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, 187 insertions, 0 deletions

diff --git a/drivers/mfd/rohm-bd9576.c b/drivers/mfd/rohm-bd9576.c
new file mode 100644
index 000000000..17323ae39
--- /dev/null
+++ b/drivers/mfd/rohm-bd9576.c
@@ -0,0 +1,187 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2021 ROHM Semiconductors
+ *
+ * ROHM BD9576MUF and BD9573MUF PMIC driver
+ */
+
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/ioport.h>
+#include <linux/irq.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/rohm-bd957x.h>
+#include <linux/mfd/rohm-generic.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+#include <linux/types.h>
+
+enum {
+	BD957X_REGULATOR_CELL,
+	BD957X_WDT_CELL,
+};
+
+/*
+ * Due to the BD9576MUF nasty IRQ behaviour we don't always populate IRQs.
+ * These will be added to regulator resources only if IRQ information for the
+ * PMIC is populated in device-tree.
+ */
+static const struct resource bd9576_regulator_irqs[] = {
+	DEFINE_RES_IRQ_NAMED(BD9576_INT_THERM, "bd9576-temp"),
+	DEFINE_RES_IRQ_NAMED(BD9576_INT_OVD, "bd9576-ovd"),
+	DEFINE_RES_IRQ_NAMED(BD9576_INT_UVD, "bd9576-uvd"),
+};
+
+static struct mfd_cell bd9573_mfd_cells[] = {
+	[BD957X_REGULATOR_CELL]	= { .name = "bd9573-regulator", },
+	[BD957X_WDT_CELL]	= { .name = "bd9576-wdt", },
+};
+
+static struct mfd_cell bd9576_mfd_cells[] = {
+	[BD957X_REGULATOR_CELL]	= { .name = "bd9576-regulator", },
+	[BD957X_WDT_CELL]	= { .name = "bd9576-wdt", },
+};
+
+static const struct regmap_range volatile_ranges[] = {
+	regmap_reg_range(BD957X_REG_SMRB_ASSERT, BD957X_REG_SMRB_ASSERT),
+	regmap_reg_range(BD957X_REG_PMIC_INTERNAL_STAT,
+			 BD957X_REG_PMIC_INTERNAL_STAT),
+	regmap_reg_range(BD957X_REG_INT_THERM_STAT, BD957X_REG_INT_THERM_STAT),
+	regmap_reg_range(BD957X_REG_INT_OVP_STAT, BD957X_REG_INT_SYS_STAT),
+	regmap_reg_range(BD957X_REG_INT_MAIN_STAT, BD957X_REG_INT_MAIN_STAT),
+};
+
+static const struct regmap_access_table volatile_regs = {
+	.yes_ranges = &volatile_ranges[0],
+	.n_yes_ranges = ARRAY_SIZE(volatile_ranges),
+};
+
+static const struct regmap_config bd957x_regmap = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.volatile_table = &volatile_regs,
+	.max_register = BD957X_MAX_REGISTER,
+	.cache_type = REGCACHE_MAPLE,
+};
+
+static const struct regmap_irq bd9576_irqs[] = {
+	REGMAP_IRQ_REG(BD9576_INT_THERM, 0, BD957X_MASK_INT_MAIN_THERM),
+	REGMAP_IRQ_REG(BD9576_INT_OVP, 0, BD957X_MASK_INT_MAIN_OVP),
+	REGMAP_IRQ_REG(BD9576_INT_SCP, 0, BD957X_MASK_INT_MAIN_SCP),
+	REGMAP_IRQ_REG(BD9576_INT_OCP, 0, BD957X_MASK_INT_MAIN_OCP),
+	REGMAP_IRQ_REG(BD9576_INT_OVD, 0, BD957X_MASK_INT_MAIN_OVD),
+	REGMAP_IRQ_REG(BD9576_INT_UVD, 0, BD957X_MASK_INT_MAIN_UVD),
+	REGMAP_IRQ_REG(BD9576_INT_UVP, 0, BD957X_MASK_INT_MAIN_UVP),
+	REGMAP_IRQ_REG(BD9576_INT_SYS, 0, BD957X_MASK_INT_MAIN_SYS),
+};
+
+static const struct regmap_irq_chip bd9576_irq_chip = {
+	.name = "bd9576_irq",
+	.irqs = &bd9576_irqs[0],
+	.num_irqs = ARRAY_SIZE(bd9576_irqs),
+	.status_base = BD957X_REG_INT_MAIN_STAT,
+	.mask_base = BD957X_REG_INT_MAIN_MASK,
+	.ack_base = BD957X_REG_INT_MAIN_STAT,
+	.init_ack_masked = true,
+	.num_regs = 1,
+	.irq_reg_stride = 1,
+};
+
+static int bd957x_i2c_probe(struct i2c_client *i2c)
+{
+	int ret;
+	struct regmap *regmap;
+	struct mfd_cell *cells;
+	int num_cells;
+	unsigned long chip_type;
+	struct irq_domain *domain;
+	bool usable_irqs;
+
+	chip_type = (unsigned long)of_device_get_match_data(&i2c->dev);
+
+	switch (chip_type) {
+	case ROHM_CHIP_TYPE_BD9576:
+		cells = bd9576_mfd_cells;
+		num_cells = ARRAY_SIZE(bd9576_mfd_cells);
+		usable_irqs = !!i2c->irq;
+		break;
+	case ROHM_CHIP_TYPE_BD9573:
+		cells = bd9573_mfd_cells;
+		num_cells = ARRAY_SIZE(bd9573_mfd_cells);
+		/*
+		 * BD9573 only supports fatal IRQs which we can not handle
+		 * because SoC is going to lose the power.
+		 */
+		usable_irqs = false;
+		break;
+	default:
+		dev_err(&i2c->dev, "Unknown device type");
+		return -EINVAL;
+	}
+
+	regmap = devm_regmap_init_i2c(i2c, &bd957x_regmap);
+	if (IS_ERR(regmap))
+		return dev_err_probe(&i2c->dev, PTR_ERR(regmap),
+				     "Failed to initialize Regmap\n");
+
+	/*
+	 * BD9576 behaves badly. It kepts IRQ line asserted for the whole
+	 * duration of detected HW condition (like over temperature). So we
+	 * don't require IRQ to be populated.
+	 * If IRQ information is not given, then we mask all IRQs and do not
+	 * provide IRQ resources to regulator driver - which then just omits
+	 * the notifiers.
+	 */
+	if (usable_irqs) {
+		struct regmap_irq_chip_data *irq_data;
+		struct mfd_cell *regulators;
+
+		regulators = &bd9576_mfd_cells[BD957X_REGULATOR_CELL];
+		regulators->resources = bd9576_regulator_irqs;
+		regulators->num_resources = ARRAY_SIZE(bd9576_regulator_irqs);
+
+		ret = devm_regmap_add_irq_chip(&i2c->dev, regmap, i2c->irq,
+					       IRQF_ONESHOT, 0,
+					       &bd9576_irq_chip, &irq_data);
+		if (ret)
+			return dev_err_probe(&i2c->dev, ret,
+					     "Failed to add IRQ chip\n");
+
+		domain = regmap_irq_get_domain(irq_data);
+	} else {
+		ret = regmap_update_bits(regmap, BD957X_REG_INT_MAIN_MASK,
+					 BD957X_MASK_INT_ALL,
+					 BD957X_MASK_INT_ALL);
+		if (ret)
+			return ret;
+		domain = NULL;
+	}
+
+	ret = devm_mfd_add_devices(&i2c->dev, PLATFORM_DEVID_AUTO, cells,
+				   num_cells, NULL, 0, domain);
+	if (ret)
+		dev_err_probe(&i2c->dev, ret, "Failed to create subdevices\n");
+
+	return ret;
+}
+
+static const struct of_device_id bd957x_of_match[] = {
+	{ .compatible = "rohm,bd9576", .data = (void *)ROHM_CHIP_TYPE_BD9576, },
+	{ .compatible = "rohm,bd9573", .data = (void *)ROHM_CHIP_TYPE_BD9573, },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, bd957x_of_match);
+
+static struct i2c_driver bd957x_drv = {
+	.driver = {
+		.name = "rohm-bd957x",
+		.of_match_table = bd957x_of_match,
+	},
+	.probe = bd957x_i2c_probe,
+};
+module_i2c_driver(bd957x_drv);
+
+MODULE_AUTHOR("Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>");
+MODULE_DESCRIPTION("ROHM BD9576MUF and BD9573MUF Power Management IC driver");
+MODULE_LICENSE("GPL");