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/exc3000.c | 477 ++++++++++++++++++++++++++++++++++++ 1 file changed, 477 insertions(+) create mode 100644 drivers/input/touchscreen/exc3000.c (limited to 'drivers/input/touchscreen/exc3000.c') diff --git a/drivers/input/touchscreen/exc3000.c b/drivers/input/touchscreen/exc3000.c new file mode 100644 index 000000000..037bb3523 --- /dev/null +++ b/drivers/input/touchscreen/exc3000.c @@ -0,0 +1,477 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Driver for I2C connected EETI EXC3000 multiple touch controller + * + * Copyright (C) 2017 Ahmet Inan + * + * minimal implementation based on egalax_ts.c and egalax_i2c.c + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define EXC3000_NUM_SLOTS 10 +#define EXC3000_SLOTS_PER_FRAME 5 +#define EXC3000_LEN_FRAME 66 +#define EXC3000_LEN_VENDOR_REQUEST 68 +#define EXC3000_LEN_POINT 10 + +#define EXC3000_LEN_MODEL_NAME 16 +#define EXC3000_LEN_FW_VERSION 16 + +#define EXC3000_VENDOR_EVENT 0x03 +#define EXC3000_MT1_EVENT 0x06 +#define EXC3000_MT2_EVENT 0x18 + +#define EXC3000_TIMEOUT_MS 100 + +#define EXC3000_RESET_MS 10 +#define EXC3000_READY_MS 100 + +static const struct i2c_device_id exc3000_id[]; + +struct eeti_dev_info { + const char *name; + int max_xy; +}; + +enum eeti_dev_id { + EETI_EXC3000, + EETI_EXC80H60, + EETI_EXC80H84, + EETI_EXC81W32, +}; + +static struct eeti_dev_info exc3000_info[] = { + [EETI_EXC3000] = { + .name = "EETI EXC3000 Touch Screen", + .max_xy = SZ_4K - 1, + }, + [EETI_EXC80H60] = { + .name = "EETI EXC80H60 Touch Screen", + .max_xy = SZ_16K - 1, + }, + [EETI_EXC80H84] = { + .name = "EETI EXC80H84 Touch Screen", + .max_xy = SZ_16K - 1, + }, + [EETI_EXC81W32] = { + .name = "EETI EXC81W32 Touch Screen", + .max_xy = SZ_16K - 1, + }, +}; + +struct exc3000_data { + struct i2c_client *client; + const struct eeti_dev_info *info; + struct input_dev *input; + struct touchscreen_properties prop; + struct gpio_desc *reset; + struct timer_list timer; + u8 buf[2 * EXC3000_LEN_FRAME]; + struct completion wait_event; + struct mutex query_lock; +}; + +static void exc3000_report_slots(struct input_dev *input, + struct touchscreen_properties *prop, + const u8 *buf, int num) +{ + for (; num--; buf += EXC3000_LEN_POINT) { + if (buf[0] & BIT(0)) { + input_mt_slot(input, buf[1]); + input_mt_report_slot_state(input, MT_TOOL_FINGER, true); + touchscreen_report_pos(input, prop, + get_unaligned_le16(buf + 2), + get_unaligned_le16(buf + 4), + true); + } + } +} + +static void exc3000_timer(struct timer_list *t) +{ + struct exc3000_data *data = timer_container_of(data, t, timer); + + input_mt_sync_frame(data->input); + input_sync(data->input); +} + +static inline void exc3000_schedule_timer(struct exc3000_data *data) +{ + mod_timer(&data->timer, jiffies + msecs_to_jiffies(EXC3000_TIMEOUT_MS)); +} + +static void exc3000_shutdown_timer(void *timer) +{ + timer_shutdown_sync(timer); +} + +static int exc3000_read_frame(struct exc3000_data *data, u8 *buf) +{ + struct i2c_client *client = data->client; + int ret; + + ret = i2c_master_send(client, "'", 2); + if (ret < 0) + return ret; + + if (ret != 2) + return -EIO; + + ret = i2c_master_recv(client, buf, EXC3000_LEN_FRAME); + if (ret < 0) + return ret; + + if (ret != EXC3000_LEN_FRAME) + return -EIO; + + if (get_unaligned_le16(buf) != EXC3000_LEN_FRAME) + return -EINVAL; + + return 0; +} + +static int exc3000_handle_mt_event(struct exc3000_data *data) +{ + struct input_dev *input = data->input; + int ret, total_slots; + u8 *buf = data->buf; + + total_slots = buf[3]; + if (!total_slots || total_slots > EXC3000_NUM_SLOTS) { + ret = -EINVAL; + goto out_fail; + } + + if (total_slots > EXC3000_SLOTS_PER_FRAME) { + /* Read 2nd frame to get the rest of the contacts. */ + ret = exc3000_read_frame(data, buf + EXC3000_LEN_FRAME); + if (ret) + goto out_fail; + + /* 2nd chunk must have number of contacts set to 0. */ + if (buf[EXC3000_LEN_FRAME + 3] != 0) { + ret = -EINVAL; + goto out_fail; + } + } + + /* + * We read full state successfully, no contacts will be "stuck". + */ + timer_delete_sync(&data->timer); + + while (total_slots > 0) { + int slots = min(total_slots, EXC3000_SLOTS_PER_FRAME); + + exc3000_report_slots(input, &data->prop, buf + 4, slots); + total_slots -= slots; + buf += EXC3000_LEN_FRAME; + } + + input_mt_sync_frame(input); + input_sync(input); + + return 0; + +out_fail: + /* Schedule a timer to release "stuck" contacts */ + exc3000_schedule_timer(data); + + return ret; +} + +static irqreturn_t exc3000_interrupt(int irq, void *dev_id) +{ + struct exc3000_data *data = dev_id; + u8 *buf = data->buf; + int ret; + + ret = exc3000_read_frame(data, buf); + if (ret) { + /* Schedule a timer to release "stuck" contacts */ + exc3000_schedule_timer(data); + goto out; + } + + switch (buf[2]) { + case EXC3000_VENDOR_EVENT: + complete(&data->wait_event); + break; + + case EXC3000_MT1_EVENT: + case EXC3000_MT2_EVENT: + exc3000_handle_mt_event(data); + break; + + default: + break; + } + +out: + return IRQ_HANDLED; +} + +static int exc3000_vendor_data_request(struct exc3000_data *data, u8 *request, + u8 request_len, u8 *response, int timeout) +{ + u8 buf[EXC3000_LEN_VENDOR_REQUEST] = { 0x67, 0x00, 0x42, 0x00, 0x03 }; + int ret; + unsigned long time_left; + + guard(mutex)(&data->query_lock); + + reinit_completion(&data->wait_event); + + buf[5] = request_len; + memcpy(&buf[6], request, request_len); + + ret = i2c_master_send(data->client, buf, EXC3000_LEN_VENDOR_REQUEST); + if (ret < 0) + return ret; + + time_left = wait_for_completion_timeout(&data->wait_event, + timeout * HZ); + if (time_left == 0) + return -ETIMEDOUT; + + if (data->buf[3] >= EXC3000_LEN_FRAME) + return -ENOSPC; + + memcpy(response, &data->buf[4], data->buf[3]); + return data->buf[3]; +} + +static ssize_t fw_version_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct i2c_client *client = to_i2c_client(dev); + struct exc3000_data *data = i2c_get_clientdata(client); + u8 response[EXC3000_LEN_FRAME]; + int ret; + + /* query bootloader info */ + ret = exc3000_vendor_data_request(data, + (u8[]){0x39, 0x02}, 2, response, 1); + if (ret < 0) + return ret; + + /* + * If the bootloader version is non-zero then the device is in + * bootloader mode and won't answer a query for the application FW + * version, so we just use the bootloader version info. + */ + if (response[2] || response[3]) + return sprintf(buf, "%d.%d\n", response[2], response[3]); + + ret = exc3000_vendor_data_request(data, (u8[]){'D'}, 1, response, 1); + if (ret < 0) + return ret; + + return sprintf(buf, "%s\n", &response[1]); +} +static DEVICE_ATTR_RO(fw_version); + +static ssize_t model_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct i2c_client *client = to_i2c_client(dev); + struct exc3000_data *data = i2c_get_clientdata(client); + u8 response[EXC3000_LEN_FRAME]; + int ret; + + ret = exc3000_vendor_data_request(data, (u8[]){'E'}, 1, response, 1); + if (ret < 0) + return ret; + + return sprintf(buf, "%s\n", &response[1]); +} +static DEVICE_ATTR_RO(model); + +static ssize_t type_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct i2c_client *client = to_i2c_client(dev); + struct exc3000_data *data = i2c_get_clientdata(client); + u8 response[EXC3000_LEN_FRAME]; + int ret; + + ret = exc3000_vendor_data_request(data, (u8[]){'F'}, 1, response, 1); + if (ret < 0) + return ret; + + return sprintf(buf, "%s\n", &response[1]); +} +static DEVICE_ATTR_RO(type); + +static struct attribute *exc3000_attrs[] = { + &dev_attr_fw_version.attr, + &dev_attr_model.attr, + &dev_attr_type.attr, + NULL +}; +ATTRIBUTE_GROUPS(exc3000); + +static int exc3000_probe(struct i2c_client *client) +{ + struct exc3000_data *data; + struct input_dev *input; + int error, max_xy, retry; + + data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + data->client = client; + data->info = device_get_match_data(&client->dev); + if (!data->info) { + enum eeti_dev_id eeti_dev_id = + i2c_match_id(exc3000_id, client)->driver_data; + data->info = &exc3000_info[eeti_dev_id]; + } + timer_setup(&data->timer, exc3000_timer, 0); + init_completion(&data->wait_event); + mutex_init(&data->query_lock); + + data->reset = devm_gpiod_get_optional(&client->dev, "reset", + GPIOD_OUT_HIGH); + if (IS_ERR(data->reset)) + return PTR_ERR(data->reset); + + /* For proper reset sequence, enable power while reset asserted */ + error = devm_regulator_get_enable(&client->dev, "vdd"); + if (error && error != -ENODEV) + return dev_err_probe(&client->dev, error, + "failed to request vdd regulator\n"); + + if (data->reset) { + msleep(EXC3000_RESET_MS); + gpiod_set_value_cansleep(data->reset, 0); + msleep(EXC3000_READY_MS); + } + + input = devm_input_allocate_device(&client->dev); + if (!input) + return -ENOMEM; + + data->input = input; + input_set_drvdata(input, data); + + input->name = data->info->name; + input->id.bustype = BUS_I2C; + + max_xy = data->info->max_xy; + input_set_abs_params(input, ABS_MT_POSITION_X, 0, max_xy, 0, 0); + input_set_abs_params(input, ABS_MT_POSITION_Y, 0, max_xy, 0, 0); + + touchscreen_parse_properties(input, true, &data->prop); + + error = input_mt_init_slots(input, EXC3000_NUM_SLOTS, + INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED); + if (error) + return error; + + error = input_register_device(input); + if (error) + return error; + + error = devm_add_action_or_reset(&client->dev, exc3000_shutdown_timer, + &data->timer); + if (error) + return error; + + error = devm_request_threaded_irq(&client->dev, client->irq, + NULL, exc3000_interrupt, IRQF_ONESHOT, + client->name, data); + if (error) + return error; + + /* + * I²C does not have built-in recovery, so retry on failure. This + * ensures, that the device probe will not fail for temporary issues + * on the bus. This is not needed for the sysfs calls (userspace + * will receive the error code and can start another query) and + * cannot be done for touch events (but that only means loosing one + * or two touch events anyways). + */ + for (retry = 0; retry < 3; retry++) { + u8 response[EXC3000_LEN_FRAME]; + + error = exc3000_vendor_data_request(data, (u8[]){'E'}, 1, + response, 1); + if (error > 0) { + dev_dbg(&client->dev, "TS Model: %s", &response[1]); + error = 0; + break; + } + dev_warn(&client->dev, "Retry %d get EETI EXC3000 model: %d\n", + retry + 1, error); + } + + if (error) + return error; + + i2c_set_clientdata(client, data); + + return 0; +} + +static const struct i2c_device_id exc3000_id[] = { + { .name = "exc3000", .driver_data = EETI_EXC3000 }, + { .name = "exc80h60", .driver_data = EETI_EXC80H60 }, + { .name = "exc80h84", .driver_data = EETI_EXC80H84 }, + { .name = "exc81w32", .driver_data = EETI_EXC81W32 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, exc3000_id); + +#ifdef CONFIG_OF +static const struct of_device_id exc3000_of_match[] = { + { .compatible = "eeti,exc3000", .data = &exc3000_info[EETI_EXC3000] }, + { .compatible = "eeti,exc80h60", .data = &exc3000_info[EETI_EXC80H60] }, + { .compatible = "eeti,exc80h84", .data = &exc3000_info[EETI_EXC80H84] }, + { .compatible = "eeti,exc81w32", .data = &exc3000_info[EETI_EXC81W32] }, + { } +}; +MODULE_DEVICE_TABLE(of, exc3000_of_match); +#endif + +#ifdef CONFIG_ACPI +static const struct acpi_device_id exc3000_acpi_match[] = { + { "EGA00001", .driver_data = (kernel_ulong_t)&exc3000_info[EETI_EXC80H60] }, + { } +}; +MODULE_DEVICE_TABLE(acpi, exc3000_acpi_match); +#endif + +static struct i2c_driver exc3000_driver = { + .driver = { + .name = "exc3000", + .dev_groups = exc3000_groups, + .of_match_table = of_match_ptr(exc3000_of_match), + .acpi_match_table = ACPI_PTR(exc3000_acpi_match), + }, + .id_table = exc3000_id, + .probe = exc3000_probe, +}; + +module_i2c_driver(exc3000_driver); + +MODULE_AUTHOR("Ahmet Inan "); +MODULE_DESCRIPTION("I2C connected EETI EXC3000 multiple touch controller driver"); +MODULE_LICENSE("GPL v2"); -- cgit v1.3.1