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, 151 insertions, 0 deletions

diff --git a/drivers/power/reset/ocelot-reset.c b/drivers/power/reset/ocelot-reset.c
new file mode 100644
index 000000000..9d4b8afb6
--- /dev/null
+++ b/drivers/power/reset/ocelot-reset.c
@@ -0,0 +1,151 @@
+// SPDX-License-Identifier: (GPL-2.0 OR MIT)
+/*
+ * Microsemi MIPS SoC reset driver
+ *
+ * License: Dual MIT/GPL
+ * Copyright (c) 2017 Microsemi Corporation
+ */
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/notifier.h>
+#include <linux/mfd/syscon.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/reboot.h>
+#include <linux/regmap.h>
+
+struct reset_props {
+	const char *syscon;
+	u32 protect_reg;
+	u32 vcore_protect;
+	u32 if_si_owner_bit;
+};
+
+struct ocelot_reset_context {
+	void __iomem *base;
+	struct regmap *cpu_ctrl;
+	const struct reset_props *props;
+	struct notifier_block restart_handler;
+};
+
+#define BIT_OFF_INVALID				32
+
+#define SOFT_CHIP_RST BIT(0)
+
+#define ICPU_CFG_CPU_SYSTEM_CTRL_GENERAL_CTRL	0x24
+#define IF_SI_OWNER_MASK			GENMASK(1, 0)
+#define IF_SI_OWNER_SISL			0
+#define IF_SI_OWNER_SIBM			1
+#define IF_SI_OWNER_SIMC			2
+
+static int ocelot_restart_handle(struct notifier_block *this,
+				 unsigned long mode, void *cmd)
+{
+	struct ocelot_reset_context *ctx = container_of(this, struct
+							ocelot_reset_context,
+							restart_handler);
+	u32 if_si_owner_bit = ctx->props->if_si_owner_bit;
+
+	/* Make sure the core is not protected from reset */
+	regmap_update_bits(ctx->cpu_ctrl, ctx->props->protect_reg,
+			   ctx->props->vcore_protect, 0);
+
+	/* Make the SI back to boot mode */
+	if (if_si_owner_bit != BIT_OFF_INVALID)
+		regmap_update_bits(ctx->cpu_ctrl,
+				   ICPU_CFG_CPU_SYSTEM_CTRL_GENERAL_CTRL,
+				   IF_SI_OWNER_MASK << if_si_owner_bit,
+				   IF_SI_OWNER_SIBM << if_si_owner_bit);
+
+	pr_emerg("Resetting SoC\n");
+
+	writel(SOFT_CHIP_RST, ctx->base);
+
+	pr_emerg("Unable to restart system\n");
+	return NOTIFY_DONE;
+}
+
+static int ocelot_reset_probe(struct platform_device *pdev)
+{
+	struct ocelot_reset_context *ctx;
+	struct device *dev = &pdev->dev;
+	int err;
+
+	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
+	if (!ctx)
+		return -ENOMEM;
+
+	ctx->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(ctx->base))
+		return PTR_ERR(ctx->base);
+
+	ctx->props = device_get_match_data(dev);
+
+	ctx->cpu_ctrl = syscon_regmap_lookup_by_compatible(ctx->props->syscon);
+	if (IS_ERR(ctx->cpu_ctrl)) {
+		dev_err(dev, "No syscon map: %s\n", ctx->props->syscon);
+		return PTR_ERR(ctx->cpu_ctrl);
+	}
+
+	ctx->restart_handler.notifier_call = ocelot_restart_handle;
+	ctx->restart_handler.priority = 192;
+	err = register_restart_handler(&ctx->restart_handler);
+	if (err)
+		dev_err(dev, "can't register restart notifier (err=%d)\n", err);
+
+	return err;
+}
+
+static const struct reset_props reset_props_jaguar2 = {
+	.syscon		 = "mscc,ocelot-cpu-syscon",
+	.protect_reg     = 0x20,
+	.vcore_protect   = BIT(2),
+	.if_si_owner_bit = 6,
+};
+
+static const struct reset_props reset_props_luton = {
+	.syscon		 = "mscc,ocelot-cpu-syscon",
+	.protect_reg     = 0x20,
+	.vcore_protect   = BIT(2),
+	.if_si_owner_bit = BIT_OFF_INVALID, /* n/a */
+};
+
+static const struct reset_props reset_props_ocelot = {
+	.syscon		 = "mscc,ocelot-cpu-syscon",
+	.protect_reg     = 0x20,
+	.vcore_protect   = BIT(2),
+	.if_si_owner_bit = 4,
+};
+
+static const struct reset_props reset_props_sparx5 = {
+	.syscon		 = "microchip,sparx5-cpu-syscon",
+	.protect_reg     = 0x84,
+	.vcore_protect   = BIT(10),
+	.if_si_owner_bit = 6,
+};
+
+static const struct of_device_id ocelot_reset_of_match[] = {
+	{
+		.compatible = "mscc,jaguar2-chip-reset",
+		.data = &reset_props_jaguar2
+	}, {
+		.compatible = "mscc,luton-chip-reset",
+		.data = &reset_props_luton
+	}, {
+		.compatible = "mscc,ocelot-chip-reset",
+		.data = &reset_props_ocelot
+	}, {
+		.compatible = "microchip,sparx5-chip-reset",
+		.data = &reset_props_sparx5
+	},
+	{ /*sentinel*/ }
+};
+
+static struct platform_driver ocelot_reset_driver = {
+	.probe = ocelot_reset_probe,
+	.driver = {
+		.name = "ocelot-chip-reset",
+		.of_match_table = ocelot_reset_of_match,
+	},
+};
+builtin_platform_driver(ocelot_reset_driver);