From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- drivers/rtc/rtc-meson-vrtc.c | 150 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 150 insertions(+) create mode 100644 drivers/rtc/rtc-meson-vrtc.c (limited to 'drivers/rtc/rtc-meson-vrtc.c') diff --git a/drivers/rtc/rtc-meson-vrtc.c b/drivers/rtc/rtc-meson-vrtc.c new file mode 100644 index 000000000..7d38258cb --- /dev/null +++ b/drivers/rtc/rtc-meson-vrtc.c @@ -0,0 +1,150 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2019 BayLibre, SAS + * Author: Neil Armstrong + * Copyright (C) 2015 Amlogic, Inc. All rights reserved. + */ +#include +#include +#include +#include +#include +#include + +struct meson_vrtc_data { + void __iomem *io_alarm; + unsigned long alarm_time; + bool enabled; +}; + +static int meson_vrtc_read_time(struct device *dev, struct rtc_time *tm) +{ + struct timespec64 time; + + dev_dbg(dev, "%s\n", __func__); + ktime_get_real_ts64(&time); + rtc_time64_to_tm(time.tv_sec, tm); + + return 0; +} + +static void meson_vrtc_set_wakeup_time(struct meson_vrtc_data *vrtc, + unsigned long time) +{ + writel_relaxed(time, vrtc->io_alarm); +} + +static int meson_vrtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm) +{ + struct meson_vrtc_data *vrtc = dev_get_drvdata(dev); + + dev_dbg(dev, "%s: alarm->enabled=%d\n", __func__, alarm->enabled); + if (alarm->enabled) + vrtc->alarm_time = rtc_tm_to_time64(&alarm->time); + else + vrtc->alarm_time = 0; + + return 0; +} + +static int meson_vrtc_alarm_irq_enable(struct device *dev, unsigned int enabled) +{ + struct meson_vrtc_data *vrtc = dev_get_drvdata(dev); + + vrtc->enabled = enabled; + return 0; +} + +static const struct rtc_class_ops meson_vrtc_ops = { + .read_time = meson_vrtc_read_time, + .set_alarm = meson_vrtc_set_alarm, + .alarm_irq_enable = meson_vrtc_alarm_irq_enable, +}; + +static int meson_vrtc_probe(struct platform_device *pdev) +{ + struct meson_vrtc_data *vrtc; + struct rtc_device *rtc; + + vrtc = devm_kzalloc(&pdev->dev, sizeof(*vrtc), GFP_KERNEL); + if (!vrtc) + return -ENOMEM; + + vrtc->io_alarm = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(vrtc->io_alarm)) + return PTR_ERR(vrtc->io_alarm); + + device_init_wakeup(&pdev->dev, true); + + platform_set_drvdata(pdev, vrtc); + + rtc = devm_rtc_allocate_device(&pdev->dev); + if (IS_ERR(rtc)) + return PTR_ERR(rtc); + + rtc->ops = &meson_vrtc_ops; + return devm_rtc_register_device(rtc); +} + +static int __maybe_unused meson_vrtc_suspend(struct device *dev) +{ + struct meson_vrtc_data *vrtc = dev_get_drvdata(dev); + + dev_dbg(dev, "%s\n", __func__); + if (vrtc->alarm_time) { + unsigned long local_time; + long alarm_secs; + struct timespec64 time; + + ktime_get_real_ts64(&time); + local_time = time.tv_sec; + + dev_dbg(dev, "alarm_time = %lus, local_time=%lus\n", + vrtc->alarm_time, local_time); + alarm_secs = vrtc->alarm_time - local_time; + if (alarm_secs > 0) { + meson_vrtc_set_wakeup_time(vrtc, alarm_secs); + dev_dbg(dev, "system will wakeup in %lds.\n", + alarm_secs); + } else { + dev_err(dev, "alarm time already passed: %lds.\n", + alarm_secs); + } + } + + return 0; +} + +static int __maybe_unused meson_vrtc_resume(struct device *dev) +{ + struct meson_vrtc_data *vrtc = dev_get_drvdata(dev); + + dev_dbg(dev, "%s\n", __func__); + + vrtc->alarm_time = 0; + meson_vrtc_set_wakeup_time(vrtc, 0); + return 0; +} + +static SIMPLE_DEV_PM_OPS(meson_vrtc_pm_ops, + meson_vrtc_suspend, meson_vrtc_resume); + +static const struct of_device_id meson_vrtc_dt_match[] = { + { .compatible = "amlogic,meson-vrtc"}, + {}, +}; +MODULE_DEVICE_TABLE(of, meson_vrtc_dt_match); + +static struct platform_driver meson_vrtc_driver = { + .probe = meson_vrtc_probe, + .driver = { + .name = "meson-vrtc", + .of_match_table = meson_vrtc_dt_match, + .pm = &meson_vrtc_pm_ops, + }, +}; + +module_platform_driver(meson_vrtc_driver); + +MODULE_DESCRIPTION("Amlogic Virtual Wakeup RTC Timer driver"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1