ftrace: Synchronize the initialization of ftrace_opsgrafted

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 <rostedt@goodmis.org>

1 files changed, 282 insertions, 0 deletions

diff --git a/arch/arm/mach-omap1/timer32k.c b/arch/arm/mach-omap1/timer32k.c
new file mode 100644
index 000000000..f618a6df2
--- /dev/null
+++ b/arch/arm/mach-omap1/timer32k.c
@@ -0,0 +1,282 @@
+/*
+ * linux/arch/arm/mach-omap1/timer32k.c
+ *
+ * OMAP 32K Timer
+ *
+ * Copyright (C) 2004 - 2005 Nokia Corporation
+ * Partial timer rewrite and additional dynamic tick timer support by
+ * Tony Lindgen <tony@atomide.com> and
+ * Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>
+ * OMAP Dual-mode timer framework support by Timo Teras
+ *
+ * MPU timer code based on the older MPU timer code for OMAP
+ * Copyright (C) 2000 RidgeRun, Inc.
+ * Author: Greg Lonnon <glonnon@ridgerun.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
+ * NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * You should have received a copy of the  GNU General Public License along
+ * with this program; if not, write  to the Free Software Foundation, Inc.,
+ * 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/io.h>
+#include <linux/sched_clock.h>
+
+#include <asm/irq.h>
+#include <asm/mach/irq.h>
+#include <asm/mach/time.h>
+
+#include "hardware.h"
+#include "common.h"
+
+/*
+ * ---------------------------------------------------------------------------
+ * 32KHz OS timer
+ *
+ * This currently works only on 16xx, as 1510 does not have the continuous
+ * 32KHz synchronous timer. The 32KHz synchronous timer is used to keep track
+ * of time in addition to the 32KHz OS timer. Using only the 32KHz OS timer
+ * on 1510 would be possible, but the timer would not be as accurate as
+ * with the 32KHz synchronized timer.
+ * ---------------------------------------------------------------------------
+ */
+
+/* 16xx specific defines */
+#define OMAP1_32K_TIMER_BASE		0xfffb9000
+#define OMAP1_32KSYNC_TIMER_BASE	0xfffbc400
+#define OMAP1_32K_TIMER_CR		0x08
+#define OMAP1_32K_TIMER_TVR		0x00
+#define OMAP1_32K_TIMER_TCR		0x04
+
+#define OMAP_32K_TICKS_PER_SEC		(32768)
+
+/*
+ * TRM says 1 / HZ = ( TVR + 1) / 32768, so TRV = (32768 / HZ) - 1
+ * so with HZ = 128, TVR = 255.
+ */
+#define OMAP_32K_TIMER_TICK_PERIOD	((OMAP_32K_TICKS_PER_SEC / HZ) - 1)
+
+#define JIFFIES_TO_HW_TICKS(nr_jiffies, clock_rate)			\
+				(((nr_jiffies) * (clock_rate)) / HZ)
+
+static inline void omap_32k_timer_write(int val, int reg)
+{
+	omap_writew(val, OMAP1_32K_TIMER_BASE + reg);
+}
+
+static inline void omap_32k_timer_start(unsigned long load_val)
+{
+	if (!load_val)
+		load_val = 1;
+	omap_32k_timer_write(load_val, OMAP1_32K_TIMER_TVR);
+	omap_32k_timer_write(0x0f, OMAP1_32K_TIMER_CR);
+}
+
+static inline void omap_32k_timer_stop(void)
+{
+	omap_32k_timer_write(0x0, OMAP1_32K_TIMER_CR);
+}
+
+#define omap_32k_timer_ack_irq()
+
+static int omap_32k_timer_set_next_event(unsigned long delta,
+					 struct clock_event_device *dev)
+{
+	omap_32k_timer_start(delta);
+
+	return 0;
+}
+
+static int omap_32k_timer_shutdown(struct clock_event_device *evt)
+{
+	omap_32k_timer_stop();
+	return 0;
+}
+
+static int omap_32k_timer_set_periodic(struct clock_event_device *evt)
+{
+	omap_32k_timer_stop();
+	omap_32k_timer_start(OMAP_32K_TIMER_TICK_PERIOD);
+	return 0;
+}
+
+static struct clock_event_device clockevent_32k_timer = {
+	.name			= "32k-timer",
+	.features		= CLOCK_EVT_FEAT_PERIODIC |
+				  CLOCK_EVT_FEAT_ONESHOT,
+	.set_next_event		= omap_32k_timer_set_next_event,
+	.set_state_shutdown	= omap_32k_timer_shutdown,
+	.set_state_periodic	= omap_32k_timer_set_periodic,
+	.set_state_oneshot	= omap_32k_timer_shutdown,
+	.tick_resume		= omap_32k_timer_shutdown,
+};
+
+static irqreturn_t omap_32k_timer_interrupt(int irq, void *dev_id)
+{
+	struct clock_event_device *evt = &clockevent_32k_timer;
+	omap_32k_timer_ack_irq();
+
+	evt->event_handler(evt);
+
+	return IRQ_HANDLED;
+}
+
+static __init void omap_init_32k_timer(void)
+{
+	if (request_irq(INT_OS_TIMER, omap_32k_timer_interrupt,
+			IRQF_TIMER | IRQF_IRQPOLL, "32KHz timer", NULL))
+		pr_err("Failed to request irq %d(32KHz timer)\n", INT_OS_TIMER);
+
+	clockevent_32k_timer.cpumask = cpumask_of(0);
+	clockevents_config_and_register(&clockevent_32k_timer,
+					OMAP_32K_TICKS_PER_SEC, 1, 0xfffffffe);
+}
+
+/* OMAP2_32KSYNCNT_CR_OFF: offset of 32ksync counter register */
+#define OMAP2_32KSYNCNT_REV_OFF		0x0
+#define OMAP2_32KSYNCNT_REV_SCHEME	(0x3 << 30)
+#define OMAP2_32KSYNCNT_CR_OFF_LOW	0x10
+#define OMAP2_32KSYNCNT_CR_OFF_HIGH	0x30
+
+/*
+ * 32KHz clocksource ... always available, on pretty most chips except
+ * OMAP 730 and 1510.  Other timers could be used as clocksources, with
+ * higher resolution in free-running counter modes (e.g. 12 MHz xtal),
+ * but systems won't necessarily want to spend resources that way.
+ */
+static void __iomem *sync32k_cnt_reg;
+
+static u64 notrace omap_32k_read_sched_clock(void)
+{
+	return sync32k_cnt_reg ? readl_relaxed(sync32k_cnt_reg) : 0;
+}
+
+static struct timespec64 persistent_ts;
+static cycles_t cycles;
+static unsigned int persistent_mult, persistent_shift;
+
+/**
+ * omap_read_persistent_clock64 -  Return time from a persistent clock.
+ * @ts: &struct timespec64 for the returned time
+ *
+ * Reads the time from a source which isn't disabled during PM, the
+ * 32k sync timer.  Convert the cycles elapsed since last read into
+ * nsecs and adds to a monotonically increasing timespec64.
+ */
+static void omap_read_persistent_clock64(struct timespec64 *ts)
+{
+	unsigned long long nsecs;
+	cycles_t last_cycles;
+
+	last_cycles = cycles;
+	cycles = sync32k_cnt_reg ? readl_relaxed(sync32k_cnt_reg) : 0;
+
+	nsecs = clocksource_cyc2ns(cycles - last_cycles,
+					persistent_mult, persistent_shift);
+
+	timespec64_add_ns(&persistent_ts, nsecs);
+
+	*ts = persistent_ts;
+}
+
+/**
+ * omap_init_clocksource_32k - setup and register counter 32k as a
+ * kernel clocksource
+ * @vbase: base addr of counter_32k module
+ *
+ * Returns: %0 upon success or negative error code upon failure.
+ *
+ */
+static int __init omap_init_clocksource_32k(void __iomem *vbase)
+{
+	int ret;
+
+	/*
+	 * 32k sync Counter IP register offsets vary between the
+	 * highlander version and the legacy ones.
+	 * The 'SCHEME' bits(30-31) of the revision register is used
+	 * to identify the version.
+	 */
+	if (readl_relaxed(vbase + OMAP2_32KSYNCNT_REV_OFF) &
+						OMAP2_32KSYNCNT_REV_SCHEME)
+		sync32k_cnt_reg = vbase + OMAP2_32KSYNCNT_CR_OFF_HIGH;
+	else
+		sync32k_cnt_reg = vbase + OMAP2_32KSYNCNT_CR_OFF_LOW;
+
+	/*
+	 * 120000 rough estimate from the calculations in
+	 * __clocksource_update_freq_scale.
+	 */
+	clocks_calc_mult_shift(&persistent_mult, &persistent_shift,
+			32768, NSEC_PER_SEC, 120000);
+
+	ret = clocksource_mmio_init(sync32k_cnt_reg, "32k_counter", 32768,
+				250, 32, clocksource_mmio_readl_up);
+	if (ret) {
+		pr_err("32k_counter: can't register clocksource\n");
+		return ret;
+	}
+
+	sched_clock_register(omap_32k_read_sched_clock, 32, 32768);
+	register_persistent_clock(omap_read_persistent_clock64);
+	pr_info("OMAP clocksource: 32k_counter at 32768 Hz\n");
+
+	return 0;
+}
+
+/*
+ * ---------------------------------------------------------------------------
+ * Timer initialization
+ * ---------------------------------------------------------------------------
+ */
+int __init omap_32k_timer_init(void)
+{
+	int ret = -ENODEV;
+
+	if (cpu_is_omap16xx()) {
+		void __iomem *base;
+		struct clk *sync32k_ick;
+
+		base = ioremap(OMAP1_32KSYNC_TIMER_BASE, SZ_1K);
+		if (!base) {
+			pr_err("32k_counter: failed to map base addr\n");
+			return -ENODEV;
+		}
+
+		sync32k_ick = clk_get(NULL, "omap_32ksync_ick");
+		if (!IS_ERR(sync32k_ick))
+			clk_prepare_enable(sync32k_ick);
+
+		ret = omap_init_clocksource_32k(base);
+	}
+
+	if (!ret)
+		omap_init_32k_timer();
+
+	return ret;
+}