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, 381 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-88pm860x.c b/drivers/rtc/rtc-88pm860x.c
new file mode 100644
index 000000000..964cd048f
--- /dev/null
+++ b/drivers/rtc/rtc-88pm860x.c
@@ -0,0 +1,381 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Real Time Clock driver for Marvell 88PM860x PMIC
+ *
+ * Copyright (c) 2010 Marvell International Ltd.
+ * Author:	Haojian Zhuang <haojian.zhuang@marvell.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+#include <linux/rtc.h>
+#include <linux/delay.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/88pm860x.h>
+
+#define VRTC_CALIBRATION
+
+struct pm860x_rtc_info {
+	struct pm860x_chip	*chip;
+	struct i2c_client	*i2c;
+	struct rtc_device	*rtc_dev;
+	struct device		*dev;
+	struct delayed_work	calib_work;
+
+	int			irq;
+	int			vrtc;
+};
+
+#define REG_VRTC_MEAS1		0x7D
+
+#define REG0_ADDR		0xB0
+#define REG1_ADDR		0xB2
+#define REG2_ADDR		0xB4
+#define REG3_ADDR		0xB6
+
+#define REG0_DATA		0xB1
+#define REG1_DATA		0xB3
+#define REG2_DATA		0xB5
+#define REG3_DATA		0xB7
+
+/* bit definitions of Measurement Enable Register 2 (0x51) */
+#define MEAS2_VRTC		(1 << 0)
+
+/* bit definitions of RTC Register 1 (0xA0) */
+#define ALARM_EN		(1 << 3)
+#define ALARM_WAKEUP		(1 << 4)
+#define ALARM			(1 << 5)
+#define RTC1_USE_XO		(1 << 7)
+
+#define VRTC_CALIB_INTERVAL	(HZ * 60 * 10)		/* 10 minutes */
+
+static irqreturn_t rtc_update_handler(int irq, void *data)
+{
+	struct pm860x_rtc_info *info = (struct pm860x_rtc_info *)data;
+	int mask;
+
+	mask = ALARM | ALARM_WAKEUP;
+	pm860x_set_bits(info->i2c, PM8607_RTC1, mask | ALARM_EN, mask);
+	rtc_update_irq(info->rtc_dev, 1, RTC_AF);
+	return IRQ_HANDLED;
+}
+
+static int pm860x_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+	struct pm860x_rtc_info *info = dev_get_drvdata(dev);
+
+	if (enabled)
+		pm860x_set_bits(info->i2c, PM8607_RTC1, ALARM_EN, ALARM_EN);
+	else
+		pm860x_set_bits(info->i2c, PM8607_RTC1, ALARM_EN, 0);
+	return 0;
+}
+
+static int pm860x_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct pm860x_rtc_info *info = dev_get_drvdata(dev);
+	unsigned char buf[8];
+	unsigned long ticks, base, data;
+
+	pm860x_page_bulk_read(info->i2c, REG0_ADDR, 8, buf);
+	dev_dbg(info->dev, "%x-%x-%x-%x-%x-%x-%x-%x\n", buf[0], buf[1],
+		buf[2], buf[3], buf[4], buf[5], buf[6], buf[7]);
+	base = ((unsigned long)buf[1] << 24) | (buf[3] << 16) |
+		(buf[5] << 8) | buf[7];
+
+	/* load 32-bit read-only counter */
+	pm860x_bulk_read(info->i2c, PM8607_RTC_COUNTER1, 4, buf);
+	data = ((unsigned long)buf[3] << 24) | (buf[2] << 16) |
+		(buf[1] << 8) | buf[0];
+	ticks = base + data;
+	dev_dbg(info->dev, "get base:0x%lx, RO count:0x%lx, ticks:0x%lx\n",
+		base, data, ticks);
+
+	rtc_time64_to_tm(ticks, tm);
+
+	return 0;
+}
+
+static int pm860x_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct pm860x_rtc_info *info = dev_get_drvdata(dev);
+	unsigned char buf[4];
+	unsigned long ticks, base, data;
+
+	ticks = rtc_tm_to_time64(tm);
+
+	/* load 32-bit read-only counter */
+	pm860x_bulk_read(info->i2c, PM8607_RTC_COUNTER1, 4, buf);
+	data = ((unsigned long)buf[3] << 24) | (buf[2] << 16) |
+		(buf[1] << 8) | buf[0];
+	base = ticks - data;
+	dev_dbg(info->dev, "set base:0x%lx, RO count:0x%lx, ticks:0x%lx\n",
+		base, data, ticks);
+
+	pm860x_page_reg_write(info->i2c, REG0_DATA, (base >> 24) & 0xFF);
+	pm860x_page_reg_write(info->i2c, REG1_DATA, (base >> 16) & 0xFF);
+	pm860x_page_reg_write(info->i2c, REG2_DATA, (base >> 8) & 0xFF);
+	pm860x_page_reg_write(info->i2c, REG3_DATA, base & 0xFF);
+
+	return 0;
+}
+
+static int pm860x_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct pm860x_rtc_info *info = dev_get_drvdata(dev);
+	unsigned char buf[8];
+	unsigned long ticks, base, data;
+	int ret;
+
+	pm860x_page_bulk_read(info->i2c, REG0_ADDR, 8, buf);
+	dev_dbg(info->dev, "%x-%x-%x-%x-%x-%x-%x-%x\n", buf[0], buf[1],
+		buf[2], buf[3], buf[4], buf[5], buf[6], buf[7]);
+	base = ((unsigned long)buf[1] << 24) | (buf[3] << 16) |
+		(buf[5] << 8) | buf[7];
+
+	pm860x_bulk_read(info->i2c, PM8607_RTC_EXPIRE1, 4, buf);
+	data = ((unsigned long)buf[3] << 24) | (buf[2] << 16) |
+		(buf[1] << 8) | buf[0];
+	ticks = base + data;
+	dev_dbg(info->dev, "get base:0x%lx, RO count:0x%lx, ticks:0x%lx\n",
+		base, data, ticks);
+
+	rtc_time64_to_tm(ticks, &alrm->time);
+	ret = pm860x_reg_read(info->i2c, PM8607_RTC1);
+	alrm->enabled = (ret & ALARM_EN) ? 1 : 0;
+	alrm->pending = (ret & (ALARM | ALARM_WAKEUP)) ? 1 : 0;
+	return 0;
+}
+
+static int pm860x_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct pm860x_rtc_info *info = dev_get_drvdata(dev);
+	unsigned long ticks, base, data;
+	unsigned char buf[8];
+	int mask;
+
+	pm860x_set_bits(info->i2c, PM8607_RTC1, ALARM_EN, 0);
+
+	pm860x_page_bulk_read(info->i2c, REG0_ADDR, 8, buf);
+	dev_dbg(info->dev, "%x-%x-%x-%x-%x-%x-%x-%x\n", buf[0], buf[1],
+		buf[2], buf[3], buf[4], buf[5], buf[6], buf[7]);
+	base = ((unsigned long)buf[1] << 24) | (buf[3] << 16) |
+		(buf[5] << 8) | buf[7];
+
+	ticks = rtc_tm_to_time64(&alrm->time);
+	data = ticks - base;
+
+	buf[0] = data & 0xff;
+	buf[1] = (data >> 8) & 0xff;
+	buf[2] = (data >> 16) & 0xff;
+	buf[3] = (data >> 24) & 0xff;
+	pm860x_bulk_write(info->i2c, PM8607_RTC_EXPIRE1, 4, buf);
+	if (alrm->enabled) {
+		mask = ALARM | ALARM_WAKEUP | ALARM_EN;
+		pm860x_set_bits(info->i2c, PM8607_RTC1, mask, mask);
+	} else {
+		mask = ALARM | ALARM_WAKEUP | ALARM_EN;
+		pm860x_set_bits(info->i2c, PM8607_RTC1, mask,
+				ALARM | ALARM_WAKEUP);
+	}
+	return 0;
+}
+
+static const struct rtc_class_ops pm860x_rtc_ops = {
+	.read_time	= pm860x_rtc_read_time,
+	.set_time	= pm860x_rtc_set_time,
+	.read_alarm	= pm860x_rtc_read_alarm,
+	.set_alarm	= pm860x_rtc_set_alarm,
+	.alarm_irq_enable = pm860x_rtc_alarm_irq_enable,
+};
+
+#ifdef VRTC_CALIBRATION
+static void calibrate_vrtc_work(struct work_struct *work)
+{
+	struct pm860x_rtc_info *info = container_of(work,
+		struct pm860x_rtc_info, calib_work.work);
+	unsigned char buf[2];
+	unsigned int sum, data, mean, vrtc_set;
+	int i;
+
+	for (i = 0, sum = 0; i < 16; i++) {
+		msleep(100);
+		pm860x_bulk_read(info->i2c, REG_VRTC_MEAS1, 2, buf);
+		data = (buf[0] << 4) | buf[1];
+		data = (data * 5400) >> 12;	/* convert to mv */
+		sum += data;
+	}
+	mean = sum >> 4;
+	vrtc_set = 2700 + (info->vrtc & 0x3) * 200;
+	dev_dbg(info->dev, "mean:%d, vrtc_set:%d\n", mean, vrtc_set);
+
+	sum = pm860x_reg_read(info->i2c, PM8607_RTC_MISC1);
+	data = sum & 0x3;
+	if ((mean + 200) < vrtc_set) {
+		/* try higher voltage */
+		if (++data == 4)
+			goto out;
+		data = (sum & 0xf8) | (data & 0x3);
+		pm860x_reg_write(info->i2c, PM8607_RTC_MISC1, data);
+	} else if ((mean - 200) > vrtc_set) {
+		/* try lower voltage */
+		if (data-- == 0)
+			goto out;
+		data = (sum & 0xf8) | (data & 0x3);
+		pm860x_reg_write(info->i2c, PM8607_RTC_MISC1, data);
+	} else
+		goto out;
+	dev_dbg(info->dev, "set 0x%x to RTC_MISC1\n", data);
+	/* trigger next calibration since VRTC is updated */
+	schedule_delayed_work(&info->calib_work, VRTC_CALIB_INTERVAL);
+	return;
+out:
+	/* disable measurement */
+	pm860x_set_bits(info->i2c, PM8607_MEAS_EN2, MEAS2_VRTC, 0);
+	dev_dbg(info->dev, "finish VRTC calibration\n");
+	return;
+}
+#endif
+
+#ifdef CONFIG_OF
+static int pm860x_rtc_dt_init(struct platform_device *pdev,
+			      struct pm860x_rtc_info *info)
+{
+	struct device_node *np = pdev->dev.parent->of_node;
+	int ret;
+	if (!np)
+		return -ENODEV;
+	np = of_get_child_by_name(np, "rtc");
+	if (!np) {
+		dev_err(&pdev->dev, "failed to find rtc node\n");
+		return -ENODEV;
+	}
+	ret = of_property_read_u32(np, "marvell,88pm860x-vrtc", &info->vrtc);
+	if (ret)
+		info->vrtc = 0;
+	of_node_put(np);
+	return 0;
+}
+#else
+#define pm860x_rtc_dt_init(x, y)	do { } while (0)
+#endif
+
+static int pm860x_rtc_probe(struct platform_device *pdev)
+{
+	struct pm860x_chip *chip = dev_get_drvdata(pdev->dev.parent);
+	struct pm860x_rtc_info *info;
+	int ret;
+
+	info = devm_kzalloc(&pdev->dev, sizeof(struct pm860x_rtc_info),
+			    GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+	info->irq = platform_get_irq(pdev, 0);
+	if (info->irq < 0)
+		return info->irq;
+
+	info->chip = chip;
+	info->i2c = (chip->id == CHIP_PM8607) ? chip->client : chip->companion;
+	info->dev = &pdev->dev;
+	dev_set_drvdata(&pdev->dev, info);
+
+	info->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
+	if (IS_ERR(info->rtc_dev))
+		return PTR_ERR(info->rtc_dev);
+
+	ret = devm_request_threaded_irq(&pdev->dev, info->irq, NULL,
+					rtc_update_handler, IRQF_ONESHOT, "rtc",
+					info);
+	if (ret < 0) {
+		dev_err(chip->dev, "Failed to request IRQ: #%d: %d\n",
+			info->irq, ret);
+		return ret;
+	}
+
+	/* set addresses of 32-bit base value for RTC time */
+	pm860x_page_reg_write(info->i2c, REG0_ADDR, REG0_DATA);
+	pm860x_page_reg_write(info->i2c, REG1_ADDR, REG1_DATA);
+	pm860x_page_reg_write(info->i2c, REG2_ADDR, REG2_DATA);
+	pm860x_page_reg_write(info->i2c, REG3_ADDR, REG3_DATA);
+
+	pm860x_rtc_dt_init(pdev, info);
+
+	info->rtc_dev->ops = &pm860x_rtc_ops;
+	info->rtc_dev->range_max = U32_MAX;
+
+	ret = devm_rtc_register_device(info->rtc_dev);
+	if (ret)
+		return ret;
+
+	/*
+	 * enable internal XO instead of internal 3.25MHz clock since it can
+	 * free running in PMIC power-down state.
+	 */
+	pm860x_set_bits(info->i2c, PM8607_RTC1, RTC1_USE_XO, RTC1_USE_XO);
+
+#ifdef VRTC_CALIBRATION
+	/* <00> -- 2.7V, <01> -- 2.9V, <10> -- 3.1V, <11> -- 3.3V */
+	pm860x_set_bits(info->i2c, PM8607_MEAS_EN2, MEAS2_VRTC, MEAS2_VRTC);
+
+	/* calibrate VRTC */
+	INIT_DELAYED_WORK(&info->calib_work, calibrate_vrtc_work);
+	schedule_delayed_work(&info->calib_work, VRTC_CALIB_INTERVAL);
+#endif	/* VRTC_CALIBRATION */
+
+	device_init_wakeup(&pdev->dev, true);
+
+	return 0;
+}
+
+static void pm860x_rtc_remove(struct platform_device *pdev)
+{
+	struct pm860x_rtc_info *info = platform_get_drvdata(pdev);
+
+#ifdef VRTC_CALIBRATION
+	cancel_delayed_work_sync(&info->calib_work);
+	/* disable measurement */
+	pm860x_set_bits(info->i2c, PM8607_MEAS_EN2, MEAS2_VRTC, 0);
+#endif	/* VRTC_CALIBRATION */
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int pm860x_rtc_suspend(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct pm860x_chip *chip = dev_get_drvdata(pdev->dev.parent);
+
+	if (device_may_wakeup(dev))
+		chip->wakeup_flag |= 1 << PM8607_IRQ_RTC;
+	return 0;
+}
+static int pm860x_rtc_resume(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct pm860x_chip *chip = dev_get_drvdata(pdev->dev.parent);
+
+	if (device_may_wakeup(dev))
+		chip->wakeup_flag &= ~(1 << PM8607_IRQ_RTC);
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(pm860x_rtc_pm_ops, pm860x_rtc_suspend, pm860x_rtc_resume);
+
+static struct platform_driver pm860x_rtc_driver = {
+	.driver		= {
+		.name	= "88pm860x-rtc",
+		.pm	= &pm860x_rtc_pm_ops,
+	},
+	.probe		= pm860x_rtc_probe,
+	.remove		= pm860x_rtc_remove,
+};
+
+module_platform_driver(pm860x_rtc_driver);
+
+MODULE_DESCRIPTION("Marvell 88PM860x RTC driver");
+MODULE_AUTHOR("Haojian Zhuang <haojian.zhuang@marvell.com>");
+MODULE_LICENSE("GPL");