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, 180 insertions, 0 deletions

diff --git a/drivers/mfd/max77705.c b/drivers/mfd/max77705.c
new file mode 100644
index 000000000..e98c76d6b
--- /dev/null
+++ b/drivers/mfd/max77705.c
@@ -0,0 +1,180 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Maxim MAX77705 PMIC core driver
+ *
+ * Copyright (C) 2025 Dzmitry Sankouski <dsankouski@gmail.com>
+ **/
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/max77705-private.h>
+#include <linux/mfd/max77693-common.h>
+#include <linux/pm.h>
+#include <linux/power/max17042_battery.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/of.h>
+
+static struct mfd_cell max77705_devs[] = {
+	MFD_CELL_OF("max77705-rgb", NULL, NULL, 0, 0, "maxim,max77705-rgb"),
+	MFD_CELL_OF("max77705-charger", NULL, NULL, 0, 0, "maxim,max77705-charger"),
+	MFD_CELL_OF("max77705-haptic", NULL, NULL, 0, 0, "maxim,max77705-haptic"),
+};
+
+static const struct regmap_range max77705_readable_ranges[] = {
+	regmap_reg_range(MAX77705_PMIC_REG_PMICID1,		MAX77705_PMIC_REG_BSTOUT_MASK),
+	regmap_reg_range(MAX77705_PMIC_REG_INTSRC,		MAX77705_PMIC_REG_RESERVED_29),
+	regmap_reg_range(MAX77705_PMIC_REG_BOOSTCONTROL1,	MAX77705_PMIC_REG_BOOSTCONTROL1),
+	regmap_reg_range(MAX77705_PMIC_REG_MCONFIG,		MAX77705_PMIC_REG_MCONFIG2),
+	regmap_reg_range(MAX77705_PMIC_REG_FORCE_EN_MASK,	MAX77705_PMIC_REG_FORCE_EN_MASK),
+	regmap_reg_range(MAX77705_PMIC_REG_BOOSTCONTROL1,	MAX77705_PMIC_REG_BOOSTCONTROL1),
+	regmap_reg_range(MAX77705_PMIC_REG_BOOSTCONTROL2,	MAX77705_PMIC_REG_BOOSTCONTROL2),
+	regmap_reg_range(MAX77705_PMIC_REG_SW_RESET,		MAX77705_PMIC_REG_USBC_RESET),
+};
+
+static const struct regmap_range max77705_writable_ranges[] = {
+	regmap_reg_range(MAX77705_PMIC_REG_MAINCTRL1,		MAX77705_PMIC_REG_BSTOUT_MASK),
+	regmap_reg_range(MAX77705_PMIC_REG_INTSRC,		MAX77705_PMIC_REG_RESERVED_29),
+	regmap_reg_range(MAX77705_PMIC_REG_BOOSTCONTROL1,	MAX77705_PMIC_REG_BOOSTCONTROL1),
+	regmap_reg_range(MAX77705_PMIC_REG_MCONFIG,		MAX77705_PMIC_REG_MCONFIG2),
+	regmap_reg_range(MAX77705_PMIC_REG_FORCE_EN_MASK,	MAX77705_PMIC_REG_FORCE_EN_MASK),
+	regmap_reg_range(MAX77705_PMIC_REG_BOOSTCONTROL1,	MAX77705_PMIC_REG_BOOSTCONTROL1),
+	regmap_reg_range(MAX77705_PMIC_REG_BOOSTCONTROL2,	MAX77705_PMIC_REG_BOOSTCONTROL2),
+	regmap_reg_range(MAX77705_PMIC_REG_SW_RESET,		MAX77705_PMIC_REG_USBC_RESET),
+};
+
+static const struct regmap_access_table max77705_readable_table = {
+	.yes_ranges = max77705_readable_ranges,
+	.n_yes_ranges = ARRAY_SIZE(max77705_readable_ranges),
+};
+
+static const struct regmap_access_table max77705_writable_table = {
+	.yes_ranges = max77705_writable_ranges,
+	.n_yes_ranges = ARRAY_SIZE(max77705_writable_ranges),
+};
+
+static const struct regmap_config max77705_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.rd_table = &max77705_readable_table,
+	.wr_table = &max77705_writable_table,
+	.max_register = MAX77705_PMIC_REG_USBC_RESET,
+};
+
+static const struct regmap_irq max77705_irqs[] = {
+	{ .mask = MAX77705_SRC_IRQ_CHG, },
+	{ .mask = MAX77705_SRC_IRQ_TOP, },
+	{ .mask = MAX77705_SRC_IRQ_FG, },
+	{ .mask = MAX77705_SRC_IRQ_USBC, },
+};
+
+static const struct regmap_irq_chip max77705_irq_chip = {
+	.name		= "max77705",
+	.status_base	= MAX77705_PMIC_REG_INTSRC,
+	.ack_base	= MAX77705_PMIC_REG_INTSRC,
+	.mask_base	= MAX77705_PMIC_REG_INTSRC_MASK,
+	.num_regs	= 1,
+	.irqs		= max77705_irqs,
+	.num_irqs	= ARRAY_SIZE(max77705_irqs),
+};
+
+static int max77705_i2c_probe(struct i2c_client *i2c)
+{
+	struct device *dev = &i2c->dev;
+	struct max77693_dev *max77705;
+	struct regmap_irq_chip_data *irq_data;
+	struct irq_domain *domain;
+	enum max77705_hw_rev pmic_rev;
+	unsigned int pmic_rev_value;
+	int ret;
+
+	max77705 = devm_kzalloc(dev, sizeof(*max77705), GFP_KERNEL);
+	if (!max77705)
+		return -ENOMEM;
+
+	max77705->i2c = i2c;
+	max77705->type = TYPE_MAX77705;
+	i2c_set_clientdata(i2c, max77705);
+
+	max77705->regmap = devm_regmap_init_i2c(i2c, &max77705_regmap_config);
+	if (IS_ERR(max77705->regmap))
+		return PTR_ERR(max77705->regmap);
+
+	ret = regmap_read(max77705->regmap, MAX77705_PMIC_REG_PMICREV, &pmic_rev_value);
+	if (ret < 0)
+		return -ENODEV;
+
+	pmic_rev = pmic_rev_value & MAX77705_REVISION_MASK;
+	if (pmic_rev != MAX77705_PASS3)
+		return dev_err_probe(dev, -ENODEV, "Rev.0x%x is not tested\n", pmic_rev);
+
+	/* Active Discharge Enable */
+	regmap_update_bits(max77705->regmap, MAX77705_PMIC_REG_MAINCTRL1, 1, 1);
+
+	ret = devm_regmap_add_irq_chip(dev, max77705->regmap,
+					i2c->irq,
+					IRQF_ONESHOT, 0,
+					&max77705_irq_chip,
+					&irq_data);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to add IRQ chip\n");
+
+	domain = regmap_irq_get_domain(irq_data);
+
+	ret = devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE,
+				   max77705_devs, ARRAY_SIZE(max77705_devs),
+				   NULL, 0, domain);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to register child devices\n");
+
+	ret = devm_device_init_wakeup(dev);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to init wakeup\n");
+
+	return 0;
+}
+
+static int max77705_suspend(struct device *dev)
+{
+	struct i2c_client *i2c = to_i2c_client(dev);
+
+	disable_irq(i2c->irq);
+
+	if (device_may_wakeup(dev))
+		enable_irq_wake(i2c->irq);
+
+	return 0;
+}
+
+static int max77705_resume(struct device *dev)
+{
+	struct i2c_client *i2c = to_i2c_client(dev);
+
+	if (device_may_wakeup(dev))
+		disable_irq_wake(i2c->irq);
+
+	enable_irq(i2c->irq);
+
+	return 0;
+}
+static DEFINE_SIMPLE_DEV_PM_OPS(max77705_pm_ops, max77705_suspend, max77705_resume);
+
+static const struct of_device_id max77705_i2c_of_match[] = {
+	{ .compatible = "maxim,max77705" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max77705_i2c_of_match);
+
+static struct i2c_driver max77705_i2c_driver = {
+	.driver = {
+		.name			= "max77705",
+		.of_match_table		= max77705_i2c_of_match,
+		.pm			= pm_sleep_ptr(&max77705_pm_ops),
+	},
+	.probe = max77705_i2c_probe
+};
+module_i2c_driver(max77705_i2c_driver);
+
+MODULE_DESCRIPTION("Maxim MAX77705 PMIC core driver");
+MODULE_AUTHOR("Dzmitry Sankouski <dsankouski@gmail.com>");
+MODULE_LICENSE("GPL");