Re: [PATCH v4 1/2] create SMAF module

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On 10/05/2015 03:11 AM, Benjamin Gaignard wrote:
diff --git a/drivers/smaf/smaf-core.c b/drivers/smaf/smaf-core.c
new file mode 100644
index 0000000..37914e7
--- /dev/null
+++ b/drivers/smaf/smaf-core.c
@@ -0,0 +1,736 @@
+/*
+ * smaf.c
+ *
+ * Copyright (C) Linaro SA 2015
+ * Author: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxx> for Linaro.
+ * License terms:  GNU General Public License (GPL), version 2
+ */
+
+#include <linux/device.h>
+#include <linux/dma-buf.h>
+#include <linux/dma-mapping.h>
+#include <linux/fs.h>
+#include <linux/ioctl.h>
+#include <linux/list_sort.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/smaf.h>
+#include <linux/smaf-allocator.h>
+#include <linux/smaf-secure.h>
+#include <linux/uaccess.h>
+
+struct smaf_handle {
+	struct dma_buf *dmabuf;
+	struct smaf_allocator *allocator;
+	struct dma_buf *db_alloc;
+	size_t length;
+	unsigned int flags;
+	int fd;
+	bool is_secure;
+	void *secure_ctx;
+};
+
+/**
+ * struct smaf_device - smaf device node private data
+ * @misc_dev:	the misc device
+ * @head:	list of allocator
+ * @lock:	list and secure pointer mutex
+ * @secure:	pointer to secure functions helpers
+ */
+struct smaf_device {
+	struct miscdevice misc_dev;
+	struct list_head head;
+	/* list and secure pointer lock*/
+	struct mutex lock;
+	struct smaf_secure *secure;
+};
+
+static struct smaf_device smaf_dev;
+
+/**
+ * smaf_allow_cpu_access return true if CPU can access to memory
+ * if their is no secure module associated to SMAF assume that CPU can get
+ * access to the memory.
+ */
+static bool smaf_allow_cpu_access(struct smaf_handle *handle,
+				  unsigned long flags)
+{
+	if (!handle->is_secure)
+		return true;
+
+	if (!smaf_dev.secure)
+		return true;
+
+	if (!smaf_dev.secure->allow_cpu_access)
+		return true;
+
+	return smaf_dev.secure->allow_cpu_access(handle->secure_ctx, flags);
+}
+
+static int smaf_grant_access(struct smaf_handle *handle, struct device *dev,
+			     dma_addr_t addr, size_t size,
+			     enum dma_data_direction dir)
+{
+	if (!handle->is_secure)
+		return 0;
+
+	if (!smaf_dev.secure)
+		return -EINVAL;
+
+	if (!smaf_dev.secure->grant_access)
+		return -EINVAL;
+
+	return smaf_dev.secure->grant_access(handle->secure_ctx,
+					     dev, addr, size, dir);
+}
+
+static void smaf_revoke_access(struct smaf_handle *handle, struct device *dev,
+			       dma_addr_t addr, size_t size,
+			       enum dma_data_direction dir)
+{
+	if (!handle->is_secure)
+		return;
+
+	if (!smaf_dev.secure)
+		return;
+
+	if (!smaf_dev.secure->revoke_access)
+		return;
+
+	smaf_dev.secure->revoke_access(handle->secure_ctx,
+				       dev, addr, size, dir);
+}
+
+static int smaf_secure_handle(struct smaf_handle *handle)
+{
+	if (handle->is_secure)
+		return 0;
+
+	if (!smaf_dev.secure)
+		return -EINVAL;
+
+	if (!smaf_dev.secure->create_context)
+		return -EINVAL;
+
+	handle->secure_ctx = smaf_dev.secure->create_context();
+
+	if (!handle->secure_ctx)
+		return -EINVAL;
+
+	handle->is_secure = true;
+	return 0;
+}
+
+static int smaf_unsecure_handle(struct smaf_handle *handle)
+{
+	if (!handle->is_secure)
+		return 0;
+
+	if (!smaf_dev.secure)
+		return -EINVAL;
+
+	if (!smaf_dev.secure->destroy_context)
+		return -EINVAL;
+
+	if (smaf_dev.secure->destroy_context(handle->secure_ctx))
+		return -EINVAL;
+
+	handle->secure_ctx = NULL;
+	handle->is_secure = false;
+	return 0;
+}

All these functions need to be protected by a lock, otherwise the
secure state could change. For that matter, I think the smaf_handle
needs a lock to protect its state as well for places like map_dma_buf


<snip>
+static long smaf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	switch (cmd) {
+	case SMAF_IOC_CREATE:
+	{
+		struct smaf_create_data data;
+		struct smaf_handle *handle;
+
+		if (copy_from_user(&data, (void __user *)arg, _IOC_SIZE(cmd)))
+			return -EFAULT;
+
+		handle = smaf_create_handle(data.length, data.flags);
+		if (!handle)
+			return -EINVAL;
+
+		if (data.name[0]) {
+			/* user force allocator selection */
+			if (smaf_select_allocator_by_name(handle->dmabuf,
+							  data.name)) {
+				dma_buf_put(handle->dmabuf);
+				return -EINVAL;
+			}
+		}
+
+		handle->fd = dma_buf_fd(handle->dmabuf, data.flags);
+		if (handle->fd < 0) {
+			dma_buf_put(handle->dmabuf);
+			return -EINVAL;
+		}
+
+		data.fd = handle->fd;
+		if (copy_to_user((void __user *)arg, &data, _IOC_SIZE(cmd))) {
+			dma_buf_put(handle->dmabuf);
+			return -EFAULT;
+		}
+		break;
+	}
+	case SMAF_IOC_GET_SECURE_FLAG:
+	{
+		struct smaf_secure_flag data;
+		struct dma_buf *dmabuf;
+
+		if (copy_from_user(&data, (void __user *)arg, _IOC_SIZE(cmd)))
+			return -EFAULT;
+
+		dmabuf = dma_buf_get(data.fd);
+		if (!dmabuf)
+			return -EINVAL;
+
+		data.secure = smaf_is_secure(dmabuf);
+		dma_buf_put(dmabuf);
+
+		if (copy_to_user((void __user *)arg, &data, _IOC_SIZE(cmd)))
+			return -EFAULT;
+		break;
+	}
+	case SMAF_IOC_SET_SECURE_FLAG:
+	{
+		struct smaf_secure_flag data;
+		struct dma_buf *dmabuf;
+		int ret;
+
+		if (!smaf_dev.secure)
+			return -EINVAL;
+
+		if (copy_from_user(&data, (void __user *)arg, _IOC_SIZE(cmd)))
+			return -EFAULT;
+
+		dmabuf = dma_buf_get(data.fd);
+		if (!dmabuf)
+			return -EINVAL;
+
+		ret = smaf_set_secure(dmabuf, data.secure);
+
+		dma_buf_put(dmabuf);
+
+		if (ret)
+			return -EINVAL;
+
+		break;
+	}
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}

How would you see this tying into something like Ion? It seems like
Ion and SMAF have non-zero over lapping functionality for some things
or that SMAF could be implemented as a heap type. I think my biggest
concern here is that it seems like either Ion or SMAF is going to feel
redundant as an interface.

Thanks,
Laura
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