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, 140 insertions, 0 deletions

diff --git a/drivers/bus/stm32_etzpc.c b/drivers/bus/stm32_etzpc.c
new file mode 100644
index 000000000..4918a14e5
--- /dev/null
+++ b/drivers/bus/stm32_etzpc.c
@@ -0,0 +1,140 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2023, STMicroelectronics - All Rights Reserved
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/bus/stm32_firewall.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+
+/*
+ * ETZPC registers
+ */
+#define ETZPC_DECPROT			0x10
+#define ETZPC_HWCFGR			0x3F0
+
+/*
+ * HWCFGR register
+ */
+#define ETZPC_HWCFGR_NUM_TZMA		GENMASK(7, 0)
+#define ETZPC_HWCFGR_NUM_PER_SEC	GENMASK(15, 8)
+#define ETZPC_HWCFGR_NUM_AHB_SEC	GENMASK(23, 16)
+#define ETZPC_HWCFGR_CHUNKS1N4		GENMASK(31, 24)
+
+/*
+ * ETZPC miscellaneous
+ */
+#define ETZPC_PROT_MASK			GENMASK(1, 0)
+#define ETZPC_PROT_A7NS			0x3
+#define ETZPC_DECPROT_SHIFT		1
+
+#define IDS_PER_DECPROT_REGS		16
+
+static int stm32_etzpc_grant_access(struct stm32_firewall_controller *ctrl, u32 firewall_id)
+{
+	u32 offset, reg_offset, sec_val;
+
+	if (firewall_id >= ctrl->max_entries) {
+		dev_err(ctrl->dev, "Invalid sys bus ID %u", firewall_id);
+		return -EINVAL;
+	}
+
+	/* Check access configuration, 16 peripherals per register */
+	reg_offset = ETZPC_DECPROT + 0x4 * (firewall_id / IDS_PER_DECPROT_REGS);
+	offset = (firewall_id % IDS_PER_DECPROT_REGS) << ETZPC_DECPROT_SHIFT;
+
+	/* Verify peripheral is non-secure and attributed to cortex A7 */
+	sec_val = (readl(ctrl->mmio + reg_offset) >> offset) & ETZPC_PROT_MASK;
+	if (sec_val != ETZPC_PROT_A7NS) {
+		dev_dbg(ctrl->dev, "Invalid bus configuration: reg_offset %#x, value %d\n",
+			reg_offset, sec_val);
+		return -EACCES;
+	}
+
+	return 0;
+}
+
+static void stm32_etzpc_release_access(struct stm32_firewall_controller *ctrl __maybe_unused,
+				       u32 firewall_id __maybe_unused)
+{
+}
+
+static int stm32_etzpc_probe(struct platform_device *pdev)
+{
+	struct stm32_firewall_controller *etzpc_controller;
+	struct device_node *np = pdev->dev.of_node;
+	u32 nb_per, nb_master;
+	struct resource *res;
+	void __iomem *mmio;
+	int rc;
+
+	etzpc_controller = devm_kzalloc(&pdev->dev, sizeof(*etzpc_controller), GFP_KERNEL);
+	if (!etzpc_controller)
+		return -ENOMEM;
+
+	mmio = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+	if (IS_ERR(mmio))
+		return PTR_ERR(mmio);
+
+	etzpc_controller->dev = &pdev->dev;
+	etzpc_controller->mmio = mmio;
+	etzpc_controller->name = dev_driver_string(etzpc_controller->dev);
+	etzpc_controller->type = STM32_PERIPHERAL_FIREWALL | STM32_MEMORY_FIREWALL;
+	etzpc_controller->grant_access = stm32_etzpc_grant_access;
+	etzpc_controller->release_access = stm32_etzpc_release_access;
+
+	/* Get number of etzpc entries*/
+	nb_per = FIELD_GET(ETZPC_HWCFGR_NUM_PER_SEC,
+			   readl(etzpc_controller->mmio + ETZPC_HWCFGR));
+	nb_master = FIELD_GET(ETZPC_HWCFGR_NUM_AHB_SEC,
+			      readl(etzpc_controller->mmio + ETZPC_HWCFGR));
+	etzpc_controller->max_entries = nb_per + nb_master;
+
+	platform_set_drvdata(pdev, etzpc_controller);
+
+	rc = stm32_firewall_controller_register(etzpc_controller);
+	if (rc) {
+		dev_err(etzpc_controller->dev, "Couldn't register as a firewall controller: %d",
+			rc);
+		return rc;
+	}
+
+	rc = stm32_firewall_populate_bus(etzpc_controller);
+	if (rc) {
+		dev_err(etzpc_controller->dev, "Couldn't populate ETZPC bus: %d",
+			rc);
+		return rc;
+	}
+
+	/* Populate all allowed nodes */
+	return of_platform_populate(np, NULL, NULL, &pdev->dev);
+}
+
+static const struct of_device_id stm32_etzpc_of_match[] = {
+	{ .compatible = "st,stm32-etzpc" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, stm32_etzpc_of_match);
+
+static struct platform_driver stm32_etzpc_driver = {
+	.probe  = stm32_etzpc_probe,
+	.driver = {
+		.name = "stm32-etzpc",
+		.of_match_table = stm32_etzpc_of_match,
+	},
+};
+module_platform_driver(stm32_etzpc_driver);
+
+MODULE_AUTHOR("Gatien Chevallier <gatien.chevallier@foss.st.com>");
+MODULE_DESCRIPTION("STMicroelectronics ETZPC driver");
+MODULE_LICENSE("GPL");