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, 307 insertions, 0 deletions

diff --git a/drivers/vfio/iommufd.c b/drivers/vfio/iommufd.c
new file mode 100644
index 000000000..e9893d34d
--- /dev/null
+++ b/drivers/vfio/iommufd.c
@@ -0,0 +1,307 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES
+ */
+#include <linux/vfio.h>
+#include <linux/iommufd.h>
+
+#include "vfio.h"
+
+MODULE_IMPORT_NS("IOMMUFD");
+MODULE_IMPORT_NS("IOMMUFD_VFIO");
+
+bool vfio_iommufd_device_has_compat_ioas(struct vfio_device *vdev,
+					 struct iommufd_ctx *ictx)
+{
+	u32 ioas_id;
+
+	return !iommufd_vfio_compat_ioas_get_id(ictx, &ioas_id);
+}
+
+int vfio_df_iommufd_bind(struct vfio_device_file *df)
+{
+	struct vfio_device *vdev = df->device;
+	struct iommufd_ctx *ictx = df->iommufd;
+
+	lockdep_assert_held(&vdev->dev_set->lock);
+
+	/* Group noiommu via iommufd compat needs no device binding */
+	if (df->group && vfio_device_is_noiommu(vdev))
+		return 0;
+
+	return vdev->ops->bind_iommufd(vdev, ictx, &df->devid);
+}
+
+int vfio_iommufd_compat_attach_ioas(struct vfio_device *vdev,
+				    struct iommufd_ctx *ictx)
+{
+	u32 ioas_id;
+	int ret;
+
+	lockdep_assert_held(&vdev->dev_set->lock);
+
+	/*
+	 * Compat noiommu does not need to do ioas attach. This helper is
+	 * only called from the legacy group/iommufd compat path, so no
+	 * explicit df->group check is needed.
+	 */
+	if (vfio_device_is_noiommu(vdev))
+		return 0;
+
+	ret = iommufd_vfio_compat_ioas_get_id(ictx, &ioas_id);
+	if (ret)
+		return ret;
+
+	/* The legacy path has no way to return the selected pt_id */
+	return vdev->ops->attach_ioas(vdev, &ioas_id);
+}
+
+void vfio_df_iommufd_unbind(struct vfio_device_file *df)
+{
+	struct vfio_device *vdev = df->device;
+
+	lockdep_assert_held(&vdev->dev_set->lock);
+
+	if (df->group && vfio_device_is_noiommu(vdev))
+		return;
+
+	if (vdev->ops->unbind_iommufd)
+		vdev->ops->unbind_iommufd(vdev);
+}
+
+struct iommufd_ctx *vfio_iommufd_device_ictx(struct vfio_device *vdev)
+{
+	if (vdev->iommufd_device)
+		return iommufd_device_to_ictx(vdev->iommufd_device);
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(vfio_iommufd_device_ictx);
+
+static int vfio_iommufd_device_id(struct vfio_device *vdev)
+{
+	if (vdev->iommufd_device)
+		return iommufd_device_to_id(vdev->iommufd_device);
+	return -EINVAL;
+}
+
+/*
+ * Return devid for a device.
+ *  valid ID for the device that is owned by the ictx
+ *  -ENOENT = device is owned but there is no ID
+ *  -ENODEV or other error = device is not owned
+ */
+int vfio_iommufd_get_dev_id(struct vfio_device *vdev, struct iommufd_ctx *ictx)
+{
+	struct iommu_group *group;
+	int devid;
+
+	if (vfio_iommufd_device_ictx(vdev) == ictx)
+		return vfio_iommufd_device_id(vdev);
+
+	group = iommu_group_get(vdev->dev);
+	if (!group)
+		return -ENODEV;
+
+	if (iommufd_ctx_has_group(ictx, group))
+		devid = -ENOENT;
+	else
+		devid = -ENODEV;
+
+	iommu_group_put(group);
+
+	return devid;
+}
+EXPORT_SYMBOL_GPL(vfio_iommufd_get_dev_id);
+
+/*
+ * The physical standard ops mean that the iommufd_device is bound to the
+ * physical device vdev->dev that was provided to vfio_init_group_dev(). Drivers
+ * using this ops set should call vfio_register_group_dev()
+ */
+int vfio_iommufd_physical_bind(struct vfio_device *vdev,
+			       struct iommufd_ctx *ictx, u32 *out_device_id)
+{
+	struct iommufd_device *idev;
+
+	idev = iommufd_device_bind(ictx, vdev->dev, out_device_id);
+	if (IS_ERR(idev))
+		return PTR_ERR(idev);
+	vdev->iommufd_device = idev;
+	ida_init(&vdev->pasids);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(vfio_iommufd_physical_bind);
+
+void vfio_iommufd_physical_unbind(struct vfio_device *vdev)
+{
+	int pasid;
+
+	lockdep_assert_held(&vdev->dev_set->lock);
+
+	while ((pasid = ida_find_first(&vdev->pasids)) >= 0) {
+		iommufd_device_detach(vdev->iommufd_device, pasid);
+		ida_free(&vdev->pasids, pasid);
+	}
+
+	if (vdev->iommufd_attached) {
+		iommufd_device_detach(vdev->iommufd_device, IOMMU_NO_PASID);
+		vdev->iommufd_attached = false;
+	}
+	iommufd_device_unbind(vdev->iommufd_device);
+	vdev->iommufd_device = NULL;
+}
+EXPORT_SYMBOL_GPL(vfio_iommufd_physical_unbind);
+
+int vfio_iommufd_physical_attach_ioas(struct vfio_device *vdev, u32 *pt_id)
+{
+	int rc;
+
+	lockdep_assert_held(&vdev->dev_set->lock);
+
+	if (WARN_ON(!vdev->iommufd_device))
+		return -EINVAL;
+
+	if (vdev->iommufd_attached)
+		rc = iommufd_device_replace(vdev->iommufd_device,
+					    IOMMU_NO_PASID, pt_id);
+	else
+		rc = iommufd_device_attach(vdev->iommufd_device,
+					   IOMMU_NO_PASID, pt_id);
+	if (rc)
+		return rc;
+	vdev->iommufd_attached = true;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(vfio_iommufd_physical_attach_ioas);
+
+void vfio_iommufd_physical_detach_ioas(struct vfio_device *vdev)
+{
+	lockdep_assert_held(&vdev->dev_set->lock);
+
+	if (WARN_ON(!vdev->iommufd_device) || !vdev->iommufd_attached)
+		return;
+
+	iommufd_device_detach(vdev->iommufd_device, IOMMU_NO_PASID);
+	vdev->iommufd_attached = false;
+}
+EXPORT_SYMBOL_GPL(vfio_iommufd_physical_detach_ioas);
+
+int vfio_iommufd_physical_pasid_attach_ioas(struct vfio_device *vdev,
+					    u32 pasid, u32 *pt_id)
+{
+	int rc;
+
+	lockdep_assert_held(&vdev->dev_set->lock);
+
+	if (WARN_ON(!vdev->iommufd_device))
+		return -EINVAL;
+
+	if (ida_exists(&vdev->pasids, pasid))
+		return iommufd_device_replace(vdev->iommufd_device,
+					      pasid, pt_id);
+
+	rc = ida_alloc_range(&vdev->pasids, pasid, pasid, GFP_KERNEL);
+	if (rc < 0)
+		return rc;
+
+	rc = iommufd_device_attach(vdev->iommufd_device, pasid, pt_id);
+	if (rc)
+		ida_free(&vdev->pasids, pasid);
+
+	return rc;
+}
+EXPORT_SYMBOL_GPL(vfio_iommufd_physical_pasid_attach_ioas);
+
+void vfio_iommufd_physical_pasid_detach_ioas(struct vfio_device *vdev,
+					     u32 pasid)
+{
+	lockdep_assert_held(&vdev->dev_set->lock);
+
+	if (WARN_ON(!vdev->iommufd_device))
+		return;
+
+	if (!ida_exists(&vdev->pasids, pasid))
+		return;
+
+	iommufd_device_detach(vdev->iommufd_device, pasid);
+	ida_free(&vdev->pasids, pasid);
+}
+EXPORT_SYMBOL_GPL(vfio_iommufd_physical_pasid_detach_ioas);
+
+/*
+ * The emulated standard ops mean that vfio_device is going to use the
+ * "mdev path" and will call vfio_pin_pages()/vfio_dma_rw(). Drivers using this
+ * ops set should call vfio_register_emulated_iommu_dev(). Drivers that do
+ * not call vfio_pin_pages()/vfio_dma_rw() have no need to provide dma_unmap.
+ */
+
+static void vfio_emulated_unmap(void *data, unsigned long iova,
+				unsigned long length)
+{
+	struct vfio_device *vdev = data;
+
+	if (vdev->ops->dma_unmap)
+		vdev->ops->dma_unmap(vdev, iova, length);
+}
+
+static const struct iommufd_access_ops vfio_user_ops = {
+	.needs_pin_pages = 1,
+	.unmap = vfio_emulated_unmap,
+};
+
+int vfio_iommufd_emulated_bind(struct vfio_device *vdev,
+			       struct iommufd_ctx *ictx, u32 *out_device_id)
+{
+	struct iommufd_access *user;
+
+	lockdep_assert_held(&vdev->dev_set->lock);
+
+	user = iommufd_access_create(ictx, &vfio_user_ops, vdev, out_device_id);
+	if (IS_ERR(user))
+		return PTR_ERR(user);
+	vdev->iommufd_access = user;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(vfio_iommufd_emulated_bind);
+
+void vfio_iommufd_emulated_unbind(struct vfio_device *vdev)
+{
+	lockdep_assert_held(&vdev->dev_set->lock);
+
+	if (vdev->iommufd_access) {
+		iommufd_access_destroy(vdev->iommufd_access);
+		vdev->iommufd_attached = false;
+		vdev->iommufd_access = NULL;
+	}
+}
+EXPORT_SYMBOL_GPL(vfio_iommufd_emulated_unbind);
+
+int vfio_iommufd_emulated_attach_ioas(struct vfio_device *vdev, u32 *pt_id)
+{
+	int rc;
+
+	lockdep_assert_held(&vdev->dev_set->lock);
+
+	if (vdev->iommufd_attached)
+		rc = iommufd_access_replace(vdev->iommufd_access, *pt_id);
+	else
+		rc = iommufd_access_attach(vdev->iommufd_access, *pt_id);
+	if (rc)
+		return rc;
+	vdev->iommufd_attached = true;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(vfio_iommufd_emulated_attach_ioas);
+
+void vfio_iommufd_emulated_detach_ioas(struct vfio_device *vdev)
+{
+	lockdep_assert_held(&vdev->dev_set->lock);
+
+	if (WARN_ON(!vdev->iommufd_access) ||
+	    !vdev->iommufd_attached)
+		return;
+
+	iommufd_access_detach(vdev->iommufd_access);
+	vdev->iommufd_attached = false;
+}
+EXPORT_SYMBOL_GPL(vfio_iommufd_emulated_detach_ioas);