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, 98 insertions, 0 deletions

diff --git a/arch/mips/bcm63xx/nvram.c b/arch/mips/bcm63xx/nvram.c
new file mode 100644
index 000000000..05757aed0
--- /dev/null
+++ b/arch/mips/bcm63xx/nvram.c
@@ -0,0 +1,98 @@
+/*
+ * 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.
+ *
+ * Copyright (C) 2008 Maxime Bizon <mbizon@freebox.fr>
+ * Copyright (C) 2008 Florian Fainelli <florian@openwrt.org>
+ * Copyright (C) 2012 Jonas Gorski <jonas.gorski@gmail.com>
+ */
+
+#define pr_fmt(fmt) "bcm63xx_nvram: " fmt
+
+#include <linux/bcm963xx_nvram.h>
+#include <linux/init.h>
+#include <linux/crc32.h>
+#include <linux/export.h>
+#include <linux/kernel.h>
+#include <linux/if_ether.h>
+
+#include <bcm63xx_nvram.h>
+
+#define BCM63XX_DEFAULT_PSI_SIZE	64
+
+static struct bcm963xx_nvram nvram;
+static int mac_addr_used;
+
+void __init bcm63xx_nvram_init(void *addr)
+{
+	u32 crc, expected_crc;
+	u8 hcs_mac_addr[ETH_ALEN] = { 0x00, 0x10, 0x18, 0xff, 0xff, 0xff };
+
+	/* extract nvram data */
+	memcpy(&nvram, addr, BCM963XX_NVRAM_V5_SIZE);
+
+	/* check checksum before using data */
+	if (bcm963xx_nvram_checksum(&nvram, &expected_crc, &crc))
+		pr_warn("nvram checksum failed, contents may be invalid (expected %08x, got %08x)\n",
+			expected_crc, crc);
+
+	/* Cable modems have a different NVRAM which is embedded in the eCos
+	 * firmware and not easily extractible, give at least a MAC address
+	 * pool.
+	 */
+	if (BCMCPU_IS_3368()) {
+		memcpy(nvram.mac_addr_base, hcs_mac_addr, ETH_ALEN);
+		nvram.mac_addr_count = 2;
+	}
+}
+
+u8 *bcm63xx_nvram_get_name(void)
+{
+	return nvram.name;
+}
+EXPORT_SYMBOL(bcm63xx_nvram_get_name);
+
+int bcm63xx_nvram_get_mac_address(u8 *mac)
+{
+	u8 *oui;
+	int count;
+
+	if (mac_addr_used >= nvram.mac_addr_count) {
+		pr_err("not enough mac addresses\n");
+		return -ENODEV;
+	}
+
+	memcpy(mac, nvram.mac_addr_base, ETH_ALEN);
+	oui = mac + ETH_ALEN/2 - 1;
+	count = mac_addr_used;
+
+	while (count--) {
+		u8 *p = mac + ETH_ALEN - 1;
+
+		do {
+			(*p)++;
+			if (*p != 0)
+				break;
+			p--;
+		} while (p != oui);
+
+		if (p == oui) {
+			pr_err("unable to fetch mac address\n");
+			return -ENODEV;
+		}
+	}
+
+	mac_addr_used++;
+	return 0;
+}
+EXPORT_SYMBOL(bcm63xx_nvram_get_mac_address);
+
+int bcm63xx_nvram_get_psi_size(void)
+{
+	if (nvram.psi_size > 0)
+		return nvram.psi_size;
+
+	return BCM63XX_DEFAULT_PSI_SIZE;
+}
+EXPORT_SYMBOL(bcm63xx_nvram_get_psi_size);