[PATCH 1/3] dma-buf: heaps: add Linaro secure dmabuf heap support
Brian Starkey
brian.starkey at arm.com
Fri Aug 5 15:41:39 UTC 2022
Hi Olivier,
Thanks, I think this is looking much better.
I'd like to know how others feel about landing this heap; there's been
push-back in the past about heaps in device-tree and discussions
around how "custom" heaps should be treated (though IMO this is quite
a generic one).
On Fri, Aug 05, 2022 at 03:53:28PM +0200, Olivier Masse wrote:
> add Linaro secure heap bindings: linaro,secure-heap
> use genalloc to allocate/free buffer from buffer pool.
> buffer pool info is from dts.
> use sg_table instore the allocated memory info, the length of sg_table is 1.
> implement secure_heap_buf_ops to implement buffer share in difference device:
> 1. Userspace passes this fd to all drivers it wants this buffer
> to share with: First the filedescriptor is converted to a &dma_buf using
> dma_buf_get(). Then the buffer is attached to the device using dma_buf_attach().
> 2. Once the buffer is attached to all devices userspace can initiate DMA
> access to the shared buffer. In the kernel this is done by calling dma_buf_map_attachment()
> 3. get sg_table with dma_buf_map_attachment in difference device.
>
I think this commit message could use a little rework. A few thoughts:
* The bindings are in a separate commit, so seems strange to mention
here.
* "buffer pool info is from dts" --> I think you should mention that
this uses a reserved-memory region.
* sg_table nents and genalloc seem like low-level implementation
details, so probably not needed in the commit message
* The usage steps 1, 2, 3 aren't specific to this heap - that's how
all dma-buf sharing works.
> Signed-off-by: Olivier Masse <olivier.masse at nxp.com>
> ---
> drivers/dma-buf/heaps/Kconfig | 9 +
> drivers/dma-buf/heaps/Makefile | 1 +
> drivers/dma-buf/heaps/secure_heap.c | 357 ++++++++++++++++++++++++++++
> 3 files changed, 367 insertions(+)
> create mode 100644 drivers/dma-buf/heaps/secure_heap.c
>
> diff --git a/drivers/dma-buf/heaps/Kconfig b/drivers/dma-buf/heaps/Kconfig
> index 3782eeeb91c0..c9070c728b9a 100644
> --- a/drivers/dma-buf/heaps/Kconfig
> +++ b/drivers/dma-buf/heaps/Kconfig
> @@ -20,3 +20,12 @@ config DMABUF_HEAPS_DSP
> Choose this option to enable the dsp dmabuf heap. The dsp heap
> is allocated by gen allocater. it's allocated according the dts.
> If in doubt, say Y.
> +
> +config DMABUF_HEAPS_SECURE
> + tristate "DMA-BUF Secure Heap"
> + depends on DMABUF_HEAPS
> + help
> + Choose this option to enable the secure dmabuf heap. The secure heap
> + pools are defined according to the DT. Heaps are allocated
> + in the pools using gen allocater.
> + If in doubt, say Y.
> diff --git a/drivers/dma-buf/heaps/Makefile b/drivers/dma-buf/heaps/Makefile
> index 29733f84c354..863ef10056a3 100644
> --- a/drivers/dma-buf/heaps/Makefile
> +++ b/drivers/dma-buf/heaps/Makefile
> @@ -2,3 +2,4 @@
> obj-$(CONFIG_DMABUF_HEAPS_SYSTEM) += system_heap.o
> obj-$(CONFIG_DMABUF_HEAPS_CMA) += cma_heap.o
> obj-$(CONFIG_DMABUF_HEAPS_DSP) += dsp_heap.o
> +obj-$(CONFIG_DMABUF_HEAPS_SECURE) += secure_heap.o
> diff --git a/drivers/dma-buf/heaps/secure_heap.c b/drivers/dma-buf/heaps/secure_heap.c
> new file mode 100644
> index 000000000000..25b3629613f3
> --- /dev/null
> +++ b/drivers/dma-buf/heaps/secure_heap.c
> @@ -0,0 +1,357 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * DMABUF secure heap exporter
> + *
> + * Copyright 2021 NXP.
It's 2022 :-)
> + */
> +
> +#include <linux/dma-buf.h>
> +#include <linux/dma-heap.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/err.h>
> +#include <linux/genalloc.h>
> +#include <linux/highmem.h>
> +#include <linux/mm.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_fdt.h>
> +#include <linux/of_reserved_mem.h>
> +#include <linux/scatterlist.h>
> +#include <linux/slab.h>
> +#include <linux/vmalloc.h>
> +
> +#define MAX_SECURE_HEAP 2
> +#define MAX_HEAP_NAME_LEN 32
> +
> +struct secure_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 secure_heap_attachment {
> + struct device *dev;
> + struct sg_table *table;
> + struct list_head list;
> +};
> +
> +struct secure_heap_info {
> + struct gen_pool *pool;
> +};
> +
> +struct rmem_secure {
> + phys_addr_t base;
> + phys_addr_t size;
> +
> + char name[MAX_HEAP_NAME_LEN];
> +};
> +
> +static struct rmem_secure secure_data[MAX_SECURE_HEAP] = {0};
> +static unsigned int secure_data_count;
> +
> +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->dma_address = sg->dma_address;
> +#ifdef CONFIG_NEED_SG_DMA_LENGTH
> + new_sg->dma_length = sg->dma_length;
> +#endif
> + new_sg = sg_next(new_sg);
> + }
> +
> + return new_table;
> +}
> +
> +static int secure_heap_attach(struct dma_buf *dmabuf,
> + struct dma_buf_attachment *attachment)
> +{
> + struct secure_heap_buffer *buffer = dmabuf->priv;
> + struct secure_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;
nit: You could return PTR_ERR(table), in case dup_sg_table starts
returning other errors.
> + }
> +
> + a->table = table;
> + a->dev = attachment->dev;
> + INIT_LIST_HEAD(&a->list);
> + attachment->priv = a;
> +
> + mutex_lock(&buffer->lock);
> + list_add(&a->list, &buffer->attachments);
> + mutex_unlock(&buffer->lock);
> +
> + return 0;
> +}
> +
> +static void secure_heap_detach(struct dma_buf *dmabuf,
> + struct dma_buf_attachment *attachment)
> +{
> + struct secure_heap_buffer *buffer = dmabuf->priv;
> + struct secure_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 *secure_heap_map_dma_buf(struct dma_buf_attachment *attachment,
> + enum dma_data_direction direction)
> +{
> + struct secure_heap_attachment *a = attachment->priv;
> +
> + return a->table;
I think you still need to implement mapping and unmapping using the
DMA APIs. For example devices might be behind IOMMUs and the buffer
will need mapping into the IOMMU.
> +}
> +
> +static void secure_heap_unmap_dma_buf(struct dma_buf_attachment *attachment,
> + struct sg_table *table,
> + enum dma_data_direction direction)
> +{
> +}
> +
> +static void secure_heap_dma_buf_release(struct dma_buf *dmabuf)
> +{
> + struct secure_heap_buffer *buffer = dmabuf->priv;
> + struct secure_heap_info *info;
> + struct sg_table *table;
> + struct scatterlist *sg;
> + int i;
> +
> + info = dma_heap_get_drvdata(buffer->heap);
> +
> + table = &buffer->sg_table;
> + for_each_sg(table->sgl, sg, table->nents, i)
> + gen_pool_free(info->pool, sg_dma_address(sg), sg_dma_len(sg));
> +
> + sg_free_table(table);
> + kfree(buffer);
> +}
> +
> +static const struct dma_buf_ops secure_heap_buf_ops = {
> + .attach = secure_heap_attach,
> + .detach = secure_heap_detach,
> + .map_dma_buf = secure_heap_map_dma_buf,
> + .unmap_dma_buf = secure_heap_unmap_dma_buf,
> + .release = secure_heap_dma_buf_release,
> +};
> +
> +static struct dma_buf *secure_heap_allocate(struct dma_heap *heap,
> + unsigned long len,
> + unsigned long fd_flags,
> + unsigned long heap_flags)
> +{
> + struct secure_heap_buffer *buffer;
> + struct secure_heap_info *info = dma_heap_get_drvdata(heap);
> + DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
> + unsigned long size = roundup(len, PAGE_SIZE);
> + struct dma_buf *dmabuf;
> + struct sg_table *table;
> + int ret = -ENOMEM;
> + unsigned long phy_addr;
> +
> + buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
> + if (!buffer)
> + return ERR_PTR(-ENOMEM);
> +
> + INIT_LIST_HEAD(&buffer->attachments);
> + mutex_init(&buffer->lock);
> + buffer->heap = heap;
> + buffer->len = size;
> +
> + phy_addr = gen_pool_alloc(info->pool, size);
> + if (!phy_addr)
> + goto free_buffer;
> +
> + table = &buffer->sg_table;
> + if (sg_alloc_table(table, 1, GFP_KERNEL))
> + goto free_pool;
> +
> + sg_set_page(table->sgl, phys_to_page(phy_addr), size, 0);
> + sg_dma_address(table->sgl) = phy_addr;
> + sg_dma_len(table->sgl) = size;
> +
> + /* create the dmabuf */
> + exp_info.exp_name = dma_heap_get_name(heap);
> + exp_info.ops = &secure_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;
> + }
> +
> + return dmabuf;
> +
> +free_pages:
Should maybe be called free_table:
> + sg_free_table(table);
> +
> +free_pool:
> + gen_pool_free(info->pool, phy_addr, size);
> +
> +free_buffer:
> + mutex_destroy(&buffer->lock);
> + kfree(buffer);
> +
> + return ERR_PTR(ret);
> +}
> +
> +static const struct dma_heap_ops secure_heap_ops = {
> + .allocate = secure_heap_allocate,
> +};
> +
> +static int secure_heap_add(struct rmem_secure *rmem)
> +{
> + struct dma_heap *secure_heap;
> + struct dma_heap_export_info exp_info;
> + struct secure_heap_info *info = NULL;
> + struct gen_pool *pool = NULL;
> + int ret = -EINVAL;
> +
> + if (rmem->base == 0 || rmem->size == 0) {
> + pr_err("secure_data base or size is not correct\n");
> + goto error;
> + }
> +
> + info = kzalloc(sizeof(*info), GFP_KERNEL);
> + if (!info) {
> + pr_err("dmabuf info allocation failed\n");
> + ret = -ENOMEM;
> + goto error;
> + }
> +
> + pool = gen_pool_create(PAGE_SHIFT, -1);
> + if (!pool) {
> + pr_err("can't create gen pool\n");
> + ret = -ENOMEM;
> + goto error;
> + }
> +
> + if (gen_pool_add(pool, rmem->base, rmem->size, -1) < 0) {
> + pr_err("failed to add memory into pool\n");
> + ret = -ENOMEM;
> + goto error;
> + }
> +
> + info->pool = pool;
> +
> + exp_info.name = rmem->name;
> + exp_info.ops = &secure_heap_ops;
> + exp_info.priv = info;
> +
> + secure_heap = dma_heap_add(&exp_info);
> + if (IS_ERR(secure_heap)) {
> + pr_err("dmabuf secure heap allocation failed\n");
> + ret = PTR_ERR(secure_heap);
> + goto error;
> + }
> +
> + return 0;
> +
> +error:
> + kfree(info);
> + if (pool)
> + gen_pool_destroy(pool);
nit: I think your order should be reversed here, to match the opposite
order of allocation.
> +
> + return ret;
> +}
> +
> +static int secure_heap_create(void)
> +{
> + unsigned int i;
> + int ret;
> +
> + for (i = 0; i < secure_data_count; i++) {
> + ret = secure_heap_add(&secure_data[i]);
> + if (ret)
> + return ret;
> + }
> + return 0;
> +}
> +
> +static int rmem_secure_heap_device_init(struct reserved_mem *rmem,
> + struct device *dev)
> +{
> + dev_set_drvdata(dev, rmem);
> + return 0;
> +}
> +
> +static void rmem_secure_heap_device_release(struct reserved_mem *rmem,
> + struct device *dev)
> +{
> + dev_set_drvdata(dev, NULL);
> +}
> +
> +static const struct reserved_mem_ops rmem_dma_ops = {
> + .device_init = rmem_secure_heap_device_init,
> + .device_release = rmem_secure_heap_device_release,
> +};
What are these reserved_mem_ops for? Setting the drvdata for a random
device seems like it could cause lots of problems.
Is there a requirement to support assigning this SDP reserved-memory
region to a specific device? If not, I think you can just drop this.
Otherwise, I think you need some other mechanism to do the
association.
> +
> +static int __init rmem_secure_heap_setup(struct reserved_mem *rmem)
> +{
> + if (secure_data_count < MAX_SECURE_HEAP) {
> + int name_len = 0;
> + const char *s = rmem->name;
> +
> + secure_data[secure_data_count].base = rmem->base;
> + secure_data[secure_data_count].size = rmem->size;
> +
> + while (name_len < MAX_HEAP_NAME_LEN) {
> + if ((*s == '@') || (*s == '\0'))
> + break;
> + name_len++;
> + s++;
> + }
> + if (name_len == MAX_HEAP_NAME_LEN)
> + name_len--;
> +
> + strncpy(secure_data[secure_data_count].name, rmem->name, name_len);
I think it would be good to explicitly do:
secure_data[secure_data_count].name[name_len] = '\0'
I know it's zero-initialised, but that's done on a line far away, so
may be best to be defensive.
> +
> + rmem->ops = &rmem_dma_ops;
> + pr_info("Reserved memory: DMA buf secure pool %s at %pa, size %ld MiB\n",
> + secure_data[secure_data_count].name,
> + &rmem->base, (unsigned long)rmem->size / SZ_1M);
nit: What if rmem->size < SZ_1M, or not 1M-aligned
> +
> + secure_data_count++;
> + return 0;
> + }
> + WARN_ONCE(1, "Cannot handle more than %u secure heaps\n", MAX_SECURE_HEAP);
> + return -EINVAL;
> +}
> +
> +RESERVEDMEM_OF_DECLARE(secure_heap, "linaro,secure-heap", rmem_secure_heap_setup);
Is there anything linaro-specific about this? Could it be
linux,secure-heap?
Thanks,
-Brian
> +
> +module_init(secure_heap_create);
> +MODULE_LICENSE("GPL v2");
> --
> 2.25.0
>
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