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Date: Sat, 13 Nov 2021 11:45:50 +0200
From: Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>
To: tomba@...nel.org
Cc: matthijsvanduin@...il.com, airlied@...ux.ie, daniel@...ll.ch,
linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org
Subject: Re: [PATCH] drm: omapdrm: Export correct scatterlist for TILER backed
BOs
On 13.11.21 г. 11:40 ч., Ivaylo Dimitrov wrote:
> Memory of BOs backed by TILER is not contiguous, but omap_gem_map_dma_buf()
> exports it like it is. This leads to (possibly) invalid memory accesses if
> another device imports such a BO.
>
> Fix that by providing a scatterlist that correctly describes TILER memory
> layout.
>
> Suggested-by: Matthijs van Duin <matthijsvanduin@...il.com>
> Signed-off-by: Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>
> ---
> drivers/gpu/drm/omapdrm/omap_gem.c | 78 ++++++++++++++++++++++++++++++-
> drivers/gpu/drm/omapdrm/omap_gem.h | 3 +-
> drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c | 32 ++-----------
> 3 files changed, 83 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c b/drivers/gpu/drm/omapdrm/omap_gem.c
> index 97e5fe6..a1a18bb 100644
> --- a/drivers/gpu/drm/omapdrm/omap_gem.c
> +++ b/drivers/gpu/drm/omapdrm/omap_gem.c
> @@ -48,7 +48,7 @@ struct omap_gem_object {
> * OMAP_BO_MEM_DMA_API flag set)
> *
> * - buffers imported from dmabuf (with the OMAP_BO_MEM_DMABUF flag set)
> - * if they are physically contiguous (when sgt->orig_nents == 1)
> + * if they are physically contiguous (when sgt->nents == 1)
> *
Ugh, this should not be here, will send new patch
> * - buffers mapped through the TILER when dma_addr_cnt is not zero, in
> * which case the DMA address points to the TILER aperture
> @@ -862,6 +862,11 @@ static void omap_gem_unpin_locked(struct drm_gem_object *obj)
> return;
>
> if (refcount_dec_and_test(&omap_obj->dma_addr_cnt)) {
> + if (omap_obj->sgt) {
> + sg_free_table(omap_obj->sgt);
> + kfree(omap_obj->sgt);
> + omap_obj->sgt = NULL;
> + }
> ret = tiler_unpin(omap_obj->block);
> if (ret) {
> dev_err(obj->dev->dev,
> @@ -974,6 +979,77 @@ int omap_gem_put_pages(struct drm_gem_object *obj)
> return 0;
> }
>
> +struct sg_table *omap_gem_get_sg(struct drm_gem_object *obj)
> +{
> + struct omap_gem_object *omap_obj = to_omap_bo(obj);
> + dma_addr_t addr;
> + struct sg_table *sgt;
> + struct scatterlist *sg;
> + unsigned int count, len, stride, i;
> + int ret;
> +
> + ret = omap_gem_pin(obj, &addr);
> + if (ret)
> + return ERR_PTR(ret);
> +
> + mutex_lock(&omap_obj->lock);
> +
> + sgt = omap_obj->sgt;
> + if (sgt)
> + goto out;
> +
> + sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
> + ret = -ENOMEM;
> + if (!sgt)
> + goto out_unpin;
> +
> + if (omap_obj->flags & OMAP_BO_TILED_MASK) {
> + enum tiler_fmt fmt = gem2fmt(omap_obj->flags);
> +
> + len = omap_obj->width << (int)fmt;
> + count = omap_obj->height;
> + stride = tiler_stride(fmt, 0);
> + } else {
> + len = obj->size;
> + count = 1;
> + stride = 0;
> + }
> +
> + ret = sg_alloc_table(sgt, count, GFP_KERNEL);
> + if (ret)
> + goto out_free;
> +
> + for_each_sg(sgt->sgl, sg, count, i) {
> + sg_set_page(sg, phys_to_page(addr), len, offset_in_page(addr));
> + sg_dma_address(sg) = addr;
> + sg_dma_len(sg) = len;
> +
> + addr += stride;
> + }
> +
> + omap_obj->sgt = sgt;
> +out:
> + mutex_unlock(&omap_obj->lock);
> + return sgt;
> +
> +out_free:
> + kfree(sgt);
> +out_unpin:
> + mutex_unlock(&omap_obj->lock);
> + omap_gem_unpin(obj);
> + return ERR_PTR(ret);
> +}
> +
> +void omap_gem_put_sg(struct drm_gem_object *obj, struct sg_table *sgt)
> +{
> + struct omap_gem_object *omap_obj = to_omap_bo(obj);
> +
> + if (WARN_ON(omap_obj->sgt != sgt))
> + return;
> +
> + omap_gem_unpin(obj);
> +}
> +
> #ifdef CONFIG_DRM_FBDEV_EMULATION
> /*
> * Get kernel virtual address for CPU access.. this more or less only
> diff --git a/drivers/gpu/drm/omapdrm/omap_gem.h b/drivers/gpu/drm/omapdrm/omap_gem.h
> index eda9b48..3b61cfc 100644
> --- a/drivers/gpu/drm/omapdrm/omap_gem.h
> +++ b/drivers/gpu/drm/omapdrm/omap_gem.h
> @@ -77,10 +77,11 @@ void omap_gem_dma_sync_buffer(struct drm_gem_object *obj,
> int omap_gem_get_pages(struct drm_gem_object *obj, struct page ***pages,
> bool remap);
> int omap_gem_put_pages(struct drm_gem_object *obj);
> -
> u32 omap_gem_flags(struct drm_gem_object *obj);
> int omap_gem_rotated_dma_addr(struct drm_gem_object *obj, u32 orient,
> int x, int y, dma_addr_t *dma_addr);
> int omap_gem_tiled_stride(struct drm_gem_object *obj, u32 orient);
> +struct sg_table *omap_gem_get_sg(struct drm_gem_object *obj);
> +void omap_gem_put_sg(struct drm_gem_object *obj, struct sg_table *sgt);
>
> #endif /* __OMAPDRM_GEM_H__ */
> diff --git a/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c b/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c
> index f4cde3a..9650416 100644
> --- a/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c
> +++ b/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c
> @@ -21,45 +21,21 @@ static struct sg_table *omap_gem_map_dma_buf(
> {
> struct drm_gem_object *obj = attachment->dmabuf->priv;
> struct sg_table *sg;
> - dma_addr_t dma_addr;
> - int ret;
> -
> - sg = kzalloc(sizeof(*sg), GFP_KERNEL);
> - if (!sg)
> - return ERR_PTR(-ENOMEM);
> -
> - /* camera, etc, need physically contiguous.. but we need a
> - * better way to know this..
> - */
> - ret = omap_gem_pin(obj, &dma_addr);
> - if (ret)
> - goto out;
> -
> - ret = sg_alloc_table(sg, 1, GFP_KERNEL);
> - if (ret)
> - goto out;
> -
> - sg_init_table(sg->sgl, 1);
> - sg_dma_len(sg->sgl) = obj->size;
> - sg_set_page(sg->sgl, pfn_to_page(PFN_DOWN(dma_addr)), obj->size, 0);
> - sg_dma_address(sg->sgl) = dma_addr;
> + sg = omap_gem_get_sg(obj);
> + if (IS_ERR(sg))
> + return sg;
>
> /* this must be after omap_gem_pin() to ensure we have pages attached */
> omap_gem_dma_sync_buffer(obj, dir);
>
> return sg;
> -out:
> - kfree(sg);
> - return ERR_PTR(ret);
> }
>
> static void omap_gem_unmap_dma_buf(struct dma_buf_attachment *attachment,
> struct sg_table *sg, enum dma_data_direction dir)
> {
> struct drm_gem_object *obj = attachment->dmabuf->priv;
> - omap_gem_unpin(obj);
> - sg_free_table(sg);
> - kfree(sg);
> + omap_gem_put_sg(obj, sg);
> }
>
> static int omap_gem_dmabuf_begin_cpu_access(struct dma_buf *buffer,
>
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