path: root/drivers/dma-buf/heaps/system_heap.c

// SPDX-License-Identifier: GPL-2.0
/*
 * DMABUF System heap exporter
 *
 * Copyright (C) 2011 Google, Inc.
 * Copyright (C) 2019, 2020 Linaro Ltd.
 *
 * Portions based off of Andrew Davis' SRAM heap:
 * Copyright (C) 2019 Texas Instruments Incorporated - http://www.ti.com/
 *	Andrew F. Davis <afd@ti.com>
 */

#include <linux/dma-buf.h>
#include <linux/dma-mapping.h>
#include <linux/dma-heap.h>
#include <linux/err.h>
#include <linux/highmem.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>

static struct dma_heap *sys_heap;

struct system_heap_buffer {
	struct dma_heap *heap;
	struct list_head attachments;
	struct mutex lock;
	unsigned long len;
	struct sg_table sg_table;
	int vmap_cnt;
	void *vaddr;
};

struct dma_heap_attachment {
	struct device *dev;
	struct sg_table *table;
	struct list_head list;
	bool mapped;
};

static struct sg_table *dup_sg_table(struct sg_table *table)
{
	struct sg_table *new_table;
	int ret, i;
	struct scatterlist *sg, *new_sg;

	new_table = kzalloc(sizeof(*new_table), GFP_KERNEL);
	if (!new_table)
		return ERR_PTR(-ENOMEM);

	ret = sg_alloc_table(new_table, table->orig_nents, GFP_KERNEL);
	if (ret) {
		kfree(new_table);
		return ERR_PTR(-ENOMEM);
	}

	new_sg = new_table->sgl;
	for_each_sgtable_sg(table, sg, i) {
		sg_set_page(new_sg, sg_page(sg), sg->length, sg->offset);
		new_sg = sg_next(new_sg);
	}

	return new_table;
}

static int system_heap_attach(struct dma_buf *dmabuf,
			      struct dma_buf_attachment *attachment)
{
	struct system_heap_buffer *buffer = dmabuf->priv;
	struct dma_heap_attachment *a;
	struct sg_table *table;

	a = kzalloc(sizeof(*a), GFP_KERNEL);
	if (!a)
		return -ENOMEM;

	table = dup_sg_table(&buffer->sg_table);
	if (IS_ERR(table)) {
		kfree(a);
		return -ENOMEM;
	}

	a->table = table;
	a->dev = attachment->dev;
	INIT_LIST_HEAD(&a->list);
	a->mapped = false;

	attachment->priv = a;

	mutex_lock(&buffer->lock);
	list_add(&a->list, &buffer->attachments);
	mutex_unlock(&buffer->lock);

	return 0;
}

static void system_heap_detach(struct dma_buf *dmabuf,
			       struct dma_buf_attachment *attachment)
{
	struct system_heap_buffer *buffer = dmabuf->priv;
	struct dma_heap_attachment *a = attachment->priv;

	mutex_lock(&buffer->lock);
	list_del(&a->list);
	mutex_unlock(&buffer->lock);

	sg_free_table(a->table);
	kfree(a->table);
	kfree(a);
}

static struct sg_table *system_heap_map_dma_buf(struct dma_buf_attachment *attachment,
						enum dma_data_direction direction)
{
	struct dma_heap_attachment *a = attachment->priv;
	struct sg_table *table = a->table;
	int ret;

	ret = dma_map_sgtable(attachment->dev, table, direction, 0);
	if (ret)
		return ERR_PTR(ret);

	a->mapped = true;
	return table;
}

static void system_heap_unmap_dma_buf(struct dma_buf_attachment *attachment,
				      struct sg_table *table,
				      enum dma_data_direction direction)
{
	struct dma_heap_attachment *a = attachment->priv;

	a->mapped = false;
	dma_unmap_sgtable(attachment->dev, table, direction, 0);
}

static int system_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
						enum dma_data_direction direction)
{
	struct system_heap_buffer *buffer = dmabuf->priv;
	struct dma_heap_attachment *a;

	mutex_lock(&buffer->lock);

	if (buffer->vmap_cnt)
		invalidate_kernel_vmap_range(buffer->vaddr, buffer->len);

	list_for_each_entry(a, &buffer->attachments, list) {
		if (!a->mapped)
			continue;
		dma_sync_sgtable_for_cpu(a->dev, a->table, direction);
	}
	mutex_unlock(&buffer->lock);

	return 0;
}

static int system_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf,
					      enum dma_data_direction direction)
{
	struct system_heap_buffer *buffer = dmabuf->priv;
	struct dma_heap_attachment *a;

	mutex_lock(&buffer->lock);

	if (buffer->vmap_cnt)
		flush_kernel_vmap_range(buffer->vaddr, buffer->len);

	list_for_each_entry(a, &buffer->attachments, list) {
		if (!a->mapped)
			continue;
		dma_sync_sgtable_for_device(a->dev, a->table, direction);
	}
	mutex_unlock(&buffer->lock);

	return 0;
}

static int system_heap_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma)
{
	struct system_heap_buffer *buffer = dmabuf->priv;
	struct sg_table *table = &buffer->sg_table;
	unsigned long addr = vma->vm_start;
	struct sg_page_iter piter;
	int ret;

	for_each_sgtable_page(table, &piter, vma->vm_pgoff) {
		struct page *page = sg_page_iter_page(&piter);

		ret = remap_pfn_range(vma, addr, page_to_pfn(page), PAGE_SIZE,
				      vma->vm_page_prot);
		if (ret)
			return ret;
		addr += PAGE_SIZE;
		if (addr >= vma->vm_end)
			return 0;
	}
	return 0;
}

static void *system_heap_do_vmap(struct system_heap_buffer *buffer)
{
	struct sg_table *table = &buffer->sg_table;
	int npages = PAGE_ALIGN(buffer->len) / PAGE_SIZE;
	struct page **pages = vmalloc(sizeof(struct page *) * npages);
	struct page **tmp = pages;
	struct sg_page_iter piter;
	void *vaddr;

	if (!pages)
		return ERR_PTR(-ENOMEM);

	for_each_sgtable_page(table, &piter, 0) {
		WARN_ON(tmp - pages >= npages);
		*tmp++ = sg_page_iter_page(&piter);
	}

	vaddr = vmap(pages, npages, VM_MAP, PAGE_KERNEL);
	vfree(pages);

	if (!vaddr)
		return ERR_PTR(-ENOMEM);

	return vaddr;
}

static int system_heap_vmap(struct dma_buf *dmabuf, struct dma_buf_map *map)
{
	struct system_heap_buffer *buffer = dmabuf->priv;
	void *vaddr;
	int ret = 0;

	mutex_lock(&buffer->lock);
	if (buffer->vmap_cnt) {
		buffer->vmap_cnt++;
		dma_buf_map_set_vaddr(map, buffer->vaddr);
		goto out;
	}

	vaddr = system_heap_do_vmap(buffer);
	if (IS_ERR(vaddr)) {
		ret = PTR_ERR(vaddr);
		goto out;
	}

	buffer->vaddr = vaddr;
	buffer->vmap_cnt++;
	dma_buf_map_set_vaddr(map, buffer->vaddr);
out:
	mutex_unlock(&buffer->lock);

	return ret;
}

static void system_heap_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map)
{
	struct system_heap_buffer *buffer = dmabuf->priv;

	mutex_lock(&buffer->lock);
	if (!--buffer->vmap_cnt) {
		vunmap(buffer->vaddr);
		buffer->vaddr = NULL;
	}
	mutex_unlock(&buffer->lock);
	dma_buf_map_clear(map);
}

static void system_heap_dma_buf_release(struct dma_buf *dmabuf)
{
	struct system_heap_buffer *buffer = dmabuf->priv;
	struct sg_table *table;
	struct scatterlist *sg;
	int i;

	table = &buffer->sg_table;
	for_each_sgtable_sg(table, sg, i)
		__free_page(sg_page(sg));
	sg_free_table(table);
	kfree(buffer);
}

static const struct dma_buf_ops system_heap_buf_ops = {
	.attach = system_heap_attach,
	.detach = system_heap_detach,
	.map_dma_buf = system_heap_map_dma_buf,
	.unmap_dma_buf = system_heap_unmap_dma_buf,
	.begin_cpu_access = system_heap_dma_buf_begin_cpu_access,
	.end_cpu_access = system_heap_dma_buf_end_cpu_access,
	.mmap = system_heap_mmap,
	.vmap = system_heap_vmap,
	.vunmap = system_heap_vunmap,
	.release = system_heap_dma_buf_release,
};

static int system_heap_allocate(struct dma_heap *heap,
				unsigned long len,
				unsigned long fd_flags,
				unsigned long heap_flags)
{
	struct system_heap_buffer *buffer;
	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
	struct dma_buf *dmabuf;
	struct sg_table *table;
	struct scatterlist *sg;
	pgoff_t pagecount;
	pgoff_t pg;
	int i, ret = -ENOMEM;

	buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
	if (!buffer)
		return -ENOMEM;

	INIT_LIST_HEAD(&buffer->attachments);
	mutex_init(&buffer->lock);
	buffer->heap = heap;
	buffer->len = len;

	table = &buffer->sg_table;
	pagecount = len / PAGE_SIZE;
	if (sg_alloc_table(table, pagecount, GFP_KERNEL))
		goto free_buffer;

	sg = table->sgl;
	for (pg = 0; pg < pagecount; pg++) {
		struct page *page;
		/*
		 * Avoid trying to allocate memory if the process
		 * has been killed by SIGKILL
		 */
		if (fatal_signal_pending(current))
			goto free_pages;
		page = alloc_page(GFP_KERNEL | __GFP_ZERO);
		if (!page)
			goto free_pages;
		sg_set_page(sg, page, page_size(page), 0);
		sg = sg_next(sg);
	}

	/* create the dmabuf */
	exp_info.ops = &system_heap_buf_ops;
	exp_info.size = buffer->len;
	exp_info.flags = fd_flags;
	exp_info.priv = buffer;
	dmabuf = dma_buf_export(&exp_info);
	if (IS_ERR(dmabuf)) {
		ret = PTR_ERR(dmabuf);
		goto free_pages;
	}

	ret = dma_buf_fd(dmabuf, fd_flags);
	if (ret < 0) {
		dma_buf_put(dmabuf);
		/* just return, as put will call release and that will free */
		return ret;
	}

	return ret;

free_pages:
	for_each_sgtable_sg(table, sg, i)
		__free_page(sg_page(sg));
	sg_free_table(table);
free_buffer:
	kfree(buffer);

	return ret;
}

static const struct dma_heap_ops system_heap_ops = {
	.allocate = system_heap_allocate,
};

static int system_heap_create(void)
{
	struct dma_heap_export_info exp_info;

	exp_info.name = "system";
	exp_info.ops = &system_heap_ops;
	exp_info.priv = NULL;

	sys_heap = dma_heap_add(&exp_info);
	if (IS_ERR(sys_heap))
		return PTR_ERR(sys_heap);

	return 0;
}
module_init(system_heap_create);
MODULE_LICENSE("GPL v2");