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, 306 insertions, 0 deletions

diff --git a/drivers/mtd/devices/ms02-nv.c b/drivers/mtd/devices/ms02-nv.c
new file mode 100644
index 000000000..453b3e05f
--- /dev/null
+++ b/drivers/mtd/devices/ms02-nv.c
@@ -0,0 +1,306 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *	Copyright (c) 2001 Maciej W. Rozycki
+ */
+
+#include <linux/init.h>
+#include <linux/ioport.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mtd/mtd.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+#include <asm/addrspace.h>
+#include <asm/bootinfo.h>
+#include <asm/dec/ioasic_addrs.h>
+#include <asm/dec/kn02.h>
+#include <asm/dec/kn03.h>
+#include <asm/io.h>
+#include <asm/paccess.h>
+
+#include "ms02-nv.h"
+
+
+static char version[] __initdata =
+	"ms02-nv.c: v.1.0.0  13 Aug 2001  Maciej W. Rozycki.\n";
+
+MODULE_AUTHOR("Maciej W. Rozycki <macro@linux-mips.org>");
+MODULE_DESCRIPTION("DEC MS02-NV NVRAM module driver");
+MODULE_LICENSE("GPL");
+
+
+/*
+ * Addresses we probe for an MS02-NV at.  Modules may be located
+ * at any 8MiB boundary within a 0MiB up to 112MiB range or at any 32MiB
+ * boundary within a 0MiB up to 448MiB range.  We don't support a module
+ * at 0MiB, though.
+ */
+static ulong ms02nv_addrs[] __initdata = {
+	0x07000000, 0x06800000, 0x06000000, 0x05800000, 0x05000000,
+	0x04800000, 0x04000000, 0x03800000, 0x03000000, 0x02800000,
+	0x02000000, 0x01800000, 0x01000000, 0x00800000
+};
+
+static const char ms02nv_name[] = "DEC MS02-NV NVRAM";
+static const char ms02nv_res_diag_ram[] = "Diagnostic RAM";
+static const char ms02nv_res_user_ram[] = "General-purpose RAM";
+static const char ms02nv_res_csr[] = "Control and status register";
+
+static struct mtd_info *root_ms02nv_mtd;
+
+
+static int ms02nv_read(struct mtd_info *mtd, loff_t from,
+			size_t len, size_t *retlen, u_char *buf)
+{
+	struct ms02nv_private *mp = mtd->priv;
+
+	memcpy(buf, mp->uaddr + from, len);
+	*retlen = len;
+	return 0;
+}
+
+static int ms02nv_write(struct mtd_info *mtd, loff_t to,
+			size_t len, size_t *retlen, const u_char *buf)
+{
+	struct ms02nv_private *mp = mtd->priv;
+
+	memcpy(mp->uaddr + to, buf, len);
+	*retlen = len;
+	return 0;
+}
+
+
+static inline uint ms02nv_probe_one(ulong addr)
+{
+	ms02nv_uint *ms02nv_diagp;
+	ms02nv_uint *ms02nv_magicp;
+	uint ms02nv_diag;
+	uint ms02nv_magic;
+	size_t size;
+
+	int err;
+
+	/*
+	 * The firmware writes MS02NV_ID at MS02NV_MAGIC and also
+	 * a diagnostic status at MS02NV_DIAG.
+	 */
+	ms02nv_diagp = (ms02nv_uint *)(CKSEG1ADDR(addr + MS02NV_DIAG));
+	ms02nv_magicp = (ms02nv_uint *)(CKSEG1ADDR(addr + MS02NV_MAGIC));
+	err = get_dbe(ms02nv_magic, ms02nv_magicp);
+	if (err)
+		return 0;
+	if (ms02nv_magic != MS02NV_ID)
+		return 0;
+
+	ms02nv_diag = *ms02nv_diagp;
+	size = (ms02nv_diag & MS02NV_DIAG_SIZE_MASK) << MS02NV_DIAG_SIZE_SHIFT;
+	if (size > MS02NV_CSR)
+		size = MS02NV_CSR;
+
+	return size;
+}
+
+static int __init ms02nv_init_one(ulong addr)
+{
+	struct mtd_info *mtd;
+	struct ms02nv_private *mp;
+	struct resource *mod_res;
+	struct resource *diag_res;
+	struct resource *user_res;
+	struct resource *csr_res;
+	ulong fixaddr;
+	size_t size, fixsize;
+
+	static int version_printed;
+
+	int ret = -ENODEV;
+
+	/* The module decodes 8MiB of address space. */
+	mod_res = kzalloc_obj(*mod_res);
+	if (!mod_res)
+		return -ENOMEM;
+
+	mod_res->name = ms02nv_name;
+	mod_res->start = addr;
+	mod_res->end = addr + MS02NV_SLOT_SIZE - 1;
+	mod_res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+	if (request_resource(&iomem_resource, mod_res) < 0)
+		goto err_out_mod_res;
+
+	size = ms02nv_probe_one(addr);
+	if (!size)
+		goto err_out_mod_res_rel;
+
+	if (!version_printed) {
+		printk(KERN_INFO "%s", version);
+		version_printed = 1;
+	}
+
+	ret = -ENOMEM;
+	mtd = kzalloc_obj(*mtd);
+	if (!mtd)
+		goto err_out_mod_res_rel;
+	mp = kzalloc_obj(*mp);
+	if (!mp)
+		goto err_out_mtd;
+
+	mtd->priv = mp;
+	mp->resource.module = mod_res;
+
+	/* Firmware's diagnostic NVRAM area. */
+	diag_res = kzalloc_obj(*diag_res);
+	if (!diag_res)
+		goto err_out_mp;
+
+	diag_res->name = ms02nv_res_diag_ram;
+	diag_res->start = addr;
+	diag_res->end = addr + MS02NV_RAM - 1;
+	diag_res->flags = IORESOURCE_BUSY;
+	request_resource(mod_res, diag_res);
+
+	mp->resource.diag_ram = diag_res;
+
+	/* User-available general-purpose NVRAM area. */
+	user_res = kzalloc_obj(*user_res);
+	if (!user_res)
+		goto err_out_diag_res;
+
+	user_res->name = ms02nv_res_user_ram;
+	user_res->start = addr + MS02NV_RAM;
+	user_res->end = addr + size - 1;
+	user_res->flags = IORESOURCE_BUSY;
+	request_resource(mod_res, user_res);
+
+	mp->resource.user_ram = user_res;
+
+	/* Control and status register. */
+	csr_res = kzalloc_obj(*csr_res);
+	if (!csr_res)
+		goto err_out_user_res;
+
+	csr_res->name = ms02nv_res_csr;
+	csr_res->start = addr + MS02NV_CSR;
+	csr_res->end = addr + MS02NV_CSR + 3;
+	csr_res->flags = IORESOURCE_BUSY;
+	request_resource(mod_res, csr_res);
+
+	mp->resource.csr = csr_res;
+
+	mp->addr = phys_to_virt(addr);
+	mp->size = size;
+
+	/*
+	 * Hide the firmware's diagnostic area.  It may get destroyed
+	 * upon a reboot.  Take paging into account for mapping support.
+	 */
+	fixaddr = (addr + MS02NV_RAM + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1);
+	fixsize = (size - (fixaddr - addr)) & ~(PAGE_SIZE - 1);
+	mp->uaddr = phys_to_virt(fixaddr);
+
+	mtd->type = MTD_RAM;
+	mtd->flags = MTD_CAP_RAM;
+	mtd->size = fixsize;
+	mtd->name = ms02nv_name;
+	mtd->owner = THIS_MODULE;
+	mtd->_read = ms02nv_read;
+	mtd->_write = ms02nv_write;
+	mtd->writesize = 1;
+
+	ret = -EIO;
+	if (mtd_device_register(mtd, NULL, 0)) {
+		printk(KERN_ERR
+			"ms02-nv: Unable to register MTD device, aborting!\n");
+		goto err_out_csr_res;
+	}
+
+	printk(KERN_INFO "mtd%d: %s at 0x%08lx, size %zuMiB.\n",
+		mtd->index, ms02nv_name, addr, size >> 20);
+
+	mp->next = root_ms02nv_mtd;
+	root_ms02nv_mtd = mtd;
+
+	return 0;
+
+
+err_out_csr_res:
+	release_resource(csr_res);
+	kfree(csr_res);
+err_out_user_res:
+	release_resource(user_res);
+	kfree(user_res);
+err_out_diag_res:
+	release_resource(diag_res);
+	kfree(diag_res);
+err_out_mp:
+	kfree(mp);
+err_out_mtd:
+	kfree(mtd);
+err_out_mod_res_rel:
+	release_resource(mod_res);
+err_out_mod_res:
+	kfree(mod_res);
+	return ret;
+}
+
+static void __exit ms02nv_remove_one(void)
+{
+	struct mtd_info *mtd = root_ms02nv_mtd;
+	struct ms02nv_private *mp = mtd->priv;
+
+	root_ms02nv_mtd = mp->next;
+
+	mtd_device_unregister(mtd);
+
+	release_resource(mp->resource.csr);
+	kfree(mp->resource.csr);
+	release_resource(mp->resource.user_ram);
+	kfree(mp->resource.user_ram);
+	release_resource(mp->resource.diag_ram);
+	kfree(mp->resource.diag_ram);
+	release_resource(mp->resource.module);
+	kfree(mp->resource.module);
+	kfree(mp);
+	kfree(mtd);
+}
+
+
+static int __init ms02nv_init(void)
+{
+	volatile u32 *csr;
+	uint stride = 0;
+	int count = 0;
+	int i;
+
+	switch (mips_machtype) {
+	case MACH_DS5000_200:
+		csr = (volatile u32 *)CKSEG1ADDR(KN02_SLOT_BASE + KN02_CSR);
+		if (*csr & KN02_CSR_BNK32M)
+			stride = 2;
+		break;
+	case MACH_DS5000_2X0:
+	case MACH_DS5900:
+		csr = (volatile u32 *)CKSEG1ADDR(KN03_SLOT_BASE + IOASIC_MCR);
+		if (*csr & KN03_MCR_BNK32M)
+			stride = 2;
+		break;
+	default:
+		return -ENODEV;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(ms02nv_addrs); i++)
+		if (!ms02nv_init_one(ms02nv_addrs[i] << stride))
+			count++;
+
+	return (count > 0) ? 0 : -ENODEV;
+}
+
+static void __exit ms02nv_cleanup(void)
+{
+	while (root_ms02nv_mtd)
+		ms02nv_remove_one();
+}
+
+
+module_init(ms02nv_init);
+module_exit(ms02nv_cleanup);