From a5f7a5bb3b7f28ba7e4fa246775b29a0e5537255 Mon Sep 17 00:00:00 2001 From: Jinke Han Date: Tue, 8 Sep 2026 15:37:42 +0800 Subject: x86/kprobes: Fix crash when probing CS CALL instructions 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) Signed-off-by: Jinke Han Signed-off-by: Ingo Molnar Reviewed-by: Masami Hiramatsu (Google) Acked-by: Yafang Shao Acked-by: Borislav Petkov Cc: Peter Zijlstra Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000 --- drivers/extcon/extcon-gpio.c | 165 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 165 insertions(+) create mode 100644 drivers/extcon/extcon-gpio.c (limited to 'drivers/extcon/extcon-gpio.c') diff --git a/drivers/extcon/extcon-gpio.c b/drivers/extcon/extcon-gpio.c new file mode 100644 index 000000000..4105df74f --- /dev/null +++ b/drivers/extcon/extcon-gpio.c @@ -0,0 +1,165 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * extcon_gpio.c - Single-state GPIO extcon driver based on extcon class + * + * Copyright (C) 2008 Google, Inc. + * Author: Mike Lockwood + * + * Modified by MyungJoo Ham to support extcon + * (originally switch class is supported) + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/** + * struct gpio_extcon_data - A simple GPIO-controlled extcon device state container. + * @edev: Extcon device. + * @work: Work fired by the interrupt. + * @debounce_jiffies: Number of jiffies to wait for the GPIO to stabilize, from the debounce + * value. + * @gpiod: GPIO descriptor for this external connector. + * @extcon_id: The unique id of specific external connector. + * @debounce: Debounce time for GPIO IRQ in ms. + * @check_on_resume: Boolean describing whether to check the state of gpio + * while resuming from sleep. + */ +struct gpio_extcon_data { + struct extcon_dev *edev; + struct delayed_work work; + unsigned long debounce_jiffies; + struct gpio_desc *gpiod; + unsigned int extcon_id; + unsigned long debounce; + bool check_on_resume; +}; + +static void gpio_extcon_work(struct work_struct *work) +{ + int state; + struct gpio_extcon_data *data = + container_of(to_delayed_work(work), struct gpio_extcon_data, + work); + + state = gpiod_get_value_cansleep(data->gpiod); + extcon_set_state_sync(data->edev, data->extcon_id, state); +} + +static irqreturn_t gpio_irq_handler(int irq, void *dev_id) +{ + struct gpio_extcon_data *data = dev_id; + + queue_delayed_work(system_power_efficient_wq, &data->work, + data->debounce_jiffies); + return IRQ_HANDLED; +} + +static int gpio_extcon_probe(struct platform_device *pdev) +{ + struct gpio_extcon_data *data; + struct device *dev = &pdev->dev; + unsigned long irq_flags; + int irq; + int ret; + + data = devm_kzalloc(dev, sizeof(struct gpio_extcon_data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + /* + * FIXME: extcon_id represents the unique identifier of external + * connectors such as EXTCON_USB, EXTCON_DISP_HDMI and so on. extcon_id + * is necessary to register the extcon device. But, it's not yet + * developed to get the extcon id from device-tree or others. + * On later, it have to be solved. + */ + if (data->extcon_id > EXTCON_NONE) + return -EINVAL; + + data->gpiod = devm_gpiod_get(dev, "extcon", GPIOD_IN); + if (IS_ERR(data->gpiod)) + return PTR_ERR(data->gpiod); + irq = gpiod_to_irq(data->gpiod); + if (irq <= 0) + return irq; + + /* + * It is unlikely that this is an acknowledged interrupt that goes + * away after handling, what we are looking for are falling edges + * if the signal is active low, and rising edges if the signal is + * active high. + */ + if (gpiod_is_active_low(data->gpiod)) + irq_flags = IRQF_TRIGGER_FALLING; + else + irq_flags = IRQF_TRIGGER_RISING; + + /* Allocate the memory of extcon devie and register extcon device */ + data->edev = devm_extcon_dev_allocate(dev, &data->extcon_id); + if (IS_ERR(data->edev)) { + dev_err(dev, "failed to allocate extcon device\n"); + return -ENOMEM; + } + + ret = devm_extcon_dev_register(dev, data->edev); + if (ret < 0) + return ret; + + ret = devm_delayed_work_autocancel(dev, &data->work, gpio_extcon_work); + if (ret) + return ret; + + /* + * Request the interrupt of gpio to detect whether external connector + * is attached or detached. + */ + ret = devm_request_any_context_irq(dev, irq, + gpio_irq_handler, irq_flags, + pdev->name, data); + if (ret < 0) + return ret; + + platform_set_drvdata(pdev, data); + /* Perform initial detection */ + gpio_extcon_work(&data->work.work); + + return 0; +} + +#ifdef CONFIG_PM_SLEEP +static int gpio_extcon_resume(struct device *dev) +{ + struct gpio_extcon_data *data; + + data = dev_get_drvdata(dev); + if (data->check_on_resume) + queue_delayed_work(system_power_efficient_wq, + &data->work, data->debounce_jiffies); + + return 0; +} +#endif + +static SIMPLE_DEV_PM_OPS(gpio_extcon_pm_ops, NULL, gpio_extcon_resume); + +static struct platform_driver gpio_extcon_driver = { + .probe = gpio_extcon_probe, + .driver = { + .name = "extcon-gpio", + .pm = &gpio_extcon_pm_ops, + }, +}; + +module_platform_driver(gpio_extcon_driver); + +MODULE_AUTHOR("Mike Lockwood "); +MODULE_DESCRIPTION("GPIO extcon driver"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1