webkitgtk-2.16.5HEADwebkitgtk-2.16.5master

1 files changed, 171 insertions, 0 deletions

diff --git a/Source/JavaScriptCore/wasm/WasmMemory.cpp b/Source/JavaScriptCore/wasm/WasmMemory.cpp
new file mode 100644
index 000000000..aad91c13e
--- /dev/null
+++ b/Source/JavaScriptCore/wasm/WasmMemory.cpp
@@ -0,0 +1,171 @@
+/*
+ * Copyright (C) 2016 Apple Inc. 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 APPLE INC. ``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 APPLE INC. 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 "config.h"
+#include "WasmMemory.h"
+
+#if ENABLE(WEBASSEMBLY)
+
+#include <wtf/HexNumber.h>
+#include <wtf/PrintStream.h>
+#include <wtf/text/WTFString.h>
+
+namespace JSC { namespace Wasm {
+
+namespace {
+const bool verbose = false;
+}
+
+void Memory::dump(PrintStream& out) const
+{
+    String memoryHex;
+    WTF::appendUnsigned64AsHex((uint64_t)(uintptr_t)m_memory, memoryHex);
+    out.print("Memory at 0x", memoryHex, ", size ", m_size, "B capacity ", m_mappedCapacity, "B, initial ", m_initial, " maximum ", m_maximum, " mode ", makeString(m_mode));
+}
+
+const char* Memory::makeString(Mode mode) const
+{
+    switch (mode) {
+    case Mode::BoundsChecking: return "BoundsChecking";
+    }
+    RELEASE_ASSERT_NOT_REACHED();
+    return "";
+}
+
+static_assert(sizeof(uint64_t) == sizeof(size_t), "We rely on allowing the maximum size of Memory we map to be 2^32 which is larger than fits in a 32-bit integer that we'd pass to mprotect if this didn't hold.");
+
+Memory::Memory(PageCount initial, PageCount maximum, bool& failed)
+    : m_size(initial.bytes())
+    , m_initial(initial)
+    , m_maximum(maximum)
+    , m_mode(Mode::BoundsChecking)
+    // FIXME: If we add signal based bounds checking then we need extra space for overflow on load.
+    // see: https://bugs.webkit.org/show_bug.cgi?id=162693
+{
+    RELEASE_ASSERT(!maximum || maximum >= initial); // This should be guaranteed by our caller.
+
+    m_mappedCapacity = maximum ? maximum.bytes() : PageCount::max().bytes();
+    if (!m_mappedCapacity) {
+        // This means we specified a zero as maximum (which means we also have zero as initial size).
+        RELEASE_ASSERT(m_size == 0);
+        m_memory = nullptr;
+        m_mappedCapacity = 0;
+        failed = false;
+        if (verbose)
+            dataLogLn("Memory::Memory allocating nothing ", *this);
+        return;
+    }
+
+    // FIXME: It would be nice if we had a VM tag for wasm memory. https://bugs.webkit.org/show_bug.cgi?id=163600
+    void* result = Options::simulateWebAssemblyLowMemory() ? MAP_FAILED : mmap(nullptr, m_mappedCapacity, PROT_NONE, MAP_PRIVATE | MAP_ANON, -1, 0);
+    if (result == MAP_FAILED) {
+        // Try again with a different number.
+        if (verbose)
+            dataLogLn("Memory::Memory mmap failed once for capacity, trying again", *this);
+        m_mappedCapacity = m_size;
+        if (!m_mappedCapacity) {
+            m_memory = nullptr;
+            failed = false;
+            if (verbose)
+                dataLogLn("Memory::Memory mmap not trying again because size is zero ", *this);
+            return;
+        }
+
+        result = mmap(nullptr, m_mappedCapacity, PROT_NONE, MAP_PRIVATE | MAP_ANON, -1, 0);
+        if (result == MAP_FAILED) {
+            if (verbose)
+                dataLogLn("Memory::Memory mmap failed twice ", *this);
+            failed = true;
+            return;
+        }
+    }
+
+    ASSERT(m_size <= m_mappedCapacity);
+    {
+        bool success = !mprotect(result, static_cast<size_t>(m_size), PROT_READ | PROT_WRITE);
+        RELEASE_ASSERT(success);
+    }
+
+    m_memory = result;
+    failed = false;
+    if (verbose)
+        dataLogLn("Memory::Memory mmap succeeded ", *this);
+}
+
+Memory::~Memory()
+{
+    if (verbose)
+        dataLogLn("Memory::~Memory ", *this);
+    if (m_memory) {
+        if (munmap(m_memory, m_mappedCapacity))
+            CRASH();
+    }
+}
+
+bool Memory::grow(PageCount newSize)
+{
+    RELEASE_ASSERT(newSize > PageCount::fromBytes(m_size));
+
+    if (verbose)
+        dataLogLn("Memory::grow to ", newSize, " from ", *this);
+
+    if (maximum() && newSize > maximum())
+        return false;
+
+    uint64_t desiredSize = newSize.bytes();
+
+    if (m_memory && desiredSize <= m_mappedCapacity) {
+        bool success = !mprotect(static_cast<uint8_t*>(m_memory) + m_size, static_cast<size_t>(desiredSize - m_size), PROT_READ | PROT_WRITE);
+        RELEASE_ASSERT(success);
+        m_size = desiredSize;
+        if (verbose)
+            dataLogLn("Memory::grow in-place ", *this);
+        return true;
+    }
+
+    // Otherwise, let's try to make some new memory.
+    void* newMemory = mmap(nullptr, desiredSize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0);
+    if (newMemory == MAP_FAILED)
+        return false;
+
+    if (m_memory) {
+        memcpy(newMemory, m_memory, m_size);
+        bool success = !munmap(m_memory, m_mappedCapacity);
+        RELEASE_ASSERT(success);
+    }
+    m_memory = newMemory;
+    m_mappedCapacity = desiredSize;
+    m_size = desiredSize;
+
+    if (verbose)
+        dataLogLn("Memory::grow ", *this);
+    return true;
+}
+
+} // namespace JSC
+
+} // namespace Wasm
+
+#endif // ENABLE(WEBASSEMBLY)