[Mesa-dev] [PATCH] mesa: fix mipmap generation for immutable, compressed textures

[Roland Scheidegger]

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Am 20.09.2015 um 04:33 schrieb sroland at vmware.com:
> From: Roland Scheidegger <sroland at vmware.com>
> 
> If the immutable compressed texture didn't have the full mip pyramid,
> this didn't work, because it tried to generate mip levels for non-existing
> levels. _mesa_prepare_mipmap_level() would correctly handle this by returning
> FALSE if the mip level didn't exist, however we actually created the
> non-existing mip level right before that because we used _mesa_get_tex_image()
> before calling _mesa_prepare_mipmap_level(). It would then proceed to crash
> (we allocated the mip level, which is a bad idea on an immutable texture,
> but didn't initialize the values, leading to assertion failures or segfaults).
> Fix this by using _mesa_select_tex_image() instead and call it after
> _mesa_prepare_mipmap_level(), as that function will allocate missing mip levels
> for non-immutable textures already.
> This fixes a (2 year old) crash with astromenace which was hack-fixed in ubuntu
> packages instead: http://bugs.debian.org/718680 (I guess most apps do full mip
> chains - I believe this app not doing it is actually unintentional, always one
> level less than full mip chain...).
> 
> Cc: "10.6 11.0" <mesa-stable at lists.freedesktop.org>
> ---
>  src/mesa/main/mipmap.c | 36 +++++++++++++++---------------------
>  1 file changed, 15 insertions(+), 21 deletions(-)
> 
> diff --git a/src/mesa/main/mipmap.c b/src/mesa/main/mipmap.c
> index 2bf5902..ab16c28 100644
> --- a/src/mesa/main/mipmap.c
> +++ b/src/mesa/main/mipmap.c
> @@ -1922,11 +1922,8 @@ generate_mipmap_uncompressed(struct gl_context *ctx, GLenum target,
>        }
>  
>        /* get dest gl_texture_image */
> -      dstImage = _mesa_get_tex_image(ctx, texObj, target, level + 1);
> -      if (!dstImage) {
> -         _mesa_error(ctx, GL_OUT_OF_MEMORY, "generating mipmaps");
> -         return;
> -      }
> +      dstImage = _mesa_select_tex_image(texObj, target, level + 1);
> +      assert(dstImage);
>  
>        if (target == GL_TEXTURE_1D_ARRAY) {
>  	 srcDepth = srcHeight;
> @@ -2110,7 +2107,19 @@ generate_mipmap_compressed(struct gl_context *ctx, GLenum target,
>                                           srcWidth, srcHeight, srcDepth,
>                                           &dstWidth, &dstHeight, &dstDepth);
>        if (!nextLevel)
> -	 break;
> +	 goto end;
> +
> +      if (!_mesa_prepare_mipmap_level(ctx, texObj, level + 1,
> +                                      dstWidth, dstHeight, dstDepth,
> +                                      border, srcImage->InternalFormat,
> +                                      srcImage->TexFormat)) {
> +         /* all done */
> +         goto end;
> +      }
> +
> +      /* get dest gl_texture_image */
> +      dstImage = _mesa_select_tex_image(texObj, target, level + 1);
> +      assert(dstImage);
>  
>        /* Compute dst image strides and alloc memory on first iteration */
>        temp_dst_row_stride = _mesa_format_row_stride(temp_format, dstWidth);
> @@ -2124,13 +2133,6 @@ generate_mipmap_compressed(struct gl_context *ctx, GLenum target,
>  	 }
>        }
>  
> -      /* get dest gl_texture_image */
> -      dstImage = _mesa_get_tex_image(ctx, texObj, target, level + 1);
> -      if (!dstImage) {
> -         _mesa_error(ctx, GL_OUT_OF_MEMORY, "generating mipmaps");
> -         goto end;
> -      }
> -
>        /* for 2D arrays, setup array[depth] of slice pointers */
>        for (i = 0; i < srcDepth; i++) {
>           temp_src_slices[i] = temp_src + temp_src_img_stride * i;
> @@ -2149,14 +2151,6 @@ generate_mipmap_compressed(struct gl_context *ctx, GLenum target,
>                                    dstWidth, dstHeight, dstDepth,
>                                    temp_dst_slices, temp_dst_row_stride);
>  
> -      if (!_mesa_prepare_mipmap_level(ctx, texObj, level + 1,
> -                                      dstWidth, dstHeight, dstDepth,
> -                                      border, srcImage->InternalFormat,
> -                                      srcImage->TexFormat)) {
> -         /* all done */
> -         goto end;
> -      }
> -
>        /* The image space was allocated above so use glTexSubImage now */
>        ctx->Driver.TexSubImage(ctx, 2, dstImage,
>                                0, 0, 0, dstWidth, dstHeight, dstDepth,
>