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, 120 insertions, 0 deletions

diff --git a/arch/mips/ralink/of.c b/arch/mips/ralink/of.c
new file mode 100644
index 000000000..7f90068c6
--- /dev/null
+++ b/arch/mips/ralink/of.c
@@ -0,0 +1,120 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *
+ * Copyright (C) 2008 Imre Kaloz <kaloz@openwrt.org>
+ * Copyright (C) 2008-2009 Gabor Juhos <juhosg@openwrt.org>
+ * Copyright (C) 2013 John Crispin <john@phrozen.org>
+ */
+
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/export.h>
+#include <linux/init.h>
+#include <linux/sizes.h>
+#include <linux/of_fdt.h>
+#include <linux/kernel.h>
+#include <linux/memblock.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+
+#include <asm/reboot.h>
+#include <asm/bootinfo.h>
+#include <asm/addrspace.h>
+#include <asm/prom.h>
+#include <asm/mach-ralink/ralink_regs.h>
+
+#include "common.h"
+
+__iomem void *rt_sysc_membase;
+__iomem void *rt_memc_membase;
+EXPORT_SYMBOL_GPL(rt_sysc_membase);
+
+static const struct of_device_id mtmips_memc_match[] = {
+	{ .compatible = "mediatek,mt7621-memc" },
+	{ .compatible = "ralink,mt7620a-memc" },
+	{ .compatible = "ralink,rt2880-memc" },
+	{ .compatible = "ralink,rt3050-memc" },
+	{ .compatible = "ralink,rt3883-memc" },
+	{}
+};
+
+static const struct of_device_id mtmips_sysc_match[] = {
+	{ .compatible = "mediatek,mt7621-sysc" },
+	{ .compatible = "ralink,mt7620-sysc" },
+	{ .compatible = "ralink,mt7628-sysc" },
+	{ .compatible = "ralink,mt7688-sysc" },
+	{ .compatible = "ralink,rt2880-sysc" },
+	{ .compatible = "ralink,rt3050-sysc" },
+	{ .compatible = "ralink,rt3052-sysc" },
+	{ .compatible = "ralink,rt3352-sysc" },
+	{ .compatible = "ralink,rt3883-sysc" },
+	{ .compatible = "ralink,rt5350-sysc" },
+	{}
+};
+
+static __iomem void *
+mtmips_of_remap_node(const struct of_device_id *match, const char *type)
+{
+	struct resource res;
+	struct device_node *np;
+
+	np = of_find_matching_node(NULL, match);
+	if (!np)
+		panic("Failed to find %s controller node", type);
+
+	if (of_address_to_resource(np, 0, &res))
+		panic("Failed to get resource for %s node", np->name);
+
+	if (!request_mem_region(res.start,
+				resource_size(&res),
+				res.name))
+		panic("Failed to request resources for %s node", np->name);
+
+	of_node_put(np);
+
+	return ioremap(res.start, resource_size(&res));
+}
+
+void __init ralink_of_remap(void)
+{
+	rt_sysc_membase = mtmips_of_remap_node(mtmips_sysc_match, "system");
+	rt_memc_membase = mtmips_of_remap_node(mtmips_memc_match, "memory");
+
+	if (!rt_sysc_membase || !rt_memc_membase)
+		panic("Failed to remap core resources");
+}
+
+void __init plat_mem_setup(void)
+{
+	void *dtb;
+
+	set_io_port_base(KSEG1);
+
+	/*
+	 * Load the builtin devicetree. This causes the chosen node to be
+	 * parsed resulting in our memory appearing.
+	 */
+	dtb = get_fdt();
+	__dt_setup_arch(dtb);
+
+	if (early_init_dt_scan_memory())
+		return;
+
+	if (soc_info.mem_detect)
+		soc_info.mem_detect();
+	else if (soc_info.mem_size)
+		memblock_add(soc_info.mem_base, soc_info.mem_size * SZ_1M);
+	else
+		detect_memory_region(soc_info.mem_base,
+				     soc_info.mem_size_min * SZ_1M,
+				     soc_info.mem_size_max * SZ_1M);
+}
+
+static int __init plat_of_setup(void)
+{
+	__dt_register_buses(soc_info.compatible, "palmbus");
+
+	return 0;
+}
+
+arch_initcall(plat_of_setup);