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, 208 insertions, 0 deletions

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);