On Wed, Oct 17, 2018 at 03:04:53PM +0200, Noralf Trønnes wrote:
> This adds a library for shmem backed GEM objects.
>
> v5:
> - Drop drm_gem_shmem_prime_mmap() (Daniel Vetter)
> - drm_gem_shmem_mmap(): Subtract drm_vma_node_start() to get the real
> vma->vm_pgoff
> - drm_gem_shmem_fault(): Use vmf->pgoff now that vma->vm_pgoff is correct
>
> v4:
> - Drop cache modes (Thomas Hellstrom)
> - Add a GEM attached vtable
>
> v3:
> - Grammar (Sam Ravnborg)
> - s/drm_gem_shmem_put_pages_unlocked/drm_gem_shmem_put_pages_locked/
> (Sam Ravnborg)
> - Add debug output in error path (Sam Ravnborg)
>
> Signed-off-by: Noralf Trønnes <nor...@tronnes.org>
> ---
> Documentation/gpu/drm-kms-helpers.rst | 12 +
> drivers/gpu/drm/Kconfig | 6 +
> drivers/gpu/drm/Makefile | 1 +
> drivers/gpu/drm/drm_gem_shmem_helper.c | 551
> +++++++++++++++++++++++++++++++++
> include/drm/drm_gem_shmem_helper.h | 153 +++++++++
> 5 files changed, 723 insertions(+)
> create mode 100644 drivers/gpu/drm/drm_gem_shmem_helper.c
> create mode 100644 include/drm/drm_gem_shmem_helper.h
>
> diff --git a/Documentation/gpu/drm-kms-helpers.rst
> b/Documentation/gpu/drm-kms-helpers.rst
> index 4b4dc236ef6f..8305d3566928 100644
> --- a/Documentation/gpu/drm-kms-helpers.rst
> +++ b/Documentation/gpu/drm-kms-helpers.rst
> @@ -335,3 +335,15 @@ Legacy CRTC/Modeset Helper Functions Reference
>
> .. kernel-doc:: drivers/gpu/drm/drm_crtc_helper.c
> :export:
> +
> +SHMEM GEM Helper Reference
> +==========================
> +
> +.. kernel-doc:: drivers/gpu/drm/drm_gem_shmem_helper.c
> + :doc: overview
> +
> +.. kernel-doc:: include/drm/drm_gem_shmem_helper.h
> + :internal:
> +
> +.. kernel-doc:: drivers/gpu/drm/drm_gem_shmem_helper.c
> + :export:
This doesn't make sense here imo - put them right next to the cma helpers
in drm-mm.rst instead?
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index 736b7e67e4ec..46090a36f52e 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -157,6 +157,12 @@ config DRM_KMS_CMA_HELPER
> help
> Choose this if you need the KMS CMA helper functions
>
> +config DRM_GEM_SHMEM_HELPER
> + bool
> + depends on DRM
> + help
> + Choose this if you need the GEM shmem helper functions
> +
> config DRM_VM
> bool
> depends on DRM && MMU
> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> index 576ba985e138..8733ceb41292 100644
> --- a/drivers/gpu/drm/Makefile
> +++ b/drivers/gpu/drm/Makefile
> @@ -25,6 +25,7 @@ drm-$(CONFIG_DRM_LIB_RANDOM) += lib/drm_random.o
> drm-$(CONFIG_DRM_VM) += drm_vm.o
> drm-$(CONFIG_COMPAT) += drm_ioc32.o
> drm-$(CONFIG_DRM_GEM_CMA_HELPER) += drm_gem_cma_helper.o
> +drm-$(CONFIG_DRM_GEM_SHMEM_HELPER) += drm_gem_shmem_helper.o
> drm-$(CONFIG_PCI) += ati_pcigart.o
> drm-$(CONFIG_DRM_PANEL) += drm_panel.o
> drm-$(CONFIG_OF) += drm_of.o
> diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c
> b/drivers/gpu/drm/drm_gem_shmem_helper.c
> new file mode 100644
> index 000000000000..c4eec51d3282
> --- /dev/null
> +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
> @@ -0,0 +1,551 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright 2018 Noralf Trønnes
> + */
> +
> +#include <linux/dma-buf.h>
> +#include <linux/export.h>
> +#include <linux/mutex.h>
> +#include <linux/shmem_fs.h>
> +#include <linux/slab.h>
> +#include <linux/vmalloc.h>
> +
> +#include <drm/drm_device.h>
> +#include <drm/drm_drv.h>
> +#include <drm/drm_gem_shmem_helper.h>
> +#include <drm/drm_prime.h>
> +#include <drm/drm_print.h>
> +
> +/**
> + * DOC: overview
> + *
> + * This library provides helpers for GEM objects backed by shmem buffers
> + * allocated using anonymous pageable memory.
Would be neat to insert a link to the cma version here (and to the gem
version in the cma helpers) and spend a few words on when to use each.
> + */
> +
> +static const struct drm_gem_object_funcs drm_gem_shmem_funcs = {
> + .free = drm_gem_shmem_free_object,
> + .print_info = drm_gem_shmem_print_info,
> + .pin = drm_gem_shmem_pin,
> + .unpin = drm_gem_shmem_unpin,
> + .get_sg_table = drm_gem_shmem_get_sg_table,
> + .vmap = drm_gem_shmem_vmap,
> + .vunmap = drm_gem_shmem_vunmap,
> + .vm_ops = &drm_gem_shmem_vm_ops,
> +};
> +
> +/**
> + * drm_gem_shmem_create - Allocate an object with the given size
> + * @dev: DRM device
> + * @size: Size of the object to allocate
> + *
> + * This function creates a shmem GEM object.
> + *
> + * Returns:
> + * A struct drm_gem_shmem_object * on success or an ERR_PTR()-encoded
> negative
> + * error code on failure.
> + */
> +struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev,
> size_t size)
> +{
> + struct drm_gem_shmem_object *shmem;
> + struct drm_gem_object *obj;
> + int ret;
> +
> + size = PAGE_ALIGN(size);
> +
> + if (dev->driver->gem_create_object)
> + obj = dev->driver->gem_create_object(dev, size);
> + else
> + obj = kzalloc(sizeof(*shmem), GFP_KERNEL);
> + if (!obj)
> + return ERR_PTR(-ENOMEM);
> +
> + if (!obj->funcs)
> + obj->funcs = &drm_gem_shmem_funcs;
> +
> + ret = drm_gem_object_init(dev, obj, size);
> + if (ret)
> + goto err_free;
> +
> + ret = drm_gem_create_mmap_offset(obj);
> + if (ret)
> + goto err_release;
> +
> + shmem = to_drm_gem_shmem_obj(obj);
> + mutex_init(&shmem->pages_lock);
> + mutex_init(&shmem->vmap_lock);
> +
> + return shmem;
> +
> +err_release:
> + drm_gem_object_release(obj);
> +err_free:
> + kfree(shmem);
> +
> + return ERR_PTR(ret);
> +}
> +EXPORT_SYMBOL_GPL(drm_gem_shmem_create);
> +
> +/**
> + * drm_gem_shmem_free_object - Free resources associated with a shmem GEM
> object
> + * @obj: GEM object to free
> + *
> + * This function cleans up the GEM object state and frees the memory used to
> + * store the object itself.
> + */
> +void drm_gem_shmem_free_object(struct drm_gem_object *obj)
> +{
> + struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> +
> + WARN_ON(shmem->vmap_use_count);
> +
> + if (obj->import_attach) {
> + shmem->pages_use_count--;
> + drm_prime_gem_destroy(obj, shmem->sgt);
> + kvfree(shmem->pages);
> + }
> +
> + WARN_ON(shmem->pages_use_count);
> +
> + drm_gem_object_release(obj);
> + mutex_destroy(&shmem->pages_lock);
> + mutex_destroy(&shmem->vmap_lock);
> + kfree(shmem);
> +}
> +EXPORT_SYMBOL_GPL(drm_gem_shmem_free_object);
> +
> +static int drm_gem_shmem_get_pages_locked(struct drm_gem_shmem_object *shmem)
> +{
> + struct drm_gem_object *obj = &shmem->base;
> + struct page **pages;
> +
> + if (shmem->pages_use_count++ > 0)
> + return 0;
> +
> + pages = drm_gem_get_pages(obj);
I think moving the drm_gem_get/put_pages into the shmem helper here would
be a good cleanup. Plus aligning the prefix to drm_gem_shmem - they really
only work with shmem, not cma gem bo.
> + if (IS_ERR(pages)) {
> + DRM_DEBUG_KMS("Failed to get pages (%ld)\n", PTR_ERR(pages));
> + shmem->pages_use_count = 0;
> + return PTR_ERR(pages);
> + }
> +
> + shmem->pages = pages;
> +
> + return 0;
> +}
> +
> +/*
> + * drm_gem_shmem_get_pages - Allocate backing pages for a shmem GEM object
> + * @shmem: shmem GEM object
> + *
> + * This function makes sure that backing pages exists for the shmem GEM
> object
> + * and increases the use count.
> + *
> + * Returns:
> + * 0 on success or a negative error code on failure.
> + */
> +int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem)
> +{
> + int ret;
> +
> + ret = mutex_lock_interruptible(&shmem->pages_lock);
> + if (ret)
> + return ret;
> + ret = drm_gem_shmem_get_pages_locked(shmem);
> + mutex_unlock(&shmem->pages_lock);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL(drm_gem_shmem_get_pages);
> +
> +static void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object
> *shmem)
> +{
> + struct drm_gem_object *obj = &shmem->base;
> +
> + if (WARN_ON_ONCE(!shmem->pages_use_count))
> + return;
> +
> + if (--shmem->pages_use_count > 0)
> + return;
> +
> + drm_gem_put_pages(obj, shmem->pages,
> + shmem->pages_mark_dirty_on_put,
> + shmem->pages_mark_accessed_on_put);
> + shmem->pages = NULL;
> +}
> +
> +/*
> + * drm_gem_shmem_put_pages - Decrease use count on the backing pages for a
> shmem GEM object
> + * @shmem: shmem GEM object
> + *
> + * This function decreases the use count and puts the backing pages when use
> drops to zero.
> + */
> +void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem)
> +{
> + mutex_lock(&shmem->pages_lock);
> + drm_gem_shmem_put_pages_locked(shmem);
> + mutex_unlock(&shmem->pages_lock);
> +}
> +EXPORT_SYMBOL(drm_gem_shmem_put_pages);
> +
> +/**
> + * drm_gem_shmem_pin - Pin backing pages for a shmem GEM object
> + * @obj: GEM object
> + *
> + * This function makes sure the backing pages are pinned in memory while the
> + * buffer is exported.
> + *
> + * Returns:
> + * 0 on success or a negative error code on failure.
> + */
> +int drm_gem_shmem_pin(struct drm_gem_object *obj)
> +{
> + struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> +
> + return drm_gem_shmem_get_pages(shmem);
> +}
> +EXPORT_SYMBOL(drm_gem_shmem_pin);
> +
> +/**
> + * drm_gem_shmem_unpin - Unpin backing pages for a shmem GEM object
> + * @obj: GEM object
> + *
> + * This function removes the requirement that the backing pages are pinned in
> + * memory.
> + */
> +void drm_gem_shmem_unpin(struct drm_gem_object *obj)
> +{
> + struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> +
> + drm_gem_shmem_put_pages(shmem);
> +}
> +EXPORT_SYMBOL(drm_gem_shmem_unpin);
> +
> +static void *drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem)
> +{
> + struct drm_gem_object *obj = &shmem->base;
> + int ret;
> +
> + if (shmem->vmap_use_count++ > 0)
> + return shmem->vaddr;
> +
> + ret = drm_gem_shmem_get_pages(shmem);
> + if (ret)
> + goto err_zero_use;
> +
> + if (obj->import_attach)
> + shmem->vaddr = dma_buf_vmap(obj->import_attach->dmabuf);
> + else
> + shmem->vaddr = vmap(shmem->pages, obj->size >> PAGE_SHIFT,
> VM_MAP, PAGE_KERNEL);
> +
> + if (!shmem->vaddr) {
> + DRM_DEBUG_KMS("Failed to vmap pages\n");
> + ret = -ENOMEM;
> + goto err_put_pages;
> + }
> +
> + return shmem->vaddr;
> +
> +err_put_pages:
> + drm_gem_shmem_put_pages(shmem);
> +err_zero_use:
> + shmem->vmap_use_count = 0;
> +
> + return ERR_PTR(ret);
> +}
> +
> +/*
> + * drm_gem_shmem_vmap - Create a virtual mapping for a shmem GEM object
> + * @shmem: shmem GEM object
> + *
> + * This function makes sure that a virtual address exists for the buffer
> backing
> + * the shmem GEM object.
> + *
> + * Returns:
> + * 0 on success or a negative error code on failure.
> + */
> +void *drm_gem_shmem_vmap(struct drm_gem_object *obj)
> +{
> + struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> + void *vaddr;
> + int ret;
> +
> + ret = mutex_lock_interruptible(&shmem->vmap_lock);
> + if (ret)
> + return ERR_PTR(ret);
> + vaddr = drm_gem_shmem_vmap_locked(shmem);
> + mutex_unlock(&shmem->vmap_lock);
> +
> + return vaddr;
> +}
> +EXPORT_SYMBOL(drm_gem_shmem_vmap);
> +
> +static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem)
> +{
> + struct drm_gem_object *obj = &shmem->base;
> +
> + if (WARN_ON_ONCE(!shmem->vmap_use_count))
> + return;
> +
> + if (--shmem->vmap_use_count > 0)
> + return;
> +
> + if (obj->import_attach)
> + dma_buf_vunmap(obj->import_attach->dmabuf, shmem->vaddr);
> + else
> + vunmap(shmem->vaddr);
> +
> + shmem->vaddr = NULL;
> + drm_gem_shmem_put_pages(shmem);
> +}
> +
> +/*
> + * drm_gem_shmem_vunmap - Unmap a virtual mapping fo a shmem GEM object
> + * @shmem: shmem GEM object
> + *
> + * This function removes the virtual address when use count drops to zero.
> + */
> +void drm_gem_shmem_vunmap(struct drm_gem_object *obj, void *vaddr)
> +{
> + struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> +
> + mutex_lock(&shmem->vmap_lock);
> + drm_gem_shmem_vunmap_locked(shmem);
> + mutex_unlock(&shmem->vmap_lock);
> +}
> +EXPORT_SYMBOL(drm_gem_shmem_vunmap);
> +
> +static struct drm_gem_shmem_object *
> +drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
> + struct drm_device *dev, size_t size,
> + uint32_t *handle)
> +{
> + struct drm_gem_shmem_object *shmem;
> + int ret;
> +
> + shmem = drm_gem_shmem_create(dev, size);
> + if (IS_ERR(shmem))
> + return shmem;
> +
> + /*
> + * Allocate an id of idr table where the obj is registered
> + * and handle has the id what user can see.
> + */
> + ret = drm_gem_handle_create(file_priv, &shmem->base, handle);
> + /* drop reference from allocate - handle holds it now. */
> + drm_gem_object_put_unlocked(&shmem->base);
> + if (ret)
> + return ERR_PTR(ret);
> +
> + return shmem;
> +}
> +
> +/**
> + * drm_gem_shmem_dumb_create - Create a dumb shmem buffer object
> + * @file: DRM file structure to create the dumb buffer for
> + * @dev: DRM device
> + * @args: IOCTL data
> + *
> + * This function computes the pitch of the dumb buffer and rounds it up to an
> + * integer number of bytes per pixel. Drivers for hardware that doesn't have
> + * any additional restrictions on the pitch can directly use this function as
> + * their &drm_driver.dumb_create callback.
> + *
> + * For hardware with additional restrictions, drivers can adjust the fields
> + * set up by userspace before calling into this function.
> + *
> + * Returns:
> + * 0 on success or a negative error code on failure.
> + */
> +int drm_gem_shmem_dumb_create(struct drm_file *file, struct drm_device *dev,
> + struct drm_mode_create_dumb *args)
> +{
> + u32 min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
> + struct drm_gem_shmem_object *shmem;
> +
> + if (!args->pitch || !args->size) {
> + args->pitch = min_pitch;
> + args->size = args->pitch * args->height;
> + } else {
> + /* ensure sane minimum values */
> + if (args->pitch < min_pitch)
> + args->pitch = min_pitch;
> + if (args->size < args->pitch * args->height)
> + args->size = args->pitch * args->height;
> + }
> +
> + shmem = drm_gem_shmem_create_with_handle(file, dev, args->size,
> &args->handle);
> +
> + return PTR_ERR_OR_ZERO(shmem);
> +}
> +EXPORT_SYMBOL_GPL(drm_gem_shmem_dumb_create);
> +
> +static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf)
> +{
> + struct vm_area_struct *vma = vmf->vma;
> + struct drm_gem_object *obj = vma->vm_private_data;
> + struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> + loff_t num_pages = obj->size >> PAGE_SHIFT;
> + struct page *page;
> +
> + if (vmf->pgoff > num_pages || WARN_ON_ONCE(!shmem->pages))
> + return VM_FAULT_SIGBUS;
> +
> + page = shmem->pages[vmf->pgoff];
> +
> + return vmf_insert_page(vma, vmf->address, page);
> +}
> +
> +static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
> +{
> + struct drm_gem_object *obj = vma->vm_private_data;
> + struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> +
> + drm_gem_shmem_put_pages(shmem);
Imbalance get/put_pages here, if someone forks (which is what calls
vm_ops->open on an existing vma).
> + drm_gem_vm_close(vma);
> +}
> +
> +const struct vm_operations_struct drm_gem_shmem_vm_ops = {
> + .fault = drm_gem_shmem_fault,
> + .open = drm_gem_vm_open,
> + .close = drm_gem_shmem_vm_close,
> +};
> +EXPORT_SYMBOL_GPL(drm_gem_shmem_vm_ops);
> +
> +/**
> + * drm_gem_shmem_mmap - Memory-map a shmem GEM object
> + * @filp: File object
> + * @vma: VMA for the area to be mapped
> + *
> + * This function implements an augmented version of the GEM DRM file mmap
> + * operation for shmem objects. Drivers which employ the shmem helpers should
> + * use this function as their &file_operations.mmap handler in the DRM
> device file's
> + * file_operations structure.
> + *
> + * Instead of directly referencing this function, drivers should use the
> + * DEFINE_DRM_GEM_SHMEM_FOPS() macro.
> + *
> + * Returns:
> + * 0 on success or a negative error code on failure.
> + */
Between cma helpers, gem shmem helpers and the drm_gem_mmap we now have
quite a bit a confusion of mmap functions. I think it'd be good to update
the kerneldoc for drm_gem_mmap() to point at these here (both the shmem
and cma version), so that people prefer to use these helpers here. Direct
call to drm_gem_mmap would only be needed if you want to use your own
vm_ops.
> +int drm_gem_shmem_mmap(struct file *filp, struct vm_area_struct *vma)
> +{
> + struct drm_gem_shmem_object *shmem;
> + int ret;
> +
> + ret = drm_gem_mmap(filp, vma);
> + if (ret)
> + return ret;
> +
> + shmem = to_drm_gem_shmem_obj(vma->vm_private_data);
> +
> + ret = drm_gem_shmem_get_pages(shmem);
> + if (ret) {
> + drm_gem_vm_close(vma);
> + return ret;
> + }
> +
> + /* VM_PFNMAP was set by drm_gem_mmap() */
> + vma->vm_flags &= ~VM_PFNMAP;
> + vma->vm_flags |= VM_MIXEDMAP;
> + vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
> +
> + fput(vma->vm_file);
> + vma->vm_file = get_file(shmem->base.filp);
> + /* Remove the fake offset */
> + vma->vm_pgoff -= drm_vma_node_start(&shmem->base.vma_node);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(drm_gem_shmem_mmap);
Looking through your mmap code there's 2 bits:
- shmem isn't coherent, if you try to actually buffer share this with
prime I expect it'll fail badly. We'd need begin/end_cpu_access
callbacks in dma_buf_ops to make this work. So not entirely sure how
much value there is in implementing the prime mmap stuff (but doesn't
hurt to have it).
- shmem already has an mmap implemtation, you can just use that. Needs a
similar mmap forwarding trick as you've done for prime mmap, but instead
you forward to obj->base.filp. That allows you to cut away all the
vm_ops and everything. I guess we could clean this up in a follow-up,
since it doesn't have an effect on the interfaces exposed to drivers. At
least not a big one, drm_gem_shmem_vm_ops would disappear.
> +
> +/**
> + * drm_gem_shmem_print_info() - Print &drm_gem_shmem_object info for debugfs
> + * @p: DRM printer
> + * @indent: Tab indentation level
> + * @obj: GEM object
Would be good to reference the hook this is meant for:
&drm_gem_object_funcs.print_info, same for all the others. For those
drivers that want to pick&choose.
Cheers, Daniel
> + */
> +void drm_gem_shmem_print_info(struct drm_printer *p, unsigned int indent,
> + const struct drm_gem_object *obj)
> +{
> + const struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> +
> + drm_printf_indent(p, indent, "pages_use_count=%u\n",
> shmem->pages_use_count);
> + drm_printf_indent(p, indent, "vmap_use_count=%u\n",
> shmem->vmap_use_count);
> + drm_printf_indent(p, indent, "vaddr=%p\n", shmem->vaddr);
> +}
> +EXPORT_SYMBOL(drm_gem_shmem_print_info);
> +
> +/**
> + * drm_gem_shmem_get_sg_table - Provide a scatter/gather table of pinned
> + * pages for a shmem GEM object
> + * @obj: GEM object
> + *
> + * This function exports a scatter/gather table suitable for PRIME usage by
> + * calling the standard DMA mapping API.
> + *
> + * Returns:
> + * A pointer to the scatter/gather table of pinned pages or NULL on failure.
> + */
> +struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_object *obj)
> +{
> + struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> +
> + return drm_prime_pages_to_sg(shmem->pages, obj->size >> PAGE_SHIFT);
> +}
> +EXPORT_SYMBOL_GPL(drm_gem_shmem_get_sg_table);
> +
> +/**
> + * drm_gem_shmem_prime_import_sg_table - Produce a shmem GEM object from
> + * another driver's scatter/gather table of pinned pages
> + * @dev: Device to import into
> + * @attach: DMA-BUF attachment
> + * @sgt: Scatter/gather table of pinned pages
> + *
> + * This function imports a scatter/gather table exported via DMA-BUF by
> + * another driver. Drivers that use the shmem helpers should set this as
> their
> + * &drm_driver.gem_prime_import_sg_table callback.
> + *
> + * Returns:
> + * A pointer to a newly created GEM object or an ERR_PTR-encoded negative
> + * error code on failure.
> + */
> +struct drm_gem_object *
> +drm_gem_shmem_prime_import_sg_table(struct drm_device *dev,
> + struct dma_buf_attachment *attach,
> + struct sg_table *sgt)
> +{
> + size_t size = PAGE_ALIGN(attach->dmabuf->size);
> + size_t npages = size >> PAGE_SHIFT;
> + struct drm_gem_shmem_object *shmem;
> + int ret;
> +
> + shmem = drm_gem_shmem_create(dev, size);
> + if (IS_ERR(shmem))
> + return ERR_CAST(shmem);
> +
> + shmem->pages = kvmalloc_array(npages, sizeof(struct page *),
> GFP_KERNEL);
> + if (!shmem->pages) {
> + ret = -ENOMEM;
> + goto err_free_gem;
> + }
> +
> + ret = drm_prime_sg_to_page_addr_arrays(sgt, shmem->pages, NULL, npages);
> + if (ret < 0)
> + goto err_free_array;
> +
> + shmem->sgt = sgt;
> + shmem->pages_use_count = 1; /* Permanently pinned from our point of
> view */
> +
> + DRM_DEBUG_PRIME("size = %zu\n", size);
> +
> + return &shmem->base;
> +
> +err_free_array:
> + kvfree(shmem->pages);
> +err_free_gem:
> + drm_gem_object_put_unlocked(&shmem->base);
> +
> + return ERR_PTR(ret);
> +}
> +EXPORT_SYMBOL_GPL(drm_gem_shmem_prime_import_sg_table);
> diff --git a/include/drm/drm_gem_shmem_helper.h
> b/include/drm/drm_gem_shmem_helper.h
> new file mode 100644
> index 000000000000..26b05e06407d
> --- /dev/null
> +++ b/include/drm/drm_gem_shmem_helper.h
> @@ -0,0 +1,153 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +#ifndef __DRM_GEM_SHMEM_HELPER_H__
> +#define __DRM_GEM_SHMEM_HELPER_H__
> +
> +#include <linux/fs.h>
> +#include <linux/mm.h>
> +#include <linux/mutex.h>
> +
> +#include <drm/drm_file.h>
> +#include <drm/drm_gem.h>
> +#include <drm/drm_ioctl.h>
> +#include <drm/drm_prime.h>
> +
> +struct dma_buf_attachment;
> +struct drm_mode_create_dumb;
> +struct drm_printer;
> +struct sg_table;
> +
> +/**
> + * struct drm_gem_shmem_object - GEM object backed by shmem
> + */
> +struct drm_gem_shmem_object {
> + /**
> + * @base: Base GEM object
> + */
> + struct drm_gem_object base;
> +
> + /**
> + * @pages_lock: Protects the page table and use count
> + */
> + struct mutex pages_lock;
> +
> + /**
> + * @pages: Page table
> + */
> + struct page **pages;
> +
> + /**
> + * @pages_use_count:
> + *
> + * Reference count on the pages table.
> + * The pages are put when the count reaches zero.
> + */
> + unsigned int pages_use_count;
> +
> + /**
> + * @pages_mark_dirty_on_put:
> + *
> + * Mark pages as dirty when they are put.
> + */
> + unsigned int pages_mark_dirty_on_put : 1;
> +
> + /**
> + * @pages_mark_accessed_on_put:
> + *
> + * Mark pages as accessed when they are put.
> + */
> + unsigned int pages_mark_accessed_on_put : 1;
> +
> + /**
> + * @sgt: Scatter/gather table for imported PRIME buffers
> + */
> + struct sg_table *sgt;
> +
> + /**
> + * @vmap_lock: Protects the vmap address and use count
> + */
> + struct mutex vmap_lock;
> +
> + /**
> + * @vaddr: Kernel virtual address of the backing memory
> + */
> + void *vaddr;
> +
> + /**
> + * @vmap_use_count:
> + *
> + * Reference count on the virtual address.
> + * The address are un-mapped when the count reaches zero.
> + */
> + unsigned int vmap_use_count;
> +};
> +
> +#define to_drm_gem_shmem_obj(obj) \
> + container_of(obj, struct drm_gem_shmem_object, base)
> +
> +/**
> + * DEFINE_DRM_GEM_SHMEM_FOPS() - Macro to generate file operations for shmem
> drivers
> + * @name: name for the generated structure
> + *
> + * This macro autogenerates a suitable &struct file_operations for shmem
> based
> + * drivers, which can be assigned to &drm_driver.fops. Note that this
> structure
> + * cannot be shared between drivers, because it contains a reference to the
> + * current module using THIS_MODULE.
> + *
> + * Note that the declaration is already marked as static - if you need a
> + * non-static version of this you're probably doing it wrong and will break
> the
> + * THIS_MODULE reference by accident.
> + */
> +#define DEFINE_DRM_GEM_SHMEM_FOPS(name) \
> + static const struct file_operations name = {\
> + .owner = THIS_MODULE,\
> + .open = drm_open,\
> + .release = drm_release,\
> + .unlocked_ioctl = drm_ioctl,\
> + .compat_ioctl = drm_compat_ioctl,\
> + .poll = drm_poll,\
> + .read = drm_read,\
> + .llseek = noop_llseek,\
> + .mmap = drm_gem_shmem_mmap, \
> + }
> +
> +struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev,
> size_t size);
> +void drm_gem_shmem_free_object(struct drm_gem_object *obj);
> +
> +int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem);
> +void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem);
> +int drm_gem_shmem_pin(struct drm_gem_object *obj);
> +void drm_gem_shmem_unpin(struct drm_gem_object *obj);
> +void *drm_gem_shmem_vmap(struct drm_gem_object *obj);
> +void drm_gem_shmem_vunmap(struct drm_gem_object *obj, void *vaddr);
> +
> +int drm_gem_shmem_dumb_create(struct drm_file *file, struct drm_device *dev,
> + struct drm_mode_create_dumb *args);
> +
> +int drm_gem_shmem_mmap(struct file *filp, struct vm_area_struct *vma);
> +
> +extern const struct vm_operations_struct drm_gem_shmem_vm_ops;
> +
> +void drm_gem_shmem_print_info(struct drm_printer *p, unsigned int indent,
> + const struct drm_gem_object *obj);
> +
> +struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_object *obj);
> +struct drm_gem_object *
> +drm_gem_shmem_prime_import_sg_table(struct drm_device *dev,
> + struct dma_buf_attachment *attach,
> + struct sg_table *sgt);
> +
> +/**
> + * DRM_GEM_SHMEM_DRIVER_OPS - Default shmem GEM operations
> + *
> + * This macro provides a shortcut for setting the shmem GEM operations in
> + * the &drm_driver structure.
> + */
> +#define DRM_GEM_SHMEM_DRIVER_OPS \
> + .prime_handle_to_fd = drm_gem_prime_handle_to_fd, \
> + .prime_fd_to_handle = drm_gem_prime_fd_to_handle, \
> + .gem_prime_import_sg_table = drm_gem_shmem_prime_import_sg_table, \
> + .gem_prime_mmap = drm_gem_prime_mmap, \
> + .dumb_create = drm_gem_shmem_dumb_create
> +
> +#endif /* __DRM_GEM_SHMEM_HELPER_H__ */
> --
> 2.15.1
>
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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