UserspaceEmulator: Add support for shared buffers (shbuf)

We track these separately from regular mmap() regions, as they have
slightly different behaviors.

DevTools/UserspaceEmulator/SharedBufferRegion.cpp

@@ -0,0 +1,112 @@
+/*
+ * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * 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 "SharedBufferRegion.h"
+#include "Emulator.h"
+#include <Kernel/API/Syscall.h>
+#include <serenity.h>
+#include <sys/mman.h>
+
+namespace UserspaceEmulator {
+
+NonnullOwnPtr<SharedBufferRegion> SharedBufferRegion::create_with_shbuf_id(u32 base, u32 size, int shbuf_id, u8* host_data)
+{
+    return adopt_own(*new SharedBufferRegion(base, size, shbuf_id, host_data));
+}
+
+SharedBufferRegion::SharedBufferRegion(u32 base, u32 size, int shbuf_id, u8* host_data)
+    : Region(base, size)
+    , m_data(host_data)
+    , m_shbuf_id(shbuf_id)
+{
+}
+
+SharedBufferRegion::~SharedBufferRegion()
+{
+}
+
+u8 SharedBufferRegion::read8(FlatPtr offset)
+{
+    ASSERT(offset < size());
+    return *reinterpret_cast<const u8*>(m_data + offset);
+}
+
+u16 SharedBufferRegion::read16(u32 offset)
+{
+    ASSERT(offset + 1 < size());
+    return *reinterpret_cast<const u16*>(m_data + offset);
+}
+
+u32 SharedBufferRegion::read32(u32 offset)
+{
+    ASSERT(offset + 3 < size());
+    return *reinterpret_cast<const u32*>(m_data + offset);
+}
+
+void SharedBufferRegion::write8(u32 offset, u8 value)
+{
+    ASSERT(offset < size());
+    *reinterpret_cast<u8*>(m_data + offset) = value;
+}
+
+void SharedBufferRegion::write16(u32 offset, u16 value)
+{
+    ASSERT(offset + 1 < size());
+    *reinterpret_cast<u16*>(m_data + offset) = value;
+}
+
+void SharedBufferRegion::write32(u32 offset, u32 value)
+{
+    ASSERT(offset + 3 < size());
+    *reinterpret_cast<u32*>(m_data + offset) = value;
+}
+
+int SharedBufferRegion::allow_all()
+{
+    return syscall(SC_shbuf_allow_all, m_shbuf_id);
+}
+
+int SharedBufferRegion::allow_pid(pid_t pid)
+{
+    return syscall(SC_shbuf_allow_pid, m_shbuf_id, pid);
+}
+
+int SharedBufferRegion::seal()
+{
+    return syscall(SC_shbuf_seal, m_shbuf_id);
+}
+
+int SharedBufferRegion::release()
+{
+    return syscall(SC_shbuf_release, m_shbuf_id);
+}
+
+int SharedBufferRegion::set_volatile(bool is_volatile)
+{
+    return syscall(SC_shbuf_set_volatile, m_shbuf_id, is_volatile);
+}
+
+}