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, 175 insertions, 0 deletions

diff --git a/drivers/acpi/acpica/hwtimer.c b/drivers/acpi/acpica/hwtimer.c
new file mode 100644
index 000000000..c08bbaa95
--- /dev/null
+++ b/drivers/acpi/acpica/hwtimer.c
@@ -0,0 +1,175 @@
+// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
+/******************************************************************************
+ *
+ * Name: hwtimer.c - ACPI Power Management Timer Interface
+ *
+ * Copyright (C) 2000 - 2026, Intel Corp.
+ *
+ *****************************************************************************/
+
+#define EXPORT_ACPI_INTERFACES
+
+#include <acpi/acpi.h>
+#include "accommon.h"
+
+#define _COMPONENT          ACPI_HARDWARE
+ACPI_MODULE_NAME("hwtimer")
+
+#if (!ACPI_REDUCED_HARDWARE)	/* Entire module */
+/******************************************************************************
+ *
+ * FUNCTION:    acpi_get_timer_resolution
+ *
+ * PARAMETERS:  resolution          - Where the resolution is returned
+ *
+ * RETURN:      Status and timer resolution
+ *
+ * DESCRIPTION: Obtains resolution of the ACPI PM Timer (24 or 32 bits).
+ *
+ ******************************************************************************/
+acpi_status acpi_get_timer_resolution(u32 * resolution)
+{
+	ACPI_FUNCTION_TRACE(acpi_get_timer_resolution);
+
+	if (!resolution) {
+		return_ACPI_STATUS(AE_BAD_PARAMETER);
+	}
+
+	if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) {
+		*resolution = 24;
+	} else {
+		*resolution = 32;
+	}
+
+	return_ACPI_STATUS(AE_OK);
+}
+
+ACPI_EXPORT_SYMBOL(acpi_get_timer_resolution)
+
+/******************************************************************************
+ *
+ * FUNCTION:    acpi_get_timer
+ *
+ * PARAMETERS:  ticks               - Where the timer value is returned
+ *
+ * RETURN:      Status and current timer value (ticks)
+ *
+ * DESCRIPTION: Obtains current value of ACPI PM Timer (in ticks).
+ *
+ ******************************************************************************/
+acpi_status acpi_get_timer(u32 * ticks)
+{
+	acpi_status status;
+	u64 timer_value;
+
+	ACPI_FUNCTION_TRACE(acpi_get_timer);
+
+	if (!ticks) {
+		return_ACPI_STATUS(AE_BAD_PARAMETER);
+	}
+
+	/* ACPI 5.0A: PM Timer is optional */
+
+	if (!acpi_gbl_FADT.xpm_timer_block.address) {
+		return_ACPI_STATUS(AE_SUPPORT);
+	}
+
+	status = acpi_hw_read(&timer_value, &acpi_gbl_FADT.xpm_timer_block);
+	if (ACPI_SUCCESS(status)) {
+
+		/* ACPI PM Timer is defined to be 32 bits (PM_TMR_LEN) */
+
+		*ticks = (u32)timer_value;
+	}
+
+	return_ACPI_STATUS(status);
+}
+
+ACPI_EXPORT_SYMBOL(acpi_get_timer)
+
+/******************************************************************************
+ *
+ * FUNCTION:    acpi_get_timer_duration
+ *
+ * PARAMETERS:  start_ticks         - Starting timestamp
+ *              end_ticks           - End timestamp
+ *              time_elapsed        - Where the elapsed time is returned
+ *
+ * RETURN:      Status and time_elapsed
+ *
+ * DESCRIPTION: Computes the time elapsed (in microseconds) between two
+ *              PM Timer time stamps, taking into account the possibility of
+ *              rollovers, the timer resolution, and timer frequency.
+ *
+ *              The PM Timer's clock ticks at roughly 3.6 times per
+ *              _microsecond_, and its clock continues through Cx state
+ *              transitions (unlike many CPU timestamp counters) -- making it
+ *              a versatile and accurate timer.
+ *
+ *              Note that this function accommodates only a single timer
+ *              rollover. Thus for 24-bit timers, this function should only
+ *              be used for calculating durations less than ~4.6 seconds
+ *              (~20 minutes for 32-bit timers) -- calculations below:
+ *
+ *              2**24 Ticks / 3,600,000 Ticks/Sec = 4.66 sec
+ *              2**32 Ticks / 3,600,000 Ticks/Sec = 1193 sec or 19.88 minutes
+ *
+ ******************************************************************************/
+acpi_status
+acpi_get_timer_duration(u32 start_ticks, u32 end_ticks, u32 *time_elapsed)
+{
+	acpi_status status;
+	u64 delta_ticks;
+	u64 quotient;
+
+	ACPI_FUNCTION_TRACE(acpi_get_timer_duration);
+
+	if (!time_elapsed) {
+		return_ACPI_STATUS(AE_BAD_PARAMETER);
+	}
+
+	/* ACPI 5.0A: PM Timer is optional */
+
+	if (!acpi_gbl_FADT.xpm_timer_block.address) {
+		return_ACPI_STATUS(AE_SUPPORT);
+	}
+
+	if (start_ticks == end_ticks) {
+		*time_elapsed = 0;
+		return_ACPI_STATUS(AE_OK);
+	}
+
+	/*
+	 * Compute Tick Delta:
+	 * Handle (max one) timer rollovers on 24-bit versus 32-bit timers.
+	 */
+	delta_ticks = end_ticks;
+	if (start_ticks > end_ticks) {
+		if ((acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER) == 0) {
+
+			/* 24-bit Timer */
+
+			delta_ticks |= (u64)1 << 24;
+		} else {
+			/* 32-bit Timer */
+
+			delta_ticks |= (u64)1 << 32;
+		}
+	}
+	delta_ticks -= start_ticks;
+
+	/*
+	 * Compute Duration (Requires a 64-bit multiply and divide):
+	 *
+	 * time_elapsed (microseconds) =
+	 *  (delta_ticks * ACPI_USEC_PER_SEC) / ACPI_PM_TIMER_FREQUENCY;
+	 */
+	status = acpi_ut_short_divide(delta_ticks * ACPI_USEC_PER_SEC,
+				      ACPI_PM_TIMER_FREQUENCY, &quotient, NULL);
+
+	*time_elapsed = (u32)quotient;
+	return_ACPI_STATUS(status);
+}
+
+ACPI_EXPORT_SYMBOL(acpi_get_timer_duration)
+#endif				/* !ACPI_REDUCED_HARDWARE */