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-ds1216.c | 174 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 174 insertions(+) create mode 100644 drivers/rtc/rtc-ds1216.c (limited to 'drivers/rtc/rtc-ds1216.c') diff --git a/drivers/rtc/rtc-ds1216.c b/drivers/rtc/rtc-ds1216.c new file mode 100644 index 000000000..7eeb3f359 --- /dev/null +++ b/drivers/rtc/rtc-ds1216.c @@ -0,0 +1,174 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Dallas DS1216 RTC driver + * + * Copyright (c) 2007 Thomas Bogendoerfer + * + */ + +#include +#include +#include +#include +#include + +struct ds1216_regs { + u8 tsec; + u8 sec; + u8 min; + u8 hour; + u8 wday; + u8 mday; + u8 month; + u8 year; +}; + +#define DS1216_HOUR_1224 (1 << 7) +#define DS1216_HOUR_AMPM (1 << 5) + +struct ds1216_priv { + struct rtc_device *rtc; + void __iomem *ioaddr; +}; + +static const u8 magic[] = { + 0xc5, 0x3a, 0xa3, 0x5c, 0xc5, 0x3a, 0xa3, 0x5c +}; + +/* + * Read the 64 bit we'd like to have - It a series + * of 64 bits showing up in the LSB of the base register. + * + */ +static void ds1216_read(u8 __iomem *ioaddr, u8 *buf) +{ + unsigned char c; + int i, j; + + for (i = 0; i < 8; i++) { + c = 0; + for (j = 0; j < 8; j++) + c |= (readb(ioaddr) & 0x1) << j; + buf[i] = c; + } +} + +static void ds1216_write(u8 __iomem *ioaddr, const u8 *buf) +{ + unsigned char c; + int i, j; + + for (i = 0; i < 8; i++) { + c = buf[i]; + for (j = 0; j < 8; j++) { + writeb(c, ioaddr); + c = c >> 1; + } + } +} + +static void ds1216_switch_ds_to_clock(u8 __iomem *ioaddr) +{ + /* Reset magic pointer */ + readb(ioaddr); + /* Write 64 bit magic to DS1216 */ + ds1216_write(ioaddr, magic); +} + +static int ds1216_rtc_read_time(struct device *dev, struct rtc_time *tm) +{ + struct ds1216_priv *priv = dev_get_drvdata(dev); + struct ds1216_regs regs; + + ds1216_switch_ds_to_clock(priv->ioaddr); + ds1216_read(priv->ioaddr, (u8 *)®s); + + tm->tm_sec = bcd2bin(regs.sec); + tm->tm_min = bcd2bin(regs.min); + if (regs.hour & DS1216_HOUR_1224) { + /* AM/PM mode */ + tm->tm_hour = bcd2bin(regs.hour & 0x1f); + if (regs.hour & DS1216_HOUR_AMPM) + tm->tm_hour += 12; + } else + tm->tm_hour = bcd2bin(regs.hour & 0x3f); + tm->tm_wday = (regs.wday & 7) - 1; + tm->tm_mday = bcd2bin(regs.mday & 0x3f); + tm->tm_mon = bcd2bin(regs.month & 0x1f); + tm->tm_year = bcd2bin(regs.year); + if (tm->tm_year < 70) + tm->tm_year += 100; + + return 0; +} + +static int ds1216_rtc_set_time(struct device *dev, struct rtc_time *tm) +{ + struct ds1216_priv *priv = dev_get_drvdata(dev); + struct ds1216_regs regs; + + ds1216_switch_ds_to_clock(priv->ioaddr); + ds1216_read(priv->ioaddr, (u8 *)®s); + + regs.tsec = 0; /* clear 0.1 and 0.01 seconds */ + regs.sec = bin2bcd(tm->tm_sec); + regs.min = bin2bcd(tm->tm_min); + regs.hour &= DS1216_HOUR_1224; + if (regs.hour && tm->tm_hour > 12) { + regs.hour |= DS1216_HOUR_AMPM; + tm->tm_hour -= 12; + } + regs.hour |= bin2bcd(tm->tm_hour); + regs.wday &= ~7; + regs.wday |= tm->tm_wday; + regs.mday = bin2bcd(tm->tm_mday); + regs.month = bin2bcd(tm->tm_mon); + regs.year = bin2bcd(tm->tm_year % 100); + + ds1216_switch_ds_to_clock(priv->ioaddr); + ds1216_write(priv->ioaddr, (u8 *)®s); + return 0; +} + +static const struct rtc_class_ops ds1216_rtc_ops = { + .read_time = ds1216_rtc_read_time, + .set_time = ds1216_rtc_set_time, +}; + +static int __init ds1216_rtc_probe(struct platform_device *pdev) +{ + struct ds1216_priv *priv; + u8 dummy[8]; + + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + platform_set_drvdata(pdev, priv); + + priv->ioaddr = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(priv->ioaddr)) + return PTR_ERR(priv->ioaddr); + + priv->rtc = devm_rtc_device_register(&pdev->dev, "ds1216", + &ds1216_rtc_ops, THIS_MODULE); + if (IS_ERR(priv->rtc)) + return PTR_ERR(priv->rtc); + + /* dummy read to get clock into a known state */ + ds1216_read(priv->ioaddr, dummy); + return 0; +} + +static struct platform_driver ds1216_rtc_platform_driver = { + .driver = { + .name = "rtc-ds1216", + }, +}; + +module_platform_driver_probe(ds1216_rtc_platform_driver, ds1216_rtc_probe); + +MODULE_AUTHOR("Thomas Bogendoerfer "); +MODULE_DESCRIPTION("DS1216 RTC driver"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:rtc-ds1216"); -- cgit v1.3.1