Kernel: Introduce the MemoryDevice

This is a character device that is being used by the dmidecode utility.
We only allow to map the BIOS ROM area to userspace with this device.

1 files changed, 78 insertions, 0 deletions

diff --git a/Kernel/Devices/MemoryDevice.cpp b/Kernel/Devices/MemoryDevice.cpp
new file mode 100644
index 0000000000..acbe53ae90
--- /dev/null
+++ b/Kernel/Devices/MemoryDevice.cpp
@@ -0,0 +1,78 @@
+/*
+ * Copyright (c) 2021, Liav A. <liavalb@hotmail.co.il>
+ * All rights reserved.
+ *
+ * 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.
+ *
+ * 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 "MemoryDevice.h"
+#include <AK/Memory.h>
+#include <AK/StdLibExtras.h>
+#include <Kernel/Arch/PC/BIOS.h>
+#include <Kernel/VM/AnonymousVMObject.h>
+#include <Kernel/VM/TypedMapping.h>
+
+namespace Kernel {
+
+MemoryDevice::MemoryDevice()
+    : CharacterDevice(1, 1)
+{
+}
+
+MemoryDevice::~MemoryDevice()
+{
+}
+
+KResultOr<size_t> MemoryDevice::read(FileDescription&, size_t, UserOrKernelBuffer&, size_t)
+{
+    TODO();
+}
+
+void MemoryDevice::did_seek(FileDescription&, off_t)
+{
+    TODO();
+}
+
+KResultOr<Region*> MemoryDevice::mmap(Process& process, FileDescription&, const Range& range, size_t offset, int prot, bool shared)
+{
+    auto viewed_address = PhysicalAddress(offset);
+
+    dbgln("MemoryDevice: Trying to mmap physical memory at {} for range of {} bytes", viewed_address, range.size());
+    if (!MM.is_allowed_to_mmap_to_userspace(viewed_address, range)) {
+        dbgln("MemoryDevice: Trying to mmap physical memory at {} for range of {} bytes failed due to violation of access", viewed_address, range.size());
+        return EINVAL;
+    }
+
+    auto vmobject = AnonymousVMObject::create_for_physical_range(viewed_address, range.size());
+    if (!vmobject)
+        return ENOMEM;
+    dbgln("MemoryDevice: Mapped physical memory at {} for range of {} bytes", viewed_address, range.size());
+    return process.allocate_region_with_vmobject(
+        range,
+        vmobject.release_nonnull(),
+        0,
+        "Mapped Physical Memory",
+        prot,
+        shared);
+}
+
+}