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, 340 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-88pm80x.c b/drivers/rtc/rtc-88pm80x.c
new file mode 100644
index 000000000..a3e52a5a7
--- /dev/null
+++ b/drivers/rtc/rtc-88pm80x.c
@@ -0,0 +1,340 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Real Time Clock driver for Marvell 88PM80x PMIC
+ *
+ * Copyright (c) 2012 Marvell International Ltd.
+ *  Wenzeng Chen<wzch@marvell.com>
+ *  Qiao Zhou <zhouqiao@marvell.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/regmap.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/88pm80x.h>
+#include <linux/rtc.h>
+
+#define PM800_RTC_COUNTER1		(0xD1)
+#define PM800_RTC_COUNTER2		(0xD2)
+#define PM800_RTC_COUNTER3		(0xD3)
+#define PM800_RTC_COUNTER4		(0xD4)
+#define PM800_RTC_EXPIRE1_1		(0xD5)
+#define PM800_RTC_EXPIRE1_2		(0xD6)
+#define PM800_RTC_EXPIRE1_3		(0xD7)
+#define PM800_RTC_EXPIRE1_4		(0xD8)
+#define PM800_RTC_TRIM1			(0xD9)
+#define PM800_RTC_TRIM2			(0xDA)
+#define PM800_RTC_TRIM3			(0xDB)
+#define PM800_RTC_TRIM4			(0xDC)
+#define PM800_RTC_EXPIRE2_1		(0xDD)
+#define PM800_RTC_EXPIRE2_2		(0xDE)
+#define PM800_RTC_EXPIRE2_3		(0xDF)
+#define PM800_RTC_EXPIRE2_4		(0xE0)
+
+#define PM800_POWER_DOWN_LOG1	(0xE5)
+#define PM800_POWER_DOWN_LOG2	(0xE6)
+
+struct pm80x_rtc_info {
+	struct pm80x_chip *chip;
+	struct regmap *map;
+	struct rtc_device *rtc_dev;
+	struct device *dev;
+
+	int irq;
+};
+
+static irqreturn_t rtc_update_handler(int irq, void *data)
+{
+	struct pm80x_rtc_info *info = (struct pm80x_rtc_info *)data;
+	int mask;
+
+	mask = PM800_ALARM | PM800_ALARM_WAKEUP;
+	regmap_update_bits(info->map, PM800_RTC_CONTROL, mask | PM800_ALARM1_EN,
+			   mask);
+	rtc_update_irq(info->rtc_dev, 1, RTC_AF);
+	return IRQ_HANDLED;
+}
+
+static int pm80x_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+	struct pm80x_rtc_info *info = dev_get_drvdata(dev);
+
+	if (enabled)
+		regmap_update_bits(info->map, PM800_RTC_CONTROL,
+				   PM800_ALARM1_EN, PM800_ALARM1_EN);
+	else
+		regmap_update_bits(info->map, PM800_RTC_CONTROL,
+				   PM800_ALARM1_EN, 0);
+	return 0;
+}
+
+/*
+ * Calculate the next alarm time given the requested alarm time mask
+ * and the current time.
+ */
+static void rtc_next_alarm_time(struct rtc_time *next, struct rtc_time *now,
+				struct rtc_time *alrm)
+{
+	unsigned long next_time;
+	unsigned long now_time;
+
+	next->tm_year = now->tm_year;
+	next->tm_mon = now->tm_mon;
+	next->tm_mday = now->tm_mday;
+	next->tm_hour = alrm->tm_hour;
+	next->tm_min = alrm->tm_min;
+	next->tm_sec = alrm->tm_sec;
+
+	now_time = rtc_tm_to_time64(now);
+	next_time = rtc_tm_to_time64(next);
+
+	if (next_time < now_time) {
+		/* Advance one day */
+		next_time += 60 * 60 * 24;
+		rtc_time64_to_tm(next_time, next);
+	}
+}
+
+static int pm80x_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct pm80x_rtc_info *info = dev_get_drvdata(dev);
+	unsigned char buf[4];
+	unsigned long ticks, base, data;
+	regmap_raw_read(info->map, PM800_RTC_EXPIRE2_1, buf, 4);
+	base = ((unsigned long)buf[3] << 24) | (buf[2] << 16) |
+		(buf[1] << 8) | buf[0];
+	dev_dbg(info->dev, "%x-%x-%x-%x\n", buf[0], buf[1], buf[2], buf[3]);
+
+	/* load 32-bit read-only counter */
+	regmap_raw_read(info->map, PM800_RTC_COUNTER1, buf, 4);
+	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 pm80x_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct pm80x_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 */
+	regmap_raw_read(info->map, PM800_RTC_COUNTER1, buf, 4);
+	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);
+	buf[0] = base & 0xFF;
+	buf[1] = (base >> 8) & 0xFF;
+	buf[2] = (base >> 16) & 0xFF;
+	buf[3] = (base >> 24) & 0xFF;
+	regmap_raw_write(info->map, PM800_RTC_EXPIRE2_1, buf, 4);
+
+	return 0;
+}
+
+static int pm80x_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct pm80x_rtc_info *info = dev_get_drvdata(dev);
+	unsigned char buf[4];
+	unsigned long ticks, base, data;
+	int ret;
+
+	regmap_raw_read(info->map, PM800_RTC_EXPIRE2_1, buf, 4);
+	base = ((unsigned long)buf[3] << 24) | (buf[2] << 16) |
+		(buf[1] << 8) | buf[0];
+	dev_dbg(info->dev, "%x-%x-%x-%x\n", buf[0], buf[1], buf[2], buf[3]);
+
+	regmap_raw_read(info->map, PM800_RTC_EXPIRE1_1, buf, 4);
+	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);
+	regmap_read(info->map, PM800_RTC_CONTROL, &ret);
+	alrm->enabled = (ret & PM800_ALARM1_EN) ? 1 : 0;
+	alrm->pending = (ret & (PM800_ALARM | PM800_ALARM_WAKEUP)) ? 1 : 0;
+	return 0;
+}
+
+static int pm80x_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct pm80x_rtc_info *info = dev_get_drvdata(dev);
+	struct rtc_time now_tm, alarm_tm;
+	unsigned long ticks, base, data;
+	unsigned char buf[4];
+	int mask;
+
+	regmap_update_bits(info->map, PM800_RTC_CONTROL, PM800_ALARM1_EN, 0);
+
+	regmap_raw_read(info->map, PM800_RTC_EXPIRE2_1, buf, 4);
+	base = ((unsigned long)buf[3] << 24) | (buf[2] << 16) |
+		(buf[1] << 8) | buf[0];
+	dev_dbg(info->dev, "%x-%x-%x-%x\n", buf[0], buf[1], buf[2], buf[3]);
+
+	/* load 32-bit read-only counter */
+	regmap_raw_read(info->map, PM800_RTC_COUNTER1, buf, 4);
+	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, &now_tm);
+	dev_dbg(info->dev, "%s, now time : %lu\n", __func__, ticks);
+	rtc_next_alarm_time(&alarm_tm, &now_tm, &alrm->time);
+	/* get new ticks for alarm in 24 hours */
+	ticks = rtc_tm_to_time64(&alarm_tm);
+	dev_dbg(info->dev, "%s, alarm time: %lu\n", __func__, ticks);
+	data = ticks - base;
+
+	buf[0] = data & 0xff;
+	buf[1] = (data >> 8) & 0xff;
+	buf[2] = (data >> 16) & 0xff;
+	buf[3] = (data >> 24) & 0xff;
+	regmap_raw_write(info->map, PM800_RTC_EXPIRE1_1, buf, 4);
+	if (alrm->enabled) {
+		mask = PM800_ALARM | PM800_ALARM_WAKEUP | PM800_ALARM1_EN;
+		regmap_update_bits(info->map, PM800_RTC_CONTROL, mask, mask);
+	} else {
+		mask = PM800_ALARM | PM800_ALARM_WAKEUP | PM800_ALARM1_EN;
+		regmap_update_bits(info->map, PM800_RTC_CONTROL, mask,
+				   PM800_ALARM | PM800_ALARM_WAKEUP);
+	}
+	return 0;
+}
+
+static const struct rtc_class_ops pm80x_rtc_ops = {
+	.read_time = pm80x_rtc_read_time,
+	.set_time = pm80x_rtc_set_time,
+	.read_alarm = pm80x_rtc_read_alarm,
+	.set_alarm = pm80x_rtc_set_alarm,
+	.alarm_irq_enable = pm80x_rtc_alarm_irq_enable,
+};
+
+#ifdef CONFIG_PM_SLEEP
+static int pm80x_rtc_suspend(struct device *dev)
+{
+	return pm80x_dev_suspend(dev);
+}
+
+static int pm80x_rtc_resume(struct device *dev)
+{
+	return pm80x_dev_resume(dev);
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(pm80x_rtc_pm_ops, pm80x_rtc_suspend, pm80x_rtc_resume);
+
+static int pm80x_rtc_probe(struct platform_device *pdev)
+{
+	struct pm80x_chip *chip = dev_get_drvdata(pdev->dev.parent);
+	struct pm80x_rtc_pdata *pdata = dev_get_platdata(&pdev->dev);
+	struct pm80x_rtc_info *info;
+	struct device_node *node = pdev->dev.of_node;
+	int ret;
+
+	if (!pdata && !node) {
+		dev_err(&pdev->dev,
+			"pm80x-rtc requires platform data or of_node\n");
+		return -EINVAL;
+	}
+
+	if (!pdata) {
+		pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
+		if (!pdata) {
+			dev_err(&pdev->dev, "failed to allocate memory\n");
+			return -ENOMEM;
+		}
+	}
+
+	info =
+	    devm_kzalloc(&pdev->dev, sizeof(struct pm80x_rtc_info), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+	info->irq = platform_get_irq(pdev, 0);
+	if (info->irq < 0) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	info->chip = chip;
+	info->map = chip->regmap;
+	if (!info->map) {
+		dev_err(&pdev->dev, "no regmap!\n");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	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 = pm80x_request_irq(chip, info->irq, rtc_update_handler,
+				IRQF_ONESHOT, "rtc", info);
+	if (ret < 0) {
+		dev_err(chip->dev, "Failed to request IRQ: #%d: %d\n",
+			info->irq, ret);
+		goto out;
+	}
+
+	info->rtc_dev->ops = &pm80x_rtc_ops;
+	info->rtc_dev->range_max = U32_MAX;
+
+	ret = devm_rtc_register_device(info->rtc_dev);
+	if (ret)
+		goto out_rtc;
+
+	/*
+	 * enable internal XO instead of internal 3.25MHz clock since it can
+	 * free running in PMIC power-down state.
+	 */
+	regmap_update_bits(info->map, PM800_RTC_CONTROL, PM800_RTC1_USE_XO,
+			   PM800_RTC1_USE_XO);
+
+	/* remember whether this power up is caused by PMIC RTC or not */
+	info->rtc_dev->dev.platform_data = &pdata->rtc_wakeup;
+
+	device_init_wakeup(&pdev->dev, true);
+
+	return 0;
+out_rtc:
+	pm80x_free_irq(chip, info->irq, info);
+out:
+	return ret;
+}
+
+static void pm80x_rtc_remove(struct platform_device *pdev)
+{
+	struct pm80x_rtc_info *info = platform_get_drvdata(pdev);
+	pm80x_free_irq(info->chip, info->irq, info);
+}
+
+static struct platform_driver pm80x_rtc_driver = {
+	.driver = {
+		   .name = "88pm80x-rtc",
+		   .pm = &pm80x_rtc_pm_ops,
+		   },
+	.probe = pm80x_rtc_probe,
+	.remove = pm80x_rtc_remove,
+};
+
+module_platform_driver(pm80x_rtc_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Marvell 88PM80x RTC driver");
+MODULE_AUTHOR("Qiao Zhou <zhouqiao@marvell.com>");
+MODULE_ALIAS("platform:88pm80x-rtc");