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/numachip.c | 88 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 88 insertions(+) create mode 100644 drivers/clocksource/numachip.c (limited to 'drivers/clocksource/numachip.c') diff --git a/drivers/clocksource/numachip.c b/drivers/clocksource/numachip.c new file mode 100644 index 000000000..fdb5fc21f --- /dev/null +++ b/drivers/clocksource/numachip.c @@ -0,0 +1,88 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * + * Copyright (C) 2015 Numascale AS. All rights reserved. + */ + +#include + +#include +#include +#include + +static DEFINE_PER_CPU(struct clock_event_device, numachip2_ced); + +static cycles_t numachip2_timer_read(struct clocksource *cs) +{ + return numachip2_read64_lcsr(NUMACHIP2_TIMER_NOW); +} + +static struct clocksource numachip2_clocksource = { + .name = "numachip2", + .rating = 295, + .read = numachip2_timer_read, + .mask = CLOCKSOURCE_MASK(64), + .flags = CLOCK_SOURCE_IS_CONTINUOUS, + .mult = 1, + .shift = 0, +}; + +static int numachip2_set_next_event(unsigned long delta, struct clock_event_device *ced) +{ + numachip2_write64_lcsr(NUMACHIP2_TIMER_DEADLINE + numachip2_timer(), + delta); + return 0; +} + +static const struct clock_event_device numachip2_clockevent __initconst = { + .name = "numachip2", + .rating = 400, + .set_next_event = numachip2_set_next_event, + .features = CLOCK_EVT_FEAT_ONESHOT, + .mult = 1, + .shift = 0, + .min_delta_ns = 1250, + .min_delta_ticks = 1250, + .max_delta_ns = LONG_MAX, + .max_delta_ticks = LONG_MAX, +}; + +static void numachip_timer_interrupt(void) +{ + struct clock_event_device *ced = this_cpu_ptr(&numachip2_ced); + + ced->event_handler(ced); +} + +static __init void numachip_timer_each(struct work_struct *work) +{ + unsigned local_apicid = __this_cpu_read(x86_cpu_to_apicid) & 0xff; + struct clock_event_device *ced = this_cpu_ptr(&numachip2_ced); + + /* Setup IPI vector to local core and relative timing mode */ + numachip2_write64_lcsr(NUMACHIP2_TIMER_INT + numachip2_timer(), + (3 << 22) | (X86_PLATFORM_IPI_VECTOR << 14) | + (local_apicid << 6)); + + *ced = numachip2_clockevent; + ced->cpumask = cpumask_of(smp_processor_id()); + clockevents_register_device(ced); +} + +static int __init numachip_timer_init(void) +{ + if (numachip_system != 2) + return -ENODEV; + + /* Reset timer */ + numachip2_write64_lcsr(NUMACHIP2_TIMER_RESET, 0); + clocksource_register_hz(&numachip2_clocksource, NSEC_PER_SEC); + + /* Setup per-cpu clockevents */ + x86_platform_ipi_callback = numachip_timer_interrupt; + schedule_on_each_cpu(&numachip_timer_each); + + return 0; +} + +arch_initcall(numachip_timer_init); -- cgit v1.3.1