user: add wrappers for userspace data transfer

This doesn't do anything right now, but will save some work in the
future when we have hardware memory protection.

include/ardix/userspace.h

@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+/* See the end of this file for copyright, licensing, and warranty information. */
+
+#pragma once
+
+#include <ardix/types.h>
+
+#include <toolchain.h>
+
+/**
+ * Copy data from user space to kernel space.
+ *
+ * @param dest: where to copy to
+ * @param src: where to copy from
+ * @param len: amount of bytes to copy
+ * @returns amount of bytes copied
+ */
+size_t copy_from_user(void *dest, __user const void *src, size_t len);
+
+/**
+ * Copy data from kernel space to user space.
+ *
+ * @param dest: where to copy to
+ * @param src: where to copy from
+ * @param len: amount of bytes to copy
+ * @returns amount of bytes copied
+ */
+size_t copy_to_user(__user void *dest, __user const void *src, size_t len);
+
+/*
+ * Copyright (c) 2020 Felix Kopp <sandtler@sandtler.club>
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are permitted
+ * provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this list of
+ *    conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
+ *    conditions and the following disclaimer in the documentation and/or other materials
+ *    provided with the distribution.
+ * 3. Neither the name of the copyright holder nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software without specific prior
+ *    written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
+ * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */

include/toolchain.h

@@ -46,8 +46,20 @@
 #define __section(name) __attribute__((section(#name)))
 #endif /* __section */
 
+#ifndef __rodata
 /** Place a variable in program memory rather than into RAM. */
 #define __rodata __section(.rodata#)
+#endif
+
+#ifndef __user
+/** Denote a pointer to user space (this will be used for static code checks later) */
+#define __user
+#endif
+
+#ifndef __shared
+/** Storage attribute indicating the symbol will be shared with userspace. */
+#define __shared __section(.text.shared)
+#endif
 
 /*
  * Copyright (c) 2020 Felix Kopp <sandtler@sandtler.club>

kernel/userspace.c

@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+/* See the end of this file for copyright, licensing, and warranty information. */
+
+#include <ardix/types.h>
+#include <ardix/userspace.h>
+
+#include <ardix/string.h>
+#include <toolchain.h>
+
+/*
+ * These don't do anything special because there is no MPU or other protection
+ * yet, but having them as a wrapper this early is probably a good idea because
+ * it make life easier when the MPU is active.
+ */
+
+size_t copy_from_user(void *dest, __user const void *src, size_t len)
+{
+	void *tmp = memcpy(dest, src, len);
+	return (size_t)tmp - (size_t)dest;
+}
+
+size_t copy_to_user(__user void *dest, const void *src, size_t len)
+{
+	void *tmp = memcpy(dest, src, len);
+	return (size_t)tmp - (size_t)dest;
+}
+
+/*
+ * Copyright (c) 2020 Felix Kopp <sandtler@sandtler.club>
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are permitted
+ * provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this list of
+ *    conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
+ *    conditions and the following disclaimer in the documentation and/or other materials
+ *    provided with the distribution.
+ * 3. Neither the name of the copyright holder nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software without specific prior
+ *    written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
+ * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */