target/linux/bcm27xx/patches-5.4/950-0272-drm-vc4-Prevent-load-tracking-from-breaking-FKMS.patch

   1 From 907dc84e0c7208b79ad57e0e2a7964dbc9155f50 Mon Sep 17 00:00:00 2001
   2 From: Phil Elwell <phil@raspberrypi.org>
   3 Date: Thu, 15 Aug 2019 08:39:08 +0100
   4 Subject: [PATCH] drm/vc4: Prevent load tracking from breaking FKMS
   5
   6 Firmware KMS uses a mixture of VC4 processing and dedicated code. The
   7 load tracking support in VC4 assumes it is dealing with vc4_plane_state
   8 objects when up-casting with container_of, but FKMS uses unadorned
   9 drm_plane_state structures causing the VC4 code to read off the end
  10 into random portions of memory. Work around the problem in a minimally-
  11 invasive way by over-allocating the FKMS plane state structures to be
  12 large enough to contain a vc4_plane_state, filling the remainder with
  13 zeroes.
  14
  15 Signed-off-by: Phil Elwell <phil@raspberrypi.org>
  16 ---
  17  drivers/gpu/drm/vc4/vc4_firmware_kms.c | 34 ++++++++++++++++++++++++--
  18  1 file changed, 32 insertions(+), 2 deletions(-)
  19
  20 --- a/drivers/gpu/drm/vc4/vc4_firmware_kms.c
  21 +++ b/drivers/gpu/drm/vc4/vc4_firmware_kms.c
  22 @@ -561,6 +561,20 @@ static int vc4_plane_atomic_check(struct
  23         return 0;
  24  }
  25
  26 +/* Called during init to allocate the plane's atomic state. */
  27 +static void vc4_plane_reset(struct drm_plane *plane)
  28 +{
  29 +       struct vc4_plane_state *vc4_state;
  30 +
  31 +       WARN_ON(plane->state);
  32 +
  33 +       vc4_state = kzalloc(sizeof(*vc4_state), GFP_KERNEL);
  34 +       if (!vc4_state)
  35 +               return;
  36 +
  37 +       __drm_atomic_helper_plane_reset(plane, &vc4_state->base);
  38 +}
  39 +
  40  static void vc4_plane_destroy(struct drm_plane *plane)
  41  {
  42         drm_plane_cleanup(plane);
  43 @@ -602,13 +616,29 @@ static bool vc4_fkms_format_mod_supporte
  44         }
  45  }
  46
  47 +static struct drm_plane_state *vc4_plane_duplicate_state(struct drm_plane *plane)
  48 +{
  49 +       struct vc4_plane_state *vc4_state;
  50 +
  51 +       if (WARN_ON(!plane->state))
  52 +               return NULL;
  53 +
  54 +       vc4_state = kzalloc(sizeof(*vc4_state), GFP_KERNEL);
  55 +       if (!vc4_state)
  56 +               return NULL;
  57 +
  58 +       __drm_atomic_helper_plane_duplicate_state(plane, &vc4_state->base);
  59 +
  60 +       return &vc4_state->base;
  61 +}
  62 +
  63  static const struct drm_plane_funcs vc4_plane_funcs = {
  64         .update_plane = drm_atomic_helper_update_plane,
  65         .disable_plane = drm_atomic_helper_disable_plane,
  66         .destroy = vc4_plane_destroy,
  67         .set_property = NULL,
  68 -       .reset = drm_atomic_helper_plane_reset,
  69 -       .atomic_duplicate_state = drm_atomic_helper_plane_duplicate_state,
  70 +       .reset = vc4_plane_reset,
  71 +       .atomic_duplicate_state = vc4_plane_duplicate_state,
  72         .atomic_destroy_state = drm_atomic_helper_plane_destroy_state,
  73         .format_mod_supported = vc4_fkms_format_mod_supported,
  74  };