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/iio/trigger/stm32-lptimer-trigger.c | 152 ++++++++++++++++++++++++++++ 1 file changed, 152 insertions(+) create mode 100644 drivers/iio/trigger/stm32-lptimer-trigger.c (limited to 'drivers/iio/trigger/stm32-lptimer-trigger.c') diff --git a/drivers/iio/trigger/stm32-lptimer-trigger.c b/drivers/iio/trigger/stm32-lptimer-trigger.c new file mode 100644 index 000000000..828890fe3 --- /dev/null +++ b/drivers/iio/trigger/stm32-lptimer-trigger.c @@ -0,0 +1,152 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * STM32 Low-Power Timer Trigger driver + * + * Copyright (C) STMicroelectronics 2017 + * + * Author: Fabrice Gasnier . + * + * Inspired by Benjamin Gaignard's stm32-timer-trigger driver + */ + +#include +#include +#include +#include +#include +#include + +/* Maximum triggers + one trailing null entry to indicate the end of array */ +#define MAX_TRIGGERS 3 + +struct stm32_lptim_cfg { + const char * const (*triggers)[MAX_TRIGGERS]; + unsigned int nb_triggers; +}; + +/* List Low-Power Timer triggers for H7, MP13, MP15 */ +static const char * const stm32_lptim_triggers[][MAX_TRIGGERS] = { + { LPTIM1_OUT,}, + { LPTIM2_OUT,}, + { LPTIM3_OUT,}, +}; + +/* List Low-Power Timer triggers for STM32MP25 */ +static const char * const stm32mp25_lptim_triggers[][MAX_TRIGGERS] = { + { LPTIM1_CH1, LPTIM1_CH2, }, + { LPTIM2_CH1, LPTIM2_CH2, }, + { LPTIM3_CH1,}, + { LPTIM4_CH1,}, + { LPTIM5_OUT,}, +}; + +static const struct stm32_lptim_cfg stm32mp15_lptim_cfg = { + .triggers = stm32_lptim_triggers, + .nb_triggers = ARRAY_SIZE(stm32_lptim_triggers), +}; + +static const struct stm32_lptim_cfg stm32mp25_lptim_cfg = { + .triggers = stm32mp25_lptim_triggers, + .nb_triggers = ARRAY_SIZE(stm32mp25_lptim_triggers), +}; + +struct stm32_lptim_trigger { + struct device *dev; + const char * const *triggers; +}; + +static int stm32_lptim_validate_device(struct iio_trigger *trig, + struct iio_dev *indio_dev) +{ + if (indio_dev->modes & INDIO_HARDWARE_TRIGGERED) + return 0; + + return -EINVAL; +} + +static const struct iio_trigger_ops stm32_lptim_trigger_ops = { + .validate_device = stm32_lptim_validate_device, +}; + +/** + * is_stm32_lptim_trigger + * @trig: trigger to be checked + * + * return true if the trigger is a valid STM32 IIO Low-Power Timer Trigger + * either return false + */ +bool is_stm32_lptim_trigger(struct iio_trigger *trig) +{ + return (trig->ops == &stm32_lptim_trigger_ops); +} +EXPORT_SYMBOL(is_stm32_lptim_trigger); + +static int stm32_lptim_setup_trig(struct stm32_lptim_trigger *priv) +{ + const char * const *cur = priv->triggers; + int ret; + + while (cur && *cur) { + struct iio_trigger *trig; + + trig = devm_iio_trigger_alloc(priv->dev, "%s", *cur); + if (!trig) + return -ENOMEM; + + trig->dev.parent = priv->dev->parent; + trig->ops = &stm32_lptim_trigger_ops; + iio_trigger_set_drvdata(trig, priv); + + ret = devm_iio_trigger_register(priv->dev, trig); + if (ret) + return ret; + cur++; + } + + return 0; +} + +static int stm32_lptim_trigger_probe(struct platform_device *pdev) +{ + struct stm32_lptim_trigger *priv; + struct stm32_lptim_cfg const *lptim_cfg; + u32 index; + + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + if (device_property_read_u32(&pdev->dev, "reg", &index)) + return -EINVAL; + + lptim_cfg = device_get_match_data(&pdev->dev); + + if (index >= lptim_cfg->nb_triggers) + return -EINVAL; + + priv->dev = &pdev->dev; + priv->triggers = lptim_cfg->triggers[index]; + + return stm32_lptim_setup_trig(priv); +} + +static const struct of_device_id stm32_lptim_trig_of_match[] = { + { .compatible = "st,stm32-lptimer-trigger", .data = &stm32mp15_lptim_cfg }, + { .compatible = "st,stm32mp25-lptimer-trigger", .data = &stm32mp25_lptim_cfg}, + { } +}; +MODULE_DEVICE_TABLE(of, stm32_lptim_trig_of_match); + +static struct platform_driver stm32_lptim_trigger_driver = { + .probe = stm32_lptim_trigger_probe, + .driver = { + .name = "stm32-lptimer-trigger", + .of_match_table = stm32_lptim_trig_of_match, + }, +}; +module_platform_driver(stm32_lptim_trigger_driver); + +MODULE_AUTHOR("Fabrice Gasnier "); +MODULE_ALIAS("platform:stm32-lptimer-trigger"); +MODULE_DESCRIPTION("STMicroelectronics STM32 LPTIM trigger driver"); +MODULE_LICENSE("GPL v2"); -- cgit v1.3.1