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, 113 insertions, 0 deletions

diff --git a/drivers/pnp/system.c b/drivers/pnp/system.c
new file mode 100644
index 000000000..bd939b564
--- /dev/null
+++ b/drivers/pnp/system.c
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * system.c - a driver for reserving pnp system resources
+ *
+ * Some code is based on pnpbios_core.c
+ * Copyright 2002 Adam Belay <ambx1@neo.rr.com>
+ * (c) Copyright 2007 Hewlett-Packard Development Company, L.P.
+ *	Bjorn Helgaas <bjorn.helgaas@hp.com>
+ */
+
+#include <linux/pnp.h>
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/ioport.h>
+
+static const struct pnp_device_id pnp_dev_table[] = {
+	/* General ID for reserving resources */
+	{ .id = "PNP0c02" },
+	/* memory controller */
+	{ .id = "PNP0c01" },
+	{ }
+};
+
+static void reserve_range(struct pnp_dev *dev, struct resource *r, int port)
+{
+	char *regionid;
+	const char *pnpid = dev_name(&dev->dev);
+	resource_size_t start = r->start, end = r->end;
+	struct resource *res;
+
+	regionid = kmalloc(16, GFP_KERNEL);
+	if (!regionid)
+		return;
+
+	snprintf(regionid, 16, "pnp %s", pnpid);
+	if (port)
+		res = request_region(start, end - start + 1, regionid);
+	else
+		res = request_mem_region(start, end - start + 1, regionid);
+	if (res)
+		res->flags &= ~IORESOURCE_BUSY;
+	else
+		kfree(regionid);
+
+	/*
+	 * Failures at this point are usually harmless. pci quirks for
+	 * example do reserve stuff they know about too, so we may well
+	 * have double reservations.
+	 */
+	dev_info(&dev->dev, "%pR %s reserved\n", r,
+		 res ? "has been" : "could not be");
+}
+
+static void reserve_resources_of_dev(struct pnp_dev *dev)
+{
+	struct resource *res;
+	int i;
+
+	for (i = 0; (res = pnp_get_resource(dev, IORESOURCE_IO, i)); i++) {
+		if (res->flags & IORESOURCE_DISABLED)
+			continue;
+		if (res->start == 0)
+			continue;	/* disabled */
+		if (res->start < 0x100)
+			/*
+			 * Below 0x100 is only standard PC hardware
+			 * (pics, kbd, timer, dma, ...)
+			 * We should not get resource conflicts there,
+			 * and the kernel reserves these anyway
+			 * (see arch/i386/kernel/setup.c).
+			 * So, do nothing
+			 */
+			continue;
+		if (res->end < res->start)
+			continue;	/* invalid */
+
+		reserve_range(dev, res, 1);
+	}
+
+	for (i = 0; (res = pnp_get_resource(dev, IORESOURCE_MEM, i)); i++) {
+		if (res->flags & IORESOURCE_DISABLED)
+			continue;
+
+		reserve_range(dev, res, 0);
+	}
+}
+
+static int system_pnp_probe(struct pnp_dev *dev,
+			    const struct pnp_device_id *dev_id)
+{
+	reserve_resources_of_dev(dev);
+	return 0;
+}
+
+static struct pnp_driver system_pnp_driver = {
+	.name     = "system",
+	.id_table = pnp_dev_table,
+	.flags    = PNP_DRIVER_RES_DO_NOT_CHANGE,
+	.probe    = system_pnp_probe,
+};
+
+static int __init pnp_system_init(void)
+{
+	return pnp_register_driver(&system_pnp_driver);
+}
+
+/*
+ * Reserve motherboard resources after PCI claim BARs,
+ * but before PCI assign resources for uninitialized PCI devices
+ */
+fs_initcall(pnp_system_init);