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[PATCH] drm, i915: Fix pointer size cast

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  [PATCH] drm, i915: Fix pointer size cast Borislav Petkov <bp@alien8.de> - 2015-12-21 20:00 +0100
    Re: [Intel-gfx] [PATCH] drm, i915: Fix pointer size cast Daniel Vetter <daniel@ffwll.ch> - 2015-12-21 20:30 +0100

#1296150 — [PATCH] drm, i915: Fix pointer size cast

From: Borislav Petkov <bp@suse.de>

gcc complains on 32-bit like this:

  drivers/gpu/drm/i915/intel_display.c: In function ‘intel_plane_obj_offset’:
  drivers/gpu/drm/i915/intel_display.c:2954:11: warning: cast to pointer from \
	  integer of different size [-Wint-to-pointer-cast]
    offset = (unsigned char *)vma->node.start;
             ^

because vma->node.start is u64 but a pointer on 32-bit is 4 bytes.

Do the calculations with an unsigned long directly and save us the
casts.

Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: David Airlie <airlied@linux.ie>
Cc: intel-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Borislav Petkov <bp@suse.de>
---
 drivers/gpu/drm/i915/intel_display.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 62211abe4922..640cb7c9b7f3 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2941,7 +2941,7 @@ unsigned long intel_plane_obj_offset(struct intel_plane *intel_plane,
 {
 	const struct i915_ggtt_view *view = &i915_ggtt_view_normal;
 	struct i915_vma *vma;
-	unsigned char *offset;
+	unsigned long offset;
 
 	if (intel_rotation_90_or_270(intel_plane->base.state->rotation))
 		view = &i915_ggtt_view_rotated;
@@ -2951,14 +2951,14 @@ unsigned long intel_plane_obj_offset(struct intel_plane *intel_plane,
 		view->type))
 		return -1;
 
-	offset = (unsigned char *)vma->node.start;
+	offset = vma->node.start;
 
 	if (plane == 1) {
 		offset += vma->ggtt_view.rotation_info.uv_start_page *
 			  PAGE_SIZE;
 	}
 
-	return (unsigned long)offset;
+	return offset;
 }
 
 static void skl_detach_scaler(struct intel_crtc *intel_crtc, int id)
-- 
2.3.5

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#1296168 — Re: [Intel-gfx] [PATCH] drm, i915: Fix pointer size cast

On Mon, Dec 21, 2015 at 07:53:59PM +0100, Borislav Petkov wrote:
> From: Borislav Petkov <bp@suse.de>
> 
> gcc complains on 32-bit like this:
> 
>   drivers/gpu/drm/i915/intel_display.c: In function ‘intel_plane_obj_offset’:
>   drivers/gpu/drm/i915/intel_display.c:2954:11: warning: cast to pointer from \
> 	  integer of different size [-Wint-to-pointer-cast]
>     offset = (unsigned char *)vma->node.start;
>              ^
> 
> because vma->node.start is u64 but a pointer on 32-bit is 4 bytes.
> 
> Do the calculations with an unsigned long directly and save us the
> casts.
> 
> Cc: Daniel Vetter <daniel.vetter@intel.com>
> Cc: Jani Nikula <jani.nikula@linux.intel.com>
> Cc: David Airlie <airlied@linux.ie>
> Cc: intel-gfx@lists.freedesktop.org
> Cc: dri-devel@lists.freedesktop.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Borislav Petkov <bp@suse.de>

This has been fixed already in

commit 44eb0cb9620c6a53ec8e7073262e2af8079b727f
Author: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Date:   Fri Oct 30 13:26:15 2015 +0200

    drm/i915: Avoid pointer arithmetic in calculating plane surface offset

Cheers,
Daniel
> ---
>  drivers/gpu/drm/i915/intel_display.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 62211abe4922..640cb7c9b7f3 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -2941,7 +2941,7 @@ unsigned long intel_plane_obj_offset(struct intel_plane *intel_plane,
>  {
>  	const struct i915_ggtt_view *view = &i915_ggtt_view_normal;
>  	struct i915_vma *vma;
> -	unsigned char *offset;
> +	unsigned long offset;
>  
>  	if (intel_rotation_90_or_270(intel_plane->base.state->rotation))
>  		view = &i915_ggtt_view_rotated;
> @@ -2951,14 +2951,14 @@ unsigned long intel_plane_obj_offset(struct intel_plane *intel_plane,
>  		view->type))
>  		return -1;
>  
> -	offset = (unsigned char *)vma->node.start;
> +	offset = vma->node.start;
>  
>  	if (plane == 1) {
>  		offset += vma->ggtt_view.rotation_info.uv_start_page *
>  			  PAGE_SIZE;
>  	}
>  
> -	return (unsigned long)offset;
> +	return offset;
>  }
>  
>  static void skl_detach_scaler(struct intel_crtc *intel_crtc, int id)
> -- 
> 2.3.5
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

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