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>

6 files changed, 253 insertions, 0 deletions

diff --git a/drivers/gpu/drm/nova/Kconfig b/drivers/gpu/drm/nova/Kconfig
new file mode 100644
index 000000000..ba16c7440
--- /dev/null
+++ b/drivers/gpu/drm/nova/Kconfig
@@ -0,0 +1,17 @@
+config DRM_NOVA
+	tristate "Nova DRM driver"
+	depends on 64BIT
+	depends on DRM=y
+	depends on PCI
+	depends on RUST
+	depends on !CPU_BIG_ENDIAN
+	select AUXILIARY_BUS
+	select NOVA_CORE
+	default n
+	help
+	  Choose this if you want to build the Nova DRM driver for Nvidia
+	  GSP-based GPUs.
+
+	  This driver is work in progress and may not be functional.
+
+	  If M is selected, the module will be called nova-drm.
diff --git a/drivers/gpu/drm/nova/Makefile b/drivers/gpu/drm/nova/Makefile
new file mode 100644
index 000000000..6355f7502
--- /dev/null
+++ b/drivers/gpu/drm/nova/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0
+# nova-drm is built from drivers/gpu/Makefile.
+# nova.o (rust-analyzer marker - DO NOT REMOVE).
diff --git a/drivers/gpu/drm/nova/driver.rs b/drivers/gpu/drm/nova/driver.rs
new file mode 100644
index 000000000..60752bccd
--- /dev/null
+++ b/drivers/gpu/drm/nova/driver.rs
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-2.0
+
+use kernel::{
+    auxiliary,
+    device::{
+        Core,
+        DeviceContext, //
+    },
+    drm::{
+        self,
+        gem,
+        ioctl, //
+    },
+    prelude::*,
+    sync::aref::ARef, //
+};
+
+use crate::file::File;
+use crate::gem::NovaObject;
+
+pub(crate) struct NovaDriver;
+
+pub(crate) struct Nova<'bound> {
+    #[expect(unused)]
+    drm: ARef<drm::Device<NovaDriver>>,
+    _reg: drm::Registration<'bound, NovaDriver>,
+}
+
+/// Convienence type alias for the DRM device type for this driver
+pub(crate) type NovaDevice<Ctx = drm::Normal> = drm::Device<NovaDriver, Ctx>;
+
+const INFO: drm::DriverInfo = drm::DriverInfo {
+    major: 0,
+    minor: 0,
+    patchlevel: 0,
+    name: c"nova-drm",
+    desc: c"NVIDIA Graphics and Compute",
+};
+
+const NOVA_CORE_MODULE_NAME: &CStr = c"nova-core";
+const AUXILIARY_NAME: &CStr = c"nova-drm";
+
+kernel::auxiliary_device_table!(
+    AUX_TABLE,
+    <NovaDriver as auxiliary::Driver>::IdInfo,
+    [(
+        auxiliary::DeviceId::new(NOVA_CORE_MODULE_NAME, AUXILIARY_NAME),
+        ()
+    )]
+);
+
+impl auxiliary::Driver for NovaDriver {
+    type IdInfo = ();
+    type Data<'bound> = Nova<'bound>;
+    const ID_TABLE: auxiliary::IdTable<Self::IdInfo> = &AUX_TABLE;
+
+    fn probe<'bound>(
+        adev: &'bound auxiliary::Device<Core<'_>>,
+        _info: &'bound Self::IdInfo,
+    ) -> impl PinInit<Self::Data<'bound>, Error> + 'bound {
+        let drm = drm::UnregisteredDevice::<Self>::new(adev, Ok(()))?;
+        // SAFETY: `reg` is stored in `Nova` and dropped when the driver is unbound; it is
+        // never forgotten.
+        let reg = unsafe { drm::Registration::new(adev.as_ref(), drm, (), 0)? };
+
+        Ok(Nova {
+            drm: reg.device().into(),
+            _reg: reg,
+        })
+    }
+}
+
+#[vtable]
+impl drm::Driver for NovaDriver {
+    type Data = ();
+    type RegistrationData<'a> = ();
+    type File = File;
+    type Object = gem::Object<NovaObject>;
+    type ParentDevice<Ctx: DeviceContext> = auxiliary::Device<Ctx>;
+
+    const INFO: drm::DriverInfo = INFO;
+
+    kernel::declare_drm_ioctls! {
+        (NOVA_GETPARAM, drm_nova_getparam, ioctl::RENDER_ALLOW, File::get_param),
+        (NOVA_GEM_CREATE, drm_nova_gem_create, ioctl::AUTH | ioctl::RENDER_ALLOW, File::gem_create),
+        (NOVA_GEM_INFO, drm_nova_gem_info, ioctl::AUTH | ioctl::RENDER_ALLOW, File::gem_info),
+    }
+}
diff --git a/drivers/gpu/drm/nova/file.rs b/drivers/gpu/drm/nova/file.rs
new file mode 100644
index 000000000..298c02bac
--- /dev/null
+++ b/drivers/gpu/drm/nova/file.rs
@@ -0,0 +1,77 @@
+// SPDX-License-Identifier: GPL-2.0
+
+use crate::driver::{NovaDevice, NovaDriver};
+use crate::gem::NovaObject;
+use kernel::{
+    alloc::flags::*,
+    auxiliary,
+    device::Bound,
+    drm::{
+        self,
+        gem::BaseObject,
+        Registered, //
+    },
+    pci,
+    prelude::*,
+    uapi,
+};
+
+pub(crate) struct File;
+
+impl drm::file::DriverFile for File {
+    type Driver = NovaDriver;
+
+    fn open(_dev: &NovaDevice) -> Result<Pin<KBox<Self>>> {
+        Ok(KBox::new(Self, GFP_KERNEL)?.into())
+    }
+}
+
+impl File {
+    /// IOCTL: get_param: Query GPU / driver metadata.
+    pub(crate) fn get_param(
+        dev: &NovaDevice<Registered>,
+        _reg_data: &(),
+        getparam: &mut uapi::drm_nova_getparam,
+        _file: &drm::File<File>,
+    ) -> Result<u32> {
+        let adev: &auxiliary::Device<Bound> = dev.as_ref();
+        let pdev: &pci::Device<Bound> = adev.parent().try_into()?;
+
+        let value = match getparam.param as u32 {
+            uapi::NOVA_GETPARAM_VRAM_BAR_SIZE => pdev.resource_len(1)?,
+            _ => return Err(EINVAL),
+        };
+
+        getparam.value = Into::<u64>::into(value);
+
+        Ok(0)
+    }
+
+    /// IOCTL: gem_create: Create a new DRM GEM object.
+    pub(crate) fn gem_create(
+        dev: &NovaDevice<Registered>,
+        _reg_data: &(),
+        req: &mut uapi::drm_nova_gem_create,
+        file: &drm::File<File>,
+    ) -> Result<u32> {
+        let obj = NovaObject::new(dev, req.size.try_into()?)?;
+
+        req.handle = obj.create_handle(file)?;
+
+        Ok(0)
+    }
+
+    /// IOCTL: gem_info: Query GEM metadata.
+    pub(crate) fn gem_info(
+        _dev: &NovaDevice<Registered>,
+        _reg_data: &(),
+        req: &mut uapi::drm_nova_gem_info,
+        file: &drm::File<File>,
+    ) -> Result<u32> {
+        let bo = NovaObject::lookup_handle(file, req.handle)?;
+
+        req.size = bo.size().try_into()?;
+
+        Ok(0)
+    }
+}
diff --git a/drivers/gpu/drm/nova/gem.rs b/drivers/gpu/drm/nova/gem.rs
new file mode 100644
index 000000000..2b6fe9dc0
--- /dev/null
+++ b/drivers/gpu/drm/nova/gem.rs
@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: GPL-2.0
+
+use kernel::{
+    drm,
+    drm::{
+        gem,
+        gem::BaseObject, //
+    },
+    page,
+    prelude::*,
+    sync::aref::ARef,
+};
+
+use crate::{
+    driver::{NovaDevice, NovaDriver},
+    file::File,
+};
+
+/// GEM Object inner driver data
+#[pin_data]
+pub(crate) struct NovaObject {}
+
+impl gem::DriverObject for NovaObject {
+    type Driver = NovaDriver;
+    type Args = ();
+
+    fn new(_dev: &NovaDevice, _size: usize, _args: Self::Args) -> impl PinInit<Self, Error> {
+        try_pin_init!(NovaObject {})
+    }
+}
+
+impl NovaObject {
+    /// Create a new DRM GEM object.
+    pub(crate) fn new(dev: &NovaDevice, size: usize) -> Result<ARef<gem::Object<Self>>> {
+        if size == 0 {
+            return Err(EINVAL);
+        }
+        let aligned_size = page::page_align(size).ok_or(EINVAL)?;
+
+        gem::Object::<Self>::new(dev, aligned_size, ())
+    }
+
+    /// Look up a GEM object handle for a `File` and return an `ObjectRef` for it.
+    #[inline]
+    pub(crate) fn lookup_handle(
+        file: &drm::File<File>,
+        handle: u32,
+    ) -> Result<ARef<gem::Object<Self>>> {
+        gem::Object::lookup_handle(file, handle)
+    }
+}
diff --git a/drivers/gpu/drm/nova/nova.rs b/drivers/gpu/drm/nova/nova.rs
new file mode 100644
index 000000000..1fd454c7e
--- /dev/null
+++ b/drivers/gpu/drm/nova/nova.rs
@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Nova DRM Driver
+
+mod driver;
+mod file;
+mod gem;
+
+use crate::driver::NovaDriver;
+
+kernel::module_auxiliary_driver! {
+    type: NovaDriver,
+    name: "nova-drm",
+    authors: ["Danilo Krummrich"],
+    description: "Nova GPU driver",
+    license: "GPL v2",
+}