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-ep93xx.c | 170 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 170 insertions(+) create mode 100644 drivers/rtc/rtc-ep93xx.c (limited to 'drivers/rtc/rtc-ep93xx.c') diff --git a/drivers/rtc/rtc-ep93xx.c b/drivers/rtc/rtc-ep93xx.c new file mode 100644 index 000000000..507c9f220 --- /dev/null +++ b/drivers/rtc/rtc-ep93xx.c @@ -0,0 +1,170 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * A driver for the RTC embedded in the Cirrus Logic EP93XX processors + * Copyright (c) 2006 Tower Technologies + * + * Author: Alessandro Zummo + */ + +#include +#include +#include +#include +#include + +#define EP93XX_RTC_DATA 0x000 +#define EP93XX_RTC_MATCH 0x004 +#define EP93XX_RTC_STATUS 0x008 +#define EP93XX_RTC_STATUS_INTR BIT(0) +#define EP93XX_RTC_LOAD 0x00C +#define EP93XX_RTC_CONTROL 0x010 +#define EP93XX_RTC_CONTROL_MIE BIT(0) +#define EP93XX_RTC_SWCOMP 0x108 +#define EP93XX_RTC_SWCOMP_DEL_MASK 0x001f0000 +#define EP93XX_RTC_SWCOMP_DEL_SHIFT 16 +#define EP93XX_RTC_SWCOMP_INT_MASK 0x0000ffff +#define EP93XX_RTC_SWCOMP_INT_SHIFT 0 + +struct ep93xx_rtc { + void __iomem *mmio_base; +}; + +static int ep93xx_rtc_get_swcomp(struct device *dev, unsigned short *preload, + unsigned short *delete) +{ + struct ep93xx_rtc *ep93xx_rtc = dev_get_drvdata(dev); + unsigned long comp; + + comp = readl(ep93xx_rtc->mmio_base + EP93XX_RTC_SWCOMP); + + if (preload) + *preload = (comp & EP93XX_RTC_SWCOMP_INT_MASK) + >> EP93XX_RTC_SWCOMP_INT_SHIFT; + + if (delete) + *delete = (comp & EP93XX_RTC_SWCOMP_DEL_MASK) + >> EP93XX_RTC_SWCOMP_DEL_SHIFT; + + return 0; +} + +static int ep93xx_rtc_read_time(struct device *dev, struct rtc_time *tm) +{ + struct ep93xx_rtc *ep93xx_rtc = dev_get_drvdata(dev); + unsigned long time; + + time = readl(ep93xx_rtc->mmio_base + EP93XX_RTC_DATA); + + rtc_time64_to_tm(time, tm); + return 0; +} + +static int ep93xx_rtc_set_time(struct device *dev, struct rtc_time *tm) +{ + struct ep93xx_rtc *ep93xx_rtc = dev_get_drvdata(dev); + unsigned long secs = rtc_tm_to_time64(tm); + + writel(secs + 1, ep93xx_rtc->mmio_base + EP93XX_RTC_LOAD); + return 0; +} + +static int ep93xx_rtc_proc(struct device *dev, struct seq_file *seq) +{ + unsigned short preload, delete; + + ep93xx_rtc_get_swcomp(dev, &preload, &delete); + + seq_printf(seq, "preload\t\t: %d\n", preload); + seq_printf(seq, "delete\t\t: %d\n", delete); + + return 0; +} + +static const struct rtc_class_ops ep93xx_rtc_ops = { + .read_time = ep93xx_rtc_read_time, + .set_time = ep93xx_rtc_set_time, + .proc = ep93xx_rtc_proc, +}; + +static ssize_t comp_preload_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + unsigned short preload; + + ep93xx_rtc_get_swcomp(dev->parent, &preload, NULL); + + return sprintf(buf, "%d\n", preload); +} +static DEVICE_ATTR_RO(comp_preload); + +static ssize_t comp_delete_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + unsigned short delete; + + ep93xx_rtc_get_swcomp(dev->parent, NULL, &delete); + + return sprintf(buf, "%d\n", delete); +} +static DEVICE_ATTR_RO(comp_delete); + +static struct attribute *ep93xx_rtc_attrs[] = { + &dev_attr_comp_preload.attr, + &dev_attr_comp_delete.attr, + NULL +}; + +static const struct attribute_group ep93xx_rtc_sysfs_files = { + .attrs = ep93xx_rtc_attrs, +}; + +static int ep93xx_rtc_probe(struct platform_device *pdev) +{ + struct ep93xx_rtc *ep93xx_rtc; + struct rtc_device *rtc; + int err; + + ep93xx_rtc = devm_kzalloc(&pdev->dev, sizeof(*ep93xx_rtc), GFP_KERNEL); + if (!ep93xx_rtc) + return -ENOMEM; + + ep93xx_rtc->mmio_base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(ep93xx_rtc->mmio_base)) + return PTR_ERR(ep93xx_rtc->mmio_base); + + platform_set_drvdata(pdev, ep93xx_rtc); + + rtc = devm_rtc_allocate_device(&pdev->dev); + if (IS_ERR(rtc)) + return PTR_ERR(rtc); + + rtc->ops = &ep93xx_rtc_ops; + rtc->range_max = U32_MAX; + + err = rtc_add_group(rtc, &ep93xx_rtc_sysfs_files); + if (err) + return err; + + return devm_rtc_register_device(rtc); +} + +static const struct of_device_id ep93xx_rtc_of_ids[] = { + { .compatible = "cirrus,ep9301-rtc" }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, ep93xx_rtc_of_ids); + +static struct platform_driver ep93xx_rtc_driver = { + .driver = { + .name = "ep93xx-rtc", + .of_match_table = ep93xx_rtc_of_ids, + }, + .probe = ep93xx_rtc_probe, +}; + +module_platform_driver(ep93xx_rtc_driver); + +MODULE_AUTHOR("Alessandro Zummo "); +MODULE_DESCRIPTION("EP93XX RTC driver"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:ep93xx-rtc"); -- cgit v1.3.1