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, 182 insertions, 0 deletions

diff --git a/drivers/acpi/arm64/apmt.c b/drivers/acpi/arm64/apmt.c
new file mode 100644
index 000000000..8ad049f81
--- /dev/null
+++ b/drivers/acpi/arm64/apmt.c
@@ -0,0 +1,182 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ARM APMT table support.
+ * Design document number: ARM DEN0117.
+ *
+ * Copyright (c) 2022, NVIDIA CORPORATION & AFFILIATES.
+ *
+ */
+
+#define pr_fmt(fmt)	"ACPI: APMT: " fmt
+
+#include <linux/acpi.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include "init.h"
+
+#define DEV_NAME "arm-cs-arch-pmu"
+
+/* There can be up to 3 resources: page 0 and 1 address, and interrupt. */
+#define DEV_MAX_RESOURCE_COUNT 3
+
+/* Root pointer to the mapped APMT table */
+static struct acpi_table_header *apmt_table;
+
+static int __init apmt_init_resources(struct resource *res,
+				      struct acpi_apmt_node *node)
+{
+	int irq, trigger;
+	int num_res = 0;
+
+	res[num_res].start = node->base_address0;
+	res[num_res].end = node->base_address0 + SZ_4K - 1;
+	res[num_res].flags = IORESOURCE_MEM;
+
+	num_res++;
+
+	if (node->flags & ACPI_APMT_FLAGS_DUAL_PAGE) {
+		res[num_res].start = node->base_address1;
+		res[num_res].end = node->base_address1 + SZ_4K - 1;
+		res[num_res].flags = IORESOURCE_MEM;
+
+		num_res++;
+	}
+
+	if (node->ovflw_irq != 0) {
+		trigger = (node->ovflw_irq_flags & ACPI_APMT_OVFLW_IRQ_FLAGS_MODE);
+		trigger = (trigger == ACPI_APMT_OVFLW_IRQ_FLAGS_MODE_LEVEL) ?
+			ACPI_LEVEL_SENSITIVE : ACPI_EDGE_SENSITIVE;
+		irq = acpi_register_gsi(NULL, node->ovflw_irq, trigger,
+						ACPI_ACTIVE_HIGH);
+
+		if (irq <= 0) {
+			pr_warn("APMT could not register gsi hwirq %d\n", irq);
+			return num_res;
+		}
+
+		res[num_res].start = irq;
+		res[num_res].end = irq;
+		res[num_res].flags = IORESOURCE_IRQ;
+
+		num_res++;
+	}
+
+	return num_res;
+}
+
+/**
+ * apmt_add_platform_device() - Allocate a platform device for APMT node
+ * @node: Pointer to device ACPI APMT node
+ * @fwnode: fwnode associated with the APMT node
+ *
+ * Returns: 0 on success, <0 failure
+ */
+static int __init apmt_add_platform_device(struct acpi_apmt_node *node,
+					   struct fwnode_handle *fwnode)
+{
+	struct platform_device *pdev;
+	int ret, count, uid = node->id & INT_MAX;
+	struct resource res[DEV_MAX_RESOURCE_COUNT];
+
+	if (uid != node->id)
+		pr_warn("Unexpectedly large UID 0x%x, truncated to 0x%x\n", node->id, uid);
+	pdev = platform_device_alloc(DEV_NAME, uid);
+	if (!pdev)
+		return -ENOMEM;
+
+	memset(res, 0, sizeof(res));
+
+	count = apmt_init_resources(res, node);
+
+	ret = platform_device_add_resources(pdev, res, count);
+	if (ret)
+		goto dev_put;
+
+	/*
+	 * Add a copy of APMT node pointer to platform_data to be used to
+	 * retrieve APMT data information.
+	 */
+	ret = platform_device_add_data(pdev, &node, sizeof(node));
+	if (ret)
+		goto dev_put;
+
+	platform_device_set_fwnode(pdev, fwnode);
+
+	ret = platform_device_add(pdev);
+
+	if (ret)
+		goto dev_put;
+
+	return 0;
+
+dev_put:
+	platform_device_put(pdev);
+
+	return ret;
+}
+
+static int __init apmt_init_platform_devices(void)
+{
+	struct acpi_apmt_node *apmt_node;
+	struct acpi_table_apmt *apmt;
+	struct fwnode_handle *fwnode;
+	u64 offset, end;
+	int ret;
+
+	/*
+	 * apmt_table and apmt both point to the start of APMT table, but
+	 * have different struct types
+	 */
+	apmt = (struct acpi_table_apmt *)apmt_table;
+	offset = sizeof(*apmt);
+	end = apmt->header.length;
+
+	while (offset < end) {
+		apmt_node = ACPI_ADD_PTR(struct acpi_apmt_node, apmt,
+				 offset);
+
+		fwnode = acpi_alloc_fwnode_static();
+		if (!fwnode)
+			return -ENOMEM;
+
+		ret = apmt_add_platform_device(apmt_node, fwnode);
+		if (ret) {
+			acpi_free_fwnode_static(fwnode);
+			return ret;
+		}
+
+		offset += apmt_node->length;
+	}
+
+	return 0;
+}
+
+void __init acpi_apmt_init(void)
+{
+	acpi_status status;
+	int ret;
+
+	/**
+	 * APMT table nodes will be used at runtime after the apmt init,
+	 * so we don't need to call acpi_put_table() to release
+	 * the APMT table mapping.
+	 */
+	status = acpi_get_table(ACPI_SIG_APMT, 0, &apmt_table);
+
+	if (ACPI_FAILURE(status)) {
+		if (status != AE_NOT_FOUND) {
+			const char *msg = acpi_format_exception(status);
+
+			pr_err("Failed to get APMT table, %s\n", msg);
+		}
+
+		return;
+	}
+
+	ret = apmt_init_platform_devices();
+	if (ret) {
+		pr_err("Failed to initialize APMT platform devices, ret: %d\n", ret);
+		acpi_put_table(apmt_table);
+	}
+}