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, 390 insertions, 0 deletions

diff --git a/drivers/regulator/s2mpa01.c b/drivers/regulator/s2mpa01.c
new file mode 100644
index 000000000..817150386
--- /dev/null
+++ b/drivers/regulator/s2mpa01.c
@@ -0,0 +1,390 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// Copyright (c) 2013 Samsung Electronics Co., Ltd
+//		http://www.samsung.com
+
+#include <linux/bug.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/machine.h>
+#include <linux/regulator/of_regulator.h>
+#include <linux/mfd/samsung/core.h>
+#include <linux/mfd/samsung/s2mpa01.h>
+
+struct s2mpa01_info {
+	int ramp_delay24;
+	int ramp_delay3;
+	int ramp_delay5;
+	int ramp_delay16;
+	int ramp_delay7;
+	int ramp_delay8910;
+};
+
+static int get_ramp_delay(int ramp_delay)
+{
+	unsigned char cnt = 0;
+
+	ramp_delay /= 6250;
+
+	while (true) {
+		ramp_delay = ramp_delay >> 1;
+		if (ramp_delay == 0)
+			break;
+		cnt++;
+	}
+
+	if (cnt > 3)
+		cnt = 3;
+
+	return cnt;
+}
+
+static int s2mpa01_regulator_set_voltage_time_sel(struct regulator_dev *rdev,
+				   unsigned int old_selector,
+				   unsigned int new_selector)
+{
+	struct s2mpa01_info *s2mpa01 = rdev_get_drvdata(rdev);
+	unsigned int ramp_delay = 0;
+	int old_volt, new_volt;
+
+	switch (rdev_get_id(rdev)) {
+	case S2MPA01_BUCK2:
+	case S2MPA01_BUCK4:
+		ramp_delay = s2mpa01->ramp_delay24;
+		break;
+	case S2MPA01_BUCK3:
+		ramp_delay = s2mpa01->ramp_delay3;
+		break;
+	case S2MPA01_BUCK5:
+		ramp_delay = s2mpa01->ramp_delay5;
+		break;
+	case S2MPA01_BUCK1:
+	case S2MPA01_BUCK6:
+		ramp_delay = s2mpa01->ramp_delay16;
+		break;
+	case S2MPA01_BUCK7:
+		ramp_delay = s2mpa01->ramp_delay7;
+		break;
+	case S2MPA01_BUCK8:
+	case S2MPA01_BUCK9:
+	case S2MPA01_BUCK10:
+		ramp_delay = s2mpa01->ramp_delay8910;
+		break;
+	}
+
+	if (ramp_delay == 0)
+		ramp_delay = rdev->desc->ramp_delay;
+
+	old_volt = rdev->desc->min_uV + (rdev->desc->uV_step * old_selector);
+	new_volt = rdev->desc->min_uV + (rdev->desc->uV_step * new_selector);
+
+	return DIV_ROUND_UP(abs(new_volt - old_volt), ramp_delay);
+}
+
+static int s2mpa01_set_ramp_delay(struct regulator_dev *rdev, int ramp_delay)
+{
+	struct s2mpa01_info *s2mpa01 = rdev_get_drvdata(rdev);
+	unsigned int ramp_val, ramp_shift, ramp_reg = S2MPA01_REG_RAMP2;
+	unsigned int ramp_enable = 1, enable_shift = 0;
+	int ret;
+
+	switch (rdev_get_id(rdev)) {
+	case S2MPA01_BUCK1:
+		enable_shift = S2MPA01_BUCK1_RAMP_EN_SHIFT;
+		if (!ramp_delay) {
+			ramp_enable = 0;
+			break;
+		}
+
+		if (ramp_delay > s2mpa01->ramp_delay16)
+			s2mpa01->ramp_delay16 = ramp_delay;
+		else
+			ramp_delay = s2mpa01->ramp_delay16;
+
+		ramp_shift = S2MPA01_BUCK16_RAMP_SHIFT;
+		break;
+	case S2MPA01_BUCK2:
+		enable_shift = S2MPA01_BUCK2_RAMP_EN_SHIFT;
+		if (!ramp_delay) {
+			ramp_enable = 0;
+			break;
+		}
+
+		if (ramp_delay > s2mpa01->ramp_delay24)
+			s2mpa01->ramp_delay24 = ramp_delay;
+		else
+			ramp_delay = s2mpa01->ramp_delay24;
+
+		ramp_shift = S2MPA01_BUCK24_RAMP_SHIFT;
+		ramp_reg = S2MPA01_REG_RAMP1;
+		break;
+	case S2MPA01_BUCK3:
+		enable_shift = S2MPA01_BUCK3_RAMP_EN_SHIFT;
+		if (!ramp_delay) {
+			ramp_enable = 0;
+			break;
+		}
+
+		s2mpa01->ramp_delay3 = ramp_delay;
+		ramp_shift = S2MPA01_BUCK3_RAMP_SHIFT;
+		ramp_reg = S2MPA01_REG_RAMP1;
+		break;
+	case S2MPA01_BUCK4:
+		enable_shift = S2MPA01_BUCK4_RAMP_EN_SHIFT;
+		if (!ramp_delay) {
+			ramp_enable = 0;
+			break;
+		}
+
+		if (ramp_delay > s2mpa01->ramp_delay24)
+			s2mpa01->ramp_delay24 = ramp_delay;
+		else
+			ramp_delay = s2mpa01->ramp_delay24;
+
+		ramp_shift = S2MPA01_BUCK24_RAMP_SHIFT;
+		ramp_reg = S2MPA01_REG_RAMP1;
+		break;
+	case S2MPA01_BUCK5:
+		s2mpa01->ramp_delay5 = ramp_delay;
+		ramp_shift = S2MPA01_BUCK5_RAMP_SHIFT;
+		break;
+	case S2MPA01_BUCK6:
+		if (ramp_delay > s2mpa01->ramp_delay16)
+			s2mpa01->ramp_delay16 = ramp_delay;
+		else
+			ramp_delay = s2mpa01->ramp_delay16;
+
+		ramp_shift = S2MPA01_BUCK16_RAMP_SHIFT;
+		break;
+	case S2MPA01_BUCK7:
+		s2mpa01->ramp_delay7 = ramp_delay;
+		ramp_shift = S2MPA01_BUCK7_RAMP_SHIFT;
+		break;
+	case S2MPA01_BUCK8:
+	case S2MPA01_BUCK9:
+	case S2MPA01_BUCK10:
+		if (ramp_delay > s2mpa01->ramp_delay8910)
+			s2mpa01->ramp_delay8910 = ramp_delay;
+		else
+			ramp_delay = s2mpa01->ramp_delay8910;
+
+		ramp_shift = S2MPA01_BUCK8910_RAMP_SHIFT;
+		break;
+	default:
+		return 0;
+	}
+
+	if (!ramp_enable)
+		goto ramp_disable;
+
+	/* Ramp delay can be enabled/disabled only for buck[1234] */
+	if (rdev_get_id(rdev) >= S2MPA01_BUCK1 &&
+			rdev_get_id(rdev) <= S2MPA01_BUCK4) {
+		ret = regmap_update_bits(rdev->regmap, S2MPA01_REG_RAMP1,
+					 1 << enable_shift, 1 << enable_shift);
+		if (ret) {
+			dev_err(&rdev->dev, "failed to enable ramp rate\n");
+			return ret;
+		}
+	}
+
+	ramp_val = get_ramp_delay(ramp_delay);
+
+	return regmap_update_bits(rdev->regmap, ramp_reg, 0x3 << ramp_shift,
+				  ramp_val << ramp_shift);
+
+ramp_disable:
+	return regmap_update_bits(rdev->regmap, S2MPA01_REG_RAMP1,
+				  1 << enable_shift, 0);
+}
+
+static const struct regulator_ops s2mpa01_ldo_ops = {
+	.list_voltage		= regulator_list_voltage_linear,
+	.map_voltage		= regulator_map_voltage_linear,
+	.is_enabled		= regulator_is_enabled_regmap,
+	.enable			= regulator_enable_regmap,
+	.disable		= regulator_disable_regmap,
+	.get_voltage_sel	= regulator_get_voltage_sel_regmap,
+	.set_voltage_sel	= regulator_set_voltage_sel_regmap,
+	.set_voltage_time_sel	= regulator_set_voltage_time_sel,
+};
+
+static const struct regulator_ops s2mpa01_buck_ops = {
+	.list_voltage		= regulator_list_voltage_linear,
+	.map_voltage		= regulator_map_voltage_linear,
+	.is_enabled		= regulator_is_enabled_regmap,
+	.enable			= regulator_enable_regmap,
+	.disable		= regulator_disable_regmap,
+	.get_voltage_sel	= regulator_get_voltage_sel_regmap,
+	.set_voltage_sel	= regulator_set_voltage_sel_regmap,
+	.set_voltage_time_sel	= s2mpa01_regulator_set_voltage_time_sel,
+	.set_ramp_delay		= s2mpa01_set_ramp_delay,
+};
+
+#define regulator_desc_ldo(num, step) {			\
+	.name		= "LDO"#num,			\
+	.of_match	= of_match_ptr("LDO"#num),	\
+	.regulators_node = of_match_ptr("regulators"),	\
+	.id		= S2MPA01_LDO##num,		\
+	.ops		= &s2mpa01_ldo_ops,		\
+	.type		= REGULATOR_VOLTAGE,		\
+	.owner		= THIS_MODULE,			\
+	.min_uV		= MIN_800_MV,			\
+	.uV_step	= step,				\
+	.n_voltages	= S2MPA01_LDO_N_VOLTAGES,	\
+	.vsel_reg	= S2MPA01_REG_L1CTRL + num - 1,	\
+	.vsel_mask	= S2MPA01_LDO_VSEL_MASK,	\
+	.enable_reg	= S2MPA01_REG_L1CTRL + num - 1,	\
+	.enable_mask	= S2MPA01_ENABLE_MASK		\
+}
+
+#define regulator_desc_buck1_4(num)	{			\
+	.name		= "BUCK"#num,				\
+	.of_match	= of_match_ptr("BUCK"#num),		\
+	.regulators_node = of_match_ptr("regulators"),		\
+	.id		= S2MPA01_BUCK##num,			\
+	.ops		= &s2mpa01_buck_ops,			\
+	.type		= REGULATOR_VOLTAGE,			\
+	.owner		= THIS_MODULE,				\
+	.min_uV		= MIN_600_MV,				\
+	.uV_step	= STEP_6_25_MV,				\
+	.n_voltages	= S2MPA01_BUCK_N_VOLTAGES,		\
+	.ramp_delay	= S2MPA01_RAMP_DELAY,			\
+	.vsel_reg	= S2MPA01_REG_B1CTRL2 + (num - 1) * 2,	\
+	.vsel_mask	= S2MPA01_BUCK_VSEL_MASK,		\
+	.enable_reg	= S2MPA01_REG_B1CTRL1 + (num - 1) * 2,	\
+	.enable_mask	= S2MPA01_ENABLE_MASK			\
+}
+
+#define regulator_desc_buck5	{				\
+	.name		= "BUCK5",				\
+	.of_match	= of_match_ptr("BUCK5"),		\
+	.regulators_node = of_match_ptr("regulators"),		\
+	.id		= S2MPA01_BUCK5,			\
+	.ops		= &s2mpa01_buck_ops,			\
+	.type		= REGULATOR_VOLTAGE,			\
+	.owner		= THIS_MODULE,				\
+	.min_uV		= MIN_800_MV,				\
+	.uV_step	= STEP_6_25_MV,				\
+	.n_voltages	= S2MPA01_BUCK_N_VOLTAGES,		\
+	.ramp_delay	= S2MPA01_RAMP_DELAY,			\
+	.vsel_reg	= S2MPA01_REG_B5CTRL2,			\
+	.vsel_mask	= S2MPA01_BUCK_VSEL_MASK,		\
+	.enable_reg	= S2MPA01_REG_B5CTRL1,			\
+	.enable_mask	= S2MPA01_ENABLE_MASK			\
+}
+
+#define regulator_desc_buck6_10(num, min, step) {			\
+	.name		= "BUCK"#num,				\
+	.of_match	= of_match_ptr("BUCK"#num),		\
+	.regulators_node = of_match_ptr("regulators"),		\
+	.id		= S2MPA01_BUCK##num,			\
+	.ops		= &s2mpa01_buck_ops,			\
+	.type		= REGULATOR_VOLTAGE,			\
+	.owner		= THIS_MODULE,				\
+	.min_uV		= min,					\
+	.uV_step	= step,					\
+	.n_voltages	= S2MPA01_BUCK_N_VOLTAGES,		\
+	.ramp_delay	= S2MPA01_RAMP_DELAY,			\
+	.vsel_reg	= S2MPA01_REG_B6CTRL2 + (num - 6) * 2,	\
+	.vsel_mask	= S2MPA01_BUCK_VSEL_MASK,		\
+	.enable_reg	= S2MPA01_REG_B6CTRL1 + (num - 6) * 2,	\
+	.enable_mask	= S2MPA01_ENABLE_MASK			\
+}
+
+static const struct regulator_desc regulators[] = {
+	regulator_desc_ldo(1, STEP_25_MV),
+	regulator_desc_ldo(2, STEP_50_MV),
+	regulator_desc_ldo(3, STEP_50_MV),
+	regulator_desc_ldo(4, STEP_50_MV),
+	regulator_desc_ldo(5, STEP_25_MV),
+	regulator_desc_ldo(6, STEP_25_MV),
+	regulator_desc_ldo(7, STEP_50_MV),
+	regulator_desc_ldo(8, STEP_50_MV),
+	regulator_desc_ldo(9, STEP_50_MV),
+	regulator_desc_ldo(10, STEP_50_MV),
+	regulator_desc_ldo(11, STEP_50_MV),
+	regulator_desc_ldo(12, STEP_50_MV),
+	regulator_desc_ldo(13, STEP_50_MV),
+	regulator_desc_ldo(14, STEP_50_MV),
+	regulator_desc_ldo(15, STEP_50_MV),
+	regulator_desc_ldo(16, STEP_50_MV),
+	regulator_desc_ldo(17, STEP_50_MV),
+	regulator_desc_ldo(18, STEP_50_MV),
+	regulator_desc_ldo(19, STEP_50_MV),
+	regulator_desc_ldo(20, STEP_50_MV),
+	regulator_desc_ldo(21, STEP_50_MV),
+	regulator_desc_ldo(22, STEP_50_MV),
+	regulator_desc_ldo(23, STEP_50_MV),
+	regulator_desc_ldo(24, STEP_50_MV),
+	regulator_desc_ldo(25, STEP_50_MV),
+	regulator_desc_ldo(26, STEP_25_MV),
+	regulator_desc_buck1_4(1),
+	regulator_desc_buck1_4(2),
+	regulator_desc_buck1_4(3),
+	regulator_desc_buck1_4(4),
+	regulator_desc_buck5,
+	regulator_desc_buck6_10(6, MIN_600_MV, STEP_6_25_MV),
+	regulator_desc_buck6_10(7, MIN_600_MV, STEP_6_25_MV),
+	regulator_desc_buck6_10(8, MIN_800_MV, STEP_12_5_MV),
+	regulator_desc_buck6_10(9, MIN_1500_MV, STEP_12_5_MV),
+	regulator_desc_buck6_10(10, MIN_1000_MV, STEP_12_5_MV),
+};
+
+static int s2mpa01_pmic_probe(struct platform_device *pdev)
+{
+	struct sec_pmic_dev *iodev = dev_get_drvdata(pdev->dev.parent);
+	struct regulator_config config = { };
+	struct s2mpa01_info *s2mpa01;
+	int i;
+
+	s2mpa01 = devm_kzalloc(&pdev->dev, sizeof(*s2mpa01), GFP_KERNEL);
+	if (!s2mpa01)
+		return -ENOMEM;
+
+	config.dev = iodev->dev;
+	config.regmap = iodev->regmap_pmic;
+	config.driver_data = s2mpa01;
+
+	for (i = 0; i < S2MPA01_REGULATOR_MAX; i++) {
+		struct regulator_dev *rdev;
+
+		rdev = devm_regulator_register(&pdev->dev,
+						&regulators[i], &config);
+		if (IS_ERR(rdev)) {
+			dev_err(&pdev->dev, "regulator init failed for %d\n",
+				i);
+			return PTR_ERR(rdev);
+		}
+	}
+
+	return 0;
+}
+
+static const struct platform_device_id s2mpa01_pmic_id[] = {
+	{ .name = "s2mpa01-pmic" },
+	{ }
+};
+MODULE_DEVICE_TABLE(platform, s2mpa01_pmic_id);
+
+static struct platform_driver s2mpa01_pmic_driver = {
+	.driver = {
+		.name = "s2mpa01-pmic",
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+	.probe = s2mpa01_pmic_probe,
+	.id_table = s2mpa01_pmic_id,
+};
+
+module_platform_driver(s2mpa01_pmic_driver);
+
+/* Module information */
+MODULE_AUTHOR("Sangbeom Kim <sbkim73@samsung.com>");
+MODULE_AUTHOR("Sachin Kamat <sachin.kamat@samsung.com>");
+MODULE_DESCRIPTION("Samsung S2MPA01 Regulator Driver");
+MODULE_LICENSE("GPL");