drm/msm: Add a way to override processes comm/cmdline

In the cause of using the GPU via virtgpu, the host side process is
really a sort of proxy, and not terribly interesting from the PoV of
crash/fault logging.  Add a way to override these per process so that
we can see the guest process's name.

v2: Handle kmalloc failure, add comment to explain kstrdup returns
    NULL if passed NULL [Dan Carpenter]

Signed-off-by: Rob Clark <robdclark@chromium.org>
Link: https://lore.kernel.org/r/20220317165144.222101-4-robdclark@gmail.com
Signed-off-by: Rob Clark <robdclark@chromium.org>

include/uapi/drm/msm_drm.h

@@ -82,6 +82,8 @@ struct drm_msm_timespec {
 #define MSM_PARAM_FAULTS     0x09  /* RO */
 #define MSM_PARAM_SUSPENDS   0x0a  /* RO */
 #define MSM_PARAM_SYSPROF    0x0b  /* WO: 1 preserves perfcntrs, 2 also disables suspend */
+#define MSM_PARAM_COMM       0x0c  /* WO: override for task->comm */
+#define MSM_PARAM_CMDLINE    0x0d  /* WO: override for task cmdline */
 
 /* For backwards compat.  The original support for preemption was based on
  * a single ring per priority level so # of priority levels equals the #