3
+ */
+static const unsigned int mp5416_I_limits1[] = {
+	3800000, 4600000, 5600000, 6800000
+};
+
+/* ILIM2 & ILIM4 */
+static const unsigned int mp5416_I_limits2[] = {
+	2200000, 3200000, 4200000, 5200000
+};
+
+/*
+ * DVS ramp rate BUCK1 to BUCK4
+ * 00: 32mV/us
+ * 01: 16mV/us
+ * 10: 8mV/us
+ * 11: 4mV/us
+ */
+static const unsigned int mp5416_buck_ramp_table[] = {
+	32000, 16000, 8000, 4000
+};
+
+static const struct regulator_ops mp5416_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,
+};
+
+static const struct regulator_ops mp5416_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,
+	.get_current_limit	= regulator_get_current_limit_regmap,
+	.set_current_limit	= regulator_set_current_limit_regmap,
+	.set_ramp_delay		= regulator_set_ramp_delay_regmap,
+};
+
+static const struct regulator_desc mp5416_regulators_desc[MP5416_MAX_REGULATORS] = {
+	MP5416BUCK("buck1", 1, mp5416_I_limits1, MP5416_REG_CTL1, BIT(0), 1),
+	MP5416BUCK("buck2", 2, mp5416_I_limits2, MP5416_REG_CTL1, BIT(1), 2),
+	MP5416BUCK("buck3", 3, mp5416_I_limits1, MP5416_REG_CTL1, BIT(2), 1),
+	MP5416BUCK("buck4", 4, mp5416_I_limits2, MP5416_REG_CTL2, BIT(5), 2),
+	MP5416LDO("ldo1", 1, BIT(4)),
+	MP5416LDO("ldo2", 2, BIT(3)),
+	MP5416LDO("ldo3", 3, BIT(2)),
+	MP5416LDO("ldo4", 4, BIT(1)),
+};
+
+static const struct regulator_desc mp5496_regulators_desc[MP5416_MAX_REGULATORS] = {
+	MP5416BUCK("buck1", 1, mp5416_I_limits1, MP5416_REG_CTL1, BIT(0), 1),
+	MP5416BUCK("buck2", 2, mp5416_I_limits2, MP5416_REG_CTL1, BIT(1), 1),
+	MP5416BUCK("buck3", 3, mp5416_I_limits1, MP5416_REG_CTL1, BIT(2), 1),
+	MP5416BUCK("buck4", 4, mp5416_I_limits2, MP5416_REG_CTL2, BIT(5), 1),
+	MP5416LDO("ldo1", 1, BIT(4)),
+	MP5416LDO("ldo2", 2, BIT(3)),
+	MP5416LDO("ldo3", 3, BIT(2)),
+	MP5416LDO("ldo4", 4, BIT(1)),
+};
+
+static int mp5416_i2c_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct regulator_config config = { NULL, };
+	static const struct regulator_desc *desc;
+	struct regulator_dev *rdev;
+	struct regmap *regmap;
+	int i;
+
+	regmap = devm_regmap_init_i2c(client, &mp5416_regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err(dev, "Failed to allocate regmap!\n");
+		return PTR_ERR(regmap);
+	}
+
+	desc = i2c_get_match_data(client);
+	if (!desc)
+		return -ENODEV;
+
+	config.dev = dev;
+	config.regmap = regmap;
+
+	for (i = 0; i < MP5416_MAX_REGULATORS; i++) {
+		rdev = devm_regulator_register(dev,
+					       &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 mp5416_of_match[] = {
+	{ .compatible = "mps,mp5416", .data = &mp5416_regulators_desc },
+	{ .compatible = "mps,mp5496", .data = &mp5496_regulators_desc },
+	{}
+};
+MODULE_DEVICE_TABLE(of, mp5416_of_match);
+
+static const struct i2c_device_id mp5416_id[] = {
+	{ .name = "mp5416", .driver_data = (kernel_ulong_t)&mp5416_regulators_desc },
+	{ .name = "mp5496", .driver_data = (kernel_ulong_t)&mp5496_regulators_desc },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, mp5416_id);
+
+static struct i2c_driver mp5416_regulator_driver = {
+	.driver = {
+		.name = "mp5416",
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+		.of_match_table = of_match_ptr(mp5416_of_match),
+	},
+	.probe = mp5416_i2c_probe,
+	.id_table = mp5416_id,
+};
+module_i2c_driver(mp5416_regulator_driver);
+
+MODULE_AUTHOR("Saravanan Sekar <sravanhome@gmail.com>");
+MODULE_DESCRIPTION("MP5416 PMIC regulator driver");
+MODULE_LICENSE("GPL");