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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ *
+ * Copyright (C) 2008 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.
+ */
+
+#ifndef jit_ExecutableAllocator_h
+#define jit_ExecutableAllocator_h
+
+#include "mozilla/EnumeratedArray.h"
+
+#include <limits>
+#include <stddef.h> // for ptrdiff_t
+
+#include "jit/ProcessExecutableMemory.h"
+#include "js/AllocPolicy.h"
+#include "js/HashTable.h"
+#include "js/TypeDecls.h"
+#include "js/Vector.h"
+
+namespace JS {
+struct CodeSizes;
+} // namespace JS
+
+namespace js {
+namespace jit {
+
+enum class CodeKind : uint8_t { Ion, Baseline, RegExp, Other, Count };
+
+class ExecutableAllocator;
+
+// These are reference-counted. A new one starts with a count of 1.
+class ExecutablePool {
+ friend class ExecutableAllocator;
+
+ private:
+ struct Allocation {
+ char* pages;
+ size_t size;
+ };
+
+ ExecutableAllocator* m_allocator;
+ char* m_freePtr;
+ char* m_end;
+ Allocation m_allocation;
+
+ // Reference count for automatic reclamation.
+ unsigned m_refCount : 31;
+
+ // Flag that can be used by algorithms operating on pools.
+ bool m_mark : 1;
+
+ // Number of bytes currently allocated for each CodeKind.
+ mozilla::EnumeratedArray<CodeKind, CodeKind::Count, size_t> m_codeBytes;
+
+ public:
+ void release(bool willDestroy = false);
+ void release(size_t n, CodeKind kind);
+
+ void addRef();
+
+ ExecutablePool(ExecutableAllocator* allocator, Allocation a)
+ : m_allocator(allocator),
+ m_freePtr(a.pages),
+ m_end(m_freePtr + a.size),
+ m_allocation(a),
+ m_refCount(1),
+ m_mark(false) {
+ for (size_t& count : m_codeBytes) {
+ count = 0;
+ }
+ }
+
+ ~ExecutablePool();
+
+ void mark() {
+ MOZ_ASSERT(!m_mark);
+ m_mark = true;
+ }
+ void unmark() {
+ MOZ_ASSERT(m_mark);
+ m_mark = false;
+ }
+ bool isMarked() const { return m_mark; }
+
+ private:
+ ExecutablePool(const ExecutablePool&) = delete;
+ void operator=(const ExecutablePool&) = delete;
+
+ void* alloc(size_t n, CodeKind kind);
+
+ size_t available() const;
+
+ // Returns the number of bytes that are currently in use (referenced by
+ // live JitCode objects).
+ size_t usedCodeBytes() const {
+ size_t res = 0;
+ for (size_t count : m_codeBytes) {
+ res += count;
+ }
+ return res;
+ }
+};
+
+struct JitPoisonRange {
+ jit::ExecutablePool* pool;
+ void* start;
+ size_t size;
+
+ JitPoisonRange(jit::ExecutablePool* pool, void* start, size_t size)
+ : pool(pool), start(start), size(size) {}
+};
+
+typedef Vector<JitPoisonRange, 0, SystemAllocPolicy> JitPoisonRangeVector;
+
+class ExecutableAllocator {
+ public:
+ ExecutableAllocator() = default;
+ ~ExecutableAllocator();
+
+ void purge();
+
+ // alloc() returns a pointer to some memory, and also (by reference) a
+ // pointer to reference-counted pool. The caller owns a reference to the
+ // pool; i.e. alloc() increments the count before returning the object.
+ void* alloc(JSContext* cx, size_t n, ExecutablePool** poolp, CodeKind type);
+
+ void releasePoolPages(ExecutablePool* pool);
+
+ void addSizeOfCode(JS::CodeSizes* sizes) const;
+
+ private:
+ static const size_t OVERSIZE_ALLOCATION = size_t(-1);
+
+ static size_t roundUpAllocationSize(size_t request, size_t granularity);
+
+ // On OOM, this will return an Allocation where pages is nullptr.
+ ExecutablePool::Allocation systemAlloc(size_t n);
+ static void systemRelease(const ExecutablePool::Allocation& alloc);
+
+ ExecutablePool* createPool(size_t n);
+ ExecutablePool* poolForSize(size_t n);
+
+ static void reprotectPool(JSRuntime* rt, ExecutablePool* pool,
+ ProtectionSetting protection,
+ MustFlushICache flushICache);
+
+ public:
+ [[nodiscard]] static bool makeWritable(void* start, size_t size) {
+ return ReprotectRegion(start, size, ProtectionSetting::Writable,
+ MustFlushICache::No);
+ }
+
+ [[nodiscard]] static bool makeExecutableAndFlushICache(void* start,
+ size_t size) {
+ return ReprotectRegion(start, size, ProtectionSetting::Executable,
+ MustFlushICache::Yes);
+ }
+
+ static void poisonCode(JSRuntime* rt, JitPoisonRangeVector& ranges);
+
+ private:
+ ExecutableAllocator(const ExecutableAllocator&) = delete;
+ void operator=(const ExecutableAllocator&) = delete;
+
+ // These are strong references; they keep pools alive.
+ static const size_t maxSmallPools = 4;
+ typedef js::Vector<ExecutablePool*, maxSmallPools, js::SystemAllocPolicy>
+ SmallExecPoolVector;
+ SmallExecPoolVector m_smallPools;
+
+ // All live pools are recorded here, just for stats purposes. These are
+ // weak references; they don't keep pools alive. When a pool is destroyed
+ // its reference is removed from m_pools.
+ typedef js::HashSet<ExecutablePool*, js::DefaultHasher<ExecutablePool*>,
+ js::SystemAllocPolicy>
+ ExecPoolHashSet;
+ ExecPoolHashSet m_pools; // All pools, just for stats purposes.
+};
+
+} // namespace jit
+} // namespace js
+
+#endif /* jit_ExecutableAllocator_h */