shm_pool.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2021-2023, Arm Limited
 */

#include <linux/arm_ffa.h>
#include <linux/device.h>
#include <linux/dma-buf.h>
#include <linux/genalloc.h>
#include <linux/slab.h>
#include <linux/tee_drv.h>

#include "tstee_private.h"

/*
 * This file implements a dynamic shared memory pool. It's used by the TEE
 * subsystem to allocate kernel memory to be shared with the SWd as part of the
 * TEE_IOC_SHM_ALLOC call.
 */

static int pool_op_alloc(struct tee_shm_pool *pool __always_unused, struct tee_shm *shm,
			 size_t size, size_t align __always_unused)
{
	unsigned int order, nr_pages, i;
	struct page *page, **pages;
	int rc;

	if (size == 0)
		return -EINVAL;

	order = get_order(size);
	nr_pages = 1 << order;

	page = alloc_pages(GFP_KERNEL | __GFP_ZERO, order);
	if (!page)
		return -ENOMEM;

	shm->kaddr = page_address(page);
	shm->paddr = page_to_phys(page);
	shm->size = PAGE_SIZE << order;

	pages = kcalloc(nr_pages, sizeof(*pages), GFP_KERNEL);
	if (!pages) {
		rc = -ENOMEM;
		goto err;
	}

	for (i = 0; i < nr_pages; i++)
		pages[i] = page + i;

	rc = tstee_shm_register(shm->ctx, shm, pages, nr_pages, (unsigned long)shm->kaddr);
	kfree(pages);
	if (rc)
		goto err;

	return 0;

err:
	__free_pages(page, order);
	return rc;
}

static void pool_op_free(struct tee_shm_pool *pool __always_unused, struct tee_shm *shm)
{
	int rc;

	rc = tstee_shm_unregister(shm->ctx, shm);
	if (rc)
		pr_err("shm id 0x%llx unregister rc %d\n", shm->sec_world_id, rc);

	free_pages((unsigned long)shm->kaddr, get_order(shm->size));
	shm->kaddr = NULL;
}

static void pool_op_destroy_pool(struct tee_shm_pool *pool)
{
	kfree(pool);
}

static const struct tee_shm_pool_ops pool_ops = {
	.alloc = pool_op_alloc,
	.free = pool_op_free,
	.destroy_pool = pool_op_destroy_pool,
};

struct tee_shm_pool *tstee_create_shm_pool(void)
{
	struct tee_shm_pool *pool;

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

	pool->ops = &pool_ops;

	return pool;
}