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, 226 insertions, 0 deletions

diff --git a/drivers/clk/ux500/clk-sysctrl.c b/drivers/clk/ux500/clk-sysctrl.c
new file mode 100644
index 000000000..ba3258c88
--- /dev/null
+++ b/drivers/clk/ux500/clk-sysctrl.c
@@ -0,0 +1,226 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Sysctrl clock implementation for ux500 platform.
+ *
+ * Copyright (C) 2013 ST-Ericsson SA
+ * Author: Ulf Hansson <ulf.hansson@linaro.org>
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/mfd/abx500/ab8500-sysctrl.h>
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/err.h>
+#include "clk.h"
+
+#define SYSCTRL_MAX_NUM_PARENTS 4
+
+#define to_clk_sysctrl(_hw) container_of(_hw, struct clk_sysctrl, hw)
+
+struct clk_sysctrl {
+	struct clk_hw hw;
+	struct device *dev;
+	u8 parent_index;
+	u16 reg_sel[SYSCTRL_MAX_NUM_PARENTS];
+	u8 reg_mask[SYSCTRL_MAX_NUM_PARENTS];
+	u8 reg_bits[SYSCTRL_MAX_NUM_PARENTS];
+	unsigned long rate;
+	unsigned long enable_delay_us;
+};
+
+/* Sysctrl clock operations. */
+
+static int clk_sysctrl_prepare(struct clk_hw *hw)
+{
+	int ret;
+	struct clk_sysctrl *clk = to_clk_sysctrl(hw);
+
+	ret = ab8500_sysctrl_write(clk->reg_sel[0], clk->reg_mask[0],
+				clk->reg_bits[0]);
+
+	if (!ret && clk->enable_delay_us)
+		usleep_range(clk->enable_delay_us, clk->enable_delay_us +
+			     (clk->enable_delay_us >> 2));
+
+	return ret;
+}
+
+static void clk_sysctrl_unprepare(struct clk_hw *hw)
+{
+	struct clk_sysctrl *clk = to_clk_sysctrl(hw);
+	if (ab8500_sysctrl_clear(clk->reg_sel[0], clk->reg_mask[0]))
+		dev_err(clk->dev, "clk_sysctrl: %s fail to clear %s.\n",
+			__func__, clk_hw_get_name(hw));
+}
+
+static unsigned long clk_sysctrl_recalc_rate(struct clk_hw *hw,
+					unsigned long parent_rate)
+{
+	struct clk_sysctrl *clk = to_clk_sysctrl(hw);
+	return clk->rate;
+}
+
+static int clk_sysctrl_set_parent(struct clk_hw *hw, u8 index)
+{
+	struct clk_sysctrl *clk = to_clk_sysctrl(hw);
+	u8 old_index = clk->parent_index;
+	int ret = 0;
+
+	if (clk->reg_sel[old_index]) {
+		ret = ab8500_sysctrl_clear(clk->reg_sel[old_index],
+					clk->reg_mask[old_index]);
+		if (ret)
+			return ret;
+	}
+
+	if (clk->reg_sel[index]) {
+		ret = ab8500_sysctrl_write(clk->reg_sel[index],
+					clk->reg_mask[index],
+					clk->reg_bits[index]);
+		if (ret) {
+			if (clk->reg_sel[old_index])
+				ab8500_sysctrl_write(clk->reg_sel[old_index],
+						clk->reg_mask[old_index],
+						clk->reg_bits[old_index]);
+			return ret;
+		}
+	}
+	clk->parent_index = index;
+
+	return ret;
+}
+
+static u8 clk_sysctrl_get_parent(struct clk_hw *hw)
+{
+	struct clk_sysctrl *clk = to_clk_sysctrl(hw);
+	return clk->parent_index;
+}
+
+static const struct clk_ops clk_sysctrl_gate_ops = {
+	.prepare = clk_sysctrl_prepare,
+	.unprepare = clk_sysctrl_unprepare,
+};
+
+static const struct clk_ops clk_sysctrl_gate_fixed_rate_ops = {
+	.prepare = clk_sysctrl_prepare,
+	.unprepare = clk_sysctrl_unprepare,
+	.recalc_rate = clk_sysctrl_recalc_rate,
+};
+
+static const struct clk_ops clk_sysctrl_set_parent_ops = {
+	.determine_rate = clk_hw_determine_rate_no_reparent,
+	.set_parent = clk_sysctrl_set_parent,
+	.get_parent = clk_sysctrl_get_parent,
+};
+
+static struct clk *clk_reg_sysctrl(struct device *dev,
+				const char *name,
+				const char **parent_names,
+				u8 num_parents,
+				u16 *reg_sel,
+				u8 *reg_mask,
+				u8 *reg_bits,
+				unsigned long rate,
+				unsigned long enable_delay_us,
+				unsigned long flags,
+				const struct clk_ops *clk_sysctrl_ops)
+{
+	struct clk_sysctrl *clk;
+	struct clk_init_data clk_sysctrl_init;
+	struct clk *clk_reg;
+	int i;
+
+	if (!dev)
+		return ERR_PTR(-EINVAL);
+
+	if (!name || (num_parents > SYSCTRL_MAX_NUM_PARENTS)) {
+		dev_err(dev, "clk_sysctrl: invalid arguments passed\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	clk = devm_kzalloc(dev, sizeof(*clk), GFP_KERNEL);
+	if (!clk)
+		return ERR_PTR(-ENOMEM);
+
+	/* set main clock registers */
+	clk->reg_sel[0] = reg_sel[0];
+	clk->reg_bits[0] = reg_bits[0];
+	clk->reg_mask[0] = reg_mask[0];
+
+	/* handle clocks with more than one parent */
+	for (i = 1; i < num_parents; i++) {
+		clk->reg_sel[i] = reg_sel[i];
+		clk->reg_bits[i] = reg_bits[i];
+		clk->reg_mask[i] = reg_mask[i];
+	}
+
+	clk->parent_index = 0;
+	clk->rate = rate;
+	clk->enable_delay_us = enable_delay_us;
+	clk->dev = dev;
+
+	clk_sysctrl_init.name = name;
+	clk_sysctrl_init.ops = clk_sysctrl_ops;
+	clk_sysctrl_init.flags = flags;
+	clk_sysctrl_init.parent_names = parent_names;
+	clk_sysctrl_init.num_parents = num_parents;
+	clk->hw.init = &clk_sysctrl_init;
+
+	clk_reg = devm_clk_register(clk->dev, &clk->hw);
+	if (IS_ERR(clk_reg))
+		dev_err(dev, "clk_sysctrl: clk_register failed\n");
+
+	return clk_reg;
+}
+
+struct clk *clk_reg_sysctrl_gate(struct device *dev,
+				const char *name,
+				const char *parent_name,
+				u16 reg_sel,
+				u8 reg_mask,
+				u8 reg_bits,
+				unsigned long enable_delay_us,
+				unsigned long flags)
+{
+	const char **parent_names = (parent_name ? &parent_name : NULL);
+	u8 num_parents = (parent_name ? 1 : 0);
+
+	return clk_reg_sysctrl(dev, name, parent_names, num_parents,
+			&reg_sel, &reg_mask, &reg_bits, 0, enable_delay_us,
+			flags, &clk_sysctrl_gate_ops);
+}
+
+struct clk *clk_reg_sysctrl_gate_fixed_rate(struct device *dev,
+					const char *name,
+					const char *parent_name,
+					u16 reg_sel,
+					u8 reg_mask,
+					u8 reg_bits,
+					unsigned long rate,
+					unsigned long enable_delay_us,
+					unsigned long flags)
+{
+	const char **parent_names = (parent_name ? &parent_name : NULL);
+	u8 num_parents = (parent_name ? 1 : 0);
+
+	return clk_reg_sysctrl(dev, name, parent_names, num_parents,
+			&reg_sel, &reg_mask, &reg_bits,
+			rate, enable_delay_us, flags,
+			&clk_sysctrl_gate_fixed_rate_ops);
+}
+
+struct clk *clk_reg_sysctrl_set_parent(struct device *dev,
+				const char *name,
+				const char **parent_names,
+				u8 num_parents,
+				u16 *reg_sel,
+				u8 *reg_mask,
+				u8 *reg_bits,
+				unsigned long flags)
+{
+	return clk_reg_sysctrl(dev, name, parent_names, num_parents,
+			reg_sel, reg_mask, reg_bits, 0, 0, flags,
+			&clk_sysctrl_set_parent_ops);
+}