path: root/drivers/gpu/drm/drm_gem_shmem_helper.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright 2018 Noralf Trønnes
 */

#include <linux/dma-buf.h>
#include <linux/export.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/shmem_fs.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>

#ifdef CONFIG_X86
#include <asm/set_memory.h>
#endif

#include <kunit/visibility.h>

#include <drm/drm.h>
#include <drm/drm_device.h>
#include <drm/drm_drv.h>
#include <drm/drm_dumb_buffers.h>
#include <drm/drm_gem_shmem_helper.h>
#include <drm/drm_prime.h>
#include <drm/drm_print.h>

MODULE_IMPORT_NS("DMA_BUF");

/**
 * DOC: overview
 *
 * This library provides helpers for GEM objects backed by shmem buffers
 * allocated using anonymous pageable memory.
 *
 * Functions that operate on the GEM object receive struct &drm_gem_shmem_object.
 * For GEM callback helpers in struct &drm_gem_object functions, see likewise
 * named functions with an _object_ infix (e.g., drm_gem_shmem_object_vmap() wraps
 * drm_gem_shmem_vmap()). These helpers perform the necessary type conversion.
 */

static const struct drm_gem_object_funcs drm_gem_shmem_funcs = {
	.free = drm_gem_shmem_object_free,
	.print_info = drm_gem_shmem_object_print_info,
	.pin = drm_gem_shmem_object_pin,
	.unpin = drm_gem_shmem_object_unpin,
	.get_sg_table = drm_gem_shmem_object_get_sg_table,
	.vmap = drm_gem_shmem_object_vmap,
	.vunmap = drm_gem_shmem_object_vunmap,
	.mmap = drm_gem_shmem_object_mmap,
	.vm_ops = &drm_gem_shmem_vm_ops,
};

static int __drm_gem_shmem_init(struct drm_device *dev, struct drm_gem_shmem_object *shmem,
				size_t size, bool private)
{
	struct drm_gem_object *obj = &shmem->base;
	int ret = 0;

	if (!obj->funcs)
		obj->funcs = &drm_gem_shmem_funcs;

	if (private) {
		drm_gem_private_object_init(dev, obj, size);
		shmem->map_wc = false; /* dma-buf mappings use always writecombine */
	} else {
		ret = drm_gem_object_init(dev, obj, size);
	}
	if (ret) {
		drm_gem_private_object_fini(obj);
		return ret;
	}

	ret = drm_gem_create_mmap_offset(obj);
	if (ret)
		goto err_release;

	INIT_LIST_HEAD(&shmem->madv_list);

	if (!private) {
		/*
		 * Our buffers are kept pinned, so allocating them
		 * from the MOVABLE zone is a really bad idea, and
		 * conflicts with CMA. See comments above new_inode()
		 * why this is required _and_ expected if you're
		 * going to pin these pages.
		 */
		mapping_set_gfp_mask(obj->filp->f_mapping, GFP_HIGHUSER |
				     __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
	}

	return 0;
err_release:
	drm_gem_object_release(obj);
	return ret;
}

/**
 * drm_gem_shmem_init - Initialize an allocated object.
 * @dev: DRM device
 * @shmem: shmem GEM object to initialize
 * @size: Buffer size in bytes
 *
 * This function initializes an allocated shmem GEM object.
 *
 * Returns:
 * 0 on success, or a negative error code on failure.
 */
int drm_gem_shmem_init(struct drm_device *dev, struct drm_gem_shmem_object *shmem, size_t size)
{
	return __drm_gem_shmem_init(dev, shmem, size, false);
}
EXPORT_SYMBOL_GPL(drm_gem_shmem_init);

static struct drm_gem_shmem_object *
__drm_gem_shmem_create(struct drm_device *dev, size_t size, bool private)
{
	struct drm_gem_shmem_object *shmem;
	struct drm_gem_object *obj;
	int ret = 0;

	size = PAGE_ALIGN(size);

	if (dev->driver->gem_create_object) {
		obj = dev->driver->gem_create_object(dev, size);
		if (IS_ERR(obj))
			return ERR_CAST(obj);
		shmem = to_drm_gem_shmem_obj(obj);
	} else {
		shmem = kzalloc_obj(*shmem);
		if (!shmem)
			return ERR_PTR(-ENOMEM);
		obj = &shmem->base;
	}

	ret = __drm_gem_shmem_init(dev, shmem, size, private);
	if (ret) {
		kfree(obj);
		return ERR_PTR(ret);
	}

	return shmem;
}
/**
 * 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)
{
	return __drm_gem_shmem_create(dev, size, false);
}
EXPORT_SYMBOL_GPL(drm_gem_shmem_create);

/**
 * drm_gem_shmem_release - Release resources associated with a shmem GEM object.
 * @shmem: shmem GEM object
 *
 * This function cleans up the GEM object state, but does not free the memory used to store the
 * object itself. This function is meant to be a dedicated helper for the Rust GEM bindings.
 */
void drm_gem_shmem_release(struct drm_gem_shmem_object *shmem)
{
	struct drm_gem_object *obj = &shmem->base;

	if (drm_gem_is_imported(obj)) {
		drm_prime_gem_destroy(obj, shmem->sgt);
	} else {
		dma_resv_lock(shmem->base.resv, NULL);

		drm_WARN_ON(obj->dev, refcount_read(&shmem->