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, 156 insertions, 0 deletions

diff --git a/drivers/power/reset/keystone-reset.c b/drivers/power/reset/keystone-reset.c
new file mode 100644
index 000000000..3c44cd6ce
--- /dev/null
+++ b/drivers/power/reset/keystone-reset.c
@@ -0,0 +1,156 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * TI keystone reboot driver
+ *
+ * Copyright (C) 2014 Texas Instruments Incorporated. https://www.ti.com/
+ *
+ * Author: Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>
+ */
+
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/notifier.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/regmap.h>
+#include <linux/mfd/syscon.h>
+#include <linux/of.h>
+
+#define RSCTRL_RG			0x4
+#define RSCFG_RG			0x8
+#define RSISO_RG			0xc
+
+#define RSCTRL_KEY_MASK			0x0000ffff
+#define RSCTRL_RESET_MASK		BIT(16)
+#define RSCTRL_KEY			0x5a69
+
+#define RSMUX_OMODE_MASK		0xe
+#define RSMUX_OMODE_RESET_ON		0xa
+#define RSMUX_OMODE_RESET_OFF		0x0
+#define RSMUX_LOCK_SET			0x1
+
+#define RSCFG_RSTYPE_SOFT		0x300f
+#define RSCFG_RSTYPE_HARD		0x0
+
+#define WDT_MUX_NUMBER			0x4
+
+static int rspll_offset;
+static struct regmap *pllctrl_regs;
+
+/**
+ * rsctrl_enable_rspll_write - enable access to RSCTRL, RSCFG
+ * To be able to access to RSCTRL, RSCFG registers
+ * we have to write a key before
+ */
+static inline int rsctrl_enable_rspll_write(void)
+{
+	return regmap_update_bits(pllctrl_regs, rspll_offset + RSCTRL_RG,
+				  RSCTRL_KEY_MASK, RSCTRL_KEY);
+}
+
+static int rsctrl_restart_handler(struct sys_off_data *data)
+{
+	/* enable write access to RSTCTRL */
+	rsctrl_enable_rspll_write();
+
+	/* reset the SOC */
+	regmap_update_bits(pllctrl_regs, rspll_offset + RSCTRL_RG,
+			   RSCTRL_RESET_MASK, 0);
+
+	return NOTIFY_DONE;
+}
+
+static const struct of_device_id rsctrl_of_match[] = {
+	{.compatible = "ti,keystone-reset", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, rsctrl_of_match);
+
+static int rsctrl_probe(struct platform_device *pdev)
+{
+	int i;
+	int ret;
+	u32 val;
+	unsigned int rg;
+	u32 rsmux_offset;
+	struct regmap *devctrl_regs;
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+
+	if (!np)
+		return -ENODEV;
+
+	/* get regmaps */
+	pllctrl_regs = syscon_regmap_lookup_by_phandle_args(np, "ti,syscon-pll",
+							    1, &rspll_offset);
+	if (IS_ERR(pllctrl_regs))
+		return PTR_ERR(pllctrl_regs);
+
+	devctrl_regs = syscon_regmap_lookup_by_phandle_args(np, "ti,syscon-dev",
+							    1, &rsmux_offset);
+	if (IS_ERR(devctrl_regs))
+		return PTR_ERR(devctrl_regs);
+
+	/* set soft/hard reset */
+	val = of_property_read_bool(np, "ti,soft-reset");
+	val = val ? RSCFG_RSTYPE_SOFT : RSCFG_RSTYPE_HARD;
+
+	ret = rsctrl_enable_rspll_write();
+	if (ret)
+		return ret;
+
+	ret = regmap_write(pllctrl_regs, rspll_offset + RSCFG_RG, val);
+	if (ret)
+		return ret;
+
+	/* disable a reset isolation for all module clocks */
+	ret = regmap_write(pllctrl_regs, rspll_offset + RSISO_RG, 0);
+	if (ret)
+		return ret;
+
+	/* enable a reset for watchdogs from wdt-list */
+	for (i = 0; i < WDT_MUX_NUMBER; i++) {
+		ret = of_property_read_u32_index(np, "ti,wdt-list", i, &val);
+		if (ret == -EOVERFLOW && !i) {
+			dev_err(dev, "ti,wdt-list property has to contain at"
+				"least one entry\n");
+			return -EINVAL;
+		} else if (ret) {
+			break;
+		}
+
+		if (val >= WDT_MUX_NUMBER) {
+			dev_err(dev, "ti,wdt-list property can contain "
+				"only numbers < 4\n");
+			return -EINVAL;
+		}
+
+		rg = rsmux_offset + val * 4;
+
+		ret = regmap_update_bits(devctrl_regs, rg, RSMUX_OMODE_MASK,
+					 RSMUX_OMODE_RESET_ON |
+					 RSMUX_LOCK_SET);
+		if (ret)
+			return ret;
+	}
+
+	ret = devm_register_sys_off_handler(dev, SYS_OFF_MODE_RESTART, 128,
+					    rsctrl_restart_handler, NULL);
+	if (ret)
+		dev_err(dev, "cannot register restart handler (err=%d)\n", ret);
+
+	return ret;
+}
+
+static struct platform_driver rsctrl_driver = {
+	.probe = rsctrl_probe,
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.of_match_table = rsctrl_of_match,
+	},
+};
+module_platform_driver(rsctrl_driver);
+
+MODULE_AUTHOR("Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>");
+MODULE_DESCRIPTION("Texas Instruments keystone reset driver");
+MODULE_ALIAS("platform:" KBUILD_MODNAME);