dma-buf: heaps: Add system heap to dmabuf heaps

	  allows userspace to allocate dma-bufs that can be shared

	  between drivers.

source "drivers/dma-buf/heaps/Kconfig"

endmenu

config DMABUF_HEAPS_SYSTEM

	bool "DMA-BUF System Heap"

	depends on DMABUF_HEAPS

	help

	  Choose this option to enable the system dmabuf heap. The system heap

	  is backed by pages from the buddy allocator. If in doubt, say Y.

# SPDX-License-Identifier: GPL-2.0

obj-y					+= heap-helpers.o

obj-$(CONFIG_DMABUF_HEAPS_SYSTEM)	+= system_heap.o

// SPDX-License-Identifier: GPL-2.0

/*

 * DMABUF System heap exporter

 *

 * Copyright (C) 2011 Google, Inc.

 * Copyright (C) 2019 Linaro Ltd.

 */

#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/sched/signal.h>

#include <asm/page.h>

#include "heap-helpers.h"

struct dma_heap *sys_heap;

static void system_heap_free(struct heap_helper_buffer *buffer)

{

	pgoff_t pg;

	for (pg = 0; pg < buffer->pagecount; pg++)

		__free_page(buffer->pages[pg]);

	kfree(buffer->pages);

	kfree(buffer);

}

static int system_heap_allocate(struct dma_heap *heap,

				unsigned long len,

				unsigned long fd_flags,

				unsigned long heap_flags)

{

	struct heap_helper_buffer *helper_buffer;

	struct dma_buf *dmabuf;

	int ret = -ENOMEM;

	pgoff_t pg;

	helper_buffer = kzalloc(sizeof(*helper_buffer), GFP_KERNEL);

	if (!helper_buffer)

		return -ENOMEM;

	init_heap_helper_buffer(helper_buffer, system_heap_free);

	helper_buffer->flags = heap_flags;

	helper_buffer->heap = heap;

	helper_buffer->size = len;

	helper_buffer->pagecount = len / PAGE_SIZE;

	helper_buffer->pages = kmalloc_array(helper_buffer->pagecount,

					     sizeof(*helper_buffer->pages),

					     GFP_KERNEL);

	if (!helper_buffer->pages) {

		ret = -ENOMEM;

		goto err0;

	}

	for (pg = 0; pg < helper_buffer->pagecount; pg++) {

		/*

		 * Avoid trying to allocate memory if the process

		 * has been killed by by SIGKILL

		 */

		if (fatal_signal_pending(current))

			goto err1;

		helper_buffer->pages[pg] = alloc_page(GFP_KERNEL | __GFP_ZERO);

		if (!helper_buffer->pages[pg])

			goto err1;

	}

	/* create the dmabuf */

	dmabuf = heap_helper_export_dmabuf(helper_buffer, fd_flags);

	if (IS_ERR(dmabuf)) {

		ret = PTR_ERR(dmabuf);

		goto err1;

	}

	helper_buffer->dmabuf = dmabuf;

	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;

err1:

	while (pg > 0)

		__free_page(helper_buffer->pages[--pg]);

	kfree(helper_buffer->pages);

err0:

	kfree(helper_buffer);

	return -ENOMEM;

}

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;

	int ret = 0;

	exp_info.name = "system_heap";

	exp_info.ops = &system_heap_ops;

	exp_info.priv = NULL;

	sys_heap = dma_heap_add(&exp_info);

	if (IS_ERR(sys_heap))

		ret = PTR_ERR(sys_heap);

	return ret;

}

module_init(system_heap_create);

MODULE_LICENSE("GPL v2");