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, 439 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-jz4740.c b/drivers/rtc/rtc-jz4740.c
new file mode 100644
index 000000000..11fce47be
--- /dev/null
+++ b/drivers/rtc/rtc-jz4740.c
@@ -0,0 +1,439 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ *  Copyright (C) 2009-2010, Lars-Peter Clausen <lars@metafoo.de>
+ *  Copyright (C) 2010, Paul Cercueil <paul@crapouillou.net>
+ *	 JZ4740 SoC RTC driver
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm_wakeirq.h>
+#include <linux/property.h>
+#include <linux/reboot.h>
+#include <linux/rtc.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+#define JZ_REG_RTC_CTRL		0x00
+#define JZ_REG_RTC_SEC		0x04
+#define JZ_REG_RTC_SEC_ALARM	0x08
+#define JZ_REG_RTC_REGULATOR	0x0C
+#define JZ_REG_RTC_HIBERNATE	0x20
+#define JZ_REG_RTC_WAKEUP_FILTER	0x24
+#define JZ_REG_RTC_RESET_COUNTER	0x28
+#define JZ_REG_RTC_SCRATCHPAD	0x34
+#define JZ_REG_RTC_CKPCR	0x40
+
+/* The following are present on the jz4780 */
+#define JZ_REG_RTC_WENR	0x3C
+#define JZ_RTC_WENR_WEN	BIT(31)
+
+#define JZ_RTC_CTRL_WRDY	BIT(7)
+#define JZ_RTC_CTRL_1HZ		BIT(6)
+#define JZ_RTC_CTRL_1HZ_IRQ	BIT(5)
+#define JZ_RTC_CTRL_AF		BIT(4)
+#define JZ_RTC_CTRL_AF_IRQ	BIT(3)
+#define JZ_RTC_CTRL_AE		BIT(2)
+#define JZ_RTC_CTRL_ENABLE	BIT(0)
+
+/* Magic value to enable writes on jz4780 */
+#define JZ_RTC_WENR_MAGIC	0xA55A
+
+#define JZ_RTC_WAKEUP_FILTER_MASK	0x0000FFE0
+#define JZ_RTC_RESET_COUNTER_MASK	0x00000FE0
+
+#define JZ_RTC_CKPCR_CK32PULL_DIS	BIT(4)
+#define JZ_RTC_CKPCR_CK32CTL_EN		(BIT(2) | BIT(1))
+
+enum jz4740_rtc_type {
+	ID_JZ4740,
+	ID_JZ4760,
+	ID_JZ4780,
+};
+
+struct jz4740_rtc {
+	void __iomem *base;
+	enum jz4740_rtc_type type;
+
+	struct rtc_device *rtc;
+
+	struct clk_hw clk32k;
+
+	spinlock_t lock;
+};
+
+static struct device *dev_for_power_off;
+
+static inline uint32_t jz4740_rtc_reg_read(struct jz4740_rtc *rtc, size_t reg)
+{
+	return readl(rtc->base + reg);
+}
+
+static int jz4740_rtc_wait_write_ready(struct jz4740_rtc *rtc)
+{
+	uint32_t ctrl;
+
+	return readl_poll_timeout(rtc->base + JZ_REG_RTC_CTRL, ctrl,
+				  ctrl & JZ_RTC_CTRL_WRDY, 0, 1000);
+}
+
+static inline int jz4780_rtc_enable_write(struct jz4740_rtc *rtc)
+{
+	uint32_t ctrl;
+	int ret;
+
+	ret = jz4740_rtc_wait_write_ready(rtc);
+	if (ret != 0)
+		return ret;
+
+	writel(JZ_RTC_WENR_MAGIC, rtc->base + JZ_REG_RTC_WENR);
+
+	return readl_poll_timeout(rtc->base + JZ_REG_RTC_WENR, ctrl,
+				  ctrl & JZ_RTC_WENR_WEN, 0, 1000);
+}
+
+static inline int jz4740_rtc_reg_write(struct jz4740_rtc *rtc, size_t reg,
+	uint32_t val)
+{
+	int ret = 0;
+
+	if (rtc->type >= ID_JZ4760)
+		ret = jz4780_rtc_enable_write(rtc);
+	if (ret == 0)
+		ret = jz4740_rtc_wait_write_ready(rtc);
+	if (ret == 0)
+		writel(val, rtc->base + reg);
+
+	return ret;
+}
+
+static int jz4740_rtc_ctrl_set_bits(struct jz4740_rtc *rtc, uint32_t mask,
+	bool set)
+{
+	int ret;
+	unsigned long flags;
+	uint32_t ctrl;
+
+	spin_lock_irqsave(&rtc->lock, flags);
+
+	ctrl = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_CTRL);
+
+	/* Don't clear interrupt flags by accident */
+	ctrl |= JZ_RTC_CTRL_1HZ | JZ_RTC_CTRL_AF;
+
+	if (set)
+		ctrl |= mask;
+	else
+		ctrl &= ~mask;
+
+	ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_CTRL, ctrl);
+
+	spin_unlock_irqrestore(&rtc->lock, flags);
+
+	return ret;
+}
+
+static int jz4740_rtc_read_time(struct device *dev, struct rtc_time *time)
+{
+	struct jz4740_rtc *rtc = dev_get_drvdata(dev);
+	uint32_t secs, secs2;
+	int timeout = 5;
+
+	if (jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SCRATCHPAD) != 0x12345678)
+		return -EINVAL;
+
+	/* If the seconds register is read while it is updated, it can contain a
+	 * bogus value. This can be avoided by making sure that two consecutive
+	 * reads have the same value.
+	 */
+	secs = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SEC);
+	secs2 = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SEC);
+
+	while (secs != secs2 && --timeout) {
+		secs = secs2;
+		secs2 = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SEC);
+	}
+
+	if (timeout == 0)
+		return -EIO;
+
+	rtc_time64_to_tm(secs, time);
+
+	return 0;
+}
+
+static int jz4740_rtc_set_time(struct device *dev, struct rtc_time *time)
+{
+	struct jz4740_rtc *rtc = dev_get_drvdata(dev);
+	int ret;
+
+	ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SEC, rtc_tm_to_time64(time));
+	if (ret)
+		return ret;
+
+	return jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SCRATCHPAD, 0x12345678);
+}
+
+static int jz4740_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct jz4740_rtc *rtc = dev_get_drvdata(dev);
+	uint32_t secs;
+	uint32_t ctrl;
+
+	secs = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SEC_ALARM);
+
+	ctrl = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_CTRL);
+
+	alrm->enabled = !!(ctrl & JZ_RTC_CTRL_AE);
+	alrm->pending = !!(ctrl & JZ_RTC_CTRL_AF);
+
+	rtc_time64_to_tm(secs, &alrm->time);
+
+	return 0;
+}
+
+static int jz4740_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	int ret;
+	struct jz4740_rtc *rtc = dev_get_drvdata(dev);
+	uint32_t secs = lower_32_bits(rtc_tm_to_time64(&alrm->time));
+
+	ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SEC_ALARM, secs);
+	if (!ret)
+		ret = jz4740_rtc_ctrl_set_bits(rtc,
+			JZ_RTC_CTRL_AE | JZ_RTC_CTRL_AF_IRQ, alrm->enabled);
+
+	return ret;
+}
+
+static int jz4740_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
+{
+	struct jz4740_rtc *rtc = dev_get_drvdata(dev);
+	return jz4740_rtc_ctrl_set_bits(rtc, JZ_RTC_CTRL_AF_IRQ, enable);
+}
+
+static const struct rtc_class_ops jz4740_rtc_ops = {
+	.read_time	= jz4740_rtc_read_time,
+	.set_time	= jz4740_rtc_set_time,
+	.read_alarm	= jz4740_rtc_read_alarm,
+	.set_alarm	= jz4740_rtc_set_alarm,
+	.alarm_irq_enable = jz4740_rtc_alarm_irq_enable,
+};
+
+static irqreturn_t jz4740_rtc_irq(int irq, void *data)
+{
+	struct jz4740_rtc *rtc = data;
+	uint32_t ctrl;
+	unsigned long events = 0;
+
+	ctrl = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_CTRL);
+
+	if (ctrl & JZ_RTC_CTRL_1HZ)
+		events |= (RTC_UF | RTC_IRQF);
+
+	if (ctrl & JZ_RTC_CTRL_AF)
+		events |= (RTC_AF | RTC_IRQF);
+
+	rtc_update_irq(rtc->rtc, 1, events);
+
+	jz4740_rtc_ctrl_set_bits(rtc, JZ_RTC_CTRL_1HZ | JZ_RTC_CTRL_AF, false);
+
+	return IRQ_HANDLED;
+}
+
+static void jz4740_rtc_poweroff(struct device *dev)
+{
+	struct jz4740_rtc *rtc = dev_get_drvdata(dev);
+	jz4740_rtc_reg_write(rtc, JZ_REG_RTC_HIBERNATE, 1);
+}
+
+static void jz4740_rtc_power_off(void)
+{
+	jz4740_rtc_poweroff(dev_for_power_off);
+	kernel_halt();
+}
+
+static const struct of_device_id jz4740_rtc_of_match[] = {
+	{ .compatible = "ingenic,jz4740-rtc", .data = (void *)ID_JZ4740 },
+	{ .compatible = "ingenic,jz4760-rtc", .data = (void *)ID_JZ4760 },
+	{ .compatible = "ingenic,jz4770-rtc", .data = (void *)ID_JZ4780 },
+	{ .compatible = "ingenic,jz4780-rtc", .data = (void *)ID_JZ4780 },
+	{},
+};
+MODULE_DEVICE_TABLE(of, jz4740_rtc_of_match);
+
+static void jz4740_rtc_set_wakeup_params(struct jz4740_rtc *rtc,
+					 struct device_node *np,
+					 unsigned long rate)
+{
+	unsigned long wakeup_ticks, reset_ticks;
+	unsigned int min_wakeup_pin_assert_time = 60; /* Default: 60ms */
+	unsigned int reset_pin_assert_time = 100; /* Default: 100ms */
+
+	of_property_read_u32(np, "ingenic,reset-pin-assert-time-ms",
+			     &reset_pin_assert_time);
+	of_property_read_u32(np, "ingenic,min-wakeup-pin-assert-time-ms",
+			     &min_wakeup_pin_assert_time);
+
+	/*
+	 * Set minimum wakeup pin assertion time: 100 ms.
+	 * Range is 0 to 2 sec if RTC is clocked at 32 kHz.
+	 */
+	wakeup_ticks = (min_wakeup_pin_assert_time * rate) / 1000;
+	if (wakeup_ticks < JZ_RTC_WAKEUP_FILTER_MASK)
+		wakeup_ticks &= JZ_RTC_WAKEUP_FILTER_MASK;
+	else
+		wakeup_ticks = JZ_RTC_WAKEUP_FILTER_MASK;
+	jz4740_rtc_reg_write(rtc, JZ_REG_RTC_WAKEUP_FILTER, wakeup_ticks);
+
+	/*
+	 * Set reset pin low-level assertion time after wakeup: 60 ms.
+	 * Range is 0 to 125 ms if RTC is clocked at 32 kHz.
+	 */
+	reset_ticks = (reset_pin_assert_time * rate) / 1000;
+	if (reset_ticks < JZ_RTC_RESET_COUNTER_MASK)
+		reset_ticks &= JZ_RTC_RESET_COUNTER_MASK;
+	else
+		reset_ticks = JZ_RTC_RESET_COUNTER_MASK;
+	jz4740_rtc_reg_write(rtc, JZ_REG_RTC_RESET_COUNTER, reset_ticks);
+}
+
+static int jz4740_rtc_clk32k_enable(struct clk_hw *hw)
+{
+	struct jz4740_rtc *rtc = container_of(hw, struct jz4740_rtc, clk32k);
+
+	return jz4740_rtc_reg_write(rtc, JZ_REG_RTC_CKPCR,
+				    JZ_RTC_CKPCR_CK32PULL_DIS |
+				    JZ_RTC_CKPCR_CK32CTL_EN);
+}
+
+static void jz4740_rtc_clk32k_disable(struct clk_hw *hw)
+{
+	struct jz4740_rtc *rtc = container_of(hw, struct jz4740_rtc, clk32k);
+
+	jz4740_rtc_reg_write(rtc, JZ_REG_RTC_CKPCR, 0);
+}
+
+static int jz4740_rtc_clk32k_is_enabled(struct clk_hw *hw)
+{
+	struct jz4740_rtc *rtc = container_of(hw, struct jz4740_rtc, clk32k);
+	u32 ckpcr;
+
+	ckpcr = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_CKPCR);
+
+	return !!(ckpcr & JZ_RTC_CKPCR_CK32CTL_EN);
+}
+
+static const struct clk_ops jz4740_rtc_clk32k_ops = {
+	.enable = jz4740_rtc_clk32k_enable,
+	.disable = jz4740_rtc_clk32k_disable,
+	.is_enabled = jz4740_rtc_clk32k_is_enabled,
+};
+
+static int jz4740_rtc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	struct jz4740_rtc *rtc;
+	unsigned long rate;
+	struct clk *clk;
+	int ret, irq;
+
+	rtc = devm_kzalloc(dev, sizeof(*rtc), GFP_KERNEL);
+	if (!rtc)
+		return -ENOMEM;
+
+	rtc->type = (uintptr_t)device_get_match_data(dev);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	rtc->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(rtc->base))
+		return PTR_ERR(rtc->base);
+
+	clk = devm_clk_get_enabled(dev, "rtc");
+	if (IS_ERR(clk))
+		return dev_err_probe(dev, PTR_ERR(clk), "Failed to get RTC clock\n");
+
+	spin_lock_init(&rtc->lock);
+
+	platform_set_drvdata(pdev, rtc);
+
+	device_init_wakeup(dev, true);
+
+	ret = dev_pm_set_wake_irq(dev, irq);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to set wake irq\n");
+
+	rtc->rtc = devm_rtc_allocate_device(dev);
+	if (IS_ERR(rtc->rtc))
+		return dev_err_probe(dev, PTR_ERR(rtc->rtc),
+				     "Failed to allocate rtc device\n");
+
+	rtc->rtc->ops = &jz4740_rtc_ops;
+	rtc->rtc->range_max = U32_MAX;
+
+	rate = clk_get_rate(clk);
+	jz4740_rtc_set_wakeup_params(rtc, np, rate);
+
+	/* Each 1 Hz pulse should happen after (rate) ticks */
+	jz4740_rtc_reg_write(rtc, JZ_REG_RTC_REGULATOR, rate - 1);
+
+	ret = devm_rtc_register_device(rtc->rtc);
+	if (ret)
+		return ret;
+
+	ret = devm_request_irq(dev, irq, jz4740_rtc_irq, 0,
+			       pdev->name, rtc);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to request rtc irq\n");
+
+	if (of_device_is_system_power_controller(np)) {
+		dev_for_power_off = dev;
+
+		if (!pm_power_off)
+			pm_power_off = jz4740_rtc_power_off;
+		else
+			dev_warn(dev, "Poweroff handler already present!\n");
+	}
+
+	if (device_property_present(dev, "#clock-cells")) {
+		rtc->clk32k.init = CLK_HW_INIT_HW("clk32k", __clk_get_hw(clk),
+						  &jz4740_rtc_clk32k_ops, 0);
+
+		ret = devm_clk_hw_register(dev, &rtc->clk32k);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "Unable to register clk32k clock\n");
+
+		ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get,
+						  &rtc->clk32k);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "Unable to register clk32k clock provider\n");
+	}
+
+	return 0;
+}
+
+static struct platform_driver jz4740_rtc_driver = {
+	.probe	 = jz4740_rtc_probe,
+	.driver	 = {
+		.name  = "jz4740-rtc",
+		.of_match_table = jz4740_rtc_of_match,
+	},
+};
+
+module_platform_driver(jz4740_rtc_driver);
+
+MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("RTC driver for the JZ4740 SoC\n");