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

3 files changed, 300 insertions, 0 deletions

diff --git a/drivers/phy/canaan/Kconfig b/drivers/phy/canaan/Kconfig
new file mode 100644
index 000000000..1ff883184
--- /dev/null
+++ b/drivers/phy/canaan/Kconfig
@@ -0,0 +1,14 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Phy drivers for Canaan platforms
+#
+config PHY_CANAAN_USB
+	tristate "Canaan USB2 PHY Driver"
+	depends on (ARCH_CANAAN || COMPILE_TEST) && OF
+	select GENERIC_PHY
+	help
+	Enable this driver to support the USB 2.0 PHY controller
+	on Canaan K230 RISC-V SoCs. This PHY controller
+	provides physical layer functionality for USB 2.0 devices.
+	If you have a Canaan K230 board and need USB 2.0 support,
+	say Y or M here.
diff --git a/drivers/phy/canaan/Makefile b/drivers/phy/canaan/Makefile
new file mode 100644
index 000000000..d73857ba2
--- /dev/null
+++ b/drivers/phy/canaan/Makefile
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_PHY_CANAAN_USB)		+= phy-k230-usb.o
diff --git a/drivers/phy/canaan/phy-k230-usb.c b/drivers/phy/canaan/phy-k230-usb.c
new file mode 100644
index 000000000..52dad35fc
--- /dev/null
+++ b/drivers/phy/canaan/phy-k230-usb.c
@@ -0,0 +1,284 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Canaan usb PHY driver
+ *
+ * Copyright (C) 2026 Jiayu Du <jiayu.riscv@isrc.iscas.ac.cn>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/io.h>
+#include <linux/of_address.h>
+#include <linux/phy/phy.h>
+#include <linux/platform_device.h>
+
+#define MAX_PHYS		2
+
+/* Register offsets within the HiSysConfig system controller */
+#define K230_USB0_TEST_REG_BASE     0x70
+#define K230_USB0_CTL_REG_BASE      0xb0
+#define K230_USB1_TEST_REG_BASE     0x90
+#define K230_USB1_CTL_REG_BASE      0xb8
+
+/* Relative offsets within each PHY's control/test block */
+#define CTL0_OFFSET		0x00
+#define CTL1_OFFSET		0x04
+#define TEST_CTL3_OFFSET	0x0c
+
+/* Bit definitions for TEST_CTL3 */
+#define USB_IDPULLUP0		BIT(4)
+#define USB_DMPULLDOWN0		BIT(8)
+#define USB_DPPULLDOWN0		BIT(9)
+
+/* USB control register 0 in HiSysConfig system controller */
+/* PLL Integral Path Tune */
+#define USB_CTL0_PLLITUNE_MASK		GENMASK(23, 22)
+
+/* PLL Proportional Path Tune */
+#define USB_CTL0_PLLPTUNE_MASK		GENMASK(21, 18)
+
+/* PLL Bandwidth Adjustment */
+#define USB_CTL0_PLLBTUNE_MASK		GENMASK(17, 17)
+
+/* VReg18 Bypass Control */
+#define USB_CTL0_VREGBYPASS_MASK	GENMASK(16, 16)
+
+/* Retention Mode Enable */
+#define USB_CTL0_RETENABLEN_MASK	GENMASK(15, 15)
+
+/* Reserved Request Input */
+#define USB_CTL0_RESREQIN_MASK		GENMASK(14, 14)
+
+/* External VBUS Valid Select */
+#define USB_CTL0_VBUSVLDEXTSEL0_MASK	GENMASK(13, 13)
+
+/* OTG Block Disable Control */
+#define USB_CTL0_OTGDISABLE0_MASK	GENMASK(12, 12)
+
+/* Drive VBUS Enable */
+#define USB_CTL0_DRVVBUS0_MASK		GENMASK(11, 11)
+
+/* Autoresume Mode Enable */
+#define USB_CTL0_AUTORSMENB0_MASK	GENMASK(10, 10)
+
+/* HS Transceiver Asynchronous Control */
+#define USB_CTL0_HSXCVREXTCTL0_MASK	GENMASK(9, 9)
+
+/* USB 1.1 Transmit Data */
+#define USB_CTL0_FSDATAEXT0_MASK	GENMASK(8, 8)
+
+/* USB 1.1 SE0 Generation */
+#define USB_CTL0_FSSE0EXT0_MASK		GENMASK(7, 7)
+
+/* USB 1.1 Data Enable */
+#define USB_CTL0_TXENABLEN0_MASK	GENMASK(6, 6)
+
+/* Disconnect Threshold */
+#define USB_CTL0_COMPDISTUNE0_MASK	GENMASK(5, 3)
+
+/* Squelch Threshold */
+#define USB_CTL0_SQRXTUNE0_MASK		GENMASK(2, 0)
+
+/* USB control register 1 in HiSysConfig system controller */
+/* Data Detect Voltage */
+#define USB_CTL1_VDATREFTUNE0_MASK	GENMASK(23, 22)
+
+/* VBUS Valid Threshold */
+#define USB_CTL1_OTGTUNE0_MASK		GENMASK(21, 19)
+
+/* Transmitter High-Speed Crossover */
+#define USB_CTL1_TXHSXVTUNE0_MASK	GENMASK(18, 17)
+
+/* FS/LS Source Impedance */
+#define USB_CTL1_TXFSLSTUNE0_MASK	GENMASK(16, 13)
+
+/* HS DC Voltage Level */
+#define USB_CTL1_TXVREFTUNE0_MASK	GENMASK(12, 9)
+
+/* HS Transmitter Rise/Fall Time */
+#define USB_CTL1_TXRISETUNE0_MASK	GENMASK(8, 7)
+
+/* USB Source Impedance */
+#define USB_CTL1_TXRESTUNE0_MASK	GENMASK(6, 5)
+
+/* HS Transmitter Pre-Emphasis Current Control */
+#define USB_CTL1_TXPREEMPAMPTUNE0_MASK	GENMASK(4, 3)
+
+/* HS Transmitter Pre-Emphasis Duration Control */
+#define USB_CTL1_TXPREEMPPULSETUNE0_MASK	GENMASK(2, 2)
+
+/* charging detection */
+#define USB_CTL1_CHRGSRCPUENB0_MASK	GENMASK(1, 0)
+
+#define K230_PHY_CTL0_VAL \
+( \
+	FIELD_PREP(USB_CTL0_PLLITUNE_MASK, 0x0) | \
+	FIELD_PREP(USB_CTL0_PLLPTUNE_MASK, 0xc) | \
+	FIELD_PREP(USB_CTL0_PLLBTUNE_MASK, 0x1) | \
+	FIELD_PREP(USB_CTL0_VREGBYPASS_MASK, 0x1) | \
+	FIELD_PREP(USB_CTL0_RETENABLEN_MASK, 0x1) | \
+	FIELD_PREP(USB_CTL0_RESREQIN_MASK, 0x0) | \
+	FIELD_PREP(USB_CTL0_VBUSVLDEXTSEL0_MASK, 0x0) | \
+	FIELD_PREP(USB_CTL0_OTGDISABLE0_MASK, 0x0) | \
+	FIELD_PREP(USB_CTL0_DRVVBUS0_MASK, 0x1) | \
+	FIELD_PREP(USB_CTL0_AUTORSMENB0_MASK, 0x0) | \
+	FIELD_PREP(USB_CTL0_HSXCVREXTCTL0_MASK, 0x0) | \
+	FIELD_PREP(USB_CTL0_FSDATAEXT0_MASK, 0x0) | \
+	FIELD_PREP(USB_CTL0_FSSE0EXT0_MASK, 0x0) | \
+	FIELD_PREP(USB_CTL0_TXENABLEN0_MASK, 0x0) | \
+	FIELD_PREP(USB_CTL0_COMPDISTUNE0_MASK, 0x3) | \
+	FIELD_PREP(USB_CTL0_SQRXTUNE0_MASK, 0x3) \
+)
+
+#define K230_PHY_CTL1_VAL \
+( \
+	FIELD_PREP(USB_CTL1_VDATREFTUNE0_MASK, 0x1) | \
+	FIELD_PREP(USB_CTL1_OTGTUNE0_MASK, 0x3) | \
+	FIELD_PREP(USB_CTL1_TXHSXVTUNE0_MASK, 0x3) | \
+	FIELD_PREP(USB_CTL1_TXFSLSTUNE0_MASK, 0x3) | \
+	FIELD_PREP(USB_CTL1_TXVREFTUNE0_MASK, 0x3) | \
+	FIELD_PREP(USB_CTL1_TXRISETUNE0_MASK, 0x1) | \
+	FIELD_PREP(USB_CTL1_TXRESTUNE0_MASK, 0x1) | \
+	FIELD_PREP(USB_CTL1_TXPREEMPAMPTUNE0_MASK, 0x0) | \
+	FIELD_PREP(USB_CTL1_TXPREEMPPULSETUNE0_MASK, 0x0) | \
+	FIELD_PREP(USB_CTL1_CHRGSRCPUENB0_MASK, 0x0) \
+)
+
+struct k230_usb_phy_instance {
+	struct k230_usb_phy_global *global;
+	struct phy *phy;
+	u32 test_offset;
+	u32 ctl_offset;
+	int index;
+};
+
+struct k230_usb_phy_global {
+	struct k230_usb_phy_instance phys[MAX_PHYS];
+	void __iomem *base;
+};
+
+static int k230_usb_phy_power_on(struct phy *phy)
+{
+	struct k230_usb_phy_instance *inst = phy_get_drvdata(phy);
+	struct k230_usb_phy_global *global = inst->global;
+	void __iomem *base = global->base;
+	u32 val;
+
+	/* Apply recommended settings */
+	writel(K230_PHY_CTL0_VAL, base + inst->ctl_offset + CTL0_OFFSET);
+	writel(K230_PHY_CTL1_VAL, base + inst->ctl_offset + CTL1_OFFSET);
+
+	/* Configure test register (pull-ups/pull-downs) */
+	val = readl(base + inst->test_offset + TEST_CTL3_OFFSET);
+	val |= USB_IDPULLUP0;
+
+	if (inst->index == 1)
+		val |= (USB_DMPULLDOWN0 | USB_DPPULLDOWN0);
+	else
+		val &= ~(USB_DMPULLDOWN0 | USB_DPPULLDOWN0);
+
+	writel(val, base + inst->test_offset + TEST_CTL3_OFFSET);
+
+	return 0;
+}
+
+static int k230_usb_phy_power_off(struct phy *phy)
+{
+	struct k230_usb_phy_instance *inst = phy_get_drvdata(phy);
+	struct k230_usb_phy_global *global = inst->global;
+	void __iomem *base = global->base;
+	u32 val;
+
+	val = readl(base + inst->test_offset + TEST_CTL3_OFFSET);
+	val &= ~(USB_DMPULLDOWN0 | USB_DPPULLDOWN0);
+	writel(val, base + inst->test_offset + TEST_CTL3_OFFSET);
+
+	return 0;
+}
+
+static const struct phy_ops k230_usb_phy_ops = {
+	.power_on = k230_usb_phy_power_on,
+	.power_off = k230_usb_phy_power_off,
+	.owner = THIS_MODULE,
+};
+
+static struct phy *k230_usb_phy_xlate(struct device *dev,
+				      const struct of_phandle_args *args)
+{
+	struct k230_usb_phy_global *global = dev_get_drvdata(dev);
+	unsigned int idx = args->args[0];
+
+	if (idx >= MAX_PHYS)
+		return ERR_PTR(-EINVAL);
+
+	return global->phys[idx].phy;
+}
+
+static int k230_usb_phy_probe(struct platform_device *pdev)
+{
+	struct k230_usb_phy_global *global;
+	struct device *dev = &pdev->dev;
+	struct phy_provider *provider;
+	int i;
+
+	global = devm_kzalloc(dev, sizeof(*global), GFP_KERNEL);
+	if (!global)
+		return -ENOMEM;
+	dev_set_drvdata(dev, global);
+
+	global->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(global->base))
+		return dev_err_probe(dev, PTR_ERR(global->base),
+				     "failed to map registers\n");
+
+	static const struct {
+		u32 test_offset;
+		u32 ctl_offset;
+	} phy_reg_info[MAX_PHYS] = {
+		[0] = { K230_USB0_TEST_REG_BASE, K230_USB0_CTL_REG_BASE },
+		[1] = { K230_USB1_TEST_REG_BASE, K230_USB1_CTL_REG_BASE },
+	};
+
+	for (i = 0; i < MAX_PHYS; i++) {
+		struct k230_usb_phy_instance *inst = &global->phys[i];
+		struct phy *phy;
+
+		inst->global = global;
+		inst->index = i;
+		inst->test_offset = phy_reg_info[i].test_offset;
+		inst->ctl_offset  = phy_reg_info[i].ctl_offset;
+
+		phy = devm_phy_create(dev, NULL, &k230_usb_phy_ops);
+		if (IS_ERR(phy)) {
+			dev_err(dev, "failed to create phy%d\n", i);
+			return PTR_ERR(phy);
+		}
+
+		phy_set_drvdata(phy, inst);
+		inst->phy = phy;
+	}
+
+	provider = devm_of_phy_provider_register(dev, k230_usb_phy_xlate);
+	if (IS_ERR(provider))
+		return PTR_ERR(provider);
+
+	return 0;
+}
+
+static const struct of_device_id k230_usb_phy_of_match[] = {
+	{ .compatible = "canaan,k230-usb-phy" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, k230_usb_phy_of_match);
+
+static struct platform_driver k230_usb_phy_driver = {
+	.probe = k230_usb_phy_probe,
+	.driver = {
+		.name = "k230-usb-phy",
+		.of_match_table = k230_usb_phy_of_match,
+	},
+};
+module_platform_driver(k230_usb_phy_driver);
+
+MODULE_DESCRIPTION("Canaan Kendryte K230 USB 2.0 PHY driver");
+MODULE_AUTHOR("Jiayu Du <jiayu.riscv@isrc.iscas.ac.cn>");
+MODULE_LICENSE("GPL");