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, 79 insertions, 0 deletions

diff --git a/drivers/power/reset/axxia-reset.c b/drivers/power/reset/axxia-reset.c
new file mode 100644
index 000000000..797bf6773
--- /dev/null
+++ b/drivers/power/reset/axxia-reset.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Reset driver for Axxia devices
+ *
+ * Copyright (C) 2014 LSI
+ */
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/notifier.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/regmap.h>
+
+#define SC_CRIT_WRITE_KEY	0x1000
+#define SC_LATCH_ON_RESET	0x1004
+#define SC_RESET_CONTROL	0x1008
+#define   RSTCTL_RST_ZERO	(1<<3)
+#define   RSTCTL_RST_FAB	(1<<2)
+#define   RSTCTL_RST_CHIP	(1<<1)
+#define   RSTCTL_RST_SYS	(1<<0)
+#define SC_EFUSE_INT_STATUS	0x180c
+#define   EFUSE_READ_DONE	(1<<31)
+
+static int axxia_restart_handler(struct sys_off_data *data)
+{
+	struct regmap *syscon = data->cb_data;
+
+	/* Access Key (0xab) */
+	regmap_write(syscon, SC_CRIT_WRITE_KEY, 0xab);
+	/* Select internal boot from 0xffff0000 */
+	regmap_write(syscon, SC_LATCH_ON_RESET, 0x00000040);
+	/* Assert ResetReadDone (to avoid hanging in boot ROM) */
+	regmap_write(syscon, SC_EFUSE_INT_STATUS, EFUSE_READ_DONE);
+	/* Assert chip reset */
+	regmap_update_bits(syscon, SC_RESET_CONTROL,
+			   RSTCTL_RST_CHIP, RSTCTL_RST_CHIP);
+
+	return NOTIFY_DONE;
+}
+
+static int axxia_reset_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct regmap *syscon;
+	int err;
+
+	syscon = syscon_regmap_lookup_by_phandle(dev->of_node, "syscon");
+	if (IS_ERR(syscon)) {
+		pr_err("%pOFn: syscon lookup failed\n", dev->of_node);
+		return PTR_ERR(syscon);
+	}
+
+	err = devm_register_sys_off_handler(&pdev->dev, SYS_OFF_MODE_RESTART,
+					    128, axxia_restart_handler, syscon);
+	if (err)
+		dev_err(dev, "cannot register restart handler (err=%d)\n", err);
+
+	return err;
+}
+
+static const struct of_device_id of_axxia_reset_match[] = {
+	{ .compatible = "lsi,axm55xx-reset", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, of_axxia_reset_match);
+
+static struct platform_driver axxia_reset_driver = {
+	.probe = axxia_reset_probe,
+	.driver = {
+		.name = "axxia-reset",
+		.of_match_table = of_match_ptr(of_axxia_reset_match),
+	},
+};
+builtin_platform_driver(axxia_reset_driver);