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, 314 insertions, 0 deletions

diff --git a/drivers/of/device.c b/drivers/of/device.c
new file mode 100644
index 000000000..b3dc78f2f
--- /dev/null
+++ b/drivers/of/device.c
@@ -0,0 +1,314 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_address.h>
+#include <linux/of_iommu.h>
+#include <linux/of_reserved_mem.h>
+#include <linux/dma-direct.h> /* for bus_dma_region */
+#include <linux/dma-map-ops.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+
+#include <asm/errno.h>
+#include "of_private.h"
+
+/**
+ * of_match_device - Tell if a struct device matches an of_device_id list
+ * @matches: array of of_device_id match structures to search in
+ * @dev: the OF device structure to match against
+ *
+ * Used by a driver to check whether an platform_device present in the
+ * system is in its list of supported devices.
+ */
+const struct of_device_id *of_match_device(const struct of_device_id *matches,
+					   const struct device *dev)
+{
+	if (!matches || !dev->of_node || dev_of_node_reused(dev))
+		return NULL;
+	return of_match_node(matches, dev->of_node);
+}
+EXPORT_SYMBOL(of_match_device);
+
+static void
+of_dma_set_restricted_buffer(struct device *dev, struct device_node *np)
+{
+	struct device_node *of_node = dev->of_node;
+	struct of_phandle_iterator it;
+	int rc, i = 0;
+
+	if (!IS_ENABLED(CONFIG_DMA_RESTRICTED_POOL))
+		return;
+
+	/*
+	 * If dev->of_node doesn't exist or doesn't contain memory-region, try
+	 * the OF node having DMA configuration.
+	 */
+	if (!of_property_present(of_node, "memory-region"))
+		of_node = np;
+
+	of_for_each_phandle(&it, rc, of_node, "memory-region", NULL, 0) {
+		/*
+		 * There might be multiple memory regions, but only one
+		 * restricted-dma-pool region is allowed.
+		 */
+		if (of_device_is_compatible(it.node, "restricted-dma-pool") &&
+		    of_device_is_available(it.node)) {
+			if (of_reserved_mem_device_init_by_idx(dev, of_node, i))
+				dev_warn(dev, "failed to initialise \"restricted-dma-pool\" memory node\n");
+			of_node_put(it.node);
+			break;
+		}
+		i++;
+	}
+
+}
+
+/**
+ * of_dma_configure_id - Setup DMA configuration
+ * @dev:	Device to apply DMA configuration
+ * @np:		Pointer to OF node having DMA configuration
+ * @force_dma:  Whether device is to be set up by of_dma_configure() even if
+ *		DMA capability is not explicitly described by firmware.
+ * @id:		Optional const pointer value input id
+ *
+ * Try to get devices's DMA configuration from DT and update it
+ * accordingly.
+ *
+ * If platform code needs to use its own special DMA configuration, it
+ * can use a platform bus notifier and handle BUS_NOTIFY_ADD_DEVICE events
+ * to fix up DMA configuration.
+ */
+int of_dma_configure_id(struct device *dev, struct device_node *np,
+			bool force_dma, const u32 *id)
+{
+	const struct bus_dma_region *map = NULL;
+	struct device_node *bus_np;
+	u64 mask, end = 0;
+	bool coherent, set_map = false;
+	int ret;
+
+	if (dev->dma_range_map) {
+		dev_dbg(dev, "dma_range_map already set\n");
+		goto skip_map;
+	}
+
+	if (np == dev->of_node)
+		bus_np = __of_get_dma_parent(np);
+	else
+		bus_np = of_node_get(np);
+
+	ret = of_dma_get_range(bus_np, &map);
+	of_node_put(bus_np);
+	if (ret < 0) {
+		/*
+		 * For legacy reasons, we have to assume some devices need
+		 * DMA configuration regardless of whether "dma-ranges" is
+		 * correctly specified or not.
+		 */
+		if (!force_dma)
+			return ret == -ENODEV ? 0 : ret;
+	} else {
+		/* Determine the overall bounds of all DMA regions */
+		end = dma_range_map_max(map);
+		set_map = true;
+	}
+skip_map:
+	/*
+	 * If @dev is expected to be DMA-capable then the bus code that created
+	 * it should have initialised its dma_mask pointer by this point. For
+	 * now, we'll continue the legacy behaviour of coercing it to the
+	 * coherent mask if not, but we'll no longer do so quietly.
+	 */
+	if (!dev->dma_mask) {
+		dev_warn(dev, "DMA mask not set\n");
+		dev->dma_mask = &dev->coherent_dma_mask;
+	}
+
+	if (!end && dev->coherent_dma_mask)
+		end = dev->coherent_dma_mask;
+	else if (!end)
+		end = (1ULL << 32) - 1;
+
+	/*
+	 * Limit coherent and dma mask based on size and default mask
+	 * set by the driver.
+	 */
+	mask = DMA_BIT_MASK(ilog2(end) + 1);
+	dev->coherent_dma_mask &= mask;
+	*dev->dma_mask &= mask;
+	/* ...but only set bus limit and range map if we found valid dma-ranges earlier */
+	if (set_map) {
+		dev->bus_dma_limit = end;
+		dev->dma_range_map = map;
+	}
+
+	coherent = of_dma_is_coherent(np);
+	dev_dbg(dev, "device is%sdma coherent\n",
+		coherent ? " " : " not ");
+
+	ret = of_iommu_configure(dev, np, id);
+	if (ret == -EPROBE_DEFER) {
+		/* Don't touch range map if it wasn't set from a valid dma-ranges */
+		if (set_map)
+			dev->dma_range_map = NULL;
+		kfree(map);
+		return -EPROBE_DEFER;
+	}
+	/* Take all other IOMMU errors to mean we'll just carry on without it */
+	dev_dbg(dev, "device is%sbehind an iommu\n",
+		!ret ? " " : " not ");
+
+	arch_setup_dma_ops(dev, coherent);
+
+	if (ret)
+		of_dma_set_restricted_buffer(dev, np);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(of_dma_configure_id);
+
+const void *of_device_get_match_data(const struct device *dev)
+{
+	const struct of_device_id *match;
+
+	match = of_match_device(dev->driver->of_match_table, dev);
+	if (!match)
+		return NULL;
+
+	return match->data;
+}
+EXPORT_SYMBOL(of_device_get_match_data);
+
+/**
+ * of_device_modalias - Fill buffer with newline terminated modalias string
+ * @dev:	Calling device
+ * @str:	Modalias string
+ * @len:	Size of @str
+ */
+ssize_t of_device_modalias(struct device *dev, char *str, ssize_t len)
+{
+	ssize_t sl;
+
+	if (!dev || !dev->of_node || dev_of_node_reused(dev))
+		return -ENODEV;
+
+	sl = of_modalias(dev->of_node, str, len - 2);
+	if (sl < 0)
+		return sl;
+	if (sl > len - 2)
+		return -ENOMEM;
+
+	str[sl++] = '\n';
+	str[sl] = 0;
+	return sl;
+}
+EXPORT_SYMBOL_GPL(of_device_modalias);
+
+/**
+ * of_device_uevent - Display OF related uevent information
+ * @dev:	Device to display the uevent information for
+ * @env:	Kernel object's userspace event reference to fill up
+ */
+void of_device_uevent(const struct device *dev, struct kobj_uevent_env *env)
+{
+	const char *compat, *type;
+	struct alias_prop *app;
+	struct property *p;
+	int seen = 0;
+
+	if ((!dev) || (!dev->of_node))
+		return;
+
+	add_uevent_var(env, "OF_NAME=%pOFn", dev->of_node);
+	add_uevent_var(env, "OF_FULLNAME=%pOF", dev->of_node);
+	type = of_node_get_device_type(dev->of_node);
+	if (type)
+		add_uevent_var(env, "OF_TYPE=%s", type);
+
+	/* Since the compatible field can contain pretty much anything
+	 * it's not really legal to split it out with commas. We split it
+	 * up using a number of environment variables instead. */
+	of_property_for_each_string(dev->of_node, "compatible", p, compat) {
+		add_uevent_var(env, "OF_COMPATIBLE_%d=%s", seen, compat);
+		seen++;
+	}
+	add_uevent_var(env, "OF_COMPATIBLE_N=%d", seen);
+
+	seen = 0;
+	mutex_lock(&of_mutex);
+	list_for_each_entry(app, &aliases_lookup, link) {
+		if (dev->of_node == app->np) {
+			add_uevent_var(env, "OF_ALIAS_%d=%s", seen,
+				       app->alias);
+			seen++;
+		}
+	}
+	mutex_unlock(&of_mutex);
+}
+EXPORT_SYMBOL_GPL(of_device_uevent);
+
+int of_device_uevent_modalias(const struct device *dev, struct kobj_uevent_env *env)
+{
+	int sl;
+
+	if ((!dev) || (!dev->of_node) || dev_of_node_reused(dev))
+		return -ENODEV;
+
+	/* Devicetree modalias is tricky, we add it in 2 steps */
+	if (add_uevent_var(env, "MODALIAS="))
+		return -ENOMEM;
+
+	sl = of_modalias(dev->of_node, &env->buf[env->buflen-1],
+			 sizeof(env->buf) - env->buflen);
+	if (sl < 0)
+		return sl;
+	if (sl >= (sizeof(env->buf) - env->buflen))
+		return -ENOMEM;
+	env->buflen += sl;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(of_device_uevent_modalias);
+
+/**
+ * of_device_make_bus_id - Use the device node data to assign a unique name
+ * @dev: pointer to device structure that is linked to a device tree node
+ *
+ * This routine will first try using the translated bus address to
+ * derive a unique name. If it cannot, then it will prepend names from
+ * parent nodes until a unique name can be derived.
+ */
+void of_device_make_bus_id(struct device *dev)
+{
+	struct device_node *node = dev->of_node;
+	const __be32 *reg;
+	u64 addr;
+	u32 mask;
+
+	/* Construct the name, using parent nodes if necessary to ensure uniqueness */
+	while (node->parent) {
+		/*
+		 * If the address can be translated, then that is as much
+		 * uniqueness as we need. Make it the first component and return
+		 */
+		reg = of_get_property(node, "reg", NULL);
+		if (reg && (addr = of_translate_address(node, reg)) != OF_BAD_ADDR) {
+			if (!of_property_read_u32(node, "mask", &mask))
+				dev_set_name(dev, dev_name(dev) ? "%llx.%x.%pOFn:%s" : "%llx.%x.%pOFn",
+					     addr, ffs(mask) - 1, node, dev_name(dev));
+
+			else
+				dev_set_name(dev, dev_name(dev) ? "%llx.%pOFn:%s" : "%llx.%pOFn",
+					     addr, node, dev_name(dev));
+			return;
+		}
+
+		/* format arguments only used if dev_name() resolves to NULL */
+		dev_set_name(dev, dev_name(dev) ? "%s:%s" : "%s",
+			     kbasename(node->full_name), dev_name(dev));
+		node = node->parent;
+	}
+}
+EXPORT_SYMBOL_GPL(of_device_make_bus_id);