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/clocksource/timer-ixp4xx.c | 293 +++++++++++++++++++++++++++++++++++++ 1 file changed, 293 insertions(+) create mode 100644 drivers/clocksource/timer-ixp4xx.c (limited to 'drivers/clocksource/timer-ixp4xx.c') diff --git a/drivers/clocksource/timer-ixp4xx.c b/drivers/clocksource/timer-ixp4xx.c new file mode 100644 index 000000000..4238a004f --- /dev/null +++ b/drivers/clocksource/timer-ixp4xx.c @@ -0,0 +1,293 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * IXP4 timer driver + * Copyright (C) 2019 Linus Walleij + * + * Based on arch/arm/mach-ixp4xx/common.c + * Copyright 2002 (C) Intel Corporation + * Copyright 2003-2004 (C) MontaVista, Software, Inc. + * Copyright (C) Deepak Saxena + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* + * Constants to make it easy to access Timer Control/Status registers + */ +#define IXP4XX_OSTS_OFFSET 0x00 /* Continuous Timestamp */ +#define IXP4XX_OST1_OFFSET 0x04 /* Timer 1 Timestamp */ +#define IXP4XX_OSRT1_OFFSET 0x08 /* Timer 1 Reload */ +#define IXP4XX_OST2_OFFSET 0x0C /* Timer 2 Timestamp */ +#define IXP4XX_OSRT2_OFFSET 0x10 /* Timer 2 Reload */ +#define IXP4XX_OSST_OFFSET 0x20 /* Timer Status */ + +/* + * Timer register values and bit definitions + */ +#define IXP4XX_OST_ENABLE 0x00000001 +#define IXP4XX_OST_ONE_SHOT 0x00000002 +/* Low order bits of reload value ignored */ +#define IXP4XX_OST_RELOAD_MASK 0x00000003 +#define IXP4XX_OST_DISABLED 0x00000000 +#define IXP4XX_OSST_TIMER_1_PEND 0x00000001 +#define IXP4XX_OSST_TIMER_2_PEND 0x00000002 +#define IXP4XX_OSST_TIMER_TS_PEND 0x00000004 +/* Remaining registers are for the watchdog and defined in the watchdog driver */ + +struct ixp4xx_timer { + void __iomem *base; + u32 latch; + struct clock_event_device clkevt; +#ifdef CONFIG_ARM + struct delay_timer delay_timer; +#endif +}; + +/* + * A local singleton used by sched_clock and delay timer reads, which are + * fast and stateless + */ +static struct ixp4xx_timer *local_ixp4xx_timer; + +static inline struct ixp4xx_timer * +to_ixp4xx_timer(struct clock_event_device *evt) +{ + return container_of(evt, struct ixp4xx_timer, clkevt); +} + +static unsigned long ixp4xx_read_timer(void) +{ + return __raw_readl(local_ixp4xx_timer->base + IXP4XX_OSTS_OFFSET); +} + +static u64 notrace ixp4xx_read_sched_clock(void) +{ + return ixp4xx_read_timer(); +} + +static u64 ixp4xx_clocksource_read(struct clocksource *c) +{ + return ixp4xx_read_timer(); +} + +static irqreturn_t ixp4xx_timer_interrupt(int irq, void *dev_id) +{ + struct ixp4xx_timer *tmr = dev_id; + struct clock_event_device *evt = &tmr->clkevt; + + /* Clear Pending Interrupt */ + __raw_writel(IXP4XX_OSST_TIMER_1_PEND, + tmr->base + IXP4XX_OSST_OFFSET); + + evt->event_handler(evt); + + return IRQ_HANDLED; +} + +static int ixp4xx_set_next_event(unsigned long cycles, + struct clock_event_device *evt) +{ + struct ixp4xx_timer *tmr = to_ixp4xx_timer(evt); + u32 val; + + val = __raw_readl(tmr->base + IXP4XX_OSRT1_OFFSET); + /* Keep enable/oneshot bits */ + val &= IXP4XX_OST_RELOAD_MASK; + __raw_writel((cycles & ~IXP4XX_OST_RELOAD_MASK) | val, + tmr->base + IXP4XX_OSRT1_OFFSET); + + return 0; +} + +static int ixp4xx_shutdown(struct clock_event_device *evt) +{ + struct ixp4xx_timer *tmr = to_ixp4xx_timer(evt); + u32 val; + + val = __raw_readl(tmr->base + IXP4XX_OSRT1_OFFSET); + val &= ~IXP4XX_OST_ENABLE; + __raw_writel(val, tmr->base + IXP4XX_OSRT1_OFFSET); + + return 0; +} + +static int ixp4xx_set_oneshot(struct clock_event_device *evt) +{ + struct ixp4xx_timer *tmr = to_ixp4xx_timer(evt); + + __raw_writel(IXP4XX_OST_ENABLE | IXP4XX_OST_ONE_SHOT, + tmr->base + IXP4XX_OSRT1_OFFSET); + + return 0; +} + +static int ixp4xx_set_periodic(struct clock_event_device *evt) +{ + struct ixp4xx_timer *tmr = to_ixp4xx_timer(evt); + u32 val; + + val = tmr->latch & ~IXP4XX_OST_RELOAD_MASK; + val |= IXP4XX_OST_ENABLE; + __raw_writel(val, tmr->base + IXP4XX_OSRT1_OFFSET); + + return 0; +} + +static int ixp4xx_resume(struct clock_event_device *evt) +{ + struct ixp4xx_timer *tmr = to_ixp4xx_timer(evt); + u32 val; + + val = __raw_readl(tmr->base + IXP4XX_OSRT1_OFFSET); + val |= IXP4XX_OST_ENABLE; + __raw_writel(val, tmr->base + IXP4XX_OSRT1_OFFSET); + + return 0; +} + +/* + * IXP4xx timer tick + * We use OS timer1 on the CPU for the timer tick and the timestamp + * counter as a source of real clock ticks to account for missed jiffies. + */ +static __init int ixp4xx_timer_register(void __iomem *base, + int timer_irq, + unsigned int timer_freq) +{ + struct ixp4xx_timer *tmr; + int ret; + + tmr = kzalloc_obj(*tmr); + if (!tmr) + return -ENOMEM; + tmr->base = base; + + /* + * The timer register doesn't allow to specify the two least + * significant bits of the timeout value and assumes them being zero. + * So make sure the latch is the best value with the two least + * significant bits unset. + */ + tmr->latch = DIV_ROUND_CLOSEST(timer_freq, + (IXP4XX_OST_RELOAD_MASK + 1) * HZ) + * (IXP4XX_OST_RELOAD_MASK + 1); + + local_ixp4xx_timer = tmr; + + /* Reset/disable counter */ + __raw_writel(0, tmr->base + IXP4XX_OSRT1_OFFSET); + + /* Clear any pending interrupt on timer 1 */ + __raw_writel(IXP4XX_OSST_TIMER_1_PEND, + tmr->base + IXP4XX_OSST_OFFSET); + + /* Reset time-stamp counter */ + __raw_writel(0, tmr->base + IXP4XX_OSTS_OFFSET); + + clocksource_mmio_init(NULL, "OSTS", timer_freq, 200, 32, + ixp4xx_clocksource_read); + + tmr->clkevt.name = "ixp4xx timer1"; + tmr->clkevt.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT; + tmr->clkevt.rating = 200; + tmr->clkevt.set_state_shutdown = ixp4xx_shutdown; + tmr->clkevt.set_state_periodic = ixp4xx_set_periodic; + tmr->clkevt.set_state_oneshot = ixp4xx_set_oneshot; + tmr->clkevt.tick_resume = ixp4xx_resume; + tmr->clkevt.set_next_event = ixp4xx_set_next_event; + tmr->clkevt.cpumask = cpumask_of(0); + tmr->clkevt.irq = timer_irq; + ret = request_irq(timer_irq, ixp4xx_timer_interrupt, + IRQF_TIMER, "IXP4XX-TIMER1", tmr); + if (ret) { + pr_crit("no timer IRQ\n"); + return -ENODEV; + } + clockevents_config_and_register(&tmr->clkevt, timer_freq, + 0xf, 0xfffffffe); + + sched_clock_register(ixp4xx_read_sched_clock, 32, timer_freq); + +#ifdef CONFIG_ARM + /* Also use this timer for delays */ + tmr->delay_timer.read_current_timer = ixp4xx_read_timer; + tmr->delay_timer.freq = timer_freq; + register_current_timer_delay(&tmr->delay_timer); +#endif + + return 0; +} + +static struct platform_device ixp4xx_watchdog_device = { + .name = "ixp4xx-watchdog", + .id = -1, +}; + +/* + * This probe gets called after the timer is already up and running. The main + * function on this platform is to spawn the watchdog device as a child. + */ +static int ixp4xx_timer_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + + /* Pass the base address as platform data and nothing else */ + ixp4xx_watchdog_device.dev.platform_data = local_ixp4xx_timer->base; + ixp4xx_watchdog_device.dev.parent = dev; + return platform_device_register(&ixp4xx_watchdog_device); +} + +static const struct of_device_id ixp4xx_timer_dt_id[] = { + { .compatible = "intel,ixp4xx-timer", }, + { /* sentinel */ }, +}; + +static struct platform_driver ixp4xx_timer_driver = { + .probe = ixp4xx_timer_probe, + .driver = { + .name = "ixp4xx-timer", + .of_match_table = ixp4xx_timer_dt_id, + .suppress_bind_attrs = true, + }, +}; +builtin_platform_driver(ixp4xx_timer_driver); + +static __init int ixp4xx_of_timer_init(struct device_node *np) +{ + void __iomem *base; + int irq; + int ret; + + base = of_iomap(np, 0); + if (!base) { + pr_crit("IXP4xx: can't remap timer\n"); + return -ENODEV; + } + + irq = irq_of_parse_and_map(np, 0); + if (irq <= 0) { + pr_err("Can't parse IRQ\n"); + ret = -EINVAL; + goto out_unmap; + } + + /* TODO: get some fixed clocks into the device tree */ + ret = ixp4xx_timer_register(base, irq, 66666000); + if (ret) + goto out_unmap; + return 0; + +out_unmap: + iounmap(base); + return ret; +} +TIMER_OF_DECLARE(ixp4xx, "intel,ixp4xx-timer", ixp4xx_of_timer_init); -- cgit v1.3.1