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, 149 insertions, 0 deletions

diff --git a/drivers/clk/qcom/clk-krait.c b/drivers/clk/qcom/clk-krait.c
new file mode 100644
index 000000000..5e4408b74
--- /dev/null
+++ b/drivers/clk/qcom/clk-krait.c
@@ -0,0 +1,149 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018, The Linux Foundation. All rights reserved.
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/clk-provider.h>
+#include <linux/spinlock.h>
+
+#include <asm/krait-l2-accessors.h>
+
+#include "clk-krait.h"
+
+/* Secondary and primary muxes share the same cp15 register */
+static DEFINE_SPINLOCK(krait_clock_reg_lock);
+
+#define LPL_SHIFT	8
+#define SECCLKAGD	BIT(4)
+
+static void __krait_mux_set_sel(struct krait_mux_clk *mux, int sel)
+{
+	unsigned long flags;
+	u32 regval;
+
+	spin_lock_irqsave(&krait_clock_reg_lock, flags);
+
+	regval = krait_get_l2_indirect_reg(mux->offset);
+
+	/* apq/ipq8064 Errata: disable sec_src clock gating during switch. */
+	if (mux->disable_sec_src_gating) {
+		regval |= SECCLKAGD;
+		krait_set_l2_indirect_reg(mux->offset, regval);
+	}
+
+	regval &= ~(mux->mask << mux->shift);
+	regval |= (sel & mux->mask) << mux->shift;
+	if (mux->lpl) {
+		regval &= ~(mux->mask << (mux->shift + LPL_SHIFT));
+		regval |= (sel & mux->mask) << (mux->shift + LPL_SHIFT);
+	}
+	krait_set_l2_indirect_reg(mux->offset, regval);
+
+	/* apq/ipq8064 Errata: re-enabled sec_src clock gating. */
+	if (mux->disable_sec_src_gating) {
+		regval &= ~SECCLKAGD;
+		krait_set_l2_indirect_reg(mux->offset, regval);
+	}
+
+	/* Wait for switch to complete. */
+	mb();
+	udelay(1);
+
+	/*
+	 * Unlock now to make sure the mux register is not
+	 * modified while switching to the new parent.
+	 */
+	spin_unlock_irqrestore(&krait_clock_reg_lock, flags);
+}
+
+static int krait_mux_set_parent(struct clk_hw *hw, u8 index)
+{
+	struct krait_mux_clk *mux = to_krait_mux_clk(hw);
+	u32 sel;
+
+	sel = clk_mux_index_to_val(mux->parent_map, 0, index);
+	mux->en_mask = sel;
+	/* Don't touch mux if CPU is off as it won't work */
+	if (clk_hw_is_enabled(hw))
+		__krait_mux_set_sel(mux, sel);
+
+	mux->reparent = true;
+
+	return 0;
+}
+
+static u8 krait_mux_get_parent(struct clk_hw *hw)
+{
+	struct krait_mux_clk *mux = to_krait_mux_clk(hw);
+	u32 sel;
+
+	sel = krait_get_l2_indirect_reg(mux->offset);
+	sel >>= mux->shift;
+	sel &= mux->mask;
+	mux->en_mask = sel;
+
+	return clk_mux_val_to_index(hw, mux->parent_map, 0, sel);
+}
+
+const struct clk_ops krait_mux_clk_ops = {
+	.set_parent = krait_mux_set_parent,
+	.get_parent = krait_mux_get_parent,
+	.determine_rate = __clk_mux_determine_rate_closest,
+};
+EXPORT_SYMBOL_GPL(krait_mux_clk_ops);
+
+/* The divider can divide by 2, 4, 6 and 8. But we only really need div-2. */
+static int krait_div2_determine_rate(struct clk_hw *hw, struct clk_rate_request *req)
+{
+	req->best_parent_rate = clk_hw_round_rate(clk_hw_get_parent(hw), req->rate * 2);
+	req->rate = DIV_ROUND_UP(req->best_parent_rate, 2);
+	return 0;
+}
+
+static int krait_div2_set_rate(struct clk_hw *hw, unsigned long rate,
+			       unsigned long parent_rate)
+{
+	struct krait_div2_clk *d = to_krait_div2_clk(hw);
+	unsigned long flags;
+	u32 val;
+	u32 mask = BIT(d->width) - 1;
+
+	if (d->lpl)
+		mask = mask << (d->shift + LPL_SHIFT) | mask << d->shift;
+	else
+		mask <<= d->shift;
+
+	spin_lock_irqsave(&krait_clock_reg_lock, flags);
+	val = krait_get_l2_indirect_reg(d->offset);
+	val &= ~mask;
+	krait_set_l2_indirect_reg(d->offset, val);
+	spin_unlock_irqrestore(&krait_clock_reg_lock, flags);
+
+	return 0;
+}
+
+static unsigned long
+krait_div2_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
+{
+	struct krait_div2_clk *d = to_krait_div2_clk(hw);
+	u32 mask = BIT(d->width) - 1;
+	u32 div;
+
+	div = krait_get_l2_indirect_reg(d->offset);
+	div >>= d->shift;
+	div &= mask;
+	div = (div + 1) * 2;
+
+	return DIV_ROUND_UP(parent_rate, div);
+}
+
+const struct clk_ops krait_div2_clk_ops = {
+	.determine_rate = krait_div2_determine_rate,
+	.set_rate = krait_div2_set_rate,
+	.recalc_rate = krait_div2_recalc_rate,
+};
+EXPORT_SYMBOL_GPL(krait_div2_clk_ops);