bpf: mark a NULL kfunc argument precisegrafted

check_kfunc_arg() allows bpf_register_is_null() for nullable arguments
w/o marking the underlying scalar register precise. Hence a checkpoint
created on such a path would prune against arbitrary scalar value.

Fixes: 3bda08b63670 ("bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 23 insertions, 0 deletions

diff --git a/Documentation/driver-api/wmi.rst b/Documentation/driver-api/wmi.rst
new file mode 100644
index 000000000..b847bcdcb
--- /dev/null
+++ b/Documentation/driver-api/wmi.rst
@@ -0,0 +1,23 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+==============
+WMI Driver API
+==============
+
+The WMI driver core supports a more modern bus-based interface for interacting
+with WMI devices, and an older GUID-based interface. The latter interface is
+considered to be deprecated, so new WMI drivers should generally avoid it since
+it has some issues with multiple WMI devices sharing the same GUID.
+The modern bus-based interface instead maps each WMI device to a
+:c:type:`struct wmi_device <wmi_device>`, so it supports WMI devices sharing the
+same GUID. Drivers can then register a :c:type:`struct wmi_driver <wmi_driver>`
+which will be bound to compatible WMI devices by the driver core.
+
+.. kernel-doc:: include/linux/wmi.h
+   :internal:
+
+.. kernel-doc:: drivers/platform/wmi/string.c
+   :export:
+
+.. kernel-doc:: drivers/platform/wmi/core.c
+   :export: