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/mmio.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 75 insertions(+) create mode 100644 drivers/clocksource/mmio.c (limited to 'drivers/clocksource/mmio.c') diff --git a/drivers/clocksource/mmio.c b/drivers/clocksource/mmio.c new file mode 100644 index 000000000..0fee8edb8 --- /dev/null +++ b/drivers/clocksource/mmio.c @@ -0,0 +1,75 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Generic MMIO clocksource support + */ +#include +#include +#include +#include + +struct clocksource_mmio { + void __iomem *reg; + struct clocksource clksrc; +}; + +static inline struct clocksource_mmio *to_mmio_clksrc(struct clocksource *c) +{ + return container_of(c, struct clocksource_mmio, clksrc); +} + +u64 clocksource_mmio_readl_up(struct clocksource *c) +{ + return (u64)readl_relaxed(to_mmio_clksrc(c)->reg); +} +EXPORT_SYMBOL_GPL(clocksource_mmio_readl_up); + +u64 clocksource_mmio_readl_down(struct clocksource *c) +{ + return ~(u64)readl_relaxed(to_mmio_clksrc(c)->reg) & c->mask; +} +EXPORT_SYMBOL_GPL(clocksource_mmio_readl_down); + +u64 clocksource_mmio_readw_up(struct clocksource *c) +{ + return (u64)readw_relaxed(to_mmio_clksrc(c)->reg); +} +EXPORT_SYMBOL_GPL(clocksource_mmio_readw_up); + +u64 clocksource_mmio_readw_down(struct clocksource *c) +{ + return ~(u64)readw_relaxed(to_mmio_clksrc(c)->reg) & c->mask; +} +EXPORT_SYMBOL_GPL(clocksource_mmio_readw_down); + +/** + * clocksource_mmio_init - Initialize a simple mmio based clocksource + * @base: Virtual address of the clock readout register + * @name: Name of the clocksource + * @hz: Frequency of the clocksource in Hz + * @rating: Rating of the clocksource + * @bits: Number of valid bits + * @read: One of clocksource_mmio_read*() above + */ +int clocksource_mmio_init(void __iomem *base, const char *name, + unsigned long hz, int rating, unsigned bits, + u64 (*read)(struct clocksource *)) +{ + struct clocksource_mmio *cs; + + if (bits > 64 || bits < 16) + return -EINVAL; + + cs = kzalloc_obj(struct clocksource_mmio); + if (!cs) + return -ENOMEM; + + cs->reg = base; + cs->clksrc.name = name; + cs->clksrc.rating = rating; + cs->clksrc.read = read; + cs->clksrc.mask = CLOCKSOURCE_MASK(bits); + cs->clksrc.flags = CLOCK_SOURCE_IS_CONTINUOUS; + + return clocksource_register_hz(&cs->clksrc, hz); +} +EXPORT_SYMBOL_GPL(clocksource_mmio_init); -- cgit v1.3.1