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, 158 insertions, 0 deletions

diff --git a/drivers/phy/nuvoton/Kconfig b/drivers/phy/nuvoton/Kconfig
new file mode 100644
index 000000000..d02cae2db
--- /dev/null
+++ b/drivers/phy/nuvoton/Kconfig
@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# PHY drivers for Nuvoton MA35 platforms
+#
+config PHY_MA35_USB
+	tristate "Nuvoton MA35 USB2.0 PHY driver"
+	depends on ARCH_MA35 || COMPILE_TEST
+	depends on OF
+	select GENERIC_PHY
+	help
+	  Enable this to support the USB2.0 PHY on the Nuvoton MA35
+	  series SoCs.
diff --git a/drivers/phy/nuvoton/Makefile b/drivers/phy/nuvoton/Makefile
new file mode 100644
index 000000000..2937e3921
--- /dev/null
+++ b/drivers/phy/nuvoton/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0
+
+obj-$(CONFIG_PHY_MA35_USB)		+= phy-ma35d1-usb2.o
diff --git a/drivers/phy/nuvoton/phy-ma35d1-usb2.c b/drivers/phy/nuvoton/phy-ma35d1-usb2.c
new file mode 100644
index 000000000..9a459b700
--- /dev/null
+++ b/drivers/phy/nuvoton/phy-ma35d1-usb2.c
@@ -0,0 +1,143 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2024 Nuvoton Technology Corp.
+ */
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/phy/phy.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+/* USB PHY Miscellaneous Control Register */
+#define MA35_SYS_REG_USBPMISCR	0x60
+#define PHY0POR			BIT(0)  /* PHY Power-On Reset Control Bit */
+#define PHY0SUSPEND			BIT(1)  /* PHY Suspend; 0: suspend, 1: operaion */
+#define PHY0COMN			BIT(2)  /* PHY Common Block Power-Down Control */
+#define PHY0DEVCKSTB			BIT(10) /* PHY 60 MHz UTMI clock stable bit */
+
+struct ma35_usb_phy {
+	struct clk *clk;
+	struct device *dev;
+	struct regmap *sysreg;
+};
+
+static int ma35_usb_phy_power_on(struct phy *phy)
+{
+	struct ma35_usb_phy *p_phy = phy_get_drvdata(phy);
+	unsigned int val;
+	int ret;
+
+	ret = clk_prepare_enable(p_phy->clk);
+	if (ret < 0) {
+		dev_err(p_phy->dev, "Failed to enable PHY clock: %d\n", ret);
+		return ret;
+	}
+
+	regmap_read(p_phy->sysreg, MA35_SYS_REG_USBPMISCR, &val);
+	if (val & PHY0SUSPEND) {
+		/*
+		 * USB PHY0 is in operation mode already
+		 * make sure USB PHY 60 MHz UTMI Interface Clock ready
+		 */
+		ret = regmap_read_poll_timeout(p_phy->sysreg, MA35_SYS_REG_USBPMISCR, val,
+						val & PHY0DEVCKSTB, 10, 1000);
+		if (ret == 0)
+			return 0;
+	}
+
+	/*
+	 * reset USB PHY0.
+	 * wait until USB PHY0 60 MHz UTMI Interface Clock ready
+	 */
+	regmap_update_bits(p_phy->sysreg, MA35_SYS_REG_USBPMISCR, 0x7, (PHY0POR | PHY0SUSPEND));
+	udelay(20);
+
+	/* make USB PHY0 enter operation mode */
+	regmap_update_bits(p_phy->sysreg, MA35_SYS_REG_USBPMISCR, 0x7, PHY0SUSPEND);
+
+	/* make sure USB PHY 60 MHz UTMI Interface Clock ready */
+	ret = regmap_read_poll_timeout(p_phy->sysreg, MA35_SYS_REG_USBPMISCR, val,
+					val & PHY0DEVCKSTB, 10, 1000);
+	if (ret == -ETIMEDOUT) {
+		dev_err(p_phy->dev, "Check PHY clock, Timeout: %d\n", ret);
+		clk_disable_unprepare(p_phy->clk);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int ma35_usb_phy_power_off(struct phy *phy)
+{
+	struct ma35_usb_phy *p_phy = phy_get_drvdata(phy);
+
+	clk_disable_unprepare(p_phy->clk);
+	return 0;
+}
+
+static const struct phy_ops ma35_usb_phy_ops = {
+	.power_on = ma35_usb_phy_power_on,
+	.power_off = ma35_usb_phy_power_off,
+	.owner = THIS_MODULE,
+};
+
+static int ma35_usb_phy_probe(struct platform_device *pdev)
+{
+	struct phy_provider *provider;
+	struct ma35_usb_phy *p_phy;
+	struct phy *phy;
+
+	p_phy = devm_kzalloc(&pdev->dev, sizeof(*p_phy), GFP_KERNEL);
+	if (!p_phy)
+		return -ENOMEM;
+
+	p_phy->dev = &pdev->dev;
+	platform_set_drvdata(pdev, p_phy);
+
+	p_phy->sysreg = syscon_regmap_lookup_by_phandle(pdev->dev.of_node, "nuvoton,sys");
+	if (IS_ERR(p_phy->sysreg))
+		return dev_err_probe(&pdev->dev, PTR_ERR(p_phy->sysreg),
+				     "Failed to get SYS registers\n");
+
+	p_phy->clk = of_clk_get(pdev->dev.of_node, 0);
+	if (IS_ERR(p_phy->clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(p_phy->clk),
+				     "failed to find usb_phy clock\n");
+
+	phy = devm_phy_create(&pdev->dev, NULL, &ma35_usb_phy_ops);
+	if (IS_ERR(phy))
+		return dev_err_probe(&pdev->dev, PTR_ERR(phy), "Failed to create PHY\n");
+
+	phy_set_drvdata(phy, p_phy);
+
+	provider = devm_of_phy_provider_register(&pdev->dev, of_phy_simple_xlate);
+	if (IS_ERR(provider))
+		return dev_err_probe(&pdev->dev, PTR_ERR(provider),
+				     "Failed to register PHY provider\n");
+	return 0;
+}
+
+static const struct of_device_id ma35_usb_phy_of_match[] = {
+	{ .compatible = "nuvoton,ma35d1-usb2-phy", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, ma35_usb_phy_of_match);
+
+static struct platform_driver ma35_usb_phy_driver = {
+	.probe		= ma35_usb_phy_probe,
+	.driver	= {
+		.name	= "ma35d1-usb2-phy",
+		.of_match_table = ma35_usb_phy_of_match,
+	},
+};
+module_platform_driver(ma35_usb_phy_driver);
+
+MODULE_DESCRIPTION("Nuvoton ma35d1 USB2.0 PHY driver");
+MODULE_AUTHOR("Hui-Ping Chen <hpchen0nvt@gmail.com>");
+MODULE_LICENSE("GPL");