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>

3 files changed, 325 insertions, 0 deletions

diff --git a/drivers/tc/Makefile b/drivers/tc/Makefile
new file mode 100644
index 000000000..6cccaf1f6
--- /dev/null
+++ b/drivers/tc/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Makefile for the linux kernel.
+#
+
+# Object file lists.
+
+obj-$(CONFIG_TC) += tc.o tc-driver.o
diff --git a/drivers/tc/tc-driver.c b/drivers/tc/tc-driver.c
new file mode 100644
index 000000000..2f6d14759
--- /dev/null
+++ b/drivers/tc/tc-driver.c
@@ -0,0 +1,109 @@
+/*
+ *	TURBOchannel driver services.
+ *
+ *	Copyright (c) 2005  James Simmons
+ *	Copyright (c) 2006  Maciej W. Rozycki
+ *
+ *	Loosely based on drivers/dio/dio-driver.c and
+ *	drivers/pci/pci-driver.c.
+ *
+ *	This file is subject to the terms and conditions of the GNU
+ *	General Public License.  See the file "COPYING" in the main
+ *	directory of this archive for more details.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/tc.h>
+
+/**
+ * tc_register_driver - register a new TC driver
+ * @drv: the driver structure to register
+ *
+ * Adds the driver structure to the list of registered drivers
+ * Returns a negative value on error, otherwise 0.
+ * If no error occurred, the driver remains registered even if
+ * no device was claimed during registration.
+ */
+int tc_register_driver(struct tc_driver *tdrv)
+{
+	return driver_register(&tdrv->driver);
+}
+EXPORT_SYMBOL(tc_register_driver);
+
+/**
+ * tc_unregister_driver - unregister a TC driver
+ * @drv: the driver structure to unregister
+ *
+ * Deletes the driver structure from the list of registered TC drivers,
+ * gives it a chance to clean up by calling its remove() function for
+ * each device it was responsible for, and marks those devices as
+ * driverless.
+ */
+void tc_unregister_driver(struct tc_driver *tdrv)
+{
+	driver_unregister(&tdrv->driver);
+}
+EXPORT_SYMBOL(tc_unregister_driver);
+
+/**
+ * tc_match_device - tell if a TC device structure has a matching
+ *                   TC device ID structure
+ * @tdrv: the TC driver to earch for matching TC device ID strings
+ * @tdev: the TC device structure to match against
+ *
+ * Used by a driver to check whether a TC device present in the
+ * system is in its list of supported devices.  Returns the matching
+ * tc_device_id structure or %NULL if there is no match.
+ */
+static const struct tc_device_id *tc_match_device(const struct tc_driver *tdrv,
+						  struct tc_dev *tdev)
+{
+	const struct tc_device_id *id = tdrv->id_table;
+
+	if (id) {
+		while (id->name[0] || id->vendor[0]) {
+			if (strcmp(tdev->name, id->name) == 0 &&
+			    strcmp(tdev->vendor, id->vendor) == 0)
+				return id;
+			id++;
+		}
+	}
+	return NULL;
+}
+
+/**
+ * tc_bus_match - Tell if a device structure has a matching
+ *                TC device ID structure
+ * @dev: the device structure to match against
+ * @drv: the device driver to search for matching TC device ID strings
+ *
+ * Used by a driver to check whether a TC device present in the
+ * system is in its list of supported devices.  Returns 1 if there
+ * is a match or 0 otherwise.
+ */
+static int tc_bus_match(struct device *dev, const struct device_driver *drv)
+{
+	struct tc_dev *tdev = to_tc_dev(dev);
+	const struct tc_driver *tdrv = to_tc_driver(drv);
+	const struct tc_device_id *id;
+
+	id = tc_match_device(tdrv, tdev);
+	if (id)
+		return 1;
+
+	return 0;
+}
+
+const struct bus_type tc_bus_type = {
+	.name	= "tc",
+	.match	= tc_bus_match,
+};
+EXPORT_SYMBOL(tc_bus_type);
+
+static int __init tc_driver_init(void)
+{
+	return bus_register(&tc_bus_type);
+}
+
+postcore_initcall(tc_driver_init);
diff --git a/drivers/tc/tc.c b/drivers/tc/tc.c
new file mode 100644
index 000000000..ebc835cf1
--- /dev/null
+++ b/drivers/tc/tc.c
@@ -0,0 +1,208 @@
+/*
+ *	TURBOchannel bus services.
+ *
+ *	Copyright (c) Harald Koerfgen, 1998
+ *	Copyright (c) 2001, 2003, 2005, 2006, 2018  Maciej W. Rozycki
+ *	Copyright (c) 2005  James Simmons
+ *
+ *	This file is subject to the terms and conditions of the GNU
+ *	General Public License.  See the file "COPYING" in the main
+ *	directory of this archive for more details.
+ */
+#include <linux/compiler.h>
+#include <linux/dma-mapping.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/ioport.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/tc.h>
+#include <linux/types.h>
+
+#include <asm/io.h>
+
+static struct tc_bus tc_bus = {
+	.name = "TURBOchannel",
+};
+
+/*
+ * Probing for TURBOchannel modules.
+ */
+static void __init tc_bus_add_devices(struct tc_bus *tbus)
+{
+	resource_size_t slotsize = tbus->info.slot_size << 20;
+	resource_size_t extslotsize = tbus->ext_slot_size;
+	resource_size_t slotaddr;
+	resource_size_t extslotaddr;
+	resource_size_t devsize;
+	void __iomem *module;
+	struct tc_dev *tdev;
+	int i, slot, err;
+	u8 pattern[4];
+	long offset;
+
+	for (slot = 0; slot < tbus->num_tcslots; slot++) {
+		slotaddr = tbus->slot_base + slot * slotsize;
+		extslotaddr = tbus->ext_slot_base + slot * extslotsize;
+		module = ioremap(slotaddr, slotsize);
+		BUG_ON(!module);
+
+		offset = TC_OLDCARD;
+
+		err = 0;
+		err |= tc_preadb(pattern + 0, module + offset + TC_PATTERN0);
+		err |= tc_preadb(pattern + 1, module + offset + TC_PATTERN1);
+		err |= tc_preadb(pattern + 2, module + offset + TC_PATTERN2);
+		err |= tc_preadb(pattern + 3, module + offset + TC_PATTERN3);
+		if (err)
+			goto out_err;
+
+		if (pattern[0] != 0x55 || pattern[1] != 0x00 ||
+		    pattern[2] != 0xaa || pattern[3] != 0xff) {
+			offset = TC_NEWCARD;
+
+			err = 0;
+			err |= tc_preadb(pattern + 0,
+					 module + offset + TC_PATTERN0);
+			err |= tc_preadb(pattern + 1,
+					 module + offset + TC_PATTERN1);
+			err |= tc_preadb(pattern + 2,
+					 module + offset + TC_PATTERN2);
+			err |= tc_preadb(pattern + 3,
+					 module + offset + TC_PATTERN3);
+			if (err)
+				goto out_err;
+		}
+
+		if (pattern[0] != 0x55 || pattern[1] != 0x00 ||
+		    pattern[2] != 0xaa || pattern[3] != 0xff)
+			goto out_err;
+
+		/* Found a board, allocate it an entry in the list */
+		tdev = kzalloc_obj(*tdev);
+		if (!tdev) {
+			pr_err("tc%x: unable to allocate tc_dev\n", slot);
+			goto out_err;
+		}
+		dev_set_name(&tdev->dev, "tc%x", slot);
+		tdev->bus = tbus;
+		tdev->dev.parent = &tbus->dev;
+		tdev->dev.bus = &tc_bus_type;
+		tdev->slot = slot;
+
+		/* TURBOchannel has 34-bit DMA addressing (16GiB space). */
+		tdev->dma_mask = DMA_BIT_MASK(34);
+		tdev->dev.dma_mask = &tdev->dma_mask;
+		tdev->dev.coherent_dma_mask = DMA_BIT_MASK(34);
+
+		for (i = 0; i < 8; i++) {
+			tdev->firmware[i] =
+				readb(module + offset + TC_FIRM_VER + 4 * i);
+			tdev->vendor[i] =
+				readb(module + offset + TC_VENDOR + 4 * i);
+			tdev->name[i] =
+				readb(module + offset + TC_MODULE + 4 * i);
+		}
+		tdev->firmware[8] = 0;
+		tdev->vendor[8] = 0;
+		tdev->name[8] = 0;
+
+		pr_info("%s: %s %s %s\n", dev_name(&tdev->dev), tdev->vendor,
+			tdev->name, tdev->firmware);
+
+		devsize = readb(module + offset + TC_SLOT_SIZE);
+		devsize <<= 22;
+		if (devsize <= slotsize) {
+			tdev->resource.start = slotaddr;
+			tdev->resource.end = slotaddr + devsize - 1;
+		} else if (devsize <= extslotsize) {
+			tdev->resource.start = extslotaddr;
+			tdev->resource.end = extslotaddr + devsize - 1;
+		} else {
+			pr_err("%s: Cannot provide slot space "
+			       "(%ldMiB required, up to %ldMiB supported)\n",
+			       dev_name(&tdev->dev), (long)(devsize >> 20),
+			       (long)(max(slotsize, extslotsize) >> 20));
+			kfree(tdev);
+			goto out_err;
+		}
+		tdev->resource.name = tdev->name;
+		tdev->resource.flags = IORESOURCE_MEM;
+
+		tc_device_get_irq(tdev);
+
+		if (device_register(&tdev->dev)) {
+			put_device(&tdev->dev);
+			goto out_err;
+		}
+		list_add_tail(&tdev->node, &tbus->devices);
+
+out_err:
+		iounmap(module);
+	}
+}
+
+/*
+ * The main entry.
+ */
+static int __init tc_init(void)
+{
+	/* Initialize the TURBOchannel bus */
+	if (tc_bus_get_info(&tc_bus))
+		goto out_err;
+
+	INIT_LIST_HEAD(&tc_bus.devices);
+	dev_set_name(&tc_bus.dev, "tc");
+	if (device_register(&tc_bus.dev))
+		goto out_err_device;
+
+	if (tc_bus.info.slot_size) {
+		unsigned int tc_clock = tc_get_speed(&tc_bus) / 100000;
+
+		pr_info("tc: TURBOchannel rev. %d at %u.%u MHz "
+			"(with%s parity)\n", tc_bus.info.revision,
+			tc_clock / 10, tc_clock % 10,
+			tc_bus.info.parity ? "" : "out");
+
+		tc_bus.resource[0].start = tc_bus.slot_base;
+		tc_bus.resource[0].end = tc_bus.slot_base +
+					 (tc_bus.info.slot_size << 20) *
+					 tc_bus.num_tcslots - 1;
+		tc_bus.resource[0].name = tc_bus.name;
+		tc_bus.resource[0].flags = IORESOURCE_MEM;
+		if (request_resource(&iomem_resource,
+				     &tc_bus.resource[0]) < 0) {
+			pr_err("tc: Cannot reserve resource\n");
+			goto out_err_device;
+		}
+		if (tc_bus.ext_slot_size) {
+			tc_bus.resource[1].start = tc_bus.ext_slot_base;
+			tc_bus.resource[1].end = tc_bus.ext_slot_base +
+						 tc_bus.ext_slot_size *
+						 tc_bus.num_tcslots - 1;
+			tc_bus.resource[1].name = tc_bus.name;
+			tc_bus.resource[1].flags = IORESOURCE_MEM;
+			if (request_resource(&iomem_resource,
+					     &tc_bus.resource[1]) < 0) {
+				pr_err("tc: Cannot reserve resource\n");
+				goto out_err_resource;
+			}
+		}
+
+		tc_bus_add_devices(&tc_bus);
+	}
+
+	return 0;
+
+out_err_resource:
+	release_resource(&tc_bus.resource[0]);
+out_err_device:
+	put_device(&tc_bus.dev);
+out_err:
+	return 0;
+}
+
+subsys_initcall(tc_init);