Re: [Linaro-mm-sig] [RFC][PATCH] dma-buf: Introduce dma-buf test module

On Tue, Mar 14, 2017 at 01:04:19PM -0700, Laura Abbott wrote:

dma-buf is designed to share buffers. Sharing means that there needs to be another subsystem to accept those buffers. Introduce a simple test module to act as a dummy system to accept dma_bufs from elsewhere. The goal is to provide a very simple interface to validate exported buffers do something reasonable. This is based on ion_test.c that existed for the Ion framework.

Signed-off-by: Laura Abbott labbott@redhat.com

This is basically a drop in of what was available as drivers/staging/android/ion/ion_test.c. Given it has no Ion specific parts it might be useful as a more general test module. RFC mostly to see if this is generally useful or not.

We already have a test dma-buf driver, which also handles reservation objects and can create fences to provoke signalling races an all kinds of other fun. It's drivers/gpu/drm/vgem.

If there's anything missing in there, patches very much welcome. -Daniel

---

drivers/dma-buf/Kconfig | 9 ++ drivers/dma-buf/Makefile | 1 + drivers/dma-buf/dma-buf-test.c | 309 ++++++++++++++++++++++++++++++++++++++ include/uapi/linux/dma_buf_test.h | 67 +++++++++ 4 files changed, 386 insertions(+) create mode 100644 drivers/dma-buf/dma-buf-test.c create mode 100644 include/uapi/linux/dma_buf_test.h

diff --git a/drivers/dma-buf/Kconfig b/drivers/dma-buf/Kconfig index ed3b785..8b3fdb1 100644 --- a/drivers/dma-buf/Kconfig +++ b/drivers/dma-buf/Kconfig @@ -30,4 +30,13 @@ config SW_SYNC WARNING: improper use of this can result in deadlocking kernel drivers from userspace. Intended for test and debug only. +config DMA_BUF_TEST

• bool "Test module for dma-buf"
• default n
• ---help---

•  A test module to validate dma_buf APIs. This should not be
  

•  enabled for general use.
  

•  Say N here unless you know you want this.
  

endmenu diff --git a/drivers/dma-buf/Makefile b/drivers/dma-buf/Makefile index c33bf88..5029608 100644 --- a/drivers/dma-buf/Makefile +++ b/drivers/dma-buf/Makefile @@ -1,3 +1,4 @@ obj-y := dma-buf.o dma-fence.o dma-fence-array.o reservation.o seqno-fence.o obj-$(CONFIG_SYNC_FILE) += sync_file.o obj-$(CONFIG_SW_SYNC) += sw_sync.o sync_debug.o +obj-$(CONFIG_DMA_BUF_TEST) += dma-buf-test.o diff --git a/drivers/dma-buf/dma-buf-test.c b/drivers/dma-buf/dma-buf-test.c new file mode 100644 index 0000000..3af131c --- /dev/null +++ b/drivers/dma-buf/dma-buf-test.c @@ -0,0 +1,309 @@ +/*

• • Copyright (C) 2013 Google, Inc.
• • This software is licensed under the terms of the GNU General Public
• • License versdma_buf 2, as published by the Free Software Foundatdma_buf, and
• • may be copied, distributed, and modified under those terms.
• • This program is distributed in the hope that it will be useful,
• • but WITHOUT ANY WARRANTY; without even the implied warranty of
• • MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
• • GNU General Public License for more details.
• */

+#define pr_fmt(fmt) "dma-buf-test: " fmt

+#include <linux/dma-buf.h> +#include <linux/dma-direction.h> +#include <linux/fs.h> +#include <linux/miscdevice.h> +#include <linux/mm.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/sched.h> +#include <linux/slab.h> +#include <linux/uaccess.h> +#include <linux/vmalloc.h>

+#include <uapi/linux/dma_buf_test.h>

+struct dma_buf_test_device {

• struct miscdevice misc;

+};

+struct dma_buf_test_data {

• struct dma_buf *dma_buf;
• struct device *dev;

+};

+static int dma_buf_handle_test_dma(struct device *dev, struct dma_buf *dma_buf,

• 	       void __user *ptr, size_t offset, size_t size,
  

• 	       bool write)
  

+{

• int ret = 0;
• struct dma_buf_attachment *attach;
• struct sg_table *table;
• pgprot_t pgprot = pgprot_writecombine(PAGE_KERNEL);
• enum dma_data_direction dir = write ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
• struct sg_page_iter sg_iter;
• unsigned long offset_page;
• attach = dma_buf_attach(dma_buf, dev);
• if (IS_ERR(attach))

• return PTR_ERR(attach);
  

• table = dma_buf_map_attachment(attach, dir);
• if (IS_ERR(table))

• return PTR_ERR(table);
  

• offset_page = offset >> PAGE_SHIFT;
• offset %= PAGE_SIZE;
• for_each_sg_page(table->sgl, &sg_iter, table->nents, offset_page) {

• struct page *page = sg_page_iter_page(&sg_iter);
  

• void *vaddr = vmap(&page, 1, VM_MAP, pgprot);
  

• size_t to_copy = PAGE_SIZE - offset;
  

• to_copy = min(to_copy, size);
  

• if (!vaddr) {
  

• 	ret = -ENOMEM;
  

• 	goto err;
  

• }
  

• if (write)
  

• 	ret = copy_from_user(vaddr + offset, ptr, to_copy);
  

• else
  

• 	ret = copy_to_user(ptr, vaddr + offset, to_copy);
  

• vunmap(vaddr);
  

• if (ret) {
  

• 	ret = -EFAULT;
  

• 	goto err;
  

• }
  

• size -= to_copy;
  

• if (!size)
  

• 	break;
  

• ptr += to_copy;
  

• offset = 0;
  

• }

+err:

• dma_buf_unmap_attachment(attach, table, dir);
• dma_buf_detach(dma_buf, attach);
• return ret;

+}

+static int dma_buf_handle_test_kernel(struct dma_buf *dma_buf, void __user *ptr,

• 		  size_t offset, size_t size, bool write)
  

+{

• int ret;
• unsigned long page_offset = offset >> PAGE_SHIFT;
• size_t copy_offset = offset % PAGE_SIZE;
• size_t copy_size = size;
• enum dma_data_direction dir = write ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
• if (offset > dma_buf->size || size > dma_buf->size - offset)

• return -EINVAL;
  

• ret = dma_buf_begin_cpu_access(dma_buf, dir);
• if (ret)

• return ret;
  

• while (copy_size > 0) {

• size_t to_copy;
  

• void *vaddr = dma_buf_kmap(dma_buf, page_offset);
  

• if (!vaddr)
  

• 	goto err;
  

• to_copy = min_t(size_t, PAGE_SIZE - copy_offset, copy_size);
  

• if (write)
  

• 	ret = copy_from_user(vaddr + copy_offset, ptr, to_copy);
  

• else
  

• 	ret = copy_to_user(ptr, vaddr + copy_offset, to_copy);
  

• dma_buf_kunmap(dma_buf, page_offset, vaddr);
  

• if (ret) {
  

• 	ret = -EFAULT;
  

• 	goto err;
  

• }
  

• copy_size -= to_copy;
  

• ptr += to_copy;
  

• page_offset++;
  

• copy_offset = 0;
  

• }

+err:

• dma_buf_end_cpu_access(dma_buf, dir);
• return ret;

+}

+static long dma_buf_test_ioctl(struct file *filp, unsigned int cmd,

• 	   unsigned long arg)
  

+{

• struct dma_buf_test_data *test_data = filp->private_data;
• int ret = 0;
• union {

• struct dma_buf_test_rw_data test_rw;
  

• } data;
• if (_IOC_SIZE(cmd) > sizeof(data))

• return -EINVAL;
  

• if (_IOC_DIR(cmd) & _IOC_WRITE)

• if (copy_from_user(&data, (void __user *)arg, _IOC_SIZE(cmd)))
  

• 	return -EFAULT;
  

• switch (cmd) {
• case DMA_BUF_IOC_TEST_SET_FD:
• {

• struct dma_buf *dma_buf = NULL;
  

• int fd = arg;
  

• if (fd >= 0) {
  

• 	dma_buf = dma_buf_get((int)arg);
  

• 	if (IS_ERR(dma_buf))
  

• 		return PTR_ERR(dma_buf);
  

• }
  

• if (test_data->dma_buf)
  

• 	dma_buf_put(test_data->dma_buf);
  

• test_data->dma_buf = dma_buf;
  

• break;
  

• }
• case DMA_BUF_IOC_TEST_DMA_MAPPING:
• {

• ret = dma_buf_handle_test_dma(test_data->dev,
  

• 			  test_data->dma_buf,
  

• 			  u64_to_user_ptr(data.test_rw.ptr),
  

• 			  data.test_rw.offset,
  

• 			  data.test_rw.size,
  

• 			  data.test_rw.write);
  

• break;
  

• }
• case DMA_BUF_IOC_TEST_KERNEL_MAPPING:
• {

• ret = dma_buf_handle_test_kernel(test_data->dma_buf,
  

• 			     u64_to_user_ptr(data.test_rw.ptr),
  

• 			     data.test_rw.offset,
  

• 			     data.test_rw.size,
  

• 			     data.test_rw.write);
  

• break;
  

• }
• default:

• return -ENOTTY;
  

• }
• if (_IOC_DIR(cmd) & _IOC_READ) {

• if (copy_to_user((void __user *)arg, &data, sizeof(data)))
  

• 	return -EFAULT;
  

• }
• return ret;

+}

+static int dma_buf_test_open(struct inode *inode, struct file *file) +{

• struct dma_buf_test_data *data;
• struct miscdevice *miscdev = file->private_data;
• data = kzalloc(sizeof(*data), GFP_KERNEL);
• if (!data)

• return -ENOMEM;
  

• data->dev = miscdev->parent;
• file->private_data = data;
• return 0;

+}

+static int dma_buf_test_release(struct inode *inode, struct file *file) +{

• struct dma_buf_test_data *data = file->private_data;
• kfree(data);
• return 0;

+}

+static const struct file_operations dma_buf_test_fops = {

• .owner = THIS_MODULE,
• .unlocked_ioctl = dma_buf_test_ioctl,
• .compat_ioctl = dma_buf_test_ioctl,
• .open = dma_buf_test_open,
• .release = dma_buf_test_release,

+};

+static int __init dma_buf_test_probe(struct platform_device *pdev) +{

• int ret;
• struct dma_buf_test_device *testdev;
• testdev = devm_kzalloc(&pdev->dev, sizeof(struct dma_buf_test_device),

• 	       GFP_KERNEL);
  

• if (!testdev)

• return -ENOMEM;
  

• testdev->misc.minor = MISC_DYNAMIC_MINOR;
• testdev->misc.name = "dma_buf-test";
• testdev->misc.fops = &dma_buf_test_fops;
• testdev->misc.parent = &pdev->dev;
• /*

• * We need to force 'something' for a DMA mask. This isn't an actual
  

• * device and won't be doing actual DMA so pick 'something' that
  

• * probably won't blow up. Probably.
  

• */
  

• dma_coerce_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
• ret = misc_register(&testdev->misc);
• if (ret) {

• pr_err("failed to register misc device.\n");
  

• return ret;
  

• }
• platform_set_drvdata(pdev, testdev);
• return 0;

+}

+static int dma_buf_test_remove(struct platform_device *pdev) +{

• struct dma_buf_test_device *testdev;
• testdev = platform_get_drvdata(pdev);
• if (!testdev)

• return -ENODATA;
  

• misc_deregister(&testdev->misc);
• return 0;

+}

+static struct platform_device *dma_buf_test_pdev; +static struct platform_driver dma_buf_test_platform_driver = {

• .remove = dma_buf_test_remove,
• .driver = {

• .name = "dma_buf-test",
  

• },

+};

+static int __init dma_buf_test_init(void) +{

• dma_buf_test_pdev = platform_device_register_simple("dma-buf-test",

• 					-1, NULL, 0);
  

• if (IS_ERR(dma_buf_test_pdev))

• return PTR_ERR(dma_buf_test_pdev);
  

• return platform_driver_probe(&dma_buf_test_platform_driver,

• 		     dma_buf_test_probe);
  

+}

+static void __exit dma_buf_test_exit(void) +{

• platform_driver_unregister(&dma_buf_test_platform_driver);
• platform_device_unregister(dma_buf_test_pdev);

+}

+module_init(dma_buf_test_init); +module_exit(dma_buf_test_exit); +MODULE_LICENSE("GPL v2"); diff --git a/include/uapi/linux/dma_buf_test.h b/include/uapi/linux/dma_buf_test.h new file mode 100644 index 0000000..af2d521 --- /dev/null +++ b/include/uapi/linux/dma_buf_test.h @@ -0,0 +1,67 @@ +/*

• • Copyright (C) 2011 Google, Inc.
• • This software is licensed under the terms of the GNU General Public
• • License versdma_buf 2, as published by the Free Software Foundatdma_buf, and
• • may be copied, distributed, and modified under those terms.
• • This program is distributed in the hope that it will be useful,
• • but WITHOUT ANY WARRANTY; without even the implied warranty of
• • MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
• • GNU General Public License for more details.
• */

+#ifndef _UAPI_LINUX_DMA_BUF_TEST_H +#define _UAPI_LINUX_DMA_BUF_TEST_H

+#include <linux/ioctl.h> +#include <linux/types.h>

+/**

• • struct dma_buf_test_rw_data - metadata passed to the kernel to read handle
• • @ptr: a pointer to an area at least as large as size
• • @offset: offset into the dma_buf buffer to start reading
• • @size: size to read or write
• • @write: 1 to write, 0 to read
• */

+struct dma_buf_test_rw_data {

• __u64 ptr;
• __u64 offset;
• __u64 size;
• int write;
• int __padding;

+};

+#define DMA_BUF_IOC_MAGIC 'I'

+/**

• • DOC: DMA_BUF_IOC_TEST_SET_DMA_BUF - attach a dma buf to the test driver
• • Attaches a dma buf fd to the test driver. Passing a second fd or -1 will
• • release the first fd.
• */

+#define DMA_BUF_IOC_TEST_SET_FD \

• 	_IO(DMA_BUF_IOC_MAGIC, 0xf0)
  

+/**

• • DOC: DMA_BUF_IOC_TEST_DMA_MAPPING - read or write memory from a handle as DMA
• • Reads or writes the memory from a handle using an uncached mapping. Can be
• • used by unit tests to emulate a DMA engine as close as possible. Only
• • expected to be used for debugging and testing, may not always be available.
• */

+#define DMA_BUF_IOC_TEST_DMA_MAPPING \

• 	_IOW(DMA_BUF_IOC_MAGIC, 0xf1, struct dma_buf_test_rw_data)
  

+/**

• • DOC: DMA_BUF_IOC_TEST_KERNEL_MAPPING - read or write memory from a handle
• • Reads or writes the memory from a handle using a kernel mapping. Can be
• • used by unit tests to test heap map_kernel functdma_bufs. Only expected to be
• • used for debugging and testing, may not always be available.
• */

+#define DMA_BUF_IOC_TEST_KERNEL_MAPPING \

• 	_IOW(DMA_BUF_IOC_MAGIC, 0xf2, struct dma_buf_test_rw_data)
  

+#endif /* _UAPI_LINUX_DMA_BUF_TEST_H */

2.7.4

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