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, 171 insertions, 0 deletions

diff --git a/drivers/pci/controller/pci-versatile.c b/drivers/pci/controller/pci-versatile.c
new file mode 100644
index 000000000..e9a6758fe
--- /dev/null
+++ b/drivers/pci/controller/pci-versatile.c
@@ -0,0 +1,171 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2004 Koninklijke Philips Electronics NV
+ *
+ * Conversion to platform driver and DT:
+ * Copyright 2014 Linaro Ltd.
+ *
+ * 14/04/2005 Initial version, colin.king@philips.com
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_pci.h>
+#include <linux/of_platform.h>
+#include <linux/pci.h>
+#include <linux/platform_device.h>
+
+#include "../pci.h"
+
+static void __iomem *versatile_pci_base;
+static void __iomem *versatile_cfg_base[2];
+
+#define PCI_IMAP(m)		(versatile_pci_base + ((m) * 4))
+#define PCI_SMAP(m)		(versatile_pci_base + 0x14 + ((m) * 4))
+#define PCI_SELFID		(versatile_pci_base + 0xc)
+
+#define VP_PCI_DEVICE_ID		0x030010ee
+#define VP_PCI_CLASS_ID			0x0b400000
+
+static u32 pci_slot_ignore;
+
+static int __init versatile_pci_slot_ignore(char *str)
+{
+	int slot;
+
+	while (get_option(&str, &slot)) {
+		if ((slot < 0) || (slot > 31))
+			pr_err("Illegal slot value: %d\n", slot);
+		else
+			pci_slot_ignore |= (1 << slot);
+	}
+	return 1;
+}
+__setup("pci_slot_ignore=", versatile_pci_slot_ignore);
+
+
+static void __iomem *versatile_map_bus(struct pci_bus *bus,
+				       unsigned int devfn, int offset)
+{
+	unsigned int busnr = bus->number;
+
+	if (pci_slot_ignore & (1 << PCI_SLOT(devfn)))
+		return NULL;
+
+	return versatile_cfg_base[1] + ((busnr << 16) | (devfn << 8) | offset);
+}
+
+static struct pci_ops pci_versatile_ops = {
+	.map_bus = versatile_map_bus,
+	.read	= pci_generic_config_read32,
+	.write	= pci_generic_config_write,
+};
+
+static int versatile_pci_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+	struct resource_entry *entry;
+	int i, myslot = -1, mem = 1;
+	u32 val;
+	void __iomem *local_pci_cfg_base;
+	struct pci_host_bridge *bridge;
+
+	bridge = devm_pci_alloc_host_bridge(dev, 0);
+	if (!bridge)
+		return -ENOMEM;
+
+	versatile_pci_base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(versatile_pci_base))
+		return PTR_ERR(versatile_pci_base);
+
+	versatile_cfg_base[0] = devm_platform_ioremap_resource(pdev, 1);
+	if (IS_ERR(versatile_cfg_base[0]))
+		return PTR_ERR(versatile_cfg_base[0]);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 2);
+	versatile_cfg_base[1] = devm_pci_remap_cfg_resource(dev, res);
+	if (IS_ERR(versatile_cfg_base[1]))
+		return PTR_ERR(versatile_cfg_base[1]);
+
+	resource_list_for_each_entry(entry, &bridge->windows) {
+		if (resource_type(entry->res) == IORESOURCE_MEM) {
+			writel(entry->res->start >> 28, PCI_IMAP(mem));
+			writel(__pa(PAGE_OFFSET) >> 28, PCI_SMAP(mem));
+			mem++;
+		}
+	}
+
+	/*
+	 * We need to discover the PCI core first to configure itself
+	 * before the main PCI probing is performed
+	 */
+	for (i = 0; i < 32; i++) {
+		if ((readl(versatile_cfg_base[0] + (i << 11) + PCI_VENDOR_ID) == VP_PCI_DEVICE_ID) &&
+		    (readl(versatile_cfg_base[0] + (i << 11) + PCI_CLASS_REVISION) == VP_PCI_CLASS_ID)) {
+			myslot = i;
+			break;
+		}
+	}
+	if (myslot == -1) {
+		dev_err(dev, "Cannot find PCI core!\n");
+		return -EIO;
+	}
+	/*
+	 * Do not to map Versatile FPGA PCI device into memory space
+	 */
+	pci_slot_ignore |= (1 << myslot);
+
+	dev_info(dev, "PCI core found (slot %d)\n", myslot);
+
+	writel(myslot, PCI_SELFID);
+	local_pci_cfg_base = versatile_cfg_base[1] + (myslot << 11);
+
+	val = readl(local_pci_cfg_base + PCI_COMMAND);
+	val |= PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER | PCI_COMMAND_INVALIDATE;
+	writel(val, local_pci_cfg_base + PCI_COMMAND);
+
+	/*
+	 * Configure the PCI inbound memory windows to be 1:1 mapped to SDRAM
+	 */
+	writel(__pa(PAGE_OFFSET), local_pci_cfg_base + PCI_BASE_ADDRESS_0);
+	writel(__pa(PAGE_OFFSET), local_pci_cfg_base + PCI_BASE_ADDRESS_1);
+	writel(__pa(PAGE_OFFSET), local_pci_cfg_base + PCI_BASE_ADDRESS_2);
+
+	/*
+	 * For many years the kernel and QEMU were symbiotically buggy
+	 * in that they both assumed the same broken IRQ mapping.
+	 * QEMU therefore attempts to auto-detect old broken kernels
+	 * so that they still work on newer QEMU as they did on old
+	 * QEMU. Since we now use the correct (ie matching-hardware)
+	 * IRQ mapping we write a definitely different value to a
+	 * PCI_INTERRUPT_LINE register to tell QEMU that we expect
+	 * real hardware behaviour and it need not be backwards
+	 * compatible for us. This write is harmless on real hardware.
+	 */
+	writel(0, versatile_cfg_base[0] + PCI_INTERRUPT_LINE);
+
+	pci_add_flags(PCI_REASSIGN_ALL_BUS);
+
+	bridge->ops = &pci_versatile_ops;
+
+	return pci_host_probe(bridge);
+}
+
+static const struct of_device_id versatile_pci_of_match[] = {
+	{ .compatible = "arm,versatile-pci", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, versatile_pci_of_match);
+
+static struct platform_driver versatile_pci_driver = {
+	.driver = {
+		.name = "versatile-pci",
+		.of_match_table = versatile_pci_of_match,
+		.suppress_bind_attrs = true,
+	},
+	.probe = versatile_pci_probe,
+};
+module_platform_driver(versatile_pci_driver);
+
+MODULE_DESCRIPTION("Versatile PCI driver");