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, 284 insertions, 0 deletions

diff --git a/drivers/mtd/maps/pismo.c b/drivers/mtd/maps/pismo.c
new file mode 100644
index 000000000..b0310fddc
--- /dev/null
+++ b/drivers/mtd/maps/pismo.c
@@ -0,0 +1,284 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * PISMO memory driver - http://www.pismoworld.org/
+ *
+ * For ARM Realview and Versatile platforms
+ */
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <linux/mutex.h>
+#include <linux/mtd/physmap.h>
+#include <linux/mtd/plat-ram.h>
+#include <linux/mtd/pismo.h>
+
+#define PISMO_NUM_CS	5
+
+struct pismo_cs_block {
+	u8	type;
+	u8	width;
+	__le16	access;
+	__le32	size;
+	u32	reserved[2];
+	char	device[32];
+} __packed;
+
+struct pismo_eeprom {
+	struct pismo_cs_block cs[PISMO_NUM_CS];
+	char	board[15];
+	u8	sum;
+} __packed;
+
+struct pismo_mem {
+	phys_addr_t base;
+	u32	size;
+	u16	access;
+	u8	width;
+	u8	type;
+};
+
+struct pismo_data {
+	struct i2c_client	*client;
+	void			(*vpp)(void *, int);
+	void			*vpp_data;
+	struct platform_device	*dev[PISMO_NUM_CS];
+};
+
+static void pismo_set_vpp(struct platform_device *pdev, int on)
+{
+	struct i2c_client *client = to_i2c_client(pdev->dev.parent);
+	struct pismo_data *pismo = i2c_get_clientdata(client);
+
+	pismo->vpp(pismo->vpp_data, on);
+}
+
+static unsigned int pismo_width_to_bytes(unsigned int width)
+{
+	width &= 15;
+	if (width > 2)
+		return 0;
+	return 1 << width;
+}
+
+static int pismo_eeprom_read(struct i2c_client *client, void *buf, u8 addr,
+			     size_t size)
+{
+	int ret;
+	struct i2c_msg msg[] = {
+		{
+			.addr = client->addr,
+			.len = sizeof(addr),
+			.buf = &addr,
+		}, {
+			.addr = client->addr,
+			.flags = I2C_M_RD,
+			.len = size,
+			.buf = buf,
+		},
+	};
+
+	ret = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
+
+	return ret == ARRAY_SIZE(msg) ? size : -EIO;
+}
+
+static int pismo_add_device(struct pismo_data *pismo, int i,
+			    struct pismo_mem *region, const char *name,
+			    void *pdata, size_t psize)
+{
+	struct platform_device *dev;
+	struct resource res = { };
+	phys_addr_t base = region->base;
+	int ret;
+
+	if (base == ~0)
+		return -ENXIO;
+
+	res.start = base;
+	res.end = base + region->size - 1;
+	res.flags = IORESOURCE_MEM;
+
+	dev = platform_device_alloc(name, i);
+	if (!dev)
+		return -ENOMEM;
+	dev->dev.parent = &pismo->client->dev;
+
+	do {
+		ret = platform_device_add_resources(dev, &res, 1);
+		if (ret)
+			break;
+
+		ret = platform_device_add_data(dev, pdata, psize);
+		if (ret)
+			break;
+
+		ret = platform_device_add(dev);
+		if (ret)
+			break;
+
+		pismo->dev[i] = dev;
+		return 0;
+	} while (0);
+
+	platform_device_put(dev);
+	return ret;
+}
+
+static int pismo_add_nor(struct pismo_data *pismo, int i,
+			 struct pismo_mem *region)
+{
+	struct physmap_flash_data data = {
+		.width = region->width,
+	};
+
+	if (pismo->vpp)
+		data.set_vpp = pismo_set_vpp;
+
+	return pismo_add_device(pismo, i, region, "physmap-flash",
+		&data, sizeof(data));
+}
+
+static int pismo_add_sram(struct pismo_data *pismo, int i,
+			  struct pismo_mem *region)
+{
+	struct platdata_mtd_ram data = {
+		.bankwidth = region->width,
+	};
+
+	return pismo_add_device(pismo, i, region, "mtd-ram",
+		&data, sizeof(data));
+}
+
+static void pismo_add_one(struct pismo_data *pismo, int i,
+			  const struct pismo_cs_block *cs, phys_addr_t base)
+{
+	struct device *dev = &pismo->client->dev;
+	struct pismo_mem region;
+
+	region.base = base;
+	region.type = cs->type;
+	region.width = pismo_width_to_bytes(cs->width);
+	region.access = le16_to_cpu(cs->access);
+	region.size = le32_to_cpu(cs->size);
+
+	if (region.width == 0) {
+		dev_err(dev, "cs%u: bad width: %02x, ignoring\n", i, cs->width);
+		return;
+	}
+
+	/*
+	 * FIXME: may need to the platforms memory controller here, but at
+	 * the moment we assume that it has already been correctly setup.
+	 * The memory controller can also tell us the base address as well.
+	 */
+
+	dev_info(dev, "cs%u: %.32s: type %02x access %u00ps size %uK\n",
+		i, cs->device, region.type, region.access, region.size / 1024);
+
+	switch (region.type) {
+	case 0:
+		break;
+	case 1:
+		/* static DOC */
+		break;
+	case 2:
+		/* static NOR */
+		pismo_add_nor(pismo, i, &region);
+		break;
+	case 3:
+		/* static RAM */
+		pismo_add_sram(pismo, i, &region);
+		break;
+	}
+}
+
+static void pismo_remove(struct i2c_client *client)
+{
+	struct pismo_data *pismo = i2c_get_clientdata(client);
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(pismo->dev); i++)
+		platform_device_unregister(pismo->dev[i]);
+
+	kfree(pismo);
+}
+
+static int pismo_probe(struct i2c_client *client)
+{
+	struct pismo_pdata *pdata = client->dev.platform_data;
+	struct pismo_eeprom eeprom;
+	struct pismo_data *pismo;
+	int ret, i;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
+		dev_err(&client->dev, "functionality mismatch\n");
+		return -EIO;
+	}
+
+	pismo = kzalloc_obj(*pismo);
+	if (!pismo)
+		return -ENOMEM;
+
+	pismo->client = client;
+	if (pdata) {
+		pismo->vpp = pdata->set_vpp;
+		pismo->vpp_data = pdata->vpp_data;
+	}
+	i2c_set_clientdata(client, pismo);
+
+	ret = pismo_eeprom_read(client, &eeprom, 0, sizeof(eeprom));
+	if (ret < 0) {
+		dev_err(&client->dev, "error reading EEPROM: %d\n", ret);
+		goto exit_free;
+	}
+
+	dev_info(&client->dev, "%.15s board found\n", eeprom.board);
+
+	for (i = 0; i < ARRAY_SIZE(eeprom.cs); i++)
+		if (eeprom.cs[i].type != 0xff)
+			pismo_add_one(pismo, i, &eeprom.cs[i],
+				      pdata->cs_addrs[i]);
+
+	return 0;
+
+ exit_free:
+	kfree(pismo);
+	return ret;
+}
+
+static const struct i2c_device_id pismo_id[] = {
+	{ "pismo" },
+	{ },
+};
+MODULE_DEVICE_TABLE(i2c, pismo_id);
+
+static struct i2c_driver pismo_driver = {
+	.driver	= {
+		.name	= "pismo",
+	},
+	.probe		= pismo_probe,
+	.remove		= pismo_remove,
+	.id_table	= pismo_id,
+};
+
+static int __init pismo_init(void)
+{
+	BUILD_BUG_ON(sizeof(struct pismo_cs_block) != 48);
+	BUILD_BUG_ON(sizeof(struct pismo_eeprom) != 256);
+
+	return i2c_add_driver(&pismo_driver);
+}
+module_init(pismo_init);
+
+static void __exit pismo_exit(void)
+{
+	i2c_del_driver(&pismo_driver);
+}
+module_exit(pismo_exit);
+
+MODULE_AUTHOR("Russell King <linux@arm.linux.org.uk>");
+MODULE_DESCRIPTION("PISMO memory driver");
+MODULE_LICENSE("GPL");