2018-09-06 07:31:07

by Gerd Hoffmann

Subject: [PATCH] drm: refuse ADDFB2 ioctl for broken bigendian drivers

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 <[email protected]>
---
drivers/gpu/drm/drm_ioctl.c | 25 ++++++++++++++++++++++++-
1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
index ea10e9a26a..08e48bda23 100644
--- a/drivers/gpu/drm/drm_ioctl.c
+++ b/drivers/gpu/drm/drm_ioctl.c
@@ -469,6 +469,29 @@ static int drm_copy_field(char __user *buf, size_t *buf_len, const char *value)
return 0;
}

+static int drm_mode_addfb2_check(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.
+ */
+ return -EINVAL;
+ }
+#endif
+ return drm_mode_addfb2(dev, data, file_priv);
+}
+
/*
* Get version information
*
@@ -645,7 +668,7 @@ 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_check, 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),
--
2.9.3

2018-09-06 07:34:10

by Daniel Vetter

Subject: Re: [PATCH] drm: refuse ADDFB2 ioctl for broken bigendian drivers

On Thu, Sep 06, 2018 at 09:28:50AM +0200, Gerd Hoffmann wrote:
> 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 <[email protected]>
> ---
> drivers/gpu/drm/drm_ioctl.c | 25 ++++++++++++++++++++++++-
> 1 file changed, 24 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
> index ea10e9a26a..08e48bda23 100644
> --- a/drivers/gpu/drm/drm_ioctl.c
> +++ b/drivers/gpu/drm/drm_ioctl.c
> @@ -469,6 +469,29 @@ static int drm_copy_field(char __user *buf, size_t *buf_len, const char *value)
> return 0;
> }
>
> +static int drm_mode_addfb2_check(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 would be good here I think, just to help userspace people
figure out why they got an -EINVAL.

> + return -EINVAL;
> + }
> +#endif
> + return drm_mode_addfb2(dev, data, file_priv);

I think it'd be better if we have all the addfb code in drm_framebuffer.c.
So leave the function name, and extract the common code into
__drm_mode_addfb2 helper.

With these two nits addressed:

Reviewed-by: Daniel Vetter <[email protected]>

> +}
> +
> /*
> * Get version information
> *
> @@ -645,7 +668,7 @@ 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_check, 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),
> --
> 2.9.3
>
> _______________________________________________
> dri-devel mailing list
> [email protected]
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch