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, 159 insertions, 0 deletions

diff --git a/drivers/media/common/ttpci-eeprom.c b/drivers/media/common/ttpci-eeprom.c
new file mode 100644
index 000000000..ef8746684
--- /dev/null
+++ b/drivers/media/common/ttpci-eeprom.c
@@ -0,0 +1,159 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+    Retrieve encoded MAC address from 24C16 serial 2-wire EEPROM,
+    decode it and store it in the associated adapter struct for
+    use by dvb_net.c
+
+    This card appear to have the 24C16 write protect held to ground,
+    thus permitting normal read/write operation. Theoretically it
+    would be possible to write routines to burn a different (encoded)
+    MAC address into the EEPROM.
+
+    Robert Schlabbach	GMX
+    Michael Glaum	KVH Industries
+    Holger Waechtler	Convergence
+
+    Copyright (C) 2002-2003 Ralph Metzler <rjkm@metzlerbros.de>
+			    Metzler Brothers Systementwicklung GbR
+
+
+*/
+
+#include <asm/errno.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/i2c.h>
+#include <linux/etherdevice.h>
+
+#include "ttpci-eeprom.h"
+
+#if 1
+#define dprintk(x...) do { printk(x); } while (0)
+#else
+#define dprintk(x...) do { } while (0)
+#endif
+
+
+static int check_mac_tt(u8 *buf)
+{
+	int i;
+	u16 tmp = 0xffff;
+
+	for (i = 0; i < 8; i++) {
+		tmp  = (tmp << 8) | ((tmp >> 8) ^ buf[i]);
+		tmp ^= (tmp >> 4) & 0x0f;
+		tmp ^= (tmp << 12) ^ ((tmp & 0xff) << 5);
+	}
+	tmp ^= 0xffff;
+	return (((tmp >> 8) ^ buf[8]) | ((tmp & 0xff) ^ buf[9]));
+}
+
+static int getmac_tt(u8 * decodedMAC, u8 * encodedMAC)
+{
+	u8 xor[20] = { 0x72, 0x23, 0x68, 0x19, 0x5c, 0xa8, 0x71, 0x2c,
+		       0x54, 0xd3, 0x7b, 0xf1, 0x9E, 0x23, 0x16, 0xf6,
+		       0x1d, 0x36, 0x64, 0x78};
+	u8 data[20];
+	int i;
+
+	/* In case there is a sig check failure have the orig contents available */
+	memcpy(data, encodedMAC, 20);
+
+	for (i = 0; i < 20; i++)
+		data[i] ^= xor[i];
+	for (i = 0; i < 10; i++)
+		data[i] = ((data[2 * i + 1] << 8) | data[2 * i])
+			>> ((data[2 * i + 1] >> 6) & 3);
+
+	if (check_mac_tt(data))
+		return -ENODEV;
+
+	decodedMAC[0] = data[2]; decodedMAC[1] = data[1]; decodedMAC[2] = data[0];
+	decodedMAC[3] = data[6]; decodedMAC[4] = data[5]; decodedMAC[5] = data[4];
+	return 0;
+}
+
+int ttpci_eeprom_decode_mac(u8 *decodedMAC, u8 *encodedMAC)
+{
+	u8 xor[20] = { 0x72, 0x23, 0x68, 0x19, 0x5c, 0xa8, 0x71, 0x2c,
+		       0x54, 0xd3, 0x7b, 0xf1, 0x9E, 0x23, 0x16, 0xf6,
+		       0x1d, 0x36, 0x64, 0x78};
+	u8 data[20];
+	int i;
+
+	memcpy(data, encodedMAC, 20);
+
+	for (i = 0; i < 20; i++)
+		data[i] ^= xor[i];
+	for (i = 0; i < 10; i++)
+		data[i] = ((data[2 * i + 1] << 8) | data[2 * i])
+			>> ((data[2 * i + 1] >> 6) & 3);
+
+	if (check_mac_tt(data))
+		return -ENODEV;
+
+	decodedMAC[0] = data[2];
+	decodedMAC[1] = data[1];
+	decodedMAC[2] = data[0];
+	decodedMAC[3] = data[6];
+	decodedMAC[4] = data[5];
+	decodedMAC[5] = data[4];
+	return 0;
+}
+EXPORT_SYMBOL(ttpci_eeprom_decode_mac);
+
+static int ttpci_eeprom_read_encodedMAC(struct i2c_adapter *adapter, u8 * encodedMAC)
+{
+	int ret;
+	u8 b0[] = { 0xcc };
+
+	struct i2c_msg msg[] = {
+		{ .addr = 0x50, .flags = 0, .buf = b0, .len = 1 },
+		{ .addr = 0x50, .flags = I2C_M_RD, .buf = encodedMAC, .len = 20 }
+	};
+
+	/* dprintk("%s\n", __func__); */
+
+	ret = i2c_transfer(adapter, msg, 2);
+
+	if (ret != 2)		/* Assume EEPROM isn't there */
+		return (-ENODEV);
+
+	return 0;
+}
+
+
+int ttpci_eeprom_parse_mac(struct i2c_adapter *adapter, u8 *proposed_mac)
+{
+	int ret;
+	u8 encodedMAC[20];
+	u8 decodedMAC[6];
+
+	ret = ttpci_eeprom_read_encodedMAC(adapter, encodedMAC);
+
+	if (ret != 0) {		/* Will only be -ENODEV */
+		dprintk("Couldn't read from EEPROM: not there?\n");
+		eth_zero_addr(proposed_mac);
+		return ret;
+	}
+
+	ret = getmac_tt(decodedMAC, encodedMAC);
+	if( ret != 0 ) {
+		dprintk("adapter failed MAC signature check\n");
+		dprintk("encoded MAC from EEPROM was %*phC",
+			(int)sizeof(encodedMAC), &encodedMAC);
+		eth_zero_addr(proposed_mac);
+		return ret;
+	}
+
+	memcpy(proposed_mac, decodedMAC, 6);
+	dprintk("adapter has MAC addr = %pM\n", decodedMAC);
+	return 0;
+}
+
+EXPORT_SYMBOL(ttpci_eeprom_parse_mac);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Ralph Metzler, Marcus Metzler, others");
+MODULE_DESCRIPTION("Decode dvb_net MAC address from EEPROM of PCI DVB cards made by Siemens, Technotrend, Hauppauge");