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, 253 insertions, 0 deletions

diff --git a/drivers/mcb/mcb-parse.c b/drivers/mcb/mcb-parse.c
new file mode 100644
index 000000000..7e09a0ea8
--- /dev/null
+++ b/drivers/mcb/mcb-parse.c
@@ -0,0 +1,253 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/types.h>
+#include <linux/ioport.h>
+#include <linux/slab.h>
+#include <linux/export.h>
+#include <linux/io.h>
+#include <linux/mcb.h>
+
+#include "mcb-internal.h"
+
+#define for_each_chameleon_cell(dtype, p)	\
+	for ((dtype) = get_next_dtype((p));	\
+	     (dtype) != CHAMELEON_DTYPE_END;	\
+	     (dtype) = get_next_dtype((p)))
+
+static inline uint32_t get_next_dtype(void __iomem *p)
+{
+	uint32_t dtype;
+
+	dtype = readl(p);
+	return dtype >> 28;
+}
+
+static int chameleon_parse_bdd(struct mcb_bus *bus,
+			struct chameleon_bar *cb,
+			void __iomem *base)
+{
+	return 0;
+}
+
+static int chameleon_parse_gdd(struct mcb_bus *bus,
+			struct chameleon_bar *cb,
+			void __iomem *base, int bar_count)
+{
+	struct chameleon_gdd __iomem *gdd =
+		(struct chameleon_gdd __iomem *) base;
+	struct mcb_device *mdev;
+	u32 dev_mapbase;
+	u32 offset;
+	u32 size;
+	int ret;
+	__le32 reg1;
+	__le32 reg2;
+
+	mdev = mcb_alloc_dev(bus);
+	if (!mdev)
+		return -ENOMEM;
+
+	reg1 = readl(&gdd->reg1);
+	reg2 = readl(&gdd->reg2);
+	offset = readl(&gdd->offset);
+	size = readl(&gdd->size);
+
+	mdev->id = GDD_DEV(reg1);
+	mdev->rev = GDD_REV(reg1);
+	mdev->var = GDD_VAR(reg1);
+	mdev->bar = GDD_BAR(reg2);
+	mdev->group = GDD_GRP(reg2);
+	mdev->inst = GDD_INS(reg2);
+
+	/*
+	 * If the BAR is missing, dev_mapbase is zero, or if the
+	 * device is IO mapped we just print a warning and go on with the
+	 * next device, instead of completely stop the gdd parser
+	 */
+	if (mdev->bar > bar_count - 1) {
+		pr_info("No BAR for 16z%03d\n", mdev->id);
+		ret = 0;
+		goto err;
+	}
+
+	dev_mapbase = cb[mdev->bar].addr;
+	if (!dev_mapbase) {
+		pr_info("BAR not assigned for 16z%03d\n", mdev->id);
+		ret = 0;
+		goto err;
+	}
+
+	if (dev_mapbase & 0x01) {
+		pr_info("IO mapped Device (16z%03d) not yet supported\n",
+			mdev->id);
+		ret = 0;
+		goto err;
+	}
+
+	pr_debug("Found a 16z%03d\n", mdev->id);
+
+	mdev->irq.start = GDD_IRQ(reg1);
+	mdev->irq.end = GDD_IRQ(reg1);
+	mdev->irq.flags = IORESOURCE_IRQ;
+
+	mdev->mem.start = dev_mapbase + offset;
+
+	mdev->mem.end = mdev->mem.start + size - 1;
+	mdev->mem.flags = IORESOURCE_MEM;
+
+	ret = mcb_device_register(bus, mdev);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+
+err:
+	mcb_free_dev(mdev);
+
+	return ret;
+}
+
+static void chameleon_parse_bar(void __iomem *base,
+				struct chameleon_bar *cb, int bar_count)
+{
+	char __iomem *p = base;
+	int i;
+
+	/* skip reg1 */
+	p += sizeof(__le32);
+
+	for (i = 0; i < bar_count; i++) {
+		cb[i].addr = readl(p);
+		cb[i].size = readl(p + 4);
+
+		p += sizeof(struct chameleon_bar);
+	}
+}
+
+static int chameleon_get_bar(void __iomem **base, phys_addr_t mapbase,
+			     struct chameleon_bar **cb)
+{
+	struct chameleon_bar *c;
+	int bar_count;
+	__le32 reg;
+	u32 dtype;
+
+	/*
+	 * For those devices which are not connected
+	 * to the PCI Bus (e.g. LPC) there is a bar
+	 * descriptor located directly after the
+	 * chameleon header. This header is comparable
+	 * to a PCI header.
+	 */
+	dtype = get_next_dtype(*base);
+	if (dtype == CHAMELEON_DTYPE_BAR) {
+		reg = readl(*base);
+
+		bar_count = BAR_CNT(reg);
+		if (bar_count <= 0 || bar_count > CHAMELEON_BAR_MAX)
+			return -ENODEV;
+
+		c = kzalloc_objs(struct chameleon_bar, bar_count);
+		if (!c)
+			return -ENOMEM;
+
+		chameleon_parse_bar(*base, c, bar_count);
+		*base += BAR_DESC_SIZE(bar_count);
+	} else {
+		c = kzalloc_obj(struct chameleon_bar);
+		if (!c)
+			return -ENOMEM;
+
+		bar_count = 1;
+		c->addr = mapbase;
+	}
+
+	*cb = c;
+
+	return bar_count;
+}
+
+int chameleon_parse_cells(struct mcb_bus *bus, phys_addr_t mapbase,
+			void __iomem *base)
+{
+	struct chameleon_fpga_header *header;
+	struct chameleon_bar *cb;
+	void __iomem *p = base;
+	int num_cells = 0;
+	uint32_t dtype;
+	int bar_count;
+	int ret;
+	u32 hsize;
+	u32 table_size;
+
+	hsize = sizeof(struct chameleon_fpga_header);
+
+	header = kzalloc(hsize, GFP_KERNEL);
+	if (!header)
+		return -ENOMEM;
+
+	/* Extract header information */
+	memcpy_fromio(header, p, hsize);
+	/* We only support chameleon v2 at the moment */
+	header->magic = le16_to_cpu(header->magic);
+	if (header->magic != CHAMELEONV2_MAGIC) {
+		pr_err("Unsupported chameleon version 0x%x\n",
+				header->magic);
+		ret = -ENODEV;
+		goto free_header;
+	}
+	p += hsize;
+
+	bus->revision = header->revision;
+	bus->model = header->model;
+	bus->minor = header->minor;
+	snprintf(bus->name, CHAMELEON_FILENAME_LEN + 1, "%s",
+		 header->filename);
+
+	bar_count = chameleon_get_bar(&p, mapbase, &cb);
+	if (bar_count < 0) {
+		ret = bar_count;
+		goto free_header;
+	}
+
+	for_each_chameleon_cell(dtype, p) {
+		switch (dtype) {
+		case CHAMELEON_DTYPE_GENERAL:
+			ret = chameleon_parse_gdd(bus, cb, p, bar_count);
+			if (ret < 0)
+				goto free_bar;
+			p += sizeof(struct chameleon_gdd);
+			break;
+		case CHAMELEON_DTYPE_BRIDGE:
+			chameleon_parse_bdd(bus, cb, p);
+			p += sizeof(struct chameleon_bdd);
+			break;
+		case CHAMELEON_DTYPE_END:
+			break;
+		default:
+			pr_err("Invalid chameleon descriptor type 0x%x\n",
+				dtype);
+			ret = -EINVAL;
+			goto free_bar;
+		}
+		num_cells++;
+	}
+
+	if (num_cells == 0) {
+		ret = -EINVAL;
+		goto free_bar;
+	}
+
+	table_size = p - base;
+	pr_debug("%d cell(s) found. Chameleon table size: 0x%04x bytes\n", num_cells, table_size);
+	kfree(cb);
+	kfree(header);
+	return table_size;
+
+free_bar:
+	kfree(cb);
+free_header:
+	kfree(header);
+
+	return ret;
+}
+EXPORT_SYMBOL_NS_GPL(chameleon_parse_cells, "MCB");