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, 383 insertions, 0 deletions

diff --git a/drivers/soc/apple/sart.c b/drivers/soc/apple/sart.c
new file mode 100644
index 000000000..66b99955b
--- /dev/null
+++ b/drivers/soc/apple/sart.c
@@ -0,0 +1,383 @@
+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+/*
+ * Apple SART device driver
+ * Copyright (C) The Asahi Linux Contributors
+ *
+ * Apple SART is a simple address filter for some DMA transactions.
+ * Regions of physical memory must be added to the SART's allow
+ * list before any DMA can target these. Unlike a proper
+ * IOMMU no remapping can be done and special support in the
+ * consumer driver is required since not all DMA transactions of
+ * a single device are subject to SART filtering.
+ */
+
+#include <linux/soc/apple/sart.h>
+#include <linux/atomic.h>
+#include <linux/bits.h>
+#include <linux/bitfield.h>
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+
+#define APPLE_SART_MAX_ENTRIES 16
+
+/* SARTv0 registers */
+#define APPLE_SART0_CONFIG(idx)       (0x00 + 4 * (idx))
+#define APPLE_SART0_CONFIG_FLAGS      GENMASK(28, 24)
+#define APPLE_SART0_CONFIG_SIZE       GENMASK(18, 0)
+#define APPLE_SART0_CONFIG_SIZE_SHIFT 12
+#define APPLE_SART0_CONFIG_SIZE_MAX   GENMASK(18, 0)
+
+#define APPLE_SART0_PADDR(idx)  (0x40 + 4 * (idx))
+#define APPLE_SART0_PADDR_SHIFT 12
+
+#define APPLE_SART0_FLAGS_ALLOW 0xf
+
+/* SARTv2 registers */
+#define APPLE_SART2_CONFIG(idx)	      (0x00 + 4 * (idx))
+#define APPLE_SART2_CONFIG_FLAGS      GENMASK(31, 24)
+#define APPLE_SART2_CONFIG_SIZE	      GENMASK(23, 0)
+#define APPLE_SART2_CONFIG_SIZE_SHIFT 12
+#define APPLE_SART2_CONFIG_SIZE_MAX   GENMASK(23, 0)
+
+#define APPLE_SART2_PADDR(idx)	(0x40 + 4 * (idx))
+#define APPLE_SART2_PADDR_SHIFT 12
+
+#define APPLE_SART2_FLAGS_ALLOW 0xff
+
+/* SARTv3 registers */
+#define APPLE_SART3_CONFIG(idx) (0x00 + 4 * (idx))
+
+#define APPLE_SART3_PADDR(idx)	(0x40 + 4 * (idx))
+#define APPLE_SART3_PADDR_SHIFT 12
+
+#define APPLE_SART3_SIZE(idx)  (0x80 + 4 * (idx))
+#define APPLE_SART3_SIZE_SHIFT 12
+#define APPLE_SART3_SIZE_MAX   GENMASK(29, 0)
+
+#define APPLE_SART3_FLAGS_ALLOW 0xff
+
+struct apple_sart_ops {
+	void (*get_entry)(struct apple_sart *sart, int index, u8 *flags,
+			  phys_addr_t *paddr, size_t *size);
+	void (*set_entry)(struct apple_sart *sart, int index, u8 flags,
+			  phys_addr_t paddr_shifted, size_t size_shifted);
+	/* This is probably a bitfield but the exact meaning of each bit is unknown. */
+	unsigned int flags_allow;
+	unsigned int size_shift;
+	unsigned int paddr_shift;
+	size_t size_max;
+};
+
+struct apple_sart {
+	struct device *dev;
+	void __iomem *regs;
+
+	const struct apple_sart_ops *ops;
+
+	unsigned long protected_entries;
+	unsigned long used_entries;
+};
+
+static void sart0_get_entry(struct apple_sart *sart, int index, u8 *flags,
+	phys_addr_t *paddr, size_t *size)
+{
+	u32 cfg = readl(sart->regs + APPLE_SART0_CONFIG(index));
+	phys_addr_t paddr_ = readl(sart->regs + APPLE_SART0_PADDR(index));
+	size_t size_ = FIELD_GET(APPLE_SART0_CONFIG_SIZE, cfg);
+
+	*flags = FIELD_GET(APPLE_SART0_CONFIG_FLAGS, cfg);
+	*size = size_ << APPLE_SART0_CONFIG_SIZE_SHIFT;
+	*paddr = paddr_ << APPLE_SART0_PADDR_SHIFT;
+}
+
+static void sart0_set_entry(struct apple_sart *sart, int index, u8 flags,
+	phys_addr_t paddr_shifted, size_t size_shifted)
+{
+	u32 cfg;
+
+	cfg = FIELD_PREP(APPLE_SART0_CONFIG_FLAGS, flags);
+	cfg |= FIELD_PREP(APPLE_SART0_CONFIG_SIZE, size_shifted);
+
+	writel(paddr_shifted, sart->regs + APPLE_SART0_PADDR(index));
+	writel(cfg, sart->regs + APPLE_SART0_CONFIG(index));
+}
+
+static struct apple_sart_ops sart_ops_v0 = {
+	.get_entry = sart0_get_entry,
+	.set_entry = sart0_set_entry,
+	.flags_allow = APPLE_SART0_FLAGS_ALLOW,
+	.size_shift = APPLE_SART0_CONFIG_SIZE_SHIFT,
+	.paddr_shift = APPLE_SART0_PADDR_SHIFT,
+	.size_max = APPLE_SART0_CONFIG_SIZE_MAX,
+};
+
+static void sart2_get_entry(struct apple_sart *sart, int index, u8 *flags,
+			    phys_addr_t *paddr, size_t *size)
+{
+	u32 cfg = readl(sart->regs + APPLE_SART2_CONFIG(index));
+	phys_addr_t paddr_ = readl(sart->regs + APPLE_SART2_PADDR(index));
+	size_t size_ = FIELD_GET(APPLE_SART2_CONFIG_SIZE, cfg);
+
+	*flags = FIELD_GET(APPLE_SART2_CONFIG_FLAGS, cfg);
+	*size = size_ << APPLE_SART2_CONFIG_SIZE_SHIFT;
+	*paddr = paddr_ << APPLE_SART2_PADDR_SHIFT;
+}
+
+static void sart2_set_entry(struct apple_sart *sart, int index, u8 flags,
+			    phys_addr_t paddr_shifted, size_t size_shifted)
+{
+	u32 cfg;
+
+	cfg = FIELD_PREP(APPLE_SART2_CONFIG_FLAGS, flags);
+	cfg |= FIELD_PREP(APPLE_SART2_CONFIG_SIZE, size_shifted);
+
+	writel(paddr_shifted, sart->regs + APPLE_SART2_PADDR(index));
+	writel(cfg, sart->regs + APPLE_SART2_CONFIG(index));
+}
+
+static struct apple_sart_ops sart_ops_v2 = {
+	.get_entry = sart2_get_entry,
+	.set_entry = sart2_set_entry,
+	.flags_allow = APPLE_SART2_FLAGS_ALLOW,
+	.size_shift = APPLE_SART2_CONFIG_SIZE_SHIFT,
+	.paddr_shift = APPLE_SART2_PADDR_SHIFT,
+	.size_max = APPLE_SART2_CONFIG_SIZE_MAX,
+};
+
+static void sart3_get_entry(struct apple_sart *sart, int index, u8 *flags,
+			    phys_addr_t *paddr, size_t *size)
+{
+	phys_addr_t paddr_ = readl(sart->regs + APPLE_SART3_PADDR(index));
+	size_t size_ = readl(sart->regs + APPLE_SART3_SIZE(index));
+
+	*flags = readl(sart->regs + APPLE_SART3_CONFIG(index));
+	*size = size_ << APPLE_SART3_SIZE_SHIFT;
+	*paddr = paddr_ << APPLE_SART3_PADDR_SHIFT;
+}
+
+static void sart3_set_entry(struct apple_sart *sart, int index, u8 flags,
+			    phys_addr_t paddr_shifted, size_t size_shifted)
+{
+	writel(paddr_shifted, sart->regs + APPLE_SART3_PADDR(index));
+	writel(size_shifted, sart->regs + APPLE_SART3_SIZE(index));
+	writel(flags, sart->regs + APPLE_SART3_CONFIG(index));
+}
+
+static struct apple_sart_ops sart_ops_v3 = {
+	.get_entry = sart3_get_entry,
+	.set_entry = sart3_set_entry,
+	.flags_allow = APPLE_SART3_FLAGS_ALLOW,
+	.size_shift = APPLE_SART3_SIZE_SHIFT,
+	.paddr_shift = APPLE_SART3_PADDR_SHIFT,
+	.size_max = APPLE_SART3_SIZE_MAX,
+};
+
+static int apple_sart_probe(struct platform_device *pdev)
+{
+	int i;
+	struct apple_sart *sart;
+	struct device *dev = &pdev->dev;
+
+	sart = devm_kzalloc(dev, sizeof(*sart), GFP_KERNEL);
+	if (!sart)
+		return -ENOMEM;
+
+	sart->dev = dev;
+	sart->ops = of_device_get_match_data(dev);
+
+	sart->regs = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(sart->regs))
+		return PTR_ERR(sart->regs);
+
+	for (i = 0; i < APPLE_SART_MAX_ENTRIES; ++i) {
+		u8 flags;
+		size_t size;
+		phys_addr_t paddr;
+
+		sart->ops->get_entry(sart, i, &flags, &paddr, &size);
+
+		if (!flags)
+			continue;
+
+		dev_dbg(sart->dev,
+			"SART bootloader entry: index %02d; flags: 0x%02x; paddr: %pa; size: 0x%zx\n",
+			i, flags, &paddr, size);
+		set_bit(i, &sart->protected_entries);
+	}
+
+	platform_set_drvdata(pdev, sart);
+	return 0;
+}
+
+struct apple_sart *devm_apple_sart_get(struct device *dev)
+{
+	struct device_node *sart_node;
+	struct platform_device *sart_pdev;
+	struct device_link *link;
+	struct apple_sart *sart;
+
+	sart_node = of_parse_phandle(dev->of_node, "apple,sart", 0);
+	if (!sart_node)
+		return ERR_PTR(-ENODEV);
+
+	sart_pdev = of_find_device_by_node(sart_node);
+	of_node_put(sart_node);
+
+	if (!sart_pdev)
+		return ERR_PTR(-ENODEV);
+
+	sart = dev_get_drvdata(&sart_pdev->dev);
+	if (!sart) {
+		put_device(&sart_pdev->dev);
+		return ERR_PTR(-EPROBE_DEFER);
+	}
+
+	link = device_link_add(dev, &sart_pdev->dev,
+			       DL_FLAG_PM_RUNTIME | DL_FLAG_AUTOREMOVE_SUPPLIER);
+	if (!link) {
+		put_device(&sart_pdev->dev);
+		return ERR_PTR(-ENODEV);
+	}
+
+	put_device(&sart_pdev->dev);
+
+	return sart;
+}
+EXPORT_SYMBOL_GPL(devm_apple_sart_get);
+
+static int sart_set_entry(struct apple_sart *sart, int index, u8 flags,
+			  phys_addr_t paddr, size_t size)
+{
+	if (size & ((1 << sart->ops->size_shift) - 1))
+		return -EINVAL;
+	if (paddr & ((1 << sart->ops->paddr_shift) - 1))
+		return -EINVAL;
+
+	paddr >>= sart->ops->size_shift;
+	size >>= sart->ops->paddr_shift;
+
+	if (size > sart->ops->size_max)
+		return -EINVAL;
+
+	sart->ops->set_entry(sart, index, flags, paddr, size);
+	return 0;
+}
+
+int apple_sart_add_allowed_region(struct apple_sart *sart, phys_addr_t paddr,
+				  size_t size)
+{
+	int i, ret;
+
+	for (i = 0; i < APPLE_SART_MAX_ENTRIES; ++i) {
+		if (test_bit(i, &sart->protected_entries))
+			continue;
+		if (test_and_set_bit(i, &sart->used_entries))
+			continue;
+
+		ret = sart_set_entry(sart, i, sart->ops->flags_allow, paddr,
+				     size);
+		if (ret) {
+			dev_dbg(sart->dev,
+				"unable to set entry %d to [%pa, 0x%zx]\n",
+				i, &paddr, size);
+			clear_bit(i, &sart->used_entries);
+			return ret;
+		}
+
+		dev_dbg(sart->dev, "wrote [%pa, 0x%zx] to %d\n", &paddr, size,
+			i);
+		return 0;
+	}
+
+	dev_warn(sart->dev,
+		 "no free entries left to add [paddr: 0x%pa, size: 0x%zx]\n",
+		 &paddr, size);
+
+	return -EBUSY;
+}
+EXPORT_SYMBOL_GPL(apple_sart_add_allowed_region);
+
+int apple_sart_remove_allowed_region(struct apple_sart *sart, phys_addr_t paddr,
+				     size_t size)
+{
+	int i;
+
+	dev_dbg(sart->dev,
+		"will remove [paddr: %pa, size: 0x%zx] from allowed regions\n",
+		&paddr, size);
+
+	for (i = 0; i < APPLE_SART_MAX_ENTRIES; ++i) {
+		u8 eflags;
+		size_t esize;
+		phys_addr_t epaddr;
+
+		if (test_bit(i, &sart->protected_entries))
+			continue;
+
+		sart->ops->get_entry(sart, i, &eflags, &epaddr, &esize);
+
+		if (epaddr != paddr || esize != size)
+			continue;
+
+		sart->ops->set_entry(sart, i, 0, 0, 0);
+
+		clear_bit(i, &sart->used_entries);
+		dev_dbg(sart->dev, "cleared entry %d\n", i);
+		return 0;
+	}
+
+	dev_warn(sart->dev, "entry [paddr: 0x%pa, size: 0x%zx] not found\n",
+		 &paddr, size);
+
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(apple_sart_remove_allowed_region);
+
+static void apple_sart_shutdown(struct platform_device *pdev)
+{
+	struct apple_sart *sart = dev_get_drvdata(&pdev->dev);
+	int i;
+
+	for (i = 0; i < APPLE_SART_MAX_ENTRIES; ++i) {
+		if (test_bit(i, &sart->protected_entries))
+			continue;
+
+		sart->ops->set_entry(sart, i, 0, 0, 0);
+	}
+}
+
+static const struct of_device_id apple_sart_of_match[] = {
+	{
+		.compatible = "apple,t6000-sart",
+		.data = &sart_ops_v3,
+	},
+	{
+		.compatible = "apple,t8103-sart",
+		.data = &sart_ops_v2,
+	},
+	{
+		.compatible = "apple,t8015-sart",
+		.data = &sart_ops_v0,
+	},
+	{}
+};
+MODULE_DEVICE_TABLE(of, apple_sart_of_match);
+
+static struct platform_driver apple_sart_driver = {
+	.driver = {
+		.name = "apple-sart",
+		.of_match_table = apple_sart_of_match,
+	},
+	.probe = apple_sart_probe,
+	.shutdown = apple_sart_shutdown,
+};
+module_platform_driver(apple_sart_driver);
+
+MODULE_LICENSE("Dual MIT/GPL");
+MODULE_AUTHOR("Sven Peter <sven@svenpeter.dev>");
+MODULE_DESCRIPTION("Apple SART driver");