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, 118 insertions, 0 deletions

diff --git a/drivers/usb/phy/phy-keystone.c b/drivers/usb/phy/phy-keystone.c
new file mode 100644
index 000000000..51155c551
--- /dev/null
+++ b/drivers/usb/phy/phy-keystone.c
@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * phy-keystone - USB PHY, talking to dwc3 controller in Keystone.
+ *
+ * Copyright (C) 2013 Texas Instruments Incorporated - https://www.ti.com
+ *
+ * Author: WingMan Kwok <w-kwok2@ti.com>
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/usb/usb_phy_generic.h>
+#include <linux/io.h>
+#include <linux/of.h>
+
+#include "phy-generic.h"
+
+/* USB PHY control register offsets */
+#define USB_PHY_CTL_UTMI		0x0000
+#define USB_PHY_CTL_PIPE		0x0004
+#define USB_PHY_CTL_PARAM_1		0x0008
+#define USB_PHY_CTL_PARAM_2		0x000c
+#define USB_PHY_CTL_CLOCK		0x0010
+#define USB_PHY_CTL_PLL			0x0014
+
+#define PHY_REF_SSP_EN			BIT(29)
+
+struct keystone_usbphy {
+	struct usb_phy_generic	usb_phy_gen;
+	void __iomem			*phy_ctrl;
+};
+
+static inline u32 keystone_usbphy_readl(void __iomem *base, u32 offset)
+{
+	return readl(base + offset);
+}
+
+static inline void keystone_usbphy_writel(void __iomem *base,
+					  u32 offset, u32 value)
+{
+	writel(value, base + offset);
+}
+
+static int keystone_usbphy_init(struct usb_phy *phy)
+{
+	struct keystone_usbphy *k_phy = dev_get_drvdata(phy->dev);
+	u32 val;
+
+	val  = keystone_usbphy_readl(k_phy->phy_ctrl, USB_PHY_CTL_CLOCK);
+	keystone_usbphy_writel(k_phy->phy_ctrl, USB_PHY_CTL_CLOCK,
+				val | PHY_REF_SSP_EN);
+	return 0;
+}
+
+static void keystone_usbphy_shutdown(struct usb_phy *phy)
+{
+	struct keystone_usbphy *k_phy = dev_get_drvdata(phy->dev);
+	u32 val;
+
+	val  = keystone_usbphy_readl(k_phy->phy_ctrl, USB_PHY_CTL_CLOCK);
+	keystone_usbphy_writel(k_phy->phy_ctrl, USB_PHY_CTL_CLOCK,
+				val & ~PHY_REF_SSP_EN);
+}
+
+static int keystone_usbphy_probe(struct platform_device *pdev)
+{
+	struct device		*dev = &pdev->dev;
+	struct keystone_usbphy	*k_phy;
+	int ret;
+
+	k_phy = devm_kzalloc(dev, sizeof(*k_phy), GFP_KERNEL);
+	if (!k_phy)
+		return -ENOMEM;
+
+	k_phy->phy_ctrl = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(k_phy->phy_ctrl))
+		return PTR_ERR(k_phy->phy_ctrl);
+
+	ret = usb_phy_gen_create_phy(dev, &k_phy->usb_phy_gen);
+	if (ret)
+		return ret;
+
+	k_phy->usb_phy_gen.phy.init = keystone_usbphy_init;
+	k_phy->usb_phy_gen.phy.shutdown = keystone_usbphy_shutdown;
+
+	platform_set_drvdata(pdev, k_phy);
+
+	return usb_add_phy_dev(&k_phy->usb_phy_gen.phy);
+}
+
+static void keystone_usbphy_remove(struct platform_device *pdev)
+{
+	struct keystone_usbphy *k_phy = platform_get_drvdata(pdev);
+
+	usb_remove_phy(&k_phy->usb_phy_gen.phy);
+}
+
+static const struct of_device_id keystone_usbphy_ids[] = {
+	{ .compatible = "ti,keystone-usbphy" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, keystone_usbphy_ids);
+
+static struct platform_driver keystone_usbphy_driver = {
+	.probe          = keystone_usbphy_probe,
+	.remove         = keystone_usbphy_remove,
+	.driver         = {
+		.name   = "keystone-usbphy",
+		.of_match_table = keystone_usbphy_ids,
+	},
+};
+
+module_platform_driver(keystone_usbphy_driver);
+
+MODULE_ALIAS("platform:keystone-usbphy");
+MODULE_AUTHOR("Texas Instruments Inc.");
+MODULE_DESCRIPTION("Keystone USB phy driver");
+MODULE_LICENSE("GPL v2");