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, 193 insertions, 0 deletions

diff --git a/drivers/usb/phy/phy-am335x-control.c b/drivers/usb/phy/phy-am335x-control.c
new file mode 100644
index 000000000..ada508be0
--- /dev/null
+++ b/drivers/usb/phy/phy-am335x-control.c
@@ -0,0 +1,193 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/io.h>
+#include <linux/delay.h>
+#include <linux/usb/otg.h>
+#include "phy-am335x-control.h"
+
+struct am335x_control_usb {
+	struct device *dev;
+	void __iomem *phy_reg;
+	void __iomem *wkup;
+	spinlock_t lock;
+	struct phy_control phy_ctrl;
+};
+
+#define AM335X_USB0_CTRL		0x0
+#define AM335X_USB1_CTRL		0x8
+#define AM335x_USB_WKUP			0x0
+
+#define USBPHY_CM_PWRDN		(1 << 0)
+#define USBPHY_OTG_PWRDN	(1 << 1)
+#define USBPHY_OTGVDET_EN	(1 << 19)
+#define USBPHY_OTGSESSEND_EN	(1 << 20)
+
+#define AM335X_PHY0_WK_EN	(1 << 0)
+#define AM335X_PHY1_WK_EN	(1 << 8)
+
+static void am335x_phy_wkup(struct  phy_control *phy_ctrl, u32 id, bool on)
+{
+	struct am335x_control_usb *usb_ctrl;
+	u32 val;
+	u32 reg;
+
+	usb_ctrl = container_of(phy_ctrl, struct am335x_control_usb, phy_ctrl);
+
+	switch (id) {
+	case 0:
+		reg = AM335X_PHY0_WK_EN;
+		break;
+	case 1:
+		reg = AM335X_PHY1_WK_EN;
+		break;
+	default:
+		WARN_ON(1);
+		return;
+	}
+
+	spin_lock(&usb_ctrl->lock);
+	val = readl(usb_ctrl->wkup);
+
+	if (on)
+		val |= reg;
+	else
+		val &= ~reg;
+
+	writel(val, usb_ctrl->wkup);
+	spin_unlock(&usb_ctrl->lock);
+}
+
+static void am335x_phy_power(struct phy_control *phy_ctrl, u32 id,
+				enum usb_dr_mode dr_mode, bool on)
+{
+	struct am335x_control_usb *usb_ctrl;
+	u32 val;
+	u32 reg;
+
+	usb_ctrl = container_of(phy_ctrl, struct am335x_control_usb, phy_ctrl);
+
+	switch (id) {
+	case 0:
+		reg = AM335X_USB0_CTRL;
+		break;
+	case 1:
+		reg = AM335X_USB1_CTRL;
+		break;
+	default:
+		WARN_ON(1);
+		return;
+	}
+
+	val = readl(usb_ctrl->phy_reg + reg);
+	if (on) {
+		if (dr_mode == USB_DR_MODE_HOST) {
+			val &= ~(USBPHY_CM_PWRDN | USBPHY_OTG_PWRDN |
+					USBPHY_OTGVDET_EN);
+			val |= USBPHY_OTGSESSEND_EN;
+		} else {
+			val &= ~(USBPHY_CM_PWRDN | USBPHY_OTG_PWRDN);
+			val |= USBPHY_OTGVDET_EN | USBPHY_OTGSESSEND_EN;
+		}
+	} else {
+		val |= USBPHY_CM_PWRDN | USBPHY_OTG_PWRDN;
+	}
+
+	writel(val, usb_ctrl->phy_reg + reg);
+
+	/*
+	 * Give the PHY ~1ms to complete the power up operation.
+	 * Tests have shown unstable behaviour if other USB PHY related
+	 * registers are written too shortly after such a transition.
+	 */
+	if (on)
+		mdelay(1);
+}
+
+static const struct phy_control ctrl_am335x = {
+	.phy_power = am335x_phy_power,
+	.phy_wkup = am335x_phy_wkup,
+};
+
+static const struct of_device_id omap_control_usb_id_table[] = {
+	{ .compatible = "ti,am335x-usb-ctrl-module", .data = &ctrl_am335x },
+	{}
+};
+MODULE_DEVICE_TABLE(of, omap_control_usb_id_table);
+
+static struct platform_driver am335x_control_driver;
+static int match(struct device *dev, const void *data)
+{
+	const struct device_node *node = (const struct device_node *)data;
+	return dev->of_node == node &&
+		dev->driver == &am335x_control_driver.driver;
+}
+
+struct phy_control *am335x_get_phy_control(struct device *dev)
+{
+	struct device_node *node;
+	struct am335x_control_usb *ctrl_usb;
+
+	node = of_parse_phandle(dev->of_node, "ti,ctrl_mod", 0);
+	if (!node)
+		return NULL;
+
+	dev = bus_find_device(&platform_bus_type, NULL, node, match);
+	of_node_put(node);
+	if (!dev)
+		return NULL;
+
+	ctrl_usb = dev_get_drvdata(dev);
+	put_device(dev);
+	if (!ctrl_usb)
+		return NULL;
+	return &ctrl_usb->phy_ctrl;
+}
+EXPORT_SYMBOL_GPL(am335x_get_phy_control);
+
+static int am335x_control_usb_probe(struct platform_device *pdev)
+{
+	struct am335x_control_usb *ctrl_usb;
+	const struct of_device_id *of_id;
+	const struct phy_control *phy_ctrl;
+
+	of_id = of_match_node(omap_control_usb_id_table, pdev->dev.of_node);
+	if (!of_id)
+		return -EINVAL;
+
+	phy_ctrl = of_id->data;
+
+	ctrl_usb = devm_kzalloc(&pdev->dev, sizeof(*ctrl_usb), GFP_KERNEL);
+	if (!ctrl_usb)
+		return -ENOMEM;
+
+	ctrl_usb->dev = &pdev->dev;
+
+	ctrl_usb->phy_reg = devm_platform_ioremap_resource_byname(pdev, "phy_ctrl");
+	if (IS_ERR(ctrl_usb->phy_reg))
+		return PTR_ERR(ctrl_usb->phy_reg);
+
+	ctrl_usb->wkup = devm_platform_ioremap_resource_byname(pdev, "wakeup");
+	if (IS_ERR(ctrl_usb->wkup))
+		return PTR_ERR(ctrl_usb->wkup);
+
+	spin_lock_init(&ctrl_usb->lock);
+	ctrl_usb->phy_ctrl = *phy_ctrl;
+
+	dev_set_drvdata(ctrl_usb->dev, ctrl_usb);
+	return 0;
+}
+
+static struct platform_driver am335x_control_driver = {
+	.probe		= am335x_control_usb_probe,
+	.driver		= {
+		.name	= "am335x-control-usb",
+		.of_match_table = omap_control_usb_id_table,
+	},
+};
+
+module_platform_driver(am335x_control_driver);
+MODULE_DESCRIPTION("AM335x USB PHY Control Driver");
+MODULE_LICENSE("GPL v2");