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drm: refuse ADDFB2 ioctl for broken bigendian drivers
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Drivers must set the quirk_addfb_prefer_host_byte_order quirk to make
the drm_mode_addfb() compat code work correctly on bigendian machines.

If they don't they interpret pixel_format values incorrectly for bug
compatibility, which in turn implies the ADDFB2 ioctl does not work
correctly then.  So block it to make userspace fallback to ADDFB.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20180907073213.20410-1-kraxel@redhat.com
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Gerd Hoffmann committed Sep 10, 2018
1 parent ea4584c commit eae0612
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Showing 3 changed files with 29 additions and 3 deletions.
6 changes: 4 additions & 2 deletions drivers/gpu/drm/drm_crtc_internal.h
Original file line number Diff line number Diff line change
Expand Up @@ -182,15 +182,17 @@ void drm_fb_release(struct drm_file *file_priv);

int drm_mode_addfb(struct drm_device *dev, struct drm_mode_fb_cmd *or,
struct drm_file *file_priv);
int drm_mode_addfb2(struct drm_device *dev,
void *data, struct drm_file *file_priv);
int drm_mode_rmfb(struct drm_device *dev, u32 fb_id,
struct drm_file *file_priv);


/* IOCTL */
int drm_mode_addfb_ioctl(struct drm_device *dev,
void *data, struct drm_file *file_priv);
int drm_mode_addfb2(struct drm_device *dev,
void *data, struct drm_file *file_priv);
int drm_mode_addfb2_ioctl(struct drm_device *dev,
void *data, struct drm_file *file_priv);
int drm_mode_rmfb_ioctl(struct drm_device *dev,
void *data, struct drm_file *file_priv);
int drm_mode_getfb(struct drm_device *dev,
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24 changes: 24 additions & 0 deletions drivers/gpu/drm/drm_framebuffer.c
Original file line number Diff line number Diff line change
Expand Up @@ -369,6 +369,30 @@ int drm_mode_addfb2(struct drm_device *dev,
return 0;
}

int drm_mode_addfb2_ioctl(struct drm_device *dev,
void *data, struct drm_file *file_priv)
{
#ifdef __BIG_ENDIAN
if (!dev->mode_config.quirk_addfb_prefer_host_byte_order) {
/*
* Drivers must set the
* quirk_addfb_prefer_host_byte_order quirk to make
* the drm_mode_addfb() compat code work correctly on
* bigendian machines.
*
* If they don't they interpret pixel_format values
* incorrectly for bug compatibility, which in turn
* implies the ADDFB2 ioctl does not work correctly
* then. So block it to make userspace fallback to
* ADDFB.
*/
DRM_DEBUG_KMS("addfb2 broken on bigendian");
return -EINVAL;
}
#endif
return drm_mode_addfb2(dev, data, file_priv);
}

struct drm_mode_rmfb_work {
struct work_struct work;
struct list_head fbs;
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2 changes: 1 addition & 1 deletion drivers/gpu/drm/drm_ioctl.c
Original file line number Diff line number Diff line change
Expand Up @@ -645,7 +645,7 @@ static const struct drm_ioctl_desc drm_ioctls[] = {
DRM_IOCTL_DEF(DRM_IOCTL_MODE_GETPROPBLOB, drm_mode_getblob_ioctl, DRM_UNLOCKED),
DRM_IOCTL_DEF(DRM_IOCTL_MODE_GETFB, drm_mode_getfb, DRM_UNLOCKED),
DRM_IOCTL_DEF(DRM_IOCTL_MODE_ADDFB, drm_mode_addfb_ioctl, DRM_UNLOCKED),
DRM_IOCTL_DEF(DRM_IOCTL_MODE_ADDFB2, drm_mode_addfb2, DRM_UNLOCKED),
DRM_IOCTL_DEF(DRM_IOCTL_MODE_ADDFB2, drm_mode_addfb2_ioctl, DRM_UNLOCKED),
DRM_IOCTL_DEF(DRM_IOCTL_MODE_RMFB, drm_mode_rmfb_ioctl, DRM_UNLOCKED),
DRM_IOCTL_DEF(DRM_IOCTL_MODE_PAGE_FLIP, drm_mode_page_flip_ioctl, DRM_MASTER|DRM_UNLOCKED),
DRM_IOCTL_DEF(DRM_IOCTL_MODE_DIRTYFB, drm_mode_dirtyfb_ioctl, DRM_MASTER|DRM_UNLOCKED),
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