On Fri, 4 Apr 2014 17:22:01 +0800
Daniel Kurtz <djku...@chromium.org> wrote:
> Kernel access to the eyxnos fbdev framebuffer is via its gem object's
> kernel mapping (kvaddr, stored in info->screen_base).
>
> User space access is provided by mmap(), read() and write() of /dev/fb/fb0.
> These functions also only use screen_base/screen_size().
>
> Therefore, it is not necessary to set fix->smem_{start,len} or
> fix->mmio_{start,len} fields.
>
> This avoids leaking kernel, physical and dma mapped addresses to user
> space via the ioctls FBIOGET_VSCREENINFO and FBIOGET_FSCREENINFO.
>
> Signed-off-by: Daniel Kurtz <djku...@chromium.org>
> ---
> drivers/gpu/drm/exynos/exynos_drm_fbdev.c | 7 -------
> 1 file changed, 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_fbdev.c
> b/drivers/gpu/drm/exynos/exynos_drm_fbdev.c
> index 5fa342e..2dcc589 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_fbdev.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_fbdev.c
> @@ -123,14 +123,7 @@ static int exynos_drm_fbdev_update(struct drm_fb_helper
> *helper,
>
> dev->mode_config.fb_base = (resource_size_t)buffer->dma_addr;
> fbi->screen_base = buffer->kvaddr + offset;
> - if (is_drm_iommu_supported(dev))
> - fbi->fix.smem_start = (unsigned long)
> - (page_to_phys(sg_page(buffer->sgt->sgl)) + offset);
> - else
> - fbi->fix.smem_start = (unsigned long)buffer->dma_addr;
> -
> fbi->screen_size = size;
> - fbi->fix.smem_len = size;
Can we keep proper initialization of 'smem_len'? Some userland
applications use it for calculating the size for mmap:
http://cgit.freedesktop.org/xorg/xserver/tree/hw/xfree86/fbdevhw/fbdevhw.c?id=xorg-server-1.15.99.903#n571
>
> return 0;
> }
Basically, this patch breaks the xf86-video-fbdev ddx and some users
are already unhappy.
--
Best regards,
Siarhei Siamashka
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