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, 244 insertions, 0 deletions

diff --git a/drivers/usb/cdns3/cdns3-starfive.c b/drivers/usb/cdns3/cdns3-starfive.c
new file mode 100644
index 000000000..2ff7f2b48
--- /dev/null
+++ b/drivers/usb/cdns3/cdns3-starfive.c
@@ -0,0 +1,244 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * cdns3-starfive.c - StarFive specific Glue layer for Cadence USB Controller
+ *
+ * Copyright (C) 2023 StarFive Technology Co., Ltd.
+ *
+ * Author:	Minda Chen <minda.chen@starfivetech.com>
+ */
+
+#include <linux/bits.h>
+#include <linux/clk.h>
+#include <linux/module.h>
+#include <linux/mfd/syscon.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/of_platform.h>
+#include <linux/reset.h>
+#include <linux/regmap.h>
+#include <linux/usb/otg.h>
+#include "core.h"
+
+#define USB_STRAP_HOST			BIT(17)
+#define USB_STRAP_DEVICE		BIT(18)
+#define USB_STRAP_MASK			GENMASK(18, 16)
+
+#define USB_SUSPENDM_HOST		BIT(19)
+#define USB_SUSPENDM_MASK		BIT(19)
+
+#define USB_MISC_CFG_MASK		GENMASK(23, 20)
+#define USB_SUSPENDM_BYPS		BIT(20)
+#define USB_PLL_EN			BIT(22)
+#define USB_REFCLK_MODE			BIT(23)
+
+struct cdns_starfive {
+	struct device *dev;
+	struct regmap *stg_syscon;
+	struct reset_control *resets;
+	struct clk_bulk_data *clks;
+	int num_clks;
+	u32 stg_usb_mode;
+};
+
+static void cdns_mode_init(struct platform_device *pdev,
+			   struct cdns_starfive *data)
+{
+	enum usb_dr_mode mode;
+
+	regmap_update_bits(data->stg_syscon, data->stg_usb_mode,
+			   USB_MISC_CFG_MASK,
+			   USB_SUSPENDM_BYPS | USB_PLL_EN | USB_REFCLK_MODE);
+
+	/* dr mode setting */
+	mode = usb_get_dr_mode(&pdev->dev);
+
+	switch (mode) {
+	case USB_DR_MODE_HOST:
+		regmap_update_bits(data->stg_syscon,
+				   data->stg_usb_mode,
+				   USB_STRAP_MASK,
+				   USB_STRAP_HOST);
+		regmap_update_bits(data->stg_syscon,
+				   data->stg_usb_mode,
+				   USB_SUSPENDM_MASK,
+				   USB_SUSPENDM_HOST);
+		break;
+
+	case USB_DR_MODE_PERIPHERAL:
+		regmap_update_bits(data->stg_syscon, data->stg_usb_mode,
+				   USB_STRAP_MASK, USB_STRAP_DEVICE);
+		regmap_update_bits(data->stg_syscon, data->stg_usb_mode,
+				   USB_SUSPENDM_MASK, 0);
+		break;
+	default:
+		break;
+	}
+}
+
+static int cdns_clk_rst_init(struct cdns_starfive *data)
+{
+	int ret;
+
+	ret = clk_bulk_prepare_enable(data->num_clks, data->clks);
+	if (ret)
+		return dev_err_probe(data->dev, ret,
+				     "failed to enable clocks\n");
+
+	ret = reset_control_deassert(data->resets);
+	if (ret) {
+		dev_err(data->dev, "failed to reset clocks\n");
+		goto err_clk_init;
+	}
+
+	return ret;
+
+err_clk_init:
+	clk_bulk_disable_unprepare(data->num_clks, data->clks);
+	return ret;
+}
+
+static void cdns_clk_rst_deinit(struct cdns_starfive *data)
+{
+	reset_control_assert(data->resets);
+	clk_bulk_disable_unprepare(data->num_clks, data->clks);
+}
+
+static int cdns_starfive_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct cdns_starfive *data;
+	unsigned int args;
+	int ret;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->dev = dev;
+
+	data->stg_syscon =
+		syscon_regmap_lookup_by_phandle_args(pdev->dev.of_node,
+						     "starfive,stg-syscon", 1, &args);
+
+	if (IS_ERR(data->stg_syscon))
+		return dev_err_probe(dev, PTR_ERR(data->stg_syscon),
+				     "Failed to parse starfive,stg-syscon\n");
+
+	data->stg_usb_mode = args;
+
+	data->num_clks = devm_clk_bulk_get_all(data->dev, &data->clks);
+	if (data->num_clks < 0)
+		return dev_err_probe(data->dev, -ENODEV,
+				     "Failed to get clocks\n");
+
+	data->resets = devm_reset_control_array_get_exclusive(data->dev);
+	if (IS_ERR(data->resets))
+		return dev_err_probe(data->dev, PTR_ERR(data->resets),
+				     "Failed to get resets");
+
+	cdns_mode_init(pdev, data);
+	ret = cdns_clk_rst_init(data);
+	if (ret)
+		return ret;
+
+	ret = of_platform_populate(dev->of_node, NULL, NULL, dev);
+	if (ret) {
+		dev_err(dev, "Failed to create children\n");
+		cdns_clk_rst_deinit(data);
+		return ret;
+	}
+
+	device_set_wakeup_capable(dev, true);
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
+	platform_set_drvdata(pdev, data);
+
+	return 0;
+}
+
+static int cdns_starfive_remove_core(struct device *dev, void *c)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+
+	platform_device_unregister(pdev);
+
+	return 0;
+}
+
+static void cdns_starfive_remove(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct cdns_starfive *data = dev_get_drvdata(dev);
+
+	pm_runtime_get_sync(dev);
+	device_for_each_child(dev, NULL, cdns_starfive_remove_core);
+
+	pm_runtime_disable(dev);
+	pm_runtime_put_noidle(dev);
+	cdns_clk_rst_deinit(data);
+	platform_set_drvdata(pdev, NULL);
+}
+
+#ifdef CONFIG_PM
+static int cdns_starfive_runtime_resume(struct device *dev)
+{
+	struct cdns_starfive *data = dev_get_drvdata(dev);
+
+	return clk_bulk_prepare_enable(data->num_clks, data->clks);
+}
+
+static int cdns_starfive_runtime_suspend(struct device *dev)
+{
+	struct cdns_starfive *data = dev_get_drvdata(dev);
+
+	clk_bulk_disable_unprepare(data->num_clks, data->clks);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int cdns_starfive_resume(struct device *dev)
+{
+	struct cdns_starfive *data = dev_get_drvdata(dev);
+
+	return cdns_clk_rst_init(data);
+}
+
+static int cdns_starfive_suspend(struct device *dev)
+{
+	struct cdns_starfive *data = dev_get_drvdata(dev);
+
+	cdns_clk_rst_deinit(data);
+
+	return 0;
+}
+#endif
+#endif
+
+static const struct dev_pm_ops cdns_starfive_pm_ops = {
+	SET_RUNTIME_PM_OPS(cdns_starfive_runtime_suspend,
+			   cdns_starfive_runtime_resume, NULL)
+	SET_SYSTEM_SLEEP_PM_OPS(cdns_starfive_suspend, cdns_starfive_resume)
+};
+
+static const struct of_device_id cdns_starfive_of_match[] = {
+	{ .compatible = "starfive,jh7110-usb", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, cdns_starfive_of_match);
+
+static struct platform_driver cdns_starfive_driver = {
+	.probe		= cdns_starfive_probe,
+	.remove		= cdns_starfive_remove,
+	.driver		= {
+		.name	= "cdns3-starfive",
+		.of_match_table	= cdns_starfive_of_match,
+		.pm	= &cdns_starfive_pm_ops,
+	},
+};
+module_platform_driver(cdns_starfive_driver);
+
+MODULE_ALIAS("platform:cdns3-starfive");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Cadence USB3 StarFive Glue Layer");