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/input/touchscreen/htcpen.c | 243 +++++++++++++++++++++++++++++++++++++ 1 file changed, 243 insertions(+) create mode 100644 drivers/input/touchscreen/htcpen.c (limited to 'drivers/input/touchscreen/htcpen.c') diff --git a/drivers/input/touchscreen/htcpen.c b/drivers/input/touchscreen/htcpen.c new file mode 100644 index 000000000..056ba7608 --- /dev/null +++ b/drivers/input/touchscreen/htcpen.c @@ -0,0 +1,243 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * HTC Shift touchscreen driver + * + * Copyright (C) 2008 Pau Oliva Fora + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +MODULE_AUTHOR("Pau Oliva Fora "); +MODULE_DESCRIPTION("HTC Shift touchscreen driver"); +MODULE_LICENSE("GPL"); + +#define HTCPEN_PORT_IRQ_CLEAR 0x068 +#define HTCPEN_PORT_INIT 0x06c +#define HTCPEN_PORT_INDEX 0x0250 +#define HTCPEN_PORT_DATA 0x0251 +#define HTCPEN_IRQ 3 + +#define DEVICE_ENABLE 0xa2 +#define DEVICE_DISABLE 0xa3 + +#define X_INDEX 3 +#define Y_INDEX 5 +#define TOUCH_INDEX 0xb +#define LSB_XY_INDEX 0xc +#define X_AXIS_MAX 2040 +#define Y_AXIS_MAX 2040 + +static bool invert_x; +module_param(invert_x, bool, 0644); +MODULE_PARM_DESC(invert_x, "If set, X axis is inverted"); +static bool invert_y; +module_param(invert_y, bool, 0644); +MODULE_PARM_DESC(invert_y, "If set, Y axis is inverted"); + +static irqreturn_t htcpen_interrupt(int irq, void *handle) +{ + struct input_dev *htcpen_dev = handle; + unsigned short x, y, xy; + + /* 0 = press; 1 = release */ + outb_p(TOUCH_INDEX, HTCPEN_PORT_INDEX); + + if (inb_p(HTCPEN_PORT_DATA)) { + input_report_key(htcpen_dev, BTN_TOUCH, 0); + } else { + outb_p(X_INDEX, HTCPEN_PORT_INDEX); + x = inb_p(HTCPEN_PORT_DATA); + + outb_p(Y_INDEX, HTCPEN_PORT_INDEX); + y = inb_p(HTCPEN_PORT_DATA); + + outb_p(LSB_XY_INDEX, HTCPEN_PORT_INDEX); + xy = inb_p(HTCPEN_PORT_DATA); + + /* get high resolution value of X and Y using LSB */ + x = X_AXIS_MAX - ((x * 8) + ((xy >> 4) & 0xf)); + y = (y * 8) + (xy & 0xf); + if (invert_x) + x = X_AXIS_MAX - x; + if (invert_y) + y = Y_AXIS_MAX - y; + + if (x != X_AXIS_MAX && x != 0) { + input_report_key(htcpen_dev, BTN_TOUCH, 1); + input_report_abs(htcpen_dev, ABS_X, x); + input_report_abs(htcpen_dev, ABS_Y, y); + } + } + + input_sync(htcpen_dev); + + inb_p(HTCPEN_PORT_IRQ_CLEAR); + + return IRQ_HANDLED; +} + +static int htcpen_open(struct input_dev *dev) +{ + outb_p(DEVICE_ENABLE, HTCPEN_PORT_INIT); + + return 0; +} + +static void htcpen_close(struct input_dev *dev) +{ + outb_p(DEVICE_DISABLE, HTCPEN_PORT_INIT); + synchronize_irq(HTCPEN_IRQ); +} + +static int htcpen_isa_probe(struct device *dev, unsigned int id) +{ + struct input_dev *htcpen_dev; + int err = -EBUSY; + + if (!request_region(HTCPEN_PORT_IRQ_CLEAR, 1, "htcpen")) { + printk(KERN_ERR "htcpen: unable to get IO region 0x%x\n", + HTCPEN_PORT_IRQ_CLEAR); + goto request_region1_failed; + } + + if (!request_region(HTCPEN_PORT_INIT, 1, "htcpen")) { + printk(KERN_ERR "htcpen: unable to get IO region 0x%x\n", + HTCPEN_PORT_INIT); + goto request_region2_failed; + } + + if (!request_region(HTCPEN_PORT_INDEX, 2, "htcpen")) { + printk(KERN_ERR "htcpen: unable to get IO region 0x%x\n", + HTCPEN_PORT_INDEX); + goto request_region3_failed; + } + + htcpen_dev = input_allocate_device(); + if (!htcpen_dev) { + printk(KERN_ERR "htcpen: can't allocate device\n"); + err = -ENOMEM; + goto input_alloc_failed; + } + + htcpen_dev->name = "HTC Shift EC TouchScreen"; + htcpen_dev->id.bustype = BUS_ISA; + + htcpen_dev->evbit[0] = BIT_MASK(EV_ABS) | BIT_MASK(EV_KEY); + htcpen_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH); + input_set_abs_params(htcpen_dev, ABS_X, 0, X_AXIS_MAX, 0, 0); + input_set_abs_params(htcpen_dev, ABS_Y, 0, Y_AXIS_MAX, 0, 0); + + htcpen_dev->open = htcpen_open; + htcpen_dev->close = htcpen_close; + + err = request_irq(HTCPEN_IRQ, htcpen_interrupt, 0, "htcpen", + htcpen_dev); + if (err) { + printk(KERN_ERR "htcpen: irq busy\n"); + goto request_irq_failed; + } + + inb_p(HTCPEN_PORT_IRQ_CLEAR); + + err = input_register_device(htcpen_dev); + if (err) + goto input_register_failed; + + dev_set_drvdata(dev, htcpen_dev); + + return 0; + + input_register_failed: + free_irq(HTCPEN_IRQ, htcpen_dev); + request_irq_failed: + input_free_device(htcpen_dev); + input_alloc_failed: + release_region(HTCPEN_PORT_INDEX, 2); + request_region3_failed: + release_region(HTCPEN_PORT_INIT, 1); + request_region2_failed: + release_region(HTCPEN_PORT_IRQ_CLEAR, 1); + request_region1_failed: + return err; +} + +static void htcpen_isa_remove(struct device *dev, unsigned int id) +{ + struct input_dev *htcpen_dev = dev_get_drvdata(dev); + + input_unregister_device(htcpen_dev); + + free_irq(HTCPEN_IRQ, htcpen_dev); + + release_region(HTCPEN_PORT_INDEX, 2); + release_region(HTCPEN_PORT_INIT, 1); + release_region(HTCPEN_PORT_IRQ_CLEAR, 1); +} + +#ifdef CONFIG_PM +static int htcpen_isa_suspend(struct device *dev, unsigned int n, + pm_message_t state) +{ + outb_p(DEVICE_DISABLE, HTCPEN_PORT_INIT); + + return 0; +} + +static int htcpen_isa_resume(struct device *dev, unsigned int n) +{ + outb_p(DEVICE_ENABLE, HTCPEN_PORT_INIT); + + return 0; +} +#endif + +static struct isa_driver htcpen_isa_driver = { + .probe = htcpen_isa_probe, + .remove = htcpen_isa_remove, +#ifdef CONFIG_PM + .suspend = htcpen_isa_suspend, + .resume = htcpen_isa_resume, +#endif + .driver = { + .owner = THIS_MODULE, + .name = "htcpen", + } +}; + +static const struct dmi_system_id htcshift_dmi_table[] __initconst = { + { + .ident = "Shift", + .matches = { + DMI_MATCH(DMI_SYS_VENDOR, "High Tech Computer Corp"), + DMI_MATCH(DMI_PRODUCT_NAME, "Shift"), + }, + }, + { } +}; +MODULE_DEVICE_TABLE(dmi, htcshift_dmi_table); + +static int __init htcpen_isa_init(void) +{ + if (!dmi_check_system(htcshift_dmi_table)) + return -ENODEV; + + return isa_register_driver(&htcpen_isa_driver, 1); +} + +static void __exit htcpen_isa_exit(void) +{ + isa_unregister_driver(&htcpen_isa_driver); +} + +module_init(htcpen_isa_init); +module_exit(htcpen_isa_exit); -- cgit v1.3.1