Hi,
> I think if we do an mmap callback, it should replace all the mmap handling
> (except the drm_gem_object_get) that drm_gem_mmap_obj does. So maybe
> something like the below:
[ snip ]
> Since I remember quite a few discussions where the default vma flag
> wrangling we're doing is seriously getting in the way of things too.
Yep, makes sense.
> I think even better would be if this new ->mmap hook could also be used
> directly by the dma-buf mmap code, without having to jump through hoops
> creating a fake file and fake vma offset and everything. I think with that
> we'd have a really solid case to add this ->mmap hook.
Looks easy on a quick glance. So something like the patch below (quick
sketch, not tested yet other than compiling it)?
cheers,
Gerd
>From c13b30d776fb593a03473fa3bc93baf470cba728 Mon Sep 17 00:00:00 2001
From: Gerd Hoffmann <kraxel@xxxxxxxxxx>
Date: Wed, 19 Jun 2019 14:26:51 +0200
Subject: [PATCH] drm: add mmap() to drm_gem_object_funcs
drm_gem_object_funcs->vm_ops alone can't handle everything which needs
to be done for mmap(), tweaking vm_flags for example. So add a new
mmap() callback to drm_gem_object_funcs where this code can go to.
Note that the vm_ops field is not used in case the mmap callback is
presnt, it is expected that the callback sets vma->vm_ops instead.
drm_gem_mmap_obj() will use the new callback for object specific mmap
setup. With this in place the need for driver-speific fops->mmap
callbacks goes away, drm_gem_mmap can be hooked instead.
drm_gem_prime_mmap() will use the new callback too to just mmap gem
objects directly instead of jumping though loops to make
drm_gem_object_lookup() and fops->mmap work.
Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
---
include/drm/drm_gem.h | 14 ++++++++++++++
drivers/gpu/drm/drm_gem.c | 26 +++++++++++++++++---------
drivers/gpu/drm/drm_prime.c | 9 +++++++++
3 files changed, 40 insertions(+), 9 deletions(-)
diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
index 6aaba14f5972..e71f75a2ab57 100644
--- a/include/drm/drm_gem.h
+++ b/include/drm/drm_gem.h
@@ -150,6 +150,20 @@ struct drm_gem_object_funcs {
*/
void (*vunmap)(struct drm_gem_object *obj, void *vaddr);
+ /**
+ * @mmap:
+ *
+ * Handle mmap() of the gem object, setup vma accordingly.
+ *
+ * This callback is optional.
+ *
+ * The callback is used by by both drm_gem_mmap_obj() and
+ * drm_gem_prime_mmap(). When @mmap is present @vm_ops is not
+ * used, the @mmap callback must set vma->vm_ops instead.
+ *
+ */
+ int (*mmap)(struct drm_gem_object *obj, struct vm_area_struct *vma);
+
/**
* @vm_ops:
*
diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 6854f5867d51..aabde003ac4a 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -1099,22 +1099,30 @@ int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size,
struct vm_area_struct *vma)
{
struct drm_device *dev = obj->dev;
+ int ret;
/* Check for valid size. */
if (obj_size < vma->vm_end - vma->vm_start)
return -EINVAL;
- if (obj->funcs && obj->funcs->vm_ops)
- vma->vm_ops = obj->funcs->vm_ops;
- else if (dev->driver->gem_vm_ops)
- vma->vm_ops = dev->driver->gem_vm_ops;
- else
- return -EINVAL;
+ if (obj->funcs && obj->funcs->mmap) {
+ ret = obj->funcs->mmap(obj, vma);
+ if (ret)
+ return ret;
+ } else {
+ if (obj->funcs && obj->funcs->vm_ops)
+ vma->vm_ops = obj->funcs->vm_ops;
+ else if (dev->driver->gem_vm_ops)
+ vma->vm_ops = dev->driver->gem_vm_ops;
+ else
+ return -EINVAL;
+
+ vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
+ vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
+ vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
+ }
- vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
vma->vm_private_data = obj;
- vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
- vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
/* Take a ref for this mapping of the object, so that the fault
* handler can dereference the mmap offset's pointer to the object.
diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index 0a2316e0e812..0814211b0f3f 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -713,6 +713,15 @@ int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
struct file *fil;
int ret;
+ if (obj->funcs && obj->funcs->mmap) {
+ ret = obj->funcs->mmap(obj, vma);
+ if (ret)
+ return ret;
+ vma->vm_private_data = obj;
+ drm_gem_object_get(obj);
+ return 0;
+ }
+
priv = kzalloc(sizeof(*priv), GFP_KERNEL);
fil = kzalloc(sizeof(*fil), GFP_KERNEL);
if (!priv || !fil) {
--
2.18.1
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