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, 136 insertions, 0 deletions

diff --git a/drivers/reset/reset-pistachio.c b/drivers/reset/reset-pistachio.c
new file mode 100644
index 000000000..151ceeb42
--- /dev/null
+++ b/drivers/reset/reset-pistachio.c
@@ -0,0 +1,136 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Pistachio SoC Reset Controller driver
+ *
+ * Copyright (C) 2015 Imagination Technologies Ltd.
+ *
+ * Author: Damien Horsley <Damien.Horsley@imgtec.com>
+ */
+
+#include <linux/init.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/reset-controller.h>
+#include <linux/slab.h>
+#include <linux/mfd/syscon.h>
+
+#include <dt-bindings/reset/pistachio-resets.h>
+
+#define	PISTACHIO_SOFT_RESET		0
+
+struct pistachio_reset_data {
+	struct reset_controller_dev	rcdev;
+	struct regmap			*periph_regs;
+};
+
+static inline int pistachio_reset_shift(unsigned long id)
+{
+	switch (id) {
+	case PISTACHIO_RESET_I2C0:
+	case PISTACHIO_RESET_I2C1:
+	case PISTACHIO_RESET_I2C2:
+	case PISTACHIO_RESET_I2C3:
+	case PISTACHIO_RESET_I2S_IN:
+	case PISTACHIO_RESET_PRL_OUT:
+	case PISTACHIO_RESET_SPDIF_OUT:
+	case PISTACHIO_RESET_SPI:
+	case PISTACHIO_RESET_PWM_PDM:
+	case PISTACHIO_RESET_UART0:
+	case PISTACHIO_RESET_UART1:
+	case PISTACHIO_RESET_QSPI:
+	case PISTACHIO_RESET_MDC:
+	case PISTACHIO_RESET_SDHOST:
+	case PISTACHIO_RESET_ETHERNET:
+	case PISTACHIO_RESET_IR:
+	case PISTACHIO_RESET_HASH:
+	case PISTACHIO_RESET_TIMER:
+		return id;
+	case PISTACHIO_RESET_I2S_OUT:
+	case PISTACHIO_RESET_SPDIF_IN:
+	case PISTACHIO_RESET_EVT:
+		return id + 6;
+	case PISTACHIO_RESET_USB_H:
+	case PISTACHIO_RESET_USB_PR:
+	case PISTACHIO_RESET_USB_PHY_PR:
+	case PISTACHIO_RESET_USB_PHY_PON:
+		return id + 7;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int pistachio_reset_assert(struct reset_controller_dev *rcdev,
+				  unsigned long id)
+{
+	struct pistachio_reset_data *rd;
+	u32 mask;
+	int shift;
+
+	rd = container_of(rcdev, struct pistachio_reset_data, rcdev);
+	shift = pistachio_reset_shift(id);
+	if (shift < 0)
+		return shift;
+	mask = BIT(shift);
+
+	return regmap_update_bits(rd->periph_regs, PISTACHIO_SOFT_RESET,
+				  mask, mask);
+}
+
+static int pistachio_reset_deassert(struct reset_controller_dev *rcdev,
+				    unsigned long id)
+{
+	struct pistachio_reset_data *rd;
+	u32 mask;
+	int shift;
+
+	rd = container_of(rcdev, struct pistachio_reset_data, rcdev);
+	shift = pistachio_reset_shift(id);
+	if (shift < 0)
+		return shift;
+	mask = BIT(shift);
+
+	return regmap_update_bits(rd->periph_regs, PISTACHIO_SOFT_RESET,
+				  mask, 0);
+}
+
+static const struct reset_control_ops pistachio_reset_ops = {
+	.assert		= pistachio_reset_assert,
+	.deassert	= pistachio_reset_deassert,
+};
+
+static int pistachio_reset_probe(struct platform_device *pdev)
+{
+	struct pistachio_reset_data *rd;
+	struct device *dev = &pdev->dev;
+	struct device_node *np = pdev->dev.of_node;
+
+	rd = devm_kzalloc(dev, sizeof(*rd), GFP_KERNEL);
+	if (!rd)
+		return -ENOMEM;
+
+	rd->periph_regs = syscon_node_to_regmap(np->parent);
+	if (IS_ERR(rd->periph_regs))
+		return PTR_ERR(rd->periph_regs);
+
+	rd->rcdev.owner = THIS_MODULE;
+	rd->rcdev.nr_resets = PISTACHIO_RESET_MAX + 1;
+	rd->rcdev.ops = &pistachio_reset_ops;
+	rd->rcdev.of_node = np;
+
+	return devm_reset_controller_register(dev, &rd->rcdev);
+}
+
+static const struct of_device_id pistachio_reset_dt_ids[] = {
+	 { .compatible = "img,pistachio-reset", },
+	 { /* sentinel */ },
+};
+
+static struct platform_driver pistachio_reset_driver = {
+	.probe	= pistachio_reset_probe,
+	.driver = {
+		.name		= "pistachio-reset",
+		.of_match_table	= pistachio_reset_dt_ids,
+	},
+};
+builtin_platform_driver(pistachio_reset_driver);