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, 184 insertions, 0 deletions

diff --git a/drivers/mtd/hyperbus/rpc-if.c b/drivers/mtd/hyperbus/rpc-if.c
new file mode 100644
index 000000000..f448e23f9
--- /dev/null
+++ b/drivers/mtd/hyperbus/rpc-if.c
@@ -0,0 +1,184 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Linux driver for RPC-IF HyperFlash
+ *
+ * Copyright (C) 2019-2020 Cogent Embedded, Inc.
+ */
+
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mtd/hyperbus.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mux/consumer.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+
+#include <memory/renesas-rpc-if.h>
+
+struct	rpcif_hyperbus {
+	struct rpcif rpc;
+	struct hyperbus_ctlr ctlr;
+	struct hyperbus_device hbdev;
+};
+
+static const struct rpcif_op rpcif_op_tmpl = {
+	.cmd = {
+		.buswidth = 8,
+		.ddr = true,
+	},
+	.ocmd = {
+		.buswidth = 8,
+		.ddr = true,
+	},
+	.addr = {
+		.nbytes = 1,
+		.buswidth = 8,
+		.ddr = true,
+	},
+	.data = {
+		.buswidth = 8,
+		.ddr = true,
+	},
+};
+
+static void rpcif_hb_prepare_read(struct rpcif *rpc, void *to,
+				  unsigned long from, ssize_t len)
+{
+	struct rpcif_op op = rpcif_op_tmpl;
+
+	op.cmd.opcode = HYPERBUS_RW_READ | HYPERBUS_AS_MEM;
+	op.addr.val = from >> 1;
+	op.dummy.buswidth = 1;
+	op.dummy.ncycles = 15;
+	op.data.dir = RPCIF_DATA_IN;
+	op.data.nbytes = len;
+	op.data.buf.in = to;
+
+	rpcif_prepare(rpc->dev, &op, NULL, NULL);
+}
+
+static void rpcif_hb_prepare_write(struct rpcif *rpc, unsigned long to,
+				   void *from, ssize_t len)
+{
+	struct rpcif_op op = rpcif_op_tmpl;
+
+	op.cmd.opcode = HYPERBUS_RW_WRITE | HYPERBUS_AS_MEM;
+	op.addr.val = to >> 1;
+	op.data.dir = RPCIF_DATA_OUT;
+	op.data.nbytes = len;
+	op.data.buf.out = from;
+
+	rpcif_prepare(rpc->dev, &op, NULL, NULL);
+}
+
+static u16 rpcif_hb_read16(struct hyperbus_device *hbdev, unsigned long addr)
+{
+	struct rpcif_hyperbus *hyperbus =
+		container_of(hbdev, struct rpcif_hyperbus, hbdev);
+	map_word data;
+
+	rpcif_hb_prepare_read(&hyperbus->rpc, &data, addr, 2);
+
+	rpcif_manual_xfer(hyperbus->rpc.dev);
+
+	return data.x[0];
+}
+
+static void rpcif_hb_write16(struct hyperbus_device *hbdev, unsigned long addr,
+			     u16 data)
+{
+	struct rpcif_hyperbus *hyperbus =
+		container_of(hbdev, struct rpcif_hyperbus, hbdev);
+
+	rpcif_hb_prepare_write(&hyperbus->rpc, addr, &data, 2);
+
+	rpcif_manual_xfer(hyperbus->rpc.dev);
+}
+
+static void rpcif_hb_copy_from(struct hyperbus_device *hbdev, void *to,
+			       unsigned long from, ssize_t len)
+{
+	struct rpcif_hyperbus *hyperbus =
+		container_of(hbdev, struct rpcif_hyperbus, hbdev);
+
+	rpcif_hb_prepare_read(&hyperbus->rpc, to, from, len);
+
+	rpcif_dirmap_read(hyperbus->rpc.dev, from, len, to);
+}
+
+static const struct hyperbus_ops rpcif_hb_ops = {
+	.read16 = rpcif_hb_read16,
+	.write16 = rpcif_hb_write16,
+	.copy_from = rpcif_hb_copy_from,
+};
+
+static int rpcif_hb_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct rpcif_hyperbus *hyperbus;
+	int error;
+
+	hyperbus = devm_kzalloc(dev, sizeof(*hyperbus), GFP_KERNEL);
+	if (!hyperbus)
+		return -ENOMEM;
+
+	error = rpcif_sw_init(&hyperbus->rpc, pdev->dev.parent);
+	if (error)
+		return error;
+
+	platform_set_drvdata(pdev, hyperbus);
+
+	pm_runtime_enable(hyperbus->rpc.dev);
+
+	error = rpcif_hw_init(hyperbus->rpc.dev, true);
+	if (error)
+		goto out_disable_rpm;
+
+	hyperbus->hbdev.map.size = hyperbus->rpc.size;
+	hyperbus->hbdev.map.virt = hyperbus->rpc.dirmap;
+
+	hyperbus->ctlr.dev = dev;
+	hyperbus->ctlr.ops = &rpcif_hb_ops;
+	hyperbus->hbdev.ctlr = &hyperbus->ctlr;
+	hyperbus->hbdev.np = of_get_next_child(pdev->dev.parent->of_node, NULL);
+	error = hyperbus_register_device(&hyperbus->hbdev);
+	if (error)
+		goto out_disable_rpm;
+
+	return 0;
+
+out_disable_rpm:
+	pm_runtime_disable(hyperbus->rpc.dev);
+	return error;
+}
+
+static void rpcif_hb_remove(struct platform_device *pdev)
+{
+	struct rpcif_hyperbus *hyperbus = platform_get_drvdata(pdev);
+
+	hyperbus_unregister_device(&hyperbus->hbdev);
+
+	pm_runtime_disable(hyperbus->rpc.dev);
+}
+
+static const struct platform_device_id rpc_if_hyperflash_id_table[] = {
+	{ .name = "rpc-if-hyperflash" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(platform, rpc_if_hyperflash_id_table);
+
+static struct platform_driver rpcif_platform_driver = {
+	.probe	= rpcif_hb_probe,
+	.remove = rpcif_hb_remove,
+	.id_table = rpc_if_hyperflash_id_table,
+	.driver	= {
+		.name	= "rpc-if-hyperflash",
+	},
+};
+
+module_platform_driver(rpcif_platform_driver);
+
+MODULE_DESCRIPTION("Renesas RPC-IF HyperFlash driver");
+MODULE_LICENSE("GPL v2");