openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted

sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user
pointers, v1 and v2, and swaps the words they point to in hand-written
assembly.

    l.lwz   r29,0(r4)
    l.lwz   r27,0(r5)
    l.sw    0(r4),r27
    l.sw    0(r5),r29

The pointers are not checked with access_ok(). The four memory
accesses also have no exception table entries.

A caller passes a kernel address as either pointer, and the syscall
reads from and writes to it directly.

This gives an unprivileged process a kernel read/write primitive. It
overwrites kernel data such as the sys_call_table, gaining code
execution in kernel context.

Check both pointers before entering the critical section. Add fixups
for the four memory accesses so faults on valid but unmapped user
addresses return -EFAULT.

[shorne@gmail.com: fix comment style]
Fixes: 9d02a4283e9c ("OpenRISC: Boot code")
Cc: stable@vger.kernel.org
Signed-off-by: Ali Ahmet Memis <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

1 files changed, 49 insertions, 0 deletions

diff --git a/Documentation/gpu/panfrost.rst b/Documentation/gpu/panfrost.rst
new file mode 100644
index 000000000..51ba375fd
--- /dev/null
+++ b/Documentation/gpu/panfrost.rst
@@ -0,0 +1,49 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+=========================
+ drm/Panfrost Mali Driver
+=========================
+
+.. _panfrost-usage-stats:
+
+Panfrost DRM client usage stats implementation
+==============================================
+
+The drm/Panfrost driver implements the DRM client usage stats specification as
+documented in :ref:`drm-client-usage-stats`.
+
+Example of the output showing the implemented key value pairs and entirety of
+the currently possible format options:
+
+::
+      pos:    0
+      flags:  02400002
+      mnt_id: 27
+      ino:    531
+      drm-driver:     panfrost
+      drm-client-id:  14
+      drm-engine-fragment:    1846584880 ns
+      drm-cycles-fragment:    1424359409
+      drm-maxfreq-fragment:   799999987 Hz
+      drm-curfreq-fragment:   799999987 Hz
+      drm-engine-vertex-tiler:        71932239 ns
+      drm-cycles-vertex-tiler:        52617357
+      drm-maxfreq-vertex-tiler:       799999987 Hz
+      drm-curfreq-vertex-tiler:       799999987 Hz
+      drm-total-memory:       290 MiB
+      drm-shared-memory:      0 MiB
+      drm-active-memory:      226 MiB
+      drm-resident-memory:    36496 KiB
+      drm-purgeable-memory:   128 KiB
+
+Possible `drm-engine-` key names are: `fragment`, and  `vertex-tiler`.
+`drm-curfreq-` values convey the current operating frequency for that engine.
+
+Users must bear in mind that engine and cycle sampling are disabled by default,
+because of power saving concerns. `fdinfo` users and benchmark applications which
+query the fdinfo file must make sure to toggle the job profiling status of the
+driver by writing into the appropriate sysfs node::
+
+    echo <N> > /sys/bus/platform/drivers/panfrost/[a-f0-9]*.gpu/profiling
+
+Where `N` is either `0` or `1`, depending on the desired enablement status.