1/*
2 * Copyright (C) 2009 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include "config.h"
27#include "ExecutableAllocator.h"
28
29#include "JSCInlines.h"
30
31#if ENABLE(EXECUTABLE_ALLOCATOR_FIXED)
32
33#include "CodeProfiling.h"
34#include <errno.h>
35#include <unistd.h>
36#include <wtf/MetaAllocator.h>
37#include <wtf/PageReservation.h>
38#include <wtf/VMTags.h>
39
40#if OS(DARWIN)
41#include <sys/mman.h>
42#endif
43
44#if OS(LINUX)
45#include <stdio.h>
46#endif
47
48#if PLATFORM(MAC) && __MAC_OS_X_VERSION_MIN_REQUIRED < 1090
49// MADV_FREE_REUSABLE does not work for JIT memory on older OSes so use MADV_FREE in that case.
50#define WTF_USE_MADV_FREE_FOR_JIT_MEMORY 1
51#endif
52
53using namespace WTF;
54
55namespace JSC {
56
57uintptr_t startOfFixedExecutableMemoryPool;
58
59class FixedVMPoolExecutableAllocator : public MetaAllocator {
60    WTF_MAKE_FAST_ALLOCATED;
61public:
62    FixedVMPoolExecutableAllocator()
63        : MetaAllocator(jitAllocationGranule) // round up all allocations to 32 bytes
64    {
65        m_reservation = PageReservation::reserveWithGuardPages(fixedExecutableMemoryPoolSize, OSAllocator::JSJITCodePages, EXECUTABLE_POOL_WRITABLE, true);
66        if (m_reservation) {
67            ASSERT(m_reservation.size() == fixedExecutableMemoryPoolSize);
68            addFreshFreeSpace(m_reservation.base(), m_reservation.size());
69
70            startOfFixedExecutableMemoryPool = reinterpret_cast<uintptr_t>(m_reservation.base());
71        }
72    }
73
74    virtual ~FixedVMPoolExecutableAllocator();
75
76protected:
77    virtual void* allocateNewSpace(size_t&) override
78    {
79        // We're operating in a fixed pool, so new allocation is always prohibited.
80        return 0;
81    }
82
83    virtual void notifyNeedPage(void* page) override
84    {
85#if USE(MADV_FREE_FOR_JIT_MEMORY)
86        UNUSED_PARAM(page);
87#else
88        m_reservation.commit(page, pageSize());
89#endif
90    }
91
92    virtual void notifyPageIsFree(void* page) override
93    {
94#if USE(MADV_FREE_FOR_JIT_MEMORY)
95        for (;;) {
96            int result = madvise(page, pageSize(), MADV_FREE);
97            if (!result)
98                return;
99            ASSERT(result == -1);
100            if (errno != EAGAIN) {
101                RELEASE_ASSERT_NOT_REACHED(); // In debug mode, this should be a hard failure.
102                break; // In release mode, we should just ignore the error - not returning memory to the OS is better than crashing, especially since we _will_ be able to reuse the memory internally anyway.
103            }
104        }
105#else
106        m_reservation.decommit(page, pageSize());
107#endif
108    }
109
110private:
111    PageReservation m_reservation;
112};
113
114static FixedVMPoolExecutableAllocator* allocator;
115
116void ExecutableAllocator::initializeAllocator()
117{
118    ASSERT(!allocator);
119    allocator = new FixedVMPoolExecutableAllocator();
120    CodeProfiling::notifyAllocator(allocator);
121}
122
123ExecutableAllocator::ExecutableAllocator(VM&)
124{
125    ASSERT(allocator);
126}
127
128ExecutableAllocator::~ExecutableAllocator()
129{
130}
131
132FixedVMPoolExecutableAllocator::~FixedVMPoolExecutableAllocator()
133{
134    m_reservation.deallocate();
135}
136
137bool ExecutableAllocator::isValid() const
138{
139    return !!allocator->bytesReserved();
140}
141
142bool ExecutableAllocator::underMemoryPressure()
143{
144    MetaAllocator::Statistics statistics = allocator->currentStatistics();
145    return statistics.bytesAllocated > statistics.bytesReserved / 2;
146}
147
148double ExecutableAllocator::memoryPressureMultiplier(size_t addedMemoryUsage)
149{
150    MetaAllocator::Statistics statistics = allocator->currentStatistics();
151    ASSERT(statistics.bytesAllocated <= statistics.bytesReserved);
152    size_t bytesAllocated = statistics.bytesAllocated + addedMemoryUsage;
153    if (bytesAllocated >= statistics.bytesReserved)
154        bytesAllocated = statistics.bytesReserved;
155    double result = 1.0;
156    size_t divisor = statistics.bytesReserved - bytesAllocated;
157    if (divisor)
158        result = static_cast<double>(statistics.bytesReserved) / divisor;
159    if (result < 1.0)
160        result = 1.0;
161    return result;
162}
163
164PassRefPtr<ExecutableMemoryHandle> ExecutableAllocator::allocate(VM& vm, size_t sizeInBytes, void* ownerUID, JITCompilationEffort effort)
165{
166    RefPtr<ExecutableMemoryHandle> result = allocator->allocate(sizeInBytes, ownerUID);
167    if (!result) {
168        if (effort == JITCompilationCanFail)
169            return result;
170        releaseExecutableMemory(vm);
171        result = allocator->allocate(sizeInBytes, ownerUID);
172        RELEASE_ASSERT(result);
173    }
174    return result.release();
175}
176
177size_t ExecutableAllocator::committedByteCount()
178{
179    return allocator->bytesCommitted();
180}
181
182#if ENABLE(META_ALLOCATOR_PROFILE)
183void ExecutableAllocator::dumpProfile()
184{
185    allocator->dumpProfile();
186}
187#endif
188
189}
190
191
192#endif // ENABLE(EXECUTABLE_ALLOCATOR_FIXED)
193