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, 83 insertions, 0 deletions

diff --git a/drivers/pci/controller/pci-host-generic.c b/drivers/pci/controller/pci-host-generic.c
new file mode 100644
index 000000000..9e85c6e9b
--- /dev/null
+++ b/drivers/pci/controller/pci-host-generic.c
@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Simple, generic PCI host controller driver targeting firmware-initialised
+ * systems and virtual machines (e.g. the PCI emulation provided by kvmtool).
+ *
+ * Copyright (C) 2014 ARM Limited
+ *
+ * Author: Will Deacon <will.deacon@arm.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/pci-ecam.h>
+#include <linux/platform_device.h>
+
+#include "pci-host-common.h"
+
+static bool pci_dw_valid_device(struct pci_bus *bus, unsigned int devfn)
+{
+	struct pci_config_window *cfg = bus->sysdata;
+
+	/*
+	 * The Synopsys DesignWare PCIe controller in ECAM mode will not filter
+	 * type 0 config TLPs sent to devices 1 and up on its downstream port,
+	 * resulting in devices appearing multiple times on bus 0 unless we
+	 * filter out those accesses here.
+	 */
+	if (bus->number == cfg->busr.start && PCI_SLOT(devfn) > 0)
+		return false;
+
+	return true;
+}
+
+static void __iomem *pci_dw_ecam_map_bus(struct pci_bus *bus,
+					 unsigned int devfn, int where)
+{
+	if (!pci_dw_valid_device(bus, devfn))
+		return NULL;
+
+	return pci_ecam_map_bus(bus, devfn, where);
+}
+
+static const struct pci_ecam_ops pci_dw_ecam_bus_ops = {
+	.pci_ops	= {
+		.map_bus	= pci_dw_ecam_map_bus,
+		.read		= pci_generic_config_read,
+		.write		= pci_generic_config_write,
+	}
+};
+
+static const struct of_device_id gen_pci_of_match[] = {
+	{ .compatible = "pci-host-cam-generic",
+	  .data = &pci_generic_cam_ops },
+
+	{ .compatible = "pci-host-ecam-generic",
+	  .data = &pci_generic_ecam_ops },
+
+	{ .compatible = "marvell,armada8k-pcie-ecam",
+	  .data = &pci_dw_ecam_bus_ops },
+
+	{ .compatible = "socionext,synquacer-pcie-ecam",
+	  .data = &pci_dw_ecam_bus_ops },
+
+	{ .compatible = "snps,dw-pcie-ecam",
+	  .data = &pci_dw_ecam_bus_ops },
+
+	{ },
+};
+MODULE_DEVICE_TABLE(of, gen_pci_of_match);
+
+static struct platform_driver gen_pci_driver = {
+	.driver = {
+		.name = "pci-host-generic",
+		.of_match_table = gen_pci_of_match,
+	},
+	.probe = pci_host_common_probe,
+	.remove = pci_host_common_remove,
+};
+module_platform_driver(gen_pci_driver);
+
+MODULE_DESCRIPTION("Generic PCI host controller driver");
+MODULE_LICENSE("GPL v2");