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, 118 insertions, 0 deletions

diff --git a/drivers/mtd/maps/uclinux.c b/drivers/mtd/maps/uclinux.c
new file mode 100644
index 000000000..de4c46318
--- /dev/null
+++ b/drivers/mtd/maps/uclinux.c
@@ -0,0 +1,118 @@
+/****************************************************************************/
+
+/*
+ *	uclinux.c -- generic memory mapped MTD driver for uclinux
+ *
+ *	(C) Copyright 2002, Greg Ungerer (gerg@snapgear.com)
+ *
+ *      License: GPL
+ */
+
+/****************************************************************************/
+
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/major.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/map.h>
+#include <linux/mtd/partitions.h>
+#include <asm/io.h>
+#include <asm/sections.h>
+
+/****************************************************************************/
+
+#ifdef CONFIG_MTD_ROM
+#define MAP_NAME "rom"
+#else
+#define MAP_NAME "ram"
+#endif
+
+static struct map_info uclinux_ram_map = {
+	.name = MAP_NAME,
+	.size = 0,
+};
+
+static unsigned long physaddr = -1;
+module_param(physaddr, ulong, S_IRUGO);
+
+static struct mtd_info *uclinux_ram_mtdinfo;
+
+/****************************************************************************/
+
+static const struct mtd_partition uclinux_romfs[] = {
+	{ .name = "ROMfs" }
+};
+
+#define	NUM_PARTITIONS	ARRAY_SIZE(uclinux_romfs)
+
+/****************************************************************************/
+
+static int uclinux_point(struct mtd_info *mtd, loff_t from, size_t len,
+	size_t *retlen, void **virt, resource_size_t *phys)
+{
+	struct map_info *map = mtd->priv;
+	*virt = map->virt + from;
+	if (phys)
+		*phys = map->phys + from;
+	*retlen = len;
+	return(0);
+}
+
+/****************************************************************************/
+
+static int __init uclinux_mtd_init(void)
+{
+	struct mtd_info *mtd;
+	struct map_info *mapp;
+
+	mapp = &uclinux_ram_map;
+
+	if (physaddr == -1)
+		mapp->phys = (resource_size_t)__bss_stop;
+	else
+		mapp->phys = physaddr;
+
+	if (!mapp->size)
+		mapp->size = PAGE_ALIGN(ntohl(*((unsigned long *)(mapp->phys + 8))));
+	mapp->bankwidth = 4;
+
+	printk("uclinux[mtd]: probe address=0x%x size=0x%x\n",
+	       	(int) mapp->phys, (int) mapp->size);
+
+	/*
+	 * The filesystem is guaranteed to be in direct mapped memory. It is
+	 * directly following the kernels own bss region. Following the same
+	 * mechanism used by architectures setting up traditional initrds we
+	 * use phys_to_virt to get the virtual address of its start.
+	 */
+	mapp->virt = phys_to_virt(mapp->phys);
+
+	if (mapp->virt == 0) {
+		printk("uclinux[mtd]: no virtual mapping?\n");
+		return(-EIO);
+	}
+
+	simple_map_init(mapp);
+
+	mtd = do_map_probe("map_" MAP_NAME, mapp);
+	if (!mtd) {
+		printk("uclinux[mtd]: failed to find a mapping?\n");
+		return(-ENXIO);
+	}
+
+	mtd->owner = THIS_MODULE;
+	mtd->_point = uclinux_point;
+	mtd->priv = mapp;
+
+	uclinux_ram_mtdinfo = mtd;
+	mtd_device_register(mtd, uclinux_romfs, NUM_PARTITIONS);
+
+	return(0);
+}
+device_initcall(uclinux_mtd_init);
+
+/****************************************************************************/